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Sample records for accurately measured total

  1. Development and calibration of an accurate 6-degree-of-freedom measurement system with total station

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Lin, Jiarui; Yang, Linghui; Zhu, Jigui

    2016-12-01

    To meet the demand of high-accuracy, long-range and portable use in large-scale metrology for pose measurement, this paper develops a 6-degree-of-freedom (6-DOF) measurement system based on total station by utilizing its advantages of long range and relative high accuracy. The cooperative target sensor, which is mainly composed of a pinhole prism, an industrial lens, a camera and a biaxial inclinometer, is designed to be portable in use. Subsequently, a precise mathematical model is proposed from the input variables observed by total station, imaging system and inclinometer to the output six pose variables. The model must be calibrated in two levels: the intrinsic parameters of imaging system, and the rotation matrix between coordinate systems of the camera and the inclinometer. Then corresponding approaches are presented. For the first level, we introduce a precise two-axis rotary table as a calibration reference. And for the second level, we propose a calibration method by varying the pose of a rigid body with the target sensor and a reference prism on it. Finally, through simulations and various experiments, the feasibilities of the measurement model and calibration methods are validated, and the measurement accuracy of the system is evaluated.

  2. Accurate spectral color measurements

    NASA Astrophysics Data System (ADS)

    Hiltunen, Jouni; Jaeaeskelaeinen, Timo; Parkkinen, Jussi P. S.

    1999-08-01

    Surface color measurement is of importance in a very wide range of industrial applications including paint, paper, printing, photography, textiles, plastics and so on. For a demanding color measurements spectral approach is often needed. One can measure a color spectrum with a spectrophotometer using calibrated standard samples as a reference. Because it is impossible to define absolute color values of a sample, we always work with approximations. The human eye can perceive color difference as small as 0.5 CIELAB units and thus distinguish millions of colors. This 0.5 unit difference should be a goal for the precise color measurements. This limit is not a problem if we only want to measure the color difference of two samples, but if we want to know in a same time exact color coordinate values accuracy problems arise. The values of two instruments can be astonishingly different. The accuracy of the instrument used in color measurement may depend on various errors such as photometric non-linearity, wavelength error, integrating sphere dark level error, integrating sphere error in both specular included and specular excluded modes. Thus the correction formulas should be used to get more accurate results. Another question is how many channels i.e. wavelengths we are using to measure a spectrum. It is obvious that the sampling interval should be short to get more precise results. Furthermore, the result we get is always compromise of measuring time, conditions and cost. Sometimes we have to use portable syste or the shape and the size of samples makes it impossible to use sensitive equipment. In this study a small set of calibrated color tiles measured with the Perkin Elmer Lamda 18 and the Minolta CM-2002 spectrophotometers are compared. In the paper we explain the typical error sources of spectral color measurements, and show which are the accuracy demands a good colorimeter should have.

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Analytical Validation of a Highly Quantitative, Sensitive, Accurate, and Reproducible Assay (HERmark®) for the Measurement of HER2 Total Protein and HER2 Homodimers in FFPE Breast Cancer Tumor Specimens

    PubMed Central

    Larson, Jeffrey S.; Goodman, Laurie J.; Tan, Yuping; Defazio-Eli, Lisa; Paquet, Agnes C.; Cook, Jennifer W.; Rivera, Amber; Frankson, Kristi; Bose, Jolly; Chen, Lili; Cheung, Judy; Shi, Yining; Irwin, Sarah; Kiss, Linda D. B.; Huang, Weidong; Utter, Shannon; Sherwood, Thomas; Bates, Michael; Weidler, Jodi; Parry, Gordon; Winslow, John; Petropoulos, Christos J.; Whitcomb, Jeannette M.

    2010-01-01

    We report here the results of the analytical validation of assays that measure HER2 total protein (H2T) and HER2 homodimer (H2D) expression in Formalin Fixed Paraffin Embedded (FFPE) breast cancer tumors as well as cell line controls. The assays are based on the VeraTag technology platform and are commercially available through a central CAP-accredited clinical reference laboratory. The accuracy of H2T measurements spans a broad dynamic range (2-3 logs) as evaluated by comparison with cross-validating technologies. The measurement of H2T expression demonstrates a sensitivity that is approximately 7–10 times greater than conventional immunohistochemistry (IHC) (HercepTest). The HERmark assay is a quantitative assay that sensitively and reproducibly measures continuous H2T and H2D protein expression levels and therefore may have the potential to stratify patients more accurately with respect to response to HER2-targeted therapies than current methods which rely on semiquantitative protein measurements (IHC) or on indirect assessments of gene amplification (FISH). PMID:21151530

  9. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2017-03-01

    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.

  10. 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.

  11. Accurate, reproducible measurement of blood pressure.

    PubMed Central

    Campbell, N R; Chockalingam, A; Fodor, J G; McKay, D W

    1990-01-01

    The diagnosis of mild hypertension and the treatment of hypertension require accurate measurement of blood pressure. Blood pressure readings are altered by various factors that influence the patient, the techniques used and the accuracy of the sphygmomanometer. The variability of readings can be reduced if informed patients prepare in advance by emptying their bladder and bowel, by avoiding over-the-counter vasoactive drugs the day of measurement and by avoiding exposure to cold, caffeine consumption, smoking and physical exertion within half an hour before measurement. The use of standardized techniques to measure blood pressure will help to avoid large systematic errors. Poor technique can account for differences in readings of more than 15 mm Hg and ultimately misdiagnosis. Most of the recommended procedures are simple and, when routinely incorporated into clinical practice, require little additional time. The equipment must be appropriate and in good condition. Physicians should have a suitable selection of cuff sizes readily available; the use of the correct cuff size is essential to minimize systematic errors in blood pressure measurement. Semiannual calibration of aneroid sphygmomanometers and annual inspection of mercury sphygmomanometers and blood pressure cuffs are recommended. We review the methods recommended for measuring blood pressure and discuss the factors known to produce large differences in blood pressure readings. PMID:2192791

  12. 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.

  13. 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.

  14. Fast and accurate exhaled breath ammonia measurement.

    PubMed

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

    2014-06-11

    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.

  15. 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.

  16. Accurately measuring dynamic coefficient of friction in ultraform finishing

    NASA Astrophysics Data System (ADS)

    Briggs, Dennis; Echaves, Samantha; Pidgeon, Brendan; Travis, Nathan; Ellis, Jonathan D.

    2013-09-01

    UltraForm Finishing (UFF) is a deterministic sub-aperture computer numerically controlled grinding and polishing platform designed by OptiPro Systems. UFF is used to grind and polish a variety of optics from simple spherical to fully freeform, and numerous materials from glasses to optical ceramics. The UFF system consists of an abrasive belt around a compliant wheel that rotates and contacts the part to remove material. This work aims to accurately measure the dynamic coefficient of friction (μ), how it changes as a function of belt wear, and how this ultimately affects material removal rates. The coefficient of friction has been examined in terms of contact mechanics and Preston's equation to determine accurate material removal rates. By accurately predicting changes in μ, polishing iterations can be more accurately predicted, reducing the total number of iterations required to meet specifications. We have established an experimental apparatus that can accurately measure μ by measuring triaxial forces during translating loading conditions or while manufacturing the removal spots used to calculate material removal rates. Using this system, we will demonstrate μ measurements for UFF belts during different states of their lifecycle and assess the material removal function from spot diagrams as a function of wear. Ultimately, we will use this system for qualifying belt-wheel-material combinations to develop a spot-morphing model to better predict instantaneous material removal functions.

  17. Trends in total column ozone measurements

    NASA Technical Reports Server (NTRS)

    Rowland, F. S.; Angell, J.; Attmannspacher, W.; Bloomfield, P.; Bojkov, R. D.; Harris, N.; Komhyr, W.; Mcfarland, M.; Mcpeters, R.; Stolarski, R. S.

    1989-01-01

    It is important to ensure the best available data are used in any determination of possible trends in total ozone in order to have the most accurate estimates of any trends and the associated uncertainties. Accordingly, the existing total ozone records were examined in considerable detail. Once the best data set has been produced, the statistical analysis must examine the data for any effects that might indicate changes in the behavior of global total ozone. The changes at any individual measuring station could be local in nature, and herein, particular attention was paid to the seasonal and latitudinal variations of total ozone, because two dimensional photochemical models indicate that any changes in total ozone would be most pronounced at high latitudes during the winter months. The conclusions derived from this detailed examination of available total ozone can be split into two categories, one concerning the quality and the other the statistical analysis of the total ozone record.

  18. Total body potassium measurement method

    SciTech Connect

    Tomlinson, F.K.

    1985-09-01

    The body counter facility at Mound was used to measure the total body potassium (TBK) in hypertensive patients. Radioactive /sup 40/K accounts for 0.0118% of natural potassium and can be readily measured in vivo. The normal adult human generally has 80 to 185 g of TBK depending on sex, age, height, etc. 10 refs., 1 tab.

  19. Totally Implantable Wireless Ultrasonic Doppler Blood Flowmeters: Toward Accurate Miniaturized Chronic Monitors.

    PubMed

    Rothfuss, Michael A; Unadkat, Jignesh V; Gimbel, Michael L; Mickle, Marlin H; Sejdić, Ervin

    2017-03-01

    Totally implantable wireless ultrasonic blood flowmeters provide direct-access chronic vessel monitoring in hard-to-reach places without using wired bedside monitors or imaging equipment. Although wireless implantable Doppler devices are accurate for most applications, device size and implant lifetime remain vastly underdeveloped. We review past and current approaches to miniaturization and implant lifetime extension for wireless implantable Doppler devices and propose approaches to reduce device size and maximize implant lifetime for the next generation of devices. Additionally, we review current and past approaches to accurate blood flow measurements. This review points toward relying on increased levels of monolithic customization and integration to reduce size. Meanwhile, recommendations to maximize implant lifetime should include alternative sources of power, such as transcutaneous wireless power, that stand to extend lifetime indefinitely. Coupling together the results will pave the way for ultra-miniaturized totally implantable wireless blood flow monitors for truly chronic implantation.

  20. Reproduction of Hip Offset and Leg Length in Navigated Total Hip Arthroplasty: How Accurate Are We?

    PubMed

    Ellapparadja, Pregash; Mahajan, Vivek; Deakin, Angela H; Deep, Kamal

    2015-06-01

    This study assesses how accurately we can restore hip offset and leg length in navigated total hip arthroplasty (THA). 152 consecutive patients with navigated THA formed the study group. The contra-lateral hip formed control for measuring hip offset and leg length. All radiological measurements were made using Orthoview digital software. In the normal hip offset group, the mean is 75.73 (SD- 8.61). In the reconstructed hip offset group, the mean is 75.35 (SD - 7.48). 95.39% had hip offset within 6 mm of opposite side while 96.04% had leg length restored within 6 mm of contra-lateral side. Equivalence test revealed that the two groups of hip offsets were essentially the same. We conclude that computer navigation can successfully reproduce hip offset and leg length accurately.

  1. 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 ...

  2. A unique, accurate LWIR optics measurement system

    NASA Astrophysics Data System (ADS)

    Fantone, Stephen D.; Orband, Daniel G.

    2011-05-01

    A compact low-cost LWIR test station has been developed that provides real time MTF testing of IR optical systems and EO imaging systems. The test station is intended to be operated by a technician and can be used to measure the focal length, blur spot size, distortion, and other metrics of system performance. The challenges and tradeoffs incorporated into this instrumentation will be presented. The test station performs the measurement of an IR lens or optical system's first order quantities (focal length, back focal length) including on and off-axis imaging performance (e.g., MTF, resolution, spot size) under actual test conditions to enable the simulation of their actual use. Also described is the method of attaining the needed accuracies so that derived calculations like focal length (EFL = image shift/tan(theta)) can be performed to the requisite accuracy. The station incorporates a patented video capture technology and measures MTF and blur characteristics using newly available lowcost LWIR cameras. This allows real time determination of the optical system performance enabling faster measurements, higher throughput and lower cost results than scanning systems. Multiple spectral filters are also accommodated within the test stations which facilitate performance evaluation under various spectral conditions.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Accurate measurement of psoralen-crosslinked DNA: direct biochemical measurements and indirect measurement by hybridization

    SciTech Connect

    Matsuo, N.; Ross, P.M.

    1988-11-01

    This paper evaluates methods to measure crosslinkage due to psoralen plus light in total DNA and in specific sequences. DNA exposed in cells or in vitro to a bifunctional psoralen and near ultraviolet light accumulates interstrand crosslinks. Crosslinkage is the DNA mass fraction that is attached in both strands to a crosslink. We show here biochemical methods to measure psoralen photocrosslinkage accurately in total DNA. We also describe methods to measure photocrosslinkage indirectly, in specific sequences, by nucleic acid hybridization. We show that a single 4,5',8-trimethylpsoralen (TMP) crosslink causes at least 50 kbp of alkali-denatured DNA contiguous in both strands with it to snap back into the duplex form when the denatured preparation is returned to neutral pH. This process was so efficient that the DNA was not nicked by the single-strand nuclease S1 at 100-fold excess after snapping back. Uncrosslinked DNA was digested to acid-soluble material by the enzyme. Crosslinkage therefore equals the fraction of S1-resistant nucleotide in this kind of experiment. We alkali-denatured DNA samples crosslinked to varying degrees by varying TMP concentration at constant light exposure. We then measured crosslinkage by ethidium bromide (EtBr) fluorometry at pH 11.8; by EtBr fluorometry at neutral pH of S1 digests of the DNA; and by the fraction of radioactivity remaining acid insoluble in S1-digests of DNA labeled uniformly with (3H)deoxythymidine. These assays measure distinct physical properties of crosslinked DNA. Numerical agreement is expected only when all three measurements are accurate. Under optimum conditions, the three methods yielded identical results over the range of measurement. Using alkaline EtBr fluorescence in crude cell lysates, we detected crosslinks at frequencies in the range of 1.6 X 10(-7) per base pair.

  9. 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.

  10. 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.

  11. Can tritiated water-dilution space accurately predict total body water in chukar partridges

    SciTech Connect

    Crum, B.G.; Williams, J.B.; Nagy, K.A.

    1985-11-01

    Total body water (TBW) volumes determined from the dilution space of injected tritiated water have consistently overestimated actual water volumes (determined by desiccation to constant mass) in reptiles and mammals, but results for birds are controversial. We investigated potential errors in both the dilution method and the desiccation method in an attempt to resolve this controversy. Tritiated water dilution yielded an accurate measurement of water mass in vitro. However, in vivo, this method yielded a 4.6% overestimate of the amount of water (3.1% of live body mass) in chukar partridges, apparently largely because of loss of tritium from body water to sites of dissociable hydrogens on body solids. An additional source of overestimation (approximately 2% of body mass) was loss of tritium to the solids in blood samples during distillation of blood to obtain pure water for tritium analysis. Measuring tritium activity in plasma samples avoided this problem but required measurement of, and correction for, the dry matter content in plasma. Desiccation to constant mass by lyophilization or oven-drying also overestimated the amount of water actually in the bodies of chukar partridges by 1.4% of body mass, because these values included water adsorbed onto the outside of feathers. When desiccating defeathered carcasses, oven-drying at 70 degrees C yielded TBW values identical to those obtained from lyophilization, but TBW was overestimated (0.5% of body mass) by drying at 100 degrees C due to loss of organic substances as well as water.

  12. 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.

  13. Ultrasonic system for accurate distance measurement in the air.

    PubMed

    Licznerski, Tomasz J; Jaroński, Jarosław; Kosz, Dariusz

    2011-12-01

    This paper presents a system that accurately measures the distance travelled by ultrasound waves through the air. The simple design of the system and its obtained accuracy provide a tool for non-contact distance measurements required in the laser's optical system that investigates the surface of the eyeball.

  14. In-line sensor for accurate rf power measurements

    NASA Astrophysics Data System (ADS)

    Gahan, D.; Hopkins, M. B.

    2005-10-01

    An in-line sensor has been constructed with 50Ω characteristic impedance to accurately measure rf power dissipated in a matched or unmatched load with a view to being implemented as a rf discharge diagnostic. The physical construction and calibration technique are presented. The design is a wide band, hybrid directional coupler/current-voltage sensor suitable for fundamental and harmonic power measurements. A comparison with a standard wattmeter using dummy load impedances shows that this in-line sensor is significantly more accurate in mismatched conditions.

  15. In-line sensor for accurate rf power measurements

    SciTech Connect

    Gahan, D.; Hopkins, M.B.

    2005-10-15

    An in-line sensor has been constructed with 50 {omega} characteristic impedance to accurately measure rf power dissipated in a matched or unmatched load with a view to being implemented as a rf discharge diagnostic. The physical construction and calibration technique are presented. The design is a wide band, hybrid directional coupler/current-voltage sensor suitable for fundamental and harmonic power measurements. A comparison with a standard wattmeter using dummy load impedances shows that this in-line sensor is significantly more accurate in mismatched conditions.

  16. Estimation of bone permeability using accurate microstructural measurements.

    PubMed

    Beno, Thoma; Yoon, Young-June; Cowin, Stephen C; Fritton, Susannah P

    2006-01-01

    While interstitial fluid flow is necessary for the viability of osteocytes, it is also believed to play a role in bone's mechanosensory system by shearing bone cell membranes or causing cytoskeleton deformation and thus activating biochemical responses that lead to the process of bone adaptation. However, the fluid flow properties that regulate bone's adaptive response are poorly understood. In this paper, we present an analytical approach to determine the degree of anisotropy of the permeability of the lacunar-canalicular porosity in bone. First, we estimate the total number of canaliculi emanating from each osteocyte lacuna based on published measurements from parallel-fibered shaft bones of several species (chick, rabbit, bovine, horse, dog, and human). Next, we determine the local three-dimensional permeability of the lacunar-canalicular porosity for these species using recent microstructural measurements and adapting a previously developed model. Results demonstrated that the number of canaliculi per osteocyte lacuna ranged from 41 for human to 115 for horse. Permeability coefficients were found to be different in three local principal directions, indicating local orthotropic symmetry of bone permeability in parallel-fibered cortical bone for all species examined. For the range of parameters investigated, the local lacunar-canalicular permeability varied more than three orders of magnitude, with the osteocyte lacunar shape and size along with the 3-D canalicular distribution determining the degree of anisotropy of the local permeability. This two-step theoretical approach to determine the degree of anisotropy of the permeability of the lacunar-canalicular porosity will be useful for accurate quantification of interstitial fluid movement in bone.

  17. 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.

  18. 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.

  19. 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.

  20. 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,…

  1. Ellipsoidal-mirror reflectometer accurately measures infrared reflectance of materials

    NASA Technical Reports Server (NTRS)

    Dunn, S. T.; Richmond, J. C.

    1967-01-01

    Reflectometer accurately measures the reflectance of specimens in the infrared beyond 2.5 microns and under geometric conditions approximating normal irradiation and hemispherical viewing. It includes an ellipsoidal mirror, a specially coated averaging sphere associated with a detector for minimizing spatial and angular sensitivity, and an incident flux chopper.

  2. Accurate measurement of streamwise vortices using dual-plane PIV

    NASA Astrophysics Data System (ADS)

    Waldman, Rye M.; Breuer, Kenneth S.

    2012-11-01

    Low Reynolds number aerodynamic experiments with flapping animals (such as bats and small birds) are of particular interest due to their application to micro air vehicles which operate in a similar parameter space. Previous PIV wake measurements described the structures left by bats and birds and provided insight into the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions based on said measurements. The highly three-dimensional and unsteady nature of the flows associated with flapping flight are major challenges for accurate measurements. The challenge of animal flight measurements is finding small flow features in a large field of view at high speed with limited laser energy and camera resolution. Cross-stream measurement is further complicated by the predominately out-of-plane flow that requires thick laser sheets and short inter-frame times, which increase noise and measurement uncertainty. Choosing appropriate experimental parameters requires compromise between the spatial and temporal resolution and the dynamic range of the measurement. To explore these challenges, we do a case study on the wake of a fixed wing. The fixed model simplifies the experiment and allows direct measurements of the aerodynamic forces via load cell. We present a detailed analysis of the wake measurements, discuss the criteria for making accurate measurements, and present a solution for making quantitative aerodynamic load measurements behind free-flyers.

  3. Accurately measuring volcanic plume velocity with multiple UV spectrometers

    USGS Publications Warehouse

    Williams-Jones, Glyn; Horton, Keith A.; Elias, Tamar; Garbeil, Harold; Mouginis-Mark, Peter J; Sutton, A. Jeff; Harris, Andrew 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 Kīlauea (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.

  4. Optical Fiber Geometry: Accurate Measurement of Cladding Diameter

    PubMed Central

    Young, Matt; Hale, Paul D.; Mechels, Steven E.

    1993-01-01

    We have developed three instruments for accurate measurement of optieal fiber cladding diameter: a contact micrometer, a scanning confocal microscope, and a white-light interference microscope. Each instrument has an estimated uncertainty (3 standard deviations) of 50 nm or less, but the confocal microscope may display a 20 nm systematic error as well. The micrometer is used to generate Standard Reference Materials that are commercially available. PMID:28053467

  5. Defense meteorological satellite measurements of total ozone

    NASA Technical Reports Server (NTRS)

    Lovill, J. E.; Ellis, J. S.; Luther, F. M.; Sullivan, T. J.; Weichel, R. L.

    1982-01-01

    A multichannel filter radiometer (MFR) on Defense Meteorological Satellites (DMS) that measured total ozone on a global-scale from March 1977 - February 1980 is described. The total ozone data measured by the MFR were compared with total ozone data taken by surfaced-based Dobson spectrophotometers. When comparisons were made for five months, the Dobson spectrophotometer measured 2-5% more total ozone than the MFR. Comparisons between the Dobson spectrophotometer and the MFR showed a reduced RMS difference as the comparisons were made at closer proximity. A Northern Hemisphere total ozone distribution obtained from MFR data is presented.

  6. 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

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

    PubMed

    Shortis, Mark

    2015-12-07

    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.

  8. RTbox: a device for highly accurate response time measurements.

    PubMed

    Li, Xiangrui; Liang, Zhen; Kleiner, Mario; Lu, Zhong-Lin

    2010-02-01

    Although computer keyboards and mice are frequently used in measuring response times (RTs), the accuracy of these measurements is quite low. Specialized RT collection devices must be used to obtain more accurate measurements. However, all the existing devices have some shortcomings. We have developed and implemented a new, commercially available device, the RTbox, for highly accurate RT measurements. The RTbox has its own microprocessor and high-resolution clock. It can record the identities and timing of button events with high accuracy, unaffected by potential timing uncertainty or biases during data transmission and processing in the host computer. It stores button events until the host computer chooses to retrieve them. The asynchronous storage greatly simplifies the design of user programs. The RTbox can also receive and record external signals as triggers and can measure RTs with respect to external events. The internal clock of the RTbox can be synchronized with the computer clock, so the device can be used without external triggers. A simple USB connection is sufficient to integrate the RTbox with any standard computer and operating system.

  9. Accurate measurement of the helical twisting power of chiral dopants

    NASA Astrophysics Data System (ADS)

    Kosa, Tamas; Bodnar, Volodymyr; Taheri, Bahman; Palffy-Muhoray, Peter

    2002-03-01

    We propose a method for the accurate determination of the helical twisting power (HTP) of chiral dopants. In the usual Cano-wedge method, the wedge angle is determined from the far-field separation of laser beams reflected from the windows of the test cell. Here we propose to use an optical fiber based spectrometer to accurately measure the cell thickness. Knowing the cell thickness at the positions of the disclination lines allows determination of the HTP. We show that this extension of the Cano-wedge method greatly increases the accuracy with which the HTP is determined. We show the usefulness of this method by determining the HTP of ZLI811 in a variety of hosts with negative dielectric anisotropy.

  10. Accurate Runout Measurement for HDD Spinning Motors and Disks

    NASA Astrophysics Data System (ADS)

    Jiang, Quan; Bi, Chao; Lin, Song

    As hard disk drive (HDD) areal density increases, its track width becomes smaller and smaller and so is non-repeatable runout. HDD industry needs more accurate and better resolution runout measurements of spinning spindle motors and media platters in both axial and radial directions. This paper introduces a new system how to precisely measure the runout of HDD spinning disks and motors through synchronously acquiring the rotor position signal and the displacements in axial or radial directions. In order to minimize the synchronizing error between the rotor position and the displacement signal, a high resolution counter is adopted instead of the conventional phase-lock loop method. With Laser Doppler Vibrometer and proper signal processing, the proposed runout system can precisely measure the runout of the HDD spinning disks and motors with 1 nm resolution and 0.2% accuracy with a proper sampling rate. It can provide an effective and accurate means to measure the runout of high areal density HDDs, in particular the next generation HDDs, such as, pattern media HDDs and HAMR HDDs.

  11. Accurate measurement method for tube's endpoints based on machine vision

    NASA Astrophysics Data System (ADS)

    Liu, Shaoli; Jin, Peng; Liu, Jianhua; Wang, Xiao; Sun, Peng

    2017-01-01

    Tubes are used widely in aerospace vehicles, and their accurate assembly can directly affect the assembling reliability and the quality of products. It is important to measure the processed tube's endpoints and then fix any geometric errors correspondingly. However, the traditional tube inspection method is time-consuming and complex operations. Therefore, a new measurement method for a tube's endpoints based on machine vision is proposed. First, reflected light on tube's surface can be removed by using photometric linearization. Then, based on the optimization model for the tube's endpoint measurements and the principle of stereo matching, the global coordinates and the relative distance of the tube's endpoint are obtained. To confirm the feasibility, 11 tubes are processed to remove the reflected light and then the endpoint's positions of tubes are measured. The experiment results show that the measurement repeatability accuracy is 0.167 mm, and the absolute accuracy is 0.328 mm. The measurement takes less than 1 min. The proposed method based on machine vision can measure the tube's endpoints without any surface treatment or any tools and can realize on line measurement.

  12. Accurate vessel width measurement from fundus photographs: a new concept.

    PubMed Central

    Rassam, S M; Patel, V; Brinchmann-Hansen, O; Engvold, O; Kohner, E M

    1994-01-01

    Accurate determination of retinal vessel width measurement is important in the study of the haemodynamic changes that accompany various physiological and pathological states. Currently the width at the half height of the transmittance and densitometry profiles are used as a measure of retinal vessel width. A consistent phenomenon of two 'kick points' on the slopes of the transmittance and densitometry profiles near the base, has been observed. In this study, mathematical models have been formulated to describe the characteristic curves of the transmittance and the densitometry profiles. They demonstrate the kick points being coincident with the edges of the blood column. The horizontal distance across the kick points would therefore indicate the actual blood column width. To evaluate this hypothesis, blood was infused through two lengths of plastic tubing of known diameters, and photographed. In comparison with the known diameters, the half height underestimated the blood column width by 7.33% and 6.46%, while the kick point method slightly overestimated it by 1.40% and 0.34%. These techniques were applied to monochromatic fundus photographs. In comparison with the kick point method, the half height underestimated the blood column width in veins by 16.67% and in arteries by 15.86%. The characteristics of the kick points and their practicality have been discussed. The kick point method may provide the most accurate measurement of vessel width possible from these profiles. Images PMID:8110693

  13. 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.

  14. 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.

  15. Accurate and precise zinc isotope ratio measurements in urban aerosols.

    PubMed

    Gioia, Simone; Weiss, Dominik; Coles, Barry; Arnold, Tim; Babinski, Marly

    2008-12-15

    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 delta(66)Zn determinations in aerosols is around 0.05 per thousand per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in delta(66)Zn(Imperial) ranging between -0.96 and -0.37 per thousand in coarse and between -1.04 and 0.02 per thousand in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source. We present further delta(66)Zn(Imperial) data for the standard reference material NIST SRM 2783 (delta(66)Zn(Imperial) = 0.26 +/- 0.10 per thousand).

  16. Accurate measurement of the pulse wave delay with imaging photoplethysmography

    PubMed Central

    Kamshilin, Alexei A.; Sidorov, Igor S.; Babayan, Laura; Volynsky, Maxim A.; Giniatullin, Rashid; Mamontov, Oleg V.

    2016-01-01

    Assessment of the cardiovascular parameters using noncontact video-based or imaging photoplethysmography (IPPG) is usually considered as inaccurate because of strong influence of motion artefacts. To optimize this technique we performed a simultaneous recording of electrocardiogram and video frames of the face for 36 healthy volunteers. We found that signal disturbances originate mainly from the stochastically enhanced dichroic notch caused by endogenous cardiovascular mechanisms, with smaller contribution of the motion artefacts. Our properly designed algorithm allowed us to increase accuracy of the pulse-transit-time measurement and visualize propagation of the pulse wave in the facial region. Thus, the accurate measurement of the pulse wave parameters with this technique suggests a sensitive approach to assess local regulation of microcirculation in various physiological and pathological states. PMID:28018731

  17. 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

  18. Measurement and Accurate Interpretation of the Solubility of Pharmaceutical Salts.

    PubMed

    He, Yan; Ho, Chris; Yang, Donglai; Chen, Jeane; Orton, Edward

    2017-01-30

    Salt formation is one of the primary approaches to improve the developability of ionizable poorly water-soluble compounds. Solubility determination of the salt candidates in aqueous media or biorelevant fluids is a critical step in salt screening. Salt solubility measurements can be complicated due to dynamic changes in both solution and solid phases. Because of the early implementation of salt screening in research, solubility measurements often are performed using minimal amount of material. Some salts have transient high solubility on dissolution. Recognition of these transients can be critical in developing these salts into drug products. This minireview focuses on challenges in salt solubility measurements due to the changes in solution caused by self-buffering effects of dissolved species and the changes in solid phase due to solid-state phase transformations. Solubility measurements and their accurate interpretation are assessed in the context of dissolution monitoring and solid-phase analysis technologies. A harmonized method for reporting salt solubility measurements is recommended to reduce errors and to align with the U.S. Pharmacopeial policy and Food and Drug Administration recommendations for drug products containing pharmaceutical salts.

  19. 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.

  20. MRI is more accurate than CT for patient-specific total knee arthroplasty.

    PubMed

    Frye, Benjamin M; Najim, Amjad A; Adams, Joanne B; Berend, Keith R; Lombardi, Adolph V

    2015-12-01

    Previous reports have stated that MRI is less accurate than CT for patient specific guide creation in total knee arthroplasty (TKA). Twenty-three TKAs were performed with CT-based guides and 27 with MRI-based guides. A mechanical axis through the central third of the knee was achieved in 88.9% of MRI-guided TKA versus 69.6% of CT-guided TKA (p=0.07). There were nine component outliers in the CT group (39.1%) and two in the MRI group (7.4%, p=0.00768). The relative risk of having an outlier using a CT-based guide was 5.28 times that of an MRI-based guide. Superior overall alignment and fewer outliers were achieved with the use of MRI compared with CT. MRI is the best imaging modality for surgeons wishing to utilize patient specific guides for TKA.

  1. 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.

  2. 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.

  3. 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.

  4. Method for Accurate Surface Temperature Measurements During Fast Induction Heating

    NASA Astrophysics Data System (ADS)

    Larregain, Benjamin; Vanderesse, Nicolas; Bridier, Florent; Bocher, Philippe; Arkinson, Patrick

    2013-07-01

    A robust method is proposed for the measurement of surface temperature fields during induction heating. It is based on the original coupling of temperature-indicating lacquers and a high-speed camera system. Image analysis tools have been implemented to automatically extract the temporal evolution of isotherms. This method was applied to the fast induction treatment of a 4340 steel spur gear, allowing the full history of surface isotherms to be accurately documented for a sequential heating, i.e., a medium frequency preheating followed by a high frequency final heating. Three isotherms, i.e., 704, 816, and 927°C, were acquired every 0.3 ms with a spatial resolution of 0.04 mm per pixel. The information provided by the method is described and discussed. Finally, the transformation temperature Ac1 is linked to the temperature on specific locations of the gear tooth.

  5. Electron Microprobe Analysis Techniques for Accurate Measurements of Apatite

    NASA Astrophysics Data System (ADS)

    Goldoff, B. A.; Webster, J. D.; Harlov, D. E.

    2010-12-01

    Apatite [Ca5(PO4)3(F, Cl, OH)] is a ubiquitous accessory mineral in igneous, metamorphic, and sedimentary rocks. The mineral contains halogens and hydroxyl ions, which can provide important constraints on fugacities of volatile components in fluids and other phases in igneous and metamorphic environments in which apatite has equilibrated. Accurate measurements of these components in apatite are therefore necessary. Analyzing apatite by electron microprobe (EMPA), which is a commonly used geochemical analytical technique, has often been found to be problematic and previous studies have identified sources of error. For example, Stormer et al. (1993) demonstrated that the orientation of an apatite grain relative to the incident electron beam could significantly affect the concentration results. In this study, a variety of alternative EMPA operating conditions for apatite analysis were investigated: a range of electron beam settings, count times, crystal grain orientations, and calibration standards were tested. Twenty synthetic anhydrous apatite samples that span the fluorapatite-chlorapatite solid solution series, and whose halogen concentrations were determined by wet chemistry, were analyzed. Accurate measurements of these samples were obtained with many EMPA techniques. One effective method includes setting a static electron beam to 10-15nA, 15kV, and 10 microns in diameter. Additionally, the apatite sample is oriented with the crystal’s c-axis parallel to the slide surface and the count times are moderate. Importantly, the F and Cl EMPA concentrations are in extremely good agreement with the wet-chemical data. We also present EMPA operating conditions and techniques that are problematic and should be avoided. J.C. Stormer, Jr. et al., Am. Mineral. 78 (1993) 641-648.

  6. 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

  7. ELODIE: A spectrograph for accurate radial velocity measurements.

    NASA Astrophysics Data System (ADS)

    Baranne, A.; Queloz, D.; Mayor, M.; Adrianzyk, G.; Knispel, G.; Kohler, D.; Lacroix, D.; Meunier, J.-P.; Rimbaud, G.; Vin, A.

    1996-10-01

    The fibre-fed echelle spectrograph of Observatoire de Haute-Provence, ELODIE, is presented. This instrument has been in operation since the end of 1993 on the 1.93 m telescope. ELODIE is designed as an updated version of the cross-correlation spectrometer CORAVEL, to perform very accurate radial velocity measurements such as needed in the search, by Doppler shift, for brown-dwarfs or giant planets orbiting around nearby stars. In one single exposure a spectrum at a resolution of 42000 (λ/{DELTA}λ) ranging from 3906A to 6811A is recorded on a 1024x1024 CCD. This performance is achieved by using a tanθ=4 echelle grating and a combination of a prism and a grism as cross-disperser. An automatic on-line data treatment reduces all the ELODIE echelle spectra and computes cross-correlation functions. The instrument design and the data reduction algorithms are described in this paper. The efficiency and accuracy of the instrument and its long term instrumental stability allow us to measure radial velocities with an accuracy better than 15m/s for stars up to 9th magnitude in less than 30 minutes exposure time. Observations of 16th magnitude stars are also possible to measure velocities at about 1km/s accuracy. For classic spectroscopic studies (S/N>100) 9th magnitude stars can be observed in one hour exposure time.

  8. 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

  9. Accurate multipixel phase measurement with classical-light interferometry

    NASA Astrophysics Data System (ADS)

    Singh, Mandeep; Khare, Kedar; Jha, Anand Kumar; Prabhakar, Shashi; Singh, R. P.

    2015-02-01

    We demonstrate accurate phase measurement from experimental low photon level interferograms using a constrained optimization method that takes into account the expected redundancy in the unknown phase function. This approach is shown to have significant noise advantage over traditional methods, such as balanced homodyning or phase shifting, that treat individual pixels in the interference data as independent of each other. Our interference experiments comparing the optimization method with the traditional phase-shifting method show that when the same photon resources are used, the optimization method provides phase recoveries with tighter error bars. In particular, rms phase error performance of the optimization method for low photon number data (10 photons per pixel) shows a >5 × noise gain over the phase-shifting method. In our experiments where a laser light source is used for illumination, the results imply phase measurement with an accuracy better than the conventional single-pixel-based shot-noise limit that assumes independent phases at individual pixels. The constrained optimization approach presented here is independent of the nature of the light source and may further enhance the accuracy of phase detection when a nonclassical-light source is used.

  10. Fast processing techniques for accurate ultrasonic range measurements

    NASA Astrophysics Data System (ADS)

    Barshan, Billur

    2000-01-01

    Four methods of range measurement for airborne ultrasonic systems - namely simple thresholding, curve-fitting, sliding-window, and correlation detection - are compared on the basis of bias error, standard deviation, total error, robustness to noise, and the difficulty/complexity of implementation. Whereas correlation detection is theoretically optimal, the other three methods can offer acceptable performance at much lower cost. Performances of all methods have been investigated as a function of target range, azimuth, and signal-to-noise ratio. Curve fitting, sliding window, and thresholding follow correlation detection in the order of decreasing complexity. Apart from correlation detection, minimum bias and total error is most consistently obtained with the curve-fitting method. On the other hand, the sliding-window method is always better than the thresholding and curve-fitting methods in terms of minimizing the standard deviation. The experimental results are in close agreement with the corresponding simulation results. Overall, the three simple and fast processing methods provide a variety of attractive compromises between measurement accuracy and system complexity. Although this paper concentrates on ultrasonic range measurement in air, the techniques described may also find application in underwater acoustics.

  11. 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

  12. 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

  13. Rapid, accurate, and direct determination of total lycopene content in tomato paste

    NASA Astrophysics Data System (ADS)

    Bicanic, D.; Anese, M.; Luterotti, S.; Dadarlat, D.; Gibkes, J.; Lubbers, M.

    2003-01-01

    Lycopene that imparts red color to the tomato fruit is the most potent antioxidant among carotenes, an important nutrient and also used as a color ingredient in many food formulations. Since cooked and processed foods derived from tomatoes were shown to provide optimal lycopene boost, products such as paste, puree, juice, etc. are nowadays gaining popularity as dietary sources. The analysis of lycopene in tomato paste (partially dehydrated product prepared by vacuum concentrating tomato juice) is carried out using either high pressure liquid chromatography (HPLC), spectrophotometry, or by evaluating the color. The instability of lycopene during processes of extraction, etc., handling, and disposal of organic solvents makes the preparation of a sample for the analysis a delicate task. Despite a recognized need for accurate and rapid assessment of lycopene in tomato products no such method is available at present. The study described here focuses on a direct determination of a total lycopene content in different tomato pastes by means of the laser optothermal window (LOW) method at 502 nm. The concentration of lycopene in tomato paste ranged between 25 and 150 mg per 100 g product; the results are in excellent agreement with those obtained by spectrophotometry. The time needed to complete LOW analysis is very short, so that decomposition of pigment and the formation of artifacts are minimized. Preliminary results indicate a good degree of reproducibility making the LOW method suitable for routine assays of lycopene content in tomato paste.

  14. Progress on FP13 Total Cross Section Measurements Capability

    SciTech Connect

    Ullmann, John Leonard; Couture, Aaron Joseph; Koehler, Paul E.; Mocko, Michal; Mosby, Shea Morgan; Wender, Stephen Arthur

    2016-09-26

    An accurate knowledge of the neutron capture cross section is important for many applications. Experimental measurements are important since theoretical calculations of capture have been notoriously difficult, with the ratio of measured to calculated cross sections often a factor of 2 or more in the 10 keV to 1 MeV region. However, a direct measurement of capture cannot be made on many interesting radioactive nuclides because of their short half-life or backgrounds caused by their nuclear decay. On the other hand, neutron transmission measurements of the total cross section are feasible for a wide range of radioactive nuclides since the detectors are far from the sample, and often are less sensitive to decay radiation. The parameters extracted from a total cross section measurement, which include the average resonance spacing, the neutron strength function, and the average total radiation width, (Γγ), provide tight constraints on the calculation of the capture cross section, and when applied produce much more accurate results. These measurements can be made using the intense epithermal neutron flux at the Lujan Center on relatively small quantities of target material. It was the purpose of this project to investigate and develop the capability to make these measurements. A great deal of progress was made towards establishing this capability during 2016, including setting up the flight path and obtaining preliminary results, but more work remains to be done.

  15. 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.

  16. Measured flexion following total knee arthroplasty.

    PubMed

    Mai, Kenny T; Verioti, Christopher A; Hardwick, Mary E; Ezzet, Kace A; Copp, Steven N; Colwell, Clifford W

    2012-10-01

    Postoperative flexion is an important factor in the outcome of total knee arthroplasty. Although normal activities of daily living require a minimum of 105° to 110° of flexion, patients from non-Western cultures often engage in activities such as kneeling and squatting that require higher flexion. The desire to achieve greater flexion serves as the driving force for prosthetic modifications, including high-flexion designs. Techniques used to measure knee flexion and knee position during measurement are not often described or are different depending on the examiner. The purpose of this study was to compare active (self) and passive (assisted) flexion after successful total knee arthroplasty for 5 prostheses (2 standard and 3 high-flexion) using clinical (goniometer) and radiographic (true lateral radiograph) measurement techniques by different independent examiners.At a mean follow-up of 2.7 years (range, 1-5.6 years), a total of 108 patients (144 total knee arthroplasties) had completed the study. Mean postoperative active flexion was 111° clinically and 109° radiographically for the standard designs and 114° clinically and 117° radiographically for the high-flexion designs. Adding passive flexion increased flexion to 115° clinically and 117° radiographically for the standard designs and 119° clinically and 124° radiographically for the high-flexion designs. Flexion differences between the 2 measurement techniques (active vs passive and clinically vs radiographically) were statistically significant (P<.05). These findings demonstrate the importance of describing how flexion is measured in studies and understanding how the method of measurement can affect the findings.

  17. 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

  18. Measuring Total and Germinable Spore Populations

    NASA Technical Reports Server (NTRS)

    Noell, A.C.; Yung, P.T.; Yang, W.; Lee, C.; Ponce, A.

    2011-01-01

    It has been shown that bacterial endospores can be enumerated using a microscopy based assay that images the luminescent halos from terbium ions bound to dipicolinic acid, a spore specific chemical marker released upon spore germination. Further development of the instrument has simplified it towards automation while at the same time improving image quality. Enumeration of total spore populations has also been developed allowing measurement of the percentage of viable spores in any population by comparing the germinable/culturable spores to the total. Percentage viability will allow a more quantitative comparison of the ability of spores to survive across a wide range of extreme environments.

  19. Measurement of total organic concentration in water

    NASA Technical Reports Server (NTRS)

    Winkler, E.

    1978-01-01

    Instrument for determining total organic concentration in water uses no corrosive reagents or gases. Instead continuous ultraviolet photolysis process converts organic compounds to carbon dioxide (CO2). CO2 electrode is used to measure CO2 content. Only reagent necessary is oxygen, generated in situ by electrolyzing some water. In addition to application in aerospace industry, system has potential uses in pollution monitoring and in laboratory analyses.

  20. 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

  1. 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

  2. Accurate Alternative Measurements for Female Lifetime Reproductive Success in Drosophila melanogaster

    PubMed Central

    Nguyen, Trinh T. X.; Moehring, Amanda J.

    2015-01-01

    Fitness is an individual’s ability to survive and reproduce, and is an important concept in evolutionary biology. However, accurately measuring fitness is often difficult, and appropriate fitness surrogates need to be identified. Lifetime reproductive success, the total progeny an organism can produce in their lifetime, is thought to be a suitable proxy for fitness, but the measure of an organism’s reproductive output across a lifetime can be difficult or impossible to obtain. Here we demonstrate that the short-term measure of reproductive success across five days provides a reasonable prediction of an individual's total lifetime reproductive success in Drosophila melanogaster. However, the lifetime reproductive success of a female that has only mated once is not correlated to the lifetime reproductive success of a female that is allowed to mate multiple times, demonstrating that these measures should not serve as surrogates nor be used to make inferences about one another. PMID:26125633

  3. Accurate mass replacement method for the sediment concentration measurement with a constant volume container

    NASA Astrophysics Data System (ADS)

    Ban, Yunyun; Chen, Tianqin; Yan, Jun; Lei, Tingwu

    2017-04-01

    The measurement of sediment concentration in water is of great importance in soil erosion research and soil and water loss monitoring systems. The traditional weighing method has long been the foundation of all the other measuring methods and instrument calibration. The development of a new method to replace the traditional oven-drying method is of interest in research and practice for the quick and efficient measurement of sediment concentration, especially field measurements. A new method is advanced in this study for accurately measuring the sediment concentration based on the accurate measurement of the mass of the sediment-water mixture in the confined constant volume container (CVC). A sediment-laden water sample is put into the CVC to determine its mass before the CVC is filled with water and weighed again for the total mass of the water and sediments in the container. The known volume of the CVC, the mass of sediment-laden water, and sediment particle density are used to calculate the mass of water, which is replaced by sediments, therefore sediment concentration of the sample is calculated. The influence of water temperature was corrected by measuring water density to determine the temperature of water before measurements were conducted. The CVC was used to eliminate the surface tension effect so as to obtain the accurate volume of water and sediment mixture. Experimental results showed that the method was capable of measuring the sediment concentration from 0.5 up to 1200 kg m‑3. A good liner relationship existed between the designed and measured sediment concentrations with all the coefficients of determination greater than 0.999 and the averaged relative error less than 0.2%. All of these seem to indicate that the new method is capable of measuring a full range of sediment concentration above 0.5 kg m‑3 to replace the traditional oven-drying method as a standard method for evaluating and calibrating other methods.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Apparatus designed for very accurate measurement of the optical reflection.

    PubMed

    Piombini, Hervé; Voarino, Philippe

    2007-12-20

    The described instrument is a new reflectometer designed to check the normal specular reflectance of 40,000 reflectors necessary for the Laser Megajoule (LMJ). This new reflectometer has a high accuracy over the 400-950 nm wavelength range and allows the delicate measurement of shaped parts. The measurements are relative and several reference mirrors, which are low loss dielectric mirrors [R(lambda)>99.9%], are used for the standardization. The apparatus gives an excellent repeatability (< 0.06% at 2sigma) thanks to its design and automatic focalization imaging system. After a brief review that is related to performance evolution of the spectrophotometers, our facility and its components are described. The methodology of focusing and calibration are explained. The capabilities of our device are illustrated through some measurements realized on flat or shaped samples.

  10. Accurate measurement of gas volumes by liquid displacement

    NASA Technical Reports Server (NTRS)

    Christian, J. D.

    1972-01-01

    Mariotte bottle as liquid displacement device was used to measure gas volumes at flow rates that are far below threshold of wet test gas meters. Study of factors affecting amount of liquid displaced by gas flow was completed, and equations were derived which relate different variables.

  11. APPARATUS FOR MEASURING TOTAL NEUTRON CROSS SECTIONS

    DOEpatents

    Cranberg, L.

    1959-10-13

    An apparatus is described for measuring high-resolution total neutron cross sections at high counting rate in the range above 50-kev neutron energy. The pulsed-beam time-of-flight technique is used to identify the neutrons of interest which are produced in the target of an electrostatic accelerator. Energy modulation of the accelerator . makes it possible to make observations at 100 energy points simultaneously. 761O An apparatus is described for monitoring the proton resonance of a liquid which is particulariy useful in the continuous purity analysis of heavy water. A hollow shell with parallel sides defines a meander chamber positioned within a uniform magnetic fieid. The liquid passes through an inlet at the outer edge of the chamber and through a spiral channel to the central region of the chamber where an outlet tube extends into the chamber perpendicular to the magnetic field. The radiofrequency energy for the monitor is coupled to a coil positioned coaxially with the outlet tube at its entrance point within the chamber. The improvement lies in the compact mechanical arrangement of the monitor unit whereby the liquid under analysis is subjected to the same magnetic field in the storage and sensing areas, and the entire unit is shielded from external electrostatic influences.

  12. 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.

  13. Accurate reconstruction in measurement of microstructures using digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolei; Zhang, Xiangchao; Xiao, Hong; Xu, Min

    2016-11-01

    Due to the limitation of traditional interferometry, digital holographic microscopy has attracted intensive attention for its capability of measuring complex shapes. However, speckles are inevitable in the recorded interferometric patterns, thereby polluting the reconstructed surface topographies. In this paper, a phase-shifting interferometer is built to realize the in-axis digital holographic microscopy. The anti-aliasing shift-invariant contourlet transform (ASCT) is used for reconstructing the measured surfaces. By avoiding subsampling in the scale and directional filtering schemes, the problems of frequency aliasing and phase distortion can be effectively solved. Practical experiments show that speckles can be recognized and removed straightforwardly. Therefore the proposed method has excellent performance for reconstructing structured surfaces.

  14. 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.

  15. Application of second-order-accurate Total Variation Diminishing (TVD) schemes to the Euler equations in general geometries

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Kutler, P.

    1983-01-01

    A one-parameter family of explicit and implicit second-order-accurate, entropy satisfying, total variation diminishing (TVD) schemes was developed by Harten. These TVD schemes were the property of not generating spurious oscillations for one-dimensional nonlinear scalar hyperbolic conservation laws and constant coefficient hyperbolic systems. Application of these methods to one- and two-dimensional fluid flows containing shocks (in Cartesian coordinates) yields highly accurate nonoscillatory numerical solutions. The goal of this work is to expand these methods to the multidimensional Euler equations in generalized coordinate systems. Some numerical results of shock waves impinging on cylindrical bodies are compared with MacCormack's method.

  16. 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.

  17. Model verification studies using accurate measurements of spin up

    NASA Technical Reports Server (NTRS)

    Hyun, J. M.

    1981-01-01

    The reliability and accuracy of the numerical code for spin up flows in a cylinder by comparing the numerical results against high resolution laser Doppler velocimeter (LDV) measurements of the azimuthal flows were checked. A computer code to generate numerical solution for axisymmetric rotating fluid in a cylinder was obtained and amended for routine use at MSFC. The numerical simulations used the Navier-Stokes equations in axisymmetric form and employed finite difference techniques on both constant and variable grids. The numerical solutions are analyzed to gain further insight into the fundamental questions analyzed in rotating fluid dynamics.

  18. Accurate measurement of mean sea level changes by altimetric satellites

    NASA Technical Reports Server (NTRS)

    Born, G. H.; Tapley, B. D.; Ries, J. C.; Stewart, R. H.

    1986-01-01

    A technique for monitoring changes in global mean sea levels using altimeter data from a well-tracked satellite is examined. The usefulness of this technique is evaluated by analyzing Seasat altimeter data obtained during July-September 1978. The effects of orbit errors, geoid errors, sampling intervals, tides, and atmosphere refraction on the calculation of the mean sea level are investigated. The data reveal that the stability of an altimeter can be determined with an accuracy of + or - 7 cm using globally averaged sea surface height measurements. The application of this procedure to the US/French Ocean Topography Experiment is discussed.

  19. Diamond micro-Raman thermometers for accurate gate temperature measurements

    SciTech Connect

    Simon, Roland B.; Pomeroy, James W.; Kuball, Martin

    2014-05-26

    Determining the peak channel temperature in AlGaN/GaN high electron mobility transistors and other devices with high accuracy is an important and challenging issue. A surface-sensitive thermometric technique is demonstrated, utilizing Raman thermography and diamond microparticles to measure the gate temperature. This technique enhances peak channel temperature estimation, especially when it is applied in combination with standard micro-Raman thermography. Its application to other metal-covered areas of devices, such as field plates is demonstrated. Furthermore, this technique can be readily applied to other material/device systems.

  20. Accurate measurement of curvilinear shapes by Virtual Image Correlation

    NASA Astrophysics Data System (ADS)

    Semin, B.; Auradou, H.; François, M. L. M.

    2011-10-01

    The proposed method allows the detection and the measurement, in the sense of metrology, of smooth elongated curvilinear shapes. Such measurements are required in many fields of physics, for example: mechanical engineering, biology or medicine (deflection of beams, fibers or filaments), fluid mechanics or chemistry (detection of fronts). Contrary to actual methods, the result is given in an analytical form of class C∞ (and not a finite set of locations or pixels) thus curvatures and slopes, often of great interest in science, are given with good confidence. The proposed Virtual Image Correlation (VIC) method uses a virtual beam, an image which consists in a lateral expansion of the curve with a bell-shaped gray level. This figure is deformed until it fits the best the physical image with a method issued from the Digital Image Correlation method in use in solid mechanics. The precision of the identification is studied in a benchmark and successfully compared to two state-of-the-art methods. Three practical examples are given: a bar bending under its own weight, a thin fiber transported by a flow within a fracture and a thermal front. The first allows a comparison with theoretical solution, the second shows the ability of the method to deal with complex shapes and crossings and the third deals with ill-defined image.

  1. 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

  2. Electrochemical valveless flow microsystems for ultra fast and accurate analysis of total isoflavones with integrated calibration.

    PubMed

    Blasco, Antonio Javier; Crevillén, Agustín González; de la Fuente, Pedro; González, María Cristina; Escarpa, Alberto

    2007-04-01

    A novel strategy integrating methodological calibration and analysis on board on a planar first-generation microfluidics system for the determination of total isoflavones in soy samples is proposed. The analytical strategy is conceptually proposed and successfully demonstrated on the basis of (i) the microchip design (with the possibility to use both reservoirs), (ii) the analytical characteristics of the developed method (statically zero intercept and excellent robustness between calibration slopes, RSDs < 5%), (iii) the irreversible electrochemical behaviour of isoflavone oxidation (no significant electrode fouling effect was observed between calibration and analysis runs) and (iv) the inherent versatility of the electrochemical end-channel configurations (possibility of use different pumping and detection media). Repeatability obtained in both standard (calibration) and real soy samples (analysis) with values of RSD less than 1% for the migration times indicated the stability of electroosmotic flow (EOF) during both integrated operations. The accuracy (an error of less than 6%) is demonstrated for the first time in these microsystems using a documented secondary standard from the Drug Master File (SW/1211/03) as reference material. Ultra fast calibration and analysis of total isoflavones in soy samples was integrated successfully employing 60 s each; enhancing notably the analytical performance of these microdevices with an important decrease in overall analysis times (less than 120 s) and with an increase in accuracy by a factor of 3.

  3. Accurate treatment of total photoabsorption cross sections by an ab initio time-dependent method

    NASA Astrophysics Data System (ADS)

    Daud, Mohammad Noh

    2014-09-01

    A detailed discussion of parallel and perpendicular transitions required for the photoabsorption of a molecule is presented within a time-dependent view. Total photoabsorption cross sections for the first two ultraviolet absorption bands of the N2O molecule corresponding to transitions from the X1 A' state to the 21 A' and 11 A'' states are calculated to test the reliability of the method. By fully considering the property of the electric field polarization vector of the incident light, the method treats the coupling of angular momentum and the parity differently for two kinds of transitions depending on the direction of the vector whether it is: (a) situated parallel in a molecular plane for an electronic transition between states with the same symmetry; (b) situated perpendicular to a molecular plane for an electronic transition between states with different symmetry. Through this, for those transitions, we are able to offer an insightful picture of the dynamics involved and to characterize some new aspects in the photoabsorption process of N2O. Our calculations predicted that the parallel transition to the 21 A' state is the major dissociation pathway which is in qualitative agreement with the experimental observations. Most importantly, a significant improvement in the absolute value of the total cross section over previous theoretical results [R. Schinke, J. Chem. Phys. 134, 064313 (2011), M.N. Daud, G.G. Balint-Kurti, A. Brown, J. Chem. Phys. 122, 054305 (2005), S. Nanbu, M.S. Johnson, J. Phys. Chem. A 108, 8905 (2004)] was obtained.

  4. Accurate treatment of total photoabsorption cross sections by an ab initio time-dependent method

    NASA Astrophysics Data System (ADS)

    Noh Daud, Mohammad

    2014-09-01

    A detailed discussion of parallel and perpendicular transitions required for the photoabsorption of a molecule is presented within a time-dependent view. Total photoabsorption cross sections for the first two ultraviolet absorption bands of the N2O molecule corresponding to transitions from the X1A' state to the 21A' and 11A'' states are calculated to test the reliability of the method. By fully considering the property of the electric field polarization vector of the incident light, the method treats the coupling of angular momentum and the parity differently for two kinds of transitions depending on the direction of the vector whether it is: (a) situated parallel in a molecular plane for an electronic transition between states with the same symmetry; (b) situated perpendicular to a molecular plane for an electronic transition between states with different symmetry. Through this, for those transitions, we are able to offer an insightful picture of the dynamics involved and to characterize some new aspects in the photoabsorption process of N2O. Our calculations predicted that the parallel transition to the 21A' state is the major dissociation pathway which is in qualitative agreement with the experimental observations. Most importantly, a significant improvement in the absolute value of the total cross section over previous theoretical results [R. Schinke, J. Chem. Phys. 134, 064313 (2011), M.N. Daud, G.G. Balint-Kurti, A. Brown, J. Chem. Phys. 122, 054305 (2005), S. Nanbu, M.S. Johnson, J. Phys. Chem. A 108, 8905 (2004)] was obtained.

  5. Numerical assessment of accurate measurements of laminar flame speed

    NASA Astrophysics Data System (ADS)

    Goulier, Joules; Bizon, Katarzyna; Chaumeix, Nabiha; Meynet, Nicolas; Continillo, Gaetano

    2016-12-01

    In combustion, the laminar flame speed constitutes an important parameter that reflects the chemistry of oxidation for a given fuel, along with its transport and thermal properties. Laminar flame speeds are used (i) in turbulent models used in CFD codes, and (ii) to validate detailed or reduced mechanisms, often derived from studies using ideal reactors and in diluted conditions as in jet stirred reactors and in shock tubes. End-users of such mechanisms need to have an assessment of their capability to predict the correct heat released by combustion in realistic conditions. In this view, the laminar flame speed constitutes a very convenient parameter, and it is then very important to have a good knowledge of the experimental errors involved with its determination. Stationary configurations (Bunsen burners, counter-flow flames, heat flux burners) or moving flames (tubes, spherical vessel, soap bubble) can be used. The spherical expanding flame configuration has recently become popular, since it can be used at high pressures and temperatures. With this method, the flame speed is not measured directly, but derived through the recording of the flame radius. The method used to process the radius history will have an impact on the estimated flame speed. Aim of this work is to propose a way to derive the laminar flame speed from experimental recording of expanding flames, and to assess the error magnitude.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Fission, total and neutron capture cross section measurements at ORELA

    SciTech Connect

    Guber, K.H.; Spencer, R.R.; Leal, L.C.; Larson, D.C.; Dos Santos, G.; Harvey, J.A.; Hill, N.W.

    1998-08-01

    In support of the Nuclear Criticality Predictability Program established in response to the Defense Nuclear Facility Safety Board Recommendation 93-2, time-of-flight (TOF) measurements of the fission cross sections of {sup 233}U in the neutron energy range from 0.36 eV to several hundred keV have been initiated at the Oak Ridge Electron Linear Accelerator (ORELA). Also total and capture cross sections of Al, Cl, and K in the energy range from about 100 eV to several hundred keV have been measured or are under way. The goal is to derive accurate cross section representations for the materials involved in criticality calculations of fuel storage, transportation, etc., configurations. Additional high-resolution measurements of the total cross sections of {sup 233}U below a few keV neutron energy are being planned for 1998, as well as for the other involved material. Evaluated data files in ENDF-6 format will be processed into formats for use in criticality analysis and utilized in benchmark data testing. Finally the data will be submitted for inclusion in ENDF/B.

  13. Intraoperative measurement of limb lengthening during total hip arthroplasty

    PubMed Central

    Papadopoulos, Dimitrios Vasileiou; Koulouvaris, Panagiotis; Aggelidakis, Georgios Charalambos; Tsantes, Andreas Georgios; Lykissas, Marios Georgios; Mavrodontidis, Alexandros

    2017-01-01

    Background: Limb length discrepancy (LLD) after total hip arthroplasty (THA) is a common problem which cannot be completely resolved. Many techniques have been described in order to minimize postoperative LLD, but most of these techniques are difficult to apply. Ideal technique must be simple and accurate. The most simple technique using a suture tied on the skin has well-known limitations, but its accuracy has not been evaluated before. Materials and Methods: Sixty THAs in sixty patients (mean age 71 years, 1:1 male to female ratio) with hip osteoarthritis (37 cases in the right, and 23 cases in the left side) were studied in this prospective study. In all surgeries, the intraoperataive measurement of limb lengthening was performed using a suture tied on the skin of the lateral pelvis. The accuracy of this technique and correlation between intraoperative and postoperative radiological measurements of lengthening were evaluated. Results: The mean preoperative LLD was –7.5 mm while the mean postoperative LLD was 1.58 mm. The accuracy of this technique, defined as the mean difference between the intraoperative and postoperative measurements was 1.8 mm. A strong correlation between these two measurements was noticed (r = 0.86). Conclusion: The accuracy and correlation index of this simple technique were similar to those of other techniques. The studied technique is quite accurate when attention is given to certain details, such as the amount of tension applied on the suture, the position of the tied point on the skin, and the position of the leg during measurements.

  14. NASA Measured Erika's Rainfall Totals From Space

    NASA Video Gallery

    GPM measured rainfall from Tropical Storm Erika August 21 through 29, 2015. The heaviest rainfall in the analysis was estimated to be over 307 mm (12.1 inches) in the area of Dominica. Credit: NASA...

  15. 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%.

  16. Low frequency oscillations in total ozone measurements

    NASA Technical Reports Server (NTRS)

    Gao, X. H.; Stanford, J. L.

    1989-01-01

    Low frequency oscillations with periods of approximately one to two months are found in eight years of global grids of total ozone data from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument. The low frequency oscillations corroborate earlier analyses based on four years of data. In addition, both annual and seasonal one-point correlation maps based on the 8-year TOMS data are presented. The results clearly show a standing dipole in ozone perturbations, oscillating with 35 to 50 day periods over the equatorial Indian Ocean-west Pacific region. This contrasts with the eastward moving dipole reported in other data sets. The standing ozone dipole appears to be a dynamical feature associated with vertical atmospheric motions. Consistent with prior analyses based on lower stratospheric temperature fields, large-scale standing patterns are also found in the extratropics of both hemispheres, correlated with ozone fluctuations over the equatorial west Pacific. In the Northern Hemisphere, a standing pattern is observed extending from the tropical Indian Ocean to the north Pacific, across North America, and down to the equatorial Atlantic Ocean region. This feature is most pronounced in the NH summer.

  17. 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...

  18. FAMBE-pH: a fast and accurate method to compute the total solvation free energies of proteins.

    PubMed

    Vorobjev, Yury N; Vila, Jorge A; Scheraga, Harold A

    2008-09-04

    A fast and accurate method to compute the total solvation free energies of proteins as a function of pH is presented. The method makes use of a combination of approaches, some of which have already appeared in the literature; (i) the Poisson equation is solved with an optimized fast adaptive multigrid boundary element (FAMBE) method; (ii) the electrostatic free energies of the ionizable sites are calculated for their neutral and charged states by using a detailed model of atomic charges; (iii) a set of optimal atomic radii is used to define a precise dielectric surface interface; (iv) a multilevel adaptive tessellation of this dielectric surface interface is achieved by using multisized boundary elements; and (v) 1:1 salt effects are included. The equilibrium proton binding/release is calculated with the Tanford-Schellman integral if the proteins contain more than approximately 20-25 ionizable groups; for a smaller number of ionizable groups, the ionization partition function is calculated directly. The FAMBE method is tested as a function of pH (FAMBE-pH) with three proteins, namely, bovine pancreatic trypsin inhibitor (BPTI), hen egg white lysozyme (HEWL), and bovine pancreatic ribonuclease A (RNaseA). The results are (a) the FAMBE-pH method reproduces the observed pK a's of the ionizable groups of these proteins within an average absolute value of 0.4 p K units and a maximum error of 1.2 p K units and (b) comparison of the calculated total pH-dependent solvation free energy for BPTI, between the exact calculation of the ionization partition function and the Tanford-Schellman integral method, shows agreement within 1.2 kcal/mol. These results indicate that calculation of total solvation free energies with the FAMBE-pH method can provide an accurate prediction of protein conformational stability at a given fixed pH and, if coupled with molecular mechanics or molecular dynamics methods, can also be used for more realistic studies of protein folding, unfolding, and

  19. 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.

  20. A method for measuring total thiaminase activity in fish tissues

    USGS Publications Warehouse

    Zajicek, James L.; Tillitt, Donald E.; Honeyfield, Dale C.; Brown, Scott B.; Fitzsimons, John D.

    2005-01-01

    An accurate, quantitative, and rapid method for the measurement of thiaminase activity in fish samples is required to provide sufficient information to characterize the role of dietary thiaminase in the onset of thiamine deficiency in Great Lakes salmonines. A radiometric method that uses 14C-thiamine was optimized for substrate and co-substrate (nicotinic acid) concentrations, incubation time, and sample dilution. Total thiaminase activity was successfully determined in extracts of selected Great Lakes fishes and invertebrates. Samples included whole-body and selected tissues of forage fishes. Positive control material prepared from frozen alewives Alosa pseudoharengus collected in Lake Michigan enhanced the development and application of the method. The method allowed improved discrimination of thiaminolytic activity among forage fish species and their tissues. The temperature dependence of the thiaminase activity observed in crude extracts of Lake Michigan alewives followed a Q10 = 2 relationship for the 1-37??C temperature range, which is consistent with the bacterial-derived thiaminase I protein. ?? Copyright by the American Fisheries Society 2005.

  1. 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...

  2. Pose measurement of Anterior Pelvic Plane based on inertial measurement unit in total hip replacement surgeries.

    PubMed

    Zhe Cao; Shaojie Su; Hong Chen; Hao Tang; Yixin Zhou; Zhihua Wang

    2016-08-01

    In Total Hip Replacement (THR), inaccurate measurement of Anterior Pelvic Plane (APP), which is usually used as a reference plane, will lead to malposition of the acetabular prosthesis. As a result, the risk of impingement, dislocation and wear will increase and the safe range of motion will be limited. In order to acquire the accurate pose of APP, a measurement system is designed in this paper, which includes two parts: one is used to estimate the initial pose of APP and the other is used to trail dynamic motion of APP. Both parts are composed of an Inertial Measurement Unit (IMU) and magnetometer sensors. An Extended Kalman Filter (EKF) is adopted to fuse the data from IMU and the magnetometer sensors to estimate the orientation of the pelvis. The test results show that the error angle between calculated axis and true axis of the pelvis in geodetic coordinate frame is less than 1.2 degree, which meets the requirement of the surgery.

  3. Accurate measurements of the acoustical physical constants of synthetic alpha-quartz for SAW devices.

    PubMed

    Kushibiki, Juin-ichi; Takanaga, Izumi; Nishiyama, Shouichi

    2002-01-01

    Accurate measurements of the acoustical physical constants (elastic constants, piezoelectric constants, dielectric constants, and density) of commercially available and widely used surface acoustic wave (SAW)-grade synthetic a-quartz are reported. The propagation directions and modes of bulk waves optimal for accurately determining the constants were selected through numerical calculations, and three principal X-, Y-, and Z-cut specimens and several rotated Y-cut specimens were prepared from a single crystal ingot to determine the constants and to confirm their accuracy. All of the constants were determined through highly accurate measurements of the longitudinal velocities, shear velocities, dielectric constants, and density. The velocity values measured for the specimens that were not used to determine the constants agreed well with those calculated from the determined constants, within a difference of +/- 0.20 m/s (+/- 0.004%).

  4. Positron interactions with water–total elastic, total inelastic, and elastic differential cross section measurements

    SciTech Connect

    Tattersall, Wade; Chiari, Luca; Machacek, J. R.; Anderson, Emma; Sullivan, James P.; White, Ron D.; Brunger, M. J.; Buckman, Stephen J.; Garcia, Gustavo; Blanco, Francisco

    2014-01-28

    Utilising a high-resolution, trap-based positron beam, we have measured both elastic and inelastic scattering of positrons from water vapour. The measurements comprise differential elastic, total elastic, and total inelastic (not including positronium formation) absolute cross sections. The energy range investigated is from 1 eV to 60 eV. Comparison with theory is made with both R-Matrix and distorted wave calculations, and with our own application of the Independent Atom Model for positron interactions.

  5. Automated analyzer for aircraft measurements of atmospheric methane and total hydrocarbons

    NASA Technical Reports Server (NTRS)

    Cofer, W. R., III; Purgold, G. C.

    1981-01-01

    An automated methane/total hydrocarbon analyzer is presented, which can produce alternate methane/total hydrocarbon measurements every 7 seconds to provide the spatial resolution required for regional hydrocarbon measurements at aircraft speeds. The construction and sampling techniques developed for the aircraft mounted system are discussed. A technique to periodically measure atmosphere oxygen is incorporated into the analyzer to ensure accurate hydrocarbon measurements, and a data collection methodology is developed to minimize errors resulting from changes in flame ionization detector sensitivity at different altitudes. Aircraft data acquired at the 1979 Southeastern Virginia Urban Plume Study are also presented, which illustrate the application of the instrument to a troposphere pollution plume.

  6. 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...

  7. Accurate measurement method of Fabry-Perot cavity parameters via optical transfer function

    SciTech Connect

    Bondu, Francois; Debieu, Olivier

    2007-05-10

    It is shown how the transfer function from frequency noise to a Pound-Drever-Hall signal for a Fabry-Perot cavity can be used to accurately measure cavity length, cavity linewidth, mirror curvature, misalignments, laser beam shape mismatching with resonant beam shape, and cavity impedance mismatching with respect to vacuum.

  8. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... production and utilization? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  9. 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? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  10. 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? 3275.15 Section 3275.15 Public Lands: Interior Regulations Relating to Public...) GEOTHERMAL RESOURCE LEASING Conducting Utilization Operations § 3275.15 How accurately must I measure my production and utilization? It depends on whether you use a meter to calculate Federal production or...

  11. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1986-01-01

    A method for the simultaneous flow cytometric measurement of the total DNA content and the level of DNA synthesis in normal and malignant cells is disclosed. The sensitivity of the method allows a study of cell cycle traverse rates for large scale cell populations as well as single cell measurements. A DNA stain such as propidium iodide is used as the probe for the measurement of total DNA content and a monoclonal antibody reactive with a DNA precursor such as bromodeoxyuridine (BrdU) is used as a probe for the measurement of BrdU uptake by the cells as a measure of DNA synthesis.

  12. 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.

  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. 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.

  15. Determination of Ionospheric Total Electron Content Derived from Gnss Measurements

    NASA Astrophysics Data System (ADS)

    Inyurt, S.; Mekik, C.; Yildirim, O.

    2014-12-01

    Global Navigation Satellite System (GNSS) has been used in numerous fields especially related to satellite- based radio navigation system for a long time. Ionosphere, one of the upper atmosphere layers ranges from 60 km to 1500 km, is a dispersive medium and it includes a number of free electrons and ions. The ionization is mainly subject to the sun and its activity. Ionospheric activity depends also on seasonal, diurnal variations and geographical location. Total Electron Content (TEC), which is also called Slant Total Electron Content (STEC), is a parameter that changes according to ionospheric conditions and has highly variable structure. Furthermore, Vertical TEC (VTEC) can be explained as TEC value in the direction of zenith. Thanks to VTEC, TEC values can be modelled. TEC is measured in units of TECU and 1TECU= 1016 electrons/m2. Ionospheric modelling has a great importance for improving the accuracies of positioning and understanding the ionosphere. Thus, various models have been developed to detect TEC value in the last years. Single Layer Model (SLM) which provides determining TEC value and GPS positioning in the ionosphere accurately is one of the most commonly used models. SLM assumes that all free electrons are concentrated in a shell of infinitesimal thickness. In this paper SLM model was used to derive TEC values by means of Bernese 5.0 program developed by the University of Bern, Sweden. In this study, we have used regional ionosphere model to derive TEC value. First of all, GPS data have been collected from 10 stations in Turkey and 13 IGS stations for 7 days from 06.03.2010 to 12.03.2010. Then, Regional Ionosphere Model (RIM) is created with the reference of the GPS data. At the end of the process, the result files are stored as IONEX format. TEC results for those days are obtained with two hours interval. TEC variation related to the research area ranges from nearly 6 TECU to approximately 20 TECU. The obtained results show that TEC values start

  16. 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.

  17. Accurate and Reliable Quantification of Total Microalgal Fuel Potential as Fatty Acid Methyl Esters by in situ Transesterfication

    SciTech Connect

    Laurens, L. M. L.; Quinn, M.; Van Wychen, S.; Templeton, D. W.; Wolfrum, E. J.

    2012-04-01

    In the context of algal biofuels, lipids, or better aliphatic chains of the fatty acids, are perhaps the most important constituents of algal biomass. Accurate quantification of lipids and their respective fuel yield is crucial for comparison of algal strains and growth conditions and for process monitoring. As an alternative to traditional solvent-based lipid extraction procedures, we have developed a robust whole-biomass in situ transesterification procedure for quantification of algal lipids (as fatty acid methyl esters, FAMEs) that (a) can be carried out on a small scale (using 4-7 mg of biomass), (b) is applicable to a range of different species, (c) consists of a single-step reaction, (d) is robust over a range of different temperature and time combinations, and (e) tolerant to at least 50% water in the biomass. Unlike gravimetric lipid quantification, which can over- or underestimate the lipid content, whole biomass transesterification reflects the true potential fuel yield of algal biomass. We report here on the comparison of the yield of FAMEs by using different catalysts and catalyst combinations, with the acid catalyst HCl providing a consistently high level of conversion of fatty acids with a precision of 1.9% relative standard deviation. We investigate the influence of reaction time, temperature, and biomass water content on the measured FAME content and profile for 4 different samples of algae (replete and deplete Chlorella vulgaris, replete Phaeodactylum tricornutum, and replete Nannochloropsis sp.). We conclude by demonstrating a full mass balance closure of all fatty acids around a traditional lipid extraction process.

  18. Accurate and reliable quantification of total microalgal fuel potential as fatty acid methyl esters by in situ transesterification.

    PubMed

    Laurens, Lieve M L; Quinn, Matthew; Van Wychen, Stefanie; Templeton, David W; Wolfrum, Edward J

    2012-04-01

    In the context of algal biofuels, lipids, or better aliphatic chains of the fatty acids, are perhaps the most important constituents of algal biomass. Accurate quantification of lipids and their respective fuel yield is crucial for comparison of algal strains and growth conditions and for process monitoring. As an alternative to traditional solvent-based lipid extraction procedures, we have developed a robust whole-biomass in situ transesterification procedure for quantification of algal lipids (as fatty acid methyl esters, FAMEs) that (a) can be carried out on a small scale (using 4-7 mg of biomass), (b) is applicable to a range of different species, (c) consists of a single-step reaction, (d) is robust over a range of different temperature and time combinations, and (e) tolerant to at least 50% water in the biomass. Unlike gravimetric lipid quantification, which can over- or underestimate the lipid content, whole biomass transesterification reflects the true potential fuel yield of algal biomass. We report here on the comparison of the yield of FAMEs by using different catalysts and catalyst combinations, with the acid catalyst HCl providing a consistently high level of conversion of fatty acids with a precision of 1.9% relative standard deviation. We investigate the influence of reaction time, temperature, and biomass water content on the measured FAME content and profile for 4 different samples of algae (replete and deplete Chlorella vulgaris, replete Phaeodactylum tricornutum, and replete Nannochloropsis sp.). We conclude by demonstrating a full mass balance closure of all fatty acids around a traditional lipid extraction process.

  19. System to measure accurate temperature dependence of electric conductivity down to 20 K in ultrahigh vacuum.

    PubMed

    Sakai, C; Takeda, S N; Daimon, H

    2013-07-01

    We have developed the new in situ electrical-conductivity measurement system which can be operated in ultrahigh vacuum (UHV) with accurate temperature measurement down to 20 K. This system is mainly composed of a new sample-holder fixing mechanism, a new movable conductivity-measurement mechanism, a cryostat, and two receptors for sample- and four-probe holders. Sample-holder is pushed strongly against the receptor, which is connected to a cryostat, by using this new sample-holder fixing mechanism to obtain high thermal conductivity. Test pieces on the sample-holders have been cooled down to about 20 K using this fixing mechanism, although they were cooled down to only about 60 K without this mechanism. Four probes are able to be touched to a sample surface using this new movable conductivity-measurement mechanism for measuring electrical conductivity after making film on substrates or obtaining clean surfaces by cleavage, flashing, and so on. Accurate temperature measurement is possible since the sample can be transferred with a thermocouple and∕or diode being attached directly to the sample. A single crystal of Bi-based copper oxide high-Tc superconductor (HTSC) was cleaved in UHV to obtain clean surface, and its superconducting critical temperature has been successfully measured in situ. The importance of in situ measurement of resistance in UHV was demonstrated for this HTSC before and after cesium (Cs) adsorption on its surface. The Tc onset increase and the Tc offset decrease by Cs adsorption were observed.

  20. Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup

    NASA Astrophysics Data System (ADS)

    Natividad, Eva; Castro, Miguel; Mediano, Arturo

    2008-03-01

    Accurate measurements of the specific absorption rate (SAR) of solids and fluids were obtained by a calorimetric method, using a special-purpose setup working under adiabatic conditions. Unlike in current nonadiabatic setups, the weak heat exchange with the surroundings allowed a straightforward determination of temperature increments, avoiding the usual initial-time approximations. The measurements performed on a commercial magnetite aqueous ferrofluid revealed a good reproducibility (4%). Also, the measurements on a copper sample allowed comparison between experimental and theoretical values: adiabatic conditions gave SAR values only 3% higher than the theoretical ones, while the typical nonadiabatic method underestimated SAR by 21%.

  1. Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Reed, Zachary D.; Sperling, Brent; van Zee, Roger D.; Whetstone, James R.; Gillis, Keith A.; Hodges, Joseph T.

    2014-06-01

    We have developed a portable photoacoustic spectrometer that offers routine, precise and accurate measurements of the molar concentration of atmospheric carbon. The temperature-controlled spectrometer continuously samples dried atmospheric air and employs an intensity-modulated distributed feedback laser and fiber amplifier operating near 1.57 µm. For measurements of carbon dioxide in air, we demonstrate a measurement precision (60-s averaging time) of 0.15 µmol mol-1 and achieve a standard uncertainty of 0.8 µmol mol-1 by calibrating the analyzer response in terms of certified gas mixtures. We also investigate how water vapor affects the photoacoustic signal by promoting collisional relaxation of the carbon dioxide.

  2. 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.

  3. Device for measuring the total concentration of oxygen in gases

    DOEpatents

    Isaacs, Hugh S.; Romano, Anthony J.

    1977-01-01

    This invention provides a CO equilibrium in a device for measuring the total concentration of oxygen impurities in a fluid stream. To this end, the CO equilibrium is produced in an electrochemical measuring cell by the interaction of a carbon element in the cell with the chemically combined and uncombined oxygen in the fluid stream at an elevated temperature.

  4. 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.

  5. Accurate microfour-point probe sheet resistance measurements on small samples.

    PubMed

    Thorsteinsson, Sune; Wang, Fei; Petersen, Dirch H; Hansen, Torben Mikael; Kjaer, Daniel; Lin, Rong; Kim, Jang-Yong; Nielsen, Peter F; Hansen, Ole

    2009-05-01

    We show that accurate sheet resistance measurements on small samples may be performed using microfour-point probes without applying correction factors. Using dual configuration measurements, the sheet resistance may be extracted with high accuracy when the microfour-point probes are in proximity of a mirror plane on small samples with dimensions of a few times the probe pitch. We calculate theoretically the size of the "sweet spot," where sufficiently accurate sheet resistances result and show that even for very small samples it is feasible to do correction free extraction of the sheet resistance with sufficient accuracy. As an example, the sheet resistance of a 40 microm (50 microm) square sample may be characterized with an accuracy of 0.3% (0.1%) using a 10 microm pitch microfour-point probe and assuming a probe alignment accuracy of +/-2.5 microm.

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

    PubMed

    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

    2014-05-01

    X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without 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 meaningful high-resolution signals from fewer diffraction measurements.

  7. 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.

  8. Brewer spectrometer total ozone column measurements in Sodankylä

    NASA Astrophysics Data System (ADS)

    Karppinen, Tomi; Lakkala, Kaisa; Karhu, Juha M.; Heikkinen, Pauli; Kivi, Rigel; Kyrö, Esko

    2016-06-01

    Brewer total ozone column measurements started in Sodankylä in May 1988, 9 months after the signing of The Montreal Protocol. The Brewer instrument has been well maintained and frequently calibrated since then to produce a high-quality ozone time series now spanning more than 25 years. The data have now been uniformly reprocessed between 1988 and 2014. The quality of the data has been assured by automatic data rejection rules as well as by manual checking. Daily mean values calculated from the highest-quality direct sun measurements are available 77 % of time with up to 75 measurements per day on clear days. Zenith sky measurements fill another 14 % of the time series and winter months are sparsely covered by moon measurements. The time series provides information to survey the evolution of Arctic ozone layer and can be used as a reference point for assessing other total ozone column measurement practices.

  9. 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.

  10. Accurate measurement of spatial noise portraits of photosensors of digital cameras

    NASA Astrophysics Data System (ADS)

    Cheremkhin, P. A.; Evtikhiev, N. N.; Krasnov, V. V.; Kulakov, M. N.; Starikov, R. S.

    2016-08-01

    Method of measurement of accurate portraits of light and dark spatial noise of photosensors is described. The method consists of four steps: creation of spatially homogeneous illumination; shooting light and dark frames; digital processing and filtering. Unlike standard technique, this method uses iterative creation of spatially homogeneous illumination by display, compensation of photosensor dark spatial noise portrait and improved procedure of elimination of dark temporal noise. Portraits of light and dark spatial noise of photosensors of a scientific digital camera were found. Characteristics of the measured portraits were compared with values of photo response and dark signal non-uniformities of camera's photosensor.

  11. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, F.A.; Gray, J.W.

    1983-10-18

    A method for the simultaneous flow cylometric measurement of total cellular DNA content and of the uptake of DNA precursors as a measure of DNA synthesis during various phases of the cell cycle in normal and malignant cells in vitro and in vivo is described. The method comprises reacting cells with labelled halodeoxyuridine (HdU), partially denaturing cellular DNA, adding to the reaction medium monoclonal antibodies (mabs) reactive with HdU, reacting the bound mabs with a second labelled antibody, incubating the mixture with a DNA stain, and measuring simultaneously the intensity of the DNA stain as a measure of the total cellular DNA and the HdU incorporated as a measure of DNA synthesis. (ACR)

  12. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1988-01-01

    A method for the simultaneous flow cytometric measurement of the total DNA content and the level of DNA synthesis in normal and malignant cells is disclosed. The sensitivity of the method allows a study of cell cycle traverse rates for large scale cell populations as well as single cell measurements. A DNA stain such as propidium iodide or Hoechst 33258 is used as the probe for the measurement of total DNA content and a monoclonal antibody reactive with a DNA precursor such as halodeoxy-uridine (HdU), more specifically bromodeoxyuridine (BrdU) is used as a probe for the measurement of HdU or BrdU uptake by the cells as a measure of DNA synthesis.

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

    SciTech Connect

    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. 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.

  14. 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.

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

    DOE PAGES

    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

  16. 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%.

  17. Accurate surface tension measurement of glass melts by the pendant drop method.

    PubMed

    Chang, Yao-Yuan; Wu, Ming-Ya; Hung, Yi-Lin; Lin, Shi-Yow

    2011-05-01

    A pendant drop tensiometer, coupled with image digitization technology and a best-fitting algorithm, was built to accurately measure the surface tension of glass melts at high temperatures. More than one thousand edge-coordinate points were obtained for a pendant glass drop. These edge points were fitted with the theoretical drop profiles derived from the Young-Laplace equation to determine the surface tension of glass melt. The uncertainty of the surface tension measurements was investigated. The measurement uncertainty (σ) could be related to a newly defined factor of drop profile completeness (Fc): the larger the Fc is, the smaller σ is. Experimental data showed that the uncertainty of the surface tension measurement when using this pendant drop tensiometer could be ±3 mN∕m for glass melts.

  18. A fast and accurate image-based measuring system for isotropic reflection materials

    NASA Astrophysics Data System (ADS)

    Kim, Duck Bong; Kim, Kang Yeon; Park, Kang Su; Seo, Myoung Kook; Lee, Kwan H.

    2008-08-01

    We present a novel image-based BRDF (Bidirectional Reflectance Distribution Function) measurement system for materials that have isotropic reflectance properties. Our proposed system is fast due to simple set up and automated operations. It also provides a wide angular coverage and noise reduction capability so that it achieves accuracy that is needed for computer graphics applications. We test the uniformity and constancy of the light source and the reciprocity of the measurement system. We perform a photometric calibration of HDR (High Dynamic Range) camera to recover an accurate radiance map from each HDR image. We verify our proposed system by comparing it with a previous imagebased BRDF measurement system. We demonstrate the efficiency and accuracy of our proposed system by generating photorealistic images of the measured BRDF data that include glossy blue, green plastics, gold coated metal and gold metallic paints.

  19. 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.

  20. Total cellular Ca2+ measurements in yeast using flame photometry.

    PubMed

    Tisi, Renata; Martegani, Enzo; Brandão, Rogelio L

    2015-02-02

    A photoelectric flame photometer is a device used in inorganic chemical analysis for determining the concentrations of certain metals in solution. It does this by measuring the intensity of the light emitted by the metal when the solution is sprayed under controlled conditions into a nonluminous flame. This protocol describes how to measure total cellular calcium (maximal emission at 622 nm, orange flame) in yeast using this technique.

  1. Error in total ozone measurements arising from aerosol attenuation

    NASA Technical Reports Server (NTRS)

    Thomas, R. W. L.; Basher, R. E.

    1979-01-01

    A generalized least squares method for deducing both total ozone and aerosol extinction spectrum parameters from Dobson spectrophotometer measurements was developed. An error analysis applied to this system indicates that there is little advantage to additional measurements once a sufficient number of line pairs have been employed to solve for the selected detail in the attenuation model. It is shown that when there is a predominance of small particles (less than about 0.35 microns in diameter) the total ozone from the standard AD system is too high by about one percent. When larger particles are present the derived total ozone may be an overestimate or an underestimate but serious errors occur only for narrow polydispersions.

  2. Comparative Analysis of the Measurement of Total Instructional Alignment

    ERIC Educational Resources Information Center

    Kick, Laura C.

    2013-01-01

    In 2007, Lisa Carter created the Total Instructional Alignment system--a process that aligns standards, curriculum, assessment, and instruction. Employed in several hundred school systems, the TIA process is a successful professional development program. The researcher developed an instrument to measure the success of the TIA process with the…

  3. Combining MFD and PIE for accurate single-pair Förster resonance energy transfer measurements.

    PubMed

    Kudryavtsev, Volodymyr; Sikor, Martin; Kalinin, Stanislav; Mokranjac, Dejana; Seidel, Claus A M; Lamb, Don C

    2012-03-01

    Single-pair Förster resonance energy transfer (spFRET) experiments using single-molecule burst analysis on a confocal microscope are an ideal tool to measure inter- and intramolecular distances and dynamics on the nanoscale. Different techniques have been developed to maximize the amount of information available in spFRET burst analysis experiments. Multiparameter fluorescence detection (MFD) is used to monitor a variety of fluorescence parameters simultaneously and pulsed interleaved excitation (PIE) employs direct excitation of the acceptor to probe its presence and photoactivity. To calculate accurate FRET efficiencies from spFRET experiments with MFD or PIE, several calibration measurements are usually required. Herein, we demonstrate that by combining MFD with PIE information regarding all calibration factors as well as an accurate determination of spFRET histograms can be performed in a single measurement. In addition, the quality of overlap of the different detection volumes as well as the detection of acceptor photophysics can be investigated with MFD-PIE. Bursts containing acceptor photobleaching can be identified and excluded from further investigation while bursts that contain FRET dynamics are unaffected by this analysis. We have employed MFD-PIE to accurately analyze the effects of nucleotides and substrate on the interdomain separation in DnaK, the major bacterial heat shock protein 70 (Hsp70). The interdomain distance increases from 47 Å in the ATP-bound state to 84 Å in the ADP-bound state and slightly contracts to 77 Å when a substrate is bound. This is in contrast to what was observed for the mitochondrial member of the Hsp70s, Ssc1, supporting the notion of evolutionary specialization of Hsp70s for different cellular functions in different organisms and cell organelles.

  4. 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).

  5. Note: long range and accurate measurement of deep trench microstructures by a specialized scanning tunneling microscope.

    PubMed

    Ju, Bing-Feng; Chen, Yuan-Liu; Zhang, Wei; Zhu, Wule; Jin, Chao; Fang, F Z

    2012-05-01

    A compact but practical scanning tunneling microscope (STM) with high aspect ratio and high depth capability has been specially developed. Long range scanning mechanism with tilt-adjustment stage is adopted for the purpose of adjusting the probe-sample relative angle to compensate the non-parallel effects. A periodical trench microstructure with a pitch of 10 μm has been successfully imaged with a long scanning range up to 2.0 mm. More innovatively, a deep trench with depth and step height of 23.0 μm has also been successfully measured, and slope angle of the sidewall can approximately achieve 67°. The probe can continuously climb the high step and exploring the trench bottom without tip crashing. The new STM could perform long range measurement for the deep trench and high step surfaces without image distortion. It enables accurate measurement and quality control of periodical trench microstructures.

  6. Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area1

    PubMed Central

    Easlon, Hsien Ming; Bloom, Arnold J.

    2014-01-01

    • Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. • Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. • Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images. PMID:25202639

  7. Multiple-frequency continuous wave ultrasonic system for accurate distance measurement

    NASA Astrophysics Data System (ADS)

    Huang, C. F.; Young, M. S.; Li, Y. C.

    1999-02-01

    A highly accurate multiple-frequency continuous wave ultrasonic range-measuring system for use in air is described. The proposed system uses a method heretofore applied to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. In the test embodiment to confirm concept feasibility, two low cost 40 kHz ultrasonic transducers are set face to face and used to transmit and receive ultrasound. Individual frequencies are transmitted serially, each generating its own phase shift. For any given frequency, the transmitter/receiver distance modulates the phase shift between the transmitted and received signals. Comparison of the phase shifts allows a highly accurate evaluation of target distance. A single-chip microcomputer-based multiple-frequency continuous wave generator and phase detector was designed to record and compute the phase shift information and the resulting distance, which is then sent to either a LCD or a PC. The PC is necessary only for calibration of the system, which can be run independently after calibration. Experiments were conducted to test the performance of the whole system. Experimentally, ranging accuracy was found to be within ±0.05 mm, with a range of over 1.5 m. The main advantages of this ultrasonic range measurement system are high resolution, low cost, narrow bandwidth requirements, and ease of implementation.

  8. 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.

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

    PubMed Central

    Stafylas, Kosmas; McManus, John; Schizas, Constantin

    2008-01-01

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

  10. Local and Total Density Measurements in Ice Shapes

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Broughton, Howard; Sims, James J.; Bleeze, Brian; Gaines, Vatanna

    2005-01-01

    Preliminary measurements of local and total densities inside ice shapes were obtained from ice shapes grown in the NASA Glenn Research Tunnel for a range of glaze ice, rime ice, and mixed phase ice conditions on a NACA 0012 airfoil at 0 angle of attack. The ice shapes were removed from the airfoil and a slice of ice 3 mm thick was obtained using a microtome. The resulting samples were then x-rayed to obtain a micro-radiography, the film was digitized, and image processing techniques were used to extract the local and total density values.

  11. 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

    2016-04-23

    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).

  12. Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study1234

    PubMed Central

    Harnly, James

    2016-01-01

    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 size measurement of monosize calibration spheres by differential mobility analysis

    SciTech Connect

    Mulholland, George W.; Fernandez, Marco

    1998-11-24

    A differential mobility analyzer was used to measure the mean particle size of three monosize suspensions of polystyrene spheres in water. Key features of the experiment to minimize the uncertainty in the results include developing a recirculating flow to ensure equal flows into and out of the classifier, an accurate divider circuit for calibrating the electrode voltage, and use of the 100.7 nm NIST SRM for calibrating the flow of the classifier. The measured average sizes and expanded uncertainties with a coverage factor of 2 are 92.4 nm{+-}1.1 nm, 126.9 nm{+-}1.4 nm, and 217.7 nm{+-}3.4 nm. These calibration sizes were characterized by NIST to improve the calibration of scanning surface inspection systems.

  14. 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.

  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.

  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. How accurately will SWOT measurements be able to characterize river discharge?

    NASA Astrophysics Data System (ADS)

    Durand, M.; Alsdorf, D.; Bates, P.; Rodríguez, E.; Andreadis, K.; Clark, E.

    2008-12-01

    The Surface Water and Ocean Topography (SWOT) mission is a swath mapping radar altimeter that would provide new measurements of inland water surface elevation (WSE) for rivers, lakes, wetlands and reservoirs. SWOT has been recommended by the National Research Council Decadal Survey to measure ocean topography as well as WSE over land; the proposed launch date timeframe is between 2013 - 2016. SWOT WSE estimates would provide a source of information for characterizing streamflow globally. In this paper, we evaluate the accuracy of river discharge estimates obtained from SWOT measurements over the Ohio River and eight of its major tributaries within the context of a virtual mission (VM). SWOT VM measurements are obtained by simulation from the hydrodynamic model LISFLOOD, using USGS streamflow gages as boundary conditions and validation data. SWOT measurements are then input into an algorithm to obtain estimates of discharge variations. The algorithm is based on Manning's equation, in which river width and slope are obtained from SWOT, roughness is estimated a priori. Three different algorithms are used to estimate depth. SWOT discharge estimates are compared to the discharge simulated by LISFLOOD. In this way, we are able to characterize the accuracy of SWOT estimates of instantaneous discharge. More specifically, we characterize how SWOT accuracy varies as a function of the river characteristics and contributing area, such as Strahler order. More accurate depth and discharge estimates can be obtained by data assimilation, but will be more computationally expensive.

  18. 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.

  19. 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

  20. 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.

  1. Measurement of the total acoustic output power of HITU transducers

    NASA Astrophysics Data System (ADS)

    Jenderka, Klaus-V.; Beissner, Klaus

    2010-03-01

    The majority of High Intensity Therapeutic Ultrasound (HITU) applications use strongly focused ultrasound fields generating very high local intensities in the focal region. The metrology of these high-power ultrasound fields is a challenge for the established measurement procedures and devices. This paper describes the results of measurements by means of the radiation force for a total acoustic output power up to 400 W at 1.5 MHz and up to 200 W at 2.45 MHz. For this purpose, a radiation force balance set-up was adapted for the determination of large acoustic output powers. For two types of HITU transducers, the relationship between the total acoustic output power and the applied net electrical power was determined at close transducer-target distance. Further, dependence of the measured electro-acoustic radiation conductance on the transducer-target distance was investigated at reduced power levels, considering the appearance of focal anomalies. Concluding, a list of the main uncertainty contributions, and an estimate of the uncertainty for the used radiation force balance set-up is given for measurements at high power levels.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Accurate Measurement of Velocity and Acceleration of Seismic Vibrations near Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Arif, Syed Javed; Imdadullah; Asghar, Mohammad Syed Jamil

    In spite of all prerequisite geological study based precautions, the sites of nuclear power plants are also susceptible to seismic vibrations and their consequent effects. The effect of the ongoing nuclear tragedy in Japan caused by an earthquake and its consequent tsunami on March 11, 2011 is currently beyond contemplations. It has led to a rethinking on nuclear power stations by various governments around the world. Therefore, the prediction of location and time of large earthquakes has regained a great importance. The earth crust is made up of several wide, thin and rigid plates like blocks which are in constant motion with respect to each other. A series of vibrations on the earth surface are produced by the generation of elastic seismic waves due to sudden rupture within the plates during the release of accumulated strain energy. The range of frequency of seismic vibrations is from 0 to 10 Hz. However, there appears a large variation in magnitude, velocity and acceleration of these vibrations. The response of existing or conventional methods of measurement of seismic vibrations is very slow, which is of the order of tens of seconds. A systematic and high resolution measurement of velocity and acceleration of these vibrations are useful to interpret the pattern of waves and their anomalies more accurately, which are useful for the prediction of an earthquake. In the proposed work, a fast rotating magnetic field (RMF) is used to measure the velocity and acceleration of seismic vibrations in the millisecond range. The broad spectrum of pulses within one second range, measured by proposed method, gives all possible values of instantaneous velocity and instantaneous acceleration of the seismic vibrations. The spectrum of pulses in millisecond range becomes available which is useful to measure the pattern of fore shocks to predict the time and location of large earthquakes more accurately. Moreover, instead of average, the peak values of these quantities are helpful

  5. The measurement of total sediment load in alluvial streams

    USGS Publications Warehouse

    Benedict, P.C.; Matejka, D.Q.; McNown, John S.; Boyer, M.C.

    1953-01-01

    The measurement of the total sediment load transported by streams that flow in alluvial channels has been a perplexing problem to engineers and geologists for over a century. Until the last decade the development of equipment to measure bed load and suspended load was carried on almost independently, and without primary consideration of the fundamental laws governing the transportation of fluvial sediments. French investigators during the nineteenth century described methods of measurement and a mathematical approach for computing the rate of bed-load movement. The comprehensive laboratory investigations by Gilbert early in this century provided data that are still being used for studies of sediment transport. Detailed laboratory investigations of bed-load movement conducted during the last two decades by a number of investigators have resulted in the development of additional mathematical formulas for computing rates of bed-load movement. Likewise, studies of turbulent flow have provided the turbulence suspension theory for suspended sediment as it is known today.

  6. Total OH Reactivity Measurements in the Boreal Forest

    NASA Astrophysics Data System (ADS)

    Praplan, A. P.; Hellén, H.; Hakola, H.; Hatakka, J.

    2015-12-01

    INTRODUCTION Atmospheric total OH reactivity (Rtotal) can be measured (Kovacs and Brune, 2001; Sinha et al., 2008) or it can be calculated according to Rtotal = ∑i kOH+X_i [Xi] where kOH+X_i corresponds to the reaction rate coefficient for the reaction of OH with a given compound Xi and [Xi] its concentration. Studies suggest that in some environments a large fraction of missing reactivity, comparing calculated Rtotal with ambient total OH reactivity measurements (Di Carlo et al., 2004; Hofzumahaus et al., 2009). In this study Rtotal has been measured using the Comparative Reactivity Method (Sinha et al., 2008). Levels of the reference compound (pyrrole, C4H5N) are monitored by gas chromatography every 2 minutes and Rtotal is derived from the difference of reactivity between zero and ambient air. RESULTS Around 36 hours of preliminary total OH reactivity data (30 May until 2 June 2015) are presented in Fig. 1. Its range matches previous studies for this site (Nölscher et al., 2012; Sinha et al., 2010) and is similar to values in another pine forest (Nakashima et al., 2014). The setup used during the period presented here has been updated and more recent data will be presented, as well as a comparison with calculated OH reactivity from measured individual species. ACKNOWLEDGEMENTS This work was supported by Academy of Finland (Academy Research Fellowship No. 275608). The authors acknowledge Juuso Raine for technical support. REFERENCES Di Carlo et al. (2004). Science 304, 722-725.Hofzumahaus et al. (2009). Science 324, 1702-1704.Kovacs and Brune (2001). J. Atmos. Chem. 39, 105-122.Nakashima et al. (2014). Atmos. Env. 85, 1-8.Nölscher et al. (2012). Atmos. Chem. Phys. 12, 8257-8270.Sinha et al. (2008). Atmos. Chem. Phys. 8, 2213-2227.Sinha et al. (2010). Environ. Sci. Technol. 44, 6614-6620.

  7. Robot-assisted total knee arthroplasty accurately restores the joint line and mechanical axis. A prospective randomised study.

    PubMed

    Liow, Ming Han Lincoln; Xia, Zhan; Wong, Merng Koon; Tay, Keng Jin; Yeo, Seng Jin; Chin, Pak Lin

    2014-12-01

    Robot-assisted Total Knee Arthroplasty (TKA) improves the accuracy and precision of component implantation and mechanical axis (MA) alignment. Joint-line restoration in robot-assisted TKA is not widely described and joint-line deviation of>5mm results in mid-flexion instability and poor outcomes. We prospectively randomised 60 patients into two groups: 31 patients (robot-assisted), 29 patients (conventional). No MA outliers (>±3° from neutral) or notching was noted in the robot-assisted group as compared with 19.4% (P=0.049) and 10.3% (P=0.238) respectively in the conventional group. The robot-assisted group had 3.23% joint-line outliers (>5mm) as compared to 20.6% in the conventional group (P=0.049). Robot-assisted TKA produces similar short-term clinical outcomes when compared to conventional methods with reduction of MA alignment and joint-line deviation outliers.

  8. 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.

  9. Root resistance to cavitation is accurately measured using a centrifuge technique.

    PubMed

    Pratt, R B; MacKinnon, E D; Venturas, M D; Crous, C J; Jacobsen, A L

    2015-02-01

    Plants transport water under negative pressure and this makes their xylem vulnerable to cavitation. Among plant organs, root xylem is often highly vulnerable to cavitation due to water stress. The use of centrifuge methods to study organs, such as roots, that have long vessels are hypothesized to produce erroneous estimates of cavitation resistance due to the presence of open vessels through measured samples. The assumption that roots have long vessels may be premature since data for root vessel length are sparse; moreover, recent studies have not supported the existence of a long-vessel artifact for stems when a standard centrifuge technique was used. We examined resistance to cavitation estimated using a standard centrifuge technique and compared these values with native embolism measurements for roots of seven woody species grown in a common garden. For one species we also measured vulnerability using single-vessel air injection. We found excellent agreement between root native embolism and the levels of embolism measured using a centrifuge technique, and with air-seeding estimates from single-vessel injection. Estimates of cavitation resistance measured from centrifuge curves were biologically meaningful and were correlated with field minimum water potentials, vessel diameter (VD), maximum xylem-specific conductivity (Ksmax) and vessel length. Roots did not have unusually long vessels compared with stems; moreover, root vessel length was not correlated to VD or to the vessel length of stems. These results suggest that root cavitation resistance can be accurately and efficiently measured using a standard centrifuge method and that roots are highly vulnerable to cavitation. The role of root cavitation resistance in determining drought tolerance of woody species deserves further study, particularly in the context of climate change.

  10. An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis.

    PubMed

    Xu, Z N

    2014-12-01

    In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop

  11. An algorithm for selecting the most accurate protocol for contact angle measurement by drop shape analysis

    NASA Astrophysics Data System (ADS)

    Xu, Z. N.

    2014-12-01

    In this study, an error analysis is performed to study real water drop images and the corresponding numerically generated water drop profiles for three widely used static contact angle algorithms: the circle- and ellipse-fitting algorithms and the axisymmetric drop shape analysis-profile (ADSA-P) algorithm. The results demonstrate the accuracy of the numerically generated drop profiles based on the Laplace equation. A significant number of water drop profiles with different volumes, contact angles, and noise levels are generated, and the influences of the three factors on the accuracies of the three algorithms are systematically investigated. The results reveal that the above-mentioned three algorithms are complementary. In fact, the circle- and ellipse-fitting algorithms show low errors and are highly resistant to noise for water drops with small/medium volumes and contact angles, while for water drop with large volumes and contact angles just the ADSA-P algorithm can meet accuracy requirement. However, this algorithm introduces significant errors in the case of small volumes and contact angles because of its high sensitivity to noise. The critical water drop volumes of the circle- and ellipse-fitting algorithms corresponding to a certain contact angle error are obtained through a significant amount of computation. To improve the precision of the static contact angle measurement, a more accurate algorithm based on a combination of the three algorithms is proposed. Following a systematic investigation, the algorithm selection rule is described in detail, while maintaining the advantages of the three algorithms and overcoming their deficiencies. In general, static contact angles over the entire hydrophobicity range can be accurately evaluated using the proposed algorithm. The ease of erroneous judgment in static contact angle measurements is avoided. The proposed algorithm is validated by a static contact angle evaluation of real and numerically generated water drop

  12. 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.

  13. Accurate Measurement of Canal Length during Root Canal Treatment: An In Vivo Study

    PubMed Central

    Sadaf, Durre; Ahmad, Muhammad Zubair

    2015-01-01

    Objectives: To assess the consistency and accuracy of Electronic Apex Locator (EAL) (Root ZXII) in individual canals and its association with other clinical variables. Study Design: Cross-Sectional study. Place of study: Dental section of the Aga Khan University Hospital, Karachi, Pakistan. Materials and Methods: Working length was measured by EAL in 180 patients requiring endodontic therapy in molar and premolar teeth. The effects of clinical variables e.g. gender and pulpal status on the consistency and accuracy of EAL were recorded. Performance of apex locator was considered “Consistent” when the scale bar was stable and moved only in correspondence to the movement of file in the root canal. Accuracy was determined by inserting the file at the working length determined by the EAL and periapical view of radiograph was taken using paralleling technique. Estimated working length was considered accurate when the file tip was located 0-2mm short of the radiographic apex. If the file was overextended from the radiographic apex, it showed dysfunction of the EAL. Results: Consistency of EAL was found 97.6% in distobuccal canals, 91.1% in palatal canals, 73.7% in mesiolingual canals, 83.3% in mesiobuccal and 80.2% in distal canals. Accuracy of EAL was 91.4% in mesiolingual canal, 92% in mesiobuccal, and 90.2% in Palatal and 93.2% in distal canal. Conclusion: Consistency of electronic apex locator vary in different canals, however consistent measurements are highly accurate. No significant association was found between other clinical variables with the consistency and accuracy of EAL.

  14. Small total dose measurement system for SDS-1

    NASA Astrophysics Data System (ADS)

    Kimoto, Yugo; Satoh, Yohei; Tachihara, Hiroshi

    2009-11-01

    The Japanese Aerospace Exploration Agency (JAXA) uses monitors on board satellites to measure and record in-flight data on ionization effects in space. A compact, total dose measurement system for the small satellite (SDS-1) was developed based on the previous system for measuring total ionizing dose effects. Especially, the sensor for SDS-1 is quite smaller than the sensor for SOHLA-1, which is presented in the last year. The sensor is 8 mm wide×3 mm high×19 mm long and weighs approximately 4 g with 500 mm its wire harness. Eight pin LCC RADFET and temperature sensor are arranged on it. Seven sensors are arranged on some components inside the SDS-1. One of the sensors is arranged on a printed board in advanced microprocessing in-ORBIT experiment equipment (AMI). The AMI demonstrate 320 MIPS microprocessor and DC-DC converter for space. The absorbed dose at the points where the sensors are arranged was evaluated before flight and will be compared with resulting flight data.

  15. An Accurate Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section

    NASA Astrophysics Data System (ADS)

    Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng

    2016-09-01

    The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the wave spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the variation of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more accurately reveals the airplane-borne conformal antenna's RCS scatter properties.

  16. 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.

  17. Stratus optical coherence tomogram III: a novel, reliable and accurate way to measure corneal thickness.

    PubMed

    Madgula, Indira M; Kotta, Satish

    2007-01-01

    The commercially available optical coherence tomogram (Stratus OCT III) designed for posterior segment imaging can be used for central corneal thickness (CCT) measurement. The aim of the study was to determine the accuracy and reliability of CCT measurements using Stratus OCT III versus ultrasound pachymetry. CCT using Stratus OCT III (CCT oct) was taken and averaged. The focusing system had to be defocused near the maximum to relay the image of the OCT beam onto the cornea. CCT was then determined using the ultrasound pachymeter (CCT usg). Thirty white volunteers (12 male, 18 female) participated in this study. The mean CCToct was 522.33+/-34.44 microns. The mean CCTusg was 547.37+/-33.08 microns. The mean differences between CCTusg and CCToct was 25.04+/-11.67. CCT usg was found to be highly correlated with CCToct (P < 0.001) The relation can be represented by the equation. CCToct = 0.98 (CCTusg) - 13.9. The Stratus OCT III gave reliable readings of CCT and is a novel, reliable and accurate way to measure CCT.

  18. 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.

  19. Indirect viscosimetric method is less accurate than ektacytometry for the measurement of red blood cell deformability.

    PubMed

    Vent-Schmidt, Jens; Waltz, Xavier; Pichon, Aurélien; Hardy-Dessources, Marie-Dominique; Romana, Marc; Connes, Philippe

    2015-01-01

    The aim of this study was to test the accuracy of viscosimetric method to estimate the red blood cell (RBC) deformability properties. Thirty-three subjects were enrolled in this study: 6 healthy subjects (AA), 11 patients with sickle cell-hemoglobin C disease (SC) and 16 patients with sickle cell anemia (SS). Two methods were used to assess RBC deformability: 1) indirect viscosimetric method and 2) ektacytometry. The indirect viscosimetric method was based on the Dintenfass equation where blood viscosity, plasma viscosity and hematocrit are measured and used to calculate an index of RBC rigidity (Tk index). The RBC deformability/rigidity of the three groups was compared using the two methods. Tk index was not different between SS and SC patients and the two groups had higher values than AA group. When ektacytometry was used, RBC deformability was lower in SS and SC groups compared to the AA group and SS and SC patients were different. Although the two measures of RBC deformability were correlated, the association was not very high. Bland and Altman analysis demonstrated a 3.25 bias suggesting a slight difference between the two methods. In addition, the limit of agreement represented 28% (>15%) of the mean values of RBC deformability, showing no interchangeability between the two methods. In conclusion, measuring RBC deformability by indirect viscosimetry is less accurate than by ektacytometry, which is considered the gold standard.

  20. An accurate optical technique for measuring the nuclear polarisation of 3He gas

    NASA Astrophysics Data System (ADS)

    Talbot, C.; Batz, M.; Nacher, P.-J.; Tastevin, G.

    2011-06-01

    In the metastability exchange optical pumping cells of our on-site production unit and of our other experimental set-ups, we use a light absorption technique to measure the 3He nuclear polarisation. It involves weak probe beams at 1083 nm, that are either perpendicular or parallel to the magnetic field and cell axis, with suitable light polarisations. When metastability exchange collisions control the populations of the sublevels in the 23S state, absolute values of the 3He ground state nuclear polarisation are directly inferred from the ratio of the absorption rates measured for these probe beams. Our report focuses on the transverse detection scheme for which this ratio, measured at low magnetic field for σ and π light polarisations, hardly depends on gas pressure or the presence of an intense pump beam. This technique has been systematically tested both in pure 3He and isotopic mixtures and it is routinely used for accurate control of the optical pumping efficiency as well as for calibration of the NMR system.

  1. 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

  2. Comparative responsiveness of outcome measures for total knee arthroplasty

    PubMed Central

    Giesinger, K.; Hamilton, D.F.; Jost, B.; Holzner, B.; Giesinger, J.M.

    2014-01-01

    Summary Objective The aim of this study was to compare the responsiveness of various patient-reported outcome measures (PROMs) and clinician-reported outcomes following total knee arthroplasty (TKA) over a 2-year period. Methods Data were collected in a prospective cohort study of primary TKA. Patients who had completed Forgotten Joint Score-12 (FJS-12), Western Ontario and McMaster Universities (WOMAC) osteoarthritis (OA) index, EQ-5D, Knee Society Score and range of movement (ROM) assessment were included. Five time points were assessed: pre-operative, 2 months, 6 months, 1 year and 2 years post-operative. Results Data from 98 TKAs were available for analysis. Largest effect sizes (ES) for change from pre-operative to 2-month follow-up were observed for the Knee Society Score (KSS) Knee score (1.70) and WOMAC Total (−1.50). For the period from 6 months to 1 year the largest ES for change were shown by the FJS-12 (0.99) and the KSS Function Score (0.88). The EQ-5D showed the strongest ceiling effect at 1-year follow-up with 84.4% of patients scoring the maximum score. ES for the time from 1- to 2-year follow-up were largest for the FJS-12 (0.50). All other outcome measures showed ES equal or below 0.30. Conclusion Outcome measures differ considerably in responsiveness, especially beyond one year post-operatively. Joint-specific outcome measures are more responsive than clinician-reported or generic health outcome tools. The FJS-12 was the most responsive of the tools assessed; suggesting that joint awareness may be a more discerning measure of patient outcome than traditional PROMs. PMID:24262431

  3. The use of flow cytometry to accurately ascertain total and viable counts of Lactobacillus rhamnosus in chocolate.

    PubMed

    Raymond, Yves; Champagne, Claude P

    2015-04-01

    The goals of this study were to evaluate the precision and accuracy of flow cytometry (FC) methodologies in the evaluation of populations of probiotic bacteria (Lactobacillus rhamnosus R0011) in two commercial dried forms, and ascertain the challenges in enumerating them in a chocolate matrix. FC analyses of total (FC(T)) and viable (FC(V)) counts in liquid or dried cultures were almost two times more precise (reproducible) than traditional direct microscopic counts (DCM) or colony forming units (CFU). With FC, it was possible to ascertain low levels of dead cells (FC(D)) in fresh cultures, which is not possible with traditional CFU and DMC methodologies. There was no interference of chocolate solids on FC counts of probiotics when inoculation was above 10(7) bacteria per g. Addition of probiotics in chocolate at 40 °C resulted in a 37% loss in viable cells. Blending of the probiotic powder into chocolate was not uniform which raised a concern that the precision of viable counts could suffer. FCT data can serve to identify the correct inoculation level of a sample, and viable counts (FCV or CFU) can subsequently be better interpreted.

  4. Total body water measurements using resonant cavity perturbation techniques

    NASA Astrophysics Data System (ADS)

    Stone, Darren A.; Robinson, Martin P.

    2004-05-01

    A recent paper proposed a novel technique for determining the total body water (TBW) of patients suffering with abnormal hydration levels, using a resonant cavity perturbation method. Current techniques to measure TBW are limited by resolution and technical constraints. However, this new method involves measuring the dielectric properties of the body, by placing a subject in a large cavity resonator and measuring the subsequent change in its resonant frequency, fres and its Q-factor. Utilizing the relationship that water content correlates to these dielectric properties, it has been shown that the measured response of these parameters enables determination of TBW. Results are presented for a preliminary study using data estimated from anthropometric measurements, where volunteers were asked to lie and stand in an electromagnetic screened room, before and after drinking between 1 and 2 l of water, and in some cases, after voiding the bladder. Notable changes in the parameters were observed; fres showed a negative shift and Q was reduced. Preliminary calibration curves using estimated values of water content have been developed from these results, showing that for each subject the measured resonant frequency is a linear function of TBW. Because the gradients of these calibration curves correlate to the mass-to-height-ratio of the volunteers, it has proved that a system in which TBW can be unequivocally obtained is possible. Measured values of TBW have been determined using this new pilot-technique, and the values obtained correlate well with theoretical values of body water (r = 0.87) and resolution is very good (750 ml). The results obtained are measurable, repeatable and statistically significant. This leads to confidence in the integrity of the proposed technique.

  5. Measurement of total hemispherical emissivity of contaminated mirror surfaces

    NASA Technical Reports Server (NTRS)

    Facey, T. A.; Nonnenmacher, A. L.

    1989-01-01

    The effects of dust contamination on the total hemispherical emissivity (THE) of a 1.5-inch-diameter Al/MgF2-coated telescope mirror are investigated experimentally. The THE is determined by means of cooling-rate measurements in the temperature range 10-14.5 C in a vacuum of 100 ntorr or better. Photographs and drawings of the experimental setup are provided, and results for 11 dust levels are presented in tables and graphs. It is shown that dust has a significant effect on THE, but the experimental losses are only about half those predicted for perfectly black dust in perfect thermal contact with the mirror surface.

  6. 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

  7. Measurement of Total Scatter Factor for Stereotactic Cones with Plastic Scintillation Detector

    PubMed Central

    Chaudhari, Suresh H; Dobhal, Rishabh; Kinhikar, Rajesh A.; Kadam, Sudarshan S.; Deshpande, Deepak D.

    2017-01-01

    Advanced radiotherapy modalities such as stereotactic radiosurgery (SRS) and image-guided radiotherapy may employ very small beam apertures for accurate localized high dose to target. Accurate measurement of small radiation fields is a well-known challenge for many dosimeters. The purpose of this study was to measure total scatter factors for stereotactic cones with plastic scintillation detector and its comparison against diode detector and theoretical estimates. Measurements were performed on Novalis Tx™ linear accelerator for 6MV SRS beam with stereotactic cones of diameter 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm. The advantage of plastic scintillator detector is in its energy dependence. The total scatter factor was measured in water at the depth of dose maximum. Total scatter factor with plastic scintillation detector was determined by normalizing the readings to field size of 10 cm × 10 cm. To overcome energy dependence of diode detector for the determination of scatter factor with diode detector, daisy chaining method was used. The plastic scintillator detector was calibrated against the ionization chamber, and the reproducibility in the measured doses was found to be within ± 1%. Total scatter factor measured with plastic scintillation detector was 0.728 ± 0.3, 0.783 ± 0.05, 0.866 ± 0.55, 0.885 ± 0.5, and 0.910 ± 0.06 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. Total scatter factor measured with diode detector was 0.733 ± 0.03, 0.782 ± 0.02, 0.834 ± 0.07, 0.854 ± 0.02, and 0.872 ± 0.02 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. The variation in the measurement of total scatter factor with published Monte Carlo data was found to be −1.3%, 1.9%, −0.4%, and 0.4% for cone sizes of 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. We conclude that total scatter factor measurements for stereotactic cones can be adequately carried out with a plastic scintillation detector. Our results show

  8. 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.

  9. An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers

    PubMed Central

    Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

    2016-01-01

    Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time. PMID:27941705

  10. Accurate measurement of volume and shape of resting and activated blood platelets from light scattering

    NASA Astrophysics Data System (ADS)

    Moskalensky, Alexander E.; Yurkin, Maxim A.; Konokhova, Anastasiya I.; Strokotov, Dmitry I.; Nekrasov, Vyacheslav M.; Chernyshev, Andrei V.; Tsvetovskaya, Galina A.; Chikova, Elena D.; Maltsev, Valeri P.

    2013-01-01

    We introduce a novel approach for determination of volume and shape of individual blood platelets modeled as an oblate spheroid from angle-resolved light scattering with flow-cytometric technique. The light-scattering profiles (LSPs) of individual platelets were measured with the scanning flow cytometer and the platelet characteristics were determined from the solution of the inverse light-scattering problem using the precomputed database of theoretical LSPs. We revealed a phenomenon of parameter compensation, which is partly explained in the framework of anomalous diffraction approximation. To overcome this problem, additional a priori information on the platelet refractive index was used. It allowed us to determine the size of each platelet with subdiffraction precision and independent of the particular value of the platelet aspect ratio. The shape (spheroidal aspect ratio) distributions of platelets showed substantial differences between native and activated by 10 μM adenosine diphosphate samples. We expect that the new approach may find use in hematological analyzers for accurate measurement of platelet volume distribution and for determination of the platelet activation efficiency.

  11. An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers.

    PubMed

    Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

    2016-12-09

    Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time.

  12. Wear characteristics of UHMW polyethylene: a method for accurately measuring extremely low wear rates.

    PubMed

    McKellop, H; Clarke, I C; Markolf, K L; Amstutz, H C

    1978-11-01

    The wear of UHMW polyethylene bearing against 316 stainless steel or cobalt chrome alloy was measured using a 12-channel wear tester especially developed for the evaluation of candidate materials for prosthetic joints. The coefficient of friction and wear rate was determined as a function of lubricant, contact stress, and metallic surface roughness in tests lasting two to three million cycles, the equivalent of several years' use of a prosthesis. Wear was determined from the weight loss of the polyethylene specimens corrected for the effect of fluid absorption. The friction and wear processes in blood serum differed markedly from those in saline solution or distilled water. Only serum lubrication produced wear surfaces resembling those observed on removed prostheses. The experimental method provided a very accurate reproducible measurement of polyethylene wear. The long-term wear rates were proportional to load and sliding distance and were much lower than expected from previously published data. Although the polyethylene wear rate increased with increasing surface roughness, wear was not severe except with very coarse metal surfaces. The data obtained in these studies forms a basis for the subsequent comparative evaluation of potentially superior materials for prosthetic joints.

  13. 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.

  14. 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.

  15. Accurate measurement of interferometer group delay using field-compensated scanning white light interferometer.

    PubMed

    Wan, Xiaoke; Wang, Ji; Ge, Jian

    2010-10-10

    Interferometers are key elements in radial velocity (RV) experiments in astronomy observations, and accurate calibration of the group delay of an interferometer is required for high precision measurements. A novel field-compensated white light scanning Michelson interferometer is introduced as an interferometer calibration tool. The optical path difference (OPD) scanning was achieved by translating a compensation prism, such that even if the light source were in low spatial coherence, the interference stays spatially phase coherent over a large interferometer scanning range. In the wavelength region of 500-560 nm, a multimode fiber-coupled LED was used as the light source, and high optical efficiency was essential in elevating the signal-to-noise ratio of the interferogram signal. The achromatic OPD scanning required a one-time calibration, and two methods using dual-laser wavelength references and an iodine absorption spectrum reference were employed and cross-verified. In an experiment measuring the group delay of a fixed Michelson interferometer, Fourier analysis was employed to process the interferogram data. The group delay was determined at an accuracy of 1×10(-5), and the phase angle precision was typically 2.5×10(-6) over the wide wavelength region.

  16. Comparison of three different methods of total carbon dioxide measurement.

    PubMed

    Kilborn, Susan H.; Bonnett, Brenda N.; Pook, Harold A.

    1995-01-01

    The objective of this study was to compare total carbon dioxide (TCO(2)) levels measured by three different methods. Two hundred jugular venous blood samples from dogs admitted to the Veterinary Teaching Hospital, Ontario Veterinary College with various clinical disorders were analyzed by the Radiometer blood gas analyzer (BGA) and the Coulter DACOS analyzer. In 70 of these samples, TCO(2) was also measured by the Kodak Ektachem DTE chemistry analyzer. Comparison of the agreement between methods revealed intraclass correlation coefficients (ICC) of 0.63, 0.79, and 0.82 for the DACOS-Ektachem, DACOS-BGA and Ektachem-BGA comparisons, respectively. Evaluation of the effect of storage time on TCO(2) content of stored serum samples measured on the DACOS analyzer revealed a decrease of almost 2 mmol/L and a decrease in the intraclass correlation coefficient values between the DACOS analyzer and other methods after 7 hours storage time. The results of this observational study revealed lower agreement between the three methods in this study than previously reported between other methods of TCO(2) measurement. Possible reasons for the lower than expected agreement in this study included changes in DACOS values because of storage and differences in methodologies between the methods.

  17. Measuring Total Surface Moisture with the COSMOS Rover

    NASA Astrophysics Data System (ADS)

    Chrisman, B. B.; Zreda, M.; Franz, T. E.; Rosolem, R.

    2012-12-01

    The COSMOS rover is the mobile application of the cosmic-ray soil moisture probe. By quantifying the relative amount of the hydrogen molecules within the instrument's support volume (~335 m radius in air, 10-70 cm depth in soil) the instrument makes an area-average surface moisture measurement. We call this measurement "total surface moisture". Quantifying hydrogen in all major stocks (soils, infrastructure, vegetation, and water vapor) allows for an isolation of the volumetric fraction of the exchangeable surface moisture. By isolating the hydrogen molecule we can measure the exchangeable surface moisture over all land cover types including those with built-up infrastructure and dense vegetation; two environments which have been challenging to existing technologies. . The cosmic-ray rover has the capability to improve hydrologic, climate, and weather models by parameterizing the exchangeable surface moisture status over complex landscapes. It can also fill a gap in the verification and development processes of surface moisture satellite missions, such as SMOS and SMAP. In our current research program, 2D transects are produced twice a week and 3D maps are produced once a week during the 2012 monsoon season (July-September) within the Tucson Basin. The 40 km x 40 km area includes four land cover classes; developed, scrub (natural Sonoran Desert), crops, and evergreen forest. The different land cover types show significant differences in their surface moisture behavior with irrigation acting as the largest controlling factor in the developed and crop areas. In addition we investigated the use of the cosmic-ray rover data to verify/compare with satellite derived soil moisture. A Maximum Entropy model is being used to create soil moisture profiles from shallow surface measurements (SMOS data). With the cosmic-ray penetration depth and weighting function known, the satellite measurement can be interpolated, weighted and compared with the cosmic-ray measurement when the

  18. Iodide-assisted total lead measurement and determination of different lead fractions in drinking water samples.

    PubMed

    Zhang, Yuanyuan; Ng, Ding-Quan; Lin, Yi-Pin

    2012-07-01

    Lead and its compounds are toxic and can harm human health, especially the intelligence development in children. Accurate measurement of total lead present in drinking water is crucial in determining the extent of lead contamination and human exposure due to drinking water consumption. The USEPA method for total lead measurement (no. 200.8) is often used to analyze lead levels in drinking water. However, in the presence of high concentration of the tetravalent lead corrosion product PbO(2), the USEPA method was not able to fully recover particulate lead due to incomplete dissolution of PbO(2) particles during strong acid digestion. In this study, a new procedure that integrates membrane separation, iodometric PbO(2) measurement, strong acid digestion and ICP-MS measurement was proposed and evaluated for accurate total lead measurement and quantification of different lead fractions including soluble Pb(2+), particulate Pb(II) carbonate and PbO(2) in drinking water samples. The proposed procedure was evaluated using drinking water reconstituted with spiked Pb(2+), spiked particulate Pb(II) carbonate and in situ formed or spiked PbO(2). Recovery tests showed that the proposed procedure and the USEPA method can achieve 93-112% and 86-103% recoveries respectively for samples containing low PbO(2) concentrations (0.018-0.076 mg Pb per L). For samples containing higher concentrations of PbO(2) (0.089-1.316 mg Pb per L), the USEPA method failed to meet the recovery requirement for total lead (85-115%) while the proposed method can achieve satisfactory recoveries (91-111%) and differentiate the soluble Pb(2+), particulate Pb(II) carbonate and PbO(2).

  19. A cost-effective transparency-based digital imaging for efficient and accurate wound area measurement.

    PubMed

    Li, Pei-Nan; Li, Hong; Wu, Mo-Li; Wang, Shou-Yu; Kong, Qing-You; Zhang, Zhen; Sun, Yuan; Liu, Jia; Lv, De-Cheng

    2012-01-01

    Wound measurement is an objective and direct way to trace the course of wound healing and to evaluate therapeutic efficacy. Nevertheless, the accuracy and efficiency of the current measurement methods need to be improved. Taking the advantages of reliability of transparency tracing and the accuracy of computer-aided digital imaging, a transparency-based digital imaging approach is established, by which data from 340 wound tracing were collected from 6 experimental groups (8 rats/group) at 8 experimental time points (Day 1, 3, 5, 7, 10, 12, 14 and 16) and orderly archived onto a transparency model sheet. This sheet was scanned and its image was saved in JPG form. Since a set of standard area units from 1 mm(2) to 1 cm(2) was integrated into the sheet, the tracing areas in JPG image were measured directly, using the "Magnetic lasso tool" in Adobe Photoshop program. The pixel values/PVs of individual outlined regions were obtained and recorded in an average speed of 27 second/region. All PV data were saved in an excel form and their corresponding areas were calculated simultaneously by the formula of Y (PV of the outlined region)/X (PV of standard area unit) × Z (area of standard unit). It took a researcher less than 3 hours to finish area calculation of 340 regions. In contrast, over 3 hours were expended by three skillful researchers to accomplish the above work with traditional transparency-based method. Moreover, unlike the results obtained traditionally, little variation was found among the data calculated by different persons and the standard area units in different sizes and shapes. Given its accurate, reproductive and efficient properties, this transparency-based digital imaging approach would be of significant values in basic wound healing research and clinical practice.

  20. 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.

  1. 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.

  2. Online dissolved methane and total dissolved sulfide measurement in sewers.

    PubMed

    Liu, Yiwen; Sharma, Keshab R; Fluggen, Markus; O'Halloran, Kelly; Murthy, Sudhir; Yuan, Zhiguo

    2015-01-01

    Recent studies using short-term manual sampling of sewage followed by off-line laboratory gas chromatography (GC) measurement have shown that a substantial amount of dissolved methane is produced in sewer systems. However, only limited data has been acquired to date due to the low frequency and short span of this method, which cannot capture the dynamic variations of in-sewer dissolved methane concentrations. In this study, a newly developed online measuring device was used to monitor dissolved methane concentrations at the end of a rising main sewer network, over two periods of three weeks each, in summer and early winter, respectively. This device uses an online gas-phase methane sensor to measure methane under equilibrium conditions after being stripped from the sewage. The data are then converted to liquid-phase methane concentrations according to Henry's Law. The detection limit and range are suitable for sewer application and can be adjusted by varying the ratio of liquid-to-gas phase volume settings. The measurement presented good linearity (R² > 0.95) during field application, when compared to off-line measurements. The overall data set showed a wide variation in dissolved methane concentration of 5-15 mg/L in summer and 3.5-12 mg/L in winter, resulting in a significant average daily production of 24.6 and 19.0 kg-CH₄/d, respectively, from the network with a daily average sewage flow of 2840 m³/day. The dissolved methane concentration demonstrated a clear diurnal pattern coinciding with flow and sulfide fluctuation, implying a relationship with the wastewater hydraulic retention time (HRT). The total dissolved sulfide (TDS) concentration in sewers can be determined simultaneously with the same principle.

