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Sample records for potential gradient measurements

  1. Method and apparatus for determining the spontaneous earth potential log from downhole gradient measurements

    International Nuclear Information System (INIS)

    Maciejewski, W. J.

    1985-01-01

    A method and apparatus for measuring the differential or gradient of an earth variable within a well bore (e.g., the spontaneous earth potential) and producing improved logs of this gradient or differential and its integral variable essentially free of any accumulated instrument and base line drift or error. The differential spontaneous potential of an earth formation traversed by a well bore is measured at repeated multiple depths by moving a pair of closely spaced electrodes through the well bore wherein each electrode is electrically insulated externally from the other and from a third downhole local ground (such as the well tool cable) to which each is internally resistively referenced. The measured electrical potential across the closely spaced electrodes is amplified and digitized before being transmitted to the earth's surface, whereupon an averaged value of such differential measurements within a traveling data window of predetermined length and adjacent to each successive measurement is used to adjust for base line drift, noise and instrument induced error. The resulting compensated differential logs are integrated, resulting in spontaneous potential logs of improved character

  2. Unfolding of hemoglobin variants--insights from urea gradient gel electrophoresis photon correlation spectroscopy and zeta potential measurements

    International Nuclear Information System (INIS)

    Bhattacharya, Jaydeep; GhoshMoulick, Ranjita; Choudhuri, Utpal; Chakrabarty, Prantar; Bhattacharya, Pranab K.; Lahiri, Prabir; Chakraborti, Bikas; Dasgupta, Anjan Kr.

    2004-01-01

    The unfolding pattern of crystal human hemoglobin and variants of hemoglobin obtained from hemolysate were studied using transverse urea gradient gel electrophoresis (TUGGE). A smooth sigmoid like increase of electrophoretic mobility was observed with increasing urea concentrations. A decrease in electrophoretic mobility resulted, if the protein was unfolded with guanidium hydrochloride (GdnHCl). The anomaly was resolved after the Stoke's radii (obtained using the photon correlation spectroscopy) and zeta potential (measured using laser Doppler velocimetry) measurements were made at different denaturant concentrations. Addition of denaturant led to formation of extended structure, irrespective of the nature of the denaturant, as indicated by increase in Stoke's radii in both cases (urea and GdnHCl). The unexpected increase in electrophoretic mobility in case of urea could be explained in terms of a critical redistribution of negative charge at intermediate stages of the unfolding process. In case of GdnHCl, the higher ionic strength masked the charge effect. The mobility, being solely dependent on size, decreased at higher denaturant concentration. Incidentally, folding loci of other hemoglobin variants (e.g. HbE) or that of post-translationally modified hemoglobin (e.g. HbA1c) could be determined by studying the charge distribution and hydrodynamic radius at varying denaturing stress and in each case the gel migration profile could be approximately scaled by the ratio of charge and hydrodynamic diameter of the protein. While unfolding induced charge effect was most pronounced in HbA0 (and crystal ferrous hemoglobin), the unfolding induced aggregation (manifested by the increase in Stoke's radii) was predominantly observed in the variant forms HbE and HbA1c. Representing the proteins by a plot, in which charge and hydrodynamic diameter are on independent axes, may be a useful way of characterizing protein variants having similar migration profiles on native gels

  3. Unfolding of hemoglobin variants--insights from urea gradient gel electrophoresis photon correlation spectroscopy and zeta potential measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Jaydeep; GhoshMoulick, Ranjita; Choudhuri, Utpal; Chakrabarty, Prantar; Bhattacharya, Pranab K.; Lahiri, Prabir; Chakraborti, Bikas; Dasgupta, Anjan Kr

    2004-09-27

    The unfolding pattern of crystal human hemoglobin and variants of hemoglobin obtained from hemolysate were studied using transverse urea gradient gel electrophoresis (TUGGE). A smooth sigmoid like increase of electrophoretic mobility was observed with increasing urea concentrations. A decrease in electrophoretic mobility resulted, if the protein was unfolded with guanidium hydrochloride (GdnHCl). The anomaly was resolved after the Stoke's radii (obtained using the photon correlation spectroscopy) and zeta potential (measured using laser Doppler velocimetry) measurements were made at different denaturant concentrations. Addition of denaturant led to formation of extended structure, irrespective of the nature of the denaturant, as indicated by increase in Stoke's radii in both cases (urea and GdnHCl). The unexpected increase in electrophoretic mobility in case of urea could be explained in terms of a critical redistribution of negative charge at intermediate stages of the unfolding process. In case of GdnHCl, the higher ionic strength masked the charge effect. The mobility, being solely dependent on size, decreased at higher denaturant concentration. Incidentally, folding loci of other hemoglobin variants (e.g. HbE) or that of post-translationally modified hemoglobin (e.g. HbA1c) could be determined by studying the charge distribution and hydrodynamic radius at varying denaturing stress and in each case the gel migration profile could be approximately scaled by the ratio of charge and hydrodynamic diameter of the protein. While unfolding induced charge effect was most pronounced in HbA0 (and crystal ferrous hemoglobin), the unfolding induced aggregation (manifested by the increase in Stoke's radii) was predominantly observed in the variant forms HbE and HbA1c. Representing the proteins by a plot, in which charge and hydrodynamic diameter are on independent axes, may be a useful way of characterizing protein variants having similar migration profiles on

  4. Measurement of gradient magnetic field temporal characteristics

    International Nuclear Information System (INIS)

    Bartusek, K.; Jflek, B.

    1994-01-01

    We describe a technique of measuring the time dependence and field distortions of magnetic fields due to eddy currents (EC) produced by time-dependent magnetic field gradients. The EC measuring technique makes use of a large volume sample and selective RF excitation pulses and free induction decay (FID) (or a spin or gradient echo) to measure the out-of-phase component of the FID, which is proportional to γδB, i.e. the amount the signal is off resonance. The measuring technique is sensitive, easy to implement and interpret, and used for determining pre-emphasis compensation parameters

  5. Is splash erosion potential species specific? Measuring of splash erosion potential under forest in different succession stages along a biodiversity gradient in the humid subtropics

    Science.gov (United States)

    Geißler, C.; Kühn, P.; Scholten, T.

    2009-04-01

    It is widely accepted that (forest) vegetation is a key control for the type and intensity of soil erosion. The current paradigm is that natural or quasi-natural vegetation protects the soil from erosion and that agricultural vegetation or land use generally enhances erosion. The latter was in focus of most research during the last decades and less interest was paid on natural systems, which are more difficult to study. Nevertheless, afforestation is widely used as a measure of soil protection against soil erosion. Rainfall can be highly erosive particularly in the humid subtropics. Regarding climate change, also precipitation regime may change in direction to even more severe storms and higher rainfall intensities; it is a research field of growing importance. Key mechanisms of a vegetation cover in reducing or enhancing erosion are modifications of drop-size distribution, retention of raindrop impact on the soil and changes in amount and spatial distribution of rainfall at the ground surface. Controlling determinants are rainfall intensity, drop size distribution, drop fall velocity, height of the canopy as well as density of the canopy, crown and leaf traits, LAI and coverage by a litter layer. Large drops are supposed to be significant sources of splash detachment in forests (Brandt 1989; Vis 1986). However, the mechanisms of reducing (or enhancing?) splash detachment under forest in relation to species richness and species composition are not well understood. Some studies indicate that raindrop impact is species specific (Calder 2001; Nanko et al. 2006) and some neglect the effects of species specific impacts (Foot & Morgan 2005). Our research uses different methods of rainfall characterization (splash cups, tipping-bucket rain gauge, laser distrometer) to reveal the described mechanisms from the canopy through different vegetation layers to the ground. First results of splash cup measurements (revised after Ellison 1947) show that sand loss under vegetation

  6. Density gradients in ceramic pellets measured by computed tomography

    International Nuclear Information System (INIS)

    Sawicka, B.D.; Palmer, B.J.F.

    1986-07-01

    Density gradients are of fundamental importance in ceramic processing and computed tomography (CT) can provide accurate measurements of density profiles in sintered and unsintered ceramic parts. As a demonstration of this potential, the density gradients in an unsintered pellet pressed from an alumina powder were measured by CT scanning. To detect such small density gradients, the CT images must have good density resolution and be free from beam-hardening effects. This was achieved by measuring high-contrast (low-noise) images with the use of an Ir-192 isotopic source. A beam-hardening correction was applied. The resulting images are discussed relative to the transmission of forces through the powder mass during the pelletizing process

  7. Gradient Measurements of Nitrous Acid (hono)

    Science.gov (United States)

    Kleffmann, J.; Kurtenbach, R.; Lörzer, J.; Wiesen, P.; Kalthoff, N.; Vogel, B.; Vogel, H.

    Nitrous acid (HONO) plays an important role in photochemical air pollution due to its photodissociation by solar UV radiation into hydroxyl radicals and thus significantly enhances photooxidation processes. Furthermore, HONO is an important indoor pol- lutant, which can react with amines leading to nitrosamines, which are known to be carcinogenic. Despite its importance in atmospheric chemistry the mechanisms lead- ing to HONO formation are still not completely understood at present. Although it is commonly proposed that HONO is formed by heterogeneous processes, i.e. by the conversion of NO2 on wet surfaces, it is still under discussion whether HONO produc- tion is dominated by the surface of particles or by the ground surface. Simultaneous vertical profile measurements of HONO, the precursor NO2 and the aerosol surface area, which could answer this question are not available at present. Accordingly, in the present study night-time HONO, NO2 and particle surface area gradients in the altitude range 10-190 m were measured on the meteorological tower at the Forschungszentrum Karlsruhe/Germany using a new, very sensitive HONO in- strument (LOPAP), a commercial NOx monitor and a SMPS system. For all gradient measurements during the campaign it was observed that the [HONO]/[NO2] ratio decreased with increasing altitude. In contrast, the particle sur- face area was found to be more or less constant. Accordingly, no correlation between the [HONO]/[NO2] ratio and the particle surface area was observed showing that HONO formation was dominated by processes on ground surfaces and that signifi- cant HONO formation on particle surfaces could be excluded for the measurement site.

  8. The Potential of Tropospheric Gradients for Regional Precipitation Prediction

    Science.gov (United States)

    Boisits, Janina; Möller, Gregor; Wittmann, Christoph; Weber, Robert

    2017-04-01

    Changes of temperature and humidity in the neutral atmosphere cause variations in tropospheric path delays and tropospheric gradients. By estimating zenith wet delays (ZWD) and gradients using a GNSS reference station network the obtained time series provide information about spatial and temporal variations of water vapour in the atmosphere. Thus, GNSS-based tropospheric parameters can contribute to the forecast of regional precipitation events. In a recently finalized master thesis at TU Wien the potential of tropospheric gradients for weather prediction was investigated. Therefore, ZWD and gradient time series at selected GNSS reference stations were compared to precipitation data over a period of six months (April to September 2014). The selected GNSS stations form two test areas within Austria. All required meteorological data was provided by the Central Institution for Meteorology and Geodynamics (ZAMG). Two characteristics in ZWD and gradient time series can be anticipated in case of an approaching weather front. First, an induced asymmetry in tropospheric delays results in both, an increased magnitude of the gradient and in gradients pointing towards the weather front. Second, an increase in ZWD reflects the increased water vapour concentration right before a precipitation event. To investigate these characteristics exemplary test events were processed. On the one hand, the sequence of the anticipated increase in ZWD at each GNSS station obtained by cross correlation of the time series indicates the direction of the approaching weather front. On the other hand, the corresponding peak in gradient time series allows the deduction of the direction of movement as well. To verify the results precipitation data from ZAMG was used. It can be deduced, that tropospheric gradients show high potential for predicting precipitation events. While ZWD time series rather indicate the orientation of the air mass boundary, gradients rather indicate the direction of movement

  9. Full magnetic gradient tensor from triaxial aeromagnetic gradient measurements: Calculation and application

    Science.gov (United States)

    Luo, Yao; Wu, Mei-Ping; Wang, Ping; Duan, Shu-Ling; Liu, Hao-Jun; Wang, Jin-Long; An, Zhan-Feng

    2015-09-01

    The full magnetic gradient tensor (MGT) refers to the spatial change rate of the three field components of the geomagnetic field vector along three mutually orthogonal axes. The tensor is of use to geological mapping, resources exploration, magnetic navigation, and others. However, it is very difficult to measure the full magnetic tensor gradient using existing engineering technology. We present a method to use triaxial aeromagnetic gradient measurements for deriving the full MGT. The method uses the triaxial gradient data and makes full use of the variation of the magnetic anomaly modulus in three dimensions to obtain a self-consistent magnetic tensor gradient. Numerical simulations show that the full MGT data obtained with the proposed method are of high precision and satisfy the requirements of data processing. We selected triaxial aeromagnetic gradient data from the Hebei Province for calculating the full MGT. Data processing shows that using triaxial tensor gradient data allows to take advantage of the spatial rate of change of the total field in three dimensions and suppresses part of the independent noise in the aeromagnetic gradient. The calculated tensor components have improved resolution, and the transformed full tensor gradient satisfies the requirement of geological mapping and interpretation.

  10. Biological amine transport in chromaffin ghosts. Coupling to the transmembrane proton and potential gradients.

    Science.gov (United States)

    Johnson, R G; Pfister, D; Carty, S E; Scarpa, A

    1979-11-10

    The effect of the transmembrane proton gradient (delta pH) and potential gradient (delta psi) upon the rate and extent of amine accumulation was investigated in chromaffin ghosts. The chromaffin ghosts were formed by hypo-osmotic lysis of isolated bovine chromaffin granules and extensive dialysis in order to remove intragranular binding components and dissipate the endogenous electrochemical gradients. Upon ATP addition to suspensions of chromaffin ghosts, a transmembrane proton gradient alone, a transmembrane gradient alone, or both, could be established, depending upon the compositions of the media in which the ghosts were formed and resuspended. When chloride was present in the medium, addition of ATP resulted in the generation of a transmembrane proton gradient, acidic inside of 1 pH unit (measured by [14C]methylamine distribution), and no transmembrane potential (measured by [14C]-thiocyanate distribution). When ATP was added to chromaffin ghosts suspended in a medium in which chloride was substituted by isethionate, a transmembrane potential, inside positive, of 45 mV and no transmembrane proton gradient, was measured. In each medium, the addition of agents known to affect proton or potential gradients, respectively, exerted a predictable mechanism of action. Accumulation of [14C]epinephrine or [14C]5-hydroxytryptamine was over 1 order of magnitude greater in the presence of the transmembrane proton gradient or the transmembrane potential than in the absence of any gradient and, moreover, was related to the magnitude of the proton or potential gradient in a dose-dependent manner. When ghosts were added to a medium containing chloride and isethionate, both a delta pH and delta psi could be generated upon addition of ATP. In this preparation, the maximal rate of amine accumulation was observed. The results indicate that amine accumulation into chromaffin ghosts can occur in the presence of either a transmembrane proton gradient, or a transmembrane potential

  11. Monitoring of the Proton Electrochemical Gradient in Reconstituted Vesicles: Quantitative Measurements of Both Transmembrane Potential and Intravesicular pH by Ratiometric Fluorescent Probes

    Czech Academy of Sciences Publication Activity Database

    Holoubek, A.; Večeř, J.; Sigler, Karel

    2007-01-01

    Roč. 17, - (2007), s. 201-213 ISSN 1053-0509 Institutional research plan: CEZ:AV0Z50200510 Keywords : transmembrane potential * intracellular ph * oxonol dyes Subject RIV: EE - Microbiology, Virology Impact factor: 2.101, year: 2007

  12. Measurement of carotid bifurcation pressure gradients using the Bernoulli principle.

    Science.gov (United States)

    Illig, K A; Ouriel, K; DeWeese, J A; Holen, J; Green, R M

    1996-04-01

    Current randomized prospective studies suggest that the degree of carotid stenosis is a critical element in deciding whether surgical or medical treatment is appropriate. Of potential interest is the actual pressure drop caused by the blockage, but no direct non-invasive means of quantifying the hemodynamic consequences of carotid artery stenoses currently exists. The present prospective study examined whether preoperative pulsed-Doppler duplex ultrasonographic velocity (v) measurements could be used to predict pressure gradients (delta P) caused by carotid artery stenoses, and whether such measurements could be used to predict angiographic percent diameter reduction. Preoperative Doppler velocity and intraoperative direct pressure measurements were obtained, and per cent diameter angiographic stenosis measured in 76 consecutive patients who underwent 77 elective carotid endarterectomies. Using the Bernoulli principle (delta P = 4v(2), pressure gradients across the stenoses were calculated. The predicted delta P, as well as absolute velocities and internal carotid artery/common carotid velocity ratios were compared with the actual delta P measured intraoperatively and with preoperative angiography and oculopneumoplethysmography (OPG) results. An end-diastolic velocity of > or = 1 m/s and an end-diastolic internal carotid artery/common carotid artery velocity ratio of > or = 10 predicted a 50% diameter angiographic stenosis with 100% specificity. Although statistical significance was reached, preoperative pressure gradients derived from the Bernoulli equation could not predict actual individual intraoperative pressure gradients with enough accuracy to allow decision making on an individual basis. Velocity measurements were as specific and more sensitive than OPG results. Delta P as predicted by the Bernoulli equation is not sufficiently accurate at the carotid bifurcation to be useful for clinical decision making on an individual basis. However, end

  13. Hepatic venous pressure gradients measured by duplex ultrasound

    International Nuclear Information System (INIS)

    Tasu, J.-P.; Rocher, L.; Peletier, G.; Kuoch, V.; Kulh, E.; Miquel, A.; Buffet, C.; Biery, M.

    2002-01-01

    AIMS: The hepatic venous pressure gradient is a major prognostic factor in portal hypertension but its measurement is complex and requires invasive angiography. This study investigated the relationship between the hepatic venous pressure gradient and a number of Doppler measurements, including the arterial acceleration index. METHOD: We measured the hepatic venous pressure gradient in 50 fasting patients at hepatic venography. Immediately afterwards, a duplex sonographic examination of the liver was performed at which multiple measurements and indices of the venous and arterial hepatic vasculature were made. RESULTS: Hepatic arterial acceleration was correlated directly with the hepatic venous pressure gradient (r = 0.83, P -2 provided a positive predictive value of 95%, a sensitivity of 65% and a specificity of 95% for detecting patients with severe portal hypertension (hepatic venous pressure gradient > 12 mmHg). A correlation between the hepatic venous pressure gradient and the congestion index of the portal vein velocity (r = 0.45,P = 0.01) and portal vein velocity (r = 0.40,P = 0.044), was also noted. CONCLUSION: Measuring the hepatic arterial acceleration index may help in the non-invasive evaluation of portal hypertension. Tasu, J.-P. et al. (2002)

  14. Hepatic venous pressure gradients measured by duplex ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Tasu, J.-P.; Rocher, L.; Peletier, G.; Kuoch, V.; Kulh, E.; Miquel, A.; Buffet, C.; Biery, M

    2002-08-01

    AIMS: The hepatic venous pressure gradient is a major prognostic factor in portal hypertension but its measurement is complex and requires invasive angiography. This study investigated the relationship between the hepatic venous pressure gradient and a number of Doppler measurements, including the arterial acceleration index. METHOD: We measured the hepatic venous pressure gradient in 50 fasting patients at hepatic venography. Immediately afterwards, a duplex sonographic examination of the liver was performed at which multiple measurements and indices of the venous and arterial hepatic vasculature were made. RESULTS: Hepatic arterial acceleration was correlated directly with the hepatic venous pressure gradient (r = 0.83, P < 0.0001) and with the Child-Pugh score (r = 0.63, P < 0.0001). An acceleration index cut-off value of 1 m.s{sup -2} provided a positive predictive value of 95%, a sensitivity of 65% and a specificity of 95% for detecting patients with severe portal hypertension (hepatic venous pressure gradient > 12 mmHg). A correlation between the hepatic venous pressure gradient and the congestion index of the portal vein velocity (r = 0.45,P = 0.01) and portal vein velocity (r = 0.40,P = 0.044), was also noted. CONCLUSION: Measuring the hepatic arterial acceleration index may help in the non-invasive evaluation of portal hypertension. Tasu, J.-P. et al. (2002)

  15. MEASURING LOCAL GRADIENT AND SKEW QUADRUPOLE ERRORS IN RHIC IRS

    International Nuclear Information System (INIS)

    CARDONA, J.; PEGGS, S.; PILAT, R.; PTITSYN, V.

    2004-01-01

    The measurement of local linear errors at RHIC interaction regions using an ''action and phase'' analysis of difference orbits has already been presented [2]. This paper evaluates the accuracy of this technique using difference orbits that were taken when known gradient errors and skew quadrupole errors were intentionally introduced. It also presents action and phase analysis of simulated orbits when controlled errors are intentionally placed in a RHIC simulation model

  16. A hybrid two-component Bose–Einstein condensate interferometer for measuring magnetic field gradients

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Fei [Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China); Huang, Jiahao, E-mail: hjiahao@mail2.sysu.edu.cn [TianQin Research Center & School of Physics and Astronomy, Sun Yat-Sen University, SYSU Zhuhai Campus, Zhuhai 519082 (China); Liu, Quan [Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China)

    2017-03-03

    Highlights: • A scheme for detecting magnetic field gradients via a double-well two-component Bose–Einstein condensate interferometer. • The magnetic field gradient can be extracted by either the spin population or the external state. • Our proposal is potentially sensitive to weak magnetic field inhomogeneity due to its small sensor size. - Abstract: We have proposed a scheme to detect magnetic field gradients via an interferometer based on a double-well two-component Bose–Einstein condensate (BEC). Utilizing a sequence of quantum control operations on both external and internal degree of the BEC, one can extract the magnetic field gradients by measuring either the population in one component or the fidelity between the final external state and the initial ground state. Our scheme can be implemented by current experimental techniques of manipulating ultracold atoms.

  17. COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES

    International Nuclear Information System (INIS)

    BAKER, DR; STAEBLER, GM; PETTY, CC; GREENFIELD, CM; LUCE, TC

    2003-01-01

    OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which are centrally heated tend to increase in temperature gradient until the modes become unstable. Under some conditions the increased transport can fix the gradient at the critical value. here they present a comparison between the measured ion temperature gradients and the critical gradient as calculated by a gyrokinetic linear stability (GKS) code. They also present the maximum linear growth rate as calculated by this code for comparison to experimentally derived transport coefficients. The results show that for low confinement mode (L-mode) discharges, the measured ion temperature gradient is significantly greater than the GKS calculated critical gradient over a large region of the plasma. This is the same region of the plasma where the ion thermal diffusivity is large. For high confinement mode (H-mode) discharges the ion temperature gradient is closer to the critical gradient, but often still greater than the critical gradient over some region. For the best H-mode discharges, the ion temperature is less than or equal to the critical gradient over the whole plasma. In general they find that the position in the plasma where the ion thermal diffusivity starts to increase rapidly is where the maximum linear growth rate is greater than the E x B shearing rate

  18. Utilization of a pressure sensor guidewire to measure bileaflet mechanical valve gradients: hemodynamic and echocardiographic sequelae.

    Science.gov (United States)

    Doorey, Andrew J; Gakhal, Mandip; Pasquale, Michael J

    2006-04-01

    Suspected prosthetic valve dysfunction is a difficult clinical problem, because of the high risk of repeat valvular surgery. Echocardiographic measurements of prosthetic valvular dysfunction can be misleading, especially with bileaflet valves. Direct measurement of trans-valvular gradients is problematic because of potentially serious catheter entrapment issues. We report a case in which a high-fidelity pressure sensor angioplasty guidewire was used to cross prosthetic mitral and aortic valves in a patient, with hemodynamic and echocardiographic assessment. This technique was safe and effective, refuting the inaccurate non-invasive tests that over-estimated the aortic valvular gradient.

  19. Measured longitudinal beam impedance of booster gradient magnets; TOPICAL

    International Nuclear Information System (INIS)

    James L Crisp and Brian J. Fellenz

    2001-01-01

    The Booster gradient magnets have no vacuum pipe which forces the beam image current to flow along the laminated pole tips. Both D and F style magnets were measured with a stretched wire to determine the longitudinal beam impedance caused by these laminations. Results are compared to calculations done 30 years ago. The inductive part of the magnet impedance is interesting because it partially compensates for the negative inductance effects of space charge on the beam. An R/L circuit consisting of 37K(center d ot) in parallel with between 40 and 100uH is a reasonable approximation to the total impedance of Booster magnet laminations

  20. Directed transport by surface chemical potential gradients for enhancing analyte collection in nanoscale sensors.

    Science.gov (United States)

    Sitt, Amit; Hess, Henry

    2015-05-13

    Nanoscale detectors hold great promise for single molecule detection and the analysis of small volumes of dilute samples. However, the probability of an analyte reaching the nanosensor in a dilute solution is extremely low due to the sensor's small size. Here, we examine the use of a chemical potential gradient along a surface to accelerate analyte capture by nanoscale sensors. Utilizing a simple model for transport induced by surface binding energy gradients, we study the effect of the gradient on the efficiency of collecting nanoparticles and single and double stranded DNA. The results indicate that chemical potential gradients along a surface can lead to an acceleration of analyte capture by several orders of magnitude compared to direct collection from the solution. The improvement in collection is limited to a relatively narrow window of gradient slopes, and its extent strongly depends on the size of the gradient patch. Our model allows the optimization of gradient layouts and sheds light on the fundamental characteristics of chemical potential gradient induced transport.

  1. Structure of the optimized effective Kohn-Sham exchange potential and its gradient approximations

    International Nuclear Information System (INIS)

    Gritsenko, O.; Van Leeuwen, R.; Baerends, E.J.

    1996-01-01

    An analysis of the structure of the optimized effective Kohn-Sham exchange potential v, and its gradient approximations is presented. The potential is decomposed into the Slater potential v s and the response of v s to density variations, v resp . The latter exhibits peaks that reflect the atomic shell structure. Kohn-Sham exchange potentials derived from current gradient approaches for the exchange energy are shown to be quite reasonable for the Slater potential, but they fail to approximate the response part, which leads to poor overall potentials. Improved potentials are constructed by a direct fit of v x with a gradient-dependent Pade approximant form. The potentials obtained possess proper asymptotic and scaling properties and reproduce the shell structure of the exact v x . 44 refs., 7 figs., 4 tabs

  2. Microgravimetry and the Measurement and Application of Gravity Gradients,

    Science.gov (United States)

    1980-06-01

    Neumann, R., 1972, High precision gravimetry--recent develop- ments: Report to Paris Commission of E.A.E.G., Compagnie Generale de Geophysique , Massy...experimentation on vertical gradient: Compagnie Generale de Geophysique , