Science.gov

Sample records for accurate volume measurements

  1. Accurately measuring volume of soil samples using low cost Kinect 3D scanner

    NASA Astrophysics Data System (ADS)

    van der Sterre, Boy-Santhos; Hut, Rolf; van de Giesen, Nick

    2013-04-01

    The 3D scanner of the Kinect game controller can be used to increase the accuracy and efficiency of determining in situ soil moisture content. Soil moisture is one of the principal hydrological variables in both the water and energy interactions between soil and atmosphere. Current in situ measurements of soil moisture either rely on indirect measurements (of electromagnetic constants or heat capacity) or on physically taking a sample and weighing it in a lab. The bottleneck in accurately retrieving soil moisture using samples is the determining of the volume of the sample. Currently this is mostly done by the very time consuming "sand cone method" in which the volume were the sample used to sit is filled with sand. We show that 3D scanner that is part of the 150 game controller extension "Kinect" can be used to make 3D scans before and after taking the sample. The accuracy of this method is tested by scanning forms of known volume. This method is less time consuming and less error-prone than using a sand cone.

  2. Accurately measuring volume of soil samples using low cost Kinect 3D scanner

    NASA Astrophysics Data System (ADS)

    van der Sterre, B.; Hut, R.; Van De Giesen, N.

    2012-12-01

    The 3D scanner of the Kinect game controller can be used to increase the accuracy and efficiency of determining in situ soil moisture content. Soil moisture is one of the principal hydrological variables in both the water and energy interactions between soil and atmosphere. Current in situ measurements of soil moisture either rely on indirect measurements (of electromagnetic constants or heat capacity) or on physically taking a sample and weighing it in a lab. The bottleneck in accurately retrieving soil moisture using samples is the determining of the volume of the sample. Currently this is mostly done by the very time consuming "sand cone method" in which the volume were the sample used to sit is filled with sand. We show that 3D scanner that is part of the $150 game controller extension "Kinect" can be used to make 3D scans before and after taking the sample. The accuracy of this method is tested by scanning forms of known volume. This method is less time consuming and less error-prone than using a sand cone.

  3. Archimedes Revisited: A Faster, Better, Cheaper Method of Accurately Measuring the Volume of Small Objects

    ERIC Educational Resources Information Center

    Hughes, Stephen W.

    2005-01-01

    A little-known method of measuring the volume of small objects based on Archimedes' principle is described, which involves suspending an object in a water-filled container placed on electronic scales. The suspension technique is a variation on the hydrostatic weighing technique used for measuring volume. The suspension method was compared with two…

  4. Reliable and Accurate Calcium Volume Measurement in Coronary Artery Using Intravascular Ultrasound Videos.

    PubMed

    Araki, Tadashi; Banchhor, Sumit K; Londhe, Narendra D; Ikeda, Nobutaka; Radeva, Petia; Shukla, Devarshi; Saba, Luca; Balestrieri, Antonella; Nicolaides, Andrew; Shafique, Shoaib; Laird, John R; Suri, Jasjit S

    2016-03-01

    Quantitative assessment of calcified atherosclerotic volume within the coronary artery wall is vital for cardiac interventional procedures. The goal of this study is to automatically measure the calcium volume, given the borders of coronary vessel wall for all the frames of the intravascular ultrasound (IVUS) video. Three soft computing fuzzy classification techniques were adapted namely Fuzzy c-Means (FCM), K-means, and Hidden Markov Random Field (HMRF) for automated segmentation of calcium regions and volume computation. These methods were benchmarked against previously developed threshold-based method. IVUS image data sets (around 30,600 IVUS frames) from 15 patients were collected using 40 MHz IVUS catheter (Atlantis® SR Pro, Boston Scientific®, pullback speed of 0.5 mm/s). Calcium mean volume for FCM, K-means, HMRF and threshold-based method were 37.84 ± 17.38 mm(3), 27.79 ± 10.94 mm(3), 46.44 ± 19.13 mm(3) and 35.92 ± 16.44 mm(3) respectively. Cross-correlation, Jaccard Index and Dice Similarity were highest between FCM and threshold-based method: 0.99, 0.92 ± 0.02 and 0.95 + 0.02 respectively. Student's t-test, z-test and Wilcoxon-test are also performed to demonstrate consistency, reliability and accuracy of the results. Given the vessel wall region, the system reliably and automatically measures the calcium volume in IVUS videos. Further, we validated our system against a trained expert using scoring: K-means showed the best performance with an accuracy of 92.80%. Out procedure and protocol is along the line with method previously published clinically. PMID:26643081

  5. Can endocranial volume be estimated accurately from external skull measurements in great-tailed grackles (Quiscalus mexicanus)?

    PubMed

    Logan, Corina J; Palmstrom, Christin R

    2015-01-01

    There is an increasing need to validate and collect data approximating brain size on individuals in the field to understand what evolutionary factors drive brain size variation within and across species. We investigated whether we could accurately estimate endocranial volume (a proxy for brain size), as measured by computerized tomography (CT) scans, using external skull measurements and/or by filling skulls with beads and pouring them out into a graduated cylinder for male and female great-tailed grackles. We found that while females had higher correlations than males, estimations of endocranial volume from external skull measurements or beads did not tightly correlate with CT volumes. We found no accuracy in the ability of external skull measures to predict CT volumes because the prediction intervals for most data points overlapped extensively. We conclude that we are unable to detect individual differences in endocranial volume using external skull measurements. These results emphasize the importance of validating and explicitly quantifying the predictive accuracy of brain size proxies for each species and each sex. PMID:26082858

  6. Accurate measurement of time

    NASA Astrophysics Data System (ADS)

    Itano, Wayne M.; Ramsey, Norman F.

    1993-07-01

    The paper discusses current methods for accurate measurements of time by conventional atomic clocks, with particular attention given to the principles of operation of atomic-beam frequency standards, atomic hydrogen masers, and atomic fountain and to the potential use of strings of trapped mercury ions as a time device more stable than conventional atomic clocks. The areas of application of the ultraprecise and ultrastable time-measuring devices that tax the capacity of modern atomic clocks include radio astronomy and tests of relativity. The paper also discusses practical applications of ultraprecise clocks, such as navigation of space vehicles and pinpointing the exact position of ships and other objects on earth using the GPS.

  7. Accurate quantitative measurements of brachial artery cross-sectional vascular area and vascular volume elastic modulus using automated oscillometric measurements: comparison with brachial artery ultrasound

    PubMed Central

    Tomiyama, Yuuki; Yoshinaga, Keiichiro; Fujii, Satoshi; Ochi, Noriki; Inoue, Mamiko; Nishida, Mutumi; Aziki, Kumi; Horie, Tatsunori; Katoh, Chietsugu; Tamaki, Nagara

    2015-01-01

    Increasing vascular diameter and attenuated vascular elasticity may be reliable markers for atherosclerotic risk assessment. However, previous measurements have been complex, operator-dependent or invasive. Recently, we developed a new automated oscillometric method to measure a brachial artery's estimated area (eA) and volume elastic modulus (VE). The aim of this study was to investigate the reliability of new automated oscillometric measurement of eA and VE. Rest eA and VE were measured using the recently developed automated detector with the oscillometric method. eA was estimated using pressure/volume curves and VE was defined as follows (VE=Δ pressure/ (100 × Δ area/area) mm Hg/%). Sixteen volunteers (age 35.2±13.1 years) underwent the oscillometric measurements and brachial ultrasound at rest and under nitroglycerin (NTG) administration. Oscillometric measurement was performed twice on different days. The rest eA correlated with ultrasound-measured brachial artery area (r=0.77, P<0.001). Rest eA and VE measurement showed good reproducibility (eA: intraclass correlation coefficient (ICC)=0.88, VE: ICC=0.78). Under NTG stress, eA was significantly increased (12.3±3.0 vs. 17.1±4.6 mm2, P<0.001), and this was similar to the case with ultrasound evaluation (4.46±0.72 vs. 4.73±0.75 mm, P<0.001). VE was also decreased (0.81±0.16 vs. 0.65±0.11 mm Hg/%, P<0.001) after NTG. Cross-sectional vascular area calculated using this automated oscillometric measurement correlated with ultrasound measurement and showed good reproducibility. Therefore, this is a reliable approach and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings. PMID:25693851

  8. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  9. Robust, accurate, and non-contacting vibration measurement systems: Supplemental appendices presenting comparison measurements of the robust laser interferometer and typical accelerometer systems. Volume 2

    SciTech Connect

    Goodenow, T.C.; Shipman, R.L.; Holland, H.M.

    1995-06-01

    Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer-based instrumentation systems. EEI has successfully demonstrated, on several pieces of commonplace machinery, that non-contact, line-of-sight measurements are practical and yield results equal to or, in some cases, better than customary field implementations of accelerometers. The demonstration included analysis and comparison of such phenomena as nonlinearity, transverse sensitivity, harmonics, and signal-to-noise ratio. Fast Fourier Transformations were performed on the accelerometer and the laser system outputs to provide a comparison basis. The RLI was demonstrated, within the limits o the task, to be a viable, line-of-sight, non-contact alternative to accelerometer systems. Several different kinds of machinery were instrumented and. compared, including a small pump, a gear-driven cement mixer, a rotor kit, and two small fans. Known machinery vibration sources were verified and RLI system output file formats were verified to be compatible with commercial computer programs used for vibration monitoring and trend analysis. The RLI was also observed to be less subject to electromagnetic interference (EMI) and more capable at very low frequencies. This document, Volume 2, provides the appendices to this report.

  10. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  11. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  12. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  13. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  14. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  15. Robust, accurate, and non-contacting vibration measurement systems: Summary of comparison measurements of the robust laser interferometer and typical accelerometer systems. Volume 1

    SciTech Connect

    Goodenow, T.C.; Shipman, R.L.; Holland, H.M.

    1995-06-01

    Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer-based instrumentation systems. EEI has successfully demonstrated, on several pieces of commonplace machinery, that non-contact, line-of-sight measurements are practical and yield results equal to or, in some cases, better than customary field implementations of accelerometers. The demonstration included analysis and comparison of such phenomena as nonlinearity, transverse sensitivity, harmonics, and signal-to-noise ratio. Fast Fourier Transformations were performed on the accelerometer and the laser system outputs to provide a comparison basis. The RLI was demonstrated, within the limits of the task, to be a viable, line-of-sight, non-contact alternative to accelerometer systems. Several different kinds of machinery were instrumented and compared, including a small pump, a gear-driven cement mixer, a rotor kit, and two small fans. Known machinery vibration sources were verified and RLI system output file formats were verified to be compatible with commercial computer programs used for vibration monitoring and trend analysis. The RLI was also observed to be less subject to electromagnetic interference (EMI) and more capable at very low frequencies.

  16. Accurate Mass Measurements in Proteomics

    SciTech Connect

    Liu, Tao; Belov, Mikhail E.; Jaitly, Navdeep; Qian, Weijun; Smith, Richard D.

    2007-08-01

    To understand different aspects of life at the molecular level, one would think that ideally all components of specific processes should be individually isolated and studied in details. Reductionist approaches, i.e., studying one biological event at a one-gene or one-protein-at-a-time basis, indeed have made significant contributions to our understanding of many basic facts of biology. However, these individual “building blocks” can not be visualized as a comprehensive “model” of the life of cells, tissues, and organisms, without using more integrative approaches.1,2 For example, the emerging field of “systems biology” aims to quantify all of the components of a biological system to assess their interactions and to integrate diverse types of information obtainable from this system into models that could explain and predict behaviors.3-6 Recent breakthroughs in genomics, proteomics, and bioinformatics are making this daunting task a reality.7-14 Proteomics, the systematic study of the entire complement of proteins expressed by an organism, tissue, or cell under a specific set of conditions at a specific time (i.e., the proteome), has become an essential enabling component of systems biology. While the genome of an organism may be considered static over short timescales, the expression of that genome as the actual gene products (i.e., mRNAs and proteins) is a dynamic event that is constantly changing due to the influence of environmental and physiological conditions. Exclusive monitoring of the transcriptomes can be carried out using high-throughput cDNA microarray analysis,15-17 however the measured mRNA levels do not necessarily correlate strongly with the corresponding abundances of proteins,18-20 The actual amount of functional proteins can be altered significantly and become independent of mRNA levels as a result of post-translational modifications (PTMs),21 alternative splicing,22,23 and protein turnover.24,25 Moreover, the functions of expressed

  17. Chemical measurement of urine volume

    NASA Technical Reports Server (NTRS)

    Sauer, R. L.

    1978-01-01

    Chemical method of measuring volume of urine samples using lithium chloride dilution technique, does not interfere with analysis, is faster, and more accurate than standard volumetric of specific gravity/weight techniques. Adaptation of procedure to urinalysis could prove generally practical for hospital mineral balance and catechoamine determinations.

  18. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2016-07-01

    In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.

  19. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  20. Interactive Isogeometric Volume Visualization with Pixel-Accurate Geometry.

    PubMed

    Fuchs, Franz G; Hjelmervik, Jon M

    2016-02-01

    A recent development, called isogeometric analysis, provides a unified approach for design, analysis and optimization of functional products in industry. Traditional volume rendering methods for inspecting the results from the numerical simulations cannot be applied directly to isogeometric models. We present a novel approach for interactive visualization of isogeometric analysis results, ensuring correct, i.e., pixel-accurate geometry of the volume including its bounding surfaces. The entire OpenGL pipeline is used in a multi-stage algorithm leveraging techniques from surface rendering, order-independent transparency, as well as theory and numerical methods for ordinary differential equations. We showcase the efficiency of our approach on different models relevant to industry, ranging from quality inspection of the parametrization of the geometry, to stress analysis in linear elasticity, to visualization of computational fluid dynamics results. PMID:26731454

  1. More Accurate Definition of Clinical Target Volume Based on the Measurement of Microscopic Extensions of the Primary Tumor Toward the Uterus Body in International Federation of Gynecology and Obstetrics Ib-IIa Squamous Cell Carcinoma of the Cervix

    SciTech Connect

    Xie, Wen-Jia; Wu, Xiao; Xue, Ren-Liang; Lin, Xiang-Ying; Kidd, Elizabeth A.; Yan, Shu-Mei; Zhang, Yao-Hong; Zhai, Tian-Tian; Lu, Jia-Yang; Wu, Li-Li; Zhang, Hao; Huang, Hai-Hua; Chen, Zhi-Jian; Li, De-Rui; Xie, Liang-Xi

    2015-01-01

    Purpose: To more accurately define clinical target volume for cervical cancer radiation treatment planning by evaluating tumor microscopic extension toward the uterus body (METU) in International Federation of Gynecology and Obstetrics stage Ib-IIa squamous cell carcinoma of the cervix (SCCC). Patients and Methods: In this multicenter study, surgical resection specimens from 318 cases of stage Ib-IIa SCCC that underwent radical hysterectomy were included. Patients who had undergone preoperative chemotherapy, radiation, or both were excluded from this study. Microscopic extension of primary tumor toward the uterus body was measured. The association between other pathologic factors and METU was analyzed. Results: Microscopic extension toward the uterus body was not common, with only 12.3% of patients (39 of 318) demonstrating METU. The mean (±SD) distance of METU was 0.32 ± 1.079 mm (range, 0-10 mm). Lymphovascular space invasion was associated with METU distance and occurrence rate. A margin of 5 mm added to gross tumor would adequately cover 99.4% and 99% of the METU in the whole group and in patients with lymphovascular space invasion, respectively. Conclusion: According to our analysis of 318 SCCC specimens for METU, using a 5-mm gross tumor volume to clinical target volume margin in the direction of the uterus should be adequate for International Federation of Gynecology and Obstetrics stage Ib-IIa SCCC. Considering the discrepancy between imaging and pathologic methods in determining gross tumor volume extent, we recommend a safer 10-mm margin in the uterine direction as the standard for clinical practice when using MRI for contouring tumor volume.

  2. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, Douglas D.

    1985-01-01

    The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  3. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, D.D.

    The present invention is a thermometer used for measuring furnace temperatures in the range of about 1800/sup 0/ to 2700/sup 0/C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  4. Fast and Accurate Exhaled Breath Ammonia Measurement

    PubMed Central

    Solga, Steven F.; Mudalel, Matthew L.; Spacek, Lisa A.; Risby, Terence H.

    2014-01-01

    This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations. PMID:24962141

  5. Highly accurate articulated coordinate measuring machine

    DOEpatents

    Bieg, Lothar F.; Jokiel, Jr., Bernhard; Ensz, Mark T.; Watson, Robert D.

    2003-12-30

    Disclosed is a highly accurate articulated coordinate measuring machine, comprising a revolute joint, comprising a circular encoder wheel, having an axis of rotation; a plurality of marks disposed around at least a portion of the circumference of the encoder wheel; bearing means for supporting the encoder wheel, while permitting free rotation of the encoder wheel about the wheel's axis of rotation; and a sensor, rigidly attached to the bearing means, for detecting the motion of at least some of the marks as the encoder wheel rotates; a probe arm, having a proximal end rigidly attached to the encoder wheel, and having a distal end with a probe tip attached thereto; and coordinate processing means, operatively connected to the sensor, for converting the output of the sensor into a set of cylindrical coordinates representing the position of the probe tip relative to a reference cylindrical coordinate system.

  6. Accurate Measurement of Bone Density with QCT

    NASA Technical Reports Server (NTRS)

    Cleek, Tammy M.; Beaupre, Gary S.; Matsubara, Miki; Whalen, Robert T.; Dalton, Bonnie P. (Technical Monitor)

    2002-01-01

    The objective of this study was to determine the accuracy of bone density measurement with a new OCT technology. A phantom was fabricated using two materials, a water-equivalent compound and hydroxyapatite (HA), combined in precise proportions (QRM GrnbH, Germany). The phantom was designed to have the approximate physical size and range in bone density as a human calcaneus, with regions of 0, 50, 100, 200, 400, and 800 mg/cc HA. The phantom was scanned at 80, 120 and 140 KVp with a GE CT/i HiSpeed Advantage scanner. A ring of highly attenuating material (polyvinyl chloride or teflon) was slipped over the phantom to alter the image by introducing non-axi-symmetric beam hardening. Images were corrected with a new OCT technology using an estimate of the effective X-ray beam spectrum to eliminate beam hardening artifacts. The algorithm computes the volume fraction of HA and water-equivalent matrix in each voxel. We found excellent agreement between expected and computed HA volume fractions. Results were insensitive to beam hardening ring material, HA concentration, and scan voltage settings. Data from all 3 voltages with a best fit linear regression are displays.

  7. Mining volume measurement system

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph Saul (Inventor)

    1988-01-01

    In a shaft with a curved or straight primary segment and smaller off-shooting segments, at least one standing wave is generated in the primary segment. The shaft has either an open end or a closed end and approximates a cylindrical waveguide. A frequency of a standing wave that represents the fundamental mode characteristic of the primary segment can be measured. Alternatively, a frequency differential between two successive harmonic modes that are characteristic of the primary segment can be measured. In either event, the measured frequency or frequency differential is characteristic of the length and thus the volume of the shaft based on length times the bore area.

  8. Accurate measure by weight of liquids in industry

    SciTech Connect

    Muller, M.R.

    1992-12-12

    This research's focus was to build a prototype of a computerized liquid dispensing system. This liquid metering system is based on the concept of altering the representative volume to account for temperature changes in the liquid to be dispensed. This is actualized by using a measuring tank and a temperature compensating displacement plunger. By constantly monitoring the temperature of the liquid, the plunger can be used to increase or decrease the specified volume to more accurately dispense liquid with a specified mass. In order to put the device being developed into proper engineering perspective, an extensive literature review was undertaken on all areas of industrial metering of liquids with an emphasis on gravimetric methods.

  9. Accurate measure by weight of liquids in industry. Final report

    SciTech Connect

    Muller, M.R.

    1992-12-12

    This research`s focus was to build a prototype of a computerized liquid dispensing system. This liquid metering system is based on the concept of altering the representative volume to account for temperature changes in the liquid to be dispensed. This is actualized by using a measuring tank and a temperature compensating displacement plunger. By constantly monitoring the temperature of the liquid, the plunger can be used to increase or decrease the specified volume to more accurately dispense liquid with a specified mass. In order to put the device being developed into proper engineering perspective, an extensive literature review was undertaken on all areas of industrial metering of liquids with an emphasis on gravimetric methods.

  10. Simple, accurate temperature-measuring instrument

    NASA Technical Reports Server (NTRS)

    Mc Fadin, L. W.

    1970-01-01

    Compact instrument, composed of integrated circuits and a temperature-sensitive platinum resistor, measures temperature over a wide dynamic range. Ultimate accuracy is limited by nonlinearity of the platinum resistor. With proper calibration and current regulation to within 0.01 percent, a measurement accuracy of 0.05 percent can be achieved.

  11. Considerations for Accurate Whole Plant Photosynthesis Measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole plant photosynthetic rate (Pn) measurements provide an integral assessment of how an entire plant responds to biotic and abitics factors. Pn determination is based on measurements of CO2 exchange rates (CER) using various types of system including Closed, Semi-closed, and Open systems. This ...

  12. Accurate Measurement of Organic Solar Cell Efficiency

    SciTech Connect

    Emery, K.; Moriarty, T.

    2008-01-01

    We discuss the measurement and analysis of current vs. voltage (I-V) characteristics of organic and dye-sensitized photovoltaic cells and modules. A brief discussion of the history of photovoltaic efficiency measurements and procedures will be presented. We discuss both the error sources in the measurements and the strategies to minimize their influence. These error sources include the sample area, spectral errors, temperature fluctuations, current and voltage response time, contacting, and degradation during testing. Information that can be extracted from light and dark I-V measurement includes peak power, open-circuit voltage, short-circuit current, series and shunt resistance, diode quality factor, dark current, and photo-current. The quantum efficiency provides information on photo-current nonlinearities, current generation, and recombination mechanisms.

  13. Development of limb volume measuring system

    NASA Technical Reports Server (NTRS)

    Bhagat, P. K.; Kadaba, P. K.

    1983-01-01

    The mechanisms underlying the reductions in orthostatic tolerance associated with weightlessness are not well established. Contradictory results from measurements of leg volume changes suggest that altered venomotor tone and reduced blood flow may not be the only contributors to orthostatic intolerance. It is felt that a more accurate limb volume system which is insensitive to environmental factors will aid in better quantification of the hemodynamics of the leg. Of the varous limb volume techniques presently available, the ultrasonic limb volume system has proven to be the best choice. The system as described herein is free from environmental effects, safe, simple to operate and causes negligible radio frequency interference problems. The segmental ultrasonic ultrasonic plethysmograph is expected to provide a better measurement of limb volume change since it is based on cross-sectional area measurements.

  14. Stereometric body volume measurement

    NASA Technical Reports Server (NTRS)

    Herron, R. E.

    1975-01-01

    The following studies are reported: (1) effects of extended space flight on body form of Skylab astronauts using biostereometrics; (2) comparison of body volume determinations using hydrostatic weighing and biostereometrics; and (3) training of technicians in biostereometric principles and procedures.

  15. Microbalance accurately measures extremely small masses

    NASA Technical Reports Server (NTRS)

    Patashnick, H.

    1970-01-01

    Oscillating fiber microbalance has a vibrating quartz fiber as balance arm to hold the mass to be weighed. Increasing fiber weight decreases its resonant frequency. Scaler and timer measure magnitude of the shift. This instrument withstands considerable physical abuse and has calibration stability at normal room temperatures.

  16. Accurate temperature measurements with a degrading thermocouple

    SciTech Connect

    Skripnik, Y.A.; Khimicheva, A.I.

    1995-04-01

    Ways are considered of enhancing the accuracy of thermoelectric measurement of temperature. The high accuracy method proposed for monitoring the temperature of an aggressive medium can determine the temperature, irrespective of the instantaneous values of the Seebeck and Peltier coefficients, i.e., irrespective of the uncontrolled thermocouple sensitivity, which varies during use.

  17. Modified algesimeter provides accurate depth measurements

    NASA Technical Reports Server (NTRS)

    Turner, D. P.

    1966-01-01

    Algesimeter which incorporates a standard sensory needle with a sensitive micrometer, measures needle point depth penetration in pain tolerance research. This algesimeter provides an inexpensive, precise instrument with assured validity of recordings in those biomedical areas with a requirement for repeated pain detection or ascertaining pain sensitivity.

  18. Instrument accurately measures weld angle and offset

    NASA Technical Reports Server (NTRS)

    Boyd, W. G.

    1967-01-01

    Weld angle is measured to the nearest arc minute and offset to one thousandth of an inch by an instrument designed to use a reference plane at two locations on a test coupon. A special table for computation has been prepared for use with the instrument.

  19. Air brake-dynamometer accurately measures torque

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Air brake-dynamometer assembly combines the principles of the air turbine and the air pump to apply braking torque. The assembly absorbs and measures power outputs of rotating machinery over a wide range of shaft speeds. It can also be used as an air turbine.

  20. EMR Gage Would Measure Coal Thickness Accurately

    NASA Technical Reports Server (NTRS)

    King, J. D.; Rollwitz, W. L.

    1982-01-01

    Laboratory tests indicate electron magnetic resonance (EMR) would be effective in measuring thickness of coal overlying rock substrate. In prototype dual-frequency EMR system, Sample is irradiated by two radio frequencies. Signals are mixed, producing sum and difference output frequencies that are detected by receiver. Magnetic field is varied to scan resonant spot through sample. In system designed for field use, electromagnet is U-shaped, so that sample can be adjacent to, rather than inside the probe. Same coil is used for transmitting and receiving.

  1. Volume measuring system

    NASA Technical Reports Server (NTRS)

    Oele, J. S.

    1975-01-01

    Chamber is designed to be airtight; it includes face mask for person to breathe outside air so that he does not disturb chamber environment. Chamber includes piston to vary air volume inside. Also included are two microphone transducers which record pressure information inside chamber.

  2. Accurate Determination of the Volume of an Irregular Helium Balloon

    ERIC Educational Resources Information Center

    Blumenthal, Jack; Bradvica, Rafaela; Karl, Katherine

    2013-01-01

    In a recent paper, Zable described an experiment with a near-spherical balloon filled with impure helium. Measuring the temperature and the pressure inside and outside the balloon, the lift of the balloon, and the mass of the balloon materials, he described how to use the ideal gas laws and Archimedes' principal to compute the average molecular…

  3. Accurate Fiber Length Measurement Using Time-of-Flight Technique

    NASA Astrophysics Data System (ADS)

    Terra, Osama; Hussein, Hatem

    2016-06-01

    Fiber artifacts of very well-measured length are required for the calibration of optical time domain reflectometers (OTDR). In this paper accurate length measurement of different fiber lengths using the time-of-flight technique is performed. A setup is proposed to measure accurately lengths from 1 to 40 km at 1,550 and 1,310 nm using high-speed electro-optic modulator and photodetector. This setup offers traceability to the SI unit of time, the second (and hence to meter by definition), by locking the time interval counter to the Global Positioning System (GPS)-disciplined quartz oscillator. Additionally, the length of a recirculating loop artifact is measured and compared with the measurement made for the same fiber by the National Physical Laboratory of United Kingdom (NPL). Finally, a method is proposed to relatively correct the fiber refractive index to allow accurate fiber length measurement.

  4. VOLUMNECT: measuring volumes with Kinect

    NASA Astrophysics Data System (ADS)

    Quintino Ferreira, Beatriz; Griné, Miguel; Gameiro, Duarte; Costeira, João. Paulo; Sousa Santos, Beatriz

    2014-03-01

    This article presents a solution to volume measurement object packing using 3D cameras (such as the Microsoft KinectTM). We target application scenarios, such as warehouses or distribution and logistics companies, where it is important to promptly compute package volumes, yet high accuracy is not pivotal. Our application auto- matically detects cuboid objects using the depth camera data and computes their volume and sorting it allowing space optimization. The proposed methodology applies to a point cloud simple computer vision and image processing methods, as connected components, morphological operations and Harris corner detector, producing encouraging results, namely an accuracy in volume measurement of 8mm. Aspects that can be further improved are identified; nevertheless, the current solution is already promising turning out to be cost effective for the envisaged scenarios.

  5. Volumetric measurement of tank volume

    NASA Technical Reports Server (NTRS)

    Walter, Richard T. (Inventor); Vanbuskirk, Paul D. (Inventor); Weber, William F. (Inventor); Froebel, Richard C. (Inventor)

    1991-01-01

    A method is disclosed for determining the volume of compressible gas in a system including incompressible substances in a zero-gravity environment consisting of measuring the change in pressure (delta P) for a known volume change rate (delta V/delta t) in the polytrophic region between isothermal and adiabatic conditions. The measurements are utilized in an idealized formula for determining the change in isothermal pressure (delta P sub iso) for the gas. From the isothermal pressure change (delta iso) the gas volume is obtained. The method is also applicable to determination of gas volume by utilizing work (W) in the compression process. In a passive system, the relationship of specific densities can be obtained.

  6. Sonographic measurement of gallbladder volume.

    PubMed

    Dodds, W J; Groh, W J; Darweesh, R M; Lawson, T L; Kishk, S M; Kern, M K

    1985-11-01

    Sonographic images of the gallbladder enable satisfactory approximation of gallbladder volume using the sum-of-cylinders method. The sum-of-cylinder measurements, however, are moderately cumbersome and time consuming to perform. In this investigation, in vitro and in vivo testing was done to determine that a simple ellipsoid method applied to sonographic gallbladder images yields reasonable volume approximations that are comparable to the volumes calculated by the sum-of-cylinders method. Findings from a water-bath experiment showed that measurement of gallbladder volume by the ellipsoid method closely approximated the true volume with a mean difference of about 1.0 ml. The results of in vivo studies in five volunteers demonstrated that the gallbladder contracted substantially after a fatty meal and that volumes calculated by the ellipsoid and sum-of-cylinders methods were nearly identical. Thus, a simple ellipsoid method, requiring negligible time, may be used to approximate satisfactory gallbladder volume for clinical or investigative studies. PMID:3901703

  7. Cerebrospinal fluid volume measurements in hydrocephalic rats.

    PubMed

    Basati, Sukhraaj; Desai, Bhargav; Alaraj, Ali; Charbel, Fady; Linninger, Andreas

    2012-10-01

    Object Experimental data about the evolution of intracranial volume and pressure in cases of hydrocephalus are limited due to the lack of available monitoring techniques. In this study, the authors validate intracranial CSF volume measurements within the lateral ventricle, while simultaneously using impedance sensors and pressure transducers in hydrocephalic animals. Methods A volume sensor was fabricated and connected to a catheter that was used as a shunt to withdraw CSF. In vitro bench-top calibration experiments were created to provide data for the animal experiments and to validate the sensors. To validate the measurement technique in a physiological system, hydrocephalus was induced in weanling rats by kaolin injection into the cisterna magna. At 28 days after induction, the sensor was implanted into the lateral ventricles. After sealing the skull using dental cement, an acute CSF drainage/infusion protocol consisting of 4 sequential phases was performed with a pump. Implant location was confirmed via radiography using intraventricular iohexol contrast administration. Results Controlled CSF shunting in vivo with hydrocephalic rats resulted in precise and accurate sensor measurements (r = 0.98). Shunting resulted in a 17.3% maximum measurement error between measured volume and actual volume as assessed by a Bland-Altman plot. A secondary outcome confirmed that both ventricular volume and intracranial pressure decreased during CSF shunting and increased during infusion. Ventricular enlargement consistent with successful hydrocephalus induction was confirmed using imaging, as well as postmortem. These results indicate that volume monitoring is feasible for clinical cases of hydrocephalus. Conclusions This work marks a departure from traditional shunting systems currently used to treat hydrocephalus. The overall clinical application is to provide alternative monitoring and treatment options for patients. Future work includes development and testing of a chronic

  8. A urine volume measurement system

    NASA Technical Reports Server (NTRS)

    Poppendiek, H. F.; Mouritzen, G.; Sabin, C. M.

    1972-01-01

    An improved urine volume measurement system for use in the unusual environment of manned space flight is reported. The system utilizes a low time-constant thermal flowmeter. The time integral of the transient response of the flowmeter gives the urine volume during a void as it occurs. In addition, the two phase flows through the flowmeter present no problem. Developments of the thermal flowmeter and a verification of the predicted performance characteristics are summarized.

  9. Accurate Insertion Loss Measurements of the Juno Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Chen, Jacqueline; Hodges, Richard; Demas, John

    2010-01-01

    This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.

  10. Accurate Measurements of the Local Deuterium Abundance from HST Spectra

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.

    1996-01-01

    An accurate measurement of the primordial value of D/H would provide a critical test of nucleosynthesis models for the early universe and the baryon density. I briefly summarize the ongoing HST observations of the interstellar H and D Lyman-alpha absorption for lines of sight to nearby stars and comment on recent reports of extragalactic D/H measurements.

  11. Monitoring circuit accurately measures movement of solenoid valve

    NASA Technical Reports Server (NTRS)

    Gillett, J. D.

    1966-01-01

    Solenoid operated valve in a control system powered by direct current issued to accurately measure the valve travel. This system is currently in operation with a 28-vdc power system used for control of fluids in liquid rocket motor test facilities.

  12. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  13. A Simple and Accurate Method for Measuring Enzyme Activity.

    ERIC Educational Resources Information Center

    Yip, Din-Yan

    1997-01-01

    Presents methods commonly used for investigating enzyme activity using catalase and presents a new method for measuring catalase activity that is more reliable and accurate. Provides results that are readily reproduced and quantified. Can also be used for investigations of enzyme properties such as the effects of temperature, pH, inhibitors,…

  14. Instrument accurately measures small temperature changes on test surface

    NASA Technical Reports Server (NTRS)

    Harvey, W. D.; Miller, H. B.

    1966-01-01

    Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material.

  15. Accurately measuring volcanic plume velocity with multiple UV spectrometers

    USGS Publications Warehouse

    Williams-Jones, G.; Horton, K.A.; Elias, T.; Garbeil, H.; Mouginis-Mark, P. J.; Sutton, A.J.; Harris, A.J.L.

    2006-01-01

    A fundamental problem with all ground-based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume. Since a representative wind speed and direction are used as proxies for the actual plume velocity, there can be considerable uncertainty in reported gas flux values. Here we present a method that uses at least two time-synchronized simultaneously recording UV spectrometers (FLYSPECs) placed a known distance apart. By analyzing the time varying structure of SO2 concentration signals at each instrument, the plume velocity can accurately be determined. Experiments were conducted on Ki??lauea (USA) and Masaya (Nicaragua) volcanoes in March and August 2003 at plume velocities between 1 and 10 m s-1. Concurrent ground-based anemometer measurements differed from FLYSPEC-measured plume speeds by up to 320%. This multi-spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements. ?? Springer-Verlag 2006.

  16. A unique approach to accurately measure thickness in thick multilayers.

    PubMed

    Shi, Bing; Hiller, Jon M; Liu, Yuzi; Liu, Chian; Qian, Jun; Gades, Lisa; Wieczorek, Michael J; Marander, Albert T; Maser, Jorg; Assoufid, Lahsen

    2012-05-01

    X-ray optics called multilayer Laue lenses (MLLs) provide a promising path to focusing hard X-rays with high focusing efficiency at a resolution between 5 nm and 20 nm. MLLs consist of thousands of depth-graded thin layers. The thickness of each layer obeys the linear zone plate law. X-ray beamline tests have been performed on magnetron sputter-deposited WSi(2)/Si MLLs at the Advanced Photon Source/Center for Nanoscale Materials 26-ID nanoprobe beamline. However, it is still very challenging to accurately grow each layer at the designed thickness during deposition; errors introduced during thickness measurements of thousands of layers lead to inaccurate MLL structures. Here, a new metrology approach that can accurately measure thickness by introducing regular marks on the cross section of thousands of layers using a focused ion beam is reported. This new measurement method is compared with a previous method. More accurate results are obtained using the new measurement approach. PMID:22514179

  17. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  18. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  19. A time accurate finite volume high resolution scheme for three dimensional Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Hsu, Andrew T.

    1989-01-01

    A time accurate, three-dimensional, finite volume, high resolution scheme for solving the compressible full Navier-Stokes equations is presented. The present derivation is based on the upwind split formulas, specifically with the application of Roe's (1981) flux difference splitting. A high-order accurate (up to the third order) upwind interpolation formula for the inviscid terms is derived to account for nonuniform meshes. For the viscous terms, discretizations consistent with the finite volume concept are described. A variant of second-order time accurate method is proposed that utilizes identical procedures in both the predictor and corrector steps. Avoiding the definition of midpoint gives a consistent and easy procedure, in the framework of finite volume discretization, for treating viscous transport terms in the curvilinear coordinates. For the boundary cells, a new treatment is introduced that not only avoids the use of 'ghost cells' and the associated problems, but also satisfies the tangency conditions exactly and allows easy definition of viscous transport terms at the first interface next to the boundary cells. Numerical tests of steady and unsteady high speed flows show that the present scheme gives accurate solutions.

  20. Accurate thermal expansivity measurements in the range 1500 2000 K are needed for minerals

    NASA Astrophysics Data System (ADS)

    Anderson, O. L.

    1991-07-01

    It is shown that the future high-temperature thermodynamic computations for minerals now hinge on the extension of the measurement of the volume thermal expansivity, β up to 2000 K. At present many measurements of β end at about 1200 1500 K, but the extrapolations to 2000 K are fraught with large errors. A few years ago, the missing thermodynamic parameter at high temperatures was the bulk modulus (or its reciprocal compressibility). Now that measurements of the bulk modulus are being accurately measured at 1800 K, attention is focused on improving measurements of β at higher temperatures.

  1. Accurate Automatic Delineation of Heterogeneous Functional Volumes in Positron Emission Tomography for Oncology Applications

    SciTech Connect

    Hatt, Mathieu; Cheze le Rest, Catherine; Descourt, Patrice; Dekker, Andre; De Ruysscher, Dirk; Oellers, Michel; Lambin, Philippe; Pradier, Olivier; Visvikis, Dimitris

    2010-05-01

    Purpose: Accurate contouring of positron emission tomography (PET) functional volumes is now considered crucial in image-guided radiotherapy and other oncology applications because the use of functional imaging allows for biological target definition. In addition, the definition of variable uptake regions within the tumor itself may facilitate dose painting for dosimetry optimization. Methods and Materials: Current state-of-the-art algorithms for functional volume segmentation use adaptive thresholding. We developed an approach called fuzzy locally adaptive Bayesian (FLAB), validated on homogeneous objects, and then improved it by allowing the use of up to three tumor classes for the delineation of inhomogeneous tumors (3-FLAB). Simulated and real tumors with histology data containing homogeneous and heterogeneous activity distributions were used to assess the algorithm's accuracy. Results: The new 3-FLAB algorithm is able to extract the overall tumor from the background tissues and delineate variable uptake regions within the tumors, with higher accuracy and robustness compared with adaptive threshold (T{sub bckg}) and fuzzy C-means (FCM). 3-FLAB performed with a mean classification error of less than 9% +- 8% on the simulated tumors, whereas binary-only implementation led to errors of 15% +- 11%. T{sub bckg} and FCM led to mean errors of 20% +- 12% and 17% +- 14%, respectively. 3-FLAB also led to more robust estimation of the maximum diameters of tumors with histology measurements, with <6% standard deviation, whereas binary FLAB, T{sub bckg} and FCM lead to 10%, 12%, and 13%, respectively. Conclusion: These encouraging results warrant further investigation in future studies that will investigate the impact of 3-FLAB in radiotherapy treatment planning, diagnosis, and therapy response evaluation.

  2. Accurate skin dose measurements using radiochromic film in clinical applications

    SciTech Connect

    Devic, S.; Seuntjens, J.; Abdel-Rahman, W.; Evans, M.; Olivares, M.; Podgorsak, E.B.; Vuong, Te; Soares, Christopher G.

    2006-04-15

    Megavoltage x-ray beams exhibit the well-known phenomena of dose buildup within the first few millimeters of the incident phantom surface, or the skin. Results of the surface dose measurements, however, depend vastly on the measurement technique employed. Our goal in this study was to determine a correction procedure in order to obtain an accurate skin dose estimate at the clinically relevant depth based on radiochromic film measurements. To illustrate this correction, we have used as a reference point a depth of 70 {mu}. We used the new GAFCHROMIC[reg] dosimetry films (HS, XR-T, and EBT) that have effective points of measurement at depths slightly larger than 70 {mu}. In addition to films, we also used an Attix parallel-plate chamber and a home-built extrapolation chamber to cover tissue-equivalent depths in the range from 4 {mu} to 1 mm of water-equivalent depth. Our measurements suggest that within the first millimeter of the skin region, the PDD for a 6 MV photon beam and field size of 10x10 cm{sup 2} increases from 14% to 43%. For the three GAFCHROMIC[reg] dosimetry film models, the 6 MV beam entrance skin dose measurement corrections due to their effective point of measurement are as follows: 15% for the EBT, 15% for the HS, and 16% for the XR-T model GAFCHROMIC[reg] films. The correction factors for the exit skin dose due to the build-down region are negligible. There is a small field size dependence for the entrance skin dose correction factor when using the EBT GAFCHROMIC[reg] film model. Finally, a procedure that uses EBT model GAFCHROMIC[reg] film for an accurate measurement of the skin dose in a parallel-opposed pair 6 MV photon beam arrangement is described.

  3. Accurate measurements of dynamics and reproducibility in small genetic networks

    PubMed Central

    Dubuis, Julien O; Samanta, Reba; Gregor, Thomas

    2013-01-01

    Quantification of gene expression has become a central tool for understanding genetic networks. In many systems, the only viable way to measure protein levels is by immunofluorescence, which is notorious for its limited accuracy. Using the early Drosophila embryo as an example, we show that careful identification and control of experimental error allows for highly accurate gene expression measurements. We generated antibodies in different host species, allowing for simultaneous staining of four Drosophila gap genes in individual embryos. Careful error analysis of hundreds of expression profiles reveals that less than ∼20% of the observed embryo-to-embryo fluctuations stem from experimental error. These measurements make it possible to extract not only very accurate mean gene expression profiles but also their naturally occurring fluctuations of biological origin and corresponding cross-correlations. We use this analysis to extract gap gene profile dynamics with ∼1 min accuracy. The combination of these new measurements and analysis techniques reveals a twofold increase in profile reproducibility owing to a collective network dynamics that relays positional accuracy from the maternal gradients to the pair-rule genes. PMID:23340845

  4. Technological Basis and Scientific Returns for Absolutely Accurate Measurements

    NASA Astrophysics Data System (ADS)

    Dykema, J. A.; Anderson, J.

    2011-12-01

    The 2006 NRC Decadal Survey fostered a new appreciation for societal objectives as a driving motivation for Earth science. Many high-priority societal objectives are dependent on predictions of weather and climate. These predictions are based on numerical models, which derive from approximate representations of well-founded physics and chemistry on space and timescales appropriate to global and regional prediction. These laws of chemistry and physics in turn have a well-defined quantitative relationship with physical measurement units, provided these measurement units are linked to international measurement standards that are the foundation of contemporary measurement science and standards for engineering and commerce. Without this linkage, measurements have an ambiguous relationship to scientific principles that introduces avoidable uncertainty in analyses, predictions, and improved understanding of the Earth system. Since the improvement of climate and weather prediction is fundamentally dependent on the improvement of the representation of physical processes, measurement systems that reduce the ambiguity between physical truth and observations represent an essential component of a national strategy for understanding and living with the Earth system. This paper examines the technological basis and potential science returns of sensors that make measurements that are quantitatively tied on-orbit to international measurement standards, and thus testable to systematic errors. This measurement strategy provides several distinct benefits. First, because of the quantitative relationship between these international measurement standards and fundamental physical constants, measurements of this type accurately capture the true physical and chemical behavior of the climate system and are not subject to adjustment due to excluded measurement physics or instrumental artifacts. In addition, such measurements can be reproduced by scientists anywhere in the world, at any time

  5. ACCURATE TEMPERATURE MEASUREMENTS IN A NATURALLY-ASPIRATED RADIATION SHIELD

    SciTech Connect

    Kurzeja, R.

    2009-09-09

    Experiments and calculations were conducted with a 0.13 mm fine wire thermocouple within a naturally-aspirated Gill radiation shield to assess and improve the accuracy of air temperature measurements without the use of mechanical aspiration, wind speed or radiation measurements. It was found that this thermocouple measured the air temperature with root-mean-square errors of 0.35 K within the Gill shield without correction. A linear temperature correction was evaluated based on the difference between the interior plate and thermocouple temperatures. This correction was found to be relatively insensitive to shield design and yielded an error of 0.16 K for combined day and night observations. The correction was reliable in the daytime when the wind speed usually exceeds 1 m s{sup -1} but occasionally performed poorly at night during very light winds. Inspection of the standard deviation in the thermocouple wire temperature identified these periods but did not unambiguously locate the most serious events. However, estimates of sensor accuracy during these periods is complicated by the much larger sampling volume of the mechanically-aspirated sensor compared with the naturally-aspirated sensor and the presence of significant near surface temperature gradients. The root-mean-square errors therefore are upper limits to the aspiration error since they include intrinsic sensor differences and intermittent volume sampling differences.

  6. Consisitent and Accurate Finite Volume Methods for Coupled Flow and Geomechanics

    NASA Astrophysics Data System (ADS)

    Nordbotten, J. M.

    2014-12-01

    We introduce a new class of cell-centered finite volume methods for elasticity and poro-elasticity. As compared to lowest-order finite element discretizations, the new discretization has no additional degrees of freedom, and yet gives more accurate stress and flow fields. This finite volume discretization methods has furthermore the advantage that the mechanical discretization is fully compatible (in terms of grid and variables) with the standard cell-centered finite volume discretizations that are prevailing for commercial simulation of multi-phase flows in porous media. Theoretical analysis proves the convergence of the method. We give results showing that so-called numerical locking is avoided for a large class of structured and unstructured grids. The results are valid in both two and three spatial dimensions. The talk concludes with applications to problems with coupled multi-phase flow, transport and deformation, together with fractured porous media.

  7. Accurate and Precise Zinc Isotope Ratio Measurements in Urban Aerosols

    NASA Astrophysics Data System (ADS)

    Weiss, D.; Gioia, S. M. C. L.; Coles, B.; Arnold, T.; Babinski, M.

    2009-04-01

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of δ66Zn determinations in aerosols is around 0.05 per mil per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in δ66Zn ranging between -0.96 and -0.37 per mil in coarse and between -1.04 and 0.02 per mil in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source.

  8. Novel dispersion tolerant interferometry method for accurate measurements of displacement

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.

    2015-05-01

    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  9. Accurate Sound Velocity Measurement in Ocean Near-Surface Layer

    NASA Astrophysics Data System (ADS)

    Lizarralde, D.; Xu, B. L.

    2015-12-01

    Accurate sound velocity measurement is essential in oceanography because sound is the only wave that can propagate in sea water. Due to its measuring difficulties, sound velocity is often not measured directly but instead calculated from water temperature, salinity, and depth, which are much easier to obtain. This research develops a new method to directly measure the sound velocity in the ocean's near-surface layer using multi-channel seismic (MCS) hydrophones. This system consists of a device to make a sound pulse and a long cable with hundreds of hydrophones to record the sound. The distance between the source and each receiver is the offset. The time it takes the pulse to arrive to each receiver is the travel time.The errors of measuring offset and travel time will affect the accuracy of sound velocity if we calculated with just one offset and one travel time. However, by analyzing the direct arrival signal from hundreds of receivers, the velocity can be determined as the slope of a straight line in the travel time-offset graph. The errors in distance and time measurement result in only an up or down shift of the line and do not affect the slope. This research uses MCS data of survey MGL1408 obtained from the Marine Geoscience Data System and processed with Seismic Unix. The sound velocity can be directly measured to an accuracy of less than 1m/s. The included graph shows the directly measured velocity verses the calculated velocity along 100km across the Mid-Atlantic continental margin. The directly measured velocity shows a good coherence to the velocity computed from temperature and salinity. In addition, the fine variations in the sound velocity can be observed, which is hardly seen from the calculated velocity. Using this methodology, both large area acquisition and fine resolution can be achieved. This directly measured sound velocity will be a new and powerful tool in oceanography.

  10. A spectroscopic transfer standard for accurate atmospheric CO measurements

    NASA Astrophysics Data System (ADS)

    Nwaboh, Javis A.; Li, Gang; Serdyukov, Anton; Werhahn, Olav; Ebert, Volker

    2016-04-01

    Atmospheric carbon monoxide (CO) is a precursor of essential climate variables and has an indirect effect for enhancing global warming. Accurate and reliable measurements of atmospheric CO concentration are becoming indispensable. WMO-GAW reports states a compatibility goal of ±2 ppb for atmospheric CO concentration measurements. Therefore, the EMRP-HIGHGAS (European metrology research program - high-impact greenhouse gases) project aims at developing spectroscopic transfer standards for CO concentration measurements to meet this goal. A spectroscopic transfer standard would provide results that are directly traceable to the SI, can be very useful for calibration of devices operating in the field, and could complement classical gas standards in the field where calibration gas mixtures in bottles often are not accurate, available or stable enough [1][2]. Here, we present our new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor capable of performing absolute ("calibration free") CO concentration measurements, and being operated as a spectroscopic transfer standard. To achieve the compatibility goal stated by WMO for CO concentration measurements and ensure the traceability of the final concentration results, traceable spectral line data especially line intensities with appropriate uncertainties are needed. Therefore, we utilize our new high-resolution Fourier-transform infrared (FTIR) spectroscopy CO line data for the 2-0 band, with significantly reduced uncertainties, for the dTDLAS data evaluation. Further, we demonstrate the capability of our sensor for atmospheric CO measurements, discuss uncertainty calculation following the guide to the expression of uncertainty in measurement (GUM) principles and show that CO concentrations derived using the sensor, based on the TILSAM (traceable infrared laser spectroscopic amount fraction measurement) method, are in excellent agreement with gravimetric values. Acknowledgement Parts of this work have been

  11. Accurate measurement of oxygen consumption in children undergoing cardiac catheterization.

    PubMed

    Li, Jia

    2013-01-01

    Oxygen consumption (VO(2) ) is an important part of hemodynamics using the direct Fick principle in children undergoing cardiac catheterization. Accurate measurement of VO(2) is vital. Obviously, any error in the measurement of VO(2) will translate directly into an equivalent percentage under- or overestimation of blood flows and vascular resistances. It remains common practice to estimate VO(2) values from published predictive equations. Among these, the LaFarge equation is the most commonly used equation and gives the closest estimation with the least bias and limits of agreement. However, considerable errors are introduced by the LaFarge equation, particularly in children younger than 3 years of age. Respiratory mass spectrometry remains the "state-of-the-art" method, allowing highly sensitive, rapid and simultaneous measurement of multiple gas fractions. The AMIS 2000 quadrupole respiratory mass spectrometer system has been adapted to measure VO(2) in children under mechanical ventilation with pediatric ventilators during cardiac catheterization. The small sampling rate, fast response time and long tubes make the equipment a unique and powerful tool for bedside continuous measurement of VO(2) in cardiac catheterization for both clinical and research purposes. PMID:22488802

  12. PRESAGE 3D dosimetry accurately measures Gamma Knife output factors

    NASA Astrophysics Data System (ADS)

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-12-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and 2D detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ±0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors.

  13. Volume measuring and mapping system for coal yard

    NASA Astrophysics Data System (ADS)

    Zhou, Jianxun; An, Feng; Yang, Linsheng; Li, Heming; Shen, Fugen; Jiang, Zhiwei

    1998-09-01

    The article analyzes the present volume measuring and mapping system used for coal yard, and presents a principle which connects phase-modulating laser ranging with high- accurate angle scanning, to fulfill an effective system of measuring and mapping the volume of heaps of coal. This system can complete shape-mapping and volume-measuring over 200 m X 50 m coal yard within 20 minute, and the accuracy up to 0.5%. Also, some detail working principle, actual measuring result and performance analysis of the system are discussed in this article. Due to having solved the prompt (< 1/500) and accurate (3 cm) ranging problem under the condition of low-reflection objects ((rho) < 0.01), this system can be widely used for 3D measuring and mapping on bulky objects.

  14. Accurate measurement of streamwise vortices in low speed aerodynamic flows

    NASA Astrophysics Data System (ADS)

    Waldman, Rye M.; Kudo, Jun; Breuer, Kenneth S.

    2010-11-01

    Low Reynolds number experiments with flapping animals (such as bats and small birds) are of current interest in understanding biological flight mechanics, and due to their application to Micro Air Vehicles (MAVs) which operate in a similar parameter space. Previous PIV wake measurements have described the structures left by bats and birds, and provided insight to the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions due to significant experimental challenges associated with the highly three-dimensional and unsteady nature of the flows, and the low wake velocities associated with lifting bodies that only weigh a few grams. This requires the high-speed resolution of small flow features in a large field of view using limited laser energy and finite camera resolution. Cross-stream measurements are further complicated by the high out-of-plane flow which requires thick laser sheets and short interframe times. To quantify and address these challenges we present data from a model study on the wake behind a fixed wing at conditions comparable to those found in biological flight. We present a detailed analysis of the PIV wake measurements, discuss the criteria necessary for accurate measurements, and present a new dual-plane PIV configuration to resolve these issues.

  15. Accurate reconstruction of hyperspectral images from compressive sensing measurements

    NASA Astrophysics Data System (ADS)

    Greer, John B.; Flake, J. C.

    2013-05-01

    The emerging field of Compressive Sensing (CS) provides a new way to capture data by shifting the heaviest burden of data collection from the sensor to the computer on the user-end. This new means of sensing requires fewer measurements for a given amount of information than traditional sensors. We investigate the efficacy of CS for capturing HyperSpectral Imagery (HSI) remotely. We also introduce a new family of algorithms for constructing HSI from CS measurements with Split Bregman Iteration [Goldstein and Osher,2009]. These algorithms combine spatial Total Variation (TV) with smoothing in the spectral dimension. We examine models for three different CS sensors: the Coded Aperture Snapshot Spectral Imager-Single Disperser (CASSI-SD) [Wagadarikar et al.,2008] and Dual Disperser (CASSI-DD) [Gehm et al.,2007] cameras, and a hypothetical random sensing model closer to CS theory, but not necessarily implementable with existing technology. We simulate the capture of remotely sensed images by applying the sensor forward models to well-known HSI scenes - an AVIRIS image of Cuprite, Nevada and the HYMAP Urban image. To measure accuracy of the CS models, we compare the scenes constructed with our new algorithm to the original AVIRIS and HYMAP cubes. The results demonstrate the possibility of accurately sensing HSI remotely with significantly fewer measurements than standard hyperspectral cameras.

  16. Accurate measurement of RF exposure from emerging wireless communication systems

    NASA Astrophysics Data System (ADS)

    Letertre, Thierry; Monebhurrun, Vikass; Toffano, Zeno

    2013-04-01

    Isotropic broadband probes or spectrum analyzers (SAs) may be used for the measurement of rapidly varying electromagnetic fields generated by emerging wireless communication systems. In this paper this problematic is investigated by comparing the responses measured by two different isotropic broadband probes typically used to perform electric field (E-field) evaluations. The broadband probes are submitted to signals with variable duty cycles (DC) and crest factors (CF) either with or without Orthogonal Frequency Division Multiplexing (OFDM) modulation but with the same root-mean-square (RMS) power. The two probes do not provide accurate enough results for deterministic signals such as Worldwide Interoperability for Microwave Access (WIMAX) or Long Term Evolution (LTE) as well as for non-deterministic signals such as Wireless Fidelity (WiFi). The legacy measurement protocols should be adapted to cope for the emerging wireless communication technologies based on the OFDM modulation scheme. This is not easily achieved except when the statistics of the RF emission are well known. In this case the measurement errors are shown to be systematic and a correction factor or calibration can be applied to obtain a good approximation of the total RMS power.

  17. Radio Astronomers Set New Standard for Accurate Cosmic Distance Measurement

    NASA Astrophysics Data System (ADS)

    1999-06-01

    A team of radio astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) to make the most accurate measurement ever made of the distance to a faraway galaxy. Their direct measurement calls into question the precision of distance determinations made by other techniques, including those announced last week by a team using the Hubble Space Telescope. The radio astronomers measured a distance of 23.5 million light-years to a galaxy called NGC 4258 in Ursa Major. "Ours is a direct measurement, using geometry, and is independent of all other methods of determining cosmic distances," said Jim Herrnstein, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. The team says their measurement is accurate to within less than a million light-years, or four percent. The galaxy is also known as Messier 106 and is visible with amateur telescopes. Herrnstein, along with James Moran and Lincoln Greenhill of the Harvard- Smithsonian Center for Astrophysics; Phillip Diamond, of the Merlin radio telescope facility at Jodrell Bank and the University of Manchester in England; Makato Inoue and Naomasa Nakai of Japan's Nobeyama Radio Observatory; Mikato Miyoshi of Japan's National Astronomical Observatory; Christian Henkel of Germany's Max Planck Institute for Radio Astronomy; and Adam Riess of the University of California at Berkeley, announced their findings at the American Astronomical Society's meeting in Chicago. "This is an incredible achievement to measure the distance to another galaxy with this precision," said Miller Goss, NRAO's Director of VLA/VLBA Operations. "This is the first time such a great distance has been measured this accurately. It took painstaking work on the part of the observing team, and it took a radio telescope the size of the Earth -- the VLBA -- to make it possible," Goss said. "Astronomers have sought to determine the Hubble Constant, the rate of expansion of the universe, for decades. This will in turn lead to an

  18. Accurate measurement of liquid transport through nanoscale conduits

    NASA Astrophysics Data System (ADS)

    Alibakhshi, Mohammad Amin; Xie, Quan; Li, Yinxiao; Duan, Chuanhua

    2016-04-01

    Nanoscale liquid transport governs the behaviour of a wide range of nanofluidic systems, yet remains poorly characterized and understood due to the enormous hydraulic resistance associated with the nanoconfinement and the resulting minuscule flow rates in such systems. To overcome this problem, here we present a new measurement technique based on capillary flow and a novel hybrid nanochannel design and use it to measure water transport through single 2-D hydrophilic silica nanochannels with heights down to 7 nm. Our results show that silica nanochannels exhibit increased mass flow resistance compared to the classical hydrodynamics prediction. This difference increases with decreasing channel height and reaches 45% in the case of 7 nm nanochannels. This resistance increase is attributed to the formation of a 7-angstrom-thick stagnant hydration layer on the hydrophilic surfaces. By avoiding use of any pressure and flow sensors or any theoretical estimations the hybrid nanochannel scheme enables facile and precise flow measurement through single nanochannels, nanotubes, or nanoporous media and opens the prospect for accurate characterization of both hydrophilic and hydrophobic nanofluidic systems.

  19. Slim hole MWD tool accurately measures downhole annular pressure

    SciTech Connect

    Burban, B.; Delahaye, T. )

    1994-02-14

    Measurement-while-drilling of downhole pressure accurately determines annular pressure losses from circulation and drillstring rotation and helps monitor swab and surge pressures during tripping. In early 1993, two slim-hole wells (3.4 in. and 3 in. diameter) were drilled with continuous real-time electromagnetic wave transmission of downhole temperature and annular pressure. The data were obtained during all stages of the drilling operation and proved useful for operations personnel. The use of real-time measurements demonstrated the characteristic hydraulic effects of pressure surges induced by drillstring rotation in the small slim-hole annulus under field conditions. The interest in this information is not restricted to the slim-hole geometry. Monitoring or estimating downhole pressure is a key element for drilling operations. Except in special cases, no real-time measurements of downhole annular pressure during drilling and tripping have been used on an operational basis. The hydraulic effects are significant in conventional-geometry wells (3 1/2-in. drill pipe in a 6-in. hole). This paper describes the tool and the results from the field test.

  20. Accurate measurement of liquid transport through nanoscale conduits.

    PubMed

    Alibakhshi, Mohammad Amin; Xie, Quan; Li, Yinxiao; Duan, Chuanhua

    2016-01-01

    Nanoscale liquid transport governs the behaviour of a wide range of nanofluidic systems, yet remains poorly characterized and understood due to the enormous hydraulic resistance associated with the nanoconfinement and the resulting minuscule flow rates in such systems. To overcome this problem, here we present a new measurement technique based on capillary flow and a novel hybrid nanochannel design and use it to measure water transport through single 2-D hydrophilic silica nanochannels with heights down to 7 nm. Our results show that silica nanochannels exhibit increased mass flow resistance compared to the classical hydrodynamics prediction. This difference increases with decreasing channel height and reaches 45% in the case of 7 nm nanochannels. This resistance increase is attributed to the formation of a 7-angstrom-thick stagnant hydration layer on the hydrophilic surfaces. By avoiding use of any pressure and flow sensors or any theoretical estimations the hybrid nanochannel scheme enables facile and precise flow measurement through single nanochannels, nanotubes, or nanoporous media and opens the prospect for accurate characterization of both hydrophilic and hydrophobic nanofluidic systems. PMID:27112404

  1. Accurate measurement of liquid transport through nanoscale conduits

    PubMed Central

    Alibakhshi, Mohammad Amin; Xie, Quan; Li, Yinxiao; Duan, Chuanhua

    2016-01-01

    Nanoscale liquid transport governs the behaviour of a wide range of nanofluidic systems, yet remains poorly characterized and understood due to the enormous hydraulic resistance associated with the nanoconfinement and the resulting minuscule flow rates in such systems. To overcome this problem, here we present a new measurement technique based on capillary flow and a novel hybrid nanochannel design and use it to measure water transport through single 2-D hydrophilic silica nanochannels with heights down to 7 nm. Our results show that silica nanochannels exhibit increased mass flow resistance compared to the classical hydrodynamics prediction. This difference increases with decreasing channel height and reaches 45% in the case of 7 nm nanochannels. This resistance increase is attributed to the formation of a 7-angstrom-thick stagnant hydration layer on the hydrophilic surfaces. By avoiding use of any pressure and flow sensors or any theoretical estimations the hybrid nanochannel scheme enables facile and precise flow measurement through single nanochannels, nanotubes, or nanoporous media and opens the prospect for accurate characterization of both hydrophilic and hydrophobic nanofluidic systems. PMID:27112404

  2. Second-order accurate finite volume method for well-driven flows

    NASA Astrophysics Data System (ADS)

    Dotlić, M.; Vidović, D.; Pokorni, B.; Pušić, M.; Dimkić, M.

    2016-02-01

    We consider a finite volume method for a well-driven fluid flow in a porous medium. Due to the singularity of the well, modeling in the near-well region with standard numerical schemes results in a completely wrong total well flux and an inaccurate hydraulic head. Local grid refinement can help, but it comes at computational cost. In this article we propose two methods to address the well singularity. In the first method the flux through well faces is corrected using a logarithmic function, in a way related to the Peaceman model. Coupling this correction with a non-linear second-order accurate two-point scheme gives a greatly improved total well flux, but the resulting scheme is still inconsistent. In the second method fluxes in the near-well region are corrected by representing the hydraulic head as a sum of a logarithmic and a linear function. This scheme is second-order accurate.