  3. Total Water Content Measurements with an Isokinetic Sampling Probe

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Miller, Dean R.; Bidwell, Colin S.

    2010-01-01

    The NASA Glenn Research Center has developed a Total Water Content (TWC) Isokinetic Sampling Probe. Since it is not sensitive to cloud water particle phase nor size, it is particularly attractive to support super-cooled large droplet and high ice water content aircraft icing studies. The instrument is comprised of the Sampling Probe, Sample Flow Control, and Water Vapor Measurement subsystems. Analysis and testing have been conducted on the subsystems to ensure their proper function and accuracy. End-to-end bench testing has also been conducted to ensure the reliability of the entire instrument system. A Stokes Number based collection efficiency correction was developed to correct for probe thickness effects. The authors further discuss the need to ensure that no condensation occurs within the instrument plumbing. Instrument measurements compared to facility calibrations from testing in the NASA Glenn Icing Research Tunnel are presented and discussed. There appears to be liquid water content and droplet size effects in the differences between the two measurement techniques.

  4. Measurement of total body calcium in osteoporotic patients treated with salmon calcitonin

    SciTech Connect

    Zanzi, I.; Thompson, K.; Cohn, S.H.

    1981-01-01

    In the past, the evaluation of therapies for osteoporosis has been limited by the lack of a suitable quantitative end point. The introduction of the technique of in vivo total body neutron activation analysis (TBNAA) has made possible the precise and accurate measurement of total body calcium (TBCa). Since almost 99 percent of TBCa is in the skeleton, TBNAA gives a direct measurement of skeletal mass. Thus, changes in skeletal mass serve as an objective criterion in the evaluation of the efficacy of the therapy in osteoporosis. Studies performed at Brookhaven National Laboratory and elsewhere have reported the use of calcitonin (CT) in the treatment of primary osteoporosis and related conditions in a limited number of patients. The physiological effects of CT as an inhibitor of bone resorption has been the rationale of its use. The results of a randomized, controlled, 2 year therapeutical trial of CT in a group of postmenopausal osteoporotic women are presented in this report.

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

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-02-29

    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

  6. Measurement of total ion current from vacuum arc plasmasources

    SciTech Connect

    Oks, Efim M.; Savkin, Konstantin P.; Yushkov, Georgiu Yu.; Nikolaev, Alexey G.; Anders, A.; Brown, Ian G.

    2005-07-01

    The total ion current generated by a vacuum arc plasma source was measured. The discharge system investigated allowed ion collection from the arc plasma streaming through a hemispherical mesh anode with geometric transparency of 72 percent. A range of different cathode materials was investigated, and the arc current was varied over the range 50-500 A. We find that the normalized ion current (Iion/Iarc) depends on the cathode material, with values in the range from 5 percent to 19 percent and generally greater for elements of low cohesive energy. The application of a strong axial magnetic field in the cathode and arc region leads to increased normalized ion current, but only by virtue of enhanced ion charge states formed in a strong magnetic field.

  7. Anatomic dimensions of the patella measured during total knee arthroplasty.

    PubMed

    Baldwin, James L; House, C Ken

    2005-02-01

    The anatomic measurements of 92 patellae with normal underlying bony structure were studied during total knee arthroplasty before and after resection of the articular surface. The articular surface of the patella was found to have an oval shape with a width-to-height ratio (46 x 36 mm) of 1.30. The dome was 4.8 mm high and displaced medially 3.6 mm. The medial facet was slightly thicker than the lateral facet (18 vs 17 mm). The lateral facet is 25% wider than the medial facet. Coverage provided by oval patellar prostheses was significantly better than with round prostheses. The patellae in women were significantly smaller than in men. Size differences and deformity need to be taken into account when the patella is prepared for resurfacing. It is recommended that the bony resection should be no greater than one third of the maximum patellar thickness to avoid alteration of normal bony structure. Key words: patella, total knee arthroplasty, anatomy.

  8. An easy way to measure accurately the direct magnetoelectric voltage coefficient of thin film devices

    NASA Astrophysics Data System (ADS)

    Poullain, Gilles; More-Chevalier, Joris; Cibert, Christophe; Bouregba, Rachid

    2017-01-01

    TbxDy1-xFe2/Pt/Pb(Zrx, Ti1-x)O3 thin films were grown on Pt/TiO2/SiO2/Si substrate by multi-target sputtering. The magnetoelectric voltage coefficient αΗΜΕ was determined at room temperature using a lock-in amplifier. By adding, in series in the circuit, a capacitor of the same value as that of the device under test, we were able to demonstrate that the magnetoelectric device behaves as a voltage source. Furthermore, a simple way to subtract the stray voltage arising from the flow of eddy currents in the measurement set-up, is proposed. This allows the easy and accurate determination of the true magnetoelectric voltage coefficient. A large αΗΜΕ of 8.3 V/cm. Oe was thus obtained for a Terfenol-D/Pt/PZT thin film device, without DC magnetic field nor mechanical resonance.

  9. Mass spectrometry in Earth sciences: the precise and accurate measurement of time.

    PubMed

    Schaltegger, Urs; Wotzlaw, Jörn-Frederik; Ovtcharova, Maria; Chiaradia, Massimo; Spikings, Richard

    2014-01-01

    Precise determinations of the isotopic compositions of a variety of elements is a widely applied tool in Earth sciences. Isotope ratios are used to quantify rates of geological processes that occurred during the previous 4.5 billion years, and also at the present time. An outstanding application is geochronology, which utilizes the production of radiogenic daughter isotopes by the radioactive decay of parent isotopes. Geochronological tools, involving isotopic analysis of selected elements from smallest volumes of minerals by thermal ionization mass spectrometry, provide precise and accurate measurements of time throughout the geological history of our planet over nine orders of magnitude, from the accretion of the proto-planetary disk, to the timing of the last glaciation. This article summarizes the recent efforts of the Isotope Geochemistry, Geochronology and Thermochronology research group at the University of Geneva to advance the U-Pb geochronological tool to achieve unprecedented precision and accuracy, and presents two examples of its application to two significant open questions in Earth sciences: what are the triggers and timescales of volcanic supereruptions, and what were the causes of mass extinctions in the geological past, driven by global climatic and environmental deterioration?

  10. 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.

  11. Integration of an intensified charge-coupled device (ICCD) camera for accurate spectroscopic measurements.

    PubMed

    Peláez, Ramón Javier; Mar, Santiago; Aparicio, Juan Antonio; Belmonte, María Teresa

    2012-08-01

    Intensified charge-coupled devices (ICCD) are used in a great variety of spectroscopic applications, some of them requiring high sensitivity and spectral resolution. The setup, configuration, and featuring of these cameras are fundamental issues in order to acquire high quality spectra. In this work a critical assessment of these detectors is performed and the specific configuration, the optical alignment, featuring, and the dark and shot noise are described and analyzed. Spatial response of the detector usually shows a significant lack of spatial homogeneity and a map of interferences may appear in certain ranges of wavelengths, which damages the quality of the recorded spectra. In this work the spectral resolution and the spatial and spectral sensitivity are also studied. The analysis of the dark current reveals the existence of a smooth but clear spatial dependence. As a final conclusion, the spectra registered with the spectrometer equipped with our ICCD camera allow us to explore and measure accurately spectral line shapes emitted by pulsed plasmas in the visible range and particularly in the ultraviolet (UV) range.

  12. 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.

  13. An Improved Method for Accurate and Rapid Measurement of Flight Performance in Drosophila

    PubMed Central

    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

  14. Determination of lithium ion--rare gas potentials from total cross section measurements

    SciTech Connect

    Polak-Dingels, P.; Rajan, M.S.; Gislason, E.A.

    1982-10-15

    Total cross sections have been measured for Li/sup +/ ions scattered by He, Ne, Ar, Kr, and Xe in the range Etheta/sub R/ = 5--1000 eV deg. Here E is the laboratory energy of the Li/sup +/ beam, and theta/sub R/ is the resolution angle of the apparatus. The cross sections have been inverted to obtain accurate estimates of the potential V(R) over a wide range of R including the attractive well region. The results are compared with other theoretical and experimental work on these systems.

  15. High-accuracy measurements of total column water vapor from the Orbiting Carbon Observatory-2

    NASA Astrophysics Data System (ADS)

    Nelson, Robert R.; Crisp, David; Ott, Lesley E.; O'Dell, Christopher W.

    2016-12-01

    Accurate knowledge of the distribution of water vapor in Earth's atmosphere is of critical importance to both weather and climate studies. Here we report on measurements of total column water vapor (TCWV) from hyperspectral observations of near-infrared reflected sunlight over land and ocean surfaces from the Orbiting Carbon Observatory-2 (OCO-2). These measurements are an ancillary product of the retrieval algorithm used to measure atmospheric carbon dioxide concentrations, with information coming from three highly resolved spectral bands. Comparisons to high-accuracy validation data, including ground-based GPS and microwave radiometer data, demonstrate that OCO-2 TCWV measurements have maximum root-mean-square deviations of 0.9-1.3mm. Our results indicate that OCO-2 is the first space-based sensor to accurately and precisely measure the two most important greenhouse gases, water vapor and carbon dioxide, at high spatial resolution (1.3 × 2.3 km2) and that OCO-2 TCWV measurements may be useful in improving numerical weather predictions and reanalysis products.

  16. Accurate measurement of transgene copy number in crop plants using droplet digital PCR.

    PubMed

    Collier, Ray; Dasgupta, Kasturi; Xing, Yan-Ping; Hernandez, Bryan Tarape; Shao, Min; Rohozinski, Dominica; Kovak, Emma; Lin, Jeanie; de Oliveira, Maria Luiza P; Stover, Ed; McCue, Kent F; Harmon, Frank G; Blechl, Ann; Thomson, James G; Thilmony, Roger

    2017-02-23

    Genetic transformation is a powerful means for the improvement of crop plants, but requires labor and resource intensive methods. An efficient method for identifying single copy transgene insertion events from a population of independent transgenic lines is desirable. Currently transgene copy number is estimated by either Southern blot hybridization analyses or quantitative polymerase chain reaction (qPCR) experiments. Southern hybridization is a convincing and reliable method, but it also is expensive, time-consuming and often requires a large amount of genomic DNA and radioactively labeled probes. Alternatively, qPCR requires less DNA and is potentially simpler to perform, but its results can lack the accuracy and precision needed to confidently distinguish between one and two copy events in transgenic plants with large genomes. To address this need, we developed a droplet digital PCR (dPCR)-based method for transgene copy number measurement in an array of crops: rice, citrus, potato, maize, tomato, and wheat. The method utilizes specific primers to amplify target transgenes, and endogenous reference genes in a single duplexed reaction containing thousands of droplets. Endpoint amplicon production in the droplets is detected and quantified using sequence-specific fluorescently labeled probes. The results demonstrate that this approach can generate confident copy number measurements in independent transgenic lines in these crop species. This method and the compendium of probes and primers will be a useful resource for the plant research community, enabling the simple and accurate determination of transgene copy number in these six important crop species. This article is protected by copyright. All rights reserved.

  17. 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

  18. Measurement of Total Cross Sections at Pohang Neutron Facility

    SciTech Connect

    Kim, Guinyun; Meaze, A.K.M.M.H.; Ahmed, Hossain; Son, Dongchul; Lee, Young Seok; Kang, Hengsik; Cho, Moo-Hyun; Ko, In Soo; Namkung, Won; Ro, Tae-Ik.; Chung, Won-Chung; Kim, Young Ae; Yoo, Kun Joong; Chang, Jong Hwa

    2005-05-24

    The Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a time-of-flight path with an 11 m length has been operated since 2000. We report the status activities on the neutron total cross-section measurements in the neutron energy region from 0.01 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.5 cm has been used as a neutron detector. The background level has been determined by using notch-filters of Co, In, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and that from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shape. The present measurements for Ag, Hf, and Ta samples are compared with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters for Ag and Hf samples have been extracted from the transmission data by using the SAMMY code.

  19. ISS-SOLAR: Total (TSI) and spectral (SSI) irradiance measurements

    NASA Astrophysics Data System (ADS)

    Schmidtke, G.; Fröhlich, C.; Thuillier, G.

    The primary objective of the ISS-SOLAR mission on Columbus (to be launched in 2006) is the quasi-continuous measurement of the solar irradiance variability with highest possible accuracy. For this reason the total spectral range will be recorded simultaneously from 3000 to 17 nm by three sets of instruments: SOVIM is combining two types of absolute radiometers and three-channel filter radiometers. SOLSPEC is composed of three double monochromators using concave gratings, covering the wavelength range from 3000 to 180 nm. SOL-ACES has four grazing incidence planar grating spectrometers plus two three-signal ionization chambers (two signals from a two stage chamber plus a third signal from a silicon diode at the end of the chamber) with exchangeable band pass filters to determine the absolute fluxes from 220 to 17 nm repeatedly during the mission. For the TSI the relative standard uncertainty (RSU) to be achieved is of the order of 0.15% and for the SSI from 1% in the IR/Vis, 2% in the UV, 5% in the FUV up to 10% in the XUV spectral regions. The general requirements for the TSI and SSI measurements and their conceptual realization within this payload will be discussed with emphasis on instrumental realization and calibration aspects.

  20. ISS-SOLAR: Total (TSI) and Spectral (SSI) Irradiance Measurements

    NASA Astrophysics Data System (ADS)

    Schmidtke, G.; Thuillier, G.; Fröhlich, C.

    Related to the climatic aspects in atmospheric science the primary objective of the ISS-SOLAR Mission on Columbus (to be launched in 2006) is the quasi-continuous measurement of the solar irradiance variation with highest possible accuracy. For this reason the total spectral range will be recorded simultaneously for the first time from 3000-16 nm by three sets of instruments: SOVIM(3) is combining two types of absolute radiometers and three-channel filterradiometers. SOLSPEC(2) is composed of three concave grating spectrometers with two monochromators, each, covering the wavelength range from 3000-180 nm. SOL-ACES(1) has four grazing incidence planar grating spectrometers plus two three-signal ionization chambers with exchangeable band pass filters to determine the absolute fluxes from 220-16 nm repeatedly during the mission. For the TSI the absolute accuracy to be achieved is of the order of 0.1 % and for the SSI from 1 % in the VIS, 2 % in the UV, 5 % in the FUV to 10 % in the XUV spectral regions. The general requirements for the TSI and SSI measurements and their conceptual realization within the payload will be discussed with emphasis on instrumental realization and calibration aspects.

  1. Regular, Fast and Accurate Airborne In-Situ Methane Measurements Around the Tropopause

    NASA Astrophysics Data System (ADS)

    Dyroff, Christoph; Rauthe-Schöch, Armin; Schuck, Tanja J.; Zahn, Andreas

    2013-04-01

    We present a laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft. The instrument is based on a commercial fast methane analyzer (FMA, Los Gatos Res.), which was modified for fully unattended employment. A laboratory characterization was performed and the results with emphasis on the precision, cross sensitivity to H2O, and accuracy are presented. An in-flight calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. By statistical comparison of the in-situ measurements with the flask samples we derive a total uncetrainty estimate of ~ 3.85 ppbv (1?) around the tropopause, and ~ 12.4 ppbv (1?) during aircraft ascent and descent. Data from the first two years of airborne operation are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere, with occasional crossings of the tropics on flights to southern Africa. With its high spatial resolution and high accuracy this data set is unprecedented in the highly important atmospheric layer of the tropopause.

  2. Are portable bladder scanning and real-time ultrasound accurate measures of bladder volume in postnatal women?

    PubMed

    Mathew, S; Horne, A W; Murray, L S; Tydeman, G; McKinley, C A

    2007-08-01

    Real-time ultrasound and portable bladder scanners are commonly used instead of catheterisation to determine bladder volumes in postnatal women but it is not known whether these are accurate. Change in bladder volumes measured by ultrasound and portable scanners were compared with actual voided volume (VV) in 100 postnatal women. The VV was on average 41 ml (CI 29 - 54 ml) higher than that measured by ultrasound, and 33 ml (CI 17 - 48 ml) higher than that measured by portable scanners. Portable scanner volumes were 9 ml (CI -8 - 26 ml) higher than those measured by ultrasound. Neither method is an accurate tool for detecting bladder volume in postnatal women.

  3. 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

  4. MODIS Measures Total U.S. Leaf Area

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This composite image over the continental United States was produced with data acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS) during the period March 24 - April 8, 2000. The image is a map of the density of the plant canopy covering the ground. It is the first in a series of images over the continental U.S. produced by the MODIS Land Discipline Group (refer to this site June 2 and 5 for the next two images in the series). The image is a MODIS data product called 'Leaf Area Index,' which is produced by radiometrically measuring the visible and near infrared energy reflected by vegetation. The Leaf Area Index provides information on the structure of plant canopy, showing how much surface area is covered by green foliage relative to total land surface area. In this image, dark green pixels indicate areas where more than 80 percent of the land surface is covered by green vegetation, light green pixels show where leaves cover about 10 to 50 percent of the land surface, and brown pixels show virtually no leaf coverage. The more leaf area a plant has, the more sunlight it can absorb for photosynthesis. Leaf Area Index is one of a new suite of measurements that scientists use to understand how the Earth's land surfaces are changing over time. Their goal is to use these measurements to refine computer models well enough to simulate how the land biosphere influences the natural cycles of water, carbon, and energy throughout the Earth system. This image is the first of its kind from the MODIS instrument, which launched in December 1999 aboard the Terra spacecraft. MODIS began acquiring scientific data on February 24, 2000, when it first opened its aperture door. The MODIS instrument and Terra spacecraft are both managed by NASA's Goddard Space Flight Center, Greenbelt, MD. Image courtesy Steven Running, MODIS Land Group Member, University of Montana

  5. An accurate air temperature measurement system based on an envelope pulsed ultrasonic time-of-flight technique

    NASA Astrophysics Data System (ADS)

    Huang, Y. S.; Huang, Y. P.; Huang, K. N.; Young, M. S.

    2007-11-01

    A new microcomputer based air temperature measurement system is presented. An accurate temperature measurement is derived from the measurement of sound velocity by using an ultrasonic time-of-flight (TOF) technique. The study proposes a novel algorithm that combines both amplitude modulation (AM) and phase modulation (PM) to get the TOF measurement. The proposed system uses the AM and PM envelope square waveform (APESW) to reduce the error caused by inertia delay. The APESW ultrasonic driving waveform causes an envelope zero and phase inversion phenomenon in the relative waveform of the receiver. To accurately achieve a TOF measurement, the phase inversion phenomenon was used to sufficiently identify the measurement pulse in the received waveform. Additionally, a counter clock technique was combined to compute the phase shifts of the last incomplete cycle for TOF. The presented system can obtain 0.1% TOF resolution for the period corresponding to the 40kHz frequency ultrasonic wave. Consequently, with the integration of a humidity compensation algorithm, a highly accurate and high resolution temperature measurement can be achieved using the accurate TOF measurement. Experimental results indicate that the combined standard uncertainty of the temperature measurement is approximately 0.39°C. The main advantages of this system are high resolution measurements, narrow bandwidth requirements, and ease of implementation.

  6. Describing and compensating gas transport dynamics for accurate instantaneous emission measurement

    NASA Astrophysics Data System (ADS)

    Weilenmann, Martin; Soltic, Patrik; Ajtay, Delia

    Instantaneous emission measurements on chassis dynamometers and engine test benches are becoming increasingly usual for car-makers and for environmental emission factor measurement and calculation, since much more information about the formation conditions can be extracted than from the regulated bag measurements (integral values). The common exhaust gas analysers for the "regulated pollutants" (carbon monoxide, total hydrocarbons, nitrogen oxide, carbon dioxide) allow measurement at a rate of one to ten samples per second. This gives the impression of having after-the-catalyst emission information with that chronological precision. It has been shown in recent years, however, that beside the reaction time of the analysers, the dynamics of gas transport in both the exhaust system of the car and the measurement system last significantly longer than 1 s. This paper focuses on the compensation of all these dynamics convoluting the emission signals. Most analysers show linear and time-invariant reaction dynamics. Transport dynamics can basically be split into two phenomena: a pure time delay accounting for the transport of the gas downstream and a dynamic signal deformation since the gas is mixed by turbulence along the way. This causes emission peaks to occur which are smaller in height and longer in time at the sensors than they are after the catalyst. These dynamics can be modelled using differential equations. Both mixing dynamics and time delay are constant for modelling a raw gas analyser system, since the flow in that system is constant. In the exhaust system of the car, however, the parameters depend on the exhaust volume flow. For gasoline cars, the variation in overall transport time may be more than 6 s. It is shown in this paper how all these processes can be described by invertible mathematical models with the focus on the more complex case of the car's exhaust system. Inversion means that the sharp emission signal at the catalyst out location can be

  7. Carbon monoxide total column retrievals from TROPOMI shortwave infrared measurements

    NASA Astrophysics Data System (ADS)

    Landgraf, Jochen; aan de Brugh, Joost; Scheepmaker, Remco; Borsdorff, Tobias; Hu, Haili; Houweling, Sander; Butz, Andre; Aben, Ilse; Hasekamp, Otto

    2016-10-01

    The Tropospheric Monitoring Instrument (TROPOMI) spectrometer is the single payload of the Copernicus Sentinel 5 Precursor (S5P) mission. It measures Earth radiance spectra in the shortwave infrared spectral range around 2.3 µm with a dedicated instrument module. These measurements provide carbon monoxide (CO) total column densities over land, which for clear sky conditions are highly sensitive to the tropospheric boundary layer. For cloudy atmospheres over land and ocean, the column sensitivity changes according to the light path through the atmosphere. In this study, we present the physics-based operational S5P algorithm to infer atmospheric CO columns satisfying the envisaged accuracy ( < 15 %) and precision ( < 10 %) both for clear sky and cloudy observations with low cloud height. Here, methane absorption in the 2.3 µm range is combined with methane abundances from a global chemical transport model to infer information on atmospheric scattering. For efficient processing, we deploy a linearized two-stream radiative transfer model as forward model and a profile scaling approach to adjust the CO abundance in the inversion. Based on generic measurement ensembles, including clear sky and cloudy observations, we estimated the CO retrieval precision to be ≤ 11 % for surface albedo ≥ 0.03 and solar zenith angle ≤ 70°. CO biases of ≤ 3 % are introduced by inaccuracies in the methane a priori knowledge. For strongly enhanced CO concentrations in the tropospheric boundary layer and for cloudy conditions, CO errors in the order of 8 % can be introduced by the retrieval of cloud parameters of our algorithm. Moreover, we estimated the effect of a distorted spectral instrument response due to the inhomogeneous illumination of the instrument entrance slit in the flight direction to be < 2 % with pseudo-random characteristics when averaging over space and time. Finally, the CO data exploitation is demonstrated for a TROPOMI orbit of simulated shortwave infrared

  8. DCMB that combines divide-and-conquer and mixed-basis set methods for accurate geometry optimizations, total energies, and vibrational frequencies of large molecules.

    PubMed

    Wu, Anan; Xu, Xin

    2012-06-15

    We present a method, named DCMB, for the calculations of large molecules. It is a combination of a parallel divide-and-conquer (DC) method and a mixed-basis (MB) set scheme. In this approach, atomic forces, total energy and vibrational frequencies are obtained from a series of MB calculations, which are derived from the target system utilizing the DC concept. Unlike the fragmentation based methods, all DCMB calculations are performed over the whole target system and no artificial caps are introduced so that it is particularly useful for charged and/or delocalized systems. By comparing the DCMB results with those from the conventional method, we demonstrate that DCMB is capable of providing accurate prediction of molecular geometries, total energies, and vibrational frequencies of molecules of general interest. We also demonstrate that the high efficiency of the parallel DCMB code holds the promise for a routine geometry optimization of large complex systems.

  9. Chronic intestinal ischaemia: measurement of the total splanchnic blood flow.

    PubMed

    Zacho, Helle D

    2013-04-01

    A redundant collateral network between the intestinal arteries is present at all times. In case of ischaemia in the gastrointestinal tract, the collateral blood supply can develop further, thus accommodating the demand for oxygen even in the presence of significant stenosis or occlusion of the intestinal arteries without clinical symptoms of intestinal ischaemia. Symptoms of ischemia develop when the genuine and collateral blood supply no longer can accommodate the need for oxygen. Atherosclerosis is the most common cause of obliteration in the intestinal arteries. In chronic intestinal ischaemia (CII), the fasting splanchnic blood flow (SBF) is sufficient, but the postprandial increase in SBF is inadequate and abdominal pain will therefore develop in relation to food intake causing the patient to eat smaller meals at larger intervals with a resulting weight loss. Traditionally, the CII-diagnosis has exclusively been based upon morphology (angiography) of the intestinal arteries; however, substantial discrepancies between CII-symptoms and the presence of atherosclerosis/stenosis in the intestinal arteries have been described repeatedly in the literature impeding the diagnosis of CII. This PhD thesis explores a method to determine the total SBF and its potential use as a diagnostic tool in patients suspected to suffer from CII. The SBF can be measured using a continuous infusion of a tracer and catheterisation of a hepatic vein and an artery. By measuring the SBF before and after a standard meal it is possible to assess the ability or inability to enhance the SBF and thereby diagnosing CII. In Study I, measurement of SBF was tested against angiography in a group of patients suspected to suffer from CII due to pain and weight loss. A very good agreement between the postprandial increase in SBF and angiography was found. The method was validated against a well-established method independent of the hepatic extraction of tracer using pAH in a porcine model (study II

  10. Summer 2015 measurements of total OH reactivity at a UK coastal site

    NASA Astrophysics Data System (ADS)

    Woodward-Massey, R.; Cryer, D. R.; Whalley, L. K.; Ingham, T.; Crilley, L.; Kramer, L. J.; Reeves, C.; Forster, G.; Oram, D.; Bandy, B.; Reed, C.; Lee, J. D.; Bloss, W.; Heard, D. E.

    2015-12-01

    The hydroxyl radical (OH) plays a central role in the day time oxidative removal of pollutants and greenhouse gases in the atmosphere. It is essential that all production and loss pathways of OH are understood and included in computer models in order to accurately predict OH concentrations for a range of environments, and in turn the rate of production of secondary products, for example ozone and organic aerosol. Direct measurement of total OH reactivity, the pseudo first order rate coefficient for OH loss by reaction with its sinks, is a very useful tool to test how complete our knowledge is of OH loss pathways. Comparison with values of total OH reactivity calculated by computer models using concentrations of simultaneously measured OH 'sinks' and unmeasured intermediates enables environments to be identified where there are unidentified 'missing' OH sinks. Total OH reactivity was measured using the laser flash photolysis combined with time-resolved laser-induced fluorescence technique during the ICOZA (Integrated Chemistry of OZone in the Atmosphere) campaign in July 2015 at the Weybourne Atmospheric Observatory (WAO), Norfolk, UK. Air masses sampled ranged from polluted air from the UK or Europe containing processed urban emissions to very clean air of marine origin. Data for measured and calculated OH reactivity will be presented in addition to a discussion of the magnitude of the 'missing' OH sink determined for each type of air mass.

  11. 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.

  12. Robust dynamic myocardial perfusion CT deconvolution for accurate residue function estimation via adaptive-weighted tensor total variation regularization: a preclinical study

    NASA Astrophysics Data System (ADS)

    Zeng, Dong; Gong, Changfei; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Niu, Shanzhou; Zhang, Zhang; Liang, Zhengrong; Feng, Qianjin; Chen, Wufan; Ma, Jianhua

    2016-11-01

    Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total variation (AwTTV) regularization for accurate residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed ‘MPD-AwTTV’. More specifically, the gains of the AwTTV regularization over the original tensor total variation regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and accurate flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment.

  13. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew Charles Rule

    1999-11-16

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  14. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew C. R.; Hudgens, Jeffrey W.

    1999-08-24

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  15. A method of treating the non-grey error in total emittance measurements

    NASA Technical Reports Server (NTRS)

    Heaney, J. B.; Henninger, J. H.

    1971-01-01

    In techniques for the rapid determination of total emittance, the sample is generally exposed to surroundings that are at a different temperature than the sample's surface. When the infrared spectral reflectance of the surface is spectrally selective, these techniques introduce an error into the total emittance values. Surfaces of aluminum overcoated with oxides of various thicknesses fall into this class. Because they are often used as temperature control coatings on satellites, their emittances must be accurately known. The magnitude of the error was calculated for Alzak and silicon oxide-coated aluminum and was shown to be dependent on the thickness of the oxide coating. The results demonstrate that, because the magnitude of the error is thickness-dependent, it is generally impossible or impractical to eliminate it by calibrating the measuring device.

  16. 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

  17. μTAS (micro total analysis systems) for the high-throughput measurement of nanomaterial solubility

    NASA Astrophysics Data System (ADS)

    Tantra, R.; Jarman, J.

    2013-04-01

    There is a consensus in the nanoecotoxicology community that better analytical tools i.e. faster and more accurate ones, are needed for the physicochemical characterisation of nanomaterials in environmentally/biologically relevant media. In this study, we introduce the concept of μTAS (Micro Total Analysis Systems), which was a term coined to encapsulate the integration of laboratory processes on a single microchip. Our focus here is on the use of a capillary electrophoresis (CE) with conductivity detection microchip and how this may be used for the measurement of dissolution of metal oxide nanomaterials. Our preliminary results clearly show promise in that the device is able to: a) measure ionic zinc in various ecotox media with high selectivity b) track the dynamic dissolution events of zinc oxide (ZnO) nanomaterial when dispersed in fish medium.

  18. Improved Segmented-Flow Tracer-Monitored Titration for Automated Measurement of Total Alkalinity in Seawater

    NASA Astrophysics Data System (ADS)

    Spaulding, R. S.; Hales, B.; Beck, J. C.; Degrandpre, M. D.

    2008-12-01

    The four measurable inorganic carbon parameters commonly measured as part of oceanic carbon cycle studies are total dissolved inorganic carbon (DIC), total alkalinity (AT), hydrogen ion concentration (pH) and partial pressure of CO2 (pCO2). AT determination is critical for anthropogenic CO2 inventory calculations and for quantifying CaCO3 saturation. Additionally, measurement of AT in combination with one other carbonate parameter can be used to describe the inorganic carbon equilibria. Current methods for measuring AT require calibrated volumetric flasks and burettes, gravimetry, or precise flow measurements. These methods also require analysis times of ˜15 min and sample volumes of ˜200 mL, and sample introduction is not automated, resulting in labor-intensive measurements and low temporal resolution. The Tracer Monitored Titration (TMT) system was previously developed at the University of Montana for AT measurements. The TMT is not dependent on accurate gravimetric, volumetric or flow rate measurements because it relies on a pH-sensitive indicator (tracer) to track the amount of titrant added to the sample. Sample and a titrant-indicator mixture are mechanically stirred in an optical flow cell and pH is calculated using the indicator equilibrium constant and the spectrophotometrically determined concentrations of the acid and base forms of the indicator. AT is then determined using these data in a non-linear least squares regression of the AT mass and proton balances. The precision and accuracy of the TMT are 2 and 4 micromol per kg in 16 min using 110-mL of sample. The TMT is dependent on complete mixing of titrant with the sample and accurate absorbance measurements. We have developed the segmented-flow TMT (SF- TMT) to improve on these aspects and decrease sample analysis time. The TMT uses segmented flow instead of active mixing and a white LED instead of a tungsten-halogen light source. Air is added to the liquid flow stream, producing segments of liquid

  19. Standardization of vitrinite reflectance measurements in shale petroleum systems: How accurate are my Ro data?

    USGS Publications Warehouse

    Hackley, Paul C.

    2014-01-01

    Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708-11: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks. In 2012-2013, an interlaboratory exercise was conducted to establish precision limits for the measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (Ro 0.31-1.53%), from organic-rich to organic-lean (1-22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability values (difference between repetitive results from same operator, same conditions) ranged from 0.03-0.11% absolute reflectance, whereas reproducibility values (difference between results obtained on same test material by different operators, different laboratories) ranged from 0.12-0.54% absolute reflectance. Repeatability and reproducibility degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping the other components. Discussion among

  20. 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.

  1. 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%.

  2. The global distribution on total ozone - Toms satellite measurements

    NASA Technical Reports Server (NTRS)

    Krueger, Arlin J.

    1989-01-01

    The general behavior of total ozone by season and latitude was known before 1930 through the pioneering observations by Dobson. The ozone record at Oxford and other European stations was dominated by an annual cycle and by irregular short term fluctuations. The amplitude and phase of the annual cycle were determined at representative latitudes in both hemispheres. However, the short term variations appeared to be meteorological origin, although the specific cause could not be identified. Data from the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus 7 spacecraft, with global coverage at an average spatial resolution of 66 km, can now be used to completely map the total ozone field. These maps demonstrate that troughs and ridges in the upper troposphere are responsible for the large, short term ozone variations found at middle latitudes, while in the tropics, the steady, low ozone levels show broad scale structure associated with the Hadley circulation.

  3. 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.

  4. Assessing Educational Processes Using Total-Quality-Management Measurement Tools.

    ERIC Educational Resources Information Center

    Macchia, Peter, Jr.

    1993-01-01

    Discussion of the use of Total Quality Management (TQM) assessment tools in educational settings highlights and gives examples of fishbone diagrams, or cause and effect charts; Pareto diagrams; control charts; histograms and check sheets; scatter diagrams; and flowcharts. Variation and quality are discussed in terms of continuous process…

  5. Novel method for accurate g measurements in electron-spin resonance

    NASA Astrophysics Data System (ADS)

    Stesmans, A.; Van Gorp, G.

    1989-09-01

    In high-accuracy work, electron-spin-resonance (ESR) g values are generally determined by calibrating against the accurately known proton nuclear magnetic resonance (NMR). For that method—based on leakage of microwave energy out of the ESR cavity—a convenient technique is presented to obtain accurate g values without needing conscientious precalibration procedures or cumbersome constructions. As main advantages, the method allows the easy monitoring of the positioning of the ESR and NMR samples while they are mounted as close as physically realizable at all time during their simultaneous resonances. Relative accuracies on g of ≊2×10-6 are easily achieved for ESR signals of peak-to-peak width ΔBpp≲0.3 G. The method has been applied to calibrate the g value of conduction electrons of small Li particles embedded in LiF—a frequently used g marker—resulting in gLiF: Li=2.002 293±0.000 002.

  6. 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

  7. 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%).

  8. Accurate monitoring and fault detection in wind measuring devices through wireless sensor networks.

    PubMed

    Khan, Komal Saifullah; Tariq, Muhammad

    2014-11-24

    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.

  9. Direct total body (214)Bi measurements and their implications for radon dose assessment.

    PubMed

    Kalef-Ezra, John A; Valakis, Stratos T

    2016-09-01

    Direct (214)Bi bioassays may elucidate some of the uncertainties related to the relationship between the ambient concentration of radon and its short-lived decay products and the corresponding radiation burdens of individual human subjects. Sequential total body (214)Bi activity measurements were carried out on a group of 67 healthy adult volunteers living in a region with moderate airborne radioactivity and conducting similar daily activities using a whole-body counter equipped with sixteen NaI(Tl) detectors. The total body (214)Bi activity in the studied subjects was related to gender, fat-free mass and the season of the year. Approximately 95% and 92% of the (214)Bi activity measured during the cold seasons of the year in men and women, respectively, was attributed to radon progeny inhalation. Following acute exposure to high airborne radioactivity over a short time period, the (214)Bi enhancement in a volunteer decreased exponentially with time post-exposure, with a half-time of about 40 min. Taking into account the anticipated low (214)Bi activity in the vast majority of individuals, and the uncertainties in (214)Bi biodistribution even during counting, accurate measurements can be obtained using high-sensitivity whole-body counters with almost geometrical invariant counting efficiency.

  10. 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

  11. Total x-ray power measurements in the Sandia LIGA program.

    SciTech Connect

    Malinowski, Michael E. (Sandia National Laboratories, Livermore, CA); Ting, Aili (Sandia National Laboratories, Livermore, CA)

    2005-08-01

    Total X-ray power measurements using aluminum block calorimetry and other techniques were made at LIGA X-ray scanner synchrotron beamlines located at both the Advanced Light Source (ALS) and the Advanced Photon Source (APS). This block calorimetry work was initially performed on the LIGA beamline 3.3.1 of the ALS to provide experimental checks of predictions of the LEX-D (LIGA Exposure- Development) code for LIGA X-ray exposures, version 7.56, the version of the code in use at the time calorimetry was done. These experiments showed that it was necessary to use bend magnet field strengths and electron storage ring energies different from the default values originally in the code in order to obtain good agreement between experiment and theory. The results indicated that agreement between LEX-D predictions and experiment could be as good as 5% only if (1) more accurate values of the ring energies, (2) local values of the magnet field at the beamline source point, and (3) the NIST database for X-ray/materials interactions were used as code inputs. These local magnetic field value and accurate ring energies, together with NIST database, are now defaults in the newest release of LEX-D, version 7.61. Three dimensional simulations of the temperature distributions in the aluminum calorimeter block for a typical ALS power measurement were made with the ABAQUS code and found to be in good agreement with the experimental temperature data. As an application of the block calorimetry technique, the X-ray power exiting the mirror in place at a LIGA scanner located at the APS beamline 10 BM was measured with a calorimeter similar to the one used at the ALS. The overall results at the APS demonstrated the utility of calorimetry in helping to characterize the total X-ray power in LIGA beamlines. In addition to the block calorimetry work at the ALS and APS, a preliminary comparison of the use of heat flux sensors, photodiodes and modified beam calorimeters as total X-ray power

  12. 43 CFR 3275.15 - How accurately must I measure my production and utilization?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... royalty: (1) If the meter measures electricity, it must have an accuracy of ±0.25% or better of reading... meter measures water flowing at more than 500,000 lbs/hr on a monthly basis, it must have an accuracy reading of ±2 percent or better; (5) If the meter measures water flowing at 500,000 lbs/hr or less on...

  13. Lightdrum—Portable Light Stage for Accurate BTF Measurement on Site

    PubMed Central

    Havran, Vlastimil; Hošek, Jan; Němcová, Šárka; Čáp, Jiří; Bittner, Jiří

    2017-01-01

    We propose a miniaturised light stage for measuring the bidirectional reflectance distribution function (BRDF) and the bidirectional texture function (BTF) of surfaces on site in real world application scenarios. The main principle of our lightweight BTF acquisition gantry is a compact hemispherical skeleton with cameras along the meridian and with light emitting diode (LED) modules shining light onto a sample surface. The proposed device is portable and achieves a high speed of measurement while maintaining high degree of accuracy. While the positions of the LEDs are fixed on the hemisphere, the cameras allow us to cover the range of the zenith angle from 0∘ to 75∘ and by rotating the cameras along the axis of the hemisphere we can cover all possible camera directions. This allows us to take measurements with almost the same quality as existing stationary BTF gantries. Two degrees of freedom can be set arbitrarily for measurements and the other two degrees of freedom are fixed, which provides a tradeoff between accuracy of measurements and practical applicability. Assuming that a measured sample is locally flat and spatially accessible, we can set the correct perpendicular direction against the measured sample by means of an auto-collimator prior to measuring. Further, we have designed and used a marker sticker method to allow for the easy rectification and alignment of acquired images during data processing. We show the results of our approach by images rendered for 36 measured material samples. PMID:28241466

  14. 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.

  15. Metrology target design simulations for accurate and robust scatterometry overlay measurements

    NASA Astrophysics Data System (ADS)

    Ben-Dov, Guy; Tarshish-Shapir, Inna; Gready, David; Ghinovker, Mark; Adel, Mike; Herzel, Eitan; Oh, Soonho; Choi, DongSub; Han, Sang Hyun; El Kodadi, Mohamed; Hwang, Chan; Lee, Jeongjin; Lee, Seung Yoon; Lee, Kuntack

    2016-03-01

    Overlay metrology target design is an essential step prior to performing overlay measurements. This step is done through the optimization of target parameters for a given process stack. A simulation tool is therefore used to improve measurement performances. This work shows how our Metrology Target Design (MTD) simulator helps significantly in the target design process. We show the role of film and Optical CD measurements in improving significantly the fidelity of the simulations. We demonstrate that for various target design parameters we are capable of predicting measured performance metrics by simulations and correctly rank various designs performances.

  16. Lightdrum-Portable Light Stage for Accurate BTF Measurement on Site.

    PubMed

    Havran, Vlastimil; Hošek, Jan; Němcová, Šárka; Čáp, Jiří; Bittner, Jiří

    2017-02-23

    We propose a miniaturised light stage for measuring the bidirectional reflectance distribution function (BRDF) and the bidirectional texture function (BTF) of surfaces on site in real world application scenarios. The main principle of our lightweight BTF acquisition gantry is a compact hemispherical skeleton with cameras along the meridian and with light emitting diode (LED) modules shining light onto a sample surface. The proposed device is portable and achieves a high speed of measurement while maintaining high degree of accuracy. While the positions of the LEDs are fixed on the hemisphere, the cameras allow us to cover the range of the zenith angle from 0 ∘ to 75 ∘ and by rotating the cameras along the axis of the hemisphere we can cover all possible camera directions. This allows us to take measurements with almost the same quality as existing stationary BTF gantries. Two degrees of freedom can be set arbitrarily for measurements and the other two degrees of freedom are fixed, which provides a tradeoff between accuracy of measurements and practical applicability. Assuming that a measured sample is locally flat and spatially accessible, we can set the correct perpendicular direction against the measured sample by means of an auto-collimator prior to measuring. Further, we have designed and used a marker sticker method to allow for the easy rectification and alignment of acquired images during data processing. We show the results of our approach by images rendered for 36 measured material samples.

  17. Radiological method for measuring patellofemoral tracking and tibiofemoral kinematics before and after total knee replacement

    PubMed Central

    Sharma, G. B.; Saevarsson, S. K.; Amiri, S.; Montgomery, S.; Ramm, H.; Lichti, D. D.; Lieck, R.; Zachow, S.; Anglin, C.

    2012-01-01

    Objectives Numerous complications following total knee replacement (TKR) relate to the patellofemoral (PF) joint, including pain and patellar maltracking, yet the options for in vivo imaging of the PF joint are limited, especially after TKR. We propose a novel sequential biplane radiological method that permits accurate tracking of the PF and tibiofemoral (TF) joints throughout the range of movement under weightbearing, and test it in knees pre- and post-arthroplasty. Methods A total of three knees with end-stage osteoarthritis and three knees that had undergone TKR at more than one year’s follow-up were investigated. In each knee, sequential biplane radiological images were acquired from the sagittal direction (i.e. horizontal X-ray source and 10° below horizontal) for a sequence of eight flexion angles. Three-dimensional implant or bone models were matched to the biplane images to compute the six degrees of freedom of PF tracking and TF kinematics, and other clinical measures. Results The mean and standard deviation for the six degrees of freedom of PF tracking and TF kinematics were computed. TF and PF kinematics were highly accurate (< 0.9 mm, < 0.6°) and repeatable. Conclusions The developed method permitted measuring of in vivo PF tracking and TF kinematics before and after TKR throughout the range of movement. This method could be a useful tool for investigating differences between cohorts of patients (e.g., with and without pain) impacting clinical decision-making regarding surgical technique, revision surgery or implant design. PMID:23610657

  18. Accurate respiration measurement using DC-coupled continuous-wave radar sensor for motion-adaptive cancer radiotherapy.

    PubMed

    Gu, Changzhan; Li, Ruijiang; Zhang, Hualiang; Fung, Albert Y C; Torres, Carlos; Jiang, Steve B; Li, Changzhi

    2012-11-01

    Accurate respiration measurement is crucial in motion-adaptive cancer radiotherapy. Conventional methods for respiration measurement are undesirable because they are either invasive to the patient or do not have sufficient accuracy. In addition, measurement of external respiration signal based on conventional approaches requires close patient contact to the physical device which often causes patient discomfort and undesirable motion during radiation dose delivery. In this paper, a dc-coupled continuous-wave radar sensor was presented to provide a noncontact and noninvasive approach for respiration measurement. The radar sensor was designed with dc-coupled adaptive tuning architectures that include RF coarse-tuning and baseband fine-tuning, which allows the radar sensor to precisely measure movement with stationary moment and always work with the maximum dynamic range. The accuracy of respiration measurement with the proposed radar sensor was experimentally evaluated using a physical phantom, human subject, and moving plate in a radiotherapy environment. It was shown that respiration measurement with radar sensor while the radiation beam is on is feasible and the measurement has a submillimeter accuracy when compared with a commercial respiration monitoring system which requires patient contact. The proposed radar sensor provides accurate, noninvasive, and noncontact respiration measurement and therefore has a great potential in motion-adaptive radiotherapy.

  19. 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…

  20. Low-frequency oscillations in total ozone measurements

    NASA Technical Reports Server (NTRS)

    Gao, X. H.; Stanford, J. L.

    1990-01-01

    Low frequency oscillations with periods of approximately one to two months are found in eight years of global grids of total ozone data from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument. The low frequency oscillations corroborate earlier analyses based on four years of data. In addition, both annual and seasonal one-point correlation maps based on the 8-year TOMS data are presented. The results clearly show a standing dipole in ozone perturbations, oscillating with 35 to 50 day periods over the equatorial Indian Ocean-west Pacific region. This contrasts with the eastward moving dipole reported in other data sets. The standing ozone dipole appears to be a dynamical feature associated with vertical atmospheric motions. Consistent with prior analyses based on lower stratospheric temperature fields, large-scale standing patterns are also found in the extratropics of both hemispheres, correlated with ozone fluctuations over the equatorial west Pacific. In the Northern Hemisphere, a standing pattern is observed extending from the tropical Indian Ocean to the north Pacific, across North America, and down to the equatorial Atlantic Ocean region. This feature is most pronounced in the NH summer.

  1. An Inexpensive, Stable, and Accurate Relative Humidity Measurement Method for Challenging Environments.

    PubMed

    Zhang, Wei; Ma, Hong; Yang, Simon X

    2016-03-18

    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.

  2. 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

  3. 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

  4. 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.

  5. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

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

    2014-01-01

    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 two-dimensional 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. PMID:25368961

  6. [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.

  7. Novel methodology for accurate resolution of fluid signatures from multi-dimensional NMR well-logging measurements.

    PubMed

    Anand, Vivek

    2017-03-01

    A novel methodology for accurate fluid characterization from multi-dimensional nuclear magnetic resonance (NMR) well-logging measurements is introduced. This methodology overcomes a fundamental challenge of poor resolution of features in multi-dimensional NMR distributions due to low signal-to-noise ratio (SNR) of well-logging measurements. Based on an unsupervised machine-learning concept of blind source separation, the methodology resolves fluid responses from simultaneous analysis of large quantities of well-logging data. The multi-dimensional NMR distributions from a well log are arranged in a database matrix that is expressed as the product of two non-negative matrices. The first matrix contains the unique fluid signatures, and the second matrix contains the relative contributions of the signatures for each measurement sample. No a priori information or subjective assumptions about the underlying features in the data are required. Furthermore, the dimensionality of the data is reduced by several orders of magnitude, which greatly simplifies the visualization and interpretation of the fluid signatures. Compared to traditional methods of NMR fluid characterization which only use the information content of a single measurement, the new methodology uses the orders-of-magnitude higher information content of the entire well log. Simulations show that the methodology can resolve accurate fluid responses in challenging SNR conditions. The application of the methodology to well-logging data from a heavy oil reservoir shows that individual fluid signatures of heavy oil, water associated with clays and water in interstitial pores can be accurately obtained.

  8. Novel methodology for accurate resolution of fluid signatures from multi-dimensional NMR well-logging measurements

    NASA Astrophysics Data System (ADS)

    Anand, Vivek

    2017-03-01

    A novel methodology for accurate fluid characterization from multi-dimensional nuclear magnetic resonance (NMR) well-logging measurements is introduced. This methodology overcomes a fundamental challenge of poor resolution of features in multi-dimensional NMR distributions due to low signal-to-noise ratio (SNR) of well-logging measurements. Based on an unsupervised machine-learning concept of blind source separation, the methodology resolves fluid responses from simultaneous analysis of large quantities of well-logging data. The multi-dimensional NMR distributions from a well log are arranged in a database matrix that is expressed as the product of two non-negative matrices. The first matrix contains the unique fluid signatures, and the second matrix contains the relative contributions of the signatures for each measurement sample. No a priori information or subjective assumptions about the underlying features in the data are required. Furthermore, the dimensionality of the data is reduced by several orders of magnitude, which greatly simplifies the visualization and interpretation of the fluid signatures. Compared to traditional methods of NMR fluid characterization which only use the information content of a single measurement, the new methodology uses the orders-of-magnitude higher information content of the entire well log. Simulations show that the methodology can resolve accurate fluid responses in challenging SNR conditions. The application of the methodology to well-logging data from a heavy oil reservoir shows that individual fluid signatures of heavy oil, water associated with clays and water in interstitial pores can be accurately obtained.

  9. 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.

  10. 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.

  11. Quantitative orientation measurements in thin lipid films by attenuated total reflection infrared spectroscopy.

    PubMed Central

    Picard, F; Buffeteau, T; Desbat, B; Auger, M; Pézolet, M

    1999-01-01

    Quantitative orientation measurements by attenuated total reflectance (ATR) infrared spectroscopy require the accurate knowledge of the dichroic ratio and of the mean-square electric fields along the three axes of the ATR crystal. In this paper, polarized ATR spectra of single supported bilayers of the phospholipid dimyristoylphosphatidic acid covered by either air or water have been recorded and the dichroic ratio of the bands due to the methylene stretching vibrations has been calculated. The mean-square electric field amplitudes were calculated using three formalisms, namely the Harrick thin film approximation, the two-phase approximation, and the thickness- and absorption-dependent one. The results show that for dry bilayers, the acyl chain tilt angle varies with the formalism used, while no significant variations are observed for the hydrated bilayers. To test the validity of the different formalisms, s- and p-polarized ATR spectra of a 40-A lipid layer were simulated for different acyl chain tilt angles. The results show that the thickness- and absorption-dependent formalism using the mean values of the electric fields over the film thickness gives the most accurate values of acyl chain tilt angle in dry lipid films. However, for lipid monolayers or bilayers, the tilt angle can be determined with an acceptable accuracy using the Harrick thin film approximation. Finally, this study shows clearly that the uncertainty on the determination of the tilt angle comes mostly from the experimental error on the dichroic ratio and from the knowledge of the refractive index. PMID:9876167

  12. Accurate Ultrasonic Measurement of Surface Profile Using Phase Shift of Echo and Inverse Filtering

    NASA Astrophysics Data System (ADS)

    Arihara, Chihiro; Hasegawa, Hideyuki; Kanai, Hiroshi

    2006-05-01

    Atherosclerosis is the main cause of circulatory diseases such as myocardial infarction and cerebral infarction, and it is very important to diagnose atherosclerosis in its early stage. In the early stage of atherosclerosis, the luminal surface of an arterial wall becomes rough because of the injury of the endothelium [R. Ross: New Engl. J. Med. 340 (2004) 115]. Conventional ultrasonic diagnostic equipments cannot detect such roughness on the order of micrometer because of their low resolution of approximately 0.1 mm. In this study, for the accurate detection of surface roughness, an ultrasonic beam was scanned in the direction that is parallel to the surface of an object. When there is a gap on the surface, the phase of the echo from the surface changes because the distance between the probe and the surface changes during the scanning. Therefore, surface roughness can be assessed by estimating the phase shift of echoes obtained during the beam scanning. Furthermore, lateral resolution, which is deteriorated by a finite diameter of the ultrasound beam, was improved by an inverse filter. By using the proposed method, the surface profile of a phantom, which had surface roughness on the micrometer order, was detected, and the estimated surface profiles became more precise by applying the inverse filter.

  13. Total Extractable Tin Measurement in Complex Matrices. An Evaluation.

    DTIC Science & Technology

    1986-01-01

    tributyltin chloride (Aldrich Chemical Company) or dibutyltin dichloride (Aldrich Chemical Company) in 95-percent ethanol to prepare the calibration...hexane were prepared similarly from tributyltin chloride and dibutyltin dichloride. For hydride derivatization/flame AAS measurements, 1.0-ml aliquots...water bath and a 150*C oil bath to volatilize Bu 2SnH 2 and Bu 3SnH, respectively. Standards consisting of tributyltin chloride and dibutyltin dichloride

  14. The measurement of total serum proteins by the Biuret method.

    PubMed

    Lubran, M M

    1978-01-01

    The biuret reaction for proteins provides a simple and precise method for measuring serum proteins; Beer's law is obeyed to at least 10 g per dl. Several stable biuret reagents are available. Hemoglobin is the only important cause of interference which cannot be minimized by use of a sample blank. The mechanism of the biuret reaction is described and attention is drawn to the heterogeneity of the serum proteins and to the use of a certified albumin standard.

  15. Instrumentation for the accurate measurement of phase and amplitude in optical tomography

    NASA Astrophysics Data System (ADS)

    Nissilä, Ilkka; Kotilahti, Kalle; Fallström, Kim; Katila, Toivo

    2002-09-01

    A single-channel prototype for a frequency-domain optical tomography system is presented. The two main goals in the design of the system were the measurement of phase with minimal systematic errors and a high enough signal-to-noise ratio to detect the small changes in the absorption of brain tissue during brain activity. Although the system inherently is an imaging system, the aspects of the system that relate to multichannel operation will be published separately, as this part of the system is not yet finished. The instrument is described in detail, including the radio-frequency system, the light detection system, and the light source. Factors that affect the accuracy of the measured phase include phase drift, radio-frequency coupling between the source and detector electronics, phase-amplitude cross talk, and others. To increase the range of intensities that can be measured, the gain of the detector is adjusted while keeping the mean anode current small compared with the quiescent current through the voltage bleeder of the photomultiplier tube so that cross talk is avoided. The calibration of the measurements is considered, and the data measured on a phantom are compared with a time-resolved instrument as well as with a finite-element forward model. The instrument allows the measurement of phase to an accuracy of 0.5° between 80 fW and 80 nW at a modulation frequency of 100 MHz, giving a dynamic range of 1:106. With a time constant of 0.3 s, phase noise is 0.5° at 1 pW and decreases to 0.06° in a typical activation measurement at 3 cm separation between the optodes. Amplitude noise is 0.8% at 1 pW and 0.1% at 3 cm separation.

  16. How accurate are electronic monitoring devices? A laboratory study testing two devices to measure medication adherence.

    PubMed

    De Bleser, Leentje; De Geest, Sabina; Vandenbroeck, Sofie; Vanhaecke, Johan; Dobbels, Fabienne

    2010-01-01

    In a prospective descriptive laboratory study, 25 Helping Hand(™) (HH) (10 without and 15 with reminder system) and 50 Medication Event Monitoring Systems (MEMS) (25 with 18-month and 25 with 2-year battery life) were manipulated twice daily following a predefined protocol during 3 consecutive weeks. Accuracy was determined using the fixed manipulation scheme as the reference. Perfect functioning (i.e., total absence of missing registrations and/or overregistrations) was observed in 70% of the HH without, 87% of the HH with reminder, 20% MEMS with 18 months, and 100% with 2-year battery life respectively.

  17. A method to account for the temperature sensitivity of TCCON total column measurements

    NASA Astrophysics Data System (ADS)

    Niebling, Sabrina G.; Wunch, Debra; Toon, Geoffrey C.; Wennberg, Paul O.; Feist, Dietrich G.

    2014-05-01

    The Total Carbon Column Observing Network (TCCON) consists of ground-based Fourier Transform Spectrometer (FTS) systems all around the world. It achieves better than 0.25% precision and accuracy for total column measurements of CO2 [Wunch et al. (2011)]. In recent years, the TCCON data processing and retrieval software (GGG) has been improved to achieve better and better results (e. g. ghost correction, improved a priori profiles, more accurate spectroscopy). However, a small error is also introduced by the insufficent knowledge of the true temperature profile in the atmosphere above the individual instruments. This knowledge is crucial to retrieve highly precise gas concentrations. In the current version of the retrieval software, we use six-hourly NCEP reanalysis data to produce one temperature profile at local noon for each measurement day. For sites in the mid latitudes which can have a large diurnal variation of the temperature in the lowermost kilometers of the atmosphere, this approach can lead to small errors in the final gas concentration of the total column. Here, we present and describe a method to account for the temperature sensitivity of the total column measurements. We exploit the fact that H2O is most abundant in the lowermost kilometers of the atmosphere where the largest diurnal temperature variations occur. We use single H2O absorption lines with different temperature sensitivities to gain information about the temperature variations over the course of the day. This information is used to apply a posteriori correction of the retrieved gas concentration of total column. In addition, we show that the a posteriori temperature correction is effective by applying it to data from Lamont, Oklahoma, USA (36,6°N and 97,5°W). We chose this site because regular radiosonde launches with a time resolution of six hours provide detailed information of the real temperature in the atmosphere and allow us to test the effectiveness of our correction. References

  18. Three dimensional accurate morphology measurements of polystyrene standard particles on silicon substrate by electron tomography.

    PubMed

    Hayashida, Misa; Kumagai, Kazuhiro; Malac, Marek

    2015-12-01

    Polystyrene latex (PSL) nanoparticle (NP) sample is one of the most widely used standard materials. It is used for calibration of particle counters and particle size measurement tools. It has been reported that the measured NP sizes by various methods, such as Differential Mobility Analysis, dynamic light scattering (DLS), optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), differ from each other. Deformation of PSL NPs on mica substrate has been reported in AFM measurements: the lateral width of PSL NPs is smaller than their vertical height. To provide a reliable calibration standard, the deformation must be measured by a method that can reliably visualize the entire three dimensional (3D) shape of the PSL NPs. Here we present a method for detailed measurement of PSL NP 3D shape by means of electron tomography in a transmission electron microscope. The observed shape of the PSL NPs with 100 nm and 50 nm diameter were not spherical, but squished in direction perpendicular to the support substrate by about 7.4% and 12.1%, respectively. The high difference in surface energy of the PSL NPs and that of substrate together with their low Young modulus appear to explain the squishing of the NPs without presence of water film.

  19. Accurate GPS measurement of the location and orientation of a floating platform. [for sea floor geodesy

    NASA Technical Reports Server (NTRS)

    Purcell, G. H., Jr.; Young, L. E.; Wolf, S. K.; Meehan, T. K.; Duncan, C. B.; Fisher, S. S.; Spiess, F. N.; Austin, G.; Boegeman, D. E.; Lowenstein, C. D.

    1990-01-01

    This article describes the design and initial tests of the GPS portion of a system for making seafloor geodesy measurements. In the planned system, GPS antennas on a floating platform will be used to measure the location of an acoustic transducer, attached below the platform, which interrogates an array of transponders on the seafloor. Since the GPS antennas are necessarily some distance above the transducer, a short-baseline GPS interferometer consisting of three antennas is used to measure the platform's orientation. A preliminary test of several crucial elements of the system was performed. The test involved a fixed antenna on the pier and a second antenna floating on a buoy about 80 m away. GPS measurements of the vertical component of this baseline, analyzed independently by two groups using different software, agree with each other and with an independent measurement within a centimeter. The first test of an integrated GPS/acoustic system took place in the Santa Cruz Basin off the coast of southern California in May 1990. In this test a much larger buoy, designed and built at SIO, was equipped with three GPS antennas and an acoustic transducer that interrogated a transponder on the ocean floor. Preliminary analysis indicates that the horizontal position of the transponder can be determined with a precision of about a centimeter.

  20. Accurate GPS measurement of the location and orientation of a floating platform

    NASA Astrophysics Data System (ADS)

    Purcell, G. H., Jr.; Young, L. E.; Wolf, S. K.; Meehan, T. K.; Duncan, C. B.; Fisher, S. S.; Spiess, F. N.; Austin, G.; Boegeman, D. E.; Lowenstein, C. D.

    This article describes the design and initial tests of the GPS portion of a system for making seafloor geodesy measurements. In the planned system, GPS antennas on a floating platform will be used to measure the location of an acoustic transducer, attached below the platform, which interrogates an array of transponders on the seafloor. Since the GPS antennas are necessarily some distance above the transducer, a short-baseline GPS interferometer consisting of three antennas is used to measure the platform's orientation. A preliminary test of several crucial elements of the system was performed. The test involved a fixed antenna on the pier and a second antenna floating on a buoy about 80 m away. GPS measurements of the vertical component of this baseline, analyzed independently by two groups using different software, agree with each other and with an independent measurement within a centimeter. The first test of an integrated GPS/acoustic system took place in the Santa Cruz Basin off the coast of southern California in May 1990. In this test a much larger buoy, designed and built at SIO, was equipped with three GPS antennas and an acoustic transducer that interrogated a transponder on the ocean floor. Preliminary analysis indicates that the horizontal position of the transponder can be determined with a precision of about a centimeter.

  1. Decay Heat Measurements Using Total Absorption Gamma-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rice, S.; Valencia, E.; Algora, A.; Taín, J. L.; Regan, P. H.; Podolyák, Z.; Agramunt, J.; Gelletly, W.; Nichols, A. L.

    2012-09-01

    A knowledge of the decay heat emitted by thermal neutron-irradiated nuclear fuel is an important factor in ensuring safe reactor design and operation, spent fuel removal from the core, and subsequent storage prior to and after reprocessing, and waste disposal. Decay heat can be readily calculated from the nuclear decay properties of the fission products, actinides and their decay products as generated within the irradiated fuel. Much of the information comes from experiments performed with HPGe detectors, which often underestimate the beta feeding to states at high excitation energies. This inability to detect high-energy gamma emissions effectively results in the derivation of decay schemes that suffer from the pandemonium effect, although such a serious problem can be avoided through application of total absorption γ-ray spectroscopy (TAS). The beta decay of key radionuclei produced as a consequence of the neutron-induced fission of 235U and 239Pu are being re-assessed by means of this spectroscopic technique. A brief synopsis is given of the Valencia-Surrey (BaF2) TAS detector, and their method of operation, calibration and spectral analysis.

  2. Total pollen counts do not influence active surface measurements

    NASA Astrophysics Data System (ADS)

    Moshammer, Hanns; Schinko, Herwig; Neuberger, Manfred

    We investigated the temporal association of various aerosol parameters with pollen counts in the pollen season (April 2001) in Linz, Austria. We were especially interested in the relationship between active surface (or Fuchs' surface) because we had shown previously (Atmos. Environ. 37 (2003) 1737-1744) that this parameter during the same observation period was a better predictor for acute respiratory symptoms in school children (like wheezing, shortness of breath, and cough) and reduced lung function on the same day than particle mass (PM 10). While active surface is most sensitive for fine particles with a diameter of less than 100 nm it has no strict upper cut-off regarding particle size and so could eventually be influenced also by larger particles if their numbers were high. All particle mass parameters tested (TSP, PM 10, PM 1) were weakly ( r approximately 0.2) though significantly correlated with pollen counts but neither was active surface nor total particle counts (CPC). The weak association of particle mass and pollen counts was due mainly to similar diurnal variations and a linear trend over time. Only the mass of the coarse fraction (TSP minus PM 10) remained associated with pollen counts significantly after controlling for these general temporal patterns.

  3. Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

    PubMed

    Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

    2002-09-01

    Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore

  4. A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.

    PubMed

    Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric

    2012-03-07

    We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.

  5. METHOD 415.3 - MEASUREMENT OF TOTAL ORGANIC ...

    EPA Pesticide Factsheets

    2.0 SUMMARY OF METHOD2.1 In both TOC and DOC determinations, organic carbon in the water sample is oxidized to form carbon dioxide (CO2), which is then measured by a detection system. There are two different approaches for the oxidation of organic carbon in water samples to carbon dioxide gas: (a) combustion in an oxidizing gas and (b) UV promoted or heat catalized chemical oxidation with a persulfate solution. Carbon dioxide, which is released from the oxidized sample, is detected by a conductivity detector or by a nondispersive infrared (NDIR) detector. Instruments using any combination of the above technologies may be used in this method.2.2. Setteable solids and floating matter may cause plugging of valves, tubing, and the injection needle port. The TOC procedure allows the removal of settleable solids and floating matter. The suspended matter is considered part of the sample. The resulting water sample is then considered a close approximation of the original whole water sample for the purpose of TOC measurement.2.3. The DOC procedure requires that the sample be passed through a 0.45 um filter prior to analysis.2.4. The TOC and DOC procedures require that all inorganic carbon be removed from the sample before the sample is analyzed for organic carbon content. If the inorganic carbon (IC) is not completely removed, significant error will occur. The inorganic carbon interference is removed by converting the mineralized IC to CO2 by acidification and

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. The effect of external dynamic loads on the lifetime of rolling element bearings: accurate measurement of the bearing behaviour

    NASA Astrophysics Data System (ADS)

    Jacobs, W.; Boonen, R.; Sas, P.; Moens, D.

    2012-05-01

    Accurate prediction of the lifetime of rolling element bearings is a crucial step towards a reliable design of many rotating machines. Recent research emphasizes an important influence of external dynamic loads on the lifetime of bearings. However, most lifetime calculations of bearings are based on the classical ISO 281 standard, neglecting this influence. For bearings subjected to highly varying loads, this leads to inaccurate estimations of the lifetime, and therefore excessive safety factors during the design and unexpected failures during operation. This paper presents a novel test rig, developed to analyse the behaviour of rolling element bearings subjected to highly varying loads. Since bearings are very precise machine components, their motion can only be measured in an accurately controlled environment. Otherwise, noise from other components and external influences such as temperature variations will dominate the measurements. The test rig is optimised to perform accurate measurements of the bearing behaviour. Also, the test bearing is fitted in a modular structure, which guarantees precise mounting and allows testing different types and sizes of bearings. Finally, a fully controlled multi-axial static and dynamic load is imposed on the bearing, while its behaviour is monitored with capacitive proximity probes.

  11. 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.

  12. THE IMPACT OF ACCURATE EXTINCTION MEASUREMENTS FOR X-RAY SPECTRAL MODELS

    SciTech Connect

    Smith, Randall K.; Valencic, Lynne A.; Corrales, Lia

    2016-02-20

    Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources, and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure that the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.

  13. 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.

  14. Spontaneous fluctuation indices of the cardiovagal baroreflex accurately measure the baroreflex sensitivity at the operating point during upright tilt.

    PubMed

    Schwartz, Christopher E; Medow, Marvin S; Messer, Zachary; Stewart, Julian M

    2013-06-15

    Spontaneous fluctuation indices of cardiovagal baroreflex have been suggested to be inaccurate measures of baroreflex function during orthostatic stress compared with alternate open-loop methods (e.g. neck pressure/suction, modified Oxford method). We therefore tested the hypothesis that spontaneous fluctuation measurements accurately reflect local baroreflex gain (slope) at the operating point measured by the modified Oxford method, and that apparent differences between these two techniques during orthostasis can be explained by a resetting of the baroreflex function curve. We computed the sigmoidal baroreflex function curves supine and during 70° tilt in 12 young, healthy individuals. With the use of the modified Oxford method, slopes (gains) of supine and upright curves were computed at their maxima (Gmax) and operating points. These were compared with measurements of spontaneous indices in both positions. Supine spontaneous analyses of operating point slope were similar to calculated Gmax of the modified Oxford curve. In contrast, upright operating point was distant from the centering point of the reset curve and fell on the nonlinear portion of the curve. Whereas spontaneous fluctuation measurements were commensurate with the calculated slope of the upright modified Oxford curve at the operating point, they were significantly lower than Gmax. In conclusion, spontaneous measurements of cardiovagal baroreflex function accurately estimate the slope near operating points in both supine and upright position.

  15. 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.

  16. 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.

  17. Measuring Accurately Single-Phase Sinusoidal and Non-Sinusoidal Power.

    DTIC Science & Technology

    1983-01-01

    dc source. - 1 T Figure 2.2 Power Measuring Test Set-up Source: Robert L. Boylestad , Introductory Circuit Analysis (Ohio: Charles E. Merrill, 1977) p...Power Waveforms for the General Case. Source: Robert L. Boylestad , Introductory CircuitAnalysis (Ohio: Charles E. Merrill, 1968) p. 309. Note that the...Inductive Circuit Source: Robert L. Boylestad , Introductory Circuit Analysis (Ohio: Charles E. Merrill, 1968) p. 43-. and c) In a1 purely capacitive

  18. 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.

  19. 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.

  20. 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.

  1. A technique for fast and accurate measurement of hand volumes using Archimedes' principle.

    PubMed

    Hughes, S; Lau, J

    2008-03-01

    A new technique for measuring hand volumes using Archimedes principle is described. The technique involves the immersion of a hand in a water container placed on an electronic balance. The volume is given by the change in weight divided by the density of water. This technique was compared with the more conventional technique of immersing an object in a container with an overflow spout and collecting and weighing the volume of overflow water. The hand volume of two subjects was measured. Hand volumes were 494 +/- 6 ml and 312 +/- 7 ml for the immersion method and 476 +/- 14 ml and 302 +/- 8 ml for the overflow method for the two subjects respectively. Using plastic test objects, the mean difference between the actual and measured volume was -0.3% and 2.0% for the immersion and overflow techniques respectively. This study shows that hand volumes can be obtained more quickly than the overflow method. The technique could find an application in clinics where frequent hand volumes are required.

  2. 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.

  3. 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.

  4. Possibility of detecting anisotropic expansion of the universe by very accurate astrometry measurements.

    PubMed

    Quercellini, Claudia; Quartin, Miguel; Amendola, Luca

    2009-04-17

    Refined astrometry measurements allow us to detect large-scale deviations from isotropy through real-time observations of changes in the angular separation between sources at cosmic distances. This "cosmic parallax" effect is a powerful consistency test of the Friedmann-Robertson-Walker metric and may set independent constraints on cosmic anisotropy. We apply this novel general test to Lemaitre-Tolman-Bondi cosmologies with off-center observers and show that future satellite missions such as Gaia might achieve accuracies that would put limits on the off-center distance which are competitive with cosmic microwave background dipole constraints.

  5. 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.

  6. Rapid and accurate measurement of the frequency-frequency correlation function.

    PubMed

    Osborne, Derek G; Kubarych, Kevin J

    2013-07-25

    Using an implementation of heterodyne-detected vibrational echo spectroscopy, we show that equilibrium spectral diffusion caused by solvation dynamics can be measured in a fraction of the time required using traditional two-dimensional infrared spectroscopy. Spectrally resolved, heterodyne-detected rephasing and nonrephasing signals, recorded at a single delay between the first two pulses in a photon echo sequence, can be used to measure the full waiting time dependent spectral dynamics that are typically extracted from a series of 2D-IR spectra. Hence, data acquisition is accelerated by more than 1 order of magnitude, while permitting extremely fine sampling of the spectral dynamics during the waiting time between the second and third pulses. Using cymantrene (cyclopentadienyl manganese tricarbonyl, CpMn(CO)3) in alcohol solutions, we compare this novel approach--denoted rapidly acquired spectral diffusion (RASD)--with a traditional method using full 2D-IR spectra, finding excellent agreement. Though this approach is largely limited to isolated vibrational bands, we also show how to remove interference from cross-peaks that can produce characteristic modulations of the spectral dynamics through vibrational quantum beats.

  7. Non-VKA Oral Anticoagulants: Accurate Measurement of Plasma Drug Concentrations.

    PubMed

    Douxfils, Jonathan; Mani, Helen; Minet, Valentine; Devalet, Bérangère; Chatelain, Bernard; Dogné, Jean-Michel; Mullier, François

    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.

  8. Quantitatively accurate activity measurements with a dedicated cardiac SPECT camera: Physical phantom experiments

    SciTech Connect

    Pourmoghaddas, Amir Wells, R. Glenn

    2016-01-15

    Purpose: Recently, there has been increased interest in dedicated cardiac single photon emission computed tomography (SPECT) scanners with pinhole collimation and improved detector technology due to their improved count sensitivity and resolution over traditional parallel-hole cameras. With traditional cameras, energy-based approaches are often used in the clinic for scatter compensation because they are fast and easily implemented. Some of the cardiac cameras use cadmium-zinc-telluride (CZT) detectors which can complicate the use of energy-based scatter correction (SC) due to the low-energy tail—an increased number of unscattered photons detected with reduced energy. Modified energy-based scatter correction methods can be implemented, but their level of accuracy is unclear. In this study, the authors validated by physical phantom experiments the quantitative accuracy and reproducibility of easily implemented correction techniques applied to {sup 99m}Tc myocardial imaging with a CZT-detector-based gamma camera with multiple heads, each with a single-pinhole collimator. Methods: Activity in the cardiac compartment of an Anthropomorphic Torso phantom (Data Spectrum Corporation) was measured through 15 {sup 99m}Tc-SPECT acquisitions. The ratio of activity concentrations in organ compartments resembled a clinical {sup 99m}Tc-sestamibi scan and was kept consistent across all experiments (1.2:1 heart to liver and 1.5:1 heart to lung). Two background activity levels were considered: no activity (cold) and an activity concentration 1/10th of the heart (hot). A plastic “lesion” was placed inside of the septal wall of the myocardial insert to simulate the presence of a region without tracer uptake and contrast in this lesion was calculated for all images. The true net activity in each compartment was measured with a dose calibrator (CRC-25R, Capintec, Inc.). A 10 min SPECT image was acquired using a dedicated cardiac camera with CZT detectors (Discovery NM530c, GE

  9. 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.

  10. Accurate optical measurement of nuclear polarization in optically pumped ^3He gas

    NASA Astrophysics Data System (ADS)

    Bigelow, N. P.; Nacher, P. J.; Leduc, M.

    1992-12-01

    Large nuclear polarizations M (over 80 %) can now be achieved in gaseous ^3He by optical pumping. The gas is excited by an RF discharge and is oriented using a high power LNA laser which is lamp pumped and tuned to the 2 ^3S-2 ^3P transition at 1.08 μm. In this paper we describe an experiment in which we measure M with high absolute precision. Our method is based on a change as a function of M in the ratio of σ or π polarized light absorbed from a weak probe beam by the 2 ^3S metastable atoms. The probe was delivered by a diode pumped LNA laser and propagated perpendicular to the direction of the magnetization. Simultaneous measurement of M was made by monitoring the degree of circular polarization \\cal{P} of the optical line at 668 nm emitted by the discharge. Our measurements show a linear relationship between M and \\cal{P} for all accessible M values and for a wide range of experimental conditions (sample pressure, magnetic field, RF discharge level, etc.). This provides a second method of measurement of the ^3He nuclear polarization which is simple to operate and is calibrated and is calibrated over a pressure range of 0.15 to 6.5 torr. On peut maintenant produire par pompage optique de fortes polarisations nucléaires M (M supérieure à 80 % dans l' ^3He gazeux. Le gaz est excité par une décharge radiofréquence et orienté à l'aide d'un laser LNA de forte intensité qui est pompé par des lampes et accordé sur la transition 2 ^3S-2 ^3P à 1,08 μm. Dans cet article, nous décrivons une expérience où nous mesurons M avec une grande précision absolue. Notre méthode est fondée sur la variation en fonction de M de l'absorption par les atomes métastables d'un faisceau sonde de faible intensité polarisé linéairement. Nous mesurons le rapport des absorptions pour des polarisations π et σ. Le faisceau sonde est un laser LNA pompé par diode qui se propage perpendiculairement à la direction de l'aimantation. Simultanément, nous mesurons M par le

  11. Numerical simulation and analysis of accurate blood oxygenation measurement by using optical resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Yu, Tianhao; Li, Qian; Li, Lin; Zhou, Chuanqing

    2016-10-01

    Accuracy of photoacoustic signal is the crux on measurement of oxygen saturation in functional photoacoustic imaging, which is influenced by factors such as defocus of laser beam, curve shape of large vessels and nonlinear saturation effect of optical absorption in biological tissues. We apply Monte Carlo model to simulate energy deposition in tissues and obtain photoacoustic signals reaching a simulated focused surface detector to investigate corresponding influence of these factors. We also apply compensation on photoacoustic imaging of in vivo cat cerebral cortex blood vessels, in which signals from different lateral positions of vessels are corrected based on simulation results. And this process on photoacoustic images can improve the smoothness and accuracy of oxygen saturation results.

  12. 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.

  13. 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.

  14. Accurate measurement of silver isotopic compositions in geological materials including low Pd/Ag meteorites

    NASA Astrophysics Data System (ADS)

    Woodland, S. J.; Rehkämper, M.; Halliday, A. N.; Lee, D.-C.; Hattendorf, B.; Günther, D.

    2005-04-01

    Very precise silver (Ag) isotopic compositions have been determined for a number of terrestrial rocks, and high and low Pd/Ag meteorites by utilizing multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The meteorites include primitive chondrites, the Group IAB iron meteorites Canyon Diablo and Toluca, and the Group IIIAB iron meteorite Grant. Silver isotopic measurements are primarily of interest because 107Ag was produced by decay of the short-lived radionuclide 107Pd during the formation of the solar system and hence the Pd-Ag chronometer has set constraints on the timing of early planetesimal formation. A 2σ precision of ±0.05‰ can be obtained for analyses of standard solutions when Ag isotopic ratios are normalized to Pd, to correct for instrumental mass discrimination, and to bracketing standards. Caution must be exercised when making Ag isotopic measurements because isotopic artifacts can be generated in the laboratory and during mass spectrometry. The external reproducibility for geological samples based on replicate analyses of rocks is ±0.2‰ (2σ). All chondrites analyzed have similar Ag isotopic compositions that do not differ significantly (>0.3‰) from the 'terrestrial' value of the NIST SRM 978a Ag isotope standard. Hence, they show no evidence of excess 107Ag derived from 107Pd decay or, of stable Ag isotope fractionation associated with volatile element depletion within the accretion disk or from parent body metamorphism. The Group IAB iron meteorite samples analyzed show evidence of complex behavior and disturbance of Ag isotope systematics. Therefore, care must be taken when using this group of iron meteorites to obtain chronological information based on the Pd-Ag decay scheme.

  15. 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.

  16. Measurements of accurate x-ray scattering data of protein solutions using small stationary sample cells

    NASA Astrophysics Data System (ADS)

    Hong, Xinguo; Hao, Quan

    2009-01-01

    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 °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.

  17. 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.

  18. Total cross sections for positrons scattered elastically from helium based on new measurements of total ionization cross sections

    NASA Technical Reports Server (NTRS)

    Diana, L. M.; Chaplin, R. L.; Brooks, D. L.; Adams, J. T.; Reyna, L. K.

    1990-01-01

    An improved technique is presented for employing the 2.3m spectrometer to measure total ionization cross sections, Q sub ion, for positrons incident on He. The new ionization cross section agree with the values reported earlier. Estimates are also presented of total elastic scattering cross section, Q sub el, obtained by subtracting from total scattering cross sections, Q sub tot, reported in the literature, the Q sub ion and Q sub Ps (total positronium formation cross sections) and total excitation cross sections, Q sub ex, published by another researcher. The Q sub ion and Q sub el measured with the 3m high resolution time-of-flight spectrometer for 54.9eV positrons are in accord with the results from the 2.3m spectrometer. The ionization cross sections are in fair agreement with theory tending for the most part to be higher, especially at 76.3 and 88.5eV. The elastic cross section agree quite well with theory to the vicinity of 50eV, but at 60eV and above the experimental elastic cross sections climb to and remain at about 0.30 pi a sub o sq while the theoretical values steadily decrease.

  19. S3 HMBC hetero: Spin-State-Selective HMBC for accurate measurement of long-range heteronuclear coupling constants

    NASA Astrophysics Data System (ADS)

    Hoeck, Casper; Gotfredsen, Charlotte H.; Sørensen, Ole W.

    2017-02-01

    A novel method, Spin-State-Selective (S3) HMBC hetero, for accurate measurement of heteronuclear coupling constants is introduced. The method extends the S3 HMBC technique for measurement of homonuclear coupling constants by appending a pulse sequence element that interchanges the polarization in 13C-1H methine pairs. This amounts to converting the spin-state selectivity from 1H spin states to 13C spin states in the spectra of long-range coupled 1H spins, allowing convenient measurement of heteronuclear coupling constants similar to other S3 or E.COSY-type methods. As usual in this type of techniques, the accuracy of coupling constant measurement is independent of the size of the coupling constant of interest. The merits of the new method are demonstrated by application to vinyl acetate, the alkaloid strychnine, and the carbohydrate methyl β-maltoside.

  20. Accurate weak lensing of standard candles. II. Measuring σ8 with supernovae

    NASA Astrophysics Data System (ADS)

    Quartin, Miguel; Marra, Valerio; Amendola, Luca

    2014-01-01

    Soon the number of type Ia supernova (SN) measurements should exceed 100 000. Understanding the effect of weak lensing by matter structures on the supernova brightness will then be more important than ever. Although SN lensing is usually seen as a source of systematic noise, we will show that it can be in fact turned into signal. More precisely, the non-Gaussianity introduced by lensing in the SN Hubble diagram dispersion depends rather sensitively on the amplitude σ8 of the matter power spectrum. By exploiting this relation, we are able to predict constraints on σ8 of 7% (3%) for a catalog of 100 000 (500 000) SNe of average magnitude error 0.12, without having to assume that such intrinsic dispersion and its redshift evolution are known a priori. The intrinsic dispersion has been assumed to be Gaussian; possible intrinsic non-Gaussianities in the data set (due to the SN themselves and/or to other transients) could be potentially dealt with by means of additional nuisance parameters describing higher moments of the intrinsic dispersion distribution function. This method is independent of and complementary to the standard methods based on cosmic microwave background, cosmic shear, or cluster abundance observables.

  1. 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.

  2. Accurate thickness/density measurements of organic light-emitting diodes

    SciTech Connect

    Maree, C.H.; Weller, R.A.; Feldman, L.C.; Pakbaz, K.; Lee, H.W.

    1998-10-01

    We report on the use of Rutherford backscattering spectroscopy for thickness analysis of organic light-emitting diode structures (OLEDs) with subnanometer resolution and a spatial resolution {lt}1thinspmm. A careful study of ion beam induced effects revealed some organic film degradation, but not so severe as to inhibit meaningful measurements. The method is independent of the substrate and is still applicable if the organic film is capped with a metal cathode. Common OLED materials have been the subject of this study: poly(2-methoxy,5-(2{sup {prime}}-ethylhexoxy)-1,4-phenylene-vinylene) (MEH-PPV), N{sup {prime}},N{sup {prime}}-diphenyl-N, N{sup {prime}}-bis(3-methylphenyl)-1,1{sup {prime}} biphenyl-4,4{sup {prime}}-diamine (TPD), and tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}). The densities of thin films of evaporated TPD ({rho}=1.22{plus_minus}0.05thinspg/cm{sup 3}) and Alq{sub 3} ({rho}=1.51{plus_minus}0.03thinspg/cm{sup 3}) have been established. {copyright} {ital 1998 American Institute of Physics.}

  3. Accurate modeling of antennas for radiating short pulses, FDTD analysis and experimental measurements

    NASA Astrophysics Data System (ADS)

    Maloney, James G.; Smith, Glenn S.

    1993-01-01

    Antennas used to radiate short pulses often require different design rules that those that are used to radiate essentially time-harmonic signals. The finite-difference time-domain (FDTD) method is a very flexible numerical approach that can be used to treat a variety of electromagnetic problems in the time domain. It is well suited to the analysis and design of antennas for radiating short pulses; however, several advances had to be made before the method could be applied to this problem. In this paper, we will illustrate the use of the FDTD method with two antennas designed for the radiation of short pulses. The first is a simple, two-dimensional geometry, and open-ended parallel-plate waveguide, while the second is a three-dimensional, rotationally symmetric geometry, a conical monopole fed through an image by a coaxial transmission line. Both antennas are 'optimized' according to given criteria by adjusting geometrical parameters and including resistive loading that varies continuously with position along the antenna. The predicted performance for the conical monopole antenna is compared with experimental measurements; this verifies the optimization and demonstrates the practicality of the design.

  4. 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.

  5. Do anthropometric indices accurately reflect directly measured body composition in men and women with chronic heart failure?

    PubMed

    Oreopoulos, Antigone; Fonarow, Gregg C; Ezekowitz, Justin A; McAlister, Finlay A; Sharma, Arya M; Kalantar-Zadeh, Kamyar; Norris, Colleen M; Johnson, Jeffery A; Padwal, Raj S

    2011-01-01

    How well anthropometric indices such as body mass index (BMI), waist circumference, waist-stature ratio, and waist index correlate with direct measures of body composition (lean body mass, body fat) in men and women with chronic heart failure (CHF) has not been reported. Body composition was assessed by dual-energy x-ray absorptiometry in 140 patients with CHF. Age-adjusted Pearson correlations between each index and measures of body composition for men and women were calculated. Diagnostic accuracy of detecting obesity or high central fat was also examined. In men, all of the anthropometric indices except waist index were just as strongly correlated with lean body mass (correlation coefficients varied between 0.56 for waist-stature ratio to 0.74 for BMI) as with percentage of body fat (correlation coefficients varied between 0.72 for BMI to 0.79 for waist circumference). In women, all 4 anthropometric measures were unable to significantly differentiate between body fat and lean body mass. The positive likelihood ratios for the detection of obesity varied between 2.26 for waist circumference and 3.42 for BMI, waist-stature ratio, and waist index. Anthropometric indices do not accurately reflect body composition in patients with CHF, especially in women. When accurate assessment of body composition is required, direct measurements should be obtained.

  6. A systematic approach for the accurate and rapid measurement of water vapor transmission through ultra-high barrier films

    NASA Astrophysics Data System (ADS)

    Kiese, Sandra; Kücükpinar, Esra; Reinelt, Matthias; Miesbauer, Oliver; Ewender, Johann; Langowski, Horst-Christian

    2017-02-01

    Flexible organic electronic devices are often protected from degradation by encapsulation in multilayered films with very high barrier properties against moisture and oxygen. However, metrology must be improved to detect such low quantities of permeants. We therefore developed a modified ultra-low permeation measurement device based on a constant-flow carrier-gas system to measure both the transient and stationary water vapor permeation through high-performance barrier films. The accumulation of permeated water vapor before its transport to the detector allows the measurement of very low water vapor transmission rates (WVTRs) down to 2 × 10-5 g m-2 d-1. The measurement cells are stored in a temperature-controlled chamber, allowing WVTR measurements within the temperature range 23-80 °C. Differences in relative humidity can be controlled within the range 15%-90%. The WVTR values determined using the novel measurement device agree with those measured using a commercially available carrier-gas device from MOCON®. Depending on the structure and quality of the barrier film, it may take a long time for the WVTR to reach a steady-state value. However, by using a combination of the time-dependent measurement and the finite element method, we were able to estimate the steady-state WVTR accurately with significantly shorter measurement times.

  7. 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).

  8. Measurements of Nitrogen Dioxide Total Column Amounts using a Brewer Double Spectrophotometer in Direct Sun Mode

    NASA Technical Reports Server (NTRS)

    Cede, Alexander; Herman, Jay; Richter, Andreas; Krotkov, Nickolay; Burrows, John

    2006-01-01

    NO2 column amounts were measured for the past 2 years at Goddard Space Flight Center, Greenbelt, Maryland, using a Brewer spectrometer in direct Sun mode. A new bootstrap method to calibrate the instrument is introduced and described. This technique selects the cleanest days from the database to obtain the solar reference spectrum. The main advantage for direct Sun measurements is that the conversion uncertainty from slant column to vertical column is negligible compared to the standard scattered light observations where it is typically on the order of 100% (2sigma) at polluted sites. The total 2sigma errors of the direct Sun retrieved column amounts decrease with solar zenith angle and are estimated at 0.2 to 0.6 Dobson units (DU, 1 DU approx. equal to 2.7 10(exp 16) molecules cm(exp -2)), which is more accurate than scattered light measurements for high NO2 amounts. Measured NO2 column amounts, ranging from 0 to 3 DU with a mean of 0.7 DU, show a pronounced daily course and a strong variability from day to day. The NO2 concentration typically increases from sunrise to noon. In the afternoon it decreases in summer and stays constant in winter. As expected from the anthropogenic nature of its source, NO2 amounts on weekends are significantly reduced. The measurements were compared to satellite retrievals from Scanning Image Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). Satellite data give the same average NO2 column and show a seasonal cycle that is similar to the ground data in the afternoon. We show that NO2 must be considered when retrieving aerosol absorption properties, especially for situations with low aerosol optical depth.

  9. Accurate measurement of dispersion data through short and narrow tubes used in very high-pressure liquid chromatography.

    PubMed

    Gritti, Fabrice; McDonald, Thomas; Gilar, Martin

    2015-09-04

    An original method is proposed for the accurate and reproducible measurement of the time-based dispersion properties of short L< 50cm and narrow rc< 50μm tubes at mobile phase flow rates typically used in very high-pressure liquid chromatography (vHPLC). Such tubes are used to minimize sample dispersion in vHPLC; however, their dispersion characteristics cannot be accurately measured at such flow rates due to system dispersion contribution of vHPLC injector and detector. It is shown that using longer and wider tubes (>10μL) enables a reliable measurement of the dispersion data. We confirmed that the dimensionless plot of the reduced dispersion coefficient versus the reduced linear velocity (Peclet number) depends on the aspect ratio, L/rc, of the tube, and unexpectedly also on the diffusion coefficient of the analyte. This dimensionless plot could be easily obtained for a large volume tube, which has the same aspect ratio as that of the short and narrow tube, and for the same diffusion coefficient. The dispersion data for the small volume tube are then directly extrapolated from this plot. For instance, it is found that the maximum volume variances of 75μm×30.5cm and 100μm×30.5cm prototype finger-tightened connecting tubes are 0.10 and 0.30μL(2), respectively, with an accuracy of a few percent and a precision smaller than seven percent.

  10. Compensation method for obtaining accurate, sub-micrometer displacement measurements of immersed specimens using electronic speckle interferometry.

    PubMed

    Fazio, Massimo A; Bruno, Luigi; Reynaud, Juan F; Poggialini, Andrea; Downs, J Crawford

    2012-03-01

    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.

  11. Accurate measurement of optical properties of narrow leaves and conifer needles with a typical integrating sphere and spectroradiometer.

    PubMed

    Noda, Hibiki M; Motohka, Takeshi; Murakami, Kazutaka; Muraoka, Hiroyuki; Nasahara, Kenlo Nishida

    2013-10-01

    Accurate information on the optical properties (reflectance and transmittance spectra) of single leaves is important for an ecophysiological understanding of light use by leaves, radiative transfer models and remote sensing of terrestrial ecosystems. In general, leaf optical properties are measured with an integrating sphere and a spectroradiometer. However, this method is usually difficult to use with grass leaves and conifer needles because they are too narrow to cover the sample port of a typical integrating sphere. Although ways to measure the optical properties of narrow leaves have been suggested, they have problems. We propose a new measurement protocol and calculation algorithms. The protocol does not damage sample leaves and is valid for various types of leaves, including green and senescent. We tested our technique with leaves of Aucuba japonica, an evergreen broadleaved shrub, and compared the spectral data of whole leaves and narrow strips of the leaves. The reflectance and transmittance of the strips matched those of the whole leaves, indicating that our technique can accurately estimate the optical properties of narrow leaves. Tests of conifer needles confirmed the applicability.

  12. Accurately measuring 'green' credentials.

    PubMed

    Túnica, José; Planas, Carla; Clemente, Raquel

    2013-08-01

    In a slightly adapted version of article first published in the IFHE (International Federation of Hospital Engineering) Digest 2012, José Túnica, managing director, Carla Planas, BREEAM assessor, and Raquel Clemente, LEED AP BREEAM assessor, at Spanish independent engineering firm, JG Ingenieros, examine the impact on the design of hospitals and other healthcare buildings of some of the key environmental assessment schemes now in use internationally.

  13. 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.

  14. Development of a Ground-Based Differential Absorption Lidar for High Accurate Measurements of Vertical CO2 Concentration Profiles

    NASA Astrophysics Data System (ADS)

    Nagasawa, Chikao; Abo, Makoto; Shibata, Yasukuni; Nagai, Tomohiro; Nakazato, Masahisa; Sakai, Tetsu; Tsukamoto, Makoto; Sakaizawa, Daisuku

    2010-05-01

    High-accurate vertical carbon dioxide (CO2) profiles are highly desirable in the inverse method to improve quantification and understanding of the global sink and source of CO2, and also global climate change. We have developed a ground based 1.6μm differential absorption lidar (DIAL) to achieve high accurate measurements of vertical CO2 profiles in the atmosphere. The DIAL system is constructed from the optical parametric oscillation(OPO) transmitter and the direct detection receiving system that included a near-infrared photomultiplier tube operating at photon counting mode. The primitive DIAL measurement was achieved successfully the vertical CO2 profile up to 7 km altitude with an error less than 1.0 % by integration time of 50 minutes and vertical resolution of 150m. We are developing the next generation 1.6 μm DIAL that can measure simultaneously the vertical CO2 concentration, temperature and pressure profiles in the atmosphere. The output laser of the OPO is 20mJ at a 500 Hz repetition rate and a 600mm diameter telescope is employed for this measurement. A very narrow interference filter (0.5nm FWHM) is used for daytime measurement. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement may be realized. Moreover, the value of the retrieved CO2 concentration will be improved remarkably by processing the iteration assignment of CO2 concentration, temperature and pressure, which measured by DIAL techniques. This work was financially supported by the Japan EOS Promotion Program by the MEXT Japan and System Development Program for Advanced Measurement and Analysis by the JST. Reference D. Sakaizawa, C. Nagasawa, T. Nagai, M. Abo, Y. Shibata, H. Nagai, M. Nakazato, and T. Sakai, Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and

  15. Urinary C-peptide measurements in patients receiving continuous and cyclic total parenteral nutrition.

    PubMed

    Wood, R J; Bengoa, J M; Rosenberg, I H

    1985-02-01

    Urinary C-peptide excretion has been found to be an accurate index of insulin secretion under a variety of physiologic conditions, such as acute starvation and exercise, and after oral and intravenous glucose administration. We investigated urinary C-peptide responses in a group of patients who were receiving all of their nutrient intake by intravenous administration. In these patients receiving total parenteral nutrition (TPN), we were able to monitor changes in insulin secretion when the same nutrients were infused at different rates, for example, during cyclic vs. continuous TPN administration, and to observe changes in the insulin secretory response as the pattern of nutrient delivery was altered in the same individual. We found that increasing the TPN infusion rate by 50% during cyclic TPN caused a 65% increase in serum insulin levels over levels observed during continuous TPN administration (93 vs. 60 microU/ml), whereas a 100% increase in the cyclic TPN infusion rate above the continuous TPN rate increased insulin levels by 147% (147 vs. 60 microU/ml). The molar ratio of insulin to C-peptide was increased by increasing rates of TPN infusion, from 0.116 during fasting periods to 0.151 during maximum rates of TPN administration. An additional finding of this study is that 24-hour insulin secretion, estimated by urinary C-peptide measurements, was equivalent in all treatments regardless of the pattern of insulin response elicited.

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

    PubMed Central

    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

  17. Accurate human limb angle measurement: sensor fusion through Kalman, least mean squares and recursive least-squares adaptive filtering

    NASA Astrophysics Data System (ADS)

    Olivares, A.; Górriz, J. M.; Ramírez, J.; Olivares, G.

    2011-02-01

    Inertial sensors are widely used in human body motion monitoring systems since they permit us to determine the position of the subject's limbs. Limb angle measurement is carried out through the integration of the angular velocity measured by a rate sensor and the decomposition of the components of static gravity acceleration measured by an accelerometer. Different factors derived from the sensors' nature, such as the angle random walk and dynamic bias, lead to erroneous measurements. Dynamic bias effects can be reduced through the use of adaptive filtering based on sensor fusion concepts. Most existing published works use a Kalman filtering sensor fusion approach. Our aim is to perform a comparative study among different adaptive filters. Several least mean squares (LMS), recursive least squares (RLS) and Kalman filtering variations are tested for the purpose of finding the best method leading to a more accurate and robust limb angle measurement. A new angle wander compensation sensor fusion approach based on LMS and RLS filters has been developed.

  18. Accurate quantification of total chromium and its speciation form Cr(VI) in water by ICP-DRC-IDMS and HPLC/ICP-DRC-IDMS.

    PubMed

    Markiewicz, Barbara; Komorowicz, Izabela; Barałkiewicz, Danuta

    2016-05-15

    Two analytical procedures have been developed for the determination of total chromium (TCr) and its highly toxic species, i.e. Cr(VI) in water samples using the following methods: inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (ICP-DRC-IDMS) and high performance liquid chromatography inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (HPLC/ICP-DRC-IDMS). Spectral interferences, predominantly occurring in chromium determination, were removed using a dynamic reaction cell (DRC). The presented procedures facilitate the quantification of trace amounts - below 1 µg L(-1) of TCr and individual Cr species - in various water matrices including drinking water and still bottled water with different mineral composition. Special attention has been paid to the adequate preparation of isotopically enriched (53)Cr(VI) standard solution in order to avoid artifacts in chromium speciation. Both procedures were fully validated as well as establishing the traceability and estimation of the uncertainty of measurement were carried out. Application of all of the above mentioned elements and of the isotope dilution technique, which provides the highest quality of metrological traceability, allowed to obtain reliable and high quality results of chromium determination in water samples. Additionally, the comparison of two methods: HPLC/ICP-DRC-MS and HPLC/ICP-DRC-IDMS for Cr(VI) determination, was submitted basing on the validation parameters. As a result, the lower values for these parameters were obtained using the second method.

  19. Method for measuring tetraethyl lead and total lead in organic solvents

    SciTech Connect

    Ouyang, Y.; Mansell, R.S.; Ou, L.T. )

    1994-05-01

    Lead (Pb) contamination is a nationwide public health problem which is prevalent among children in urban metropolitan areas. The source of Pb contamination is due mostly to emissions from vehicular traffic using leaded gasoline. Pb alkyl species used by automobile-related industries include tetraethyl Pb (TEL), tetramethyl Pb, triethylmethyl Pb, dimethyldiethyl Pb, and trimethylethyl Pb compounds. All of these compounds have been used as antiknock agents and have provided a convenient and inexpensive means to enhance octane rating for gasoline. Use of leaded gasoline was almost global for more than 50 years during 1925 to 1975. The amount of Pb released in automobile exhaust during that time accounted for more than a half of the total yearly Pb pollution of the entire earth. Although only Pb-free gasoline may now be used as an automobile fuel in the US, leaded gasoline is still used as both an aviation and automobile fuel in many other countries. Extensive use of Pb antiknock additives has made Pb perhaps the most widely distributed toxic heavy metal in the urban environment. The public health concern about Pb content in the subsurface environment requires a method to determine Pb contents that is both accurate and not demanding of time, technique, or special equipments. The currently used American Society for Testing Materials (ASTM) Standard Method D3237 is time consuming, expensive, and tedious as compared to the method presented in this article. The objective of this study was to develop a simple method to measure TEL as well as total Pb contents in organic solvents using a ICI digestion method. Two types of samples were used: (1) TEL in gasoline, and (2) TEL in hexane. In additional, an experiment was also conducted to verify that conversion of TEL by ICI with the above procedures is actually to inorganic Pb[sup +2] and not to a mixture of the intermediate TREL and DEL species which are highly water soluble.

  20. Development of Ground-Based DIAL Techniques for High Accurate Measurements of CO2 Concentration Profiles in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Nagasawa, C.; Abo, M.; Shibata, Y.; Nagai, T.; Nakazato, M.; Sakai, T.; Tsukamoto, M.; Sakaizawa, D.

    2009-12-01

    High-accurate vertical carbon dioxide (CO2) profiles are highly desirable in the inverse method to improve quantification and understanding of the global sink and source of CO2, and also global climate change. We have developed a ground based 1.6μm differential absorption lidar (DIAL) to achieve high accurate measurements of vertical CO2 profiles in the atmosphere. The DIAL system is constructed from the optical parametric oscillation(OPO) transmitter and the direct detection receiving system that included a near-infrared photomultiplier tube operating at photon counting mode (Fig.1). The primitive DIAL measurement was achieved successfully the vertical CO2 profile up to 7 km altitude with an error less than 1.0 % by integration time of 50 minutes and vertical resolution of 150m. We develop the next generation 1.6 μm DIAL that can measure simultaneously the vertical CO2 concentration, temperature and pressure profiles in the atmosphere. The characteristics of the 1.6 μm DIALs of the primitive and next generations are shown in Table 1. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement may be realized. Moreover, the value of the retrieved CO2 concentration will be improved remarkably by processing the iteration assignment of CO2 concentration, temperature and pressure which measured by DIAL techniques. This work was financially supported by the Japan EOS Promotion Program by the MEXT Japan and System Development Program for Advanced Measurement and Analysis by the JST. Reference D. Sakaisawa et al., Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile, Applied Optics, Vol.48, No.4, pp.748-757, 2009. Fig. 1 Experimental setup of the 1.6 μm CO2 DIAL. Comparison of primitive

  1. 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.

  2. 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

  3. 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.

  4. Chamber for indirect calorimetry with accurate measurement and time discrimination of metabolic plateaus of over 20 min.

    PubMed

    Nguyen, T; de Jonge, L; Smith, S R; Bray, G A

    2003-09-01

    A robust algorithm for pull-calorimeters that provides a rapid response to changes in respiratory gas exchange has been implemented. Metabolic plateaus (over 20 min), such as that generated by steady treadmill exercise, can be measured accurately (< 2.0% error for an energy expenditure level of 16.7 kJ min(-1)). The time resolution for changes between plateaus can be accurately found with 1 min discrimination. Implementation required only software changes but no structural or instrumentation changes to the chamber. The algorithm was based on the one developed for the push-calorimeter at the Sahlgrenska Hospital in Sweden. The method utilises published equations for the rate of O2 consumption and CO2 production in the chamber, along with techniques for suppressing noise and identifying trends. Using the exact solution of the equations for steady state, the O2 concentrations from the preceding 30 min period are fitted to two connected exponential segments, of variable length, using the least-squares method. The smoothed O2 concentration and associated time derivative are then determined for the time point 15 min earlier and substituted into the respiration equations. The CO2 concentrations are subjected to the same analysis. The process is repeated every minute, and the newly computed rates of O2 consumption and CO2 production, as well as metabolic rate, are then presented. Gas injection tests proved that the chamber can respond instantaneously to a change from one steady state of respiration to another and correctly averages repeated changes in respiration with periods less than 15min (< 1.4% error for simulated, alternating O2 consumption levels of 0.81 min (-1) and 0.01 min). The successful integration of the algorithm into the Pennington chambers allows for traditional 24 h energy expenditure measurements and various metabolic experiments requiring rapid responses.

  5. How accurate are antenatal weight measurements? A survey of hospital and community clinics in a South Thames Region NHS Trust.

    PubMed

    Harris, H E; Ellison, G T; Holliday, M; Nickson, C

    1998-04-01

    The accuracy of antenatal weight data recorded in obstetric notes was investigated in the 45 hospital and community antenatal clinics within a South Thames Region NHS Trust. In order to assess the reliability and validity of all 60 clinic scales triplicate measurements of body weight for low- and high-weight subjects were recorded on each clinical scale and on a calibrated standard scale. The quality of weighing practice during antenatal care was investigated by means of semi-structured interviews conducted with all 33 midwives who currently provide antenatal care within the Trust. Beam balances had the highest reliability and validity, whereas scales with spring mechanisms were the least accurate. Only 40% of the clinics surveyed had access to beam balances, yet most of the maternal weight measurements recorded during antenatal care are likely to be out by no more than 1-1.5% of body weight. Weighing practice was generally inconsistent, and serial measurements of maternal body weight collected during pregnancy are probably too imprecise to provide a sensitive screen for conditions associated with unusual weight gain and too inaccurate to assess compliance with guidelines for weight gain.

  6. Accurate Measurements of Multiple-Bond 13C- 1H Coupling Constants from Phase-Sensitive 2D INEPT Spectra

    NASA Astrophysics Data System (ADS)

    Ding, Keyang

    1999-10-01

    Measurements of multiple-bond 13C-1H coupling constants are of great interest for the assignment of nonprotonated 13C resonances and the elucidation of molecular conformation in solution. Usually, the heteronuclear multiple-bond coupling constants were measured either by the JCH splittings mostly in selective 2D spectra or in 3D spectra, which are time consuming, or by the cross peak intensity analysis in 2D quantitative heteronuclear J correlation spectra (1994, G. Zhu, A. Renwick, and A. Bax, J. Magn. Reson. A 110, 257; 1994, A. Bax, G. W. Vuister, S. Grzesiek, F. Delaglio, A. C. Wang, R. Tschudin, and G. Zhu, Methods Enzymol. 239, 79.), which suffer from the accuracy problem caused by the signal-to-noise ratio and the nonpure absorptive peak patterns. Concerted incrementation of the duration for developing proton antiphase magnetization with respect to carbon-13 and the evolution time for proton chemical shift in different steps in a modified INEPT pulse sequence provides a new method for accurate measurements of heteronuclear multiple-bond coupling constants in a single 2D experiment.

  7. Inference of total DT fusion neutron yield from prompt gamma-ray measurements at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Church, J. A.; Herrmann, H. W.; Stoeffl, W.; Caggiano, J. A.; Cerjan, C.; Sayre, D.

    2014-10-01

    Prompt D-T fusion gamma-rays measured at the National Ignition Facility (NIF) with the Gamma-ray Reaction History detector (GRH) have been used recently to infer the total DT fusion neutron yield of inertial confinement fusion (ICF) implosions. DT fusion produces energetic gamma-rays (16.75 MeV) with a small branching ratio of approximately (4.2 +/- 2.0)e-5 γ/n. While the large error bar precludes use of the branching ratio for an accurate yield determination, the gamma-rays themselves provide the most unperturbed measure of fusion burn and can be used for such a purpose. A cross-calibration for the DT fusion gamma-ray to neutron signal is obtained via low areal density exploding pusher implosions which have mostly unperturbed neutron and gamma-ray signals. The calibration is then used to infer total DT neutron yield from gamma-ray measurements on high areal-density, cryogenically layered implosions in which neutrons are heavily down-scattered (up to 30%). Furthermore, the difference between the gamma-ray inferred total DT yield and the primary neutron yield (unscattered neutrons) can be used to estimate the total down-scatter fraction. Error analysis and comparison of yield values will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, LLNL-ABS-657694.

  8. 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

  9. 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.

  10. 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.

  11. Optimally accurate thermal-wave cavity photopyroelectric measurements of pressure-dependent thermophysical properties of air: theory and experiments.

    PubMed

    Kwan, Chi-Hang; Matvienko, Anna; Mandelis, Andreas

    2007-10-01

    An experimental technique for the measurement of thermal properties of air at low pressures using a photopyroelectric (PPE) thermal-wave cavity (TWC) was developed. In addition, two theoretical approaches, a conventional one-dimensional thermal-wave model and a three-dimensional theory based on the Hankel integral, were applied to interpret the thermal-wave field in the thermal-wave cavity. The importance of radiation heat transfer mechanisms in a TWC was also investigated. Radiation components were added to the purely conductive model by linearizing the radiation heat transfer component at the cavity boundary. The experimental results indicate that the three-dimensional model is necessary to describe the PPE signal, especially at low frequencies where thermal diffusion length is large and sideways propagation of the thermal-wave field becomes significant. Radiation is found to be the dominant contributor of the PPE signal at high frequencies and large cavity lengths, where heat conduction across the TWC length is relatively weak. The three-dimensional theory and the Downhill Simplex algorithm were used to fit the experimental data and extract the thermal diffusivity of air and the heat transfer coefficient in a wide range of pressures from 760 to 2.6 Torr. It was shown that judicious adjustments of cavity length and computational best fits to frequency-scanned data using three-dimensional photopyroelectric theory lead to optimally accurate value measurements of thermal diffusivity and heat transfer coefficient at various pressures.

  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; 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.

  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

    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.

  14. A modified ELISA accurately measures secretion of high molecular weight hyaluronan (HA) by Graves' disease orbital cells.

    PubMed

    Krieger, Christine C; Gershengorn, Marvin C

    2014-02-01

    Excess production of hyaluronan (hyaluronic acid [HA]) in the retro-orbital space is a major component of Graves' ophthalmopathy, and regulation of HA production by orbital cells is a major research area. In most previous studies, HA was measured by ELISAs that used HA-binding proteins for detection and rooster comb HA as standards. We show that the binding efficiency of HA-binding protein in the ELISA is a function of HA polymer size. Using gel electrophoresis, we show that HA secreted from orbital cells is primarily comprised of polymers more than 500 000. We modified a commercially available ELISA by using 1 million molecular weight HA as standard to accurately measure HA of this size. We demonstrated that IL-1β-stimulated HA secretion is at least 2-fold greater than previously reported, and activation of the TSH receptor by an activating antibody M22 from a patient with Graves' disease led to more than 3-fold increase in HA production in both fibroblasts/preadipocytes and adipocytes. These effects were not consistently detected with the commercial ELISA using rooster comb HA as standard and suggest that fibroblasts/preadipocytes may play a more prominent role in HA remodeling in Graves' ophthalmopathy than previously appreciated.

  15. 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.

  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

    2003-11-01

    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.

  17. 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.

  18. Development of an accurate EPID-based output measurement and dosimetric verification tool for electron beam therapy

    PubMed Central

    Ding, Aiping; Xing, Lei; Han, Bin

    2015-01-01

    chamber measurements. The average discrepancy between EPID and ion chamber/film measurements was 0.81% ± 0.60% (SD) and 1.34% ± 0.75%, respectively. For the three clinical cases, the difference in output between the EPID- and ion chamber array measured values was found to be 1.13% ± 0.11%, 0.54% ± 0.10%, and 0.74% ± 0.11%, respectively. Furthermore, the γ-index analysis showed an excellent agreement between the EPID- and ion chamber array measured dose distributions: 100% of the pixels passed the criteria of 3%/3 mm. When the γ-index was set to be 2%/2 mm, the pass rate was found to be 99.0% ± 0.07%, 98.2% ± 0.14%, and 100% for the three cases. Conclusions: The EPID dosimetry system developed in this work provides an accurate and reliable tool for routine output measurement and dosimetric verification of electron beam therapy. Coupled with its portability and ease of use, the proposed system promises to replace the current film-based approach for fast and reliable assessment of small and irregular electron field dosimetry. PMID:26133618

  19. FDG-PET measurement is more accurate than neuropsychological assessments to predict global cognitive deterioration in patients with mild cognitive impairment.

    PubMed

    Chételat, Gaël; Eustache, Francis; Viader, Fausto; De La Sayette, Vincent; Pélerin, Alice; Mézenge, Florence; Hannequin, Didier; Dupuy, Benoît; Baron, Jean-Claude; Desgranges, Béatrice

    2005-02-01

    The accurate prediction, at a pre-dementia stage of Alzheimer's disease (AD), of the subsequent clinical evolution of patients would be a major breakthrough from both therapeutic and research standpoints. Amnestic mild cognitive impairment (MCI) is presently the most common reference to address the pre-dementia stage of AD. However, previous longitudinal studies on patients with MCI assessing neuropsychological and PET markers of future conversion to AD are sparse and yield discrepant findings, while a comprehensive comparison of the relative accuracy of these two categories of measure is still lacking. In the present study, we assessed the global cognitive decline as measured by the Mattis scale in 18 patients with amnestic MCI over an 18-month follow-up period, studying which subtest of this scale showed significant deterioration over time. Using baseline measurements from neuropsychological evaluation of memory and PET, we then assessed significant markers of global cognitive change, that is, percent annual change in the Mattis scale total score, and searched for the best predictor of this global cognitive decline. Altogether, our results revealed significant decline over the 18-month follow-up period in the total score and the verbal initiation and memory-recall subscores of the Mattis scale. The percent annual change in the total Mattis score significantly correlated with age and baseline performances in delayed episodic memory recall as well as semantic autobiographical and category word fluencies. Regarding functional imaging, significant correlations were also found with baseline PET values in the right temporo-parietal and medial frontal areas. Age and right temporo-parietal PET values were the most significant predictors of subsequent global cognitive decline, and the only ones to survive stepwise regression analyses. Our findings are consistent with previous works showing predominant delayed recall and semantic memory impairment at a pre-dementia stage

  20. A comparison between patient recall and concurrent measurement of preoperative quality of life outcome in total hip arthroplasty.

    PubMed

    Howell, Jonathan; Xu, Min; Duncan, Clive P; Masri, Bassam A; Garbuz, Donald S

    2008-09-01

    The objective is to evaluate the reliability of patients' recall of preoperative pain and function during the immediate postoperation period after total hip arthroplasty. A prospective cohort of 104 patients completed a survey about their quality of life before operation, and recalled preoperative status at 3 days, 6 weeks, and 12 weeks after operation. Quality of life was measured by the Western Ontario and McMaster University Osteoarthritis Index, the Oxford-12 hip score, and the 12-item Short-Form score. The intraclass correlation coefficient and Spearman correlation coefficient were used to compare preoperative quality of life scores to the scores recalled. The reliability of recall remained high up to 3 months postoperation. Patients are able to accurately recall their preoperative function for up to 3 months after total hip arthroplasty.

  1. 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

  2. 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

    2016-07-19

    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.

  3. HDO and H2O total column retrievals from TROPOMI shortwave infrared measurements

    NASA Astrophysics Data System (ADS)

    Scheepmaker, Remco A.; aan de Brugh, Joost; Hu, Haili; Borsdorff, Tobias; Frankenberg, Christian; Risi, Camille; Hasekamp, Otto; Aben, Ilse; Landgraf, Jochen

    2016-08-01

    The TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor mission is scheduled for launch in the last quarter of 2016. As part of its operational processing the mission will provide CH4 and CO total columns using backscattered sunlight in the shortwave infrared band (2.3 µm). By adapting the CO retrieval algorithm, we have developed a non-scattering algorithm to retrieve total column HDO and H2O from the same measurements under clear-sky conditions. The isotopologue ratio HDO / H2O is a powerful diagnostic in the efforts to improve our understanding of the hydrological cycle and its role in climate change, as it provides an insight into the source and transport history of water vapour, nature's strongest greenhouse gas. Due to the weak reflectivity over water surfaces, we need to restrict the retrieval to cloud-free scenes over land. We exploit a novel 2-band filter technique, using strong vs. weak water or methane absorption bands, to prefilter scenes with medium-to-high-level clouds, cirrus or aerosol and to significantly reduce processing time. Scenes with cloud top heights ≲1 km, very low fractions of high-level clouds or an aerosol layer above a high surface albedo are not filtered out. We use an ensemble of realistic measurement simulations for various conditions to show the efficiency of the cloud filter and to quantify the performance of the retrieval. The single-measurement precision in terms of δD is better than 15-25 ‰ for even the lowest surface albedo (2-4 ‰ for high albedos), while a small bias remains possible of up to ˜ 20 ‰ due to remaining aerosol or up to ˜ 70 ‰ due to remaining cloud contamination. We also present an analysis of the sensitivity towards prior assumptions, which shows that the retrieval has a small but significant sensitivity to the a priori assumption of the atmospheric trace gas profiles. Averaging multiple measurements over time and space, however, will reduce these

  4. High-precision topography measurement through accurate in-focus plane detection with hybrid digital holographic microscope and white light interferometer module.

    PubMed

    Liżewski, Kamil; Tomczewski, Sławomir; Kozacki, Tomasz; Kostencka, Julianna

    2014-04-10

    High-precision topography measurement of micro-objects using interferometric and holographic techniques can be realized provided that the in-focus plane of an imaging system is very accurately determined. Therefore, in this paper we propose an accurate technique for in-focus plane determination, which is based on coherent and incoherent light. The proposed method consists of two major steps. First, a calibration of the imaging system with an amplitude object is performed with a common autofocusing method using coherent illumination, which allows for accurate localization of the in-focus plane position. In the second step, the position of the detected in-focus plane with respect to the imaging system is measured with white light interferometry. The obtained distance is used to accurately adjust a sample with the precision required for the measurement. The experimental validation of the proposed method is given for measurement of high-numerical-aperture microlenses with subwavelength accuracy.

  5. Instrumentation and key elements of the dispersive x-ray absorption spectrometer for accurate measurements (invited) (abstract)

    NASA Astrophysics Data System (ADS)

    Fontaine, A.; Baudelet, F.; Dartyge, E.; Dubuisson, J. M.; Giorgetti, C.; Pizzini, Stefania; Andrault, D.; Farges, F.; Fiquet, G.; Itié, J. P.; Polian, A.; Miguel, A. San; Tolentino, H.

    1995-02-01

    Measurement of very small differences of the total cross section is the current demand for the spectrometers dedicated to time-dependent experiments carried out under various time-ramped parameters. The dispersive optics and more precisely the full x-ray-absorption spectrometer is mechanically movement-free during data collection which can last over 12 h at LURE-DCI to be sensitive to relative change of the absorption of the order of 10-5. In this range, artefacts due to the drift of silicon lattice spacing under temperature change of the crystal, and drifts of the detector position because of liquid-nitrogen evaporation contained in the cryostat, are sources of errors which have been identified and cured or ... by-passed. The accuracy in difference measurements is now of the order of 10-5 for a total cross section measured equal to 1. In term of optics stability a difference signal of 10-4 out of 1 can be generated by an absorption edge shift caused by a 0.05 K drift of the temperature of the silicon crystal at 7 keV. These performances are essential for the measurement of XMCD in the hard-x-ray range. Water cooling of the dynamically bent crystal reduces dramatically the change of the Si temperature. Adequate geometry makes the spatial drift of the position of the photodiode array much less concerning. The focusing efficiency is also a key parameter to push high-pressure x-ray-absorption spectroscopy (55 GPa), and high-temperature XAS (2000 K), and the combination (15 GPa, 800 K). Simple devices, taking advantage of the focusing geometry, have been successfully tested these last two years.

  6. 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

  7. The direct fitting approach for total ozone column retrievals: a sensitivity study on GOME-2/MetOp-A measurements

    NASA Astrophysics Data System (ADS)

    Wassmann, A.; Borsdorff, T.; aan de Brugh, J. M. J.; Hasekamp, O. P.; Aben, I.; Landgraf, J.

    2015-10-01

    We present a sensitivity study of the direct fitting approach to retrieve total ozone columns from the clear sky Global Ozone Monitoring Experiment 2/MetOp-A (GOME-2/MetOp-A) measurements between 325 and 335 nm in the period 2007-2010. The direct fitting of the measurement is based on adjusting the scaling of a reference ozone profile and requires accurate simulation of GOME-2 radiances. In this context, we study the effect of three aspects that introduce forward model errors if not addressed appropriately: (1) the use of a clear sky model atmosphere in the radiative transfer demanding cloud filtering, (2) different approximations of Earth's sphericity to address the influence of the solar zenith angle, and (3) the need of polarization in radiative transfer modeling. We conclude that cloud filtering using the operational GOME-2 FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A band) cloud product, which is part of level 1B data, and the use of pseudo-spherical scalar radiative transfer is fully sufficient for the purpose of this retrieval. A validation with ground-based measurements at 36 stations confirms this showing a global mean bias of -0.1 % with a standard deviation (SD) of 2.7 %. The regularization effect inherent to the profile scaling approach is thoroughly characterized by the total column averaging kernel for each individual retrieval. It characterizes the effect of the particular choice of the ozone profile to be scaled by the inversion and is part of the retrieval product. Two different interpretations of the data product are possible: first, regarding the retrieval product as an estimate of the true column, a direct comparison of the retrieved column with total ozone columns from ground-based measurements can be done. This requires accurate a priori knowledge of the reference ozone profile and the column averaging kernel is not needed. Alternatively, the retrieval product can be interpreted as an effective column defined by the total column

  8. Measurement of the total energy of an isolated system by an internal observer

    SciTech Connect

    Massar, S.; Popescu, S.

    2005-04-01

    We consider the situation in which an observer internal to an isolated system wants to measure the total energy of the isolated system (this includes his own energy, that of the measuring device and clocks used, etc.). We show that he can do this in an arbitrarily short time, as measured by his own clock. This measurement is not subjected to a time-energy uncertainty relation. The properties of such measurements are discussed in detail with particular emphasis on the relation between the duration of the measurement as measured by internal clocks versus external clocks.

  9. 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.

  10. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis.

    PubMed

    Ruiz de Gauna, Sofía; González-Otero, Digna M; Ruiz, Jesus; Gutiérrez, J J; Russell, James K

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

  11. Accurate quantification of creatinine in serum by coupling a measurement standard to extractive electrospray ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    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.

  12. An accurate method to measure alpha-emitting natural radionuclides in atmospheric filters: Application in two NORM industries

    NASA Astrophysics Data System (ADS)

    Lozano, R. L.; Bolívar, J. P.; San Miguel, E. G.; García-Tenorio, R.; Gázquez, M. J.

    2011-12-01

    In this work, an accurate method for the measurement of natural alpha-emitting radionuclides from aerosols collected in air filters is presented and discussed in detail. The knowledge of the levels of several natural alpha-emitting radionuclides (238U, 234U, 232Th, 230Th, 228Th, 226Ra and 210Po) in atmospheric aerosols is essential not only for a better understanding of the several atmospheric processes and changes, but also for a proper evaluation of the potential doses, which can inadvertently be received by the population via inhalation. The proposed method takes into account the presence of intrinsic amounts of these radionuclides in the matrices of the quartz filters used, as well as the possible variation in the humidity of the filters throughout the collection process. In both cases, the corrections necessary in order to redress these levels have been evaluated and parameterized. Furthermore, a detailed study has been performed into the optimisation of the volume of air to be sampled in order to increase the accuracy in the determination of the radionuclides. The method as a whole has been applied for the determination of the activity concentrations of U- and Th-isotopes in aerosols collected at two NORM (Naturally Occurring Radioactive Material) industries located in the southwest of Spain. Based on the levels found, a conservative estimation has been performed to yield the additional committed effective doses to which the workers are potentially susceptible due to inhalation of anthropogenic material present in the environment of these two NORM industries.

  13. A fast experimental beam hardening correction method for accurate bone mineral measurements in 3D μCT imaging system.

    PubMed

    Koubar, Khodor; Bekaert, Virgile; Brasse, David; Laquerriere, Patrice

    2015-06-01

    Bone mineral density plays an important role in the determination of bone strength and fracture risks. Consequently, it is very important to obtain accurate bone mineral density measurements. The microcomputerized tomography system provides 3D information about the architectural properties of bone. Quantitative analysis accuracy is decreased by the presence of artefacts in the reconstructed images, mainly due to beam hardening artefacts (such as cupping artefacts). In this paper, we introduced a new beam hardening correction method based on a postreconstruction technique performed with the use of off-line water and bone linearization curves experimentally calculated aiming to take into account the nonhomogeneity in the scanned animal. In order to evaluate the mass correction rate, calibration line has been carried out to convert the reconstructed linear attenuation coefficient into bone masses. The presented correction method was then applied on a multimaterial cylindrical phantom and on mouse skeleton images. Mass correction rate up to 18% between uncorrected and corrected images were obtained as well as a remarkable improvement of a calculated mouse femur mass has been noticed. Results were also compared to those obtained when using the simple water linearization technique which does not take into account the nonhomogeneity in the object.

  14. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

    PubMed Central

    Gutiérrez, J. J.; Russell, James K.

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces. PMID:27999808

  15. Operation Hardtack. Report to the Scientific Director. Power-time and total-thermal measurements

    SciTech Connect

    Hansen, D.F.; Perry, J.E.; Rockman, A.G.

    1985-09-01

    The objective of the experiments reported in this volume was to determine the very-high-altitude behavior of two nuclear explosions, namely, the thermal power versus time and the total thermal yield. The power-time measurements were performed wth four bolometers chopper units. A large dynamic range was provided both electronically and by neutral filters. The total thermal yield of the Teak Shot was measured by thermopile recorder systems. The total thermal yield for Orange Shot could not be determined because of the cloud cover present over Johnston Island.

  16. Evaluation of the consistency of OMI-TOMS total ozone with collocated ground-based measurements

    NASA Astrophysics Data System (ADS)

    Ma, Mingliang; Shi, Runhe; Bai, Kaixu; Liu, Chaoshun; Gao, Wei; Sun, Zhibin

    2016-09-01

    As Ozone Monitoring Instrument (OMI) onboard the Aura satellite has provided global scale ozone measurements on a daily basis since 2004, the long-term stability and consistency of ozone retrievals is thus of critical importance, especially for the ozone recovery assessment. This study aims to evaluate the long-term stability of total ozone derived from the OMI Total Ozone Mapping Spectrometer (OMI-TOMS) algorithm, by comparing with collocated ground-based total ozone measurements recorded from 42Dobson spectrophotometers during the period 2004-2015. It is indicative that the OMI-TOMS total ozone is in good agreement with collocated ground-based measurements, with a R2 of 0.96 and root mean square error (RMSE) of 3.3%. Further investigations show that the OMI-TOMS total ozone is of quality, as no significant latitude dependence is observed. In the past 12 years, the OMI-TOMS total ozone is highly consistent with the ground-based Dobson total ozone, with a variation of mean relative difference less than 1%. In general, the OMI-TOMS total ozone performs well and can be used with confidence.

  17. Geometric Measure of Quantum Discord for Entanglement of Total Dirac Fields in Noninertial Frames

    NASA Astrophysics Data System (ADS)

    Qiang, Wen-Chao; Zhang, Lei

    2017-04-01

    We study the geometric measure of quantum discord of total Dirac fields in noninertial frames. As a comparison, we also calculate the corresponding geometric measure of entanglement of the same system. We discuss the properties of geometric measure of quantum discord and geometric measure of entanglement for this system with acceleration parameter and the parameter describing the entangle degree of the system in detail. Our results show that from an overall perspective, two geometric measures have similar behavior with the variation of the entangle parameter and the acceleration parameter. We find that this tripartite system is monogamous for the geometric measure of quantum discord.

  18. A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements

    NASA Astrophysics Data System (ADS)

    Chisham, G.; Freeman, M. P.

    2003-04-01

    Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1 2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year’s worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced

  19. Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere

    NASA Astrophysics Data System (ADS)

    Volten, H.; Bergwerff, J. B.; Haaima, M.; Lolkema, D. E.; Berkhout, A. J. C.; van der Hoff, G. R.; Potma, C. J. M.; Wichink Kruit, R. J.; van Pul, W. A. J.; Swart, D. P. J.

    2012-02-01

    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM: the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference-free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 μg m-3, have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 μg m-3 for ammonia for 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day, the (mini)DOAS and AMOR results agree reasonably well, although an offset of the AMOR values compared to the (mini)DOAS results exists. On short time scales, the (mini)DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini)DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.

  20. Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere

    NASA Astrophysics Data System (ADS)

    Volten, H.; Bergwerff, J. B.; Haaima, M.; Lolkema, D. E.; Berkhout, A. J. C.; van der Hoff, G. R.; Potma, C. J. M.; Wichink Kruit, R. J.; van Pul, W. A. J.; Swart, D. P. J.

    2011-08-01

    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM, the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 μg m-3, have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 μg m-3 for ammonia over 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day the (mini)DOAS and AMOR results agree reasonably well, although an offset of the AMOR values compared to the (mini)DOAS results exists. On short time scales the (mini)DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini)DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.

  1. High frequent total station measurements for the monitoring of bridge vibrations

    NASA Astrophysics Data System (ADS)

    Lienhart, Werner; Ehrhart, Matthias; Grick, Magdalena

    2017-03-01

    Robotic total stations (RTS) are frequently used for the measurement of temperature induced bridge deformations or during load testing of bridges. In experimental setups, total stations have also been used for the measurement of dynamic bridge deformations. However, with standard configurations the measurement rate is not constant and on average an update rate of 7-10Hz can be achieved. This is not sufficient for the vibration monitoring of bridges considering their natural frequencies which are also in the same range. In this paper, we present different approaches to overcome these problems. In the first two approaches we demonstrate how the measurement rate to prisms can be increased to 20Hz to determine vertical deformations of bridges. Critical aspects like the measurement resolution of the automated target tracking and the correct sequence of steering commands are discussed. In another approach we demonstrate how vertical bridge vibrations can be measured using an image assisted total station (IATS) and corresponding processing techniques. The advantage of image-based methods is that structural features of a bridge like bolts can be used as targets. Therefore, no expensive prisms have to be mounted and access to the bridge is not required. All approaches are verified by laboratory investigations and their suitability is proven in a field experiment on a 74m long footbridge. In this field experiment the natural frequencies derived from the total station measurements are compared to the results of accelerometer measurements.

  2. Total variation denoising of probability measures using iterated function systems with probabilities

    NASA Astrophysics Data System (ADS)

    La Torre, Davide; Mendivil, Franklin; Vrscay, Edward R.

    2017-01-01

    In this paper we present a total variation denoising problem for probability measures using the set of fixed point probability measures of iterated function systems with probabilities IFSP. By means of the Collage Theorem for contraction mappings, we provide an upper bound for this problem that can be solved by determining a set of probabilities.

  3. Cosmic ray isotope measurements with a new Cerenkov X total energy telescope

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Kish, J. C.; Schrier, D. A.

    1985-01-01

    Measurements of the isotopic composition of cosmic nuclei with Z = 7-20 are reported. These measurements were made with a new version of a Cerenkov x total E telescope. Path length and uniformity corrections are made to all counters to a RMS level 1%. Since the Cerenkov counter is crucial to mass measurements using the C x E technique - special care was taken to optimize the resolution of the 2.4 cm thick Pilot 425 Cerenkov counter. This counter exhibited a beta = 1 muon equivalent LED resolution of 24%, corresponding to a total of 90 p.e. collected at the 1st dynodes of the photomultiplier tubes.

  4. First comparison of simultaneous IRIS, BUV, and ground-based measurements of total ozone

    NASA Technical Reports Server (NTRS)

    Prior, E. J.; Oza, B. J.

    1978-01-01

    In the present paper, the zonally-averaged global distribution of total ozone obtained simultaneously from different measurements are compared with respect to differences in the measured latitudinal and seasonal variations of total ozone. Emphasis is placed on systematic discrepancies that appear to be related to differences in the sensing methodologies or instruments. While the zonal averages of the IRIS and BUV satellite techniques agree quite well at low latitudes, the results are consistently higher for IRIS than for BUV above mid-latitudes in both the Northern and Southern Hemispheres. The BUV and ground-based ultraviolet averages agree better with each other than with infrared IRIS measurements.

  5. Total retinal blood flow measurement by three beam Doppler optical coherence tomography

    PubMed Central

    Haindl, Richard; Trasischker, Wolfgang; Wartak, Andreas; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K.

    2016-01-01

    We present measurements of total retinal blood flow in healthy volunteers using a three beam Doppler optical coherence tomography (D-OCT) technique. This technology has the advantage of a precise determination of the flow vector without the use of any a-priori information on the vessel geometry. Circular D-OCT scans around the optic disc were recorded and venous as well as arterial total blood flow was determined and compared for each subject. The reproducibility of the method was assessed in 6 subjects by repeated measurements. Only small deviations of around 6% between the measurements were found which indicates the high precision of the proposed method. PMID:26977340

  6. Skin mechanics measured in vivo using torsion: a new and accurate model more sensitive to age, sex and moisturizing treatment.

    PubMed

    Salter, D C; McArthur, H C; Crosse, J E; Dickens, A D

    1993-10-01

    Summary Measurements of skin mechanics are required to understand better cracking and flaking of the epidermis and loss of 'elasticity'with age in the dermis. Improvements in torsional testing are described here. The resulting data was fitted to algebraic models, the parameters of which can serve both as a concise description of the responses and as a means of relating them to skin structure and physiology. This investigation looks into the suitability of seven such algebraic models. Five of the models examined here appear to be new. Using the commercially available Dia-Stron DTM Torque Meter with our own software, model parameters were studied as indicators of the effects of age and sex in 41 people, and of skin moisturizing treatments in a further 10 people. The two models in the literature were both found to be substantially less accurate and sensitive representations of experimental data than one of the new models proposed here based on the Weibull distribution. This 'WB model'was consistently the one best able to distinguish differences and detect changes which were statistically significant. The WB model appears to be the most powerful and efficient available. Use of this model makes it possible to demonstrate in vivo a statistically significant mechanical difference between male and pre-menopausal female skin using only one parameter (p= 0.0163, with 18 males and 19 females) and to demonstrate a statistically significant mechanical difference between successive decades of age in female skin using only one parameter (p= 0.0124, n= 24). The two parameters of the model most sensitive to skin structure, function and treatment have been combined to form the axes of a 'Skin condition chart'. Any person can be located on this chart at a point indicating their overall skin condition in mechanical terms and any changes in that condition can be clearly demonstrated by movement across the plot.

  7. The use of visible-channel data from NOAA satellites to measure total ozone amount over Antarctica

    NASA Technical Reports Server (NTRS)

    Boime, Robert D.; Warren, Steven G.; Gruber, Arnold

    1994-01-01

    Accurate, detailed maps of total ozone were not available until the launch of the Total Ozone Mapping Spectrometer (TOMS) in late 1978. However, the Scanning Radiometer (SR), an instrument on board the NOAA series satellites during the 1970s, had a visible channel that overlapped closely with the Chappuis absorption band of ozone. We are investigating whether data from the SR can be used to map Antarctic ozone prior to 1978. The method is being developed with 1980s data from the Advanced Very High Resolution Radiometer (AVHRR), which succeeded the SR on the NOAA polar-orbiting satellites. Visible-derived total ozone maps can then be compared able on the NOAA satellites, which precludes the use of a differential absorption technique to measure ozone. Consequently, our method works exclusively over scenes whose albedos are large and unvarying, i.e. scenes that contain ice sheets and/or uniform cloud-cover. Initial comparisons of time series for October-December 1987 at locations in East Antarctica show that the visible absorption by ozone in measurable and that the technique may be usable for the 1970s, but with much less accuracy than TOMS. This initial test assumes that clouds, snow, and ice all reflect the same percentage of visible light towards the satellite, regardless of satellite position or environmental conditions. This assumption is our greatest source of error. To improve the accuracy of ozone retrievals, realistic anisotropic reflectance factors are needed, which are strongly influenced by cloud and snow surface features.

  8. Introduction to total- and partial-pressure measurements in vacuum systems

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Kern, F. A.

    1989-01-01

    An introduction to the fundamentals of total and partial pressure measurement in the vacuum regime (760 x 10 to the -16th power Torr) is presented. The instrument most often used in scientific fields requiring vacuum measurement are discussed with special emphasis on ionization type gauges and quadrupole mass spectrometers. Some attention is also given to potential errors in measurement as well as calibration techniques.

  9. Total ozone and aerosol optical depths inferred from radiometric measurements in the Chappuis absorption band

    SciTech Connect

    Flittner, D.E.; Herman, B.M.; Thome, K.J.; Simpson, J.M.; Reagan, J.A. )

    1993-04-15

    A second-derivative smoothing technique, commonly used in inversion work, is applied to the problem of inferring total columnar ozone amounts and aerosol optical depths. The application is unique in that the unknowns (i.e., total columnar ozone and aerosol optical depth) may be solved for directly without employing standard inversion methods. It is shown, however, that by employing inversion constraints, better solutions are normally obtained. The current method requires radiometric measurements of total optical depth through the Chappuis ozone band. It assumes no a priori shape for the aerosol optical depth versus wavelength profile and makes no assumptions about the ozone amount. Thus, the method is quite versatile and able to deal with varying total ozone and various aerosol size distributions. The technique is applied first in simulation, then to 119 days of measurements taken in Tucson, Arizona, that are compared to TOMS values for the same dates. The technique is also applied to two measurements taken at Mauna Loa, Hawaii, for which Dobson ozone values are available in addition to the TOMS values, and the results agree to within 15%. It is also shown through simulations that additional information can be obtained from measurements outside the Chappuis band. This approach reduces the bias and spread of the estimates total ozone and is unique in that it uses measurements from both the Chappuis and Huggins absorption bands. 12 refs., 6 figs., 2 tabs.

  10. Continuous refractive index dispersion measurement based on derivative total reflection method

    NASA Astrophysics Data System (ADS)

    Deng, Zhichao; Wang, Jin; Ye, Qing; Sun, Tengqian; Zhou, Wenyuan; Mei, Jianchun; Zhang, Chunping; Tian, Jianguo

    2015-04-01

    Traditionally, continuous refractive index dispersion (CRID) measurement of materials with scattering is hard to realize. In this paper, CRID measurement based on the derivative total reflection method (CRIDM-DTRM) is proposed to measure the CRID of both absorption and scattering materials. It effectively determined the CRID of K9 glass, concentrated milk, and 0.5% methyl red solution in the 400-750 nm range with the spectral resolution of about 0.259 nm. For the first time, CRID of a scattering material is measured. CRIDM-DTRM is a useful technique in the field of RID measurement, especially for biotissues and anomalous dispersion materials.

  11. The characterization of an air pollution episode using satellite total ozone measurements

    NASA Technical Reports Server (NTRS)

    Fishman, Jack; Shipham, Mark C.; Vukovich, Fred M.; Cahoon, Donald R.

    1987-01-01

    A case study is presented which demonstrates that measurements of total ozone from a space-based platform can be used to study a widespread air pollution episode over the southeastern U.S. In particular, the synoptic-scale distribution of surface-level ozone obtained from an independent analysis of ground-based monitoring stations appears to be captured by the synoptic-scale distribution of total ozone, even though about 90 percent of the total ozone is in the stratosphere. Additional analyses of upper air meteorological data, other satellite imagery, and in situ aircraft measurements of ozone likewise support the fact that synoptic-scale variability of tropospheric ozone is primarily responsible for the observed variability in total ozone under certain conditions. The use of the type of analysis discussed in this study may provide an important technique for understanding the global budget of tropospheric ozone.

  12. Characterization of an air pollution episode using satellite total ozone measurements

    SciTech Connect

    Fishman, J.; Vukovich, F.M.; Cahoon, D.R.; Shipham, M.C.

    1987-12-01

    A case study is presented which demonstrates that measurements of total ozone from a space-based platform can be used to study a widespread air pollution episode over the southeastern United States. In particular, the synoptic-scale distribution of surface-level ozone obtained from an independent analysis of ground-based monitoring stations appears to be captured by the synoptic-scale distribution of total ozone, even though approx. =90% of the total ozone is in the stratosphere. Additional analyses of upper air meteorological data, other satellite imagery, and in situ aircraft measurements of ozone likewise support the fact that synoptic-scale variability of tropospheric ozone is primarily responsible for the observed variability in total ozone under certain conditions. The use of the type of analysis discussed in this study may provide an important technique for understanding the global budget of tropospheric ozone.

  13. Ultrahigh mass resolution and accurate mass measurements as a tool to characterize oligomers in secondary organic aerosols.

    PubMed

    Reinhardt, Alain; Emmenegger, Christian; Gerrits, Bertran; Panse, Christian; Dommen, Josef; Baltensperger, Urs; Zenobi, Renato; Kalberer, Markus

    2007-06-01

    Organic aerosols are a major fraction, often more than 50%, of the total atmospheric aerosol mass. The chemical composition of the total organic aerosol mass is poorly understood, although hundreds of compounds have been identified in the literature. High molecular weight compounds have recently gained much attention because this class of compounds potentially represents a major fraction of the unexplained organic aerosol mass. Here we analyze secondary organic aerosols, generated in a smog chamber from alpha-pinene ozonolysis with ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). About 450 compounds are detected in the mass range of m/z 200-700. The mass spectrum is clearly divided into a low molecular weight range (monomer) and a high molecular weight range, where dimers and trimers are distinguishable. Using the Kendrick mass analysis, the elemental composition of about 60% of all peaks could be determined throughout the whole mass range. Most compounds have high O:C ratios between 0.4 and 0.6. Small compounds (i.e., monomers) have a higher maximum O:C ratio than dimers and trimers, suggesting that condensation reactions with, for example, the loss of water are important in the oligomer formation process. A program developed in-house was used to determine exact mass differences between peaks in the monomer, dimer, and trimer mass range to identify potential monomer building blocks, which form the co-oligomers observed in the mass spectrum. A majority of the peaks measured in the low mass region of the spectrum (m/z < 300) is also found in the calculated results. For the first time the elemental composition of the majority of peaks over a wide mass range was determined using advanced data analysis methods for the analysis of ultra-high-resolution MS data. Possible oligomer formation mechanisms in secondary organic aerosols were investigated.

  14. Tropical intercontinental optical measurement network of aerosol, precipitable water and total column ozone

    NASA Technical Reports Server (NTRS)

    Holben, B. N.; Tanre, D.; Reagan, J. A.; Eck, T. F.; Setzer, A.; Kaufman, Y. A.; Vermote, E.; Vassiliou, G. D.; Lavenu, F.

    1992-01-01

    A new generation of automatic sunphotometers is used to systematically monitor clear sky total column aerosol concentration and optical properties, precipitable water and total column ozone diurnally and annually in West Africa and South America. The instruments are designed to measure direct beam sun, solar aureole and sky radiances in nine narrow spectral bands from the UV to the near infrared on an hourly basis. The instrumentation and the algorithms required to reduce the data for subsequent analysis are described.

  15. Continuous measurements of the total ozone content in the full moon period

    NASA Technical Reports Server (NTRS)

    Ishov, Alexander G.

    1994-01-01

    Presented are the experimental data on the total ozone content obtained during continuous measurements (day-night-...-night-day) by Brewer 044 spectrophotometer near the Issyk Kul Lake (42.59N, 77.04W) at 1650 m above the sea level at full moon from 13 to 18 October 1989 under anomalously high transparent atmospheric conditions (the horizontal visibility range exceeded 50 km). At night the total O3 content decreased regularly to about 20 percent of the average daytime values. The minimum values at night were observed in 1-2 hours after the maximum solar dip below the horizon. In the daytime the measurements were carried out from direct Sun, at night - from the Moon. The values of the total ozone content for adjacent measurements from the Sun and from the Moon in the evening as well as in the morning are in good agreement.

  16. Localized hippocampus measures are associated with Alzheimer pathology and cognition independent of total hippocampal volume.

    PubMed

    Carmichael, Owen; Xie, Jing; Fletcher, Evan; Singh, Baljeet; DeCarli, Charles

    2012-06-01

    Hippocampal injury in the Alzheimer's disease (AD) pathological process is region-specific and magnetic resonance imaging (MRI)-based measures of localized hippocampus (HP) atrophy are known to detect region-specific changes associated with clinical AD, but it is unclear whether these measures provide information that is independent of that already provided by measures of total HP volume. Therefore, this study assessed the strength of association between localized HP atrophy measures and AD-related measures including cerebrospinal fluid (CSF) amyloid beta and tau concentrations, and cognitive performance, in statistical models that also included total HP volume as a covariate. A computational technique termed localized components analysis (LoCA) was used to identify 7 independent patterns of HP atrophy among 390 semiautomatically delineated HP from baseline magnetic resonance imaging of participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Among cognitively normal participants, multiple measures of localized HP atrophy were significantly associated with CSF amyloid concentration, while total HP volume was not. In addition, among all participants, localized HP atrophy measures and total HP volume were both independently and additively associated with CSF tau concentration, performance on numerous neuropsychological tests, and discrimination between normal, mild cognitive impairment (MCI), and AD clinical diagnostic groups. Together, these results suggest that regional measures of hippocampal atrophy provided by localized components analysis may be more sensitive than total HP volume to the effects of AD pathology burden among cognitively normal individuals and may provide information about HP regions whose deficits may have especially profound cognitive consequences throughout the AD clinical course.

  17. Measurement of serum total glycerides and free glycerol by high-performance liquid chromatography.

    PubMed

    Li, Hongxia; Dong, Jun; Chen, Wenxiang; Wang, Shu; Guo, Hanbang; Man, Yong; Mo, Peisheng; Li, Jianzhai

    2006-09-01

    Serum levels of total glycerides and free glycerol are important indices of lipid metabolism and cardiovascular disease risk. Convenient enzymatic methods of measurement have been available, but they are susceptible to interference. Situations exist in both research and clinical laboratories in which more specific and precise methods are needed. We developed HPLC methods for the measurement of serum total glycerides and free glycerol. For total glycerides, serum was mixed with an internal standard (1,2,4-butanetriol) and treated with alcoholic sodium hydroxide to hydrolyze glycerides to glycerol. After deproteinization with tungstic acid, the glycerol was benzoylated with an optimized Schotten-Baumann reaction and analyzed by HPLC. For free glycerol, serum was equilibrated with the internal standard and deproteinized with tungstic acid to remove the glycerides. The glycerol was benzoylated and analyzed as for total glycerol. Various factors were investigated, and no significant sources of interference were detected. The total coefficients of variation ranged from 0.7% to 2.0% for total glycerides and from 1.7% to 3.2% for free glycerol. The analytical recoveries ranged from 98.5% to 101.6%. In conclusion, simple and reliable HPLC methods for serum total glycerides and free glycerol have been developed. The methods may also be used for the analyses of glycerol or glycerides in other biological samples.

  18. Implications of (Less) Accurate Mass-Radius-Measurements for the Habitability of Extrasolar Terrestrial Planets: Why Do We Need PLATO?

    NASA Astrophysics Data System (ADS)

    Noack, L.; Wagner, F. W.; Plesa, A.-C.; Höning, D.; Sohl, F.; Breuer, D.; Rauer, H.

    2012-04-01

    Several space missions (CoRoT, Kepler and others) already provided promising candidates for terrestrial exoplanets (i.e. with masses less than about 10 Earth masses) and thereby triggered an exciting new research branch of planetary modelling to investigate the possible habitability of such planets. Earth analogues (low-mass planets with an Earth-like structure and composition) are likely to be found in the near future with new missions such as the proposed M3 mission PLATO. Planets may be more diverse in the universe than they are in the solar system. Our neighbouring planets in the habitable zone are all terrestrial by the means of being differentiated into an iron core, a silicate mantle and a crust. To reliably determine the interior structure of an exoplanet, measurements of mass and radius have to be sufficiently accurate (around +/-2% error allowed for the radius and +/-5% for the mass). An Earth-size planet with an Earth-like mass but an expected error of ~15% in mass for example may have either a Mercury-like, an Earth-like or a Moon-like (i.e. small iron core) structure [1,2]. Even though the atmospheric escape is not strongly influenced by the interior structure, the outgassing of volatiles and the likeliness of plate tectonics and an ongoing carbon-cycle may be very different. Our investigations show, that a planet with a small silicate mantle is less likely to shift into the plate-tectonics regime, cools faster (which may lead to the loss of a magnetic field after a short time) and outgasses less volatiles than a planet with the same mass but a large silicate mantle and small iron core. To be able to address the habitability of exoplanets, space missions such as PLATO, which can lead up to 2% accuracy in radius [3], are extremely important. Moreover, information about the occurrence of different planetary types helps us to better understand the formation of planetary systems and to further constrain the Drake's equation, which gives an estimate of the

  19. Mathematical Relationships Between Two Sets of Laser Anemometer Measurements for Resolving the Total Velocity Vector

    NASA Technical Reports Server (NTRS)

    Owen, Albert K.

    1993-01-01

    The mathematical relations between the measured velocity fields for the same compressor rotor flow field resolved by two fringe type laser anemometers at different observational locations are developed in this report. The relations allow the two sets of velocity measurements to be combined to produce a total velocity vector field for the compressor rotor. This report presents the derivation of the mathematical relations, beginning with the specification of the coordinate systems and the velocity projections in those coordinate systems. The vector projections are then transformed into a common coordinate system. The transformed vector coordinates are then combined to determine the total velocity vector. A numerical example showing the solution procedure is included.

  20. Accurate Measurements of the Skin Surface Area of the Healthy Auricle and Skin Deficiency in Microtia Patients

    PubMed Central

    van Doremalen, Rob F. M.; Melchels, Ferry P. W.; Kolodzynski, Michail N.; Pouran, Behdad; Malda, Jos; Kon, Moshe; Breugem, Corstiaan C.

    2016-01-01

    Background: The limited cranial skin covering auricular implants is an important yet underrated factor in auricular reconstruction for both reconstruction surgery and tissue engineering strategies. We report exact measurements on skin deficiency in microtia patients and propose an accessible preoperative method for these measurements. Methods: Plaster ear models (n = 11; male:female = 2:1) of lobular-type microtia patients admitted to the University Medical Center Utrecht in The Netherlands were scanned using a micro-computed tomographic scanner or a cone-beam computed tomographic scanner. The resulting images were converted into mesh models from which the surface area could be calculated. Results: The mean total skin area of an adult-size healthy ear was 47.3 cm2, with 49.0 cm2 in men and 44.3 cm2 in women. Microtia ears averaged 14.5 cm2, with 15.6 cm2 in men and 12.6 cm2 in women. The amount of skin deficiency was 25.4 cm2, with 26.7 cm2 in men and 23.1 cm2 in women. Conclusions: This study proposes a novel method to provide quantitative data on the skin surface area of the healthy adult auricle and the amount of skin deficiency in microtia patients. We demonstrate that the microtia ear has less than 50% of skin available compared with healthy ears. Limited skin availability in microtia patients can lead to healing problems after auricular reconstruction and poses a significant challenge in the development of tissue-engineered cartilage implants. The results of this study could be used to evaluate outcomes and investigate new techniques with regard to tissue-engineered auricular constructs. PMID:28293505

  1. Measurement of Neutron Total Cross Sections in Support of the APT Program

    SciTech Connect

    Abfalterer, W.P.; Haight, R.C.; Morgan, G.L.; Bateman, F.B.; Dietrich, F.S.; Finlay, R.W.

    1998-11-04

    The authors have completed a new set of total cross section measurements of 37 samples spanning the periodic table. The authors employed the same technique as in a previous measurement, with refinements intended to allow measurements on separated isotopes, and with improved systematic error control. The goal of the new measurement was 1% statistical accuracy in 1% energy bins with systematic errors less than 1%. This was achieved for all but the smallest samples, for which the statistical accuracy was as large as 2% in 1% bins.

  2. Micro-gravity measurements during the total solar eclipse of 9 March 2016 in Indonesia

    NASA Astrophysics Data System (ADS)

    Laesanpura, Agus; Hidayat, Taufiq; Abdurachman, Dady; Mahasena, Putra; Premadi, Premana W.; Wulandari, Hesti; Suharyadi, Yudi; Sjarmidi, Achmad

    2016-11-01

    Since 1950s, several authors have reported the so-called anomalous gravity during the total solar eclipses through various experiments. To address this issue, in the moment of the total solar eclipse of 9 March 2016 passing most regions in Indonesia, we undertook microgravity measurements using two precise gravimeters. The measurements were made at two locations: (1) Poso (central Sulawesi), a location close to the centre passage of the total eclipse and (2) Lembang (West Java), the site of Bosscha Observatory, where the partial solar eclipse occurred. The two sites are selected to measure the possible different influence of the eclipse on aligning the three objects. The measurements were recorded three days before and one day after the eclipse at various intervals from 30 seconds to a short time at 5 seconds. The finer recording was performed several hours before and after the total eclipse. This measurement allowed detailed analysis, not only in time but also in frequency range. A detailed analysis is presented in this paper. We consider all possible geophysical as well as atmospheric effects. The residual data show that the shielding effect, usually thought as responsible factor on anomalous gravity, is not significant.

  3. Initial Results of Aperture Area Comparisons for Exo-Atmospheric Total Solar Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Johnson, B. Carol; Litorja, Maritoni; Fowler, Joel B.; Butler, James J.

    2009-01-01

    In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

  4. Measuring movement symmetry using tibial-mounted accelerometers for people recovering from total knee arthroplasty

    PubMed Central

    Christiansen, Cory L.; Bade, Michael J.; Paxton, Roger J.; Stevens-Lapsley, Jennifer E.

    2015-01-01

    Background The purpose of this investigation was to examine movement symmetry changes over the first 26 weeks following unilateral total knee arthroplasty in community environments using skin-mounted tibial accelerometers. Comparisons to healthy participants of similar age were also made. Methods Patients (N = 24) with unilateral knee osteoarthritis (mean (SD), 65.2 (9.2) years) scheduled to undergo total knee arthroplasty and a control group (N = 19 healthy people; mean (SD), 61.3 (9.2) years) were recruited. The total knee arthroplasty group participated in a standardized course of physical rehabilitation. Tibial acceleration data were recorded during a Stair Climb Test and 6-Minute Walk Test. Tibial acceleration data were reduced to initial peak acceleration for each step. An inter-limb absolute symmetry index of tibial initial peak acceleration values was calculated. Findings The total knee arthroplasty group had greater between limb asymmetry for tibial initial peak acceleration and initial peak acceleration absolute symmetry index values five weeks after total knee arthroplasty, during the Stair Climb Test and the 6-Minute Walk Test. Interpretation Tibial accelerometry is a potential tool for measuring movement symmetry following unilateral total knee arthroplasty in clinical and community environments. Accelerometer-based symmetry outcomes follow patterns similar to published measures of limb loading recorded in laboratory settings. PMID:25979222

  5. Measurement of spine and total body mineral by dual-photon absorptiometry

    NASA Technical Reports Server (NTRS)

    Mazess, R. B.; Young, D.

    1983-01-01

    The use of Gd-153 dual-photon absorptiometry at 43 and 100 keV to measure individual-bone and total-body bone minerals is discussed in a survey of recent studies on humans, phantoms, and monkeys. Precision errors of as low as 1 percent have been achieved in vivo, suggesting the use of sequential measurements in studies of immobilization and space-flight effects.

  6. Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

    NASA Technical Reports Server (NTRS)

    Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

  7. Perceptions of Community College Presidents: Total Quality Management Performance Measures at Their Colleges

    ERIC Educational Resources Information Center

    Riccardi, Mark T.

    2009-01-01

    Continuous Quality Improvement (CQI) measures such as Total Quality Management (TQM), Strategic Planning, Six Sigma, and the Balanced Scorecard are often met with skepticism among leaders of higher education. This study attempts to fill a gap in the literature regarding the study of relationships among specific variables, or building blocks,…

  8. DEMONSTRATION PLAN FIELD MEASUREMENT TECHNOLOGIES FOR TOTAL PETROLEUM HYDROCARBONS IN SOIL

    EPA Science Inventory



    The demonstration of innovative field measurement devices for total petroleum hydrocarbons (TPH) in soil is being conducted under the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation Program in June 2000 at the Navy Base Ventura County...

  9. Use of Total Possibilistic Uncertainty as a Measure of Students' Modelling Capacities

    ERIC Educational Resources Information Center

    Voskoglou, Michael Gr.

    2010-01-01

    We represent the main stages of the process of mathematical modelling as fuzzy sets in the set of the linguistic labels of negligible, low intermediate, high and complete success by students in each of these stages and we use the total possibilistic uncertainty as a measure of students' modelling capacities. A classroom experiment is also…

  10. Novel Sampling Techniques for Measurement of Turbine Engine Total Particulate Matter Emissions

    EPA Science Inventory

    This is the first progress report of a study to evaluate two different condensation devices for the measurement of the total (volatile + non-volatile) particulate matter (PM) emissions from aircraft turbine engines by direct sampling at the engine exit. The characteristics of th...

  11. Variability of standard liver volume estimation versus software-assisted total liver volume measurement.

    PubMed

    Pomposelli, James J; Tongyoo, Assanee; Wald, Christoph; Pomfret, Elizabeth A

    2012-09-01

    The estimation of the standard liver volume (SLV) is an important component of the evaluation of potential living liver donors and the surgical planning for resection for tumors. At least 16 different formulas for estimating SLV have been published in the worldwide literature. More recently, several proprietary software-assisted image postprocessing (SAIP) programs have been developed to provide accurate volume measurements based on the actual anatomy of a specific patient. Using SAIP, we measured SLV in 375 healthy potential liver donors and compared the results to SLV values that were estimated with the previously published formulas and each donor's demographic and anthropomorphic data. The percentage errors of the 16 SLV formulas versus SAIP varied by more than 59% (from -21.6% to +37.7%). One formula was not statistically different from SAIP with respect to the percentage error (-1.2%), and another formula was not statistically different with respect to the absolute liver volume (18 mL). More than 75% of the estimated SLV values produced by these 2 formulas had percentage errors within ±15%, and the formulas provided good predictions within acceptable agreement (±15%) on scatter plots. Because of the wide variability, care must be taken when a formula is being chosen for estimating SLV, but the 2 aforementioned formulas provided the most accurate results with our patient demographics.

  12. Expected total counts for the Self-Interrogation Neutron Resonance Densitometry measurements of spent nuclear fuel

    SciTech Connect

    Rossa, Riccardo; Borella, Alessandro; Van der Meer, Klaas; Labeau, Pierre-Etienne; Pauly, Nicolas

    2015-07-01

    The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive neutron technique that aims at a direct quantification of {sup 239}Pu in spent fuel assemblies by measuring the attenuation of the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. The {sup 239}Pu mass is estimated by calculating the SINRD signature, that is the ratio between the neutron counts in the fast energy region and around the 0.3 eV resonance region. The SINRD measurement approach in this study consisted in introducing a small neutron detector in the central guide tube of a PWR 17x17 fuel assembly. In order to measure the neutron flux in the energy regions defined in the SINRD signature, different detector types were used. The response of a bare {sup 238}U fission chamber is considered for the determination of the fast neutron flux, while other thermal-epithermal detectors wrapped in neutron absorbers are envisaged to measure the neutron flux around the resonance region. This paper provides an estimation of the total neutron counts that can be achieved with the detector types proposed for the SINRD measurement. In the first section a set of detectors are evaluated in terms of total neutron counts and sensitivity to the {sup 239}Pu content, in order to identify the optimal measurement configuration for each detector type. Then a study is performed to increase the total neutron counts by increasing the detector size. The study shows that the highest total neutron counts are achieved by using either {sup 3}He or {sup 10}B proportional counters because of the high neutron efficiency of these detectors. However, the calculations indicate that the biggest contribution to the measurement uncertainty is due to the measurement of the fast neutron flux. Finally, similar sensitivity to the {sup 239}Pu content is obtained by using the different detector types for the measurement of the neutron flux close to the resonance region. Therefore, the total neutron counts

  13. Calcium: total or ionized?

    PubMed

    Schenck, Patricia A; Chew, Dennis J

    2008-05-01

    Measurement of serum total calcium (tCa) has been relied on for assessment of calcium status, despite the fact that it is the ionized calcium (iCa) fraction that has biologic activity. Serum tCa does not accurately predict iCa status in many clinical conditions. For accurate assessment of iCa status, iCa should be directly measured. Anaerobic measurement of serum iCa under controlled conditions provides the most reliable assessment of calcium status; aerobic measurement of iCa with species-specific pH correction is highly correlated with anaerobic measurements.

  14. Neutral air density and temperature measurements by the TOTAL instrument aboard the ROSE payloads

    NASA Astrophysics Data System (ADS)

    Friker, A.; Luebken, F.-J.

    1992-06-01

    Four ROSE payloads, launched from November 1988 to February 1989 from northern Scandinavia, carried ionization gauges ('TOTAL' instruments) for neutral air density measurements in the altitude range 90-105 km. Temperature profiles are derived by integrating the number density profiles. Density and temperature data are presented. The limitations of the measurement technique as well as instrumental errors are discussed. In one of the flights (F1) a significant temperature enhancement was observed at an altitude where plasma instabilities were detected by independent measurements.

  15. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    SciTech Connect

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; Pekour, Mikhail; Barnard, James; Chand, Duli; Flynn, Connor; Ovchinnikov, Mikhail; Schmid, Beat; Shilling, John; Tomlinson, Jason; Fast, Jerome

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.

  16. Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

    DOE PAGES

    Kassianov, Evgueni; Sedlacek, Arthur; Berg, Larry K.; ...

    2015-07-31

    We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by amore » suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.« less

  17. Average Neutron Total Cross Sections in the Unresolved Energy Range From ORELA High Resolutio Transmission Measurements

    SciTech Connect

    Derrien, H

    2004-05-27

    Average values of the neutron total cross sections of {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu have been obtained in the unresolved resonance energy range from high-resolution transmission measurements performed at ORELA in the past two decades. The cross sections were generated by correcting the effective total cross sections for the self-shielding effects due to the resonance structure of the data. The self-shielding factors were found by calculating the effective and true cross sections with the computer code SAMMY for the same Doppler and resolution conditions as for the transmission measurements, using an appropriate set of resonance parameters. Our results are compared to results of previous measurements and to the current ENDF/B-VI data.

  18. A new fast response instrument for measuring total water content from aircraft

    NASA Astrophysics Data System (ADS)

    Nicholls, S.; Leighton, J.; Barker, R.

    1990-10-01

    A device for measuring the total water content of a parcel of air from an aircraft has been developed. The total water of a parcel of air is a conserved quantity, independent of phase changes, provided there is no transport of water through the parcel boundaries. Current airborne hygrometers normally attempt to measure the water content in individual phases and the presence of other phases invariably influences the quality of the data. However, any liquid water or ice entering this new probe is efficiently evaporated and the resultant water vapor measured using a Lyman-alpha hygrometer. In airborne trials the device was calibrated against a cooled-mirror dewpoint device. Runs were conducted in warm stratocumulus tops, through small cumulus, in mixed-phase precipitation and cirrus cloud. In all cases the device was found to produce high quality, fast response data.

  19. Results of aperture area comparisons for exo-atmospheric total solar irradiance measurements.

    PubMed

    Johnson, B Carol; Litorja, Maritoni; Fowler, Joel B; Shirley, Eric L; Barnes, Robert A; Butler, James J

    2013-11-20

    Exo-atmospheric solar irradiance measurements made by the solar irradiance community since 1978 have incorporated limiting apertures with diameters measured by a number of metrology laboratories using a variety of techniques. Knowledge of the aperture area is a critical component in the conversion of radiant flux measurements to solar irradiance. A National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) sponsored international comparison of aperture area measurements of limiting apertures provided by solar irradiance researchers was performed, the effort being executed by the National Institute of Standards and Technology (NIST) in coordination with the EOS Project Science Office. Apertures that had institutional heritage with historical solar irradiance measurements were measured using the absolute aperture measurement facility at NIST. The measurement technique employed noncontact video microscopy using high-accuracy translation stages. We have quantified the differences between the participating institutions' aperture area measurements and find no evidence to support the hypothesis that preflight aperture area measurements were the root cause of discrepancies in long-term total solar irradiance satellite measurements. Another result is the assessment of uncertainties assigned to methods used by participants. We find that uncertainties assigned to a participant's values may be underestimated.

  20. Measured versus modeled dietary arsenic and relation to urinary arsenic excretion and total exposure

    PubMed Central

    Kurzius-Spencer, Margaret; O’Rourke, Mary Kay; Hsu, Chiu-Hsieh; Hartz, Vern; Harris, Robin B.; Burgess, Jefferey L.

    2014-01-01

    Chronic exposure to arsenic (As) in food and water is a significant public health problem. Person-specific aggregate exposure is difficult to collect, and modeling based on limited food As residue databases is of uncertain reliability. Two, cross-sectional, population exposure studies—the National Human Exposure Assessment Survey (NHEXAS)-Arizona and the Arizona Border Survey (ABS)— had a total of 252 subjects with diet, water, and urinary As data. Total As was measured in 24-hour duplicate diet samples and modeled using 24-hour diet diaries in conjunction with several published food surveys of As. Two-stage regression was used to assess the effects of dietary As on urinary total As (uAs): 1) generalized linear mixed models of uAs above versus below the limit of detection (LOD); and 2) restricted models limited to those subjects with uAs > LOD, using bootstrap sampling and mixed models adjusted for age, sex, BMI, ethnicity, current smoking, and As intake from drinking and cooking water. In restricted models, measured and modeled estimates were significant predictors of uAs. Modeled dietary As based on Total Diet Study mean residues greatly underestimated dietary intake. In households with tap water As ≤ 10 ppb, over 93% of total As exposure was attributable to diet. PMID:23321855

  1. A measure of total research impact independent of time and discipline.

    PubMed

    Pepe, Alberto; Kurtz, Michael J

    2012-01-01

    Authorship and citation practices evolve with time and differ by academic discipline. As such, indicators of research productivity based on citation records are naturally subject to historical and disciplinary effects. We observe these effects on a corpus of astronomer career data constructed from a database of refereed publications. We employ a simple mechanism to measure research output using author and reference counts available in bibliographic databases to develop a citation-based indicator of research productivity. The total research impact (tori) quantifies, for an individual, the total amount of scholarly work that others have devoted to his/her work, measured in the volume of research papers. A derived measure, the research impact quotient (riq), is an age-independent measure of an individual's research ability. We demonstrate that these measures are substantially less vulnerable to temporal debasement and cross-disciplinary bias than the most popular current measures. The proposed measures of research impact, tori and riq, have been implemented in the Smithsonian/NASA Astrophysics Data System.

  2. A Measure of Total Research Impact Independent of Time and Discipline

    PubMed Central

    Pepe, Alberto; Kurtz, Michael J.

    2012-01-01

    Authorship and citation practices evolve with time and differ by academic discipline. As such, indicators of research productivity based on citation records are naturally subject to historical and disciplinary effects. We observe these effects on a corpus of astronomer career data constructed from a database of refereed publications. We employ a simple mechanism to measure research output using author and reference counts available in bibliographic databases to develop a citation-based indicator of research productivity. The total research impact (tori) quantifies, for an individual, the total amount of scholarly work that others have devoted to his/her work, measured in the volume of research papers. A derived measure, the research impact quotient (riq), is an age-independent measure of an individual's research ability. We demonstrate that these measures are substantially less vulnerable to temporal debasement and cross-disciplinary bias than the most popular current measures. The proposed measures of research impact, tori and riq, have been implemented in the Smithsonian/NASA Astrophysics Data System. PMID:23144782

  3. Measuring percent oxygen saturation of hemoglobin, percent carboxyhemoglobin and methemoglobin, and concentrations of total hemoglobin and oxygen in blood of man, dog, and baboon.

    PubMed

    Dennis, R C; Valeri, C R

    1980-08-01

    We used an automated four-wavelength spectrometer to measure the concentration of total hemoglobin, percent oxyhemoglobin, carboxyhemoglobin, and methemoglobin, and concentration of oxygen bound to hemoglobin in the blood of humans, dogs, and baboons under clinical and various experimental conditions. Measurements of total hemoglobin and methemoglobin with this simple method were comparable to those with standard spectrometric procedures. Carboxyhemoglobin measurements were comparable to those made with gas chromatography, and measurements of oxygen content were comparable to those made with the galvanic cell method. The new instrument is as accurate as the comparison methods used to evaluate it in all parameters, is reliable, and measurements take only 63 s per sample. In addition, it requires minimal operator training, infrequent need for calibration, and no sample preparation.

  4. Assessment of total body fat in infancy from skinfold thickness measurements.

    PubMed Central

    Dauncey, M J; Gandy, G; Gairdner, D

    1977-01-01

    A formula is given, allowing a value for total body fat to be calculated from skinfold thickness measurements at two sites (subscapular and triceps), in conjunction with nine body dimensions. For newborn infants total body fat so calculated accorded satisfactorily with published data from cadaver analyses. The formula has been tentatively applied to infants up to the age of 40 weeks, and to preterm infants. The difference between the growth of male and female infants was analysed in a series of 27 normal infants; the greater growth of musculoskeletal tissue in the male contrasted with the relatively greater growth of fat tissue in the female. PMID:849001

  5. Preliminary measurements of velocity, density and total temperature fluctuations in compressible subsonic flow

    NASA Technical Reports Server (NTRS)

    Stainback, P. C.; Johnson, C. B.; Basnett, C. B.

    1983-01-01

    The heat transfer characteristics of a three-wire hot-wire probe operated with a constant temperature anemometer were investigated in the subsonic compressible flow regime. The sensitivity coefficients, with respect to velocity, density and total temperature, were measured and the results were used to calculate the velocity, density, and total temperature fluctuations in the test section of the Langley 0.3-m Transonic Cryogenic Tunnel (TCT). These results were extended to give estimates for fluctuations due to vorticity, sound, and entropy. In addition, attempts were made to determine the major source of disturbances in the 0.3-m TCT.

  6. On the Use of Total Brightness Measurements for Tomography of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Frazin, R. A.; Kamalabadi, F.

    2005-08-01

    A time series of polarized white light coronagraph images may be used to make a tomographic estimate of the electron density (Ne) in three dimensions, as has been demonstrated by several authors. This technique has come to be known as solar rotational tomography (SRT). SRT relies on the fact that the polarized brightness (pB) is dominated by the electron-scattered K corona. In contrast, the total brightness contains a large contribution from the dust-scattered F-corona with some signal from the K corona. The K-corona contribution to the total brightness (B) is of interest because the Thomson scattering has different angular dependences for the polarized and unpolarized components. This difference in angular dependence in principle allows one to exploit total brightness measurements as a source of independent information for SRT. In this paper the problem of making optimal tomographic estimates of Ne using both total and polarized brightness data is considered under the assumption that the F-corona contribution can be determined with a known level of precision. Formulae for the reconstructions and the likely errors are given in terms of the singular value decomposition of the weighted measurement operators. It is shown that in order for the total brightness measurements to be useful for SRT, the process of removing the F-corona contribution must be almost perfect in the sense that it contributes uncertainty that is not much greater than the measurement noise in the polarized images. This result holds at heights below roughly 15 solar radii, where the F corona is almost completely unpolarized.

  7. Comparison of total ozone amounts derived from satellite and ground-based measurements

    NASA Technical Reports Server (NTRS)

    Planet, Walter G.; Miller, Alvin J.; Angell, James K.

    1988-01-01

    Total ozone amounts derived from the NOAA operational sounder (TOVS) are compared to measurements from Nimbus-7 SBUV and ground-based Dobson spectrophotometer observations over a seven-year period. The global trends of the data, in terms of deviations from long-term averages, derived from measurements by each satellite instrument show qualitative agreement until mid-1984 when the data diverge with the TOVS-derived data showing higher values. Additionally, more significant differences appear in both the north and south temperate zones' records. The trends derived from the satellite systems' measurements also show differences from that of the Dobson instrument measurements with the trend of the TOVS measurements showing generally better overall agreement with the Dobson data record.

  8. Total hemispherical emittance measured at high temperatures by the calorimetric method

    SciTech Connect

    DiFilippo, F.; Mirtich, M.J.; Banks, B.A.; Stidham, C.; Kussmaul, M.

    1994-09-01

    A calorimetric vacuum emissometer (CVE) capable of measuring total hemispherical emittance of surfaces at elevated temperatures was designed, built, and tested. Several materials with a wide range of emittances were measured in the CVE between 773 to 923 K. These results were compared to values calculated from spectral emittance curves measured in a room temperature Hohlraum reflectometer and in an open-air elevated temperature emissometer. The results differed by as much as 0.2 for some materials but were in closer agreement for the more highly-emitting, diffuse-reflecting samples. The differences were attributed to temperature, atmospheric, and directional effects, and errors in the Hohlraum and emissometer measurements ({+-} 5 percent). The probable error of the CVE measurements was typically less than 1 percent.

  9. Application of Electronic Nose for Measuring Total Volatile Basic Nitrogen and Total Viable Counts in Packaged Pork During Refrigerated Storage.

    PubMed

    Li, Miaoyun; Wang, Haibiao; Sun, Lingxia; Zhao, Gaiming; Huang, Xianqing

    2016-04-01

    The objective of this study was to predict the total viable counts (TVC) and total volatile basic nitrogen (TVB-N) in pork using an electronic nose (E-nose), and to assess the freshness of chilled pork during storage using different packaging methods, including pallet packaging (PP), vacuum packaging (VP), and modified atmosphere packaging (MAP, 40% O2 /40% CO2 /20% N2 ). Principal component analysis (PCA) was used to analyze the E-nose signals, and the results showed that the relationships between the freshness of chilled pork and E-nose signals could be distinguished in the loadings plots, and the freshness of chilled pork could be distributed along 2 first principal components. Multiple linear regression (MLR) was used to correlate TVC and TVB-N to E-nose signals. High F and R2 values were obtained in the MLR output of TVB-N (F = 32.1, 21.6, and 24.2 for PP [R2 = 0.93], VP [R2 = 0.94], and MAP [R2 = 0.95], respectively) and TVC (F = 34.2, 46.4, and 7.8 for PP [R2 = 0.98], VP [R2 = 0.89], and MAP [R2 = 0.85], respectively). The results of this study suggest that it is possible to use the E-nose technology to predict TVB-N and TVC for assessing the freshness of chilled pork during storage.

  10. Can ECAP measures be used for totally objective programming of cochlear implants?

    PubMed

    McKay, Colette M; Chandan, Kirpa; Akhoun, Idrick; Siciliano, Catherine; Kluk, Karolina

    2013-12-01

    An experiment was conducted with eight cochlear implant subjects to investigate the feasibility of using electrically evoked compound action potential (ECAP) measures other than ECAP thresholds to predict the way that behavioral thresholds change with rate of stimulation, and hence, whether they can be used without combination with behavioral measures to determine program stimulus levels for cochlear implants. Loudness models indicate that two peripheral neural response characteristics contribute to the slope of the threshold versus rate function: the way that neural activity to each stimulus pulse decreases as rate increases and the slope of the neural response versus stimulus current function. ECAP measures related to these two characteristics were measured: the way that ECAP amplitude decreases with stimulus rate and the ECAP amplitude growth function, respectively. A loudness model (incorporating temporal integration and the two neural response characteristics) and regression analyses were used to evaluate whether the ECAP measures could predict the average slope of the behavioral threshold versus current function and whether individual variation in the measures could predict individual variation in the slope of the threshold function. The average change of behavioral threshold with increasing rate was well predicted by the model when using the average ECAP data. However, the individual variations in the slope of the thresholds versus rate functions were not well predicted by individual variations in ECAP data. It was concluded that these ECAP measures are not useful for fully objective programming, possibly because they do not accurately reflect the neural response characteristics assumed by the model, or are measured at current levels much higher than threshold currents.

  11. Total OH reactivity measurement in a BVOC dominated temperate forest during a summer campaign, 2014

    NASA Astrophysics Data System (ADS)

    Ramasamy, Sathiyamurthi; Ida, Akira; Jones, Charlotte; Kato, Shungo; Tsurumaru, Hiroshi; Kishimoto, Iori; Kawasaki, Shio; Sadanaga, Yasuhiro; Nakashima, Yoshihiro; Nakayama, Tomoki; Matsumi, Yutaka; Mochida, Michihiro; Kagami, Sara; Deng, Yange; Ogawa, Shuhei; Kawana, Kaori; Kajii, Yoshizumi

    2016-04-01

    A total OH reactivity measurement was conducted in coniferous forest located in Wakayama prefecture, Japan, during the summer of 2014. The average total OH reactivity, measured using a laser-induced pump and probe technique was 7.1 s-1. The measured OH reactivity was comparable with other coniferous and temperate forest measurements and much lower than that of tropical forests. OH reactivity varied diurnally and showed moderate linear correlation with temperature (r2 = 0.66) and light (r2 = 0.53). Monoterpene emitters, Cryptomeria japonica and Chamaecyparis obutsa, are the dominant tree species in this forest. Although clean air from the sea was predominant, the beginning of the campaign was influenced by transported anthropogenic pollutants and consequently a higher average OH reactivity of 9.8 s-1 with high missing sinks of 37.3% was determined. Cleaner conditions, along with cooler day-time temperatures during in the second half of the campaign resulted in a lower average OH reactivity of 6.0 s-1 with a lower missing OH reactivity of 21.5%. Monoterpenes, isoprene, acetaldehyde were the dominant contributors to the total OH reactivity, accounting for 23.7%, 17.0% and 14.5%, respectively.

  12. Beryllium Concentrations at European Workplaces: Comparison of 'Total' and Inhalable Particulate Measurements.

    PubMed

    Kock, Heiko; Civic, Terence; Koch, Wolfgang

    2015-07-01

    A field study was carried out in order to derive a factor for the conversion of historic worker exposure data on airborne beryllium (Be) obtained by sampling according to the 37-mm closed faced filter cassette (CFC) 'total' particulate method into exposure concentration values to be expected when sampling using the 'Gesamtstaubprobenahmesystem' (GSP) inhalable sampling convention. Workplaces selected to represent the different copper Be work processing operations that typically occur in Germany and the EU were monitored revealing a broad spectrum of prevailing Be size distributions. In total, 39 personal samples were taken using a 37-mm CFC and a GSP worn side by side for simultaneous collection of the 'total' dust and the inhalable particulates, respectively. In addition, 20 static general area measurements were carried out using GSP, CFC, and Respicon samplers in parallel, the latter one providing information on the extra-thoracic fraction of the workplace aerosol. The study showed that there is a linear relationship between the concentrations measured with the CFC and those measured with the GSP sampler. The geometric mean value of the ratios of time-weighted average concentrations determined from GSP and CFC samples of all personal samples was 2.88. The individual values covered a range between 1 and 17 related to differences in size distributions of the Be-containing particulates. This was supported by the area measurements showing that the conversion factor increases with increasing values of the extra-thoracic fraction covering a range between 0 and 79%.

  13. Small Total Dose Measurement System for SOHLA-1 and SDS-1

    NASA Astrophysics Data System (ADS)

    Kimoto, Yugo; Satoh, Yohei; Tachihara, Hiroshi

    The Japanese Aerospace Exploration Agency (JAXA) uses monitors on board satellites to measure and record in-flight data about ionization effects in space. A compact, total-dose measurement system for small satellites—Space-Oriented Higashiosaka Leading Association -1 (SOHLA-1) and Small Demonstration-Satellite -1 (SDS-1)—was developed based on a prior system for measuring total ionizing dose effects. Especially, the sensor for SDS-1 is much smaller than the sensor for SOHLA-1. The sensor for SDS-1 is 8 mm wide × 3 mm high × 19 mm long and weighs approximately 4 g with 500 mm with its wire harness. An 8-pin Lead less Chip Carrier (LCC) RADFET and temperature sensor are arranged on it. Seven sensors are mounted on some components inside the SDS-1. The sensor for SOHLA-1 is a 14-pin Dual Inline Package (DIP) type RADFET. The four sensors, which have RADFET on a printed board covered with an aluminum chassis, are mounted both inside and outside the satellite. This report presents small total dose measurement systems and ground irradiation test results for two small satellites.

  14. A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection.

    PubMed

    Bechet, P; Mitran, R; Munteanu, M

    2013-08-01

    Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8-28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.

  15. A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection

    NASA Astrophysics Data System (ADS)

    Bechet, P.; Mitran, R.; Munteanu, M.

    2013-08-01

    Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8-28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.

  16. Radial velocity discriminated coronal photometric measurements at the July 11, 1991 total eclipse

    NASA Astrophysics Data System (ADS)

    Beavers, Willet I.; Eitter, Joseph J.

    2009-03-01

    The results from a set of 12 solar corona radial velocity measurements in the 400-440 nm spectral band during the total solar eclipse of July 11, 1991 are reported. The measurements show that the orbital motion of the F-corona material near the sun in the ecliptic plane is consistent with Keplerian motion and predominantly, but not exclusively, prograde, as is usually assumed. This work demonstrates a method of using the measured radial velocities to sort out the relative amounts of K-corona, near-earth F-corona, near-solar F-corona, and scattered light in each measurement for each observation point W and E of the sun between 2.5 Ro(solar radii) and 5 Ro along the celestial equator and at three points north of the sun. The near-solar F-corona component is quite weak, contributing only 7-14% of the total signal in each case. The stronger diffraction component from near-earth F-corona is estimated to have been produced by particles with radii of about 11μ. In contrast, the scattered light component appears as strong zero-velocity features dominating all the measurements. The measurements W and E of the sun and near the ecliptic plane also show evidence of a red-shift velocity of at least 330 km s -1, suggestive of a high-speed dust outflow from the sun.

  17. Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey

    PubMed Central

    Huang, Lihui; Yu, Chang Ho; Hopke, Philip K.; Lioy, Paul J.; Buckley, Brian T.; Shin, Jin Young; Fan, Zhihua (Tina)

    2015-01-01

    Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na2CO3-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m3. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM10 collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05–1.41 ng/m3 in the winter and 0.99–1.56 ng/m3 in the summer. The soluble Cr(VI) concentrations were 0.03–0.19 ng/m3 in the winter and 0.12–0.37 ng/m3 in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3–43.7%, significantly higher than 4.2–14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer. PMID:26120324

  18. Performing Accurate Rigid Kinematics Measurements from 3D in vivo Image Sequences through Median Consensus Simultaneous Registration.

    PubMed

    Cresson, T; Jacq, J; Burdin, V; Roux, Ch

    2005-01-01

    While focusing at accurate 3D joint kinematics, this paper explores the problem of how to perform a robust rigid registration for a sequence of object surfaces observed using standard 3D medical imaging techniques. Each object instance is assumed to give access to a polyhedral encoding of its boundary. We consider the case where object instances are noised with significant truncations and segmentation errors. The proposed method aims to tackle this problem in a global way, fully exploiting the duality between redundancy and complementarity of the available instances set. The algorithm operates through robust and simultaneous registration of all geometrical instances on a virtual instance accounting for their median consensus. When compared with standard robust techniques, trials reveal significant gains, as much in robustness as in accuracy. The considered applications are mainly focused on generating highly accurate kinematics in relation to the bone structures of the most complex joints - the tarsus and the carpus - for which no alternative examination techniques exist, enabling fine morphological analysis as well as access to internal joint motions.

  19. Uncertain future soil carbon dynamics under global change predicted by models constrained by total carbon measurements.

    PubMed

    Luo, Zhongkui; Wang, Enli; Sun, Osbert J

    2017-01-23

    Pool-based carbon (C) models are widely applied to predict soil C dynamics under global change and infer underlying mechanisms. However, it is unclear about the credibility of model-predicted C pool size, decay rate (k) and/or microbial C use efficiency (e) as only data on bulked total C is usually available for model-constraining. Using observing system simulation experiments (OSSE), we constrained a two-pool model using simulated datasets of total soil C dynamics under topical hypotheses on responses of soil C dynamics to warming and elevated CO2 (i.e., global change scenarios). The results indicated that the model predicted great uncertainties in C pool size, k and e under all global change scenarios, resulting in the difficulty to correctly infer the presupposed "real" values of those parameters that are used to generate the simulated total soil C for constraining the model. Furthermore, the model using the constrained parameters generated divergent future soil C dynamics. Compared with the predictions using the presupposed real parameters (i.e., the real future C dynamics), the percentage uncertainty in 100-year predictions using the constrained parameters was up to 45% depending on global change scenarios and data availability for model-constraining. Such great uncertainty was mainly due to the high collinearity among the model parameters. Using pool-based models, we argue that soil C pool size, k and/or e and their responses to global change have to be estimated explicitly and empirically, rather than through model-fitting, in order to accurately predict C dynamics and infer underlying mechanisms. The OSSE approach provides a powerful way to identify data requirement for the new generation of model development and test model performance. This article is protected by copyright. All rights reserved.

  20. TOTAL: a rocket-borne instrument for high resolution measurements of neutral air turbulence during DYANA

    NASA Astrophysics Data System (ADS)

    Hillert, W.; Lübken, F.-J.; Lehmacher, G.

    1994-12-01

    An improved version of a rocket-borne instrument ('TOTAL'), optimized for high resolution measurements of relative density variations, was successfully employed during the DYANA campaign in winter 1990. Both the inertial-convective subrange and the viscous-diffusive subrange of turbulence were observed in the power spectra derived from density fluctuations. An extended spectral model which comprises both subranges has been used to analyse the data. In this paper we present altitude profiles of turbulent parameters, such as turbulent energy dissipation rates ɛ and turbulent diffusion coefficients K, which were derived from a total of eight successfully launched instruments at high (Andoya, 69°N) and middle (Biscarosse, 44°N) latitudes. The limitations of the measurement technique as well as instrumental errors are discussed. The results mainly show small values of ɛ and K throughout the whole campaign period. The turbopause was found at an altitude of 95 ± 3 km.

  1. Measurements of NO and total reactive odd-nitrogen, NOy, in the Antarctic stratosphere

    NASA Technical Reports Server (NTRS)

    Fahey, D. W.; Murphy, D. M.; Eubank, C. S.; Ferry, G. V.; Chan, K. Roland; Ko, Malcolm K. W.

    1988-01-01

    Measurements of NO and total reactive N, NOy, were made as part of the Airborne Antarctic Ozone Experiment conducted in Punta Arenas, Chile during Aug. and Sept. 1987. The total reactive N reservoir includes the species NO, NO2, NO3, N2 O5, HNO3, and ClONO2. The instrument was located on board the NASA ER2 aircraft which conducted 12 flights over the Antarctic continent reaching altitudes of 18 km at 72 deg S latitude. The NOy technique utilized the conversion of component NOy species to NO on a gold catalyst and the subsequent detection of NO by the chemiluminescence reaction of NO with ozone. Since the inlet sample line is heated and the catalyst operates at 300 C, NOy incorporated in aerosols evaporates and is converted to NO. NO was measured on two separate flights by removing the catalyst from the sample inlet line.

  2. Comprehensive measurement of total nondigestible carbohydrates in foods by enzymatic-gravimetric method and liquid chromatography.

    PubMed

    Nishibata, Toyohide; Tashiro, Kouichi; Kanahori, Sumiko; Hashizume, Chieko; Kitagawa, Machiko; Okuma, Kazuhiro; Gordon, Dennis T

    2009-09-09

    Total nondigestible carbohydrate (NDC) in foods was determined by combining, not modifications, AOAC Official Methods 991.43, 2001.03, and 2002.02. Total NDC included insoluble dietary fiber (IDF) + high-molecular-weight soluble dietary fiber (HMWSDF), nondigestible oligosaccharides (NDO) not precipitated in ethanol solution, and resistant starch (RS). Eight sources of NDC (cellulose, wheat bran, gum arabic, resistant maltodextrin, polydextrose, fructooligosaccharide, galactooligosaccharides, and RS) were incorporated in different combinations into standard formula bread samples. All of the NDC sources and bread samples were analyzed for their (1) IDF + HMWSDF content with corrections for residual RS amount using AOAC Official Method 991.43, (2) NDO by liquid chromatography (LC) in AOAC Official Method 2001.03, and (3) RS by AOAC Official Method 2002.02. The correlation coefficient (R(2)) comparing calculated amounts versus measured amounts of total NDC in 11 bread samples was 0.92. Analysis of commercial food samples was also well matched with the DF + NDO value on their nutritional label. Consequently, we confirmed a single measurement of LC can determine all NDO in foods, and total NDC in foods can be determined by unifying existing AOAC Official Methods.

  3. Application of measurement configuration optimization for accurate metrology of sub-wavelength dimensions in multilayer gratings using optical scatterometry.

    PubMed

    Zhu, Jinlong; Shi, Yating; Goddard, Lynford L; Liu, Shiyuan

    2016-09-01

    Critical dimension measurement accuracy in optical scatterometry relies not only on the systematic noise level of instruments and the reliability of forward modeling algorithms, but also heavily on the measurement configuration. To construct a set of potentially high-accuracy configurations, we apply a general measurement configuration optimization method based on error propagation theory and singular value decomposition, by which the measurement accuracy is approximated as a function of a pseudo Jacobian with respect to the measurement configurations. Simulations and experiments for the optical metrology of a sub-wavelength deep-etched multilayer grating establish the feasibility of the proposed method.

  4. Gas chromatographic identification of interferences and their elimination in measuring total reduced sulfur gases

    SciTech Connect

    de Souza, T.L.C. )

    1992-05-01

    This paper reports on a selective filter that is capable of eliminating positive interference in the coulometric measurement of ambient concentrations of total reduced sulfur gases which has been successfully developed and field tested. Most of the interference was found to be caused by terpenes, which react with bromine, the active reagent in the coulometric titrators. Terpenes are given off by conifer trees in the natural environment as well as emitted in pulping and other wood-handling and lumber manufacturing operations.

  5. Sensitivity Studies for Space-based Measurements of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

    NASA Technical Reports Server (NTRS)

    Mao, Jianping; Kawa, S. Randolph

    2003-01-01

    A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 micron. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the effects of other interfering constituents, such as water vapor, aerosols and cirrus clouds, on the radiance are significant but the overall effects of the modification of light path length on total back-to-space radiance sensitivity to CO2 change are minor for general cases, which means that generally the total column CO2 can be derived in high precision from the ratio of the on-line center to off-line radiances; (c) together with CO2 gas absorption aerosol/cirrus cloud layer has differential scattering which may result in the modification of on-line to off-line radiance ratio which could lead a large bias in the total column CO2 retrieval. Approaches to correct such bias need further investigation. (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature, which is achievable from new atmospheric sounders in the near future; (e) the atmospheric path length, over which the CO2 absorption occurs, should be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

  6. Aromatase inhibitors: assessment of biochemical efficacy measured by total body aromatase inhibition and tissue estrogen suppression.

    PubMed

    Lønning, Per E; Geisler, Jürgen

    2008-02-01

    The implementation of aromatase inhibitors for treatment of early and metastatic breast cancer has been one of the major improvements in endocrine therapy of breast cancer. Measurement of endocrine effects of aromatase inhibition in vivo has been a major tool in the process of evaluating novel compounds. Biochemical efficacy of aromatase inhibitors in vivo may be determined from their effects on "total body aromatization" as well changes in plasma and tissue estrogen levels. Due to high sensitivity, tracer methods allowing calculation of whole body aromatase inhibition are still considered the gold standard. The method developed by our group in collaboration with the Royal Marsden Hospital and the results of this joint program are summarized and discussed. These studies allowed classification of the different aromatase inhibitors and their optimal dosage, selecting the best compounds for clinical evaluation. In vivo total body aromatase assessment is a work-consuming method, allowing such studies to be conducted in a limited number of patients only. In contrast, plasma estrogen measurement is a cruder but simpler method, allowing screening of larger groups of patients. As plasma estrogens arise through passive diffusion of estrogens synthesized in different body compartments, plasma estrogens, as well as total body aromatase assessment, present a rough estimate of total body tissue estrogen production, and changes associated with treatment with aromatase inhibitors reflect the effects on tissue estrogen production in general. However, plasma estrogen levels do not correlate to breast cancer tissue estrogen levels. This is due to the endocrine autonomy of breast cancer tissue with significant local estrogen production in some tumors. Thus, direct measurement of intratumor estrogens is demanded to evaluate the effects of aromatase inhibitors in malignant target tissues. Our group has developed a highly sensitive HPLC-RIA for the simultaneous measurement of estrone

  7. High-Resolution Measurements of e++H2O Total Cross Section

    NASA Astrophysics Data System (ADS)

    Loreti, A.; Kadokura, R.; Fayer, S. E.; Kövér, Á.; Laricchia, G.

    2016-12-01

    Using a purely electrostatic positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃1 ° ) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section.

  8. Initial Slope Index of Total Cerebral Blood Flow Measured by Hydrogen Clearance: A Pragmatic Evaluation

    DTIC Science & Technology

    1975-06-01

    An initial slope index of total cerebral blood flow, measured by hydrogen clearance from torcular blood, shows high correlation with flows calculated by bicompartmental analysis. In 247 flow measurements done on 41 rhesus monkeys, a linear regression analysis between these two methods of calculating flow shows a correlation coefficient of 0.9280 with a standard error about y values of plus or minus 7.63. The initial slope index is not only faster to calculate but does not require that a steady state be maintained for 10 minutes.

  9. Precise measurement method for ionospheric total electron content using signals from GPS satellites

    NASA Technical Reports Server (NTRS)

    Imae, Michito; Kiuchi, Hitoshi; Kaneko, Akihiro; Hama, Shinichi; Miki, Chihiro

    1990-01-01

    A GPS codeless receiver called GTR-2 was for measuring total electron content (TEC) along the line of sight to the GPS satellite by using the cross correlation amplitude of the received P-code signals carried by L1(1575.42 MHz) and L2(1227.6 MHz). This equipment has the performance of uncertainty in the measurement of TEC of about 2 X 10(exp 16) electrons/sq m when a 10 dBi gain antenna was used. To increase the measurement performance, an upper version of GTR-2 called GTR-3 is planned which uses the phase information of the continuous signals obtained by making a cross correlation or multiplication of the received L1 and L2 P-code signals. By using the difference of these measured phases values, the ionospheric delay with the ambiguities of the periods of L1+L2 and L1-L2 signals can be estimated.

  10. The current status of continuous noninvasive measurement of total, carboxy, and methemoglobin concentration.

    PubMed

    Shamir, Micha Y; Avramovich, Aharon; Smaka, Todd

    2012-05-01

    Intraoperative early detection of anemia, identifying toxic levels of carboxyhemoglobin after carbon monoxide exposure and titrating drug dosage to prevent toxic levels of methemoglobin are important goals. The pulse oximeter works by illuminating light into the tissue and sensing the amount of light absorbed. The same methodology is used by laboratory hemoglobinometers to measure hemoglobin concentration. Because both devices work in the same way, efforts were made to modify the pulse oximeter to also measure hemoglobin concentration. Currently there are 2 commercial pulse oximeters (Masimo Rainbow SET and OrSense NBM-200MP) that measure total hemoglobin concentration and one (Masimo) that also measures methemoglobin and carboxyhemoglobin. In this review, we describe the peer-reviewed literature addressing the accuracy of these monitors.

  11. Discriminative ability of total body bone-mineral measured by dual photon absorptiometry.

    PubMed

    Gotfredsen, A; Pødenphant, J; Nilas, L; Christiansen, C

    1989-04-01

    We investigated the discriminative ability of total body bone-mineral expressed as the total body bone-density (TBBD) measured by dual photon absorptiometry (DPA) in 79 healthy premenopausal women, 27 healthy postmenopausal women, and 120 female osteoporotic fracture patients presenting with either Colles' fracture, vertebral fracture or femoral neck-fracture. TBBD was compared to the bone-mineral density of the lumbar spine (BMDspine) also measured by DPA, and to the bone-mineral content of the forearms (BMCforearm) measured by single photon absorptiometry (SPA). TBBD, BMDspine and BMCforearm showed that all the fracture patient groups had significantly reduced bone-mass. Using receiver operating characteristic (ROC) analysis, we found that TBBD had a tendency towards better discriminative ability than BMDspine or BMCforearm with regard to the discrimination between healthy premenopausal women and the three types of osteoporotic fractures (not significant in spinal fracture patients). BMCforearm had an intermediate position, whereas BMDspine had the smallest discriminative ability. TBBD also discriminated better between healthy postmenopausal women and hip-fracture patients than BMDspine or BMCforearm, whereas there was no significant difference between the three methods regarding the discrimination between the healthy postmenopausal women and the Colles' and spinal fracture patients. We conclude that the TBBD measurement by DPA has a discriminative potential which is better than the local spine or forearm measurements.

  12. The comparison of IR and MW ground-based measurements of total precipitable water

    NASA Astrophysics Data System (ADS)

    Berezin, I. A.; Virolainen, Ya. A.; Timofeyev, Yu. M.; Poberovskii, A. V.

    2016-05-01

    Water vapor is one of the basic climate gases playing a key role in various processes at different altitudes of the Earth's atmosphere. An intercomparison and validation of different total precipitable water (TPW) measurement methods are important for determining the true accuracy of these methods, the shared use of data from multiple sources, the creation of data archives of different measurements, etc. In this paper, the TPW values obtained from measurements of solar IR spectral radiation (~8-9 μm absorption band) and thermal MW radiation of the atmosphere (1.35 cm absorption line) for 138 days of observation are compared. Measurements have been carried out from March 2013 to June 2014 at Peterhof station of the St. Petersburg State University in (59.88° N, 29.82° E). It is shown that MW measurements usually give higher TPW values than IR measurements. The bias between the two methods varies from 1 to 8% for small and large TPW values, respectively. With increasing TPW values, the bias reduces and for TPW > 1 cm it is ~1%. Standard deviation (SD) between the two methods reaches 7% for TPW < 0.4 cm and 3-5% for TPW > 1 cm. These data show the high quality of both remote sensing methods. Moreover, the IR measurements have a higher accuracy than MW measurements for small TPW values.

  13. White-light interferometer with dispersion: an accurate fiber-optic sensor for the measurement of distance.

    PubMed

    Pavlícek, Pavel; Häusler, Gerd

    2005-05-20

    We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.

  14. Total Measurement Uncertainty (TMU) for Nondestructive Assay of Transuranic (TRU) Waste at the WRAP Facility

    SciTech Connect

    WILLS, C.E.

    2000-02-24

    The Waste Receiving and Processing (WRAP) facility, located on the Hanford Site in southeast Washington, is a key link in the certification of Hanford's transuranic (TRU) waste for shipment to the Waste Isolation Pilot Plant (WIPP). Waste characterization is one of the vital functions performed at WRAP, and nondestructive assay (NDA) measurements of TRU waste containers is one of two required methods used for waste characterization (Reference 1). Various programs exist to ensure the validity of waste characterization data; all of these cite the need for clearly defined knowledge of uncertainty, associated with any measurements taken. All measurements have an inherent uncertainty associated with them. The combined effect of all uncertainties associated with a measurement is referred to as the Total Measurement Uncertainty (TMU). The NDA measurement uncertainties can be numerous and complex. In addition to system-induced measurement uncertainty, other factors contribute to the TMU, each associated with a particular measurement. The NDA measurements at WRAP are based on processes (radioactive decay and induced fission) which are statistical in nature. As a result, the proper statistical summation of the various uncertainty components is essential. This report examines the contributing factors to NDA measurement uncertainty at WRAP. The significance of each factor on the TMU is analyzed, and a final method is given for determining the TMU for NDA measurements at WRAP. As more data becomes available, and WRAP gains in operational experience, this report will be reviewed semi-annually and updated as necessary. This report also includes the data flow paths for the analytical process in the radiometric determinations.

  15. First light measurements of the Total Solar Irradiance experiment CLARA on NORSAT-1

    NASA Astrophysics Data System (ADS)

    Schmutz, Werner

    2016-07-01

    NORSAT-1 is a Norwegian micro-satellite, which will be launched April 22, 2016. (In the future at the time of writing this abstract.) The satellite carries two scientific instruments and an AIS receiver for performing ship detection from space. One of the scientific instruments is a Compact Light-weight Absolute RAdiometer (CLARA) and the other is a Langmuir Probe instrument comprising four probes mounted on booms. The latter experiment will measure electron density and the platform's floating potential along the orbit. The University of Oslo provides the Langmuir probes. The radiometer experiment CLARA has been built by PMOD/WRC funded through the Swiss PRODEX program. It will measure Total Solar Irradiance with an instrument of novel design that is optimized for minimizing mass and size by still ensuring highest measuring accuracy and thermal stability. The radiometers of CLARA have been fully characterized as well as calibrated at the TRF facility. It is expected that the first light accuracy of the absolute measurement of Total Solar Irradiance will be better than pm0.3 W/m^{2, allowing to probe the current TSI composite for its absolute level. The presentation will give an overview of the CLARA instrument and its calibration. It is expected that at the time of the COSPAR conference the first light TSI value of CLARA/NORSAT-1 is ready for publication. Together with a previous absolute TSI measurements available for July 27, 2010 measured by PREMOS/PICARD the new absolute TSI measurement will be used to test the accuracy of long term TSI trend given by the relative TSI composite.

  16. Progress in accurate measurements of sub-surface flows near the solar limb using ring-diagram analysis

    NASA Astrophysics Data System (ADS)

    Baldner, Charles; Bogart, Richard S.

    2016-05-01

    The use of helioseismology to study the properties of the Sun has yielded very high precision measurements of solar flows throughout much of the interior. It has been apparent for many years, however, that the accuracy of many of these measurements is suspect due to significant systematic effects in helioseismic techniques. The most well-known effect in flow measurements is sometimes referred to as the `center-to-limb' effect, in which flow measurements depend strongly on the distance of the measurement from the center of the observed solar disk. Attempts have already been made to explain the origin of this error (e.g. Balder & Schou 2012) and to correct it (e.g. Zhao et al. 2011). Significant work remains, however.In this work, we report on continued efforts to precisely characterize the effect of position on the observed disk on flow measurements in the HMI ring diagram pipeline, and from other HMI data. Our efforts are focused on 1) quantifying the non-radial systematic effect in flow measurements; 2) understanding the effect of the underlying model used in the mode parameter estimations; and 3) characterizing the difference between helioseismic measurements made with different observed quantities.

  17. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  18. A comparison of total precipitable water measurements from radiosonde and sunphotometers

    NASA Astrophysics Data System (ADS)

    Campmany, Elies; Bech, Joan; Rodríguez-Marcos, Javier; Sola, Yolanda; Lorente, Jerónimo

    2010-08-01

    Atmospheric water vapour is an essential component of the terrestrial atmosphere and must be known precisely in a wide range of applications such as radiative transfer modelling or weather forecasting to mention just a few examples. Vertically integrated measurements, or total precipitable water (TPW) equivalent amounts traditionally derived from radiosonde measurements, are needed in many of these applications and can also be obtained from other methodologies such as sunphotometers or GPS-based techniques. This paper presents a study comparing different measurements of TPW from radiosonde and sunphotometer data recorded from 2001 to 2004 in Barcelona, Spain. Three collocated instruments were employed in this study: RS-80A Vaisala sondes and two types of commonly used sunphotometers (Cimel 318N-VBS7 and Microtops II). A cloud screening filter was applied to photometer data based on the quality control procedure of the AERONET database. A systematic comparison among the measurements indicates that bivariate correlations between different instruments were high, with correlation factors ( r2) above 0.8 in all cases. Measurements covered all seasons allowing examining intra-annual variability, which generally did not exhibit statistically significant differences. Examination of 57 concurrent measurements of the three instruments indicated that radiosonde TPW measurements were the highest (15 mm on average) and Cimel and Microtops presented similar values (12 mm and 11 mm respectively).

  19. Accurate and high-performance 3D position measurement of fiducial marks by stereoscopic system for railway track inspection

    NASA Astrophysics Data System (ADS)

    Gorbachev, Alexey A.; Serikova, Mariya G.; Pantyushina, Ekaterina N.; Volkova, Daria A.

    2016-04-01

    Modern demands for railway track measurements require high accuracy (about 2-5 mm) of rails placement along the track to ensure smooth, safe and fast transportation. As a mean for railways geometry measurements we suggest a stereoscopic system which measures 3D position of fiducial marks arranged along the track by image processing algorithms. The system accuracy was verified during laboratory tests by comparison with precise laser tracker indications. The accuracy of +/-1.5 mm within a measurement volume 150×400×5000 mm was achieved during the tests. This confirmed that the stereoscopic system demonstrates good measurement accuracy and can be potentially used as fully automated mean for railway track inspection.

  20. Measuring the Grafting Density of Nanoparticles in Solution by Analytical Ultracentrifugation and Total Organic Carbon Analysis

    PubMed Central

    Benoit, Denise N.; Zhu, Huiguang; Lilierose, Michael H.; Verm, Raymond A.; Ali, Naushaba; Morrison, Adam N.; Fortner, John D.; Avendano, Carolina; Colvin, Vicki L.

    2012-01-01

    Many of the solution phase properties of nanoparticles, such as their colloidal stability and hydrodynamic diameter, are governed by the number of stabilizing groups bound to the particle surface (i.e., grafting density). Here we show how two techniques, analytical ultracentrifugation (AUC) and total organic carbon analysis (TOC), can be applied separately to the measurement of this parameter. AUC directly measures the density of nanoparticle–polymer conjugates while TOC provides the total carbon content of its aqueous dispersions. When these techniques are applied to model gold nanoparticles capped with thiolated poly(ethylene glycol), the measured grafting densities across a range of polymer chain lengths, polymer concentrations, and nanoparticle diameters agree to within 20%. Moreover, the measured grafting densities correlate well with the polymer content determined by thermogravimetric analysis of solid conjugate samples. Using these tools, we examine the particle core diameter, polymer chain length, and polymer solution concentration dependence of nanoparticle grafting densities in a gold nanoparticle–poly(ethylene glycol) conjugate system. PMID:22967239

  1. Measurement of total RBC volume relative to lean body mass for diagnosis of polycythemia.

    PubMed

    Berlin, N I; Lewis, S M

    2000-12-01

    An elevated total RBC volume (TRCV) in milliliters per kilogram of body weight has been an essential criterion for determining whether a person is polycythemic. This may be misleading in obese subjects as the TRCV per kilogram of fat is only one-tenth that of the TRCV of the lean body mass (LBM). Various formulas based on surface area have been used to account for this difference, but they are not always reliable. Direct measurement of TRCV per kilogram of lean body mass was obtained originally in studies in which body composition was determined by the combined body density and total body water measurement method. This is impractical as a routine procedure, but simple-to-use instruments are now available for direct measurement of a person's body composition and percentage of fat by impedance technology. Thus, the TRCV can be obtained by a direct measurement that discounts the effects of fat, and a graph has been designed to normalize the TRCV to milliliters per kilogram of LBM. The TRCV for men and women has been established as 36 mL/kg LBM; when it is more than 43 mL/kg LBM, a diagnosis of polychthemia can be made with confidence.

  2. Measuring partial body potassium in the arm versus total body potassium.

    PubMed

    Wielopolski, L; Ramirez, L M; Gallagher, D; Sarkar, S R; Zhu, F; Kaysen, G A; Levin, N W; Heymsfield, S B; Wang, Z M

    2006-09-01

    Skeletal muscle (SM), the body's main structural support, has been implicated in metabolic, physiological, and disease processes in humans. Despite being the largest tissue in the human body, its assessment remains difficult and indirect. However, being metabolically active it contains over 50% of the total body potassium (TBK) pool. We present our preliminary results from a new system for measuring partial body K (PBK) that presently are limited to the arm yet provide a direct and specific measure of the SM. This uniquely specific quantification of the SM mass in the arm, which is shielded from the body during measurement, allows us to simplify the assumptions used in deriving the total SM, thereby possibly improving the modeling of the human body compartments. Preliminary results show that PBK measurements are consistent with those from the TBK previously obtained from the same subjects, thus offering a simpler alternative to computed tomography and magnetic resonance imaging used for the same purposes. The PBK system, which can be set up in a physician's office or bedside in a hospital, is completely passive, safe, and inexpensive; it can be used on immobilized patients, children, pregnant women, or other at-risk populations.

  3. Airborne Aerosol In situ Measurements during TCAP: A Closure Study of Total Scattering

    SciTech Connect

    Kassianov, Evgueni I.; Berg, Larry K.; Pekour, Mikhail S.; Flynn, Connor J.; Tomlinson, Jason M.; Chand, Duli; Shilling, John E.; Ovchinnikov, Mikhail; Barnard, James C.; Sedlacek, Art; Schmid, Beat

    2015-07-31

    We present here a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. The synergistically employed aircraft data involve aerosol microphysical, chemical, and optical components and ambient relative humidity measurements. Our framework is developed emphasizing the explicit use of the complementary chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total aerosol scattering is demonstrated for different ambient conditions with a wide range of relative humidities (from 5 to 80%) using three types of data collected by the U.S. Department of Energy (DOE) G-1 aircraft during the recent Two-Column Aerosol Project (TCAP). Namely, these three types of data employed are: (1) size distributions measured by an Ultra High Sensitivity Aerosol Spectrometer (UHSAS; 0.06-1 µm), a Passive Cavity Aerosol Spectrometer (PCASP; 0.1-3 µm) and a Cloud and Aerosol Spectrometer (CAS; 0.6- >10 µm), (2) chemical composition data measured by an Aerosol Mass Spectrometer (AMS; 0.06-0.6 µm) and a Single Particle Soot Photometer (SP2; 0.06-0.6 µm), and (3) the dry total scattering coefficient measured by a TSI integrating nephelometer at three wavelengths (0.45, 0.55, 0.7 µm) and scattering enhancement factor measured with a humidification system at three RHs (near 45%, 65% and 90%) at a single wavelength (0.525 µm). We demonstrate that good agreement (~10% on average) between the observed and calculated scattering at these three wavelengths can be obtained using the best available chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction and using non-representative RI values can cause a substantial underestimation (~40

  4. Accurate method for measurement of pipe wall thickness using a circumferential guided wave generated and detected by a pair of noncontact transducers

    NASA Astrophysics Data System (ADS)

    Nishino, H.; Taniguchi, Y.; Yoshida, K.

    2012-05-01

    A noncontact method of an accurate estimation of a pipe wall thickness using a circumferential (C-) Lamb wave is presented. The C-Lamb waves circling along the circumference of pipes are transmitted and received by the critical angle method using a pair of noncontact air-coupled ultrasonic transducers. For the accurate estimation of a pipe wall thickness, the accurate measurement of the angular wave number that changes minutely owing to the thickness must be achieved. To achieve the accurate measurement, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This paper presents the principle of the method and experimental verifications. As results of the experimental verifications, it was confirmed that the maximum error between the estimates and the theoretical model was less than 10 micrometers.

  5. Accurate modeling of spectral fine-structure in Earth radiance spectra measured with the Global Ozone Monitoring Experiment.

    PubMed

    van Deelen, Rutger; Hasekamp, Otto P; Landgraf, Jochen

    2007-01-10

    We present what we believe to be a novel approach to simulating the spectral fine structure (<1 nm) in measurements of spectrometers such as the Global Ozone Monitoring Experiment (GOME). GOME measures the Earth's radiance spectra and daily solar irradiance spectra from which a reflectivity spectrum is commonly extracted. The high-frequency structures contained in such a spectrum are, apart from atmospheric absorption, caused by Raman scattering and by a shift between the solar irradiance and the Earth's radiance spectrum. Normally, an a priori high-resolution solar spectrum is used to simulate these structures. We present an alternative method in which all the required information on the solar spectrum is retrieved from the GOME measurements. We investigate two approaches for the spectral range of 390-400 nm. First, a solar spectrum is reconstructed on a fine spectral grid from the GOME solar measurement. This approach leads to undersampling errors of up to 0.5% in the modeling of the Earth's radiance spectra. Second, a combination of the solar measurement and one of the Earth's radiance measurement is used to retrieve a solar spectrum. This approach effectively removes the undersampling error and results in residuals close to the GOME measurement noise of 0.1%.

  6. Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography

    NASA Astrophysics Data System (ADS)

    Hussey, D. S.; Spernjak, D.; Weber, A. Z.; Mukundan, R.; Fairweather, J.; Brosha, E. L.; Davey, J.; Spendelow, J. S.; Jacobson, D. L.; Borup, R. L.

    2012-11-01

    The water sorption of proton-exchange membranes (PEMs) was measured in situ using high-resolution neutron imaging in small-scale fuel cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. An image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel cell and hydrogen-pump operation. The measured in situ water content of a restricted membrane at 80 °C is shown to agree with ex situ gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by in situ water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel cell operation, the measured water content indicates that the membrane is operating between the vapor- and liquid-equilibrated states.

  7. Measurements of the Temperature-Dependent Total Hemispherical Emissivity Using an Electrostatic Levitation Facility

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, A. K.; Kelton, K. F.

    2017-01-01

    Among the three fundamental processes of heat transfer (conduction, convection, and radiation), radiation is the most dominant at high temperatures. The total hemispherical emissivity is an important property that determines the amount of heat loss by radiation. Unfortunately, the emissivity, especially its temperature dependence (ɛ (T)), is unknown for most materials. Here, we demonstrate the feasibility of measuring ɛ (T) using an electrostatic levitation (ESL) technique that allows such measurements to be made on levitated solid and liquid samples in a contamination-free, high-vacuum environment. The ɛ (T) for solid Ni and liquid Zr_{60}Al_{10}Cu_{18}Ni9Co3 from these measurements is consistent with the existing literature data.

  8. Two Methods for Retrieving UV Index for All Cloud Conditions from Sky Imager Products or Total SW Radiation Measurements

    SciTech Connect

    Badosa, Jordi; Calbo, J.; McKenzie, R. L.; Liley, Ben; Gonzalez, J. A.; Forgan, B. W.; Long, Charles N.

    2014-07-01

    In the present study, we assess the cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover estimations and sunny conditions (from sky imaging products) as well as of solar zenith angle (SZA). These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (< 60%) and large SZA (> 60º). Similarly, clouds enhance TR more than UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: 1) from sky imaging cloud cover and sunny conditions, and 2) from TR measurements. Both methods may be used in practical operational applications, although Method 2 shows overall the best performance, since TR allows accounting for cloud optical properties. The mean absolute differences of Method 2 estimations with respect to measured values are 0.17 UVI units (for 1-minute data) and 0.79 Standard Erythemal Dose (SED) units (for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units and 1.6 SED.

  9. Two methods for retrieving UV index for all cloud conditions from sky imager products or total SW radiation measurements.

    PubMed

    Badosa, Jordi; Calbó, Josep; Mckenzie, Richard; Liley, Ben; González, Josep-Abel; Forgan, Bruce; Long, Charles N

    2014-01-01

    Cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover and sunny conditions (from sky images) as well as of solar zenith angle (SZA) are assessed. These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (<60%) and large SZA (>60°). Similarly, local short-time enhancement effects are stronger for TR than for UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: (1) from sky imaging cloud cover and sunny conditions, and (2) from TR measurements. Both methods may be used in practical applications, although Method 2 shows overall the best performance, as TR allows considering cloud optical properties. The mean absolute (relative) differences of Method 2 estimations with respect to measured values are 0.17 UVI units (6.7%, for 1 min data) and 0.79 Standard Erythemal Dose (SED) units (3.9%, for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units (15%) and 1.6 SED (8.0%).

  10. Total temperature probes for high-temperature hypersonic boundary-layer measurements

    NASA Technical Reports Server (NTRS)

    Albertson, Cindy W.; Bauserman, Willard A., Jr.

    1993-01-01

    The design and test results of two types of total temperature probes that were used for hypersonic boundary-layer measurements are presented. The intent of each design was to minimize the total error and to maintain minimal size for measurements in boundary layers 1.0 in. thick and less. A single platinum-20-percent-rhodium shield was used in both designs to minimize radiation heat transfer losses during exposure to the high-temperature test stream. The shield of the smaller design was flattened at the flow entrance to an interior height of 0.02 in., compared with 0.03 in. for the larger design. The resulting vent-to-inlet area ratios were 60 and 50 percent. A stainless steel structural support sleeve that was used in the larger design was excluded from the smaller design, which resulted in an outer diameter of 0.059 in., to allow closer placement of the probes to each other and to the wall. These small design changes to improve resolution did not affect probe performance. Tests were conducted at boundary-layer-edge Mach numbers of 5.0 and 6.2. The nominal free-stream total temperatures were 2600 degrees and 3200 degrees R. The probes demonstrated extremely good reliability. The best performance in terms of recovery factor occurred when the wire-based Nusselt number was at least 0.04. Recommendations for future probe designs are included.

  11. Finite Element Modelling of a Field-Sensed Magnetic Suspended System for Accurate Proximity Measurement Based on a Sensor Fusion Algorithm with Unscented Kalman Filter.

    PubMed

    Chowdhury, Amor; Sarjaš, Andrej

    2016-09-15

    The presented paper describes accurate distance measurement for a field-sensed magnetic suspension system. The p