Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE PAGES

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli; ...

2018-04-23

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well withmore » other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Interagency comparison of iodometric methods for ozone determination

NASA Technical Reports Server (NTRS)

Demore, W. B.; Romanovsky, J. C.; Feldstein, M.; Mueller, P. K.; Hamming, W. J.

1976-01-01

The California Air Resources Board appointed an Oxidant Calibration Committee for the purpose of evaluating the accuracy of the different agency calibration procedures. The committee chose UV absorption photometry as the reference method for ozone measurement. Interagency comparisons of the various iodometric methods were conducted relative to the ultraviolet standard. The tests included versions of the iodometric methods as employed by the Air Resources Board, the Los Angeles Air Pollution Control District, and the EPA. An alternative candidate reference method for ozone measurement, gas phase titration, was also included in the test series.

A Comparison of Methods for Detecting Differential Distractor Functioning

ERIC Educational Resources Information Center

Koon, Sharon

2010-01-01

This study examined the effectiveness of the odds-ratio method (Penfield, 2008) and the multinomial logistic regression method (Kato, Moen, & Thurlow, 2009) for measuring differential distractor functioning (DDF) effects in comparison to the standardized distractor analysis approach (Schmitt & Bleistein, 1987). Students classified as participating…

Comparison of measurement methods with a mixed effects procedure accounting for replicated evaluations (COM3PARE): method comparison algorithm implementation for head and neck IGRT positional verification.

PubMed

Roy, Anuradha; Fuller, Clifton D; Rosenthal, David I; Thomas, Charles R

2015-08-28

Comparison of imaging measurement devices in the absence of a gold-standard comparator remains a vexing problem; especially in scenarios where multiple, non-paired, replicated measurements occur, as in image-guided radiotherapy (IGRT). As the number of commercially available IGRT presents a challenge to determine whether different IGRT methods may be used interchangeably, an unmet need conceptually parsimonious and statistically robust method to evaluate the agreement between two methods with replicated observations. Consequently, we sought to determine, using an previously reported head and neck positional verification dataset, the feasibility and utility of a Comparison of Measurement Methods with the Mixed Effects Procedure Accounting for Replicated Evaluations (COM3PARE), a unified conceptual schema and analytic algorithm based upon Roy's linear mixed effects (LME) model with Kronecker product covariance structure in a doubly multivariate set-up, for IGRT method comparison. An anonymized dataset consisting of 100 paired coordinate (X/ measurements from a sequential series of head and neck cancer patients imaged near-simultaneously with cone beam CT (CBCT) and kilovoltage X-ray (KVX) imaging was used for model implementation. Software-suggested CBCT and KVX shifts for the lateral (X), vertical (Y) and longitudinal (Z) dimensions were evaluated for bias, inter-method (between-subject variation), intra-method (within-subject variation), and overall agreement using with a script implementing COM3PARE with the MIXED procedure of the statistical software package SAS (SAS Institute, Cary, NC, USA). COM3PARE showed statistically significant bias agreement and difference in inter-method between CBCT and KVX was observed in the Z-axis (both p - value<0.01). Intra-method and overall agreement differences were noted as statistically significant for both the X- and Z-axes (all p - value<0.01). Using pre-specified criteria, based on intra-method agreement, CBCT was deemed preferable for X-axis positional verification, with KVX preferred for superoinferior alignment. The COM3PARE methodology was validated as feasible and useful in this pilot head and neck cancer positional verification dataset. COM3PARE represents a flexible and robust standardized analytic methodology for IGRT comparison. The implemented SAS script is included to encourage other groups to implement COM3PARE in other anatomic sites or IGRT platforms.

Comparison of Motion Blur Measurement Methods

NASA Technical Reports Server (NTRS)

Watson, Andrew B.

2008-01-01

Motion blur is a significant display property for which accurate, valid measurement methods are needed. Recent measurements of a set of eight displays by a set of six measurement devices provide an opportunity to evaluate techniques of measurement and of the analysis of those measurements.

A semi-automatic method for positioning a femoral bone reconstruction for strict view generation.

PubMed

Milano, Federico; Ritacco, Lucas; Gomez, Adrian; Gonzalez Bernaldo de Quiros, Fernan; Risk, Marcelo

2010-01-01

In this paper we present a semi-automatic method for femoral bone positioning after 3D image reconstruction from Computed Tomography images. This serves as grounding for the definition of strict axial, longitudinal and anterior-posterior views, overcoming the problem of patient positioning biases in 2D femoral bone measuring methods. After the bone reconstruction is aligned to a standard reference frame, new tomographic slices can be generated, on which unbiased measures may be taken. This could allow not only accurate inter-patient comparisons but also intra-patient comparisons, i.e., comparisons of images of the same patient taken at different times. This method could enable medical doctors to diagnose and follow up several bone deformities more easily.

Quantification of Ice Accretions for Icing Scaling Evaluations

NASA Technical Reports Server (NTRS)

Ruff, Gary A.; Anderson, David N.

2003-01-01

The comparison of ice accretion characteristics is an integral part of aircraft icing research. It is often necessary to compare an ice accretion obtained from a flight test or numerical simulation to one produced in an icing wind tunnel or for validation of an icing scaling method. Traditionally, this has been accomplished by overlaying two-dimensional tracings of ice accretion shapes. This paper addresses the basic question of how to compare ice accretions using more quantitative methods. For simplicity, geometric characteristics of the ice accretions are used for the comparison. One method evaluated is a direct comparison of the percent differences of the geometric measurements. The second method inputs these measurements into a fuzzy inference system to obtain a single measure of the goodness of the comparison. The procedures are demonstrated by comparing ice shapes obtained in the Icing Research Tunnel at NASA Glenn Research Center during recent icing scaling tests. The results demonstrate that this type of analysis is useful in quantifying the similarity of ice accretion shapes and that the procedures should be further developed by expanding the analysis to additional icing data sets.

A Comparison of Signal Enhancement Methods for Extracting Tonal Acoustic Signals

NASA Technical Reports Server (NTRS)

Jones, Michael G.

1998-01-01

The measurement of pure tone acoustic pressure signals in the presence of masking noise, often generated by mean flow, is a continual problem in the field of passive liner duct acoustics research. In support of the Advanced Subsonic Technology Noise Reduction Program, methods were investigated for conducting measurements of advanced duct liner concepts in harsh, aeroacoustic environments. This report presents the results of a comparison study of three signal extraction methods for acquiring quality acoustic pressure measurements in the presence of broadband noise (used to simulate the effects of mean flow). The performance of each method was compared to a baseline measurement of a pure tone acoustic pressure 3 dB above a uniform, broadband noise background.

Comparison of Psychophysiological and Dual-Task Measures of Listening Effort

ERIC Educational Resources Information Center

Seeman, Scott; Sims, Rebecca

2015-01-01

Purpose: We wished to make a comparison of psychophysiological measures of listening effort with subjective and dual-task measures of listening effort for a diotic-dichotic-digits and a sentences-in-noise task. Method: Three groups of young adults (18-38 years old) with normal hearing participated in three experiments: two psychophysiological…

Comparison of measurement methods for capacitive tactile sensors and their implementation

NASA Astrophysics Data System (ADS)

Tarapata, Grzegorz; Sienkiewicz, Rafał

2015-09-01

This paper presents a review of ideas and implementations of measurement methods utilized for capacity measurements in tactile sensors. The paper describes technical method, charge amplification method, generation and as well integration method. Three selected methods were implemented in dedicated measurement system and utilised for capacitance measurements of ourselves made tactile sensors. The tactile sensors tested in this work were fully fabricated with the inkjet printing technology. The tests result were presented and summarised. The charge amplification method (CDC) was selected as the best method for the measurement of the tactile sensors.

Quantitative comparison of in situ soil CO2 flux measurement methods

Treesearch

Jennifer D. Knoepp; James M. Vose

2002-01-01

Development of reliable regional or global carbon budgets requires accurate measurement of soil CO2 flux. We conducted laboratory and field studies to determine the accuracy and comparability of methods commonly used to measure in situ soil CO2 fluxes. Methods compared included CO2...

Indirect scaling methods for testing quantitative emotion theories.

PubMed

Junge, Martin; Reisenzein, Rainer

2013-01-01

Two studies investigated the utility of indirect scaling methods, based on graded pair comparisons, for the testing of quantitative emotion theories. In Study 1, we measured the intensity of relief and disappointment caused by lottery outcomes, and in Study 2, the intensity of disgust evoked by pictures, using both direct intensity ratings and graded pair comparisons. The stimuli were systematically constructed to reflect variables expected to influence the intensity of the emotions according to theoretical models of relief/disappointment and disgust, respectively. Two probabilistic scaling methods were used to estimate scale values from the pair comparison judgements: Additive functional measurement (AFM) and maximum likelihood difference scaling (MLDS). The emotion models were fitted to the direct and indirect intensity measurements using nonlinear regression (Study 1) and analysis of variance (Study 2). Both studies found substantially improved fits of the emotion models for the indirectly determined emotion intensities, with their advantage being evident particularly at the level of individual participants. The results suggest that indirect scaling methods yield more precise measurements of emotion intensity than rating scales and thereby provide stronger tests of emotion theories in general and quantitative emotion theories in particular.

Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements

NASA Astrophysics Data System (ADS)

Ježek, I.; Drinovec, L.; Ferrero, L.; Carriero, M.; Močnik, G.

2015-01-01

We have used two methods for measuring emission factors (EFs) in real driving conditions on five cars in a controlled environment: the stationary method, where the investigated vehicle drives by the stationary measurement platform and the composition of the plume is measured, and the chasing method, where a mobile measurement platform drives behind the investigated vehicle. We measured EFs of black carbon and particle number concentration. The stationary method was tested for repeatability at different speeds and on a slope. The chasing method was tested on a test track and compared to the portable emission measurement system. We further developed the data processing algorithm for both methods, trying to improve consistency, determine the plume duration, limit the background influence and facilitate automatic processing of measurements. The comparison of emission factors determined by the two methods showed good agreement. EFs of a single car measured with either method have a specific distribution with a characteristic value and a long tail of super emissions. Measuring EFs at different speeds or slopes did not significantly influence the EFs of different cars; hence, we propose a new description of vehicle emissions that is not related to kinematic or engine parameters, and we rather describe the vehicle EF with a characteristic value and a super emission tail.

Final report of the SIM.QM-S8 supplementary comparison, trace metals in drinking water

NASA Astrophysics Data System (ADS)

Yang, Lu; Nadeau, Kenny; Gedara Pihillagawa, Indu; Meija, Juris; Mester, Zoltan; Napoli, Romina; Pérez Zambra, Ramiro; Ferreira, Elizabeth; Alejandro Ahumada Forigua, Diego; Abella Gamba, Johanna Paola

2018-01-01

After completing a supplementary comparison SIM.QM-S7, the National Metrology Institute of Colombia (NMIC) requested to National Research Council of Canada (NRC) a subsequent bilateral comparison, because INMC considered that its results in SIM.QM-S7 unrepresentative of its standards. In this context, NRC agreed to coordinate this bilateral comparison with the aim of demonstrating the measurement capabilities of trace elements in fresh water. Participants included NMIC and LATU. No measurement method was prescribed by the coordinating laboratory. Therefore, NMIs used measurement methods of their choice. However, the majority of NMIs/DIs used ICP-MS. This SIM.QM-S8 Supplementary Comparison provides NMIs with the needed evidence for CMC claims for trace elements in fresh waters and similar matrices. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Experimental comparison and validation of hot-ball method with guarded hot plate method on polyurethane foams

NASA Astrophysics Data System (ADS)

Hudec, Ján; Glorieux, Christ; Dieška, Peter; Kubičár, Ľudovít

2016-07-01

The Hot-ball method is an innovative transient method for measuring thermophysical properties. The principle is based on heating of a small ball, incorporated in measured medium, by constant heating power and simultaneous measuring of the ball's temperature response since the heating was initiated. The shape of the temperature response depends on thermophysical properties of the medium, where the sensor is placed. This method is patented by Institute of Physics, SAS, where the method and sensors based on this method are being developed. At the beginning of the development of sensors for this method we were oriented on monitoring applications, where relative precision is much more important than accuracy. Meanwhile, the quality of sensors was improved good enough to be used for a new application - absolute measuring of thermophysical parameters of low thermally conductive materials. This paper describes experimental verification and validation of measurement by hot-ball method. Thanks to cooperation with Laboratory of Soft Matter and Biophysics of Catholic University of Leuven in Belgium, established Guarded Hot Plate method was used as a reference. Details about measuring setups, description of the experiments and results of the comparison are presented.

Measuring Cognitive Load: A Comparison of Self-Report and Physiological Methods

ERIC Educational Resources Information Center

Joseph, Stacey

2013-01-01

This study explored three methods to measure cognitive load in a learning environment using four logic puzzles that systematically varied in level of intrinsic cognitive load. Participants' perceived intrinsic load was simultaneously measured with a self-report measure-a traditional subjective measure-and two objective, physiological measures…

Retooling Predictive Relations for non-volatile PM by Comparison to Measurements

NASA Astrophysics Data System (ADS)

Vander Wal, R. L.; Abrahamson, J. P.

2015-12-01

Non-volatile particulate matter (nvPM) emissions from jet aircraft at cruise altitude are of particular interest for climate and atmospheric processes but are difficult to measure and are normally approximated. To provide such inventory estimates the present approach is to use measured, ground-based values with scaling to cruise (engine operating) conditions. Several points are raised by this approach. First is what ground based values to use. Empirical and semi-empirical approaches, such as the revised first order approximation (FOA3) and formation-oxidation (FOX) methods, each with embedded assumptions are available to calculate a ground-based black carbon concentration, CBC. Second is the scaling relation that can depend upon the ratios of fuel-air equivalence, pressure, and combustor flame temperature. We are using measured ground-based values to evaluate the accuracy of present methods towards developing alternative methods for CBCby smoke number or via a semi-empirical kinetic method for the specific engine, CFM56-2C, representative of a rich-dome style combustor, and as one of the most prevalent engine families in commercial use. Applying scaling relations to measured ground based values and comparison to measurements at cruise evaluates the accuracy of current scaling formalism. In partnership with GE Aviation, performing engine cycle deck calculations enables critical comparison between estimated or predicted thermodynamic parameters and true (engine) operational values for the CFM56-2C engine. Such specific comparisons allow tracing differences between predictive estimates for, and measurements of nvPM to their origin - as either divergence of input parameters or in the functional form of the predictive relations. Such insights will lead to development of new predictive tools for jet aircraft nvPM emissions. Such validated relations can then be extended to alternative fuels with confidence in operational thermodynamic values and functional form. Comparisons will then be made between these new predictive relationships and measurements of nvPM from alternative fuels using ground and cruise data - as collected during NASA-led AAFEX and ACCESS field campaigns, respectively.

The Relative Importance of Job Factors: A New Measurement Approach.

ERIC Educational Resources Information Center

Nealey, Stanley M.

This paper reports on a new two-phase measurement technique that permits a direct comparison of the perceived relative importance of economic vs. non-economic factors in a job situation in accounting for personnel retention, the willingness to produce, and job satisfaction. The paired comparison method was used to measure the preferences of 91…

Use of petroleum-based correlations and estimation methods for synthetic fuels

NASA Technical Reports Server (NTRS)

Antoine, A. C.

1980-01-01

Correlations of hydrogen content with aromatics content, heat of combustion, and smoke point are derived for some synthetic fuels prepared from oil and coal syncrudes. Comparing the results of the aromatics content with correlations derived for petroleum fuels shows that the shale-derived fuels fit the petroleum-based correlations, but the coal-derived fuels do not. The correlations derived for heat of combustion and smoke point are comparable to some found for petroleum-based correlations. Calculated values of hydrogen content and of heat of combustion are obtained for the synthetic fuels by use of ASTM estimation methods. Comparisons of the measured and calculated values show biases in the equations that exceed the critical statistics values. Comparison of the measured hydrogen content by the standard ASTM combustion method with that by a nuclear magnetic resonance (NMR) method shows a decided bias. The comparison of the calculated and measured NMR hydrogen contents shows a difference similar to that found with petroleum fuels.

Results of the CCRI(II)-S12.H-3 supplementary comparison: Comparison of methods for the calculation of the activity and standard uncertainty of a tritiated-water source measured using the LSC-TDCR method.

PubMed

Cassette, Philippe; Altzitzoglou, Timotheos; Antohe, Andrei; Rossi, Mario; Arinc, Arzu; Capogni, Marco; Galea, Raphael; Gudelis, Arunas; Kossert, Karsten; Lee, K B; Liang, Juncheng; Nedjadi, Youcef; Oropesa Verdecia, Pilar; Shilnikova, Tanya; van Wyngaardt, Winifred; Ziemek, Tomasz; Zimmerman, Brian

2018-04-01

A comparison of calculations of the activity of a 3 H 2 O liquid scintillation source using the same experimental data set collected at the LNE-LNHB with a triple-to-double coincidence ratio (TDCR) counter was completed. A total of 17 laboratories calculated the activity and standard uncertainty of the LS source using the files with experimental data provided by the LNE-LNHB. The results as well as relevant information on the computation techniques are presented and analysed in this paper. All results are compatible, even if there is a significant dispersion between the reported uncertainties. An output of this comparison is the estimation of the dispersion of TDCR measurement results when measurement conditions are well defined. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter-laboratory comparisons of hexenuronic acid measurements in kraft eucalyptus pulps using a UV-Vis spectroscopic method

Treesearch

J.Y. Zhu; H.F Zhou; Chai X.S.; Donna Johannes; Richard Pope; Cristina Valls; M. Blanca Roncero

2014-01-01

An inter-laboratory comparison of a UV-Vis spectroscopic method (TAPPI T 282 om-13 “Hexeneuronic acid content of chemical pulp”) for hexeneuronic acid measurements was conducted using three eucalyptus kraft pulps. The pulp samples were produced in a laboratory at kappa numbers of approximately 14, 20, and 35. The hexeneuronic acid contents of the three pulps were...

WTA estimates using the method of paired comparison: tests of robustness

Treesearch

Patricia A. Champ; John B. Loomis

1998-01-01

The method of paired comparison is modified to allow choices between two alternative gains so as to estimate willingness to accept (WTA) without loss aversion. The robustness of WTA values for two public goods is tested with respect to sensitivity of theWTA measure to the context of the bundle of goods used in the paired comparison exercise and to the scope (scale) of...

Solar radiation over Egypt: Comparison of predicted and measured meteorological data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamel, M.A.; Shalaby, S.A.; Mostafa, S.S.

1993-06-01

Measurements of global solar irradiance on a horizontal surface at five meteorological stations in Egypt for three years 1987, 1988, and 1989 are compared with their corresponding values computed by two independent methods. The first method is based on the Angstrom formula, which correlates relative solar irradiance H/H[sub o] to corresponding relative duration of bright sunshine n/N. Regional regression coefficients are obtained and used for prediction of global solar irradiance. Good agreement with measurements is obtained. In the second method an empirical relation, in which sunshine duration and the noon altitude of the sun as inputs together with appropriate choicemore » of zone parameters, is employed. This gives good agreement with the measurements. Comparison shows that the first method gives better fitting with the experimental data.« less

AGREEMENT AND COVERAGE OF INDICATORS OF RESPONSE TO INTERVENTION: A MULTI-METHOD COMPARISON AND SIMULATION

PubMed Central

Fletcher, Jack M.; Stuebing, Karla K.; Barth, Amy E.; Miciak, Jeremy; Francis, David J.; Denton, Carolyn A.

2013-01-01

Purpose Agreement across methods for identifying students as inadequate responders or as learning disabled is often poor. We report (1) an empirical examination of final status (post-intervention benchmarks) and dual-discrepancy growth methods based on growth during the intervention and final status for assessing response to intervention; and (2) a statistical simulation of psychometric issues that may explain low agreement. Methods After a Tier 2 intervention, final status benchmark criteria were used to identify 104 inadequate and 85 adequate responders to intervention, with comparisons of agreement and coverage for these methods and a dual-discrepancy method. Factors affecting agreement were investigated using computer simulation to manipulate reliability, the intercorrelation between measures, cut points, normative samples, and sample size. Results Identification of inadequate responders based on individual measures showed that single measures tended not to identify many members of the pool of 104 inadequate responders. Poor to fair levels of agreement for identifying inadequate responders were apparent between pairs of measures In the simulation, comparisons across two simulated measures generated indices of agreement (kappa) that were generally low because of multiple psychometric issues inherent in any test. Conclusions Expecting excellent agreement between two correlated tests with even small amounts of unreliability may not be realistic. Assessing outcomes based on multiple measures, such as level of CBM performance and short norm-referenced assessments of fluency may improve the reliability of diagnostic decisions. PMID:25364090

[Comparisons of manual and automatic refractometry with subjective results].

PubMed

Wübbolt, I S; von Alven, S; Hülssner, O; Erb, C

2006-11-01

Refractometry is very important in everyday clinical practice. The aim of this study is to compare the precision of three objective methods of refractometry with subjective dioptometry (Phoropter). The objective methods with the smallest deviation to subjective refractometry results are evaluated. The objective methods/instruments used were retinoscopy, Prism Refractometer PR 60 (Rodenstock) and Auto Refractometer RM-A 7000 (Topcon). The results of monocular dioptometry (sphere, cylinder and axis) of each objective method were compared to the results of the subjective method. The examination was carried out on 178 eyes, which were divided into 3 age-related groups: 6 - 12 years (103 eyes), 13 - 18 years (38 eyes) and older than 18 years (37 eyes). All measurements were made in cycloplegia. The smallest standard deviation of the measurement error was found for the Auto Refractometer RM-A 7000. Both the PR 60 and retinoscopy had a clearly higher standard deviation. Furthermore, the RM-A 7000 showed in three and retinoscopy in four of the nine comparisons a significant bias in the measurement error. The Auto Refractometer provides measurements with the smallest deviation compared to the subjective method. Here it has to be taken into account that the measurements for the sphere have an average deviation of + 0.2 dpt. In comparison to retinoscopy the examination of children with the RM-A 7000 is difficult. An advantage of the Auto Refractometer is the fast and easy handling, so that measurements can be performed by medical staff.

KEY COMPARISON: Final report of International Comparison EUROMET.QM-K1c: Comparison of measurements of nitrogen monoxide in nitrogen

NASA Astrophysics Data System (ADS)

van der Veen, A. M. H.; Nieuwenkamp, G.; Oudwater, R.; Wessel, R. M.; Novak, J.; Perrochet, J.-F.; Ackermann, A.; Rakowska, A.; Cortez, L.; Dias, F.; Konopelko, L.; Kustikov, Y.; Sutour, C.; Masé, T.; Milton, M. J. T.; Uprichard, I. J.; Woods, P. T.; Walden, J.; Lopez Esteban, M. T.

2005-01-01

Following-up the key comparison CCQM-K1c, EUROMET organized a regional key comparison involving ten laboratories. The objectives of this EUROMET key comparison were essentially the same as for the CCQM-K1c comparison: to compare the measurement capabilities of national metrological institutes (NMIs) in measuring amount of substance fractions of nitrogen monoxide in nitrogen. The nominal amount of substance fraction of the standards used for the comparison was 100 µmol/mol. The pilot laboratory in this key comparison also piloted the CCQM key comparison and has long-term experience in the behaviour of these mixtures and the technical challenges in preparing batches of very similar mixtures. Most participants used chemiluminescence as the measurement method; two participants used UV techniques and one ND-IR. The degrees of equivalence between this comparison and CCQM-K1c were calculated; four laboratories participated in both key comparisons, thus providing sufficient data for demonstrating the comparability. Main text. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the Mutual Recognition Arrangement (MRA).

High-resolution frequency measurement method with a wide-frequency range based on a quantized phase step law.

PubMed

Du, Baoqiang; Dong, Shaofeng; Wang, Yanfeng; Guo, Shuting; Cao, Lingzhi; Zhou, Wei; Zuo, Yandi; Liu, Dan

2013-11-01

A wide-frequency and high-resolution frequency measurement method based on the quantized phase step law is presented in this paper. Utilizing a variation law of the phase differences, the direct different frequency phase processing, and the phase group synchronization phenomenon, combining an A/D converter and the adaptive phase shifting principle, a counter gate is established in the phase coincidences at one-group intervals, which eliminates the ±1 counter error in the traditional frequency measurement method. More importantly, the direct phase comparison, the measurement, and the control between any periodic signals have been realized without frequency normalization in this method. Experimental results show that sub-picosecond resolution can be easily obtained in the frequency measurement, the frequency standard comparison, and the phase-locked control based on the phase quantization processing technique. The method may be widely used in navigation positioning, space techniques, communication, radar, astronomy, atomic frequency standards, and other high-tech fields.

Identification of common coexpression modules based on quantitative network comparison.

PubMed

Jo, Yousang; Kim, Sanghyeon; Lee, Doheon

2018-06-13

Finding common molecular interactions from different samples is essential work to understanding diseases and other biological processes. Coexpression networks and their modules directly reflect sample-specific interactions among genes. Therefore, identification of common coexpression network or modules may reveal the molecular mechanism of complex disease or the relationship between biological processes. However, there has been no quantitative network comparison method for coexpression networks and we examined previous methods for other networks that cannot be applied to coexpression network. Therefore, we aimed to propose quantitative comparison methods for coexpression networks and to find common biological mechanisms between Huntington's disease and brain aging by the new method. We proposed two similarity measures for quantitative comparison of coexpression networks. Then, we performed experiments using known coexpression networks. We showed the validity of two measures and evaluated threshold values for similar coexpression network pairs from experiments. Using these similarity measures and thresholds, we quantitatively measured the similarity between disease-specific and aging-related coexpression modules and found similar Huntington's disease-aging coexpression module pairs. We identified similar Huntington's disease-aging coexpression module pairs and found that these modules are related to brain development, cell death, and immune response. It suggests that up-regulated cell signalling related cell death and immune/ inflammation response may be the common molecular mechanisms in the pathophysiology of HD and normal brain aging in the frontal cortex.

A candidate reference method for serum potassium measurement by inductively coupled plasma mass spectrometry.

PubMed

Yan, Ying; Han, Bingqing; Zeng, Jie; Zhou, Weiyan; Zhang, Tianjiao; Zhang, Jiangtao; Chen, Wenxiang; Zhang, Chuanbao

2017-08-28

Potassium is an important serum ion that is frequently assayed in clinical laboratories. Quality assurance requires reference methods; thus, the establishment of a candidate reference method for serum potassium measurements is important. An inductively coupled plasma mass spectrometry (ICP-MS) method was developed. Serum samples were gravimetrically spiked with an aluminum internal standard, digested with 69% ultrapure nitric acid, and diluted to the required concentration. The 39K/27Al ratios were measured by ICP-MS in hydrogen mode. The method was calibrated using 5% nitric acid matrix calibrators, and the calibration function was established using the bracketing method. The correlation coefficients between the measured 39K/27Al ratios and the analyte concentration ratios were >0.9999. The coefficients of variation were 0.40%, 0.68%, and 0.22% for the three serum samples, and the analytical recovery was 99.8%. The accuracy of the measurement was also verified by measuring certified reference materials, SRM909b and SRM956b. Comparison with the ion selective electrode routine method and international inter-laboratory comparisons gave satisfied results. The new ICP-MS method is specific, precise, simple, and low-cost, and it may be used as a candidate reference method for standardizing serum potassium measurements.

Valx: A system for extracting and structuring numeric lab test comparison statements from text

PubMed Central

Hao, Tianyong; Liu, Hongfang; Weng, Chunhua

2017-01-01

Objectives To develop an automated method for extracting and structuring numeric lab test comparison statements from text and evaluate the method using clinical trial eligibility criteria text. Methods Leveraging semantic knowledge from the Unified Medical Language System (UMLS) and domain knowledge acquired from the Internet, Valx takes 7 steps to extract and normalize numeric lab test expressions: 1) text preprocessing, 2) numeric, unit, and comparison operator extraction, 3) variable identification using hybrid knowledge, 4) variable - numeric association, 5) context-based association filtering, 6) measurement unit normalization, and 7) heuristic rule-based comparison statements verification. Our reference standard was the consensus-based annotation among three raters for all comparison statements for two variables, i.e., HbA1c and glucose, identified from all of Type 1 and Type 2 diabetes trials in ClinicalTrials.gov. Results The precision, recall, and F-measure for structuring HbA1c comparison statements were 99.6%, 98.1%, 98.8% for Type 1 diabetes trials, and 98.8%, 96.9%, 97.8% for Type 2 Diabetes trials, respectively. The precision, recall, and F-measure for structuring glucose comparison statements were 97.3%, 94.8%, 96.1% for Type 1 diabetes trials, and 92.3%, 92.3%, 92.3% for Type 2 diabetes trials, respectively. Conclusions Valx is effective at extracting and structuring free-text lab test comparison statements in clinical trial summaries. Future studies are warranted to test its generalizability beyond eligibility criteria text. The open-source Valx enables its further evaluation and continued improvement among the collaborative scientific community. PMID:26940748

Experimental comparison between performance of the PM and LPM methods in computed radiography

NASA Astrophysics Data System (ADS)

Kermani, Aboutaleb; Feghhi, Seyed Amir Hossein; Rokrok, Behrouz

2018-07-01

The scatter downgrades the image quality and reduces its information efficiency in quantitative measurement usages when creating projections with ionizing radiation. Therefore, the variety of methods have been applied for scatter reduction and correction of the undesirable effects. As new approaches, the ordinary and localized primary modulation methods have already been used individually through experiments and simulations in medical and industrial computed tomography, respectively. The aim of this study is the evaluation of capabilities and limitations of these methods in comparison with each other. For this mean, the ordinary primary modulation has been implemented in computed radiography for the first time and the potential of both methods has been assessed in thickness measurement as well as scatter to primary signal ratio determination. The comparison results, based on the experimental outputs which obtained using aluminum specimens and continuous X-ray spectra, are to the benefit of the localized primary modulation method because of improved accuracy and higher performance especially at the edges.

Estimating direct, diffuse, and global solar radiation for various cities in Iran by two methods and their comparison with the measured data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashjaee, M.; Roomina, M.R.; Ghafouri-Azar, R.

1993-05-01

Two computational methods for calculating hourly, daily, and monthly average values of direct, diffuse, and global solar radiation on horizontal collectors have been presented in this article for location with different latitude, altitude, and atmospheric conditions in Iran. These methods were developed using two different independent sets of measured data from the Iranian Meteorological Organization (IMO) for two cities in Iran (Tehran and Isfahan) during 14 years of measurement for Tehran and 4 years of measurement for Isfahan. Comparison of calculated monthly average global solar radiation, using the two models for Tehran and Isfahan with measured data from the IMO,more » has indicated a good agreement between them. Then these developed methods were extended to another location (city of Bandar-Abbas), where measured data are not available. But the work of Daneshyar predicts its monthly global radiation. The maximum discrepancy of 7% between the developed models and the work of Daneshyar was observed.« less

Investigation of converging and collimated beam instrument geometry on specular gloss measurements

NASA Astrophysics Data System (ADS)

Zwinkels, Joanne C.; Côté, Éric; Morgan, John

2018-02-01

Specular gloss is an important appearance property of a wide variety of manufactured goods. Depending upon the application, e.g. paints, paper, ceramics, etc. different instrument designs and measurement geometries are specified in standard test methods. For a given specular angle, these instrument designs can be broadly classified as converging beam (TAPPI method) and collimated beam (DIN method). In recent comparisons of specular gloss measurements using different glossmeters, very large standard deviations have been reported, well exceeding the manufacturers claims. In this paper, we investigate the effect of instrument beam geometry on gloss measurements. These results indicate that this difference in beam geometry can give the magnitude of gloss differences reported in these comparisons and highlights the importance of educating the user community of best measurement practices and obtaining appropriate traceability for their glossmeters.

Assessing Vowel Centralization in Dysarthria: A Comparison of Methods

ERIC Educational Resources Information Center

Fletcher, Annalise R.; McAuliffe, Megan J.; Lansford, Kaitlin L.; Liss, Julie M.

2017-01-01

Purpose: The strength of the relationship between vowel centralization measures and perceptual ratings of dysarthria severity has varied considerably across reports. This article evaluates methods of acoustic-perceptual analysis to determine whether procedural changes can strengthen the association between these measures. Method: Sixty-one…

Comparison of phase velocities from array measurements of Rayleigh waves associated with microtremor and results calculated from borehole shear-wave velocity profiles

USGS Publications Warehouse

Liu, Hsi-Ping; Boore, David M.; Joyner, William B.; Oppenheimer, David H.; Warrick, Richard E.; Zhang, Wenbo; Hamilton, John C.; Brown, Leo T.

2000-01-01

Shear-wave velocities (VS) are widely used for earthquake ground-motion site characterization. VS data are now largely obtained using borehole methods. Drilling holes, however, is expensive. Nonintrusive surface methods are inexpensive for obtaining VS information, but not many comparisons with direct borehole measurements have been published. Because different assumptions are used in data interpretation of each surface method and public safety is involved in site characterization for engineering structures, it is important to validate the surface methods by additional comparisons with borehole measurements. We compare results obtained from a particular surface method (array measurement of surface waves associated with microtremor) with results obtained from borehole methods. Using a 10-element nested-triangular array of 100-m aperture, we measured surface-wave phase velocities at two California sites, Garner Valley near Hemet and Hollister Municipal Airport. The Garner Valley site is located at an ancient lake bed where water-saturated sediment overlies decomposed granite on top of granite bedrock. Our array was deployed at a location where seismic velocities had been determined to a depth of 500 m by borehole methods. At Hollister, where the near-surface sediment consists of clay, sand, and gravel, we determined phase velocities using an array located close to a 60-m deep borehole where downhole velocity logs already exist. Because we want to assess the measurements uncomplicated by uncertainties introduced by the inversion process, we compare our phase-velocity results with the borehole VS depth profile by calculating fundamental-mode Rayleigh-wave phase velocities from an earth model constructed from the borehole data. For wavelengths less than ~2 times of the array aperture at Garner Valley, phase-velocity results from array measurements agree with the calculated Rayleigh-wave velocities to better than 11%. Measurement errors become larger for wavelengths 2 times greater than the array aperture. At Hollister, the measured phase velocity at 3.9 Hz (near the upper edge of the microtremor frequency band) is within 20% of the calculated Rayleigh-wave velocity. Because shear-wave velocity is the predominant factor controlling Rayleigh-wave phase velocities, the comparisons suggest that this nonintrusive method can provide VS information adequate for ground-motion estimation.

Measuring digit lengths with 3D digital stereophotogrammetry: A comparison across methods.

PubMed

Gremba, Allison; Weinberg, Seth M

2018-05-09

We compared digital 3D stereophotogrammetry to more traditional measurement methods (direct anthropometry and 2D scanning) to capture digit lengths and ratios. The length of the second and fourth digits was measured by each method and the second-to-fourth ratio was calculated. For each digit measurement, intraobserver agreement was calculated for each of the three collection methods. Further, measurements from the three methods were compared directly to one another. Agreement statistics included the intraclass correlation coefficient (ICC) and technical error of measurement (TEM). Intraobserver agreement statistics for the digit length measurements were high for all three methods; ICC values exceeded 0.97 and TEM values were below 1 mm. For digit ratio, intraobserver agreement was also acceptable for all methods, with direct anthropometry exhibiting lower agreement (ICC = 0.87) compared to indirect methods. For the comparison across methods, the overall agreement was high for digit length measurements (ICC values ranging from 0.93 to 0.98; TEM values below 2 mm). For digit ratios, high agreement was observed between the two indirect methods (ICC = 0.93), whereas indirect methods showed lower agreement when compared to direct anthropometry (ICC < 0.75). Digit measurements and derived ratios from 3D stereophotogrammetry showed high intraobserver agreement (similar to more traditional methods) suggesting that landmarks could be placed reliably on 3D hand surface images. While digit length measurements were found to be comparable across all three methods, ratios derived from direct anthropometry tended to be higher than those calculated indirectly from 2D or 3D images. © 2018 Wiley Periodicals, Inc.

An Evaluation of Attitude-Independent Magnetometer-Bias Determination Methods

NASA Technical Reports Server (NTRS)

Hashmall, J. A.; Deutschmann, Julie

1996-01-01

Although several algorithms now exist for determining three-axis magnetometer (TAM) biases without the use of attitude data, there are few studies on the effectiveness of these methods, especially in comparison with attitude dependent methods. This paper presents the results of a comparison of three attitude independent methods and an attitude dependent method for computing TAM biases. The comparisons are based on in-flight data from the Extreme Ultraviolet Explorer (EUVE), the Upper Atmosphere Research Satellite (UARS), and the Compton Gamma Ray Observatory (GRO). The effectiveness of an algorithm is measured by the accuracy of attitudes computed using biases determined with that algorithm. The attitude accuracies are determined by comparison with known, extremely accurate, star-tracker-based attitudes. In addition, the effect of knowledge of calibration parameters other than the biases on the effectiveness of all bias determination methods is examined.

Comparison of potential method in analytic hierarchy process for multi-attribute of catering service companies

NASA Astrophysics Data System (ADS)

Mamat, Siti Salwana; Ahmad, Tahir; Awang, Siti Rahmah

2017-08-01

Analytic Hierarchy Process (AHP) is a method used in structuring, measuring and synthesizing criteria, in particular ranking of multiple criteria in decision making problems. On the other hand, Potential Method is a ranking procedure in which utilizes preference graph ς (V, A). Two nodes are adjacent if they are compared in a pairwise comparison whereby the assigned arc is oriented towards the more preferred node. In this paper Potential Method is used to solve problem on a catering service selection. The comparison of result by using Potential method is made with Extent Analysis. The Potential Method is found to produce the same rank as Extent Analysis in AHP.

A Comparison of Web-Based and Face-to-Face Functional Measurement Experiments

ERIC Educational Resources Information Center

Van Acker, Frederik; Theuns, Peter

2010-01-01

Information Integration Theory (IIT) is concerned with how people combine information into an overall judgment. A method is hereby presented to perform Functional Measurement (FM) experiments, the methodological counterpart of IIT, on the Web. In a comparison of Web-based FM experiments, face-to-face experiments, and computer-based experiments in…

Validity of the SMS, Phone, and medical staff Examination sports injury surveillance system for time-loss and medical attention injuries in sports.

PubMed

Møller, M; Wedderkopp, N; Myklebust, G; Lind, M; Sørensen, H; Hebert, J J; Emery, C A; Attermann, J

2018-01-01

The accurate measurement of sport exposure time and injury occurrence is key to effective injury prevention and management. Current measures are limited by their inability to identify all types of sport-related injury, narrow scope of injury information, or lack the perspective of the injured athlete. The aims of the study were to evaluate the proportion of injuries and the agreement between sport exposures reported by the SMS messaging and follow-up telephone part of the SMS, Phone, and medical staff Examination (SPEx) sports injury surveillance system when compared to measures obtained by trained on-field observers and medical staff (comparison method). We followed 24 elite adolescent handball players over 12 consecutive weeks. Eighty-six injury registrations were obtained by the SPEx and comparison methods. Of them, 35 injury registrations (41%) were captured by SPEx only, 10 injury registrations (12%) by the comparison method only, and 41 injury registrations (48%) by both methods. Weekly exposure time differences (95% limits of agreement) between SPEx and the comparison method ranged from -4.2 to 6.3 hours (training) and -1.5 to 1.0 hours (match) with systematic differences being 1.1 hours (95% CI 0.7 to 1.4) and -0.2 (95% CI -0.3 to -0.2), respectively. These results support the ability of the SPEx system to measure training and match exposures and injury occurrence among young athletes. High weekly response proportions (mean 83%) indicate that SMS messaging can be used for player measures of injury consequences beyond time-loss from sport. However, this needs to be further evaluated in large-scale studies. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Optical Methods

NASA Technical Reports Server (NTRS)

Schmid, Beat; Michalsky, J.; Slater, D.; Barnard, J.; Halthore, R.; Liljegren, J.; Holben, B.; Eck, T.; Livingston, J.; Russell, P.;

The Use and Abuse of Limits of Detection in Environmental Analytical Chemistry

PubMed Central

Brown, Richard J. C.

2008-01-01

The limit of detection (LoD) serves as an important method performance measure that is useful for the comparison of measurement techniques and the assessment of likely signal to noise performance, especially in environmental analytical chemistry. However, the LoD is only truly related to the precision characteristics of the analytical instrument employed for the analysis and the content of analyte in the blank sample. This article discusses how other criteria, such as sampling volume, can serve to distort the quoted LoD artificially and make comparison between various analytical methods inequitable. In order to compare LoDs between methods properly, it is necessary to state clearly all of the input parameters relating to the measurements that have been used in the calculation of the LoD. Additionally, the article discusses that the use of LoDs in contexts other than the comparison of the attributes of analytical methods, in particular when reporting analytical results, may be confusing, less informative than quoting the actual result with an accompanying statement of uncertainty, and may act to bias descriptive statistics. PMID:18690384

Amino acid racemization dating of fossil bones, I. inter-laboratory comparison of racemization measurements

USGS Publications Warehouse

Bada, J.L.; Hoopes, E.; Darling, D.; Dungworth, G.; Kessels, H.J.; Kvenvolden, K.A.; Blunt, D.J.

1979-01-01

Enantiomeric measurements for aspartic acid, glutamic acid, and alanine in twenty-one different fossil bone samples have been carried out by three different laboratories using different analytical methods. These inter-laboratory comparisons demonstrate that D/L aspartic acid measurements are highly reproducible, whereas the enantiomeric measurements for the other amino acids show a wide variation between the three laboratories. At present, aspartic acid measurements are the most suitable for racemization dating of bone because of their superior analytical precision. ?? 1979.

Estimating School Efficiency: A Comparison of Methods Using Simulated Data.

ERIC Educational Resources Information Center

Bifulco, Robert; Bretschneider, Stuart

2001-01-01

Uses simulated data to assess the adequacy of two econometric and linear-programming techniques (data-envelopment analysis and corrected ordinary least squares) for measuring performance-based school reform. In complex data sets (simulated to contain measurement error and endogeneity), these methods are inadequate efficiency measures. (Contains 40…

Contrasting Methods for Measuring Evapotranspiration in Soybean

USDA-ARS?s Scientific Manuscript database

Crop scientists are often interested in canopy rather than leaf water fluxes. Canopy measurements are difficult to obtain because instrumentation is expensive, investigations require a high level of comprehension in micrometeorological methods, and treatment comparisons are usually limited. The obje...

A Conceptual Approach to Assimilating Remote Sensing Data to Improve Soil Moisture Profile Estimates in a Surface Flux/Hydrology Model. 3; Disaggregation

NASA Technical Reports Server (NTRS)

Caulfield, John; Crosson, William L.; Inguva, Ramarao; Laymon, Charles A.; Schamschula, Marius

1998-01-01

This is a followup on the preceding presentation by Crosson and Schamschula. The grid size for remote microwave measurements is much coarser than the hydrological model computational grids. To validate the hydrological models with measurements we propose mechanisms to disaggregate the microwave measurements to allow comparison with outputs from the hydrological models. Weighted interpolation and Bayesian methods are proposed to facilitate the comparison. While remote measurements occur at a large scale, they reflect underlying small-scale features. We can give continuing estimates of the small scale features by correcting the simple 0th-order, starting with each small-scale model with each large-scale measurement using a straightforward method based on Kalman filtering.

A Comparison of Three Methods for Computing Scale Score Conditional Standard Errors of Measurement. ACT Research Report Series, 2013 (7)

ERIC Educational Resources Information Center

Woodruff, David; Traynor, Anne; Cui, Zhongmin; Fang, Yu

2013-01-01

Professional standards for educational testing recommend that both the overall standard error of measurement and the conditional standard error of measurement (CSEM) be computed on the score scale used to report scores to examinees. Several methods have been developed to compute scale score CSEMs. This paper compares three methods, based on…

A Comparison of High Spectral Resolution Infrared Cloud-Top Pressure Altitude Algorithms Using S-HIS Measurements

NASA Technical Reports Server (NTRS)

Holz, Robert E.; Ackerman, Steve; Antonelli, Paolo; Nagle, Fred; McGill, Matthew; Hlavka, Dennis L.; Hart, William D.

2005-01-01

This paper presents a comparison of cloud-top altitude retrieval methods applied to S-HIS (Scanning High Resolution Interferometer Sounder) measurements. Included in this comparison is an improvement to the traditional CO2 Slicing method. The new method, CO2 Sorting, determines optimal channel pairs to apply the CO2 Slicing. Measurements from collocated samples of the Cloud Physics Lidar (CPL) and Modis Airborne Simulator (MAS) instruments assist in the comparison. For optically thick clouds good correlation between the S-HIS and lidar cloud-top retrievals are found. For tenuous ice clouds there can be large differences between lidar (CPL) and S-HIS retrieved cloud-tops. It is found that CO2 Sorting significantly reduces the cloud height biases for the optically thin cloud (total optical depths less then 1.0). For geometrically thick but optically thin cirrus clouds large differences between the S-HIS infrared cloud top retrievals and the CPL detected cloud top where found. For these cases the cloud height retrieved by the S-HIS cloud retrievals correlated closely with the level the CPL integrated cloud optical depth was approximately 1.0.

A Comparison of Three Methods for Measuring Distortion in Optical Windows

NASA Technical Reports Server (NTRS)

Youngquist, Robert C.; Nurge, Mark A.; Skow, Miles

2015-01-01

It's important that imagery seen through large-area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach, the distortion of an acrylic window is measured using three different methods: image comparison, moiré interferometry, and phase-shifting interferometry.

A comparison of techniques for nondestructive composition measurements in CdZnTe substrates

NASA Astrophysics Data System (ADS)

Tobin, S. P.; Tower, J. P.; Norton, P. W.; Chandler-Horowitz, D.; Amirtharaj, P. M.; Lopes, V. C.; Duncan, W. M.; Syllaios, A. J.; Ard, C. K.; Giles, N. C.; Lee, Jaesun; Balasubramanian, R.; Bollong, A. B.; Steiner, T. W.; Thewalt, M. L. W.; Bowen, D. K.; Tanner, B. K.

1995-05-01

We report an overview and a comparison of nondestructive optical techniques for determining alloy composition x in Cd1-xZnxTe substrates for HgCdTe epitaxy. The methods for single-point measurements include a new x-ray diffraction technique for precision lattice parameter measurements using a standard highresolution diffractometer, room-temperature photoreflectance, and low-temperature photoluminescence. We compare measurements on the same set of samples by all three techniques. Comparisons of precision and accuracy, with a discussion of the strengths and weaknesses of different techniques, are presented. In addition, a new photoluminescence excitation technique for full-wafer imaging of composition variations is described.

Comparison of microstickies measurement methods. Part II, Results and discussion

Treesearch

Mahendra R. Doshi; Angeles Blanco; Carlos Negro; Concepcion Monte; Gilles M. Dorris; Carlos C. Castro; Axel Hamann; R. Daniel Haynes; Carl Houtman; Karen Scallon; Hans-Joachim Putz; Hans Johansson; R. A. Venditti; K. Copeland; H.-M. Chang

2003-01-01

In part I of the article we discussed sample preparation procedure and described various methods used for the measurement of microstickies. Some of the important features of different methods are highlighted in Table 1. Temperatures used in the measurement methods vary from room temperature in some cases, 45 °C to 65 °C in other cases. Sample size ranges from as low as...

Assessing Strain Mapping by Electron Backscatter Diffraction and Confocal Raman Microscopy Using Wedge-indented Si

PubMed Central

Friedman, Lawrence H.; Vaudin, Mark D.; Stranick, Stephan J.; Stan, Gheorghe; Gerbig, Yvonne B.; Osborn, William; Cook, Robert F.

2016-01-01

The accuracy of electron backscatter diffraction (EBSD) and confocal Raman microscopy (CRM) for small-scale strain mapping are assessed using the multi-axial strain field surrounding a wedge indentation in Si as a test vehicle. The strain field is modeled using finite element analysis (FEA) that is adapted to the near-indentation surface profile measured by atomic force microscopy (AFM). The assessment consists of (1) direct experimental comparisons of strain and deformation and (2) comparisons in which the modeled strain field is used as an intermediate step. Direct experimental methods (1) consist of comparisons of surface elevation and gradient measured by AFM and EBSD and of Raman shifts measured and predicted by CRM and EBSD, respectively. Comparisons that utilize the combined FEA-AFM model (2) consist of predictions of distortion, strain, and rotation for comparison with EBSD measurements and predictions of Raman shift for comparison with CRM measurements. For both EBSD and CRM, convolution of measurements in depth-varying strain fields is considered. The interconnected comparisons suggest that EBSD was able to provide an accurate assessment of the wedge indentation deformation field to within the precision of the measurements, approximately 2 × 10−4 in strain. CRM was similarly precise, but was limited in accuracy to several times this value. PMID:26939030

Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Solar Transmittance Methods

NASA Technical Reports Server (NTRS)

Schmid, B.; Michalsky, J. J.; Slater, D. W.; Barnard, J. C.; Halthore, R. N.; Liljegren, J. C.; Holben, B. N.; Eck, T. F.; Livingston, J. M.; Russell, P. B.

2000-01-01

In the fall of 1997, during an Intensive Observation Period (IOP), the Atmospheric Radiation Measurement (ARM) program conducted a study of water vapor abundance measurement at its Southern Great Plains (SGP) site. Among a large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring total solar transmittance in the 0.94-gm water vapor absorption band and subtracting contributions due to Rayleigh, ozone and aerosol transmittances. The aerosol optical depth comparisons among the same four radiometers has been presented elsewhere (Geophys. Res. Lett., 26, 17, 2725-2728, 1999). We have used three different methods to retrieve CWV. In a first round of comparison no attempt was made to standardize on the same radiative transfer model and its underlying water vapor spectroscopy. In the second round of comparison we used the same line-by-line code (which includes recently corrected H2O spectroscopy) to retrieve CAN from all four suntracking radiometers. This decreased the mean CWV by 8% or 13%. The spread of 8% in the solar radiometer results found when using the same model is an indication of the other-than-model uncertainties involved in determining CWV from solar transmittance measurements with current instrumentation.

Quantifying plant colour and colour difference as perceived by humans using digital images.

PubMed

Kendal, Dave; Hauser, Cindy E; Garrard, Georgia E; Jellinek, Sacha; Giljohann, Katherine M; Moore, Joslin L

2013-01-01

Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management.

Quantifying Plant Colour and Colour Difference as Perceived by Humans Using Digital Images

PubMed Central

Kendal, Dave; Hauser, Cindy E.; Garrard, Georgia E.; Jellinek, Sacha; Giljohann, Katherine M.; Moore, Joslin L.

2013-01-01

Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management. PMID:23977275

Measuring Melatonin in Humans

PubMed Central

Benloucif, Susan; Burgess, Helen J.; Klerman, Elizabeth B.; Lewy, Alfred J.; Middleton, Benita; Murphy, Patricia J.; Parry, Barbara L.; Revell, Victoria L.

2008-01-01

Study Objectives: To provide guidelines for collecting and analyzing urinary, salivary, and plasma melatonin, thereby assisting clinicians and researchers in determining which method of measuring melatonin is most appropriate for their particular needs and facilitating the comparison of data between laboratories. Methods: A modified RAND process was utilized to derive recommendations for methods of measuring melatonin in humans. Results: Consensus-based guidelines are presented for collecting and analyzing melatonin for studies that are conducted in the natural living environment, the clinical setting, and in-patient research facilities under controlled conditions. Conclusions: The benefits and disadvantages of current methods of collecting and analyzing melatonin are summarized. Although a single method of analysis would be the most effective way to compare studies, limitations of current methods preclude this possibility. Given that the best analysis method for use under multiple conditions is not established, it is recommended to include, in any published report, one of the established low threshold measures of dim light melatonin onset to facilitate comparison between studies. Citation: Benloucif S; Burgess HJ; Klerman EB; Lewy AJ; Middleton B; Murphy PJ; Parry BL; Revell VL. Measuring melatonin in humans. J Clin Sleep Med 2008;4(1):66-69. PMID:18350967

Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria

ERIC Educational Resources Information Center

Titze, Ingo R.; Hunter, Eric J.

2015-01-01

Purpose: School-teachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method: Vibration dosimetry is reformulated with the inclusion of collision stress.…

Paired comparison estimates of willingness to accept versus contingent valuation estimates of willingness to pay

Treesearch

John B. Loomis; George Peterson; Patricia A. Champ; Thomas C. Brown; Beatrice Lucero

1998-01-01

Estimating empirical measures of an individual's willingness to accept that are consistent with conventional economic theory, has proven difficult. The method of paired comparison offers a promising approach to estimate willingness to accept. This method involves having individuals make binary choices between receiving a particular good or a sum of money....

Comparison of an objective method of measuring bulbar redness to the use of traditional grading scales.

PubMed

Sorbara, Luigina; Simpson, Trefford; Duench, Stephanie; Schulze, Marc; Fonn, Desmond

2007-03-01

The primary objective was to compare measures of bulbar redness objectively using a photometric method with standard grading methods. Measures of redness were made on 24 participants wearing a silicone hydrogel contact lens in one eye for overnight wear. This report compares hyperaemia after 1 week of daily wear (baseline) with redness measured after 6 months of overnight wear. A new method of objectively measuring bulbar conjunctival redness was performed using the Spectrascan650 Photometer by Photo Research under fixed illumination. Photometric measures in CIEu(*) chromaticity values involve the measurement of chromaticity, a physical analogue of redness, greenness and blueness in the image. This method was validated in Part 1 of the study using repeated measurements on the photographic CCLRU scale. In Part 2 of the study, the photographic grading scale (CCLRU) from 0 (none) to 100 (extreme) was used to make the comparison. Part 1 indicated that the photometer provides a repeatable and reliable measure of bulbar redness (CCC=0.989). A moderately strong and significant correlation was found between the CIEu(*) chromaticity values and the analogue data (R=0.795, p=0.000) at each measurement session (from baseline to 1 day, 1 week, and 1, 3 and 6 months of overnight wear). This new standardized and objective method of measuring bulbar redness has great potential to replace subjective grading scales, especially with multi-centre studies, where variability between investigators occurs. This method may also detect smaller changes between visits or between eyes.

A laser interferometer for measuring skin friction in three-dimensional flows

NASA Technical Reports Server (NTRS)

Monson, D. J.

1983-01-01

A new, nonintrusive method is described for measuring skin friction in three-dimensional flows with unknown direction. The method uses a laser interferometer to measure the changing slope of a thin oil film applied to a surface experiencing shear stress. The details of the method are described, and skin friction measurements taken in a swirling three-dimensional boundary-layer flow are presented. Comparisons between analytical results and experimental values from the laser interferometer method and from a bidirectional surface-fence gauge are made.

Comparison and validation of the aerosol optical depth obtained with the Langley plot method in the UV-B from Brewer Ozone Spectrophotometer measurements

NASA Astrophysics Data System (ADS)

Cheymol, Anne; de Backer, Hugo; Josefsson, Weine; Stübi, René

2006-08-01

The Aerosol Optical Depths (AODs) retrieved from Brewer Ozone Spectrophotometer measurements with a method previously developed (Cheymol and De Backer, 2003) are now validated by comparisons between AODs from six Brewer spectrophotometers and two CSEM SPM2000 sunphotometers: two Brewer spectrophotometers 016 and 178 at Uccle in Belgium; one Brewer spectrophotometer 128 and one sunphotometer CSEM SPM2000 at Norrköping in Sweden; and three Brewer instruments 040, 072, 156 at Arosa and one CSEM SPM2000 sunphotometer at Davos in Switzerland. The comparison between AODs from Brewer spectrophotometer 128 at 320.1 nm and sunphotometer SPM2000 at 368 nm at Norrköping shows that the AODs obtained from the Brewer measurements with the Langley Plot Method (LPM) are very accurate if the neutral density filter spectral transmittances are well known: with the measured values of these filters, the correlation coefficient, the slope, and the intercept of the regression line are 0.98, 0.85 ± 0.004, and 0.02 ± 0.0014, respectively. The bias observed is mainly owing to the wavelength difference between the two instruments. The comparison between AODs from different Brewer spectrophotometers confirm that AODs will be in very good agreement if they are measured with several Brewer instruments at the same place: At Uccle, the correlation coefficient, slope, and intercept of the regression line are 0.98, 1.02 ± 0.003, and 0.06 ± 0.001, respectively; at Arosa, the comparisons between the AODs from three Brewer spectrophotometers 040, 072, and 156 give a correlation coefficient, a slope, and an intercept of the regression line above 0.94, 0.98 and below 0.04, respectively.

Comparison between measured turbine stage performance and the predicted performance using quasi-3D flow and boundary layer analyses

NASA Technical Reports Server (NTRS)

Boyle, R. J.; Haas, J. E.; Katsanis, T.

1984-01-01

A method for calculating turbine stage performance is described. The usefulness of the method is demonstrated by comparing measured and predicted efficiencies for nine different stages. Comparisons are made over a range of turbine pressure ratios and rotor speeds. A quasi-3D flow analysis is used to account for complex passage geometries. Boundary layer analyses are done to account for losses due to friction. Empirical loss models are used to account for incidence, secondary flow, disc windage, and clearance losses.

Turbulence excited frequency domain damping measurement and truncation effects

NASA Technical Reports Server (NTRS)

Soovere, J.

1976-01-01

Existing frequency domain modal frequency and damping analysis methods are discussed. The effects of truncation in the Laplace and Fourier transform data analysis methods are described. Methods for eliminating truncation errors from measured damping are presented. Implications of truncation effects in fast Fourier transform analysis are discussed. Limited comparison with test data is presented.

Measurement Equivalence in ADL and IADL Difficulty Across International Surveys of Aging: Findings From the HRS, SHARE, and ELSA

PubMed Central

Kasper, Judith D.; Brandt, Jason; Pezzin, Liliana E.

2012-01-01

Objective. To examine the measurement equivalence of items on disability across three international surveys of aging. Method. Data for persons aged 65 and older were drawn from the Health and Retirement Survey (HRS, n = 10,905), English Longitudinal Study of Aging (ELSA, n = 5,437), and Survey of Health, Ageing and Retirement in Europe (SHARE, n = 13,408). Differential item functioning (DIF) was assessed using item response theory (IRT) methods for activities of daily living (ADL) and instrumental activities of daily living (IADL) items. Results. HRS and SHARE exhibited measurement equivalence, but 6 of 11 items in ELSA demonstrated meaningful DIF. At the scale level, this item-level DIF affected scores reflecting greater disability. IRT methods also spread out score distributions and shifted scores higher (toward greater disability). Results for mean disability differences by demographic characteristics, using original and DIF-adjusted scores, were the same overall but differed for some subgroup comparisons involving ELSA. Discussion. Testing and adjusting for DIF is one means of minimizing measurement error in cross-national survey comparisons. IRT methods were used to evaluate potential measurement bias in disability comparisons across three international surveys of aging. The analysis also suggested DIF was mitigated for scales including both ADL and IADL and that summary indexes (counts of limitations) likely underestimate mean disability in these international populations. PMID:22156662

WOODSTOVE EMISSION MEASUREMENT METHODS COMPARISON AND EMISSION FACTORS UPDATE

EPA Science Inventory

This paper compares various field and laboratory woodstove emission measurement methods. n 1988, the U.S. EPA promulgated performance standards for residential wood heaters (woodstoves). ver the past several years, a number of field studies have been undertaken to determine the a...

Quantitative Assessment of Blood Pressure Measurement Accuracy and Variability from Visual Auscultation Method by Observers without Receiving Medical Training

PubMed Central

Feng, Yong; Chen, Aiqing

2017-01-01

This study aimed to quantify blood pressure (BP) measurement accuracy and variability with different techniques. Thirty video clips of BP recordings from the BHS training database were converted to Korotkoff sound waveforms. Ten observers without receiving medical training were asked to determine BPs using (a) traditional manual auscultatory method and (b) visual auscultation method by visualizing the Korotkoff sound waveform, which was repeated three times on different days. The measurement error was calculated against the reference answers, and the measurement variability was calculated from the SD of the three repeats. Statistical analysis showed that, in comparison with the auscultatory method, visual method significantly reduced overall variability from 2.2 to 1.1 mmHg for SBP and from 1.9 to 0.9 mmHg for DBP (both p < 0.001). It also showed that BP measurement errors were significant for both techniques (all p < 0.01, except DBP from the traditional method). Although significant, the overall mean errors were small (−1.5 and −1.2 mmHg for SBP and −0.7 and 2.6 mmHg for DBP, resp., from the traditional auscultatory and visual auscultation methods). In conclusion, the visual auscultation method had the ability to achieve an acceptable degree of BP measurement accuracy, with smaller variability in comparison with the traditional auscultatory method. PMID:29423405

Comparison of RCS prediction techniques, computations and measurements

NASA Astrophysics Data System (ADS)

Brand, M. G. E.; Vanewijk, L. J.; Klinker, F.; Schippers, H.

1992-07-01

Three calculation methods to predict radar cross sections (RCS) of three dimensional objects are evaluated by computing the radar cross sections of a generic wing inlet configuration. The following methods are applied: a three dimensional high frequency method, a three dimensional boundary element method, and a two dimensional finite difference time domain method. The results of the computations are compared with the data of measurements.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Vartio, Eric; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott,Robert C.

2007-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott, Robert C.

2006-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Vertebral rotation measurement: a summary and comparison of common radiographic and CT methods

PubMed Central

Lam, Gabrielle C; Hill, Doug L; Le, Lawrence H; Raso, Jim V; Lou, Edmond H

2008-01-01

Current research has provided a more comprehensive understanding of Adolescent Idiopathic Scoliosis (AIS) as a three-dimensional spinal deformity, encompassing both lateral and rotational components. Apart from quantifying curve severity using the Cobb angle, vertebral rotation has become increasingly prominent in the study of scoliosis. It demonstrates significance in both preoperative and postoperative assessment, providing better appreciation of the impact of bracing or surgical interventions. In the past, the need for computer resources, digitizers and custom software limited studies of rotation to research performed after a patient left the scoliosis clinic. With advanced technology, however, rotation measurements are now more feasible. While numerous vertebral rotation measurement methods have been developed and tested, thorough comparisons of these are still relatively unexplored. This review discusses the advantages and disadvantages of six common measurement techniques based on technology most pertinent in clinical settings: radiography (Cobb, Nash-Moe, Perdriolle and Stokes' method) and computer tomography (CT) imaging (Aaro-Dahlborn and Ho's method). Better insight into the clinical suitability of rotation measurement methods currently available is presented, along with a discussion of critical concerns that should be addressed in future studies and development of new methods. PMID:18976498

Measurement of limb volume: laser scanning versus volume displacement.

PubMed

McKinnon, John Gregory; Wong, Vanessa; Temple, Walley J; Galbraith, Callum; Ferry, Paul; Clynch, George S; Clynch, Colin

2007-10-01

Determining the prevalence and treatment success of surgical lymphedema requires accurate and reproducible measurement. A new method of measurement of limb volume is described. A series of inanimate objects of known and unknown volume was measured using digital laser scanning and water displacement. A similar comparison was made with 10 human volunteers. Digital scanning was evaluated by comparison to the established method of water displacement, then to itself to determine reproducibility of measurement. (1) Objects of known volume: Laser scanning accurately measured the calculated volume but water displacement became less accurate as the size of the object increased. (2) Objects of unknown volume: As average volume increased, there was an increasing bias of underestimation of volume by the water displacement method. The coefficient of reproducibility of water displacement was 83.44 ml. In contrast, the reproducibility of the digital scanning method was 19.0 ml. (3) Human data: The mean difference between water displacement volume and laser scanning volume was 151.7 ml (SD +/- 189.5). The coefficient of reproducibility of water displacement was 450.8 ml whereas for laser scanning it was 174 ml. Laser scanning is an innovative method of measuring tissue volume that combines precision and reproducibility and may have clinical utility for measuring lymphedema. 2007 Wiley-Liss, Inc

Applicability of Unmanned Aerial Vehicles in Research on Aeolian Processes

NASA Astrophysics Data System (ADS)

Algimantas, Česnulevičius; Artūras, Bautrėnas; Linas, Bevainis; Donatas, Ovodas; Kęstutis, Papšys

2018-02-01

Surface dynamics and instabilities are characteristic of aeolian formation. The method of surface comparison is regarded as the most appropriate one for evaluation of the intensity of aeolian processes and the amount of transported sand. The data for surface comparison can be collected by topographic survey measurements and using unmanned aerial vehicles. Time cost for relief microform fixation and measurement executing topographic survey are very high. The method of unmanned aircraft aerial photographs fixation also encounters difficulties because there are no stable clear objects and contours that enable to link aerial photographs, to determine the boundaries of captured territory and to ensure the accuracy of surface measurements. Creation of stationary anchor points is irrational due to intense sand accumulation and deflation in different climate seasons. In September 2015 and in April 2016 the combined methodology was applied for evaluation of intensity of aeolian processes in the Curonian Spit. Temporary signs (marks) were installed on the surface, coordinates of the marks were fixed using GPS and then flight of unmanned aircraft was conducted. The fixed coordinates of marks ensure the accuracy of measuring aerial imagery and the ability to calculate the possible corrections. This method was used to track and measure very small (micro-rank) relief forms (5-10 cm height and 10-20 cm length). Using this method morphometric indicators of micro-terraces caused by sand dunes pressure to gytia layer were measured in a non-contact way. An additional advantage of the method is the ability to accurately link the repeated measurements. The comparison of 3D terrain models showed sand deflation and accumulation areas and quantitative changes in the terrain very clearly.

Final report of the key comparison APMP.QM-K9: APMP comparison on pH measurement of phosphate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Ohata, Masaki; Cherdchu, Chainarong; Tangpaisarnkul, Nongluck

2011-01-01

The APMP.QM-K9 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phosphate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan, NMIJ, and the National Institute of Metrology of Thailand, NIMT, in August 2009. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K9, CCQM-K9.1 and CCQM-K9.2. The comparison material was a phosphate buffer of pH around 6.86 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the first APMP key comparison on pH measurement and the third APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004 and APMP.QM-P09 (a phthalate buffer) in 2006. The results can be used further by any participant to support its CMC claim for a phosphate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the temperature(s) used or the full temperature range between 15 °C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

A review on creatinine measurement techniques.

PubMed

Mohabbati-Kalejahi, Elham; Azimirad, Vahid; Bahrami, Manouchehr; Ganbari, Ahmad

2012-08-15

This paper reviews the entire recent global tendency for creatinine measurement. Creatinine biosensors involve complex relationships between biology and micro-mechatronics to which the blood is subjected. Comparison between new and old methods shows that new techniques (e.g. Molecular Imprinted Polymers based algorithms) are better than old methods (e.g. Elisa) in terms of stability and linear range. All methods and their details for serum, plasma, urine and blood samples are surveyed. They are categorized into five main algorithms: optical, electrochemical, impedometrical, Ion Selective Field-Effect Transistor (ISFET) based technique and chromatography. Response time, detection limit, linear range and selectivity of reported sensors are discussed. Potentiometric measurement technique has the lowest response time of 4-10 s and the lowest detection limit of 0.28 nmol L(-1) belongs to chromatographic technique. Comparison between various techniques of measurements indicates that the best selectivity belongs to MIP based and chromatographic techniques. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of optical and electrical investigations of meat ageing

NASA Astrophysics Data System (ADS)

Prokopyeva, Elena; Tománek, Pavel; Kocová, Lucie; Palai-Dany, Tomáš; Balík, Zdeněk.; Škarvada, Pavel; Grmela, Lubomír.

2013-05-01

Different ultrasonic, electromagnetic, electrical and optical methods are used for meat ageing detection. Muscles are turbid anisotropic media, they exhibit changes in electrical and optical properties according to the direction of the electrical and optical fields in the sample. The work assesses the feasibility of impedance measurements for meat ageing detection and their comparison with optical measurement of scattered light. The pork chop slices were used for their relative homogeneity. An investigation was carried out for the detection of the ageing of unpacked slices exposed directly to the air, and other packed in polyethylene bags. The electrical method is a promising method due to the possibility of getting much information and realizing cheap and fast enough measurement systems. The optical method allows measure the rotation of polarization plane in the range of 95 degrees within considered period. Nevertheless, further work has to be provided to determine closer relationships between optical scattering characteristics, electrical anisotropy in ageing-related tissue structural properties.

A novel anisotropic fast marching method and its application to blood flow computation in phase-contrast MRI.

PubMed

Schwenke, M; Hennemuth, A; Fischer, B; Friman, O

2012-01-01

Phase-contrast MRI (PC MRI) can be used to assess blood flow dynamics noninvasively inside the human body. The acquired images can be reconstructed into flow vector fields. Traditionally, streamlines can be computed based on the vector fields to visualize flow patterns and particle trajectories. The traditional methods may give a false impression of precision, as they do not consider the measurement uncertainty in the PC MRI images. In our prior work, we incorporated the uncertainty of the measurement into the computation of particle trajectories. As a major part of the contribution, a novel numerical scheme for solving the anisotropic Fast Marching problem is presented. A computing time comparison to state-of-the-art methods is conducted on artificial tensor fields. A visual comparison of healthy to pathological blood flow patterns is given. The comparison shows that the novel anisotropic Fast Marching solver outperforms previous schemes in terms of computing time. The visual comparison of flow patterns directly visualizes large deviations of pathological flow from healthy flow. The novel anisotropic Fast Marching solver efficiently resolves even strongly anisotropic path costs. The visualization method enables the user to assess the uncertainty of particle trajectories derived from PC MRI images.

Comparison of usual and alternative methods to measure height in mechanically ventilated patients: potential impact on protective ventilation.

PubMed

Bojmehrani, Azadeh; Bergeron-Duchesne, Maude; Bouchard, Carmelle; Simard, Serge; Bouchard, Pierre-Alexandre; Vanderschuren, Abel; L'Her, Erwan; Lellouche, François

2014-07-01

Protective ventilation implementation requires the calculation of predicted body weight (PBW), determined by a formula based on gender and height. Consequently, height inaccuracy may be a limiting factor to correctly set tidal volumes. The objective of this study was to evaluate the accuracy of different methods in measuring heights in mechanically ventilated patients. Before cardiac surgery, actual height was measured with a height gauge while subjects were standing upright (reference method); the height was also estimated by alternative methods based on lower leg and forearm measurements. After cardiac surgery, upon ICU admission, a subject's height was visually estimated by a clinician and then measured with a tape measure while the subject was supine and undergoing mechanical ventilation. One hundred subjects (75 men, 25 women) were prospectively included. Mean PBW was 61.0 ± 9.7 kg, and mean actual weight was 30.3% higher. In comparison with the reference method, estimating the height visually and using the tape measure were less accurate than both lower leg and forearm measurements. Errors above 10% in calculating the PBW were present in 25 and 40 subjects when the tape measure or visual estimation of height was used in the formula, respectively. With lower leg and forearm measurements, 15 subjects had errors above 10% (P < .001). Our results demonstrate that significant variability exists between the different methods used to measure height in bedridden patients on mechanical ventilation. Alternative methods based on lower leg and forearm measurements are potentially interesting solutions to facilitate the accurate application of protective ventilation. Copyright © 2014 by Daedalus Enterprises.

Comparison between psycho-acoustics and physio-acoustic measurement to determine optimum reverberation time of pentatonic angklung music concert hall

NASA Astrophysics Data System (ADS)

Sudarsono, Anugrah S.; Merthayasa, I. G. N.; Suprijanto

2015-09-01

This research tried to compare psycho-acoustics and Physio-acoustic measurement to find the optimum reverberation time of soundfield from angklung music. Psycho-acoustic measurement was conducted using a paired comparison method and Physio-acoustic measurement was conducted with EEG Measurement on T3, T4, FP1, and FP2 measurement points. EEG measurement was conducted with 5 persons. Pentatonic angklung music was used as a stimulus with reverberation time variation. The variation was between 0.8 s - 1.6 s with 0.2 s step. EEG signal was analysed using a Power Spectral Density method on Alpha Wave, High Alpha Wave, and Theta Wave. Psycho-acoustic measurement on 50 persons showed that reverberation time preference of pentatonic angklung music was 1.2 second. The result was similar to Theta Wave measurement on FP2 measurement point. High Alpha wave on T4 measurement gave different results, but had similar patterns with psycho-acoustic measurement

Comparison of fluid-fluid interfacial areas measured with X-ray microtomography and interfacial partitioning tracer tests for the same samples: COMPARISON OF FLUID-FLUID INTERFACIAL AREAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, Kieran; Carroll, Kenneth C.; Brusseau, Mark L.

2016-07-01

Two different methods are currently used for measuring interfacial areas between immiscible fluids within 3-D porous media, high-resolution microtomographic imaging and interfacial partitioning tracer tests (IPTT). Both methods were used in this study to measure nonwetting/wetting interfacial areas for a natural sand. The microtomographic imaging was conducted on the same packed columns that were used for the IPTTs. This is in contrast to prior studies comparing the two methods, for which in all cases different samples were used for the two methods. In addition, the columns were imaged before and after the IPTTs to evaluate the potential impacts of themore » tracer solution on fluid configuration and attendant interfacial area. The interfacial areas measured using IPTT are ~5 times larger than the microtomographic-measured values, which is consistent with previous work. Analysis of the image data revealed no significant impact of the tracer solution on NAPL configuration or interfacial area. Other potential sources of error were evaluated, and all were demonstrated to be insignificant. The disparity in measured interfacial areas between the two methods is attributed to the limitation of the microtomography method to characterize interfacial area associated with microscopic surface roughness due to resolution constraints.« less

[Analysis of variance of repeated data measured by water maze with SPSS].

PubMed

Qiu, Hong; Jin, Guo-qin; Jin, Ru-feng; Zhao, Wei-kang

2007-01-01

To introduce the method of analyzing repeated data measured by water maze with SPSS 11.0, and offer a reference statistical method to clinical and basic medicine researchers who take the design of repeated measures. Using repeated measures and multivariate analysis of variance (ANOVA) process of the general linear model in SPSS and giving comparison among different groups and different measure time pairwise. Firstly, Mauchly's test of sphericity should be used to judge whether there were relations among the repeatedly measured data. If any (P

Blood glucose measurement by glucometer in comparison with standard method in diagnosis of neonatal hypoglycemia.

PubMed

Nayeri, Fatemeh; Shariat, Mamak; Mousavi Behbahani, Hamid Modarres; Dehghan, Padideh; Ebrahim, Bita

2014-01-01

Hypoglycemia is considered as a serious risk factor in neonates. In the majority of cases, it occurs with no clinical symptoms. Accordingly, early diagnosis is extremely imperative, which can also lead to less morbidity and mortality. The aim of this study was to assess the importance of screening blood glucose using glucometer (known as a quick and cost-effective diagnostic test) in comparison with laboratory method. A total of 219 neonates at risk of hypoglycemia were included in this study. Blood glucose was measured by glucometer and laboratory. In addition glucose level of capillary blood was measured by glucometer at the same time. Sensitivity and specificity of capillary blood glucose measurement by glucometer were 83.5%, 97.5% respectively (ppv=80%), (npv=98%). Capillary blood glucose measured by glucometer has an acceptable sensitivity and specificity in measurement of neonatal blood glucose. Therefore measurement by glucometer is recommended as a proper diagnostic test.

Transonic pressure measurements and comparison of theory to experiment for an arrow-wing configuration. Volume 1: Experimental data report, base configuration and effects of wing twist and leading-edge configuration. [wind tunnel tests, aircraft models

NASA Technical Reports Server (NTRS)

Manro, M. E.; Manning, K. J. R.; Hallstaff, T. H.; Rogers, J. T.

1975-01-01

A wind tunnel test of an arrow-wing-body configuration consisting of flat and twisted wings, as well as a variety of leading- and trailing-edge control surface deflections, was conducted at Mach numbers from 0.4 to 1.1 to provide an experimental pressure data base for comparison with theoretical methods. Theory-to-experiment comparisons of detailed pressure distributions were made using current state-of-the-art attached and separated flow methods. The purpose of these comparisons was to delineate conditions under which these theories are valid for both flat and twisted wings and to explore the use of empirical methods to correct the theoretical methods where theory is deficient.

Thorndike, Thurstone and Rasch: A Comparison of Their Approaches to Item-Invariant Measurement.

ERIC Educational Resources Information Center

Englehard, George, Jr.

The methods used by E. L. Thorndike, L. L. Thurstone, and G. Rasch to address issues related to item-invariant measurement and the scoring of individual performance are compared. The analyses highlight the close connection among the three methods, and suggest that progress in measurement theory reflects the movement from essentially ad hoc methods…

Comparing methods for measuring the rate of spread of invading populations

Treesearch

Marius Gilbert; Andrew Liebhold

2010-01-01

Measuring rates of spread during biological invasions is important for predicting where and when invading organisms will spread in the future as well as for quantifying the influence of environmental conditions on invasion speed. While several methods have been proposed in the literature to measure spread rates, a comprehensive comparison of their accuracy when applied...

A Comparison of Fuzzy Models in Similarity Assessment of Misregistered Area Class Maps

NASA Astrophysics Data System (ADS)

Brown, Scott

Spatial uncertainty refers to unknown error and vagueness in geographic data. It is relevant to land change and urban growth modelers, soil and biome scientists, geological surveyors and others, who must assess thematic maps for similarity, or categorical agreement. In this paper I build upon prior map comparison research, testing the effectiveness of similarity measures on misregistered data. Though several methods compare uncertain thematic maps, few methods have been tested on misregistration. My objective is to test five map comparison methods for sensitivity to misregistration, including sub-pixel errors in both position and rotation. Methods included four fuzzy categorical models: fuzzy kappa's model, fuzzy inference, cell aggregation, and the epsilon band. The fifth method used conventional crisp classification. I applied these methods to a case study map and simulated data in two sets: a test set with misregistration error, and a control set with equivalent uniform random error. For all five methods, I used raw accuracy or the kappa statistic to measure similarity. Rough-set epsilon bands report the most similarity increase in test maps relative to control data. Conversely, the fuzzy inference model reports a decrease in test map similarity.

Comparison of SVM RBF-NN and DT for crop and weed identification based on spectral measurement over corn fields

USDA-ARS?s Scientific Manuscript database

It is important to find an appropriate pattern-recognition method for in-field plant identification based on spectral measurement in order to classify the crop and weeds accurately. In this study, the method of Support Vector Machine (SVM) was evaluated and compared with two other methods, Decision ...

Improving the evaluation of therapeutic interventions in multiple sclerosis: the role of new psychometric methods.

PubMed

Hobart, J; Cano, S

2009-02-01

In this monograph we examine the added value of new psychometric methods (Rasch measurement and Item Response Theory) over traditional psychometric approaches by comparing and contrasting their psychometric evaluations of existing sets of rating scale data. We have concentrated on Rasch measurement rather than Item Response Theory because we believe that it is the more advantageous method for health measurement from a conceptual, theoretical and practical perspective. Our intention is to provide an authoritative document that describes the principles of Rasch measurement and the practice of Rasch analysis in a clear, detailed, non-technical form that is accurate and accessible to clinicians and researchers in health measurement. A comparison was undertaken of traditional and new psychometric methods in five large sets of rating scale data: (1) evaluation of the Rivermead Mobility Index (RMI) in data from 666 participants in the Cannabis in Multiple Sclerosis (CAMS) study; (2) evaluation of the Multiple Sclerosis Impact Scale (MSIS-29) in data from 1725 people with multiple sclerosis; (3) evaluation of test-retest reliability of MSIS-29 in data from 150 people with multiple sclerosis; (4) examination of the use of Rasch analysis to equate scales purporting to measure the same health construct in 585 people with multiple sclerosis; and (5) comparison of relative responsiveness of the Barthel Index and Functional Independence Measure in data from 1400 people undergoing neurorehabilitation. Both Rasch measurement and Item Response Theory are conceptually and theoretically superior to traditional psychometric methods. Findings from each of the five studies show that Rasch analysis is empirically superior to traditional psychometric methods for evaluating rating scales, developing rating scales, analysing rating scale data, understanding and measuring stability and change, and understanding the health constructs we seek to quantify. There is considerable added value in using Rasch analysis rather than traditional psychometric methods in health measurement. Future research directions include the need to reproduce our findings in a range of clinical populations, detailed head-to-head comparisons of Rasch analysis and Item Response Theory, and the application of Rasch analysis to clinical practice.

Comparison of a clinical gait analysis method using videography and temporal-distance measures with 16-mm cinematography.

PubMed

Stuberg, W A; Colerick, V L; Blanke, D J; Bruce, W

1988-08-01

The purpose of this study was to compare a clinical gait analysis method using videography and temporal-distance measures with 16-mm cinematography in a gait analysis laboratory. Ten children with a diagnosis of cerebral palsy (means age = 8.8 +/- 2.7 years) and 9 healthy children (means age = 8.9 +/- 2.4 years) participated in the study. Stride length, walking velocity, and goniometric measurements of the hip, knee, and ankle were recorded using the two gait analysis methods. A multivariate analysis of variance was used to determine significant differences between the data collected using the two methods. Pearson product-moment correlation coefficients were determined to examine the relationship between the measurements recorded by the two methods. The consistency of performance of the subjects during walking was examined by intraclass correlation coefficients. No significant differences were found between the methods for the variables studied. Pearson product-moment correlation coefficients ranged from .79 to .95, and intraclass coefficients ranged from .89 to .97. The clinical gait analysis method was found to be a valid tool in comparison with 16-mm cinematography for the variables that were studied.

Two laboratory methods for the calibration of GPS speed meters

NASA Astrophysics Data System (ADS)

Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

2015-01-01

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40-180 km h-1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology.

Manipulating measurement scales in medical statistical analysis and data mining: A review of methodologies

PubMed Central

Marateb, Hamid Reza; Mansourian, Marjan; Adibi, Peyman; Farina, Dario

2014-01-01

Background: selecting the correct statistical test and data mining method depends highly on the measurement scale of data, type of variables, and purpose of the analysis. Different measurement scales are studied in details and statistical comparison, modeling, and data mining methods are studied based upon using several medical examples. We have presented two ordinal–variables clustering examples, as more challenging variable in analysis, using Wisconsin Breast Cancer Data (WBCD). Ordinal-to-Interval scale conversion example: a breast cancer database of nine 10-level ordinal variables for 683 patients was analyzed by two ordinal-scale clustering methods. The performance of the clustering methods was assessed by comparison with the gold standard groups of malignant and benign cases that had been identified by clinical tests. Results: the sensitivity and accuracy of the two clustering methods were 98% and 96%, respectively. Their specificity was comparable. Conclusion: by using appropriate clustering algorithm based on the measurement scale of the variables in the study, high performance is granted. Moreover, descriptive and inferential statistics in addition to modeling approach must be selected based on the scale of the variables. PMID:24672565

Laser tracker orientation in confined space using on-board targets

NASA Astrophysics Data System (ADS)

Gao, Yang; Kyle, Stephen; Lin, Jiarui; Yang, Linghui; Ren, Yu; Zhu, Jigui

2016-08-01

This paper presents a novel orientation method for two laser trackers using on-board targets attached to the tracker head and rotating with it. The technique extends an existing method developed for theodolite intersection systems which are now rarely used. This method requires only a very narrow space along the baseline between the instrument heads, in order to establish the orientation relationship. This has potential application in environments where space is restricted. The orientation parameters can be calculated by means of two-face reciprocal measurements to the on-board targets, and measurements to a common point close to the baseline. An accurate model is then applied which can be solved through nonlinear optimization. Experimental comparison has been made with the conventional orientation method, which is based on measurements to common intersection points located off the baseline. This requires more space and the comparison has demonstrated the feasibility of the more compact technique presented here. Physical setup and testing suggest that the method is practical. Uncertainties estimated by simulation indicate good performance in terms of measurement quality.

International documentary standards and comparison of national physical measurement standards for the calibration of accelerometers

NASA Astrophysics Data System (ADS)

Evans, David J.

2002-11-01

The documentary standards defining internationally adopted methodologies and protocols for calibrating transducers used to measure vibration are currently developed under the International Organization for Standardization (ISO) Technical Committee 108 Sub Committee 3 (Use and calibration of vibration and shock measuring instruments). Recent revisions of the documentary standards on primary methods for the calibration of accelerometers used to measure rectilinear motion have been completed. These standards can be, and have been, used as references in the technical protocols of key international and regional comparisons between National Measurement Institutes (NMIs) on the calibration of accelerometers. These key comparisons are occurring in part as a result of the creation of the Mutual Recognition Arrangement between NMIs which has appendices that document the uncertainties, and the comparisons completed in support of the uncertainties, claimed by the National Laboratories that are signatories of the MRA. The measurements for the first international and the first Interamerican System of Metrology (SIM) regional key comparisons in vibration have been completed. These intercomparisons were promulgated via the relatively new Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV) of the International Committee for Weights and Measures (CIPM) and SIM Metrology Working Group (MWG) 9, respectively.

A Stellar Dynamical Black Hole Mass for the Reverberation Mapped AGN NGC 5273

NASA Astrophysics Data System (ADS)

Batiste, Merida; Bentz, Misty C.; Valluri, Monica; Onken, Christopher A.

2018-01-01

We present preliminary results from stellar dynamical modeling of the mass of the central super-massive black hole (MBH) in the active galaxy NGC 5273. NGC 5273 is one of the few AGN with a secure MBH measurement from reverberation-mapping that is also nearby enough to measure MBH with stellar dynamical modeling. Dynamical modeling and reverberation-mapping are the two most heavily favored methods of direct MBH determination in the literature, however the specific limitations of each method means that there are very few galaxies for which both can be used. To date only two such galaxies, NGC 3227 and NGC 4151, have MBH determinations from both methods. Given this small sample size, it is not yet clear that the two methods give consistent results. Moreover, given the inherent uncertainties and potential systematic biases in each method, it is likewise unclear whether one method should be preferred over the other. This study is part of an ongoing project to increase the sample of galaxies with secure MBH measurements from both methods, so that a direct comparison may be made. NGC 5273 provides a particularly valuable comparison because it is free of kinematic substructure (e.g. the presence of a bar, as is the case for NGC 4151) which can complicate and potentially bias results from stellar dynamical modeling. I will discuss our current results as well as the advantages and limitations of each method, and the potential sources of systematic bias that may affect comparison between results.

The Danish Organic Action Plan 2020: assessment method and baseline status of organic procurement in public kitchens.

PubMed

Sørensen, Nina N; Lassen, Anne D; Løje, Hanne; Tetens, Inge

2015-09-01

With political support from the Danish Organic Action Plan 2020, organic public procurement in Denmark is expected to increase. In order to evaluate changes in organic food procurement in Danish public kitchens, reliable methods are needed. The present study aimed to compare organic food procurement measurements by two methods and to collect and discuss baseline organic food procurement measurements from public kitchens participating in the Danish Organic Action Plan 2020. Comparison study measuring organic food procurement by applying two different methods, one based on the use of procurement invoices (the Organic Cuisine Label method) and the other on self-reported procurement (the Dogme method). Baseline organic food procurement status was based on organic food procurement measurements and background information from public kitchens. Public kitchens participating in the six organic food conversion projects funded by the Danish Organic Action Plan 2020 during 2012 and 2013. Twenty-six public kitchens (comparison study) and 345 public kitchens (baseline organic food procurement status). A high significant correlation coefficient was found between the two organic food procurement measurement methods (r=0·83, P<0·001) with measurements relevant for the baseline status. Mean baseline organic food procurement was found to be 24 % when including measurements from both methods. The results indicate that organic food procurement measurements by both methods were valid for the baseline status report of the Danish Organic Action Plan 2020. Baseline results in Danish public kitchens suggest there is room for more organic as well as sustainable public procurement in Denmark.

Comparison of gravimetric, creamatocrit and esterified fatty acid methods for determination of total fat content in human milk.

PubMed

Du, Jian; Gay, Melvin C L; Lai, Ching Tat; Trengove, Robert D; Hartmann, Peter E; Geddes, Donna T

2017-02-15

The gravimetric method is considered the gold standard for measuring the fat content of human milk. However, it is labor intensive and requires large volumes of human milk. Other methods, such as creamatocrit and esterified fatty acid assay (EFA), have also been used widely in fat analysis. However, these methods have not been compared concurrently with the gravimetric method. Comparison of the three methods was conducted with human milk of varying fat content. Correlations between these methods were high (r(2)=0.99). Statistical differences (P<0.001) were observed in the overall fat measurements and within each group (low, medium and high fat milk) using the three methods. Overall, stronger correlation with lower mean (4.73g/L) and percentage differences (5.16%) was observed with the creamatocrit than the EFA method when compared to the gravimetric method. Furthermore, the ease of operation and real-time analysis make the creamatocrit method preferable. Copyright © 2016. Published by Elsevier Ltd.

Multiplex cDNA quantification method that facilitates the standardization of gene expression data

PubMed Central

Gotoh, Osamu; Murakami, Yasufumi; Suyama, Akira

2011-01-01

Microarray-based gene expression measurement is one of the major methods for transcriptome analysis. However, current microarray data are substantially affected by microarray platforms and RNA references because of the microarray method can provide merely the relative amounts of gene expression levels. Therefore, valid comparisons of the microarray data require standardized platforms, internal and/or external controls and complicated normalizations. These requirements impose limitations on the extensive comparison of gene expression data. Here, we report an effective approach to removing the unfavorable limitations by measuring the absolute amounts of gene expression levels on common DNA microarrays. We have developed a multiplex cDNA quantification method called GEP-DEAN (Gene expression profiling by DCN-encoding-based analysis). The method was validated by using chemically synthesized DNA strands of known quantities and cDNA samples prepared from mouse liver, demonstrating that the absolute amounts of cDNA strands were successfully measured with a sensitivity of 18 zmol in a highly multiplexed manner in 7 h. PMID:21415008

Comparison of methods for measuring cholinesterase inhibition by carbamates

PubMed Central

Wilhelm, K.; Vandekar, M.; Reiner, E.

1973-01-01

The Acholest and tintometric methods are used widely for measuring blood cholinesterase activity after exposure to organophosphorus compounds. However, if applied for measuring blood cholinesterase activity in persons exposed to carbamates, the accuracy of the methods requires verification since carbamylated cholinesterases are unstable. The spectrophotometric method was used as a reference method and the two field methods were employed under controlled conditions. Human blood cholinesterases were inhibited in vitro by four methylcarbamates that are used as insecticides. When plasma cholinesterase activity was measured by the Acholest and spectrophotometric methods, no difference was found. The enzyme activity in whole blood determined by the tintometric method was ≤ 11% higher than when the same sample was measured by the spectrophotometric method. PMID:4541147

Comparative measurements of ambient atmospheric concentrations of ice nucleating particles using multiple immersion freezing methods and a continuous flow diffusion chamber

NASA Astrophysics Data System (ADS)

DeMott, Paul J.; Hill, Thomas C. J.; Petters, Markus D.; Bertram, Allan K.; Tobo, Yutaka; Mason, Ryan H.; Suski, Kaitlyn J.; McCluskey, Christina S.; Levin, Ezra J. T.; Schill, Gregory P.; Boose, Yvonne; Rauker, Anne Marie; Miller, Anna J.; Zaragoza, Jake; Rocci, Katherine; Rothfuss, Nicholas E.; Taylor, Hans P.; Hader, John D.; Chou, Cedric; Huffman, J. Alex; Pöschl, Ulrich; Prenni, Anthony J.; Kreidenweis, Sonia M.

2017-09-01

A number of new measurement methods for ice nucleating particles (INPs) have been introduced in recent years, and it is important to address how these methods compare. Laboratory comparisons of instruments sampling major INP types are common, but few comparisons have occurred for ambient aerosol measurements exploring the utility, consistency and complementarity of different methods to cover the large dynamic range of INP concentrations that exists in the atmosphere. In this study, we assess the comparability of four offline immersion freezing measurement methods (Colorado State University ice spectrometer, IS; North Carolina State University cold stage, CS; National Institute for Polar Research Cryogenic Refrigerator Applied to Freezing Test, CRAFT; University of British Columbia micro-orifice uniform deposit impactor-droplet freezing technique, MOUDI-DFT) and an online method (continuous flow diffusion chamber, CFDC) used in a manner deemed to promote/maximize immersion freezing, for the detection of INPs in ambient aerosols at different locations and in different sampling scenarios. We also investigated the comparability of different aerosol collection methods used with offline immersion freezing instruments. Excellent agreement between all methods could be obtained for several cases of co-sampling with perfect temporal overlap. Even for sampling periods that were not fully equivalent, the deviations between atmospheric INP number concentrations measured with different methods were mostly less than 1 order of magnitude. In some cases, however, the deviations were larger and not explicable without sampling and measurement artifacts. Overall, the immersion freezing methods seem to effectively capture INPs that activate as single particles in the modestly supercooled temperature regime (> -20 °C), although more comparisons are needed in this temperature regime that is difficult to access with online methods. Relative to the CFDC method, three immersion freezing methods that disperse particles into a bulk liquid (IS, CS, CRAFT) exhibit a positive bias in measured INP number concentrations below -20 °C, increasing with decreasing temperature. This bias was present but much less pronounced for a method that condenses separate water droplets onto limited numbers of particles prior to cooling and freezing (MOUDI-DFT). Potential reasons for the observed differences are discussed, and further investigations proposed to elucidate the role of all factors involved.

A Tomographic Method for the Reconstruction of Local Probability Density Functions

NASA Technical Reports Server (NTRS)

Sivathanu, Y. R.; Gore, J. P.

1993-01-01

A method of obtaining the probability density function (PDF) of local properties from path integrated measurements is described. The approach uses a discrete probability function (DPF) method to infer the PDF of the local extinction coefficient from measurements of the PDFs of the path integrated transmittance. The local PDFs obtained using the method are compared with those obtained from direct intrusive measurements in propylene/air and ethylene/air diffusion flames. The results of this comparison are good.

Realization of the medium and high vacuum primary standard in CENAM, Mexico

NASA Astrophysics Data System (ADS)

Torres-Guzman, J. C.; Santander, L. A.; Jousten, K.

2005-12-01

A medium and high vacuum primary standard, based on the static expansion method, has been set up at Centro Nacional de Metrología (CENAM), Mexico. This system has four volumes and covers a measuring range of 1 × 10-5 Pa to 1 × 103 Pa of absolute pressure. As part of its realization, a characterization was performed, which included volume calibrations, several tests and a bilateral key comparison. To determine the expansion ratios, two methods were applied: the gravimetric method and the method with a linearized spinning rotor gauge. The outgassing ratios for the whole system were also determined. A comparison was performed with Physikalisch-Technische Bundesanstalt (comparison SIM-Euromet.M.P-BK3). By means of this comparison, a link has been achieved with the Euromet comparison (Euromet.M.P-K1.b). As a result, it is concluded that the value obtained at CENAM is equivalent to the Euromet reference value, and therefore the design, construction and operation of CENAM's SEE-1 vacuum primary standard were successful.

Supersonic pressure measurements and comparison of theory to experiment for an arrow-wing configuration

NASA Technical Reports Server (NTRS)

Manro, M. E.

1976-01-01

A wind tunnel test of an arrow-wing-body configuration consisting of flat and twisted wings, as well as leading- and trailing-edge control surface deflections, was conducted at Mach numbers from 1.54 to 2.50 to provide an experimental pressure data base for comparison with theoretical methods. Theory-to-experiment comparisons of detailed pressure distributions were made using a state-of-the-art inviscid flow, constant-pressure-panel method. Emphasis was on conditions under which this theory is valid for both flat and twisted wings.

Transonic pressure measurements and comparison of theory to experiment for three arrow-wing configurations

NASA Technical Reports Server (NTRS)

Manro, M. E.

1982-01-01

Wind tunnel tests of arrow-wing body configurations consisting of flat, twisted, and cambered twisted wings, as well as a variety of leading and trailing edge control surface deflections, were conducted at Mach numbers from 0.4 to 1.05 to provide an experimental pressure data base for comparison with theoretical methods. Theory to experiment comparisons of detailed pressure distributions were made using state of the art attached flow methods. Conditions under which these theories are valid for these wings are presented.

Practical methodological guide for hydrometric inter-laboratory organisation

NASA Astrophysics Data System (ADS)

Besson, David; Bertrand, Xavier

2015-04-01

Discharge measurements performed by the French governmental hydrometer team feed a national database. This data is available for general river flows knowkedge, flood forecasting, low water survey, statistical calculations flow, control flow regulatory and many other uses. Regularly checking the measurements quality and better quantifying its accuracy is therefore an absolute need. The practice of inter-laboratory comparison in hydrometry particularly developed during the last decade. Indeed, discharge measurement can not easily be linked to a standard. Therefore, on-site measurement accuracy control is very difficult. Inter-laboratory comparison is thus a practical solution to this issue. However, it needs some regulations in order to ease its practice and legitimize its results. To do so, the French government hydrometrics teams produced a practical methodological guide for hydrometric inter-laboratory organisation in destination of hydrometers community in view of ensure the harmonization of inter-laboratory comparison practices for different materials (ADCP, current meter on wadind rod or gauging van, tracer dilution, surface speed) and flow range (flood, low water). Ensure the results formalization and banking. The realisation of this practice guide is grounded on the experience of the governmental teams & their partners (or fellows), following existing approaches (Doppler group especially). The guide is designated to validate compliance measures and identify outliers : Hardware, methodological, environmental, or human. Inter-laboratory comparison provides the means to verify the compliance of the instruments (devices + methods + operators) and provides methods to determine an experimental uncertainty of the tested measurement method which is valid only for the site and the measurement conditions but does not address the calibration or periodic monitoring of the few materials. After some conceptual definitions, the guide describes the different stages of an inter-comparison campaign: the campaing creation: targets, participants ( instruments type and number) and site preparation of test protocols and schedule; the campaign set-up (organization): invitation and pre-information of the participants, logistics, field preparation; the campaign conduct: participants reception and information, sequences of tests, results analysis and communication, balance sheet; post-campaign work: further analysis, dissemination and periodic verification of the instruments. This guide is associated with measurement instruments forms, reminding their limits and conditions for use, land forms, used to record all the necessary information during the inter-comparison campaign (site description and measurement conditions, equipment and its settings, and the set of measurements or intermediate calculations to the final results) as well as a calculation tool and banking measures and results.

A COMPARISON OF VECTOR AND RASTER GIS METHODS FOR CALCULATING LANDSCAPE METRICS USED IN ENVIRONMENTAL ASSESSMENTS

EPA Science Inventory

GIS-based measurements that combine native raster and native vector data are commonly used to assess environmental quality. Most of these measurements can be calculated using either raster or vector data formats and processing methods. Raster processes are more commonly used beca...

ABSCISSA ASSESSMENT WITH ALGAE: A COMPARISON OF LOCAL AND LANDSCAPE IMPAIRMENT MEASURES FOR BIOLOGICAL ASSESSMENT USING BENTHIC DIATOMS

EPA Science Inventory

The development of rigorous biological assessments is dependent upon well-constructed abscissa, and various methods, both subjective and objective, exist to measure expected impairment at both the landscape and local scale. A new, landscape-scale method has recently been offered...

A Comparison of Two Methods for Estimating Black Hole Spin in Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capellupo, Daniel M.; Haggard, Daryl; Wafflard-Fernandez, Gaylor, E-mail: danielc@physics.mcgill.ca

Angular momentum, or spin, is a fundamental property of black holes (BHs), yet it is much more difficult to estimate than mass or accretion rate (for actively accreting systems). In recent years, high-quality X-ray observations have allowed for detailed measurements of the Fe K α emission line, where relativistic line broadening allows constraints on the spin parameter (the X-ray reflection method). Another technique uses accretion disk models to fit the AGN continuum emission (the continuum-fitting, or CF, method). Although each technique has model-dependent uncertainties, these are the best empirical tools currently available and should be vetted in systems where bothmore » techniques can be applied. A detailed comparison of the two methods is also useful because neither method can be applied to all AGN. The X-ray reflection technique targets mostly local ( z ≲ 0.1) systems, while the CF method can be applied at higher redshift, up to and beyond the peak of AGN activity and growth. Here, we apply the CF method to two AGN with X-ray reflection measurements. For both the high-mass AGN, H1821+643, and the Seyfert 1, NGC 3783, we find a range in spin parameter consistent with the X-ray reflection measurements. However, the near-maximal spin favored by the reflection method for NGC 3783 is more probable if we add a disk wind to the model. Refinement of these techniques, together with improved X-ray measurements and tighter BH mass constraints, will permit this comparison in a larger sample of AGN and increase our confidence in these spin estimation techniques.« less

On the equivalence of generalized least-squares approaches to the evaluation of measurement comparisons

NASA Astrophysics Data System (ADS)

Koo, A.; Clare, J. F.

2012-06-01

Analysis of CIPM international comparisons is increasingly being carried out using a model-based approach that leads naturally to a generalized least-squares (GLS) solution. While this method offers the advantages of being easier to audit and having general applicability to any form of comparison protocol, there is a lack of consensus over aspects of its implementation. Two significant results are presented that show the equivalence of three differing approaches discussed by or applied in comparisons run by Consultative Committees of the CIPM. Both results depend on a mathematical condition equivalent to the requirement that any two artefacts in the comparison are linked through a sequence of measurements of overlapping pairs of artefacts. The first result is that a GLS estimator excluding all sources of error common to all measurements of a participant is equal to the GLS estimator incorporating all sources of error, including those associated with any bias in the standards or procedures of the measuring laboratory. The second result identifies the component of uncertainty in the estimate of bias that arises from possible systematic effects in the participants' measurement standards and procedures. The expression so obtained is a generalization of an expression previously published for a one-artefact comparison with no inter-participant correlations, to one for a comparison comprising any number of repeat measurements of multiple artefacts and allowing for inter-laboratory correlations.

Comparison of infusion pumps calibration methods

NASA Astrophysics Data System (ADS)

Batista, Elsa; Godinho, Isabel; do Céu Ferreira, Maria; Furtado, Andreia; Lucas, Peter; Silva, Claudia

2017-12-01

Nowadays, several types of infusion pump are commonly used for drug delivery, such as syringe pumps and peristaltic pumps. These instruments present different measuring features and capacities according to their use and therapeutic application. In order to ensure the metrological traceability of these flow and volume measuring equipment, it is necessary to use suitable calibration methods and standards. Two different calibration methods can be used to determine the flow error of infusion pumps. One is the gravimetric method, considered as a primary method, commonly used by National Metrology Institutes. The other calibration method, a secondary method, relies on an infusion device analyser (IDA) and is typically used by hospital maintenance offices. The suitability of the IDA calibration method was assessed by testing several infusion instruments at different flow rates using the gravimetric method. In addition, a measurement comparison between Portuguese Accredited Laboratories and hospital maintenance offices was performed under the coordination of the Portuguese Institute for Quality, the National Metrology Institute. The obtained results were directly related to the used calibration method and are presented in this paper. This work has been developed in the framework of the EURAMET projects EMRP MeDD and EMPIR 15SIP03.

First Interlaboratory Comparison on Calibration of Temperature-Controlled Enclosures in Turkey

NASA Astrophysics Data System (ADS)

Uytun, A.; Kalemci, M.

2017-11-01

The number of accredited laboratories in the field of calibration of temperature-controlled enclosures has been increasing in Turkey. One of the main criteria demonstrating the competence of a calibration laboratory is successful participation in interlaboratory comparisons. Therefore, TUBITAK UME Temperature Laboratory organized the first interlaboratory comparison on "Calibration of Temperature-Controlled Enclosures" in Turkey as a pilot laboratory between January and November, 2013. Forty accredited laboratories which provide routine calibration services to the industry in this field participated in the comparison. The standards used during the comparison was a climatic chamber for the measurements at -40 {°}C, -20 {°}C, 40 {°}C and 100 {°}C and an oven for the measurements at 200 {°}C. The protocol of the comparison was prepared considering guide EURAMET cg-20 and BS EN/IEC standards 600068-3-5 and 600068-3-11. During the comparison measurements, each participant had the liberty to choose the most convenient calibration points in terms of their accreditation scope among the values mentioned above and carried out on-site measurements at UME. The details and the results of this comparison are given in the paper. Determination of the statistical consistency of the results with the uncertainties given by the participants can be assessed by the method of En value assessment for each laboratory. En values for all measurement results based on the results of pilot and participating laboratories were calculated.

Valx: A System for Extracting and Structuring Numeric Lab Test Comparison Statements from Text.

PubMed

Hao, Tianyong; Liu, Hongfang; Weng, Chunhua

2016-05-17

To develop an automated method for extracting and structuring numeric lab test comparison statements from text and evaluate the method using clinical trial eligibility criteria text. Leveraging semantic knowledge from the Unified Medical Language System (UMLS) and domain knowledge acquired from the Internet, Valx takes seven steps to extract and normalize numeric lab test expressions: 1) text preprocessing, 2) numeric, unit, and comparison operator extraction, 3) variable identification using hybrid knowledge, 4) variable - numeric association, 5) context-based association filtering, 6) measurement unit normalization, and 7) heuristic rule-based comparison statements verification. Our reference standard was the consensus-based annotation among three raters for all comparison statements for two variables, i.e., HbA1c and glucose, identified from all of Type 1 and Type 2 diabetes trials in ClinicalTrials.gov. The precision, recall, and F-measure for structuring HbA1c comparison statements were 99.6%, 98.1%, 98.8% for Type 1 diabetes trials, and 98.8%, 96.9%, 97.8% for Type 2 diabetes trials, respectively. The precision, recall, and F-measure for structuring glucose comparison statements were 97.3%, 94.8%, 96.1% for Type 1 diabetes trials, and 92.3%, 92.3%, 92.3% for Type 2 diabetes trials, respectively. Valx is effective at extracting and structuring free-text lab test comparison statements in clinical trial summaries. Future studies are warranted to test its generalizability beyond eligibility criteria text. The open-source Valx enables its further evaluation and continued improvement among the collaborative scientific community.

Optimization with artificial neural network systems - A mapping principle and a comparison to gradient based methods

NASA Technical Reports Server (NTRS)

Leong, Harrison Monfook

1988-01-01

General formulae for mapping optimization problems into systems of ordinary differential equations associated with artificial neural networks are presented. A comparison is made to optimization using gradient-search methods. The performance measure is the settling time from an initial state to a target state. A simple analytical example illustrates a situation where dynamical systems representing artificial neural network methods would settle faster than those representing gradient-search. Settling time was investigated for a more complicated optimization problem using computer simulations. The problem was a simplified version of a problem in medical imaging: determining loci of cerebral activity from electromagnetic measurements at the scalp. The simulations showed that gradient based systems typically settled 50 to 100 times faster than systems based on current neural network optimization methods.

SUPPLEMENTARY COMPARISON: APMP.PR-S1 comparison of irradiance responsivity of UVA detectors

NASA Astrophysics Data System (ADS)

Xu, Gan; Huang, Xuebo; Liu, Yuanjie

2007-01-01

APMP.PR-S1, a supplementary comparison of irradiance responsivity of UVA detectors, was carried out among seven national metrology institutes piloted by SPRING Singapore from 2003 to 2005. Two quantities, the narrow band UV (365 nm ± 5 nm) irradiance responsivity and the broad band UVA (315 nm-400 nm) irradiance responsivity of the transfer detectors, have been compared. Commercial UV source (medium pressure mercury short arc lamp) and UVA detectors were used as transfer standards in the comparison. Measurement results from participants were reported and their uncertainties associated with the comparison were analysed in this report. The method of weighted mean with cut-off was used to calculate the comparison reference values. The results from most participating labs lie within ±5% against the comparison reference values with a few exceptions. The degree of agreement of the comparison depends not only on the base scales of spectral responsivity and spectral irradiance of a laboratory, but also equally importantly on the method used for the measurement. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Comparison of methods to determine disk and heartwood areas

Treesearch

Michael C. Wiemann; John P. Brown; Neal D. Bennett

2002-01-01

The feasibility of using radius measurements on disks to determine cross-sectional areas of tree stems and the heartwood they contain was examined in sugar maple and red oak butt logs. Areas calculated from quadratic means of four stem radii and four heartwood radii were compared with areas measured with a planimeter. The lineal measurement method was less precise for...

Mathematics Curriculum Based Measurement to Predict State Test Performance: A Comparison of Measures and Methods

ERIC Educational Resources Information Center

Stevens, Olinger; Leigh, Erika

2012-01-01

Scope and Method of Study: The purpose of the study is to use an empirical approach to identify a simple, economical, efficient, and technically adequate performance measure that teachers can use to assess student growth in mathematics. The current study has been designed to expand the body of research for math CBM to further examine technical…

Lies, Damn Lies, and Statistics Revisited: A Comparison of Three Methods of Representing Change. AIR 1991 Annual Forum Paper.

ERIC Educational Resources Information Center

Pike, Gary R.

Because change is fundamental to education and the measurement of change assesses the quality and effectiveness of postsecondary education, this study examined three methods of measuring change: (1) gain scores; (2) residual scores; and (3) repeated measures. Data for the study was obtained from transcripts of 722 graduating seniors at the…

Radiometric calibration of SPOT 2 HRV - A comparison of three methods

NASA Technical Reports Server (NTRS)

Biggar, Stuart F.; Dinguirard, Magdeleine C.; Gellman, David I.; Henry, Patrice; Jackson, Ray D.; Moran, M. S.; Slater, Philip N.

1991-01-01

Three methods for determining an absolute radiometric calibration of a spacecraft optical sensor are compared. They are the well-known reflectance-based and radiance-based methods and a new method based on measurements of the ratio of diffuse-to-global irradiance at the ground. The latter will be described in detail and the comparison of the three approaches will be made with reference to the SPOT-2 HRV cameras for a field campaign 1990-06-19 through 1990-06-24 at the White Sands Missile Range in New Mexico.

Chemometric Methods to Quantify 1D and 2D NMR Spectral Differences Among Similar Protein Therapeutics.

PubMed

Chen, Kang; Park, Junyong; Li, Feng; Patil, Sharadrao M; Keire, David A

2018-04-01

NMR spectroscopy is an emerging analytical tool for measuring complex drug product qualities, e.g., protein higher order structure (HOS) or heparin chemical composition. Most drug NMR spectra have been visually analyzed; however, NMR spectra are inherently quantitative and multivariate and thus suitable for chemometric analysis. Therefore, quantitative measurements derived from chemometric comparisons between spectra could be a key step in establishing acceptance criteria for a new generic drug or a new batch after manufacture change. To measure the capability of chemometric methods to differentiate comparator NMR spectra, we calculated inter-spectra difference metrics on 1D/2D spectra of two insulin drugs, Humulin R® and Novolin R®, from different manufacturers. Both insulin drugs have an identical drug substance but differ in formulation. Chemometric methods (i.e., principal component analysis (PCA), 3-way Tucker3 or graph invariant (GI)) were performed to calculate Mahalanobis distance (D M ) between the two brands (inter-brand) and distance ratio (D R ) among the different lots (intra-brand). The PCA on 1D inter-brand spectral comparison yielded a D M value of 213. In comparing 2D spectra, the Tucker3 analysis yielded the highest differentiability value (D M  = 305) in the comparisons made followed by PCA (D M  = 255) then the GI method (D M  = 40). In conclusion, drug quality comparisons among different lots might benefit from PCA on 1D spectra for rapidly comparing many samples, while higher resolution but more time-consuming 2D-NMR-data-based comparisons using Tucker3 analysis or PCA provide a greater level of assurance for drug structural similarity evaluation between drug brands.

Developing a Measure of Wealth for Primary Student Families in a Developing Country: Comparison of Two Methods of Psychometric Calibration

ERIC Educational Resources Information Center

Griffin, Patrick

2005-01-01

This article compares the invariance properties of two methods of psychometric instrument calibration for the development of a measure of wealth among families of Grade 5 pupils in five provinces in Vietnam. The measure is based on self-reported lists of possessions in the home. Its stability has been measured over two time periods. The concept of…

Concentration Measurements in a Cold Flow Model Annular Combustor Using Laser Induced Fluorescence

NASA Technical Reports Server (NTRS)

Morgan, Douglas C.

1996-01-01

A nonintrusive concentration measurement method is developed for determining the concentration distribution in a complex flow field. The measurement method consists of marking a liquid flow with a water soluble fluorescent dye. The dye is excited by a two dimensional sheet of laser light. The fluorescent intensity is shown to be proportional to the relative concentration level. The fluorescent field is recorded on a video cassette recorder through a video camera. The recorded images are analyzed with image processing hardware and software to obtain intensity levels. Mean and root mean square (rms) values are calculated from these intensity levels. The method is tested on a single round turbulent jet because previous concentration measurements have been made on this configuration by other investigators. The previous results were used to comparison to qualify the current method. These comparisons showed that this method provides satisfactory results. 'Me concentration measurement system was used to measure the concentrations in the complex flow field of a model gas turbine annular combustor. The model annular combustor consists of opposing primary jets and an annular jet which discharges perpendicular to the primary jets. The mixing between the different jet flows can be visualized from the calculated mean and rms profiles. Concentration field visualization images obtained from the processing provide further qualitative information about the flow field.

Slump sitting X-ray of the lumbar spine is superior to the conventional flexion view in assessing lumbar spine instability.

PubMed

Hey, Hwee Weng Dennis; Lau, Eugene Tze-Chun; Lim, Joel-Louis; Choong, Denise Ai-Wen; Tan, Chuen-Seng; Liu, Gabriel Ka-Po; Wong, Hee-Kit

2017-03-01

Flexion radiographs have been used to identify cases of spinal instability. However, current methods are not standardized and are not sufficiently sensitive or specific to identify instability. This study aimed to introduce a new slump sitting method for performing lumbar spine flexion radiographs and comparison of the angular range of motions (ROMs) and displacements between the conventional method and this new method. This study used is a prospective study on radiological evaluation of the lumbar spine flexion ROMs and displacements using dynamic radiographs. Sixty patients were recruited from a single spine tertiary center. Angular and displacement measurements of lumbar spine flexion were carried out. Participants were randomly allocated into two groups: those who did the new method first, followed by the conventional method versus those who did the conventional method first, followed by the new method. A comparison of the angular and displacement measurements of lumbar spine flexion between the conventional method and the new method was performed and tested for superiority and non-inferiority. The measurements of global lumbar angular ROM were, on average, 17.3° larger (p<.0001) using the new slump sitting method compared with the conventional method. They were most significant at the levels of L3-L4, L4-L5, and L5-S1 (p<.0001, p<.0001 and p=.001, respectively). There was no significant difference between both methods when measuring lumbar displacements (p=.814). The new method of slump sitting dynamic radiograph was shown to be superior to the conventional method in measuring the angular ROM and non-inferior to the conventional method in the measurement of displacement. Copyright © 2016 Elsevier Inc. All rights reserved.

A comparison of five benchmarks

NASA Technical Reports Server (NTRS)

Huss, Janice E.; Pennline, James A.

1987-01-01

Five benchmark programs were obtained and run on the NASA Lewis CRAY X-MP/24. A comparison was made between the programs codes and between the methods for calculating performance figures. Several multitasking jobs were run to gain experience in how parallel performance is measured.

Comparison is key.

PubMed

Stone, Mark H; Stenner, A Jackson

2014-01-01

Several concepts from Georg Rasch's last papers are discussed. The key one is comparison because Rasch considered the method of comparison fundamental to science. From the role of comparison stems scientific inference made operational by a properly developed frame of reference producing specific objectivity. The exact specifications Rasch outlined for making comparisons are explicated from quotes, and the role of causality derived from making comparisons is also examined. Understanding causality has implications for what can and cannot be produced via Rasch measurement. His simple examples were instructive, but the implications are far reaching upon first establishing the key role of comparison.

Subjective Memory in a National Sample: Predicting Psychological Well-Being

PubMed Central

Hill, Nikki; McDermott, Caroline

2017-01-01

Background Individual perception of memory performance (i.e., subjective memory) is assessed using a variety of approaches. This article focuses on two such approaches: self-comparison assessments that attempt to capture changes in memory ability over a period of time, and age-anchored comparisons that assess how an individual perceives their memory in relation to others their age. These different types of assessment may relate to psychological well-being differently due to the underlying mechanisms of assessment. Objective The purpose of these analyses is to examine two measures of subjective memory (i.e., a self-comparison measure and an age-anchored comparison measure) as predictors of psychological well-being among adults in mid- and late life. Methods Participants (n=3,434) in the Midlife in the United States Study completed measures of subjective memory, depressive affect, and life satisfaction. Structural equation modeling was used to examine whether self-comparison and age-anchored comparison measures had differential predictive utility of on psychological well-being. Results Higher age-anchored comparison ratings were related to higher life satisfaction scores. There was a significant interaction between the two items such that individuals with lower ratings on both subjective memory measures had the poorest outcomes. Additionally, age-anchored comparisons interacted with age: older adults had the poorest outcomes when they reported poorer age-anchored comparisons. Conclusion These findings highlight the importance of precise measurement in the consideration of subjective memory. How an individual was asked to rate his or her perception of memory influenced the relationships between subjective memory and psychological well-being. This study contributes valuable insight into the importance of the assessment models of subjective memory. PMID:28441647

Report of secondary flows, boundary layers, turbulence and wave team, report 1

NASA Technical Reports Server (NTRS)

Scoggins, J. R.; Fitzjarrald, D.; Doviak, R.; Cliff, W.

1980-01-01

General criteria for a flight test option are that: (1) there be a good opportunity for comparison with other measurement techniques; (2) the flow to be measured is of considerable scientific or practical interest; and (3) the airborne laser Doppler system is well suited to measure the required quantities. The requirement for comparison, i.e., ground truth, is particularly important because this is the first year of operation for the system. It is necessary to demonstrate that the system does actually measure the winds and compare the results with other methods to provide a check on the system error analysis. The uniqueness of the laser Doppler system precludes any direct comparison, but point measurements from tower mounted wind sensors and two dimensional fields obtained from radars with substantially different sampling volumes are quite useful.

Evaluation and Comparison of Chemiluminescence and UV Photometric Methods for Measuring Ozone Concentrations in Ambient Air

EPA Science Inventory

The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C₂H₄) and any ozone (O₃) that may be p...

Preliminary comparative assessment of PM10 hourly measurement results from new monitoring stations type using stochastic and exploratory methodology and models

NASA Astrophysics Data System (ADS)

Czechowski, Piotr Oskar; Owczarek, Tomasz; Badyda, Artur; Majewski, Grzegorz; Rogulski, Mariusz; Ogrodnik, Paweł

2018-01-01

The paper presents selected preliminary stage key issues proposed extended equivalence measurement results assessment for new portable devices - the comparability PM10 concentration results hourly series with reference station measurement results with statistical methods. In article presented new portable meters technical aspects. The emphasis was placed on the comparability the results using the stochastic and exploratory methods methodology concept. The concept is based on notice that results series simple comparability in the time domain is insufficient. The comparison of regularity should be done in three complementary fields of statistical modeling: time, frequency and space. The proposal is based on model's results of five annual series measurement results new mobile devices and WIOS (Provincial Environmental Protection Inspectorate) reference station located in Nowy Sacz city. The obtained results indicate both the comparison methodology completeness and the high correspondence obtained new measurements results devices with reference.

Comparison of Enzymatic Assay for HBA1C Measurement (Abbott Architect) With Capillary Electrophoresis (Sebia Minicap Flex Piercing Analyser).

PubMed

Tesija Kuna, Andrea; Dukic, Kristina; Nikolac Gabaj, Nora; Miler, Marijana; Vukasovic, Ines; Langer, Sanja; Simundic, Ana-Maria; Vrkic, Nada

2018-03-08

To compare the analytical performances of the enzymatic method (EM) and capillary electrophoresis (CE) for hemoglobin A1c (HbA1c) measurement. Imprecision, carryover, stability, linearity, method comparison, and interferences were evaluated for HbA1c via EM (Abbott Laboratories, Inc) and CE (Sebia). Both methods have shown overall within-laboratory imprecision of less than 3% for International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) units (<2% National Glycohemoglobin Standardization Program [NGSP] units). Carryover effects were within acceptable criteria. The linearity of both methods has proven to be excellent (R2 = 0.999). Significant proportional and constant difference were found for EM, compared with CE, but were not clinically relevant (<5 mmol/mol; NGSP <0.5%). At the clinically relevant HbA1c concentration, stability observed with both methods was acceptable (bias, <3%). Triglyceride levels of 8.11 mmol per L or greater showed to interfere with EM and fetal hemoglobin (HbF) of 10.6% or greater with CE. The enzymatic method proved to be comparable to the CE method in analytical performances; however, certain interferences can influence the measurements of each method.

Final report of the key comparison APMP.QM-K91: APMP comparison on pH measurement of phthalate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Ketrin, Rosi; Nuryatini; Thanh, Ngo Huy; Truong Chinh, Nguyen; Vospelova, Alena; Bastkowski, Frank; Sander, Beatrice; Matzke, Jessica; Prokunin, Sergey; Frolov, Dmitry; Aprelev, Alexey; Dobrovolskiy, Vladimir; Uysal, Emrah; Liv, Lokman; Velina Lara-Manzano, Judith; Montero-Ruiz, Jazmin; Ortiz-Aparicio, JosÉ Luis; Ticona Canaza, Galia; Anuar Mohd Amin, Khirul; Abd Kadir, Haslina; Bakovets, Nickolay; Wong, Siu-Kay; Lam, Wai-Hing

2017-01-01

The APMP.QM-K91 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phthalate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan at the APMP-TCQM meeting held September 22-23, 2014. After approval by TCQM, the comparison has been conducted by NMIJ. The comparison is a key comparison following CCQM-K91. The comparison material was a phthalate buffer of pH around 4.0 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the third APMP key comparison on pH measurement and the fifth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006, APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011 and APMP.QM-K19/APMP.QM-P25 (a borate buffer) in 2013-2014. The results can be used further by any participant to support its CMC claim at least for a phthalate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Report of the key comparison APMP.QM-K19. APMP comparison on pH measurement of borate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Obromsook, Krairerk; Tangpaisarnkul, Nongluck; Rodruangthum, Patumporn; Wong, Siu-Kay; Lam, Wai-Hing; Zakaria, Osman; Anuar Mohd. Amin, Khirul; Thanh, Ngo Huy; Máriássy, Michal; Vyskocil, Leos; Hankova, Zuzana; Fisicaro, Paola; Stoica, Daniela; Singh, Nahar; Soni, Daya; Ticona Canaza, Galia; Kutovoy, Viatcheslav; Barbieri Gonzaga, Fabiano; Dias, Júlio Cesar; Vospelova, Alena; Bakovets, Nickolay; Zhanasbayeva, Bibinur

2015-01-01

The APMP.QM-K19 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a borate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan (NMIJ) and the National Institute of Metrology (Thailand) (NIMT) at the APMP-TCQM meeting held 26-27 November 2012. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K19 and CCQM-K19.1. The comparison material was a borate buffer of pH around 9.2 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the second APMP key comparison on pH measurement and the fourth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006 and APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011. The results can be used further by any participant to support its CMC claim at least for a borate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of direct and indirect methods for assessing leaf area index across a tropical rain forest landscape

Treesearch

Paulo C. Olivas; Steven F. Oberbauer; David B. Clark; Deborah A. Clark; Michael G. Ryan; Joseph J. O' Brien; Harlyn Ordonez

2013-01-01

Many functional properties of forests depend on the leaf area; however, measuring leaf area is not trivial in tall evergreen vegetation. As a result, leaf area is generally estimated indirectly by light absorption methods. These indirect methods are widely used, but have never been calibrated against direct measurements in tropical rain forests, either at point or...

Final report of the key comparison CCQM-K106: Pb, As and Hg measurements in cosmetic (cream)

NASA Astrophysics Data System (ADS)

Wang, Jun; Wang, Qian; Yamani, Randa Nasr Ahmed; Shehata, Adel B.; Jacimovic, Radojko; Pavlin, Majda; Horvat, Milena; Tsoi, Y. P.; Tsang, C. K.; Shin, Richard; Chailap, Benjamat; Yafa, Charun; Caciano de Sena, Rodrigo; de Almeida, Marcelo; Yim, Yong-Hyeon; Lee, Kyoung-Seok; Heun Kim, Sook; Konopelko, Leonid; Ari, Betül; Tokman, Nilgün; Rienitz, Olaf; Jaehrling, Reinhard; Pape, Carola

2015-01-01

Cosmetics are used in practically all walks of life as a means of improving skin and beautifying complexion. In recent years, more and more attention has been paid to the cosmetic safety. In response to the cosmetic safety issue, the accurate measurement of the heavy metals in cosmetics is, therefore, particularly important. NMIs from different countries should establish their chemical metrology traceability system in this area, which includes both measurement methods research and certain CRMs development. It should be noted that because the matrix of many cosmetics is complex and the contents of the heavy metals are relatively low, it still is a challenging task to measure the analytes with high accuracy and precision. CCQM-K106 followed up CCQM pilot study 'CCQM-P128: Pb, As measurements in cosmetic (cream)' coordinated by the National Institute of Metrology, China (NIM) in 2009. The cream was selected as the testing material, which is widely used as a daily skin care worldwide. This is the first CCQM key comparison regarding the measurement of toxic metal elements with the cosmetic matrix, which includes pure water, liquid paraffin, silicone oil, synthetic squalane, hyaluronic acid, glycerin, propylene glycol, allantoin, preservative and so on. The aim of the CCQM-K106 is to demonstrate the capability of participating NMIs and designated institutes in measuring the contents of poisonous elements, including lead, arsenic and mercury in a cosmetic sample (cream), and support CMC claims relating to inorganic elements in cosmetic materials and similar chemical industry products. The cream matrix sample was prepared under the guidance of professional technicians. The formula of the cream was carefully chosen to match with a real cosmetic. The homogeneity and stability level of Pb, As and Hg in the cream sample were fit for the objective of the comparison. Each participant received two numbered bottles containing about 5g samples in each bottle. The instruction relating to CCQM-K106 was sent to each participant by e-mail, which consisted of technical protocol, results report form and inorganic core capabilities tables. The results were reported as mass faction (mg/kg). Calculation of the uncertainty expressed as a combined standard uncertainty and an expanded uncertainty at 95% confidence. In order to allow a sufficient evaluation of the comparison, the report was required to include a detailed description of the applied method of measurement, information about sample digestion and preparation, information about the reference material used for calibration. The methods of measurement were free to be selected by the participants. For the sample treatment, most of the participants used microwave digestion method. For instrumental determination, a variety of techniques such as ICP-MS, AAS, INAA were adopted by the participants. Most participants choose ID-ICP-MS method to measure Pb and Hg, which showed the better performance in terms of consistency and reliability of the measurement results. The reference mass fraction values and associated uncertainties were calculated by different statistic ways. As the result, the median and uncertainty of median were proposed as the key comparison reference value (KCRV) and its associated key comparison reference uncertainty after removal of suspected extreme values. In general, the performances of the majority of the CCQM-K106 participants are excellent, illustrating their measurement capability for Pb, As and Hg in a complex greasy matrix. The results can be used further by any participant to support its CMC claim at least for a borate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Sensitivity and comparison evaluation of Saturn 5 liquid penetrants

NASA Technical Reports Server (NTRS)

Jones, G. H.

1973-01-01

Results of a sensitivity and comparison evaluation performed on six liquid penetrants that were used on the Saturn 5 vehicle and other space hardware to detect surface discontinuities are described. The relationship between penetrant materials and crack definition capabilities, the optimum penetrant materials evaluation method, and the optimum measurement methods for crack dimensions were investigated. A unique method of precise developer thickness control was envolved, utilizing clear radiographic film and a densitometer. The method of evaluation included five aluminum alloy, 2219-T87, specimens that were heated and then quenched in cold water to produce cracks. The six penetrants were then applied, one at a time, and the crack indications were counted and recorded for each penetrant for comparison purposes. Measurements were made by determining the visual crack indications per linear inch and then sectioning the specimens for a metallographic count of the cracks present. This method provided a numerical approach for assigning a sensitivity index number to the penetrants. Of the six penetrants evaluated, two were not satisfactory (one was not sufficiently sensitive and the other was to sensitive, giving false indications). The other four were satisfactory with approximately the same sensitivity in the range of 78 to 80.5 percent of total cracks detected.

International Comparison of Methane-Stabilized He-Ne Lasers

NASA Astrophysics Data System (ADS)

Koshelyaevskii, N. B.; Oboukhov, A.; Tatarenkov, V. M.; Titov, A. N.; Chartier, J.-M.; Felder, R.

1981-01-01

Two portable methane-stabilized lasers designed at BIPM have been compared with a type a stationary Soviet device developed in VNIIFTRI1. This comparison is one of a series aimed at establishing the coherence of laser wavelength and frequency measurements throughout the world and took place in June 1979. The VNIIFTRI and BIPM lasers using different methods of stabilization, have different optical and mechanical designs and laser tubes. The results of previous measurements, made in VNIIFTRI, of the most important frequency shifts for Soviet lasers together with a method of reproducing their frequency which leads to a precision of 1.10-12 are also presented.

Comparison of Methods for Evaluating Urban Transportation Alternatives

DOT National Transportation Integrated Search

1975-02-01

The objective of the report was to compare five alternative methods for evaluating urban transportation improvement options: unaided judgmental evaluation cost-benefit analysis, cost-effectiveness analysis based on a single measure of effectiveness, ...

Comparison of measured efficiencies of nine turbine designs with efficiencies predicted by two empirical methods

NASA Technical Reports Server (NTRS)

English, Robert E; Cavicchi, Richard H

1951-01-01

Empirical methods of Ainley and Kochendorfer and Nettles were used to predict performances of nine turbine designs. Measured and predicted performances were compared. Appropriate values of blade-loss parameter were determined for the method of Kochendorfer and Nettles. The measured design-point efficiencies were lower than predicted by as much as 0.09 (Ainley and 0.07 (Kochendorfer and Nettles). For the method of Kochendorfer and Nettles, appropriate values of blade-loss parameter ranged from 0.63 to 0.87 and the off-design performance was accurately predicted.

Extraction and analysis of the image in the sight field of comparison goniometer to measure IR mirrors assembly

NASA Astrophysics Data System (ADS)

Wang, Zhi-shan; Zhao, Yue-jin; Li, Zhuo; Dong, Liquan; Chu, Xuhong; Li, Ping

2010-11-01

The comparison goniometer is widely used to measure and inspect small angle, angle difference, and parallelism of two surfaces. However, the common manner to read a comparison goniometer is to inspect the ocular of the goniometer by one eye of the operator. To read an old goniometer that just equips with one adjustable ocular is a difficult work. In the fabrication of an IR reflecting mirrors assembly, a common comparison goniometer is used to measure the angle errors between two neighbor assembled mirrors. In this paper, a quick reading technique image-based for the comparison goniometer used to inspect the parallelism of mirrors in a mirrors assembly is proposed. One digital camera, one comparison goniometer and one set of computer are used to construct a reading system, the image of the sight field in the comparison goniometer will be extracted and recognized to get the angle positions of the reflection surfaces to be measured. In order to obtain the interval distance between the scale lines, a particular technique, left peak first method, based on the local peak values of intensity in the true color image is proposed. A program written in VC++6.0 has been developed to perform the color digital image processing.

APMP supplementary comparison (APMP.L-S8) measurement of flatness of optical flat by interferometry

NASA Astrophysics Data System (ADS)

Buajarern, J.; Bitou, Y.; Zi, X.; Zhao, L.; Swift, N.; Agarwal, A.; Hungwe, F.

2018-01-01

A reginal supplementary comparison, APMP.L-S8, was started in 2015 to demonstrate the equivalence of routine calibration services offered by NMIs to clients. Participants in this APMP.L-S8 comparison agreed to apply interferometric method for flatness measurement of the optical flats. There are two configurations of flatness interferometer used in this comparison, vertical type and horizontal type. There are seven laboratories from NMIs participated this supplementary comparison which included NIMT, NMIJ, NIM, NMC/A*STAR, MSL, NPLI and NMISA. This report describes the measurement results of two optical flats, diameter of 70 mm and 160 mm. The calibrations of this comparison were carried out by participants during the period from July 2015 to September 2016. The results show that there is a degree of equivalence below 1 for all measurands. Hence, there is a close agreement between the measurements from all participants. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of Five System Identification Algorithms for Rotorcraft Higher Harmonic Control

NASA Technical Reports Server (NTRS)

Jacklin, Stephen A.

1998-01-01

This report presents an analysis and performance comparison of five system identification algorithms. The methods are presented in the context of identifying a frequency-domain transfer matrix for the higher harmonic control (HHC) of helicopter vibration. The five system identification algorithms include three previously proposed methods: (1) the weighted-least- squares-error approach (in moving-block format), (2) the Kalman filter method, and (3) the least-mean-squares (LMS) filter method. In addition there are two new ones: (4) a generalized Kalman filter method and (5) a generalized LMS filter method. The generalized Kalman filter method and the generalized LMS filter method were derived as extensions of the classic methods to permit identification by using more than one measurement per identification cycle. Simulation results are presented for conditions ranging from the ideal case of a stationary transfer matrix and no measurement noise to the more complex cases involving both measurement noise and transfer-matrix variation. Both open-loop identification and closed- loop identification were simulated. Closed-loop mode identification was more challenging than open-loop identification because of the decreasing signal-to-noise ratio as the vibration became reduced. The closed-loop simulation considered both local-model identification, with measured vibration feedback and global-model identification with feedback of the identified uncontrolled vibration. The algorithms were evaluated in terms of their accuracy, stability, convergence properties, computation speeds, and relative ease of implementation.

What is the best method for assessing lower limb force-velocity relationship?

PubMed

Giroux, C; Rabita, G; Chollet, D; Guilhem, G

2015-02-01

This study determined the concurrent validity and reliability of force, velocity and power measurements provided by accelerometry, linear position transducer and Samozino's methods, during loaded squat jumps. 17 subjects performed squat jumps on 2 separate occasions in 7 loading conditions (0-60% of the maximal concentric load). Force, velocity and power patterns were averaged over the push-off phase using accelerometry, linear position transducer and a method based on key positions measurements during squat jump, and compared to force plate measurements. Concurrent validity analyses indicated very good agreement with the reference method (CV=6.4-14.5%). Force, velocity and power patterns comparison confirmed the agreement with slight differences for high-velocity movements. The validity of measurements was equivalent for all tested methods (r=0.87-0.98). Bland-Altman plots showed a lower agreement for velocity and power compared to force. Mean force, velocity and power were reliable for all methods (ICC=0.84-0.99), especially for Samozino's method (CV=2.7-8.6%). Our findings showed that present methods are valid and reliable in different loading conditions and permit between-session comparisons and characterization of training-induced effects. While linear position transducer and accelerometer allow for examining the whole time-course of kinetic patterns, Samozino's method benefits from a better reliability and ease of processing. © Georg Thieme Verlag KG Stuttgart · New York.

Method of determining pH by the alkaline absorption of carbon dioxide

DOEpatents

Hobbs, David T.

1992-01-01

A method for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction.

Viscosity measuring using microcantilevers

DOEpatents

Oden, Patrick Ian

2001-01-01

A method for the measurement of the viscosity of a fluid uses a micromachined cantilever mounted on a moveable base. As the base is rastered while in contact with the fluid, the deflection of the cantilever is measured and the viscosity determined by comparison with standards.

High dose rate brachytherapy source measurement intercomparison.

PubMed

Poder, Joel; Smith, Ryan L; Shelton, Nikki; Whitaker, May; Butler, Duncan; Haworth, Annette

2017-06-01

This work presents a comparison of air kerma rate (AKR) measurements performed by multiple radiotherapy centres for a single HDR 192 Ir source. Two separate groups (consisting of 15 centres) performed AKR measurements at one of two host centres in Australia. Each group travelled to one of the host centres and measured the AKR of a single 192 Ir source using their own equipment and local protocols. Results were compared to the 192 Ir source calibration certificate provided by the manufacturer by means of a ratio of measured to certified AKR. The comparisons showed remarkably consistent results with the maximum deviation in measurement from the decay-corrected source certificate value being 1.1%. The maximum percentage difference between any two measurements was less than 2%. The comparisons demonstrated the consistency of well-chambers used for 192 Ir AKR measurements in Australia, despite the lack of a local calibration service, and served as a valuable focal point for the exchange of ideas and dosimetry methods.

Differential Item Functioning Detection Across Two Methods of Defining Group Comparisons

PubMed Central

Sari, Halil Ibrahim

2014-01-01

This study compares two methods of defining groups for the detection of differential item functioning (DIF): (a) pairwise comparisons and (b) composite group comparisons. We aim to emphasize and empirically support the notion that the choice of pairwise versus composite group definitions in DIF is a reflection of how one defines fairness in DIF studies. In this study, a simulation was conducted based on data from a 60-item ACT Mathematics test (ACT; Hanson & Béguin). The unsigned area measure method (Raju) was used as the DIF detection method. An application to operational data was also completed in the study, as well as a comparison of observed Type I error rates and false discovery rates across the two methods of defining groups. Results indicate that the amount of flagged DIF or interpretations about DIF in all conditions were not the same across the two methods, and there may be some benefits to using composite group approaches. The results are discussed in connection to differing definitions of fairness. Recommendations for practice are made. PMID:29795837

A Conceptual Approach to Assimilating Remote Sensing Data to Improve Soil Moisture Profile Estimates in a Surface Flux/Hydrology Model. 2; Aggregation

NASA Technical Reports Server (NTRS)

Schamschula, Marius; Crosson, William L.; Inguva, Ramarao; Yates, Thomas; Laymen, Charles A.; Caulfield, John

1998-01-01

This is a follow up on the preceding presentation by Crosson. The grid size for remote microwave measurements is much coarser than the hydrological model computational grids. To validate the hydrological models with measurements we propose mechanisms to aggregate the hydrological model outputs for soil moisture to allow comparison with measurements. Weighted neighborhood averaging methods are proposed to facilitate the comparison. We will also discuss such complications as misalignment, rotation and other distortions introduced by a generalized sensor image.

A comparison of latent class, K-means, and K-median methods for clustering dichotomous data.

PubMed

Brusco, Michael J; Shireman, Emilie; Steinley, Douglas

2017-09-01

The problem of partitioning a collection of objects based on their measurements on a set of dichotomous variables is a well-established problem in psychological research, with applications including clinical diagnosis, educational testing, cognitive categorization, and choice analysis. Latent class analysis and K-means clustering are popular methods for partitioning objects based on dichotomous measures in the psychological literature. The K-median clustering method has recently been touted as a potentially useful tool for psychological data and might be preferable to its close neighbor, K-means, when the variable measures are dichotomous. We conducted simulation-based comparisons of the latent class, K-means, and K-median approaches for partitioning dichotomous data. Although all 3 methods proved capable of recovering cluster structure, K-median clustering yielded the best average performance, followed closely by latent class analysis. We also report results for the 3 methods within the context of an application to transitive reasoning data, in which it was found that the 3 approaches can exhibit profound differences when applied to real data. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Comparison of EPA Method 1615 RT-qPCR Assays in Standard and Kit Format

EPA Science Inventory

EPA Method 1615 contains protocols for measuring enterovirus and norovirus by reverse transcription quantitative polymerase chain reaction. A commercial kit based upon these protocols was designed and compared to the method's standard approach. Reagent grade, secondary effluent, ...

Measurement correction method for force sensor used in dynamic pressure calibration based on artificial neural network optimized by genetic algorithm

NASA Astrophysics Data System (ADS)

Gu, Tingwei; Kong, Deren; Shang, Fei; Chen, Jing

2017-12-01

We present an optimization algorithm to obtain low-uncertainty dynamic pressure measurements from a force-transducer-based device. In this paper, the advantages and disadvantages of the methods that are commonly used to measure the propellant powder gas pressure, the applicable scope of dynamic pressure calibration devices, and the shortcomings of the traditional comparison calibration method based on the drop-weight device are firstly analysed in detail. Then, a dynamic calibration method for measuring pressure using a force sensor based on a drop-weight device is introduced. This method can effectively save time when many pressure sensors are calibrated simultaneously and extend the life of expensive reference sensors. However, the force sensor is installed between the drop-weight and the hammerhead by transition pieces through the connection mode of bolt fastening, which causes adverse effects such as additional pretightening and inertia forces. To solve these effects, the influence mechanisms of the pretightening force, the inertia force and other influence factors on the force measurement are theoretically analysed. Then a measurement correction method for the force measurement is proposed based on an artificial neural network optimized by a genetic algorithm. The training and testing data sets are obtained from calibration tests, and the selection criteria for the key parameters of the correction model is discussed. The evaluation results for the test data show that the correction model can effectively improve the force measurement accuracy of the force sensor. Compared with the traditional high-accuracy comparison calibration method, the percentage difference of the impact-force-based measurement is less than 0.6% and the relative uncertainty of the corrected force value is 1.95%, which can meet the requirements of engineering applications.

Reliability and validity in measurement of true humeral retroversion by a three-dimensional cylinder fitting method.

PubMed

Saka, Masayuki; Yamauchi, Hiroki; Hoshi, Kenji; Yoshioka, Toru; Hamada, Hidetoshi; Gamada, Kazuyoshi

2015-05-01

Humeral retroversion is defined as the orientation of the humeral head relative to the distal humerus. Because none of the previous methods used to measure humeral retroversion strictly follow this definition, values obtained by these techniques vary and may be biased by morphologic variations of the humerus. The purpose of this study was 2-fold: to validate a method to define the axis of the distal humerus with a virtual cylinder and to establish the reliability of 3-dimensional (3D) measurement of humeral retroversion by this cylinder fitting method. Humeral retroversion in 14 baseball players (28 humeri) was measured by the 3D cylinder fitting method. The root mean square error was calculated to compare values obtained by a single tester and by 2 different testers using the embedded coordinate system. To establish the reliability, intraclass correlation coefficient (ICC) and precision (standard error of measurement [SEM]) were calculated. The root mean square errors for the humeral coordinate system were <1.0 mm/1.0° for comparison of all translations/rotations obtained by a single tester and <1.0 mm/2.0° for comparison obtained by 2 different testers. Assessment of reliability and precision of the 3D measurement of retroversion yielded an intratester ICC of 0.99 (SEM, 1.0°) and intertester ICC of 0.96 (SEM, 2.8°). The error in measurements obtained by a distal humerus cylinder fitting method was small enough not to affect retroversion measurement. The 3D measurement of retroversion by this method provides excellent intratester and intertester reliability. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

International Airline Quality Measurement

DOT National Transportation Integrated Search

1998-01-01

Historically, airline quality has been measured through the use of surveys that ask the consumers to make a comparison between expectations and outcomes. This method was informative but very cumbersome in a rapidly changing environment. This paper ou...

A method of reconstructing the spatial measurement network by mobile measurement transmitter for shipbuilding

NASA Astrophysics Data System (ADS)

Guo, Siyang; Lin, Jiarui; Yang, Linghui; Ren, Yongjie; Guo, Yin

2017-07-01

The workshop Measurement Position System (wMPS) is a distributed measurement system which is suitable for the large-scale metrology. However, there are some inevitable measurement problems in the shipbuilding industry, such as the restriction by obstacles and limited measurement range. To deal with these factors, this paper presents a method of reconstructing the spatial measurement network by mobile transmitter. A high-precision coordinate control network with more than six target points is established. The mobile measuring transmitter can be added into the measurement network using this coordinate control network with the spatial resection method. This method reconstructs the measurement network and broadens the measurement scope efficiently. To verify this method, two comparison experiments are designed with the laser tracker as the reference. The results demonstrate that the accuracy of point-to-point length is better than 0.4mm and the accuracy of coordinate measurement is better than 0.6mm.

Comparison of Measured Flapwise Structural Bending Moments on a Teetering Rotor Blade With Results Calculated From the Measured Pressure Distribution

NASA Technical Reports Server (NTRS)

Mayo, Alton P.

1959-01-01

Flapwise bending moments were calculated for a teetering rotor blade using a reasonably rapid theoretical method in which airloads obtained from wind-tunnel tests were employed. The calculated moments agreed reasonably well with those measured with strain gages under the same test conditions. The range of the tests included one hovering and two forward-flight conditions. The rotor speed for the test was very near blade resonance, and difficult-to-calculate resonance effects apparently were responsible for the largest differences between the calculated and measured harmonic components of blade bending moments. These differences, moreover, were largely nullified when the harmonic components were combined to give a comparison of the calculated and measured blade total- moment time histories. The degree of agreement shown is therefore considered adequate to warrant the use of the theoretical method in establishing and applying methods of prediction of rotor-blade fatigue loads. At the same time, the validity of the experimental methods of obtaining both airload and blade stress measurement is also indicated to be adequate for use in establishing improved methods for prediction of rotor-blade fatigue loads during the design stage. The blade stiffnesses and natural frequencies were measured and found to be in close agreement with calculated values; however, for a condition of blade resonance the use of the experimental stiffness values resulted in better agreement between calculated and measured blade stresses.

Objective comparison of particle tracking methods.

PubMed

Chenouard, Nicolas; Smal, Ihor; de Chaumont, Fabrice; Maška, Martin; Sbalzarini, Ivo F; Gong, Yuanhao; Cardinale, Janick; Carthel, Craig; Coraluppi, Stefano; Winter, Mark; Cohen, Andrew R; Godinez, William J; Rohr, Karl; Kalaidzidis, Yannis; Liang, Liang; Duncan, James; Shen, Hongying; Xu, Yingke; Magnusson, Klas E G; Jaldén, Joakim; Blau, Helen M; Paul-Gilloteaux, Perrine; Roudot, Philippe; Kervrann, Charles; Waharte, François; Tinevez, Jean-Yves; Shorte, Spencer L; Willemse, Joost; Celler, Katherine; van Wezel, Gilles P; Dan, Han-Wei; Tsai, Yuh-Show; Ortiz de Solórzano, Carlos; Olivo-Marin, Jean-Christophe; Meijering, Erik

2014-03-01

Particle tracking is of key importance for quantitative analysis of intracellular dynamic processes from time-lapse microscopy image data. Because manually detecting and following large numbers of individual particles is not feasible, automated computational methods have been developed for these tasks by many groups. Aiming to perform an objective comparison of methods, we gathered the community and organized an open competition in which participating teams applied their own methods independently to a commonly defined data set including diverse scenarios. Performance was assessed using commonly defined measures. Although no single method performed best across all scenarios, the results revealed clear differences between the various approaches, leading to notable practical conclusions for users and developers.

Comparison of micrometeorological techniques in measuring gas emissions from waste lagoons

USDA-ARS?s Scientific Manuscript database

In this study, we evaluated and compared the accuracies of two micrometeorological methods using open-path tunable diode laser absorption spectrometers; vertical radial plume mapping method and the inverse dispersion model method. The accuracy of these two methods was evaluated using a 45m x 45m p...

Comparison of micrometeorological techniques in measuring gas emissions from waste lagoons

USDA-ARS?s Scientific Manuscript database

In this study, we evaluated and compared the accuracies of two micrometeorological methods using open-path tunable diode laser absorption spectrometers; vertical radial plume mapping method (US EPA OTM-10) and the inverse dispersion model method. The accuracy of these two methods was evaluated usin...

AN ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) METHOD FOR MONITORING 2,4 DICHLOROPHENOXYACETIC ACID (2,4-D) EXPOSURES

EPA Science Inventory

Abstract describes a streamlined ELISA method developed to quantitatively measure 2,4-D in human urine samples. Method development steps and comparison with gas chromatography/mass spectrometry are presented. Results indicated that the ELISA method could be used as a high throu...

Mechanical testing of internal fixation devices: A theoretical and practical examination of current methods.

PubMed

Grant, Caroline A; Schuetz, Michael; Epari, Devakar

2015-11-26

Successful healing of long bone fractures is dependent on the mechanical environment created within the fracture, which in turn is dependent on the fixation strategy. Recent literature reports have suggested that locked plating devices are too stiff to reliably promote healing. However, in vitro testing of these devices has been inconsistent in both method of constraint and reported outcomes, making comparisons between studies and the assessment of construct stiffness problematic. Each of the methods previously used in the literature were assessed for their effect on the bending of the sample and concordant stiffness. The choice of outcome measures used in in vitro fracture studies was also assessed. Mechanical testing was conducted on seven hole locked plated constructs in each method for comparison. Based on the assessment of each method the use of spherical bearings, ball joints or similar is suggested at both ends of the sample. The use of near and far cortex movement was found to be more comprehensive and more accurate than traditional centrally calculated interfragmentary movement values; stiffness was found to be highly susceptible to the accuracy of deformation measurements and constraint method, and should only be used as a within study comparison method. The reported stiffness values of locked plate constructs from in vitro mechanical testing is highly susceptible to testing constraints and output measures, with many standard techniques overestimating the stiffness of the construct. This raises the need for further investigation into the actual mechanical behaviour within the fracture gap of these devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measuring the Earth's Magnetic Field in a Laboratory

ERIC Educational Resources Information Center

Cartacci, A.; Straulino, S.

2008-01-01

Two methods for measuring the Earth's magnetic field are described. In the former, according to Gauss, the Earth's magnetic field is compared with that of a permanent magnet; in the latter, a well-known method, the comparison is made with the magnetic field generated by a current. As all the used instruments are available off the shelf, both…

A Comparison of Measurement Equivalence Methods Based on Confirmatory Factor Analysis and Item Response Theory.

ERIC Educational Resources Information Center

Flowers, Claudia P.; Raju, Nambury S.; Oshima, T. C.

Current interest in the assessment of measurement equivalence emphasizes two methods of analysis, linear, and nonlinear procedures. This study simulated data using the graded response model to examine the performance of linear (confirmatory factor analysis or CFA) and nonlinear (item-response-theory-based differential item function or IRT-Based…

Comparison of sprinkler droplet size and velocity measurements using a laser precipitation meter and photographic method

USDA-ARS?s Scientific Manuscript database

Kinetic energy of water droplets has a substantial effect on development of a soil surface seal and infiltration rate of bare soil. Methods for measuring sprinkler droplet size and velocity needed to calculate droplet kinetic energy have been developed and tested over the past 50 years, each with ad...

A Comparison of Vector and Raster GIS Methods for Calculating Landscape Metrics Used in Environmental Assessments

Treesearch

Timothy G. Wade; James D. Wickham; Maliha S. Nash; Anne C. Neale; Kurt H. Riitters; K. Bruce Jones

2003-01-01

AbstractGIS-based measurements that combine native raster and native vector data are commonly used in environmental assessments. Most of these measurements can be calculated using either raster or vector data formats and processing methods. Raster processes are more commonly used because they can be significantly faster computationally...

Integrated method for chaotic time series analysis

DOEpatents

Hively, Lee M.; Ng, Esmond G.

1998-01-01

Methods and apparatus for automatically detecting differences between similar but different states in a nonlinear process monitor nonlinear data. Steps include: acquiring the data; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis; obtaining time serial trends in the nonlinear measures; and determining by comparison whether differences between similar but different states are indicated.

Solid Propellant Test Motor Scaling

DTIC Science & Technology

2001-09-01

50 Figure 40. Comparison of Measured and Calculated Strand and Small Motor Burning Rates for Fundamental Studies of HTPB /AP Smokeless...Propellants...................................... 51 Figure 41. Agreement Between 2x4 Motor and Strand Burning Rate Data for Non-aluminized HTPB /AP...58 Figure 51. Comparison Between Results Obtained with Ultrasonic Method and Standard

Research report on: Specialized physiological studies in support of manned space flight

NASA Technical Reports Server (NTRS)

Luft, U. C.

1975-01-01

An investigation of the role of 02 fluctuations in oxygen uptake observed with changing posture is reported. A comparison of the closing volume test with other pulmonary function measurements is presented along with a comparison of hydrostatic weighing, and a stereophotogrammetric method for determining body volume.

AC Power at Power Frequencies: Bilateral comparison between SASO NMCC and TÜBİTAK UME

NASA Astrophysics Data System (ADS)

Çaycı, Hüseyin; Yılmaz, Özlem; AlRobaish, Abdullah M.; AlAnazi, Shafi S.; AlAyali, Ahmed R.; AlRumie, Rashed A.

2018-01-01

A supplementary bilateral comparison measurement on AC Power at 50/60 Hz between SASO NMCC (GULFMET) and TÜBİTAK UME (EURAMET) was performed with the primary power standards of each partner. Measurement methods and setups which are very similar of the participants, measurement results, calculation of differences in the results, evaluation of uncertainties are given within this report. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Comparison of different phase retrieval algorithms

NASA Astrophysics Data System (ADS)

Kaufmann, Rolf; Plamondon, Mathieu; Hofmann, Jürgen; Neels, Antonia

2017-09-01

X-ray phase contrast imaging is attracting more and more interest. Since the phase cannot be measured directly an indirect method using e.g. a grating interferometer has to be applied. This contribution compares three different approaches to calculate the phase from Talbot-Lau interferometer measurements using a phase-stepping approach. Besides the usually applied Fourier coefficient method also a linear fitting technique and Taylor series expansion method are applied and compared.

A Backscatter-Lidar Forward-Operator

NASA Astrophysics Data System (ADS)

Geisinger, Armin; Behrendt, Andreas; Wulfmeyer, Volker; Vogel, Bernhard; Mattis, Ina; Flentje, Harald; Förstner, Jochen; Potthast, Roland

2015-04-01

We have developed a forward-operator which is capable of calculating virtual lidar profiles from atmospheric state simulations. The operator allows us to compare lidar measurements and model simulations based on the same measurement parameter: the lidar backscatter profile. This method simplifies qualitative comparisons and also makes quantitative comparisons possible, including statistical error quantification. Implemented into an aerosol-capable model system, the operator will act as a component to assimilate backscatter-lidar measurements. As many weather services maintain already networks of backscatter-lidars, such data are acquired already in an operational manner. To estimate and quantify errors due to missing or uncertain aerosol information, we started sensitivity studies about several scattering parameters such as the aerosol size and both the real and imaginary part of the complex index of refraction. Furthermore, quantitative and statistical comparisons between measurements and virtual measurements are shown in this study, i.e. applying the backscatter-lidar forward-operator on model output.

Comparison of acoustic doppler current profiler and Price AA mechanical current meter measurements made during the 2011 Mississippi River Flood

USGS Publications Warehouse

O'Brien, Patrick; Mueller, David; Pratt, Thad

2012-01-01

The Mississippi River and Tributaries project performed as designed during the historic 2011 Mississippi River flood, with many of the operational decisions based on discharge targets as opposed to stage. Measurement of discharge at the Tarbert Landing, Mississippi range provides critical information used in operational decisions for the floodways located in Louisiana. Historically, discharge measurements have been made using a Price AA current meter and the mid-section method, and a long record exists based on these types of measurements, including historical peak discharges. Discharge measurements made using an acoustic Doppler current profiler from a moving boat have been incorporated into the record since the mid 1990's, and are used along with the Price AA mid-section measurements. During the 2011 flood event, both methods were used and appeared to provide different results at times. The apparent differences between the measurement techniques are due to complex hydrodynamics at this location that created large spatial and temporal fluctuations in the flow. The data and analysis presented herein show the difference between the two methods to be within the expected accuracy of the measurements when the measurements are made concurrently. The observed fluctuations prevent valid comparisons of data collected sequentially or even with different observation durations.

Measurement of health outcomes.

PubMed

Thavorncharoensap, Montarat

2014-05-01

Health outcomes are one of the most important components of health technology assessments (HTAs). All HTA outcomes should be measured from a relevant sample using a properly designed study and method. A number of recommendations on health outcome measurements are made in this second edition of Thailand's HTA guidelines. In particular the use of final outcomes, rather than surrogate outcomes, in HTAs is stressed. Where surrogate outcomes are used, strong justification and evidence must be provided. Effectiveness is preferred over efficacy. The relative treatment effect (the difference between health outcome that would be experienced by patients receiving the technology and that experienced by the same group were they to receive an alternative technology) should be derived from a systematic review of head-to-head RCTs. Mixed treatment comparison (MTC) should be used only to provide supplementary data that cannot be obtained from a head-to-head comparison. Where no direct comparison evidence exists, indirect comparison and observational study data can be used.

EURAMET.M.P-S9: comparison in the negative gauge pressure range -950 to 0 hPa

NASA Astrophysics Data System (ADS)

Saxholm, S.; Otal, P.; AltintaS, A.; Bermanec, L. G.; Durgut, Y.; Hanrahan, R.; Kocas, I.; Lefkopoulos, A.; Pražák, D.; Sandu, I.; Åetina, J.; Spohr, I.; Steindl, D.; Tammik, K.; Testa, N.

2016-01-01

A comparison in the negative gauge pressure range was arranged in the period 2011 - 2012. A total of 14 laboratories participated in this comparison: BEV (Austria), CMI (Czech Republic), DANIAmet-FORCE (Denmark), EIM (Greece), HMI/FSB-LPM (Croatia), INM (Romania), IPQ (Portugal), LNE (France), MCCAA (Malta), METROSERT (Estonia), MIKES (Finland), MIRS/IMT/LMT (Slovenia), NSAI (Ireland) and UME (Turkey). The project was divided into two loops: Loop1, piloted by MIKES, and Loop2, piloted by LNE. The results of the two loops are reported separately: Loop1 results are presented in this paper. The transfer standard was Beamex MC5 no. 25516865 with internal pressure module INT1C, resolution 0.01 hPa. The nominal pressure range of the INT1C is -1000 hPa to +1000 hPa. The nominal pressure points for the comparison were 0 hPa, -200 hPa, -400 hPa, -600 hPa, -800 hPa and -950 hPa. The reference values and their uncertainties as well as the difference uncertainty between the laboratory results and the reference values were determined from the measurement data by Monte Carlo simulations. Stability uncertainty of the transfer standard was included in the final difference uncertainty. Degrees of equivalences and mutual equivalences between the laboratories were calculated. Each laboratory reported results for all twelve measurement points, which means that there were 168 reported values in total. Some 163 of the 168 values (97 %) agree with the reference values within the expanded uncertainties, with a coverage factor k = 2. Among the laboratories, four different methods were used to determine negative gauge pressure. It is concluded that special attention must be paid to the measurements and methods when measuring negative gauge pressures. There might be a need for a technical guide or a workshop that provides information about details and practices related to the measurements of negative gauge pressure, as well as differences between the different methods. The comparison is registered as EURAMET project no. 1170 and as a supplementary comparison EURAMET.M.P-S9 in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

A method for surface topography measurement using a new focus function based on dual-tree complex wavelet transform

NASA Astrophysics Data System (ADS)

Li, Shimiao; Guo, Tong; Yuan, Lin; Chen, Jinping

2018-01-01

Surface topography measurement is an important tool widely used in many fields to determine the characteristics and functionality of a part or material. Among existing methods for this purpose, the focus variation method has proved high performance particularly in large slope scenarios. However, its performance depends largely on the effectiveness of focus function. This paper presents a method for surface topography measurement using a new focus measurement function based on dual-tree complex wavelet transform. Experiments are conducted on simulated defocused images to prove its high performance in comparison with other traditional approaches. The results showed that the new algorithm has better unimodality and sharpness. The method was also verified by measuring a MEMS micro resonator structure.

Comparison of three nondestructive and contactless techniques for investigations of recombination parameters on an example of silicon samples

NASA Astrophysics Data System (ADS)

Chrobak, Ł.; Maliński, M.

2018-06-01

This paper presents a comparison of three nondestructive and contactless techniques used for determination of recombination parameters of silicon samples. They are: photoacoustic method, modulated free carriers absorption method and the photothermal radiometry method. In the paper the experimental set-ups used for measurements of the recombination parameters in these methods as also theoretical models used for interpretation of obtained experimental data have been presented and described. The experimental results and their respective fits obtained with these nondestructive techniques are shown and discussed. The values of the recombination parameters obtained with these methods are also presented and compared. Main advantages and disadvantages of presented methods have been discussed.

Comparison of connectivity analyses for resting state EEG data

NASA Astrophysics Data System (ADS)

Olejarczyk, Elzbieta; Marzetti, Laura; Pizzella, Vittorio; Zappasodi, Filippo

2017-06-01

Objective. In the present work, a nonlinear measure (transfer entropy, TE) was used in a multivariate approach for the analysis of effective connectivity in high density resting state EEG data in eyes open and eyes closed. Advantages of the multivariate approach in comparison to the bivariate one were tested. Moreover, the multivariate TE was compared to an effective linear measure, i.e. directed transfer function (DTF). Finally, the existence of a relationship between the information transfer and the level of brain synchronization as measured by phase synchronization value (PLV) was investigated. Approach. The comparison between the connectivity measures, i.e. bivariate versus multivariate TE, TE versus DTF, TE versus PLV, was performed by means of statistical analysis of indexes based on graph theory. Main results. The multivariate approach is less sensitive to false indirect connections with respect to the bivariate estimates. The multivariate TE differentiated better between eyes closed and eyes open conditions compared to DTF. Moreover, the multivariate TE evidenced non-linear phenomena in information transfer, which are not evidenced by the use of DTF. We also showed that the target of information flow, in particular the frontal region, is an area of greater brain synchronization. Significance. Comparison of different connectivity analysis methods pointed to the advantages of nonlinear methods, and indicated a relationship existing between the flow of information and the level of synchronization of the brain.

MTF measurement of LCDs by a linear CCD imager: I. Monochrome case

NASA Astrophysics Data System (ADS)

Kim, Tae-hee; Choe, O. S.; Lee, Yun Woo; Cho, Hyun-Mo; Lee, In Won

1997-11-01

We construct the modulation transfer function (MTF) measurement system of a LCD using a linear charge-coupled device (CCD) imager. The MTF used in optical system can not describe in the effect of both resolution and contrast on the image quality of display. Thus we present the new measurement method based on the transmission property of a LCD. While controlling contrast and brightness levels, the MTF is measured. From the result, we show that the method is useful for describing of the image quality. A ne measurement method and its condition are described. To demonstrate validity, the method is applied for comparison of the performance of two different LCDs.

Note: Measuring instrument of singlet oxygen quantum yield in photodynamic effects

NASA Astrophysics Data System (ADS)

Li, Zhongwei; Zhang, Pengwei; Zang, Lixin; Qin, Feng; Zhang, Zhiguo; Zhang, Hongli

2017-06-01

Using diphenylisobenzofuran (C20H14O) as a singlet oxygen (1O2) reporter, a comparison method, which can be used to measure the singlet oxygen quantum yield (ΦΔ) of the photosensitizer quantitatively, is presented in this paper. Based on this method, an automatic measuring instrument of singlet oxygen quantum yield is developed. The singlet oxygen quantum yield of the photosensitizer hermimether and aloe-emodin is measured. It is found that the measuring results are identical to the existing ones, which verifies the validity of the measuring instrument.

Comparison of methods for measuring travel time at Florida freeways and arterials : [summary].

DOT National Transportation Integrated Search

2014-07-01

In this project, University of Florida researchers : collected field data along several highways to : evaluate travel time measurements from several : sources: STEWARD, BlueTOAD, INRIX, and HERE. : STEWARD (Statewide Transportation Engineering : Ware...

Black Versus Gray T-Shirts: Comparison of Spectrophotometric and Other Biophysical Properties of Physical Fitness Uniforms and Modeled Heat Strain and Thermal Comfort

DTIC Science & Technology

2016-09-01

test method for measuring the thermal insulation of clothing using a heated manikin. 2010. 2. ASTM International. F2370-10 Standard test method for...PROPERTIES OF PHYSICAL FITNESS UNIFORMS AND MODELED HEAT STRAIN AND THERMAL COMFORT DISCLAIMER The opinions or assertions contained herein are the...SHIRTS: COMPARISON OF SPECTROPHOTOMETRIC AND OTHER BIOPHYSICAL PROPERTIES OF PHYSICAL FITNESS UNIFORMS AND MODELED HEAT STRAIN AND THERMAL COMFORT

Longitudinally Jointed Edge-Wise Compression HoneyComb Composite Sandwich Coupon Testing And Fe Analysis: Three Methods of Strain Measurement, And Comparison

NASA Technical Reports Server (NTRS)

Farrokh, Babak; Rahim, Nur Aida Abul; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex

2013-01-01

Three distinct strain measurement methods (i.e., foil resistance strain gages, fiber optic strain sensors, and a three-dimensional digital image photogrammetry that gives full field strain and displacement measurements) were implemented to measure strains on the back and front surfaces of a longitudinally jointed curved test article subjected to edge-wise compression testing, at NASA Goddard Space Flight Center, according to ASTM C364. The pre-test finite element analysis (FEA) was conducted to assess ultimate failure load and predict strain distribution pattern throughout the test coupon. The predicted strain pattern contours were then utilized as guidelines for installing the strain measurement instrumentations. The foil resistance strain gages and fiber optic strain sensors were bonded on the specimen at locations with nearly the same analytically predicted strain values, and as close as possible to each other, so that, comparisons between the measured strains by strain gages and fiber optic sensors, as well as the three-dimensional digital image photogrammetric system are relevant. The test article was loaded to failure (at 167 kN), at the compressive strain value of 10,000 micro epsilon. As a part of this study, the validity of the measured strains by fiber optic sensors is examined against the foil resistance strain gages and the three-dimensional digital image photogrammetric data, and comprehensive comparisons are made with FEA predictions.

Stress measurement in thin films by geometrical optics

NASA Technical Reports Server (NTRS)

Rossnagel, S. M.; Gilstrap, P.; Rujkorakarn, R.

1982-01-01

A variation of Newton's rings experiment is proposed for measuring film stress. The procedure described, the geometrical optics method, is used to measure radii of curvature for a series of film depositions with Ta, Al, and Mo films. The method has a sensitivity of 1 x 10 to the 9th dyn/sq cm, corresponding to the practical radius limit of about 50 m, and a repeatability usually within five percent. For the purposes of comparison, radii are also measured by Newton's rings method and the Talysurf method; all results are found to be in general agreement. Measurement times are also compared: the geometrical optics method requires only 1/2-1 minute. It is concluded that the geometrical optics method provides an inexpensive, fast, and a reasonably correct technique with which to measure stresses in film.

Biases and power for groups comparison on subjective health measurements.

PubMed

Hamel, Jean-François; Hardouin, Jean-Benoit; Le Neel, Tanguy; Kubis, Gildas; Roquelaure, Yves; Sébille, Véronique

2012-01-01

Subjective health measurements are increasingly used in clinical research, particularly for patient groups comparisons. Two main types of analytical strategies can be used for such data: so-called classical test theory (CTT), relying on observed scores and models coming from Item Response Theory (IRT) relying on a response model relating the items responses to a latent parameter, often called latent trait. Whether IRT or CTT would be the most appropriate method to compare two independent groups of patients on a patient reported outcomes measurement remains unknown and was investigated using simulations. For CTT-based analyses, groups comparison was performed using t-test on the scores. For IRT-based analyses, several methods were compared, according to whether the Rasch model was considered with random effects or with fixed effects, and the group effect was included as a covariate or not. Individual latent traits values were estimated using either a deterministic method or by stochastic approaches. Latent traits were then compared with a t-test. Finally, a two-steps method was performed to compare the latent trait distributions, and a Wald test was performed to test the group effect in the Rasch model including group covariates. The only unbiased IRT-based method was the group covariate Wald's test, performed on the random effects Rasch model. This model displayed the highest observed power, which was similar to the power using the score t-test. These results need to be extended to the case frequently encountered in practice where data are missing and possibly informative.

Mechanical scale and load cell underwater weighing: a comparison of simultaneous measurements and the reliability of methods.

PubMed

Moon, Jordan R; Stout, Jeffrey R; Walter, Ashley A; Smith, Abbie E; Stock, Matt S; Herda, Trent J; Sherk, Vanessa D; Young, Kaelin C; Lockwood, Christopher M; Kendall, Kristina L; Fukuda, David H; Graef, Jennifer L; Cramer, Joel T; Beck, Travis W; Esposito, Enrico N

2011-03-01

Both load cell and mechanical scale-based hydrostatic weighing (HW) systems are used for the measurement of underwater weight. However, there has been no direct comparison of the 2 methods. The purpose of the current investigation was to simultaneously compare a load cell and mechanical scale for use in HW. Twenty-seven men and women (mean ± SD, age: 22 ± 2 years) participated in the 2-day investigation. Each subject completed 2 HW assessments 24 hours apart. Single-day comparisons of all trials for both days revealed no significant difference between the mechanical scale and the load cell (mean difference < 0.016 kg, p > 0.05). True underwater weight values were not significantly different between methods for either days (mean difference < 0.014 kg, p > 0.05) and accounted for a mean difference in percent fat (%FAT) of <0.108%. The 95% limits of agreement indicated a maximum difference between methods of 0.53% FAT. Both methods produced similar reliability SEM values (mechanical SEM < 0.72%FAT, load cell SEM < 0.75%FAT). In conclusion, there was no difference between mechanical scale and load cell measurements of underwater weights and the added precision of the load cell only marginally (<0.16%FAT) improved day-to-day reliability. Either a mechanical scale or load cell can be used for HW with similar accuracy and reliability in young adults with a body mass index of 18.7-34.4 (5-25%FAT).

Sediment-generated noise (SGN): Comparison with physical bedload measurements in a small semi-arid watershed

USDA-ARS?s Scientific Manuscript database

Passive acoustic techniques for the measurement of Sediment-Generated Noise (SGN) in gravel-bed rivers present a promising alternative to traditional bedload measurement techniques. Where traditional methods are often prohibitively costly, particularly in labor requirements, and produce point-scale ...

Comparison of holographic and numerical vibration modes on ductile cast iron containers at drop tests

NASA Astrophysics Data System (ADS)

Ettemeyer, Andreas; Schreiber, Dietmar; Voelzer, W.

1996-08-01

Ductile cast iron containers for transportation and deposition of radioactive waste have to be designed carefully in order to avoid unacceptable damages and leakages in case of an accident. Therefore various calculation and experimental methods are used during development and licensing of the containers. Besides others the container has to suffer severe impacts (e.g. falling from a height of several meters onto a concrete base). The level of strains must not exceed a value which would adversely affect the package in such a way that it would fail to meet the applicable requirements. In practice complex events such as drop tests are very difficult to calculate. Both the position of Maximum stress and the time of its occurrence are not easy to be predicted with the method of FEM. The uncertainty of the material modelling for plastic deformations by dynamic loading rates is the limiting factor. Therefore holography as an integral measuring technique in combination with strain gauge techniques were used to fit the FEM. By using the FEM calculations in the case of licensing, the FE and the material model have to be verified. The verification of the FE model has to be done by comparison of the local maxima measured by strain gauges and by comparison of the vibration modes. These vibration modes we take from holographic measurements. In this paper we explain container vibrations after impact analyzed with holographic measurements, FEM calculations and the comparison of the results. The comparison of the local maxima (strain gauges/FEM) is reported earlier.

Measuring Education for Sustainable Development: Experiences from the University of Bristol

ERIC Educational Resources Information Center

Tierney, Aisling; Tweddell, Hannah; Willmore, Chris

2015-01-01

Purpose: The purpose of this paper is to explore how education for sustainable development (ESD) was measured in the taught curriculum at the University of Bristol (UoB), providing comparison to other methods of measurement and how measurements were used to engage academics in considering the visibility of the penetration of sustainable…

Active microwave water equivalence

NASA Technical Reports Server (NTRS)

Boyne, H. S.; Ellerbruch, D. A.

1980-01-01

Measurements of water equivalence using an active FM-CW microwave system were conducted over the past three years at various sites in Colorado, Wyoming, and California. The measurement method is described. Measurements of water equivalence and stratigraphy are compared with ground truth. A comparison of microwave, federal sampler, and snow pillow measurements at three sites in Colorado is described.

Comparisons of Audio and Audiovisual Measures of Stuttering Frequency and Severity in Preschool-Age Children

ERIC Educational Resources Information Center

Rousseau, Isabelle; Onslow, Mark; Packman, Ann; Jones, Mark

2008-01-01

Purpose: To determine whether measures of stuttering frequency and measures of overall stuttering severity in preschoolers differ when made from audio-only recordings compared with audiovisual recordings. Method: Four blinded speech-language pathologists who had extensive experience with preschoolers who stutter measured stuttering frequency and…

Shortwave Radiometer Calibration Methods Comparison and Resulting Solar Irradiance Measurement Differences: A User Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habte, Aron; Sengupta, Manajit; Andreas, Afshin

Banks financing solar energy projects require assurance that these systems will produce the energy predicted. Furthermore, utility planners and grid system operators need to understand the impact of the variable solar resource on solar energy conversion system performance. Accurate solar radiation data sets reduce the expense associated with mitigating performance risk and assist in understanding the impacts of solar resource variability. The accuracy of solar radiation measured by radiometers depends on the instrument performance specification, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methods provided by radiometric calibrationmore » service providers, such as NREL and manufacturers of radiometers, on the resulting calibration responsivity. Some of these radiometers are calibrated indoors and some outdoors. To establish or understand the differences in calibration methodology, we processed and analyzed field-measured data from these radiometers. This study investigates calibration responsivities provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The BORCAL method provides the outdoor calibration responsivity of pyranometers and pyrheliometers at 45 degree solar zenith angle, and as a function of solar zenith angle determined by clear-sky comparisons with reference irradiance. The BORCAL method also employs a thermal offset correction to the calibration responsivity of single-black thermopile detectors used in pyranometers. Indoor calibrations of radiometers by their manufacturers are performed using a stable artificial light source in a side-by-side comparison between the test radiometer under calibration and a reference radiometer of the same type. In both methods, the reference radiometer calibrations are traceable to the World Radiometric Reference (WRR). These different methods of calibration demonstrated +1% to +2% differences in solar irradiance measurement. Analyzing these differences will ultimately help determine the uncertainty of the field radiometer data and guide the development of a consensus standard for calibration. Further advancing procedures for precisely calibrating radiometers to world reference standards that reduce measurement uncertainty will allow more accurate prediction of solar output and improve the bankability of solar projects.« less

The optical measurement of 1,2-propanediol for the determination of lung capillary permeability surface area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galloway, R.L. Jr.; Staton, D.J.; Harris, T.R.

1989-06-01

A technique has been developed which allows for the optical measurement of the concentration-time relationship for a diffusion-limited material in indicator dilution studies. The material, 1-2 propanediol, is used as a probe of the permeability of capillaries in the lung. Comparisons between standard radioisotope measurements and the optical measurements are provided and show excellent agreement. The optical method represents an improvement over the standard radioisotope method in that it provides the same data at lower cost, lower risk, and without the delay required by the radiographic methods.

Microrheology with optical tweezers: measuring the relative viscosity of solutions 'at a glance'.

PubMed

Tassieri, Manlio; Del Giudice, Francesco; Robertson, Emma J; Jain, Neena; Fries, Bettina; Wilson, Rab; Glidle, Andrew; Greco, Francesco; Netti, Paolo Antonio; Maffettone, Pier Luca; Bicanic, Tihana; Cooper, Jonathan M

2015-03-06

We present a straightforward method for measuring the relative viscosity of fluids via a simple graphical analysis of the normalised position autocorrelation function of an optically trapped bead, without the need of embarking on laborious calculations. The advantages of the proposed microrheology method are evident when it is adopted for measurements of materials whose availability is limited, such as those involved in biological studies. The method has been validated by direct comparison with conventional bulk rheology methods, and has been applied both to characterise synthetic linear polyelectrolytes solutions and to study biomedical samples.

Microrheology with Optical Tweezers: Measuring the relative viscosity of solutions ‘at a glance'

PubMed Central

Tassieri, Manlio; Giudice, Francesco Del; Robertson, Emma J.; Jain, Neena; Fries, Bettina; Wilson, Rab; Glidle, Andrew; Greco, Francesco; Netti, Paolo Antonio; Maffettone, Pier Luca; Bicanic, Tihana; Cooper, Jonathan M.

2015-01-01

We present a straightforward method for measuring the relative viscosity of fluids via a simple graphical analysis of the normalised position autocorrelation function of an optically trapped bead, without the need of embarking on laborious calculations. The advantages of the proposed microrheology method are evident when it is adopted for measurements of materials whose availability is limited, such as those involved in biological studies. The method has been validated by direct comparison with conventional bulk rheology methods, and has been applied both to characterise synthetic linear polyelectrolytes solutions and to study biomedical samples. PMID:25743468

Comparison of two reference methods for detemining cotton fiber moisture

USDA-ARS?s Scientific Manuscript database

Moisture is an important quality and processing property for the cotton industry. The standard reference method for determining the moisture content in cotton fiber is the ASTM oven method (gravimetric weight loss). Several concerns have expressed on its ability to measure the actual moisture cont...

Intra-abdominal fat: Comparison of computed tomography fat segmentation and bioimpedance spectroscopy.

PubMed

Finch, Peter

2017-06-01

Intra-abdominal fat is an important factor in determining the metabolic syndrome/insulin resistance, and thus the risk of diabetes and ischaemic heart disease. Computed Tomography (CT) fat segmentation represents a defined method of quantifying intra-abdominal fat, with attendant radiation risks. Bioimpedance spectroscopy may offer a method of assessment without any risks to the patients. A comparison is made of these two methods. This was a preliminary study of the utility of multifrequency bioimpedance spectroscopy of the mid abdomen as a measure of intra-abdominal fat, by comparison with fat segmentation of an abdominal CT scan in the -30 to -190 HU range. There was a significant (P < 0.01) correlation between intra-abdominal fat and mid-upper arm circumference, as well as the bioimpedance parameter, the R/S ratio. Multivariate analysis showed that these were the only independant variables and allowed the derivation of a formula to estimate intra-abdominal fat: IAF = 0.02 × MAC - 0.757 × R/S + 0.036. Circumabdominal bioimpedance spectroscopy may prove a useful method of assessing intra-abdominal fat, and may be suitable for use in studies to enhance other measures of body composition, such as mid-upper arm circumference.

Automatic high-sensitivity control of suspended pollutants in drinking and natural water

NASA Astrophysics Data System (ADS)

Akopov, Edmund I.; Karabegov, M.; Ovanesyan, A.

1993-11-01

This article presents a description of the new instrumental method and device for automatic measurement of water turbidity (WT) by means of photoelectron flow ultramicroscope (PFU). The method presents the WT determination by measuring the number concentration (number of particles suspended in 1 cm3 of water under study) using the PFU and demonstrates much higher sensitivity and accuracy in comparison with the usual methods--turbidimetry and nephelometry.

Comparison of shear-wave slowness profiles at 10 strong-motion sites from noninvasive SASW measurements and measurements made in boreholes

USGS Publications Warehouse

Brown, L.T.; Boore, D.M.; Stokoe, K.H.

2002-01-01

The spectral-analysis-of-surface-waves (SASW) method is a relatively new in situ method for determining shear-wave slownesses. All measurements are made on the ground surface, making it much less costly than methods that require boreholes. The SASW method uses a number of active sources (ranging from a commercial Vibroseis truck to a small handheld hammer for the study conducted here) and different receiver spacings to map a curve of apparent phase velocity versus frequency. With the simplifying assumption that the phase velocities correspond to fundamental mode surface waves, forward modeling yields an estimate of the sub-surface shear-wave slownesses. To establish the reliability of this indirect technique, we conducted a blind evaluation of the SASW method. SASW testing was performed at 10 strong-motion stations at which borehole seismic measurements were previously or subsequently made; if previously made, the borehole results were not used for the interpretation of the SASW data, and vice-versa. Comparisons of the shear-wave slownesses from the SASW and borehole measurements are generally very good. The differences in predicted ground-motion amplifications are less than about 15% for most frequencies. In addition, both methods gave the same NEHRP site classification for seven of the sites. For the other three sites the average velocities from the downhole measurements were only 5-13 m/sec larger than the velocity defining the class C/D boundary. This study demonstrates that in many situations the SASW method can provide subsurface information suitable for site response predictions.

The Pot Calling the Kettle Black? A Comparison of Measures of Current Tobacco Use

PubMed Central

ROSENMAN, ROBERT

2014-01-01

Researchers often use the discrepancy between self-reported and biochemically assessed active smoking status to argue that self-reported smoking status is not reliable, ignoring the limitations of biochemically assessed measures and treating it as the gold standard in their comparisons. Here, we employ econometric techniques to compare the accuracy of self-reported and biochemically assessed current tobacco use, taking into account measurement errors with both methods. Our approach allows estimating and comparing the sensitivity and specificity of each measure without directly observing true smoking status. The results, robust to several alternative specifications, suggest that there is no clear reason to think that one measure dominates the other in accuracy. PMID:25587199

A Comparison of Two Tree Construction Methods for Obtaining Proximity Measures among Words. Number 47.

ERIC Educational Resources Information Center

Rapoport, Amnon

The prediction that two different methods of constructing linear, tree graphs will yield the same formal structure of semantic space and measurement of word proximity was tested by comparing the distribution of node degree, the distribution of the number of pairs of nodes connected y times, and the distribution of adjective degree in trees…

Integrated method for chaotic time series analysis

DOEpatents

Hively, L.M.; Ng, E.G.

1998-09-29

Methods and apparatus for automatically detecting differences between similar but different states in a nonlinear process monitor nonlinear data are disclosed. Steps include: acquiring the data; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis; obtaining time serial trends in the nonlinear measures; and determining by comparison whether differences between similar but different states are indicated. 8 figs.

Comparison of micrometeorological methods using open-path optical instruments for measuring methane emission from agricultural sites

USDA-ARS?s Scientific Manuscript database

In this study, we evaluated the accuracies of two relatively new micrometeorological methods using open-path tunable diode laser absorption spectrometers: vertical radial plume mapping method (US EPA OTM-10) and the backward Lagragian stochastic method (Wintrax®). We have evaluated the accuracy of t...

Comparison of methods for measuring travel time at Florida freeways and arterials.

DOT National Transportation Integrated Search

2014-07-01

Travel time is an important performance measure used to assess the traffic operational quality of various types of highway : facilities. Previous research funded by the Florida Department of Transportation (FDOT) on travel time reliability developed,...

Issues concerning international comparison of free-field calibrations of acoustical standards

NASA Astrophysics Data System (ADS)

Nedzelnitsky, Victor

2002-11-01

Primary free-field calibrations of laboratory standard microphones by the reciprocity method establish these microphones as reference standard devices for calibrating working standard microphones, other measuring microphones, and practical instruments such as sound level meters and personal sound exposure meters (noise dosimeters). These primary, secondary, and other calibrations are indispensable to the support of regulatory requirements, standards, and product characterization and quality control procedures important for industry, commerce, health, and safety. International Electrotechnical Commission (IEC) Technical Committee 29 Electroacoustics produces international documentary standards, including standards for primary and secondary free-field calibration and measurement procedures and their critically important application to practical instruments. This paper addresses some issues concerning calibrations, standards activities, and the international key comparison of primary free-field calibrations of IEC-type LS2 laboratory standard microphones that is being planned by the Consultative Committee for Acoustics, Ultrasound, and Vibration (CCAUV) of the International Committee for Weights and Measures (CIPM). This comparison will include free-field calibrations by the reciprocity method at participating major national metrology laboratories throughout the world.

The Visual Analogue Scale for Rating, Ranking and Paired-Comparison (VAS-RRP): A new technique for psychological measurement.

PubMed

Sung, Yao-Ting; Wu, Jeng-Shin

2018-04-17

Traditionally, the visual analogue scale (VAS) has been proposed to overcome the limitations of ordinal measures from Likert-type scales. However, the function of VASs to overcome the limitations of response styles to Likert-type scales has not yet been addressed. Previous research using ranking and paired comparisons to compensate for the response styles of Likert-type scales has suffered from limitations, such as that the total score of ipsative measures is a constant that cannot be analyzed by means of many common statistical techniques. In this study we propose a new scale, called the Visual Analogue Scale for Rating, Ranking, and Paired-Comparison (VAS-RRP), which can be used to collect rating, ranking, and paired-comparison data simultaneously, while avoiding the limitations of each of these data collection methods. The characteristics, use, and analytic method of VAS-RRPs, as well as how they overcome the disadvantages of Likert-type scales, ranking, and VASs, are discussed. On the basis of analyses of simulated and empirical data, this study showed that VAS-RRPs improved reliability, response style bias, and parameter recovery. Finally, we have also designed a VAS-RRP Generator for researchers' construction and administration of their own VAS-RRPs.

Building a Better Model: A Comprehensive Breast Cancer Risk Model Incorporating Breast Density to Stratify Risk and Apply Resources

DTIC Science & Technology

2014-10-01

variability with well trained readers. Figure 7: comparison between the PD (percent density using Cumulus area) and the automatic PD. The...evaluation of outlier correction, comparison of several different software methods, precision measurement, and evaluation of variation by mammography...chart review for selected cases (month 4-6). Comparison of information from the Breast Cancer Database and medical records showed good consistency

Comparison of SAND-II and FERRET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wootan, D.W.; Schmittroth, F.

1981-01-01

A comparison was made of the advantages and disadvantages of two codes, SAND-II and FERRET, for determining the neutron flux spectrum and uncertainty from experimental dosimeter measurements as anticipated in the FFTF Reactor Characterization Program. This comparison involved an examination of the methodology and the operational performance of each code. The merits of each code were identified with respect to theoretical basis, directness of method, solution uniqueness, subjective influences, and sensitivity to various input parameters.

Key comparison SIM.EM.RF-K5b.CL: scattering coefficients by broad-band methods, 2 GHz-18 GHz — type N connector

NASA Astrophysics Data System (ADS)

Silva, H.; Monasterios, G.

2016-01-01

The first key comparison in microwave frequencies within the SIM (Sistema Interamericano de Metrología) region has been carried out. The measurands were the S-parameters of 50 ohm coaxial devices with Type-N connectors and were measured at 2 GHz, 9 GHz and 18 GHz. SIM.EM.RF-K5b.CL was the identification assigned and it was based on a parent CCEM key comparison named CCEM.RF-K5b.CL. For this reason, the measurements standards and their nominal values were selected accordingly, i.e. two one-port devices (a matched and a mismatched load) to cover low and high reflection coefficients and two attenuators (3dB and 20 dB) to cover low and high transmission coefficients. This key comparison has met the need for ensuring traceability in high-frequency measurements across America by linking SIM's results to CCEM. Six NMIs have participated in this comparison which was piloted by the Instituto Nacional de Tecnología Industrial (Argentina). A linking method of multivariate values was proposed and implemented in order to allow the linking of 2-dimensional results. KEY WORDS FOR SEARCH Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

A comparison of two methods for quantifying parasitic nematode fecundity

USDA-ARS?s Scientific Manuscript database

Accurate measures of nematode fecundity can provide important information for investigating parasite life history evolution, transmission potential, and effects on host health. Understanding differences among fecundity assessment protocols and standardizing methods, where possible, will enable compa...

Comparison of viable plate count, turbidity measurement and real-time PCR for quantification of Porphyromonas gingivalis.

PubMed

Clais, S; Boulet, G; Van Kerckhoven, M; Lanckacker, E; Delputte, P; Maes, L; Cos, P

2015-01-01

The viable plate count (VPC) is considered as the reference method for bacterial enumeration in periodontal microbiology but shows some important limitations for anaerobic bacteria. As anaerobes such as Porphyromonas gingivalis are difficult to culture, VPC becomes time-consuming and less sensitive. Hence, efficient normalization of experimental data to bacterial cell count requires alternative rapid and reliable quantification methods. This study compared the performance of VPC with that of turbidity measurement and real-time PCR (qPCR) in an experimental context using highly concentrated bacterial suspensions. Our TaqMan-based qPCR assay for P. gingivalis 16S rRNA proved to be sensitive and specific. Turbidity measurements offer a fast method to assess P. gingivalis growth, but suffer from high variability and a limited dynamic range. VPC was very time-consuming and less repeatable than qPCR. Our study concludes that qPCR provides the most rapid and precise approach for P. gingivalis quantification. Although our data were gathered in a specific research context, we believe that our conclusions on the inferior performance of VPC and turbidity measurements in comparison to qPCR can be extended to other research and clinical settings and even to other difficult-to-culture micro-organisms. Various clinical and research settings require fast and reliable quantification of bacterial suspensions. The viable plate count method (VPC) is generally seen as 'the gold standard' for bacterial enumeration. However, VPC-based quantification of anaerobes such as Porphyromonas gingivalis is time-consuming due to their stringent growth requirements and shows poor repeatability. Comparison of VPC, turbidity measurement and TaqMan-based qPCR demonstrated that qPCR possesses important advantages regarding speed, accuracy and repeatability. © 2014 The Society for Applied Microbiology.

KEY COMPARISON: Final report on CCQM-K69 key comparison: Testosterone glucuronide in human urine

NASA Astrophysics Data System (ADS)

Liu, Fong-Ha; Mackay, Lindsey; Murby, John

2010-01-01

The CCQM-K69 key comparison of testosterone glucuronide in human urine was organized under the auspices of the CCQM Organic Analysis Working Group (OAWG). The National Measurement Institute Australia (NMIA) acted as the coordinating laboratory for the comparison. The samples distributed for the key comparison were prepared at NMIA with funding from the World Anti-Doping Agency (WADA). WADA granted the approval for this material to be used for the intercomparison provided the distribution and handling of the material were strictly controlled. Three national metrology institutes (NMIs)/designated institutes (DIs) developed reference methods and submitted data for the key comparison along with two other laboratories who participated in the parallel pilot study. A good selection of analytical methods and sample workup procedures was displayed in the results submitted considering the complexities of the matrix involved. The comparability of measurement results was successfully demonstrated by the participating NMIs. Only the key comparison data were used to estimate the key comparison reference value (KCRV), using the arithmetic mean approach. The reported expanded uncertainties for results ranged from 3.7% to 6.7% at the 95% level of confidence and all results agreed within the expanded uncertainty of the KCRV. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Method of determining pH by the alkaline absorption of carbon dioxide

DOEpatents

Hobbs, D.T.

1992-10-06

A method is described for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction. 2 figs.

Densitometry By Acoustic Levitation

NASA Technical Reports Server (NTRS)

Trinh, Eugene H.

1989-01-01

"Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

A new method for the determination of vaporization enthalpies of ionic liquids at low temperatures.

PubMed

Verevkin, Sergey P; Zaitsau, Dzmitry H; Emelyanenko, Vladimir N; Heintz, Andreas

2011-11-10

A new method for the determination of vaporization enthalpies of extremely low volatile ILs has been developed using a newly constructed quartz crystal microbalance (QCM) vacuum setup. Because of the very high sensitivity of the QCM it has been possible to reduce the average temperature of the vaporization studies by approximately 100 K in comparison to other conventional techniques. The physical basis of the evaluation procedure has been developed and test measurements have been performed with the common ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C(2)mim][NTf(2)] extending the range of measuring vaporization enthalpies down to 363 K. The results obtained for [C(2)mim][NTf(2)] have been tested for thermodynamic consistency by comparison with data already available at higher temperatures. Comparison of the temperature-dependent vaporization enthalpy data taken from the literature show only acceptable agreement with the heat capacity difference of -40 J K(-1) mol(-1). The method developed in this work opens also a new way to obtain reliable values of vaporization enthalpies of thermally unstable ionic liquids.

Application of probabilistic fiber-tracking method of MR imaging to measure impact of cranial irradiation on structural brain connectivity in children treated for medulloblastoma

NASA Astrophysics Data System (ADS)

Duncan, Elizabeth C.; Reddick, Wilburn E.; Glass, John O.; Hyun, Jung Won; Ji, Qing; Li, Yimei; Gajjar, Amar

2016-03-01

We applied a modified probabilistic fiber-tracking method for the extraction of fiber pathways to quantify decreased white matter integrity as a surrogate of structural loss in connectivity due to cranial radiation therapy (CRT) as treatment for pediatric medulloblastoma. Thirty subjects were examined (n=8 average-risk, n=22 high-risk) and the groups did not differ significantly in age at examination. The pathway analysis created a structural connectome focused on sub-networks within the central executive network (CEN) for comparison between baseline and post-CRT scans and for comparison between standard and high dose CRT. A paired-wise comparison of the connectivity between baseline and post-CRT scans showed the irradiation did have a significant detrimental impact on white matter integrity (decreased fractional anisotropy (FA) and decreased axial diffusivity (AX)) in most of the CEN sub-networks. Group comparisons of the change in the connectivity revealed that patients receiving high dose CRT experienced significant AX decreases in all sub-networks while the patients receiving standard dose CRT had relatively stable AX measures across time. This study on pediatric patients with medulloblastoma demonstrated the utility of this method to identify specific sub-networks within the developing brain affected by CRT.

A comparison of visual and quantitative methods to identify interstitial lung abnormalities.

PubMed

Kliment, Corrine R; Araki, Tetsuro; Doyle, Tracy J; Gao, Wei; Dupuis, Josée; Latourelle, Jeanne C; Zazueta, Oscar E; Fernandez, Isis E; Nishino, Mizuki; Okajima, Yuka; Ross, James C; Estépar, Raúl San José; Diaz, Alejandro A; Lederer, David J; Schwartz, David A; Silverman, Edwin K; Rosas, Ivan O; Washko, George R; O'Connor, George T; Hatabu, Hiroto; Hunninghake, Gary M

2015-10-29

Evidence suggests that individuals with interstitial lung abnormalities (ILA) on a chest computed tomogram (CT) may have an increased risk to develop a clinically significant interstitial lung disease (ILD). Although methods used to identify individuals with ILA on chest CT have included both automated quantitative and qualitative visual inspection methods, there has been not direct comparison between these two methods. To investigate this relationship, we created lung density metrics and compared these to visual assessments of ILA. To provide a comparison between ILA detection methods based on visual assessment we generated measures of high attenuation areas (HAAs, defined by attenuation values between -600 and -250 Hounsfield Units) in >4500 participants from both the COPDGene and Framingham Heart studies (FHS). Linear and logistic regressions were used for analyses. Increased measures of HAAs (in ≥ 10 % of the lung) were significantly associated with ILA defined by visual inspection in both cohorts (P < 0.0001); however, the positive predictive values were not very high (19 % in COPDGene and 13 % in the FHS). In COPDGene, the association between HAAs and ILA defined by visual assessment were modified by the percentage of emphysema and body mass index. Although increased HAAs were associated with reductions in total lung capacity in both cohorts, there was no evidence for an association between measurement of HAAs and MUC5B promoter genotype in the FHS. Our findings demonstrate that increased measures of lung density may be helpful in determining the severity of lung volume reduction, but alone, are not strongly predictive of ILA defined by visual assessment. Moreover, HAAs were not associated with MUC5B promoter genotype.

(abstract) A Comparison Between Measurements of the F-layer Critical Frequency and Values Derived from the PRISM Adjustment Algorithm Applied to Total Electron Content Data in the Equatorial Region

NASA Technical Reports Server (NTRS)

Mannucci, A. J.; Anderson, D. N.; Abdu, A. M.

1994-01-01

The Parametrized Real-Time Ionosphere Specification Model (PRISM) is a global ionospheric specification model that can incorporate real-time data to compute accurate electron density profiles. Time series of computed and measured data are compared in this paper. This comparison can be used to suggest methods of optimizing the PRISM adjustment algorithm for TEC data obtained at low altitudes.

Comparison of forward flight effects theory of A. Michalke and U. Michel with measured data

NASA Technical Reports Server (NTRS)

Rawls, J. W., Jr.

1983-01-01

The scaling laws of a Michalke and Michel predict flyover noise of a single stream shock free circular jet from static data or static predictions. The theory is based on a farfield solution to Lighthill's equation and includes density terms which are important for heated jets. This theory is compared with measured data using two static jet noise prediction methods. The comparisons indicate the theory yields good results when the static noise levels are accurately predicted.

A Comparison of Three Methods to Measure Percent Body Fat on Mentally Retarded Adults.

ERIC Educational Resources Information Center

Burkett, Lee N.; And Others

1994-01-01

Reports a study that compared three measures for determining percent body fat in mentally retarded adults (multiple skinfolds and circumference measurements, Infrared Interactance, and Bioelectrical Impedance). Results indicated the Bioelectrical Impedance Analyzer and Infrared Interactance Analyzer produced values for percent body fat that were…

Using Caspar Creek flow records to test peak flow estimation methods applicable to crossing design

Treesearch

Peter H. Cafferata; Leslie M. Reid

2017-01-01

Long-term flow records from sub-watersheds in the Caspar Creek Experimental Watersheds were used to test the accuracy of four methods commonly used to estimate peak flows in small forested watersheds: the Rational Method, the updated USGS Magnitude and Frequency Method, flow transference methods, and the NRCS curve number method. Comparison of measured and calculated...

SUPPLEMENTARY COMPARISON: Final report on APMP.PR-S1.1: Bilateral comparison of irradiance responsivity of UVA detectors

NASA Astrophysics Data System (ADS)

Huang, Xuebo

2009-01-01

In order to assess the performance of the standards and techniques used for calibration and measurement of UVA irradiance responsivity of photodetectors in NMISA, South Africa, a new comparison was decided as a follow-up to comparison APMP.PR-S1. It is registered in the Key Comparison Data Base (KCDB) of BIPM as a bilateral supplementary comparison, with the identifier APMP.PR-S1.1. The comparison was carried out following the same technical protocol as that of supplementary comparison APMP PR-S1. The principle, organization and method of the comparison, as well as the preliminary measurements at the pilot laboratory NMC-A*STAR Singapore, were described in the Final Report of the APMP.PR-S1 comparison. The results of this bilateral comparison show that the NMISA's results lie within ±2% against the comparison reference values of APMP.PR-S1, which is a great improvement. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Objective comparison of particle tracking methods

PubMed Central

Chenouard, Nicolas; Smal, Ihor; de Chaumont, Fabrice; Maška, Martin; Sbalzarini, Ivo F.; Gong, Yuanhao; Cardinale, Janick; Carthel, Craig; Coraluppi, Stefano; Winter, Mark; Cohen, Andrew R.; Godinez, William J.; Rohr, Karl; Kalaidzidis, Yannis; Liang, Liang; Duncan, James; Shen, Hongying; Xu, Yingke; Magnusson, Klas E. G.; Jaldén, Joakim; Blau, Helen M.; Paul-Gilloteaux, Perrine; Roudot, Philippe; Kervrann, Charles; Waharte, François; Tinevez, Jean-Yves; Shorte, Spencer L.; Willemse, Joost; Celler, Katherine; van Wezel, Gilles P.; Dan, Han-Wei; Tsai, Yuh-Show; de Solórzano, Carlos Ortiz; Olivo-Marin, Jean-Christophe; Meijering, Erik

2014-01-01

Particle tracking is of key importance for quantitative analysis of intracellular dynamic processes from time-lapse microscopy image data. Since manually detecting and following large numbers of individual particles is not feasible, automated computational methods have been developed for these tasks by many groups. Aiming to perform an objective comparison of methods, we gathered the community and organized, for the first time, an open competition, in which participating teams applied their own methods independently to a commonly defined data set including diverse scenarios. Performance was assessed using commonly defined measures. Although no single method performed best across all scenarios, the results revealed clear differences between the various approaches, leading to important practical conclusions for users and developers. PMID:24441936

Landsat-4 (TDRSS-user) orbit determination using batch least-squares and sequential methods

NASA Technical Reports Server (NTRS)

Oza, D. H.; Jones, T. L.; Hakimi, M.; Samii, M. V.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

1992-01-01

TDRSS user orbit determination is analyzed using a batch least-squares method and a sequential estimation method. It was found that in the batch least-squares method analysis, the orbit determination consistency for Landsat-4, which was heavily tracked by TDRSS during January 1991, was about 4 meters in the rms overlap comparisons and about 6 meters in the maximum position differences in overlap comparisons. The consistency was about 10 to 30 meters in the 3 sigma state error covariance function in the sequential method analysis. As a measure of consistency, the first residual of each pass was within the 3 sigma bound in the residual space.

The Impact of Indoor and Outdoor Radiometer Calibration on Solar Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habte, Aron; Sengupta, Manajit; Andreas, Afshin

2016-06-02

This study addresses the effect of calibration methodologies on calibration responsivities and the resulting impact on radiometric measurements. The calibration responsivities used in this study are provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The BORCAL method provides outdoor calibration responsivity of pyranometers and pyrheliometers at a 45 degree solar zenith angle and responsivity as a function of solar zenith angle determined by clear-sky comparisons to reference irradiance. The BORCAL method also employs a thermal offset correction to the calibration responsivity of single-black thermopile detectors used in pyranometers. Indoor calibrations of radiometers by their manufacturersmore » are performed using a stable artificial light source in a side-by-side comparison of the test radiometer under calibration to a reference radiometer of the same type. These different methods of calibration demonstrated 1percent to 2 percent differences in solar irradiance measurement. Analyzing these values will ultimately enable a reduction in radiometric measurement uncertainties and assist in developing consensus on a standard for calibration.« less

A comparison of wet and dry season ozone and CO over Brazil using in situ and satellite measurements

NASA Technical Reports Server (NTRS)

Watson, Catherine E.; Fishman, Jack; Gregory, Gerald L.; Sachse, Glen W.

1991-01-01

A comparison conducted between direct measurements of Brazilian ozone and NO concentrations and space-based measurements has indicated a strong correlation between the two environmental sensing methods and indicated the seasonality of both ozone and CO concentrations in this region. Dry season increases appear to be due to both increased local biomass burning and the transport of CO and ozone from Africa. The coincident high values of both CO and ozone suggest photochemical sources, rather than a stratospheric source, for the African and South American ozone.

Use of units of measurement error in anthropometric comparisons.

PubMed

Lucas, Teghan; Henneberg, Maciej

2017-09-01

Anthropometrists attempt to minimise measurement errors, however, errors cannot be eliminated entirely. Currently, measurement errors are simply reported. Measurement errors should be included into analyses of anthropometric data. This study proposes a method which incorporates measurement errors into reported values, replacing metric units with 'units of technical error of measurement (TEM)' by applying these to forensics, industrial anthropometry and biological variation. The USA armed forces anthropometric survey (ANSUR) contains 132 anthropometric dimensions of 3982 individuals. Concepts of duplication and Euclidean distance calculations were applied to the forensic-style identification of individuals in this survey. The National Size and Shape Survey of Australia contains 65 anthropometric measurements of 1265 women. This sample was used to show how a woman's body measurements expressed in TEM could be 'matched' to standard clothing sizes. Euclidean distances show that two sets of repeated anthropometric measurements of the same person cannot be matched (> 0) on measurements expressed in millimetres but can in units of TEM (= 0). Only 81 women can fit into any standard clothing size when matched using centimetres, with units of TEM, 1944 women fit. The proposed method can be applied to all fields that use anthropometry. Units of TEM are considered a more reliable unit of measurement for comparisons.

Dynamic pressure sensitivity determination with Mach number method

NASA Astrophysics Data System (ADS)

Sarraf, Christophe; Damion, Jean-Pierre

2018-05-01

Measurements of pressure in fast transient conditions are often performed even if the dynamic characteristic of the transducer are not traceable to international standards. Moreover, the question of a primary standard in dynamic pressure is still open, especially for gaseous applications. The question is to improve dynamic standards in order to respond to expressed industrial needs. In this paper, the method proposed in the EMRP IND09 ‘Dynamic’ project, which can be called the ‘ideal shock tube method’, is compared with the ‘collective standard method’ currently used in the Laboratoire de Métrologie Dynamique (LNE/ENSAM). The input is a step of pressure generated by a shock tube. The transducer is a piezoelectric pressure sensor. With the ‘ideal shock tube method’ the sensitivity of a pressure sensor is first determined dynamically. This method requires a shock tube implemented with piezoelectric shock wave detectors. The measurement of the Mach number in the tube allows an evaluation of the incident pressure amplitude of a step using a theoretical 1D model of the shock tube. Heat transfer, other actual effects and effects of the shock tube imperfections are not taken into account. The amplitude of the pressure step is then used to determine the sensitivity in dynamic conditions. The second method uses a frequency bandwidth comparison to determine pressure at frequencies from quasi-static conditions, traceable to static pressure standards, to higher frequencies (up to 10 kHz). The measurand is also a step of pressure generated by a supposed ideal shock tube or a fast-opening device. The results are provided as a transfer function with an uncertainty budget assigned to a frequency range, also deliverable frequency by frequency. The largest uncertainty in the bandwidth of comparison is used to trace the final pressure step level measured in dynamic conditions, owing that this pressure is not measurable in a steady state on a shock tube. A reference sensor thereby calibrated can be used in a comparison measurement process. At high frequencies the most important component of the uncertainty in this method is due to actual shock tube complex effects not already functionalized nowadays or thought not to be functionalized in this kind of direct method. After a brief review of both methods and a brief review of the determination of the transfer function of pressure transducers, and the budget of associated uncertainty for the dynamic calibration of a pressure transducer in gas, this paper presents a comparison of the results obtained with the ‘ideal shock tube’ and the ‘collective standard’ methods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hohimer, J.P.

The use of laser-based analytical methods in nuclear-fuel processing plants is considered. The species and locations for accountability, process control, and effluent control measurements in the Coprocessing, Thorex, and reference Purex fuel processing operations are identified and the conventional analytical methods used for these measurements are summarized. The laser analytical methods based upon Raman, absorption, fluorescence, and nonlinear spectroscopy are reviewed and evaluated for their use in fuel processing plants. After a comparison of the capabilities of the laser-based and conventional analytical methods, the promising areas of application of the laser-based methods in fuel processing plants are identified.

Measuring fecal testosterone in females and fecal estrogens in males: comparison of RIA and LC/MS/MS methods for wild baboons (Papio cynocephalus)

PubMed Central

Gesquiere, Laurence R.; Ziegler, Toni E.; Chen, Patricia A.; Epstein, Katherine A.; Alberts, Susan C.; Altmann, Jeanne

2014-01-01

The development of non-invasive methods, particularly fecal determination, has made possible the assessment of hormone concentrations in wild animal populations. However, measuring fecal metabolites needs careful validation for each species and for each sex. We investigated whether radioimmunoassays (RIAs) previously used to measure fecal testosterone (fT) in male baboons and fecal estrogens (fE) in female baboons were well suited to measure these hormones in the opposite sex. We compared fE and fT concentrations determined by RIA to those measured by liquid chromatography combined with triple quadropole mass spectrometry (LC/MS/MS), a highly specific method. Additionally, we conducted a biological validation to assure that the measurements of fecal concentrations reflected physiological levels of the hormone of interest. Several tests produced expected results that led us to conclude that our RIAs can reliably measure fT and fE in both sexes, and that within-sex comparisons of these measures are valid: (i) fTRIA were significantly correlated to fTLC/MS/MS for both sexes; (ii) fTRIA were higher in adult than in immature males; (iii) fTRIA were higher in pregnant than non-pregnant females; (iv) fERIA were correlated with 17β-estradiol (fE2) and with estrone (fE1) determined by LC/MS/MS in pregnant females; (v) fERIA were significantly correlated with fE2 in non-pregnant females and nearly significantly correlated in males; (vi) fERIA were higher in adult males than in immature males. fERIA were higher in females than in males, as predicted, but unexpectedly, fTRIA were higher in females than in males, suggesting a difference in steroid metabolism in the two sexes; consequently, we conclude that while within-sex comparisons are valid, fTRIA should not be used for intersexual comparisons. Our results should open the field to important additional studies, as to date the roles of testosterone in females and estrogens in males have been little investigated. PMID:24798581

Comparative Accuracy of Facial Models Fabricated Using Traditional and 3D Imaging Techniques.

PubMed

Lincoln, Ketu P; Sun, Albert Y T; Prihoda, Thomas J; Sutton, Alan J

2016-04-01

The purpose of this investigation was to compare the accuracy of facial models fabricated using facial moulage impression methods to the three-dimensional printed (3DP) fabrication methods using soft tissue images obtained from cone beam computed tomography (CBCT) and 3D stereophotogrammetry (3D-SPG) scans. A reference phantom model was fabricated using a 3D-SPG image of a human control form with ten fiducial markers placed on common anthropometric landmarks. This image was converted into the investigation control phantom model (CPM) using 3DP methods. The CPM was attached to a camera tripod for ease of image capture. Three CBCT and three 3D-SPG images of the CPM were captured. The DICOM and STL files from the three 3dMD and three CBCT were imported to the 3DP, and six testing models were made. Reversible hydrocolloid and dental stone were used to make three facial moulages of the CPM, and the impressions/casts were poured in type IV gypsum dental stone. A coordinate measuring machine (CMM) was used to measure the distances between each of the ten fiducial markers. Each measurement was made using one point as a static reference to the other nine points. The same measuring procedures were accomplished on all specimens. All measurements were compared between specimens and the control. The data were analyzed using ANOVA and Tukey pairwise comparison of the raters, methods, and fiducial markers. The ANOVA multiple comparisons showed significant difference among the three methods (p < 0.05). Further, the interaction of methods versus fiducial markers also showed significant difference (p < 0.05). The CBCT and facial moulage method showed the greatest accuracy. 3DP models fabricated using 3D-SPG showed statistical difference in comparison to the models fabricated using the traditional method of facial moulage and 3DP models fabricated from CBCT imaging. 3DP models fabricated using 3D-SPG were less accurate than the CPM and models fabricated using facial moulage and CBCT imaging techniques. © 2015 by the American College of Prosthodontists.

Comparison of the optical depth of total ozone and atmospheric aerosols in Poprad-Gánovce, Slovakia

NASA Astrophysics Data System (ADS)

Hrabčák, Peter

2018-06-01

The amount of ultraviolet solar radiation reaching the Earth's surface is significantly affected by atmospheric ozone along with aerosols. The present paper is focused on a comparison of the total ozone and atmospheric aerosol optical depth in the area of Poprad-Gánovce, which is situated at the altitude of 706 m a. s. l. in the vicinity of the highest mountain in the Carpathian mountains. The direct solar ultraviolet radiation has been measured here continuously since August 1993 using a Brewer MKIV ozone spectrophotometer. These measurements have been used to calculate the total amount of atmospheric ozone and, subsequently, its optical depth. They have also been used to determine the atmospheric aerosol optical depth (AOD) using the Langley plot method. Results obtained by this method were verified by means of comparison with a method that is part of the Brewer operating software, as well as with measurements made by a Cimel sun photometer. Diffuse radiation, the stray-light effect and polarization corrections were applied to calculate the AOD using the Langley plot method. In this paper, two factors that substantially attenuate the flow of direct ultraviolet solar radiation to the Earth's surface are compared. The paper presents results for 23 years of measurements, namely from 1994 to 2016. Values of optical depth were determined for the wavelengths of 306.3, 310, 313.5, 316.8 and 320 nm. A statistically significant decrease in the total optical depth of the atmosphere was observed with all examined wavelengths. Its root cause is the statistically significant decline in the optical depth of aerosols.

Comparison of 15 evaporation methods applied to a small mountain lake in the northeastern USA

USGS Publications Warehouse

Rosenberry, D.O.; Winter, T.C.; Buso, D.C.; Likens, G.E.

2007-01-01

Few detailed evaporation studies exist for small lakes or reservoirs in mountainous settings. A detailed evaporation study was conducted at Mirror Lake, a 0.15 km2 lake in New Hampshire, northeastern USA, as part of a long-term investigation of lake hydrology. Evaporation was determined using 14 alternate evaporation methods during six open-water seasons and compared with values from the Bowen-ratio energy-budget (BREB) method, considered the standard. Values from the Priestley-Taylor, deBruin-Keijman, and Penman methods compared most favorably with BREB-determined values. Differences from BREB values averaged 0.19, 0.27, and 0.20 mm d-1, respectively, and results were within 20% of BREB values during more than 90% of the 37 monthly comparison periods. All three methods require measurement of net radiation, air temperature, change in heat stored in the lake, and vapor pressure, making them relatively data intensive. Several of the methods had substantial bias when compared with BREB values and were subsequently modified to eliminate bias. Methods that rely only on measurement of air temperature, or air temperature and solar radiation, were relatively cost-effective options for measuring evaporation at this small New England lake, outperforming some methods that require measurement of a greater number of variables. It is likely that the atmosphere above Mirror Lake was affected by occasional formation of separation eddies on the lee side of nearby high terrain, although those influences do not appear to be significant to measured evaporation from the lake when averaged over monthly periods. ?? 2007 Elsevier B.V. All rights reserved.

Comparison of analytical and experimental steadyand unsteady-pressure distributions at Mach number 0.78 for a high-aspect-ratio supercritical wing model with oscillating control surfaces

NASA Technical Reports Server (NTRS)

Mccain, W. E.

1984-01-01

The unsteady aerodynamic lifting surface theory, the Doublet Lattice method, with experimental steady and unsteady pressure measurements of a high aspect ratio supercritical wing model at a Mach number of 0.78 were compared. The steady pressure data comparisons were made for incremental changes in angle of attack and control surface deflection. The unsteady pressure data comparisons were made at set angle of attack positions with oscillating control surface deflections. Significant viscous and transonic effects in the experimental aerodynamics which cannot be predicted by the Doublet Lattice method are shown. This study should assist development of empirical correction methods that may be applied to improve Doublet Lattice calculations of lifting surface aerodynamics.

International comparison of activity measurements of a solution of 75Se

NASA Astrophysics Data System (ADS)

Ratel, Guy

2002-04-01

Activity measurements of a solution of 75Se, supplied by the BIPM, have been carried out by 21 laboratories within the framework of an international comparison. Seven different methods were used. Details on source preparation, experimental facilities and counting data are reported. The measured activity-concentration values show a total spread of 6.62% before correction and 6.02% after correction for delayed events, with standard deviations of the unweighted means of 0.45% and 0.36%, respectively. The correction for delayed events was measured directly by four laboratories. Unfortunately no consensus on the activity value could be deduced from their results. The results of the comparison have been entered in the tables of the International Reference System (SIR) for γ-ray emitting radionuclides. The half-life of the metastable state was also determined by two laboratories and found to be in good agreement with the values found in the literature.

ClusCo: clustering and comparison of protein models.

PubMed

Jamroz, Michal; Kolinski, Andrzej

2013-02-22

The development, optimization and validation of protein modeling methods require efficient tools for structural comparison. Frequently, a large number of models need to be compared with the target native structure. The main reason for the development of Clusco software was to create a high-throughput tool for all-versus-all comparison, because calculating similarity matrix is the one of the bottlenecks in the protein modeling pipeline. Clusco is fast and easy-to-use software for high-throughput comparison of protein models with different similarity measures (cRMSD, dRMSD, GDT_TS, TM-Score, MaxSub, Contact Map Overlap) and clustering of the comparison results with standard methods: K-means Clustering or Hierarchical Agglomerative Clustering. The application was highly optimized and written in C/C++, including the code for parallel execution on CPU and GPU, which resulted in a significant speedup over similar clustering and scoring computation programs.

Usability of calcium carbide gas pressure method in hydrological sciences

NASA Astrophysics Data System (ADS)

Arsoy, S.; Ozgur, M.; Keskin, E.; Yilmaz, C.

2013-10-01

Soil moisture is a key engineering variable with major influence on ecological and hydrological processes as well as in climate, weather, agricultural, civil and geotechnical applications. Methods for quantification of the soil moisture are classified into three main groups: (i) measurement with remote sensing, (ii) estimation via (soil water balance) simulation models, and (iii) measurement in the field (ground based). Remote sensing and simulation modeling require rapid ground truthing with one of the ground based methods. Calcium carbide gas pressure (CCGP) method is a rapid measurement procedure for obtaining soil moisture and relies on the chemical reaction of the calcium carbide reagent with the water in soil pores. However, the method is overlooked in hydrological science applications. Therefore, the purpose of this study is to evaluate the usability of the CCGP method in comparison with standard oven-drying and dielectric methods in terms of accuracy, time efficiency, operational ease, cost effectiveness and safety for quantification of the soil moisture over a wide range of soil types. The research involved over 250 tests that were carried out on 15 different soil types. It was found that the accuracy of the method is mostly within ±1% of soil moisture deviation range in comparison to oven-drying, and that CCGP method has significant advantages over dielectric methods in terms of accuracy, cost, operational ease and time efficiency for the purpose of ground truthing.

Analysis method comparison of on-time and on-budget data.

DOT National Transportation Integrated Search

2007-02-01

New Mexico Department of Transportation (NMDOT) results for On-Time and On-Budget performance measures as reported in (AASHTO/SCoQ) NCHRP 20-24(37) Project Measuring Performance Among State DOTs (Phase I) are lower than construction personnel kno...

An investigation of a PRESAGE® in-vivo dosimeter for brachytherapy

PubMed Central

Vidovic, A K; Juang, T; Meltsner, S; Adamovics, J; Chino, J; Steffey, B; Craciunescu, O; Oldham, M

2014-01-01

Determining accurate in-vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in-vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm x 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® In-Vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0–15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy·cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (~1mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in-vivo dose verification, although improved sensitivity would be desirable. Advantages include high-resolution, convenience and fast, low-cost readout. PMID:24957850

An investigation of a PRESAGE® in vivo dosimeter for brachytherapy

NASA Astrophysics Data System (ADS)

Vidovic, A. K.; Juang, T.; Meltsner, S.; Adamovics, J.; Chino, J.; Steffey, B.; Craciunescu, O.; Oldham, M.

2014-07-01

Determining accurate in vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm × 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® in vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with a commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0-15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy ṡ cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (˜1 mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in vivo dose verification, although improved sensitivity would be desirable. Advantages include high-resolution, convenience and fast, low-cost readout.

Conduct of a personal radiofrequency electromagnetic field measurement study: proposed study protocol

PubMed Central

2010-01-01

Background The development of new wireless communication technologies that emit radio frequency electromagnetic fields (RF-EMF) is ongoing, but little is known about the RF-EMF exposure distribution in the general population. Previous attempts to measure personal exposure to RF-EMF have used different measurement protocols and analysis methods making comparisons between exposure situations across different study populations very difficult. As a result, observed differences in exposure levels between study populations may not reflect real exposure differences but may be in part, or wholly due to methodological differences. Methods The aim of this paper is to develop a study protocol for future personal RF-EMF exposure studies based on experience drawn from previous research. Using the current knowledge base, we propose procedures for the measurement of personal exposure to RF-EMF, data collection, data management and analysis, and methods for the selection and instruction of study participants. Results We have identified two basic types of personal RF-EMF measurement studies: population surveys and microenvironmental measurements. In the case of a population survey, the unit of observation is the individual and a randomly selected representative sample of the population is needed to obtain reliable results. For microenvironmental measurements, study participants are selected in order to represent typical behaviours in different microenvironments. These two study types require different methods and procedures. Conclusion Applying our proposed common core procedures in future personal measurement studies will allow direct comparisons of personal RF-EMF exposures in different populations and study areas. PMID:20487532

Improved Atmospheric Correction for AVIRIS Spectra from Inland Waters

NASA Technical Reports Server (NTRS)

Gastil, Mary; Melack, John M.

1998-01-01

Remote sensing reflectance (Rrs) cannot be measured directly. Comparison of Rrs calculated from field measurements to Rrs calculated from AVIRIS spectra and the atmospheric radiative transfer model modtran provides a measure of the accuracy of our method. That and other comparisons are presented here as a validation of a method of retrieving Rrs from inland waters from AVIRIS radiance. The method of collecting field measurements for Rrs is described in Hamilton, 1993. Retrieval of Rrs from AVIRIS using modtran was developed from Carder, 1993. AVIRIS radiance is reduced by the path radiance modeled by modtran and divided by one-way transmission. Skylight, modeled by modtran, specularly reflected from the lake surface, is then subtracted from this radiance, leaving only that radiance which has come from under water. This water-leaving radiance is then normalized by the downwelling irradiance incident at the surface as modeled by modtran. Our improved retrieval of Rrs has allowed us to fit a single curve to a set of 134 pairs of AVIRIS Rrs and measured chlorophyll gathered on eight experiments at Mono Lake. Previously, spectra from different surveys varied more due to lingering atmospheric effects and/or radiometric calibration imprecision than they varied due to chlorophyll.

Comparison of a New Multiplex Immunoassay for Measurement of Ferritin, Soluble Transferrin Receptor, Retinol-Binding Protein, C-Reactive Protein and α1-Acid-glycoprotein Concentrations against a Widely-Used s-ELISA Method

PubMed Central

Henderson, Amanda M.; Samson, Kaitlyn L. I.; Aljaadi, Abeer M.; Devlin, Angela M.; Becquey, Elodie; Wirth, James P.

2018-01-01

Recently, a multiplex ELISA (Quansys Biosciences) was developed that measures ferritin, soluble transferrin receptor (sTfR), retinol-binding protein (RBP), C-reactive protein (CRP), α1-acid glycoprotein (AGP), thyroglobulin, and histidine-rich protein 2. Our primary aim was to conduct a method-comparison study to compare five biomarkers (ferritin, sTfR, RBP, CRP, and AGP) measured with the Quansys assay and a widely-used s-ELISA (VitMin Lab, Willstaett, Germany) with use of serum samples from 180 women and children from Burkina Faso, Cambodia, and Malaysia. Bias and concordance were used to describe the agreement in values measured by the two methods. We observed poor overall agreement between the methods, both with regard to biomarker concentrations and deficiency prevalence estimates. Several measurements were outside of the limit of detection with use of the Quansys ELISA (total n = 42 for ferritin, n = 2 for sTfR, n = 0 for AGP, n = 5 for CRP, n = 22 for RBP), limiting our ability to interpret assay findings. Although the Quansys ELISA has great potential to simplify laboratory analysis of key nutritional and inflammation biomarkers, there are some weaknesses in the procedures. Overall, we found poor comparability of results between methods. Besides addressing procedural issues, additional validation of the Quansys against a gold standard method is warranted for future research. PMID:29393894

Detector absorptivity measuring method and apparatus

NASA Technical Reports Server (NTRS)

Sheets, R. E. (Inventor)

1976-01-01

A method and apparatus for measuring the absorptivity of a radiation detector by making the detector an integral part of a cavity radiometer are described. By substituting the detector for the surface of the cavity upon which the radiation first impinges a comparison is made between the quantity of radiation incident upon the detector and the quantity reflected from the detector. The difference between the two is a measurement of the amount of radiation absorbed by the detector.

Quantitative data standardization of X-ray based densitometry methods

NASA Astrophysics Data System (ADS)

Sergunova, K. A.; Petraikin, A. V.; Petrjajkin, F. A.; Akhmad, K. S.; Semenov, D. S.; Potrakhov, N. N.

2018-02-01

In the present work is proposed the design of special liquid phantom for assessing the accuracy of quantitative densitometric data. Also are represented the dependencies between the measured bone mineral density values and the given values for different X-ray based densitometry techniques. Shown linear graphs make it possible to introduce correction factors to increase the accuracy of BMD measurement by QCT, DXA and DECT methods, and to use them for standardization and comparison of measurements.

Comparison of Two Acoustic Waveguide Methods for Determining Liner Impedance

NASA Technical Reports Server (NTRS)

Jones, Michael G.; Watson, Willie R.; Tracy, Maureen B.; Parrott, Tony L.

2001-01-01

Acoustic measurements taken in a flow impedance tube are used to assess the relative accuracy of two waveguide methods for impedance eduction in the presence of grazing flow. The aeroacoustic environment is assumed to contain forward and backward-traveling acoustic waves, consisting of multiple modes, and uniform mean flow. Both methods require a measurement of the complex acoustic pressure profile over the length of the test liner. The Single Mode Method assumes that the sound pressure level and phase decay-rates of a single progressive mode can be extracted from this measured complex acoustic pressure profile. No a priori assumptions are made in the Finite Element. Method regarding the modal or reflection content in the measured acoustic pressure profile. The integrity of each method is initially demonstrated by how well their no-flow impedances match those acquired in a normal incidence impedance tube. These tests were conducted using ceramic tubular and conventional perforate liners. Ceramic tubular liners were included because of their impedance insensitivity to mean flow effects. Conversely, the conventional perforate liner was included because its impedance is known to be sensitive to mean flow velocity effects. Excellent comparisons between impedance values educed with the two waveguide methods in the absence of mean flow and the corresponding values educed with the normal incident impedance tube were observed. The two methods are then compared for mean flow Mach numbers up to 0.5, and are shown to give consistent results for both types of test liners. The quality of the results indicates that the Single Mode Method should be used when the measured acoustic pressure profile is clearly dominated by a single progressive mode, and the Finite Element Method should be used for all other cases.

KEY COMPARISON: Final report on CCPR K1-a: Spectral irradiance from 250 nm to 2500 nm

NASA Astrophysics Data System (ADS)

Woolliams, Emma R.; Fox, Nigel P.; Cox, Maurice G.; Harris, Peter M.; Harrison, Neil J.

2006-01-01

The CCPR K1-a key comparison of spectral irradiance (from 250 nm to 2500 nm) was carried out to meet the requirements of the Mutual Recognition Arrangement by 13 participating national metrology institutes (NMIs). Because of the fragile nature of the tungsten halogen lamps used as comparison artefacts, the comparison was arranged as a star comparison with three lamps per participant. NPL (United Kingdom) piloted the comparison and, by measuring all lamps, provided a link between participants' measurements. The other participants were BNM-INM (France), CENAM (Mexico), CSIRO (Australia), HUT (Finland), IFA-CSIC (Spain), MSL-IRL (New Zealand), NIM (China), NIST (United States of America), NMIJ (Japan), NRC (Canada), PTB (Germany) and VNIIOFI (Russian Federation). Before the analysis was completed and the results known, the pilot discussed with each participant which lamp measurements should be included as representative of their comparison. As a consequence of this check, at least one measurement was excluded from one third of the lamps because of changes due to transportations. The comparison thus highlighted the difficulty regarding the availability of suitable transfer standards for the dissemination of spectral irradiance. The use of multiple lamps and multiple measurements ensured sufficient redundancy that all participants were adequately represented. In addition, during this pre-draft A phase all participants had the opportunity to review the uncertainty budgets and methods of all other participants. This new process helped to ensure that all submitted results and their associated uncertainties were evaluated in a consistent manner. The comparison was analysed using a model-based method which regarded each lamp as having a stable spectral irradiance and the measurements made by an NMI as systematically influenced by a factor that applies to all that NMI's measurements. The aim of the analysis was to estimate the systematic factor for each NMI. Across the spectral region (250 nm to 2500 nm) there were 44 wavelengths at which a comparison was made. These were treated entirely independently and thus the report describes 44 comparisons. For wavelengths from 250 nm to 800 nm (apart from 300 nm) all participants had unilateral degrees of equivalence (DoEs) with values consistent with their uncertainties for a coverage level k = 2. At all other wavelengths (apart from 1400 nm) all participants achieved consistency at the k = 4 level for the unilateral DoEs and the vast majority within k = 3. The results are a significant improvement over those of the previous comparison in 1990, especially considering that the declared uncertainties of most participants have been substantially improved over the intervening decade. These results are evidence of the value of the effort devoted to the development of improved spectral scales (and of the evaluation of their uncertainty) by many NMIs in recent years. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Assessing five field sampling methods to monitor Yellowstone National Park's northern ungulate winter range: the advantages and disadvantages of implementing a new sampling protocol

Treesearch

Pamela G. Sikkink; Roy Renkin; Geneva Chong; Art Sikkink

2013-01-01

The five field sampling methods tested for this study differed in richness and Simpson's Index values calculated from the raw data. How much the methods differed, and which ones were most similar to each other, depended on which diversity measure and which type of data were used for comparisons. When the number of species (richness) was used as a measure of...

Comparison of Predicted and Measured Soil Retention Curve in Lombardy Region Northern of Italy

NASA Astrophysics Data System (ADS)

Wassar, Fatma; Rienzner, Michele; Chiaradia, Enrico Antonio; Gandolfi, Claudio

2013-04-01

Water retention characteristics are crucial input parameters in any modeling study on water flow and solute transport. These properties are difficult to measure and therefore the use of both direct and indirect methods is required in order to adequately describe them with sufficient accuracy. Several field methods, laboratory methods and theoretical models for such determinations exist, each having their own limitations and advantages (Stephens, 1994). Therefore, extensive comparisons between estimated, field and laboratory results to determine it still requires their validity for a range of different soils and specific cases. This study attempts to make a contribution specifically in this connection. The soil water retention characteristics were determined in two representative sites (PMI-1 and PMI-5) located in Landriano field, in Lombardy region, northern Italy. In the laboratory, values of both volumetric water content (θ) and soil water matric potential (h) are measured in the same sample using the tensiometric box and pressure plate apparatus. Field determination of soil water retention involved measurements of soil water content with SENTEK probes, and matric potential with tensiometers. The retention curve characteristics were also determined using some of the most commonly cited and some recently developed PTFs that use soil properties such as particle-size distribution (sand, silt, and clay content), organic matter or organic Carbon content, and dry bulk density. Field methods are considered to be more representative than laboratory and estimation methods for determining water retention characteristics (Marion et al., 1996). Therefore, field retention curves were compared against retention curves obtained from laboratory measurements and PTFs estimations. The performances of laboratory and PTFs in predicting field measured data were evaluated using root mean square error (RMSE) and bias. The comparison showed that laboratory measurements were the most accurate. They had the highest ranking for the validation indices (RMSE ranging between 2.4 and 7.7% and bias between 0.1 and 6.4%). The second best technique was the PTF Rosetta (Schaap et al. 2001). They perform only slightly poorer than the laboratory measurements (RMSE ranging between 2.7 and 10% and bias between 0.3 and 7.7%). The lowest prediction accuracy is observed for the Rawls and Brakensiek (1985) PTF (RMSE ranging between 6.3 and 17% and bias between 5 and 10%) which is in contradiction with previous finding (Calzolari et al., 2001), showing that this function is well representing the retention characteristics of the area. We conclude that the Rosetta PTF developed by Schaap et al (2001) appears to be well suited to predict the soil moisture retention curve from easily available soil properties in the Lombardy area and further field investigations would be useful to reinforce this finding. Keywords: water retention curve; laboratory measurements; field measurements; pedotransfert functions; comparison.

A New Method to Cross Calibrate and Validate TOMS, SBUV/2, and SCIAMACHY Measurements

NASA Technical Reports Server (NTRS)

Ahmad, Ziauddin; Hilsenrath, Ernest; Einaudi, Franco (Technical Monitor)

2001-01-01

A unique method to validate back scattered ultraviolet (buv) type satellite data that complements the measurements from existing ground networks is proposed. The method involves comparing the zenith sky radiance measurements from the ground to the nadir radiance measurements taken from space. Since the measurements are compared directly, the proposed method is superior to any other method that involves comparing derived products (for example, ozone), because comparison of derived products involve inversion algorithms which are susceptible to several type of errors. Forward radiative transfer (RT) calculations show that for an aerosol free atmosphere, the ground-based zenith sky radiance measurement and the satellite nadir radiance measurements can be predicted with an accuracy of better than 1 percent. The RT computations also show that for certain values of the solar zenith angles, the radiance comparisons could be better than half a percent. This accuracy is practically independent of ozone amount and aerosols in the atmosphere. Experiences with the Shuttle Solar Backscatter Ultraviolet (SSBUV) program show that the accuracy of the ground-based zenith sky radiance measuring instrument can be maintained at a level of a few tenth of a percent. This implies that the zenith sky radiance measurements can be used to validate Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet (SBUV/2), and The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) radiance data. Also, this method will help improve the long term precision of the measurements for better trend detection and the accuracy of other BUV products such as tropospheric ozone and aerosols. Finally, in the long term, this method is a good candidate to inter-calibrate and validate long term observations of upcoming operational instruments such as Global Ozone Monitoring Experiment (GOME-2), Ozone Mapping Instrument (OMI), Ozone Dynamics Ultraviolet Spectrometer (ODUS), and Ozone Mapping and Profiler Suite (OMPS).

Validation and Comparison of Two Sampling Methods to Assess Dermal Exposure to Drilling Fluids and Crude Oil

PubMed Central

Galea, Karen S.; McGonagle, Carolyn; Sleeuwenhoek, Anne; Todd, David; Jiménez, Araceli Sánchez

2014-01-01

Dermal exposure to drilling fluids and crude oil is an exposure route of concern. However, there have been no published studies describing sampling methods or reporting dermal exposure measurements. We describe a study that aimed to evaluate a wipe sampling method to assess dermal exposure to an oil-based drilling fluid and crude oil, as well as to investigate the feasibility of using an interception cotton glove sampler for exposure on the hands/wrists. A direct comparison of the wipe and interception methods was also completed using pigs’ trotters as a surrogate for human skin and a direct surface contact exposure scenario. Overall, acceptable recovery and sampling efficiencies were reported for both methods, and both methods had satisfactory storage stability at 1 and 7 days, although there appeared to be some loss over 14 days. The methods’ comparison study revealed significantly higher removal of both fluids from the metal surface with the glove samples compared with the wipe samples (on average 2.5 times higher). Both evaluated sampling methods were found to be suitable for assessing dermal exposure to oil-based drilling fluids and crude oil; however, the comparison study clearly illustrates that glove samplers may overestimate the amount of fluid transferred to the skin. Further comparison of the two dermal sampling methods using additional exposure situations such as immersion or deposition, as well as a field evaluation, is warranted to confirm their appropriateness and suitability in the working environment. PMID:24598941

Epileptic seizure prediction by non-linear methods

DOEpatents

Hively, Lee M.; Clapp, Ned E.; Daw, C. Stuart; Lawkins, William F.

1999-01-01

Methods and apparatus for automatically predicting epileptic seizures monitor and analyze brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis tools; obtaining time serial trends in the nonlinear measures; comparison of the trend to known seizure predictors; and providing notification that a seizure is forthcoming.

An improved model for whole genome phylogenetic analysis by Fourier transform.

PubMed

Yin, Changchuan; Yau, Stephen S-T

2015-10-07

DNA sequence similarity comparison is one of the major steps in computational phylogenetic studies. The sequence comparison of closely related DNA sequences and genomes is usually performed by multiple sequence alignments (MSA). While the MSA method is accurate for some types of sequences, it may produce incorrect results when DNA sequences undergone rearrangements as in many bacterial and viral genomes. It is also limited by its computational complexity for comparing large volumes of data. Previously, we proposed an alignment-free method that exploits the full information contents of DNA sequences by Discrete Fourier Transform (DFT), but still with some limitations. Here, we present a significantly improved method for the similarity comparison of DNA sequences by DFT. In this method, we map DNA sequences into 2-dimensional (2D) numerical sequences and then apply DFT to transform the 2D numerical sequences into frequency domain. In the 2D mapping, the nucleotide composition of a DNA sequence is a determinant factor and the 2D mapping reduces the nucleotide composition bias in distance measure, and thus improving the similarity measure of DNA sequences. To compare the DFT power spectra of DNA sequences with different lengths, we propose an improved even scaling algorithm to extend shorter DFT power spectra to the longest length of the underlying sequences. After the DFT power spectra are evenly scaled, the spectra are in the same dimensionality of the Fourier frequency space, then the Euclidean distances of full Fourier power spectra of the DNA sequences are used as the dissimilarity metrics. The improved DFT method, with increased computational performance by 2D numerical representation, can be applicable to any DNA sequences of different length ranges. We assess the accuracy of the improved DFT similarity measure in hierarchical clustering of different DNA sequences including simulated and real datasets. The method yields accurate and reliable phylogenetic trees and demonstrates that the improved DFT dissimilarity measure is an efficient and effective similarity measure of DNA sequences. Due to its high efficiency and accuracy, the proposed DFT similarity measure is successfully applied on phylogenetic analysis for individual genes and large whole bacterial genomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Initial estimate of NOAA-9 SBUV/2 total ozone drift: Based on comparison with re-calibrated TOMS measurements and pair justification of SBUV/2

NASA Technical Reports Server (NTRS)

Wellemeyer, C. G.; Taylor, S. L.; Gu, X. U.; Mcpeters, Richard D.; Hudson, R. D.

1990-01-01

Newly recalibrated version 6 Total Ozone Mapping Spectrometer (TOMS) data are used as a reference measurement in a comparison of monthly means of total ozone in 10 degree latitude zones from SBUV/2 and the nadir measurements from TOMS. These comparisons indicate a roughly linear long-term drift in SBUV/2 total ozone relative to TOMS of about 2.5 Dobson units per year at the equator over the first three years of SBUV/2. The pari justification technique is also applied to the SBUV/2 measurements in a manner similar to that used for SBUV and TOMS. The higher solar zenith angles associated with the afternoon orbit of NOAA-9 and the large changes in solar zenith angle associated with its changing equator crossing time degrade the accuracy of the pair justification method relative to its application to SBUV and TOMS, but the results are consistent with the SBUV/2-TOMS comparisons, and show a roughly linear drift in SBUV/2 of 2.5 to 4.5 Dobson units per year in equatorial ozone.

A cross-comparison of field, spectral, and lidar estimates of forest canopy cover

Treesearch

Alistair M. S. Smith; Michael J. Falkowski; Andrew T. Hudak; Jeffrey S. Evans; Andrew P. Robinson; Caiti M. Steele

2010-01-01

A common challenge when comparing forest canopy cover and similar metrics across different ecosystems is that there are many field- and landscape-level measurement methods. This research conducts a cross-comparison and evaluation of forest canopy cover metrics produced using unmixing of reflective spectral satellite data, light detection and ranging (lidar) data, and...

The "Public Opinion Survey of Human Attributes-Stuttering" (POSHA-S): Summary Framework and Empirical Comparisons

ERIC Educational Resources Information Center

St. Louis, Kenneth O.

2011-01-01

Purpose: The "Public Opinion Survey of Human Attributes-Stuttering" ("POSHA-S") was developed to make available worldwide a standard measure of public attitudes toward stuttering that is practical, reliable, valid, and translatable. Mean data from past field studies as comparisons for interpretation of "POSHA-S" results are reported. Method: Means…

Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimm, K. N.

1998-07-13

In anticipation of processing irradiated EBR-II depleted uranium blanket subassemblies in the Fuel Conditioning Facility (FCF) at ANL-West, it has been possible to obtain a limited set of destructive chemical analyses of samples from a single EBR-II blanket subassembly. Comparison of calculated values with these measurements is being used to validate a depletion methodology based on a limited number of generic models of EBR-II to simulate the irradiation history of these subassemblies. Initial comparisons indicate these methods are adequate to meet the operations and material control and accountancy (MC and A) requirements for the FCF, but also indicate several shortcomingsmore » which may be corrected or improved.« less

Assessment of interchangeability rate between 2 methods of measurements: An example with a cardiac output comparison study.

PubMed

Lorne, Emmanuel; Diouf, Momar; de Wilde, Robert B P; Fischer, Marc-Olivier

2018-02-01

The Bland-Altman (BA) and percentage error (PE) methods have been previously described to assess the agreement between 2 methods of medical or laboratory measurements. This type of approach raises several problems: the BA methodology constitutes a subjective approach to interchangeability, whereas the PE approach does not take into account the distribution of values over a range. We describe a new methodology that defines an interchangeability rate between 2 methods of measurement and cutoff values that determine the range of interchangeable values. We used a simulated data and a previously published data set to demonstrate the concept of the method. The interchangeability rate of 5 different cardiac output (CO) pulse contour techniques (Wesseling method, LiDCO, PiCCO, Hemac method, and Modelflow) was calculated, in comparison with the reference pulmonary artery thermodilution CO using our new method. In our example, Modelflow with a good interchangeability rate of 93% and a cutoff value of 4.8 L min, was found to be interchangeable with the thermodilution method for >95% of measurements. Modelflow had a higher interchangeability rate compared to Hemac (93% vs 86%; P = .022) or other monitors (Wesseling cZ = 76%, LiDCO = 73%, and PiCCO = 62%; P < .0001). Simulated data and reanalysis of a data set comparing 5 CO monitors against thermodilution CO showed that, depending on the repeatability of the reference method, the interchangeability rate combined with a cutoff value could be used to define the range of values over which interchangeability remains acceptable.

[Comparison of eddy covariance and static chamber/gas chromatogram methods in measuring ecosystem respiration].

PubMed

Zheng, Ze-Mei; Yu, Gui-Rui; Sun, Xiao-Min; Cao, Guang-Min; Wang, Yue-Si; Du, Ming-Yuan; Li, Jun; Li, Ying-Nian

2008-02-01

Based on the measurement of carbon flux by the methods of eddy covariance and static chamber/gas chromatogram, a comparison was made between the two methods in evaluating ecosystem respiration over winter wheat (Triticum aestivum)--summer maize (Zea mays) double cropland and Kobresia humilis alpine meadow. The results showed that under the conditions of obtained data having good quality, nighttime ecosystem respiration from eddy covariance measurement was significantly agreed with that from static chamber/gas chromatogram measurement, with the correlation coefficients ranging from 0.95 to 0.98, and the daytime ecosystem respiration from these two measurements also had a good consistency though the static chamber/gas chromatogram measurement often produced higher values. The daily mean value of ecosystem respiration was significantly different between these two measurements, but the seasonal pattern was similar. For winter wheat-summer maize double cropland, the difference of mean air temperature inside and outside the chamber was 1.8 degrees C, and the daily mean value of ecosystem respiration across the whole study period was 30.3% lower in eddy covariance measurement than in static chamber/gas chromatogram measurement; while for alpine meadow, the difference of the mean air temperature was 1.9 degrees C, and the daily mean value of ecosystem respiration was 31.4% lower in eddy covariance measurement than in static chamber/gas chromatogram measurement. The variance between the daily mean values of ecosystem respiration obtained from the two measurements was higher in growing season than in dormant season.

Cross Calibration of TOMS, SBUV/2 and SCIAMACHY Radiances from Ground Observations

NASA Technical Reports Server (NTRS)

Hilsenrath, Ernest; Bhartia, P. K.; Bojkov, B.; Kowaleski, M.; Labow, G.; Ahmad, Z.

2002-01-01

We have shown that validation of radiances is a very effective means for correcting absolute accuracy and long term drifts of backscatter type satellite measurements. This method by-passes the algorithms used for both satellite and ground based measurements which are normally used to validate and correct the satellite data. A new method for satellite validation is planned which will compliment measurements from the existing ground-based networks. This method will employ very accurate comparisons between ground based zenith sky radiances and satellite nadir radiances. These comparisons will rely heavily on the experience derived from the Shuttle SBUV (SSBUV) program which provided a reference standard of radiance measurements for SBUV/2, TOMS, and GOME. This new measurement program, called 'Skyrad', employs two well established capabilities at the Goddard Space Flight Center, 1) the SSBUV calibration facilities and 2) the radiative transfer codes used for the TOMS and SBUV/2 algorithms and their subsequent refinements. Radiative transfer calculations show that ground based zenith sky and satellite nadir backscatter ultraviolet comparisons can be made very accurately under certain viewing conditions. The Skyrad instruments (SSBUV, Brewer spectrophotometers, and possibly others) will be calibrated and maintained to a precision of a few tenths of a percent. Skyrad data will then enable long term calibration of upcoming satellite instruments such as QuickTOMS, SBUV/2s and SCIAMACHY with a high degree of precision. This technique can be further employed to monitor the performance of future instruments such as GOMEZ, OMI, and OMPS. Additional information is included in the original extended abstract.

Comparison of two target classification techniques

NASA Astrophysics Data System (ADS)

Chen, J. S.; Walton, E. K.

1986-01-01

Radar target classification techniques based on backscatter measurements in the resonance region (1.0-20.0 MHz) are discussed. Attention is given to two novel methods currently being tested at the radar range of Ohio State University. The methods include: (1) the nearest neighbor (NN) algorithm for determining the radar cross section (RCS) magnitude and range corrected phase at various operating frequencies; and (2) an inverse Fourier transformation of the complex multifrequency radar returns of the time domain, followed by cross correlation analysis. Comparisons are made of the performance of the two techniques as a function of signal-to-error noise ratio for different types of processing. The results of the comparison are discussed in detail.

Measurement of Cognitive Load in Multimedia Learning: A Comparison of Different Objective Measures

ERIC Educational Resources Information Center

Korbach, Andreas; Brünken, Roland; Park, Babette

2017-01-01

Different indicators are interesting for analyzing human learning processes. Recent studies analyze learning performance in combination with cognitive load, as an indicator for learners' invested mental effort. In order to compare different measures of cognitive load research, the present study uses three different objective methods and one…

[A comparison between prostatic volume measured during suprapubic ultrasonography (TAUS) and volume of the enucleated gland after open prostatectomy].

PubMed

Szewczyk, Wojciech; Prajsner, Andrzej; Kozina, Janusz; Login, Tomasz; Kaczorowski, Marek

2004-01-01

General practitioner very often uses transabdominal ultrasonograpy (TAUS) in order to measure prostatic volume. Using this method it is rather impossible to distinguish between tissue of benign prostatic hyperplasia (BPH) and prostatic tissue which forms so called surgical capsule of BPH. The aim of this study was a comparison of prostatic volume measured during suprapubic (transabdominal) ultrasonography and volume of the enucleated gland after open prostatectomy. Regarding the results authors created a nomogram based on TAUS measurement of the prostate which helps to predict the volume of BPH. They also stated that surgical capsule of the BPH makes about 1/3 of the whole volume of the prostate measured by TAUS.

A Transfer Voltage Simulation Method for Generator Step Up Transformers

NASA Astrophysics Data System (ADS)

Funabashi, Toshihisa; Sugimoto, Toshirou; Ueda, Toshiaki; Ametani, Akihiro

It has been found from measurements for 13 sets of GSU transformers that a transfer voltage of a generator step-up (GSU) transformer involves one dominant oscillation frequency. The frequency can be estimated from the inductance and capacitance values of the GSU transformer low-voltage-side. This observation has led to a new method for simulating a GSU transformer transfer voltage. The method is based on the EMTP TRANSFORMER model, but stray capacitances are added. The leakage inductance and the magnetizing resistance are modified using approximate curves for their frequency characteristics determined from the measured results. The new method is validated in comparison with the measured results.

Biases and Power for Groups Comparison on Subjective Health Measurements

PubMed Central

Hamel, Jean-François; Hardouin, Jean-Benoit; Le Neel, Tanguy; Kubis, Gildas; Roquelaure, Yves; Sébille, Véronique

2012-01-01

Subjective health measurements are increasingly used in clinical research, particularly for patient groups comparisons. Two main types of analytical strategies can be used for such data: so-called classical test theory (CTT), relying on observed scores and models coming from Item Response Theory (IRT) relying on a response model relating the items responses to a latent parameter, often called latent trait. Whether IRT or CTT would be the most appropriate method to compare two independent groups of patients on a patient reported outcomes measurement remains unknown and was investigated using simulations. For CTT-based analyses, groups comparison was performed using t-test on the scores. For IRT-based analyses, several methods were compared, according to whether the Rasch model was considered with random effects or with fixed effects, and the group effect was included as a covariate or not. Individual latent traits values were estimated using either a deterministic method or by stochastic approaches. Latent traits were then compared with a t-test. Finally, a two-steps method was performed to compare the latent trait distributions, and a Wald test was performed to test the group effect in the Rasch model including group covariates. The only unbiased IRT-based method was the group covariate Wald’s test, performed on the random effects Rasch model. This model displayed the highest observed power, which was similar to the power using the score t-test. These results need to be extended to the case frequently encountered in practice where data are missing and possibly informative. PMID:23115620

How to regress and predict in a Bland-Altman plot? Review and contribution based on tolerance intervals and correlated-errors-in-variables models.

PubMed

Francq, Bernard G; Govaerts, Bernadette

2016-06-30

Two main methodologies for assessing equivalence in method-comparison studies are presented separately in the literature. The first one is the well-known and widely applied Bland-Altman approach with its agreement intervals, where two methods are considered interchangeable if their differences are not clinically significant. The second approach is based on errors-in-variables regression in a classical (X,Y) plot and focuses on confidence intervals, whereby two methods are considered equivalent when providing similar measures notwithstanding the random measurement errors. This paper reconciles these two methodologies and shows their similarities and differences using both real data and simulations. A new consistent correlated-errors-in-variables regression is introduced as the errors are shown to be correlated in the Bland-Altman plot. Indeed, the coverage probabilities collapse and the biases soar when this correlation is ignored. Novel tolerance intervals are compared with agreement intervals with or without replicated data, and novel predictive intervals are introduced to predict a single measure in an (X,Y) plot or in a Bland-Atman plot with excellent coverage probabilities. We conclude that the (correlated)-errors-in-variables regressions should not be avoided in method comparison studies, although the Bland-Altman approach is usually applied to avert their complexity. We argue that tolerance or predictive intervals are better alternatives than agreement intervals, and we provide guidelines for practitioners regarding method comparison studies. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Comparison of different measurement methods for transmittance haze

NASA Astrophysics Data System (ADS)

Yu, Hsueh-Ling; Hsaio, Chin-Chai

2009-08-01

Transmittance haze is increasingly important to the LCD and solar cell industry. Most commercial haze measurement instruments are designed according to the method recommended in the documentary standards like ASTM D 1003 (ASTM 2003 Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics), JIS K 7361 (JIS 1997 Plastics—Determination of the Total Luminous Transmittance of Transparent Materials—Part 1: Single Beam Instrument) and ISO 14782 (ISO 1997 Plastics—Determination of Haze of Transparent Materials). To improve the measurement accuracy of the current standards, a new apparatus was designed by the Center for Measurement Standards (Yu et al 2006 Meas. Sci. Technol. 17 N29-36). Besides the methods mentioned above, a double-beam method is used in the design of some instruments. There are discrepancies between the various methods. But no matter which method is used, a white standard is always needed. This paper compares the measurement results from different methods, presents the effect of the white standard, and analyses the measurement uncertainty.

Comparison of high-pressure liquid chromatography (HPLC) and Griess reagent-spectroscopic methods for the measurement of nitrate in serum from healthy individuals in the Nordic countries.

PubMed

Larsen, Tine Lise; Nilsen, Valentina; Andersen, Dag Olav; Francis, George; Rustad, Pål; Mansoor, Mohammad Azam

2008-12-01

Bioavailability of NO can be estimated by measuring the concentration of nitrate (NO(3)) in serum. However, the methods used for the measurement NO(3) in plasma or serum show a great degree of variation. Therefore, we compared two analytical methods for the measurement of NO(3) in serum. The concentration of NO(3) in 600 serum samples collected from healthy individuals was determined by the HPLC and by the Griess reagent-spectroscopic method. The concentration of NO(3) in the samples was 29.4+/-16.1 micromol/L and 26.2+/-14.0 micromol/L (mean+/-SD) measured by HPLC and Griess reagent-spectroscopic method respectively (p<0.0001). We detected a significant correlation between the two methods (R=0.81, p<0.0001). A significant correlation between the two methods may suggest that either method can be used for the measurement of NO(3) in serum, however the Griess reagent-spectroscopic method measures lower concentrations of NO(3) than the HPLC method.

Activity measurements of 55Fe by two different methods

NASA Astrophysics Data System (ADS)

da Cruz, Paulo A. L.; Iwahara, Akira; da Silva, Carlos J.; Poledna, Roberto; Loureiro, Jamir S.; da Silva, Monica A. L.; Ruzzarin, Anelise

2018-03-01

A calibrated germanium detector and CIEMAT/NIST liquid scintillation method were used in the standardization of solution of 55Fe coming from a key-comparison BIPM. Commercial cocktails were used in source preparation for activity measurements in CIEMAT/NIST method. Measurements were performed in Liquid Scintillation Counter. In the germanium counting method standard point sources were prepared for obtaining atomic number versus efficiency curve of the detector in order to obtain the efficiency of 5.9 keV KX-ray of 55Fe by interpolation. The activity concentrations obtained were 508.17 ± 3.56 and 509.95 ± 16.20 kBq/g for CIEMAT/NIST and germanium methods, respectively.

COOMET pilot comparison 473/RU-a/09: Comparison of hydrophone calibrations in the frequency range 250 Hz to 200 kHz

NASA Astrophysics Data System (ADS)

Yi, Chen; Isaev, A. E.; Yuebing, Wang; Enyakov, A. M.; Teng, Fei; Matveev, A. N.

2011-01-01

A description is given of the COOMET project 473/RU-a/09: a pilot comparison of hydrophone calibrations at frequencies from 250 Hz to 200 kHz between Hangzhou Applied Acoustics Research Institute (HAARI, China)—pilot laboratory—and Russian National Research Institute for Physicotechnical and Radio Engineering Measurements (VNIIFTRI, Designated Institute of Russia of the CIPM MRA). Two standard hydrophones, B&K 8104 and TC 4033, were calibrated and compared to assess the current state of hydrophone calibration of HAARI (China) and Russia. Three different calibration methods were applied: a vibrating column method, a free-field reciprocity method and a comparison method. The standard facilities of each laboratory were used, and three different sound fields were applied: pressure field, free-field and reverberant field. The maximum deviation of the sensitivities of two hydrophones between the participants' results was 0.36 dB. Main text. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCAUV-KCWG.

Comparison of optomagnetic and AC susceptibility readouts in a magnetic nanoparticle agglutination assay for detection of C-reactive protein.

PubMed

Fock, Jeppe; Parmvi, Mattias; Strömberg, Mattias; Svedlindh, Peter; Donolato, Marco; Hansen, Mikkel Fougt

2017-02-15

There is an increasing need to develop biosensor methods that are highly sensitive and that can be combined with low-cost consumables. The use of magnetic nanoparticles (MNPs) is attractive because their detection is compatible with low-cost disposables and because application of a magnetic field can be used to accelerate assay kinetics. We present the first study and comparison of the performance of magnetic susceptibility measurements and a newly proposed optomagnetic method. For the comparison we use the C-reactive protein (CRP) induced agglutination of identical samples of 100nm MNPs conjugated with CRP antibodies. Both methods detect agglutination as a shift to lower frequencies in measurements of the dynamics in response to an applied oscillating magnetic field. The magnetic susceptibility method probes the magnetic response whereas the optomagnetic technique probes the modulation of laser light transmitted through the sample. The two techniques provided highly correlated results upon agglutination when they measure the decrease of the signal from the individual MNPs (turn-off detection strategy), whereas the techniques provided different results, strongly depending on the read-out frequency, when detecting the signal due to MNP agglomerates (turn-on detection strategy). These observations are considered to be caused by differences in the volume-dependence of the magnetic and optical signals from agglomerates. The highest signal from agglomerates was found in the optomagnetic signal at low frequencies. Copyright © 2016 Elsevier B.V. All rights reserved.

[Comparison of three methods for measuring multiple morbidity according to the use of health resources in primary healthcare].

PubMed

Sicras-Mainar, Antoni; Velasco-Velasco, Soledad; Navarro-Artieda, Ruth; Blanca Tamayo, Milagrosa; Aguado Jodar, Alba; Ruíz Torrejón, Amador; Prados-Torres, Alexandra; Violan-Fors, Concepción

2012-06-01

To compare three methods of measuring multiple morbidity according to the use of health resources (cost of care) in primary healthcare (PHC). Retrospective study using computerized medical records. Thirteen PHC teams in Catalonia (Spain). Assigned patients requiring care in 2008. The socio-demographic variables were co-morbidity and costs. Methods of comparison were: a) Combined Comorbidity Index (CCI): an index itself was developed from the scores of acute and chronic episodes, b) Charlson Index (ChI), and c) Adjusted Clinical Groups case-mix: resource use bands (RUB). The cost model was constructed by differentiating between fixed (operational) and variable costs. 3 multiple lineal regression models were developed to assess the explanatory power of each measurement of co-morbidity which were compared from the determination coefficient (R(2)), p< .05. The study included 227,235 patients. The mean unit of cost was €654.2. The CCI explained an R(2)=50.4%, the ChI an R(2)=29.2% and BUR an R(2)=39.7% of the variability of the cost. The behaviour of the ICC is acceptable, albeit with low scores (1 to 3 points), showing inconclusive results. The CCI may be a simple method of predicting PHC costs in routine clinical practice. If confirmed, these results will allow improvements in the comparison of the case-mix. Copyright © 2011 Elsevier España, S.L. All rights reserved.

Comparing and Combining Data across Multiple Sources via Integration of Paired-sample Data to Correct for Measurement Error

PubMed Central

Huang, Yunda; Huang, Ying; Moodie, Zoe; Li, Sue; Self, Steve

2014-01-01

Summary In biomedical research such as the development of vaccines for infectious diseases or cancer, measures from the same assay are often collected from multiple sources or laboratories. Measurement error that may vary between laboratories needs to be adjusted for when combining samples across laboratories. We incorporate such adjustment in comparing and combining independent samples from different labs via integration of external data, collected on paired samples from the same two laboratories. We propose: 1) normalization of individual level data from two laboratories to the same scale via the expectation of true measurements conditioning on the observed; 2) comparison of mean assay values between two independent samples in the Main study accounting for inter-source measurement error; and 3) sample size calculations of the paired-sample study so that hypothesis testing error rates are appropriately controlled in the Main study comparison. Because the goal is not to estimate the true underlying measurements but to combine data on the same scale, our proposed methods do not require that the true values for the errorprone measurements are known in the external data. Simulation results under a variety of scenarios demonstrate satisfactory finite sample performance of our proposed methods when measurement errors vary. We illustrate our methods using real ELISpot assay data generated by two HIV vaccine laboratories. PMID:22764070

A Comparison of Methods for Transforming Sentences into Test Questions for Instructional Materials. Technical Report #1.

ERIC Educational Resources Information Center

Roid, Gale; And Others

Several measurement theorists have convincingly argued that methods of writing test questions, particularly for criterion-referenced tests, should be based on operationally defined rules. This study was designed to examine and further refine a method for objectively generating multiple-choice questions for prose instructional materials. Important…

a Contemporary Approach for Evaluation of the best Measurement Capability of a Force Calibration Machine

NASA Astrophysics Data System (ADS)

Kumar, Harish

The present paper discusses the procedure for evaluation of best measurement capability of a force calibration machine. The best measurement capability of force calibration machine is evaluated by a comparison through the precision force transfer standards to the force standard machines. The force transfer standards are calibrated by the force standard machine and then by the force calibration machine by adopting the similar procedure. The results are reported and discussed in the paper and suitable discussion has been made for force calibration machine of 200 kN capacity. Different force transfer standards of nominal capacity 20 kN, 50 kN and 200 kN are used. It is found that there are significant variations in the .uncertainty of force realization by the force calibration machine according to the proposed method in comparison to the earlier method adopted.

An efficient optimization method to improve the measuring accuracy of oxygen saturation by using triangular wave optical signal

NASA Astrophysics Data System (ADS)

Li, Gang; Yu, Yue; Zhang, Cui; Lin, Ling

2017-09-01

The oxygen saturation is one of the important parameters to evaluate human health. This paper presents an efficient optimization method that can improve the accuracy of oxygen saturation measurement, which employs an optical frequency division triangular wave signal as the excitation signal to obtain dynamic spectrum and calculate oxygen saturation. In comparison to the traditional method measured RMSE (root mean square error) of SpO2 which is 0.1705, this proposed method significantly reduced the measured RMSE which is 0.0965. It is notable that the accuracy of oxygen saturation measurement has been improved significantly. The method can simplify the circuit and bring down the demand of elements. Furthermore, it has a great reference value on improving the signal to noise ratio of other physiological signals.

Comparison of various hours living fission products for absolute power density determination in VVER-1000 mock up in LR-0 reactor.

PubMed

Košťál, Michal; Švadlenková, Marie; Koleška, Michal; Rypar, Vojtěch; Milčák, Ján

2015-11-01

Measuring power level of zero power reactor is a quite difficult task. Due to the absence of measurable cooling media heating, it is necessary to employ a different method. The gamma-ray spectroscopy of fission products induced within reactor operation is one of possible ways of power determination. The method is based on the proportionality between fission product buildup and released power. The (92)Sr fission product was previously preferred as nuclide for LR-0 power determination for short-time irradiation experiments. This work aims to find more appropriate candidates, because the (92)Sr, however suitable, has a short half-life, which limits the maximal measurable amount of fuel pins within a single irradiation batch. The comparison of various isotopes is realized for (92)Sr, (97)Zr, (135)I, (91)Sr, and (88)Kr. The comparison between calculated and experimentally determined (C/E-1 values) net peak areas is assessed for these fission products. Experimental results show that studied fission products, except (88)Kr, are in comparable agreement with (92)Sr results. Since (91)Sr has notably higher half-life than (92)Sr, (91)Sr seems to be more appropriate marker in experiments with a large number of measured fuel pins. Copyright © 2015 Elsevier Ltd. All rights reserved.

Alkaline solution absorption of carbon dioxide method and apparatus

DOEpatents

Hobbs, D.T.

1991-01-01

Disclosed is a method for measuring the concentration of hydroxides (or pH) in alkaline solutions, using the tendency of hydroxides to adsorb CO{sub 2}. The method comprises passing CO{sub 2} over the surface of an alkaline solution in a remote tank before and after measurements of the CO{sub 2} concentration. Comparison of the measurements yields the adsorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to adsorption fraction. A schematic is given of a process system according to a preferred embodiment of the invention. 2 figs.

Validation and comparison of two sampling methods to assess dermal exposure to drilling fluids and crude oil.

PubMed

Galea, Karen S; McGonagle, Carolyn; Sleeuwenhoek, Anne; Todd, David; Jiménez, Araceli Sánchez

2014-06-01

Dermal exposure to drilling fluids and crude oil is an exposure route of concern. However, there have been no published studies describing sampling methods or reporting dermal exposure measurements. We describe a study that aimed to evaluate a wipe sampling method to assess dermal exposure to an oil-based drilling fluid and crude oil, as well as to investigate the feasibility of using an interception cotton glove sampler for exposure on the hands/wrists. A direct comparison of the wipe and interception methods was also completed using pigs' trotters as a surrogate for human skin and a direct surface contact exposure scenario. Overall, acceptable recovery and sampling efficiencies were reported for both methods, and both methods had satisfactory storage stability at 1 and 7 days, although there appeared to be some loss over 14 days. The methods' comparison study revealed significantly higher removal of both fluids from the metal surface with the glove samples compared with the wipe samples (on average 2.5 times higher). Both evaluated sampling methods were found to be suitable for assessing dermal exposure to oil-based drilling fluids and crude oil; however, the comparison study clearly illustrates that glove samplers may overestimate the amount of fluid transferred to the skin. Further comparison of the two dermal sampling methods using additional exposure situations such as immersion or deposition, as well as a field evaluation, is warranted to confirm their appropriateness and suitability in the working environment. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Characterization of air-coupled ultrasound transducers in the frequency range 40 kHz-2 mHz using light diffraction tomography.

PubMed

Almqvist, M; Holm, A; Persson, H W; Lindström, K

2000-01-01

The aim of this work was to show the applicability of light diffraction tomography on airborne ultrasound in the frequency range 40 kHz-2 MHz. Seven different air-coupled transducers were measured to show the method's performance regarding linearity, absolute pressure measurements, phase measurements, frequency response, S/N ratio and spatial resolution. A calibrated microphone and the pulse-echo method were used to evaluate the results. The absolute measurements agreed within the calibrated microphone's uncertainty range. Pulse waveforms and corresponding FFT diagrams show the method's higher bandwidth compared with the microphone. Further, the method offers non-perturbing measurements with high spatial resolution, which was especially advantageous for measurements close to the transducer surfaces. The S/N ratio was higher than or in the same range as that of the two comparison methods.

Usage of noncontact human body measurements for development of Army Work Wear Trousers

NASA Astrophysics Data System (ADS)

Dabolina, Inga; Lapkovska, Eva; Vilumsone, Ausma

2017-10-01

The paper is based on issues related to imperfections of clothing fit, garment construction solutions and control measurement systems of finished products, which were identified in the research process analysing army soldier work wear trousers. The aim is to obtain target group body measurements using noncontact anthropometrical data acquisition method (3D scanning) for selection and analysis of scanned data suitable for trouser design. Tasks include comparison of scanned data with manually taken body measurements and different corresponding human body measurement standard data for establishing potential advantages of noncontact method usage in solving different trouser design issues.

Techniques for the characterization of sub-10-fs optical pulses: a comparison

NASA Astrophysics Data System (ADS)

Gallmann, L.; Sutter, D. H.; Matuschek, N.; Steinmeyer, G.; Keller, U.

Several methods have been proposed for the phase and amplitude characterization of sub-10-fs pulses with nJ energies. An overview of these techniques is presented, with a focus on the comparison of second-harmonic generation frequency-resolved optical gating (SHG-FROG) and spectral phase interferometry for direct electric-field reconstruction (SPIDER). We describe a collinear FROG variant based on type-II phase-matching that completely avoids the geometrical blurring artifact and use both this and SPIDER for the characterization of sub-10-fs Ti:sapphire laser pulses. The results of both methods are compared in an extensive statistical analysis. From this first direct experimental comparison of FROG and SPIDER, guidelines for accurate measurements of sub-10-fs pulses are derived. We point out limitations of both methods for pulses in this ultrashort pulse regime.

Sound propagation in and radiation from acoustically lined flow ducts: A comparison of experiment and theory

NASA Technical Reports Server (NTRS)

Plumblee, H. E., Jr.; Dean, P. D.; Wynne, G. A.; Burrin, R. H.

1973-01-01

The results of an experimental and theoretical study of many of the fundamental details of sound propagation in hard wall and soft wall annular flow ducts are reported. The theory of sound propagation along such ducts and the theory for determining the complex radiation impedance of higher order modes of an annulus are outlined, and methods for generating acoustic duct modes are developed. The results of a detailed measurement program on propagation in rigid wall annular ducts with and without airflow through the duct are presented. Techniques are described for measuring cut-on frequencies, modal phase speed, and radial and annular mode shapes. The effects of flow velocity on cut-on frequencies and phase speed are measured. Comparisons are made with theoretical predictions for all of the effects studies. The two microphone method of impedance is used to measure the effects of flow on acoustic liners. A numerical study of sound propagation in annular ducts with one or both walls acoustically lined is presented.

Placebo non-response measure in sequential parallel comparison design studies.

PubMed

Rybin, Denis; Doros, Gheorghe; Pencina, Michael J; Fava, Maurizio

2015-07-10

The Sequential Parallel Comparison Design (SPCD) is one of the novel approaches addressing placebo response. The analysis of SPCD data typically classifies subjects as 'placebo responders' or 'placebo non-responders'. Most current methods employed for analysis of SPCD data utilize only a part of the data collected during the trial. A repeated measures model was proposed for analysis of continuous outcomes that permitted the inclusion of information from all subjects into the treatment effect estimation. We describe here a new approach using a weighted repeated measures model that further improves the utilization of data collected during the trial, allowing the incorporation of information that is relevant to the placebo response, and dealing with the problem of possible misclassification of subjects. Our simulations show that when compared to the unweighted repeated measures model method, our approach performs as well or, under certain conditions, better, in preserving the type I error, achieving adequate power and minimizing the mean squared error. Copyright © 2015 John Wiley & Sons, Ltd.

Radius of Curvature of Off-Axis Paraboloids

NASA Technical Reports Server (NTRS)

Robinson, Brian; Reardon, Patrick; Hadaway, James; Geary, Joseph; Russell, Kevin (Technical Monitor)

2002-01-01

We present several methods for measuring the vertex radius of curvature of off-axis paraboloidal mirrors. One is based on least-squares fitting of interferometer output, one on comparison of sagittal and tangential radii of curvature, and another on measurement of displacement of the nulled test article from the ideal reference wave. Each method defines radius of curvature differently and, as a consequence, produces its own sort of errors.

Epileptic seizure prediction by non-linear methods

DOEpatents

Hively, L.M.; Clapp, N.E.; Day, C.S.; Lawkins, W.F.

1999-01-12

This research discloses methods and apparatus for automatically predicting epileptic seizures monitor and analyze brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis tools; obtaining time serial trends in the nonlinear measures; comparison of the trend to known seizure predictors; and providing notification that a seizure is forthcoming. 76 figs.

Field-scale comparison of frequency- and time-domain spectral induced polarization

NASA Astrophysics Data System (ADS)

Maurya, P. K.; Fiandaca, G.; Christiansen, A. V.; Auken, E.

2018-05-01

In this paper we present a comparison study of the time-domain (TD) and frequency-domain (FD) spectral induced polarization (IP) methods in terms of acquisition time, data quality, and spectral information retrieved from inversion. We collected TDIP and FDIP surface measurements on three profiles with identical electrode setups, at two different field sites with different lithology. In addition, TDIP data were collected in two boreholes using the El-Log drilling technique, in which apparent formation resistivity and chargeability values are measured during drilling using electrodes integrated within the stem auger.

A comparison of contour maps derived from independent methods of measuring lunar magnetic fields

NASA Technical Reports Server (NTRS)

Lichtenstein, B. R.; Coleman, P. J., Jr.; Russell, C. T.

1978-01-01

Computer-generated contour maps of strong lunar remanent magnetic fields are presented and discussed. The maps, obtained by previously described (Eliason and Soderblom, 1977) techniques, are derived from a variety of direct and indirect measurements from Apollo 15 and 16 and Explorer 35 magnetometer and electron reflection data. A common display format is used to facilitate comparison of the maps over regions of overlapping coverage. Most large scale features of either weak or strong magnetic field regions are found to correlate fairly well on all the maps considered.

ANALYTICAL METHOD COMPARISONS BY ESTIMATES OF PRECISION AND LOWER DETECTION LIMIT

EPA Science Inventory

The paper describes the use of principal component analysis to estimate the operating precision of several different analytical instruments or methods simultaneously measuring a common sample of a material whose actual value is unknown. This approach is advantageous when none of ...

An in silico method to identify computer-based protocols worthy of clinical study: An insulin infusion protocol use case

PubMed Central

Wong, Anthony F; Pielmeier, Ulrike; Haug, Peter J; Andreassen, Steen

2016-01-01

Objective Develop an efficient non-clinical method for identifying promising computer-based protocols for clinical study. An in silico comparison can provide information that informs the decision to proceed to a clinical trial. The authors compared two existing computer-based insulin infusion protocols: eProtocol-insulin from Utah, USA, and Glucosafe from Denmark. Materials and Methods The authors used eProtocol-insulin to manage intensive care unit (ICU) hyperglycemia with intravenous (IV) insulin from 2004 to 2010. Recommendations accepted by the bedside clinicians directly link the subsequent blood glucose values to eProtocol-insulin recommendations and provide a unique clinical database. The authors retrospectively compared in silico 18 984 eProtocol-insulin continuous IV insulin infusion rate recommendations from 408 ICU patients with those of Glucosafe, the candidate computer-based protocol. The subsequent blood glucose measurement value (low, on target, high) was used to identify if the insulin recommendation was too high, on target, or too low. Results Glucosafe consistently provided more favorable continuous IV insulin infusion rate recommendations than eProtocol-insulin for on target (64% of comparisons), low (80% of comparisons), or high (70% of comparisons) blood glucose. Aggregated eProtocol-insulin and Glucosafe continuous IV insulin infusion rates were clinically similar though statistically significantly different (Wilcoxon signed rank test P = .01). In contrast, when stratified by low, on target, or high subsequent blood glucose measurement, insulin infusion rates from eProtocol-insulin and Glucosafe were statistically significantly different (Wilcoxon signed rank test, P < .001), and clinically different. Discussion This in silico comparison appears to be an efficient nonclinical method for identifying promising computer-based protocols. Conclusion Preclinical in silico comparison analytical framework allows rapid and inexpensive identification of computer-based protocol care strategies that justify expensive and burdensome clinical trials. PMID:26228765

Implementation and Validation of an Impedance Eduction Technique

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Jones, Michael G.; Gerhold, Carl H.

2011-01-01

Implementation of a pressure gradient method of impedance eduction in two NASA Langley flow ducts is described. The Grazing Flow Impedance Tube only supports plane-wave sources, while the Curved Duct Test Rig supports sources that contain higher-order modes. Multiple exercises are used to validate this new impedance eduction method. First, synthesized data for a hard wall insert and a conventional liner mounted in the Grazing Flow Impedance Tube are used as input to the two impedance eduction methods, the pressure gradient method and a previously validated wall pressure method. Comparisons between the two results are excellent. Next, data measured in the Grazing Flow Impedance Tube are used as input to both methods. Results from the two methods compare quite favorably for sufficiently low Mach numbers but this comparison degrades at Mach 0.5, especially when the hard wall insert is used. Finally, data measured with a hard wall insert mounted in the Curved Duct Test Rig are used as input to the pressure gradient method. Significant deviation from the known solution is observed, which is believed to be largely due to 3-D effects in this flow duct. Potential solutions to this issue are currently being explored.

Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial, Part I: Quality Control, Comparisons, and Variability

PubMed Central

2014-01-01

Purpose. Optical coherence tomography (OCT) has been used to investigate papilledema in single-site, mostly retrospective studies. We investigated whether spectral-domain OCT (SD-OCT), which provides thickness and volume measurements of the optic nerve head and retina, could reliably demonstrate structural changes due to papilledema in a prospective multisite clinical trial setting. Methods. At entry, 126 subjects in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) with mild visual field loss had optic disc and macular scans, using the Cirrus SD-OCT. Images were analyzed by using the proprietary commercial and custom 3D-segmentation algorithms to calculate retinal nerve fiber layer (RNFL), total retinal thickness (TRT), optic nerve head volume (ONHV), and retinal ganglion cell layer (GCL) thickness. We evaluated variability, with interocular comparison and correlation between results for both methods. Results. The average RNFL thickness > 95% of normal controls in 90% of eyes and the RNFL, TRT, ONH height, and ONHV showed strong (r > 0.8) correlations for interocular comparisons. Variability for repeated testing of OCT parameters was low for both methods and intraclass correlations > 0.9 except for the proprietary GCL thickness. The proprietary algorithm–derived RNFL, TRT, and GCL thickness measurements had failure rates of 10%, 16%, and 20% for all eyes respectively, which were uncommon with 3D-segmentation–derived measurements. Only 7% of eyes had GCL thinning that was less than fifth percentile of normal age-matched control eyes by both methods. Conclusions. Spectral-domain OCT provides reliable continuous variables and quantified assessment of structural alterations due to papilledema. (ClinicalTrials.gov number, NCT01003639.) PMID:25370510

Communicating Patient Status: Comparison of Teaching Strategies in Prelicensure Nursing Education.

PubMed

Lanz, Amelia S; Wood, Felecia G

Research indicates that nurses lack adequate preparation for reporting patient status. This study compared 2 instructional methods focused on patient status reporting in the clinical setting using a randomized posttest-only comparison group design. Reporting performance using a standardized communication framework and student perceptions of satisfaction and confidence with learning were measured in a simulated event that followed the instruction. Between the instructional methods, there was no statistical difference in student reporting performance or perceptions of learning. Performance evaluations provided helpful insights for the nurse educator.

A comparison of two methods of in vivo dosimetry for a high energy neutron beam.

PubMed

Blake, S W; Bonnett, D E; Finch, J

1990-06-01

Two methods of in vivo dosimetry have been compared in a high energy neutron beam. These were activation dosimetry and thermoluminescence dosimetry (TLD). Their suitability was determined by comparison with estimates of total dose, obtained using a tissue equivalent ionization chamber. Measurements were made on the central axis and a profile of a 10 x 10 cm square field and also behind a shielding block in order to simulate conditions of clinical use. The TLD system was found to provide the best estimate of total dose.

Contaminant and other elements in soil (CCQM-K127)

NASA Astrophysics Data System (ADS)

Rocio Arvizu Torres, M.; Manzano, J. Velina Lara; Valle Moya, Edith; Horvat, Milena; Jaćimović, Radojko; Zuliani, Tea; Vreča, Polona; Acosta, Osvaldo; Bennet, John; Snell, James; Almeida, Marcelo D.; de Sena, Rodrigo C.; Dutra, Emily S.; Yang, Lu; Li, Haifeng

2017-01-01

Non-contaminated soils contain trace and major elements at levels representing geochemical background of the region. The main sources of elements as contaminants/pollutants in soils are mining and smelting activities, fossil fuel combustion, agricultural practices, industrial activities and waste disposal. Contaminated/polluted sites are of great concern and represent serious environmental, health and economic problems. Characterization and identification of contaminated land is the first step in risk assessment and remediation activities. It is well known that soil is a complex matrix with huge variation locally and worldwide. According to the IAWG's five year plan, it is recommended to have a key comparison under the measurement service category of soils and sediments for the year 2015. Currently 13 NMI has claimed calibration and measurement capabilities (CMCs) in category 13 (sediments, soils, ores, and particulates): 29 CMCs in soil and 96 CMCs in sediments. In this regard this is a follow-up comparison in the category 13; wherein three key comparisons have been carried out during the years 2000 (CCQM-K13), 2003 (CCQM-K28) and 2004 (CCQM-K44). Since it is important to update the capabilities of NMIs in this category. CENAM and JSI proposed a key comparison in this category and a pilot study in parallel. The proposed study was agreed by IAWG members, where two soils samples were used in both CCQM-K127 representing a non-contaminated soil with low contents of elements (arsenic, cadmium, iron, lead and manganese), and a contaminated soil with much higher content of selected elements (arsenic, cadmium, iron and lead). This broadens the scope and a degree of complexity of earlier measurements in this field. National metrology institutes (NMIs)/designate institutes (DIs) should, therefore, demonstrate their measurement capabilities of trace and major elements in a wide concentration ranges, representing background/reference sites as well as highly contaminated soils by their available analytical methods. This facilitated the investigation into the core capabilities of participants to measure the mass fraction of tested elements in soil and therefore to claim their CMCs as listed in appendix C of the key comparison database (KCDB) under the mutual recognition arrangement of the International Committee for Weights and Measures (CIPM MRA). In total 19 institutes (NMIs/Dis) participated in the key comparison and the reported results of the key comparison were from 18 institutes (NMIs/DIs); 151 measurements were reported for CCQM-K127. The analytical techniques selected by the participant institutes were ICP-MS, ICP-OES, FAAS, ET-AAS and INAA (k0-method of INAA); the sample preparation methods used were based on microwave assisted digestion, except when it was used INAA. After discussions it agreed to use the median as KCRV and the MMADe as u(xKCRV). Generally most of the results of the participants were found to be consistent for all measurements according to their equivalence statements, with the exception of some extreme values, which were identified with a value of di/U(di) higher than 1. This key comparison is a means of providing evidence for practical demonstration of a CCQM comparison calibration and measurement capabilities (CMCs) claims for contaminant and others elements, in low and medium content levels in non-contaminated and contaminated matrices described in category 13. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Measuring the volume of uterine fibroids using 2- and 3-dimensional ultrasound and comparison with histopathology.

PubMed

Zivković, Nikica; Zivković, Kreiimir; Despot, Albert; Paić, Josip; Zelić, Ana

2012-12-01

The aim of this study was clinical testing of the reliability and usability of three-dimensional (3D) and two-dimensional (2D) ultrasound (US) technology. The ultimate aim and purpose of this study was to establish ultrasound methods, standards and protocols for determining the volume of any gynecologic organ or tumor. The study included 31 women in reproductive age and postmenopause. All patients were examined with a RIC 5-9 3D-endovaginal probe (4.3-7.5 MHz) on a Voluson 730 Pro ultrasound device. The volume of myomas was measured by using the existing 2D and 3D ultrasound methods on the above mentioned device. All patients underwent myomectomy or hysterectomy due to clinically and ultrasonographically diagnosed uterine myomas indicating operative intervention. After the operation, the pathologist determined the volume of removed myomas by measuring them in a gauge bowl containing water, i.e. using Archimedes' principle (lift), serving as the control group with histopathologic diagnosis. A total of 155 myoma volumes were processed on 2D display, 31 myoma volumes were preoperatively measured on 3D display and 31 myoma volumes were measured by the pathologist. The values of US measurements for each US method were expressed as mean value of all measurements of myoma volumes. Statistical processing of the results and Student's t-test for independent samples revealed that the 2nd examined US method (measuring of myoma by using an ellipse and the longer tumor diameter) and 4th examined US method (measuring of myoma by using the longer and shorter tumor diameters together with establishing their mean values) in 2D US technique, as well as the 6th examined US method in 3D US technique showed no significant measurement differences in comparison with control measurement in a gauge bowl containing water (p < 0.05), indicating acceptability of the US methods for verifying tumor volumes. The standard error in determining the volume of myomas by the above US methods varied between 15% and 25%, so it is concluded that these three methods can be used in clinical practice to determine tumor volumes, in this case uterine myomas. The 3D MultiPlane method proved to be the most reliable method of determining the volume of uterine myomas.

Assessing Lower Limb Alignment: Comparison of Standard Knee Xray vs Long Leg View

PubMed Central

Zampogna, Biagio; Vasta, Sebastiano; Amendola, Annunziato; Uribe-Echevarria Marbach, Bastian; Gao, Yubo; Papalia, Rocco; Denaro, Vincenzo

2015-01-01

Background High tibial osteotomy (HTO) is a well-established and commonly utilized technique in medial knee osteoarthritis secondary to varus malalignment. Accurate measurement of the preoperative limb alignment, and the amount of correction required are essential when planning limb realignment surgery. The hip-knee-ankle angle (HKA) measured on a full length weightbearing (FLWB) X-ray in the standing position is considered the gold standard, since it allows for reliable and accurate measurement of the mechanical axis of the whole lower extremity. In general practice, alignment is often evaluated on standard anteroposterior weightbearing (APWB) X-rays, as the angle between the femur and tibial anatomic axis (TFa). It is, therefore, of value to establish if measuring the anatomical axis from limited APWB is an effective measure of knee alignment especially in patients undergoing osteotomy about the knee. Methods Three independent observers measured preoperative and postoperative FTa with standard method (FTa1) and with circles method (FTa2) on APWB X-ray and the HKA on FLWB X-ray at three different time-points separated by a two-week period. Intra-observer and inter-observer reliabilities and the comparison and relationship between anatomical and mechanical alignment were calculated. Results Intra- and interclass coefficients for all the three methods indicated excellent reliability, having all the values above 0.80. Using the mean of paired t-student test, the comparison of HKA versus TFa1 and TFa2 showed a statistically significant difference (p<.0001) both for the pre-operative and post-operative sets of values. The correlation between the HKA and FTal was found poor for the preoperative set (R=0.26) and fair for the postoperative one (R=0.53), while the new circles method showed a higher correlation in both the preoperative (R=0.71) and postoperative sets (R=0.79). Conclusions Intra-observer reliability was high for HKA, FTal and FTa2 on APWB x-rays in the pre- and post-operative setting. Inter-rater reliability was higher for HKA and TFa2 compared to FTal. The femoro-tibial angle as measured on APWB with the traditional method (FTal) has a weak correlation with the HKA, and based on these findings, should not be used in everyday practice. The FTa2 showed better correlation with the HKA, although not excellent Level of Evidence Level III, Retrospective study. PMID:26361444

A randomized trial to identify accurate and cost-effective fidelity measurement methods for cognitive-behavioral therapy: project FACTS study protocol.

PubMed

Beidas, Rinad S; Maclean, Johanna Catherine; Fishman, Jessica; Dorsey, Shannon; Schoenwald, Sonja K; Mandell, David S; Shea, Judy A; McLeod, Bryce D; French, Michael T; Hogue, Aaron; Adams, Danielle R; Lieberman, Adina; Becker-Haimes, Emily M; Marcus, Steven C

2016-09-15

This randomized trial will compare three methods of assessing fidelity to cognitive-behavioral therapy (CBT) for youth to identify the most accurate and cost-effective method. The three methods include self-report (i.e., therapist completes a self-report measure on the CBT interventions used in session while circumventing some of the typical barriers to self-report), chart-stimulated recall (i.e., therapist reports on the CBT interventions used in session via an interview with a trained rater, and with the chart to assist him/her) and behavioral rehearsal (i.e., therapist demonstrates the CBT interventions used in session via a role-play with a trained rater). Direct observation will be used as the gold-standard comparison for each of the three methods. This trial will recruit 135 therapists in approximately 12 community agencies in the City of Philadelphia. Therapists will be randomized to one of the three conditions. Each therapist will provide data from three unique sessions, for a total of 405 sessions. All sessions will be audio-recorded and coded using the Therapy Process Observational Coding System for Child Psychotherapy-Revised Strategies scale. This will enable comparison of each measurement approach to direct observation of therapist session behavior to determine which most accurately assesses fidelity. Cost data associated with each method will be gathered. To gather stakeholder perspectives of each measurement method, we will use purposive sampling to recruit 12 therapists from each condition (total of 36 therapists) and 12 supervisors to participate in semi-structured qualitative interviews. Results will provide needed information on how to accurately and cost-effectively measure therapist fidelity to CBT for youth, as well as important information about stakeholder perspectives with regard to each measurement method. Findings will inform fidelity measurement practices in future implementation studies as well as in clinical practice. NCT02820623 , June 3rd, 2016.

Ares I-X Launch Abort System, Crew Module, and Upper Stage Simulator Vibroacoustic Flight Data Evaluation, Comparison to Predictions, and Recommendations for Adjustments to Prediction Methodology and Assumptions

NASA Technical Reports Server (NTRS)

Smith, Andrew; Harrison, Phil

2010-01-01

The National Aeronautics and Space Administration (NASA) Constellation Program (CxP) has identified a series of tests to provide insight into the design and development of the Crew Launch Vehicle (CLV) and Crew Exploration Vehicle (CEV). Ares I-X was selected as the first suborbital development flight test to help meet CxP objectives. The Ares I-X flight test vehicle (FTV) is an early operational model of CLV, with specific emphasis on CLV and ground operation characteristics necessary to meet Ares I-X flight test objectives. The in-flight part of the test includes a trajectory to simulate maximum dynamic pressure during flight and perform a stage separation of the Upper Stage Simulator (USS) from the First Stage (FS). The in-flight test also includes recovery of the FS. The random vibration response from the ARES 1-X flight will be reconstructed for a few specific locations that were instrumented with accelerometers. This recorded data will be helpful in validating and refining vibration prediction tools and methodology. Measured vibroacoustic environments associated with lift off and ascent phases of the Ares I-X mission will be compared with pre-flight vibration predictions. The measured flight data was given as time histories which will be converted into power spectral density plots for comparison with the maximum predicted environments. The maximum predicted environments are documented in the Vibroacoustics and Shock Environment Data Book, AI1-SYS-ACOv4.10 Vibration predictions made using statistical energy analysis (SEA) VAOne computer program will also be incorporated in the comparisons. Ascent and lift off measured acoustics will also be compared to predictions to assess whether any discrepancies between the predicted vibration levels and measured vibration levels are attributable to inaccurate acoustic predictions. These comparisons will also be helpful in assessing whether adjustments to prediction methodologies are needed to improve agreement between the predicted and measured flight data. Future assessment will incorporate hybrid methods in VAOne analysis (i.e., boundary element methods, BEM and finite element methods, FEM). These hybrid methods will enable the ability to import NASTRAN models providing much more detailed modeling of the underlying beams and support structure of the ARES 1-X test vehicle. Measured acoustic data will be incorporated into these analyses to improve correlation for additional post flight analysis.

Cross Calibration of TOMS, SBUV/2 and Sciamachy Radiances from Ground Observations

NASA Technical Reports Server (NTRS)

Hillsenrath, Ernest; Ahmad, Ziauddin; Bhartia, Pawan K. (Technical Monitor)

2001-01-01

Verification of a stratospheric ozone recovery remains a high priority for environmental research and policy definition. Models predict an ozone recovery at a much lower rate than the measured depletion rate observed to date. Therefore improved precision of the satellite and ground ozone observing systems are required over the long term to verify recovery. We have shown that validation of radiances is the most effective means for correcting absolute accuracy and long term drifts of backscatter type satellite measurements. This method by-passes the algorithms used for both satellite and ground based measurements which are normally used to validate and correct the satellite data. Validation of radiances will also improve all higher level data products derived from the satellite observations. Backscatter algorithms suffer from several errors such as unrepresentative a-priori data and air mass factor corrections. Radiance comparisons employ forward models but are inherently more accurate and than inverse (retrieval) algorithms. A new method for satellite validation is planned which will compliment measurements from the existing ground-based networks. This method will employ very accurate comparisons between ground based zenith sky radiances and satellite nadir radiances. These comparisons will rely heavily on the experience derived from the Shuttle SBUV (SSBUV) program which provided a reference standard of radiance measurements for SBUV/2, TOMS, and GOME. This new measurement program, called "Skyrad", employs two well established capabilities at the Goddard Space Flight Center, 1) the SSBUV calibration facilities and 2) the radiative transfer codes used for the TOMS and SBUV/2 algorithms and their subsequent refinements. Radiative transfer calculations show that ground based zenith sky and satellite nadir backscatter ultraviolet comparisons can be made very accurately under certain viewing conditions. The Skyrad instruments (SSBUV, Brewer spectrophotometers, and possibly others) will be calibrated and maintained to a precision of a few tenths of a percent. Skyrad data will then enable long term calibration of upcoming satellite instruments such as QuickTOMS. SBUV/2s and SCIAMACHY with a high degree of precision. This technique can be further employed to monitor the performance of future instruments such as GOME-2, OMI, and OMPS. Initial ground observations taken from Goddard Space Flight Center compared with radiative transfer calculations has indicated the feasibility of this method.

Comparison of individual-based model output to data using a model of walleye pollock early life history in the Gulf of Alaska

NASA Astrophysics Data System (ADS)

Hinckley, Sarah; Parada, Carolina; Horne, John K.; Mazur, Michael; Woillez, Mathieu

2016-10-01

Biophysical individual-based models (IBMs) have been used to study aspects of early life history of marine fishes such as recruitment, connectivity of spawning and nursery areas, and marine reserve design. However, there is no consistent approach to validating the spatial outputs of these models. In this study, we hope to rectify this gap. We document additions to an existing individual-based biophysical model for Alaska walleye pollock (Gadus chalcogrammus), some simulations made with this model and methods that were used to describe and compare spatial output of the model versus field data derived from ichthyoplankton surveys in the Gulf of Alaska. We used visual methods (e.g. distributional centroids with directional ellipses), several indices (such as a Normalized Difference Index (NDI), and an Overlap Coefficient (OC), and several statistical methods: the Syrjala method, the Getis-Ord Gi* statistic, and a geostatistical method for comparing spatial indices. We assess the utility of these different methods in analyzing spatial output and comparing model output to data, and give recommendations for their appropriate use. Visual methods are useful for initial comparisons of model and data distributions. Metrics such as the NDI and OC give useful measures of co-location and overlap, but care must be taken in discretizing the fields into bins. The Getis-Ord Gi* statistic is useful to determine the patchiness of the fields. The Syrjala method is an easily implemented statistical measure of the difference between the fields, but does not give information on the details of the distributions. Finally, the geostatistical comparison of spatial indices gives good information of details of the distributions and whether they differ significantly between the model and the data. We conclude that each technique gives quite different information about the model-data distribution comparison, and that some are easy to apply and some more complex. We also give recommendations for a multistep process to validate spatial output from IBMs.

Assessment of cardiac fibrosis: a morphometric method comparison for collagen quantification.

PubMed

Schipke, Julia; Brandenberger, Christina; Rajces, Alexandra; Manninger, Martin; Alogna, Alessio; Post, Heiner; Mühlfeld, Christian

2017-04-01

Fibrotic remodeling of the heart is a frequent condition linked to various diseases and cardiac dysfunction. Collagen quantification is an important objective in cardiac fibrosis research; however, a variety of different histological methods are currently used that may differ in accuracy. Here, frequently applied collagen quantification techniques were compared. A porcine model of early stage heart failure with preserved ejection fraction was used as an example. Semiautomated threshold analyses were imprecise, mainly due to inclusion of noncollagen structures or failure to detect certain collagen deposits. In contrast, collagen assessment by automated image analysis and light microscopy (LM)-stereology was more sensitive. Depending on the quantification method, the amount of estimated collagen varied and influenced intergroup comparisons. PicroSirius Red, Masson's trichrome, and Azan staining protocols yielded similar results, whereas the measured collagen area increased with increasing section thickness. Whereas none of the LM-based methods showed significant differences between the groups, electron microscopy (EM)-stereology revealed a significant collagen increase between cardiomyocytes in the experimental group, but not at other localizations. In conclusion, in contrast to the staining protocol, section thickness and the quantification method being used directly influence the estimated collagen content and thus, possibly, intergroup comparisons. EM in combination with stereology is a precise and sensitive method for collagen quantification if certain prerequisites are considered. For subtle fibrotic alterations, consideration of collagen localization may be necessary. Among LM methods, LM-stereology and automated image analysis are appropriate to quantify fibrotic changes, the latter depending on careful control of algorithm and comparable section staining. NEW & NOTEWORTHY Direct comparison of frequently applied histological fibrosis assessment techniques revealed a distinct relation of measured collagen and utilized quantification method as well as section thickness. Besides electron microscopy-stereology, which was precise and sensitive, light microscopy-stereology and automated image analysis proved to be appropriate for collagen quantification. Moreover, consideration of collagen localization might be important in revealing minor fibrotic changes. Copyright © 2017 the American Physiological Society.

Tongue Measures in Individuals with Normal and Impaired Swallowing

ERIC Educational Resources Information Center

Stierwalt, Julie A. G.; Youmans, Scott R.

2007-01-01

Purpose: This investigation sought to add to the extant literature on measures of normal tongue function, to provide information on measures of tongue function in a group of individuals with oral phase dysphagia, and to provide a comparison of these 2 groups matched for age and gender. Method: The Iowa Oral Performance Instrument was utilized to…

Standardization of Tc-99 by two methods and participation at the CCRI(II)-K2. Tc-99 comparison.

PubMed

Sahagia, M; Antohe, A; Ioan, R; Luca, A; Ivan, C

2014-05-01

The work accomplished within the participation at the 2012 key comparison of Tc-99 is presented. The solution was standardized for the first time in IFIN-HH by two methods: LSC-TDCR and 4π(PC)β-γ efficiency tracer. The methods are described and the results are compared. For the LSC-TDCR method, the program TDCR07c, written and provided by P. Cassette, was used for processing the measurement data. The results are 2.1% higher than when applying the TDCR06b program; the higher value, calculated with the software TDCR07c, was used for reporting the final result in the comparison. The tracer used for the 4π(PC)β-γ efficiency tracer method was a standard (60)Co solution. The sources were prepared from the mixture (60)Co+(99)Tc solution and a general extrapolation curve, type: N(βTc-99)/(M)(Tc-99)=f [1-ε(Co-60)], was drawn. This value was not used for the final result of the comparison. The difference between the values of activity concentration obtained by the two methods was within the limit of the combined standard uncertainty of the difference of these two results. © 2013 Published by Elsevier Ltd.

How to compare movement? A review of physical movement similarity measures in geographic information science and beyond.

PubMed

Ranacher, Peter; Tzavella, Katerina

2014-05-27

In geographic information science, a plethora of different approaches and methods is used to assess the similarity of movement. Some of these approaches term two moving objects similar if they share akin paths. Others require objects to move at similar speed and yet others consider movement similar if it occurs at the same time. We believe that a structured and comprehensive classification of movement comparison measures is missing. We argue that such a classification not only depicts the status quo of qualitative and quantitative movement analysis, but also allows for identifying those aspects of movement for which similarity measures are scarce or entirely missing. In this review paper we, first, decompose movement into its spatial, temporal, and spatiotemporal movement parameters. A movement parameter is a physical quantity of movement, such as speed, spatial path, or temporal duration. For each of these parameters we then review qualitative and quantitative methods of how to compare movement. Thus, we provide a systematic and comprehensive classification of different movement similarity measures used in geographic information science. This classification is a valuable first step toward a GIS toolbox comprising all relevant movement comparison methods.

How to compare movement? A review of physical movement similarity measures in geographic information science and beyond

PubMed Central

Ranacher, Peter; Tzavella, Katerina

2014-01-01

In geographic information science, a plethora of different approaches and methods is used to assess the similarity of movement. Some of these approaches term two moving objects similar if they share akin paths. Others require objects to move at similar speed and yet others consider movement similar if it occurs at the same time. We believe that a structured and comprehensive classification of movement comparison measures is missing. We argue that such a classification not only depicts the status quo of qualitative and quantitative movement analysis, but also allows for identifying those aspects of movement for which similarity measures are scarce or entirely missing. In this review paper we, first, decompose movement into its spatial, temporal, and spatiotemporal movement parameters. A movement parameter is a physical quantity of movement, such as speed, spatial path, or temporal duration. For each of these parameters we then review qualitative and quantitative methods of how to compare movement. Thus, we provide a systematic and comprehensive classification of different movement similarity measures used in geographic information science. This classification is a valuable first step toward a GIS toolbox comprising all relevant movement comparison methods. PMID:27019646

Technique for active measurement of atmospheric transmittance using an imaging system: implementation at 10.6-μm wavelength

NASA Astrophysics Data System (ADS)

Sadot, Dan; Zaarur, O.; Zaarur, S.; Kopeika, Norman S.

1994-10-01

An active method is presented for measuring atmospheric transmittance with an imaging system. In comparison to other measurement methods, this method has the advantage of immunity to background noise, independence of atmospheric conditions such as solar radiation, and an improved capability to evaluate effects of turbulence on the measurements. Other significant advantages are integration over all particulate size distribution effects including very small and very large particulates whose concentration is hard to measure, and the fact that this method is a path-integrated measurement. In this implementation attenuation deriving from molecular absorption and from small and large particulate scatter and absorption and their weather dependences are separated out. Preliminary results indicate high correlation with direct transmittance calculations via particle size distribution measurement, and that even at 10.6 micrometers wavelength atmospheric transmission depends noticeably on aerosol size distribution and concentration.

A technique for active measurement of atmospheric transmittance using an imaging system: implementation at 10.6 μm wavelength

NASA Astrophysics Data System (ADS)

Sadot, D.; Zaarur, O.; Zaarur, S.

1995-12-01

An active method is presented for measuring atmospheric transmittance with an imaging system. In comparison to other measurement methods, this method has the advantage of immunity to background noise, independence of atmospheric conditions such as solar radiation, and an improved capability to evaluate effects of turbulence on the measurements. Other significant advantages are integration over all particulate size distribution effects including very small and very large particulates whose concentration is hard to measure, and the fact that this method is a path-integrated measurement. Attenuation deriving from molecular absorption and from small and large particulate scatter and absorption and their weather dependences are separated out. Preliminary results indicate high correlation with direct transmittance calculations via particle size distribution measurement, and that even at 10.6 μm wavelength atmospheric transmission depends noticeably on aerosol size distribution and concentration.

From comparison to classification: a cortical tool for boosting perception.

PubMed

Nahum, Mor; Daikhin, Luba; Lubin, Yedida; Cohen, Yamit; Ahissar, Merav

2010-01-20

Humans are much better in relative than in absolute judgments. This common assertion is based on findings that discrimination thresholds are much lower when measured with methods that allow interstimuli comparisons than when measured with methods that require classification of one stimulus at a time and are hence sensitive to memory load. We now challenged this notion by measuring discrimination thresholds and evoked potentials while listeners performed a two-tone frequency discrimination task. We tested various protocols that differed in the pattern of cross-trial tone repetition. We found that best performance was achieved only when listeners effectively used cross-trial repetition to avoid interstimulus comparisons with the repeated reference tone. Instead, they classified one tone, the nonreference tone, as either high or low by comparing it with a recently formed internal reference. Listeners were not aware of the switch from interstimulus comparison to classification. Its successful use was revealed by the conjunction of improved behavioral performance and an event-related potential component (P3), indicating an implicit perceptual decision, which followed the nonreference tone in each trial. Interestingly, tone repetition itself did not suffice for the switch, implying that the bottleneck to discrimination does not reside at the lower, sensory stage. Rather, the temporal consistency of repetition was important, suggesting the involvement of higher-level mechanisms with longer time constants. These findings suggest that classification is based on more automatic and accurate mechanisms than interstimulus comparisons and that the ability to effectively use them depends on a dynamic interplay between higher- and lower-level cortical mechanisms.

Arima model and exponential smoothing method: A comparison

NASA Astrophysics Data System (ADS)

Wan Ahmad, Wan Kamarul Ariffin; Ahmad, Sabri

2013-04-01

This study shows the comparison between Autoregressive Moving Average (ARIMA) model and Exponential Smoothing Method in making a prediction. The comparison is focused on the ability of both methods in making the forecasts with the different number of data sources and the different length of forecasting period. For this purpose, the data from The Price of Crude Palm Oil (RM/tonne), Exchange Rates of Ringgit Malaysia (RM) in comparison to Great Britain Pound (GBP) and also The Price of SMR 20 Rubber Type (cents/kg) with three different time series are used in the comparison process. Then, forecasting accuracy of each model is measured by examinethe prediction error that producedby using Mean Squared Error (MSE), Mean Absolute Percentage Error (MAPE), and Mean Absolute deviation (MAD). The study shows that the ARIMA model can produce a better prediction for the long-term forecasting with limited data sources, butcannot produce a better prediction for time series with a narrow range of one point to another as in the time series for Exchange Rates. On the contrary, Exponential Smoothing Method can produce a better forecasting for Exchange Rates that has a narrow range of one point to another for its time series, while itcannot produce a better prediction for a longer forecasting period.

Comparison of automated volumetry of the hippocampus using NeuroQuant® and visual assessment of the medial temporal lobe in Alzheimer's disease.

PubMed

Persson, Karin; Barca, Maria Lage; Cavallin, Lena; Brækhus, Anne; Knapskog, Anne-Brita; Selbæk, Geir; Engedal, Knut

2017-01-01

Background Different clinically feasible methods for evaluation of medial temporal lobe atrophy exists and are useful in diagnostic work-up of Alzheimer's disease (AD). Purpose To compare the diagnostic properties of two clinically available magnetic resonance imaging (MRI)-based methods-an automated volumetric software, NeuroQuant® (NQ) (evaluation of hippocampus volume) and the Scheltens scale (visual evaluation of medial temporal lobe atrophy [MTA])-in patients with AD dementia, and subjective and mild cognitive impairment (non-dementia). Material and Methods MRIs from 56 patients (31 AD, 25 non-dementia) were assessed with both methods. Correlations between the methods were calculated and receiver operating curve (ROC) analyses that yield area under the curve (AUC) statistics were conducted. Results High correlations were found between the two MRI assessments for the total hippocampal volume measured with NQ and mean MTA score (-0.753, P < 0.001), for the right (-0.767, P < 0.001), and for the left (-0.675, P < 0.001) sides. The NQ total measure yielded somewhat higher AUC (0.88, "good") compared to the MTA mean measure (0.80, "good") in the comparison of patients with AD and non-dementia, but the accuracy was in favor of the MTA scale. Conclusion The two methods correlated highly and both methods reached equally "good" power.

Comparison of the dye method with the thermocouple psychrometer for measuring leaf water potentials.

PubMed

Knipling, E B; Kramer, P J

1967-10-01

The dye method for measuring water potential was examined and compared with the thermocouple psychrometer method in order to evaluate its usefulness for measuring leaf water potentials of forest trees and common laboratory plants. Psychrometer measurements are assumed to represent the true leaf water potentials. Because of the contamination of test solutions by cell sap and leaf surface residues, dye method values of most species varied about 1 to 5 bars from psychrometer values over the leaf water potential range of 0 to -30 bars. The dye method is useful for measuring changes and relative values in leaf potential. Because of species differences in the relationships of dye method values to true leaf water potentials, dye method values should be interpreted with caution when comparing different species or the same species growing in widely different environments. Despite its limitations the dye method has a usefulness to many workers because it is simple, requires no elaborate equipment, and can be used in both the laboratory and field.

How to Quantify Penile Corpus Cavernosum Structures with Histomorphometry: Comparison of Two Methods

PubMed Central

Felix-Patrício, Bruno; De Souza, Diogo Benchimol; Gregório, Bianca Martins; Costa, Waldemar Silva; Sampaio, Francisco José

2015-01-01

The use of morphometrical tools in biomedical research permits the accurate comparison of specimens subjected to different conditions, and the surface density of structures is commonly used for this purpose. The traditional point-counting method is reliable but time-consuming, with computer-aided methods being proposed as an alternative. The aim of this study was to compare the surface density data of penile corpus cavernosum trabecular smooth muscle in different groups of rats, measured by two observers using the point-counting or color-based segmentation method. Ten normotensive and 10 hypertensive male rats were used in this study. Rat penises were processed to obtain smooth muscle immunostained histological slices and photomicrographs captured for analysis. The smooth muscle surface density was measured in both groups by two different observers by the point-counting method and by the color-based segmentation method. Hypertensive rats showed an increase in smooth muscle surface density by the two methods, and no difference was found between the results of the two observers. However, surface density values were higher by the point-counting method. The use of either method did not influence the final interpretation of the results, and both proved to have adequate reproducibility. However, as differences were found between the two methods, results obtained by either method should not be compared. PMID:26413547

How to Quantify Penile Corpus Cavernosum Structures with Histomorphometry: Comparison of Two Methods.

PubMed

Felix-Patrício, Bruno; De Souza, Diogo Benchimol; Gregório, Bianca Martins; Costa, Waldemar Silva; Sampaio, Francisco José

2015-01-01

The use of morphometrical tools in biomedical research permits the accurate comparison of specimens subjected to different conditions, and the surface density of structures is commonly used for this purpose. The traditional point-counting method is reliable but time-consuming, with computer-aided methods being proposed as an alternative. The aim of this study was to compare the surface density data of penile corpus cavernosum trabecular smooth muscle in different groups of rats, measured by two observers using the point-counting or color-based segmentation method. Ten normotensive and 10 hypertensive male rats were used in this study. Rat penises were processed to obtain smooth muscle immunostained histological slices and photomicrographs captured for analysis. The smooth muscle surface density was measured in both groups by two different observers by the point-counting method and by the color-based segmentation method. Hypertensive rats showed an increase in smooth muscle surface density by the two methods, and no difference was found between the results of the two observers. However, surface density values were higher by the point-counting method. The use of either method did not influence the final interpretation of the results, and both proved to have adequate reproducibility. However, as differences were found between the two methods, results obtained by either method should not be compared.

Comparison of Fourier transform infrared spectrometry and 2,4-dinitrophenylhydrazine impinger techniques for the measurement of formaldehyde in vehicle exhaust

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haack, L.P.; LaCourse, D.L.; Korniski, T.J.

1986-01-01

Experiments were conducted to validate a Fourier transform infrared (FT-IR) sampling and analysis system for measurement of trace gases in vehicle exhaust utilizing gasoline-, gasohol-, diesel-, and methanol-fueled vehicles as the emission source and formaldehyde (HCHO) as the test molecule. The 2,4-dinitrophenylhydrazine impinger method was chosen as the reference method. Diluted exhaust was drawn continuously though the FT-IR cell and measured every 3 s. The FT-IR signals were averaged over a complete driving-test cycle and compared to the concentration determined from concurrent impinger sampling. By impinger measurements it was shown that HCHO losses between the tailpipe and the FT-IR cellmore » were on the order of only 5%, independent of vehicle type or HCHO concentration (0.02-8.5 ppm). Comparisons between FT-IR and impinger measurements on 43 tests of methanol-fueled vehicles under transient conditions (diluted-exhaust HCHO 0.28-8.5 ppm) showed FT-IR/impinger = 1.055 +/- 0.095. 19 references, 5 figures, 5 tables.« less

Comparison of VOC measurements made by PTR-MS, adsorbent tubes-GC-FID-MS and DNPH derivatization-HPLC during the Sydney Particle Study, 2012: a contribution to the assessment of uncertainty in routine atmospheric VOC measurements

NASA Astrophysics Data System (ADS)

Dunne, Erin; Galbally, Ian E.; Cheng, Min; Selleck, Paul; Molloy, Suzie B.; Lawson, Sarah J.

2018-01-01

Understanding uncertainty is essential for utilizing atmospheric volatile organic compound (VOC) measurements in robust ways to develop atmospheric science. This study describes an inter-comparison of the VOC data, and the derived uncertainty estimates, measured with three independent techniques (PTR-MS, proton-transfer-reaction mass spectrometry; GC-FID-MS, gas chromatography with flame-ionization and mass spectrometric detection; and DNPH-HPLC, 2,4-dinitrophenylhydrazine derivatization followed by analysis by high-performance liquid chromatography) during routine monitoring as part of the Sydney Particle Study (SPS) campaign in 2012. Benzene, toluene, C8 aromatics, isoprene, formaldehyde and acetaldehyde were selected for the comparison, based on objective selection criteria from the available data. Bottom-up uncertainty analyses were undertaken for each compound and each measurement system. Top-down uncertainties were quantified via the inter-comparisons. In all seven comparisons, the correlations between independent measurement techniques were high with R2 values with a median of 0.92 (range 0.75-0.98) and small root mean square of the deviations (RMSD) of the observations from the regression line with a median of 0.11 (range 0.04-0.23 ppbv). These results give a high degree of confidence that for each comparison the response of the two independent techniques is dominated by the same constituents. The slope and intercept as determined by reduced major axis (RMA) regression gives a different story. The slopes varied considerably with a median of 1.25 and a range of 1.16-2.01. The intercepts varied with a median of 0.04 and a range of -0.03 to 0.31 ppbv. An ideal comparison would give a slope of 1.00 and an intercept of 0. Some sources of uncertainty that are poorly quantified by the bottom-up uncertainty analysis method were identified, including: contributions of non-target compounds to the measurement of the target compound for benzene, toluene and isoprene by PTR-MS as well as the under-reporting of formaldehyde, acetaldehyde and acetone by the DNPH technique. As well as these, this study has identified a specific interference of liquid water with acetone measurements by the DNPH technique. These relationships reported for Sydney 2012 were incorporated into a larger analysis with 61 similar published inter-comparison studies for the same compounds. Overall, for the light aromatics, isoprene and the C1-C3 carbonyls, the uncertainty in a set of measurements varies by a factor of between 1.5 and 2. These uncertainties ( ˜ 50 %) are significantly higher than uncertainties estimated using standard propagation of error methods, which in this case were ˜ 22 % or less, and are the result of the presence of poorly understood or neglected processes that affect the measurement and its uncertainty. The uncertainties in VOC measurements identified here should be considered when assessing the reliability of VOC measurements from routine monitoring with individual, stand-alone instruments; when utilizing VOC data to constrain and inform air quality and climate models; when using VOC observations for human exposure studies; and for comparison with satellite retrievals.

An Experimental Comparison of Similarity Assessment Measures for 3D Models on Constrained Surface Deformation

NASA Astrophysics Data System (ADS)

Quan, Lulin; Yang, Zhixin

2010-05-01

To address the issues in the area of design customization, this paper expressed the specification and application of the constrained surface deformation, and reported the experimental performance comparison of three prevail effective similarity assessment algorithms on constrained surface deformation domain. Constrained surface deformation becomes a promising method that supports for various downstream applications of customized design. Similarity assessment is regarded as the key technology for inspecting the success of new design via measuring the difference level between the deformed new design and the initial sample model, and indicating whether the difference level is within the limitation. According to our theoretical analysis and pre-experiments, three similarity assessment algorithms are suitable for this domain, including shape histogram based method, skeleton based method, and U system moment based method. We analyze their basic functions and implementation methodologies in detail, and do a series of experiments on various situations to test their accuracy and efficiency using precision-recall diagram. Shoe model is chosen as an industrial example for the experiments. It shows that shape histogram based method gained an optimal performance in comparison. Based on the result, we proposed a novel approach that integrating surface constrains and shape histogram description with adaptive weighting method, which emphasize the role of constrains during the assessment. The limited initial experimental result demonstrated that our algorithm outperforms other three algorithms. A clear direction for future development is also drawn at the end of the paper.

COMPARISON OF FIVE EXTRACTION METHODS FOR DETERMINING INCURRED AND FORTIFIED PESTICIDES IN DIETARY COMPOSITES

EPA Science Inventory

U.S. EPA's National Exposure Research Laboratory conducts research to measure exposure of individuals to chemical pollutants through the diet. In support of this research, methods are being evaluated for determination of pesticides in dietary composite samples. In the present s...

Critical evaluations of vegetation cover measurement techniques: a response to Thacker et al. (2015)

USDA-ARS?s Scientific Manuscript database

Comparison studies are necessary to reconcile methods that have arisen among disparate rangeland monitoring programs. However, Thacker et al.'s study comparing Daubenmire frame (DF) and line-point intercept (LPI) methods for estimating vegetation cover ignores definitional differences between what t...

A Profilometry-Based Dentifrice Abrasion Method for V8 Brushing Machines Part II: Comparison of RDA-PE and Radiotracer RDA Measures.

PubMed

Schneiderman, Eva; Colón, Ellen; White, Donald J; St John, Samuel

2015-01-01

The purpose of this study was to compare the abrasivity of commercial dentifrices by two techniques: the conventional gold standard radiotracer-based Radioactive Dentin Abrasivity (RDA) method; and a newly validated technique based on V8 brushing that included a profilometry-based evaluation of dentin wear. This profilometry-based method is referred to as RDA-Profilometry Equivalent, or RDA-PE. A total of 36 dentifrices were sourced from four global dentifrice markets (Asia Pacific [including China], Europe, Latin America, and North America) and tested blindly using both the standard radiotracer (RDA) method and the new profilometry method (RDA-PE), taking care to follow specific details related to specimen preparation and treatment. Commercial dentifrices tested exhibited a wide range of abrasivity, with virtually all falling well under the industry accepted upper limit of 250; that is, 2.5 times the level of abrasion measured using an ISO 11609 abrasivity reference calcium pyrophosphate as the reference control. RDA and RDA-PE comparisons were linear across the entire range of abrasivity (r2 = 0.7102) and both measures exhibited similar reproducibility with replicate assessments. RDA-PE assessments were not just linearly correlated, but were also proportional to conventional RDA measures. The linearity and proportionality of the results of the current study support that both methods (RDA or RDA-PE) provide similar results and justify a rationale for making the upper abrasivity limit of 250 apply to both RDA and RDA-PE.

Comparison of the various methods for the direct calculation of the transmission functions of the 15-micron CO2 band with experimental data

NASA Technical Reports Server (NTRS)

1978-01-01

Various methods for calculating the transmission functions of the 15 micron CO2 band are described. The results of these methods are compared with laboratory measurements. It is found that program P4 provides the best agreement with experimental results on the average.

A Comparison of Affect Ratings Obtained with Ecological Momentary Assessment and the Day Reconstruction Method

ERIC Educational Resources Information Center

Dockray, Samantha; Grant, Nina; Stone, Arthur A.; Kahneman, Daniel; Wardle, Jane; Steptoe, Andrew

2010-01-01

Measurement of affective states in everyday life is of fundamental importance in many types of quality of life, health, and psychological research. Ecological momentary assessment (EMA) is the recognized method of choice, but the respondent burden can be high. The day reconstruction method (DRM) was developed by Kahneman and colleagues ("Science,"…

Calculation of Mitral Valve Area in Mitral Stenosis: Comparison of Continuity Equation and Pressure Half Time With Two-Dimensional Planimetry in Patients With and Without Associated Aortic or Mitral Regurgitation or Atrial Fibrillation.

PubMed

Sattarzadeh, Roya; Tavoosi, Anahita; Saadat, Mohammad; Derakhshan, Leila; Khosravi, Bakhtyar; Geraiely, Babak

2017-11-01

Accurate measurement of Mitral Valve Area (MVA) is essential to determining the Mitral Stenosis (MS) severity and to achieving the best management strategies for this disease. The goal of the present study is to compare mitral valve area (MVA) measurement by Continuity Equation (CE) and Pressure Half-Time (PHT) methods with that of 2D-Planimetry (PL) in patients with moderate to severe mitral stenosis (MS). This comparison also was performed in subgroups of patients with significant Aortic Insufficiency (AI), Mitral Regurgitation (MR) and Atrial Fibrillation (AF). We studied 70 patients with moderate to severe MS who were referred to echocardiography clinic. MVA was determined by PL, CE and PHT methods. The agreement and correlations between MVA's obtained from various methods were determined by kappa index, Bland-Altman analysis, and linear regression analysis. The mean values for MVA calculated by CE was 0.81 cm (±0.27) and showed good correlation with those calculated by PL (0.95 cm, ±0.26 ) in whole population (r=0.771, P<0.001) and MR subgroup (r=0.763, P<0.001) and normal sinus rhythm and normal valve subgroups (r=0.858, P<0.001 and r=0.867, P<0.001, respectively). But CE methods didn't show any correlation in AF and AI subgroups. MVA measured by PHT had a good correlation with that measured by PL in whole population (r=0.770, P<0.001) and also in NSR (r=0.814, P<0.001) and normal valve subgroup (r=0.781, P<0.001). Subgroup with significant AI and those with significant MR showed moderate correlation (r=0.625, P=0.017 and r=0.595, P=0.041, respectively). Bland Altman Analysis showed that CE would estimate MVA smaller in comparison with PL in the whole population and all subgroups and PHT would estimate MVA larger in comparison with PL in the whole population and all subgroups. The mean bias for CE and PHT are 0.14 cm and -0.06 cm respectively. In patients with moderate to severe mitral stenosis, in the absence of concomitant AF, AI or MR, the accuracy of CE or PHT method in measuring MVA is nearly equal. But in the presence of significant AI or MR, PHT method is obviously superior to CE and in the presence of AF neither have sufficient accuracy.

Investigating Correlation between Protein Sequence Similarity and Semantic Similarity Using Gene Ontology Annotations.

PubMed

Ikram, Najmul; Qadir, Muhammad Abdul; Afzal, Muhammad Tanvir

2018-01-01

Sequence similarity is a commonly used measure to compare proteins. With the increasing use of ontologies, semantic (function) similarity is getting importance. The correlation between these measures has been applied in the evaluation of new semantic similarity methods, and in protein function prediction. In this research, we investigate the relationship between the two similarity methods. The results suggest absence of a strong correlation between sequence and semantic similarities. There is a large number of proteins with low sequence similarity and high semantic similarity. We observe that Pearson's correlation coefficient is not sufficient to explain the nature of this relationship. Interestingly, the term semantic similarity values above 0 and below 1 do not seem to play a role in improving the correlation. That is, the correlation coefficient depends only on the number of common GO terms in proteins under comparison, and the semantic similarity measurement method does not influence it. Semantic similarity and sequence similarity have a distinct behavior. These findings are of significant effect for future works on protein comparison, and will help understand the semantic similarity between proteins in a better way.

Dimension Preference and Component Selection: A Comparison of Alternative Methods for Measuring Children's Attention to Stimulus Attributes.

ERIC Educational Resources Information Center

Lipps, Leann E. T.

To investigate two measures which have been used to assess children's attention to stimulus dimensions, component selection, and dimension preference, both measures were administered to 38 3 1/2 to 5-year-olds and 20 5- to 6 1/2-year-olds. Seven to ten days after the dimension preference task was given. the component selection measure was…

Research on signal processing method for total organic carbon of water quality online monitor

NASA Astrophysics Data System (ADS)

Ma, R.; Xie, Z. X.; Chu, D. Z.; Zhang, S. W.; Cao, X.; Wu, N.

2017-08-01

At present, there is no rapid, stable and effective approach of total organic carbon (TOC) measurement in the Marine environmental online monitoring field. Therefore, this paper proposes an online TOC monitor of chemiluminescence signal processing method. The weak optical signal detected by photomultiplier tube can be enhanced and converted by a series of signal processing module: phase-locked amplifier module, fourth-order band pass filter module and AD conversion module. After a long time of comparison test & measurement, compared with the traditional method, on the premise of sufficient accuracy, this chemiluminescence signal processing method can offer greatly improved measuring speed and high practicability for online monitoring.

3D topography of biologic tissue by multiview imaging and structured light illumination

NASA Astrophysics Data System (ADS)

Liu, Peng; Zhang, Shiwu; Xu, Ronald

2014-02-01

Obtaining three-dimensional (3D) information of biologic tissue is important in many medical applications. This paper presents two methods for reconstructing 3D topography of biologic tissue: multiview imaging and structured light illumination. For each method, the working principle is introduced, followed by experimental validation on a diabetic foot model. To compare the performance characteristics of these two imaging methods, a coordinate measuring machine (CMM) is used as a standard control. The wound surface topography of the diabetic foot model is measured by multiview imaging and structured light illumination methods respectively and compared with the CMM measurements. The comparison results show that the structured light illumination method is a promising technique for 3D topographic imaging of biologic tissue.

Photomask linewidth comparison by PTB and NIST

NASA Astrophysics Data System (ADS)

Bergmann, D.; Bodermann, B.; Bosse, H.; Buhr, E.; Dai, G.; Dixson, R.; Häßler-Grohne, W.; Hahm, K.; Wurm, M.

2015-10-01

We report the initial results of a recent bilateral comparison of linewidth or critical dimension (CD) calibrations on photomask line features between two national metrology institutes (NMIs): the National Institute of Standards and Technology (NIST) in the United States and the Physikalisch-Technische Bundesanstalt (PTB) in Germany. For the comparison, a chrome on glass (CoG) photomask was used which has a layout of line features down to 100 nm nominal size. Different measurement methods were used at both institutes. These included: critical dimension atomic force microscopy (CD-AFM), CD scanning electron microscopy (CD-SEM) and ultraviolet (UV) transmission optical microscopy. The measurands are CD at 50 % height of the features as well as sidewall angle and line width roughness (LWR) of the features. On the isolated opaque features, we found agreement of the CD measurements at the 3 nm to 5 nm level on most features - usually within the combined expanded uncertainties of the measurements.

Digital Quantification of Goldmann Visual Fields (GVF) as a Means for Genotype-Phenotype Comparisons and Detection of Progression in Retinal Degenerations

PubMed Central

Zahid, Sarwar; Peeler, Crandall; Khan, Naheed; Davis, Joy; Mahmood, Mahdi; Heckenlively, John; Jayasundera, Thiran

2015-01-01

Purpose To develop a reliable and efficient digital method to quantify planimetric Goldmann visual field (GVF) data to monitor disease course and treatment responses in retinal degenerative diseases. Methods A novel method to digitally quantify GVF using Adobe Photoshop CS3 was developed for comparison to traditional digital planimetry (Placom 45C digital planimeter; EngineerSupply, Lynchburg, Virginia, USA). GVFs from 20 eyes from 10 patients with Stargardt disease were quantified to assess the difference between the two methods (a total of 230 measurements per method). This quantification approach was also applied to 13 patients with X-linked retinitis pigmentosa (XLRP) with mutations in RPGR. Results Overall, measurements using Adobe Photoshop were more rapidly performed than those using conventional planimetry. Photoshop measurements also exhibited less inter- and intra-observer variability. GVF areas for the I4e isopter in patients with the same mutation in RPGR who were nearby in age had similar qualitative and quantitative areas. Conclusions Quantification of GVF using Adobe Photoshop is quicker, more reliable, and less-user dependent than conventional digital planimetry. It will be a useful tool for both retrospective and prospective studies of disease course as well as for monitoring treatment response in clinical trials for retinal degenerative diseases. PMID:24664690

Ground Snow Measurements: Comparisons of the Hotplate, Weighing and Manual Methods

NASA Astrophysics Data System (ADS)

Wettlaufer, A.; Snider, J.; Campbell, L. S.; Steenburgh, W. J.; Burkhart, M.

2015-12-01

The Yankee Environmental Systems (YES) Hotplate was developed to avoid some of the problems associated with weighing snowfall sensors. This work compares Hotplate, weighing sensor (ETI NOAH-II) and manual measurements of liquid-equivalent depth. The main field site was at low altitude in western New York; Hotplate and ETI comparisons were also made at two forested subalpine sites in southeastern Wyoming. The manual measurement (only conducted at the New York site) was derived by weighing snow cores sampled from a snow board. The two recording gauges (Hotplate and ETI) were located within 5 m of the snow board. Hotplate-derived accumulations were corrected using a wind-speed dependent catch efficiency and the ETI orifice was heated and alter shielded. Three important findings are evident from the comparisons: 1) The Yes-derived accumulations, recorded in a user-accessible file, were compared to accumulations derived using an in-house calibration and fundamental measurements (plate power, long and shortwave radiances, wind speed, and temperature). These accumulations are highly correlated (N=24; r2=0.99), but the YES-derived values are larger by 20%. 2) The in-house Hotplate accumulations are in good agreement with ETI-based accumulations but with larger variability (N=24; r2=0.88). 3) The comparison of in-house Hotplate accumulation versus manual accumulation, expressed as mm of liquid, exhibits a fitted linear relationship Y (in-house) versus X (manual) given by Y = -0.2 (±1.4) + 0.9 (±0.1) · X (N= 20; r2=0.89). Thus, these two methods agree within statistical uncertainty.

Measuring financial protection against catastrophic health expenditures: methodological challenges for global monitoring.

PubMed

Hsu, Justine; Flores, Gabriela; Evans, David; Mills, Anne; Hanson, Kara

2018-05-31

Monitoring financial protection against catastrophic health expenditures is important to understand how health financing arrangements in a country protect its population against high costs associated with accessing health services. While catastrophic health expenditures are generally defined to be when household expenditures for health exceed a given threshold of household resources, there is no gold standard with several methods applied to define the threshold and household resources. These different approaches to constructing the indicator might give different pictures of a country's progress towards financial protection. In order for monitoring to effectively provide policy insight, it is critical to understand the sensitivity of measurement to these choices. This paper examines the impact of varying two methodological choices by analysing household expenditure data from a sample of 47 countries. We assess sensitivity of cross-country comparisons to a range of thresholds by testing for restricted dominance. We further assess sensitivity of comparisons to different methods for defining household resources (i.e. total expenditure, non-food expenditure and non-subsistence expenditure) by conducting correlation tests of country rankings. We found country rankings are robust to the choice of threshold in a tenth to a quarter of comparisons within the 5-85% threshold range and this increases to half of comparisons if the threshold is restricted to 5-40%, following those commonly used in the literature. Furthermore, correlations of country rankings using different methods to define household resources were moderate to high; thus, this choice makes less difference from a measurement perspective than from an ethical perspective as different definitions of available household resources reflect varying concerns for equity. Interpreting comparisons from global monitoring based on a single threshold should be done with caution as these may not provide reliable insight into relative country progress. We therefore recommend financial protection against catastrophic health expenditures be measured across a range of thresholds using a catastrophic incidence curve as shown in this paper. We further recommend evaluating financial protection in relation to a country's health financing system arrangements in order to better understand the extent of protection and better inform future policy changes.

Effectiveness of the surviving the Teens® suicide prevention and depression awareness program: an impact evaluation utilizing a comparison group.

PubMed

Strunk, Catherine M; King, Keith A; Vidourek, Rebecca A; Sorter, Michael T

2014-12-01

Youth suicide is a serious public health issue in the United States. It is currently the third leading cause of death for youth aged 10 to 19. School-based prevention programs may be an effective method of educating youth and enhancing their help-seeking. Most school-based suicide prevention programs have not been rigorously evaluated for their effectiveness. This evaluation employs a comparison group to measure whether program group participants differed significantly from comparison group participants on pretest-posttest measures while assessing the immediate impact of the Surviving the Teens® Suicide Prevention and Depression Awareness Program. Findings indicate several positive outcomes in program group students' suicide and depression knowledge, attitudes, confidence, and behavioral intentions compared with the comparison group. Suicide prevention specialists and prevention planners may benefit from study findings. © 2014 Society for Public Health Education.

Artificial bias typically neglected in comparisons of uncertain atmospheric data

NASA Astrophysics Data System (ADS)

Pitkänen, Mikko R. A.; Mikkonen, Santtu; Lehtinen, Kari E. J.; Lipponen, Antti; Arola, Antti

2016-09-01

Publications in atmospheric sciences typically neglect biases caused by regression dilution (bias of the ordinary least squares line fitting) and regression to the mean (RTM) in comparisons of uncertain data. We use synthetic observations mimicking real atmospheric data to demonstrate how the biases arise from random data uncertainties of measurements, model output, or satellite retrieval products. Further, we provide examples of typical methods of data comparisons that have a tendency to pronounce the biases. The results show, that data uncertainties can significantly bias data comparisons due to regression dilution and RTM, a fact that is known in statistics but disregarded in atmospheric sciences. Thus, we argue that often these biases are widely regarded as measurement or modeling errors, for instance, while they in fact are artificial. It is essential that atmospheric and geoscience communities become aware of and consider these features in research.

Calibration of TOMS Radiances From Ground Observations

NASA Technical Reports Server (NTRS)

Bojkov, B. R.; Kowalewski, M.; Wellemeyer, C.; Labow, G.; Hilsenrath, E.; Bhartia, P. K.; Ahmad, Z.

2003-01-01

Verification of a stratospheric ozone recovery remains a high priority for environmental research and policy definition. Models predict an ozone recovery at a much lower rate than the measured depletion rate observed to date. Therefore improved precision of the satellite and ground ozone observing systems are required over the long term to verify its recovery. We show that validation of radiances from the ground can be a very effective means for correcting long term drifts of backscatter type satellite measurements and can be used to cross calibrate all BUV instruments in orbit (TOMS, SBUV/2, GOME, SCIAMACHY, OMI, GOME-2, OMPS). This method bypasses the retrieval algorithms used to derive ozone products from both satellite and ground based measurements that are normally used to validate the satellite data. Radiance comparisons employ forward models, but they are inherently more accurate than the retrieval This method employs very accurate comparisons between ground based zenith sicy radiances and satellite nadir radiances and employs two well established capabilities at the Goddard Space Flight Center, 1) the SSBUV calibration facilities and 2) the radiative transfer codes used for the TOMS and SBUV/2 algorithms and their subsequent refinements. The zenith sky observations are made by the SSBUV where its calibration is maintained to a high degree of accuracy and precision. Radiative transfer calculations show that ground based zenith sky and satellite nadir backscatter ultraviolet comparisons can be made very accurately under certain viewing conditions. Initial ground observations taken from Goddard Space Flight Center compared with radiative transfer calculations has indicated the feasibility of this method. The effect of aerosols and varying ozone amounts are considered in the model simulations and the theoretical comparisons. The radiative transfer simulations show that the ground and satellite radiance comparisons can be made with an uncertainty of less than l\\% without the knowledge of the amount ozone viewed by either instrument on ground or in space. algorithms.

Comparison of methods for measurement of organic compounds at ultra-trace level: analytical criteria and application to analysis of amino acids in extraterrestrial samples.

PubMed

Vandenabeele-Trambouze, O; Claeys-Bruno, M; Dobrijevic, M; Rodier, C; Borruat, G; Commeyras, A; Garrelly, L

2005-02-01

The need for criteria to compare different analytical methods for measuring extraterrestrial organic matter at ultra-trace levels in relatively small and unique samples (e.g., fragments of meteorites, micrometeorites, planetary samples) is discussed. We emphasize the need to standardize the description of future analyses, and take the first step toward a proposed international laboratory network for performance testing.

Video Measurements: Quantity or Quality

ERIC Educational Resources Information Center

Zajkov, Oliver; Mitrevski, Boce

2012-01-01

Students have problems with understanding, using and interpreting graphs. In order to improve the students' skills for working with graphs, we propose Manual Video Measurement (MVM). In this paper, the MVM method is explained and its accuracy is tested. The comparison with the standardized video data software shows that its accuracy is comparable…

Examining the Bricks and Mortar of Socioeconomic Status: An Empirical Comparison of Measurement Methods

ERIC Educational Resources Information Center

Markle, Ross Edward

2010-01-01

The impact of socioeconomic status (SES) on educational outcomes has been widely demonstrated in the fields of sociology, psychology, and educational research. Across these fields however, measurement models of SES vary, including single indicators (parental income, education, and occupation), multiple indicators, hierarchical models, and most…

Self-Discrepancy: Comparisons of the Psychometric Properties of Three Instruments

ERIC Educational Resources Information Center

Watson, Neill; Bryan, Brandon C.; Thrash, Todd M.

2010-01-01

In 2 studies, the psychometric properties of 3 methods for measuring real-ideal and real ought self-discrepancies were compared: the idiographic Self-Concept Questionnaire--Personal Constructs, the nonidiographic Self-Concept Questionnaire--Conventional Constructs, and the content-free Abstract Measures. In the 1st study, 125 students at a…

Clinical aviation medicine research : comparison of simultaneous measurements of intra-aortic and auscultatory blood pressures with pressure-flow dynamics during rest and excercise.

DOT National Transportation Integrated Search

1966-10-01

The study provides correlative information with respect to the comparative accuracy of the traditional 'cuff' clinical method of obtaining blood pressure and the laboratory catheterization procedure which measures actual blood pressure. The informati...

Comparison of Nasal Acceleration and Nasalance across Vowels

ERIC Educational Resources Information Center

Thorp, Elias B.; Virnik, Boris T.; Stepp, Cara E.

2013-01-01

Purpose: The purpose of this study was to determine the performance of normalized nasal acceleration (NNA) relative to nasalance as estimates of nasalized versus nonnasalized vowel and sentence productions. Method: Participants were 18 healthy speakers of American English. NNA was measured using a custom sensor, and nasalance was measured using…

Investigation of Presage 3D Dosimetry as a Method of Clinically Intuitive Quality Assurance and Comparison to a Semi-3D Delta4 System

NASA Astrophysics Data System (ADS)

Crockett, Ethan Van

The need for clinically intuitive metrics for patient-specific quality assurance in radiation therapy has been well-documented (Zhen, Nelms et al. 2011). A novel transform method has shown to be effective at converting full-density 3D dose measurements made in a phantom to dose values in the patient geometry, enabling comparisons using clinically intuitive metrics such as dose-volume histograms (Oldham et al. 2011). This work investigates the transform method and compares its calculated dose-volume histograms (DVHs) to DVH values calculated by a Delta4 QA device (Scandidos), marking the first comparison of a true 3D system to a semi-3D device using clinical metrics. Measurements were made using Presage 3D dosimeters, which were readout by an in-house optical-CT scanner. Three patient cases were chosen for the study: one head-and-neck VMAT treatment and two spine IMRT treatments. The transform method showed good agreement with the planned dose values for all three cases. Furthermore, the transformed DVHs adhered to the planned dose with more accuracy than the Delta4 DVHs. The similarity between the Delta4 DVHs and the transformed DVHs, however, was greater for one of the spine cases than it was for the head-and-neck case, implying that the accuracy of the Delta4 Anatomy software may vary from one treatment site to another. Overall, the transform method, which incorporates data from full-density 3D dose measurements, provides clinically intuitive results that are more accurate and consistent than the corresponding results from a semi-3D Delta 4 system.

Measuring Glial Metabolism in Repetitive Brain Trauma and Alzheimer’s Disease

DTIC Science & Technology

2016-09-01

Six methods: Single value decomposition (SVD), wavelet, sliding window, sliding window with Gaussian weighting, spline and spectral improvements...comparison of a range of different denoising methods for dynamic MRS. Six denoising methods were considered: Single value decomposition (SVD), wavelet...project by improving the software required for the data analysis by developing six different denoising methods. He also assisted with the testing

An experimental comparison of various methods of nearfield acoustic holography

DOE PAGES

Chelliah, Kanthasamy; Raman, Ganesh; Muehleisen, Ralph T.

2017-05-19

An experimental comparison of four different methods of nearfield acoustic holography (NAH) is presented in this study for planar acoustic sources. The four NAH methods considered in this study are based on: (1) spatial Fourier transform, (2) equivalent sources model, (3) boundary element methods and (4) statistically optimized NAH. Two dimensional measurements were obtained at different distances in front of a tonal sound source and the NAH methods were used to reconstruct the sound field at the source surface. Reconstructed particle velocity and acoustic pressure fields presented in this study showed that the equivalent sources model based algorithm along withmore » Tikhonov regularization provided the best localization of the sources. Reconstruction errors were found to be smaller for the equivalent sources model based algorithm and the statistically optimized NAH algorithm. Effect of hologram distance on the performance of various algorithms is discussed in detail. The study also compares the computational time required by each algorithm to complete the comparison. Four different regularization parameter choice methods were compared. The L-curve method provided more accurate reconstructions than the generalized cross validation and the Morozov discrepancy principle. Finally, the performance of fixed parameter regularization was comparable to that of the L-curve method.« less

An experimental comparison of various methods of nearfield acoustic holography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chelliah, Kanthasamy; Raman, Ganesh; Muehleisen, Ralph T.

An experimental comparison of four different methods of nearfield acoustic holography (NAH) is presented in this study for planar acoustic sources. The four NAH methods considered in this study are based on: (1) spatial Fourier transform, (2) equivalent sources model, (3) boundary element methods and (4) statistically optimized NAH. Two dimensional measurements were obtained at different distances in front of a tonal sound source and the NAH methods were used to reconstruct the sound field at the source surface. Reconstructed particle velocity and acoustic pressure fields presented in this study showed that the equivalent sources model based algorithm along withmore » Tikhonov regularization provided the best localization of the sources. Reconstruction errors were found to be smaller for the equivalent sources model based algorithm and the statistically optimized NAH algorithm. Effect of hologram distance on the performance of various algorithms is discussed in detail. The study also compares the computational time required by each algorithm to complete the comparison. Four different regularization parameter choice methods were compared. The L-curve method provided more accurate reconstructions than the generalized cross validation and the Morozov discrepancy principle. Finally, the performance of fixed parameter regularization was comparable to that of the L-curve method.« less

Measurement Of Trailing Edge Noise using Directional Array and Coherent Output Power Methods

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Brooks, Thomas F.

2002-01-01

The use of a directional array of microphones for the measurement of trailing edge (TE) noise is described. The capabilities of this method are evaluated via measurements of TE noise from a NACA 63-215 airfoil model and from a cylindrical rod. This TE noise measurement approach is compared to one that is based on the cross spectral analysis of output signals from a pair of microphones (COP method). Advantages and limitations of both methods are examined. It is shown that the microphone array can accurately measures TE noise and captures its two-dimensional characteristic over a large frequency range for any TE configuration as long as noise contamination from extraneous sources is within bounds. The COP method is shown to also accurately measure TE noise but over a more limited frequency range that narrows for increased TE thickness. Finally, the applicability and generality of an airfoil self-noise prediction method was evaluated via comparison to the experimental data obtained using the COP and array measurement methods. The predicted and experimental results are shown to agree over large frequency ranges.

Fully automated measuring setup for tactile coordinate measuring machine for three dimensional measurement of freeform eyeglass frames

NASA Astrophysics Data System (ADS)

Rückwardt, M.; Göpfert, A.; Correns, M.; Schellhorn, M.; Linß, G.

2010-07-01

Coordinate measuring machines are high precession all-rounder in three dimensional measuring. Therefore the versatility of parameters and expandability of additionally hardware is very comprehensive. Consequently you need much expert knowledge of the user and mostly a lot of advanced information about the measuring object. In this paper a coordinate measuring machine and a specialized measuring machine are compared at the example of the measuring of eyeglass frames. For this case of three dimensional measuring challenges the main focus is divided into metrological and economical aspects. At first there is shown a fully automated method for tactile measuring of this abstract form. At second there is shown a comparison of the metrological characteristics of a coordinate measuring machine and a tracer for eyeglass frames. The result is in favour to the coordinate measuring machine. It was not surprising in these aspects. At last there is shown a comparison of the machine in front of the economical aspects.

Ground-based measurements of ionospheric dynamics

NASA Astrophysics Data System (ADS)

Kouba, Daniel; Chum, Jaroslav

2018-05-01

Different methods are used to research and monitor the ionospheric dynamics using ground measurements: Digisonde Drift Measurements (DDM) and Continuous Doppler Sounding (CDS). For the first time, we present comparison between both methods on specific examples. Both methods provide information about the vertical drift velocity component. The DDM provides more information about the drift velocity vector and detected reflection points. However, the method is limited by the relatively low time resolution. In contrast, the strength of CDS is its high time resolution. The discussed methods can be used for real-time monitoring of medium scale travelling ionospheric disturbances. We conclude that it is advantageous to use both methods simultaneously if possible. The CDS is then applied for the disturbance detection and analysis, and the DDM is applied for the reflection height control.

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

PubMed

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

2015-09-18

High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of magnification and superimposition of structures on cephalometric diagnosis.

PubMed

Paula, Leonardo Koerich de; Solon-de-Mello, Priscilla de Almeida; Mattos, Claudia Trindade; Ruellas, Antônio Carlos de Oliveira; Sant'Anna, Eduardo Franzotti

2015-01-01

The purpose of this study was to assess the influence of magnification and superimposition of structures on CBCT-generated lateral cephalometric radiographs (LCR) using different segments of the cranium. CBCT scans of 10 patients were selected. Four LCR were generated using Dolphin Imaging(r) software: full-face, right side, left side and center of the head. A total of 40 images were imported into Radiocef Studio 2(r), and the angles of the most common cephalometric analyses were traced by the same observer twice and within a 10-day interval. Statistical analyses included intraexaminer agreement and comparison between methods by means of intraclass correlation coefficient (ICC) and Bland-Altman agreement tests. Intraexaminer agreement of the angles assessed by ICC was excellent (> 0.90) for 83% of measurements, good (between 0.75 and 0.90) for 15%, and moderate (between 0.50 and 0.75) for 2% of measurements. The comparison between methods by ICC was excellent for 68% of measurements, good for 26%, and moderate for 6%. Variables presenting wider confidence intervals (> 6o) in the Bland-Altman tests, in intraexaminer assessment, were: mandibular incisor angle, maxillary incisor angle, and occlusal plane angle. And in comparison methods the variables with wider confidence interval were: mandibular incisor, maxillary incisor, GoGn, occlusal plane angle, Frankfort horizontal plane (FHP), and CoA. Superimposition of structures seemed to influence the results more than magnification, and neither one of them significantly influenced the measurements. Considerable individual variability may occur, especially for mandibular and maxillary incisors, FHP and occlusal plane.

EVALUATION OF METHODS FOR THE DETERMINATION OF DIESEL-GENERATED FINE PARTICULATE MATTER: PHYSICAL CHARACTERIZATION OF RESULTS

EPA Science Inventory

A multi-phase instrument comparison study was conducted on two different diesel engines on a dynamometer to compare commonly used particulate matter (PM) measurement techniques while sampling the same diesel exhaust aerosol and to evaluate inter- and intra-method variability. In...

ASSESSMENT OF PC12 CELL DIFFERENTIATION AND NEURITE GROWTH: A COMPARISON OF MORPHOLOGICAL AND NEUROCHEMICAL MEASURES.

EPA Science Inventory

In order to screen large numbers of chemicals for their potential to produce developmental neurotoxicity new, in vitro methods are needed. One approach is to develop methods based on the biologic processes which underlie brain development including the growth and maturation of ce...

Using Artificial Neural Networks in Educational Research: Some Comparisons with Linear Statistical Models.

ERIC Educational Resources Information Center

Everson, Howard T.; And Others

This paper explores the feasibility of neural computing methods such as artificial neural networks (ANNs) and abductory induction mechanisms (AIM) for use in educational measurement. ANNs and AIMS methods are contrasted with more traditional statistical techniques, such as multiple regression and discriminant function analyses, for making…

COMPARISON OF SAMPLING METHODS FOR SEMI-VOLATILE ORGANIC CARBON (SVOC) ASSOCIATED WITH PM 2.5

EPA Science Inventory

This study evaluates the influence of denuder sampling methods and filter collection media on the measurement of semi-volatile organic carbon (SVOC) associated with PM2.5. Two types of collection media, charcoal (activated carbon) and XAD, were used both in diffusion denuders ...

COMPARISON OF SAMPLING METHODS FOR SEMI-VOLATILE ORGANIC CARBON ASSOCIATED WITH PM 2.5

EPA Science Inventory

This study evaluates the influence of denuder sampling methods and filter collection media on the measurement of semi-volatile organic carbon (SVOC) associated with PM2.5. Two types of collection media, charcoal (activated carbon) and XAD, were used both in diffusion denuders ...

Stored grain pack factors for wheat: comparison of three methods to field measurements

USDA-ARS?s Scientific Manuscript database

Storing grain in bulk storage units results in grain packing from overbearing pressure, which increases grain bulk density and storage-unit capacity. This study compared pack factors of hard red winter (HRW) wheat in vertical storage bins using different methods: the existing packing model (WPACKING...

(PRESENTED NAQC SAN FRANCISCO, CA) COARSE PM METHODS STUDY: STUDY DESIGN AND RESULTS

EPA Science Inventory

Comprehensive field studies were conducted to evaluate the performance of sampling methods for measuring the coarse fraction of PM10 in ambient air. Five separate sampling approaches were evaluated at each of three sampling sites. As the primary basis of comparison, a discrete ...

DETECTION OF HUMAN ENTERIC VIRUSES IN STREAM WATER WITH RT-PCR AND CELL CULTURE

EPA Science Inventory

A multiplex RT-PCR method was used to measure virus occurrence at five stream water sites that span a range of hydroclimatic, water-quality, and land-use characteristics. The performance of the molecular method was evaluated in comparison to traditional cell culture and Escherich...

KEY COMPARISON: Final report on CCQM-K9.2: Subsequent key comparison on pH determination of phosphate buffer by Harned cell measurements

NASA Astrophysics Data System (ADS)

Spitzer, Petra; Giera, Janine; Fraga, Isabel C.; Tønnes Jakobsen, Pia; Jensen, Hans D.; Hyllested, Peter; Karpov, Oleg; Kutovoy, Viatcheslav; Nakamura, Susumu; Vospelova, Alena; Zvezdina, Valentina

2008-01-01

CCQM-K9.2 was performed supplementary to the key comparison CCQM-K9 on the pH determination of a phosphate buffer with nominal pH ~ 6.9 (at 25 °C). The sample composition was very similar in both comparisons. Only the source of the starting material used for sample preparation was different. The comparison was restricted to the use of the primary method for pH (Harned cell measurement) as defined in the IUPAC Recommendations [2]. The measurement temperatures were 15 °C, 25 °C, 37 °C. CCQM-K9.2, CCQM-K.9 and the first supplementary comparison CCQM-K9.1 [5] are activities of the Electrochemical Working Group (EAWG) of the CCQM. All three comparisons were coordinated by the PTB, Germany. The Danish Primary Laboratory (DPL) successfully took part in the CCQM-K9. Meanwhile the primary set-up for pH in Denmark moved from DPL affiliated to Radiometer Medical to DFM, Denmark. The subsequent comparison allows assessing the degree of equivalence for the measurement of pH at DFM after the move. Due to the interest of other laboratories in demonstrating their progress in pH measurements on the primary level the CCQM-K9.2 supplementary comparison was extended to other participants than DFM, namely NMIJ, VNIIFTRI, INMETRO and CMI. The reported quantity for CCQM-K9.2 was not the pH of the sample but the acidity function at zero chloride molality (see chapter 12). To calculate the pH value from the acidity function it is necessary to know the ionic strength of the sample buffer solution, which was undisclosed by the coordinator. With the exception of the Czech Metrology Institute, CMI, good agreement in the determined acidity function is found between the participants. The results reported by DFM and by PTB agree within their measurement uncertainty at all measurement temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

KEY COMPARISON: Final report of the CCQM-K56: Ca, Fe, Zn and Cu in whole fat soybean powder

NASA Astrophysics Data System (ADS)

Liandi, Ma; Qian, Wang

2010-01-01

The CCQM-K56 key comparison was organized by the Inorganic Analysis Working Group (IAWG) of CCQM as a follow-up to completed pilot study CCQM-P64 to test the abilities of national metrology institutes to measure the amount content of nutritious elements in whole fat soybean powder. A pilot study CCQM-P64.1 was conducted in parallel with this key comparison. The National Institute of Metrology (NIM), P. R. China, acted as the coordinating laboratory. Eleven NIMs participated in CCQM-K56. Four elements - Ca, Fe, Zn and Cu - in different concentration levels have been studied. Different measurement methods (IDMS, ICP-MS, ICP-OES, AAS and INAA) and the microwave digestion method were used. The agreement of the results of CCQM-K56 is very good, and obviously better than that of the original P64. It shows that the capability of all of the participants had been promoted from the original pilot study to this key comparison. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Diffuse reflectance spectrophotometry with visible light: comparison of four different methods in a tissue phantom

NASA Astrophysics Data System (ADS)

Gade, John; Palmqvist, Dorte; Plomgård, Peter; Greisen, Gorm

2006-01-01

The purpose of the study was to compare algorithms of four methods (plus two modifications) for spectrophotometric haemoglobin saturation measurements. Comparison was made in tissue phantoms basically consisting of a phosphate buffer, Intralipid and blood, allowing samples to be taken for reference measurements. Three experimental series were made. In experiment A (eight phantoms) we used the Knoefel method and measured specific extinction coefficients with a reflection spectrophotometer. In experiment B (six phantoms) the fully oxygenated phantoms were gradually deoxygenated with baker's yeast, and simultaneous measurements were made with our spectrophotometer and with a reference oxymeter (ABL-605) in 3 min intervals. For each spectrophotometric measurement haemoglobin saturation was calculated with all algorithms and modifications, and compared with reference. In experiment C (11 phantoms) we evaluated the ability of a modification of the Knoefel method to measure haemoglobin concentration in absolute quantities using extinction coefficients from experiment A. Results. Experiment A: with the Knoefel method extinction coefficients (±SD) for oxyhaemoglobin at 553.04 and 573.75 nm were 1.117 (±0.0396) ODmM-1 and 1.680 (± 0.0815) ODmM-1, respectively, and for deoxyhaemoglobin 1.205 (± 0.0514) ODmM-1 and 0.953 (±0.0487) ODmM-1, respectively. Experiment B: high correlation with the reference was found in all methods (r = 0.94-0.97). However, agreement varied from evidently wrong in method 3 and the original method 4 (e.g. saturation above 160%) to high agreement in method 2 as well as the modifications of methods 1 and 4, where oxygen dissociation curves were close to the reference method. Experiment C: with the modified Knoefel method the mean haemoglobin concentration difference from reference was 8.3% and the correlation was high (r = 0.91). We conclude that method 2 and the modifications of 1 and 4 were superior to the others, but depended on known values in the same or similar phantoms. The original method 1 was independent of results from the tissue phantoms, but agreement was slightly poorer. Method 3 and the original method 4 could not be recommended. The ability of the modified method 1 to measure haemoglobin concentration is promising, but needs further development.

Conduct of a personal radiofrequency electromagnetic field measurement study: proposed study protocol.

PubMed

Röösli, Martin; Frei, Patrizia; Bolte, John; Neubauer, Georg; Cardis, Elisabeth; Feychting, Maria; Gajsek, Peter; Heinrich, Sabine; Joseph, Wout; Mann, Simon; Martens, Luc; Mohler, Evelyn; Parslow, Roger C; Poulsen, Aslak Harbo; Radon, Katja; Schüz, Joachim; Thuroczy, György; Viel, Jean-François; Vrijheid, Martine

2010-05-20

The development of new wireless communication technologies that emit radio frequency electromagnetic fields (RF-EMF) is ongoing, but little is known about the RF-EMF exposure distribution in the general population. Previous attempts to measure personal exposure to RF-EMF have used different measurement protocols and analysis methods making comparisons between exposure situations across different study populations very difficult. As a result, observed differences in exposure levels between study populations may not reflect real exposure differences but may be in part, or wholly due to methodological differences. The aim of this paper is to develop a study protocol for future personal RF-EMF exposure studies based on experience drawn from previous research. Using the current knowledge base, we propose procedures for the measurement of personal exposure to RF-EMF, data collection, data management and analysis, and methods for the selection and instruction of study participants. We have identified two basic types of personal RF-EMF measurement studies: population surveys and microenvironmental measurements. In the case of a population survey, the unit of observation is the individual and a randomly selected representative sample of the population is needed to obtain reliable results. For microenvironmental measurements, study participants are selected in order to represent typical behaviours in different microenvironments. These two study types require different methods and procedures. Applying our proposed common core procedures in future personal measurement studies will allow direct comparisons of personal RF-EMF exposures in different populations and study areas.

Comparing the Medicaid Retrospective Drug Utilization Review Program Cost-Savings Methods Used by State Agencies.

PubMed

Prada, Sergio I

2017-12-01

The Medicaid Drug Utilization Review (DUR) program is a 2-phase process conducted by Medicaid state agencies. The first phase is a prospective DUR and involves electronically monitoring prescription drug claims to identify prescription-related problems, such as therapeutic duplication, contraindications, incorrect dosage, or duration of treatment. The second phase is a retrospective DUR and involves ongoing and periodic examinations of claims data to identify patterns of fraud, abuse, underutilization, drug-drug interaction, or medically unnecessary care, implementing corrective actions when needed. The Centers for Medicare & Medicaid Services requires each state to measure prescription drug cost-savings generated from its DUR programs on an annual basis, but it provides no guidance or unified methodology for doing so. To describe and synthesize the methodologies used by states to measure cost-savings using their Medicaid retrospective DUR program in federal fiscal years 2014 and 2015. For each state, the cost-savings methodologies included in the Medicaid DUR 2014 and 2015 reports were downloaded from Medicaid's website. The reports were then reviewed and synthesized. Methods described by the states were classified according to research designs often described in evaluation textbooks. In 2014, the most often used prescription drugs cost-savings estimation methodology for the Medicaid retrospective DUR program was a simple pre-post intervention method, without a comparison group (ie, 12 states). In 2015, the most common methodology used was a pre-post intervention method, with a comparison group (ie, 14 states). Comparisons of savings attributed to the program among states are still unreliable, because of a lack of a common methodology available for measuring cost-savings. There is great variation among states in the methods used to measure prescription drug utilization cost-savings. This analysis suggests that there is still room for improvement in terms of methodology transparency, which is important, because lack of transparency hinders states from learning from each other. Ultimately, the federal government needs to evaluate and improve its DUR program.

Correlations between the Various Methods of Estimating Prostate Volume: Transabdominal, Transrectal, and Three-Dimensional US

PubMed Central

Kim, Seung Hyup

2008-01-01

Objective To evaluate the correlations between prostate volumes estimated by transabdominal, transrectal, and three-dimensional US and the factors affecting the differences. Materials and Methods The prostate volumes of 94 consecutive patients were measured by both transabdominal and transrectal US. Next, the prostate volumes of 58 other patients was measured by both transrectal and three-dimensional US. We evaluated the degree of correlation and mean difference in each comparison. We also analyzed possible factors affecting the differences, such as the experiences of examiners in transrectal US, bladder volume, and prostate volume. Results In the comparison of transabdominal and transrectal US methods, the mean difference was 8.4 ± 10.5 mL and correlation coefficient (r) was 0.775 (p < 0.01). The experienced examiner for the transrectal US method had the highest correlation (r = 0.967) and the significantly smallest difference (5.4 ± 3.9 mL) compared to the other examiners (the beginner and the trained; p < 0.05). Prostate volume measured by transrectal US showed a weak correlation with the difference (r = 0.360, p < 0.05). Bladder volume did not show significant correlation with the difference (r = -0.043, p > 0.05). The comparison between the transrectal and three-dimensional US methods revealed a mean difference of 3.7 ± 3.4 mL and the correlation coefficient was 0.924 for the experienced examiner. Furthermore, no significant difference existed between examiners (p > 0.05). Prostate volume measured by transrectal US showed a positive correlation with the difference for the beginner only (r = 0.405, p < 0.05). Conclusion In the prostate volume estimation by US, experience in transrectal US is important in the correlation with transabdominal US, but not with three-dimensional US. Also, less experienced examiners' assessment of the prostate volume can be affected by prostate volume itself. PMID:18385560

Methodology for the evaluation of the Stephanie Alexander Kitchen Garden program.

PubMed

Gibbs, L; Staiger, P K; Townsend, M; Macfarlane, S; Gold, L; Block, K; Johnson, B; Kulas, J; Waters, E

2013-04-01

Community and school cooking and gardening programs have recently increased internationally. However, despite promising indications, there is limited evidence of their effectiveness. This paper presents the evaluation framework and methods negotiated and developed to meet the information needs of all stakeholders for the Stephanie Alexander Kitchen Garden (SAKG) program, a combined cooking and gardening program implemented in selectively funded primary schools across Australia. The evaluation used multiple aligned theoretical frameworks and models, including a public health ecological approach, principles of effective health promotion and models of experiential learning. The evaluation is a non-randomised comparison of six schools receiving the program (intervention) and six comparison schools (all government-funded primary schools) in urban and rural areas of Victoria, Australia. A mixed-methods approach was used, relying on qualitative measures to understand changes in school cultures and the experiential impacts on children, families, teachers, parents and volunteers, and quantitative measures at baseline and 1 year follow up to provide supporting information regarding patterns of change. The evaluation study design addressed the limitations of many existing evaluation studies of cooking or garden programs. The multistrand approach to the mixed methodology maintained the rigour of the respective methods and provided an opportunity to explore complexity in the findings. Limited sensitivity of some of the quantitative measures was identified, as well as the potential for bias in the coding of the open-ended questions. The SAKG evaluation methodology will address the need for appropriate evaluation approaches for school-based kitchen garden programs. It demonstrates the feasibility of a meaningful, comprehensive evaluation of school-based programs and also demonstrates the central role qualitative methods can have in a mixed-method evaluation. So what? This paper contributes to debate about appropriate evaluation approaches to meet the information needs of all stakeholders and will support the sharing of measures and potential comparisons between program outcomes for comparable population groups and settings.

Inversion of solar extinction data from the Apollo-Soyuz Test Project Stratospheric Aerosol Measurement (ASTP/SAM) experiment

NASA Technical Reports Server (NTRS)

Pepin, T. J.

1977-01-01

The inversion methods are reported that have been used to determine the vertical profile of the extinction coefficient due to the stratospheric aerosols from data measured during the ASTP/SAM solar occultation experiment. Inversion methods include the onion skin peel technique and methods of solving the Fredholm equation for the problem subject to smoothing constraints. The latter of these approaches involves a double inversion scheme. Comparisons are made between the inverted results from the SAM experiment and near simultaneous measurements made by lidar and balloon born dustsonde. The results are used to demonstrate the assumptions required to perform the inversions for aerosols.

An Efficient and Robust Singular Value Method for Star Pattern Recognition and Attitude Determination

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Kim, Hye-Young; Junkins, John L.

2003-01-01

A new star pattern recognition method is developed using singular value decomposition of a measured unit column vector matrix in a measurement frame and the corresponding cataloged vector matrix in a reference frame. It is shown that singular values and right singular vectors are invariant with respect to coordinate transformation and robust under uncertainty. One advantage of singular value comparison is that a pairing process for individual measured and cataloged stars is not necessary, and the attitude estimation and pattern recognition process are not separated. An associated method for mission catalog design is introduced and simulation results are presented.

Ion chromatography for the precise analysis of chloride and sodium in sweat for the diagnosis of cystic fibrosis.

PubMed

Doorn, J; Storteboom, T T R; Mulder, A M; de Jong, W H A; Rottier, B L; Kema, I P

2015-07-01

Measurement of chloride in sweat is an essential part of the diagnostic algorithm for cystic fibrosis. The lack in sensitivity and reproducibility of current methods led us to develop an ion chromatography/high-performance liquid chromatography (IC/HPLC) method, suitable for the analysis of both chloride and sodium in small volumes of sweat. Precision, linearity and limit of detection of an in-house developed IC/HPLC method were established. Method comparison between the newly developed IC/HPLC method and the traditional Chlorocounter was performed, and trueness was determined using Passing Bablok method comparison with external quality assurance material (Royal College of Pathologists of Australasia). Precision and linearity fulfill criteria as established by UK guidelines are comparable with inductively coupled plasma-mass spectrometry methods. Passing Bablok analysis demonstrated excellent correlation between IC/HPLC measurements and external quality assessment target values, for both chloride and sodium. With a limit of quantitation of 0.95 mmol/L, our method is suitable for the analysis of small amounts of sweat and can thus be used in combination with the Macroduct collection system. Although a chromatographic application results in a somewhat more expensive test compared to a Chlorocounter test, more accurate measurements are achieved. In addition, simultaneous measurements of sodium concentrations will result in better detection of false positives, less test repeating and thus faster and more accurate and effective diagnosis. The described IC/HPLC method, therefore, provides a precise, relatively cheap and easy-to-handle application for the analysis of both chloride and sodium in sweat. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

A method for validation of finite element forming simulation on basis of a pointwise comparison of distance and curvature

NASA Astrophysics Data System (ADS)

Dörr, Dominik; Joppich, Tobias; Schirmaier, Fabian; Mosthaf, Tobias; Kärger, Luise; Henning, Frank

2016-10-01

Thermoforming of continuously fiber reinforced thermoplastics (CFRTP) is ideally suited to thin walled and complex shaped products. By means of forming simulation, an initial validation of the producibility of a specific geometry, an optimization of the forming process and the prediction of fiber-reorientation due to forming is possible. Nevertheless, applied methods need to be validated. Therefor a method is presented, which enables the calculation of error measures for the mismatch between simulation results and experimental tests, based on measurements with a conventional coordinate measuring device. As a quantitative measure, describing the curvature is provided, the presented method is also suitable for numerical or experimental sensitivity studies on wrinkling behavior. The applied methods for forming simulation, implemented in Abaqus explicit, are presented and applied to a generic geometry. The same geometry is tested experimentally and simulation and test results are compared by the proposed validation method.

A comparison of methods for estimating the weight of preterm infants.

PubMed

Elser, A S; Vessey, J A

1995-09-01

Four methods of predicting a preterm infant's weight (upper mid-arm circumference, gestational age, tape measure nomogram, and guessing) were investigated to see which was the most accurate. The weights of 37 preterm neonates were initially guessed by an experienced clinician, then estimated by the other three approaches applied in a random order, and then confirmed through actual weighing. The correlations between the four estimated weights and the actual weights were .96, .84, .97, and .98, respectively. The tape measure nomogram method was the best overall approach for clinical use.

Measuring Learning Gains in Chemical Education: A Comparison of Two Methods

ERIC Educational Resources Information Center

Pentecost, Thomas C.; Barbera, Jack

2013-01-01

Evaluating the effect of a pedagogical innovation is often done by looking for a significant difference in a content measure using a pre-post design. While this approach provides valuable information regarding the presence or absence of an effect, it is limited in providing details about the nature of the effect. A measure of the magnitude of the…

Comparison of 2 Radiographic Techniques for Measurement of Tibiofemoral Joint Space Width.

PubMed

Mehta, Nabil; Duryea, Jeffrey; Badger, Gary J; Akelman, Matthew R; Jones, Morgan H; Spindler, Kurt P; Fleming, Braden C

2017-09-01

No consensus is available regarding the best method for measuring tibiofemoral joint space width (JSW) on radiographs to quantify joint changes after injury. Studies that track articular cartilage thickness after injury frequently use patients' uninjured contralateral knees as controls, although the literature supporting this comparison is limited. (1) To compare JSW measurements using 2 established measurement techniques in healthy control participants and (2) to determine whether the mean JSW of the uninjured contralateral knee in a cohort with anterior cruciate ligament (ACL) reconstruction is different from that obtained from a true control population. Cohort study (diagnosis); Level of evidence, 2. Medial and lateral JSWs were measured on standardized, bilateral, semiflexed metatarsophalangeal positioning, posteroanterior radiographs of 60 healthy individuals (26 females; mean ± SD age, 25 ± 6.2 years; no history of knee injury) via 2 published techniques: a computerized surface-delineation method (surface-fit method) and a manual digitization method (midpoint method). Bland-Altman method was used to examine the agreement between JSW measurements obtained with the 2 methods and to examine the agreement between measurements obtained on left and right knees within a participant for each measurement method. Within- and between-participant variance components and intraclass correlation coefficients (ICCs) were computed for JSW measurements corresponding to each method. Two-sample t tests were used to compare the surface-fit method measurements of mean JSW of the true control group (n = 60) with the previously published mean JSW measurements from the Multicenter Orthopaedics Outcomes Network (MOON) nested cohort of 262 contralateral uninjured knees 2 to 3 years after ACL reconstruction. For JSW in the medial compartment, the surface-fit method had lower within-participant interknee variability (σ 2 within , 0.064; 95% CI, 0.04-0.09) compared with the midpoint method (σ 2 within , 0.28; 95% CI, 0.20-0.43) and a higher ICC (0.93 vs 0.65; P < .001). Lateral JSW values were similar for the surface-fit method (σ 2 within , 0.27; 95% CI, 0.18-0.43) and the midpoint method (σ 2 within , 0.20; 95% CI, 0.14-0.31), with ICCs of 0.75 and 0.77, respectively ( P = .80). With the surface-fit method, mean JSW measurements of the medial and lateral compartments of a control population were not significantly different from the contralateral uninjured knees of patients after ACL reconstruction. For measuring medial JSW, the surface-fit method was less variable across knees within a participant than the midpoint method, as evidenced by larger ICCs and lower interknee variability. For measuring lateral JSW, the 2 methods were similar. The JSW measurements of uninjured contralateral knees of patients with ACL reconstruction at 2 to 3 years postsurgery were not significantly different from those of a cohort of healthy control participants. Future work should be performed to demonstrate the validity of these methods for documenting change over time in the ACL-reconstructed knee.

High-precision radius automatic measurement using laser differential confocal technology

NASA Astrophysics Data System (ADS)

Jiang, Hongwei; Zhao, Weiqian; Yang, Jiamiao; Guo, Yongkui; Xiao, Yang

2015-02-01

A high precision radius automatic measurement method using laser differential confocal technology is proposed. Based on the property of an axial intensity curve that the null point precisely corresponds to the focus of the objective and the bipolar property, the method uses the composite PID (proportional-integral-derivative) control to ensure the steady movement of the motor for process of quick-trigger scanning, and uses least-squares linear fitting to obtain the position of the cat-eye and confocal positions, then calculates the radius of curvature of lens. By setting the number of measure times, precision auto-repeat measurement of the radius of curvature is achieved. The experiment indicates that the method has the measurement accuracy of better than 2 ppm, and the measuring repeatability is better than 0.05 μm. In comparison with the existing manual-single measurement, this method has a high measurement precision, a strong environment anti-interference capability, a better measuring repeatability which is only tenth of former's.

A revision of the gamma-evaluation concept for the comparison of dose distributions.

PubMed

Bakai, Annemarie; Alber, Markus; Nüsslin, Fridtjof

2003-11-07

A method for the quantitative four-dimensional (4D) evaluation of discrete dose data based on gradient-dependent local acceptance thresholds is presented. The method takes into account the local dose gradients of a reference distribution for critical appraisal of misalignment and collimation errors. These contribute to the maximum tolerable dose error at each evaluation point to which the local dose differences between comparison and reference data are compared. As shown, the presented concept is analogous to the gamma-concept of Low et al (1998a Med. Phys. 25 656-61) if extended to (3+1) dimensions. The pointwise dose comparisons of the reformulated concept are easier to perform and speed up the evaluation process considerably, especially for fine-grid evaluations of 3D dose distributions. The occurrences of false negative indications due to the discrete nature of the data are reduced with the method. The presented method was applied to film-measured, clinical data and compared with gamma-evaluations. 4D and 3D evaluations were performed. Comparisons prove that 4D evaluations have to be given priority, especially if complex treatment situations are verified, e.g., non-coplanar beam configurations.

A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maile, Tobias; Bazjanac, Vladimir; O'Donnell, James

2011-11-01

Building energy performance is often inadequate when compared to design goals. To link design goals to actual operation one can compare measured with simulated energy performance data. Our previously developed comparison approach is the Energy Performance Comparison Methodology (EPCM), which enables the identification of performance problems based on a comparison of measured and simulated performance data. In context of this method, we developed a software tool that provides graphing and data processing capabilities of the two performance data sets. The software tool called SEE IT (Stanford Energy Efficiency Information Tool) eliminates the need for manual generation of data plots andmore » data reformatting. SEE IT makes the generation of time series, scatter and carpet plots independent of the source of data (measured or simulated) and provides a valuable tool for comparing measurements with simulation results. SEE IT also allows assigning data points on a predefined building object hierarchy and supports different versions of simulated performance data. This paper briefly introduces the EPCM, describes the SEE IT tool and illustrates its use in the context of a building case study.« less

Comparison of Indocyanine Green Angiography and Laser Speckle Contrast Imaging for the Assessment of Vasculature Perfusion

PubMed Central

Towle, Erica L.; Richards, Lisa M.; Kazmi, S. M. Shams; Fox, Douglas J.; Dunn, Andrew K.

2013-01-01

BACKGROUND Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI). OBJECTIVE To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion. METHODS An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion. RESULTS The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent. CONCLUSION These 2 methods should be used together to obtain a complete understanding of tissue perfusion. PMID:22843129

Comparison of two surface temperature measurement using thermocouples and infrared camera

NASA Astrophysics Data System (ADS)

Michalski, Dariusz; Strąk, Kinga; Piasecka, Magdalena

This paper compares two methods applied to measure surface temperatures at an experimental setup designed to analyse flow boiling heat transfer. The temperature measurements were performed in two parallel rectangular minichannels, both 1.7 mm deep, 16 mm wide and 180 mm long. The heating element for the fluid flowing in each minichannel was a thin foil made of Haynes-230. The two measurement methods employed to determine the surface temperature of the foil were: the contact method, which involved mounting thermocouples at several points in one minichannel, and the contactless method to study the other minichannel, where the results were provided with an infrared camera. Calculations were necessary to compare the temperature results. Two sets of measurement data obtained for different values of the heat flux were analysed using the basic statistical methods, the method error and the method accuracy. The experimental error and the method accuracy were taken into account. The comparative analysis showed that although the values and distributions of the surface temperatures obtained with the two methods were similar but both methods had certain limitations.

Comparison of methods to estimate water access: a pilot study of a GPS-based approach in low resource settings.

PubMed

Pearson, Amber L

2016-09-20

Most water access studies involve self-reported measures such as time spent or simple spatial measures such as Euclidean distance from home to source. GPS-based measures of access are often considered actual access and have shown little correlation with self-reported measures. One main obstacle to widespread use of GPS-based measurement of access to water has been technological limitations (e.g., battery life). As such, GPS-based measures have been limited by time and in sample size. The aim of this pilot study was to develop and test a novel GPS unit, (≤4-week battery life, waterproof) to measure access to water. The GPS-based method was pilot-tested to estimate number of trips per day, time spent and distance traveled to source for all water collected over a 3-day period in five households in south-western Uganda. This method was then compared to self-reported measures and commonly used spatial measures of access for the same households. Time spent collecting water was significantly overestimated using a self-reported measure, compared to GPS-based (p < 0.05). In contrast, both the GIS Euclidean distances to nearest and actual primary source significantly underestimated distances traveled, compared to the GPS-based measurement of actual travel paths to water source (p < 0.05). Households did not consistently collect water from the source nearest their home. Comparisons between the GPS-based measure and self-reported meters traveled were not made, as respondents did not feel that they could accurately estimate distance. However, there was complete agreement between self-reported primary source and GPS-based. Reliance on cross-sectional self-reported or simple GIS measures leads to misclassification in water access measurement. This new method offers reductions in such errors and may aid in understanding dynamic measures of access to water for health studies.

KEY COMPARISON: Final report on CCEM key comparison CCEM.RF-K10.CL (GT-RF/99-2) 'Power in 50 Ω coaxial lines, frequency: 50 MHz to 26 GHz' measurement techniques and results

NASA Astrophysics Data System (ADS)

Janik, Dieter; Inoue, T.; Michaud, A.

2006-01-01

This report summarizes the results and the measuring methods of an international key comparison between twelve national metrology institutes (NMIs) and is concerning the calibration factor of RF power sensors in the coaxial 3.5 mm line for frequencies up to 26 GHz. Two RF power travelling standards fitted with male PC 3.5 mm connectors were measured at seven frequencies. The following NMIs participated: NMIJ (Japan), NRC (Canada), NIST (USA), METAS (Switzerland), CSIR-NML (South Africa), NMIA (Australia), NPL (UK), SiQ (Slovenia), IEN (Italy), VNIIFTRI (Russian Federation), SPRING (Singapore) and PTB (Germany), as the pilot laboratory. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Comparison of Three Optical Methods for Measuring Model Deformation

NASA Technical Reports Server (NTRS)

Burner, A. W.; Fleming, G. A.; Hoppe, J. C.

2000-01-01

The objective of this paper is to compare the current state-of-the-art of the following three optical techniques under study by NASA for measuring model deformation in wind tunnels: (1) video photogrammetry, (2) projection moire interferometry, and (3) the commercially available Optotrak system. An objective comparison of these three techniques should enable the selection of the best technique for a particular test undertaken at various NASA facilities. As might be expected, no one technique is best for all applications. The techniques are also not necessarily mutually exclusive and in some cases can be complementary to one another.

The mean magnetic field of the sun - Method of observation and relation to the interplanetary magnetic field

NASA Technical Reports Server (NTRS)

Scherrer, P. H.; Wilcox, J. M.; Kotov, V.; Severnyi, A. B.; Howard, R.

1977-01-01

The mean solar magnetic field as measured in integrated light has been observed since 1968. Since 1970 it has been observed both at Hale Observatories and at the Crimean Astrophysical Observatory. The observing procedures at both observatories and their implications for mean field measurements are discussed. A comparison of the two sets of daily observations shows that similar results are obtained at both observatories. A comparison of the mean field with the interplanetary magnetic polarity shows that the IMF sector structure has the same pattern as the mean field polarity.

Modal analysis applied to circular, rectangular, and coaxial waveguides

NASA Technical Reports Server (NTRS)

Hoppe, D. J.

1988-01-01

Recent developments in the analysis of various waveguide components and feedhorns using Modal Analysis (Mode Matching Method) are summarized. A brief description of the theory is presented, and the important features of the method are pointed out. Specific examples in circular, rectangular, and coaxial waveguides are included, with comparisons between the theory and experimental measurements. Extensions to the methods are described.

Quantifying clutter: A comparison of four methods and their relationship to bat detection

Treesearch

Joy M. O’Keefe; Susan C. Loeb; Hoke S. Hill Jr.; J. Drew Lanham

2014-01-01

The degree of spatial complexity in the environment, or clutter, affects the quality of foraging habitats for bats and their detection with acoustic systems. Clutter has been assessed in a variety of ways but there are no standardized methods for measuring clutter. We compared four methods (Visual Clutter, Cluster, Single Variable, and Clutter Index) and related these...

Comparison of Instream and Laboratory Methods of Measuring Sediment Oxygen Demand

USGS Publications Warehouse

Hall, Dennis C.; Berkas, Wayne R.

1988-01-01

Sediment oxygen demand (SOD) was determined at three sites in a gravel-bottomed central Missouri stream by: (1) two variations of an instream method, and (2) a laboratory method. SOD generally was greatest by the instream methods, which are considered more accurate, and least by the laboratory method. Disturbing stream sediment did not significantly decrease SOD by the instream method. Temperature ranges of up to 12 degree Celsius had no significant effect on the SOD. In the gravel-bottomed stream, the placement of chambers was critical to obtain reliable measurements. SOD rates were dependent on the method; therefore, care should be taken in comparing SOD data obtained by different methods. There is a need for a carefully researched standardized method for SOD determinations.

Measuring solids concentration in stormwater runoff: comparison of analytical methods.

PubMed

Clark, Shirley E; Siu, Christina Y S

2008-01-15

Stormwater suspended solids typically are quantified using one of two methods: aliquot/subsample analysis (total suspended solids [TSS]) or whole-sample analysis (suspended solids concentration [SSC]). Interproject comparisons are difficult because of inconsistencies in the methods and in their application. To address this concern, the suspended solids content has been measured using both methodologies in many current projects, but the question remains about how to compare these values with historical water-quality data where the analytical methodology is unknown. This research was undertaken to determine the effect of analytical methodology on the relationship between these two methods of determination of the suspended solids concentration, including the effect of aliquot selection/collection method and of particle size distribution (PSD). The results showed that SSC was best able to represent the known sample concentration and that the results were independent of the sample's PSD. Correlations between the results and the known sample concentration could be established for TSS samples, but they were highly dependent on the sample's PSD and on the aliquot collection technique. These results emphasize the need to report not only the analytical method but also the particle size information on the solids in stormwater runoff.

Estimation of evaporation and sensible heat flux from open water using a large-aperture scintillometer

NASA Astrophysics Data System (ADS)

McJannet, D. L.; Cook, F. J.; McGloin, R. P.; McGowan, H. A.; Burn, S.

2011-05-01

The use of scintillometers to determine sensible and latent heat flux is becoming increasingly common because of their ability to quantify convective fluxes over distances of hundreds of meters to several kilometers. The majority of investigations using scintillometry have focused on processes above land surfaces, but here we propose a new methodology for obtaining sensible and latent heat fluxes from a scintillometer deployed over open water. This methodology has been tested by comparison with eddy covariance measurements and through comparison with alternative scintillometer calculation approaches that are commonly used in the literature. The methodology is based on linearization of the Bowen ratio, which is a common assumption in models such as Penman's model and its derivatives. Comparison of latent heat flux estimates from the eddy covariance system and the scintillometer showed excellent agreement across a range of weather conditions and flux rates, giving a high level of confidence in scintillometry-derived latent heat fluxes. The proposed approach produced better estimates than other scintillometry calculation methods because of the reliance of alternative methods on measurements of water temperature or water body heat storage, which are both notoriously hard to quantify. The proposed methodology requires less instrumentation than alternative scintillometer calculation approaches, and the spatial scales of required measurements are arguably more compatible. In addition to scintillometer measurements of the structure parameter of the refractive index of air, the only measurements required are atmospheric pressure, air temperature, humidity, and wind speed at one height over the water body.

Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets

NASA Astrophysics Data System (ADS)

Barthlott, S.; Schneider, M.; Hase, F.; Wiegele, A.; Christner, E.; González, Y.; Blumenstock, T.; Dohe, S.; García, O. E.; Sepúlveda, E.; Strong, K.; Mendonca, J.; Weaver, D.; Palm, M.; Deutscher, N. M.; Warneke, T.; Notholt, J.; Lejeune, B.; Mahieu, E.; Jones, N.; Griffith, D. W. T.; Velazco, V. A.; Smale, D.; Robinson, J.; Kivi, R.; Heikkinen, P.; Raffalski, U.

2014-10-01

Within the NDACC (Network for the Detection of Atmospheric Composition Change), more than 20 FTIR (Fourier-Transform InfraRed) spectrometers, spread worldwide, provide long-term data records of many atmospheric trace gases. We present a method that uses measured and modelled XCO2 for assessing the consistency of these data records. Our NDACC XCO2 retrieval setup is kept simple so that it can easily be adopted for any NDACC/FTIR-like measurement made since the late 1950s. By a comparison to coincident TCCON (Total Carbon Column Observing Network) measurements, we empirically demonstrate the useful quality of this NDACC XCO2 product (empirically obtained scatter between TCCON and NDACC is about 4‰ for daily mean as well as monthly mean comparisons and the bias is 25‰). As XCO2 model we developed and used a simple regression model fitted to CarbonTracker results and the Mauna Loa CO2 in-situ records. A comparison to TCCON data suggests an uncertainty of the model for monthly mean data of below 3‰. We apply the method to the NDACC/FTIR spectra that are used within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) and demonstrate that there is a good consistency for these globally representative set of spectra measured since 1996: the scatter between the modelled and measured XCO2 on a yearly time scale is only 3‰.

Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets

NASA Astrophysics Data System (ADS)

Barthlott, S.; Schneider, M.; Hase, F.; Wiegele, A.; Christner, E.; González, Y.; Blumenstock, T.; Dohe, S.; García, O. E.; Sepúlveda, E.; Strong, K.; Mendonca, J.; Weaver, D.; Palm, M.; Deutscher, N. M.; Warneke, T.; Notholt, J.; Lejeune, B.; Mahieu, E.; Jones, N.; Griffith, D. W. T.; Velazco, V. A.; Smale, D.; Robinson, J.; Kivi, R.; Heikkinen, P.; Raffalski, U.

2015-03-01

Within the NDACC (Network for the Detection of Atmospheric Composition Change), more than 20 FTIR (Fourier-transform infrared) spectrometers, spread worldwide, provide long-term data records of many atmospheric trace gases. We present a method that uses measured and modelled XCO2 for assessing the consistency of these NDACC data records. Our XCO2 retrieval setup is kept simple so that it can easily be adopted for any NDACC/FTIR-like measurement made since the late 1950s. By a comparison to coincident TCCON (Total Carbon Column Observing Network) measurements, we empirically demonstrate the useful quality of this suggested NDACC XCO2 product (empirically obtained scatter between TCCON and NDACC is about 4‰ for daily mean as well as monthly mean comparisons, and the bias is 25‰). Our XCO2 model is a simple regression model fitted to CarbonTracker results and the Mauna Loa CO2 in situ records. A comparison to TCCON data suggests an uncertainty of the model for monthly mean data of below 3‰. We apply the method to the NDACC/FTIR spectra that are used within the project MUSICA (multi-platform remote sensing of isotopologues for investigating the cycle of atmospheric water) and demonstrate that there is a good consistency for these globally representative set of spectra measured since 1996: the scatter between the modelled and measured XCO2 on a yearly time scale is only 3‰.

3-D surface profilometry based on modulation measurement by applying wavelet transform method

NASA Astrophysics Data System (ADS)

Zhong, Min; Chen, Feng; Xiao, Chao; Wei, Yongchao

2017-01-01

A new analysis of 3-D surface profilometry based on modulation measurement technique by the application of Wavelet Transform method is proposed. As a tool excelling for its multi-resolution and localization in the time and frequency domains, Wavelet Transform method with good localized time-frequency analysis ability and effective de-noizing capacity can extract the modulation distribution more accurately than Fourier Transform method. Especially for the analysis of complex object, more details of the measured object can be well remained. In this paper, the theoretical derivation of Wavelet Transform method that obtains the modulation values from a captured fringe pattern is given. Both computer simulation and elementary experiment are used to show the validity of the proposed method by making a comparison with the results of Fourier Transform method. The results show that the Wavelet Transform method has a better performance than the Fourier Transform method in modulation values retrieval.

TROPHI: development of a tool to measure complex, multi-factorial patient handling interventions.

PubMed

Fray, Mike; Hignett, Sue

2013-01-01

Patient handling interventions are complex and multi-factorial. It has been difficult to make comparisons across different strategies due to the lack of a comprehensive outcome measurement method. The Tool for Risk Outstanding in Patient Handling Interventions (TROPHI) was developed to address this gap by measuring outcomes and comparing performance across interventions. Focus groups were held with expert patient handling practitioners (n = 36) in four European countries (Finland, Italy, Portugal and the UK) to identify preferred outcomes to be measured for interventions. A systematic literature review identified 598 outcome measures; these were critically appraised and the most appropriate measurement tool was selected for each outcome. TROPHI was evaluated in the four EU countries (eight sites) and by an expert panel (n = 16) from the European Panel of Patient Handling Ergonomics for usability and practical application. This final stage added external validity to the research by exploring transferability potential and presenting the data and analysis to allow respondent (participant) validation. Patient handling interventions are complex and multi-factorial and it has been difficult to make comparisons due to the lack of a comprehensive outcome measurement method. The Tool for Risk Outstanding in Patient Handling Interventions (TROPHI) was developed to address this gap by measuring outcomes to compare performance across interventions.

K2 and K2*: efficient alignment-free sequence similarity measurement based on Kendall statistics.

PubMed

Lin, Jie; Adjeroh, Donald A; Jiang, Bing-Hua; Jiang, Yue

2018-05-15

Alignment-free sequence comparison methods can compute the pairwise similarity between a huge number of sequences much faster than sequence-alignment based methods. We propose a new non-parametric alignment-free sequence comparison method, called K2, based on the Kendall statistics. Comparing to the other state-of-the-art alignment-free comparison methods, K2 demonstrates competitive performance in generating the phylogenetic tree, in evaluating functionally related regulatory sequences, and in computing the edit distance (similarity/dissimilarity) between sequences. Furthermore, the K2 approach is much faster than the other methods. An improved method, K2*, is also proposed, which is able to determine the appropriate algorithmic parameter (length) automatically, without first considering different values. Comparative analysis with the state-of-the-art alignment-free sequence similarity methods demonstrates the superiority of the proposed approaches, especially with increasing sequence length, or increasing dataset sizes. The K2 and K2* approaches are implemented in the R language as a package and is freely available for open access (http://community.wvu.edu/daadjeroh/projects/K2/K2_1.0.tar.gz). yueljiang@163.com. Supplementary data are available at Bioinformatics online.

Final report on EURAMET.QM-S6/1195: Bilateral comparison of liquefied hydrocarbon mixtures in constant pressure (piston) cylinders

NASA Astrophysics Data System (ADS)

Brown, Andrew S.; Downey, Michael L.; Milton, Martin J. T.; van der Veen, Adriaan M. H.; Zalewska, Ewelina T.; Li, Jianrong

2013-01-01

Traceable liquid hydrocarbon mixtures are required in order to underpin measurements of the composition and other physical properties of LPG (liquefied petroleum gas) and LNG (liquefied natural gas), thus meeting the needs of an increasingly large European industrial market. The development of traceable liquid hydrocarbon standards by National Measurement Institutes (NMIs) was still at a relatively early stage at the time this comparison was proposed in 2011. NPL and VSL, who were the only NMIs active in this area, had developed methods for the preparation and analysis of such standards in constant pressure (piston) cylinders, but neither laboratory had Calibration and Measurement Capabilities (CMCs) for these mixtures. This report presents the results of EURAMET 1195, the first comparison of liquid hydrocarbon mixtures between NMIs, which assessed the preparation and analytical capabilities of NPL and VSL for these mixtures. The comparison operated between August 2011 and January 2012. Each laboratory prepared a liquid hydrocarbon standard with nominally the same composition and these standards were exchanged for analysis. The results of the comparison show a good agreement between the laboratories' results and the comparison reference values for the six components with amount fractions greater than 1.0 cmol/mol (propane, propene, iso-butene, n-butane, iso-butane and 1-butene). Measurement of the three components with lower amount fractions (1,3-butadiene, iso-pentane and n-pentane) proved more challenging. In all but one case, the differences from the comparison reference values for these three components were greater than the expanded measurement uncertainty. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

A comparison of food crispness based on the cloud model.

PubMed

Wang, Minghui; Sun, Yonghai; Hou, Jumin; Wang, Xia; Bai, Xue; Wu, Chunhui; Yu, Libo; Yang, Jie

2018-02-01

The cloud model is a typical model which transforms the qualitative concept into the quantitative description. The cloud model has been used less extensively in texture studies before. The purpose of this study was to apply the cloud model in food crispness comparison. The acoustic signals of carrots, white radishes, potatoes, Fuji apples, and crystal pears were recorded during compression. And three time-domain signal characteristics were extracted, including sound intensity, maximum short-time frame energy, and waveform index. The three signal characteristics and the cloud model were used to compare the crispness of the samples mentioned above. The crispness based on the Ex value of the cloud model, in a descending order, was carrot > potato > white radish > Fuji apple > crystal pear. To verify the results of the acoustic signals, mechanical measurement and sensory evaluation were conducted. The results of the two verification experiments confirmed the feasibility of the cloud model. The microstructures of the five samples were also analyzed. The microstructure parameters were negatively related with crispness (p < .01). The cloud model method can be used for crispness comparison of different kinds of foods. The method is more accurate than the traditional methods such as mechanical measurement and sensory evaluation. The cloud model method can also be applied to other texture studies extensively. © 2017 Wiley Periodicals, Inc.

Diffuse sunlight based calibration of the water vapor channel in the upc raman lidar

NASA Astrophysics Data System (ADS)

Muñoz-Porcar, Constantino; Comeron, Adolfo; Sicard, Michaël; Barragan, Ruben; Garcia-Vizcaino, David; Rodríguez-Gómez, Alejandro; Rocadenbosch, Francesc

2018-04-01

A method for determining the calibration factor of the water vapor channel of a Raman lidar, based on zenith measurements of diffuse sunlight and on assumptions regarding some system parameters and Raman scattering models, has been applied to the lidar system of Universitat Politècnica de Catalunya (UPC; Technical University of Catalonia, Spain). Results will be analyzed in terms of stability and comparison with typical methods relying on simultaneous radiosonde measurements.

Comparison of global positioning and computer-based tracking systems for measuring player movement distance during Australian football.

PubMed

Edgecomb, S J; Norton, K I

2006-05-01

Sports scientists require a thorough understanding of the energy demands of sports and physical activities so that optimal training strategies and game simulations can be constructed. A range of techniques has been used to both directly assess and estimate the physiological and biochemical changes during competition. A fundamental approach to understanding the contribution of the energy systems in physical activity has involved the use of time-motion studies. A number of tools have been used from simple pen and paper methods, the use of video recordings, to sophisticated electronic tracking devices. Depending on the sport, there may be difficulties in using electronic tracking devices because of concerns of player safety. This paper assesses two methods currently used to measure player movement patterns during competition: (1) global positioning technology (GPS) and (2) a computer-based tracking (CBT) system that relies on a calibrated miniaturised playing field and mechanical movements of the tracker. A range of ways was used to determine the validity and reliability of these methods for tracking Australian footballers for distance covered during games. Comparisons were also made between these methods. The results indicate distances measured using CBT overestimated the actual values (measured with a calibrated trundle wheel) by an average of about 5.8%. The GPS system overestimated the actual values by about 4.8%. Distances measured using CBT in experienced hands were as accurate as the GPS technology. Both systems showed relatively small errors in true distances.

Assessing Lower Limb Alignment: Comparison of Standard Knee Xray vs Long Leg View.

PubMed

Zampogna, Biagio; Vasta, Sebastiano; Amendola, Annunziato; Uribe-Echevarria Marbach, Bastian; Gao, Yubo; Papalia, Rocco; Denaro, Vincenzo

2015-01-01

High tibial osteotomy (HTO) is a well-established and commonly utilized technique in medial knee osteoarthritis secondary to varus malalignment. Accurate measurement of the preoperative limb alignment, and the amount of correction required are essential when planning limb realignment surgery. The hip-knee-ankle angle (HKA) measured on a full length weightbearing (FLWB) X-ray in the standing position is considered the gold standard, since it allows for reliable and accurate measurement of the mechanical axis of the whole lower extremity. In general practice, alignment is often evaluated on standard anteroposterior weightbearing (APWB) X-rays, as the angle between the femur and tibial anatomic axis (TFa). It is, therefore, of value to establish if measuring the anatomical axis from limited APWB is an effective measure of knee alignment especially in patients undergoing osteotomy about the knee. Three independent observers measured preoperative and postoperative FTa with standard method (FTa1) and with circles method (FTa2) on APWB X-ray and the HKA on FLWB X-ray at three different time-points separated by a two-week period. Intra-observer and inter-observer reliabilities and the comparison and relationship between anatomical and mechanical alignment were calculated. Intra- and interclass coefficients for all the three methods indicated excellent reliability, having all the values above 0.80. Using the mean of paired t-student test, the comparison of HKA versus TFa1 and TFa2 showed a statistically significant difference (p<.0001) both for the pre-operative and post-operative sets of values. The correlation between the HKA and FTal was found poor for the preoperative set (R=0.26) and fair for the postoperative one (R=0.53), while the new circles method showed a higher correlation in both the preoperative (R=0.71) and postoperative sets (R=0.79). Intra-observer reliability was high for HKA, FTal and FTa2 on APWB x-rays in the pre- and post-operative setting. Inter-rater reliability was higher for HKA and TFa2 compared to FTal. The femoro-tibial angle as measured on APWB with the traditional method (FTal) has a weak correlation with the HKA, and based on these findings, should not be used in everyday practice. The FTa2 showed better correlation with the HKA, although not excellent. Level III, Retrospective study.

Chemical Shift MR Imaging Methods for the Quantification of Transcatheter Lipiodol Delivery to the Liver: Preclinical Feasibility Studies in a Rodent Model

PubMed Central

Yin, Xiaoming; Guo, Yang; Li, Weiguo; Huo, Eugene; Zhang, Zhuoli; Nicolai, Jodi; Kleps, Robert A.; Hernando, Diego; Katsaggelos, Aggelos K.; Omary, Reed A.

2012-01-01

Purpose: To demonstrate the feasibility of using chemical shift magnetic resonance (MR) imaging fat-water separation methods for quantitative estimation of transcatheter lipiodol delivery to liver tissues. Materials and Methods: Studies were performed in accordance with institutional Animal Care and Use Committee guidelines. Proton nuclear MR spectroscopy was first performed to identify lipiodol spectral peaks and relative amplitudes. Next, phantoms were constructed with increasing lipiodol-water volume fractions. A multiecho chemical shift–based fat-water separation method was used to quantify lipiodol concentration within each phantom. Six rats served as controls; 18 rats underwent catheterization with digital subtraction angiography guidance for intraportal infusion of a 15%, 30%, or 50% by volume lipiodol-saline mixture. MR imaging measurements were used to quantify lipiodol delivery to each rat liver. Lipiodol concentration maps were reconstructed by using both single-peak and multipeak chemical shift models. Intraclass and Spearman correlation coefficients were calculated for statistical comparison of MR imaging–based lipiodol concentration and volume measurements to reference standards (known lipiodol phantom compositions and the infused lipiodol dose during rat studies). Results: Both single-peak and multipeak measurements were well correlated to phantom lipiodol concentrations (r2 > 0.99). Lipiodol volume measurements were progressively and significantly higher when comparing between animals receiving different doses (P < .05 for each comparison). MR imaging–based lipiodol volume measurements strongly correlated with infused dose (intraclass correlation coefficients > 0.93, P < .001) with both single- and multipeak approaches. Conclusion: Chemical shift MR imaging fat-water separation methods can be used for quantitative measurements of lipiodol delivery to liver tissues. © RSNA, 2012 PMID:22623693

Measurement equivalence and differential item functioning in family psychology.

PubMed

Bingenheimer, Jeffrey B; Raudenbush, Stephen W; Leventhal, Tama; Brooks-Gunn, Jeanne

2005-09-01

Several hypotheses in family psychology involve comparisons of sociocultural groups. Yet the potential for cross-cultural inequivalence in widely used psychological measurement instruments threatens the validity of inferences about group differences. Methods for dealing with these issues have been developed via the framework of item response theory. These methods deal with an important type of measurement inequivalence, called differential item functioning (DIF). The authors introduce DIF analytic methods, linking them to a well-established framework for conceptualizing cross-cultural measurement equivalence in psychology (C.H. Hui and H.C. Triandis, 1985). They illustrate the use of DIF methods using data from the Project on Human Development in Chicago Neighborhoods (PHDCN). Focusing on the Caregiver Warmth and Environmental Organization scales from the PHDCN's adaptation of the Home Observation for Measurement of the Environment Inventory, the authors obtain results that exemplify the range of outcomes that may result when these methods are applied to psychological measurement instruments. (c) 2005 APA, all rights reserved

A Comparison of Three Different Scoring Methods for Self-Report Measures of Psychological Aggression in a Sample of College Females

PubMed Central

Shorey, Ryan C.; Brasfield, Hope; Febres, Jeniimarie; Cornelius, Tara L.; Stuart, Gregory L.

2012-01-01

Psychological aggression in females’ dating relationships has received increased empirical attention in recent years. However, researchers have used numerous measures of psychological aggression, and various scoring methods with these measures, making it difficult to compare across studies on psychological aggression. In addition, research has yet to examine whether different scoring methods for psychological aggression measures may affect the psychometric properties of these instruments. The current study examined three self-report measures of psychological aggression within a sample of female college students (N = 108), including their psychometric properties when scored using frequency, sum, and variety scores. Results showed that the Revised Conflict Tactics Scales (CTS2) had variable internal consistency depending on the scoring method used and good validity; the Multidimensional Measure of Emotional Abuse (MMEA) and the Follingstad Psychological Aggression Scale (FPAS) both had good internal consistency and validity across scoring methods. Implications of these findings for the assessment of psychological aggression and future research are discussed. PMID:23393957

A comparison of three different scoring methods for self-report measures of psychological aggression in a sample of college females.

PubMed

Shorey, Ryan C; Brasfield, Hope; Febres, Jeniimarie; Cornelius, Tara L; Stuart, Gregory L

2012-01-01

Psychological aggression in females' dating relationships has received increased empirical attention in recent years. However, researchers' have used numerous measures of psychological aggression and various scoring methods with these measures, making it difficult to compare across studies on psychological aggression. In addition, research has yet to examine whether different scoring methods for psychological aggression measures may affect the psychometric properties of these instruments. This study examined three self-report measures of psychological aggression within a sample of female college students (N = 108), including their psychometric properties when scored using frequency, sum, and variety scores. Results showed that the Revised Conflict Tactics Scales (CTS2) had variable internal consistency depending on the scoring method used and good validity; the Multidimensional Measure of Emotional Abuse (MMEA) and the Follingstad Psychological Aggression Scale (FPAS) both had good internal consistency and validity across scoring methods. Implications of these findings for the assessment of psychological aggression and future research are discussed.

Comparison of Measured and Calculated Stresses in Built-up Beams

NASA Technical Reports Server (NTRS)

Levin, L Ross; Nelson, David H

1946-01-01

Web stresses and flange stresses were measured in three built-up beams: one of constant depth with flanges of constant cross-section, one linearly tapered in depth with flanges of constant cross section, and one linearly tapered in depth with tapered flanges. The measured stresses were compared with the calculated stresses obtained by the methods outlined in order to determine the degree of accuracy that may be expected from the stress analysis formulas. These comparisons indicated that the average measured stresses for all points in the central section of the beams did not exceed the average calculated stresses by more than 5 percent. It also indicated that the difference between average measured flange stresses and average calculated flange stresses on the net area and a fully effective web did not exceed 6.1 percent.

Method for in situ carbon deposition measurement for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Kuhn, J.; Kesler, O.

2014-01-01

Previous methods to measure carbon deposition in solid oxide fuel cell (SOFC) anodes do not permit simultaneous electrochemical measurements. Electrochemical measurements supplemented with carbon deposition quantities create the opportunity to further understand how carbon affects SOFC performance and electrochemical impedance spectra (EIS). In this work, a method for measuring carbon in situ, named here as the quantification of gasified carbon (QGC), was developed. TGA experiments showed that carbon with a 100 h residence time in the SOFC was >99.8% gasified. Comparison of carbon mass measurements between the TGA and QGC show good agreement. In situ measurements of carbon deposition in SOFCs at varying molar steam/carbon ratios were performed to further validate the QGC method, and suppression of carbon deposition with increasing steam concentration was observed, in agreement with previous studies. The technique can be used to investigate in situ carbon deposition and gasification behavior simultaneously with electrochemical measurements for a variety of fuels and operating conditions, such as determining conditions under which incipient carbon deposition is reversible.

Body fatness or anthropometry for assessment of unhealthy weight status? Comparison between methods in South African children and adolescents.

PubMed

Craig, Eva; Reilly, John; Bland, Ruth

2013-11-01

A variety of methods are available for defining undernutrition (thinness/underweight/under-fat) and overnutrition (overweight/obesity/over-fat). The extent to which these definitions agree is unclear. The present cross-sectional study aimed to assess agreement between widely used methods of assessing nutritional status in children and adolescents, and to examine the benefit of body composition estimates. The main objective of the cross-sectional study was to assess underweight, overweight and obesity using four methods: (i) BMI-for-age using WHO (2007) reference data; (ii) BMI-for-age using Cole et al. and International Obesity Taskforce cut-offs; (iii) weight-for-age using the National Centre for Health Statistics/WHO growth reference 1977; and (iv) body fat percentage estimated by bio-impedance (body fat reference curves for children of McCarthy et al., 2006). Comparisons were made between methods using weighted kappa analyses. Rural South Africa. Individuals (n 1519) in three age groups (school grade 1, mean age 7 years; grade 5, mean age 11 years; grade 9, mean age 15 years). In boys, prevalence of unhealthy weight status (both under- and overnutrition) was much higher at all ages with body fatness measures than with simple anthropometric proxies for body fatness; agreement between fatness and weight-based measures was fair or slight using Landis and Koch categories. In girls, prevalence of unhealthy weight status was also higher with body fatness than with proxies, although agreement between measures ranged from fair to substantial. Methods for defining under- and overnutrition should not be considered equivalent. Weight-based measures provide highly conservative estimates of unhealthy weight status, possibly more conservative in boys. Simple body composition measures may be more informative than anthropometry for nutritional surveillance of children and adolescents.

Comparison of three noninvasive methods for hemoglobin screening of blood donors.

PubMed

Ardin, Sergey; Störmer, Melanie; Radojska, Stela; Oustianskaia, Larissa; Hahn, Moritz; Gathof, Birgit S

2015-02-01

To prevent phlebotomy of anemic individuals and to ensure hemoglobin (Hb) content of the blood units, Hb screening of blood donors before donation is essential. Hb values are mostly evaluated by measurement of capillary blood obtained from fingerstick. Rapid noninvasive methods have recently become available and may be preferred by donors and staff. The aim of this study was to evaluate for the first time all different noninvasive methods for Hb screening. Blood donors were screened for Hb levels in three different trials using three different noninvasive methods (Haemospect [MBR Optical Systems GmbH & Co. KG], NBM 200 [LMB Technology GmbH], Pronto-7 [Masimo Europe Ltd]) in comparison to the established fingerstick method (CompoLab Hb [Fresenius Kabi GmbH]) and to levels obtained from venous samples on a cell counter (Sysmex [Sysmex Europe GmbH]) as reference. The usability of the noninvasive methods was assessed with an especially developed survey. Technical failures occurred by using the Pronto-7 due to nail polish, skin color, or ambient light. The NBM 200 also showed a high sensitivity to ambient light and noticeably lower Hb levels for women than obtained from the Sysmex. The statistical analysis showed the following bias and standard deviation of differences of all methods in comparison to the venous results: Haemospect, -0.22 ± 1.24; NBM, 200 -0.12 ± 1.14; Pronto-7, -0.50 ± 0.99; and CompoLab Hb, -0.53 ± 0.81. Noninvasive Hb tests represent an attractive alternative by eliminating pain and reducing risks of blood contamination. The main problem for generating reliable results seems to be preanalytical variability in sampling. Despite the sensitivity to environmental stress, all methods are suitable for Hb measurement. © 2014 AABB.

Assessment of opacimeter calibration according to International Standard Organization 10155.

PubMed

Gomes, J F

2001-01-01

This paper compares the calibration method for opacimeters issued by the International Standard Organization (ISO) 10155 with the manual reference method for determination of dust content in stack gases. ISO 10155 requires at least nine operational measurements, corresponding to three operational measurements per each dust emission range within the stack. The procedure is assessed by comparison with previous calibration methods for opacimeters using only two operational measurements from a set of measurements made at stacks from pulp mills. The results show that even if the international standard for opacimeter calibration requires that the calibration curve is to be obtained using 3 x 3 points, a calibration curve derived using 3 points could be, at times, acceptable in statistical terms, provided that the amplitude of individual measurements is low.

A scoring metric for multivariate data for reproducibility analysis using chemometric methods

PubMed Central

Sheen, David A.; de Carvalho Rocha, Werickson Fortunato; Lippa, Katrice A.; Bearden, Daniel W.

2017-01-01

Process quality control and reproducibility in emerging measurement fields such as metabolomics is normally assured by interlaboratory comparison testing. As a part of this testing process, spectral features from a spectroscopic method such as nuclear magnetic resonance (NMR) spectroscopy are attributed to particular analytes within a mixture, and it is the metabolite concentrations that are returned for comparison between laboratories. However, data quality may also be assessed directly by using binned spectral data before the time-consuming identification and quantification. Use of the binned spectra has some advantages, including preserving information about trace constituents and enabling identification of process difficulties. In this paper, we demonstrate the use of binned NMR spectra to conduct a detailed interlaboratory comparison and composition analysis. Spectra of synthetic and biologically-obtained metabolite mixtures, taken from a previous interlaboratory study, are compared with cluster analysis using a variety of distance and entropy metrics. The individual measurements are then evaluated based on where they fall within their clusters, and a laboratory-level scoring metric is developed, which provides an assessment of each laboratory’s individual performance. PMID:28694553

Comparison of different methods for the in situ measurement of forest litter moisture content

NASA Astrophysics Data System (ADS)

Schunk, C.; Ruth, B.; Leuchner, M.; Wastl, C.; Menzel, A.

2015-06-01

Dead fine fuel (e.g. litter) moisture content is an important parameter for both forest fire and ecological applications as it is related to ignitability, fire behavior as well as soil respiration. However, the comprehensive literature review in this paper shows that there is no easy-to-use method for automated measurements available. This study investigates the applicability of four different sensor types (permittivity and electrical resistance measuring principles) for this measurement. Comparisons were made to manual gravimetric reference measurements carried out almost daily for one fire season and overall agreement was good (highly significant correlations with 0.792 ≦ r ≦ 0.947). Standard deviations within sensor types were linearly correlated to daily sensor mean values; however, above a certain threshold they became irregular, which may be linked to exceedance of the working ranges. Thus, measurements with irregular standard deviations were considered unusable and calibrations of all individual sensors were compared for useable periods. A large drift in the sensor raw value-litter moisture-relationship became obvious from drought to drought period. This drift may be related to installation effects or settling and decomposition of the litter layer throughout the fire season. Because of the drift and the in situ calibration necessary, it cannot be recommended to use the methods presented here for monitoring purposes. However, they may be interesting for scientific studies when some manual fuel moisture measurements are made anyway. Additionally, a number of potential methodological improvements are suggested.

Application of the Refined Integral Method in the mathematical modeling of drug delivery from one-layer torus-shaped devices.

PubMed

Helbling, Ignacio M; Ibarra, Juan C D; Luna, Julio A

2012-02-28

A mathematical modeling of controlled release of drug from one-layer torus-shaped devices is presented. Analytical solutions based on Refined Integral Method (RIM) are derived. The validity and utility of the model are ascertained by comparison of the simulation results with matrix-type vaginal rings experimental release data reported in the literature. For the comparisons, the pair-wise procedure is used to measure quantitatively the fit of the theoretical predictions to the experimental data. A good agreement between the model prediction and the experimental data is observed. A comparison with a previously reported model is also presented. More accurate results are achieved for small A/C(s) ratios. Copyright © 2011 Elsevier B.V. All rights reserved.

Role and Evaluation of Interlaboratory Comparison Results in Laboratory Accreditation

NASA Astrophysics Data System (ADS)

Bode, P.

2008-08-01

Participation in interlaboratory comparisons provides laboratories an opportunity for independent assessment of their analytical performance, both in absolute way and in comparison with those by other techniques. However, such comparisons are hindered by differences in the way laboratories participate, e.g. at best measurement capability or under routine conditions. Neutron activation analysis laboratories, determining total mass fractions, often see themselves classified as `outliers' since the majority of other participants employ techniques with incomplete digestion methods. These considerations are discussed in relation to the way results from interlaboratory comparisons are evaluated by accreditation bodies following the requirements of Clause 5.9.1 of the ISO/IEC 17025:2005. The discussion and conclusions come largely forth from experiences in the author's own laboratory.

QUEST+: A general multidimensional Bayesian adaptive psychometric method.

PubMed

Watson, Andrew B

2017-03-01

QUEST+ is a Bayesian adaptive psychometric testing method that allows an arbitrary number of stimulus dimensions, psychometric function parameters, and trial outcomes. It is a generalization and extension of the original QUEST procedure and incorporates many subsequent developments in the area of parametric adaptive testing. With a single procedure, it is possible to implement a wide variety of experimental designs, including conventional threshold measurement; measurement of psychometric function parameters, such as slope and lapse; estimation of the contrast sensitivity function; measurement of increment threshold functions; measurement of noise-masking functions; Thurstone scale estimation using pair comparisons; and categorical ratings on linear and circular stimulus dimensions. QUEST+ provides a general method to accelerate data collection in many areas of cognitive and perceptual science.

Development of a histologically validated segmentation protocol for the hippocampal body.

PubMed

Steve, Trevor A; Yasuda, Clarissa L; Coras, Roland; Lail, Mohjevan; Blumcke, Ingmar; Livy, Daniel J; Malykhin, Nikolai; Gross, Donald W

2017-08-15

Recent findings have demonstrated that hippocampal subfields can be selectively affected in different disease states, which has led to efforts to segment the human hippocampus with in vivo magnetic resonance imaging (MRI). However, no studies have examined the histological accuracy of subfield segmentation protocols. The presence of MRI-visible anatomical landmarks with known correspondence to histology represents a fundamental prerequisite for in vivo hippocampal subfield segmentation. In the present study, we aimed to: 1) develop a novel method for hippocampal body segmentation, based on two MRI-visible anatomical landmarks (stratum lacunosum moleculare [SLM] & dentate gyrus [DG]), and assess its accuracy in comparison to the gold standard direct histological measurements; 2) quantify the accuracy of two published segmentation strategies in comparison to the histological gold standard; and 3) apply the novel method to ex vivo MRI and correlate the results with histology. Ultra-high resolution ex vivo MRI was performed on six whole cadaveric hippocampal specimens, which were then divided into 22 blocks and histologically processed. The hippocampal bodies were segmented into subfields based on histological criteria and subfield boundaries and areas were directly measured. A novel method was developed using mean percentage of the total SLM distance to define subfield boundaries. Boundary distances and subfield areas on histology were then determined using the novel method and compared to the gold standard histological measurements. The novel method was then used to determine ex vivo MRI measures of subfield boundaries and areas, which were compared to histological measurements. For direct histological measurements, the mean percentages of total SLM distance were: Subiculum/CA1 = 9.7%, CA1/CA2 = 78.4%, CA2/CA3 = 97.5%. When applied to histology, the novel method provided accurate measures for CA1/CA2 (ICC = 0.93) and CA2/CA3 (ICC = 0.97) boundaries, but not for the Subiculum/CA1 (ICC = -0.04) boundary. Accuracy was poorer using previous techniques for CA1/CA2 (maximum ICC = 0.85) and CA2/CA3 (maximum ICC = 0.88), with the previously reported techniques also performing poorly in defining the Subiculum/CA1 boundary (maximum ICC = 0.00). Ex vivo MRI measurements using the novel method were linearly related to direct measurements of SLM length (r 2 = 0.58), CA1/CA2 boundary (r 2 = 0.39) and CA2/CA3 boundary (r 2 = 0.47), but not for Subiculum/CA1 boundary (r 2 = 0.01). Subfield areas measured with the novel method on histology and ex vivo MRI were linearly related to gold standard histological measures for CA1, CA2, and CA3/CA4/DG. In this initial proof of concept study, we used ex vivo MRI and histology of cadaveric hippocampi to develop a novel segmentation protocol for the hippocampal body. The novel method utilized two anatomical landmarks, SLM & DG, and provided accurate measurements of CA1, CA2, and CA3/CA4/DG subfields in comparison to the gold standard histological measurements. The relationships demonstrated between histology and ex vivo MRI supports the potential feasibility of applying this method to in vivo MRI studies. Copyright © 2017. Published by Elsevier Inc.

Comparison of Two Procedures for Analyzing Small Sets of Repeated Measures Data

ERIC Educational Resources Information Center

Vallejo, Guillermo; Livacic-Rojas, Pablo

2005-01-01

This article compares two methods for analyzing small sets of repeated measures data under normal and non-normal heteroscedastic conditions: a mixed model approach with the Kenward-Roger correction and a multivariate extension of the modified Brown-Forsythe (BF) test. These procedures differ in their assumptions about the covariance structure of…

Measuring Individual Research Productivity: A Review and Development of the Integrated Research Productivity Index

ERIC Educational Resources Information Center

Duffy, Ryan D.; Martin, Helena M.; Bryan, Nicole A.; Raque-Bogdan, Trisha L.

2008-01-01

The purpose of the present study was to investigate methods of measuring individual research productivity for counseling psychologists. Using the 60 members of the "Journal of Counseling Psychology" editorial board, the authors computed a comparison of 6 popular indices of productivity, revealing considerable levels of positive skewness,…

Inter-Method Reliability of School Effectiveness Measures: A Comparison of Value-Added and Regression Discontinuity Estimates

ERIC Educational Resources Information Center

Perry, Thomas

2017-01-01

Value-added (VA) measures are currently the predominant approach used to compare the effectiveness of schools. Recent educational effectiveness research, however, has developed alternative approaches including the regression discontinuity (RD) design, which also allows estimation of absolute school effects. Initial research suggests RD is a viable…

COMPARISON OF PRESSURIZED LIQUID EXTRACTION AND MATRIX SOLID PHASE DISPERSION FOR THE MEASUREMENT OF SEMI-VOLATILE ORGANIC COMPOUND ACCUMULATION IN TADPOLES

EPA Science Inventory

Analytical methods capable of trace measurement of semi-volatile organic compounds (SOCs) are necessary to assess the exposure of tadpoles to contaminants as a result of long-range and regional atmospheric transport and deposition. The following study compares the results of two ...

Measuring Safety Performance: A Comparison of Whole, Partial, and Momentary Time-Sampling Recording Methods

ERIC Educational Resources Information Center

Alvero, Alicia M.; Struss, Kristen; Rappaport, Eva

2008-01-01

Partial-interval (PIR), whole-interval (WIR), and momentary time sampling (MTS) estimates were compared against continuous measures of safety performance for three postural behaviors: feet, back, and shoulder position. Twenty-five samples of safety performance across five undergraduate students were scored using a second-by-second continuous…

Changes in Swallowing after Anterior Cervical Discectomy and Fusion with Instrumentation: A Presurgical versus Postsurgical Videofluoroscopic Comparison

ERIC Educational Resources Information Center

Muss, Lydia; Wilmskoetter, Janina; Richter, Kerstin; Fix, Constanze; Stanschus, Soenke; Pitzen, Tobias; Drumm, Joerg; Molfenter, Sonja

2017-01-01

Purpose: The purpose of this study was to explore the impact of anterior cervical discectomy and fusion (ACDF) with anterior instrumentation on swallowing function and physiology as measured on videofluoroscopic swallowing studies. Method: We retrospectively analyzed both functional measures (penetration-aspiration, residue) and…

A Comparison of Four Approaches to Account for Method Effects in Latent State-Trait Analyses

ERIC Educational Resources Information Center

Geiser, Christian; Lockhart, Ginger

2012-01-01

Latent state-trait (LST) analysis is frequently applied in psychological research to determine the degree to which observed scores reflect stable person-specific effects, effects of situations and/or person-situation interactions, and random measurement error. Most LST applications use multiple repeatedly measured observed variables as indicators…

Comparison between the basic least squares and the Bayesian approach for elastic constants identification

NASA Astrophysics Data System (ADS)

Gogu, C.; Haftka, R.; LeRiche, R.; Molimard, J.; Vautrin, A.; Sankar, B.

2008-11-01

The basic formulation of the least squares method, based on the L2 norm of the misfit, is still widely used today for identifying elastic material properties from experimental data. An alternative statistical approach is the Bayesian method. We seek here situations with significant difference between the material properties found by the two methods. For a simple three bar truss example we illustrate three such situations in which the Bayesian approach leads to more accurate results: different magnitude of the measurements, different uncertainty in the measurements and correlation among measurements. When all three effects add up, the Bayesian approach can have a large advantage. We then compared the two methods for identification of elastic constants from plate vibration natural frequencies.

A comparison between Warner-Bratzler shear force measurement and texture profile analysis of meat and meat products: a review

NASA Astrophysics Data System (ADS)

Novaković, S.; Tomašević, I.

2017-09-01

Texture is one of the most important characteristics of meat and we can explain it as the human physiological-psychological awareness of a number of rheological and other properties of foods and their relations. In this paper, we discuss instrumental measurement of texture by Warner-Bratzler shear force (WBSF) and texture profile analysis (TPA). The conditions for using the device are detailed in WBSF measurements, and the influence of different parameters on the execution of the method and final results are shown. After that, the main disadvantages are reflected in the non-standardized method. Also, we introduce basic texture parameters which connect and separate TPA and WBSF methods and mention contemporary methods with their main advantage.

Radar prediction of absolute rain fade distributions for earth-satellite paths and general methods for extrapolation of fade statistics to other locations

NASA Technical Reports Server (NTRS)

Goldhirsh, J.

1982-01-01

The first absolute rain fade distribution method described establishes absolute fade statistics at a given site by means of a sampled radar data base. The second method extrapolates absolute fade statistics from one location to another, given simultaneously measured fade and rain rate statistics at the former. Both methods employ similar conditional fade statistic concepts and long term rain rate distributions. Probability deviations in the 2-19% range, with an 11% average, were obtained upon comparison of measured and predicted levels at given attenuations. The extrapolation of fade distributions to other locations at 28 GHz showed very good agreement with measured data at three sites located in the continental temperate region.

In vivo measurements of skin barrier: comparison of different methods and advantages of laser scanning microscopy

NASA Astrophysics Data System (ADS)

Patzelt, A.; Sterry, W.; Lademann, J.

2010-12-01

A major function of the skin is to provide a protective barrier at the interface between external environment and the organism. For skin barrier measurement, a multiplicity of methods is available. As standard methods, the determination of the transepidermal water loss (TEWL) as well as the measurement of the stratum corneum hydration, are widely accepted, although they offer some obvious disadvantages such as increased interference liability. Recently, new optical and spectroscopic methods have been introduced to investigate skin barrier properties in vivo. Especially, laser scanning microscopy has been shown to represent an excellent tool to study skin barrier integrity in many areas of relevance such as cosmetology, occupation, diseased skin, and wound healing.

A physical retrieval of cloud liquid water over the global oceans using special sensor microwave/imager (SSM/I) observations

NASA Astrophysics Data System (ADS)

Greenwald, Thomas J.; Stephens, Graeme L.; Vonder Haar, Thomas H.; Jackson, Darren L.

1993-10-01

A method of remotely sensing integrated cloud liquid water over the oceans using spaceborne passive measurements from the special sensor microwave/imager (SSM/I) is described. The technique is comprised of a simple physical model that uses the 19.35- and 37-GHz channels of the SSM/I. The most comprehensive validation to date of cloud liquid water estimated from satellites is presented. This is accomplished through a comparison to independent ground-based microwave radiometer measurements of liquid water on San Nicolas Island, over the North Sea, and on Kwajalein and Saipan Islands in the western Pacific. In areas of marine stratocumulus clouds off the coast of California a further comparison is made to liquid water inferred from advanced very high resolution radiometer (AVHRR) visible reflectance measurements. The results are also compared qualitatively with near-coincident satellite imagery and with other existing microwave methods in selected regions. These comparisons indicate that the liquid water amounts derived from the simple scheme are consistent with the ground-based measurements for nonprecipitating cloud systems in the subtropics and middle to high latitudes. The comparison in the tropics, however, was less conclusive. Nevertheless, the retrieval method appears to have general applicability over most areas of the global oceans. An observational measure of the minimum uncertainty in the retrievals is determined in a limited number of known cloud-free areas, where the liquid water amounts are found to have a low variability of 0.016 kg m-2. A simple sensitivity and error analysis suggests that the liquid water estimates have a theoretical relative error typically ranging from about 25% to near 40% depending on the atmospheric/surface conditions and on the amount of liquid water present in the cloud. For the global oceans as a whole the average cloud liquid water is determined to be about 0.08 kg m-2. The major conclusion of this paper is that reasonably accurate amounts of cloud liquid water can be retrieved from SSM/I observations for nonprecipitating cloud systems, particularly in areas of persistent stratocumulus clouds, with less accurate retrievals in tropical regions.

Iterative fitting method for the evaluation and quantification of PAES spectra

NASA Astrophysics Data System (ADS)

Zimnik, Samantha; Hackenberg, Mathias; Hugenschmidt, Christoph

2017-01-01

The elemental composition of surfaces is of great importance for the understanding of many surface processes such as catalysis. For a reliable analysis and a comparison of results, the quantification of the measured data is indispensable. Positron annihilation induced Auger Electron Spectroscopy (PAES) is a spectroscopic technique that measures the elemental composition with outstanding surface sensitivity, but up to now, no standardized evaluation procedure for PAES spectra is available. In this paper we present a new approach for the evaluation of PAES spectra of compounds, using the spectra obtained for the pure elements as reference. The measured spectrum is then fitted by a linear combination of the reference spectra by varying their intensities. The comparison of the results of the fitting routine with a calculation of the full parameter range shows an excellent agreement. We present the results of the new analysis method to evaluate the PAES spectra of sub-monolayers of Ni on a Pd substrate.

Comparison of on-site field measured inorganic arsenic in rice with laboratory measurements using a field deployable method: Method validation.

PubMed

Mlangeni, Angstone Thembachako; Vecchi, Valeria; Norton, Gareth J; Raab, Andrea; Krupp, Eva M; Feldmann, Joerg

2018-10-15

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison of semi-automated center-dot and fully automated endothelial cell analyses from specular microscopy images.

PubMed

Maruoka, Sachiko; Nakakura, Shunsuke; Matsuo, Naoko; Yoshitomi, Kayo; Katakami, Chikako; Tabuchi, Hitoshi; Chikama, Taiichiro; Kiuchi, Yoshiaki

2017-10-30

To evaluate two specular microscopy analysis methods across different endothelial cell densities (ECDs). Endothelial images of one eye from each of 45 patients were taken by using three different specular microscopes (three replicates each). To determine the consistency of the center-dot method, we compared SP-6000 and SP-2000P images. CME-530 and SP-6000 images were compared to assess the consistency of the fully automated method. The SP-6000 images from the two methods were compared. Intraclass correlation coefficients (ICCs) for the three measurements were calculated, and parametric multiple comparisons tests and Bland-Altman analysis were performed. The ECD mean value was 2425 ± 883 (range 516-3707) cells/mm 2 . ICC values were > 0.9 for all three microscopes for ECD, but the coefficients of variation (CVs) were 0.3-0.6. For ECD measurements, Bland-Altman analysis revealed that the mean difference was 42 cells/mm 2 between the SP-2000P and SP-6000 for the center-dot method; 57 cells/mm 2 between the SP-6000 measurements from both methods; and -5 cells/mm 2 between the SP-6000 and CME-530 for the fully automated method (95% limits of agreement: - 201 to 284 cell/mm 2 , - 410 to 522 cells/mm 2 , and - 327 to 318 cells/mm 2 , respectively). For CV measurements, the mean differences were - 3, - 12, and 13% (95% limits of agreement - 18 to 11, - 26 to 2, and - 5 to 32%, respectively). Despite using three replicate measurements, the precision of the center-dot method with the SP-2000P and SP-6000 software was only ± 10% for ECD data and was even worse for the fully automated method. Japan Clinical Trials Register ( http://www.umin.ac.jp/ctr/index/htm9 ) number UMIN 000015236.

A Comparison of Several Methods of Measuring Ignition Lag in a Compression-ignition Engine

NASA Technical Reports Server (NTRS)

Spanogle, J A

1934-01-01

The ignition lag of a fuel oil in the combustion chamber of a high speed compression-ignition engine was measured by three different methods. The start of injection of the fuel as observed with a Stoborama was taken as the start of the period of ignition lag in all cases. The end of the period of ignition lag was determined by observation of the appearance of incandescence in the combustion chamber, by inspection of a pressure-time card for evidence of pressure rise, and by analysis of the indicator card for evidence of the combustion of a small but definite quantity of fuel. A comparison of the values for ignition lags obtained by these three methods indicates that the appearance of incandescence is later than other evidences of the start of combustion, that visual inspection of a pressure-time diagram gives consistent and usable values with a minimum requirement of time and/or apparatus, and that analysis of the indicator card is not worth while for ignition lag alone.

International comparison of health care systems using resource profiles.

PubMed Central

Anell, A.; Willis, M.

2000-01-01

The most frequently used bases for comparing international health care resources are health care expenditures, measured either as a fraction of gross domestic product (GDP) or per capita. There are several possible reasons for this, including the widespread availability of historic expenditure figures; the attractiveness of collapsing resource data into a common unit of measurement; and the present focus among OECD member countries and other governments on containing health care costs. Despite important criticisms of this method, relatively few alternatives have been used in practice. A simple framework for comparing data underlying health care systems is presented in this article. It distinguishes measures of real resources, for example human resources, medicines and medical equipment, from measures of financial resources such as expenditures. Measures of real resources are further subdivided according to whether their factor prices are determined primarily in national or global markets. The approach is illustrated using a simple analysis of health care resource profiles for Denmark, France, Germany, Sweden, the United Kingdom, and the USA. Comparisons based on measures of both real resources and expenditures can be more useful than conventional comparisons of expenditures alone and can lead to important insights for the future management of health care systems. PMID:10916914

The surface area of soil organic matter

USGS Publications Warehouse

Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

1990-01-01

The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

The impact of appearance comparisons made through social media, traditional media, and in person in women's everyday lives.

PubMed

Fardouly, Jasmine; Pinkus, Rebecca T; Vartanian, Lenny R

2017-03-01

Appearance comparisons are an important sociocultural factor influencing women's body image. These comparisons can occur in different contexts (e.g., through magazines, social media, in person). However, little is known about the frequency and outcome of appearance comparisons made in different contexts in women's everyday lives. Using Ecological Momentary Assessment methods, female undergraduate students (n=146) completed a brief online survey at random times every day for 5 days. They reported the frequency, direction (upward, lateral, downward), and context of appearance comparisons, and also reported their appearance satisfaction, mood, and diet and exercise thoughts and behaviors. Upward appearance comparisons were the most common across all contexts. Upward comparisons through social media were associated with more negative outcomes on all measures (except diet and exercise behavior) than comparisons made in person, and with more negative mood than comparisons in any other context. These findings highlight the importance of the appearance comparison context. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Comparison of Assessment Methods and Raters in Product Creativity

ERIC Educational Resources Information Center

Lu, Chia-Chen; Luh, Ding-Bang

2012-01-01

Although previous studies have attempted to use different experiences of raters to rate product creativity by adopting the Consensus Assessment Method (CAT) approach, the validity of replacing CAT with another measurement tool has not been adequately tested. This study aimed to compare raters with different levels of experience (expert ves.…

Physical Activity in Preschool Children: Comparison between Montessori and Traditional Preschools

ERIC Educational Resources Information Center

Pate, Russell R.; O'Neill, Jennifer R.; Byun, Wonwoo; McIver, Kerry L.; Dowda, Marsha; Brown, William H.

2014-01-01

Background: Little is known about the influence of Montessori methods on children's physical activity (PA). This cross-sectional study compared PA of children attending Montessori and traditional preschools. Methods: We enrolled 301 children in 9 Montessori and 8 traditional preschools in Columbia, South Carolina. PA was measured by accelerometry…

Comparison of Observational Methods and Their Relation to Ratings of Engagement in Young Children

ERIC Educational Resources Information Center

Wood, Brenna K.; Hojnoski, Robin L.; Laracy, Seth D.; Olson, Christopher L.

2016-01-01

Although, collectively, results of earlier direct observation studies suggest momentary time sampling (MTS) may offer certain technical advantages over whole-interval (WIR) and partial-interval (PIR) recording, no study has compared these methods for measuring engagement in young children in naturalistic environments. This study compared direct…

Ordinary Least Squares and Quantile Regression: An Inquiry-Based Learning Approach to a Comparison of Regression Methods

ERIC Educational Resources Information Center

Helmreich, James E.; Krog, K. Peter

2018-01-01

We present a short, inquiry-based learning course on concepts and methods underlying ordinary least squares (OLS), least absolute deviation (LAD), and quantile regression (QR). Students investigate squared, absolute, and weighted absolute distance functions (metrics) as location measures. Using differential calculus and properties of convex…

Comparison of estimation methods for creating small area rates of acute myocardial infarction among Medicare beneficiaries in California.

PubMed

Yasaitis, Laura C; Arcaya, Mariana C; Subramanian, S V

2015-09-01

Creating local population health measures from administrative data would be useful for health policy and public health monitoring purposes. While a wide range of options--from simple spatial smoothers to model-based methods--for estimating such rates exists, there are relatively few side-by-side comparisons, especially not with real-world data. In this paper, we compare methods for creating local estimates of acute myocardial infarction rates from Medicare claims data. A Bayesian Monte Carlo Markov Chain estimator that incorporated spatial and local random effects performed best, followed by a method-of-moments spatial Empirical Bayes estimator. As the former is more complicated and time-consuming, spatial linear Empirical Bayes methods may represent a good alternative for non-specialist investigators. Copyright © 2015 Elsevier Ltd. All rights reserved.

Derivation of Aerosol Columnar Mass from MODIS Optical Depth

NASA Technical Reports Server (NTRS)

Gasso, Santiago; Hegg, Dean A.

2003-01-01

In order to verify performance, aerosol transport models (ATM) compare aerosol columnar mass (ACM) with those derived from satellite measurements. The comparison is inherently indirect since satellites derive optical depths and they use a proportionality constant to derive the ACM. Analogously, ATMs output a four dimensional ACM distribution and the optical depth is linearly derived. In both cases, the proportionality constant requires a direct intervention of the user by prescribing the aerosol composition and size distribution. This study introduces a method that minimizes the direct user intervention by making use of the new aerosol products of MODIS. A parameterization is introduced for the derivation of columnar aerosol mass (AMC) and CCN concentration (CCNC) and comparisons between sunphotometer, MODIS Airborne Simulator (MAS) and in-measurements are shown. The method still relies on the scaling between AMC and optical depth but the proportionality constant is dependent on the MODIS derived r$_{eff}$,\\eta (contribution of the accumulation mode radiance to the total radiance), ambient RH and an assumed constant aerosol composition. The CCNC is derived fkom a recent parameterization of CCNC as a function of the retrieved aerosol volume. By comparing with in-situ data (ACE-2 and TARFOX campaigns), it is shown that retrievals in dry ambient conditions (dust) are improved when using a proportionality constant dependent on r$ {eff}$ and \\eta derived in the same pixel. In high humidity environments, the improvement inthe new method is inconclusive because of the difficulty in accounting for the uneven vertical distribution of relative humidity. Additionally, two detailed comparisons of AMC and CCNC retrieved by the MAS algorithm and the new method are shown. The new method and MAS retrievals of AMC are within the same order of magnitude with respect to the in-situ measurements of aerosol mass. However, the proposed method is closer to the in-situ measurements than the MODIS retrievals. The retrievals of CCNC are also within the same order of magnitude for both methods. The new method is applied to an actual MODIS retrieval and although no in-situ data is available to compare, it is shown that the proposed method yields more credible values than the MODIS retrievals. In addition, recent data available from the PRIDE (Puerto Rico Dust Experiment, July 2000) will be shown by comparing sunphotometer, MODIS and in-situ data.

Sine Rotation Vector Method for Attitude Estimation of an Underwater Robot

PubMed Central

Ko, Nak Yong; Jeong, Seokki; Bae, Youngchul

2016-01-01

This paper describes a method for estimating the attitude of an underwater robot. The method employs a new concept of sine rotation vector and uses both an attitude heading and reference system (AHRS) and a Doppler velocity log (DVL) for the purpose of measurement. First, the acceleration and magnetic-field measurements are transformed into sine rotation vectors and combined. The combined sine rotation vector is then transformed into the differences between the Euler angles of the measured attitude and the predicted attitude; the differences are used to correct the predicted attitude. The method was evaluated according to field-test data and simulation data and compared to existing methods that calculate angular differences directly without a preceding sine rotation vector transformation. The comparison verifies that the proposed method improves the attitude estimation performance. PMID:27490549

Subpixel displacement measurement method based on the combination of particle swarm optimization and gradient algorithm

NASA Astrophysics Data System (ADS)

Guang, Chen; Qibo, Feng; Keqin, Ding; Zhan, Gao

2017-10-01

A subpixel displacement measurement method based on the combination of particle swarm optimization (PSO) and gradient algorithm (GA) was proposed for accuracy and speed optimization in GA, which is a subpixel displacement measurement method better applied in engineering practice. An initial integer-pixel value was obtained according to the global searching ability of PSO, and then gradient operators were adopted for a subpixel displacement search. A comparison was made between this method and GA by simulated speckle images and rigid-body displacement in metal specimens. The results showed that the computational accuracy of the combination of PSO and GA method reached 0.1 pixel in the simulated speckle images, or even 0.01 pixels in the metal specimen. Also, computational efficiency and the antinoise performance of the improved method were markedly enhanced.

A critical comparison of electrical methods for measuring spin-orbit torques

NASA Astrophysics Data System (ADS)

Zhang, Xuanzi; Hung, Yu-Ming; Rehm, Laura; Kent, Andrew D.

Direct (DC) and alternating current (AC) transport measurements of spin-orbit torques (SOTs) in heavy metal-ferromagnet heterostructure with perpendicular magnetic anisotropy have been proposed and demonstrated. A DC method measures the change of perpendicular magnetization component while an AC method probes the first and second harmonic magnetization oscillation in responses to an AC current (~1 kHz). Here we conduct both types of measurements on β-Ta/CoFeB/MgO in the form of patterned Hall bars (20 μm linewidth) and compare the results. Experiments results are qualitatively in agreement with a macro spin model including Slonzewski-like and a field-like SOTs. However, the effective field from the ac method is larger than that obtained from the DC method. We discuss the possible origins of the discrepancy and its implications for quantitatively determining SOTs. Research supported by the SRC-INDEX program, NSF-DMR-1309202 and NYU-DURF award.

Woodstove emission measurement methods: Comparison and emission factors update

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCrillis, R.C.; Jaasma, D.R.

1993-01-01

Since woodstoves are tested for certification in the laboratory using EPA Methods 5G and 5H, it is of interest to determine the correlation between these regulatory methods and the inhouse equipment. Two inhouse sampling systems have been used mostwidely: one is an intermittent, pump-driven particulate sampler that collects particulate and condensible organics on a filter and organic adsorbent resin; and the other uses an evacuated cylinder as the motive force and particulate and condensible organics are collected in a condenser and dual filter. Both samplers can operate unattended for 1-week periods. A large number of tests have been run comparingmore » Methods 5G and 5H to both samplers. The paper presents these comparison data and determines the relationships between regulations and field samplers.« less

A Quantitative Comparison of Calibration Methods for RGB-D Sensors Using Different Technologies.

PubMed

Villena-Martínez, Víctor; Fuster-Guilló, Andrés; Azorín-López, Jorge; Saval-Calvo, Marcelo; Mora-Pascual, Jeronimo; Garcia-Rodriguez, Jose; Garcia-Garcia, Alberto

2017-01-27

RGB-D (Red Green Blue and Depth) sensors are devices that can provide color and depth information from a scene at the same time. Recently, they have been widely used in many solutions due to their commercial growth from the entertainment market to many diverse areas (e.g., robotics, CAD, etc.). In the research community, these devices have had good uptake due to their acceptable levelofaccuracyformanyapplicationsandtheirlowcost,butinsomecases,theyworkatthelimitof their sensitivity, near to the minimum feature size that can be perceived. For this reason, calibration processes are critical in order to increase their accuracy and enable them to meet the requirements of such kinds of applications. To the best of our knowledge, there is not a comparative study of calibration algorithms evaluating its results in multiple RGB-D sensors. Specifically, in this paper, a comparison of the three most used calibration methods have been applied to three different RGB-D sensors based on structured light and time-of-flight. The comparison of methods has been carried out by a set of experiments to evaluate the accuracy of depth measurements. Additionally, an object reconstruction application has been used as example of an application for which the sensor works at the limit of its sensitivity. The obtained results of reconstruction have been evaluated through visual inspection and quantitative measurements.

Methodological integrative review of the work sampling technique used in nursing workload research.

PubMed

Blay, Nicole; Duffield, Christine M; Gallagher, Robyn; Roche, Michael

2014-11-01

To critically review the work sampling technique used in nursing workload research. Work sampling is a technique frequently used by researchers and managers to explore and measure nursing activities. However, work sampling methods used are diverse making comparisons of results between studies difficult. Methodological integrative review. Four electronic databases were systematically searched for peer-reviewed articles published between 2002-2012. Manual scanning of reference lists and Rich Site Summary feeds from contemporary nursing journals were other sources of data. Articles published in the English language between 2002-2012 reporting on research which used work sampling to examine nursing workload. Eighteen articles were reviewed. The review identified that the work sampling technique lacks a standardized approach, which may have an impact on the sharing or comparison of results. Specific areas needing a shared understanding included the training of observers and subjects who self-report, standardization of the techniques used to assess observer inter-rater reliability, sampling methods and reporting of outcomes. Work sampling is a technique that can be used to explore the many facets of nursing work. Standardized reporting measures would enable greater comparison between studies and contribute to knowledge more effectively. Author suggestions for the reporting of results may act as guidelines for researchers considering work sampling as a research method. © 2014 John Wiley & Sons Ltd.

KEY COMPARISON: CCQM-K25: Determination of PCB congeners in sediment

NASA Astrophysics Data System (ADS)

Schantz, Michele; Wise, Stephen

2004-01-01

Polychlorinated biphenyls (PCBs) consist of 209 possible congeners depending on the substitution of the chlorine atoms around the biphenyl molecule. PCBs have been widely used as industrial fluids, flame retardants, diluents, hydraulic fluids, and dielectric fluids for capacitors and transformers. As a class of compounds, they are environmentally stable and tend to bioaccumulate. Of the 209 possible congeners, approximately 150 congeners have been reported in the environment. Congener-specific PCB methods, which are typically based on gas chromatography (GC) with electron capture detection (ECD) or mass spectrometric (MS) detection, are designed to measure selected priority congeners, but the congeners of interest change with the study and sponsoring agency. A pilot study (CCQM-P17) for the determination of PCB congeners in sediment was organized by NIST and NRC-Canada in 2000. Ten laboratories participated in the pilot study. After discussion and critical review of the data, there was agreement that the pilot study should be followed by a Key Comparison and that the Key Comparison Reference Value (KCRV) should be derived from isotope dilution GC/MS (ID-GC/MS) based methods that had been validated in the Pilot Study. The CCQM-K25 Key Comparison study utilized a sediment sample prepared by mixing known quantities of two sediment materials to simulate a moderately contaminated sample with respect to PCBs. Nine laboratories participated in CCQM-K25 and demonstrated a high level of equivalence in capabilities for determining five PCB congeners (congener numbers 28, 101, 105, 153, and 170) in a moderately contaminated sediment using GC/MS-based methods. The amount of substance concentration for the congeners measured ranged from ~10 ng/g to ~35 ng/g. The relative expanded uncertainties of the KCRVs ranged from 2% to 5%, indicating excellent agreement among the participants that used ID-GC/MS. Results from the one laboratory that used GC/MS with a non-labeled PCB congener as internal standard showed no systematic bias from the results of other laboratories. The five PCB congeners measured in CCQM-K25 were selected to be representative of the approximately 150 congeners found in environmental samples and to provide the typical analytical measurement challenges encountered in the measurement of individual congeners such as volatility losses during sample preparation and coelution during chromatographic separation. The abilities demonstrated by the laboratories that provided comparable measurements for all five congeners in this Key Comparison should be indicative of their ability to provide reference measurements for the typical suite of PCB congeners found in moderately contaminated sediments (individual congener amount of substance concentrations >5 ng/g dry basis). Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the Mutual Recognition Arrangement (MRA).

Experimental comparison between speech transmission index, rapid speech transmission index, and speech intelligibility index.

PubMed

Larm, Petra; Hongisto, Valtteri

2006-02-01

During the acoustical design of, e.g., auditoria or open-plan offices, it is important to know how speech can be perceived in various parts of the room. Different objective methods have been developed to measure and predict speech intelligibility, and these have been extensively used in various spaces. In this study, two such methods were compared, the speech transmission index (STI) and the speech intelligibility index (SII). Also the simplification of the STI, the room acoustics speech transmission index (RASTI), was considered. These quantities are all based on determining an apparent speech-to-noise ratio on selected frequency bands and summing them using a specific weighting. For comparison, some data were needed on the possible differences of these methods resulting from the calculation scheme and also measuring equipment. Their prediction accuracy was also of interest. Measurements were made in a laboratory having adjustable noise level and absorption, and in a real auditorium. It was found that the measurement equipment, especially the selection of the loudspeaker, can greatly affect the accuracy of the results. The prediction accuracy of the RASTI was found acceptable, if the input values for the prediction are accurately known, even though the studied space was not ideally diffuse.

Multivariate and repeated measures (MRM): A new toolbox for dependent and multimodal group-level neuroimaging data

PubMed Central

McFarquhar, Martyn; McKie, Shane; Emsley, Richard; Suckling, John; Elliott, Rebecca; Williams, Stephen

2016-01-01

Repeated measurements and multimodal data are common in neuroimaging research. Despite this, conventional approaches to group level analysis ignore these repeated measurements in favour of multiple between-subject models using contrasts of interest. This approach has a number of drawbacks as certain designs and comparisons of interest are either not possible or complex to implement. Unfortunately, even when attempting to analyse group level data within a repeated-measures framework, the methods implemented in popular software packages make potentially unrealistic assumptions about the covariance structure across the brain. In this paper, we describe how this issue can be addressed in a simple and efficient manner using the multivariate form of the familiar general linear model (GLM), as implemented in a new MATLAB toolbox. This multivariate framework is discussed, paying particular attention to methods of inference by permutation. Comparisons with existing approaches and software packages for dependent group-level neuroimaging data are made. We also demonstrate how this method is easily adapted for dependency at the group level when multiple modalities of imaging are collected from the same individuals. Follow-up of these multimodal models using linear discriminant functions (LDA) is also discussed, with applications to future studies wishing to integrate multiple scanning techniques into investigating populations of interest. PMID:26921716

Inconsistency between direct and indirect comparisons of competing interventions: meta-epidemiological study

PubMed Central

Xiong, Tengbin; Parekh-Bhurke, Sheetal; Loke, Yoon K; Sutton, Alex J; Eastwood, Alison J; Holland, Richard; Chen, Yen-Fu; Glenny, Anne-Marie; Deeks, Jonathan J; Altman, Doug G

2011-01-01

Objective To investigate the agreement between direct and indirect comparisons of competing healthcare interventions. Design Meta-epidemiological study based on sample of meta-analyses of randomised controlled trials. Data sources Cochrane Database of Systematic Reviews and PubMed. Inclusion criteria Systematic reviews that provided sufficient data for both direct comparison and independent indirect comparisons of two interventions on the basis of a common comparator and in which the odds ratio could be used as the outcome statistic. Main outcome measure Inconsistency measured by the difference in the log odds ratio between the direct and indirect methods. Results The study included 112 independent trial networks (including 1552 trials with 478 775 patients in total) that allowed both direct and indirect comparison of two interventions. Indirect comparison had already been explicitly done in only 13 of the 85 Cochrane reviews included. The inconsistency between the direct and indirect comparison was statistically significant in 16 cases (14%, 95% confidence interval 9% to 22%). The statistically significant inconsistency was associated with fewer trials, subjectively assessed outcomes, and statistically significant effects of treatment in either direct or indirect comparisons. Owing to considerable inconsistency, many (14/39) of the statistically significant effects by direct comparison became non-significant when the direct and indirect estimates were combined. Conclusions Significant inconsistency between direct and indirect comparisons may be more prevalent than previously observed. Direct and indirect estimates should be combined in mixed treatment comparisons only after adequate assessment of the consistency of the evidence. PMID:21846695

Comparison of the Dye Method with the Thermocouple Psychrometer for Measuring Leaf Water Potentials 1

PubMed Central

Knipling, Edward B.; Kramer, Paul J.

1967-01-01

The dye method for measuring water potential was examined and compared with the thermocouple psychrometer method in order to evaluate its usefulness for measuring leaf water potentials of forest trees and common laboratory plants. Psychrometer measurements are assumed to represent the true leaf water potentials. Because of the contamination of test solutions by cell sap and leaf surface residues, dye method values of most species varied about 1 to 5 bars from psychrometer values over the leaf water potential range of 0 to −30 bars. The dye method is useful for measuring changes and relative values in leaf potential. Because of species differences in the relationships of dye method values to true leaf water potentials, dye method values should be interpreted with caution when comparing different species or the same species growing in widely different environments. Despite its limitations the dye method has a usefulness to many workers because it is simple, requires no elaborate equipment, and can be used in both the laboratory and field. PMID:16656657

Comparison of air-kerma strength determinations for HDR (192)Ir sources.

PubMed

Rasmussen, Brian E; Davis, Stephen D; Schmidt, Cal R; Micka, John A; Dewerd, Larry A

2011-12-01

To perform a comparison of the interim air-kerma strength standard for high dose rate (HDR) (192)Ir brachytherapy sources maintained by the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) with measurements of the various source models using modified techniques from the literature. The current interim standard was established by Goetsch et al. in 1991 and has remained unchanged to date. The improved, laser-aligned seven-distance apparatus of the University of Wisconsin Medical Radiation Research Center (UWMRRC) was used to perform air-kerma strength measurements of five different HDR (192)Ir source models. The results of these measurements were compared with those from well chambers traceable to the original standard. Alternative methodologies for interpolating the (192)Ir air-kerma calibration coefficient from the NIST air-kerma standards at (137)Cs and 250 kVp x rays (M250) were investigated and intercompared. As part of the interpolation method comparison, the Monte Carlo code EGSnrc was used to calculate updated values of A(wall) for the Exradin A3 chamber used for air-kerma strength measurements. The effects of air attenuation and scatter, room scatter, as well as the solution method were investigated in detail. The average measurements when using the inverse N(K) interpolation method for the Classic Nucletron, Nucletron microSelectron, VariSource VS2000, GammaMed Plus, and Flexisource were found to be 0.47%, -0.10%, -1.13%, -0.20%, and 0.89% different than the existing standard, respectively. A further investigation of the differences observed between the sources was performed using MCNP5 Monte Carlo simulations of each source model inside a full model of an HDR 1000 Plus well chamber. Although the differences between the source models were found to be statistically significant, the equally weighted average difference between the seven-distance measurements and the well chambers was 0.01%, confirming that it is not necessary to update the current standard maintained at the UWADCL.

Comparison of geodetic and glaciological mass-balance techniques, Gulkana Glacier, Alaska, U.S.A

USGS Publications Warehouse

Cox, L.H.; March, R.S.

2004-01-01

The net mass balance on Gulkana Glacier, Alaska, U.S.A., has been measured since 1966 by the glaciological method, in which seasonal balances are measured at three index sites and extrapolated over large areas of the glacier. Systematic errors can accumulate linearly with time in this method. Therefore, the geodetic balance, in which errors are less time-dependent, was calculated for comparison with the glaciological method. Digital elevation models of the glacier in 1974, 1993 and 1999 were prepared using aerial photographs, and geodetic balances were computed, giving - 6.0??0.7 m w.e. from 1974 to 1993 and - 11.8??0.7 m w.e. from 1974 to 1999. These balances are compared with the glaciological balances over the same intervals, which were - 5.8??0.9 and -11.2??1.0 m w.e. respectively; both balances show that the thinning rate tripled in the 1990s. These cumulative balances differ by <6%. For this close agreement, the glaciologically measured mass balance of Gulkana Glacier must be largely free of systematic errors and be based on a time-variable area-altitude distribution, and the photography used in the geodetic method must have enough contrast to enable accurate photogrammetry.

Digital quantification of Goldmann visual fields (GVFs) as a means for genotype-phenotype comparisons and detection of progression in retinal degenerations.

PubMed

Zahid, Sarwar; Peeler, Crandall; Khan, Naheed; Davis, Joy; Mahmood, Mahdi; Heckenlively, John R; Jayasundera, Thiran

2014-01-01

To develop a reliable and efficient digital method to quantify planimetric Goldmann visual field (GVF) data to monitor disease course and treatment responses in retinal degenerative diseases. A novel method to digitally quantify GVFs using Adobe Photoshop CS3 was developed for comparison to traditional digital planimetry (Placom 45C digital planimeter; Engineer Supply, Lynchburg, Virginia, USA). GVFs from 20 eyes from 10 patients with Stargardt disease were quantified to assess the difference between the two methods (a total of 230 measurements per method). This quantification approach was also applied to 13 patients with X-linked retinitis pigmentosa (XLRP) with mutations in RPGR. Overall, measurements using Adobe Photoshop were more rapidly performed than those using conventional planimetry. Photoshop measurements also exhibited less inter- and intraobserver variability. GVF areas for the I4e isopter in patients with the same mutation in RPGR who were nearby in age had similar qualitative and quantitative areas. Quantification of GVFs using Adobe Photoshop is quicker, more reliable, and less user dependent than conventional digital planimetry. It will be a useful tool for both retrospective and prospective studies of disease course as well as for monitoring treatment response in clinical trials for retinal degenerative diseases.

Measurement and calibration of differential Mueller matrix of distributed targets

NASA Technical Reports Server (NTRS)

Sarabandi, Kamal; Oh, Yisok; Ulaby, Fawwaz T.

1992-01-01

A rigorous method for calibrating polarimetric backscatter measurements of distributed targets is presented. By characterizing the radar distortions over the entire mainlobe of the antenna, the differential Mueller matrix is derived from the measured scattering matrices with a high degree of accuracy. It is shown that the radar distortions can be determined by measuring the polarimetric response of a metallic sphere over the main lobe of the antenna. Comparison of results obtained with the new algorithm with the results derived from the old calibration method show that the discrepancy between the two methods is less than 1 dB for the backscattering coefficients. The discrepancy is more drastic for the phase-difference statistics, indicating that removal of the radar distortions from the cross products of the scattering matrix elements cannot be accomplished with the traditional calibration methods.

Pulse Transit Time Measurement Using Seismocardiogram, Photoplethysmogram, and Acoustic Recordings: Evaluation and Comparison.

PubMed

Yang, Chenxi; Tavassolian, Negar

2018-05-01

This work proposes a novel method of pulse transit time (PTT) measurement. The proximal arterial location data are collected from seismocardiogram (SCG) recordings by placing a micro-electromechanical accelerometer on the chest wall. The distal arterial location data are recorded using an acoustic sensor placed inside the ear. The performance of distal location recordings is evaluated by comparing SCG-acoustic and SCG-photoplethysmogram (PPG) measurements. PPG and acoustic performances under motion noise are also compared. Experimental results suggest comparable performances for the acoustic-based and PPG-based devices. The feasibility of each PTT measurement method is validated for blood pressure evaluations and its limitations are analyzed.

Uncertainty estimation and multi sensor fusion for kinematic laser tracker measurements

NASA Astrophysics Data System (ADS)

Ulrich, Thomas

2013-08-01

Laser trackers are widely used to measure kinematic tasks such as tracking robot movements. Common methods to evaluate the uncertainty in the kinematic measurement include approximations specified by the manufacturers, various analytical adjustment methods and the Kalman filter. In this paper a new, real-time technique is proposed, which estimates the 4D-path (3D-position + time) uncertainty of an arbitrary path in space. Here a hybrid system estimator is applied in conjunction with the kinematic measurement model. This method can be applied to processes, which include various types of kinematic behaviour, constant velocity, variable acceleration or variable turn rates. The new approach is compared with the Kalman filter and a manufacturer's approximations. The comparison was made using data obtained by tracking an industrial robot's tool centre point with a Leica laser tracker AT901 and a Leica laser tracker LTD500. It shows that the new approach is more appropriate to analysing kinematic processes than the Kalman filter, as it reduces overshoots and decreases the estimated variance. In comparison with the manufacturer's approximations, the new approach takes account of kinematic behaviour with an improved description of the real measurement process and a reduction in estimated variance. This approach is therefore well suited to the analysis of kinematic processes with unknown changes in kinematic behaviour as well as the fusion among laser trackers.

Comparing the Medicaid Retrospective Drug Utilization Review Program Cost-Savings Methods Used by State Agencies

PubMed Central

Prada, Sergio I.

2017-01-01

Background The Medicaid Drug Utilization Review (DUR) program is a 2-phase process conducted by Medicaid state agencies. The first phase is a prospective DUR and involves electronically monitoring prescription drug claims to identify prescription-related problems, such as therapeutic duplication, contraindications, incorrect dosage, or duration of treatment. The second phase is a retrospective DUR and involves ongoing and periodic examinations of claims data to identify patterns of fraud, abuse, underutilization, drug–drug interaction, or medically unnecessary care, implementing corrective actions when needed. The Centers for Medicare & Medicaid Services requires each state to measure prescription drug cost-savings generated from its DUR programs on an annual basis, but it provides no guidance or unified methodology for doing so. Objectives To describe and synthesize the methodologies used by states to measure cost-savings using their Medicaid retrospective DUR program in federal fiscal years 2014 and 2015. Method For each state, the cost-savings methodologies included in the Medicaid DUR 2014 and 2015 reports were downloaded from Medicaid's website. The reports were then reviewed and synthesized. Methods described by the states were classified according to research designs often described in evaluation textbooks. Discussion In 2014, the most often used prescription drugs cost-savings estimation methodology for the Medicaid retrospective DUR program was a simple pre-post intervention method, without a comparison group (ie, 12 states). In 2015, the most common methodology used was a pre-post intervention method, with a comparison group (ie, 14 states). Comparisons of savings attributed to the program among states are still unreliable, because of a lack of a common methodology available for measuring cost-savings. Conclusion There is great variation among states in the methods used to measure prescription drug utilization cost-savings. This analysis suggests that there is still room for improvement in terms of methodology transparency, which is important, because lack of transparency hinders states from learning from each other. Ultimately, the federal government needs to evaluate and improve its DUR program. PMID:29403573

Comparison of ionospheric plasma drifts obtained by different techniques

NASA Astrophysics Data System (ADS)

Kouba, Daniel; Arikan, Feza; Arikan, Orhan; Toker, Cenk; Mosna, Zbysek; Gok, Gokhan; Rejfek, Lubos; Ari, Gizem

2016-07-01

Ionospheric observatory in Pruhonice (Czech Republic, 50N, 14.9E) provides regular ionospheric sounding using Digisonde DPS-4D. The paper is focused on F-region vertical drift data. Vertical component of the drift velocity vector can be estimated by several methods. Digisonde DPS-4D allows sounding in drift mode with direct output represented by drift velocity vector. The Digisonde located in Pruhonice provides direct drift measurement routinely once per 15 minutes. However, also other different techniques can be found in the literature, for example the indirect estimation based on the temporal evolution of measured ionospheric characteristics is often used for calculation of the vertical drift component. The vertical velocity is thus estimated according to the change of characteristics scaled from the classical quarter-hour ionograms. In present paper direct drift measurement is compared with technique based on measuring of the virtual height at fixed frequency from the F-layer trace on ionogram, technique based on variation of h`F and hmF. This comparison shows possibility of using different methods for calculating vertical drift velocity and their relationship to the direct measurement used by Digisonde. This study is supported by the Joint TUBITAK 114E092 and AS CR 14/001 projects.

Experimental Verification of Modeled Thermal Distribution Produced by a Piston Source in Physiotherapy Ultrasound

PubMed Central

Lopez-Haro, S. A.; Leija, L.

2016-01-01

Objectives. To present a quantitative comparison of thermal patterns produced by the piston-in-a-baffle approach with those generated by a physiotherapy ultrasonic device and to show the dependency among thermal patterns and acoustic intensity distributions. Methods. The finite element (FE) method was used to model an ideal acoustic field and the produced thermal pattern to be compared with the experimental acoustic and temperature distributions produced by a real ultrasonic applicator. A thermal model using the measured acoustic profile as input is also presented for comparison. Temperature measurements were carried out with thermocouples inserted in muscle phantom. The insertion place of thermocouples was monitored with ultrasound imaging. Results. Modeled and measured thermal profiles were compared within the first 10 cm of depth. The ideal acoustic field did not adequately represent the measured field having different temperature profiles (errors 10% to 20%). Experimental field was concentrated near the transducer producing a region with higher temperatures, while the modeled ideal temperature was linearly distributed along the depth. The error was reduced to 7% when introducing the measured acoustic field as the input variable in the FE temperature modeling. Conclusions. Temperature distributions are strongly related to the acoustic field distributions. PMID:27999801

A Comparison of the Efficacy of Survey Methods for Amphibians in Small Forest Ponds

Treesearch

Richard R. Buech; Leanna M. Egeland

2002-01-01

Although researchers have studied amphibians for many years, status assessments have been hampered by a lack of standards and protocols for inventory and monitoring. Heyer et al. (1994) and Olson et al. (1997) provide a foundation in their reviews of methods used for measuring and monitoring amphibian biodiversity. It is clear from these reviews that no single method...

Optimal Threshold Determination for Interpreting Semantic Similarity and Particularity: Application to the Comparison of Gene Sets and Metabolic Pathways Using GO and ChEBI

PubMed Central

Bettembourg, Charles; Diot, Christian; Dameron, Olivier

2015-01-01

Background The analysis of gene annotations referencing back to Gene Ontology plays an important role in the interpretation of high-throughput experiments results. This analysis typically involves semantic similarity and particularity measures that quantify the importance of the Gene Ontology annotations. However, there is currently no sound method supporting the interpretation of the similarity and particularity values in order to determine whether two genes are similar or whether one gene has some significant particular function. Interpretation is frequently based either on an implicit threshold, or an arbitrary one (typically 0.5). Here we investigate a method for determining thresholds supporting the interpretation of the results of a semantic comparison. Results We propose a method for determining the optimal similarity threshold by minimizing the proportions of false-positive and false-negative similarity matches. We compared the distributions of the similarity values of pairs of similar genes and pairs of non-similar genes. These comparisons were performed separately for all three branches of the Gene Ontology. In all situations, we found overlap between the similar and the non-similar distributions, indicating that some similar genes had a similarity value lower than the similarity value of some non-similar genes. We then extend this method to the semantic particularity measure and to a similarity measure applied to the ChEBI ontology. Thresholds were evaluated over the whole HomoloGene database. For each group of homologous genes, we computed all the similarity and particularity values between pairs of genes. Finally, we focused on the PPAR multigene family to show that the similarity and particularity patterns obtained with our thresholds were better at discriminating orthologs and paralogs than those obtained using default thresholds. Conclusion We developed a method for determining optimal semantic similarity and particularity thresholds. We applied this method on the GO and ChEBI ontologies. Qualitative analysis using the thresholds on the PPAR multigene family yielded biologically-relevant patterns. PMID:26230274

Quantum coupled mutation finder: predicting functionally or structurally important sites in proteins using quantum Jensen-Shannon divergence and CUDA programming.

PubMed

Gültas, Mehmet; Düzgün, Güncel; Herzog, Sebastian; Jäger, Sven Joachim; Meckbach, Cornelia; Wingender, Edgar; Waack, Stephan

2014-04-03

The identification of functionally or structurally important non-conserved residue sites in protein MSAs is an important challenge for understanding the structural basis and molecular mechanism of protein functions. Despite the rich literature on compensatory mutations as well as sequence conservation analysis for the detection of those important residues, previous methods often rely on classical information-theoretic measures. However, these measures usually do not take into account dis/similarities of amino acids which are likely to be crucial for those residues. In this study, we present a new method, the Quantum Coupled Mutation Finder (QCMF) that incorporates significant dis/similar amino acid pair signals in the prediction of functionally or structurally important sites. The result of this study is twofold. First, using the essential sites of two human proteins, namely epidermal growth factor receptor (EGFR) and glucokinase (GCK), we tested the QCMF-method. The QCMF includes two metrics based on quantum Jensen-Shannon divergence to measure both sequence conservation and compensatory mutations. We found that the QCMF reaches an improved performance in identifying essential sites from MSAs of both proteins with a significantly higher Matthews correlation coefficient (MCC) value in comparison to previous methods. Second, using a data set of 153 proteins, we made a pairwise comparison between QCMF and three conventional methods. This comparison study strongly suggests that QCMF complements the conventional methods for the identification of correlated mutations in MSAs. QCMF utilizes the notion of entanglement, which is a major resource of quantum information, to model significant dissimilar and similar amino acid pair signals in the detection of functionally or structurally important sites. Our results suggest that on the one hand QCMF significantly outperforms the previous method, which mainly focuses on dissimilar amino acid signals, to detect essential sites in proteins. On the other hand, it is complementary to the existing methods for the identification of correlated mutations. The method of QCMF is computationally intensive. To ensure a feasible computation time of the QCMF's algorithm, we leveraged Compute Unified Device Architecture (CUDA).The QCMF server is freely accessible at http://qcmf.informatik.uni-goettingen.de/.

The comparative analysis of the current-meter method and the pressure-time method used for discharge measurements in the Kaplan turbine penstocks

NASA Astrophysics Data System (ADS)

Adamkowski, A.; Krzemianowski, Z.

2012-11-01

The paper presents experiences gathered during many years of utilizing the current-meter and pressure-time methods for flow rate measurements in many hydropower plants. The integration techniques used in these both methods are different from the recommendations contained in the relevant international standards, mainly from the graphical and arithmetical ones. The results of the comparative analysis of both methods applied at the same time during the hydraulic performance tests of two Kaplan turbines in one of the Polish hydropower plant are presented in the final part of the paper. In the case of the pressure-time method application, the concrete penstocks of the tested turbines required installing a special measuring instrumentation inside the penstock. The comparison has shown a satisfactory agreement between the results of discharge measurements executed using the both considered methods. Maximum differences between the discharge values have not exceeded 1.0 % and the average differences have not been greater than 0.5 %.

Validation of a Mobile Device for Acoustic Coordinated Reset Neuromodulation Tinnitus Therapy.

PubMed

Hauptmann, Christian; Wegener, Alexander; Poppe, Hendrik; Williams, Mark; Popelka, Gerald; Tass, Peter A

2016-10-01

Sound-based tinnitus intervention stimuli include broad-band noise signals with subjectively adjusted bandwidths used as maskers delivered by commercial devices or hearing aids, environmental sounds broadly described and delivered by both consumer devices and hearing aids, music recordings specifically modified and delivered in a variety of different ways, and other stimuli. Acoustic coordinated reset neuromodulation therapy for tinnitus reduction has unique and more stringent requirements compared to all other sound-based tinnitus interventions. These include precise characterization of tinnitus pitch and loudness, and effective provision of patient-controlled daily therapy signals at defined frequencies, levels, and durations outside of the clinic. The purpose of this study was to evaluate an approach to accommodate these requirements including evaluation of a mobile device, validation of an automated tinnitus pitch-matching algorithm and assessment of a patient's ability to control stimuli and collect repeated outcome measures. The experimental design involved direct laboratory measurements of the sound delivery capabilities of a mobile device, comparison of an automated, adaptive pitch-matching method to a traditional manual method and measures of a patient's ability to understand and manipulate a mobile device graphic user interface to both deliver the therapy signals and collect the outcome measures. This study consisted of 5 samples of a common mobile device for the laboratory measures and a total of 30 adult participants: 15 randomly selected normal-hearing participants with simulated tinnitus for validation of a tinnitus pitch-matching algorithm and 15 sequentially selected patients already undergoing tinnitus therapy for evaluation of patient usability. No tinnitus intervention(s) were specifically studied as a component of this study. Data collection involved laboratory measures of mobile devices, comparison of manual and automated adaptive tinnitus pitch-matching psychoacoustic procedures in the same participant analyzed for absolute differences (t test), variance differences (f test), and range comparisons, and assessment of patient usability including questionnaire measures and logs of patient observations. Mobile devices are able to reliably and accurately deliver the acoustic therapy signals. There was no difference in mean pitch matches (t test, p > 0.05) between an automated adaptive method compared to a traditional manual pitch-matching method. However, the variability of the automated pitch-matching method was much less (f test, p < 0.05) with twice as many matches within the predefined error range (±5%) compared to the manual pitch-matching method (80% versus 40%). After a short initial training, all participants were able to use the mobile device effectively and to perform the required tasks without further professional assistance. American Academy of Audiology

Comparison of survey and photogrammetry methods to position gravity data, Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponce, D.A.; Wu, S.S.C.; Spielman, J.B.

1985-12-31

Locations of gravity stations at Yucca Mountain, Nevada, were determined by a survey using an electronic distance-measuring device and by a photogram-metric method. The data from both methods were compared to determine if horizontal and vertical coordinates developed from photogrammetry are sufficently accurate to position gravity data at the site. The results show that elevations from the photogrammetric data have a mean difference of 0.57 +- 0.70 m when compared with those of the surveyed data. Comparison of the horizontal control shows that the two methods agreed to within 0.01 minute. At a latitude of 45{sup 0}, an error ofmore » 0.01 minute (18 m) corresponds to a gravity anomaly error of 0.015 mGal. Bouguer gravity anomalies are most sensitive to errors in elevation, thus elevation is the determining factor for use of photogrammetric or survey methods to position gravity data. Because gravity station positions are difficult to locate on aerial photographs, photogrammetric positions are not always exactly at the gravity station; therefore, large disagreements may appear when comparing electronic and photogrammetric measurements. A mean photogrammetric elevation error of 0.57 m corresponds to a gravity anomaly error of 0.11 mGal. Errors of 0.11 mGal are too large for high-precision or detailed gravity measurements but acceptable for regional work. 1 ref. 2 figs., 4 tabs.« less

Multi-feature machine learning model for automatic segmentation of green fractional vegetation cover for high-throughput field phenotyping.

PubMed

Sadeghi-Tehran, Pouria; Virlet, Nicolas; Sabermanesh, Kasra; Hawkesford, Malcolm J

2017-01-01

Accurately segmenting vegetation from the background within digital images is both a fundamental and a challenging task in phenotyping. The performance of traditional methods is satisfactory in homogeneous environments, however, performance decreases when applied to images acquired in dynamic field environments. In this paper, a multi-feature learning method is proposed to quantify vegetation growth in outdoor field conditions. The introduced technique is compared with the state-of the-art and other learning methods on digital images. All methods are compared and evaluated with different environmental conditions and the following criteria: (1) comparison with ground-truth images, (2) variation along a day with changes in ambient illumination, (3) comparison with manual measurements and (4) an estimation of performance along the full life cycle of a wheat canopy. The method described is capable of coping with the environmental challenges faced in field conditions, with high levels of adaptiveness and without the need for adjusting a threshold for each digital image. The proposed method is also an ideal candidate to process a time series of phenotypic information throughout the crop growth acquired in the field. Moreover, the introduced method has an advantage that it is not limited to growth measurements only but can be applied on other applications such as identifying weeds, diseases, stress, etc.

A comparison of high-frequency cross-correlation measures

NASA Astrophysics Data System (ADS)

Precup, Ovidiu V.; Iori, Giulia

2004-12-01

On a high-frequency scale the time series are not homogeneous, therefore standard correlation measures cannot be directly applied to the raw data. There are two ways to deal with this problem. The time series can be homogenised through an interpolation method (An Introduction to High-Frequency Finance, Academic Press, NY, 2001) (linear or previous tick) and then the Pearson correlation statistic computed. Recently, methods that can handle raw non-synchronous time series have been developed (Int. J. Theor. Appl. Finance 6(1) (2003) 87; J. Empirical Finance 4 (1997) 259). This paper compares two traditional methods that use interpolation with an alternative method applied directly to the actual time series.

Comparison of diffusion length measurements from the Flying Spot Technique and the photocarrier grating method in amorphous thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira, M.; Fantoni, A.; Martins, R.

1994-12-31

Using the Flying Spot Technique (FST) the authors have studied minority carrier transport parallel and perpendicular to the surface of amorphous silicon films (a-Si:H). To reduce slow transients due to charge redistribution in low resistivity regions during the measurement they have applied a strong homogeneously absorbed bias light. The defect density was estimated from Constant Photocurrent Method (CPM) measurements. The steady-state photocarrier grating technique (SSPG) is a 1-dimensional approach. However, the modulation depth of the carrier profile is also dependent on film surface properties, like surface recombination velocity. Both methods yield comparable diffusion lengths when applied to a-Si:H.

Joint Research on Scatterometry and AFM Wafer Metrology

NASA Astrophysics Data System (ADS)

Bodermann, Bernd; Buhr, Egbert; Danzebrink, Hans-Ulrich; Bär, Markus; Scholze, Frank; Krumrey, Michael; Wurm, Matthias; Klapetek, Petr; Hansen, Poul-Erik; Korpelainen, Virpi; van Veghel, Marijn; Yacoot, Andrew; Siitonen, Samuli; El Gawhary, Omar; Burger, Sven; Saastamoinen, Toni

2011-11-01

Supported by the European Commission and EURAMET, a consortium of 10 participants from national metrology institutes, universities and companies has started a joint research project with the aim of overcoming current challenges in optical scatterometry for traceable linewidth metrology. Both experimental and modelling methods will be enhanced and different methods will be compared with each other and with specially adapted atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurement systems in measurement comparisons. Additionally novel methods for sophisticated data analysis will be developed and investigated to reach significant reductions of the measurement uncertainties in critical dimension (CD) metrology. One final goal will be the realisation of a wafer based reference standard material for calibration of scatterometers.

Spline based least squares integration for two-dimensional shape or wavefront reconstruction

DOE PAGES

Huang, Lei; Xue, Junpeng; Gao, Bo; ...

2016-12-21

In this paper, we present a novel method to handle two-dimensional shape or wavefront reconstruction from its slopes. The proposed integration method employs splines to fit the measured slope data with piecewise polynomials and uses the analytical polynomial functions to represent the height changes in a lateral spacing with the pre-determined spline coefficients. The linear least squares method is applied to estimate the height or wavefront as a final result. Numerical simulations verify that the proposed method has less algorithm errors than two other existing methods used for comparison. Especially at the boundaries, the proposed method has better performance. Themore » noise influence is studied by adding white Gaussian noise to the slope data. Finally, experimental data from phase measuring deflectometry are tested to demonstrate the feasibility of the new method in a practical measurement.« less

Spline based least squares integration for two-dimensional shape or wavefront reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lei; Xue, Junpeng; Gao, Bo

In this paper, we present a novel method to handle two-dimensional shape or wavefront reconstruction from its slopes. The proposed integration method employs splines to fit the measured slope data with piecewise polynomials and uses the analytical polynomial functions to represent the height changes in a lateral spacing with the pre-determined spline coefficients. The linear least squares method is applied to estimate the height or wavefront as a final result. Numerical simulations verify that the proposed method has less algorithm errors than two other existing methods used for comparison. Especially at the boundaries, the proposed method has better performance. Themore » noise influence is studied by adding white Gaussian noise to the slope data. Finally, experimental data from phase measuring deflectometry are tested to demonstrate the feasibility of the new method in a practical measurement.« less

Comparison of gravimetric and gas chromatographic methods for assessing performance of textile materials against liquid pesticide penetration.

PubMed

Shaw, Anugrah; Abbi, Ruchika

2004-01-01

Penetration of liquid pesticides through textile materials is a criterion for determining the performance of protective clothing used by pesticide handlers. The pipette method is frequently used to apply liquid pesticides onto textile materials to measure penetration. Typically, analytical techniques such as Gas Chromatography (GC) are used to measure percentage penetration. These techniques are labor intensive and costly. A simpler gravimetric method was developed, and tests were conducted to compare the gravimetric and GC methods of analysis. Three types of pesticide formulations and 4 fabrics were used for the study. Diluted pesticide formulations were pipetted onto the test specimens and percentage penetration was measured using the 2 methods. For homogeneous formulation, the results of the two methods were fairly comparable. However, due to the filtering action of the textile materials, there were differences in the percentage penetration between the 2 methods for formulations that were not homogeneous.

FOEHN: The critical experiment for the Franco-German High Flux Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scharmer, K.; Eckert, H. G.

1991-01-01

A critical experiment for the Franco-German High Flux Reactor was carried out in the French reactor EOLE (CEN Cadarache). The purpose of the experiment was to check the calculation methods in a realistic geometry and to measure effects that can only be calculated imprecisely (e.g. beam hole effects). The structure of the experiment and the measurement and calculation methods are described. A detailed comparison between theoretical and experimental results was performed. 30 refs., 105 figs.

Evaluation of absolute measurement using a 4π plastic scintillator for the 4πβ-γ coincidence counting method.

PubMed

Unno, Y; Sanami, T; Sasaki, S; Hagiwara, M; Yunoki, A

2018-04-01

Absolute measurement by the 4πβ-γ coincidence counting method was conducted by two photomultipliers facing across a plastic scintillator to be focused on β ray counting efficiency. The detector was held with a through-hole-type NaI(Tl) detector. The results include absolutely determined activity and its uncertainty especially about extrapolation. A comparison between the obtained and known activities showed agreement within their uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Method for controlling gas metal arc welding

DOEpatents

Smartt, Herschel B.; Einerson, Carolyn J.; Watkins, Arthur D.

1989-01-01

The heat input and mass input in a Gas Metal Arc welding process are controlled by a method that comprises calculating appropriate values for weld speed, filler wire feed rate and an expected value for the welding current by algorithmic function means, applying such values for weld speed and filler wire feed rate to the welding process, measuring the welding current, comparing the measured current to the calculated current, using said comparison to calculate corrections for the weld speed and filler wire feed rate, and applying corrections.

Comparison between two methods of hydrostatic weighing without head submersion in morbidly obese females.

PubMed

Israel, R G; Evans, P; Pories, W J; O'Brien, K F; Donnelly, J E

1990-01-01

This study compared two methods of hydrostatic weighing without head submersion to conventional hydrostatic weighting in morbidly obese females. We concluded that hydrostatic weighing without head submersion is a valid alternative to conventional hydrostatic weighing especially when subjects are apprehensive in the water. The use of anthropometric head measures (HWNS-A) did not significantly improve the accuracy of the body composition assessment; therefore, elimination of these time consuming measurements in favor of the direct correction of head above Db is recommended.

Future directions for LDEF ionizing radiation modeling and assessments

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

1992-01-01

Data from the ionizing radiation dosimetry aboard LDEF provide a unique opportunity for assessing the accuracy of current space radiation models and in identifying needed improvements for future mission applications. Details are given of the LDEF data available for radiation model evaluations. The status is given of model comparisons with LDEF data, along with future directions of planned modeling efforts and data comparison assessments. The methodology is outlined which is related to modeling being used to help insure that the LDEF ionizing radiation results can be used to address ionizing radiation issues for future missions. In general, the LDEF radiation modeling has emphasized quick-look predictions using simplified methods to make comparisons with absorbed dose measurements and induced radioactivity measurements of emissions. Modeling and LDEF data comparisons related to linear energy transfer spectra are of importance for several reasons which are outlined. The planned modeling and LDEF data comparisons for LET spectra is discussed, including components of the LET spectra due to different environment sources, contribution from different production mechanisms, and spectra in plastic detectors vs silicon.

Dichotomisation using a distributional approach when the outcome is skewed.

PubMed

Sauzet, Odile; Ofuya, Mercy; Peacock, Janet L

2015-04-24

Dichotomisation of continuous outcomes has been rightly criticised by statisticians because of the loss of information incurred. However to communicate a comparison of risks, dichotomised outcomes may be necessary. Peacock et al. developed a distributional approach to the dichotomisation of normally distributed outcomes allowing the presentation of a comparison of proportions with a measure of precision which reflects the comparison of means. Many common health outcomes are skewed so that the distributional method for the dichotomisation of continuous outcomes may not apply. We present a methodology to obtain dichotomised outcomes for skewed variables illustrated with data from several observational studies. We also report the results of a simulation study which tests the robustness of the method to deviation from normality and assess the validity of the newly developed method. The review showed that the pattern of dichotomisation was varying between outcomes. Birthweight, Blood pressure and BMI can either be transformed to normal so that normal distributional estimates for a comparison of proportions can be obtained or better, the skew-normal method can be used. For gestational age, no satisfactory transformation is available and only the skew-normal method is reliable. The normal distributional method is reliable also when there are small deviations from normality. The distributional method with its applicability for common skewed data allows researchers to provide both continuous and dichotomised estimates without losing information or precision. This will have the effect of providing a practical understanding of the difference in means in terms of proportions.

Quantification of network structural dissimilarities.

PubMed

Schieber, Tiago A; Carpi, Laura; Díaz-Guilera, Albert; Pardalos, Panos M; Masoller, Cristina; Ravetti, Martín G

2017-01-09

Identifying and quantifying dissimilarities among graphs is a fundamental and challenging problem of practical importance in many fields of science. Current methods of network comparison are limited to extract only partial information or are computationally very demanding. Here we propose an efficient and precise measure for network comparison, which is based on quantifying differences among distance probability distributions extracted from the networks. Extensive experiments on synthetic and real-world networks show that this measure returns non-zero values only when the graphs are non-isomorphic. Most importantly, the measure proposed here can identify and quantify structural topological differences that have a practical impact on the information flow through the network, such as the presence or absence of critical links that connect or disconnect connected components.

Relative humidity vertical profiling using lidar-based synergistic methods in the framework of the Hygra-CD campaign

NASA Astrophysics Data System (ADS)

Labzovskii, Lev D.; Papayannis, Alexandros; Binietoglou, Ioannis; Banks, Robert F.; Baldasano, Jose M.; Toanca, Florica; Tzanis, Chris G.; Christodoulakis, John

2018-02-01

Accurate continuous measurements of relative humidity (RH) vertical profiles in the lower troposphere have become a significant scientific challenge. In recent years a synergy of various ground-based remote sensing instruments have been successfully used for RH vertical profiling, which has resulted in the improvement of spatial resolution and, in some cases, of the accuracy of the measurement. Some studies have also suggested the use of high-resolution model simulations as input datasets into RH vertical profiling techniques. In this paper we apply two synergetic methods for RH profiling, including the synergy of lidar with a microwave radiometer and high-resolution atmospheric modeling. The two methods are employed for RH retrieval between 100 and 6000 m with increased spatial resolution, based on datasets from the HygrA-CD (Hygroscopic Aerosols to Cloud Droplets) campaign conducted in Athens, Greece from May to June 2014. RH profiles from synergetic methods are then compared with those retrieved using single instruments or as simulated by high-resolution models. Our proposed technique for RH profiling provides improved statistical agreement with reference to radiosoundings by 27 % when the lidar-radiometer (in comparison with radiometer measurements) approach is used and by 15 % when a lidar model is used (in comparison with WRF-model simulations). Mean uncertainty of RH due to temperature bias in RH profiling was ˜ 4.34 % for the lidar-radiometer and ˜ 1.22 % for the lidar-model methods. However, maximum uncertainty in RH retrievals due to temperature bias showed that lidar-model method is more reliable at heights greater than 2000 m. Overall, our results have demonstrated the capability of both combined methods for daytime measurements in heights between 100 and 6000 m when lidar-radiometer or lidar-WRF combined datasets are available.

Applying wavelet transforms to analyse aircraft-measured turbulence and turbulent fluxes in the atmospheric boundary layer over eastern Siberia

NASA Astrophysics Data System (ADS)

Strunin, M. A.; Hiyama, T.

2004-11-01

The wavelet spectral method was applied to aircraft-based measurements of atmospheric turbulence obtained during joint Russian-Japanese research on the atmospheric boundary layer near Yakutsk (eastern Siberia) in April-June 2000. Practical ways to apply Fourier and wavelet methods for aircraft-based turbulence data are described. Comparisons between Fourier and wavelet transform results are shown and they demonstrate, in conjunction with theoretical and experimental restrictions, that the Fourier transform method is not useful for studying non-homogeneous turbulence. The wavelet method is free from many disadvantages of Fourier analysis and can yield more informative results. Comparison of Fourier and Morlet wavelet spectra showed good agreement at high frequencies (small scales). The quality of the wavelet transform and corresponding software was estimated by comparing the original data with restored data constructed with an inverse wavelet transform. A Haar wavelet basis was inappropriate for the turbulence data; the mother wavelet function recommended in this study is the Morlet wavelet. Good agreement was also shown between variances and covariances estimated with different mathematical techniques, i.e. through non-orthogonal wavelet spectra and through eddy correlation methods.

Comparison of three methods for evaluation of work postures in a truck assembly plant.

PubMed

Zare, Mohsen; Biau, Sophie; Brunet, Rene; Roquelaure, Yves

2017-11-01

This study compared the results of three risk assessment tools (self-reported questionnaire, observational tool, direct measurement method) for the upper limbs and back in a truck assembly plant at two cycle times (11 and 8 min). The weighted Kappa factor showed fair agreement between the observational and direct measurement method for the arm (0.39) and back (0.47). The weighted Kappa factor for these methods was poor for the neck (0) and wrist (0) but the observed proportional agreement (P o ) was 0.78 for the neck and 0.83 for the wrist. The weighted Kappa factor between questionnaire and direct measurement showed poor or slight agreement (0) for different body segments in both cycle times. The results revealed moderate agreement between the observational tool and the direct measurement method, and poor agreement between the self-reported questionnaire and direct measurement. Practitioner Summary: This study provides risk exposure measurement by different common ergonomic methods in the field. The results help to develop valid measurements and improve exposure evaluation. Hence, the ergonomist/practitioners should apply the methods with caution, or at least knowing what the issues/errors are.

Measurement of Trailing Edge Noise Using Directional Array and Coherent Output Power Methods

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Brooks, Thomas F.

2002-01-01

The use of a directional (or phased) array of microphones for the measurement of trailing edge (TE) noise is described and tested. The capabilities of this method arc evaluated via measurements of TE noise from a NACA 63-215 airfoil model and from a cylindrical rod. This TE noise measurement approach is compared to one that is based on thc cross spectral analysis of output signals from a pair of microphones placed on opposite sides of an airframe model (COP method). Advantages and limitations of both methods arc examined. It is shown that the microphone array can accurately measures TE noise and captures its two-dimensional characteristic over a large frequency range for any TE configuration as long as noise contamination from extraneous sources is within bounds. The COP method is shown to also accurately measure TE noise but over a more limited frequency range that narrows for increased TE thickness. Finally, the applicability and generality of an airfoil self-noise prediction method was evaluated via comparison to the experimental data obtained using the COP and array measurement methods. The predicted and experimental results are shown to agree over large frequency ranges.

Comparison of two methods in deriving a short version of oral health-related quality of life measure.

PubMed

Saub, R; Locker, D; Allison, P

2008-09-01

To compare two methods of developing short forms of the Malaysian Oral Health Impact Profile (OHIP-M) measure. Cross sectional data obtained using the long form of the OHIP-M was used to produce two types of OHIP-M short forms, derived using two different methods; namely regression and item frequency methods. The short version derived using a regression method is known as Reg-SOHIP(M) and that derived using a frequency method is known as Freq-SOHIP(M). Both short forms contained 14 items. These two forms were then compared in terms of their content, scores, reliability, validity and the ability to distinguish between groups. Out of 14 items, only four were in common. The form derived from the frequency method contained more high prevalence items and higher scores than the form derived from the regression method. Both methods produced a reliable and valid measure. However, the frequency method produced a measure, which was slightly better in terms of distinguishing between groups. Regardless of the method used to produce the measures, both forms performed equally well when tested for their cross-sectional psychometric properties.

Automatic tracking of labeled red blood cells in microchannels.

PubMed

Pinho, Diana; Lima, Rui; Pereira, Ana I; Gayubo, Fernando

2013-09-01

The current study proposes an automatic method for the segmentation and tracking of red blood cells flowing through a 100- μm glass capillary. The original images were obtained by means of a confocal system and then processed in MATLAB using the Image Processing Toolbox. The measurements obtained with the proposed automatic method were compared with the results determined by a manual tracking method. The comparison was performed by using both linear regressions and Bland-Altman analysis. The results have shown a good agreement between the two methods. Therefore, the proposed automatic method is a powerful way to provide rapid and accurate measurements for in vitro blood experiments in microchannels. Copyright © 2012 John Wiley & Sons, Ltd.

What are validated self-report adherence scales really measuring?: a systematic review

PubMed Central

Nguyen, Thi-My-Uyen; Caze, Adam La; Cottrell, Neil

2014-01-01

Aims Medication non-adherence is a significant health problem. There are numerous methods for measuring adherence, but no single method performs well on all criteria. The purpose of this systematic review is to (i) identify self-report medication adherence scales that have been correlated with comparison measures of medication-taking behaviour, (ii) assess how these scales measure adherence and (iii) explore how these adherence scales have been validated. Methods Cinahl and PubMed databases were used to search articles written in English on the development or validation of medication adherence scales dating to August 2012. The search terms used were medication adherence, medication non-adherence, medication compliance and names of each scale. Data such as barriers identified and validation comparison measures were extracted and compared. Results Sixty articles were included in the review, which consisted of 43 adherence scales. Adherence scales include items that either elicit information regarding the patient's medication-taking behaviour and/or attempts to identify barriers to good medication-taking behaviour or beliefs associated with adherence. The validation strategies employed depended on whether the focus of the scale was to measure medication-taking behaviour or identify barriers or beliefs. Conclusions Supporting patients to be adherent requires information on their medication-taking behaviour, barriers to adherence and beliefs about medicines. Adherence scales have the potential to explore these aspects of adherence, but currently there has been a greater focus on measuring medication-taking behaviour. Selecting the ‘right’ adherence scale(s) requires consideration of what needs to be measured and how (and in whom) the scale has been validated. PMID:23803249

Comparison of different methods for the in situ measurement of forest litter moisture content

NASA Astrophysics Data System (ADS)

Schunk, C.; Ruth, B.; Leuchner, M.; Wastl, C.; Menzel, A.

2016-02-01

Dead fine fuel (e.g., litter) moisture content is an important parameter for both forest fire and ecological applications as it is related to ignitability, fire behavior and soil respiration. Real-time availability of this value would thus be a great benefit to fire risk management and prevention. However, the comprehensive literature review in this paper shows that there is no easy-to-use method for automated measurements available. This study investigates the applicability of four different sensor types (permittivity and electrical resistance measuring principles) for this measurement. Comparisons were made to manual gravimetric reference measurements carried out almost daily for one fire season and overall agreement was good (highly significant correlations with 0.792 < = r < = 0.947, p < 0.001). Standard deviations within sensor types were linearly correlated to daily sensor mean values; however, above a certain threshold they became irregular, which may be linked to exceedance of the working ranges. Thus, measurements with irregular standard deviations were considered unusable and relationships between gravimetric and automatic measurements of all individual sensors were compared only for useable periods. A large drift in these relationships became obvious from drought to drought period. This drift may be related to installation effects or settling and decomposition of the litter layer throughout the fire season. Because of the drift and the in situ calibration necessary, it cannot be recommended to use the methods presented here for monitoring purposes and thus operational hazard management. However, they may be interesting for scientific studies when some manual fuel moisture measurements are made anyway. Additionally, a number of potential methodological improvements are suggested.

Toward Quantifying the Aesthetic Outcomes of Breast Cancer Treatment: Comparison of Clinical Photography and Colorimetry

PubMed Central

Kim, Min Soon; Rodney, William N.; Cooper, Tara; Kite, Chris; Reece, Gregory P.; Markey, Mia K.

2011-01-01

Rationale, aims and objectives Scarring is a significant cause of dissatisfaction for women who undergo breast surgery. Scar tissue may be clinically distinguished from normal skin by aberrant color, rough surface texture, increased thickness (hypertrophy), and firmness. Colorimeters or spectrophotometers can be used to quantitatively assess scar color, but they require direct patient interaction and can cost thousands of dollars By comparison, digital photography is already in widespread use to document clinical outcomes and requires less patient interaction. Thus, assessment of scar coloration by digital photography is an attractive alternative. The goal of this study was to compare color measurements obtained by digital photography and colorimetry. Method Agreement between photographic and colorimetric measurements of color were evaluated. Experimental conditions were controlled by performing measurements on artificial scars created by a makeup artist. The colorimetric measurements of the artificial scars were compared to those reported in the literature for real scars in order to confirm the validity of this approach. We assessed the agreement between the colorimetric and photographic measurements of color using a hypothesis test for equivalence, the intra-class correlation coefficient (ICC), and the Bland-Altman method. Results Overall, good agreement was obtained for three parameters (L*a*b*) measured by colorimetry and photography from the results of three statistical analyses. Conclusion Color measurements obtained by digital photography were equivalent to those obtained using colorimetry. Thus, digital photography is a reliable, cost-effective measurement method of skin color and should be further investigated for quantitative analysis of surgical outcomes. PMID:19239578