  3. Mean platelet volume measurement, EDTA or citrate?

    PubMed

    Dastjerdi, Mansour Siavash; Emami, Tajolmolouk; Najafian, Alireza; Amini, Masoud

    2006-10-01

    Most laboratories use EDTA for anticoagulation of whole blood prior to automated cell counting but due to platelet swelling, mean platelet volume (MPV) values may increase with its use. MPV changes may be less with acid citrate based anticoagulation. As MPV is a marker of platelet function and its precise measurement is important in a number of clinical situations, this study was performed to assess if EDTA and citrate based anticoagulated blood samples can be used interchangeably for MPV measurement. In this cross sectional descriptive study, EDTA and citrate based anticoagulated blood samples of the same patients were assessed by auto-analyzer within 1 h of sampling. In the 61 evaluated patients, there was a close correlation between MPV as measured by EDTA and citrate, but mean MPV measured from EDTA samples was 0.66 fL (9%) more than citrate. There was also a significant negative correlation between platelets count and MPV by both methods. The results of our study reveal that MPV can be measured accurately by both methods of anticoagulation; EDTA and citrate if analysis be performed within 1 h of sampling. PMID:17607580

  4. Radio Astronomers Set New Standard for Accurate Cosmic Distance Measurement

    NASA Astrophysics Data System (ADS)

    1999-06-01

    A team of radio astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) to make the most accurate measurement ever made of the distance to a faraway galaxy. Their direct measurement calls into question the precision of distance determinations made by other techniques, including those announced last week by a team using the Hubble Space Telescope. The radio astronomers measured a distance of 23.5 million light-years to a galaxy called NGC 4258 in Ursa Major. "Ours is a direct measurement, using geometry, and is independent of all other methods of determining cosmic distances," said Jim Herrnstein, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. The team says their measurement is accurate to within less than a million light-years, or four percent. The galaxy is also known as Messier 106 and is visible with amateur telescopes. Herrnstein, along with James Moran and Lincoln Greenhill of the Harvard- Smithsonian Center for Astrophysics; Phillip Diamond, of the Merlin radio telescope facility at Jodrell Bank and the University of Manchester in England; Makato Inoue and Naomasa Nakai of Japan's Nobeyama Radio Observatory; Mikato Miyoshi of Japan's National Astronomical Observatory; Christian Henkel of Germany's Max Planck Institute for Radio Astronomy; and Adam Riess of the University of California at Berkeley, announced their findings at the American Astronomical Society's meeting in Chicago. "This is an incredible achievement to measure the distance to another galaxy with this precision," said Miller Goss, NRAO's Director of VLA/VLBA Operations. "This is the first time such a great distance has been measured this accurately. It took painstaking work on the part of the observing team, and it took a radio telescope the size of the Earth -- the VLBA -- to make it possible," Goss said. "Astronomers have sought to determine the Hubble Constant, the rate of expansion of the universe, for decades. This will in turn lead to an

  5. Accurate method to study static volume-pressure relationships in small fetal and neonatal animals.

    PubMed

    Suen, H C; Losty, P D; Donahoe, P K; Schnitzer, J J

    1994-08-01

    We designed an accurate method to study respiratory static volume-pressure relationships in small fetal and neonatal animals on the basis of Archimedes' principle. Our method eliminates the error caused by the compressibility of air (Boyle's law) and is sensitive to a volume change of as little as 1 microliters. Fetal and neonatal rats during the period of rapid lung development from day 19.5 of gestation (term = day 22) to day 3.5 postnatum were studied. The absolute lung volume at a transrespiratory pressure of 30-40 cmH2O increased 28-fold from 0.036 +/- 0.006 (SE) to 0.994 +/- 0.042 ml, the volume per gram of lung increased 14-fold from 0.39 +/- 0.07 to 5.59 +/- 0.66 ml/g, compliance increased 12-fold from 2.3 +/- 0.4 to 27.3 +/- 2.7 microliters/cmH2O, and specific compliance increased 6-fold from 24.9 +/- 4.5 to 152.3 +/- 22.8 microliters.cmH2O-1.g lung-1. This technique, which allowed us to compare changes during late gestation and the early neonatal period in small rodents, can be used to monitor and evaluate pulmonary functional changes after in utero pharmacological therapies in experimentally induced abnormalities such as pulmonary hypoplasia, surfactant deficiency, and congenital diaphragmatic hernia. PMID:8002489

  6. Measurement of Fracture Geometry for Accurate Computation of Hydraulic Conductivity

    NASA Astrophysics Data System (ADS)

    Chae, B.; Ichikawa, Y.; Kim, Y.

    2003-12-01

    Fluid flow in rock mass is controlled by geometry of fractures which is mainly characterized by roughness, aperture and orientation. Fracture roughness and aperture was observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wavelength of laser is 488nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The system improves resolution in the light axis (namely z) direction because of the confocal optics. The sampling is managed in a spacing 2.5 μ m along x and y directions. The highest measurement resolution of z direction is 0.05 μ m, which is the more accurate than other methods. For the roughness measurements, core specimens of coarse and fine grained granites were provided. Measurements were performed along three scan lines on each fracture surface. The measured data were represented as 2-D and 3-D digital images showing detailed features of roughness. Spectral analyses by the fast Fourier transform (FFT) were performed to characterize on the roughness data quantitatively and to identify influential frequency of roughness. The FFT results showed that components of low frequencies were dominant in the fracture roughness. This study also verifies that spectral analysis is a good approach to understand complicate characteristics of fracture roughness. For the aperture measurements, digital images of the aperture were acquired under applying five stages of uniaxial normal stresses. This method can characterize the response of aperture directly using the same specimen. Results of measurements show that reduction values of aperture are different at each part due to rough geometry of fracture walls. Laboratory permeability tests were also conducted to evaluate changes of hydraulic conductivities related to aperture variation due to different stress levels. The results showed non-uniform reduction of hydraulic conductivity under increase of the normal stress and different values of

  7. Applications of accurate isentropic exponent determination for fuel gas measurement

    SciTech Connect

    Pack, D.J.; Edwards, T.J.; Fawcett, D.

    1996-07-01

    This paper discusses the determination and application of the isentropic exponent to the various thermodynamic processes found in a high-pressure natural gas transmission system. Increasing demands for more precise measurement of natural gas, coupled with the need for greater efficiency and accountability of transportation and processing operations, had led to the research and development of gas thermodynamic properties including isentropic exponent. The isentropic exponent has many applications, some of which include: the determination of the expansion factor {epsilon}, for calculation of flow using an orifice or venturi-type meter; the volumetric efficiency in a reciprocating compressor; the determination of the compression head for a centrifugal compressor; the engine power required for the given conditions for a gas compressor; the calculation of discharge temperatures for compressors; and the direct measurement of gas density. As can be appreciated, the application of an incorrect value for the isentropic exponent represents an error in the parameter determined. For large volume gas flows, this can translate into a significant cost penalty.

  8. History and progress on accurate measurements of the Planck constant

    NASA Astrophysics Data System (ADS)

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10-34 J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, NA. As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 108 from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the improved

  9. History and progress on accurate measurements of the Planck constant.

    PubMed

    Steiner, Richard

    2013-01-01

    The measurement of the Planck constant, h, is entering a new phase. The CODATA 2010 recommended value is 6.626 069 57 × 10(-34) J s, but it has been a long road, and the trip is not over yet. Since its discovery as a fundamental physical constant to explain various effects in quantum theory, h has become especially important in defining standards for electrical measurements and soon, for mass determination. Measuring h in the International System of Units (SI) started as experimental attempts merely to prove its existence. Many decades passed while newer experiments measured physical effects that were the influence of h combined with other physical constants: elementary charge, e, and the Avogadro constant, N(A). As experimental techniques improved, the precision of the value of h expanded. When the Josephson and quantum Hall theories led to new electronic devices, and a hundred year old experiment, the absolute ampere, was altered into a watt balance, h not only became vital in definitions for the volt and ohm units, but suddenly it could be measured directly and even more accurately. Finally, as measurement uncertainties now approach a few parts in 10(8) from the watt balance experiments and Avogadro determinations, its importance has been linked to a proposed redefinition of a kilogram unit of mass. The path to higher accuracy in measuring the value of h was not always an example of continuous progress. Since new measurements periodically led to changes in its accepted value and the corresponding SI units, it is helpful to see why there were bumps in the road and where the different branch lines of research joined in the effort. Recalling the bumps along this road will hopefully avoid their repetition in the upcoming SI redefinition debates. This paper begins with a brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant. The historical path is followed in the section describing how the

  10. Accurate on-line mass flow measurements in supercritical fluid chromatography.

    PubMed

    Tarafder, Abhijit; Vajda, Péter; Guiochon, Georges

    2013-12-13

    This work demonstrates the possible advantages and the challenges of accurate on-line measurements of the CO2 mass flow rate during supercritical fluid chromatography (SFC) operations. Only the mass flow rate is constant along the column in SFC. The volume flow rate is not. The critical importance of accurate measurements of mass flow rates for the achievement of reproducible data and the serious difficulties encountered in supercritical fluid chromatography for its assessment were discussed earlier based on the physical properties of carbon dioxide. In this report, we experimentally demonstrate the problems encountered when performing mass flow rate measurements and the gain that can possibly be achieved by acquiring reproducible data using a Coriolis flow meter. The results obtained show how the use of a highly accurate mass flow meter permits, besides the determination of accurate values of the mass flow rate, a systematic, constant diagnosis of the correct operation of the instrument and the monitoring of the condition of the carbon dioxide pump. PMID:24210558

  11. Accurate tracking of tumor volume change during radiotherapy by CT-CBCT registration with intensity correction

    NASA Astrophysics Data System (ADS)

    Park, Seyoun; Robinson, Adam; Quon, Harry; Kiess, Ana P.; Shen, Colette; Wong, John; Plishker, William; Shekhar, Raj; Lee, Junghoon

    2016-03-01

    In this paper, we propose a CT-CBCT registration method to accurately predict the tumor volume change based on daily cone-beam CTs (CBCTs) during radiotherapy. CBCT is commonly used to reduce patient setup error during radiotherapy, but its poor image quality impedes accurate monitoring of anatomical changes. Although physician's contours drawn on the planning CT can be automatically propagated to daily CBCTs by deformable image registration (DIR), artifacts in CBCT often cause undesirable errors. To improve the accuracy of the registration-based segmentation, we developed a DIR method that iteratively corrects CBCT intensities by local histogram matching. Three popular DIR algorithms (B-spline, demons, and optical flow) with the intensity correction were implemented on a graphics processing unit for efficient computation. We evaluated their performances on six head and neck (HN) cancer cases. For each case, four trained scientists manually contoured the nodal gross tumor volume (GTV) on the planning CT and every other fraction CBCTs to which the propagated GTV contours by DIR were compared. The performance was also compared with commercial image registration software based on conventional mutual information (MI), VelocityAI (Varian Medical Systems Inc.). The volume differences (mean±std in cc) between the average of the manual segmentations and automatic segmentations are 3.70+/-2.30 (B-spline), 1.25+/-1.78 (demons), 0.93+/-1.14 (optical flow), and 4.39+/-3.86 (VelocityAI). The proposed method significantly reduced the estimation error by 9% (B-spline), 38% (demons), and 51% (optical flow) over the results using VelocityAI. Although demonstrated only on HN nodal GTVs, the results imply that the proposed method can produce improved segmentation of other critical structures over conventional methods.

  12. Automatic classification and accurate size measurement of blank mask defects

    NASA Astrophysics Data System (ADS)

    Bhamidipati, Samir; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

    2015-07-01

    complexity of defects encountered. The variety arises due to factors such as defect nature, size, shape and composition; and the optical phenomena occurring around the defect. This paper focuses on preliminary characterization results, in terms of classification and size estimation, obtained by Calibre MDPAutoClassify tool on a variety of mask blank defects. It primarily highlights the challenges faced in achieving the results with reference to the variety of defects observed on blank mask substrates and the underlying complexities which make accurate defect size measurement an important and challenging task.

  13. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, James O.; Remenyik, Carl J.

    1994-01-01

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel.

  14. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, J.O.; Remenyik, C.J.

    1994-08-09

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure is disclosed. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel. 5 figs.

  15. Accurate body composition measures from whole-body silhouettes

    PubMed Central

    Xie, Bowen; Avila, Jesus I.; Ng, Bennett K.; Fan, Bo; Loo, Victoria; Gilsanz, Vicente; Hangartner, Thomas; Kalkwarf, Heidi J.; Lappe, Joan; Oberfield, Sharon; Winer, Karen; Zemel, Babette; Shepherd, John A.

    2015-01-01

    Purpose: Obesity and its consequences, such as diabetes, are global health issues that burden about 171 × 106 adult individuals worldwide. Fat mass index (FMI, kg/m2), fat-free mass index (FFMI, kg/m2), and percent fat mass may be useful to evaluate under- and overnutrition and muscle development in a clinical or research environment. This proof-of-concept study tested whether frontal whole-body silhouettes could be used to accurately measure body composition parameters using active shape modeling (ASM) techniques. Methods: Binary shape images (silhouettes) were generated from the skin outline of dual-energy x-ray absorptiometry (DXA) whole-body scans of 200 healthy children of ages from 6 to 16 yr. The silhouette shape variation from the average was described using an ASM, which computed principal components for unique modes of shape. Predictive models were derived from the modes for FMI, FFMI, and percent fat using stepwise linear regression. The models were compared to simple models using demographics alone [age, sex, height, weight, and body mass index z-scores (BMIZ)]. Results: The authors found that 95% of the shape variation of the sampled population could be explained using 26 modes. In most cases, the body composition variables could be predicted similarly between demographics-only and shape-only models. However, the combination of shape with demographics improved all estimates of boys and girls compared to the demographics-only model. The best prediction models for FMI, FFMI, and percent fat agreed with the actual measures with R2 adj. (the coefficient of determination adjusted for the number of parameters used in the model equation) values of 0.86, 0.95, and 0.75 for boys and 0.90, 0.89, and 0.69 for girls, respectively. Conclusions: Whole-body silhouettes in children may be useful to derive estimates of body composition including FMI, FFMI, and percent fat. These results support the feasibility of measuring body composition variables from simple

  16. Accurate protein-peptide titration experiments by nuclear magnetic resonance using low-volume samples.

    PubMed

    Köhler, Christian; Recht, Raphaël; Quinternet, Marc; de Lamotte, Frederic; Delsuc, Marc-André; Kieffer, Bruno

    2015-01-01

    NMR spectroscopy allows measurements of very accurate values of equilibrium dissociation constants using chemical shift perturbation methods, provided that the concentrations of the binding partners are known with high precision and accuracy. The accuracy and precision of these experiments are improved if performed using individual capillary tubes, a method enabling full automation of the measurement. We provide here a protocol to set up and perform these experiments as well as a robust method to measure peptide concentrations using tryptophan as an internal standard. PMID:25749962

  17. Is internal target volume accurate for dose evaluation in lung cancer stereotactic body radiotherapy?

    PubMed Central

    Peng, Jiayuan; Zhang, Zhen; Wang, Jiazhou; Xie, Jiang; Hu, Weigang

    2016-01-01

    Purpose 4DCT delineated internal target volume (ITV) was applied to determine the tumor motion and used as planning target in treatment planning in lung cancer stereotactic body radiotherapy (SBRT). This work is to study the accuracy of using ITV to predict the real target dose in lung cancer SBRT. Materials and methods Both for phantom and patient cases, the ITV and gross tumor volumes (GTVs) were contoured on the maximum intensity projection (MIP) CT and ten CT phases, respectively. A SBRT plan was designed using ITV as the planning target on average projection (AVG) CT. This plan was copied to each CT phase and the dose distribution was recalculated. The GTV_4D dose was acquired through accumulating the GTV doses over all ten phases and regarded as the real target dose. To analyze the ITV dose error, the ITV dose was compared to the real target dose by endpoints of D99, D95, D1 (doses received by the 99%, 95% and 1% of the target volume), and dose coverage endpoint of V100(relative volume receiving at least the prescription dose). Results The phantom study shows that the ITV underestimates the real target dose by 9.47%∼19.8% in D99, 4.43%∼15.99% in D95, and underestimates the dose coverage by 5% in V100. The patient cases show that the ITV underestimates the real target dose and dose coverage by 3.8%∼10.7% in D99, 4.7%∼7.2% in D95, and 3.96%∼6.59% in V100 in motion target cases. Conclusions Cautions should be taken that ITV is not accurate enough to predict the real target dose in lung cancer SBRT with large tumor motions. Restricting the target motion or reducing the target dose heterogeneity could reduce the ITV dose underestimation effect in lung SBRT. PMID:26968812

  18. Development of a prototype fluid volume measurement system. [for urine volume measurement on space missions

    NASA Technical Reports Server (NTRS)

    Poppendiek, H. F.; Sabin, C. M.; Meckel, P. T.

    1974-01-01

    The research is reported in applying the axial fluid temperature differential flowmeter to a urine volume measurement system for space missions. The fluid volume measurement system is described along with the prototype equipment package. Flowmeter calibration, electronic signal processing, and typical void volume measurements are also described.

  19. Method for measuring anterior chamber volume by image analysis

    NASA Astrophysics Data System (ADS)

    Zhai, Gaoshou; Zhang, Junhong; Wang, Ruichang; Wang, Bingsong; Wang, Ningli

    2007-12-01

    Anterior chamber volume (ACV) is very important for an oculist to make rational pathological diagnosis as to patients who have some optic diseases such as glaucoma and etc., yet it is always difficult to be measured accurately. In this paper, a method is devised to measure anterior chamber volumes based on JPEG-formatted image files that have been transformed from medical images using the anterior-chamber optical coherence tomographer (AC-OCT) and corresponding image-processing software. The corresponding algorithms for image analysis and ACV calculation are implemented in VC++ and a series of anterior chamber images of typical patients are analyzed, while anterior chamber volumes are calculated and are verified that they are in accord with clinical observation. It shows that the measurement method is effective and feasible and it has potential to improve accuracy of ACV calculation. Meanwhile, some measures should be taken to simplify the handcraft preprocess working as to images.

  20. Accurate strain measurements in highly strained Ge microbridges

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Osvaldo Dias, G.; Pauc, N.; Duchemin, I.; Rouchon, D.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Niquet, Y.-M.; Geiger, R.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2016-06-01

    Ge under high strain is predicted to become a direct bandgap semiconductor. Very large deformations can be introduced using microbridge devices. However, at the microscale, strain values are commonly deduced from Raman spectroscopy using empirical linear models only established up to ɛ100 = 1.2% for uniaxial stress. In this work, we calibrate the Raman-strain relation at higher strain using synchrotron based microdiffraction. The Ge microbridges show unprecedented high tensile strain up to 4.9% corresponding to an unexpected Δω = 9.9 cm-1 Raman shift. We demonstrate experimentally and theoretically that the Raman strain relation is not linear and we provide a more accurate expression.

  1. Instrument for Measuring Engine Clearance Volumes

    NASA Technical Reports Server (NTRS)

    Sparrow, S W

    1920-01-01

    With the advent of the V type engine, a new method to measure the clearance volume in cylinders was needed. It was suggested that this measurement could be made by a process which consisted essentially of simultaneously changing both a known and unknown volume of gas by a known amount and then calculating the magnitude of the unknown from the resulting difference in pressure between the two. An instrument based on this design is described.

  2. Accurate diffuse reflection measurements in the infrared spectral range.

    PubMed

    Richter, W; Erb, W

    1987-11-01

    A sphere arrangement for directional-hemispherical reflectance measurements in the 1-15-microm wavelength range is tested for its accuracy. Comparative measurements with the fundamental PTB sphere reflectometer in the overlapping spectral range between 1.0 and 1.1 microm indicate no systematic measurement uncertainties of the new device. The uncertainty of the reflectance measured by it is therefrom deduced to be +/-0.01 for the 1-5.6-microm wavelength range. PMID:20523415

  3. Fact Sheet: Accurately measuring forage yield in pastures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Farmers have a few options for measuring pasture yield. These include pasture rulers, plate meters, and electronic gauges. Pasture rulers simply measure canopy height and assume that forage yield is directly related to height. Plate meters improve accuracy by measuring compressed height. Electronic ...

  4. Accurate Critical Stress Intensity Factor Griffith Crack Theory Measurements by Numerical Techniques

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    Critical stress intensity factor (KIc) has been an approximation for fracture toughness using only load-cell measurements. However, artificial man-made cracks several orders of magnitude longer and wider than natural flaws have required a correction factor term (Y) that can be up to about 3 times the recorded experimental value [1-3]. In fact, over 30 years ago a National Academy of Sciences advisory board stated that empirical KIc testing was of serious concern and further requested that an accurate bulk fracture toughness method be found [4]. Now that fracture toughness can be calculated accurately by numerical integration from the load/deflection curve as resilience, work of fracture (WOF) and strain energy release (SIc) [5, 6], KIc appears to be unnecessary. However, the large body of previous KIc experimental test results found in the literature offer the opportunity for continued meta analysis with other more practical and accurate fracture toughness results using energy methods and numerical integration. Therefore, KIc is derived from the classical Griffith Crack Theory [6] to include SIc as a more accurate term for strain energy release rate (𝒢Ic), along with crack surface energy (γ), crack length (a), modulus (E), applied stress (σ), Y, crack-tip plastic zone defect region (rp) and yield strength (σys) that can all be determined from load and deflection data. Polymer matrix discontinuous quartz fiber-reinforced composites to accentuate toughness differences were prepared for flexural mechanical testing comprising of 3 mm fibers at different volume percentages from 0-54.0 vol% and at 28.2 vol% with different fiber lengths from 0.0-6.0 mm. Results provided a new correction factor and regression analyses between several numerical integration fracture toughness test methods to support KIc results. Further, bulk KIc accurate experimental values are compared with empirical test results found in literature. Also, several fracture toughness mechanisms

  5. Radio interferometric measurements for accurate planetary orbiter navigation

    NASA Technical Reports Server (NTRS)

    Poole, S. R.; Ananda, M.; Hildebrand, C. E.

    1979-01-01

    The use of narrowband delta-VLBI to achieve accurate orbit determination is presented by viewing a spacecraft from widely separated stations followed by viewing a nearby quasar from the same stations. Current analysis is examined that establishes the orbit determination accuracy achieved with data arcs spanning up to 3.5 d. Strategies for improving prediction accuracy are given, and the performance of delta-VLBI is compared with conventional radiometric tracking data. It is found that accuracy 'within the fit' is on the order of 0.5 km for data arcs having delta-VLBI on the ends of the arcs and for arc lengths varying from one baseline to 3.5 d. The technique is discussed with reference to the proposed Venus Orbiting Imaging Radar mission.

  6. Chemical Method of Urine Volume Measurement

    NASA Technical Reports Server (NTRS)

    Petrack, P.

    1967-01-01

    A system has been developed and qualified as flight hardware for the measurement of micturition volumes voided by crewmen during Gemini missions. This Chemical Urine Volume Measurement System (CUVMS) is used for obtaining samples of each micturition for post-flight volume determination and laboratory analysis for chemical constituents of physiological interest. The system is versatile with respect to volumes measured, with a capacity beyond the largest micturition expected to be encountered, and with respect to mission duration of inherently indefinite length. The urine sample is used for the measurement of total micturition volume by a tracer dilution technique, in which a fixed, predetermined amount of tritiated water is introduced and mixed into the voided urine, and the resulting concentration of the tracer in the sample is determined with a liquid scintillation spectrometer. The tracer employed does not interfere with the analysis for the chemical constituents of the urine. The CUVMS hardware consists of a four-way selector valve in which an automatically operated tracer metering pump is incorporated, a collection/mixing bag, and tracer storage accumulators. The assembled system interfaces with a urine receiver at the selector valve inlet, sample bags which connect to the side of the selector valve, and a flexible hose which carries the excess urine to the overboard drain connection. Results of testing have demonstrated system volume measurement accuracy within the specification limits of +/-5%, and operating reliability suitable for system use aboard the GT-7 mission, in which it was first used.

  7. Measuring industrial energy efficiency: Physical volume versus economic value

    SciTech Connect

    Freeman, S.L.; Niefer, M.J.; Roop, J.M.

    1996-12-01

    This report examines several different measures of industrial output for use in constructing estimates of industrial energy efficiency and discusses some reasons for differences between the measures. Estimates of volume-based measures of output, as well as 3 value-based measures of output (value of production, value of shipments, and value added), are evaluated for 15 separate 4-digit industries. Volatility, simple growth rate, and trend growth rate estimates are made for each industry and each measure of output. Correlations are made between the volume- and value-based measures of output. Historical energy use data are collected for 5 of the industries for making energy- intensity estimates. Growth rates in energy use, energy intensity, and correlations between volume- and value-based measures of energy intensity are computed. There is large variability in growth trend estimates both long term and from year to year. While there is a high correlation between volume- and value-based measures of output for a few industries, typically the correlation is low, and this is exacerbated for estimates of energy intensity. Analysis revealed reasons for these low correlations. It appears that substantial work must be done before reliable measures of trends in the energy efficiency of industry can be accurately characterized.

  8. Problems with Accurate Atomic Lfetime Measurements of Multiply Charged Ions

    SciTech Connect

    Trabert, E

    2009-02-19

    A number of recent atomic lifetime measurements on multiply charged ions have reported uncertainties lower than 1%. Such a level of accuracy challenges theory, which is a good thing. However, a few lessons learned from earlier precision lifetime measurements on atoms and singly charged ions suggest to remain cautious about the systematic errors of experimental techniques.

  9. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  10. Accurate Measurements of Spectral Reflectance in Picasso's Guernica Painting.

    PubMed

    de Luna, Javier Muñoz; Fernandez-Balbuena, Antonio Alvarez; Vázquez, Daniel; Melgosa, Manuel; Durán, Humberto; García, Jorge; Muro, Carmen

    2016-01-01

    The use of non-invasive spectral measurements to control the conservation status is a part of the preventive conservation of artworks which nowadays is becoming increasingly interesting. This paper describes how to use a spectral measuring device and an illumination system specifically designed for such a task in a very large dimension artwork painting (7.8 m wide × 3.5 m high). The system, controlled by a Cartesian robot, allows spectral measurements in a spectral range of 400-780 nm. The measured data array has a total of 2201 circular regions with 5.5 mm spot diameter placed on a square grid. Colorimetric calculations performed from these spectral measurements may be used to characterize color shifts related to reflectance changes in specific areas of the paint. A color shifting from the expected gray has been shown. PMID:26767640

  11. Accurate aircraft wind measurements using the global positioning system (GPS)

    SciTech Connect

    Dobosy, R.J.; Crawford, T.L., McMillen, R.T., Dumas, E.J.

    1996-11-01

    High accuracy measurements of the spatial distribution of wind speed are required in the study of turbulent exchange between the atmosphere and the earth. The use of a differential global positioning system (GPS) to determine the sensor velocity vector component of wind speed is discussed in this paper. The results of noise and rocking testing are summarized, and fluxes obtained from the GPS-based methods are compared to those measured from systems on towers and airplanes. The GPS-based methods provided usable measurements that compared well with tower and aircraft data at a significantly lower cost. 21 refs., 1 fig., 2 tabs.

  12. Magnetic field models of nine CP stars from "accurate" measurements

    NASA Astrophysics Data System (ADS)

    Glagolevskij, Yu. V.

    2013-01-01

    The dipole models of magnetic fields in nine CP stars are constructed based on the measurements of metal lines taken from the literature, and performed by the LSD method with an accuracy of 10-80 G. The model parameters are compared with the parameters obtained for the same stars from the hydrogen line measurements. For six out of nine stars the same type of structure was obtained. Some parameters, such as the field strength at the poles B p and the average surface magnetic field B s differ considerably in some stars due to differences in the amplitudes of phase dependences B e (Φ) and B s (Φ), obtained by different authors. It is noted that a significant increase in the measurement accuracy has little effect on the modelling of the large-scale structures of the field. By contrast, it is more important to construct the shape of the phase dependence based on a fairly large number of field measurements, evenly distributed by the rotation period phases. It is concluded that the Zeeman component measurement methods have a strong effect on the shape of the phase dependence, and that the measurements of the magnetic field based on the lines of hydrogen are more preferable for modelling the large-scale structures of the field.

  13. The Greenhouse Effect - Determination From Accurate Surface Longwave Radiation Measurements

    NASA Astrophysics Data System (ADS)

    Philipona, R.

    Longwave radiation measurements have been drastically improved in recent years. Uncertainty levels down to s2 Wm-2 are realistic and achieved during long-term ´ longwave irradiance measurements. Longwave downward irradiance measurements together with temperature and humidity measurements at the station are used to sepa- rate clear-sky from cloudy-sky situations. Longwave net radiation separated between clear-sky and all-sky situations allows to determine the longwave cloud radiative forc- ing at the station. For clear-sky situations radiative transfer models demonstrate a lin- ear relation between longwave downward radiation and the greenhouse radiative flux. Clear-sky longwave radiation, temperature and humidity for different atmospheres and different altitudes were modeled with the MODTRAN radiative transfer code and compared to longwave radiation, temperature and humidity measured at 4 radiation stations of the Alpine Surface Radiation Budget (ASRB) network at similar altitude and with corresponding atmospheres. At the 11 ASRB stations the clear-sky green- house effect was determined by using clear-sky longwave downward measurements and MODTRAN model calculations. The all-sky greenhouse effect was determined by adding the longwave cloud radiative forcing to the clear-sky greenhouse radiative flux. The altitude dependence of annual and seasonal mean values of the greenhouse effect will be shown for the altitude range of 400 to 3600 meter a.s.l. in the Alps.

  14. Measurement of the volume of weights using an acoustic volumeter and the reliability of such measurement

    NASA Astrophysics Data System (ADS)

    Kobata, T.; Ueki, M.; Ooiwa, A.; Ishii, Y.

    2004-04-01

    For the precise measurement of the mass of a weight, buoyancy correction of air for the volume of a weight is necessary. Although hydrostatic weighing is the most accurate method currently used in determining volume, it is a relatively complicated process requiring the weight to be wetted in a reference fluid. Since more weights with high accuracy of mass are being used, a more sophisticated method of determining volume that satisfies uncertainty requirements has been demanded to improve the efficiency of calibration. In this paper, an acoustic volumeter is proposed for the measurement of the volume of weights. An acoustic volumeter can measure volume in atmosphere in a simple manner. Consequently, it is not necessary to consider the contamination and mass change due to the liquid used in the hydrostatic weighing method. In practical applications, a procedure for measuring the volume of weights ranging from 100 g to 10 kg using an acoustic volumeter is proposed. The volumes obtained using an acoustic volumeter were compared with those obtained by the hydrostatic weighing method, and the reliability of the measurement was evaluated with a relative uncertainty below the order of 1 × 10-3. From the measurement results, it was shown that the use of an acoustic volumeter is effective for the measurement of the volume of weights.

  15. Accurate Measurements of Aircraft Engine Soot Emissions Using a CAPS PMssa Monitor

    NASA Astrophysics Data System (ADS)

    Onasch, Timothy; Thompson, Kevin; Renbaum-Wolff, Lindsay; Smallwood, Greg; Make-Lye, Richard; Freedman, Andrew

    2016-04-01

    We present results of aircraft engine soot emissions measurements during the VARIAnT2 campaign using CAPS PMssa monitors. VARIAnT2, an aircraft engine non-volatile particulate matter (nvPM) emissions field campaign, was focused on understanding the variability in nvPM mass measurements using different measurement techniques and accounting for possible nvPM sampling system losses. The CAPS PMssa monitor accurately measures both the optical extinction and scattering (and thus single scattering albedo and absorption) of an extracted sample using the same sample volume for both measurements with a time resolution of 1 second and sensitivity of better than 1 Mm-1. Absorption is obtained by subtracting the scattering signal from the total extinction. Given that the single scattering albedo of the particulates emitted from the aircraft engine measured at both 630 and 660 nm was on the order of 0.1, any inaccuracy in the scattering measurement has little impact on the accuracy of the ddetermined absorption coefficient. The absorption is converted into nvPM mass using a documented Mass Absorption Coefficient (MAC). Results of soot emission indices (mass soot emitted per mass of fuel consumed) for a turbojet engine as a function of engine power will be presented and compared to results obtained using an EC/OC monitor.

  16. Capacitance probe for fluid flow and volume measurements

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

    1995-01-01

    Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a microgravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

  17. Capacitance Probe for Fluid Flow and Volume Measurements

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

    1997-01-01

    Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a micro-gravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

  18. Measuring Intracranial Pressure And Volume Noninvasively

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Yost, William T.

    1994-01-01

    Ultrasonic technique eliminates need to drill into brain cavity. Intracranial dynamics instrument probes cranium ultrasonically to obtain data for determination of intracranial pressure (ICP) and pressure-volume index (PVI). Instrument determines sensitivity of skull to changes in pressure and by use of mechanical device to exert external calibrated pressure on skull. By monitoring volume of blood flowing into jugular vein, one determines change of volume of blood in cranial system. By measuring response of skull to increasing pressure (where pressure increased by tilting patient known amount) and by using cranial blood pressure, one determines intial pressure in cerebrospinal fluid. Once PVI determined, ICP determined.

  19. An accurate analytic approximation to the non-linear change in volume of solids with applied pressure

    NASA Technical Reports Server (NTRS)

    Schlosser, Herbert; Ferrante, John

    1989-01-01

    An accurate analytic expression for the nonlinear change of the volume of a solid as a function of applied pressure is of great interest in high-pressure experimentation. It is found that a two-parameter analytic expression, fits the experimental volume-change data to within a few percent over the entire experimentally attainable pressure range. Results are presented for 24 different materials including metals, ceramic semiconductors, polymers, and ionic and rare-gas solids.

  20. Method of measuring a liquid pool volume

    DOEpatents

    Garcia, Gabe V.; Carlson, Nancy M.; Donaldson, Alan D.

    1991-01-01

    A method of measuring a molten metal liquid pool volume and in particular molten titanium liquid pools, including the steps of (a) generating an ultrasonic wave at the surface of the molten metal liquid pool, (b) shining a light on the surface of a molten metal liquid pool, (c) detecting a change in the frequency of light, (d) detecting an ultrasonic wave echo at the surface of the molten metal liquid pool, and (e) computing the volume of the molten metal liquid.

  1. Measuring Fisher Information Accurately in Correlated Neural Populations

    PubMed Central

    Kohn, Adam; Pouget, Alexandre

    2015-01-01

    Neural responses are known to be variable. In order to understand how this neural variability constrains behavioral performance, we need to be able to measure the reliability with which a sensory stimulus is encoded in a given population. However, such measures are challenging for two reasons: First, they must take into account noise correlations which can have a large influence on reliability. Second, they need to be as efficient as possible, since the number of trials available in a set of neural recording is usually limited by experimental constraints. Traditionally, cross-validated decoding has been used as a reliability measure, but it only provides a lower bound on reliability and underestimates reliability substantially in small datasets. We show that, if the number of trials per condition is larger than the number of neurons, there is an alternative, direct estimate of reliability which consistently leads to smaller errors and is much faster to compute. The superior performance of the direct estimator is evident both for simulated data and for neuronal population recordings from macaque primary visual cortex. Furthermore we propose generalizations of the direct estimator which measure changes in stimulus encoding across conditions and the impact of correlations on encoding and decoding, typically denoted by Ishuffle and Idiag respectively. PMID:26030735

  2. Accurate measurements of mass and center of mass

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Trubert, M. R.

    1979-01-01

    Object is measured for mass and center of mass with accuracies of 0.01% and 0.14 respectively, using method that eliminates errors in alignment, leveling, and calibration. Method is applied to scientific instruments, recorder turntables, flywheels, and other devices that require precise balancing.

  3. Instrument accurately measures stress loads in threaded bolts

    NASA Technical Reports Server (NTRS)

    Rollins, F. R., Jr.

    1971-01-01

    Interferometric instrument response is linearly related to axial tensile stresses, and, under idealized conditions, measurement errors are within approximately plus or minus 1 percent. Ultimate accuracy of instrument depends on a number of variables, such as bolt material, dimensions, and geometry and uniformity of stresses and temperature.

  4. Miniature bioelectric device accurately measures and telemeters temperature

    NASA Technical Reports Server (NTRS)

    Fryer, T. B.

    1966-01-01

    Miniature micropower solid-state circuit measures and telemeters the body temperature of laboratory animals over periods up to two years. The circuit employs a thermistor as a temperature sensing element and an fm transmitter. It is constructed from conventional discrete components or integrated circuits.

  5. Accurate measurements of thermal radiation from a tungsten photonic lattice

    SciTech Connect

    Seager, C.H.; Sinclair, M.B.; Fleming, J.G.

    2005-06-13

    Recently, photonic lattice structures have become available that are fabricated from refractory materials such as tungsten and thus stable in vacuo at high temperatures. Such structures can be tailored to exhibit optical properties that are not achievable with ordinary optical materials. In particular, photonic lattices can be designed to suppress thermal emission in undesired spectral regions, and can thereby enhance the overall energy efficiency of emission at useful wavelengths. We report measurements of the thermal emission spectra of tungsten photonic lattices in the wavelength range 3 to 24 {mu}m. Suppression of thermal emission at wavelengths longer than the photonic bandedge ({approx}6 {mu}m) is observed, along with significant emission at shorter wavelengths. We show that from 404 to 546 K the spectral emissivity E({lambda}) is temperature independent and approaches [1-R({lambda})], where R({lambda}) is the measured specular reflectance spectrum. These results are in accord with Kirchhoff's law.

  6. Air toxics being measured more accurately, controlled more effectively

    SciTech Connect

    1995-04-01

    In response to the directives of the Clean Air Act Amendments, Argonne National Laboratory is developing new or improved pollutant control technologies for industries that burn fossil fuels. This research continues Argonne`s traditional support for the US DOE Flue Gas Cleanup Program. Research is underway to measure process emissions and identify new and improved control measures. Argonne`s emission control research has ranged from experiments in the basic chemistry of pollution-control systems, through laboratory-scale process development and testing to pilot-scale field tests of several technologies. Whenever appropriate, the work has emphasized integrated or combined control systems as the best approach to technologies that offer low cost and good operating characteristics.

  7. Accurate Measurement of Heat Capacity by Differential Scanning Calorimetry

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Experience with high quality heat capacity measurement by differential scanning calorimetry is summarized and illustrated, pointing out three major causes of error: (1) incompatible thermal histories of the sample, reference and blank runs; (2) unstable initial and final isotherms; (3) incompatible differences between initial and final isotherm amplitudes for sample, reference and blank runs. Considering these problems, it is shown for the case of polyoxymethylene that accuracies in heat capacity of 0.1 percent may be possible.

  8. Accurate measurement of Cn2 profile with Shack-Hartmann data

    NASA Astrophysics Data System (ADS)

    Voyez, Juliette; Robert, Clélia; Michau, Vincent; Conan, Jean-Marc; Fusco, Thierry

    2012-07-01

    The precise reconstruction of the turbulent volume is a key point in the development of new-generation Adaptive Optics systems. We propose a new C2n profilometry method named CO-SLIDAR (COupled Slope and scIntillation Detection And Ranging), that uses correlations of slopes and scintillation indexes recorded on a Shack-Hartmann from two separated stars. CO-SLIDAR leads to an accurate C2n retrieval for both low and high altitude layers. Here, we present an end-to-end simulation of the C2n profile measurement. Two Shack-Hartmann geometries are considered. The detection noises are taken into account and a method to subtract the bias is proposed. Results are compared to C2n profiles obtained from correlations of slopes only or correlations of scintillation indexes only.

  9. Carotid blood flow measured by an ultrasonic volume flowmeter in carotid stenosis and patients with dementia.

    PubMed Central

    Uematsu, S; Folstein, M F

    1985-01-01

    The volume flowmeter is a simple, noninvasive Doppler ultrasound technique that provides accurate measurement of carotid artery diameter and flow. The device provides a useful laboratory test that can aid significantly in diagnosis of carotid stenosis and dementia. PMID:2935592

  10. Blood pressure measurement for accurate assessment of patient status in emergency medical settings.

    PubMed

    Convertino, Victor A

    2012-06-01

    Obtaining blood pressure measurements with traditional sphygomanometry that are insensitive and nonspecific can fail to provide an accurate assessment of patient status, particularly in specific clinical scenarios of acute reduction in central blood volume such as hemorrhage or orthostatic testing. This paper provides a review of newly emerging monitoring technologies that are being developed and integrated to improve patient diagnosis by using collection and feature extraction in real time of arterial waveforms by machine-learning algorithms. With assessment of continuous, noninvasively measured arterial waveforms, machine-learning algorithms have been developed with the capability to predict cardiovascular collapse with > 96% accuracy and a correlation of 0.89 between the time of predicted and actual cardiovascular collapse (e.g., shock, syncope) using a human model of progressive central hypovolemia. The resulting capability to obtain earlier predictions of imminent hemodynamic instability has significant implications for effective countermeasure applications by the aeromedical community. The ability to obtain real-time, continuous information about changes in features and patterns of arterial waveforms in addition to standard blood pressure provides for the first time the capability to assess the status of circulatory blood volume of the patient and can be used to diagnose progression toward development of syncope or overt shock, or guide fluid resuscitation. PMID:22764618

  11. Knowledge of accurate blood pressure measurement procedures in chiropractic students

    PubMed Central

    Crosley, Angela M.; Rose, James R. La

    2013-01-01

    Objective Blood pressure measurement is a basic clinical procedure. However, studies have shown that many errors are made when health care providers acquire blood pressure readings. Our study assessed knowledge of blood pressure measurement procedures in chiropractic students. Methods This was an observational, descriptive study. A questionnaire based on one created by the American Heart Association was given to 1st, 2nd, 3rd, and final year students (n = 186). A one way ANOVA was used to analyze the data. Results Of the students 80% were confident that their knowledge of this clinical skill was adequate or better. However, the overall score on the knowledge test of blood pressure–taking skills was 52% (range, 24%–88%). The only significant difference in the mean scores was between the 1st and 2nd year students compared to the 3rd and 4th year students (p < .005). Of the 16 questions given, the following mean scores were: 1st year 10.45, 2nd year 9.75, 3rd year 7.93, and 4th year 8.33. Of the 16 areas tested, 10 were of major concern (test item score <70%), showing the need for frequent retraining of chiropractic students. Conclusion Consistent with studies in other health care disciplines, our research found the knowledge of blood pressure skills to be deficient in our sample. There is a need for subsequent training in our teaching program. PMID:23957320

  12. Blood-Pressure Measuring System Gives Accurate Graphic Output

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The problem: To develop an instrument that will provide an external (indirect) measurement of arterial blood pressure in the form of an easily interpreted graphic trace that can be correlated with standard clinical blood-pressure measurements. From sphygmograms produced by conventional sphygmographs, it is very difficult to differentiate the systolic and diastolic blood-pressure pulses and to correlate these indices with the standard clinical values. It is nearly impossible to determine these indices when the subject is under physical or emotional stress. The solution: An electronic blood-pressure system, basically similar to conventional ausculatory sphygmomanometers, employing a standard occluding cuff, a gas-pressure source, and a gas-pressure regulator and valve. An electrical output transducer senses cuff pressure, and a microphone positioned on the brachial artery under the occluding cuff monitors the Korotkoff sounds from this artery. The output signals present the conventional systolic and diastolic indices in a clear, graphical display. The complete system also includes an electronic timer and cycle-control circuit.

  13. Fast and accurate automated measurements in digitized stereophotogrammetric radiographs.

    PubMed

    Vrooman, H A; Valstar, E R; Brand, G J; Admiraal, D R; Rozing, P M; Reiber, J H

    1998-05-01

    Until recently, Roentgen Stereophotogrammetric Analysis (RSA) required the manual definition of all markers using a high-resolution measurement table. To automate this tedious and time-consuming process and to eliminate observer variabilities, an analytical software package has been developed and validated for the detection, identification, and matching of markers in RSA radiographs. The digital analysis procedure consisted of the following steps: (1) the detection of markers using a variant of the Hough circle-finder technique; (2) the identification and labeling of the detected markers; (3) the reconstruction of the three-dimensional position of the bone markers and the prosthetic markers; and (4) the computation of micromotion. To assess the influence of film digitization, the measurements obtained from nine phantom radiographs using two different film scanners were compared with the results obtained by manual processing. All markers in the phantom radiographs were automatically detected and correctly labeled. The best results were obtained with a Vidar VXR-12 CCD scanner, for which the measurement errors were comparable to the errors associated with the manual approach. To assess the in vivo reproducibility, 30 patient radiographs were analyzed twice with the manual as well as with the automated procedure. Approximately, 85% of all calibration markers and bone markers were automatically detected and correctly matched. The calibration errors and the rigid-body errors show that the accuracy of the automated procedure is comparable to the accuracy of the manual procedure. The rigid-body errors had comparable mean values for both techniques: 0.05 mm for the tibia and 0.06 mm for the prosthesis. The reproducibility of the automated procedure showed to be slightly better than that of the manual procedure. The maximum errors in the computed translation and rotation of the tibial component were 0.11 mm and 0.24, compared to 0.13 mm and 0.27 for the manual RSA procedure

  14. Accurate on line measurements of low fluences of charged particles

    NASA Astrophysics Data System (ADS)

    Palla, L.; Czelusniak, C.; Taccetti, F.; Carraresi, L.; Castelli, L.; Fedi, M. E.; Giuntini, L.; Maurenzig, P. R.; Sottili, L.; Taccetti, N.

    2015-03-01

    Ion beams supplied by the 3MV Tandem accelerator of LABEC laboratory (INFN-Firenze), have been used to study the feasibility of irradiating materials with ion fluences reproducible to about 1%. Test measurements have been made with 7.5 MeV 7Li2+ beams of different intensities. The fluence control is based on counting ions contained in short bursts generated by chopping the continuous beam with an electrostatic deflector followed by a couple of adjustable slits. Ions are counted by means of a micro-channel plate (MCP) detecting the electrons emitted from a thin layer of Al inserted along the beam path in between the pulse defining slits and the target. Calibration of the MCP electron detector is obtained by comparison with the response of a Si detector.

  15. An Approach for the Accurate Measurement of Social Morality Levels

    PubMed Central

    Liu, Haiyan; Chen, Xia; Zhang, Bo

    2013-01-01

    In the social sciences, computer-based modeling has become an increasingly important tool receiving widespread attention. However, the derivation of the quantitative relationships linking individual moral behavior and social morality levels, so as to provide a useful basis for social policy-making, remains a challenge in the scholarly literature today. A quantitative measurement of morality from the perspective of complexity science constitutes an innovative attempt. Based on the NetLogo platform, this article examines the effect of various factors on social morality levels, using agents modeling moral behavior, immoral behavior, and a range of environmental social resources. Threshold values for the various parameters are obtained through sensitivity analysis; and practical solutions are proposed for reversing declines in social morality levels. The results show that: (1) Population size may accelerate or impede the speed with which immoral behavior comes to determine the overall level of social morality, but it has no effect on the level of social morality itself; (2) The impact of rewards and punishment on social morality levels follows the “5∶1 rewards-to-punishment rule,” which is to say that 5 units of rewards have the same effect as 1 unit of punishment; (3) The abundance of public resources is inversely related to the level of social morality; (4) When the cost of population mobility reaches 10% of the total energy level, immoral behavior begins to be suppressed (i.e. the 1/10 moral cost rule). The research approach and methods presented in this paper successfully address the difficulties involved in measuring social morality levels, and promise extensive application potentials. PMID:24312189

  16. Measurement of Human Blood and Plasma Volumes

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Szalkay, H. G. H.

    1987-01-01

    Report reviews techniques for measuring blood-plasma volume in humans. Common technique of using radioactive iodine isotope to label plasma albumin involves unwarranted risks from low-level radiation. Report emphasizes techniques using Evans-blue-dye (T-1824) labeling of albumin, hematocrit or hemoglobin/hematocrit measurements, or blood densitometry. In Evans-blue-dye technique, plasma volume determined from decrease in dye concentration occurring after small amount of dye solution injected into circulatory system. Subjection of Evans blue dye to test for carcinogenicity gave negative results.

  17. Induced Dual-Nanospray: A Novel Internal Calibration Method for Convenient and Accurate Mass Measurement

    NASA Astrophysics Data System (ADS)

    Li, Yafeng; Zhang, Ning; Zhou, Yueming; Wang, Jianing; Zhang, Yiming; Wang, Jiyun; Xiong, Caiqiao; Chen, Suming; Nie, Zongxiu

    2013-09-01

    Accurate mass information is of great importance in the determination of unknown compounds. An effective and easy-to-control internal mass calibration method will dramatically benefit accurate mass measurement. Here we reported a simple induced dual-nanospray internal calibration device which has the following three advantages: (1) the two sprayers are in the same alternating current field; thus both reference ions and sample ions can be simultaneously generated and recorded. (2) It is very simple and can be easily assembled. Just two metal tubes, two nanosprayers, and an alternating current power supply are included. (3) With the low-flow-rate character and the versatility of nanoESI, this calibration method is capable of calibrating various samples, even untreated complex samples such as urine and other biological samples with small sample volumes. The calibration errors are around 1 ppm in positive ion mode and 3 ppm in negative ion mode with good repeatability. This new internal calibration method opens up new possibilities in the determination of unknown compounds, and it has great potential for the broad applications in biological and chemical analysis.

  18. Volume-weighted measure for eternal inflation

    NASA Astrophysics Data System (ADS)

    Winitzki, Sergei

    2008-08-01

    I propose a new volume-weighted probability measure for cosmological “multiverse” scenarios involving eternal inflation. The “reheating-volume (RV) cutoff” calculates the distribution of observable quantities on a portion of the reheating hypersurface that is conditioned to be finite. The RV measure is gauge-invariant, does not suffer from the “youngness paradox,” and is independent of initial conditions at the beginning of inflation. In slow-roll inflationary models with a scalar inflaton, the RV-regulated probability distributions can be obtained by solving nonlinear diffusion equations. I discuss possible applications of the new measure to “landscape” scenarios with bubble nucleation. As an illustration, I compute the predictions of the RV measure in a simple toy landscape.

  19. Volume-weighted measure for eternal inflation

    SciTech Connect

    Winitzki, Sergei

    2008-08-15

    I propose a new volume-weighted probability measure for cosmological 'multiverse' scenarios involving eternal inflation. The 'reheating-volume (RV) cutoff' calculates the distribution of observable quantities on a portion of the reheating hypersurface that is conditioned to be finite. The RV measure is gauge-invariant, does not suffer from the 'youngness paradox', and is independent of initial conditions at the beginning of inflation. In slow-roll inflationary models with a scalar inflaton, the RV-regulated probability distributions can be obtained by solving nonlinear diffusion equations. I discuss possible applications of the new measure to 'landscape' scenarios with bubble nucleation. As an illustration, I compute the predictions of the RV measure in a simple toy landscape.

  20. Towards an optimized method of olive tree crown volume measurement.

    PubMed

    Miranda-Fuentes, Antonio; Llorens, Jordi; Gamarra-Diezma, Juan L; Gil-Ribes, Jesús A; Gil, Emilio

    2015-01-01

    Accurate crown characterization of large isolated olive trees is vital for adjusting spray doses in three-dimensional crop agriculture. Among the many methodologies available, laser sensors have proved to be the most reliable and accurate. However, their operation is time consuming and requires specialist knowledge and so a simpler crown characterization method is required. To this end, three methods were evaluated and compared with LiDAR measurements to determine their accuracy: Vertical Crown Projected Area method (VCPA), Ellipsoid Volume method (VE) and Tree Silhouette Volume method (VTS). Trials were performed in three different kinds of olive tree plantations: intensive, adapted one-trunked traditional and traditional. In total, 55 trees were characterized. Results show that all three methods are appropriate to estimate the crown volume, reaching high coefficients of determination: R2 = 0.783, 0.843 and 0.824 for VCPA, VE and VTS, respectively. However, discrepancies arise when evaluating tree plantations separately, especially for traditional trees. Here, correlations between LiDAR volume and other parameters showed that the Mean Vector calculated for VCPA method showed the highest correlation for traditional trees, thus its use in traditional plantations is highly recommended. PMID:25658396

  1. Towards an Optimized Method of Olive Tree Crown Volume Measurement

    PubMed Central

    Miranda-Fuentes, Antonio; Llorens, Jordi; Gamarra-Diezma, Juan L.; Gil-Ribes, Jesús A.; Gil, Emilio

    2015-01-01

    Accurate crown characterization of large isolated olive trees is vital for adjusting spray doses in three-dimensional crop agriculture. Among the many methodologies available, laser sensors have proved to be the most reliable and accurate. However, their operation is time consuming and requires specialist knowledge and so a simpler crown characterization method is required. To this end, three methods were evaluated and compared with LiDAR measurements to determine their accuracy: Vertical Crown Projected Area method (VCPA), Ellipsoid Volume method (VE) and Tree Silhouette Volume method (VTS). Trials were performed in three different kinds of olive tree plantations: intensive, adapted one-trunked traditional and traditional. In total, 55 trees were characterized. Results show that all three methods are appropriate to estimate the crown volume, reaching high coefficients of determination: R2 = 0.783, 0.843 and 0.824 for VCPA, VE and VTS, respectively. However, discrepancies arise when evaluating tree plantations separately, especially for traditional trees. Here, correlations between LiDAR volume and other parameters showed that the Mean Vector calculated for VCPA method showed the highest correlation for traditional trees, thus its use in traditional plantations is highly recommended. PMID:25658396

  2. Method of measuring a liquid pool volume

    DOEpatents

    Garcia, G.V.; Carlson, N.M.; Donaldson, A.D.

    1991-03-19

    A method of measuring a molten metal liquid pool volume and in particular molten titanium liquid pools is disclosed, including the steps of (a) generating an ultrasonic wave at the surface of the molten metal liquid pool, (b) shining a light on the surface of a molten metal liquid pool, (c) detecting a change in the frequency of light, (d) detecting an ultrasonic wave echo at the surface of the molten metal liquid pool, and (e) computing the volume of the molten metal liquid. 3 figures.

  3. Air volume measurement of 'Braeburn' apple fruit.

    PubMed

    Drazeta, Lazar; Lang, Alexander; Hall, Alistair J; Volz, Richard K; Jameson, Paula E

    2004-05-01

    The radial disposition of air in the flesh of fruit of Malus domestica Borkh., cv 'Braeburn' was investigated using a gravimetric technique based on Archimedes' principle. Intercellular air volume was measured by weighing a small tissue sample under water before and after vacuum infiltration to remove the air. In a separate procedure, the volume of the same sample was measured by recording the buoyant upthrust experienced by it when fully immersed in water. The method underestimates tissue air volume due to a slight invasion of the intercellular air spaces around the edges of the sample when it is immersed in water. To correct for this error, an adjustment factor was made based upon an analysis of a series of measurements of air volume in samples of different dimensions. In 'Braeburn' there is a gradient of declining air content from just beneath the skin to the centre of the fruit with a sharp discontinuity at the core line. Cell shape and cell packing were observed in the surface layers of freshly excised and stained flesh samples using a dissecting microscope coupled to a video camera and a PC running proprietary software. Tissue organization changed with distance below the skin. It is speculated that reduced internal gas movement, due to the tightly packed tissue of 'Braeburn' and to the potential diffusion barrier at the core line between the cortex and the pith, may increase susceptibility of the flesh to disorders associated with tissue browning and breakdown. PMID:15047764

  4. Postmortem validation of MRI cortical volume measurements in MS.

    PubMed

    Popescu, Veronica; Klaver, Roel; Versteeg, Adriaan; Voorn, Pieter; Twisk, Jos W R; Barkhof, Frederik; Geurts, Jeroen J G; Vrenken, Hugo

    2016-06-01

    Grey matter (GM) atrophy is a prominent aspect of multiple sclerosis pathology and an important outcome in studies. GM atrophy measurement requires accurate GM segmentation. Several methods are used in vivo for measuring GM volumes in MS, but assessing their validity in vivo remains challenging. In this postmortem study, we evaluated the correlation between postmortem MRI cortical volume or thickness and the cortical thickness measured on histological sections. Sixteen MS brains were scanned in situ using 3DT1-weighted MRI and these images were used to measure regional cortical volume using FSL-SIENAX, FreeSurfer, and SPM, and regional cortical thickness using FreeSurfer. Subsequently, cortical thickness was measured histologically in 5 systematically sampled cortical areas. Linear regression analyses were used to evaluate the relation between MRI regional cortical volume or thickness and histological cortical thickness to determine which postprocessing technique was most valid. After correction for multiple comparisons, we observed a significant correlation with the histological cortical thickness for FSL-SIENAX cortical volume with manual editing (std. β = 0.345, adjusted R(2)  = 0.105, P = 0.005), and FreeSurfer cortical volume with manual editing (std. β = 0.379, adjusted R(2)  = 0.129, P = 0.003). In addition, there was a significant correlation between FreeSurfer cortical thickness with manual editing and histological cortical thickness (std. β = 0.381, adjusted R(2)  = 0.130, P = 0.003). The results support the use of FSL-SIENAX and FreeSurfer in cases of severe MS pathology. Interestingly none of the methods were significant in automated mode, which supports the use of manual editing to improve the automated segmentation. Hum Brain Mapp 37:2223-2233, 2016. © 2016 Wiley Periodicals, Inc. PMID:26945922

  5. Extracting accurate strain measurements in bone mechanics: A critical review of current methods.

    PubMed

    Grassi, Lorenzo; Isaksson, Hanna

    2015-10-01

    Osteoporosis related fractures are a social burden that advocates for more accurate fracture prediction methods. Mechanistic methods, e.g. finite element models, have been proposed as a tool to better predict bone mechanical behaviour and strength. However, there is little consensus about the optimal constitutive law to describe bone as a material. Extracting reliable and relevant strain data from experimental tests is of fundamental importance to better understand bone mechanical properties, and to validate numerical models. Several techniques have been used to measure strain in experimental mechanics, with substantial differences in terms of accuracy, precision, time- and length-scale. Each technique presents upsides and downsides that must be carefully evaluated when designing the experiment. Moreover, additional complexities are often encountered when applying such strain measurement techniques to bone, due to its complex composite structure. This review of literature examined the four most commonly adopted methods for strain measurements (strain gauges, fibre Bragg grating sensors, digital image correlation, and digital volume correlation), with a focus on studies with bone as a substrate material, at the organ and tissue level. For each of them the working principles, a summary of the main applications to bone mechanics at the organ- and tissue-level, and a list of pros and cons are provided. PMID:26099201

  6. The accurate measurement of second virial coefficients using self-interaction chromatography: experimental considerations.

    PubMed

    Quigley, A; Heng, J Y Y; Liddell, J M; Williams, D R

    2013-11-01

    Measurement of B22, the second virial coefficient, is an important technique for describing the solution behaviour of proteins, especially as it relates to precipitation, aggregation and crystallisation phenomena. This paper describes the best practise for calculating B22 values from self-interaction chromatograms (SIC) for aqueous protein solutions. Detailed analysis of SIC peak shapes for lysozyme shows that non-Gaussian peaks are commonly encountered for SIC, with typical peak asymmetries of 10%. This asymmetry reflects a non-linear chromatographic retention process, in this case heterogeneity of the protein-protein interactions. Therefore, it is important to use the centre of mass calculations for determining accurate retention volumes and thus B22 values. Empirical peak maximum chromatogram analysis, often reported in the literature, can result in errors of up to 50% in B22 values. A methodology is reported here for determining both the mean and the variance in B22 from SIC experiments, includes a correction for normal longitudinal peak broadening. The variance in B22 due to chemical effects is quantified statistically and is a measure of the heterogeneity of protein-protein interactions in solution. In the case of lysozyme, a wide range of B22 values are measured which can vary significantly from the average B22 values. PMID:23623796

  7. Accurate Analysis of the Change in Volume, Location, and Shape of Metastatic Cervical Lymph Nodes During Radiotherapy

    SciTech Connect

    Takao, Seishin; Tadano, Shigeru; Taguchi, Hiroshi; Yasuda, Koichi; Onimaru, Rikiya; Ishikawa, Masayori; Bengua, Gerard; Suzuki, Ryusuke; Shirato, Hiroki

    2011-11-01

    Purpose: To establish a method for the accurate acquisition and analysis of the variations in tumor volume, location, and three-dimensional (3D) shape of tumors during radiotherapy in the era of image-guided radiotherapy. Methods and Materials: Finite element models of lymph nodes were developed based on computed tomography (CT) images taken before the start of treatment and every week during the treatment period. A surface geometry map with a volumetric scale was adopted and used for the analysis. Six metastatic cervical lymph nodes, 3.5 to 55.1 cm{sup 3} before treatment, in 6 patients with head and neck carcinomas were analyzed in this study. Three fiducial markers implanted in mouthpieces were used for the fusion of CT images. Changes in the location of the lymph nodes were measured on the basis of these fiducial markers. Results: The surface geometry maps showed convex regions in red and concave regions in blue to ensure that the characteristics of the 3D tumor geometries are simply understood visually. After the irradiation of 66 to 70 Gy in 2 Gy daily doses, the patterns of the colors had not changed significantly, and the maps before and during treatment were strongly correlated (average correlation coefficient was 0.808), suggesting that the tumors shrank uniformly, maintaining the original characteristics of the shapes in all 6 patients. The movement of the gravitational center of the lymph nodes during the treatment period was everywhere less than {+-}5 mm except in 1 patient, in whom the change reached nearly 10 mm. Conclusions: The surface geometry map was useful for an accurate evaluation of the changes in volume and 3D shapes of metastatic lymph nodes. The fusion of the initial and follow-up CT images based on fiducial markers enabled an analysis of changes in the location of the targets. Metastatic cervical lymph nodes in patients were suggested to decrease in size without significant changes in the 3D shape during radiotherapy. The movements of the

  8. ACCURATE: Greenhouse Gas Profiles Retrieval from Combined IR-Laser and Microwave Occultation Measurements

    NASA Astrophysics Data System (ADS)

    Proschek, Veronika; Kirchengast, Gottfried; Schweitzer, Susanne; Fritzer, Johannes

    2010-05-01

    The new climate satellite concept ACCURATE (Atmospheric Climate and Chemistry in the UTLS Region And climate Trends Explorer) enables simultaneous measurement of profiles of greenhouse gases, isotopes, wind and thermodynamic variables from Low Earth Orbit (LEO) satellites. The measurement principle applied is a combination of the novel LEO-LEO infrared laser occultation (LIO) technique and the already better studied LEO-LEO microwave occultation (LMO) technique. Resulting occultation events are evenly distributed around the world, have high vertical resolution and accuracy and are stable over long time periods. The LIO uses near-monochromatic signals in the short-wave infrared range (~2-2.5 μm for ACCURATE). These signals are absorbed by various trace species in the Earth's atmosphere. Profiles of the concentration of the absorbing species can be derived from signal transmission measurements. Accurately known temperature, pressure and humidity profiles derived from simultaneously measured LMO signals are essential pre-information for the retrieval of the trace species profiles. These LMO signals lie in the microwave band region from 17-23 GHz and, optionally, 178-195 GHz. The current ACCURATE mission design is arranged for the measurement of six greenhouse gases (GHG) (H2O, CO2, CH4, N2O, O3, CO) and four isotopes (13CO2, C18OO, HDO, H218O), with focus on the upper troposphere/lower stratosphere region (UTLS, 5-35 km). Wind speed in line-of-sight can be derived from a line-symmetric transmission difference which is caused by wind-induced Doppler shift. By-products are information on cloud layering, aerosol extinction, and scintillation strength. We introduce the methodology to retrieve GHG profiles from quasi-realistic forward-simulated intensities of LIO signals and thermodynamic profiles retrieved in a preceding step from LMO signals. Key of the retrieval methodology is the differencing of two LIO transmission signals, one being GHG sensitive on a target

  9. Accurate and efficient Nyström volume integral equation method for the Maxwell equations for multiple 3-D scatterers

    NASA Astrophysics Data System (ADS)

    Chen, Duan; Cai, Wei; Zinser, Brian; Cho, Min Hyung

    2016-09-01

    In this paper, we develop an accurate and efficient Nyström volume integral equation (VIE) method for the Maxwell equations for a large number of 3-D scatterers. The Cauchy Principal Values that arise from the VIE are computed accurately using a finite size exclusion volume together with explicit correction integrals consisting of removable singularities. Also, the hyper-singular integrals are computed using interpolated quadrature formulae with tensor-product quadrature nodes for cubes, spheres and cylinders, that are frequently encountered in the design of meta-materials. The resulting Nyström VIE method is shown to have high accuracy with a small number of collocation points and demonstrates p-convergence for computing the electromagnetic scattering of these objects. Numerical calculations of multiple scatterers of cubic, spherical, and cylindrical shapes validate the efficiency and accuracy of the proposed method.

  10. Measuring Pressure Volume Loops in the Mouse.

    PubMed

    Townsend, DeWayne

    2016-01-01

    Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the mouse provides great potential to explore cardiac function at the molecular level. The mouse's small size does present some challenges in regards to performing detailed cardiac phenotyping. Miniaturization and other advancements in technology have made many methods of cardiac assessment possible in the mouse. Of these, the simultaneous collection of pressure and volume data provides a detailed picture of cardiac function that is not available through any other modality. Here a detailed procedure for the collection of pressure-volume loop data is described. Included is a discussion of the principles underlying the measurements and the potential sources of error. Anesthetic management and surgical approaches are discussed in great detail as they are both critical to obtaining high quality hemodynamic measurements. The principles of hemodynamic protocol development and relevant aspects of data analysis are also addressed. PMID:27166576

  11. A bronchoscopic navigation system using bronchoscope center calibration for accurate registration of electromagnetic tracker and CT volume without markers

    SciTech Connect

    Luo, Xiongbiao

    2014-06-15

    Purpose: Various bronchoscopic navigation systems are developed for diagnosis, staging, and treatment of lung and bronchus cancers. To construct electromagnetically navigated bronchoscopy systems, registration of preoperative images and an electromagnetic tracker must be performed. This paper proposes a new marker-free registration method, which uses the centerlines of the bronchial tree and the center of a bronchoscope tip where an electromagnetic sensor is attached, to align preoperative images and electromagnetic tracker systems. Methods: The chest computed tomography (CT) volume (preoperative images) was segmented to extract the bronchial centerlines. An electromagnetic sensor was fixed at the bronchoscope tip surface. A model was designed and printed using a 3D printer to calibrate the relationship between the fixed sensor and the bronchoscope tip center. For each sensor measurement that includes sensor position and orientation information, its corresponding bronchoscope tip center position was calculated. By minimizing the distance between each bronchoscope tip center position and the bronchial centerlines, the spatial alignment of the electromagnetic tracker system and the CT volume was determined. After obtaining the spatial alignment, an electromagnetic navigation bronchoscopy system was established to real-timely track or locate a bronchoscope inside the bronchial tree during bronchoscopic examinations. Results: The electromagnetic navigation bronchoscopy system was validated on a dynamic bronchial phantom that can simulate respiratory motion with a breath rate range of 0–10 min{sup −1}. The fiducial and target registration errors of this navigation system were evaluated. The average fiducial registration error was reduced from 8.7 to 6.6 mm. The average target registration error, which indicates all tracked or navigated bronchoscope position accuracy, was much reduced from 6.8 to 4.5 mm compared to previous registration methods. Conclusions: An

  12. Small and cheap: accurate differential blood count with minimal sample volume by laser scanning cytometry (LSC)

    NASA Astrophysics Data System (ADS)

    Mittag, Anja; Lenz, Dominik; Smith, Paul J.; Pach, Susanne; Tarnok, Attila

    2005-04-01

    Aim: In patients, e.g. with congenital heart diseases, a differential blood count is needed for diagnosis. To this end by standard automatic analyzers 500 μl of blood is required from the patients. In case of newborns and infants this is a substantial volume, especially after operations associated with blood loss. Therefore, aim of this study was to develop a method to determine a differential blood picture with a substantially reduced specimen volume. Methods: To generate a differential blood picture 10 μl EDTA blood were mixed with 10 μl of a DRAQ5 solution (500μM, Biostatus) and 10 μl of an antibody mixture (CD45-FITC, CD14-PE, diluted with PBS). 20 μl of this cell suspension was filled into a Neubauer counting chamber. Due to the defined volume of the chamber it is possible to determine the cell count per volume. The trigger for leukocyte counting was set on DRAQ5 signal in order to be able to distinguish nucleated white blood cells from erythrocytes. Different leukocyte subsets could be distinguished due to the used fluorescence labeled antibodies. For erythrocyte counting cell suspension was diluted another 150 times. 20 μl of this dilution was analyzed in a microchamber by LSC with trigger set on forward scatter signal. Results: This method allows a substantial decrease of blood sample volume for generation of a differential blood picture (10 μl instead of 500μl). There was a high correlation between our method and the results of routine laboratory (r2=0.96, p<0.0001 n=40). For all parameters intra-assay variance was less than 7 %. Conclusions: In patients with low blood volume such as neonates and in critically ill infants every effort has to be taken to reduce the blood volume needed for diagnostics. With this method only 2% of standard sample volume is needed to generate a differential blood picture. Costs are below that of routine laboratory. We suggest this method to be established in paediatric cardiology for routine diagnostics and for

  13. Volume and Surface Measurements from Tomographic Images: in Vivo Validation of AN Unsupervised Method

    NASA Astrophysics Data System (ADS)

    Alyassin, Abdalmajeid Musa

    The maximum unit normal component method (MUNC) used for surface area measurement and the divergence theorem algorithm (DTA) used for volume measurement were evaluated in vitro and validated in vivo. To evaluate these methods in vitro, their accuracy and precision were investigated at varying conditions of signal-to-noise ratio (SNR), sampling, volume averaging, and orientation. These algorithms were also enhanced to provide interactive surface area and volume measurements for regions bounded by orthogonal cut planes. The in vitro evaluations showed that a minimum SNR of 6:1 was necessary to provide accurate surface area and volume measurements. This test also revealed surface area measurements were more sensitive to noise than volume measurement. Sampling tests showed that at least twelve samples across the shortest dimension of simulated objects are necessary to provide accurate surface area and volume measurements. Volume averaging tests, however, revealed that at least seven voxels across the diameter (51.44 mm) of a computed tomography wooden sphere image are necessary for accurate surface area and volume measurements. Orientation tests indicated that the accuracy of the measured surface area and volume was primarily dependent on the number of samples across the shortest dimension of the object. Interactive measurement tests proved that the enhanced algorithms can provide accurate and precise interactive surface area and volume measurements. To validate the investigated algorithms in vivo, an unsupervised method incorporating these algorithms was developed for measuring surface area and volume of the urinary bladder using dual-echo, T2-weighted magnetic resonance images. Accuracy and precision of the unsupervised method in estimating urine volumes in vivo for nine normal subjects were <5%. Results from in vitro evaluations show that volume measured using the DTA method compares well with the volume measured by a proven voxel counting method. The MUNC method

  14. 21 CFR 864.5950 - Blood volume measuring device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Blood volume measuring device. 864.5950 Section... § 864.5950 Blood volume measuring device. (a) Identification. A blood volume measuring device is a..., and total blood volume. (b) Classification. Class II (performance standards)....

  15. Simple and accurate empirical absolute volume calibration of a multi-sensor fringe projection system

    NASA Astrophysics Data System (ADS)

    Gdeisat, Munther; Qudeisat, Mohammad; AlSa`d, Mohammed; Burton, David; Lilley, Francis; Ammous, Marwan M. M.

    2016-05-01

    This paper suggests a novel absolute empirical calibration method for a multi-sensor fringe projection system. The optical setup of the projector-camera sensor can be arbitrary. The term absolute calibration here means that the centre of the three dimensional coordinates in the resultant calibrated volume coincides with a preset centre to the three-dimensional real-world coordinate system. The use of a zero-phase fringe marking spot is proposed to increase depth calibration accuracy, where the spot centre is determined with sub-pixel accuracy. Also, a new method is proposed for transversal calibration. Depth and transversal calibration methods have been tested using both single sensor and three-sensor fringe projection systems. The standard deviation of the error produced by this system is 0.25 mm. The calibrated volume produced by this method is 400 mm×400 mm×140 mm.

  16. Measurement of intravesicular volumes by salt entrapment.

    PubMed

    Gruber, H J; Wilmsen, H U; Schurga, A; Pilger, A; Schindler, H

    1995-12-13

    Internal volume is a very sensitive parameter of vesicle morphology. Measurement of captured volumes by solute entrapment is legitimate for most types of vesicles (Perkin, W.R. et al. (1993) Chem. Phys. Lipids 64, 197-217). In this study chloride was selected as the most convenient marker ion because the ubiquity of Cl- in physiological buffers eliminates prelabeling with exogenous markers and because minute concentrations of trapped chloride are well detectable in the presence of large extravesicular nitrate concentrations. Perfect exchange of external chloride for nitrate was shown to be accomplished by gel filtration, dialysis, or sucrose gradient flotation-but only after significant technical improvements and/or elimination of experimental pitfalls. Reliability was cross-checked by simultaneous entrapment of Cl- and K+. Diafiltration and ion exchange chromatography appeared inapplicable for exchange of extravesicular salt. When a representative variety of vesicle preparations was analyzed for internal volume (as well as for external surface and size) unexpected features of vesicle morphology were discovered. This emphasizes the genuine role of macroscopic vesicle characterization in complementing information from electron microscopy. PMID:8541298

  17. Accurate measurement of the electron beam polarization in JLab Hall A using Compton polarimetry

    SciTech Connect

    S. Escoffier; P.Y. Bertin; M. Brossard; E. Burtin; C. Cavata; N. Colombel; C.W. de Jager; A. Delbart; D. Lhuillier; F. Marie; J. Mitchell; D. Neyret; T. Pussieux

    2005-05-01

    A major advance in accurate electron beam polarization measurement has been achieved at Jlab Hall A with a Compton polarimeter based on a Fabry-Perot cavity photon beam amplifier. At an electron energy of 4.6 GeV and a beam current of 40 uA, a total relative uncertainty of 1.5% is typically achieved within 40 min of data taking. Under the same conditions monitoring of the polarization is accurate at a level of 1%. These unprecedented results make Compton polarimetry an essential tool for modern parity-violation experiments, which require very accurate electron beam polarization measurements.

  18. Benchmarking of a New Finite Volume Shallow Water Code for Accurate Tsunami Modelling

    NASA Astrophysics Data System (ADS)

    Reis, Claudia; Clain, Stephane; Figueiredo, Jorge; Baptista, Maria Ana; Miranda, Jorge Miguel

    2015-04-01

    Finite volume methods used to solve the shallow-water equation with source terms receive great attention on the two last decades due to its fundamental properties: the built-in conservation property, the capacity to treat correctly discontinuities and the ability to handle complex bathymetry configurations preserving the some steady-state configuration (well-balanced scheme). Nevertheless, it is still a challenge to build an efficient numerical scheme, with very few numerical artifacts (e.g. numerical diffusion) which can be used in an operational environment, and are able to better capture the dynamics of the wet-dry interface and the physical phenomenon that occur in the inundation area. We present here a new finite volume code and benchmark it against analytical and experimental results, and we test the performance of the code in the complex topographic of the Tagus Estuary, close to Lisbon, Portugal. This work is funded by the Portugal-France research agreement, through the research project FCT-ANR/MAT-NAN/0122/2012.

  19. Accurate polynomial expressions for the density and specific volume of seawater using the TEOS-10 standard

    NASA Astrophysics Data System (ADS)

    Roquet, F.; Madec, G.; McDougall, Trevor J.; Barker, Paul M.

    2015-06-01

    A new set of approximations to the standard TEOS-10 equation of state are presented. These follow a polynomial form, making it computationally efficient for use in numerical ocean models. Two versions are provided, the first being a fit of density for Boussinesq ocean models, and the second fitting specific volume which is more suitable for compressible models. Both versions are given as the sum of a vertical reference profile (6th-order polynomial) and an anomaly (52-term polynomial, cubic in pressure), with relative errors of ∼0.1% on the thermal expansion coefficients. A 75-term polynomial expression is also presented for computing specific volume, with a better accuracy than the existing TEOS-10 48-term rational approximation, especially regarding the sound speed, and it is suggested that this expression represents a valuable approximation of the TEOS-10 equation of state for hydrographic data analysis. In the last section, practical aspects about the implementation of TEOS-10 in ocean models are discussed.

  20. Is scintillometer measurement accurate enough for evaluating remote sensing based energy balance ET models?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The three evapotranspiration (ET) measurement/retrieval techniques used in this study, lysimeter, scintillometer and remote sensing vary in their level of complexity, accuracy, resolution and applicability. The lysimeter with its point measurement is the most accurate and direct method to measure ET...

  1. Measurements of hair volume by laser stereometry.

    PubMed

    McMullen, Roger; Zisa, Franco; Jachowicz, Janusz

    2009-01-01

    A three-dimensional laser stereometer was constructed utilizing an x-y two-dimensional translational stage and a laser device, which provides distance information in the z-direction. The distance data is obtained by triangulation of the reflecting red laser beam from the surface of the measured object, in this case hair. Since hair fiber assemblies do not have a continuous solid surface, each z-dimension reading is obtained as an average of measurements obtained from multiple reflections corresponding to fibers at various depths below the outermost hair surface. We demonstrate the utility of this technique to perform the analysis of either an entire hair tress or relatively short sections of tresses prepared from straight, curly, and frizzy hair and subjected to cosmetic treatments such as washing, conditioning, dyeing, etc. An interpretation is provided for the three-dimensional images of hair assemblies as well as for the calculated volume of space occupied by a hair tress. In addition, we investigated various strategies for testing the volume retention of styling polymers. PMID:19450418

  2. Measuring accurate body parameters of dressed humans with large-scale motion using a Kinect sensor.

    PubMed

    Xu, Huanghao; Yu, Yao; Zhou, Yu; Li, Yang; Du, Sidan

    2013-01-01

    Non-contact human body measurement plays an important role in surveillance, physical healthcare, on-line business and virtual fitting. Current methods for measuring the human body without physical contact usually cannot handle humans wearing clothes, which limits their applicability in public environments. In this paper, we propose an effective solution that can measure accurate parameters of the human body with large-scale motion from a Kinect sensor, assuming that the people are wearing clothes. Because motion can drive clothes attached to the human body loosely or tightly, we adopt a space-time analysis to mine the information across the posture variations. Using this information, we recover the human body, regardless of the effect of clothes, and measure the human body parameters accurately. Experimental results show that our system can perform more accurate parameter estimation on the human body than state-of-the-art methods. PMID:24064597

  3. Mechanical device accurately measures rf phase differences in vhf or uhf ranges

    NASA Technical Reports Server (NTRS)

    Hopp, L. A.

    1966-01-01

    Dual range linear measurement device accurately measures RF phase differences in either VHF or UHF ranges. The device has a capability consisting of a course range extending to 30 cm readable to 1 mm and any fine range portion of 2.5 cm readable to .01 mm.

  4. MASS MEASUREMENTS BY AN ACCURATE AND SENSITIVE SELECTED ION RECORDING TECHNIQUE

    EPA Science Inventory

    Trace-level components of mixtures were successfully identified or confirmed by mass spectrometric accurate mass measurements, made at high resolution with selected ion recording, using GC and LC sample introduction. Measurements were made at 20 000 or 10 000 resolution, respecti...

  5. Semiautomatic Regional Segmentation to Measure Orbital Fat Volumes in Thyroid-Associated Ophthalmopathy

    PubMed Central

    Comerci, M.; Elefante, A.; Strianese, D.; Senese, R.; Bonavolontà, P.; Alfano, B.; Bonavolontà, G.; Brunetti, A.

    2013-01-01

    Summary This study was designed to validate a novel semi-automated segmentation method to measure regional intra-orbital fat tissue volume in Graves' ophthalmopathy. Twenty-four orbits from 12 patients with Graves' ophthalmopathy, 24 orbits from 12 controls, ten orbits from five MRI study simulations and two orbits from a digital model were used. Following manual region of interest definition of the orbital volumes performed by two operators with different levels of expertise, an automated procedure calculated intra-orbital fat tissue volumes (global and regional, with automated definition of four quadrants). In patients with Graves' disease, clinical activity score and degree of exophthalmos were measured and correlated with intra-orbital fat volumes. Operator performance was evaluated and statistical analysis of the measurements was performed. Accurate intra-orbital fat volume measurements were obtained with coefficients of variation below 5%. The mean operator difference in total fat volume measurements was 0.56%. Patients had significantly higher intra-orbital fat volumes than controls (p<0.001 using Student's t test). Fat volumes and clinical score were significantly correlated (p<0.001). The semi-automated method described here can provide accurate, reproducible intra-orbital fat measurements with low inter-operator variation and good correlation with clinical data. PMID:24007725

  6. Measurement Corner: Volume, Temperature and Pressure

    ERIC Educational Resources Information Center

    Teates, Thomas G.

    1977-01-01

    Boyle's Law and basic relationships between volume and pressure of a gas at constant temperature are presented. Suggests two laboratory activities for demonstrating the effect of temperature on the volume of a gas or liquid. (CS)

  7. A Time-Accurate Upwind Unstructured Finite Volume Method for Compressible Flow with Cure of Pathological Behaviors

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Jorgenson, Philip C. E.

    2007-01-01

    A time-accurate, upwind, finite volume method for computing compressible flows on unstructured grids is presented. The method is second order accurate in space and time and yields high resolution in the presence of discontinuities. For efficiency, the Roe approximate Riemann solver with an entropy correction is employed. In the basic Euler/Navier-Stokes scheme, many concepts of high order upwind schemes are adopted: the surface flux integrals are carefully treated, a Cauchy-Kowalewski time-stepping scheme is used in the time-marching stage, and a multidimensional limiter is applied in the reconstruction stage. However even with these up-to-date improvements, the basic upwind scheme is still plagued by the so-called "pathological behaviors," e.g., the carbuncle phenomenon, the expansion shock, etc. A solution to these limitations is presented which uses a very simple dissipation model while still preserving second order accuracy. This scheme is referred to as the enhanced time-accurate upwind (ETAU) scheme in this paper. The unstructured grid capability renders flexibility for use in complex geometry; and the present ETAU Euler/Navier-Stokes scheme is capable of handling a broad spectrum of flow regimes from high supersonic to subsonic at very low Mach number, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics). Numerous examples are included to demonstrate the robustness of the methods.

  8. Uterine fibroid segmentation and volume measurement on MRI

    NASA Astrophysics Data System (ADS)

    Yao, Jianhua; Chen, David; Lu, Wenzhu; Premkumar, Ahalya

    2006-03-01

    Uterine leiomyomas are the most common pelvic tumors in females. The efficacy of medical treatment is gauged by shrinkage of the size of these tumors. In this paper, we present a method to robustly segment the fibroids on MRI and accurately measure the 3D volume. Our method is based on a combination of fast marching level set and Laplacian level set. With a seed point placed inside the fibroid region, a fast marching level set is first employed to obtain a rough segmentation, followed by a Laplacian level set to refine the segmentation. We devised a scheme to automatically determine the parameters for the level set function and the sigmoid function based on pixel statistics around the seed point. The segmentation is conducted on three concurrent views (axial, coronal and sagittal), and a combined volume measurement is computed to obtain a more reliable measurement. We carried out extensive tests on 13 patients, 25 MRI studies and 133 fibroids. The segmentation result was validated against manual segmentation defined by experts. The average segmentation sensitivity (true positive fraction) among all fibroids was 84.6%, and the average segmentation specificity (1-false positive fraction) was 84.3%.

  9. Estimation of rat mammary tumor volume using caliper and ultrasonography measurements.

    PubMed

    Faustino-Rocha, Ana; Oliveira, Paula A; Pinho-Oliveira, Jacinta; Teixeira-Guedes, Catarina; Soares-Maia, Ruben; da Costa, Rui Gil; Colaço, Bruno; Pires, Maria João; Colaço, Jorge; Ferreira, Rita; Ginja, Mário

    2013-06-01

    Mammary tumors similar to those observed in women can be induced in rats by intraperitoneal administration of N-methyl-N-nitrosourea. Determining tumor volume is a useful and quantitative way to monitor tumor progression. In this study, the authors measured dimensions of rat mammary tumors using a caliper and using real-time compound B-mode ultrasonography. They then used different formulas to calculate tumor volume from these tumor measurements and compared the calculated tumor volumes with the real tumor volume to identify the formulas that gave the most accurate volume calculations. They found that caliper and ultrasonography measurements were significantly correlated but that tumor volumes calculated using different formulas varied substantially. Mammary tumors seemed to take on an oblate spheroid geometry. The most accurate volume calculations were obtained using the formula V = (W(2) × L)/2 for caliper measurements and the formula V = (4/3) × π × (L/2) × (L/2) × (D/2) for ultrasonography measurements, where V is tumor volume, W is tumor width, L is tumor length and D is tumor depth. PMID:23689461

  10. Volume measurement by ultrasonic transverse or sagittal cross-sectional scanning.

    PubMed

    Basset, O; Gimenez, G; Mestas, J L; Cathignol, D; Devonec, M

    1991-01-01

    A technique is described that provides an accurate estimation of the volume of an organ from its ultrasonic cross-sectional images. The technique is applied to two types of ultrasonic investigation, one providing transverse and the other sagittal images. The organ outline has to be traced on each scan. The computer first calculates the area and then the volume from the vector areas and the centroids of a series of sections. The technique has been tested with phantoms of various shapes and volumes made with agar gel. These experiments show that the error in the volume estimation is less than 10% and the variability of measurements is less than 2%. PMID:1887514

  11. Improved techniques for measurement of nanolitre volumes of phloem exudate from aphid stylectomy

    PubMed Central

    2013-01-01

    Background When conducting aphid stylectomy, measuring accurate rates of phloem exudation is difficult because the volumes collected are in the nanolitre (nl) range. In a new method, exudate volume was calculated from optical measurement of droplet diameter as it forms on the tip of a severed aphid stylet. Evaporation was shown to decrease the accuracy of the measurement but was countered with the addition of water-saturated mineral oil. Volume measurements by optical estimation of the volume of a sphere suspended in oil was affected by the curvature of the oil surface. In contrast, measuring the exudate volume from optical measurement of droplet-diameter as formed on the tip of a severed aphid stylet, removes any inaccuracies due to oil surface curvature. A modified technique is proposed for measuring exudate volumes without oil by estimating the flow rate from photo-sequences of the collection period; a correction for evaporation is applied later. Results A change in oil volume of ±1.75% from an optimum volume of 285 μl had a statistically significant effect on droplet measurement, under or over-estimating droplet volume due to optical effects caused by the oil surface. Using microscope image capture and measurement software, a modified method for measuring phloem volume in air was developed, by reducing air exposure during measurement to approximately 5 s for each measurement. Phloem volumes were measured using both techniques with measurements in air being on average 19.9 nl less (SD 18.87, p<0.001) than those made in oil, and there was a strong linear relationship (R2=0.942) between the techniques. This linear relationship enabled the development of a correction equation with no significant difference at the 5% level between corrected volumes and actual volumes measured under oil. Conclusions This study showed that oil has a significant role in countering evaporation but oil volume must be carefully optimised for optical measurement of droplets to ensure

  12. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate measurements of the secondary metabolites in natural products and plant foods are critical to establishing diet/health relationships. There are as many as 50,000 secondary metabolites which may influence human health. Their structural and chemical diversity present a challenge to analytic...

  13. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, Charles V.; Killian, E. Wayne; Grafwallner, Ervin G.; Kynaston, Ronnie L.; Johnson, Larry O.; Randolph, Peter D.

    1996-01-01

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector.

  14. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, C.V.; Killian, E.W.; Grafwallner, E.G.; Kynaston, R.L.; Johnson, L.O.; Randolph, P.D.

    1996-09-03

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector. 7 figs.

  15. Techniques for determining propulsion system forces for accurate high speed vehicle drag measurements in flight

    NASA Technical Reports Server (NTRS)

    Arnaiz, H. H.

    1975-01-01

    As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.

  16. Development of a high accurate gear measuring machine based on laser interferometry

    NASA Astrophysics Data System (ADS)

    Lin, Hu; Xue, Zi; Yang, Guoliang; Huang, Yao; Wang, Heyan

    2015-02-01

    Gear measuring machine is a specialized device for gear profile, helix or pitch measurement. The classic method for gear measurement and the conventional gear measuring machine are introduced. In this gear measuring machine, the Abbe errors arisen from the angle error of guideways hold a great weight in affection of profile measurement error. For minimize of the Abbe error, a laser measuring system is applied to develop a high accurate gear measuring machine. In this laser measuring system, two cube-corner reflectors are placed close to the tip of probe, a laser beam from laser head is splited along two paths, one is arranged tangent to the base circle of gear for the measurement of profile and pitch, another is arranged parallel to the gear axis for the measurement of helix, both laser measurement performed with a resolution of 0.3nm. This approach not only improves the accuracy of length measurement but minimize the Abbe offset directly. The configuration of this improved measuring machine is illustrated in detail. The measurements are performed automatically, and all the measurement signals from guide rails, rotary table, probe and laser measuring system are obtained synchronously. Software collects all the data for further calculation and evaluation. The first measurements for a gear involute artifact and a helix artifact are carried out, the results are shown and analyzed as well.

  17. Fundamental Kinetics Database Utilizing Shock Tube Measurements (Volumes 1, 2, 3, 4, and Volume 6)

    DOE Data Explorer

    Davidson, D. F.; Hanson, R. K

    The data from shock tube experiments generally takes three forms: ignition delay times, species concentration time-histories and reaction rate measurements. Volume 1 focuses on ignition delay time data measured and published by the Shock Tube Group in the Mechanical Engineering Department of Stanford University. The cut-off date for inclusion into this volume was January 2005. Volume 2 focuses on species concentration time-histories and was cut off December 2005. The two volumes are in PDF format and are accompanied by a zipped file of supporting data. Volume 3 was issued in 2009. Volume 4, Ignition delay times measurements came out in May, 2014, along with Reaction Rates Measurements, Vol 6. Volume 5 is not available at this time.

  18. Particle Image Velocimetry Measurements in an Anatomically-Accurate Scaled Model of the Mammalian Nasal Cavity

    NASA Astrophysics Data System (ADS)

    Rumple, Christopher; Krane, Michael; Richter, Joseph; Craven, Brent

    2013-11-01

    The mammalian nose is a multi-purpose organ that houses a convoluted airway labyrinth responsible for respiratory air conditioning, filtering of environmental contaminants, and chemical sensing. Because of the complexity of the nasal cavity, the anatomy and function of these upper airways remain poorly understood in most mammals. However, recent advances in high-resolution medical imaging, computational modeling, and experimental flow measurement techniques are now permitting the study of respiratory airflow and olfactory transport phenomena in anatomically-accurate reconstructions of the nasal cavity. Here, we focus on efforts to manufacture an anatomically-accurate transparent model for stereoscopic particle image velocimetry (SPIV) measurements. Challenges in the design and manufacture of an index-matched anatomical model are addressed. PIV measurements are presented, which are used to validate concurrent computational fluid dynamics (CFD) simulations of mammalian nasal airflow. Supported by the National Science Foundation.

  19. Defining allowable physical property variations for high accurate measurements on polymer parts

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Sonne, M. R.; Madruga, D. G.; De Chiffre, L.; Hattel, J. H.

    2016-06-01

    Measurement conditions and material properties have a significant impact on the dimensions of a part, especially for polymers parts. Temperature variation causes part deformations that increase the uncertainty of the measurement process. Current industrial tolerances of a few micrometres demand high accurate measurements in non-controlled ambient. Most of polymer parts are manufactured by injection moulding and their inspection is carried out after stabilization, around 200 hours. The overall goal of this work is to reach ±5μm in uncertainty measurements a polymer products which is a challenge in today`s production and metrology environments. The residual deformations in polymer products at room temperature after injection molding are important when micrometer accuracy needs to be achieved. Numerical modelling can give a valuable insight to what is happening in the polymer during cooling down after injection molding. In order to obtain accurate simulations, accurate inputs to the model are crucial. In reality however, the material and physical properties will have some variations. Although these variations may be small, they can act as a source of uncertainty for the measurement. In this paper, we investigated how big the variation in material and physical properties are allowed in order to reach the 5 μm target on the uncertainty.

  20. AN EFFICIENT METHOD FOR ACCURATELY DETERMINING WEAR VOLUMES OF SLIDERS WITH NON-FLAT WEAR SCARS AND COMPOUND CURVATURES

    SciTech Connect

    Qu, Jun; Truhan, Jr., John J

    2006-01-01

    Point contact is often used in unidirectional pin-on-disk and reciprocating pin-on-flat sliding friction and wear tests. The slider tip could have either a spherical shape or compound curvatures (such as an ellipsoidal shape), and the worn tip usually is not flat but has unknown curvatures. Current methods for determining the wear volumes of sliders suffer from one or more limitations. For example, the gravimetric method is not able to detect small amounts of wear, and the two-dimensional wear scar size measurement is valid only for flat wear scars. More rigorous methods can be very time consuming, such as the 3D surface profiling method that involves obtaining tedious multiple surface profiles and analyzing a large set of data. In this study, a new 'single-trace' analysis is introduced to efficiently evaluate the wear volumes of non-flat worn sliders. This method requires only the measurement of the wear scar size and one trace of profiling to obtain the curvature on the wear cap. The wear volume calculation only involves closed-form algebraic equations. This single-trace method has demonstrated much higher accuracy and fewer limitations than the gravimetric method and 2D method, and has shown good agreement with the 3D method while saving significant surface profiling and data analysis time.

  1. Progress Toward Accurate Measurements of Power Consumptions of DBD Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Ashpis, David E.; Laun, Matthew C.; Griebeler, Elmer L.

    2012-01-01

    The accurate measurement of power consumption by Dielectric Barrier Discharge (DBD) plasma actuators is a challenge due to the characteristics of the actuator current signal. Micro-discharges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. We have used a high-speed digital oscilloscope to measure the actuator power consumption using the Shunt Resistor method and the Monitor Capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the Shunt Resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the Monitor Capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work.

  2. Foundations for Measuring Volume Rendering Quality

    NASA Technical Reports Server (NTRS)

    Williams, Peter L.; Uselton, Samuel P.; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    The goal of this paper is to provide a foundation for objectively comparing volume rendered images. The key elements of the foundation are: (1) a rigorous specification of all the parameters that need to be specified to define the conditions under which a volume rendered image is generated; (2) a methodology for difference classification, including a suite of functions or metrics to quantify and classify the difference between two volume rendered images that will support an analysis of the relative importance of particular differences. The results of this method can be used to study the changes caused by modifying particular parameter values, to compare and quantify changes between images of similar data sets rendered in the same way, and even to detect errors in the design, implementation or modification of a volume rendering system. If one has a benchmark image, for example one created by a high accuracy volume rendering system, the method can be used to evaluate the accuracy of a given image.

  3. Measurement of gastric meal and secretion volumes using magnetic resonance imaging

    PubMed Central

    Hoad, C.L.; Parker, H.; Hudders, N.; Costigan, C.; Cox, E.F.; Perkins, A.C.; Blackshaw, P.E.; Marciani, L.; Spiller, R.C.; Fox, M.R.; Gowland, P.A.

    2015-01-01

    MRI can assess multiple gastric functions without ionizing radiation. However, time consuming image acquisition and analysis of gastric volume data, plus confounding of gastric emptying measurements by gastric secretions mixed with the test meal have limited its use to research centres. This study presents an MRI acquisition protocol and analysis algorithm suitable for the clinical measurement of gastric volume and secretion volume. Reproducibility of gastric volume measurements was assessed using data from 10 healthy volunteers following a liquid test meal with rapid MRI acquisition within one breath-hold and semi-automated analysis. Dilution of the ingested meal with gastric secretion was estimated using a respiratory-triggered T1 mapping protocol. Accuracy of the secretion volume measurements was assessed using data from 24 healthy volunteers following a mixed (liquid/solid) test meal with MRI meal volumes compared to data acquired using gamma scintigraphy (GS) on the same subjects studied on a separate study day. The mean (SD) coefficient of variance between 3 observers for both total gastric contents (including meal, secretions and air) and just the gastric contents (meal and secretion only) was 3 (2) % at large gastric volumes (> 200 ml). Mean (SD) secretion volumes post meal ingestion were 64 (51) ml and 110 (40) ml at 15 and 75 minutes respectively. Comparison with GS meal volumes, showed that MRI meal only volume (after correction for secretion volume) were similar to GS, with a linear regression gradient (std err) of 1.06 (0.10) and intercept −11 (24) ml. In conclusion, (i) rapid acquisition removed the requirement to image during prolonged breath-hold (ii) semi-automatic analysis greatly reduced time required to derive measurements and (iii) correction for secretion volumes provides accurate assessment of gastric meal volumes and emptying. Together these features provide the scientific basis of a protocol which would be suitable in clinical practice

  4. Precise and Accurate Measurements of Strong-Field Photoionization and a Transferable Laser Intensity Calibration Standard.

    PubMed

    Wallace, W C; Ghafur, O; Khurmi, C; Sainadh U, Satya; Calvert, J E; Laban, D E; Pullen, M G; Bartschat, K; Grum-Grzhimailo, A N; Wells, D; Quiney, H M; Tong, X M; Litvinyuk, I V; Sang, R T; Kielpinski, D

    2016-07-29

    Ionization of atoms and molecules in strong laser fields is a fundamental process in many fields of research, especially in the emerging field of attosecond science. So far, demonstrably accurate data have only been acquired for atomic hydrogen (H), a species that is accessible to few investigators. Here, we present measurements of the ionization yield for argon, krypton, and xenon with percent-level accuracy, calibrated using H, in a laser regime widely used in attosecond science. We derive a transferable calibration standard for laser peak intensity, accurate to 1.3%, that is based on a simple reference curve. In addition, our measurements provide a much needed benchmark for testing models of ionization in noble-gas atoms, such as the widely employed single-active electron approximation. PMID:27517769

  5. Precise and Accurate Measurements of Strong-Field Photoionization and a Transferable Laser Intensity Calibration Standard

    NASA Astrophysics Data System (ADS)

    Wallace, W. C.; Ghafur, O.; Khurmi, C.; Sainadh U, Satya; Calvert, J. E.; Laban, D. E.; Pullen, M. G.; Bartschat, K.; Grum-Grzhimailo, A. N.; Wells, D.; Quiney, H. M.; Tong, X. M.; Litvinyuk, I. V.; Sang, R. T.; Kielpinski, D.

    2016-07-01

    Ionization of atoms and molecules in strong laser fields is a fundamental process in many fields of research, especially in the emerging field of attosecond science. So far, demonstrably accurate data have only been acquired for atomic hydrogen (H), a species that is accessible to few investigators. Here, we present measurements of the ionization yield for argon, krypton, and xenon with percent-level accuracy, calibrated using H, in a laser regime widely used in attosecond science. We derive a transferable calibration standard for laser peak intensity, accurate to 1.3%, that is based on a simple reference curve. In addition, our measurements provide a much needed benchmark for testing models of ionization in noble-gas atoms, such as the widely employed single-active electron approximation.

  6. Accurate potential drop sheet resistance measurements of laser-doped areas in semiconductors

    SciTech Connect

    Heinrich, Martin; Kluska, Sven; Binder, Sebastian; Hameiri, Ziv; Hoex, Bram; Aberle, Armin G.

    2014-10-07

    It is investigated how potential drop sheet resistance measurements of areas formed by laser-assisted doping in crystalline Si wafers are affected by typically occurring experimental factors like sample size, inhomogeneities, surface roughness, or coatings. Measurements are obtained with a collinear four point probe setup and a modified transfer length measurement setup to measure sheet resistances of laser-doped lines. Inhomogeneities in doping depth are observed from scanning electron microscope images and electron beam induced current measurements. It is observed that influences from sample size, inhomogeneities, surface roughness, and coatings can be neglected if certain preconditions are met. Guidelines are given on how to obtain accurate potential drop sheet resistance measurements on laser-doped regions.

  7. Rapid and accurate broadband absorption cross-section measurement of human bodies in a reverberation chamber

    NASA Astrophysics Data System (ADS)

    Flintoft, Ian D.; Melia, Gregory C. R.; Robinson, Martin P.; Dawson, John F.; Marvin, Andy C.

    2015-06-01

    A measurement methodology for polarization and angle of incidence averaged electromagnetic absorption cross-section using a reverberation chamber is presented. The method is optimized for simultaneous rapid and accurate determination of average absorption cross-section over the frequency range 1-15 GHz, making it suitable for use in human absorption and exposure studies. The typical measurement time of the subject is about 8 min with a corresponding statistical uncertainty of about 3% in the measured absorption cross-section. The method is validated by comparing measurements on a spherical phantom with Mie series calculations. The efficacy of the method is demonstrated with measurements of the posture dependence of the absorption cross-section of a human subject and an investigation of the effects of clothing on the measured absorption which are important considerations for the practical design of experiments for studies on human subjects.

  8. Accurate Determination of Torsion and Pure Bending Moment for Viscoelastic Measurements

    NASA Astrophysics Data System (ADS)

    Wang, Yun-Che; Ko, Chih-Chin; Shiau, Li-Ming

    Measurements of time-dependent material properties in the context of linear viscoelasticity, at a given frequency and temperature, require accurate determination of both loading and deformation that are subjected to the testing materials. A pendulum-type viscoelastic spectroscopy is developed to experimentally measure loss tangent and the magnitude of dynamic modulus of solid materials. The mechanical system of the device is based on the behavior of the cantilever beam, and torsion and pure bending moment are generated from the interaction between a permanent magnet and the Helmholtz coils. The strength of the magnetic interactions may be determined with a material with known mechanical properties, such as aluminum 6061T4 alloy. The sensitivity of the torque measurement is on the order of one micro N-m level. With the high accurate torque measurement and deformation detection from a laser-based displacement measurement system, viscoelastic properties of materials can be experimentally measured in different frequency regimes. Sinusoidal driving signals are adopted for measuring complex modulus in the sub-resonant regime, and dc bias driving for creep tests in the low frequency limit. At structural resonant frequencies, the full-width-at-half-maximum (FWHM) method or Lorentzian curve fitting method is adopted to extract material properties. The completion of determining material properties in the wide frequency spectrum may help to identify the deformation mechanisms of the material and to create better models for simulation work.

  9. A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.; Simons, Rainee N.

    2014-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

  10. Accurate phase measurements for thick spherical objects using optical quadrature microscopy

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; DiMarzio, Charles A.

    2009-02-01

    In vitro fertilization (IVF) procedures have resulted in the birth of over three million babies since 1978. Yet the live birth rate in the United States was only 34% in 2005, with 32% of the successful pregnancies resulting in multiple births. These multiple pregnancies were directly attributed to the transfer of multiple embryos to increase the probability that a single, healthy embryo was included. Current viability markers used for IVF, such as the cell number, symmetry, size, and fragmentation, are analyzed qualitatively with differential interference contrast (DIC) microscopy. However, this method is not ideal for quantitative measures beyond the 8-cell stage of development because the cells overlap and obstruct the view within and below the cluster of cells. We have developed the phase-subtraction cell-counting method that uses the combination of DIC and optical quadrature microscopy (OQM) to count the number of cells accurately in live mouse embryos beyond the 8-cell stage. We have also created a preliminary analysis to measure the cell symmetry, size, and fragmentation quantitatively by analyzing the relative dry mass from the OQM image in conjunction with the phase-subtraction count. In this paper, we will discuss the characterization of OQM with respect to measuring the phase accurately for spherical samples that are much larger than the depth of field. Once fully characterized and verified with human embryos, this methodology could provide the means for a more accurate method to score embryo viability.

  11. Monte Carlo Method with Heuristic Adjustment for Irregularly Shaped Food Product Volume Measurement

    PubMed Central

    Siswantoro, Joko; Idrus, Bahari

    2014-01-01

    Volume measurement plays an important role in the production and processing of food products. Various methods have been proposed to measure the volume of food products with irregular shapes based on 3D reconstruction. However, 3D reconstruction comes with a high-priced computational cost. Furthermore, some of the volume measurement methods based on 3D reconstruction have a low accuracy. Another method for measuring volume of objects uses Monte Carlo method. Monte Carlo method performs volume measurements using random points. Monte Carlo method only requires information regarding whether random points fall inside or outside an object and does not require a 3D reconstruction. This paper proposes volume measurement using a computer vision system for irregularly shaped food products without 3D reconstruction based on Monte Carlo method with heuristic adjustment. Five images of food product were captured using five cameras and processed to produce binary images. Monte Carlo integration with heuristic adjustment was performed to measure the volume based on the information extracted from binary images. The experimental results show that the proposed method provided high accuracy and precision compared to the water displacement method. In addition, the proposed method is more accurate and faster than the space carving method. PMID:24892069

  12. RESIDUAL LIMB VOLUME CHANGE: SYSTEMATIC REVIEW OF MEASUREMENT AND MANAGEMENT

    PubMed Central

    Sanders, JE; Fatone, S

    2014-01-01

    Management of residual limb volume affects decisions regarding timing of fit of the first prosthesis, when a new prosthetic socket is needed, design of a prosthetic socket, and prescription of accommodation strategies for daily volume fluctuations. The purpose of this systematic review was to assess what is known about measurement and management of residual limb volume change in persons with lower-limb amputation. Publications that met inclusion criteria were grouped into three categories: (I) descriptions of residual limb volume measurement techniques; (II) studies on people with lower-limb amputation investigating the effect of residual limb volume change on clinical care; and (III) studies of residual limb volume management techniques or descriptions of techniques for accommodating or controlling residual limb volume. The review showed that many techniques for the measurement of residual limb volume have been described but clinical use is limited largely because current techniques lack adequate resolution and in-socket measurement capability. Overall, there is limited evidence regarding the management of residual limb volume, and the evidence available focuses primarily on adults with trans-tibial amputation in the early post-operative phase. While we can draw some insights from the available research about residual limb volume measurement and management, further research is required. PMID:22068373

  13. In Pursuit of Highly Accurate Atomic Lifetime Measurements of Multiply Charged Ions

    SciTech Connect

    Trabert, E

    2009-06-01

    Accurate atomic lifetime data are useful for terrestrial and astrophysical plasma diagnostics. At accuracies higher than those required for these applications, lifetime measurements test atomic structure theory in ways complementary to spectroscopic energy determinations. At the highest level of accuracy, the question arises whether such tests reach the limits of modern theory, a combination of quantum mechanics and QED, adn possibly point to physics beyond the Standard Model. If high-precision atomic lifetime measurements, especially on multiply charged ions, have not quite reached this high accuracy yet, then what is necessary to attain this goal?

  14. Design of a dual port volume measuring system

    SciTech Connect

    Klevgard, P.A.

    1990-09-01

    A volume measuring system is described which uses the ideal gas law and pressure measurements to determine an unknown vessel's volume when a gas expands into that vessel from a known volume. The design, the engineering principles, the calibration, and the accuracy of this computer-controlled system are all discussed. A set of electrical and mechanical drawings of the system is included. 3 refs., 6 figs.

  15. Improved dynamic compensation for accurate cutting force measurements in milling applications

    NASA Astrophysics Data System (ADS)

    Scippa, A.; Sallese, L.; Grossi, N.; Campatelli, G.

    2015-03-01

    Accurate cutting-force measurements appear to be the key information in most of the machining related studies as they are fundamental in understanding the cutting processes, optimizing the cutting operations and evaluating the presence of instabilities that could affect the effectiveness of cutting processes. A variety of specifically designed transducers are commercially available nowadays and many different approaches in measuring cutting forces are presented in literature. The available transducers, though, express some limitations since they are conditioned by the vibration of the surrounding system and by the transducer's natural frequency. These parameters can drastically affect the measurement accuracy in some cases; hence an effective and accurate tool is required to compensate those dynamically induced errors in cutting force measurements. This work is aimed at developing and testing a compensation technique based on Kalman filter estimator. Two different approaches named "band-fitting" and "parallel elaboration" methods, have been developed to extend applications of this compensation technique, especially for milling purpose. The compensation filter has been designed upon the experimentally identified system's dynamic and its accuracy and effectiveness has been evaluated by numerical and experimental tests. Finally its specific application in cutting force measurements compensation is described.

  16. Accurate time-of-flight measurement of particle based on ECL-TTL Timer

    NASA Astrophysics Data System (ADS)

    Li, Deping; Liu, Jianguo; Huang, Shuhua; Gui, Huaqiao; Cheng, Yin; Wang, Jie; Lu, Yihuai

    2014-11-01

    Because of its aerodynamic diameter of the aerosol particles are stranded in different parts of different human respiratory system, thus affecting human health. Therefore, how to continue to effectively monitor the aerosol particles become increasingly concerned about. Use flight time of aerosol particle beam spectroscopy of atmospheric aerosol particle size distribution is the typical method for monitoring atmospheric aerosol particle size and particle concentration measurement , and it is the key point to accurate measurement of aerosol particle size spectra that measurement of aerosol particle flight time. In order to achieve accurate measurements of aerosol particles in time-of-flight, this paper design an ECL-TTL high-speed timer with ECL counter and TTL counter. The high-speed timer includes a clock generation, high-speed timer and the control module. Clock Generation Module using a crystal plus multiplier design ideas, take advantage of the stability of the crystal to provide a stable 500MHz clock signal is high counter. High count module design using ECL and TTL counter mix design, timing accuracy while effectively maintaining , expanding the timing range, and simplifies circuit design . High-speed counter control module controls high-speed counter start, stop and reset timely based on aerosol particles time-of-flight, is a key part of the high-speed counting. The high-speed counting resolution of 4ns, the full scale of 4096ns, has been successfully applied Aerodynamic Particle Sizer, to meet the precise measurement of aerosol particles time-of-flight.

  17. No Galaxy Left Behind: Accurate Measurements with the Faintest Objects in the Dark Energy Survey

    SciTech Connect

    Suchyta, E.

    2015-07-29

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases. We also demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the standard LandySzalay correlation function estimator suppresses the effects of variable survey selection by at least two orders of magnitude. Now our measured angular clustering is found to be in excellent agreement with that of a matched sample drawn from much deeper, higherresolution space-based COSMOS imaging; over angular scales of 0.004° < θ < 0.2 ° , we find a best-fit scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending the statistical reach of measurements in a wide variety of coming imaging surveys.

  18. No Galaxy Left Behind: Accurate Measurements with the Faintest Objects in the Dark Energy Survey

    DOE PAGESBeta

    Suchyta, E.

    2016-01-27

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases.more » We also demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the standard LandySzalay correlation function estimator suppresses the effects of variable survey selection by at least two orders of magnitude. Now our measured angular clustering is found to be in excellent agreement with that of a matched sample drawn from much deeper, higherresolution space-based COSMOS imaging; over angular scales of 0.004° < θ < 0.2 ° , we find a best-fit scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending the statistical reach of measurements in a wide variety of coming imaging surveys.« less

  19. No galaxy left behind: accurate measurements with the faintest objects in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Suchyta, E.; Huff, E. M.; Aleksić, J.; Melchior, P.; Jouvel, S.; MacCrann, N.; Ross, A. J.; Crocce, M.; Gaztanaga, E.; Honscheid, K.; Leistedt, B.; Peiris, H. V.; Rykoff, E. S.; Sheldon, E.; Abbott, T.; Abdalla, F. B.; Allam, S.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; James, D. J.; Jarvis, M.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nichol, R. C.; Nord, B.; Ogando, R.; Percival, W. J.; Reil, K.; Roodman, A.; Sako, M.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, D.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Zhang, Y.; DES Collaboration

    2016-03-01

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of detectable stars or galaxies. We have implemented our proposal in BALROG, software which embeds fake objects in real imaging to accurately characterize measurement biases. We demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the Landy-Szalay estimator suppresses the effects of variable survey selection by at least two orders of magnitude. With this correction, our measured angular clustering is found to be in excellent agreement with that of a matched sample from much deeper, higher resolution space-based Cosmological Evolution Survey (COSMOS) imaging; over angular scales of 0.004° < θ < 0.2°, we find a best-fitting scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending measurements' statistical reach in a variety of upcoming imaging surveys.

  20. Three-dimensional digital holographic aperture synthesis for rapid and highly-accurate large-volume metrology

    NASA Astrophysics Data System (ADS)

    Crouch, Stephen; Kaylor, Brant M.; Barber, Zeb W.; Reibel, Randy R.

    2015-09-01

    Currently large volume, high accuracy three-dimensional (3D) metrology is dominated by laser trackers, which typically utilize a laser scanner and cooperative reflector to estimate points on a given surface. The dependency upon the placement of cooperative targets dramatically inhibits the speed at which metrology can be conducted. To increase speed, laser scanners or structured illumination systems can be used directly on the surface of interest. Both approaches are restricted in their axial and lateral resolution at longer stand-off distances due to the diffraction limit of the optics used. Holographic aperture ladar (HAL) and synthetic aperture ladar (SAL) can enhance the lateral resolution of an imaging system by synthesizing much larger apertures by digitally combining measurements from multiple smaller apertures. Both of these approaches only produce two-dimensional imagery and are therefore not suitable for large volume 3D metrology. We combined the SAL and HAL approaches to create a swept frequency digital holographic 3D imaging system that provides rapid measurement speed for surface coverage with unprecedented axial and lateral resolution at longer standoff ranges. The technique yields a "data cube" of Fourier domain data, which can be processed with a 3D Fourier transform to reveal a 3D estimate of the surface. In this paper, we provide the theoretical background for the technique and show experimental results based on an ultra-wideband frequency modulated continuous wave (FMCW) chirped heterodyne ranging system showing ~100 micron lateral and axial precisions at >2 m standoff distances.

  1. A Highly Accurate Stress Measurement System for Producing Precise X-Ray Masks

    NASA Astrophysics Data System (ADS)

    Oda, Masatoshi; Une, Atsunobu; Okada, Ikuo; Shinohara, Shinji; Nakayama, Yasuo; Yoshihara, Hideo

    1995-12-01

    A new system that measures stress in film deposited on Si wafers has been developed to produce highly accurate X-ray masks. The system consists of very rigid air sliders, an electrostatic sensor, and a soft-handling wafer chuck. With the system, wafer warp is precisely measured before and after film deposition, and the stress distribution is calculated from those measurements. Wafer warps can be measured with a repeatability of a few nanometers by this system. The stress distribution of absorber film on 2-mm-thick Si wafers can be determined with an accuracy of ±5 MPa. The stress distribution agrees well with the pattern position shifts in the membrane.

  2. No galaxy left behind. Accurate measurements with the faintest objects in the Dark Energy Survey

    DOE PAGESBeta

    Suchyta, E.; Huff, E. M.; Aleksić, J.; Melchior, P.; Jouvel, S.; MacCrann, N.; Ross, A. J.; Crocce, M.; Gaztanaga, E.; Honscheid, K.; et al

    2016-01-27

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. Here, we introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of detectable stars or galaxies. Moreover, our proposal was implemented in BALROG, software which embeds fake objects in real imaging to accurately characterize measurement biases. We demonstrate this technique with an angular clusteringmore » measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the Landy–Szalay estimator suppresses the effects of variable survey selection by at least two orders of magnitude. With this correction, our measured angular clustering is found to be in excellent agreement with that of a matched sample from much deeper, higher resolution space-based Cosmological Evolution Survey (COSMOS) imaging; over angular scales of 0.°004 < θ < 0.°2, we find a best-fitting scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending measurements’ statistical reach in a variety of upcoming imaging surveys.« less

  3. Particle Image Velocimetry Measurements in Anatomically-Accurate Models of the Mammalian Nasal Cavity

    NASA Astrophysics Data System (ADS)

    Rumple, C.; Richter, J.; Craven, B. A.; Krane, M.

    2012-11-01

    A summary of the research being carried out by our multidisciplinary team to better understand the form and function of the nose in different mammalian species that include humans, carnivores, ungulates, rodents, and marine animals will be presented. The mammalian nose houses a convoluted airway labyrinth, where two hallmark features of mammals occur, endothermy and olfaction. Because of the complexity of the nasal cavity, the anatomy and function of these upper airways remain poorly understood in most mammals. However, recent advances in high-resolution medical imaging, computational modeling, and experimental flow measurement techniques are now permitting the study of airflow and respiratory and olfactory transport phenomena in anatomically-accurate reconstructions of the nasal cavity. Here, we focus on efforts to manufacture transparent, anatomically-accurate models for stereo particle image velocimetry (SPIV) measurements of nasal airflow. Challenges in the design and manufacture of index-matched anatomical models are addressed and preliminary SPIV measurements are presented. Such measurements will constitute a validation database for concurrent computational fluid dynamics (CFD) simulations of mammalian respiration and olfaction. Supported by the National Science Foundation.

  4. Optical coherence tomography enables accurate measurement of equine cartilage thickness for determination of speed of sound.

    PubMed

    Puhakka, Pia H; Te Moller, Nikae C R; Tanska, Petri; Saarakkala, Simo; Tiitu, Virpi; Korhonen, Rami K; Brommer, Harold; Virén, Tuomas; Jurvelin, Jukka S; Töyräs, Juha

    2016-08-01

    Background and purpose - Arthroscopic estimation of articular cartilage thickness is important for scoring of lesion severity, and measurement of cartilage speed of sound (SOS)-a sensitive index of changes in cartilage composition. We investigated the accuracy of optical coherence tomography (OCT) in measurements of cartilage thickness and determined SOS by combining OCT thickness and ultrasound (US) time-of-flight (TOF) measurements. Material and methods - Cartilage thickness measurements from OCT and microscopy images of 94 equine osteochondral samples were compared. Then, SOS in cartilage was determined using simultaneous OCT thickness and US TOF measurements. SOS was then compared with the compositional, structural, and mechanical properties of cartilage. Results - Measurements of non-calcified cartilage thickness using OCT and microscopy were significantly correlated (ρ = 0.92; p < 0.001). With calcified cartilage included, the correlation was ρ = 0.85 (p < 0.001). The mean cartilage SOS (1,636 m/s) was in agreement with the literature. However, SOS and the other properties of cartilage lacked any statistically significant correlation. Interpretation - OCT can give an accurate measurement of articular cartilage thickness. Although SOS measurements lacked accuracy in thin equine cartilage, the concept of SOS measurement using OCT appears promising. PMID:27164159

  5. The road towards accurate optical width measurements at the industrial level

    NASA Astrophysics Data System (ADS)

    Bodermann, Bernd; Köning, Rainer; Bergmann, Detlef; Buhr, Egbert; Hässler-Grohne, Wolfgang; Flügge, Jens; Bosse, Harald

    2013-04-01

    Optical vision systems require both unidirectional and bidirectional measurements for the calibrations and the verification of the tool performance to enable accurate measurements traceable to the SI unit Metre. However, for bidirectional measurements up to now the national metrology institutes are unable to provide internationally recognized calibrations of suitable standards. Furthermore often users are not aware of the specific difficulties of these measurements. In this paper the current status and limitations of bidirectional optical measurements at the industrial level are summarised and compared to state-of-the-art optical linewidth measurements performed at PTB on measurement objects of semiconductor industry. It turns out, that for optical widths measurements at an uncertainty level below 1 μm edge localisation schemes are required, which are based on tool and sample dependent threshold values, which usually need to be determined by a rigorous simulation of the microscopic image. Furthermore the calibration samples and structures must have a sufficient quality, e. g. high edge angle and low edge roughness and the structure materials and their material parameters have to be known. The experience obtained within the accreditation process of industrial labs for width calibrations shows that, in order to be able to achieve a desired measurement uncertainties of about 100 nm, the imaging system needs to have a monochromatic Koehler illumination, numerical aperture larger than 0.5, a magnification greater than 50x and the ability to control the deviation of the focus position to better than 100 nm.

  6. Accurate measurements of the collision stopping powers for 5 to 30 MeV electrons

    NASA Astrophysics Data System (ADS)

    MacPherson, Miller Shawn

    Accurate knowledge of electron stopping powers is crucial for accurate radiation dosimetry and radiation transport calculations. Current values for stopping powers are based on a theoretical model, with estimated uncertainties of 0.5-1% (1σ) for electron energies greater than 100 keV. This work presents the first measurements of electron collision stopping powers capable of testing the theoretical values within these stated uncertainties. A large NaI spectrometer was used to measure the change in electron energy when an absorbing disk of known thickness was placed in an electron beam. Monte Carlo simulations of the experiment were performed to account for the effects of surrounding materials. Energy differences between the calculated and measured spectra were used to determine corrections to the soft collision component of the theoretical stopping powers employed by the Monte Carlo simulations. Four different elemental materials were studied: Be, Al, Cu, and Ta. This provided a wide range of atomic numbers and densities over which to test the theory. In addition, stopping powers were measured for graphite (both standard and pyrolytic), A-150 tissue equivalent plastic, C-552 air equivalent plastic, and water. The incident electron energies ranged from 5 to 30 MeV. Generally, the measured stopping powers agree with the theoretical values within the experimental uncertainties, which range from 0.4% to 0.7% (1σ). Aluminum, however, exhibits a 0.7% discrepancy at higher electron energies. Furthermore, these measurements have established that the grain density stopping power is appropriate for graphite, contrary to the recommendations of ICRU Report 37. This removes a 0.2% uncertainty in air kerma calibrations, and impacts on dosimetric quantities determined via graphite calorimetry, such as ɛG for Fricke dosimetry and (W/ e)air for ion chamber measurements.

  7. A conservative finite volume scheme with time-accurate local time stepping for scalar transport on unstructured grids

    NASA Astrophysics Data System (ADS)

    Cavalcanti, José Rafael; Dumbser, Michael; Motta-Marques, David da; Fragoso Junior, Carlos Ruberto

    2015-12-01

    In this article we propose a new conservative high resolution TVD (total variation diminishing) finite volume scheme with time-accurate local time stepping (LTS) on unstructured grids for the solution of scalar transport problems, which are typical in the context of water quality simulations. To keep the presentation of the new method as simple as possible, the algorithm is only derived in two space dimensions and for purely convective transport problems, hence neglecting diffusion and reaction terms. The new numerical method for the solution of the scalar transport is directly coupled to the hydrodynamic model of Casulli and Walters (2000) that provides the dynamics of the free surface and the velocity vector field based on a semi-implicit discretization of the shallow water equations. Wetting and drying is handled rigorously by the nonlinear algorithm proposed by Casulli (2009). The new time-accurate LTS algorithm allows a different time step size for each element of the unstructured grid, based on an element-local Courant-Friedrichs-Lewy (CFL) stability condition. The proposed method does not need any synchronization between different time steps of different elements and is by construction locally and globally conservative. The LTS scheme is based on a piecewise linear polynomial reconstruction in space-time using the MUSCL-Hancock method, to obtain second order of accuracy in both space and time. The new algorithm is first validated on some classical test cases for pure advection problems, for which exact solutions are known. In all cases we obtain a very good level of accuracy, showing also numerical convergence results; we furthermore confirm mass conservation up to machine precision and observe an improved computational efficiency compared to a standard second order TVD scheme for scalar transport with global time stepping (GTS). Then, the new LTS method is applied to some more complex problems, where the new scalar transport scheme has also been coupled to

  8. Highly accurate isotope measurements of surface material on planetary objects in situ

    NASA Astrophysics Data System (ADS)

    Riedo, Andreas; Neuland, Maike; Meyer, Stefan; Tulej, Marek; Wurz, Peter

    2013-04-01

    Studies of isotope variations in solar system objects are of particular interest and importance. Highly accurate isotope measurements provide insight into geochemical processes, constrain the time of formation of planetary material (crystallization ages) and can be robust tracers of pre-solar events and processes. A detailed understanding of the chronology of the early solar system and dating of planetary materials require precise and accurate measurements of isotope ratios, e.g. lead, and abundance of trace element. However, such measurements are extremely challenging and until now, they never have been attempted in space research. Our group designed a highly miniaturized and self-optimizing laser ablation time-of-flight mass spectrometer for space flight for sensitive and accurate measurements of the elemental and isotopic composition of extraterrestrial materials in situ. Current studies were performed by using UV radiation for ablation and ionization of sample material. High spatial resolution is achieved by focusing the laser beam to about Ø 20μm onto the sample surface. The instrument supports a dynamic range of at least 8 orders of magnitude and a mass resolution m/Δm of up to 800—900, measured at iron peak. We developed a measurement procedure, which will be discussed in detail, that allows for the first time to measure with the instrument the isotope distribution of elements, e.g. Ti, Pb, etc., with a measurement accuracy and precision in the per mill and sub per mill level, which is comparable to well-known and accepted measurement techniques, such as TIMS, SIMS and LA-ICP-MS. The present instrument performance offers together with the measurement procedure in situ measurements of 207Pb/206Pb ages with the accuracy for age in the range of tens of millions of years. Furthermore, and in contrast to other space instrumentation, our instrument can measure all elements present in the sample above 10 ppb concentration, which offers versatile applications

  9. Evaluation of an Automatic Registration-Based Algorithm for Direct Measurement of Volume Change in Tumors

    SciTech Connect

    Sarkar, Saradwata; Johnson, Timothy D.; Ma, Bing; Chenevert, Thomas L.; Bland, Peyton H.; Park, Hyunjin; Schott, Anne F.; Ross, Brian D.; Meyer, Charles R.

    2012-07-01

    Purpose: Assuming that early tumor volume change is a biomarker for response to therapy, accurate quantification of early volume changes could aid in adapting an individual patient's therapy and lead to shorter clinical trials. We investigated an image registration-based approach for tumor volume change quantification that may more reliably detect smaller changes that occur in shorter intervals than can be detected by existing algorithms. Methods and Materials: Variance and bias of the registration-based approach were evaluated using retrospective, in vivo, very-short-interval diffusion magnetic resonance imaging scans where true zero tumor volume change is unequivocally known and synthetic data, respectively. The interval scans were nonlinearly registered using two similarity measures: mutual information (MI) and normalized cross-correlation (NCC). Results: The 95% confidence interval of the percentage volume change error was (-8.93% to 10.49%) for MI-based and (-7.69%, 8.83%) for NCC-based registrations. Linear mixed-effects models demonstrated that error in measuring volume change increased with increase in tumor volume and decreased with the increase in the tumor's normalized mutual information, even when NCC was the similarity measure being optimized during registration. The 95% confidence interval of the relative volume change error for the synthetic examinations with known changes over {+-}80% of reference tumor volume was (-3.02% to 3.86%). Statistically significant bias was not demonstrated. Conclusion: A low-noise, low-bias tumor volume change measurement algorithm using nonlinear registration is described. Errors in change measurement were a function of tumor volume and the normalized mutual information content of the tumor.

  10. Measurement of bone cyst fluid volume using k-means clustering.

    PubMed

    Docquier, Pierre-Louis; Paul, Laurent; Menten, Renaud; Cartiaux, Olivier; Francq, Bernard; Banse, Xavier

    2009-12-01

    We designed a semiautomatic segmentation method to easily measure the volume of a bone cyst (simple or aneurysmal) from magnetic resonance imaging (MRI). This method only considers the fluid part of the cyst, even when there are several fluid intensities (fluid-fluid levels) or the cyst is multi-loculated. The nonhomogeneity phenomenon inherent in MRI was handled by a k-means clustering algorithm that classified all of the voxels corresponding to the cyst fluid as the same voxel intensity. Level-set segmentation was expanded into the whole cyst volume and the resulting segmented volume provided the measured cyst volume. The semiautomatic method was compared with the usual manual method (manual contour tracing) in terms of its ability to measure a known volume of water (gold standard) as well as the volume of 29 bone cysts. Both methods were equivalent with regards to the gold standard, but the semiautomatic method was more accurate. In terms of the experimental measurements, the semiautomatic method was more repeatable and reproducible, and less time-consuming and fastidious than the manual method. Our semiautomatic method uses only freeware and can be used routinely whenever measurement of a bone cyst volume is needed. PMID:19553051

  11. Accurate Measurements of Aerosol Hygroscopic Growth over a Wide Range in Relative Humidity.

    PubMed

    Rovelli, Grazia; Miles, Rachael E H; Reid, Jonathan P; Clegg, Simon L

    2016-06-30

    Using a comparative evaporation kinetics approach, we describe a new and accurate method for determining the equilibrium hygroscopic growth of aerosol droplets. The time-evolving size of an aqueous droplet, as it evaporates to a steady size and composition that is in equilibrium with the gas phase relative humidity, is used to determine the time-dependent mass flux of water, yielding information on the vapor pressure of water above the droplet surface at every instant in time. Accurate characterization of the gas phase relative humidity is provided from a control measurement of the evaporation profile of a droplet of know equilibrium properties, either a pure water droplet or a sodium chloride droplet. In combination, and by comparison with simulations that account for both the heat and mass transport governing the droplet evaporation kinetics, these measurements allow accurate retrieval of the equilibrium properties of the solution droplet (i.e., the variations with water activity in the mass fraction of solute, diameter growth factor, osmotic coefficient or number of water molecules per solute molecule). Hygroscopicity measurements can be made over a wide range in water activity (from >0.99 to, in principle, <0.05) on time scales of <10 s for droplets containing involatile or volatile solutes. The approach is benchmarked for binary and ternary inorganic solution aerosols with typical uncertainties in water activity of <±0.2% at water activities >0.9 and ∼±1% below 80% RH, and maximum uncertainties in diameter growth factor of ±0.7%. For all of the inorganic systems examined, the time-dependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1). PMID:27285052

  12. Accurate measurement of residual stress in glass rod by photoelastic experiment

    SciTech Connect

    Baek, Tae Hyun; Lee, Jae Choon; Kim, Dong Hyun

    1996-12-31

    Photoelastic law is used to measure residual stresses in glass rods which have been heat-treated at different temperatures ranging from 560{degrees}C to 665 {degrees}C. This research is performed to analyze the variation of residual stresses with respect to heat-treatment temperatures of glass rods. In order to measure the stresses accurately, both fringe sharpening and fringe multiplication techniques are applied to the determination of photoelastic fringe orders. The experimental results show that all the hoop stress components are changed from tensile stresses to compressive ones at approximate R/R{sub o}=0.6, where R is any measured radius and R{sub o} outer radius. For the borosilicate glass rods which are used in this experiment, residual stresses increase as heat-treatment temperatures are raised from 560{degrees}C to 665{degrees}C. These experimental results are compared with ones calculated by Instant Freezing Numerical Model.

  13. Three-dimensional shape measurement with a fast and accurate approach

    SciTech Connect

    Wang Zhaoyang; Du Hua; Park, Seungbae; Xie Huimin

    2009-02-20

    A noncontact, fast, accurate, low-cost, broad-range, full-field, easy-to-implement three-dimensional (3D) shape measurement technique is presented. The technique is based on a generalized fringe projection profilometry setup that allows each system component to be arbitrarily positioned. It employs random phase-shifting, multifrequency projection fringes, ultrafast direct phase unwrapping, and inverse self-calibration schemes to perform 3D shape determination with enhanced accuracy in a fast manner. The relative measurement accuracy can reach 1/10,000 or higher, and the acquisition speed is faster than two 3D views per second. The validity and practicability of the proposed technique have been verified by experiments. Because of its superior capability, the proposed 3D shape measurement technique is suitable for numerous applications in a variety of fields.

  14. Accurate Young's modulus measurement based on Rayleigh wave velocity and empirical Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Li, Mingxia; Feng, Zhihua

    2016-07-01

    This paper presents a method for Young's modulus measurement based on Rayleigh wave speed. The error in Poisson's ratio has weak influence on the measurement of Young's modulus based on Rayleigh wave speed, and Poisson's ratio minimally varies in a certain material; thus, we can accurately estimate Young's modulus with surface wave speed and a rough Poisson's ratio. We numerically analysed three methods using Rayleigh, longitudinal, and transversal wave speed, respectively, and the error in Poisson's ratio shows the least influence on the result in the method involving Rayleigh wave speed. An experiment was performed and has proved the feasibility of this method. Device for speed measuring could be small, and no sample pretreatment is needed. Hence, developing a portable instrument based on this method is possible. This method makes a good compromise between usability and precision.

  15. A Flexible Fringe Projection Vision System with Extended Mathematical Model for Accurate Three-Dimensional Measurement

    PubMed Central

    Xiao, Suzhi; Tao, Wei; Zhao, Hui

    2016-01-01

    In order to acquire an accurate three-dimensional (3D) measurement, the traditional fringe projection technique applies complex and laborious procedures to compensate for the errors that exist in the vision system. However, the error sources in the vision system are very complex, such as lens distortion, lens defocus, and fringe pattern nonsinusoidality. Some errors cannot even be explained or rendered with clear expressions and are difficult to compensate directly as a result. In this paper, an approach is proposed that avoids the complex and laborious compensation procedure for error sources but still promises accurate 3D measurement. It is realized by the mathematical model extension technique. The parameters of the extended mathematical model for the ’phase to 3D coordinates transformation’ are derived using the least-squares parameter estimation algorithm. In addition, a phase-coding method based on a frequency analysis is proposed for the absolute phase map retrieval to spatially isolated objects. The results demonstrate the validity and the accuracy of the proposed flexible fringe projection vision system on spatially continuous and discontinuous objects for 3D measurement. PMID:27136553

  16. Fiddler crabs accurately measure two-dimensional distance over three-dimensional terrain.

    PubMed

    Walls, Michael L; Layne, John E

    2009-10-01

    Foraging fiddler crabs (Uca spp.) monitor the location of, and are able to return to, their burrows by employing path integration. This requires them to accurately measure both the directions and distances of their locomotory movements. Even though most fiddler crabs inhabit relatively flat terrain, they must cope with vertical features of their environment, such as sloping beaches, mounds and shells, which may represent significant obstacles. To determine whether fiddler crabs can successfully perform path integration among such three-dimensional obstacles, we tested their ability to measure distance while we imposed a vertical detour. By inserting a large hill in the homeward path of foraging crabs we show that fiddler crabs can cope with vertical detours: they accurately travel the correct horizontal distance, despite the fact that the shape of the hill forces them to change their gait from what would be used on flat ground. Our results demonstrate a flexible path integrator capable of measuring, and either integrating or discarding, the vertical dimension. PMID:19801428

  17. Designer cantilevers for even more accurate quantitative measurements of biological systems with multifrequency AFM

    NASA Astrophysics Data System (ADS)

    Contera, S.

    2016-04-01

    Multifrequency excitation/monitoring of cantilevers has made it possible both to achieve fast, relatively simple, nanometre-resolution quantitative mapping of mechanical of biological systems in solution using atomic force microscopy (AFM), and single molecule resolution detection by nanomechanical biosensors. A recent paper by Penedo et al [2015 Nanotechnology 26 485706] has made a significant contribution by developing simple methods to improve the signal to noise ratio in liquid environments, by selectively enhancing cantilever modes, which will lead to even more accurate quantitative measurements.

  18. Accurate lifetime measurements for the noble gases by the electron beam alignment technique

    NASA Astrophysics Data System (ADS)

    Gorny, M. B.; Kazantsev, S. A.; Matisov, B. G.; Polezhaevs, N. T.

    1985-03-01

    Accurate lifetime measurement for the 41 P 1, 41 D 2, 51 D 2 helium and the atomic 2 p and 3 p states of other noble gases was performed by the low energy electron beam alignment technique. An account of the influence of magnetic field on the electron path was made to obtain the real Hanle signal shape. The influence of the radiation trapping in the collision chamber was analysed with regard to the metastables diffusion. The experimental data were compared with the results of other methods of the lifetime determination.

  19. Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers

    PubMed Central

    Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J.; Brewster, Aaron S.; Alonso-Mori, Roberto; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; White, William E.; Schafer, Donald W.; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Glatzel, Pieter; Zwart, Petrus H.; Grosse-Kunstleve, Ralf W.; Bogan, Michael J.; Messerschmidt, Marc; Williams, Garth J.; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K.; Adams, Paul D.; Sauter, Nicholas K.

    2014-01-01

    X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and free from radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract statistically significant high-resolution signals from fewer diffraction measurements. PMID:24633409

  20. Accurate measurements of the dielectric constant of seawater at L band

    NASA Astrophysics Data System (ADS)

    Lang, Roger; Zhou, Yiwen; Utku, Cuneyt; Le Vine, David

    2016-01-01

    This paper describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz, the center of the protected band (i.e., passive use only) used in the measurement of sea surface salinity from space. The objective of the measurements is to accurately determine the complex dielectric constant of seawater as a function of salinity and temperature. A resonant cylindrical microwave cavity in transmission mode has been employed to make the measurements. The measurements are made using standard seawater at salinities of 30, 33, 35, and 38 practical salinity units over a range of temperatures from 0°C to 35°C in 5°C intervals. Repeated measurements have been made at each temperature and salinity. Mean values and standard deviations are then computed. The total error budget indicates that the real and imaginary parts of the dielectric constant have a combined standard uncertainty of about 0.3 over the range of salinities and temperatures considered. The measurements are compared with the dielectric constants obtained from the model functions of Klein and Swift and those of Meissner and Wentz. The biggest differences occur at low and high temperatures.

  1. Accurate Measurements of the Dielectric Constant of Seawater at L Band

    NASA Technical Reports Server (NTRS)

    Lang, Roger; Zhou, Yiwen; Utku, Cuneyt; Le Vine, David

    2016-01-01

    This paper describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz, the center of the protected band (i.e., passive use only) used in the measurement of sea surface salinity from space. The objective of the measurements is to accurately determine the complex dielectric constant of seawater as a function of salinity and temperature. A resonant cylindrical microwave cavity in transmission mode has been employed to make the measurements. The measurements are made using standard seawater at salinities of 30, 33, 35, and 38 practical salinity units over a range of temperatures from 0 degree C to 35 degree C in 5 degree C intervals. Repeated measurements have been made at each temperature and salinity. Mean values and standard deviations are then computed. The total error budget indicates that the real and imaginary parts of the dielectric constant have a combined standard uncertainty of about 0.3 over the range of salinities and temperatures considered. The measurements are compared with the dielectric constants obtained from the model functions of Klein and Swift and those of Meissner and Wentz. The biggest differences occur at low and high temperatures.

  2. Ocean Lidar Measurements of Beam Attenuation and a Roadmap to Accurate Phytoplankton Biomass Estimates

    NASA Astrophysics Data System (ADS)

    Hu, Yongxiang; Behrenfeld, Mike; Hostetler, Chris; Pelon, Jacques; Trepte, Charles; Hair, John; Slade, Wayne; Cetinic, Ivona; Vaughan, Mark; Lu, Xiaomei; Zhai, Pengwang; Weimer, Carl; Winker, David; Verhappen, Carolus C.; Butler, Carolyn; Liu, Zhaoyan; Hunt, Bill; Omar, Ali; Rodier, Sharon; Lifermann, Anne; Josset, Damien; Hou, Weilin; MacDonnell, David; Rhew, Ray

    2016-06-01

    Beam attenuation coefficient, c, provides an important optical index of plankton standing stocks, such as phytoplankton biomass and total particulate carbon concentration. Unfortunately, c has proven difficult to quantify through remote sensing. Here, we introduce an innovative approach for estimating c using lidar depolarization measurements and diffuse attenuation coefficients from ocean color products or lidar measurements of Brillouin scattering. The new approach is based on a theoretical formula established from Monte Carlo simulations that links the depolarization ratio of sea water to the ratio of diffuse attenuation Kd and beam attenuation C (i.e., a multiple scattering factor). On July 17, 2014, the CALIPSO satellite was tilted 30° off-nadir for one nighttime orbit in order to minimize ocean surface backscatter and demonstrate the lidar ocean subsurface measurement concept from space. Depolarization ratios of ocean subsurface backscatter are measured accurately. Beam attenuation coefficients computed from the depolarization ratio measurements compare well with empirical estimates from ocean color measurements. We further verify the beam attenuation coefficient retrievals using aircraft-based high spectral resolution lidar (HSRL) data that are collocated with in-water optical measurements.

  3. Advances in Multicollector ICPMS for precise and accurate isotope ratio measurements of Uranium isotopes

    NASA Astrophysics Data System (ADS)

    Bouman, C.; Lloyd, N. S.; Schwieters, J.

    2011-12-01

    The accurate and precise determination of uranium isotopes is challenging, because of the large dynamic range posed by the U isotope abundances and the limited available sample material. Various mass spectrometric techniques are used for the measurement of U isotopes, where TIMS is the most accepted and accurate one. Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) can offer higher productivity compared to TIMS, but is traditionally limited by low efficiency of sample utilisation. This contribution will discuss progress in MC-ICPMS for detecting 234U, 235U, 236U and 238U in various uranium reference materials from IRMM and NBL. The Thermo Scientific NEPTUNE Plus with Jet Interface offers a modified dry plasma ICP interface using a large interface pump combined with a special set of sample and skimmer cones giving ultimate sensitivity for all elements across the mass range. For uranium, an ion yield of > 3 % was reported previously [1]. The NEPTUNE Plus also offers Multi Ion Counting using discrete dynode electron multipliers as well as two high abundance-sensitivity filters to discriminate against peak tailing effects on 234U and 236U originating from the major uranium beams. These improvements in sensitivity and dynamic range allow accurate measurements of 234U, 235U and 236U abundances on very small samples and at low concentration. In our approach, minor U isotopes 234U and 236U were detected on ion counters with high abundance sensitivity filters, whereas 235U and 238U were detected on Faraday Cups using a high gain current amplifier (10e12 Ohm) for 235U. Precisions and accuracies for 234U and 236U were down to ~1%. For 235U, subpermil levels were reached.

  4. Measurement of absolute regional lung air volumes from near-field x-ray speckles.

    PubMed

    Leong, Andrew F T; Paganin, David M; Hooper, Stuart B; Siew, Melissa L; Kitchen, Marcus J

    2013-11-18

    Propagation-based phase contrast x-ray (PBX) imaging yields high contrast images of the lung where airways that overlap in projection coherently scatter the x-rays, giving rise to a speckled intensity due to interference effects. Our previous works have shown that total and regional changes in lung air volumes can be accurately measured from two-dimensional (2D) absorption or phase contrast images when the subject is immersed in a water-filled container. In this paper we demonstrate how the phase contrast speckle patterns can be used to directly measure absolute regional lung air volumes from 2D PBX images without the need for a water-filled container. We justify this technique analytically and via simulation using the transport-of-intensity equation and calibrate the technique using our existing methods for measuring lung air volume. Finally, we show the full capabilities of this technique for measuring regional differences in lung aeration. PMID:24514306

  5. Accurate Measurement of the in vivo Ammonium Concentration in Saccharomyces cerevisiae.

    PubMed

    Cueto-Rojas, Hugo F; Maleki Seifar, Reza; Ten Pierick, Angela; Heijnen, Sef J; Wahl, Aljoscha

    2016-01-01

    Ammonium (NH₄⁺) is the most common N-source for yeast fermentations, and N-limitation is frequently applied to reduce growth and increase product yields. While there is significant molecular knowledge on NH₄⁺ transport and assimilation, there have been few attempts to measure the in vivo concentration of this metabolite. In this article, we present a sensitive and accurate analytical method to quantify the in vivo intracellular ammonium concentration in Saccharomyces cerevisiae based on standard rapid sampling and metabolomics techniques. The method validation experiments required the development of a proper sample processing protocol to minimize ammonium production/consumption during biomass extraction by assessing the impact of amino acid degradation-an element that is often overlooked. The resulting cold chloroform metabolite extraction method, together with quantification using ultra high performance liquid chromatography-isotope dilution mass spectrometry (UHPLC-IDMS), was not only more sensitive than most of the existing methods but also more accurate than methods that use electrodes, enzymatic reactions, or boiling water or boiling ethanol biomass extraction because it minimized ammonium consumption/production during sampling processing and interference from other metabolites in the quantification of intracellular ammonium. Finally, our validation experiments showed that other metabolites such as pyruvate or 2-oxoglutarate (αKG) need to be extracted with cold chloroform to avoid measurements being biased by the degradation of other metabolites (e.g., amino acids). PMID:27120628

  6. Accurate Measurement of the in vivo Ammonium Concentration in Saccharomyces cerevisiae

    PubMed Central

    Cueto-Rojas, Hugo F.; Maleki Seifar, Reza; ten Pierick, Angela; Heijnen, Sef J.; Wahl, Aljoscha

    2016-01-01

    Ammonium (NH4+) is the most common N-source for yeast fermentations, and N-limitation is frequently applied to reduce growth and increase product yields. While there is significant molecular knowledge on NH4+ transport and assimilation, there have been few attempts to measure the in vivo concentration of this metabolite. In this article, we present a sensitive and accurate analytical method to quantify the in vivo intracellular ammonium concentration in Saccharomyces cerevisiae based on standard rapid sampling and metabolomics techniques. The method validation experiments required the development of a proper sample processing protocol to minimize ammonium production/consumption during biomass extraction by assessing the impact of amino acid degradation—an element that is often overlooked. The resulting cold chloroform metabolite extraction method, together with quantification using ultra high performance liquid chromatography-isotope dilution mass spectrometry (UHPLC-IDMS), was not only more sensitive than most of the existing methods but also more accurate than methods that use electrodes, enzymatic reactions, or boiling water or boiling ethanol biomass extraction because it minimized ammonium consumption/production during sampling processing and interference from other metabolites in the quantification of intracellular ammonium. Finally, our validation experiments showed that other metabolites such as pyruvate or 2-oxoglutarate (αKG) need to be extracted with cold chloroform to avoid measurements being biased by the degradation of other metabolites (e.g., amino acids). PMID:27120628

  7. Gloxy: an oxygen-sensitive coal for accurate measurement of low oxygen tensions in biological systems.

    PubMed

    James, P E; Grinberg, O Y; Goda, F; Panz, T; O'Hara, J A; Swartz, H M

    1997-07-01

    This paper describes the characteristics of a new oxygen sensitive, paramagnetic material that has some significant advantages for measurements of tissue pO2 by in vivo EPR. This paramagnetic component of Welsh coal, termed "gloxy" was found to have valuable EPR features that allow accurate measurement of low oxygen tensions in vivo; these include large oxygen-dependent changes in linewidth, a high number of paramagnetic spin centers (resulting in high signal amplitude), and stability in tissue allowing repeated pO2 measurements to be made in vivo with high precision. Renal pO2 was measured deep in the medulla region of isolated perfused kidneys and found to be lower than that in the cortex (1.7 +/- 0.05 and 7.1 +/- 0.3 mm Hg, respectively). The quality of the EPR signal obtained from the renal outer medulla and also from tumors in mice was such that the pO2 measurements were obtained with a precision of +/-3% of the measured pO2 (Kidney: 1.7 +/- 0.05 mmHg; Tumor: 1.37 +/- 0.04 mmHg). In vitro tests on the viability of cells and in vivo studies using Gloxy demonstrate the stability and inertness of this oxygen-sensitive material. PMID:9211379

  8. Discretely disordered photonic bandgap structures: a more accurate invariant measure calculation

    NASA Astrophysics Data System (ADS)

    Kissel, Glen J.

    2009-02-01

    In the one-dimensional optical analog to Anderson localization, a periodically layered medium has one or more parameters randomly disordered. Such a randomized system can be modeled by an infinite product of 2x2 random transfer matrices with the upper Lyapunov exponent of the matrix product identified as the localization factor (inverse localization length) for the model. The theorem of Furstenberg allows us, at least theoretically, to calculate this upper Lyapunov exponent. In Furstenberg's formula we not only integrate with respect to the probability measure of the random matrices, but also with respect to the invariant probability measure of the direction of the vector propagated by the random matrices. This invariant measure is difficult to find analytically, and, as a result, the most successful approach is to determine the invariant measure numerically. A Monte Carlo simulation which uses accumulated bin counts to track the direction of the propagated vector through a long chain of random matrices does a good job of estimating the invariant probability measure, but with a level of uncertainty. A potentially more accurate numerical technique by Froyland and Aihara obtains the invariant measure as a left eigenvector of a large sparse matrix containing probability values determined by the action of the random matrices on input vectors. We first apply these two techniques to a random Fibonacci sequence whose Lyapunov exponent was determined by Viswanath. We then demonstrate these techniques on a quarter-wave stack model with binary discrete disorder in layer thickness, and compare results to the continuously disordered counterpart.

  9. Accurate Measurements of the Dielectric Constant of Seawater at L Band

    NASA Technical Reports Server (NTRS)

    Lang, Roger H.; Utku, Cuneyt; Tarkocin, Yalcin; LeVine, David M.

    2010-01-01

    This report describes measurements of the dielectric constant of seawater at a frequency of 1.413 GHz that is at the center of the L-Sand radiometric protected frequency spectrum. Aquarius will be sensing the sea surface salinity from space in this band. The objective of the project is to refine the model function for the dielectric constant as a function of salinity and temperature so that remote sensing measurements can be made with the accuracy needed to meet the measurement goals (0.2 psu) of the Aquarius mission. The measurements were made, using a microwave cavity operated in the transmission configuration. The cavity's temperature was accurately regulated to 0.02 C by immersing it in a temperature controlled bath of distilled water and ethanol glycol. Seawater had been purchased from Ocean Scientific International Limited (OS1L) at salinities of 30, 35 and 38 psu. Measurements of these seawater samples were then made over a range of temperatures, from l0 C to 35 C in 5 C intervals. Repeated measurements were made at each temperature and salinity, Mean values and standard deviations were then computed. Total error budgets indicated that the real and imaginary parts of the dielectric constant had a relative accuracy of about l%.

  10. Generalized weighted ratio method for accurate turbidity measurement over a wide range.

    PubMed

    Liu, Hongbo; Yang, Ping; Song, Hong; Guo, Yilu; Zhan, Shuyue; Huang, Hui; Wang, Hangzhou; Tao, Bangyi; Mu, Quanquan; Xu, Jing; Li, Dejun; Chen, Ying

    2015-12-14

    Turbidity measurement is important for water quality assessment, food safety, medicine, ocean monitoring, etc. In this paper, a method that accurately estimates the turbidity over a wide range is proposed, where the turbidity of the sample is represented as a weighted ratio of the scattered light intensities at a series of angles. An improvement in the accuracy is achieved by expanding the structure of the ratio function, thus adding more flexibility to the turbidity-intensity fitting. Experiments have been carried out with an 850 nm laser and a power meter fixed on a turntable to measure the light intensity at different angles. The results show that the relative estimation error of the proposed method is 0.58% on average for a four-angle intensity combination for all test samples with a turbidity ranging from 160 NTU to 4000 NTU. PMID:26699060

  11. Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

    NASA Astrophysics Data System (ADS)

    Krimi, Soufiene; Klier, Jens; Jonuscheit, Joachim; von Freymann, Georg; Urbansky, Ralph; Beigang, René

    2016-07-01

    In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wet spray in the painting process.

  12. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study.

    PubMed

    Harnly, James

    2016-03-01

    Accurate measurements of the secondary metabolites in natural products and plant foods are critical for establishing relations between diet and health. There are as many as 50,000 secondary metabolites that may influence human health. Their structural and chemical diversity presents a challenge to analytical chemistry. With respect to flavonoids, putative identification is accessible, but positive identification and quantification are limited by the lack of standards. Quantification has been tested with use of both nonspecific and specific methods. Nonspecific methods, which include antioxidant capacity methods, fail to provide information on the measured components, suffer from numerous interferences, are not equatable, and are unsuitable for health research. Specific methods, such as LC with diode array and mass spectrometric detection, require the use of internal standards and relative molar response factors. These methods are relatively expensive and require a high level of expertise and experimental verification; however, they represent the only suitable means of relating health outcomes to specific dietary components. PMID:26980821

  13. Accurate Resolution Measurement for X-Ray Micro-CT Systems

    NASA Astrophysics Data System (ADS)

    Sharma, K. Sen; Seshadri, S.; Feser, M.; Wang, G.

    2011-09-01

    Accurate measurement of modulation transfer function (MTF), or alternatively point spread function, of an x-ray micro-CT system is essential for various purposes—to determine scanner resolution, to retrieve further information about a scanned object by image-processing, etc. In this paper, a new method for MTF measurement is proposed that can be used with any resolution pattern and is more adept at studying MTF spatial variation than the traditional method of using bar pattern analysis. A resolution target used to determine micro-CT resolution was scanned in a lab-based nano-CT system—the image from the nano-CT gave the `ground truth'. The ground truth was quantitavely compared with the micro-CT projection of same target to determine the point spread function of the system. Results matched well with bar pattern analysis, but the new method was able to study spatial variations while the bar pattern analysis failed.

  14. Apparatus for measuring rat body volume: a methodological proposition.

    PubMed

    Hohl, Rodrigo; de Oliveira, Renato Buscariolli; Vaz de Macedo, Denise; Brenzikofer, René

    2007-03-01

    We propose a communicating-vessels system to measure body volume in live rats through water level detection by hydrostatic weighing. The reproducibility, accuracy, linearity, and reliability of this apparatus were evaluated in two tests using previously weighed water or six aluminum cylinders of known volume after proper system calibration. The applicability of this apparatus to measurement of live animals (Wistar rats) was tested in a transversal experiment with five rats, anesthetized and nonanesthetized. We took 18 measurements of the volume under each condition (anesthetized and nonanesthetized), totaling 90 measurements. The addition of water volumes (50-700 ml) produced a regression equation with a slope of 1.0006 +/- 0.0017, intercept of 0.75 +/- 0.81 (R(2) = 0.99999, standard error of estimate = 0.58 ml), and bias of approximately 1 ml. The differences between cylinders of known volumes and volumes calculated by the system were <0.4 ml. Mean volume errors were 0.01-0.07%. Among the live models, the difference between the volumes obtained for anesthetized and nonanesthetized rats was 0.31 +/- 2.34 (SD) ml (n = 90). These data showed that animal movement does not interfere with the volume measured by the proposed apparatus, and neither anesthesia nor fur shaving is needed for this procedure. Nevertheless, some effort should be taken to eliminate air bubbles trapped in the apparatus or the fur. The proposed apparatus for measuring rat body volume is inexpensive and may be useful for a range of scientific purposes. PMID:17082370

  15. A solution for measuring accurate reaction time to visual stimuli realized with a programmable microcontroller.

    PubMed

    Ohyanagi, Toshio; Sengoku, Yasuhito

    2010-02-01

    This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work. PMID:20160303

  16. Home Circadian Phase Assessments with Measures of Compliance Yield Accurate Dim Light Melatonin Onsets

    PubMed Central

    Burgess, Helen J.; Wyatt, James K.; Park, Margaret; Fogg, Louis F.

    2015-01-01

    Study Objectives: There is a need for the accurate assessment of circadian phase outside of the clinic/laboratory, particularly with the gold standard dim light melatonin onset (DLMO). We tested a novel kit designed to assist in saliva sampling at home for later determination of the DLMO. The home kit includes objective measures of compliance to the requirements for dim light and half-hourly saliva sampling. Design: Participants were randomized to one of two 10-day protocols. Each protocol consisted of two back-to-back home and laboratory phase assessments in counterbalanced order, separated by a 5-day break. Setting: Laboratory or participants' homes. Participants: Thirty-five healthy adults, age 21–62 y. Interventions: N/A. Measurements and Results: Most participants received at least one 30-sec epoch of light > 50 lux during the home phase assessments (average light intensity 4.5 lux), but on average for < 9 min of the required 8.5 h. Most participants collected every saliva sample within 5 min of the scheduled time. Ninety-two percent of home DLMOs were not affected by light > 50 lux or sampling errors. There was no significant difference between the home and laboratory DLMOs (P > 0.05); on average the home DLMOs occurred 9.6 min before the laboratory DLMOs. The home DLMOs were highly correlated with the laboratory DLMOs (r = 0.91, P < 0.001). Conclusions: Participants were reasonably compliant to the home phase assessment procedures. The good agreement between the home and laboratory dim light melatonin onsets (DLMOs) demonstrates that including objective measures of light exposure and sample timing during home saliva sampling can lead to accurate home DLMOs. Clinical Trial Registration: Circadian Phase Assessments at Home, http://clinicaltrials.gov/show/NCT01487252, NCT01487252. Citation: Burgess HJ, Wyatt JK, Park M, Fogg LF. Home circadian phase assessments with measures of compliance yield accurate dim light melatonin onsets. SLEEP 2015;38(6):889–897

  17. k-Space Image Correlation Spectroscopy: A Method for Accurate Transport Measurements Independent of Fluorophore Photophysics

    PubMed Central

    Kolin, David L.; Ronis, David; Wiseman, Paul W.

    2006-01-01

    We present the theory and application of reciprocal space image correlation spectroscopy (kICS). This technique measures the number density, diffusion coefficient, and velocity of fluorescently labeled macromolecules in a cell membrane imaged on a confocal, two-photon, or total internal reflection fluorescence microscope. In contrast to r-space correlation techniques, we show kICS can recover accurate dynamics even in the presence of complex fluorophore photobleaching and/or “blinking”. Furthermore, these quantities can be calculated without nonlinear curve fitting, or any knowledge of the beam radius of the exciting laser. The number densities calculated by kICS are less sensitive to spatial inhomogeneity of the fluorophore distribution than densities measured using image correlation spectroscopy. We use simulations as a proof-of-principle to show that number densities and transport coefficients can be extracted using this technique. We present calibration measurements with fluorescent microspheres imaged on a confocal microscope, which recover Stokes-Einstein diffusion coefficients, and flow velocities that agree with single particle tracking measurements. We also show the application of kICS to measurements of the transport dynamics of α5-integrin/enhanced green fluorescent protein constructs in a transfected CHO cell imaged on a total internal reflection fluorescence microscope using charge-coupled device area detection. PMID:16861272

  18. Lateral force calibration: accurate procedures for colloidal probe friction measurements in atomic force microscopy.

    PubMed

    Chung, Koo-Hyun; Pratt, Jon R; Reitsma, Mark G

    2010-01-19

    The colloidal probe technique for atomic force microscopy (AFM) has allowed the investigation of an extensive range of surface force phenomena, including the measurement of frictional (lateral) forces between numerous materials. The quantitative accuracy of such friction measurements is often debated, in part due to a lack of confidence in existing calibration strategies. Here we compare three in situ AFM lateral force calibration techniques using a single colloidal probe, seeking to establish a foundation for quantitative measurement by linking these techniques to accurate force references available at the National Institute of Standards and Technology. We introduce a procedure for calibrating the AFM lateral force response to known electrostatic forces applied directly to the conductive colloidal probe. In a second procedure, we apply known force directly to the colloidal probe using a precalibrated piezo-resistive reference cantilever. We found agreement between these direct methods on the order of 2% (within random uncertainty for both measurements). In a third procedure, we performed a displacement-based calibration using the piezo-resistive reference cantilever as a stiffness reference artifact. The method demonstrated agreement on the order of 7% with the direct force methods, with the difference attributed to an expected systematic uncertainty, caused by in-plane deflection in the cantilever during loading. The comparison establishes the existing limits of instrument accuracy and sets down a basis for selection criteria for materials and methods in colloidal probe friction (lateral) force measurements via atomic force microscopy. PMID:19827782

  19. Handcrafted cuff manometers do not accurately measure endotracheal tube cuff pressure

    PubMed Central

    Annoni, Raquel; de Almeida, Antonio Evanir

    2015-01-01

    Objective To test the agreement between two handcrafted devices and a cuff-specific manometer. Methods The agreement between two handcrafted devices adapted to measure tracheal tube cuff pressure and a cuff-specific manometer was tested on 79 subjects. The cuff pressure was measured with a commercial manometer and with two handcrafted devices (HD) assembled with aneroid sphygmomanometers (HD1 and HD2). The data were compared using Wilcoxon and Spearman tests, the intraclass correlation coefficient (ICC) and limit-of-agreement analysis. Results Cuff pressures assessed with handcrafted devices were significantly different from commercial device measurements (pressures were higher when measured with HD1 and lower with HD2). The ICCs between the commercial device and HD1 and HD2 were excellent (ICC = 0.8 p < 0.001) and good (ICC = 0.66, p < 0.001), respectively. However, the Bland- Altman plots showed wide limits of agreement between HD1 and HD2 and the commercial device. Conclusion The handcrafted manometers do not provide accurate cuff pressure measurements when compared to a cuff-specific device and should not be used to replace the commercial cuff manometers in mechanically ventilated patients. PMID:26376160

  20. Accurate and automatic extrinsic calibration method for blade measurement system integrated by different optical sensors

    NASA Astrophysics Data System (ADS)

    He, Wantao; Li, Zhongwei; Zhong, Kai; Shi, Yusheng; Zhao, Can; Cheng, Xu

    2014-11-01

    Fast and precise 3D inspection system is in great demand in modern manufacturing processes. At present, the available sensors have their own pros and cons, and hardly exist an omnipotent sensor to handle the complex inspection task in an accurate and effective way. The prevailing solution is integrating multiple sensors and taking advantages of their strengths. For obtaining a holistic 3D profile, the data from different sensors should be registrated into a coherent coordinate system. However, some complex shape objects own thin wall feather such as blades, the ICP registration method would become unstable. Therefore, it is very important to calibrate the extrinsic parameters of each sensor in the integrated measurement system. This paper proposed an accurate and automatic extrinsic parameter calibration method for blade measurement system integrated by different optical sensors. In this system, fringe projection sensor (FPS) and conoscopic holography sensor (CHS) is integrated into a multi-axis motion platform, and the sensors can be optimally move to any desired position at the object's surface. In order to simple the calibration process, a special calibration artifact is designed according to the characteristics of the two sensors. An automatic registration procedure based on correlation and segmentation is used to realize the artifact datasets obtaining by FPS and CHS rough alignment without any manual operation and data pro-processing, and then the Generalized Gauss-Markoff model is used to estimate the optimization transformation parameters. The experiments show the measurement result of a blade, where several sampled patches are merged into one point cloud, and it verifies the performance of the proposed method.

  1. Determination of Probe Volume Dimensions in Coherent Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Tedder, Sarah A.; Weikl, Markus C.; Seeger, Thomas; Leipertz, Alfred

    2008-01-01

    When investigating combustion phenomena with pump-probe techniques, the spatial resolution is given by the overlapping region of the laser beams and thus defines the probe volume size. The size of this probe volume becomes important when the length scales of interest are on the same order or smaller. In this work, we present a new approach to measure the probe volume in three dimensions (3-D), which can be used to determine the probe volume length, diameter, and shape. The optical arrangement and data evaluation are demonstrated for a dual-pump dual-broadband coherent anti-Stokes Raman scattering (CARS) setup which is used for combustion diagnostics. This new approach offers a simple, quick alternative with more capabilities than formerly used probe volume measurement methods.

  2. Quantitative calcium resistivity based method for accurate and scalable water vapor transmission rate measurement.

    PubMed

    Reese, Matthew O; Dameron, Arrelaine A; Kempe, Michael D

    2011-08-01

    The development of flexible organic light emitting diode displays and flexible thin film photovoltaic devices is dependent on the use of flexible, low-cost, optically transparent and durable barriers to moisture and/or oxygen. It is estimated that this will require high moisture barriers with water vapor transmission rates (WVTR) between 10(-4) and 10(-6) g/m(2)/day. Thus there is a need to develop a relatively fast, low-cost, and quantitative method to evaluate such low permeation rates. Here, we demonstrate a method where the resistance changes of patterned Ca films, upon reaction with moisture, enable one to calculate a WVTR between 10 and 10(-6) g/m(2)/day or better. Samples are configured with variable aperture size such that the sensitivity and/or measurement time of the experiment can be controlled. The samples are connected to a data acquisition system by means of individual signal cables permitting samples to be tested under a variety of conditions in multiple environmental chambers. An edge card connector is used to connect samples to the measurement wires enabling easy switching of samples in and out of test. This measurement method can be conducted with as little as 1 h of labor time per sample. Furthermore, multiple samples can be measured in parallel, making this an inexpensive and high volume method for measuring high moisture barriers. PMID:21895269

  3. Accurate label-free reaction kinetics determination using initial rate heat measurements

    PubMed Central

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Jacobs, Denise; Hagen, Wilfred R.

    2015-01-01

    Accurate label-free methods or assays to obtain the initial reaction rates have significant importance in fundamental studies of enzymes and in application-oriented high throughput screening of enzyme activity. Here we introduce a label-free approach for obtaining initial rates of enzyme activity from heat measurements, which we name initial rate calorimetry (IrCal). This approach is based on our new finding that the data recorded by isothermal titration calorimetry for the early stages of a reaction, which have been widely ignored, are correlated to the initial rates. Application of the IrCal approach to various enzymes led to accurate enzyme kinetics parameters as compared to spectroscopic methods and enabled enzyme kinetic studies with natural substrate, e.g. proteases with protein substrates. Because heat is a label-free property of almost all reactions, the IrCal approach holds promise in fundamental studies of various enzymes and in use of calorimetry for high throughput screening of enzyme activity. PMID:26574737

  4. Measuring nonlinear oscillations using a very accurate and low-cost linear optical position transducer

    NASA Astrophysics Data System (ADS)

    Donoso, Guillermo; Ladera, Celso L.

    2016-09-01

    An accurate linear optical displacement transducer of about 0.2 mm resolution over a range of ∼40 mm is presented. This device consists of a stack of thin cellulose acetate strips, each strip longitudinally slid ∼0.5 mm over the precedent one so that one end of the stack becomes a stepped wedge of constant step. A narrowed light beam from a white LED orthogonally incident crosses the wedge at a known point, the transmitted intensity being detected with a phototransistor whose emitter is connected to a diode. We present the interesting analytical proof that the voltage across the diode is linearly dependent upon the ordinate of the point where the light beam falls on the wedge, as well as the experimental validation of such a theoretical proof. Applications to nonlinear oscillations are then presented—including the interesting case of a body moving under dry friction, and the more advanced case of an oscillator in a quartic energy potential—whose time-varying positions were accurately measured with our transducer. Our sensing device can resolve the dynamics of an object attached to it with great accuracy and precision at a cost considerably less than that of a linear neutral density wedge. The technique used to assemble the wedge of acetate strips is described.

  5. Accurate Measurement of the Effects of All Amino-Acid Mutations on Influenza Hemagglutinin.

    PubMed

    Doud, Michael B; Bloom, Jesse D

    2016-01-01

    Influenza genes evolve mostly via point mutations, and so knowing the effect of every amino-acid mutation provides information about evolutionary paths available to the virus. We and others have combined high-throughput mutagenesis with deep sequencing to estimate the effects of large numbers of mutations to influenza genes. However, these measurements have suffered from substantial experimental noise due to a variety of technical problems, the most prominent of which is bottlenecking during the generation of mutant viruses from plasmids. Here we describe advances that ameliorate these problems, enabling us to measure with greatly improved accuracy and reproducibility the effects of all amino-acid mutations to an H1 influenza hemagglutinin on viral replication in cell culture. The largest improvements come from using a helper virus to reduce bottlenecks when generating viruses from plasmids. Our measurements confirm at much higher resolution the results of previous studies suggesting that antigenic sites on the globular head of hemagglutinin are highly tolerant of mutations. We also show that other regions of hemagglutinin-including the stalk epitopes targeted by broadly neutralizing antibodies-have a much lower inherent capacity to tolerate point mutations. The ability to accurately measure the effects of all influenza mutations should enhance efforts to understand and predict viral evolution. PMID:27271655

  6. Accurate in situ measurement of complex refractive index and particle size in intralipid emulsions.

    PubMed

    Dong, Miao L; Goyal, Kashika G; Worth, Bradley W; Makkar, Sorab S; Calhoun, William R; Bali, Lalit M; Bali, Samir

    2013-08-01

    A first accurate measurement of the complex refractive index in an intralipid emulsion is demonstrated, and thereby the average scatterer particle size using standard Mie scattering calculations is extracted. Our method is based on measurement and modeling of the reflectance of a divergent laser beam from the sample surface. In the absence of any definitive reference data for the complex refractive index or particle size in highly turbid intralipid emulsions, we base our claim of accuracy on the fact that our work offers several critically important advantages over previously reported attempts. First, our measurements are in situ in the sense that they do not require any sample dilution, thus eliminating dilution errors. Second, our theoretical model does not employ any fitting parameters other than the two quantities we seek to determine, i.e., the real and imaginary parts of the refractive index, thus eliminating ambiguities arising from multiple extraneous fitting parameters. Third, we fit the entire reflectance-versus-incident-angle data curve instead of focusing on only the critical angle region, which is just a small subset of the data. Finally, despite our use of highly scattering opaque samples, our experiment uniquely satisfies a key assumption behind the Mie scattering formalism, namely, no multiple scattering occurs. Further proof of our method's validity is given by the fact that our measured particle size finds good agreement with the value obtained by dynamic light scattering. PMID:23922125

  7. Invited Article: Time accurate mass flow measurements of solid-fueled systems

    NASA Astrophysics Data System (ADS)

    Olliges, Jordan D.; Lilly, Taylor C.; Joslyn, Thomas B.; Ketsdever, Andrew D.

    2008-10-01

    A novel diagnostic method is described that utilizes a thrust stand mass balance (TSMB) to directly measure time-accurate mass flow from a solid-fuel thruster. The accuracy of the TSMB mass flow measurement technique was demonstrated in three ways including the use of an idealized numerical simulation, verifying a fluid mass calibration with high-speed digital photography, and by measuring mass loss in more than 30 hybrid rocket motor firings. Dynamic response of the mass balance was assessed through weight calibration and used to derive spring, damping, and mass moment of inertia coefficients for the TSMB. These dynamic coefficients were used to determine the mass flow rate and total mass loss within an acrylic and gaseous oxygen hybrid rocket motor firing. Intentional variations in the oxygen flow rate resulted in corresponding variations in the total propellant mass flow as expected. The TSMB was optimized to determine mass losses of up to 2.5 g and measured total mass loss to within 2.5% of that calculated by a NIST-calibrated digital scale. Using this method, a mass flow resolution of 0.0011 g/s or 2% of the average mass flow in this study has been achieved.

  8. Invited article: Time accurate mass flow measurements of solid-fueled systems.

    PubMed

    Olliges, Jordan D; Lilly, Taylor C; Joslyn, Thomas B; Ketsdever, Andrew D

    2008-10-01

    A novel diagnostic method is described that utilizes a thrust stand mass balance (TSMB) to directly measure time-accurate mass flow from a solid-fuel thruster. The accuracy of the TSMB mass flow measurement technique was demonstrated in three ways including the use of an idealized numerical simulation, verifying a fluid mass calibration with high-speed digital photography, and by measuring mass loss in more than 30 hybrid rocket motor firings. Dynamic response of the mass balance was assessed through weight calibration and used to derive spring, damping, and mass moment of inertia coefficients for the TSMB. These dynamic coefficients were used to determine the mass flow rate and total mass loss within an acrylic and gaseous oxygen hybrid rocket motor firing. Intentional variations in the oxygen flow rate resulted in corresponding variations in the total propellant mass flow as expected. The TSMB was optimized to determine mass losses of up to 2.5 g and measured total mass loss to within 2.5% of that calculated by a NIST-calibrated digital scale. Using this method, a mass flow resolution of 0.0011 g/s or 2% of the average mass flow in this study has been achieved. PMID:19044695

  9. Accurate three-dimensional shape and deformation measurement at microscale using digital image correlation.

    PubMed

    Ren, Maodong; Liang, Jin; Li, Leigang; Wei, Bin; Wang, Lizhong; Tang, Zhengzong

    2015-07-01

    Based on stereomicroscope and three-dimensional (3D) digital image correlation (DIC) method, a non-contact measurement technique is presented to measure the 3D shape and deformation data on miniature specimens and the corresponding microscopic measurement system is developed. A pair of cameras is mounted on a binocular stereo light microscope to acquire pairing micrographs from two different optical paths of a specimen surface spraying with speckle pattern. Considering complex optical paths and high magnification, an accurate equivalent relative calibration method, combining a priori warping functions, is proposed to correct image distortions and optimize the intrinsic and extrinsic parameters of stereomicroscope. Then, a fast one-dimensional synchronous stereo matching method, based on the DIC method and image rectification technique, is proposed to search for discontinuous corresponding points in the pairing micrographs. Finally, the 3D shape is reconstructed from the corresponding points, while the temporal micrographs acquired before and after deformation are employed to determine the full-field deformation. The effectiveness and accuracy of the presented microscale measurement technique are verified by a series of experiments. PMID:26233412

  10. Accurate Measurement of the Effects of All Amino-Acid Mutations on Influenza Hemagglutinin

    PubMed Central

    Doud, Michael B.; Bloom, Jesse D.

    2016-01-01

    Influenza genes evolve mostly via point mutations, and so knowing the effect of every amino-acid mutation provides information about evolutionary paths available to the virus. We and others have combined high-throughput mutagenesis with deep sequencing to estimate the effects of large numbers of mutations to influenza genes. However, these measurements have suffered from substantial experimental noise due to a variety of technical problems, the most prominent of which is bottlenecking during the generation of mutant viruses from plasmids. Here we describe advances that ameliorate these problems, enabling us to measure with greatly improved accuracy and reproducibility the effects of all amino-acid mutations to an H1 influenza hemagglutinin on viral replication in cell culture. The largest improvements come from using a helper virus to reduce bottlenecks when generating viruses from plasmids. Our measurements confirm at much higher resolution the results of previous studies suggesting that antigenic sites on the globular head of hemagglutinin are highly tolerant of mutations. We also show that other regions of hemagglutinin—including the stalk epitopes targeted by broadly neutralizing antibodies—have a much lower inherent capacity to tolerate point mutations. The ability to accurately measure the effects of all influenza mutations should enhance efforts to understand and predict viral evolution. PMID:27271655

  11. Accurate measurement of bromine contents in plastic samples by instrumental neutron activation analysis.

    PubMed

    Kim, I J; Lee, K S; Hwang, E; Min, H S; Yim, Y H

    2013-03-26

    Accurate measurements of bromine contents in plastic samples were made by the direct comparator instrumental neutron activation analysis (INAA). Individual factors affecting the measurements were comprehensively evaluated and compensated, including the volatility loss of bromine from standard comparators, the background bromine level in the filter papers used for preparation of the standard comparators, nuclear interference, γ-ray spectral interference and the variance among replicates of the samples. Uncertainty contributions from those factors were thoroughly evaluated and included in the uncertainty budgeting of the INAA measurement. (81)Br was chosen as the target isotope, and the INAA measurements for bromine were experimentally confirmed to exhibit good linearity within a bromine content range of 10-170 μg. The established method has been applied to the analysis of eight plastic samples: four commercially available certified reference materials (CRMs) of polyethylene and polystyrene and four acrylonitrile butadiene styrene (ABS) samples prepared as the candidate reference materials (KRISS CRM 113-01-012, -013, -014 and -015). The bromine contents of the samples were calculated at three different γ-ray energies and compared, showing good agreement. The results of the four CRMs also showed good consistency with their certified values within the stated uncertainties. Finally, the bromine contents of the ABS samples were determined with expanded uncertainties (at a 95% level of confidence) between 2.5% and 5% in a bromine content range of 25-900 mg kg(-1). PMID:23498117

  12. Transcutaneous measurement of volume blood flow

    NASA Technical Reports Server (NTRS)

    Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.

    1974-01-01

    Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.

  13. Accurate measurements of ozone absorption cross-sections in the Hartley band

    NASA Astrophysics Data System (ADS)

    Viallon, J.; Lee, S.; Moussay, P.; Tworek, K.; Petersen, M.; Wielgosz, R. I.

    2015-03-01

    Ozone plays a crucial role in tropospheric chemistry, is the third largest contributor to greenhouse radiative forcing after carbon dioxide and methane and also a toxic air pollutant affecting human health and agriculture. Long-term measurements of tropospheric ozone have been performed globally for more than 30 years with UV photometers, all relying on the absorption of ozone at the 253.65 nm line of mercury. We have re-determined this cross-section and report a value of 11.27 x 10-18 cm2 molecule-1 with an expanded relative uncertainty of 0.86% (coverage factor k= 2). This is lower than the conventional value currently in use and measured by Hearn (1961) with a relative difference of 1.8%, with the consequence that historically reported ozone concentrations should be increased by 1.8%. In order to perform the new measurements of cross-sections with reduced uncertainties, a system was set up to generate pure ozone in the gas phase together with an optical system based on a UV laser with lines in the Hartley band, including accurate path length measurement of the absorption cell and a careful evaluation of possible impurities in the ozone sample by mass spectrometry and Fourier transform infrared spectroscopy. This resulted in new measurements of absolute values of ozone absorption cross-sections of 9.48 x 10-18, 10.44 x 10-18 and 11.07 x 10-18 cm2 molecule-1, with relative expanded uncertainties better than 0.7%, for the wavelengths (in vacuum) of 244.06, 248.32, and 257.34 nm respectively. The cross-section at the 253.65 nm line of mercury was determined by comparisons using a Standard Reference Photometer equipped with a mercury lamp as the light source. The newly reported value should be used in the future to obtain the most accurate measurements of ozone concentration, which are in closer agreement with non-UV-photometry based methods such as the gas phase titration of ozone with nitrogen monoxide.

  14. Three-Dimensional Ultrasound Measurement of Blood Volume Flow in the Umbilical Cord

    PubMed Central

    Pinter, Stephen Z.; Rubin, Jonathan M.; Kripfgans, Oliver D.; Treadwell, Marjorie C.; Romero, Vivian C.; Richards, Michael S.; Zhang, Man; Hall, Anne L.; Fowlkes, J. Brian

    2013-01-01

    Objectives Three-dimensional (3D) umbilical cord blood volume flow measurement with the intention of providing a straightforward, consistent, and accurate method that overcomes the limitations associated with traditional pulsed-wave Doppler flow measurement and provides a means by which to recognize and manage at-risk pregnancies. Methods The first study involved 3D ultrasound volume flow measurements in seven healthy ewes whose pregnancies ranged from 18 to 19 weeks’ gestation (7 singletons). Sonographic umbilical arterial and venous flow measurements from each fetus were compared to the corresponding average measured arterial/venous flow to assess feasibility of measurement in a static vessel. A second complementary study involved 3D ultrasound volume flow measurements in seven healthy women whose pregnancies ranged from 17.9 to 36.3 weeks’ gestation (6 singletons, 1 twin). Umbilical venous flow measurements were compared to similar flow measurements reported in the literature. Pregnancy outcomes were abstracted from the medical records of the recruited patients. Results In the fetal sheep model, arterial/venous flow comparisons yielded errors of 10% or less for eight out of the nine measurements. In the clinical study, venous flow measurements showed agreement with the literature over a range of gestational ages. Two of the seven patients in the clinical study demonstrated lower flow than anticipated for gestational age; one was subsequently diagnosed with intrauterine growth restriction and the other with preeclampsia. Conclusions Accurate measurements of umbilical blood volume flow can be performed with relative ease in both the sheep model and in humans using the proposed 3D ultrasound flow measurement technique. Results encourage further development of the method as a means for diagnosis and identification of at-risk pregnancies. PMID:23197545

  15. Simple yet accurate noncontact device for measuring the radius of curvature of a spherical mirror

    SciTech Connect

    Spiridonov, Maxim; Toebaert, David

    2006-09-10

    An easily reproducible device is demonstrated to be capable of measuring the radii of curvature of spherical mirrors, both convex and concave, without resorting to high-end interferometric or tactile devices. The former are too elaborate for our purposes,and the latter cannot be used due to the delicate nature of the coatings applied to mirrors used in high-power CO2 laser applications. The proposed apparatus is accurate enough to be useful to anyone using curved optics and needing a quick way to assess the values of the radii of curvature, be it for entrance quality control or trouble shooting an apparently malfunctioning optical system. Specifically, the apparatus was designed for checking 50 mm diameter resonator(typically flat or tens of meters concave) and telescope (typically some meters convex and concave) mirrors for a high-power CO2 laser, but it can easily be adapted to any other type of spherical mirror by a straightforward resizing.

  16. Turtle utricle dynamic behavior using a combined anatomically accurate model and experimentally measured hair bundle stiffness

    PubMed Central

    Davis, J.L.; Grant, J.W.

    2014-01-01

    Anatomically correct turtle utricle geometry was incorporated into two finite element models. The geometrically accurate model included appropriately shaped macular surface and otoconial layer, compact gel and column filament (or shear) layer thicknesses and thickness distributions. The first model included a shear layer where the effects of hair bundle stiffness was included as part of the shear layer modulus. This solid model’s undamped natural frequency was matched to an experimentally measured value. This frequency match established a realistic value of the effective shear layer Young’s modulus of 16 Pascals. We feel this is the most accurate prediction of this shear layer modulus and fits with other estimates (Kondrachuk, 2001b). The second model incorporated only beam elements in the shear layer to represent hair cell bundle stiffness. The beam element stiffness’s were further distributed to represent their location on the neuroepithelial surface. Experimentally measured striola hair cell bundles mean stiffness values were used in the striolar region and the mean extrastriola hair cell bundles stiffness values were used in this region. The results from this second model indicated that hair cell bundle stiffness contributes approximately 40% to the overall stiffness of the shear layer– hair cell bundle complex. This analysis shows that high mass saccules, in general, achieve high gain at the sacrifice of frequency bandwidth. We propose the mechanism by which this can be achieved is through increase the otoconial layer mass. The theoretical difference in gain (deflection per acceleration) is shown for saccules with large otoconial layer mass relative to saccules and utricles with small otoconial layer mass. Also discussed is the necessity of these high mass saccules to increase their overall system shear layer stiffness. Undamped natural frequencies and mode shapes for these sensors are shown. PMID:25445820

  17. Measuring solar reflectance Part I: Defining a metric that accurately predicts solar heat gain

    SciTech Connect

    Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul

    2010-05-14

    Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective 'cool colored' surface because this irradiance contains a greater fraction of near-infrared light than typically found in ordinary (unconcentrated) global sunlight. At mainland U.S. latitudes, this metric RE891BN can underestimate the annual peak solar heat gain of a typical roof or pavement (slope {le} 5:12 [23{sup o}]) by as much as 89 W m{sup -2}, and underestimate its peak surface temperature by up to 5 K. Using R{sub E891BN} to characterize roofs in a building energy simulation can exaggerate the economic value N of annual cool-roof net energy savings by as much as 23%. We define clear-sky air mass one global horizontal ('AM1GH') solar reflectance R{sub g,0}, a simple and easily measured property that more accurately predicts solar heat gain. R{sub g,0} predicts the annual peak solar heat gain of a roof or pavement to within 2 W m{sup -2}, and overestimates N by no more than 3%. R{sub g,0} is well suited to rating the solar reflectances of roofs, pavements and walls. We show in Part II that R{sub g,0} can be easily and accurately measured with a pyranometer, a solar spectrophotometer or version 6 of the Solar Spectrum Reflectometer.

  18. Measuring solar reflectance - Part I: Defining a metric that accurately predicts solar heat gain

    SciTech Connect

    Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul

    2010-09-15

    Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective ''cool colored'' surface because this irradiance contains a greater fraction of near-infrared light than typically found in ordinary (unconcentrated) global sunlight. At mainland US latitudes, this metric R{sub E891BN} can underestimate the annual peak solar heat gain of a typical roof or pavement (slope {<=} 5:12 [23 ]) by as much as 89 W m{sup -2}, and underestimate its peak surface temperature by up to 5 K. Using R{sub E891BN} to characterize roofs in a building energy simulation can exaggerate the economic value N of annual cool roof net energy savings by as much as 23%. We define clear sky air mass one global horizontal (''AM1GH'') solar reflectance R{sub g,0}, a simple and easily measured property that more accurately predicts solar heat gain. R{sub g,0} predicts the annual peak solar heat gain of a roof or pavement to within 2 W m{sup -2}, and overestimates N by no more than 3%. R{sub g,0} is well suited to rating the solar reflectances of roofs, pavements and walls. We show in Part II that R{sub g,0} can be easily and accurately measured with a pyranometer, a solar spectrophotometer or version 6 of the Solar Spectrum Reflectometer. (author)

  19. NanoLuc Complementation Reporter Optimized for Accurate Measurement of Protein Interactions in Cells.

    PubMed

    Dixon, Andrew S; Schwinn, Marie K; Hall, Mary P; Zimmerman, Kris; Otto, Paul; Lubben, Thomas H; Butler, Braeden L; Binkowski, Brock F; Machleidt, Thomas; Kirkland, Thomas A; Wood, Monika G; Eggers, Christopher T; Encell, Lance P; Wood, Keith V

    2016-02-19

    Protein-fragment complementation assays (PCAs) are widely used for investigating protein interactions. However, the fragments used are structurally compromised and have not been optimized nor thoroughly characterized for accurately assessing these interactions. We took advantage of the small size and bright luminescence of NanoLuc to engineer a new complementation reporter (NanoBiT). By design, the NanoBiT subunits (i.e., 1.3 kDa peptide, 18 kDa polypeptide) weakly associate so that their assembly into a luminescent complex is dictated by the interaction characteristics of the target proteins onto which they are appended. To ascertain their general suitability for measuring interaction affinities and kinetics, we determined that their intrinsic affinity (KD = 190 μM) and association constants (kon = 500 M(-1) s(-1), koff = 0.2 s(-1)) are outside of the ranges typical for protein interactions. The accuracy of NanoBiT was verified under defined biochemical conditions using the previously characterized interaction between SME-1 β-lactamase and a set of inhibitor binding proteins. In cells, NanoBiT fusions to FRB/FKBP produced luminescence consistent with the linear characteristics of NanoLuc. Response dynamics, evaluated using both protein kinase A and β-arrestin-2, were rapid, reversible, and robust to temperature (21-37 °C). Finally, NanoBiT provided a means to measure pharmacology of kinase inhibitors known to induce the interaction between BRAF and CRAF. Our results demonstrate that the intrinsic properties of NanoBiT allow accurate representation of protein interactions and that the reporter responds reliably and dynamically in cells. PMID:26569370

  20. Integration of a silicon-based microprobe into a gear measuring instrument for accurate measurement of micro gears

    NASA Astrophysics Data System (ADS)

    Ferreira, N.; Krah, T.; Jeong, D. C.; Metz, D.; Kniel, K.; Dietzel, A.; Büttgenbach, S.; Härtig, F.

    2014-06-01

    The integration of silicon micro probing systems into conventional gear measuring instruments (GMIs) allows fully automated measurements of external involute micro spur gears of normal modules smaller than 1 mm. This system, based on a silicon microprobe, has been developed and manufactured at the Institute for Microtechnology of the Technische Universität Braunschweig. The microprobe consists of a silicon sensor element and a stylus which is oriented perpendicularly to the sensor. The sensor is fabricated by means of silicon bulk micromachining. Its small dimensions of 6.5 mm × 6.5 mm allow compact mounting in a cartridge to facilitate the integration into a GMI. In this way, tactile measurements of 3D microstructures can be realized. To enable three-dimensional measurements with marginal forces, four Wheatstone bridges are built with diffused piezoresistors on the membrane of the sensor. On the reverse of the membrane, the stylus is glued perpendicularly to the sensor on a boss to transmit the probing forces to the sensor element during measurements. Sphere diameters smaller than 300 µm and shaft lengths of 5 mm as well as measurement forces from 10 µN enable the measurements of 3D microstructures. Such micro probing systems can be integrated into universal coordinate measuring machines and also into GMIs to extend their field of application. Practical measurements were carried out at the Physikalisch-Technische Bundesanstalt by qualifying the microprobes on a calibrated reference sphere to determine their sensitivity and their physical dimensions in volume. Following that, profile and helix measurements were carried out on a gear measurement standard with a module of 1 mm. The comparison of the measurements shows good agreement between the measurement values and the calibrated values. This result is a promising basis for the realization of smaller probe diameters for the tactile measurement of micro gears with smaller modules.

  1. Experimental validation of Doppler echocardiographic measurement of volume flow through the stenotic aortic valve.

    PubMed

    Otto, C M; Pearlman, A S; Gardner, C L; Enomoto, D M; Togo, T; Tsuboi, H; Ivey, T D

    1988-08-01

    In aortic stenosis, evaluation of aortic valve area by the continuity equation assumes that the volume of flow through the stenotic valve can be measured accurately in the left ventricular outflow tract. To test the accuracy of Doppler volume-flow measurement proximal to a stenotic valve, we developed an open-chest canine model in which the native leaflets were sutured together to create variable degrees of acute aortic stenosis. Left ventricular and aortic pressures were measured with micromanometer-tipped catheters. Volume flow was controlled and varied by directing systemic venous return through a calibrated roller pump and back to the right atrium. Because transaortic volume flow will not equal roller pump output when there is coexisting aortic insufficiency (present in 67% of studies), transaortic flow was measured by electromagnetic flowmeter with the flow probe placed around the proximal descending thoracic aorta, just beyond the ligated arch vessels. In 12 adult, mongrel dogs (mean weight, 25 kg), the mean transaortic pressure gradient ranged from 2 to 74 mm Hg, and transaortic volume flow ranged from 0.9 to 3.2 l/min. In four dogs, electromagnetic flow that was measured distal to the valve was accurate compared with volume flow determined by timed collection of total aortic flow into a graduated cylinder (n = 24, r = 0.97, electromagnetic flow = 0.87 Direct +0.13 l/min). In eight subsequent dogs, electromagnetic flow was compared with transaortic cardiac output measured by Doppler echocardiography in the left ventricular outflow tract as circular cross-sectional area [pi(D/2)2] x left ventricular outflow tract velocity-time integral x heart rate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2969311

  2. A method to directly measure maximum volume of fish stomachs or digestive tracts

    USGS Publications Warehouse

    Burley, C.C.; Vigg, S.

    1989-01-01

    A new method for measuring maximum stomach or digestive tract volume of fish incorporates air injection at constant pressure with water displacement to measure directly the internal volume of a stomach or analogous structure. The method was tested with coho salmon, Oncorhynchus kisutch (Walbaum), which has a true stomach, and northern squawfish, Ptychocheilus oregonensis(Richardson), which has a modified foregut as a functional analogue. Both species were collected during July-October 1987 from the Columbia River, U.S.A. Relationships between fish weight (= volume) and maximum volume of the digestive organ were best fitted for coho salmon by an allometric model and for northern squawfish by an exponential model. Least squares regression analysis of individual measurements showed less variability in the volume of coho salmon stomachs (R2= 0.85) than in the total digestive tracts (R2= 0.55) and foreguts (R2= 0.61) of northern squawfish, relative to fish size. Compared to previous methods, the new technique has the advantage of accurately measuring the internal volume of a wide range of digestive organ shapes and sizes.

  3. Dynamic gas temperature measurement system, volume 1

    NASA Technical Reports Server (NTRS)

    Elmore, D. L.; Robinson, W. W.; Watkins, W. B.

    1983-01-01

    A gas temperature measurement system with compensated frequency response of 1 kHz and capability to operate in the exhaust of a gas turbine engine combustor was developed. A review of available technologies which could attain this objective was done. The most promising method was identified as a two wire thermocouple, with a compensation method based on the responses of the two different diameter thermocouples to the fluctuating gas temperature field. In a detailed design of the probe, transient conduction effects were identified as significant. A compensation scheme was derived to include the effects of gas convection and wire conduction. The two wire thermocouple concept was tested in a laboratory burner exhaust to temperatures of about 3000 F and in a gas turbine engine to combustor exhaust temperatures of about 2400 F. Uncompensated and compensated waveforms and compensation spectra are presented.

  4. Multiple apolipoprotein kinetics measured in human HDL by high-resolution/accurate mass parallel reaction monitoring.

    PubMed

    Singh, Sasha A; Andraski, Allison B; Pieper, Brett; Goh, Wilson; Mendivil, Carlos O; Sacks, Frank M; Aikawa, Masanori

    2016-04-01

    Endogenous labeling with stable isotopes is used to study the metabolism of proteins in vivo. However, traditional detection methods such as GC/MS cannot measure tracer enrichment in multiple proteins simultaneously, and multiple reaction monitoring MS cannot measure precisely the low tracer enrichment in slowly turning-over proteins as in HDL. We exploited the versatility of the high-resolution/accurate mass (HR/AM) quadrupole Orbitrap for proteomic analysis of five HDL sizes. We identified 58 proteins in HDL that were shared among three humans and that were organized into five subproteomes according to HDL size. For seven of these proteins, apoA-I, apoA-II, apoA-IV, apoC-III, apoD, apoE, and apoM, we performed parallel reaction monitoring (PRM) to measure trideuterated leucine tracer enrichment between 0.03 to 1.0% in vivo, as required to study their metabolism. The results were suitable for multicompartmental modeling in all except apoD. These apolipoproteins in each HDL size mainly originated directly from the source compartment, presumably the liver and intestine. Flux of apolipoproteins from smaller to larger HDL or the reverse contributed only slightly to apolipoprotein metabolism. These novel findings on HDL apolipoprotein metabolism demonstrate the analytical breadth and scope of the HR/AM-PRM technology to perform metabolic research. PMID:26862155

  5. Can structured data fields accurately measure quality of care? The example of falls.

    PubMed

    Ganz, David A; Almeida, Shone; Roth, Carol P; Reuben, David B; Wenger, Neil S

    2012-01-01

    By automating collection of data elements, electronic health records may simplify the process of measuring the quality of medical care. Using data from a quality improvement initiative in primary care medical groups, we sought to determine whether the quality of care for falls and fear of falling in outpatients aged 75 and older could be accurately measured solely from codable (non-free-text) data in a structured visit note. A traditional medical record review by trained abstractors served as the criterion standard. Among 215 patient records reviewed, we found a structured visit note in 54% of charts within 3 mo of the date patients had been identified as having falls or fear of falling. The reliability of an algorithm based on codable data was at least good (kappa of at least 0.61) compared with full medical record review for three care processes recommended for patients with two falls or one fall with injury in the past year: orthostatic vital signs, vision test/eye examination, and home safety evaluation. However, the automated algorithm routinely underestimated quality of care. Performance standards based on automated measurement of quality of care from electronic health records need to account for documentation occurring in nonstructured form. PMID:23408222

  6. Relative Evaluation of the Independent Volume Measures of Caverns

    SciTech Connect

    MUNSON,DARRELL E.

    2000-08-01

    Throughout the construction and operation of the caverns of the Strategic Petroleum Reserve (SPR), three types of cavern volume measurements have been maintained. These are: (1) the calculated solution volume determined during initial construction by solution mining and any subsequent solutioning during oil transfers, (2) the calculated sonar volume determined through sonar surveys of the cavern dimensions, and (3) the direct metering of oil to determine the volume of the cavern occupied by the oil. The objective of this study is to compare these measurements to each other and determine, if possible, the uncertainties associated with a given type of measurement. Over time, each type of measurement has acquired a customary, or an industry accepted, stated uncertainty. This uncertainty is not necessarily the result of a technical analysis. Ultimately there is one definitive quantity, the oil volume measure by the oil custody transfer meters, taken by all parties to the transfer as the correct ledger amount and for which the SPR Project is accountable. However, subsequent transfers within a site may not be with meters of the same accuracy. In this study, a very simple theory of the perfect relationship is used to evaluate the correlation (deviation) of the various measures. This theory permits separation of uncertainty and bias. Each of the four SPR sites are examined, first with comparisons between the calculated solution volumes and the sonar volumes determined during construction, then with comparisons of the oil inventories and the sonar volumes obtained either by surveying through brine prior to oil filling or through the oil directly.

  7. Accurate measurements of thermodynamic properties of solutes in ionic liquids using inverse gas chromatography.

    PubMed

    Mutelet, Fabrice; Jaubert, Jean-Noël

    2006-01-13

    Activity coefficients at infinite dilution of 29 organic compounds in two room temperature ionic liquids were determined using inverse gas chromatography. The measurements were carried out at different temperatures between 323.15 and 343.15K. To establish the influence of concurrent retention mechanisms on the accuracy of activity coefficients at infinite dilution for 1-butyl-3-methylimidazolium octyl sulfate and 1-ethyl-3-methylimidazolium tosylate, phase loading studies of the net retention volume per gram of packing as a function of the percent phase loading were used. It is shown that most of the solutes are retained largely by partition with a small contribution from adsorption on 1-butyl-3-methylimidazolium octyl sulfate and that the n-alkanes are retained predominantly by interfacial adsorption on 1-ethyl-3-methylimidazolium tosylate. PMID:16310203

  8. The measurement of red blood cell volume change induced by Ca2+ based on full field quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Seungrag; Lee, Ji Yong; Yang, Wenzhong; Kim, Dug Young

    2009-02-01

    We present the measurement of red blood cell (RBC) volume change induced by Ca2+ for a live cell imaging with full field quantitative phase microscopy (FFQPM). FFQPM is based on the Mach-Zehnder interferometer combined with an inverted microscopy system. We present the effective method to obtain a clear image and an accurate volume of the cells. An edge detection technique is used to accurately resolve the boundary between the cell line and the suspension medium. The measurement of the polystyrene bead diameter and volume has been demonstrated the validity of our proposed method. The measured phase profile can be easily converted into thickness profile. The measured polystyrene bead volume and the simulated result are about 14.74 μm3 and 14.14 μm3, respectively. The experimental results of our proposed method agree well with the simulated results within less than 4 %. We have also measured the volume variation of a single RBC on a millisecond time scale. Its mean volume is 54.02 μm3 and its standard deviation is 0.52 μm3. With the proposed system, the shape and volume changes of RBC induced by the increased intracellular Ca2+ are measured after adding ionophore A23187. A discocyte RBC is deformed to a spherocyte due to the increased intracellular Ca2+ in RBC. The volume of the spherocyte is 47.88 μm3 and its standard deviation is 0.19 μm3. We have demonstrated that the volume measurement technique is easy, accurate, and robust method with high volume sensitivity (<0.0000452 μm3) and this provides the ability to study a biological phenomenon in Hematology.

  9. Three-dimensional reconstruction for high-speed volume measurement

    NASA Astrophysics Data System (ADS)

    Lee, Dah-Jye; Lane, Robert M.; Chang, Guang-Hwa

    2001-02-01

    Volume measurement is an important process for various industries such as food processing, fruit and vegetable grading, etc. Value or price is often determined by the size of product. In seafood industry, for example, oyster meat is separated into four grades before being packaged. Large size grade means higher selling price than small size. More consistent packaging size is also an indication of high quality. Product size can be measured optically with machine vision technology for on-line inspection and grading systems. Most optical grading techniques use a two-dimensional area projection or the weight of the product to estimate the actual product volume. These methods are subject to measurement inaccuracy because of the missing thickness information. An algorithm combines laser triangulation technique with two-dimensional measurement to reconstruct a three-dimensional surface for volume measurement is introduced in this paper. The result of this technique shows a significant accuracy improvement from the area-projection method

  10. Measurement of gastric meal and secretion volumes using magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Hoad, C. L.; Parker, H.; Hudders, N.; Costigan, C.; Cox, E. F.; Perkins, A. C.; Blackshaw, P. E.; Marciani, L.; Spiller, R. C.; Fox, M. R.; Gowland, P. A.

    2015-02-01

    MRI can assess multiple gastric functions without ionizing radiation. However, time consuming image acquisition and analysis of gastric volume data, plus confounding of gastric emptying measurements by gastric secretions mixed with the test meal have limited its use to research centres. This study presents an MRI acquisition protocol and analysis algorithm suitable for the clinical measurement of gastric volume and secretion volume. Reproducibility of gastric volume measurements was assessed using data from 10 healthy volunteers following a liquid test meal with rapid MRI acquisition within one breath-hold and semi-automated analysis. Dilution of the ingested meal with gastric secretion was estimated using a respiratory-triggered T1 mapping protocol. Accuracy of the secretion volume measurements was assessed using data from 24 healthy volunteers following a mixed (liquid/solid) test meal with MRI meal volumes compared to data acquired using gamma scintigraphy (GS) on the same subjects studied on a separate study day. The mean ± SD coefficient of variance between 3 observers for both total gastric contents (including meal, secretions and air) and just the gastric contents (meal and secretion only) was 3  ±  2% at large gastric volumes (>200 ml). Mean ± SD secretion volumes post meal ingestion were 64  ±  51 ml and 110  ±  40 ml at 15 and 75 min, respectively. Comparison with GS meal volumes, showed that MRI meal only volume (after correction for secretion volume) were similar to GS, with a linear regression gradient ± std err of 1.06  ±  0.10 and intercept -11  ±  24 ml. In conclusion, (i) rapid volume acquisition and respiratory triggered T1 mapping removed the requirement to image during prolonged breath-holds (ii) semi-automatic analysis greatly reduced the time required to derive measurements and (iii) correction for secretion volumes provided accurate assessment of gastric meal volumes and emptying. Together these features

  11. Amygdalohippocampal MR volume measurements in the early stages of Alzheimer disease

    SciTech Connect

    Lehericy, S.; Baulac, M.; Chiras, J.; Pierot, L.; Martin, N.; Pillon, B.; Deweer, B.; Dubois, B.; Marsault, C.

    1994-05-01

    To evaluate the accuracy of hippocampal and amygdala volume measurements in diagnosing patients in the early stages of Alzheimer disease. Measurements of the hippocampal formation, amygdala, amygdalohippocampal complex (the two measurements summed), caudate nucleus, and ventricles, normalized for total intracranial volume, were obtained on coronal sections (1.5 T, 400/13 [repetition time/echo time], 5 mm) of 13 patients in the mild (minimental status {ge} 21) and five patients in the moderate stages of Alzheimer disease (10 < minimental status < 21), and eight age-matched control subjects. For patients with a minimental status score of 21 or greater, atrophy was significant for the amygdala and hippocampal formation (-36% and -25% for amygdala/total intracranial volume and hippocampal formation/total intracranial volume, respectively), but not for the caudate nucleus. No significant ventricular enlargement was found. For patients with a minimental status score less than 21, atrophy was more severe in all structures studied (amygdala/total intracranial volume -40%; hippocampal formation/total intracranial volume, -45%; caudate nucleus/total intracranial volume, -21%), and ventricles were enlarged (63%). No overlap was found between Alzheimer disease and control values for the amygdalohippocampal volume, even in the mild stages of the disease. In Alzheimer disease patients, hippocampal formation volumes correlated with the minimental status. Hippocampal and amygdala atrophy is marked and significant in the mild stages of Alzheimer disease. Volumetric measurements of the amygdala and the amygdalohippocampal complex appear more accurate than those of the hippocampal formation alone in distinguishing patients with Alzheimer disease. 46 refs., 8 figs., 2 tabs.

  12. High-Frequency CTD Measurements for Accurate GPS/acoustic Sea-floor Crustal Deformation Measurement System

    NASA Astrophysics Data System (ADS)

    Tadokoro, K.; Yasuda, K.; Taniguchi, S.; Uemura, Y.; Matsuhiro, K.

    2015-12-01

    The GPS/acoustic sea-floor crustal deformation measurement system has developed as a useful tool to observe tectonic deformation especially at subduction zones. One of the factors preventing accurate GPS/acoustic sea-floor crustal deformation measurement is horizontal heterogeneity of sound speed in the ocean. It is therefore necessary to measure the gradient directly from sound speed structure. We report results of high-frequency CTD measurements using Underway CTD (UCTD) in the Kuroshio region. We perform the UCTD measurements on May 2nd, 2015 at two stations (TCA and TOA) above the sea-floor benchmarks installed across the Nankai Trough, off the south-east of Kii Peninsula, middle Japan. The number of measurement points is six at each station along circles with a diameter of 1.8 nautical miles around the sea-floor benchmark. The stations TCA and TOA are located on the edge and the interior of the Kuroshio current, respectively, judging from difference in sea water density measured at the two stations, as well as a satellite image of sea-surface temperature distribution. We detect a sound speed gradient of high speeds in the southern part and low speeds in the northern part at the two stations. At the TCA station, the gradient is noticeable down to 300 m in depth; the maximum difference in sound speed is +/- 5 m/s. The sound speed difference is as small as +/- 1.3 m/s at depths below 300 m, which causes seafloor benchmark positioning error as large as 1 m. At the TOA station, the gradient is extremely small down to 100 m in depth. The maximum difference in sound speed is less than +/- 0.3 m/s that is negligible small for seafloor benchmark positioning error. Clear gradient of high speed is observed to the depths; the maximum difference in sound speed is +/- 0.8-0.9 m/s, causing seafloor benchmark positioning error of several tens centimeters. The UCTD measurement is effective tool to detect sound speed gradient. We establish a method for accurate sea

  13. Acoustic resolution photoacoustic Doppler flowmetry: practical considerations for obtaining accurate measurements of blood flow

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2014-03-01

    An assessment has been made of various experimental factors affecting the accuracy of flow velocities measured using a pulsed time correlation photoacoustic Doppler technique. In this method, Doppler time shifts are quantified via crosscorrelation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves are detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. This enables penetration depths of several millimetres or centimetres, unlike methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1 mm. In the acoustic resolution mode, it is difficult to detect time shifts in highly concentrated suspensions of flowing absorbers, such as red blood cell suspensions and whole blood, and this challenge supposedly arises because of the lack of spatial heterogeneity. However, by assessing the effect of different absorption coefficients and tube diameters, we offer an alternative explanation relating to light attenuation and parabolic flow. We also demonstrate a new signal processing method that surmounts the previous problem of measurement under-reading. This method is a form of signal range gating and enables mapping of the flow velocity profile across the tube as well as measurement of the average flow velocity. We show that, using our signal processing scheme, it is possible to measure the flow of whole blood using a relatively low frequency detector. This important finding paves the way for application of the technique to measurements of blood flow several centimetres deep in living tissue.

  14. 34 CFR 462.41 - How must tests be administered in order to accurately measure educational gain?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... measure educational gain? 462.41 Section 462.41 Education Regulations of the Offices of the Department of... to accurately measure educational gain? (a) General. A local eligible provider must measure the... provider must— (1) Administer a pre-test to measure a student's educational functioning level at intake,...

  15. 34 CFR 462.41 - How must tests be administered in order to accurately measure educational gain?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... measure educational gain? 462.41 Section 462.41 Education Regulations of the Offices of the Department of... to accurately measure educational gain? (a) General. A local eligible provider must measure the... provider must— (1) Administer a pre-test to measure a student's educational functioning level at intake,...

  16. 34 CFR 462.41 - How must tests be administered in order to accurately measure educational gain?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... measure educational gain? 462.41 Section 462.41 Education Regulations of the Offices of the Department of... to accurately measure educational gain? (a) General. A local eligible provider must measure the... provider must— (1) Administer a pre-test to measure a student's educational functioning level at intake,...

  17. 34 CFR 462.41 - How must tests be administered in order to accurately measure educational gain?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... measure educational gain? 462.41 Section 462.41 Education Regulations of the Offices of the Department of... to accurately measure educational gain? (a) General. A local eligible provider must measure the... provider must— (1) Administer a pre-test to measure a student's educational functioning level at intake,...

  18. Procedures for accurate U and Th isotope measurements by high precision MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Hoffmann, Dirk L.; Prytulak, Julie; Richards, David A.; Elliott, Tim; Coath, Christopher D.; Smart, Peter L.; Scholz, Denis

    2007-07-01

    We present multi-collector (MC) inductively coupled plasma mass spectrometry (ICPMS) protocols developed to obtain high precision, accurate determinations of U and Th isotope ratios that are applicable to a wide range of geological materials. MC-ICPMS provides a means to make high precision measurements but a recent laboratory inter-comparison, Regular European Inter-laboratory Measurement Evaluation Programme (REIMEP)-18, indicates that accurate results for U isotope ratios are not currently achieved by all facilities using MC-ICPMS. We detail a suite of protocols that can be used for a wide variety of U and Th isotope ratios and total loads. Particular attention is devoted to instrument optimisation, instrumental backgrounds, stability and memory effects, multiplier nonlinearity and yield determinations. Our results indicate that the extent of mass fractionation of U and Th analyses run under similar instrumental conditions is 0.48% per amu and 0.45% per amu, respectively, but cannot be distinguished at per mil precision levels. However, we note that multiplier-Faraday cup gain can be significantly different for U and Th by 1% and thus a U standard should not be used to correct Th measurements. For this reason, a combination of thermal ionisation mass spectrometry (TIMS) and MC-ICPMS methods have been used to determine the isotopic ratio of an in-house Th standard (TEDDi). As part of our methods, TEDDi and the U standard NBL-112a are used as bracketing standards for Th and U samples, respectively. While the in-house Th standard has 229Th-230Th-232Th composition specific for bracketing low 232Th analyses, the methods have been also successful for silicates with 230Th/232Th <10-5. Using NBL-112a, TEDDi and a gravimetrically calibrated mixed 229Th-236U spike, we demonstrate secular equilibrium in natural materials such as Table Mountain Latite and a Long Valley Glass Mountain sample with a reproducibility of ±3.8 per mil for 230Th/238U and ±2.8 per mil for 234U

  19. Accurate, in vivo NIR measurement of skeletal muscle oxygenation through fat

    NASA Astrophysics Data System (ADS)

    Jin, Chunguang; Zou, Fengmei; Ellerby, Gwenn E. C.; Scott, Peter; Peshlov, Boyan; Soller, Babs R.

    2010-02-01

    Noninvasive near infrared (NIR) spectroscopic measurement of muscle oxygenation requires the penetration of light through overlying skin and fat layers. We have previously demonstrated a dual-light source design and orthogonalization algorithm that corrects for inference from skin absorption and fat scattering. To achieve accurate muscle oxygen saturation (SmO2) measurement, one must select the appropriate source-detector distance (SD) to completely penetrate the fat layer. Methods: Six healthy subjects were supine for 15min to normalize tissue oxygenation across the body. NIR spectra were collected from the calf, shoulder, lower and upper thigh muscles with long SD distances of 30mm, 35mm, 40mm and 45mm. Spectral preprocessing with the short SD (3mm) spectrum preceded SmO2 calculation with a Taylor series expansion method. Three-way ANOVA was used to compare SmO2 values over varying fat thickness, subjects and SD distances. Results: Overlying fat layers varied in thickness from 4.9mm to 19.6mm across all subjects. SmO2 measured at the four locations were comparable for each subject (p=0.133), regardless of fat thickness and SD distance. SmO2 (mean+/-std dev) measured at calf, shoulder, low and high thigh were 62+/-3%, 59+/-8%, 61+/-2%, 61+/-4% respectively for SD distance of 30mm. In these subjects no significant influence of SD was observed (p=0.948). Conclusions: The results indicate that for our sensor design a 30mm SD is sufficient to penetrate through a 19mm fat layer and that orthogonalization with short SD effectively removed spectral interference from fat to result in a reproducible determination of SmO2.

  20. Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

    NASA Astrophysics Data System (ADS)

    Seifert, S.; Steenbergen, J. H. L.; van Dam, H. T.; Schaart, D. R.

    2012-09-01

    In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 ns).

  1. CALIBRATION OF X-RAY IMAGING DEVICES FOR ACCURATE INTENSITY MEASUREMENT

    SciTech Connect

    Haugh, M J; Charest, M R; Ross, P W; Lee, J J; Schneider, M B; Palmer, N E; Teruya, A T

    2012-02-16

    National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems. The X-ray sources that are used for calibration are both diode type and diode/fluorescer combinations. Calibrating the X-ray detectors is key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using radioactive sources that are traceable to the National Institute of Standards and Technology (NIST). The German synchrotron at Physikalische Technische Bundestalt (PTB) is used to calibrate silicon photodiodes over the energy range from 50 eV to 60 keV. The measurements on X-ray cameras made using the NSTec X-ray sources have included quantum efficiency averaged over all pixels, camera counts per photon per pixel, and response variation across the sensor. The instrumentation required to accomplish the calibrations is described. X-ray energies ranged from 720 eV to 22.7 keV. The X-ray sources produce narrow energy bands, allowing us to determine the properties as a function of X-ray energy. The calibrations were done for several types of imaging devices. There were back illuminated and front illuminated CCD (charge coupled device) sensors, and a CID (charge injection device) type camera. The CCD and CID camera types differ significantly in some of their properties that affect the accuracy of X-ray intensity measurements. All cameras discussed here are silicon based. The measurements of quantum efficiency variation with X-ray energy are compared to models for the sensor structure. Cameras that are not back-thinned are compared to those that are.

  2. Accurate measurement of reduced glutathione in gamma-glutamyltransferase-rich brain microvessel fractions.

    PubMed

    Maguin Gaté, Katy; Lartaud, Isabelle; Giummelly, Philippe; Legrand, Romain; Pompella, Alfonso; Leroy, Pierre

    2011-01-19

    Investigation of the redox status in the cerebral circulation is of great importance in order to evaluate intensity of oxidative stress-related diseases and the corresponding therapeutic effects. Changes in levels of reduced glutathione (GSH) are a major indicator of oxidative stress conditions. However, an important limitation for measurement of GSH as a biomarker is the possible presence in samples of gamma-glutamyltransferase (GGT) activity, i.e., the enzyme catalysing GSH breakdown. An accurate assay for the measurement of GSH in rat brain microvessels was developed, taking into account the high GGT activity expressed in this tissue compartment. Based on a sensitive fluorescence-based microtiter plate method using 2,3-naphthalenedicarboxyaldehyde as GSH-selective fluorogenic probe, the assay was applied to brain microvessels isolated from individual male Wistar rats. Pooling of microvessel fractions from several animals, as required by other procedures, could thus be avoided. In order to prevent GSH consumption via GGT activity, serine-boric acid complex (SBC) was added as inhibitor all along the microvessels isolation process. In the absence of GGT inhibition GSH in isolated brain microvessels was below the limit of quantification. Addition of SBC almost completely suppressed GGT activity, thus allowing GSH quantification (4.4±1.6 nmol.mg(-1) protein, n=3). Following the administration of a GSH depletor (diethyl maleate, 1g.kg(-1), i.p.), decreased GSH levels were measured in liver, brain tissue and brain microvessels as well, thus confirming the reliability of the method for safe GSH measurements in small-sized, individual samples presenting high GGT activity. PMID:21047497

  3. Instruments for Measuring Nursing Practice and Other Health Care Variables: Volume I [and] Volume 2.

    ERIC Educational Resources Information Center

    Ward, Mary Jane, Ed.; Lindeman, Carol Ann, Ed.

    This two-volume compilation classifies, describes, and critiques 159 clinical nursing instruments; 140 which measure psychosocial variables, 19 which measure physiological variables. Instruments are in various formats: paper and pencil tests, questionnaires, interview schedules, observation guides, rating scales, and mechanical devices such as…

  4. Validity and repeatability of a depth camera-based surface imaging system for thigh volume measurement.

    PubMed

    Bullas, Alice M; Choppin, Simon; Heller, Ben; Wheat, Jon

    2016-10-01

    Complex anthropometrics such as area and volume, can identify changes in body size and shape that are not detectable with traditional anthropometrics of lengths, breadths, skinfolds and girths. However, taking these complex with manual techniques (tape measurement and water displacement) is often unsuitable. Three-dimensional (3D) surface imaging systems are quick and accurate alternatives to manual techniques but their use is restricted by cost, complexity and limited access. We have developed a novel low-cost, accessible and portable 3D surface imaging system based on consumer depth cameras. The aim of this study was to determine the validity and repeatability of the system in the measurement of thigh volume. The thigh volumes of 36 participants were measured with the depth camera system and a high precision commercially available 3D surface imaging system (3dMD). The depth camera system used within this study is highly repeatable (technical error of measurement (TEM) of <1.0% intra-calibration and ~2.0% inter-calibration) but systematically overestimates (~6%) thigh volume when compared to the 3dMD system. This suggests poor agreement yet a close relationship, which once corrected can yield a usable thigh volume measurement. PMID:26928458

  5. Micro analysis of fringe field formed inside LDA measuring volume

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhijit; Nirala, A. K.

    2016-05-01

    In the present study we propose a technique for micro analysis of fringe field formed inside laser Doppler anemometry (LDA) measuring volume. Detailed knowledge of the fringe field obtained by this technique allows beam quality, alignment and fringe uniformity to be evaluated with greater precision and may be helpful for selection of an appropriate optical element for LDA system operation. A complete characterization of fringes formed at the measurement volume using conventional, as well as holographic optical elements, is presented. Results indicate the qualitative, as well as quantitative, improvement of fringes formed at the measurement volume by holographic optical elements. Hence, use of holographic optical elements in LDA systems may be advantageous for improving accuracy in the measurement.

  6. Residual waste volume measurement for Hanford underground storage tanks

    SciTech Connect

    Berglin, E.J.

    1996-08-21

    The Acquire Commercial Technology for Retrieval program seeks commercial solutions to measure any waste residual (i.e., heel)left after waste retrieval operations of underground radioactive storage tanks. The technology identified should operate in a range of waste depth thickness of 0 - 6 inches. This report provides a description of the need, requirements, and constraints for the residual waste volume measurement system; describes a logical approach to measuring waste volume; provides a brief review and assessment of available technologies; and outlines a set of integrated tests that will evaluate the performance of candidate technologies.

  7. A feasibility study of limb volume measuring systems

    NASA Technical Reports Server (NTRS)

    Lafferty, J. F.; Carter, W. M.

    1974-01-01

    Evaluation of the various techniques by which limb volume can be measured indicates that the odometric (electromechanical) method and the reflective scanner (optical) have a high probability of meeting the specifications of the LBNP experiments. Both of these methods provide segmental measurements from which the cross sectional area of the limb can be determined.

  8. Finding the Density of Objects without Measuring Mass and Volume

    ERIC Educational Resources Information Center

    Mumba, Frackson; Tsige, Mesfin

    2007-01-01

    A simple method based on the moment of forces and Archimedes' principle is described for finding density without measuring the mass and volume of an object. The method involves balancing two unknown objects of masses M[subscript 1] and M[subscript 2] on each side of a pivot on a metre rule and measuring their corresponding moment arms. The object…

  9. A particle-tracking approach for accurate material derivative measurements with tomographic PIV

    NASA Astrophysics Data System (ADS)

    Novara, Matteo; Scarano, Fulvio

    2013-08-01

    The evaluation of the instantaneous 3D pressure field from tomographic PIV data relies on the accurate estimate of the fluid velocity material derivative, i.e., the velocity time rate of change following a given fluid element. To date, techniques that reconstruct the fluid parcel trajectory from a time sequence of 3D velocity fields obtained with Tomo-PIV have already been introduced. However, an accurate evaluation of the fluid element acceleration requires trajectory reconstruction over a relatively long observation time, which reduces random errors. On the other hand, simple integration and finite difference techniques suffer from increasing truncation errors when complex trajectories need to be reconstructed over a long time interval. In principle, particle-tracking velocimetry techniques (3D-PTV) enable the accurate reconstruction of single particle trajectories over a long observation time. Nevertheless, PTV can be reliably performed only at limited particle image number density due to errors caused by overlapping particles. The particle image density can be substantially increased by use of tomographic PIV. In the present study, a technique to combine the higher information density of tomographic PIV and the accurate trajectory reconstruction of PTV is proposed (Tomo-3D-PTV). The particle-tracking algorithm is applied to the tracers detected in the 3D domain obtained by tomographic reconstruction. The 3D particle information is highly sparse and intersection of trajectories is virtually impossible. As a result, ambiguities in the particle path identification over subsequent recordings are easily avoided. Polynomial fitting functions are introduced that describe the particle position in time with sequences based on several recordings, leading to the reduction in truncation errors for complex trajectories. Moreover, the polynomial regression approach provides a reduction in the random errors due to the particle position measurement. Finally, the acceleration

  10. The need for preoperative baseline arm measurement to accurately quantify breast cancer-related lymphedema.

    PubMed

    Sun, Fangdi; Skolny, Melissa N; Swaroop, Meyha N; Rawal, Bhupendra; Catalano, Paul J; Brunelle, Cheryl L; Miller, Cynthia L; Taghian, Alphonse G

    2016-06-01

    Breast cancer-related lymphedema (BCRL) is a feared outcome of breast cancer treatment, yet the push for early screening is hampered by a lack of standardized quantification. We sought to determine the necessity of preoperative baseline in accounting for temporal changes of upper extremity volume. 1028 women with unilateral breast cancer were prospectively screened for lymphedema by perometry. Thresholds were defined: relative volume change (RVC) ≥10 % for clinically significant lymphedema and ≥5 % including subclinical lymphedema. The first postoperative measurement (pseudo-baseline) simulated the case of no baseline. McNemar's test and binomial logistic regression models were used to analyze BCRL misdiagnoses. Preoperatively, 28.3 and 2.9 % of patients had arm asymmetry of ≥5 and 10 %, respectively. Without baseline, 41.6 % of patients were underdiagnosed and 40.1 % overdiagnosed at RVC ≥ 5 %, increasing to 50.0 and 54.8 % at RVC ≥ 10 %. Increased pseudo-baseline asymmetry, increased weight change between baselines, hormonal therapy, dominant use of contralateral arm, and not receiving axillary lymph node dissection (ALND) were associated with increased risk of underdiagnosis at RVC ≥ 5 %; not receiving regional lymph node radiation was significant at RVC ≥ 10 %. Increased pseudo-baseline asymmetry, not receiving ALND, and dominant use of ipsilateral arm were associated with overdiagnosis at RVC ≥ 5 %; increased pseudo-baseline asymmetry and not receiving ALND were significant at RVC ≥ 10 %. The use of a postoperative proxy even early after treatment results in poor sensitivity for identifying BCRL. Providers with access to patients before surgery should consider the consequent need for proper baseline, with specific strategy tailored by institution. PMID:27154787

  11. Effect of various environments and computed tomography scanning parameters on renal volume measurements in vitro: A phantom study

    PubMed Central

    Liu, Wangyan; Zhu, Yinsu; Tang, Lijun; Zhu, Xiaomei; Xu, Yi; Yang, Guanyu

    2016-01-01

    Kidney volume is an important parameter in clinical practice, and accurate assessment of kidney volume is vital. The aim of the present study was to evaluate the effect of various environments, tube voltages, tube currents and slice thicknesses on the accuracy of a novel segmentation software in determining renal volume on computed tomography (CT) images. The volumes of potatoes and porcine kidneys were measured on CT images and compared with the actual volumes, which were determined by a water displacement method. CT scans were performed under various situations, including different environments (air or oil); tube voltages/tube currents (80 kVp/200 mAs, 120 kVp/200 mAs, 120 kVp/100 mAs); and reconstructed slice thicknesses (0.75 or 1.5 mm). Percentage errors (PEs) relative to the reference standards were calculated. In addition, attenuation and image noise under different CT scanning parameters were compared. Student's t-test was also used to analyze the effect of various conditions on image quality and volume measurements. The results indicated that the volumes measured in oil were closer to the actual volumes (P<0.05). Furthermore, attenuation and image noise significantly increased when using a tube voltage of 80 kVp, while the mean PEs between 120 and 80 kVp voltages were not significantly different. The mean PEs were greater when using a tube current of 100 mAs compared with a current of 200 mAs (P<0.05). In addition, the volumes measured on 1.5 mm slice thickness were closer to the actual volumes (P<0.05). In conclusion, different environments, tube currents and slice thicknesses may affect the volume measurements. In the present study, the most accurate volume measurements were obtained at 120 kVp/200 mAs and a slice thickness of 1.5 mm. PMID:27446271

  12. How Accurate is Your Sclerostin Measurement? Comparison Between Three Commercially Available Sclerostin ELISA Kits.

    PubMed

    Piec, Isabelle; Washbourne, Christopher; Tang, Jonathan; Fisher, Emily; Greeves, Julie; Jackson, Sarah; Fraser, William D

    2016-06-01

    Sclerostin, bone formation antagonist is in the spotlight as a potential biomarker for diseases presenting with associated bone disorders such as chronic kidney disease (CDK-MBD). Accurate measurement of sclerostin is therefore important. Several immunoassays are available to measure sclerostin in serum and plasma. We compared the performance of three commercial ELISA kits. We measured sclerostin concentrations in serum and EDTA plasma obtained from healthy young (18-26 years) human subjects using kits from Biomedica, TECOmedical and from R&D Systems. The circulating sclerostin concentrations were systematically higher when measured with the Biomedica assay (serum: 35.5 ± 1.1 pmol/L; EDTA: 39.4 ± 2.0 pmol/L; mean ± SD) as compared with TECOmedical (serum: 21.8 ± 0.7 pmol/L; EDTA: 27.2 ± 1.3 pmol/L) and R&D Systems (serum: 7.6 ± 0.3 pmol/L; EDTA: 30.9 ± 1.5 pmol/L). We found a good correlation between the assay for EDTA plasma (r > 0.6; p < 0.001) while in serum, only measurements obtained using TECOmedical and R&D Systems assays correlated significantly (r = 0.78; p < 0.001). There was no correlation between matrices results when using the Biomedica kit (r = 0.20). The variability in values generated from Biomedica, R&D Systems and TECOmedical assays raises questions regarding the accuracy and specificity of the assays. Direct comparison of studies using different kits is not possible and great care should be given to measurement of sclerostin, with traceability of reagents. Standardization with appropriate material is required before different sclerostin assays can be introduced in clinical practice. PMID:26749312

  13. Accurate and Easy Measurement of Sliding Distance of Intramedullary Nail in Trochanteric Fracture

    PubMed Central

    Chinzei, Nobuaki; Niikura, Takahiro; Fujishiro, Takaaki; Hayashi, Shinya; Kanzaki, Noriyuki; Hashimoto, Shingo; Sakai, Yoshitada; Kuroda, Ryosuke; Kurosaka, Masahiro

    2015-01-01

    Background In daily clinical practice, it is essential to properly evaluate the postoperative sliding distance of various femoral head fixation devices (HFD) for trochanteric fractures. Although it is necessary to develop an accurate and reproducible method that is unaffected by inconsistent postoperative limb position on radiography, few studies have examined which method is optimal. Therefore, the purpose of this study is to prospectively compare the accuracy and reproducibility of our four original methods in the measurement of sliding distance of the HFD. Methods Radiographs of plastic simulated bone implanted with Japanese proximal femoral nail antirotation were taken in five limb postures: neutral, flexion, minute internal rotation, greater external rotation, and flexion with external rotation. Orthopedic surgeons performed five measurements of the sliding distance of the HFD in each of the flowing four methods: nail axis reference (NAR), modified NAR, inner edge reference, and nail tip reference. We also assessed two clinical cases by using these methods and evaluated the intraclass correlation coefficients. Results The measured values were consistent in the NAR method regardless of limb posture, with an even smaller error when using the modified NAR method. The standard deviation (SD) was high in the nail tip reference method and extremely low in the modified NAR method. In the two clinical cases, the SD was the lowest in the modified NAR method, similar to the results using plastic simulated bone. The intraclass correlation coefficients showed the highest value in the modified NAR method. Conclusions We conclude that the modified NAR method should be the most recommended based on its accuracy, reproducibility, and usefulness. PMID:26217459

  14. Accurate 3D kinematic measurement of temporomandibular joint using X-ray fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Yamazaki, Takaharu; Matsumoto, Akiko; Sugamoto, Kazuomi; Matsumoto, Ken; Kakimoto, Naoya; Yura, Yoshiaki

    2014-04-01

    Accurate measurement and analysis of 3D kinematics of temporomandibular joint (TMJ) is very important for assisting clinical diagnosis and treatment of prosthodontics and orthodontics, and oral surgery. This study presents a new 3D kinematic measurement technique of the TMJ using X-ray fluoroscopic images, which can easily obtain the TMJ kinematic data in natural motion. In vivo kinematics of the TMJ (maxilla and mandibular bone) is determined using a feature-based 2D/3D registration, which uses beads silhouette on fluoroscopic images and 3D surface bone models with beads. The 3D surface models of maxilla and mandibular bone with beads were created from CT scans data of the subject using the mouthpiece with the seven strategically placed beads. In order to validate the accuracy of pose estimation for the maxilla and mandibular bone, computer simulation test was performed using five patterns of synthetic tantalum beads silhouette images. In the clinical applications, dynamic movement during jaw opening and closing was conducted, and the relative pose of the mandibular bone with respect to the maxilla bone was determined. The results of computer simulation test showed that the root mean square errors were sufficiently smaller than 1.0 mm and 1.0 degree. In the results of clinical application, during jaw opening from 0.0 to 36.8 degree of rotation, mandibular condyle exhibited 19.8 mm of anterior sliding relative to maxillary articular fossa, and these measurement values were clinically similar to the previous reports. Consequently, present technique was thought to be suitable for the 3D TMJ kinematic analysis.

  15. Accurate measurement of respiratory airway wall thickness in CT images using a signal restoration technique

    NASA Astrophysics Data System (ADS)

    Park, Sang Joon; Kim, Tae Jung; Kim, Kwang Gi; Lee, Sang Ho; Goo, Jin Mo; Kim, Jong Hyo

    2008-03-01

    Airway wall thickness (AWT) is an important bio-marker for evaluation of pulmonary diseases such as chronic bronchitis, bronchiectasis. While an image-based analysis of the airway tree can provide precise and valuable airway size information, quantitative measurement of AWT in Multidetector-Row Computed Tomography (MDCT) images involves various sources of error and uncertainty. So we have developed an accurate AWT measurement technique for small airways with three-dimensional (3-D) approach. To evaluate performance of these techniques, we used a set of acryl tube phantom was made to mimic small airways to have three different sizes of wall diameter (4.20, 1.79, 1.24 mm) and wall thickness (1.84, 1.22, 0.67 mm). The phantom was imaged with MDCT using standard reconstruction kernel (Sensation 16, Siemens, Erlangen). The pixel size was 0.488 mm × 0.488 mm × 0.75 mm in x, y, and z direction respectively. The images were magnified in 5 times using cubic B-spline interpolation, and line profiles were obtained for each tube. To recover faithful line profile from the blurred images, the line profiles were deconvolved with a point spread kernel of the MDCT which was estimated using the ideal tube profile and image line profile. The inner diameter, outer diameter, and wall thickness of each tube were obtained with full-width-half-maximum (FWHM) method for the line profiles before and after deconvolution processing. Results show that significant improvement was achieved over the conventional FWHM method in the measurement of AWT.

  16. Accurate burner air flow measurement for low NO{sub x} burners

    SciTech Connect

    Earley, D.; Penterson, C.

    1998-07-01

    In 1990, Congress enacted an amendment to the Clean Air Act that required reductions in NO{sub x} emissions through the application of low NO{sub x} burner systems on fossil fueled utility steam generators. For most of the existing steam generator population, the original burning equipment incorporated highly turbulent burners that created significant in-furnace flame interaction. Thus, the measurement and control of air flow to the individual burners was much less critical than in recent years with low NO{sub x} combustion systems. With low NO{sub x} systems, the reduction of NO{sub x} emissions, as well as minimizing flyash unburned carbon levels, is very much dependent on the ability to control the relative ratios of air and fuel on a per-burner basis and their rate of mixing, particularly in the near burner zones. Air Monitor Corporation (AMC) and DB Riley, Inc. (DBR), and a large Midwestern electric utility have successfully developed and applied AMC's equipment to low NO{sub x} coal burners in order to enhance NO{sub x} control combustion systems. The results have improved burner optimization and provided real time continuous air flow balancing capability and the control of individual burner stoichiometries. To date, these enhancements have been applied to wall-fired low NO{sub x} systems for balancing individual burner air flows in a common windbox and to staged combustion systems. Most recently, calibration testing in a wind tunnel facility of AMC's individual burner air measurement (IBAM{trademark}) probes installed in DB Riley's low NO{sub x} CCV{reg{underscore}sign} burners has demonstrated the ability to produce reproducible and consistent air flow measurement accurate to within 5%. This paper will summarize this product development and quantify the benefits of its application to low NO{sub x} combustion systems.

  17. Three-dimensional direct measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections.

    PubMed

    Bensley, Jonathan Guy; De Matteo, Robert; Harding, Richard; Black, Mary Jane

    2016-01-01

    Quantitative assessment of myocardial development and disease requires accurate measurement of cardiomyocyte volume, nuclearity (nuclei per cell), and ploidy (genome copies per cell). Current methods require enzymatically isolating cells, which excludes the use of archived tissue, or serial sectioning. We describe a method of analysis that permits the direct simultaneous measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections. To demonstrate the utility of our technique, heart tissue was obtained from four species (rat, mouse, rabbit, sheep) at up to three life stages: prenatal, weaning and adulthood. Thick (40 μm) paraffin sections were stained with Wheat Germ Agglutinin-Alexa Fluor 488 to visualise cell membranes, and DAPI (4',6-diamidino-2-phenylindole) to visualise nuclei and measure ploidy. Previous methods have been restricted to thin sections (2-10 μm) and offer an incomplete picture of cardiomyocytes. Using confocal microscopy and three-dimensional image analysis software (Imaris Version 8.2, Bitplane AG, Switzerland), cardiomyocyte volume, nuclearity, and ploidy were measured. This method of staining and analysis of cardiomyocytes enables accurate morphometric measurements in thick histological sections, thus unlocking the potential of archived tissue. Our novel time-efficient method permits the entire cardiomyocyte to be visualised directly in 3D, eliminating the need for precise alignment of serial sections. PMID:27048757

  18. Three-dimensional direct measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections

    NASA Astrophysics Data System (ADS)

    Bensley, Jonathan Guy; de Matteo, Robert; Harding, Richard; Black, Mary Jane

    2016-04-01

    Quantitative assessment of myocardial development and disease requires accurate measurement of cardiomyocyte volume, nuclearity (nuclei per cell), and ploidy (genome copies per cell). Current methods require enzymatically isolating cells, which excludes the use of archived tissue, or serial sectioning. We describe a method of analysis that permits the direct simultaneous measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections. To demonstrate the utility of our technique, heart tissue was obtained from four species (rat, mouse, rabbit, sheep) at up to three life stages: prenatal, weaning and adulthood. Thick (40 μm) paraffin sections were stained with Wheat Germ Agglutinin-Alexa Fluor 488 to visualise cell membranes, and DAPI (4‧,6-diamidino-2-phenylindole) to visualise nuclei and measure ploidy. Previous methods have been restricted to thin sections (2–10 μm) and offer an incomplete picture of cardiomyocytes. Using confocal microscopy and three-dimensional image analysis software (Imaris Version 8.2, Bitplane AG, Switzerland), cardiomyocyte volume, nuclearity, and ploidy were measured. This method of staining and analysis of cardiomyocytes enables accurate morphometric measurements in thick histological sections, thus unlocking the potential of archived tissue. Our novel time-efficient method permits the entire cardiomyocyte to be visualised directly in 3D, eliminating the need for precise alignment of serial sections.

  19. Three-dimensional direct measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections

    PubMed Central

    Bensley, Jonathan Guy; De Matteo, Robert; Harding, Richard; Black, Mary Jane

    2016-01-01

    Quantitative assessment of myocardial development and disease requires accurate measurement of cardiomyocyte volume, nuclearity (nuclei per cell), and ploidy (genome copies per cell). Current methods require enzymatically isolating cells, which excludes the use of archived tissue, or serial sectioning. We describe a method of analysis that permits the direct simultaneous measurement of cardiomyocyte volume, nuclearity, and ploidy in thick histological sections. To demonstrate the utility of our technique, heart tissue was obtained from four species (rat, mouse, rabbit, sheep) at up to three life stages: prenatal, weaning and adulthood. Thick (40 μm) paraffin sections were stained with Wheat Germ Agglutinin-Alexa Fluor 488 to visualise cell membranes, and DAPI (4′,6-diamidino-2-phenylindole) to visualise nuclei and measure ploidy. Previous methods have been restricted to thin sections (2–10 μm) and offer an incomplete picture of cardiomyocytes. Using confocal microscopy and three-dimensional image analysis software (Imaris Version 8.2, Bitplane AG, Switzerland), cardiomyocyte volume, nuclearity, and ploidy were measured. This method of staining and analysis of cardiomyocytes enables accurate morphometric measurements in thick histological sections, thus unlocking the potential of archived tissue. Our novel time-efficient method permits the entire cardiomyocyte to be visualised directly in 3D, eliminating the need for precise alignment of serial sections. PMID:27048757

  20. Pleural liquid clearance rate measured in awake sheep by the volume of dilution method

    SciTech Connect

    Broaddus, V.C.; Wiener-Kronish, J.P.; Berthiaume, Y.; Staub, N.C.

    1986-03-01

    The authors reported 24h clearance of mock pleural effusions measured terminally in sheep. To measure effusion volume at different times in the same sheep, they injected /sup 111/In-transferrin and measured its dilution. In 5 sheep with effusions of known sizes, the method was accurate to +/-10%. In 5 awake sheep, the authors injected 10 ml/kg of a 1% protein solution via a non-penetrating rib capsule. At 6h, the authors measured the volume by the dilution method and at 24h by direct recovery. The clearance rate in each animal was constant at 2.9-6.0%/h (average 4.8 +/- 1.3%/h). This new method gives a reliable two point clearance rate and requires fewer animals.

  1. Enabling high grayscale resolution displays and accurate response time measurements on conventional computers.

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-01-01

    Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ (1) and DataPixx (2) use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher (3) described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network (4) and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements. Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect

  2. Examining factors that may influence accurate measurement of testosterone in sea turtles.

    PubMed

    Graham, Katherine M; Mylniczenko, Natalie D; Burns, Charlene M; Bettinger, Tammie L; Wheaton, Catharine J

    2016-01-01

    Differences in reported testosterone concentrations in male sea turtle blood samples are common in the veterinary literature, but may be accounted for by differences in sample handling and processing prior to assay. Therefore, our study was performed to determine best practices for testosterone analysis in male sea turtles (Caretta caretta and Chelonia mydas). Blood samples were collected into 5 collection tube types, and assay validation and measured testosterone concentrations were compared across different sample storage (fresh, refrigerated 1 week, or frozen), extraction (unextracted or ether-extracted), and processing treatment (untreated, homogenized, or dissociation reagent) conditions. Ether-extracted and dissociation reagent-treated samples validated in all conditions tested and are recommended for use, as unextracted samples validated only if assayed fresh. Dissociation reagent treatment was simpler to perform than ether extraction and resulted in total testosterone concentrations ~2.7-3.5 times greater than free testosterone measured in ether-extracted samples. Sample homogenization did not affect measured testosterone concentrations, and could be used to increase volume in gelled samples. An annual seasonal testosterone increase was observed in both species when ether extraction or dissociation reagent treatment was used. Annual deslorelin implant treatments in a Chelonia mydas male resulted in suppression of seasonal testosterone following the fourth treatment. Seasonal testosterone patterns resumed following discontinuation of deslorelin. Comparison of in-house and commercially available enzyme immunoassay kits revealed similar patterns of seasonal testosterone increases and deslorelin-induced suppression. Our study highlights the importance of methodological validation and provides laboratorians with best practices for testosterone enzyme immunoassay in sea turtles. PMID:26699527

  3. Photometric ``Flicker:'' Tracer of Granulation and an Accurate Measure of Stellar Surface Gravity

    NASA Astrophysics Data System (ADS)

    Bastien, Fabienne

    2015-04-01

    As a result of the high precision and cadence of surveys like NASA's Kepler, we may now directly observe the very low-level light variations in Sun-like stars. In my dissertation, I found that some of these variations unexpectedly arise from granulation, a result that enables us to more accurately determine the physical properties of Sun-like stars, permits us to understand the nature of surface convection and its connection to activity, and allows us to better determine the properties of planets around Sun-like stars. I find that granulation manifests through light ``flicker,'' thereby yielding a simple measurement of stellar surface gravity with a precision of 0.1 dex. I use this, together and solely with two other simple ways of characterizing the stellar photometric variations in a high quality light curve, to construct an evolutionary diagram for Sun-like stars from the main-sequence on towards the red giant branch. I use flicker to re-determine the fundamental properties of Kepler planet host stars, finding that the stars - and hence the planets orbiting them - are 20-30% larger than previous estimates. Finally, I show that high precision light curves can yield remarkably clean predictors of radial velocity (RV) jitter in magnetically inactive stars, allowing the exoplanet community to prioritize RV follow-up campaigns with discovery light curves and providing insight into the primary physical drivers of RV jitter in such stars.

  4. Accurate permittivity measurements for microwave imaging via ultra-wideband removal of spurious reflectors.

    PubMed

    Pelletier, Mathew G; Viera, Joseph A; Wanjura, John; Holt, Greg

    2010-01-01

    The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties. PMID:22163668

  5. Accurate Permittivity Measurements for Microwave Imaging via Ultra-Wideband Removal of Spurious Reflectors

    PubMed Central

    Pelletier, Mathew G.; Viera, Joseph A.; Wanjura, John; Holt, Greg

    2010-01-01

    The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties. PMID:22163668

  6. An improved method for accurate and rapid measurement of flight performance in Drosophila.

    PubMed

    Babcock, Daniel T; Ganetzky, Barry

    2014-01-01

    Drosophila has proven to be a useful model system for analysis of behavior, including flight. The initial flight tester involved dropping flies into an oil-coated graduated cylinder; landing height provided a measure of flight performance by assessing how far flies will fall before producing enough thrust to make contact with the wall of the cylinder. Here we describe an updated version of the flight tester with four major improvements. First, we added a "drop tube" to ensure that all flies enter the flight cylinder at a similar velocity between trials, eliminating variability between users. Second, we replaced the oil coating with removable plastic sheets coated in Tangle-Trap, an adhesive designed to capture live insects. Third, we use a longer cylinder to enable more accurate discrimination of flight ability. Fourth we use a digital camera and imaging software to automate the scoring of flight performance. These improvements allow for the rapid, quantitative assessment of flight behavior, useful for large datasets and large-scale genetic screens. PMID:24561810

  7. Produced water toxicity tests accurately measure the produced water toxicity in marine environments?

    SciTech Connect

    Douglas, W.S.; Veil, J.A.

    1996-10-01

    U.S. Environmental Protection Agency (EPA) Region VI has issued a general permit for offshore oil and gas discharges to the Gulf of Mexico that places numerical limits on whole effluent toxicity (WEI) for produced water. Recently proposed EPA general permits for other produced water discharges in Regions VI and X also include enforceable numerical limits on WET. Clearly, the industry will be conducting extensive produced water WET testing. Unfortunately, the WET test may not accurately measure the toxicity of the chemical constituents of produced water. Rather the mortality of test organisms may be attributable to (1) the high salinity of produced water, which causes salinity shock to the organisms, or (2) an ionic imbalance caused by excesses or deficiencies of one or more of seawater`s essential ions in the test chambers. Both of these effects are likely to be mitigated in actual offshore discharge settings, where the receiving water will be seawater and substantial dilution will be probable. Thus, the additional salinity of produced water will be rapidly assimilated, and the proper marine ionic balance will be quickly restored. Regulatory authorities should be aware of these factors when interpreting WET test results.

  8. The accuracy of breast volume measurement methods: A systematic review.

    PubMed

    Choppin, S B; Wheat, J S; Gee, M; Goyal, A

    2016-08-01

    Breast volume is a key metric in breast surgery and there are a number of different methods which measure it. However, a lack of knowledge regarding a method's accuracy and comparability has made it difficult to establish a clinical standard. We have performed a systematic review of the literature to examine the various techniques for measurement of breast volume and to assess their accuracy and usefulness in clinical practice. Each of the fifteen studies we identified had more than ten live participants and assessed volume measurement accuracy using a gold-standard based on the volume, or mass, of a mastectomy specimen. Many of the studies from this review report large (>200 ml) uncertainty in breast volume and many fail to assess measurement accuracy using appropriate statistical tools. Of the methods assessed, MRI scanning consistently demonstrated the highest accuracy with three studies reporting errors lower than 10% for small (250 ml), medium (500 ml) and large (1000 ml) breasts. However, as a high-cost, non-routine assessment other methods may be more appropriate. PMID:27288864

  9. MELIFT - A new device for accurate measurements in a snow rich environment

    NASA Astrophysics Data System (ADS)

    Dorninger, M.

    2012-04-01

    A deep snow pack, remote locations, no external power supply and very low temperatures are often the main ingredients when it comes to the deployment of meteorological stations in mountainous terrain. The accurate position of the sensor related to the snow surface is normally not known. A new device called METLIFT overcomes the problems. WMO recommends a height between 1.2 m and 2 m above ground level for the measurement of air temperature and humidity. The height above ground level is specified to take care of the possible strong vertical temperature and humidity gradients at the lowest layers in the atmosphere. Especially in snow rich and remote locations it may be hardly possible to follow this advice. Therefore most of the meteorological stations in mountainous terrain are situated at mountain tops where strong winds will blow off the snow or in valleys where a daily inspection of the sensors is possible. In other unpopulated mountainous areas, e.g. basins, plateaus, the distance of the sensor to the snow surface is not known or the sensor will be snow-covered. A new device was developed to guarantee the sensor height above surface within the WMO limits in harsh and remote environments. An ultrasonic snow height sensor measures the distance to the snow surface. If it exceeds certain limits due to snow accumulation or snow melt the lift adapts its height accordingly. The prototype of METLIFT has been installed in Lower Austria at an altitude of 1000m. The lift is 6 m high and can pull out for another 4 m. Sensor arms are mounted every meter to allow the connection of additional sensors or to measure a profile of a certain parameter of the lowest 5 m above surface. Sensors can be added easily since cable wiring is provided to each sensor arm. Horizontal winds are measured at 7 m height above surface. METLIFT is independent of external power supply. Three lead gel accumulators recharged by three solar panels provide the energy necessary for the sensors, the data

  10. POVME: An Algorithm for Measuring Binding-Pocket Volumes

    PubMed Central

    Durrant, Jacob D.; de Oliveira, César Augusto F.; McCammon, J. Andrew

    2011-01-01

    Researchers engaged in computer-aided drug design often wish to measure the volume of a ligand-binding pocket in order to predict pharmacology. We have recently developed a simple algorithm, called POVME (POcket Volume MEasurer), for this purpose. POVME is Python implemented, fast, and freely available. To demonstrate its utility, we use the new algorithm to study three members of the matrix-metalloproteinase family of proteins. Despite the structural similarity of these proteins, differences in binding-pocket dynamics are easily identified. PMID:21147010

  11. Near-infrared hyperspectral unmixing based on a minimum volume criterion for fast and accurate chemometric characterization of counterfeit tablets.

    PubMed

    Lopes, Marta B; Wolff, Jean-Claude; Bioucas-Dias, José M; Figueiredo, Mário A T

    2010-02-15

    A rapid detection of the nonauthenticity of suspect tablets is a key first step in the fight against pharmaceutical counterfeiting. The chemical characterization of these tablets is the logical next step to evaluate their impact on patient health and help authorities in tracking their source. Hyperspectral unmixing of near-infrared (NIR) image data is an emerging effective technology to infer the number of compounds, their spectral signatures, and the mixing fractions in a given tablet, with a resolution of a few tens of micrometers. In a linear mixing scenario, hyperspectral vectors belong to a simplex whose vertices correspond to the spectra of the compounds present in the sample. SISAL (simplex identification via split augmented Lagrangian), MVSA (minimum volume simplex analysis), and MVES (minimum-volume enclosing simplex) are recent algorithms designed to identify the vertices of the minimum volume simplex containing the spectral vectors and the mixing fractions at each pixel (vector). This work demonstrates the usefulness of these techniques, based on minimum volume criteria, for unmixing NIR hyperspectral data of tablets. The experiments herein reported show that SISAL/MVSA and MVES largely outperform MCR-ALS (multivariate curve resolution-alternating least-squares), which is considered the state-of-the-art in spectral unmixing for analytical chemistry. These experiments are based on synthetic data (studying the effect of noise and the presence/absence of pure pixels) and on a real data set composed of NIR images of counterfeit tablets. PMID:20095581

  12. Utilising Geological Field Measurements and Historic Eruption Volumes to Estimate the Volume of Santorini's Magma Chamber

    NASA Astrophysics Data System (ADS)

    Browning, J.; Drymoni, K.; Gudmundsson, A.

    2015-12-01

    An understanding of the amount of magma available to supply any given eruption is useful for determining the potential eruption magnitude and duration. Geodetic measurements and inversion techniques are often used to constrain volume changes within magma chambers, as well as constrain location and depth, but such models are incapable of calculating total magma storage. For example, during the 2012 unrest period at Santorini volcano, approximately 0.021 km3 of new magma entered a shallow chamber residing at around 4 km below the surface. This type of event is not unusual, and is in fact a necessary condition for the formation of a long-lived shallow chamber, of which Santorini must possess. The period of unrest ended without culminating in eruption, i.e the amount of magma which entered the chamber was insufficient to break the chamber and force magma further towards the surface. We combine previously published data on the volume of recent eruptions at Santorini together with geodetic measurements. Measurements of dykes within the caldera wall provide an estimate of the volume of magma transported during eruptions, assuming the dyke does not become arrested. When the combined volume of a dyke and eruption are known (Ve) they can be used to estimate using fracture mechanics principles and poro-elastic constraints the size of an underlying shallow magma chamber. We present field measurements of dykes within Santorini caldera and provide an analytical method to estimate the volume of magma contained underneath Santorini caldera. In addition we postulate the potential volume of magma required as input from deeper sources to switch the shallow magma chamber from an equilibrium setting to one where the pressure inside the chamber exceeds the surrounding host rocks tensile strength, a condition necessary to form a dyke and a possible eruption.

  13. Volume-controlled hydrologic property measurements in triaxial systems

    USGS Publications Warehouse

    Olsen, Harold W.; Willden, Arthur T.; Kiusalaas, Nicholas J.; Nelson, Karl R.; Poeter, Eileen P.

    1994-01-01

    New capabilities for hydrologic property measurements in triaxial systems include: (1) volume-controlled and simultaneous measurements of hydraulic conductivity and one-dimensional consolidation (or specific storage) of a saturated test specimen; and (2) volume-controlled measurements of hydraulic conductivity, matric potential, and the variation of these properties with the moisture content of an unsaturated test specimen. Data on saturated kaolinite demonstrate simultaneous hydraulic-conductivity and one-dimensional consolidation tests with continuous monitoring of both vertical and horizontal effective stresses. Data on well-graded silty sand demonstrate the feasibility of concurrent constant-flow hydraulic conductivity and mattic potential measurements, and the variation of these properties with moisture content, for undisturbed and unsaturated specimens mounted in triaxial cells. Refinements needed to realize the full potential of these capabilities include a more rigid triaxial cell to minimize compliance, and an improved technique for measuring hydraulic-head differences within an unsaturated test specimen.

  14. Stroke Volume estimation using aortic pressure measurements and aortic cross sectional area: Proof of concept.

    PubMed

    Kamoi, S; Pretty, C G; Chiew, Y S; Pironet, A; Davidson, S; Desaive, T; Shaw, G M; Chase, J G

    2015-08-01

    Accurate Stroke Volume (SV) monitoring is essential for patient with cardiovascular dysfunction patients. However, direct SV measurements are not clinically feasible due to the highly invasive nature of measurement devices. Current devices for indirect monitoring of SV are shown to be inaccurate during sudden hemodynamic changes. This paper presents a novel SV estimation using readily available aortic pressure measurements and aortic cross sectional area, using data from a porcine experiment where medical interventions such as fluid replacement, dobutamine infusions, and recruitment maneuvers induced SV changes in a pig with circulatory shock. Measurement of left ventricular volume, proximal aortic pressure, and descending aortic pressure waveforms were made simultaneously during the experiment. From measured data, proximal aortic pressure was separated into reservoir and excess pressures. Beat-to-beat aortic characteristic impedance values were calculated using both aortic pressure measurements and an estimate of the aortic cross sectional area. SV was estimated using the calculated aortic characteristic impedance and excess component of the proximal aorta. The median difference between directly measured SV and estimated SV was -1.4ml with 95% limit of agreement +/- 6.6ml. This method demonstrates that SV can be accurately captured beat-to-beat during sudden changes in hemodynamic state. This novel SV estimation could enable improved cardiac and circulatory treatment in the critical care environment by titrating treatment to the effect on SV. PMID:26736434

  15. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... volumes and liquid hydrocarbon burning volumes, and what records must I maintain? 250.1163 Section 250... Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and what records must I maintain? (a)...

  16. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... volumes and liquid hydrocarbon burning volumes, and what records must I maintain? 250.1163 Section 250..., and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and what records must I maintain? (a) If your facility processes more than...

  17. A new direct absorption measurement for high precision and accurate measurement of water vapor in the UT/LS

    NASA Astrophysics Data System (ADS)

    Sargent, M. R.; Sayres, D. S.; Smith, J. B.; Anderson, J.

    2011-12-01

    Highly accurate and precise water vapor measurements in the upper troposphere and lower stratosphere are critical to understanding the climate feedbacks of water vapor and clouds in that region. However, the continued disagreement among water vapor measurements (~1 - 2 ppmv) are too large to constrain the role of different hydration and dehydration mechanisms operating in the UT/LS, with model validation dependent upon which dataset is chosen. In response to these issues, we present a new instrument for measurement of water vapor in the UT/LS that was flown during the April 2011 MACPEX mission out of Houston, TX. The dual axis instrument combines the heritage and validated accuracy of the Harvard Lyman-alpha instrument with a newly designed direct IR absorption instrument, the Harvard Herriott Hygrometer (HHH). The Lyman-alpha detection axis has flown aboard NASA's WB-57 and ER2 aircraft since 1994, and provides a requisite link between the new HHH instrument and the long history of Harvard water vapor measurements. The instrument utilizes the highly sensitive Lyman-alpha photo-fragment fluorescence detection method; its accuracy has been demonstrated though rigorous laboratory calibrations and in situ diagnostic procedures. The Harvard Herriott Hygrometer employs a fiber coupled near-IR laser with state-of-the-art electronics to measure water vapor via direct absorption in a spherical Herriott cell of 10 cm length. The instrument demonstrated in-flight precision of 0.1 ppmv (1-sec, 1-sigma) at mixing ratios as low as 5 ppmv with accuracies of 10% based on careful laboratory calibrations and in-flight performance. We present a description of the measurement technique along with our methodology for calibration and details of the measurement uncertainties. The simultaneous utilization of radically different measurement techniques in a single duct in the new Harvard Water Vapor (HWV) instrument allows for the constraint of systematic errors inherent in each technique

  18. Digital fringe projection system for large-volume 360-deg shape measurement

    NASA Astrophysics Data System (ADS)

    Sitnik, Robert; Kujawinska, Malgorzata; Woznicki, Jerzy M.

    2002-02-01

    We present a system for 3-D shape measurement in large volumes based on combined digital-fringe--Gray-code projection. With the help of a new calibration procedure, the system provides accurate results despite its crossed-axis configuration and unknown aberrations of the digital light projector and CCD camera. Also, the separate clouds of points captured from different directions are automatically merged into the main cloud. The system delivers results in the form of (x,y,z) coordinates of the object points with additional (R,G,B) color information about their texture. Applicability of the system is proven by presenting sample results of measurements performed on complex objects. The uncertainty of the system was estimated at 10 -4 of the measurement volume.

  19. Designing Beam Steering for Accurate Measurement of Intima-Media Thickness at Carotid Sinus

    NASA Astrophysics Data System (ADS)

    Mashiyama, Takashi; Hasegawa, Hideyuki; Kanai, Hiroshi

    2006-05-01

    Recently, cardiovascular disease has become the second most common cause of death in Japan following malignant neoplasm formation. Therefore, it is necessary to diagnose atherosclerosis during its early stages because atherosclerosis is one of the main causes of cardiovascular diseases. The carotid sinus is a site that is easily affected by atherosclerosis [C. K. Zarins et al.: Circ. Res. 53 (1983) 502]; therefore, the diagnosis of this disease at this site is important [S. C. Nicholls et al.: Stroke 20 (1989) 175]. However, it is difficult to accurately diagnose atherosclerosis in the carotid sinus in the long-axis plane, which is parallel to the axis of the vessel, using conventional linear scanning because the carotid sinus is not flat along the axis of the vessel, and the ultrasonic beams used in linear scanning are perpendicular to the arterial wall in a limited region. Echoes from regions that are not perpendicular to the ultrasonic beams are very weak and the arterial wall in such regions is hardly recognized in a B-mode image. In this study, the position of the arterial wall was predetermined on the basis of the B-mode image obtained by conventional linear scanning, then ultrasonic beams were transmitted again so that all beams were almost perpendicular to the arterial wall. In basic experiments, a nonflat object made of silicone rubber was measured and it was shown that it is possible to image a nonflat object over the entire scanned area using the proposed beam steering method. Furthermore, in in vivo experiments, the intima-media complex was imaged over the entire scanned area at the carotid sinus.

  20. Quantitative radiology: automated measurement of polyp volume in computed tomography colonography using Hessian matrix-based shape extraction and volume growing

    PubMed Central

    Epstein, Mark L.; Obara, Piotr R.; Chen, Yisong; Liu, Junchi; Zarshenas, Amin; Makkinejad, Nazanin; Dachman, Abraham H.

    2015-01-01

    Background Current measurement of the single longest dimension of a polyp is subjective and has variations among radiologists. Our purpose was to develop a computerized measurement of polyp volume in computed tomography colonography (CTC). Methods We developed a 3D automated scheme for measuring polyp volume at CTC. Our scheme consisted of segmentation of colon wall to confine polyp segmentation to the colon wall, extraction of a highly polyp-like seed region based on the Hessian matrix, a 3D volume growing technique under the minimum surface expansion criterion for segmentation of polyps, and sub-voxel refinement and surface smoothing for obtaining a smooth polyp surface. Our database consisted of 30 polyp views (15 polyps) in CTC scans from 13 patients. Each patient was scanned in the supine and prone positions. Polyp sizes measured in optical colonoscopy (OC) ranged from 6-18 mm with a mean of 10 mm. A radiologist outlined polyps in each slice and calculated volumes by summation of volumes in each slice. The measurement study was repeated 3 times at least 1 week apart for minimizing a memory effect bias. We used the mean volume of the three studies as “gold standard”. Results Our measurement scheme yielded a mean polyp volume of 0.38 cc (range, 0.15-1.24 cc), whereas a mean “gold standard” manual volume was 0.40 cc (range, 0.15-1.08 cc). The “gold-standard” manual and computer volumetric reached excellent agreement (intra-class correlation coefficient =0.80), with no statistically significant difference [P (F≤f) =0.42]. Conclusions We developed an automated scheme for measuring polyp volume at CTC based on Hessian matrix-based shape extraction and volume growing. Polyp volumes obtained by our automated scheme agreed excellently with “gold standard” manual volumes. Our fully automated scheme can efficiently provide accurate polyp volumes for radiologists; thus, it would help radiologists improve the accuracy and efficiency of polyp volume

  1. Time-accurate analysis of nonequilibrium gas-particle mixtures using upwind/implicit finite-volume methodology

    SciTech Connect

    Hosangadi, A.; Sinha, N.; Dash, S.M. )

    1992-01-01

    A new Eulerian particulate solver whose numerical formulation is compatible with the numerics in state-of-the-art finite-volume upwind/implicit gas dynamic computer codes is presented. The heat transfer, drag, thermodynamic, and phase-change procedures in this code are derived from earlier, well established data fits and procedures. Performance for numerous flow problems with one- and two-way coupling is quite good. The solutions are nonoscillatory and robust and conserve flux balances very well. 18 refs.

  2. Bioimpedance Measurement of Segmental Fluid Volumes and Hemodynamics

    NASA Technical Reports Server (NTRS)

    Montgomery, Leslie D.; Wu, Yi-Chang; Ku, Yu-Tsuan E.; Gerth, Wayne A.; DeVincenzi, D. (Technical Monitor)

    2000-01-01

    Bioimpedance has become a useful tool to measure changes in body fluid compartment volumes. An Electrical Impedance Spectroscopic (EIS) system is described that extends the capabilities of conventional fixed frequency impedance plethysmographic (IPG) methods to allow examination of the redistribution of fluids between the intracellular and extracellular compartments of body segments. The combination of EIS and IPG techniques was evaluated in the human calf, thigh, and torso segments of eight healthy men during 90 minutes of six degree head-down tilt (HDT). After 90 minutes HDT the calf and thigh segments significantly (P < 0.05) lost conductive volume (eight and four percent, respectively) while the torso significantly (P < 0.05) gained volume (approximately three percent). Hemodynamic responses calculated from pulsatile IPG data also showed a segmental pattern consistent with vascular fluid loss from the lower extremities and vascular engorgement in the torso. Lumped-parameter equivalent circuit analyses of EIS data for the calf and thigh indicated that the overall volume decreases in these segments arose from reduced extracellular volume that was not completely balanced by increased intracellular volume. The combined use of IPG and EIS techniques enables noninvasive tracking of multi-segment volumetric and hemodynamic responses to environmental and physiological stresses.

  3. A coupled phase-field and volume-of-fluid method for accurate representation of limiting water wave deformation

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Yu, Xiping

    2016-09-01

    A coupled phase-field and volume-of-fluid method is developed to study the sensitive behavior of water waves during breaking. The THINC model is employed to solve the volume-of-fluid function over the entire domain covered by a relatively coarse grid while the phase-field model based on Allen-Cahn equation is applied over the fine grid. A special algorithm that takes into account the sharpness of the diffuse-interface is introduced to correlate the order parameter obtained on the fine grid and the volume-of-fluid function obtained on the coarse grid. The coupled model is then applied to the study of water waves generated by moving pressures on the free surface. The deformation process of the wave crest during the initial stage of breaking is discussed in details. It is shown that there is a significant variation of the free nappe developed at the front side of the wave crest as the wave steepness differs. It is of a plunging type at large wave steepness while of a spilling type at small wave steepness. The numerical results also indicate that breaking occurs later and the duration of breaking is shorter for waves of smaller steepness and vice versa. Neglecting the capillary effect leads to wave breaking with a sharper nappe and a more dynamic plunging process. The surface tension also has an effect to prevent the formation of a free nappe at the front side of the wave crest in some cases.

  4. Short communication: Measuring feed volume and weight by machine vision.

    PubMed

    Shelley, A N; Lau, D L; Stone, A E; Bewley, J M

    2016-01-01

    Individual dairy cow feed intake is closely related to the health and productive output of each cow, with healthy cows generally eating more feed than unhealthy cows. Incorporating the use of an automated system to monitor feed consumption for each cow may be beneficial for dairy farm management. This study examined the use of an inexpensive 3-dimensional video camera to measure feed volume, from which we derived feed weight. Proof-of-concept testing was conducted to determine the effectiveness and capability of the machine vision feed-scanning system and its possible use in feed intake monitoring. Such systems are ideal because they do not impede the workflow of the farm or interrupt feeding behavior. This is an improvement over existing systems that are labor and cost intensive. Our conducted experiments involve measuring feed volume at known weights, up to 22.68 kg, with the resulting volume and weight values analyzed by means of linear and quadratic least squares t-test regression analysis. The effects of feed positioning in the bin and near-range sensor limitations were also examined. The results showed that an estimation of feed weight from 3-dimensional scan of volume measurements could be made to within 0.5 kg of the physically measured feed weight using a digital scale. Future efforts will focus on extending this work to active bunks with multiple cows eating throughout the day and testing total mixed rations of varied composition. PMID:26547642

  5. Measuring the intrarenal distribution of glomerular volumes from histological sections.

    PubMed

    Hann, Bradley D; Baldelomar, Edwin J; Charlton, Jennifer R; Bennett, Kevin M

    2016-06-01

    Glomerular volume is an important metric reflecting glomerular filtration surface area within the kidney. Glomerular hypertrophy, or increased glomerular volume, may be an important marker for renal stress. Current stereological techniques report the average glomerular volume (AVglom) within the kidney. These techniques cannot assess the spatial or regional heterogeneity common in developing renal pathology. Here, we report a novel "unfolding" technique to measure the actual distribution of individual glomerular volumes in a kidney from the two-dimensional glomerulus profiles observed by optical microscopy. The unfolding technique was first developed and tested for accuracy with simulations and then applied to measure the number of glomeruli (Nglom), AVglom, and intrarenal distribution of individual glomerular volume (IVglom) in the oligosyndactyl (Os/(+)) mouse model compared with wild-type (WT) controls. The Os/(+) mice had fewer and larger glomeruli than WT mice: Nglom was 12,126 ± 1,658 (glomeruli/kidney) in the WT mice and 5,516 ± 899 in the Os/(+) mice; AVglom was 2.01 ± 0.28 × 10(-4) mm(3) for the WT mice and 3.47 ± 0.35 × 10(-4) mm(3) for the Os/(+) mice. Comparing the glomerular volume distributions in Os/(+) and WT kidneys, we observed that the Os/(+) distribution peaked at a higher value of IVglom than the WT distribution peak, and glomeruli with a radius greater than 55 μm were more prevalent in the Os/(+) mice (3.4 ± 1.6% of total glomeruli vs. 0.6 ± 1.2% in WT). Finally, the largest profiles were more commonly found in the juxtamedullary region. Unfolding is a novel stereological technique that provides a new quantitative view of glomerular volume distribution in the individual kidney. PMID:26984953

  6. Two dimensional LDA using volume measure in face recognition

    NASA Astrophysics Data System (ADS)

    Meng, Jicheng; Feng, Li; Zheng, Xiaolong

    2007-11-01

    The classification criterion for the two dimensional LDA (2DLDA)-based face recognition methods has been little considered, while we almost pay all attention to the 2DLDA-based feature extraction. The typical classification measure used in 2DLDA-based face recognition is the sum of the Euclidean distance between two feature vectors in feature matrix, called traditional distance measure (TDM). However, this classification criterion does not match the high dimensional geometry space theory. So we apply the volume measure (VM), which is based on the high dimensional geometry theory, to the 2DLDA-based face recognition in this paper. To test its performance, experiments were performed on the YALE face databases. The experimental results show the volume measure (VM) is more efficient than the TDM in 2DLDA-based face recognition.

  7. Measurement of the pressure-volume curve in mouse lungs.

    PubMed

    Limjunyawong, Nathachit; Fallica, Jonathan; Horton, Maureen R; Mitzner, Wayne

    2015-01-01

    In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential phenotypic changes are best assessed by measurement of the changes in lung elasticity. To best understand specific mechanisms underlying such pathologies in mice, it is essential to make functional measurements that can reflect the developing pathology. Although there are many ways to measure elasticity, the classical method is that of the total lung pressure-volume (PV) curve done over the whole range of lung volumes. This measurement has been made on adult lungs from nearly all mammalian species dating back almost 100 years, and such PV curves also played a major role in the discovery and understanding of the function of pulmonary surfactant in fetal lung development. Unfortunately, such total PV curves have not been widely reported in the mouse, despite the fact that they can provide useful information on the macroscopic effects of structural changes in the lung. Although partial PV curves measuring just the changes in lung volume are sometimes reported, without a measure of absolute volume, the nonlinear nature of the total PV curve makes these partial ones very difficult to interpret. In the present study, we describe a standardized way to measure the total PV curve. We have then tested the ability of these curves to detect changes in mouse lung structure in two common lung pathologies, emphysema and fibrosis. Results showed significant changes in several variables consistent with expected structural changes with these pathologies. This measurement of the lung PV curve in mice thus provides a straightforward means to monitor the progression of the pathophysiologic changes over time and the potential effect of therapeutic procedures. PMID:25651276

  8. A small volume thermodynamic system for B/A measurement.

    PubMed

    Zhang, J; Dunn, F

    1991-01-01

    A thermodynamic method capable of determining the B/A value of 4-ml sample volumes is described. The method involves a procedure in which the static pressure of the sample is altered in a short period of time, to approximate an adiabatic process, during which the ultrasonic velocity is measured. The velocity change so determined is used to calculate the B/A value. The B/A measurement error is less than 0.7%. PMID:1825834

  9. Measurement of the Pressure-volume Curve in Mouse Lungs

    PubMed Central

    Limjunyawong, Nathachit; Fallica, Jonathan; Horton, Maureen R.; Mitzner, Wayne

    2015-01-01

    In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential phenotypic changes are best assessed by measurement of the changes in lung elasticity. To best understand specific mechanisms underlying such pathologies in mice, it is essential to make functional measurements that can reflect the developing pathology. Although there are many ways to measure elasticity, the classical method is that of the total lung pressure-volume (PV) curve done over the whole range of lung volumes. This measurement has been made on adult lungs from nearly all mammalian species dating back almost 100 years, and such PV curves also played a major role in the discovery and understanding of the function of pulmonary surfactant in fetal lung development. Unfortunately, such total PV curves have not been widely reported in the mouse, despite the fact that they can provide useful information on the macroscopic effects of structural changes in the lung. Although partial PV curves measuring just the changes in lung volume are sometimes reported, without a measure of absolute volume, the nonlinear nature of the total PV curve makes these partial ones very difficult to interpret. In the present study, we describe a standardized way to measure the total PV curve. We have then tested the ability of these curves to detect changes in mouse lung structure in two common lung pathologies, emphysema and fibrosis. Results showed significant changes in several variables consistent with expected structural changes with these pathologies. This measurement of the lung PV curve in mice thus provides a straightforward means to monitor the progression of the pathophysiologic changes over time and the potential effect of therapeutic procedures. PMID:25651276

  10. A method of measuring a molten metal liquid pool volume

    DOEpatents

    Garcia, G.V.; Carlson, N.M., Donaldson, A.D.

    1990-12-12

    A method of measuring a molten metal liquid pool volume and in particular molten titanium liquid pools, including the steps of (a) generating an ultrasonic wave at the surface of the molten metal liquid pool, (b) shining a light on the surface of a molten metal liquid pool, (c) detecting a change in the frequency of light, (d) detecting an ultrasonic wave echo at the surface of the molten metal liquid pool, and (e) computing the volume of the molten metal liquid. 3 figs.

  11. High resolution as a key feature to perform accurate ELISPOT measurements using Zeiss KS ELISPOT readers.

    PubMed

    Malkusch, Wolf

    2005-01-01

    The enzyme-linked immunospot (ELISPOT) assay was originally developed for the detection of individual antibody secreting B-cells. Since then, the method has been improved, and ELISPOT is used for the determination of the production of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, or various interleukins (IL)-4, IL-5. ELISPOT measurements are performed in 96-well plates with nitrocellulose membranes either visually or by means of image analysis. Image analysis offers various procedures to overcome variable background intensity problems and separate true from false spots. ELISPOT readers offer a complete solution for precise and automatic evaluation of ELISPOT assays. Number, size, and intensity of each single spot can be determined, printed, or saved for further statistical evaluation. Cytokine spots are always round, but because of floating edges with the background, they have a nonsmooth borderline. Resolution is a key feature for a precise detection of ELISPOT. In standard applications shape and edge steepness are essential parameters in addition to size and color for an accurate spot recognition. These parameters need a minimum spot diameter of 6 pixels. Collecting one single image per well with a standard color camera with 750 x 560 pixels will result in a resolution much too low to get all of the spots in a specimen. IFN-gamma spots may have only 25 microm diameters, and TNF-alpha spots just 15 microm. A 750 x 560 pixel image of a 6-mm well has a pixel size of 12 microm, resulting in only 1 or 2 pixel for a spot. Using a precise microscope optic in combination with a high resolution (1300 x 1030 pixel) integrating digital color camera, and at least 2 x 2 images per well will result in a pixel size of 2.5 microm and, as a minimum, 6 pixel diameter per spot. New approaches try to detect two cytokines per cell at the same time (i.e., IFN-gamma and IL-5). Standard staining procedures produce brownish spots (horseradish peroxidase) and blue spots

  12. Which is More Accurate in Measuring the Blood Pressure? A Digital or an Aneroid Sphygmomanometer

    PubMed Central

    Dasgupta, Aparajita; Sarkar, Kaushik; Sahoo, Sanjaya Kumar

    2016-01-01

    Introduction Hypertension is one of the major public health problem affecting the whole world so its accurate measurement is of utmost importance for its early diagnosis and management. Concerns related to the potential ill effects of mercury on health and environment, has led to the widespread use of non-mercury sphygmomanometers. Aim A study was conducted to compare the accuracy of readings of aneroid and digital sphygmomanometers in reference to mercury sphygmomanometers and determine the hypertensive classification agreement between the mercury and non-mercury devices. Materials and Methods The study was conducted in an OPD of a health centre in a rural community of West Bengal which is the rural field practice area of our institute. An aneroid and a digital sphygmomanometer were compared to a properly calibrated mercury sphygmomanometer. All the subjects above the age of 25 years, in two days per week, selected randomly from five working days per week in a period of one month were selected. Two blood pressure readings of each of 218 study subjects was recorded with each pretested sphygmomanometer. Paired t-test, Kappa coefficients, sensitivity and specificity tests were done. Receiver Operating Characteristics curve analysis was done and Youden index was estimated to detect the optimal cut off point for the diagnosis of hypertension by non-mercury sphygmomanometers. Results Data analysis of 218 study subjects showed the mean difference of the mercury reading and the test device was much less for aneroid than that of the digital device for both systolic and diastolic blood pressure. More than 89% of aneroid readings and less than 44% of the readings by digital device had absolute difference of 5mm Hg. when compared with the mercury readings for both systolic and diastolic blood pressure. Sensitivity and specificity of aneroid device was higher (86.7% and 98.7%) than digital device (80% and 67.7%). Receiver Operating Characteristic curve had larger area under

  13. Anterior chamber volume. Its measurement and clinical application.

    PubMed

    Coakes, R L; Lloyd-Jones, D; Hitchings, R A

    1979-04-01

    Measurement of anterior chamber volume is discussed and attention drawn to a new, convenient slit-image method, which was used to study anterior chamber depth and volume before and after prophylactic peripheral iridectomy in the fellow eyes of patients presenting with unilateral acute angle-closure glaucoma. There was no significant change in depth after iridectomy but the mean anterior chamber volume increased significantly (P less than 0.01), by nearly 3 per cent. This increase was due to elimination of peripheral iris bombé which was not present in two control groups of normal eyes, one matched for anterior chamber depth and the other for age and refraction. Peripheral iris bombé may be a quantifiable factor predisposing to the development of acute angle-closure glaucoma. PMID:297385

  14. Dynamic measures of regional lung air volume using phase contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kitchen, M. J.; Lewis, R. A.; Morgan, M. J.; Wallace, M. J.; Siew, M. L.; Siu, K. K. W.; Habib, A.; Fouras, A.; Yagi, N.; Uesugi, K.; Hooper, S. B.

    2008-11-01

    Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 µm) in near real time. Changes in lung air volume as small as 25 µL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.

  15. Accurate extraction of mobility in carbon nanotube network transistors using C-V and I-V measurements

    NASA Astrophysics Data System (ADS)

    Yoon, Jinsu; Lee, Dongil; Kim, Chaewon; Lee, Jieun; Choi, Bongsik; Kim, Dong Myong; Kim, Dae Hwan; Lee, Mijung; Choi, Yang-Kyu; Choi, Sung-Jin

    2014-11-01

    The mobility of single-walled carbon nanotube (SWNT) network thin-film transistors (TFTs) is an essential parameter. Previous extraction methods for mobility encountered problems in extracting accurate intrinsic mobility due to the uncertainty of the SWNT density in the network channel and the existence of contact resistance at the source/drain electrodes. As a result, efficient and accurate extraction of the mobility in SWNT TFTs is challenging using previous methods. We propose a direct method of extracting accurate intrinsic mobility in SWNT TFTs by employing capacitance-voltage and current-voltage measurements. Consequently, we simply obtain accurate intrinsic mobility within the ink-jet printed SWNT TFTs without any complicated calculations.

  16. Sampling artifact in volume weighted velocity measurement. I. Theoretical modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie; Zheng, Yi; Jing, Yipeng

    2015-02-01

    Cosmology based on large scale peculiar velocity prefers volume weighted velocity statistics. However, measuring the volume weighted velocity statistics from inhomogeneously distributed galaxies (simulation particles/halos) suffers from an inevitable and significant sampling artifact. We study this sampling artifact in the velocity power spectrum measured by the nearest particle velocity assignment method by Zheng et al., [Phys. Rev. D 88, 103510 (2013).]. We derive the analytical expression of leading and higher order terms. We find that the sampling artifact suppresses the z =0 E -mode velocity power spectrum by ˜10 % at k =0.1 h /Mpc , for samples with number density 10-3 (Mpc /h )-3 . This suppression becomes larger for larger k and for sparser samples. We argue that this source of systematic errors in peculiar velocity cosmology, albeit severe, can be self-calibrated in the framework of our theoretical modelling. We also work out the sampling artifact in the density-velocity cross power spectrum measurement. A more robust evaluation of related statistics through simulations will be presented in a companion paper by Zheng et al., [Sampling artifact in volume weighted velocity measurement. II. Detection in simulations and comparison with theoretical modelling, arXiv:1409.6809.]. We also argue that similar sampling artifact exists in other velocity assignment methods and hence must be carefully corrected to avoid systematic bias in peculiar velocity cosmology.

  17. Image Settings Affecting Nuchal Translucency Measurement Using Volume NT™ Software

    PubMed Central

    Cho, Hee Young; Kim, Young Han; Park, Yong Won; Kim, Sung Yoon; Lee, Kwang Hee; Yoo, Joon Sang

    2015-01-01

    Purpose To evaluate the effects of the deviation from the mid-sagittal plane, fetal image size, tissue harmonic imaging (THI), and speckle reduction filter (SRF) on the measurement of the nuchal translucency (NT) thickness using Volume NT™ software. Materials and Methods In 79 pregnant women, NT was measured using Volume NT™. Firstly, the three-dimensional volumes were categorized based on the angle of deviation in 10° intervals from the mid-sagittal plane. Secondly, the operator downsized the fetal image to less than 50% of the screen (Method A) and by magnifying the image (Method B). Next, the image was magnified until the fetal head and thorax occupied 75% of the screen, and the NT was measured (Method C). Lastly, NT values were acquired with THI and SRF functions on, with each function alternately on, and with both functions off. Results The mean differences in NT measurements were -0.09 mm (p<0.01) between two-dimensional (2D) and a deviation of 31-40° and -0.10 mm (p<0.01) between 2D and 41-50°. The intraclass correlation coefficients (ICC) for 2D-NT and NT according to image size were 0.858, 0.923, and 0.928 for methods A, B, and C, respectively. The ICC for 2D-NT and NT with respect to the THI and SRF were 0.786, 0.761, 0.740, and 0.731 with both functions on, THI only, SRF only, and with both functions off, respectively. Conclusion NT measurements made using Volume NT™ are affected by angle deviation from the mid-sagittal plane and fetal image size. Additionally, the highest correlation with 2D-NT was achieved when THI and SRF functions were used. PMID:26256978

  18. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Urine flow or volume measuring system. 876.1800... volume measuring system. (a) Identification. A urine flow or volume measuring system is a device that measures directly or indirectly the volume or flow of urine from a patient, either during the course...

  19. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urine flow or volume measuring system. 876.1800... volume measuring system. (a) Identification. A urine flow or volume measuring system is a device that measures directly or indirectly the volume or flow of urine from a patient, either during the course...

  20. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Urine flow or volume measuring system. 876.1800... volume measuring system. (a) Identification. A urine flow or volume measuring system is a device that measures directly or indirectly the volume or flow of urine from a patient, either during the course...

  1. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Urine flow or volume measuring system. 876.1800... volume measuring system. (a) Identification. A urine flow or volume measuring system is a device that measures directly or indirectly the volume or flow of urine from a patient, either during the course...

  2. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Urine flow or volume measuring system. 876.1800... volume measuring system. (a) Identification. A urine flow or volume measuring system is a device that measures directly or indirectly the volume or flow of urine from a patient, either during the course...

  3. Use of an inertial navigation system for accurate track recovery and coastal oceanographic measurements

    NASA Technical Reports Server (NTRS)

    Oliver, B. M.; Gower, J. F. R.

    1977-01-01

    A data acquisition system using a Litton LTN-51 inertial navigation unit (INU) was tested and used for aircraft track recovery and for location and tracking from the air of targets at sea. The characteristic position drift of the INU is compensated for by sighting landmarks of accurately known position at discrete time intervals using a visual sighting system in the transparent nose of the Beechcraft 18 aircraft used. For an aircraft altitude of about 300 m, theoretical and experimental tests indicate that calculated aircraft and/or target positions obtained from the interpolated INU drift curve will be accurate to within 10 m for landmarks spaced approximately every 15 minutes in time. For applications in coastal oceanography, such as surface current mapping by tracking artificial targets, the system allows a broad area to be covered without use of high altitude photography and its attendant needs for large targets and clear weather.

  4. Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature Doppler radar sensor.

    PubMed

    Hu, Wei; Zhao, Zhangyan; Wang, Yunfeng; Zhang, Haiying; Lin, Fujiang

    2014-03-01

    The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%. PMID:24235293

  5. Accurate discrimination of Alzheimer's disease from other dementia and/or normal subjects using SPECT specific volume analysis

    NASA Astrophysics Data System (ADS)

    Iyatomi, Hitoshi; Hashimoto, Jun; Yoshii, Fumuhito; Kazama, Toshiki; Kawada, Shuichi; Imai, Yutaka

    2014-03-01

    Discrimination between Alzheimer's disease and other dementia is clinically significant, however it is often difficult. In this study, we developed classification models among Alzheimer's disease (AD), other dementia (OD) and/or normal subjects (NC) using patient factors and indices obtained by brain perfusion SPECT. SPECT is commonly used to assess cerebral blood flow (CBF) and allows the evaluation of the severity of hypoperfusion by introducing statistical parametric mapping (SPM). We investigated a total of 150 cases (50 cases each for AD, OD, and NC) from Tokai University Hospital, Japan. In each case, we obtained a total of 127 candidate parameters from: (A) 2 patient factors (age and sex), (B) 12 CBF parameters and 113 SPM parameters including (C) 3 from specific volume analysis (SVA), and (D) 110 from voxel-based analysis stereotactic extraction estimation (vbSEE). We built linear classifiers with a statistical stepwise feature selection and evaluated the performance with the leave-one-out cross validation strategy. Our classifiers achieved very high classification performances with reasonable number of selected parameters. In the most significant discrimination in clinical, namely those of AD from OD, our classifier achieved both sensitivity (SE) and specificity (SP) of 96%. In a similar way, our classifiers achieved a SE of 90% and a SP of 98% in AD from NC, as well as a SE of 88% and a SP of 86% in AD from OD and NC cases. Introducing SPM indices such as SVA and vbSEE, classification performances improved around 7-15%. We confirmed that these SPM factors are quite important for diagnosing Alzheimer's disease.

  6. Stable and accurate hybrid finite volume methods based on pure convexity arguments for hyperbolic systems of conservation law

    NASA Astrophysics Data System (ADS)

    De Vuyst, Florian

    2004-01-01

    This exploratory work tries to present first results of a novel approach for the numerical approximation of solutions of hyperbolic systems of conservation laws. The objective is to define stable and "reasonably" accurate numerical schemes while being free from any upwind process and from any computation of derivatives or mean Jacobian matrices. That means that we only want to perform flux evaluations. This would be useful for "complicated" systems like those of two-phase models where solutions of Riemann problems are hard, see impossible to compute. For Riemann or Roe-like solvers, each fluid model needs the particular computation of the Jacobian matrix of the flux and the hyperbolicity property which can be conditional for some of these models makes the matrices be not R-diagonalizable everywhere in the admissible state space. In this paper, we rather propose some numerical schemes where the stability is obtained using convexity considerations. A certain rate of accuracy is also expected. For that, we propose to build numerical hybrid fluxes that are convex combinations of the second-order Lax-Wendroff scheme flux and the first-order modified Lax-Friedrichs scheme flux with an "optimal" combination rate that ensures both minimal numerical dissipation and good accuracy. The resulting scheme is a central scheme-like method. We will also need and propose a definition of local dissipation by convexity for hyperbolic or elliptic-hyperbolic systems. This convexity argument allows us to overcome the difficulty of nonexistence of classical entropy-flux pairs for certain systems. We emphasize the systematic feature of the method which can be fastly implemented or adapted to any kind of systems, with general analytical or data-tabulated equations of state. The numerical results presented in the paper are not superior to many existing state-of-the-art numerical methods for conservation laws such as ENO, MUSCL or central scheme of Tadmor and coworkers. The interest is rather

  7. Seeking: Accurate Measurement Techniques for Deep-Bone Density and Structure

    NASA Technical Reports Server (NTRS)

    Sibonga, Jean

    2009-01-01

    We are seeking a clinically-useful technology with enough sensitivity to assess the microstructure of "spongy" bone that is found in the marrow cavities of whole bones. However, this technology must be for skeletal sites surrounded by layers of soft tissues, such as the spine and the hip. Soft tissue interferes with conventional imaging and using a more accessible area -- for example, the wrist or the ankle of limbs-- as a proxy for the less accessible skeletal regions, will not be accurate. A non-radioactive technology is strongly preferred.

  8. The role of anticoagulation in the measurement of platelet volumes.

    PubMed

    Thompson, C B; Diaz, D D; Quinn, P G; Lapins, M; Kurtz, S R; Valeri, C R

    1983-09-01

    The effect of anticoagulation on platelet size stability was studied using blood collected in seven different anticoagulants and stored at room temperature for up to eight hours. The mean platelet volume (MPV) value was most stable in blood collected in 15% ACD and ACD/Na2EDTA. In blood collected in Na2EDTA, K3EDTA, or 11.9% ACD, there was an increase in MPV in the first two hours, after which the MPVs remained stable up to eight hours. Sodium citrate and heparin proved unreliable for the measurement of platelet volume. Platelet counts were stable (less than 5% variation) in all anticoagulants except heparin, which had 16% variation for the eight hours of study. Simultaneously, RBC counts and mean corpuscular volume (MCV) measurements were stable in all seven anticoagulants, with sodium citrate producing the most variation. A negative correlation was observed between MCV and pH of the anticoagulated blood. WBC counts showed less than 3% variation in all anticoagulants except sodium citrate and heparin. Separate experiments demonstrated that electrolyte composition, pH, tonicity, and method of calcium chelation all influenced the stability of the MPV. Of the anticoagulants studied, ACD/Na2 EDTA appeared to provide the best conditions of anticoagulation for both routine clinical and research laboratory measurement of the MPV. It inhibited platelet activation but left the platelets in their normal discoid shape. Platelets could be removed from the anticoagulant and studied in functional assays for up to eight hours after blood drawing. Both platelet counts and MPVs remained stable in blood collected in ACD/Na2 EDTA anticoagulant for up to eight hours at room temperature. In 52 volunteers studied, an inverse correlation (r = -0.72, P less than 0.001) was observed between platelet count and MPV, suggesting that the circulating platelet mass may be a more important indicator of platelet homeostasis than either the platelet count or the mean platelet volume alone. PMID

  9. Highly accurate measurements of the spontaneous fission half-life of 240,242Pu

    NASA Astrophysics Data System (ADS)

    Salvador-Castiñeira, P.; Bryś, T.; Eykens, R.; Hambsch, F.-J.; Moens, A.; Oberstedt, S.; Sibbens, G.; Vanleeuw, D.; Vidali, M.; Pretel, C.

    2013-12-01

    Fast spectrum neutron-induced fission cross-section data for transuranic isotopes are of special demand from the nuclear data community. In particular highly accurate data are needed for the new generation IV nuclear applications. The aim is to obtain precise neutron-induced fission cross sections for 240Pu and 242Pu. To do so, accurate data on spontaneous fission half-lives must be available. Also, minimizing uncertainties in the detector efficiency is a key point. We studied both isotopes by means of a twin Frisch-grid ionization chamber with the goal of improving the present data on the neutron-induced fission cross section. For the two plutonium isotopes the high α-particle decay rates pose a particular problem to experiments due to piling-up events in the counting gas. Argon methane and methane were employed as counting gases, the latter showed considerable improvement in signal generation due to its higher drift velocity. The detection efficiency for both samples was determined, and improved spontaneous fission half-lives were obtained with very low statistical uncertainty (0.13% for 240Pu and 0.04% for 242Pu): for 240Pu, T1/2,SF=1.165×1011 yr (1.1%), and for 242Pu, T1/2,SF=6.74×1010 yr (1.3%). Systematic uncertainties are due to sample mass (0.4% for 240Pu and 0.9% for 242Pu) and efficiency (1%).

  10. Accurate Measurement of the Relative Abundance of Different DNA Species in Complex DNA Mixtures

    PubMed Central

    Jeong, Sangkyun; Yu, Hyunjoo; Pfeifer, Karl

    2012-01-01

    A molecular tool that can compare the abundances of different DNA sequences is necessary for comparing intergenic or interspecific gene expression. We devised and verified such a tool using a quantitative competitive polymerase chain reaction approach. For this approach, we adapted a competitor array, an artificially made plasmid DNA in which all the competitor templates for the target DNAs are arranged with a defined ratio, and melting analysis for allele quantitation for accurate quantitation of the fractional ratios of competitively amplified DNAs. Assays on two sets of DNA mixtures with explicitly known compositional structures of the test sequences were performed. The resultant average relative errors of 0.059 and 0.021 emphasize the highly accurate nature of this method. Furthermore, the method's capability of obtaining biological data is demonstrated by the fact that it can illustrate the tissue-specific quantitative expression signatures of the three housekeeping genes G6pdx, Ubc, and Rps27 by using the forms of the relative abundances of their transcripts, and the differential preferences of Igf2 enhancers for each of the multiple Igf2 promoters for the transcription. PMID:22334570

  11. Accurate radiocarbon age estimation using "early" measurements: a new approach to reconstructing the Paleolithic absolute chronology

    NASA Astrophysics Data System (ADS)

    Omori, Takayuki; Sano, Katsuhiro; Yoneda, Minoru

    2014-05-01

    This paper presents new correction approaches for "early" radiocarbon ages to reconstruct the Paleolithic absolute chronology. In order to discuss time-space distribution about the replacement of archaic humans, including Neanderthals in Europe, by the modern humans, a massive data, which covers a wide-area, would be needed. Today, some radiocarbon databases focused on the Paleolithic have been published and used for chronological studies. From a viewpoint of current analytical technology, however, the any database have unreliable results that make interpretation of radiocarbon dates difficult. Most of these unreliable ages had been published in the early days of radiocarbon analysis. In recent years, new analytical methods to determine highly-accurate dates have been developed. Ultrafiltration and ABOx-SC methods, as new sample pretreatments for bone and charcoal respectively, have attracted attention because they could remove imperceptible contaminates and derive reliable accurately ages. In order to evaluate the reliability of "early" data, we investigated the differences and variabilities of radiocarbon ages on different pretreatments, and attempted to develop correction functions for the assessment of the reliability. It can be expected that reliability of the corrected age is increased and the age applied to chronological research together with recent ages. Here, we introduce the methodological frameworks and archaeological applications.

  12. Accurate Monitoring and Fault Detection in Wind Measuring Devices through Wireless Sensor Networks

    PubMed Central

    Khan, Komal Saifullah; Tariq, Muhammad

    2014-01-01

    Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for wind energy projects (through simulated models) may vary from the actual potential of the area. Hence, introducing accurate site assessment techniques will lead to accurate predictions of energy production from a particular area. We solve this problem by installing a Wireless Sensor Network (WSN) to periodically analyze the data from anemometers installed in that area. After comparative analysis of the acquired data, the anemometers transmit their readings through a WSN to the sink node for analysis. The sink node uses an iterative algorithm which sequentially detects any faulty anemometer and passes the details of the fault to the central system or main station. We apply the proposed technique in simulation as well as in practical implementation and study its accuracy by comparing the simulation results with experimental results to analyze the variation in the results obtained from both simulation model and implemented model. Simulation results show that the algorithm indicates faulty anemometers with high accuracy and low false alarm rate when as many as 25% of the anemometers become faulty. Experimental analysis shows that anemometers incorporating this solution are better assessed and performance level of implemented projects is increased above 86% of the simulated models. PMID:25421739

  13. Shorter sampling periods and accurate estimates of milk volume and components are possible for pasture based dairy herds milked with automated milking systems.

    PubMed

    Kamphuis, Claudia; Burke, Jennie K; Taukiri, Sarah; Petch, Susan-Fay; Turner, Sally-Anne

    2016-08-01

    Dairy cows grazing pasture and milked using automated milking systems (AMS) have lower milking frequencies than indoor fed cows milked using AMS. Therefore, milk recording intervals used for herd testing indoor fed cows may not be suitable for cows on pasture based farms. We hypothesised that accurate standardised 24 h estimates could be determined for AMS herds with milk recording intervals of less than the Gold Standard (48 hs), but that the optimum milk recording interval would depend on the herd average for milking frequency. The Gold Standard protocol was applied on five commercial dairy farms with AMS, between December 2011 and February 2013. From 12 milk recording test periods, involving 2211 cow-test days and 8049 cow milkings, standardised 24 h estimates for milk volume and milk composition were calculated for the Gold Standard protocol and compared with those collected during nine alternative sampling scenarios, including six shorter sampling periods and three in which a fixed number of milk samples per cow were collected. Results infer a 48 h milk recording protocol is unnecessarily long for collecting accurate estimates during milk recording on pasture based AMS farms. Collection of two milk samples only per cow was optimal in terms of high concordance correlation coefficients for milk volume and components and a low proportion of missed cow-test days. Further research is required to determine the effects of diurnal variations in milk composition on standardised 24 h estimates for milk volume and components, before a protocol based on a fixed number of samples could be considered. Based on the results of this study New Zealand have adopted a split protocol for herd testing based on the average milking frequency for the herd (NZ Herd Test Standard 8100:2015). PMID:27600967

  14. Limited Reliability of CT perfusion acute infarct volume measurements compared to DWI in anterior circulation stroke

    PubMed Central

    Schaefer, Pamela W.; Souza, Leticia; Kamalian, Shervin; Hirsch, Joshua A.; Yoo, Albert J.; Kamalian, Shahmir; Gonzalez, R. Gilberto; Lev, Michael H.

    2015-01-01

    Background and Purpose DWI can reliably identify critically ischemic tissue (CIT) shortly after stroke onset. We tested if thresholded CT-CBF and CT-CBV maps are sufficiently accurate to substitute for DWI for estimating CIT volume. Methods Ischemic volumes of 55 patients with acute anterior circulation stroke were assessed on DWI by visual segmentation, and CT-CBF and CT-CBV with segmentation using 15% and 30% thresholds, respectively. The contrast-to-noise ratios (CNR) of ischemic regions on the DWI and CTP images were measured. Correlation and Bland-Altman analyses were used to assess reliability of CTP. Results Mean CNRs for DWI, CT-CBF and CT-CBV were 4.3, 0.9 and 0.4, respectively. CTP and DWI lesion volumes were highly correlated (R2=0.87 for CT-CBF; R2=0.83 for CT-CBV; p<0.001). Bland-Altman analyses revealed little systemic bias (−2.6 ml) but high measurement variability (95% CI ±56.7 ml) between mean CT-CBF and DWI lesion volumes, and systemic bias (−26 ml) and high measurement variability (95% CI ±64.0 ml) between mean CT-CBV and DWI lesion volumes. A simulated treatment study demonstrated that using CTP-CBF instead of DWI for detecting a statistically significant effect would require at least twice as many patients. Conclusions The poor CNRs of CT-CBV and CT-CBF compared to DWI result in large measurement error making it problematic to substitute CTP for DWI in selecting individual acute stroke patients for treatment. CTP could be used for treatment studies of patient groups, but the number of patients needed to identify a significant effect is much higher than if DWI is used. PMID:25550366

  15. An optofluidic system with volume measurement and surface plasmon resonance sensor for continuous glucose monitoring.

    PubMed

    Li, Dachao; Lu, Bingyu; Zhu, Rui; Yu, Haixia; Xu, Kexin

    2016-01-01

    The traditional technology of glucose monitoring is painful and invasive because of the frequent blood collection. Nowadays, the enzyme electrode sensor is mainly used for continuous glucose monitoring in clinic, but it has inherent disadvantages of significant signal drift of current due to bioelectricity in body and the missing of hypoglycemia resulting from the irreversible consumption of glucose at the process of enzyme catalytic reaction. Interstitial fluid (ISF) transdermal extraction can be nearly unsensible which effectively reduces the pain caused by invasive detection so that it may provide a new way to monitor glucose. MEMS technology has been used to produce devices for transdermal ISF extraction, but there is a lack of on-chip ISF volume measurement capabilities, which are required to compensate skin permeability variations. This paper presents a lab-on-a-chip system for ISF transdermal extraction, ISF volume measurement, and optical glucose sensing towards the application of continuous glucose monitoring. The device significantly incorporates a MEMS volume sensor, which measures extracted ISF volume via conductance monitoring, and integrates a fiber-optic surface plasmon resonance sensor to measure glucose concentration in microchannel. The fiber-based technique provides an excellent approach to overcome the above two drawbacks of the enzyme electrode based glucose sensing. Six different volumes were tested, and the standard deviation of every sample is less than 0.05 μl, The resonance wavelength moves from 549.081 nm to 592.914 nm while the concentration ranges from 0 to 200 mg/dl. The feasibility of the single-chip device for accurate and continuous monitoring of subcutaneous ISF glucose concentrations is verified. PMID:26958100

  16. Measurement and analysis of grain boundary grooving by volume diffusion

    NASA Technical Reports Server (NTRS)

    Hardy, S. C.; Mcfadden, G. B.; Coriell, S. R.; Voorhees, P. W.; Sekerka, R. F.

    1991-01-01

    Experimental measurements of isothermal grain boundary grooving by volume diffusion are carried out for Sn bicrystals in the Sn-Pb system near the eutectic temperature. The dimensions of the groove increase with a temporal exponent of 1/3, and measurement of the associated rate constant allows the determination of the product of the liquid diffusion coefficient D and the capillarity length Gamma associated with the interfacial free energy of the crystal-melt interface. The small-slope theory of Mullins is generalized to the entire range of dihedral angles by using a boundary integral formulation of the associated free boundary problem, and excellent agreement with experimental groove shapes is obtained. By using the diffusivity measured by Jordon and Hunt, the present measured values of Gamma are found to agree to within 5 percent with the values obtained from experiments by Gunduz and Hunt on grain boundary grooving in a temperature gradient.

  17. Application of a dry-gas meter for measuring air sample volumes in an ambient air monitoring network

    SciTech Connect

    Fritz, Brad G.

    2009-05-24

    Ambient air monitoring for non-research applications (e.g. compliance) occurs at locations throughout the world. Often, the air sampling systems employed for these purposes employee simple yet robust equipment capable of handling the rigors of demanding sampling schedules. At the Hanford Site (near Richland, Washington) concentrations of radionuclides in ambient air are monitored continuously at 44 locations. In 2004, mechanical dry-gas meters were incorporated into the Hanford Site ambient air sample collection system to allow the direct measurement of sample volumes. These meters replaced a portable airflow measurement system that required two manual flow measurements and a sample duration measurement to determine sample volume. A six-month evaluation of the dry-gas meters compared sample volumes calculated using the original flow rate method to the direct sample volume measurement (new method). The results of the evaluation indicate that use of the dry-gas meters result in accurate sample volume measurements and provide greater confidence in the measured sample volumes. In several years of in-network use, the meters have proven to be reliable and have resulted in an improved sampling system.

  18. Do we need time adjusted mean platelet volume measurements?

    PubMed

    Lancé, Marcus D; van Oerle, Rene; Henskens, Yvonne M C; Marcus, Marco A E

    2010-09-01

    Mean platelet volume (MPV) is associated with various diseases. Several authors reported anticoagulant and time dependency. Therefore, standardized laboratory methods are essential. The aim of this study was to standardize the MPV measurement. Blood was collected in potassium-ethylenediaminetetra-acid (EDTA) and sodium-citrate tubes. First, MPV and platelet count were determined every half hour for 4 hours in 20 healthy volunteers. The same parameters were acquired from a second group of 100 healthy donors. We measured at the point of highest stability determined in the first step and aimed to determine a reference range. Citrate samples revealed significantly smaller MPV (7.0 fL ± 0.69 standard deviation [SD]) than EDTA (8.0 fL ± 0.8 SD). Platelets swell until 120 minutes in EDTA and until 60 minutes in citrate. Mean platelet count changed significantly in citrate. In the second group, no inverse correlation between MPV and platelet count was seen. A reference range was calculated (EDTA, 7.2-10.8 fL; citrate, 6.1-9.5 fL). Platelets stored in citrate are significantly smaller compared to those stored in EDTA. Timing is important when measuring platelet volume. Optimal measuring time should be 120 minutes after venipuncture. For this we depicted a reference range. Platelet count is most stable in EDTA. There was no inverse relation between MPV and platelet count. PMID:20858586

  19. Self-heating probe instrument and method for measuring high temperature melting volume change rate of material

    NASA Astrophysics Data System (ADS)

    Wang, Junwei; Wang, Zhiping; Lu, Yang; Cheng, Bo

    2013-03-01

    The castings defects are affected by the melting volume change rate of material. The change rate has an important effect on running safety of the high temperature thermal storage chamber, too. But the characteristics of existing measuring installations are complex structure, troublesome operation and low precision. In order to measure the melting volume change rate of material accurately and conveniently, a self-designed measuring instrument, self-heating probe instrument, and measuring method are described. Temperature in heating cavity is controlled by PID temperature controller; melting volume change rate υ and molten density are calculated based on the melt volume which is measured by the instrument. Positive and negative υ represent expansion and shrinkage of the sample volume after melting, respectively. Taking eutectic LiF+CaF2 for example, its melting volume change rate and melting density at 1 123 K are -20.6% and 2 651 kg·m-3 measured by this instrument, which is only 0.71% smaller than literature value. Density and melting volume change rate of industry pure aluminum at 973 K and analysis pure NaCl at 1 123 K are detected by the instrument too. The measure results are agreed with report values. Measuring error sources are analyzed and several improving measures are proposed. In theory, the measuring errors of the change rate and molten density which are measured by the self-designed instrument is nearly 1/20-1/50 of that measured by the refitted mandril thermal expansion instrument. The self-designed instrument and method have the advantages of simple structure, being easy to operate, extensive applicability for material, relatively high accuracy, and most importantly, temperature and sample vapor pressure have little effect on the measurement accuracy. The presented instrument and method solve the problems of complicated structure and procedures, and large measuring errors for the samples with high vapor pressure by existing installations.

  20. Use of an acoustic helium analyzer for measuring lung volumes.

    PubMed

    Krumpe, P E; MacDannald, H J; Finley, T N; Schear, H E; Hall, J; Cribbs, D

    1981-01-01

    We have evaluated the use of an acoustic gas analyzer (AGA) for the measurement of total lung capacity (TLC) by single-breath helium dilution. The AGA has a rapid response time (0-90% response = 160 ms for 10% He), is linear for helium concentration of 0.1-10%, is stable over a wide range of ambient temperatures, and is small and portable. We plotted the output of the AGA vs. expired lung volume after a vital capacity breath of 10% He. However, since the AGA is sensitive to changes in speed of sound relative to air, the AGA output signal also reports an artifact due to alveolar gases. We corrected for this artifact by replotting a single-breath expiration after a vital capacity breath of room air. Mean alveolar helium concentration (HeA) was then measured by planimetry, using this alveolar gas curve as the base line. TLC was calculated using the HeA from the corrected AGA output and compared with TLC calculated from HeA simultaneously measured using a mass spectrometer (MS). In 12 normal subjects and 9 patients with chronic obstructive pulmonary disease (COPD) TLC-AGA and TLC-MS were compared by linear regression analysis; correlation coefficient (r) was 0.973 for normals and 0.968 for COPD patients (P less than 0.001). This single-breath; estimation of TLC using the corrected signal of the AGA vs. Expired volume seems ideally suited for the measurement of subdivisions of lung volume in field studies. PMID:7204187

  1. Acoustic Phase Measurements from Volume Scatter in the Ocean.

    NASA Astrophysics Data System (ADS)

    Huston, Robert Delmar

    A primary goal of this thesis has been to demonstrate that stable, useful measurements of the orientation of the acoustic signal vector as a function of range and time can be obtained from ocean backscatter, and that this orientation, or acoustic phase, can be related to the local sound speed distribution. Consistent and useful measurement of absolute phase depends upon the positions of individual scatterers, which are normally random and sparse relative to the acoustic wavelength. This difficulty has been overcome by coherent super-position of echoes from successive transmissions, such that the effective density of acoustic targets progressively increases as the summation proceeds. The theoretical basis of this type of coherent processing has been developed and examined in the limiting case, in which it approximates a scatterer continuum for which an analytic expression has been found. The theory provides fundamental insights to the behaviour of both the amplitude and phase of volume scatter. As the ratio of coherent to incoherent signal increases with successive superposition of the echoes (coherent processing), the phase statistics evolve from a uniform to a nearly Gaussian distribution. Once the phase signal is bounded to within +/-45 ^circ, the basic requirement for a coherent 'volume mirror' has been met and reliable interferometric estimates are possible. The experimental work used a bistatic configuration with a multi-beam projector and narrow beam hydrophone operating at 215 kHz. The results confirm the theoretical concepts and demonstrate that within the quite limited range of environmental conditions that were studied, the coherently processed acoustic signals are consistent with independent measurements of the evolving sound speed profile. The main contribution of this thesis has been to lay a firm theoretical and experimental foundation for the use of volume backscatter in acoustic interferometer devices. Based on these results, the potential for new

  2. Simple, accurate, and precise measurements of thermal diffusivity in liquids using a thermal-wave cavity

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.; Mandelis, A.

    2001-06-01

    A simple methodology for the direct measurement of the thermal wavelength using a thermal-wave cavity, and its application to the evaluation of the thermal diffusivity of liquids is described. The simplicity and robustness of this technique lie in its relative measurement features for both the thermal-wave phase and cavity length, thus eliminating the need for taking into account difficult-to-quantify and time-consuming instrumental phase shifts. Two liquid samples were used: distilled water and ethylene glycol. Excellent agreement was found with reported results in the literature. The accuracy of the thermal diffusivity measurements using the new methodology originates in the use of only difference measurements in the thermal-wave phase and cavity length. Measurement precision is directly related to the corresponding precision on the measurement of the thermal wavelength.

  3. Establishing traceability of photometric absorbance values for accurate measurements of the haemoglobin concentration in blood

    NASA Astrophysics Data System (ADS)

    Witt, K.; Wolf, H. U.; Heuck, C.; Kammel, M.; Kummrow, A.; Neukammer, J.

    2013-10-01

    Haemoglobin concentration in blood is one of the most frequently measured analytes in laboratory medicine. Reference and routine methods for the determination of the haemoglobin concentration in blood are based on the conversion of haeme, haemoglobin and haemiglobin species into uniform end products. The total haemoglobin concentration in blood is measured using the absorbance of the reaction products. Traceable absorbance measurement values on the highest metrological level are a prerequisite for the calibration and evaluation of procedures with respect to their suitability for routine measurements and their potential as reference measurement procedures. For this purpose, we describe a procedure to establish traceability of spectral absorbance measurements for the haemiglobincyanide (HiCN) method and for the alkaline haematin detergent (AHD) method. The latter is characterized by a higher stability of the reaction product. In addition, the toxic hazard of cyanide, which binds to the iron ion of the haem group and thus inhibits the oxygen transport, is avoided. Traceability is established at different wavelengths by applying total least-squares analysis to derive the conventional quantity values for the absorbance from the measured values. Extrapolation and interpolation are applied to get access to the spectral regions required to characterize the Q-absorption bands of the HiCN and AHD methods, respectively. For absorbance values between 0.3 and 1.8, the contributions of absorbance measurements to the total expanded uncertainties (95% level of confidence) of absorbance measurements range from 1% to 0.4%.

  4. A More Accurate Measurement of the {sup 28}Si Lattice Parameter

    SciTech Connect

    Massa, E. Sasso, C. P.; Mana, G.; Palmisano, C.

    2015-09-15

    In 2011, a discrepancy between the values of the Planck constant measured by counting Si atoms and by comparing mechanical and electrical powers prompted a review, among others, of the measurement of the spacing of {sup 28}Si (220) lattice planes, either to confirm the measured value and its uncertainty or to identify errors. This exercise confirmed the result of the previous measurement and yields the additional value d{sub 220} = 192 014 711.98(34) am having a reduced uncertainty.

  5. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... production and utilization? It depends on whether you use a meter to calculate Federal production or royalty, and what quantity of resource you are measuring. (a) For meters that you use to calculate Federal royalty: (1) If the meter measures electricity, it must have an accuracy of ±0.25% or better of...

  6. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... production and utilization? It depends on whether you use a meter to calculate Federal production or royalty, and what quantity of resource you are measuring. (a) For meters that you use to calculate Federal royalty: (1) If the meter measures electricity, it must have an accuracy of ±0.25% or better of...

  7. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... production and utilization? It depends on whether you use a meter to calculate Federal production or royalty, and what quantity of resource you are measuring. (a) For meters that you use to calculate Federal royalty: (1) If the meter measures electricity, it must have an accuracy of ±0.25% or better of...

  8. Accurate measurement of the position and velocity of a falling object

    NASA Astrophysics Data System (ADS)

    Garg, Madhur; Kalimullah, Arun, P.; Lima, F. M. S.

    2007-03-01

    An object accelerates while it falls under the influence of the gravitational force. By using two sensors a precise and automated measurement of the velocity can be obtained. The analysis of these measurements may be insufficient if air resistance is important. We discuss how by increasing the number of sensors we can determine the velocity, terminal velocity, and acceleration due to gravity.

  9. An Inexpensive, Stable, and Accurate Relative Humidity Measurement Method for Challenging Environments

    PubMed Central

    Zhang, Wei; Ma, Hong; Yang, Simon X.

    2016-01-01

    In this research, an improved psychrometer is developed to solve practical issues arising in the relative humidity measurement of challenging drying environments for meat manufacturing in agricultural and agri-food industries. The design in this research focused on the structure of the improved psychrometer, signal conversion, and calculation methods. The experimental results showed the effect of varying psychrometer structure on relative humidity measurement accuracy. An industrial application to dry-cured meat products demonstrated the effective performance of the improved psychrometer being used as a relative humidity measurement sensor in meat-drying rooms. In a drying environment for meat manufacturing, the achieved measurement accuracy for relative humidity using the improved psychrometer was ±0.6%. The system test results showed that the improved psychrometer can provide reliable and long-term stable relative humidity measurements with high accuracy in the drying system of meat products. PMID:26999161

  10. Measuring laser power as a force: a new paradigm to accurately monitor optical power during laser-based machining operations

    NASA Astrophysics Data System (ADS)

    Williams, Paul; Simonds, Brian; Sowards, Jeffrey; Hadler, Joshua

    2016-03-01

    In laser manufacturing operations, accurate measurement of laser power is important for product quality, operational repeatability, and process validation. Accurate real-time measurement of high-power lasers, however, is difficult. Typical thermal power meters must absorb all the laser power in order to measure it. This constrains power meters to be large, slow and exclusive (that is, the laser cannot be used for its intended purpose during the measurement). To address these limitations, we have developed a different paradigm in laser power measurement where the power is not measured according to its thermal equivalent but rather by measuring the laser beam's momentum (radiation pressure). Very simply, light reflecting from a mirror imparts a small force perpendicular to the mirror which is proportional to the optical power. By mounting a high-reflectivity mirror on a high-sensitivity force transducer (scale), we are able to measure laser power in the range of tens of watts up to ~ 100 kW. The critical parameters for such a device are mirror reflectivity, angle of incidence, and scale sensitivity and accuracy. We will describe our experimental characterization of a radiation-pressure-based optical power meter. We have tested it for modulated and CW laser powers up to 92 kW in the laboratory and up to 20 kW in an experimental laser welding booth. We will describe present accuracy, temporal response, sources of measurement uncertainty, and hurdles which must be overcome to have an accurate power meter capable of routine operation as a turning mirror within a laser delivery head.

  11. Reheating-volume measure for random-walk inflation

    SciTech Connect

    Winitzki, Sergei

    2008-09-15

    The recently proposed 'reheating-volume' (RV) measure promises to solve the long-standing problem of extracting probabilistic predictions from cosmological multiverse scenarios involving eternal inflation. I give a detailed description of the new measure and its applications to generic models of eternal inflation of random-walk type. For those models I derive a general formula for RV-regulated probability distributions that is suitable for numerical computations. I show that the results of the RV cutoff in random-walk type models are always gauge invariant and independent of the initial conditions at the beginning of inflation. In a toy model where equal-time cutoffs lead to the 'youngness paradox', the RV cutoff yields unbiased results that are distinct from previously proposed measures.

  12. Noninvasive Intracranial Volume and Pressure Measurements Using Ultrasound

    NASA Technical Reports Server (NTRS)

    Hargens, A. R.

    1998-01-01

    Prevention of secondary brain injuries following head can be accomplished most easily when intracranial pressure (ICP) is monitored. However, current measurement techniques are invasive and thus not practical in the combat environment. The Pulsed Phase Lock Loop (PPLL) devise, which was developed and patented, uses a unique, noninvasive ultrasonic phase comparison method to measure slight changes in cranial volume which occur with changes in ICP. Year one studies involved instrument improvements and measurement of altered intracranial distance with altered ICP in fresh cadavera. Our software was improved to facilitate future studies of normal subjects and trauma patients. Our bench studies proved that PPLL output correlated highly with changes in path length across a model cranium. Cadaveric studies demonstrated excellent compact, noninvasive devise for monitoring changes in intracranial distance may aid in the early detection of elevated ICP, decreasing risk of secondary brain injury and infection, and returning head-injured patients to duty.

  13. Accurate measurement of the x-ray coherent scattering form factors of tissues

    NASA Astrophysics Data System (ADS)

    King, Brian W.

    The material dependent x-ray scattering properties of tissues are determined by their scattering form factors, measured as a function of the momentum transfer argument, x. Incoherent scattering form factors, Finc, are calculable for all values of x while coherent scattering form factors, Fcoh, cannot be calculated except at large C because of their dependence on long range order. As a result, measuring Fcoh is very important to the developing field of x-ray scatter imaging. Previous measurements of Fcoh, based on crystallographic techniques, have shown significant variability, as these methods are not optimal for amorphous materials. Two methods of measuring F coh, designed with amorphous materials in mind, are developed in this thesis. An angle-dispersive technique is developed that uses a polychromatic x-ray beam and a large area, energy-insensitive detector. It is shown that Fcoh can be measured in this system if the incident x-ray spectrum is known. The problem is ill-conditioned for typical x-ray spectra and two numerical methods of dealing with the poor conditioning are explored. It is shown that these techniques work best with K-edge filters to limit the spectral width and that the accuracy degrades for strongly ordered materials. Measurements of width Fcoh for water samples are made using 50, 70 and 92 kVp spectra. The average absolute relative difference in Fcoh between our results and the literature for water is approximately 10-15%. Similar measurements for fat samples were made and found to be qualitatively similar to results in the literature, although there is very large variation between the literature values in this case. The angle-dispersive measurement is limited to low resolution measurements of the coherent scattering form factor although it is more accessible than traditional measurements because of the relatively commonplace equipment requirements. An energy-dispersive technique is also developed that uses a polychromatic x-ray beam and an

  14. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range☆

    PubMed Central

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M.; Tozer, Gillian M.; Paley, Martyn N.J.

    2014-01-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4 ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100 μl to 10.000 ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7 μl for 100 μl and 20 μl for 10.000 ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96 mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3–4 s post-injection trigger signal and at 9–12 s in tumor tissue. The pH of the injected pyruvate was 7.1 ± 0.3 (mean ± S.D., n = 10). For small injection volumes, e.g. less than 100 μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump. PMID:24355621

  15. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range

    NASA Astrophysics Data System (ADS)

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M.; Tozer, Gillian M.; Paley, Martyn N. J.

    2014-02-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4 ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100 μl to 10.000 ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7 μl for 100 μl and 20 μl for 10.000 ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96 mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3-4 s post-injection trigger signal and at 9-12 s in tumor tissue. The pH of the injected pyruvate was 7.1 ± 0.3 (mean ± S.D., n = 10). For small injection volumes, e.g. less than 100 μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump.

  16. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range.

    PubMed

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M; Tozer, Gillian M; Paley, Martyn N J

    2014-02-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100μl to 10.000ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7μl for 100μl and 20μl for 10.000ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3-4s post-injection trigger signal and at 9-12s in tumor tissue. The pH of the injected pyruvate was 7.1±0.3 (mean±S.D., n=10). For small injection volumes, e.g. less than 100μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump. PMID:24355621

  17. Periodontal disease activity: a development strategy for its investigation by means of accurate 3-dimensional clinical measurement.

    PubMed

    Watts, T L; Beards, C f; Ewing, P D; Leeman, S

    1995-03-01

    The central problem in all previous approaches to clinical assessment of periodontal disease activity is the use of unidimensional measurement, which implies a number of unjustifiable assumptions. In addition, the use of unidimensional probing measurement has established that there are several distinct problems of validity and reliability in currently available techniques. The present paper begins with an analysis of these matters, leading to an approach to accurate clinical measurement of periodontitis in 3 dimensions, with the possibility of future development of a valid system for assessing the nature of disease activity. PMID:7790525

  18. [Research on accurate measurement of oxygen content in coal using laser-induced breakdown spectroscopy in air environment].

    PubMed

    Yin, Wang-bao; Zhang, Lei; Wang, Le; Dong, Lei; Ma, Wei-guang; Jia, Suo-tang

    2012-01-01

    A technique about accurate measurement of oxygen content in coal in air environment using laser-induced breakdown spectroscopy (LIBS) is introduced in the present paper. Coal samples were excited by the laser, and plasma spectra were obtained. Combining internal standard method, temperature correction method and multi-line methods, the oxygen content of coal samples was precisely measured. The measurement precision is not less than 1.37% for oxygen content in coal analysis, so is satisfied for the requirement of coal-fired power plants in coal analysis. This method can be used in surveying, environmental protection, medicine, materials, archaeological and food safety, biochemical and metallurgy application. PMID:22497159

  19. Accurate measurement of guided modes in a plate using a bidirectional approach.

    PubMed

    Moreau, Ludovic; Minonzio, Jean-Gabriel; Foiret, Josquin; Bossy, Emmanuel; Talmant, Maryline; Laugier, Pascal

    2014-01-01

    Measuring guided wave propagation in long bones is of interest to the medical community. When an inclination exists between the probe and the tested specimen surface, a bias is introduced on the guided mode wavenumbers. The aim of this study was to generalize the bidirectional axial transmission technique initially developed for the first arriving signal. Validation tests were performed on academic materials such a bone-mimicking plate covered with either a silicon or fat-mimicking layer. For any inclination, the wavenumbers measured with the probe parallel to the waveguide surface can be obtained by averaging the wavenumbers measured in two opposite directions. PMID:24437851

  20. A Proposed Frequency Synthesis Approach to Accurately Measure the Angular Position of a Spacecraft

    NASA Technical Reports Server (NTRS)

    Bagri, D. S.

    2005-01-01

    This article describes an approach for measuring the angular position of a spacecraft with reference to a nearby calibration source (quasar) with an accuracy of a few tenths of a nanoradian using a very long baseline interferometer of two antennas that measures the interferometer phase with a modest accuracy. It employs (1) radio frequency phase to determine the spacecraft position with high precision and (2) multiple delay measurements using either frequency tones or telemetry signals at different frequency spacings to resolve ambiguity of the location of the fringe (cycle) containing the direction of the spacecraft.

  1. Measurement of the Velocity of Neutrinos from the CNGS Beam with the Large Volume Detector

    NASA Astrophysics Data System (ADS)

    Agafonova, N. Yu.; Aglietta, M.; Antonioli, P.; Ashikhmin, V. V.; Bari, G.; Bertoni, R.; Bressan, E.; Bruno, G.; Dadykin, V. L.; Fulgione, W.; Galeotti, P.; Garbini, M.; Ghia, P. L.; Giusti, P.; Kemp, E.; Mal'gin, A. S.; Miguez, B.; Molinario, A.; Persiani, R.; Pless, I. A.; Ryasny, V. G.; Ryazhskaya, O. G.; Saavedra, O.; Sartorelli, G.; Shakyrianova, I. R.; Selvi, M.; Trinchero, G. C.; Vigorito, C.; Yakushev, V. F.; Zichichi, A.; Razeto, A.

    2012-08-01

    We report the measurement of the time of flight of ˜17GeV νμ on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated with the beam, with a high absolute time accuracy. These events allow us to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8×10-6<(vν-c)/c<3.1×10-6 (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements.

  2. Measurement of the velocity of neutrinos from the CNGS beam with the large volume detector.

    PubMed

    Agafonova, N Yu; Aglietta, M; Antonioli, P; Ashikhmin, V V; Bari, G; Bertoni, R; Bressan, E; Bruno, G; Dadykin, V L; Fulgione, W; Galeotti, P; Garbini, M; Ghia, P L; Giusti, P; Kemp, E; Mal'gin, A S; Miguez, B; Molinario, A; Persiani, R; Pless, I A; Ryasny, V G; Ryazhskaya, O G; Saavedra, O; Sartorelli, G; Shakyrianova, I R; Selvi, M; Trinchero, G C; Vigorito, C; Yakushev, V F; Zichichi, A; Razeto, A

    2012-08-17

    We report the measurement of the time of flight of ∼17 GeV ν(μ) on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated with the beam, with a high absolute time accuracy. These events allow us to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8 × 10(-6) < (v(ν)-c)/c < 3.1 × 10(-6) (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements. PMID:23006352

  3. A more accurate method for measurement of tuberculocidal activity of disinfectants.

    PubMed Central

    Ascenzi, J M; Ezzell, R J; Wendt, T M

    1987-01-01

    The current Association of Official Analytical Chemists method for testing tuberculocidal activity of disinfectants has been shown to be inaccurate and to have a high degree of variability. An alternate test method is proposed which is more accurate, more precise, and quantitative. A suspension of Mycobacterium bovis BCG was exposed to a variety of disinfectant chemicals and a kill curve was constructed from quantitative data. Data are presented that show the discrepancy between current claims, determined by the Association of Official Analytical Chemists method, of selected commercially available products and claims generated by the proposed method. The effects of different recovery media were examined. The data indicated that Mycobacteria 7H11 and Middlebrook 7H10 agars were equal in recovery of the different chemically treated cells, with Lowenstein-Jensen agar having approximately the same recovery rate but requiring incubation for up to 3 weeks longer for countability. The kill curves generated for several different chemicals were reproducible, as indicated by the standard deviations of the slopes and intercepts of the linear regression curves. PMID:3314707

  4. Accurate evaluation of viscoelasticity of radial artery wall during flow-mediated dilation in ultrasound measurement

    NASA Astrophysics Data System (ADS)

    Sakai, Yasumasa; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    In our previous study, the viscoelasticity of the radial artery wall was estimated to diagnose endothelial dysfunction using a high-frequency (22 MHz) ultrasound device. In the present study, we employed a commercial ultrasound device (7.5 MHz) and estimated the viscoelasticity using arterial pressure and diameter, both of which were measured at the same position. In a phantom experiment, the proposed method successfully estimated the elasticity and viscosity of the phantom with errors of 1.8 and 30.3%, respectively. In an in vivo measurement, the transient change in the viscoelasticity was measured for three healthy subjects during flow-mediated dilation (FMD). The proposed method revealed the softening of the arterial wall originating from the FMD reaction within 100 s after avascularization. These results indicate the high performance of the proposed method in evaluating vascular endothelial function just after avascularization, where the function is difficult to be estimated by a conventional FMD measurement.

  5. Accurate VUV Laboratory Measurements of Fe III Transitions for Astrophysical Applications

    NASA Technical Reports Server (NTRS)

    Blackwell-Whitehead, R. J.; Pickering, J. C.; Smillie, D.; Nave, G.; Szabo, C. I.; Smith, Peter L.; Nielsen, K. E.; Peters, G.

    2006-01-01

    We report preliminary measurements of Fe III spectra in the 1150 to 2500 A wavelength interval. Spectra have been recorded with an iron-neon Penning discharge lamp (PDL) between 1600 and 2500 A at Imperial College (IC) using high resolution Fourier (FT) transform spectroscopy. These FT spectrometer measurements were extended beyond 1600 A to 1150 A using high-resolution grating spectroscopy at the National Institute of Standards and Technology (NIST). These recorded spectra represent the first radiometrically calibrated measurements of a doubly-ionized iron-group element spectrum combining the techniques of vacuum ultraviolet FT and grating spectroscopy. The spectral range of the new laboratory measurements corresponds to recent HST/STIS observations of sharp-lined B stars and of Eta Carinae. The new improved atomic data can be applied to abundance studies and diagnostics of astrophysical plasmas.

  6. Accurate VUV laboratory measurements of Fe III transitions for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Blackwell-Whitehead, R. J.; Pickering, J. C.; Smillie, D.; Nave, G.; Szabo, C. I.; Smith, Peter L.; Nielsen, K. E.; Peters, G.

    We report preliminary measurements of Fe III spectra in the 1150 to 2500 Å wavelength interval. Spectra have been recorded with an iron-neon Penning discharge lamp (PDL) between 1600 and 2500Å at Imperial College (IC) using high resolution Fourier (FT) transform spectroscopy. These FT spectrometer measurements were extended beyond 1600Å to 1150Å using high-resolution grating spectroscopy at the National Institute of Standards and Technology (NIST). These recorded spectra represent the first radiometrically calibrated measurements of a doubly-ionized iron--group element spectrum combining the techniques of vacuum ultraviolet FT and grating spectroscopy. The spectral range of the new laboratory measurements corresponds to recent HST/STIS observations of sharp-lined B stars and of Eta Carinae. The new improved atomic data can be applied to abundance studies and diagnostics of astrophysical plasmas.

  7. Clinical use of diodes and micro-chambers to obtain accurate small field output factor measurements.

    PubMed

    Kairn, T; Charles, P H; Cranmer-Sargison, G; Crowe, S B; Langton, C M; Thwaites, D I; Trapp, J V

    2015-06-01

    There have been substantial advances in small field dosimetry techniques and technologies, over the last decade, which have dramatically improved the achievable accuracy of small field dose measurements. This educational note aims to help radiation oncology medical physicists to apply some of these advances in clinical practice. The evaluation of a set of small field output factors (total scatter factors) is used to exemplify a detailed measurement and simulation procedure and as a basis for discussing the possible effects of simplifying that procedure. Field output factors were measured with an unshielded diode and a micro-ionisation chamber, at the centre of a set of square fields defined by a micro-multileaf collimator. Nominal field sizes investigated ranged from 6 × 6 to 98 × 98 mm(2). Diode measurements in fields smaller than 30 mm across were corrected using response factors calculated using Monte Carlo simulations of the diode geometry and daisy-chained to match micro-chamber measurements at intermediate field sizes. Diode measurements in fields smaller than 15 mm across were repeated twelve times over three separate measurement sessions, to evaluate the reproducibility of the radiation field size and its correspondence with the nominal field size. The five readings that contributed to each measurement on each day varied by up to 0.26  %, for the "very small" fields smaller than 15 mm, and 0.18 % for the fields larger than 15 mm. The diode response factors calculated for the unshielded diode agreed with previously published results, within uncertainties. The measured dimensions of the very small fields differed by up to 0.3 mm, across the different measurement sessions, contributing an uncertainty of up to 1.2 % to the very small field output factors. The overall uncertainties in the field output factors were 1.8 % for the very small fields and 1.1 % for the fields larger than 15 mm across. Recommended steps for acquiring small field output

  8. Accurate measurement of poleward microtubule flux in the spindle of Drosophila S2 cells.

    PubMed

    Munzarova, Alina; Popova, Julia; Razuvaeva, Alena; Shloma, Victor; Gatti, Maurizio; Omelyanchuk, Leonid

    2016-09-01

    The spindle microtubule (MT) flux is the continuous translocation of MTs toward the spindle poles caused by MT polymerization at plus ends coupled to depolymerization at minus ends. Poleward flux is observed in both mitotic and meiotic spindles; it is evolutionarily conserved and contributes to the regulation of spindle length and anaphase chromosome movement. MT photobleaching is a tool frequently used to measure poleward flux. Spindles containing fluorescently tagged tubulin are photobleached to generate a non-fluorescent stripe, which moves toward the spindle poles allowing a measure of the flux. However, this method only permits rapid measurements of the flux, because the fluorescence of the bleached stripe recovers rapidly due to the spindle MT turnover. Here, we describe a modification of the current photobleaching-based method for flux measurement. We photobleached two large areas at the opposite sides of the metaphase plate in spindles of Drosophila S2 cells expressing Cherry-tagged tubulin, leaving unbleached only the area near the chromosomes. We then measured the speed with which the fluorescent MTs move toward the poles. We found that this method allows a measure of the flux over a two- to threefold longer time than the "single stripe" method, providing a reliable evaluation of the flux rate. PMID:27317357

  9. [Measurement of left atrial and ventricular volumes in real-time 3D echocardiography. Validation by nuclear magnetic resonance

    NASA Technical Reports Server (NTRS)

    Bauer, F.; Shiota, T.; Qin, J. X.; White, R. D.; Thomas, J. D.

    2001-01-01

    The measurement of the left ventricular ejection fraction is important for the evaluation of cardiomyopathy and depends on the measurement of left ventricular volumes. There are no existing conventional echocardiographic means of measuring the true left atrial and ventricular volumes without mathematical approximations. The aim of this study was to test anew real time 3-dimensional echocardiographic system of calculating left atrial and ventricular volumes in 40 patients after in vitro validation. The volumes of the left atrium and ventricle acquired from real time 3-D echocardiography in the apical view, were calculated in 7 sections parallel to the surface of the probe and compared with atrial (10 patients) and ventricular (30 patients) volumes calculated by nuclear magnetic resonance with the simpson method and with volumes of water in balloons placed in a cistern. Linear regression analysis showed an excellent correlation between the real volume of water in the balloons and volumes given in real time 3-dimensional echocardiography (y = 0.94x + 5.5, r = 0.99, p < 0.001, D = -10 +/- 4.5 ml). A good correlation was observed between real time 3-dimensional echocardiography and nuclear magnetic resonance for the measurement of left atrial and ventricular volumes (y = 0.95x - 10, r = 0.91, p < 0.001, D = -14.8 +/- 19.5 ml and y = 0.87x + 10, r = 0.98, P < 0.001, D = -8.3 +/- 18.7 ml, respectively. The authors conclude that real time three-dimensional echocardiography allows accurate measurement of left heart volumes underlying the clinical potential of this new 3-D method.

  10. Optimizing photon fluence measurements for the accurate determination of detective quantum efficiency

    NASA Astrophysics Data System (ADS)

    Wong, Molly; Zhang, Da; Rong, John; Wu, Xizeng; Liu, Hong

    2009-10-01

    Our goal was to evaluate the error contributed by photon fluence measurements to the detective quantum efficiency (DQE) of an x-ray imaging system. The investigation consisted of separate error analyses for the exposure and spectrum measurements that determine the photon fluence. Methods were developed for each to determine the number of measurements required to achieve an acceptable error. A new method for calculating the magnification factor in the exposure measurements was presented and compared to the existing method. The new method not only produces much lower error at small source-to-image distances (SIDs) such as clinical systems, but is also independent of SID. The exposure and spectra results were combined to determine the photon fluence error contribution to the DQE of 4%. The error in this study is small because the measurements resulted from precisely controlled experimental procedures designed to minimize the error. However, these procedures are difficult to follow in clinical environments, and application of this method on clinical systems could therefore provide important insight into error reduction. This investigation was focused on the error in the photon fluence contribution to the DQE, but the error analysis method can easily be extended to a wide range of applications.

  11. A method to measure the density of seawater accurately to the level of 10-6

    NASA Astrophysics Data System (ADS)

    Schmidt, Hannes; Wolf, Henning; Hassel, Egon

    2016-04-01

    A substitution method to measure seawater density relative to pure water density using vibrating tube densimeters was realized and validated. Standard uncertainties of 1 g m-3 at atmospheric pressure, 10 g m-3 up to 10 MPa, and 20 g m-3 to 65 MPa in the temperature range of 5 °C to 35 °C and for salt contents up to 35 g kg-1 were achieved. The realization was validated by comparison measurements with a hydrostatic weighing apparatus for atmospheric pressure. For high pressures, literature values of seawater compressibility were compared with substitution measurements of the realized apparatus.

  12. An evaluation of effective radiuses of bulk-wave ultrasonic transducers as circular piston sources for accurate velocity measurements.

    PubMed

    Arakawa, Mototaka; Kushibiki, Jun-ichi; Aoki, Naoya

    2004-05-01

    The effective radius of a bulk-wave ultrasonic transducer as a circular piston source, fabricated on one end of a synthetic silica (SiO2) glass buffer rod, was evaluated for accurate velocity measurements of dispersive specimens over a wide frequency range. The effective radius was determined by comparing measured and calculated phase variations due to diffraction in an ultrasonic transmission line of the SiO2 buffer rod/water-couplant/SiO2 standard specimen, using radio-frequency (RF) tone burst ultrasonic waves. Fourteen devices with different device parameters were evaluated. The velocities of the nondispersive standard specimen (C-7940) were found to be 5934.10 +/- 0.35 m/s at 70 to 290 MHz, after diffraction correction using the nominal radius (0.75 mm) for an ultrasonic device with an operating center frequency of about 400 MHz. Corrected velocities were more accurately found to be 5934.15 +/- 0.03 m/s by using the effective radius (0.780 mm) for the diffraction correction. Bulk-wave ultrasonic devices calibrated by this experimental procedure enable conducting extremely accurate velocity dispersion measurements. PMID:15217227

  13. EEMD based pitch evaluation method for accurate grating measurement by AFM

    NASA Astrophysics Data System (ADS)

    Li, Changsheng; Yang, Shuming; Wang, Chenying; Jiang, Zhuangde

    2016-09-01

    The pitch measurement and AFM calibration precision are significantly influenced by the grating pitch evaluation method. This paper presents the ensemble empirical mode decomposition (EEMD) based pitch evaluation method to relieve the accuracy deterioration caused by high and low frequency components of scanning profile during pitch evaluation. The simulation analysis shows that the application of EEMD can improve the pitch accuracy of the FFT-FT algorithm. The pitch error is small when the iteration number of the FFT-FT algorithms was 8. The AFM measurement of the 500 nm-pitch one-dimensional grating shows that the EEMD based pitch evaluation method could improve the pitch precision, especially the grating line position precision, and greatly expand the applicability of the gravity center algorithm when particles and impression marks were distributed on the sample surface. The measurement indicates that the nonlinearity was stable, and the nonlinearity of x axis and forward scanning was much smaller than their counterpart. Finally, a detailed pitch measurement uncertainty evaluation model suitable for commercial AFMs was demonstrated and a pitch uncertainty in the sub-nanometer range was achieved. The pitch uncertainty was reduced about 10% by EEMD.

  14. An affordable and accurate conductivity probe for density measurements in stratified flows

    NASA Astrophysics Data System (ADS)

    Carminati, Marco; Luzzatto-Fegiz, Paolo

    2015-11-01

    In stratified flow experiments, conductivity (combined with temperature) is often used to measure density. The probes typically used can provide very fine spatial scales, but can be fragile, expensive to replace, and sensitive to environmental noise. A complementary instrument, comprising a low-cost conductivity probe, would prove valuable in a wide range of applications where resolving extremely small spatial scales is not needed. We propose using micro-USB cables as the actual conductivity sensors. By removing the metallic shield from a micro-B connector, 5 gold-plated microelectrodes are exposed and available for 4-wire measurements. These have a cell constant ~550m-1, an intrinsic thermal noise of at most 30pA/Hz1/2, as well as sub-millisecond time response, making them highly suitable for many stratified flow measurements. In addition, we present the design of a custom electronic board (Arduino-based and Matlab-controlled) for simultaneous acquisition from 4 sensors, with resolution (in conductivity, and resulting density) exceeding the performance of typical existing probes. We illustrate the use of our conductivity-measuring system through stratified flow experiments, and describe plans to release simple instructions to construct our complete system for around 200.

  15. High- and low-pressure pneumotachometers measure respiration rates accurately in adverse environments

    NASA Technical Reports Server (NTRS)

    Fagot, R. J.; Mc Donald, R. T.; Roman, J. A.

    1968-01-01

    Respiration-rate transducers in the form of pneumotachometers measure respiration rates of pilots operating high performance research aircraft. In each low pressure or high pressure oxygen system a sensor is placed in series with the pilots oxygen supply line to detect gas flow accompanying respiration.

  16. New insights for accurate chemically specific measurements of slow diffusing molecules

    NASA Astrophysics Data System (ADS)

    Hou, Jianbo; Madsen, Louis A.

    2013-02-01

    Investigating the myriad features of molecular transport in materials yields fundamental information for understanding processes such as ion conduction, chemical reactions, and phase transitions. Molecular transport especially impacts the performance of ion-containing liquids and polymeric materials when used as electrolytes and separation media, with applications encompassing battery electrolytes, reverse-osmosis membranes, mechanical transducers, and fuel cells. Nuclear magnetic resonance (NMR) provides a unique probe of molecular translations by allowing measurement of all mobile species via spectral selectivity, access to a broad range of transport coefficients, probing of any material direction, and investigation of variable lengthscales in a material, thus, tying morphology to transport. Here, we present new concepts to test for and guarantee robust diffusion measurements. We first employ a standard pulsed-field-gradient (PFG) calibration protocol using 2H2O and obtain expected results, but we observe crippling artifacts when measuring 1H-glycerol diffusion with the same experimental parameters. A mathematical analysis of 2H2O and glycerol signals in the presence of PFG transients show tight agreement with experimental observations. These analyses lead to our principal findings that (1) negligible artifacts observed with low gyromagnetic ratio (γ) nuclei may become dominant when observing high γ nuclei, and (2) reducing the sample dimension along the gradient direction predictably reduces non-ideal behaviors of NMR signals. We further provide a useful quantitative strategy for error minimization when measuring diffusing species slower than the one used for gradient calibration.

  17. Accurate method for measuring oblique astigmatism and oblique power of ophthalmic lenses

    NASA Astrophysics Data System (ADS)

    Wihardjo, Erning; Silva, Donald E.

    1991-12-01

    The measurement of oblique astigmatism error and its oblique power of ophthalmic lens under identical conditions of the human visual system--such as the distance from the center rotation of the eye to the back vertex surface of the lens--viewing distance, and lens aperture using a Mach Zehnder interferometer is describe.

  18. An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity.

    PubMed

    Allen, Kenneth W; Scott, Mark M; Reid, David R; Bean, Jeffrey A; Ellis, Jeremy D; Morris, Andrew P; Marsh, Jeramy M

    2016-05-01

    In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S21) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S21 measurement. The sensitivity of the technique to sample length was explored by simulating specimen lengths from 2.54 to 15.24 cm, in 2.54 cm increments. Analysis of our simulated data predicts the technique will have the sensitivity to measure loss tangent values on the order of 10(-3) for materials such as polymers with relatively low real permittivity values. The ability to accurately characterize low-loss dielectric material specimens of polypropylene is demonstrated experimentally. The method was validated by excellent agreement with a free-space focused-beam system measurement of a polypropylene sheet. This technique provides the material measurement community with the ability to accurately extract material properties of low-loss material specimen over the entire X-band range. This technique could easily be extended to other frequency bands. PMID:27250447

  19. A New Method for Accurate Signal Processing in Measurements of Elemental Mercury Vapor by Atomic Fluorescence Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L., II; Jaffe, D. A.

    2015-12-01

    The most widely used method for quantifying atmospheric Hg is gold amalgamation pre-concentration, followed by thermal desorption (TD) and detection via atomic fluorescence spectrophotometry (AFS). Most AFS-based atmospheric Hg measurements are carried out using commercial analyzers manufactured by Tekran® Instruments Corp. (instrument models 2537A and 2537B). A generally overlooked and poorly characterized source of analytical uncertainty in these measurements is the method by which the raw Hg AFS signal is processed. In nearly all applications of Tekran® analyzers for atmospheric Hg measurements, researchers rely upon embedded software which automatically integrates the Hg TD peaks. However, Swartzendruber et al. (2009; doi:10.1016/j.atmosenv.2009.02.063) demonstrated that the Hg TD peaks can be more accurately defined, and overall measurement precision increased, by post-processing the raw Hg AFS signal; improvements in measurement accuracy and precision were shown to be more significant at lower sample loadings. Despite these findings, a standardized method for signal post-processing has not been presented. To better characterize uncertainty associated with Tekran® based atmospheric Hg measurements, and to facilitate more widespread adoption of an accurate, standardized signal processing method, we developed a new, distributable Virtual Instrument (VI) which performs semi-automated post-processing of the raw Hg AFS signal from the Tekran® analyzers. Here we describe the key features of the VI and compare its performance to that of the Tekran® signal processing method.

  20. An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity

    NASA Astrophysics Data System (ADS)

    Allen, Kenneth W.; Scott, Mark M.; Reid, David R.; Bean, Jeffrey A.; Ellis, Jeremy D.; Morris, Andrew P.; Marsh, Jeramy M.

    2016-05-01

    In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S21) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S21 measurement. The sensitivity of the technique to sample length was explored by simulating specimen lengths from 2.54 to 15.24 cm, in 2.54 cm increments. Analysis of our simulated data predicts the technique will have the sensitivity to measure loss tangent values on the order of 10-3 for materials such as polymers with relatively low real permittivity values. The ability to accurately characterize low-loss dielectric material specimens of polypropylene is demonstrated experimentally. The method was validated by excellent agreement with a free-space focused-beam system measurement of a polypropylene sheet. This technique provides the material measurement community with the ability to accurately extract material properties of low-loss material specimen over the entire X-band range. This technique could easily be extended to other frequency bands.

  1. Determination of volume fractions in two-phase flows from sound speed measurement

    SciTech Connect

    Chaudhuri, Anirban; Sinha, Dipen N.; Osterhoudt, Curtis F.

    2012-08-15

    Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes and calibration errors are also presented.

  2. Optimum satellite orbits for accurate measurement of the earth's radiation budget, summary

    NASA Technical Reports Server (NTRS)

    Campbell, G. G.; Vonderhaar, T. H.

    1978-01-01

    The optimum set of orbit inclinations for the measurement of the earth radiation budget from spacially integrating sensor systems was estimated for two and three satellite systems. The best set of the two were satellites at orbit inclinations of 80 deg and 50 deg; of three the inclinations were 80 deg, 60 deg and 50 deg. These were chosen on the basis of a simulation of flat plate and spherical detectors flying over a daily varying earth radiation field as measured by the Nimbus 3 medium resolution scanners. A diurnal oscillation was also included in the emitted flux and albedo to give a source field as realistic as possible. Twenty three satellites with different inclinations and equator crossings were simulated, allowing the results of thousand of multisatellite sets to be intercompared. All were circular orbits of radius 7178 kilometers.

  3. A Procedure for Accurately Measuring the Shaker Overturning Moment During Random Vibration Tests

    NASA Technical Reports Server (NTRS)

    Nayeri, Reza D.

    2011-01-01

    Motivation: For large system level random vibration tests, there may be some concerns about the shaker's capability for the overturning moment. It is the test conductor's responsibility to predict and monitor the overturning moment during random vibration tests. If the predicted moment is close to the shaker's capability, test conductor must measure the instantaneous moment at low levels and extrapolate to higher levels. That data will be used to decide whether it is safe to proceed to the next test level. Challenge: Kistler analog formulation for computing the real-time moment is only applicable to very limited cases in which we have 3 or 4 load cells installed at shaker interface with hardware. Approach: To overcome that limitation, a simple procedure was developed for computing the overturning moment time histories using the measured time histories of the individual load cells.

  4. Switched integration amplifier-based photocurrent meter for accurate spectral responsivity measurement of photometers.

    PubMed

    Park, Seongchong; Hong, Kee-Suk; Kim, Wan-Seop

    2016-03-20

    This work introduces a switched integration amplifier (SIA)-based photocurrent meter for femtoampere (fA)-level current measurement, which enables us to measure a 107 dynamic range of spectral responsivity of photometers even with a common lamp-based monochromatic light source. We described design considerations and practices about operational amplifiers (op-amps), switches, readout methods, etc., to compose a stable SIA of low offset current in terms of leakage current and gain peaking in detail. According to the design, we made six SIAs of different integration capacitance and different op-amps and evaluated their offset currents. They showed an offset current of (1.5-85) fA with a slow variation of (0.5-10) fA for an hour under opened input. Applying a detector to the SIA input, the offset current and its variation were increased and the SIA readout became noisier due to finite shunt resistance and nonzero shunt capacitance of the detector. One of the SIAs with 10 pF nominal capacitance was calibrated using a calibrated current source at the current level of 10 nA to 1 fA and at the integration time of 2 to 65,536 ms. As a result, we obtained a calibration formula for integration capacitance as a function of integration time rather than a single capacitance value because the SIA readout showed a distinct dependence on integration time at a given current level. Finally, we applied it to spectral responsivity measurement of a photometer. It is demonstrated that the home-made SIA of 10 pF was capable of measuring a 107 dynamic range of spectral responsivity of a photometer. PMID:27140564

  5. Development of Filtered Rayleigh Scattering for Accurate Measurement of Gas Velocity

    NASA Technical Reports Server (NTRS)

    Miles, Richard B.; Lempert, Walter R.

    1995-01-01

    The overall goals of this research were to develop new diagnostic tools capable of capturing unsteady and/or time-evolving, high-speed flow phenomena. The program centers around the development of Filtered Rayleigh Scattering (FRS) for velocity, temperature, and density measurement, and the construction of narrow linewidth laser sources which will be capable of producing an order MHz repetition rate 'burst' of high power pulses.

  6. Three-Signal Method for Accurate Measurements of Depolarization Ratio with Lidar

    NASA Technical Reports Server (NTRS)

    Reichardt, Jens; Baumgart, Rudolf; McGee, Thomsa J.

    2003-01-01

    A method is presented that permits the determination of atmospheric depolarization-ratio profiles from three elastic-backscatter lidar signals with different sensitivity to the state of polarization of the backscattered light. The three-signal method is insensitive to experimental errors and does not require calibration of the measurement, which could cause large systematic uncertainties of the results, as is the case in the lidar technique conventionally used for the observation of depolarization ratios.

  7. Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Mäntynen, Henrik; Ikonen, Erkki

    2016-06-01

    The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

  8. A Robust Method of Vehicle Stability Accurate Measurement Using GPS and INS

    NASA Astrophysics Data System (ADS)

    Miao, Zhibin; Zhang, Hongtian; Zhang, Jinzhu

    2015-12-01

    With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) is a very practical method to get high-precision measurement data. Usually, the Kalman filter is used to fuse the data from GPS and INS. In this paper, a robust method is used to measure vehicle sideslip angle and yaw rate, which are two important parameters for vehicle stability. First, a four-wheel vehicle dynamic model is introduced, based on sideslip angle and yaw rate. Second, a double level Kalman filter is established to fuse the data from Global Positioning System and Inertial Navigation System. Then, this method is simulated on a sample vehicle, using Carsim software to test the sideslip angle and yaw rate. Finally, a real experiment is made to verify the advantage of this approach. The experimental results showed the merits of this method of measurement and estimation, and the approach can meet the design requirements of the vehicle stability controller.

  9. Optimal Number of Angle Images for Calculating Anterior Angle Volume and Iris Volume Measurements

    PubMed Central

    Blieden, Lauren S.; Chuang, Alice Z.; Baker, Laura A.; Bell, Nicholas P.; Fuller, Timothy S.; Mankiewicz, Kimberly A.; Feldman, Robert M.

    2015-01-01

    Purpose. We determined the optimal number of angle images required to obtain reliable measurements of trabecular-iris circumferential volume (TICV) and iris volume (IV) using swept-source Fourier domain anterior segment optical coherence tomography (SSFD-ASOCT) scans in narrow angle eyes. Methods. Scleral spur landmarks (SSL) were manually identified on ASOCT angle images from 128 meridians from each of 24 eyes with chronic primary angle closure (PAC) spectrum of disease. The anterior and posterior corneal curves, and the anterior and posterior iris surfaces were identified automatically by the anterior chamber analysis and interpretation (ACAI) software, then manually examined and edited by the reader if required. Trabecular-iris circumferential volume at 750 μm from SSL (TICV750) and IV were subsequently calculated using varying numbers of angle images. Threshold error was determined to be less than the lower 95% confidence limit of mean absolute percent error (MAPE) of the change in TICV or IV resulting from laser peripheral iridotomy, which would be 17% for TICV and 5% for IV, based on previous studies. The optimal number of angle images was the smallest number of images where MAPE was less than this threshold for TICV and IV. Results. A total of 32 equally-spaced angle images (16 meridians) was required to estimate TICV750 and 16 angle images (8 meridians) to estimate IV. Both were within 4.6% and 1.6% of MAPE, respectively. Conclusions. It is possible to determine TICV and IV parameters reliably in narrow angles without evaluating all 128 meridians obtained with SSFD-ASOCT. PMID:25829412

  10. Recent Results on the Accurate Measurements of the Dielectric Constant of Seawater at 1.413GHZ

    NASA Technical Reports Server (NTRS)

    Lang, R.H.; Tarkocin, Y.; Utku, C.; Le Vine, D.M.

    2008-01-01

    Measurements of the complex. dielectric constant of seawater at 30.00 psu, 35.00 psu and 38.27 psu over the temperature range from 5 C to 3 5 at 1.413 GHz are given and compared with the Klein-Swift results. A resonant cavity technique is used. The calibration constant used in the cavity perturbation formulas is determined experimentally using methanol and ethanediol (ethylene glycol) as reference liquids. Analysis of the data shows that the measurements are accurate to better than 1.0% in almost all cases studied.

  11. Dedicated breast CT: Fibroglandular volume measurements in a diagnostic population

    SciTech Connect

    Vedantham, Srinivasan; Shi Linxi; Karellas, Andrew; O'Connell, Avice M.

    2012-12-15

    Purpose: To determine the mean and range of volumetric glandular fraction (VGF) of the breast in a diagnostic population using a high-resolution flat-panel cone-beam dedicated breast CT system. This information is important for Monte Carlo-based estimation of normalized glandular dose coefficients and for investigating the dependence of VGF on breast dimensions, race, and pathology. Methods: Image data from a clinical trial investigating the role of dedicated breast CT that enrolled 150 women were retrospectively analyzed to determine the VGF. The study was conducted in adherence to a protocol approved by the institutional human subjects review boards and written informed consent was obtained from all study participants. All participants in the study were assigned BI-RADS{sup Registered-Sign} 4 or 5 as per the American College of Radiology assessment categories after standard diagnostic work-up and underwent dedicated breast CT exam prior to biopsy. A Gaussian-kernel based fuzzy c-means algorithm was used to partition the breast CT images into adipose and fibroglandular tissue after segmenting the skin. Upon determination of the accuracy of the algorithm with a phantom, it was applied to 137 breast CT volumes from 136 women. VGF was determined for each breast and the mean and range were determined. Pathology results with classification as benign, malignant, and hyperplasia were available for 132 women, and were used to investigate if the distributions of VGF varied with pathology. Results: The algorithm was accurate to within {+-}1.9% in determining the volume of an irregular shaped phantom. The study mean ({+-} inter-breast SD) for the VGF was 0.172 {+-} 0.142 (range: 0.012-0.719). VGF was found to be negatively correlated with age, breast dimensions (chest-wall to nipple length, pectoralis to nipple length, and effective diameter at chest-wall), and total breast volume, and positively correlated with fibroglandular volume. Based on pathology, pairwise statistical

  12. [Methods and importance of volume measurement in reconstructive and aesthetic breast surgery].

    PubMed

    Kunos, Csaba; Gulyás, Gusztáv; Pesthy, Pál; Kovács, Eszter; Mátrai, Zoltán

    2014-03-16

    Volume measurement of the breast allows for better surgical planning and implant selection in breast reconstructive and symmetrization procedures. The safety and accuracy of tumor removal, in accordance with oncoplastic principles, may be improved by knowing the true breast- and breast tumor volume. The authors discuss the methods of volume measurement of the breast and describe the method based on magnetic resonance imaging digital volume measurement in details. The volume of the breast parenchyma and the tumor was determined by processing the diagnostic magnetic resonance scans, and the difference in the volume of the two breasts was measured. Surgery was planned and implant selection was made based on the measured volume details. The authors conclude that digital volume measurement proved to be a valuable tool in preoperative planning of volume reducing mammaplasty, replacement of unknown size implants and in cases when breast asymmetry is treated. PMID:24613775

  13. Accurate mass measurements of short-lived isotopes with the MISTRAL* rf spectrometer

    SciTech Connect

    Toader, C.; Audi, G.; Doubre, H.; Jacotin, M.; Henry, S.; Kepinski, J.-F.; Le Scornet, G.; Lunney, D.; Monsanglant, C.; Saint Simon, M. de; Thibault, C.; Borcea, C.; Duma, M.; Lebee, G.

    1999-01-15

    The MISTRAL* experiment has measured its first masses at ISOLDE. Installed in May 1997, this radiofrequency transmission spectrometer is to concentrate on nuclides with particularly short half-lives. MISTRAL received its first stable beam in October and first radioactive beam in November 1997. These first tests, with a plasma ion source, resulted in excellent isobaric separation and reasonable transmission. Further testing and development enabled first data taking in July 1998 on neutron-rich Na isotopes having half-lives as short as 31 ms.

  14. The dark art of light measurement: accurate radiometry for low-level light therapy.

    PubMed

    Hadis, Mohammed A; Zainal, Siti A; Holder, Michelle J; Carroll, James D; Cooper, Paul R; Milward, Michael R; Palin, William M

    2016-05-01

    Lasers and light-emitting diodes are used for a range of biomedical applications with many studies reporting their beneficial effects. However, three main concerns exist regarding much of the low-level light therapy (LLLT) or photobiomodulation literature; (1) incomplete, inaccurate and unverified irradiation parameters, (2) miscalculation of 'dose,' and (3) the misuse of appropriate light property terminology. The aim of this systematic review was to assess where, and to what extent, these inadequacies exist and to provide an overview of 'best practice' in light measurement methods and importance of correct light measurement. A review of recent relevant literature was performed in PubMed using the terms LLLT and photobiomodulation (March 2014-March 2015) to investigate the contemporary information available in LLLT and photobiomodulation literature in terms of reporting light properties and irradiation parameters. A total of 74 articles formed the basis of this systematic review. Although most articles reported beneficial effects following LLLT, the majority contained no information in terms of how light was measured (73%) and relied on manufacturer-stated values. For all papers reviewed, missing information for specific light parameters included wavelength (3%), light source type (8%), power (41%), pulse frequency (52%), beam area (40%), irradiance (43%), exposure time (16%), radiant energy (74%) and fluence (16%). Frequent use of incorrect terminology was also observed within the reviewed literature. A poor understanding of photophysics is evident as a significant number of papers neglected to report or misreported important radiometric data. These errors affect repeatability and reliability of studies shared between scientists, manufacturers and clinicians and could degrade efficacy of patient treatments. Researchers need a physicist or appropriately skilled engineer on the team, and manuscript reviewers should reject papers that do not report beam measurement

  15. Combination 3D TOP with 2D PC MRA Techique for cerebral blood flow volume measurement.

    PubMed

    Guo, G; Wu, R H; Zhang, Y P; Guan, J T; Guo, Y L; Cheng, Y; terBrugge, K; Mikulis, D J

    2006-01-01

    To demonstrate the discrepancy of cerebral blood flow volume (BFV) estimation with 2D phase-contrast (2D PC) MRA guided with 3D time-of-flight (3D TOF) MR localization by using an "internal" standard. 20 groups of the common (CCA), internal (ICA), and external (ECA) carotid arteries in 10 healthy subjects were examined with 2D PC MRA guided by 3D TOF MR angiograms. The sum BFV of the internal and external carotid arteries was then compared with the ipsilateral common carotid artery flow. An accurate technique would demonstrate no difference. The difference was therefore a measure of accuracy of the method. 3D TOF MRA localization is presented to allow the determination of a slice orientation to improve the accuracy of 2D PC MRA in estimate the BFV. By using the combined protocols, there was better correlation in BFV estimate between the sum of ICA+ECA with the ipsilateral CCA (R2=0.729, P=0.000). The inconsistency (mean +/- SD) was found to be 6.95 +/- 5.95% for estimate the BFV in ICA+ECA and ipsilateral CCA. The main inconsistency was contributed to the ECA and its branches. Guided with 3D TOF MRA localization, 2D PC MRA is more accurate in the determination of blood flow volume in the carotid arteries. PMID:17946401

  16. Non-VKA Oral Anticoagulants: Accurate Measurement of Plasma Drug Concentrations

    PubMed Central

    Mani, Helen; Minet, Valentine; Devalet, Bérangère; Chatelain, Bernard; Dogné, Jean-Michel

    2015-01-01

    Non-VKA oral anticoagulants (NOACs) have now widely reached the lucrative market of anticoagulation. While the marketing authorization holders claimed that no routine monitoring is required and that these compounds can be given at fixed doses, several evidences arisen from the literature tend to demonstrate the opposite. New data suggests that an assessment of the response at the individual level could improve the benefit-risk ratio of at least dabigatran. Information regarding the association of rivaroxaban and apixaban exposure and the bleeding risk is available in the drug approval package on the FDA website. These reviews suggest that accumulation of these compounds increases the risk of experiencing a bleeding complication. Therefore, in certain patient populations such as patients with acute or chronic renal impairment or with multiple drug interactions, measurement of drug exposure may be useful to ensure an optimal treatment response. More specific circumstances such as patients experiencing a haemorrhagic or thromboembolic event during the treatment duration, patients who require urgent surgery or an invasive procedure, or patient with a suspected overdose could benefit from such a measurement. This paper aims at providing guidance on how to best estimate the intensity of anticoagulation using laboratory assays in daily practice. PMID:26090400

  17. Highly accurate thermal flow microsensor for continuous and quantitative measurement of cerebral blood flow.

    PubMed

    Li, Chunyan; Wu, Pei-ming; Wu, Zhizhen; Limnuson, Kanokwan; Mehan, Neal; Mozayan, Cameron; Golanov, Eugene V; Ahn, Chong H; Hartings, Jed A; Narayan, Raj K

    2015-10-01

    Cerebral blood flow (CBF) plays a critical role in the exchange of nutrients and metabolites at the capillary level and is tightly regulated to meet the metabolic demands of the brain. After major brain injuries, CBF normally decreases and supporting the injured brain with adequate CBF is a mainstay of therapy after traumatic brain injury. Quantitative and localized measurement of CBF is therefore critically important for evaluation of treatment efficacy and also for understanding of cerebral pathophysiology. We present here an improved thermal flow microsensor and its operation which provides higher accuracy compared to existing devices. The flow microsensor consists of three components, two stacked-up thin film resistive elements serving as composite heater/temperature sensor and one remote resistive element for environmental temperature compensation. It operates in constant-temperature mode (~2 °C above the medium temperature) providing 20 ms temporal resolution. Compared to previous thermal flow microsensor based on self-heating and self-sensing design, the sensor presented provides at least two-fold improvement in accuracy in the range from 0 to 200 ml/100 g/min. This is mainly achieved by using the stacked-up structure, where the heating and sensing are separated to improve the temperature measurement accuracy by minimization of errors introduced by self-heating. PMID:26256480

  18. A simple and reliable sensor for accurate measurement of angular speed for low speed rotating machinery.

    PubMed

    Kuosheng, Jiang; Guanghua, Xu; Tangfei, Tao; Lin, Liang; Yi, Wang; Sicong, Zhang; Ailing, Luo

    2014-01-01

    This paper presents the theory and implementation of a novel sensor system for measuring the angular speed (AS) of a shaft rotating at a very low speed range, nearly zero speed. The sensor system consists mainly of an eccentric sleeve rotating with the shaft on which the angular speed to be measured, and an eddy current displacement sensor to obtain the profile of the sleeve for AS calculation. When the shaft rotates at constant speed the profile will be a pure sinusoidal trace. However, the profile will be a phase modulated signal when the shaft speed is varied. By applying a demodulating procedure, the AS can be obtained in a straightforward manner. The sensor system was validated experimentally based on a gearbox test rig and the result shows that the AS obtained are consistent with that obtained by a conventional encoder. However, the new sensor gives very smooth and stable traces of the AS, demonstrating its higher accuracy and reliability in obtaining the AS of the low speed operations with speed-up and down transients. In addition, the experiment also shows that it is easy and cost-effective to be realised in different applications such as condition monitoring and process control. PMID:24517806

  19. A simple and reliable sensor for accurate measurement of angular speed for low speed rotating machinery

    NASA Astrophysics Data System (ADS)

    Kuosheng, Jiang; Guanghua, Xu; Tangfei, Tao; Lin, Liang; Yi, Wang; Sicong, Zhang; Ailing, Luo

    2014-01-01

    This paper presents the theory and implementation of a novel sensor system for measuring the angular speed (AS) of a shaft rotating at a very low speed range, nearly zero speed. The sensor system consists mainly of an eccentric sleeve rotating with the shaft on which the angular speed to be measured, and an eddy current displacement sensor to obtain the profile of the sleeve for AS calculation. When the shaft rotates at constant speed the profile will be a pure sinusoidal trace. However, the profile will be a phase modulated signal when the shaft speed is varied. By applying a demodulating procedure, the AS can be obtained in a straightforward manner. The sensor system was validated experimentally based on a gearbox test rig and the result shows that the AS obtained are consistent with that obtained by a conventional encoder. However, the new sensor gives very smooth and stable traces of the AS, demonstrating its higher accuracy and reliability in obtaining the AS of the low speed operations with speed-up and down transients. In addition, the experiment also shows that it is easy and cost-effective to be realised in different applications such as condition monitoring and process control.

  20. Recent Advances in Highly Accurate Range Measurements with TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Eineder, Michael; Balss, Ulrich; Gisinger, Christoph; Cong, Xiao Ying; Brcic, Ramon; Steigenberger, Peter

    2013-04-01

    Earth surface displacement measurement from space using Synthetic Aperture Radar (SAR) imagery is an interesting alternative to SAR interferometry (InSAR). The advantages are that 2D information can be retrieved (InSAR only 1D), absolute displacements can be retrieved (no reference point required) and it is very robust (phase unwrapping not required). On the other hand, the accuracy is limited by the pixel resolution, the object contrast, the orbit accuracy, by wave propagation distortion and by geodetic effects. Therefore the accuracy was more in the meter / decimeter level in the past, compared to millimeter accuracy of InSAR. During the recent years our team established a test and validation site at the geodetic observatory Wettzell, Germany and developed compensation methods to reduce the overall error of absolute range measurements from decimeters to only one centimeter. The methods include correction of dry and wet atmospheric delays, ionospheric corrections, solid earth tides, continental drift, atmospheric pressure loading and ocean tidal loading. For more one year a radar reflector was monitored and each image evaluated. Our presentation gives and overview of methods and achieved results. Futhermore, examples of real world applications and an outlook on more applications is given such as phase unwrapping augmentation.

  1. Measurement of Blood Volume in Adult Rhesus Macaques (Macaca mulatta)

    PubMed Central

    Hobbs, Theodore R; Blue, Steven W; Park, Byung S; Greisel, Jennifer J; Conn, P Michael; Pau, Francis K-Y

    2015-01-01

    Most biomedical facilities that use rhesus macaques (Macaca mulatta) limit the amount of blood that may be collected for experimental purposes. These limits typically are expressed as a percentage of blood volume (BV), estimated by using a fixed ratio of blood (mL) per body weight (kg). BV estimation ratios vary widely among facilities and typically do not factor in variables known to influence BV in humans: sex, age, and body condition. We used indicator dilution methodology to determine the BV of 20 adult rhesus macaques (10 male, 10 female) that varied widely in body condition. We measured body composition by using dual-energy X-ray absorptiometry, weight, crown-to-rump length, and body condition score. Two indicators, FITC-labeled hydroxyethyl starch (FITC–HES) and radioiodinated rhesus serum albumin (125I-RhSA), were injected simultaneously, followed by serial blood collection. Plasma volume at time 0 was determined by linear regression. BV was calculated from the plasma volume and Hct. We found that BV calculated by using FITC–HES was consistently lower than BV calculated by using 125I-RhSA. Sex and age did not significantly affect BV. Percentage body fat was significantly associated with BV. Subjects categorized as having ‘optimal’ body condition score had 18% body fat and 62.1 mL/kg BV (by FITC–HES; 74.5 mL/kg by 125I-RhSA). Each 1% increase in body fat corresponded to approximately 1 mL/kg decrease in BV. Body condition score correlated with the body fat percentage (R2 = 0.7469). We provide an equation for calculating BV from weight and body condition score. PMID:26632777

  2. Geometric Measures of Large Biomolecules: Surface, Volume and Pockets

    PubMed Central

    Mach, Paul; Koehl, Patrice

    2011-01-01

    Geometry plays a major role in our attempt to understand the activity of large molecules. For example, surface area and volume are used to quantify the interactions between these molecules and the water surrounding them in implicit solvent models. In addition, the detection of pockets serves as a starting point for predictive studies of biomolecule-ligand interactions. The alpha shape theory provides an exact and robust method for computing these geometric measures. Several implementations of this theory are currently available. We show however that these implementations fail on very large macromolecular systems. We show that these difficulties are not theoretical; rather, they are related to the architecture of current computers that rely on the use of cache memory to speed up calculation. By rewriting the algorithms that implement the different steps of the alpha shape theory such that we enforce locality, we show that we can remediate these cache problems; the corresponding code, UnionBall has an apparent (n) behavior over a large range of values of n (up to tens of millions), where n is the number of atoms. As an example, it takes 136 seconds with UnionBall to compute the contribution of each atom to the surface area and volume of a viral capsid with more than five million atoms on a commodity PC. UnionBall includes functions for computing the surface area and volume of the intersection of two, three and four spheres that are fully detailed in an appendix. UnionBall is available as an OpenSource software. PMID:21823134

  3. Measurement of Blood Volume in Adult Rhesus Macaques (Macaca mulatta).

    PubMed

    Hobbs, Theodore R; Blue, Steven W; Park, Byung S; Greisel, Jennifer J; Conn, P Michael; Pau, Francis K-Y

    2015-11-01

    Most biomedical facilities that use rhesus macaques (Macaca mulatta) limit the amount of blood that may be collected for experimental purposes. These limits typically are expressed as a percentage of blood volume (BV), estimated by using a fixed ratio of blood (mL) per body weight (kg). BV estimation ratios vary widely among facilities and typically do not factor in variables known to influence BV in humans: sex, age, and body condition. We used indicator dilution methodology to determine the BV of 20 adult rhesus macaques (10 male, 10 female) that varied widely in body condition. We measured body composition by using dual-energy X-ray absorptiometry, weight, crown-to-rump length, and body condition score. Two indicators, FITC-labeled hydroxyethyl starch (FITC-HES) and radioiodinated rhesus serum albumin ((125)I-RhSA), were injected simultaneously, followed by serial blood collection. Plasma volume at time 0 was determined by linear regression. BV was calculated from the plasma volume and Hct. We found that BV calculated by using FITC-HES was consistently lower than BV calculated by using (125)I-RhSA. Sex and age did not significantly affect BV. Percentage body fat was significantly associated with BV. Subjects categorized as having 'optimal' body condition score had 18% body fat and 62.1 mL/kg BV (by FITC-HES; 74.5 mL/kg by (125)I-RhSA). Each 1% increase in body fat corresponded to approximately 1 mL/kg decrease in BV. Body condition score correlated with the body fat percentage (R(2) = 0.7469). We provide an equation for calculating BV from weight and body condition score. PMID:26632777

  4. Development of Accurate Chemical Equilibrium Models for the Hanford Waste Tanks: New Thermodynamic Measurements and Model Applications

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin; Qafoku, Odeta; Xia, Yuanxian; Wang, Zheming; MacLean, Graham

    2003-03-27

    Developing accurate thermodynamic models for predicting the chemistry of the high-level waste tanks at Hanford is an extremely daunting challenge in electrolyte and radionuclide chemistry. These challenges stem from the extremely high ionic strength of the tank waste supernatants, presence of chelating agents in selected tanks, wide temperature range in processing conditions and the presence of important actinide species in multiple oxidation states. This presentation summarizes progress made to date in developing accurate models for these tank waste solutions, how these data are being used at Hanford and the important challenges that remain. New thermodynamic measurements on Sr and actinide complexation with specific chelating agents (EDTA, HEDTA and gluconate) will also be presented.

  5. Combined atomic force microscopy and voltage pulse technique to accurately measure electrostatic force

    NASA Astrophysics Data System (ADS)

    Inami, Eiichi; Sugimoto, Yoshiaki

    2016-08-01

    We propose a new method of extracting electrostatic force. The technique is based on frequency modulation atomic force microscopy (FM-AFM) combined with a voltage pulse. In this method, the work that the electrostatic field does on the oscillating tip is measured through the cantilever energy dissipation. This allows us to directly extract capacitive forces including the longer range part, to which the conventional FM-AFM is insensitive. The distance-dependent contact potential difference, which is modulated by local charges distributed on the surfaces of the tip and/or sample, could also be correctly obtained. In the absence of local charges, our method can perfectly reproduce the electrostatic force as a function of the distance and the bias voltage. Furthermore, we demonstrate that the system serves as a sensitive sensor enabling us to check the existence of the local charges such as trapped charges and patch charges.

  6. Measurements of accurate x-ray scattering data of protein solutions using small stationary sample cells

    SciTech Connect

    Hong Xinguo; Hao Quan

    2009-01-15

    In this paper, we report a method of precise in situ x-ray scattering measurements on protein solutions using small stationary sample cells. Although reduction in the radiation damage induced by intense synchrotron radiation sources is indispensable for the correct interpretation of scattering data, there is still a lack of effective methods to overcome radiation-induced aggregation and extract scattering profiles free from chemical or structural damage. It is found that radiation-induced aggregation mainly begins on the surface of the sample cell and grows along the beam path; the diameter of the damaged region is comparable to the x-ray beam size. Radiation-induced aggregation can be effectively avoided by using a two-dimensional scan (2D mode), with an interval as small as 1.5 times the beam size, at low temperature (e.g., 4 deg. C). A radiation sensitive protein, bovine hemoglobin, was used to test the method. A standard deviation of less than 5% in the small angle region was observed from a series of nine spectra recorded in 2D mode, in contrast to the intensity variation seen using the conventional stationary technique, which can exceed 100%. Wide-angle x-ray scattering data were collected at a standard macromolecular diffraction station using the same data collection protocol and showed a good signal/noise ratio (better than the reported data on the same protein using a flow cell). The results indicate that this method is an effective approach for obtaining precise measurements of protein solution scattering.

  7. Reheating-volume measure in the string theory landscape

    SciTech Connect

    Winitzki, Sergei

    2008-12-15

    I recently proposed the ''reheating-volume'' (RV) prescription as a possible solution to the measure problem in ''multiverse'' cosmology. The goal of this work is to extend the RV measure to scenarios involving bubble nucleation, such as the string theory landscape. In the spirit of the RV prescription, I propose to calculate the distribution of observable quantities in a landscape that is conditioned in probability to nucleate a finite total number of bubbles to the future of an initial bubble. A general formula for the relative number of bubbles of different types can be derived. I show that the RV measure is well defined and independent of the choice of the initial bubble type, as long as that type supports further bubble nucleation. Applying the RV measure to a generic landscape, I find that the abundance of Boltzmann brains is always negligibly small compared with the abundance of ordinary observers in the bubbles of the same type. As an illustration, I present explicit results for a toy landscape containing four vacuum states, and for landscapes with a single high-energy vacuum and a large number of low-energy vacua.

  8. Method for Measuring the Volume-Scattering Function of Water

    NASA Technical Reports Server (NTRS)

    Agrawal, Yogesh C.

    2009-01-01

    The volume scattering function (VSF) of seawater affects visibility, remote sensing properties, in-water light propagation, lidar performance, and the like. Currently, it s possible to measure only small forward angles of VSF, or to use cumbersome, large, and non-autonomous systems. This innovation is a method of measuring the full range of VSF using a portable instrument. A single rapid-sensing photosensor is used to scan a green laser beam, which delivers the desired measurement. By using a single sensor, inter-calibration is avoided. A compact design is achieved by using drift-free detector electronics, fiber optics, and a new type of photomultiplier. This provides a high angular resolution of 1 or better, as well as the ability to focus in on a VSF region of particular interest. Currently, the total scattering of light is measured as a difference from the other two parts of the light budget equation. This innovation will allow the direct calculation of the total scattering of light by taking an integral of the VSF over all angles. This directly provides one of the three components of the light budget equation, allowing greater versatility in its calculation.

  9. Accurate assessment of whole-body retention for PRRT with (177)Lu using paired measurements with external detectors.

    PubMed

    Liu, Boxue; de Blois, Erik; Breeman, Wouter A P; Konijnenberg, Mark W; Wolterbeek, Hubert T; Bode, Peter

    2015-01-01

    The aim of this study was to assess the accuracy of the results of whole-body measurements by comparison with the urine collection method in the PRRT with (177)Lu and furthermore to develop a more accurate method of paired measurements. Excreted samples were collected at given intervals and activities were measured by a dose calibrator. Traditionally, whole-body activities during subsequent measurements are normalized individually to the administered activity. In order to correct for the effects of the activity in the bladder during the baseline measurement before the first voiding and activity redistributions in the patient body during subsequent measurements, a series of paired measurements before and after each voiding were carried out. Time-dependent detector responses at given times were derived and time-activity retentions were then determined. Compared to the results of the urine collection, whole-body activities by traditional whole-body measurements were overestimated by ca. 14% at 1 h after administration and randomly varied from -29% to 49% at 24 h. Measurement uncertainties of whole-body activities were from ± 4% (the coverage factor k=2) at 1 h to >± 20% at 24 h by the urine collection and ± 7% by paired measurements, respectively. Whole-body activities at 1 h by paired measurements were validated using the results by measurements of the collected first urine. The new method of paired measurements has an equivalent measurement accuracy and even better during the later measurements with respect to the urine collection method and therefore can replace urine approach for assessing the time-activity remaining in the patient body. PMID:25771370

  10. Underreporting of patient safety incidents reduces health care's ability to quantify and accurately measure harm reduction.

    PubMed

    Noble, Douglas J; Pronovost, Peter J

    2010-12-01

    Underreporting of patient safety incidents creates a reservoir of information that is plagued with epidemiological bias. These include systematic biases such as the practice of reporting minor incidents at the expense of more serious ones. This leads to inaccurate rates of errors and an inability to generalize results to whole patient populations. It leaves reporting incidents, in epidemiological terms, comparable to nonrandom samples from an unknown universe of events. These epidemiological problems lead to a situation where priorities are skewed toward what "we know we know." As "we know what we do not know," for example, gaps in knowledge about serious incidents due to low reporting rates, due caution must be applied in making policy based on biased underreporting. Barriers to reporting contribute to low participation rates and further bias information. Lack of feedback and fear of personal consequences are common barriers. Evaluation of reporting systems indicates reports can be used as tools for learning, but it is not yet possible to monitor improvement in patient safety or measurably prove reduction in harm. Mandatory reporting makes sense from an epidemiological point of view, but there are legitimate fears that it could further reduce reporting rates due to fear of reprisal. Underreporting and the associated biases are a significant problem in realizing the epidemiological potential of incident reporting in health care. PMID:21500613

  11. Accurate measurement of the sticking time and sticking probability of Rb atoms on a polydimethylsiloxane coating

    SciTech Connect

    Atutov, S. N. Plekhanov, A. I.

    2015-01-15

    We present the results of a systematic study of Knudsen’s flow of Rb atoms in cylindrical capillary cells coated with a polydimethylsiloxane (PDMS) compound. The purpose of the investigation is to determine the characterization of the coating in terms of the sticking probability and sticking time of Rb on the two types of coating of high and medium viscosities. We report the measurement of the sticking probability of a Rb atom to the coating equal to 4.3 × 10{sup −5}, which corresponds to the number of bounces 2.3 × 10{sup 4} at room temperature. These parameters are the same for the two kinds of PDMS used. We find that at room temperature, the respective sticking times for high-viscosity and medium-viscosity PDMS are 22 ± 3 μs and 49 ± 6 μs. These sticking times are about million times larger than the sticking time derived from the surface Rb atom adsorption energy and temperature of the coating. A tentative explanation of this surprising result is proposed based on the bulk diffusion of the atoms that collide with the surface and penetrate inside the coating. The results can be important in many resonance cell experiments, such as the efficient magnetooptical trapping of rare elements or radioactive isotopes and in experiments on the light-induced drift effect.

  12. EZ-Rhizo: integrated software for the fast and accurate measurement of root system architecture.

    PubMed

    Armengaud, Patrick; Zambaux, Kevin; Hills, Adrian; Sulpice, Ronan; Pattison, Richard J; Blatt, Michael R; Amtmann, Anna

    2009-03-01

    The root system is essential for the growth and development of plants. In addition to anchoring the plant in the ground, it is the site of uptake of water and minerals from the soil. Plant root systems show an astonishing plasticity in their architecture, which allows for optimal exploitation of diverse soil structures and conditions. The signalling pathways that enable plants to sense and respond to changes in soil conditions, in particular nutrient supply, are a topic of intensive research, and root system architecture (RSA) is an important and obvious phenotypic output. At present, the quantitative description of RSA is labour intensive and time consuming, even using the currently available software, and the lack of a fast RSA measuring tool hampers forward and quantitative genetics studies. Here, we describe EZ-Rhizo: a Windows-integrated and semi-automated computer program designed to detect and quantify multiple RSA parameters from plants growing on a solid support medium. The method is non-invasive, enabling the user to follow RSA development over time. We have successfully applied EZ-Rhizo to evaluate natural variation in RSA across 23 Arabidopsis thaliana accessions, and have identified new RSA determinants as a basis for future quantitative trait locus (QTL) analysis. PMID:19000163

  13. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (Oil and Gas Operations Report), in accordance with 30 CFR 1210.102. (1) You must report the amount of... volumes and liquid hydrocarbon burning volumes, and what records must I maintain? 250.1163 Section 250... Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or...

  14. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (Oil and Gas Operations Report), in accordance with 30 CFR 1210.102. (1) You must report the amount of... volumes and liquid hydrocarbon burning volumes, and what records must I maintain? 250.1163 Section 250... Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or...

  15. 30 CFR 250.1163 - How must I measure gas flaring or venting volumes and liquid hydrocarbon burning volumes, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (Oil and Gas Operations Report), in accordance with 30 CFR 1210.102. (1) You must report the amount of... volumes and liquid hydrocarbon burning volumes, and what records must I maintain? 250.1163 Section 250... Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1163 How must I measure gas flaring or...

  16. Towards More Accurate Measurements of the Ionization Energy of Molecular Hydrogen

    NASA Astrophysics Data System (ADS)

    Sprecher, D.; Beyer, M.; Liu, J.; Merkt, F.; Salumbides, E.; Eikema, K. S. E.; Ubachs, W.; Jungen, Ch.

    2013-06-01

    With two electrons and two protons, molecular hydrogen is the simplest molecule displaying all features of a chemical bond. H_2 is therefore a fundamental system for testing molecular quantum mechanics and quantum electrodynamics in molecules. The test can be performed by comparing measured and calculated intervals between different rovibronic states of H_2. Two further quantities that can be used for this test are the dissociation and ionization energies of H_2, and considerable efforts have been invested over more than 80 years to improve the precision and accuracy of experimental and theoretical determination of these two quantities. The current status of the comparison is that the theoretical and experimental values of the ionization and dissociation energies of H_2 agree within the combined uncertainty of 30 MHz (see also). The factors currently limiting the precision of the experimental determination will be discussed and the strategies that are being implemented towards overcoming these limitations will be presented. A long-term goal is to achieve a precision of better than 15 kHz, which is the ultimate limit imposed on the accuracy of the theoretical determination by the current uncertainty of the proton-to-electron mass ratio. E. J. Salumbides, G. D. Dickenson, T. I. Ivanov and W. Ubachs, {Phys. Rev. Lett.} 107 (4), 043005 (2011). K. Piszczatowski, G. Lach, M. Przybytek, J. Komasa, K. Pachuckiand and B. Jeziorski, {J. Chem. Theory Comput.} 5 (11), 3039 (2009). J. Liu, E. J. Salumbides, U. Hollenstein, J. C. J. Koelemeij, K. S. E. Eikema, W. Ubachs and F. Merkt, {J. Chem. Phys.} 130 (17), 174306 (2009). D. Sprecher, Ch. Jungen, W. Ubachs and F. Merkt, {Faraday Discuss.} 150, 51 (2011).

  17. Simultaneous, accurate measurement of the 3D position and orientation of single molecules

    PubMed Central

    Backlund, Mikael P.; Lew, Matthew D.; Backer, Adam S.; Sahl, Steffen J.; Grover, Ginni; Agrawal, Anurag; Piestun, Rafael; Moerner, W. E.

    2012-01-01

    Recently, single molecule-based superresolution fluorescence microscopy has surpassed the diffraction limit to improve resolution to the order of 20 nm or better. These methods typically use image fitting that assumes an isotropic emission pattern from the single emitters as well as control of the emitter concentration. However, anisotropic single-molecule emission patterns arise from the transition dipole when it is rotationally immobile, depending highly on the molecule’s 3D orientation and z position. Failure to account for this fact can lead to significant lateral (x, y) mislocalizations (up to ∼50–200 nm). This systematic error can cause distortions in the reconstructed images, which can translate into degraded resolution. Using parameters uniquely inherent in the double-lobed nature of the Double-Helix Point Spread Function, we account for such mislocalizations and simultaneously measure 3D molecular orientation and 3D position. Mislocalizations during an axial scan of a single molecule manifest themselves as an apparent lateral shift in its position, which causes the standard deviation (SD) of its lateral position to appear larger than the SD expected from photon shot noise. By correcting each localization based on an estimated orientation, we are able to improve SDs in lateral localization from ∼2× worse than photon-limited precision (48 vs. 25 nm) to within 5 nm of photon-limited precision. Furthermore, by averaging many estimations of orientation over different depths, we are able to improve from a lateral SD of 116 (∼4× worse than the photon-limited precision; 28 nm) to 34 nm (within 6 nm of the photon limit). PMID:23129640

  18. How accurately can we measure the water vapour content with astronomical spectra?

    NASA Astrophysics Data System (ADS)

    Kausch, Wolfgang; Noll, Stefan; Smette, Alain; Kimeswenger, Stefan; Kerber, Florian; Jones, Amy M.; Szyszka, Cezary; Unterguggenberger, Stefanie

    2014-05-01

    Light from astronomical objects unavoidably has to pass through the Earth's atmosphere when being observed by ground-based telescopes. Thus, the fingerprint of the atmospheric state at the time of the observation is present in any spectrum taken by astronomical spectrographs due to absorption and emission arising in the atmosphere. The Very Large Telescope (VLT), operated by the European Southern Observatory, is one of the world's largest telescope facilities located at Cerro Paranal in the Chilean Atacama Desert offering a wide selection of various instruments. One of the most versatile instruments is X-Shooter. This medium resolution Echelle spectrograph covers the entire wavelength regime from 0.3 to 2.5 μm and is mounted on one of the 8m-class telescopes of the VLT. Due to its versatility, it is widely used, which leads to a good temporal coverage. We have recently developed the software package molecfit, a tool used to model and correct for atmospheric absorption lines visible in astronomical spectra. It is based on the radiative transfer code LBLRTM, the HITRAN line parameter database, the GDAS atmospheric profiles, and local meteorological data. A by-product is the determination of the amount of precipitable water vapour (PWV) above the observatory, as well as several other molecules, including CO2. In this poster, we investigate the accuracy of this method. We have used a set of X-Shooter spectra of so-called telluric standard stars, which are hot and bright stars showing nearly no intrinsic spectral features in the near infrared regime. Thus, most absorption features present in these spectra are related to the absorption arising in the Earth's atmosphere. For each spectrum, we have determined the PWV with our molecfit code and compared it with direct measurements achieved by the LHATPRO radiometer recently installed at Cerro Paranal. Therefore we have extended the results obtained by Kerber et al. (2012, Proc. SPIE, 8446) on a long time scale. Due to the

  19. ESR measurement of time-dependent and equilibrium volumes in red cells.

    PubMed

    Moronne, M M; Mehlhorn, R J; Miller, M P; Ackerson, L C; Macey, R I

    1990-04-01

    Red cell water volumes were measured using ESR methods during transient osmotic perturbation, and under equilibrium conditions. Cell water contents were determined using the spin label Tempone (2,2,6,6-tetramethyl piperidine-N-oxyl) and the membrane impermeable quencher potassium chromium oxalate. With appropriate corrections for intracellular viscosity and changes in cavity sensitivity, equilibrium cell water measured both by electron spin resonance (ESR) and wet minus dry weight methods gave excellent agreement in solutions from 243-907 mOsm. Intracellular viscosities determined from the Tempone correlation times in the same cells gave values ranging from 9-47 centipoise at 21 degrees C. Osmotically induced transient volume changes were measured using Tempone and an ESR stopped-flow configuration. The Tempone response time was estimated at 17 msec compared to 250-350 msec for normal water relaxations. Nonlinear least square solutions to the Kedem-Katchalsky equations including a correction for the finite Tempone permeability gave 0.029 and 0.030 cm/sec for the osmotic permeability of RBCs in swell and shrink experiments, respectively. In stopped-flow experiments accurate water flux data are obtained very soon after challenging cells and do not require baseline subtractions. These results represent significant improvements over conventional light scattering techniques which necessitate corrections for long lasting optical artifacts (200-300 msec), and baseline drifts. PMID:2159519

  20. Fast and accurate near-field - far-field transformation by sampling interpolation of plane-polar measurements

    NASA Astrophysics Data System (ADS)

    Bucci, Ovidio M.; Gennarelli, Claudio; Savarese, Catello

    1991-01-01

    An optimal sampling interpolation algorithm which allows the accurate recovery of plane-rectangular near-field samples from the knowledge of the plane-polar ones is developed. This enables the standard near field-far field (NF-FF) transformation, which takes full advantage of the FFT algorithm, to be applied to plane-polar scanning. The maximum allowable sample spacing is also rigorously derived, and it is shown that it can be significantly greater than lambda/2 as the measurement place moves away from the source. This allows a remarkable reduction of both measurement time and memory storage requirements. The sampling approach is compared with that based on the bivariate Lagrange interpolation (BLI) method. The sampling reconstruction agrees with the exact results significantly better than the BLI, in spite of the significantly lower number of required measurements.

  1. Compensation method for obtaining accurate, sub-micrometer displacement measurements of immersed specimens using electronic speckle interferometry

    PubMed Central

    Fazio, Massimo A.; Bruno, Luigi; Reynaud, Juan F.; Poggialini, Andrea; Downs, J. Crawford

    2012-01-01

    We proposed and validated a compensation method that accounts for the optical distortion inherent in measuring displacements on specimens immersed in aqueous solution. A spherically-shaped rubber specimen was mounted and pressurized on a custom apparatus, with the resulting surface displacements recorded using electronic speckle pattern interferometry (ESPI). Point-to-point light direction computation is achieved by a ray-tracing strategy coupled with customized B-spline-based analytical representation of the specimen shape. The compensation method reduced the mean magnitude of the displacement error induced by the optical distortion from 35% to 3%, and ESPI displacement measurement repeatability showed a mean variance of 16 nm at the 95% confidence level for immersed specimens. The ESPI interferometer and numerical data analysis procedure presented herein provide reliable, accurate, and repeatable measurement of sub-micrometer deformations obtained from pressurization tests of spherically-shaped specimens immersed in aqueous salt solution. This method can be used to quantify small deformations in biological tissue samples under load, while maintaining the hydration necessary to ensure accurate material property assessment. PMID:22435090

  2. 3D thoracoscopic ultrasound volume measurement validation in an ex vivo and in vivo porcine model of lung tumours

    NASA Astrophysics Data System (ADS)

    Hornblower, V. D. M.; Yu, E.; Fenster, A.; Battista, J. J.; Malthaner, R. A.

    2007-01-01

    The purpose of this study was to validate the accuracy and reliability of volume measurements obtained using three-dimensional (3D) thoracoscopic ultrasound (US) imaging. Artificial 'tumours' were created by injecting a liquid agar mixture into spherical moulds of known volume. Once solidified, the 'tumours' were implanted into the lung tissue in both a porcine lung sample ex vivo and a surgical porcine model in vivo. 3D US images were created by mechanically rotating the thoracoscopic ultrasound probe about its long axis while the transducer was maintained in close contact with the tissue. Volume measurements were made by one observer using the ultrasound images and a manual-radial segmentation technique and these were compared with the known volumes of the agar. In vitro measurements had average accuracy and precision of 4.76% and 1.77%, respectively; in vivo measurements had average accuracy and precision of 8.18% and 1.75%, respectively. The 3D thoracoscopic ultrasound can be used to accurately and reproducibly measure 'tumour' volumes both in vivo and ex vivo.

  3. A precision translation stage for reproducing measured target volume motions.

    PubMed

    Litzenberg, Dale W; Hadley, Scott W; Lam, Kwok L; Balter, James M

    2007-01-01

    The development of 4D imaging, treatment planning and treatment delivery methods for radiation therapy require the use of a high-precision translation stage for testing and validation. These technologies may require spatial resolutions of 1 mm, and temporal resolutions of 2-30 Hz for CT imaging, electromagnetic tracking, and fluoroscopic imaging. A 1D programmable translation stage capable of reproducing idealized and measured anatomic motions common to the thorax has been design and built to meet these spatial and temporal resolution requirement with phantoms weighing up to 27 kg. The stage consists of a polycarbonate base and table, driven by an AC servo motor with encoder feedback by means of a belt-coupled precision screw. Complex motions are possible through a programmable motion controller that is capable of running multiple independent control and monitoring programs concurrently. Programmable input and output ports allow motion to be synchronized with beam delivery and other imaging and treatment delivery devices to within 2.0 ms. Average deviations from the programmed positions are typically 0.2 mm or less, while the average typical maximum positional errors are typically 0.5 mm for an indefinite number of idealized breathing motion cycles and while reproducing measured target volume motions for several minutes. PMID:17712294

  4. New Measurements of Activation Volume in Olvine Under Anhydrous Conditions

    SciTech Connect

    Durham, W.; Mei, S; Kohlstedt, D; Wang, L; Dixon, N

    2009-01-01

    A new cell assembly for the deformation-DIA (D-DIA) shows promise for limiting the water content of samples and providing a more mechanically stable environment for deformation. The 6-mm cubic cell consists of a 6-mm diameter mullite sphere cradled in a web of unfired pyrophyllite. The pyrophyllite flows during initial compression of the D-DIA to form gaskets between the six anvils while the mullite flows to become a nearly cubic-shaped pressure medium. Measurements on olivine indicate more than one order of magnitude drop in water content to <40 ppm H/Si compared with the boron-epoxy medium. Improved mechanical stability is achieved by elimination of the thermocouple from the assembly and determination of temperature from calibration curves of furnace power vs. temperature. Three samples of polycrystalline orthopyroxene-buffer San Carlos olivine have been deformed in high-temperature creep in the new cell, at pressures of 2.7-4.9 GPa and temperatures near 1473 K. Strength is consistent with that measured in the gas-apparatus at lower pressures. Over the pressure range investigated we resolve an activation volume for creep of dry olivine of V* = 9.5 {+-} 7 x 10-6 m3/mol.

  5. An accurate Rb density measurement method for a plasma wakefield accelerator experiment using a novel Rb reservoir

    NASA Astrophysics Data System (ADS)

    Öz, E.; Batsch, F.; Muggli, P.

    2016-09-01

    A method to accurately measure the density of Rb vapor is described. We plan on using this method for the Advanced Wakefield (AWAKE) (Assmann et al., 2014 [1]) project at CERN , which will be the world's first proton driven plasma wakefield experiment. The method is similar to the hook (Marlow, 1967 [2]) method and has been described in great detail in the work by Hill et al. (1986) [3]. In this method a cosine fit is applied to the interferogram to obtain a relative accuracy on the order of 1% for the vapor density-length product. A single-mode, fiber-based, Mach-Zenhder interferometer will be built and used near the ends of the 10 meter-long AWAKE plasma source to be able to make accurate relative density measurement between these two locations. This can then be used to infer the vapor density gradient along the AWAKE plasma source and also change it to the value desired for the plasma wakefield experiment. Here we describe the plan in detail and show preliminary results obtained using a prototype 8 cm long novel Rb vapor cell.

  6. Studies with nonradioisotopic sodium chromate. I. Development of a technique for measuring red cell volume

    SciTech Connect

    Heaton, W.A.; Hanbury, C.M.; Keegan, T.E.; Pleban, P.; Holme, S. )

    1989-10-01

    A nonradioisotopic method for measuring red cell volume that involves the use of 52Cr-sodium chromate as the red cell label and of graphite furnace atomic absorption analysis of chromium is described. The technique allows the labelling of 20 mL of packed red cells with 40 to 50 micrograms of sodium chromate (Na2CrO4) in 30 minutes at 22 degrees C with 94 +/- 6 percent uptake. Approximately 40 micrograms of Na2CrO4 was injected for in vivo studies. This results in posttransfusion in vivo red cell chromium levels after sample processing in the range of 1 to 7 micrograms per L, which could be quantitated accurately (coefficient of variation = 4.7%) by Zeeman electrothermal atomic absorption spectrophotometry. The labeling concentration of chromium did not cause increased hemolysis, and the labeled cells exhibited an osmotic fragility curve similar to that of unlabeled, fresh ACD red cells. Red cell glutathione peroxidase was unaffected by labeling, although glutathione reductase was reduced by approximately 13 percent (p less than 0.05). The 52Cr red cell volume-measuring method was evaluated by concurrent in vivo studies with the standard 51Cr and 125I-albumin methods for that procedure. Simultaneous measurement of red cell volumes in seven volunteers by the 51Cr, 52Cr, and 125I-albumin techniques correlated highly with each other (r greater than 0.76), with mean values of 2294 +/- 199, 2191 +/- 180, and 2243 +/- 291 mL, respectively. The standard deviations of the differences were small: 134 mL for 52Cr versus 51Cr and 183 mL for 52Cr versus 125I.

  7. Dipstick Spot urine pH does not accurately represent 24 hour urine PH measured by an electrode

    PubMed Central

    Omar, Mohamed; Sarkissian, Carl; Jianbo, Li; Calle, Juan; Monga, Manoj

    2016-01-01

    ABSTRACT Objectives To determine whether spot urine pH measured by dipstick is an accurate representation of 24 hours urine pH measured by an electrode. Materials and Methods We retrospectively reviewed urine pH results of patients who presented to the urology stone clinic. For each patient we recorded the most recent pH result measured by dipstick from a spot urine sample that preceded the result of a 24-hour urine pH measured by the use of a pH electrode. Patients were excluded if there was a change in medications or dietary recommendations or if the two samples were more than 4 months apart. A difference of more than 0.5 pH was considered an inaccurate result. Results A total 600 patients were retrospectively reviewed for the pH results. The mean difference in pH between spot urine value and the 24 hours collection values was 0.52±0.45 pH. Higher pH was associated with lower accuracy (p<0.001). The accuracy of spot urine samples to predict 24-hour pH values of <5.5 was 68.9%, 68.2% for 5.5 to 6.5 and 35% for >6.5. Samples taken more than 75 days apart had only 49% the accuracy of more recent samples (p<0.002). The overall accuracy is lower than 80% (p<0.001). Influence of diurnal variation was not significant (p=0.588). Conclusions Spot urine pH by dipstick is not an accurate method for evaluation of the patients with urolithiasis. Patients with alkaline urine are more prone to error with reliance on spot urine pH. PMID:27286119

  8. Accurate measurements of cross-plane thermal conductivity of thin films by dual-frequency time-domain thermoreflectance (TDTR)

    NASA Astrophysics Data System (ADS)

    Jiang, Puqing; Huang, Bin; Koh, Yee Kan

    2016-07-01

    Accurate measurements of the cross-plane thermal conductivity Λcross of a high-thermal-conductivity thin film on a low-thermal-conductivity (Λs) substrate (e.g., Λcross/Λs > 20) are challenging, due to the low thermal resistance of the thin film compared with that of the substrate. In principle, Λcross could be measured by time-domain thermoreflectance (TDTR), using a high modulation frequency fh and a large laser spot size. However, with one TDTR measurement at fh, the uncertainty of the TDTR measurement is usually high due to low sensitivity of TDTR signals to Λcross and high sensitivity to the thickness hAl of Al transducer deposited on the sample for TDTR measurements. We observe that in most TDTR measurements, the sensitivity to hAl only depends weakly on the modulation frequency f. Thus, we performed an additional TDTR measurement at a low modulation frequency f0, such that the sensitivity to hAl is comparable but the sensitivity to Λcross is near zero. We then analyze the ratio of the TDTR signals at fh to that at f0, and thus significantly improve the accuracy of our Λcross measurements. As a demonstration of the dual-frequency approach, we measured the cross-plane thermal conductivity of a 400-nm-thick nickel-iron alloy film and a 3-μm-thick Cu film, both with an accuracy of ˜10%. The dual-frequency TDTR approach is useful for future studies of thin films.

  9. Accurate measurements of cross-plane thermal conductivity of thin films by dual-frequency time-domain thermoreflectance (TDTR).

    PubMed

    Jiang, Puqing; Huang, Bin; Koh, Yee Kan

    2016-07-01

    Accurate measurements of the cross-plane thermal conductivity Λcross of a high-thermal-conductivity thin film on a low-thermal-conductivity (Λs) substrate (e.g., Λcross/Λs > 20) are challenging, due to the low thermal resistance of the thin film compared with that of the substrate. In principle, Λcross could be measured by time-domain thermoreflectance (TDTR), using a high modulation frequency fh and a large laser spot size. However, with one TDTR measurement at fh, the uncertainty of the TDTR measurement is usually high due to low sensitivity of TDTR signals to Λcross and high sensitivity to the thickness hAl of Al transducer deposited on the sample for TDTR measurements. We observe that in most TDTR measurements, the sensitivity to hAl only depends weakly on the modulation frequency f. Thus, we performed an additional TDTR measurement at a low modulation frequency f0, such that the sensitivity to hAl is comparable but the sensitivity to Λcross is near zero. We then analyze the ratio of the TDTR signals at fh to that at f0, and thus significantly improve the accuracy of our Λcross measurements. As a demonstration of the dual-frequency approach, we measured the cross-plane thermal conductivity of a 400-nm-thick nickel-iron alloy film and a 3-μm-thick Cu film, both with an accuracy of ∼10%. The dual-frequency TDTR approach is useful for future studies of thin films. PMID:27475589

  10. Primary Teachers' Conceptions about the Concept of Volume: The Case of Volume-Measurable Objects

    ERIC Educational Resources Information Center

    Saiz, Mariana

    2003-01-01

    In this paper part of the results obtained by a research project called "Primary Teachers' Thinking about the Concept of Volume and its Teaching", performed from 1997 to 2001, are reported. This paper focuses in one of the two main objectives of the aforementioned research: To describe the mental object volume of the participant teachers. The…

  11. Measuring Physical Inactivity: Do Current Measures Provide an Accurate View of “Sedentary” Video Game Time?

    PubMed Central

    Fullerton, Simon; Taylor, Anne W.; Dal Grande, Eleonora; Berry, Narelle

    2014-01-01

    Background. Measures of screen time are often used to assess sedentary behaviour. Participation in activity-based video games (exergames) can contribute to estimates of screen time, as current practices of measuring it do not consider the growing evidence that playing exergames can provide light to moderate levels of physical activity. This study aimed to determine what proportion of time spent playing video games was actually spent playing exergames. Methods. Data were collected via a cross-sectional telephone survey in South Australia. Participants aged 18 years and above (n = 2026) were asked about their video game habits, as well as demographic and socioeconomic factors. In cases where children were in the household, the video game habits of a randomly selected child were also questioned. Results. Overall, 31.3% of adults and 79.9% of children spend at least some time playing video games. Of these, 24.1% of adults and 42.1% of children play exergames, with these types of games accounting for a third of all time that adults spend playing video games and nearly 20% of children's video game time. Conclusions. A substantial proportion of time that would usually be classified as “sedentary” may actually be spent participating in light to moderate physical activity. PMID:25002974

  12. Fully automated E-field measurement setup using pigtailed electro-optic sensors for accurate, vectorial, and reliable remote measurement of high-power microwave signals

    NASA Astrophysics Data System (ADS)

    Bernier, M.; Warzecha, A.; Duvillaret, L.; Lasserre, J.-L.; Paupert, A.

    2008-10-01

    The EO probe developed, offers an accurate evaluation of only one component of either continuous or single shot electric signal as long as the electric field to be measured is strong enough. Since those probes are also non intrusive, very small (tens of microns width) and have a flat response over a very large bandwidth (more than seven decades), they are competitive candidates for accurate vectorial measurement of either radiated or guided high power microwave electric field in the far- and near-field region. Unfortunately what makes them so versatile is also their Achilles' heel: the strong temporal instability of their response. Therefore, we present, in this paper, a fully-automated electro-optic probe developed to stabilise the transducer.

  13. Lung Volume Measured during Sequential Swallowing in Healthy Young Adults

    ERIC Educational Resources Information Center

    Hegland, Karen Wheeler; Huber, Jessica E.; Pitts, Teresa; Davenport, Paul W.; Sapienza, Christine M.

    2011-01-01

    Purpose: Outcomes from studying the coordinative relationship between respiratory and swallow subsystems are inconsistent for sequential swallows, and the lung volume at the initiation of sequential swallowing remains undefined. The first goal of this study was to quantify the lung volume at initiation of sequential swallowing ingestion cycles and…

  14. Ultrasonic Measurement of Change in Elasticity due to Endothelium Dependent Relaxation Response by Accurate Detection of Artery-Wall Boundary

    NASA Astrophysics Data System (ADS)

    Kaneko, Takuya; Hasegawa, Hideyuki; Kanai, Hiroshi

    2007-07-01

    Ross hypothesized that an endothelial dysfunction is considered to be an initial step in atherosclerosis. Endothelial cells, which release nitric oxide (NO) in response to shear stress from blood flow, have a function of relaxing smooth muscle in the media of the arterial wall. For the assessment of the endothelial function, there is a conventional method in which the change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) is measured with ultrasound. However, despite the fact that the collagen-rich hard adventitia does not respond to NO, the conventional method measures the change in diameter depending on the mechanical property of the entire wall including the adventitia. Therefore, we developed a method of measuring the change in the thickness and the elasticity of the brachial artery during a cardiac cycle using the phased tracking method for the evaluation of the mechanical property of only the intima-media region. In this study, the initial positions of echoes from the lumen-intima and media-adventitia boundaries are determined using complex template matching to accurately estimate the minute change in the thickness and the elasticity of the brachial and radial arteries. The ambiguity in the determination of such boundaries was eliminated using complex template matching, and the change in elasticity measured by the proposed method was larger than the change in inner diameter obtained by the conventional method.

  15. Accurate high-resolution measurements of 3-D tissue dynamics with registration-enhanced displacement encoded MRI.

    PubMed

    Gomez, Arnold D; Merchant, Samer S; Hsu, Edward W

    2014-06-01

    Displacement fields are important to analyze deformation, which is associated with functional and material tissue properties often used as indicators of health. Magnetic resonance imaging (MRI) techniques like DENSE and image registration methods like Hyperelastic Warping have been used to produce pixel-level deformation fields that are desirable in high-resolution analysis. However, DENSE can be complicated by challenges associated with image phase unwrapping, in particular offset determination. On the other hand, Hyperelastic Warping can be hampered by low local image contrast. The current work proposes a novel approach for measuring tissue displacement with both DENSE and Hyperelastic Warping, incorporating physically accurate displacements obtained by the latter to improve phase characterization in DENSE. The validity of the proposed technique is demonstrated using numerical and physical phantoms, and in vivo small animal cardiac MRI. PMID:24771572

  16. Crucial test for covariant density functional theory with new and accurate mass measurements from Sn to Pa

    NASA Astrophysics Data System (ADS)

    Zhao, P. W.; Song, L. S.; Sun, B.; Geissel, H.; Meng, J.

    2012-12-01

    The covariant density functional theory with the point-coupling interaction PC-PK1 is compared with new and accurate experimental masses in the element range from 50 to 91. The experimental data are from a mass measurement performed with the storage ring mass spectrometry at Gesellschaft für Schwerionenforschung (GSI) [Chen , Nucl. Phys. ANUPABL0375-947410.1016/j.nuclphysa.2012.03.002 882, 71 (2012)]. Although the microscopic theory contains only 11 parameters, it agrees well with the experimental data. The comparison is characterized by a rms deviation of 0.859 MeV. For even-even nuclei, the theory agrees within about 600 keV. Larger deviations are observed in this comparison for the odd-A and odd-odd nuclei. Improvements and possible reasons for the deviations are discussed in this contribution as well.

  17. Accurate High-Resolution Measurements of 3-D Tissue Dynamics With Registration-Enhanced Displacement Encoded MRI

    PubMed Central

    Merchant, Samer S.; Hsu, Edward W.

    2014-01-01

    Displacement fields are important to analyze deformation, which is associated with functional and material tissue properties often used as indicators of health. Magnetic resonance imaging (MRI) techniques like DENSE and image registration methods like Hyperelastic Warping have been used to produce pixel-level deformation fields that are desirable in high-resolution analysis. However, DENSE can be complicated by challenges associated with image phase unwrapping, in particular offset determination. On the other hand, Hyperelastic Warping can be hampered by low local image contrast. The current work proposes a novel approach for measuring tissue displacement with both DENSE and Hyperelastic Warping, incorporating physically accurate displacements obtained by the latter to improve phase characterization in DENSE. The validity of the proposed technique is demonstrated using numerical and physical phantoms, and in vivo small animal cardiac MRI. PMID:24771572

  18. The cost of a hospital ward in Europe: is there a methodology available to accurately measure the costs?

    PubMed

    Negrini, D; Kettle, A; Sheppard, L; Mills, G H; Edbrooke, D L

    2004-01-01

    Costing health care services has become a major requirement due to an increase in demand for health care and technological advances. Several studies have been published describing the computation of the costs of hospital wards. The objective of this article is to examine the methodologies utilised to try to describe the basic components of a standardised method, which could be applied throughout Europe. Cost measurement however is a complex matter and a lack of clarity exists in the terminology and the cost concepts utilised. The methods discussed in this review make it evident that there is a lack of standardized methodologies for the determination of accurate costs of hospital wards. A standardized costing methodology would facilitate comparisons, encourage economic evaluation within the ward and hence assist in the decision-making process with regard to the efficient allocation of resources. PMID:15366283

  19. A Review of the Definition and Measurement of Poverty: Volume I, Summary Review Paper; Volume II, Annotated Bibliography. The Measure of Poverty, Technical Paper III.

    ERIC Educational Resources Information Center

    Oster, Sharon; And Others

    This study reviews the existing literature on a series of issues associated with the defintion and measurement of poverty, and it consists of a summary report covering this research (Volume I), and an annotated bibliography (Volume II). Eleven specific issues were identified and reviewed in this study: (1) the historical definitions of poverty,…

  20. Hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products

    NASA Astrophysics Data System (ADS)

    Cen, Haiyan

    Hyperspectral imaging-based spatially-resolved technique is promising for determining the optical properties and quality attributes of horticultural and food products. However, considerable challenges still exist for accurate determination of spectral absorption and scattering properties from intact horticultural products. The objective of this research was, therefore, to develop and optimize hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products. Monte Carlo simulations and experiments for model samples of known optical properties were performed to optimize the inverse algorithm of a single-layer diffusion model and the optical designs, for extracting the absorption (micro a) and reduced scattering (micros') coefficients from spatially-resolved reflectance profiles. The logarithm and integral data transformation and the relative weighting methods were found to greatly improve the parameter estimation accuracy with the relative errors of 10.4%, 10.7%, and 11.4% for micro a, and 6.6%, 7.0%, and 7.1% for micros', respectively. More accurate measurements of optical properties were obtained when the light beam was of Gaussian type with the diameter of less than 1 mm, and the minimum and maximum source-detector distances were 1.5 mm and 10--20 transport mean free paths, respectively. An optical property measuring prototype was built, based on the optimization results, and evaluated for automatic measurement of absorption and reduced scattering coefficients for the wavelengths of 500--1,000 nm. The instrument was used to measure the optical properties, and assess quality/maturity, of 500 'Redstar' peaches and 1039 'Golden Delicious' (GD) and 1040 'Delicious' (RD) apples. A separate study was also conducted on confocal laser scanning and scanning electron microscopic image analysis and compression test of fruit tissue specimens to measure the structural and mechanical properties of 'Golden

  1. Necessary Conditions for Accurate, Transient Hot-Wire Measurements of the Apparent Thermal Conductivity of Nanofluids are Seldom Satisfied

    NASA Astrophysics Data System (ADS)

    Antoniadis, Konstantinos D.; Tertsinidou, Georgia J.; Assael, Marc J.; Wakeham, William A.

    2016-08-01

    The paper considers the conditions that are necessary to secure accurate measurement of the apparent thermal conductivity of two-phase systems comprising nanoscale particles of one material suspended in a fluid phase of a different material. It is shown that instruments operating according to the transient hot-wire technique can, indeed, produce excellent measurements when a finite element method (FEM) is employed to describe the instrument for the exact geometry of the hot wire. Furthermore, it is shown that an approximate analytic solution can be employed with equal success, over the time range of 0.1 s to 1 s, provided that (a) two wires are employed, so that end effects are canceled, (b) each wire is very thin, less than 30 \\upmu m diameter, so that the line source model and the corresponding corrections are valid, (c) low values of the temperature rise, less than 4 K, are employed in order to minimize the effect of convection on the heat transfer in the time of measurement of 1 s, and (d) insulated wires are employed for measurements in electrically conducting or polar liquids to avoid current leakage or other electrical distortions. According to these criteria, a transient hot-wire instrument has been designed, constructed, and employed for the measurement of the enhancement of the thermal conductivity of water when TiO2 or multi-wall carbon nanotubes (MWCNT) are added. These new results, together with a critical evaluation of other measurements, demonstrate the importance of proper implementation of the technique.

  2. Semi-automatic cone beam CT segmentation of in vivo pre-clinical subcutaneous tumours provides an efficient non-invasive alternative for tumour volume measurements

    PubMed Central

    Brodin, N P; Tang, J; Skalina, K; Quinn, TJ; Basu, I; Guha, C

    2015-01-01

    Objective: To evaluate the feasibility and accuracy of using cone beam CT (CBCT) scans obtained in radiation studies using the small-animal radiation research platform to perform semi-automatic tumour segmentation of pre-clinical tumour volumes. Methods: Volume measurements were evaluated for different anatomical tumour sites, the flank, thigh and dorsum of the hind foot, for a variety of tumour cell lines. The estimated tumour volumes from CBCT and manual calliper measurements using different volume equations were compared with the “gold standard”, measured by weighing the tumours following euthanasia and tumour resection. The correlation between tumour volumes estimated with the different methods, compared with the gold standard, was estimated by the Spearman's rank correlation coefficient, root-mean-square deviation and the coefficient of determination. Results: The semi-automatic CBCT volume segmentation performed favourably compared with manual calliper measures for flank tumours ≤2 cm3 and thigh tumours ≤1 cm3. For tumours >2 cm3 or foot tumours, the CBCT method was not able to accurately segment the tumour volumes and manual calliper measures were superior. Conclusion: We demonstrated that tumour volumes of flank and thigh tumours, obtained as a part of radiation studies using image-guided small-animal irradiators, can be estimated more efficiently and accurately using semi-automatic segmentation from CBCT scans. Advances in knowledge: This is the first study evaluating tumour volume assessment of pre-clinical subcutaneous tumours in different anatomical sites using on-board CBCT imaging. We also compared the accuracy of the CBCT method to manual calliper measures, using various volume calculation equations. PMID:25823502

  3. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    NASA Astrophysics Data System (ADS)

    Spadin, F.; Marti, D.; Hidalgo-Staub, R.; Rička, J.; Fleitmann, D.; Frenz, M.

    2015-06-01

    Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 °C, if the volume of the inclusion is larger than 105 μm3. With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10-20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 °C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 °C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 °C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 °C.

  4. Accurate measurement of blood vessel depth in port wine stained human skin in vivo using pulsed photothermal radiometry.

    PubMed

    Li, Bincheng; Majaron, Boris; Viator, John A; Milner, Thomas E; Chen, Zhongping; Zhao, Yonghua; Ren, Hongwu; Nelson, J Stuart

    2004-01-01

    We report on application of pulsed photothermal radiometry (PPTR) to determine the depth of port wine stain (PWS) blood vessels in human skin. When blood vessels are deep in the PWS skin (>100 microm), conventional PPTR depth profiling can be used to determine PWS depth with sufficient accuracy. When blood vessels are close or partially overlap the epidermal melanin layer, a modified PPTR technique using two-wavelength (585 and 600 nm) excitation is a superior method to determine PWS depth. A direct difference approach in which PWS depth is determined from a weighted difference of temperature profiles reconstructed independently from two-wavelength excitation is demonstrated to be appropriate for a wider range of PWS patients with various blood volume fractions, blood vessel sizes, and depth distribution. The most superficial PWS depths determined in vivo by PPTR are in good agreement with those measured using optical Doppler tomography (ODT). PMID:15447017

  5. The use of Helmholtz resonance for measuring the volume of liquids and solids.

    PubMed

    Webster, Emile S; Davies, Clive E

    2010-01-01

    An experimental investigation was undertaken to ascertain the potential of using Helmholtz resonance for volume determination and the factors that may influence accuracy. The uses for a rapid non-interference volume measurement system range from agricultural produce and mineral sampling through to liquid fill measurements. By weighing the sample the density can also measured indirectly. PMID:22163491

  6. Accurate and precise plasma clearance measurement using four 99mTc-DTPA plasma samples over 4 h

    PubMed Central

    Wanasundara, Surajith N.; Wesolowski, Michal J.; Barnfield, Mark C.; Waller, Michael L.; Murray, Anthony W.; Burniston, Maria T.; Babyn, Paul S.

    2016-01-01

    Objectives Glomerular filtration rate can be measured as the plasma clearance (CL) of a glomerular filtration rate marker despite body fluid disturbances using numerous, prolonged time samples. We desire a simplified technique without compromised accuracy and precision. Materials and methods We compared CL values derived from two plasma concentration curve area methods – (a) biexponential fitting [CL (E2)] and (b) Tikhonov adaptively regularized gamma variate fitting [CL (Tk-GV)] – for 4 versus 8 h time samplings from 412 99mTc-DTPA studies in 142 patients, mostly paediatric patients, with suspected fluid disturbances. Results CL (Tk-GV) from four samples/4 h and from nine samples/8 h, both accurately and precisely agreed with the standard, which was taken to be nine samples/8 h CL from (noncompartmental) numerical integration [CL (NI)]. The E2 method, four samples/4 h, and nine samples/8 h median CL values significantly overestimated the CL (NI) values by 4.9 and 3.8%, respectively. Conclusion Compared with the standard, CL (E2) from four samples/4 h and from nine samples/8 h proved to be the most inaccurate and imprecise method examined, and can be replaced by better methods for calculating CL. The CL (Tk-GV) can be used to reduce sampling time in half from 8 to 4 h and from nine to four samples for a precise and accurate, yet more easily tolerated and simplified test. PMID:26465802

  7. Low Frequency Volume Reverberation Measurements in Turbid Seawater

    NASA Astrophysics Data System (ADS)

    Liu, Yongwei; Li, Qi; Shang, Dejiang; Yang, Daheng; Zhang, Chao; Tang, Rui; Shang, Dajing; Chen, Mengying

    2010-09-01

    Shallow coastal waters are characterized by high levels of suspended sediment particles relative to the open ocean. This kind of seawater is also characterized as turbid seawater. An experimental investigation on volume reverberation has been done in the sea area outside the Yangtze River Estuary, where the seawater contains a lot of suspended sediment particles. Sound scattering data at 8 sites in the frequency range from 10 to 40 kHz, in steps of 1 kHz, has been obtained. The results demonstrate that volume backscattering intensity in turbid seawater may be expected to fall in the range from -60 to -100 dB re m-1. Because sound absorption caused by suspended sediment particles in turbid seawater is much greater than that in clear seawater, the volume backscattering intensity does not change with the pulse length of the transmitted signal, even when the pulse length is less than 0.5 ms. Salinity in the sea area has little effect on volume backscattering intensity. However, suspended sediment particles may have a great effect on it. Therefore, if the concentration of suspended sediment particles changes from 31 mg/L to 47 mg/L, the volume backscattering intensity may be changed by 30 dB.

  8. Highly accurate isotope composition measurements by a miniature laser ablation mass spectrometer designed for in situ investigations on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Riedo, A.; Meyer, S.; Heredia, B.; Neuland, M. B.; Bieler, A.; Tulej, M.; Leya, I.; Iakovleva, M.; Mezger, K.; Wurz, P.

    2013-10-01

    An experimental procedure for precise and accurate measurements of isotope abundances by a miniature laser ablation mass spectrometer for space research is described. The measurements were conducted on different untreated NIST standards and galena samples by applying pulsed UV laser radiation (266 nm, 3 ns and 20 Hz) for ablation, atomisation, and ionisation of the sample material. Mass spectra of released ions are measured by a reflectron-type time-of-flight mass analyser. A computer controlled performance optimiser was used to operate the system at maximum ion transmission and mass resolution. At optimal experimental conditions, the best relative accuracy and precision achieved for Pb isotope compositions are at the per mill level and were obtained in a range of applied laser irradiances and a defined number of accumulated spectra. A similar relative accuracy and precision was achieved in the study of Pb isotope compositions in terrestrial galena samples. The results for the galena samples are similar to those obtained with a thermal ionisation mass spectrometer (TIMS). The studies of the isotope composition of other elements yielded relative accuracy and precision at the per mill level too, with characteristic instrument parameters for each element. The relative accuracy and precision of the measurements is degrading with lower element/isotope concentration in a sample. For the elements with abundances below 100 ppm these values drop to the percent level. Depending on the isotopic abundances of Pb in minerals, 207Pb/206Pb ages with accuracy in the range of tens of millions of years can be achieved.

  9. A simple robust and accurate a posteriori sub-cell finite volume limiter for the discontinuous Galerkin method on unstructured meshes

    NASA Astrophysics Data System (ADS)

    Dumbser, Michael; Loubère, Raphaël

    2016-08-01

    In this paper we propose a simple, robust and accurate nonlinear a posteriori stabilization of the Discontinuous Galerkin (DG) finite element method for the solution of nonlinear hyperbolic PDE systems on unstructured triangular and tetrahedral meshes in two and three space dimensions. This novel a posteriori limiter, which has been recently proposed for the simple Cartesian grid case in [62], is able to resolve discontinuities at a sub-grid scale and is substantially extended here to general unstructured simplex meshes in 2D and 3D. It can be summarized as follows: At the beginning of each time step, an approximation of the local minimum and maximum of the discrete solution is computed for each cell, taking into account also the vertex neighbors of an element. Then, an unlimited discontinuous Galerkin scheme of approximation degree N is run for one time step to produce a so-called candidate solution. Subsequently, an a posteriori detection step checks the unlimited candidate solution at time t n + 1 for positivity, absence of floating point errors and whether the discrete solution has remained within or at least very close to the bounds given by the local minimum and maximum computed in the first step. Elements that do not satisfy all the previously mentioned detection criteria are flagged as troubled cells. For these troubled cells, the candidate solution is discarded as inappropriate and consequently needs to be recomputed. Within these troubled cells the old discrete solution at the previous time tn is scattered onto small sub-cells (Ns = 2 N + 1 sub-cells per element edge), in order to obtain a set of sub-cell averages at time tn. Then, a more robust second order TVD finite volume scheme is applied to update the sub-cell averages within the troubled DG cells from time tn to time t n + 1. The new sub-grid data at time t n + 1 are finally gathered back into a valid cell-centered DG polynomial of degree N by using a classical conservative and higher order

  10. A novel method to predict visual field progression more accurately, using intraocular pressure measurements in glaucoma patients.

    PubMed

    2016-01-01

    Visual field (VF) data were retrospectively obtained from 491 eyes in 317 patients with open angle glaucoma who had undergone ten VF tests (Humphrey Field Analyzer, 24-2, SITA standard). First, mean of total deviation values (mTD) in the tenth VF was predicted using standard linear regression of the first five VFs (VF1-5) through to using all nine preceding VFs (VF1-9). Then an 'intraocular pressure (IOP)-integrated VF trend analysis' was carried out by simply using time multiplied by IOP as the independent term in the linear regression model. Prediction errors (absolute prediction error or root mean squared error: RMSE) for predicting mTD and also point wise TD values of the tenth VF were obtained from both approaches. The mTD absolute prediction errors associated with the IOP-integrated VF trend analysis were significantly smaller than those from the standard trend analysis when VF1-6 through to VF1-8 were used (p < 0.05). The point wise RMSEs from the IOP-integrated trend analysis were significantly smaller than those from the standard trend analysis when VF1-5 through to VF1-9 were used (p < 0.05). This was especially the case when IOP was measured more frequently. Thus a significantly more accurate prediction of VF progression is possible using a simple trend analysis that incorporates IOP measurements. PMID:27562553

  11. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang

    2004-04-01

    This report summarizes technical progress over the third six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on sensor probe design and machining, sensor electronics design, software algorithm design, sensor field installation procedures, and sensor remote data access and control. Field testing will begin in the next several weeks.

  12. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2005-11-01

    This report summarizes technical progress April-September 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report. The sensing system will be installed and tested at TECO's Polk Power Station. Following a site visit in June 2005, our efforts have been focused on preparing for that field test, including he design of the sensor mechanical packaging, sensor electronics, the data transfer module, and the necessary software codes to accommodate this application.. We are currently ready to start sensor fabrication.

  13. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-11-01

    This report summarizes technical progress over the second six month period of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on evaluating corrosion effects in single crystal sapphire at temperatures up to 1400 C, and designing the sensor mechanical packaging with input from Wabash River Power Plant. Upcoming meetings will establish details for the gasifier field test.

  14. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang; Zhengyu Huang; Yizheng Zhu

    2005-04-01

    This report summarizes technical progress October 2004-March 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report.

  15. Accurate Diffusion Coefficients of Organosoluble Reference Dyes in Organic Media Measured by Dual-Focus Fluorescence Correlation Spectroscopy.

    PubMed

    Goossens, Karel; Prior, Mira; Pacheco, Victor; Willbold, Dieter; Müllen, Klaus; Enderlein, Jörg; Hofkens, Johan; Gregor, Ingo

    2015-07-28

    Dual-focus fluorescence correlation spectroscopy (2fFCS) is a versatile method to determine accurate diffusion coefficients of fluorescent species in an absolute, reference-free manner. Whereas (either classical or dual-focus) FCS has been employed primarily in the life sciences and thus in aqueous environments, it is increasingly being used in materials chemistry, as well. These measurements are often performed in nonaqueous media such as organic solvents. However, the diffusion coefficients of reference dyes in organic solvents are not readily available. For this reason we determined the translational diffusion coefficients of several commercially available organosoluble fluorescent dyes by means of 2fFCS. The selected dyes and organic solvents span the visible spectrum and a broad range of refractive indices, respectively. The diffusion coefficients can be used as absolute reference values for the calibration of experimental FCS setups, allowing quantitative measurements to be performed. We show that reliable information about the hydrodynamic dimensions of the fluorescent species (including noncommercial compounds) within organic media can be extracted from the 2fFCS data. PMID:26144863

  16. ON-LINE SELF-CALIBRATING SINGLE CRYSTAL SAPPHIRE OPTICAL SENSOR INSTRUMENTATION FOR ACCURATE AND RELIABLE COAL GASIFIER TEMPERATURE MEASUREMENT

    SciTech Connect

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2003-04-01

    This report summarizes technical progress over the first six months of the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the BPDI sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Research efforts were focused on analyzing and testing factors that impact performance degradation of the initially designed sensor prototype, including sensing element movement within the sensing probe and optical signal quality degradation. Based these results, a new version of the sensing system was designed by combining the sapphire disk sensing element and the single crystal zirconia right angle light reflector into one novel single crystal sapphire right angle prism. The new sensor prototype was tested up to 1650 C.

  17. Rapid and accurate measurement of transverse relaxation times using a single shot multi-echo echo-planar imaging sequence.

    PubMed

    Tyler, Damian J; Moore, Rachel J; Marciani, Luca; Gowland, Penny A

    2004-09-01

    Methods for making rapid and accurate measurements and maps of the transverse relaxation time from a single free induction decay (FID) are proposed. The methods use a multi-echo sequence in combination with B1 insensitive (hyperbolic secant or BIREF2b) refocusing pulses and rapid echo-planar imaging techniques. The results were calibrated against a single spin echo echo-planar imaging sequence using a phantom containing a range of CuSO4 concentrations. The mean percentage absolute difference between the multi-echo and single-echo results was 3% for the multi-echo sequence using the hyperbolic secant refocusing pulse, and 7% for the multi-echo sequence using the BIREF2b refocusing pulse, compared to 13% for a multi-echo sequence using a nonselective sinc refocusing pulse. The use of the sequences in vivo has been demonstrated in studies of gastric function, i.e., the measurement of gastric dilution and monitoring of formation of a raft of alginate polysaccharide within the stomach. PMID:15288145

  18. A novel method to predict visual field progression more accurately, using intraocular pressure measurements in glaucoma patients

    PubMed Central

    Asaoka, Ryo; Fujino, Yuri; Murata, Hiroshi; Miki, Atsuya; Tanito, Masaki; Mizoue, Shiro; Mori, Kazuhiko; Suzuki, Katsuyoshi; Yamashita, Takehiro; Kashiwagi, Kenji; Shoji, Nobuyuki

    2016-01-01

    Visual field (VF) data were retrospectively obtained from 491 eyes in 317 patients with open angle glaucoma who had undergone ten VF tests (Humphrey Field Analyzer, 24-2, SITA standard). First, mean of total deviation values (mTD) in the tenth VF was predicted using standard linear regression of the first five VFs (VF1-5) through to using all nine preceding VFs (VF1-9). Then an ‘intraocular pressure (IOP)-integrated VF trend analysis’ was carried out by simply using time multiplied by IOP as the independent term in the linear regression model. Prediction errors (absolute prediction error or root mean squared error: RMSE) for predicting mTD and also point wise TD values of the tenth VF were obtained from both approaches. The mTD absolute prediction errors associated with the IOP-integrated VF trend analysis were significantly smaller than those from the standard trend analysis when VF1-6 through to VF1-8 were used (p < 0.05). The point wise RMSEs from the IOP-integrated trend analysis were significantly smaller than those from the standard trend analysis when VF1-5 through to VF1-9 were used (p < 0.05). This was especially the case when IOP was measured more frequently. Thus a significantly more accurate prediction of VF progression is possible using a simple trend analysis that incorporates IOP measurements. PMID:27562553

  19. The gated integration technique for the accurate measurement of the autocorrelation function of speckle intensities scattered from random phase screens

    NASA Astrophysics Data System (ADS)

    Zhang, Ningyu; Cheng, Chuanfu; Teng, Shuyun; Chen, Xiaoyi; Xu, Zhizhan

    2007-09-01

    A new approach based on the gated integration technique is proposed for the accurate measurement of the autocorrelation function of speckle intensities scattered from a random phase screen. The Boxcar used for this technique in the acquisition of the speckle intensity data integrates the photoelectric signal during its sampling gate open, and it repeats the sampling by a preset number, m. The average analog of the m samplings output by the Boxcar enhances the signal-to-noise ratio by √{m}, because the repeated sampling and the average make the useful speckle signals stable, while the randomly varied photoelectric noise is suppressed by 1/√{m}. In the experiment, we use an analog-to-digital converter module to synchronize all the actions such as the stepped movement of the phase screen, the repeated sampling, the readout of the averaged output of the Boxcar, etc. The experimental results show that speckle signals are better recovered from contaminated signals, and the autocorrelation function with the secondary maximum is obtained, indicating that the accuracy of the measurement of the autocorrelation function is greatly improved by the gated integration technique.

  20. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect

    Kristie Cooper; Anbo Wang

    2007-03-31

    This report summarizes technical progress October 2006 - March 2007 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. During the second phase, an alternative high temperature sensing system based on Fabry-Perot interferometry was developed that offers a number of advantages over the BPDI solution. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. The sapphire wafer-based interferometric sensing system that was installed at TECO's Polk Power Station remained in operation for seven months. Our efforts have been focused on monitoring and analyzing the real-time data collected, and preparing for a second field test.

  1. Multiphase flowmeter successfully measures three-phase flow at extremely high gas-volume fractions -- Gulf of Suez, Egypt

    SciTech Connect

    Leggett, R.B.; Borling, D.C.; Powers, B.S.; Shehata, K.; Halvorsen, M.

    1998-02-01

    A multiphase flowmeter (MPFM) installed in offshore Egypt has accurately measured three-phase flow in extremely gassy flow conditions. The meter is completely nonintrusive, with no moving parts, requires no flow mixing before measurement, and has no bypass loop to remove gas before multiphase measurement. Flow regimes observed during the field test of this meter ranged from severe slugging to annular flow caused by the dynamics of gas-lift gas in the production stream. Average gas-volume fraction ranged from 93 to 98% during tests conducted on seven wells. The meter was installed in the Gulf of Suez on a well protector platform in the Gulf of Suez Petroleum Co. (Gupco) October field, and was placed in series with a test separator located on a nearby production platform. Wells were individually tested with flow conditions ranging from 1,300 to 4,700 B/D fluid, 2.4 to 3.9 MMscf/D of gas, and water cuts from 1 to 52%. The meter is capable of measuring water cuts up to 100%. Production was routed through both the MPFM and the test separator simultaneously as wells flowed with the assistance of gas-lift gas. The MPFM measured gas and liquid rates to within {+-} 10% of test-separator reference measurement flow rates, and accomplished this at gas-volume fractions from 93 to 96%. At higher gas-volume fractions up to 98%, accuracy deteriorated but the meter continued to provide repeatable results.

  2. Measurement of Crystalline Lens Volume During Accommodation in a Lens Stretcher

    PubMed Central

    Marussich, Lauren; Manns, Fabrice; Nankivil, Derek; Maceo Heilman, Bianca; Yao, Yue; Arrieta-Quintero, Esdras; Ho, Arthur; Augusteyn, Robert; Parel, Jean-Marie

    2015-01-01

    Purpose To determine if the lens volume changes during accommodation. Methods The study used data acquired on 36 cynomolgus monkey lenses that were stretched in a stepwise fashion to simulate disaccommodation. At each step, stretching force and dioptric power were measured and a cross-sectional image of the lens was acquired using an optical coherence tomography system. Images were corrected for refractive distortions and lens volume was calculated assuming rotational symmetry. The average change in lens volume was calculated and the relation between volume change and power change, and between volume change and stretching force, were quantified. Linear regressions of volume-power and volume-force plots were calculated. Results The mean (±SD) volume in the unstretched (accommodated) state was 97 ± 8 mm3. On average, there was a small but statistically significant (P = 0.002) increase in measured lens volume with stretching. The mean change in lens volume was +0.8 ± 1.3 mm3. The mean volume-power and volume-load slopes were −0.018 ± 0.058 mm3/D and +0.16 ± 0.40 mm3/g. Conclusions Lens volume remains effectively constant during accommodation, with changes that are less than 1% on average. This result supports a hypothesis that the change in lens shape with accommodation is accompanied by a redistribution of tissue within the capsular bag without significant compression of the lens contents or fluid exchange through the capsule. PMID:26161985

  3. An accurate measurement of the baryonic Tully-Fisher relation with heavily gas-dominated ALFALFA galaxies

    NASA Astrophysics Data System (ADS)

    Papastergis, E.; Adams, E. A. K.; van der Hulst, J. M.

    2016-09-01

    We use a sample of 97 galaxies selected from the Arecibo legacy fast ALFA (ALFALFA) 21 cm survey to make an accurate measurement of the baryonic Tully-Fisher relation (BTFR). These galaxies are specifically selected to be heavily gas-dominated (Mgas/M∗ ≳ 2.7) and to be oriented edge-on. The former property ensures that the error on the galactic baryonic mass is small, despite the large systematic uncertainty involved in galactic stellar mass estimates. The latter property means that rotational velocities can be derived directly from the width of the 21 cm emission line, without any need for inclination corrections. We measure a slope for the linewidth-based BTFR of α = 3.75 ± 0.11, a value that is somewhat steeper than (but in broad agreement with) previous literature results. The relation is remarkably tight, with almost all galaxies being located within a perpendicular distance of ± 0.1 dex from the best fit line. The low observational error budget for our sample enables us to establish that, despite its tightness, the measured linewidth-based BTFR has some small (i.e., non-zero) intrinsic scatter. We furthermore find a systematic difference in the BTFR of galaxies with "double-horned" 21 cm line profiles - suggestive of flat outer galactic rotation curves - and those with "peaked" profiles - suggestive of rising rotation curves. When we restrict our sample of galaxies to objects in the former category, we measure a slightly steeper slope of α = 4.13 ± 0.15. Overall, the high-accuracy measurement of the BTFR presented in this article is intended as a reliable observational benchmark against which to test theoretical expectations. Here we consider a representative set of semi-analytic models and hydrodynamic simulations in the lambda cold dark matter (ΛCDM) context, as well as modified Newtonian dynamics (MOND). In the near future, interferometric follow-up observations of several sample members will enable us to further refine the BTFR measurement, and

  4. High-resolution accurate mass measurements of biomolecules using a new electrospray ionization ion cyclotron resonance mass spectrometer.

    PubMed

    Winger, B E; Hofstadler, S A; Bruce, J E; Udseth, H R; Smith, R D

    1993-07-01

    A novel electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer based on a 7-T superconducting magnet was developed for high-resolution accurate mass measurements of large biomolecules. Ions formed at atmospheric pressure using electrospray ionization (ESI) were transmitted (through six differential pumping stages) to the trapped ion cell maintained below 10(-9) torr. The increased pumping speed attainable with cryopumping (> 10(5) L/s) allowed brief pressure excursions to above 10(-4) torr, with greatly enhanced trapping efficiencies and subsequent short pumpdown times, facilitating high-resolution mass measurements. A set of electromechanical shutters were also used to minimize the effect of the directed molecular beam produced by the ES1 source and were open only during ion injection. Coupled with the use of the pulsed-valve gas inlet, the trapped ion cell was generally filled to the space charge limit within 100 ms. The use of 10-25 ms ion injection times allowed mass spectra to be obtained from 4 fmol of bovine insulin (Mr 5734) and ubiquitin (Mr 8565, with resolution sufficient to easily resolve the isotopic envelopes and determine the charge states. The microheterogeneity of the glycoprotein ribonuclease B was examined, giving a measured mass of 14,898.74 Da for the most abundant peak in the isotopic envelope of the normally glycosylated protein (i.e., with five mannose and two N-acetylglucosamine residues (an error of approximately 2 ppm) and an average error of approximately 1 ppm for the higher glycosylated and various H3PO4 adducted forms of the protein. Time-domain signals lasting in excess of 80 s were obtained for smaller proteins, producing, for example, a mass resolution of more than 700,000 for the 4(+) charge state (m/z 1434) of insulin. PMID:24227643

  5. A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements.

    PubMed

    Weaver, Phoebe G; Jagow, Devin M; Portune, Cameron M; Kenney, John W

    2016-01-01

    The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (ΔT < 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature. PMID:27501355

  6. Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter

    PubMed Central

    Sun, Jiashu; Stowers, Chris C.; Boczko, Erik M.

    2012-01-01

    We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill’s function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation. PMID:20717618

  7. Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter.

    PubMed

    Sun, Jiashu; Stowers, Chris C; Boczko, Erik M; Li, Deyu

    2010-11-01

    We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill's function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation. PMID:20717618

  8. Measurement of lung fluid volumes and albumin exclusion in sheep

    SciTech Connect

    Pou, N.A.; Roselli, R.J.; Parker, R.E.; Clanton, J.A.; Harris, T.R. )

    1989-10-01

    A radioactive tracer technique was used to determine interstitial diethylenetriaminepentaacetic acid (DTPA) and albumin distribution volume in sheep lungs. {sup 125}I- and/or {sup 131}I-labeled albumin were injected intravenously and allowed to equilibrate for 24 h. {sup 99m}Tc-labeled DTPA and {sup 51}Cr-labeled erythrocytes were injected and allowed to equilibrate (2 h and 15 min, respectively) before a lethal dose of thiamylal sodium. Two biopsies (1-3 g) were taken from each lung and the remaining tissue was homogenized for wet-to-dry lung weight and volume calculations. Estimates of distribution volumes from whole lung homogenized samples were statistically smaller than biopsy samples for extravascular water, interstitial {sup 99m}Tc-DTPA, and interstitial albumin. The mean fraction of the interstitium (Fe), which excludes albumin, was 0.68 +/- 0.04 for whole lung samples compared with 0.62 +/- 0.03 for biopsy samples. Hematocrit may explain the consistent difference. To make the Fe for biopsy samples match that for homogenized samples, a mean hematocrit, which was 82% of large vessel hematocrit, was required. Excluded volume fraction for exogenous sheep albumin was compared with that of exogenous human albumin in two sheep, and no difference was found at 24 h.

  9. Continuous Non-Invasive Monitoring of Tidal Volumes by Measurement of Tidal Impedance in Neonatal Piglets

    PubMed Central

    Kurth, Florian; Zinnow, Fabienne; Prakapenia, Alexandra; Dietl, Sabrina; Winkler, Stefan; Ifflaender, Sascha; Rüdiger, Mario; Burkhardt, Wolfram

    2011-01-01

    Background Electrical Impedance measurements can be used to estimate the content of intra-thoracic air and thereby give information on pulmonary ventilation. Conventional Impedance measurements mainly indicate relative changes, but no information concerning air-volume is given. The study was performed to test whether a 3-point-calibration with known tidal volumes (VT) during conventional mechanical ventilation (CMV) allows subsequent calculation of VT from total Tidal-Impedance (tTI) measurements using Quadrant Impedance Measurement (QIM). In addition the distribution of TI in different regions of the thorax was examined. Methodology and Principal Findings QIM was performed in five neonatal piglets during volume-controlled CMV. tTI values at three different VT (4, 6, 8 ml/kg) were used to establish individual calibration curves. Subsequently, each animal was ventilated with different patterns of varying VT (2–10 ml/kg) at different PEEP levels (0, 3, 6, 9, 12 cmH2O). VT variation was repeated after surfactant depletion by bronchoalveolar lavage. VT was calculated from tTI values (VTcalc) and compared to the VT delivered by the ventilator (VTPNT). Bland-Altman analysis revealed good agreement between VTcalc and VTPNT before (bias −0.08 ml; limits of agreement −1.18 to 1.02 ml at PEEP = 3 cmH2O) and after surfactant depletion (bias −0.17 ml; limits of agreement −1.57 to 1.22 ml at PEEP = 3 cmH2O). At higher PEEP levels VTcalc was lower than VTPNT, when only one fixed calibration curve (at PEEP 3 cmH2O) was used. With a new calibration curve at each PEEP level the method showed similar accuracy at each PEEP level. TI showed a homogeneous distribution over the four assessed quadrants with a shift toward caudal regions of the thorax with increasing VT. Conclusion Tidal Impedance values could be used for precise and accurate calculation of VT during CMV in this animal study, when calibrated at each PEEP level. PMID:21687746

  10. NOTE Thyroid volume measurement in external beam radiotherapy patients using CT imaging: correlation with clinical and anthropometric characteristics

    NASA Astrophysics Data System (ADS)

    Veres, C.; Garsi, J. P.; Rubino, C.; Pouzoulet, F.; Bidault, F.; Chavaudra, J.; Bridier, A.; Ricard, M.; Ferreira, I.; Lefkopoulos, D.; de Vathaire, F.; Diallo, I.

    2010-11-01

    The aim of this study is to define criteria for accurate representation of the thyroid in human models used to represent external beam radiotherapy (EBRT) patients and evaluate the relationship between the volume of this organ and clinical and anthropometric characteristics. From CT images, we segmented the thyroid gland and calculated its volume for a population of 188 EBRT patients of both sexes, with ages ranging from 1 to 89 years. To evaluate uncertainties linked to measured volumes, experimental studies on the Livermore anthropomorphic phantom were performed. For our population of EBRT patients, we observed that in children, thyroid volume increased rapidly with age, from about 3 cm3 at 2 years to about 16 cm3 at 20. In adults, the mean thyroid gland volume was 23.5 ± 9 cm3 for males and 17.5 ± 8 cm3 for females. According to anthropometric parameters, the best fit for children was obtained by modeling the log of thyroid volume as a linear function of body surface area (BSA) (p < 0.0001) and age (p = 0.04) and for adults, as a linear function of BSA (p < 0.0001) and gender (p = 0.01). This work enabled us to demonstrate that BSA was the best indicator of thyroid volume for both males and females. These results should be taken into account when modeling the volume of the thyroid in human models used to represent EBRT patients for dosimetry in retrospective studies of the relationship between the estimated dose to the thyroid and long-term follow-up data on EBRT patients.

  11. SU-F-BRF-13: Investigating the Feasibility of Accurate Dose Measurement in a Deforming Radiochromic Dosimeter

    SciTech Connect

    Juang, T; Adamovics, J; Oldham, M

    2014-06-15

    Purpose: Presage-Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage-Def to validate dose-accumulation algorithms in deforming structures. Methods: Two cylindrical Presage-Def dosimeters (8cm diameter, 4.5cm length) were irradiated in a water-bath with a simple 4-field box treatment. Isocentric dose was 20Gy. One dosimeter served as control (no deformation) while the other was laterally compressed during irradiation by 21%. Both dosimeters were imaged before and after irradiation with a fast (∼10 minutes for 1mm isotropic resolution), broad beam, high resolution optical-CT scanner. Measured dose distributions were compared to corresponding distributions calculated by a commissioned Eclipse planning system. Accuracy in the control was evaluated with 3D gamma (3%/3mm). The dose distribution calculated for the compressed dosimeter in the irradiation geometry cannot be directly compared via profiles or 3D gamma to the measured distribution, which deforms with release from compression. Thus, accuracy under deformation was determined by comparing integral dose within the high dose region of the deformed dosimeter distribution versus calculated dose. Dose profiles were used to study temporal stability of measured dose distributions. Results: Good dose agreement was demonstrated in the control with a 3D gamma passing rate of 96.6%. For the dosimeter irradiated under compression, the measured integral dose in the high dose region (518.0Gy*cm3) was within 6% of the Eclipse-calculated integral dose (549.4Gy*cm3). Elevated signal was noted on the dosimeter edge in the direction of compression. Change in dosimeter signal over 1.5 hours was ≤2.7%, and the relative dose distribution remained stable over this period of time. Conclusion: Presage-Def is promising as a 3D dosimeter capable of accurately

  12. Accurate modeling of fluorescence line narrowing difference spectra: Direct measurement of the single-site fluorescence spectrum

    NASA Astrophysics Data System (ADS)

    Reppert, Mike; Naibo, Virginia; Jankowiak, Ryszard

    2010-07-01

    Accurate lineshape functions for modeling fluorescence line narrowing (FLN) difference spectra (ΔFLN spectra) in the low-fluence limit are derived and examined in terms of the physical interpretation of various contributions, including photoproduct absorption and emission. While in agreement with the earlier results of Jaaniso [Proc. Est. Acad. Sci., Phys., Math. 34, 277 (1985)] and Fünfschilling et al. [J. Lumin. 36, 85 (1986)], the derived formulas differ substantially from functions used recently [e.g., M. Rätsep et al., Chem. Phys. Lett. 479, 140 (2009)] to model ΔFLN spectra. In contrast to traditional FLN spectra, it is demonstrated that for most physically reasonable parameters, the ΔFLN spectrum reduces simply to the single-site fluorescence lineshape function. These results imply that direct measurement of a bulk-averaged single-site fluorescence lineshape function can be accomplished with no complicated extraction process or knowledge of any additional parameters such as site distribution function shape and width. We argue that previous analysis of ΔFLN spectra obtained for many photosynthetic complexes led to strong artificial lowering of apparent electron-phonon coupling strength, especially on the high-energy side of the pigment site distribution function.

  13. Accurate quantification of creatinine in serum by coupling a measurement standard to extractive electrospray ionization mass spectrometry

    PubMed Central

    Huang, Keke; Li, Ming; Li, Hongmei; Li, Mengwan; Jiang, You; Fang, Xiang

    2016-01-01

    Ambient ionization (AI) techniques have been widely used in chemistry, medicine, material science, environmental science, forensic science. AI takes advantage of direct desorption/ionization of chemicals in raw samples under ambient environmental conditions with minimal or no sample preparation. However, its quantitative accuracy is restricted by matrix effects during the ionization process. To improve the quantitative accuracy of AI, a matrix reference material, which is a particular form of measurement standard, was coupled to an AI technique in this study. Consequently the analyte concentration in a complex matrix can be easily quantified with high accuracy. As a demonstration, this novel method was applied for the accurate quantification of creatinine in serum by using extractive electrospray ionization (EESI) mass spectrometry. Over the concentration range investigated (0.166 ~ 1.617 μg/mL), a calibration curve was obtained with a satisfactory linearity (R2 = 0.994), and acceptable relative standard deviations (RSD) of 4.6 ~ 8.0% (n = 6). Finally, the creatinine concentration value of a serum sample was determined to be 36.18 ± 1.08 μg/mL, which is in excellent agreement with the certified value of 35.16 ± 0.39 μg/mL. PMID:26759071

  14. The application of intraoperative transit time flow measurement to accurately assess anastomotic quality in sequential vein grafting

    PubMed Central

    Yu, Yang; Zhang, Fan; Gao, Ming-Xin; Li, Hai-Tao; Li, Jing-Xing; Song, Wei; Huang, Xin-Sheng; Gu, Cheng-Xiong

    2013-01-01

    OBJECTIVES Intraoperative transit time flow measurement (TTFM) is widely used to assess anastomotic quality in coronary artery bypass grafting (CABG). However, in sequential vein grafting, the flow characteristics collected by the conventional TTFM method are usually associated with total graft flow and might not accurately indicate the quality of every distal anastomosis in a sequential graft. The purpose of our study was to examine a new TTFM method that could assess the quality of each distal anastomosis in a sequential graft more reliably than the conventional TTFM approach. METHODS Two TTFM methods were tested in 84 patients who underwent sequential saphenous off-pump CABG in Beijing An Zhen Hospital between April and August 2012. In the conventional TTFM method, normal blood flow in the sequential graft was maintained during the measurement, and the flow probe was placed a few centimetres above the anastomosis to be evaluated. In the new method, blood flow in the sequential graft was temporarily reduced during the measurement by placing an atraumatic bulldog clamp at the graft a few centimetres distal to the anastomosis to be evaluated, while the position of the flow probe remained the same as in the conventional method. This new TTFM method was named the flow reduction TTFM. Graft flow parameters measured by both methods were compared. RESULTS Compared with the conventional TTFM, the flow reduction TTFM resulted in significantly lower mean graft blood flow (P < 0.05); in contrast, yielded significantly higher pulsatility index (P < 0.05). Diastolic filling was not significantly different between the two methods and was >50% in both cases. Interestingly, the flow reduction TTFM identified two defective middle distal anastomoses that the conventional TTFM failed to detect. Graft flows near the defective distal anastomoses were improved substantially after revision. CONCLUSIONS In this study, we found that temporary reduction of graft flow during TTFM seemed to

  15. MRI-based Kidney Volume Measurements in ADPKD: Reliability and Effect of Gadolinium Enhancement

    PubMed Central

    Bae, Kyongtae T.; Tao, Cheng; Zhu, Fang; Bost, James E.; Chapman, Arlene B.; Grantham, Jared J.; Torres, Vicente E.; Guay-Woodford, Lisa M.; Meyers, Catherine M.; Bennett, William M.

    2009-01-01

    Background and objectives: To evaluate the inter- and intrareader reliability and the effect of gadolinium enhancement on kidney volume measurements obtained from pre- and postgadolinium T1 MR images in patients with autosomal dominant polycystic kidney disease (ADPKD). Design, setting, participants, & measurements: Twenty subjects were randomly selected with approximately equal frequency from three kidney-size groups. Pre- and postgadolinium 3D T1 (pre-T1, post-T1) MR images were obtained. The stereology method was applied to segment and measure kidney volumes. The measurement process was repeated at two-wk intervals by two radiologists. Reliability was assessed with correlation coefficients. Intra- and inter-reader bias and measure differences were assessed with paired T-tests. The size effect on the pre- and post-T1 measurements was evaluated with one-way ANOVA. Results: The intra- and inter-reader reliability was extremely high in all measurements. No systematic intrareader bias but a small inter-reader bias for the post-T1 measurements was observed. All kidney volumes measured on the pre- and post-T1 images were highly correlated with each other for both readers. The post-T1 volumes were significantly higher than pre-T1 volumes. While the post-pre volume differences were relatively constant across the three kidney-size groups, the post-pre percent volume differences were significantly smaller as the size of the kidney increased. Conclusions: Kidney volume measurements can be made with minimum intra- and inter-reader variability on both pre- and post-T1 MR images. Kidney volumes measured on the pre-T1 were smaller than those on post-T1, and percent differences between pre-T1 and post-T1 kidney volumes decreased with increasing kidney size. PMID:19339416

  16. Precise and accurate measurement of U and Th isotopes via ICP-MS using a single solution

    NASA Astrophysics Data System (ADS)

    Mertz-Kraus, R.; Sharp, W. D.; Ludwig, K. R.

    2012-04-01

    , allowing the sample's 238U/235U ratio to be measured. In step 3, we monitor peak-tails at half-mass positions (229.5, 231.5, 234.5) and on mass 237 while aspirating sample solution. Tail measurement requires a distinct cup configuration to maintain 238U in the cups; however, no sample is consumed during automated cup reconfiguration. We monitor the accuracy of 234U/238U ratios using CRM 145, which gives a weighted mean atom ratio of (5.2846 ± 0.0029) - 10-5 (all errors 2σ), consistent with published and reference values. The reproducibility of 230Th/238U ratios is monitored using the Schwartzwalder Mine secular-equilibrium standard (SM). We detect no bias in 230Th/238U or 234U/238U ratios measured for SM at beam intensities ranging over a factor of four, consistent with accurate correction for IC yields. Aladdin's cave coral (AC-1) was analyzed to check our ICP-MS method (and the preceding purification by ion exchange) on a carbonate and yields a mean age of 125.43 ± 0.38 ka, in agreement with published values. We are currently applying the method to corals, speleothems, pedogenic coatings, and tufas.

  17. Measurements and Modeling of Soot Formation and Radiation in Microgravity Jet Diffusion Flames. Volume 4

    NASA Technical Reports Server (NTRS)

    Ku, Jerry C.; Tong, Li; Greenberg, Paul S.

    1996-01-01

    This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. A compact, self-contained drop rig is used for microgravity experiments in the 2.2-second drop tower facility at NASA Lewis Research Center. On modeling, we have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed Beta-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude- Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H20 and C02. It is shown that when compared to results from true spectral integration, the Rosseland mean absorption coefficient can provide reasonably accurate predictions for the type of flames studied. The soot formation model proposed by Moss, Syed, and Stewart seems to produce better fits to experimental data and more physically sound than the simpler model by Khan et al. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar

  18. Accurate measurement of pancreatic islet β-cell mass using a second-generation fluorescent exendin-4 analog

    PubMed Central

    Reiner, Thomas; Thurber, Greg; Gaglia, Jason; Vinegoni, Claudio; Liew, Chong Wee; Upadhyay, Rabi; Kohler, Rainer H.; Kulkarni, Rohit N.; Benoist, Christophe; Mathis, Diane; Weissleder, Ralph

    2011-01-01

    The hallmark of type 1 diabetes is autoimmune destruction of the insulin-producing β-cells of the pancreatic islets. Autoimmune diabetes has been difficult to study or treat because it is not usually diagnosed until substantial β-cell loss has already occurred. Imaging agents that permit noninvasive visualization of changes in β-cell mass remain a high-priority goal. We report on the development and testing of a near-infrared fluorescent β-cell imaging agent. Based on the amino acid sequence of exendin-4, we created a neopeptide via introduction of an unnatural amino acid at the K12 position, which could subsequently be conjugated to fluorophores via bioorthogonal copper-catalyzed click-chemistry. Cell assays confirmed that the resulting fluorescent probe (E4×12-VT750) had a high binding affinity (∼3 nM). Its in vivo properties were evaluated using high-resolution intravital imaging, histology, whole-pancreas visualization, and endoscopic imaging. According to intravital microscopy, the probe rapidly bound to β-cells and, as demonstrated by confocal microscopy, it was internalized. Histology of the whole pancreas showed a close correspondence between fluorescence and insulin staining, and there was an excellent correlation between imaging signals and β-cell mass in mice treated with streptozotocin, a β-cell toxin. Individual islets could also be visualized by endoscopic imaging. In short, E4×12-VT750 showed strong and selective binding to glucose-like peptide-1 receptors and permitted accurate measurement of β-cell mass in both diabetic and nondiabetic mice. This near-infrared imaging probe, as well as future radioisotope-labeled versions of it, should prove to be important tools for monitoring diabetes, progression, and treatment in both experimental and clinical contexts. PMID:21768367

  19. ASRDI oxygen technology survey. Volume 6: Flow measurement instrumentation

    NASA Technical Reports Server (NTRS)

    Mann, D. B.

    1974-01-01

    A summary is provided of information available on liquid and gaseous oxygen flowmetering including an evaluation of commercial meters. The instrument types, physical principles of measurement, and performance characteristics are described. Problems concerning flow measurements of less than plus or minus two percent uncertainty are reviewed. Recommendations concerning work on flow reference systems, the use of surrogate fluids, and standard tests for oxygen flow measurements are also presented.

  20. High-speed volume measurement system and method

    SciTech Connect

    Lane, Michael H.; Doyle, Jr., James L.; Brinkman, Michael J.

    2015-11-24

    Disclosed is a volume sensor having first, second, and third laser sources emitting first, second, and third laser beams; first, second, and third beam splitters splitting the first, second, and third laser beams into first, second, and third beam pairs; first, second, and third optical assemblies expanding the first, second, and third beam pairs into first, second, and third pairs of parallel beam sheets; fourth, fifth, and sixth optical assemblies focusing the first, second, and third beam sheet pairs into fourth, fifth, and sixth beam pairs; and first, second, and third detector pairs receiving the fourth, fifth, and sixth beam pairs and converting a change in intensity of at least one of the beam pairs resulting from an object passing through at least one of the first, second, and third parallel beam sheets into at least one electrical signal proportional to a three-dimensional representation of the object.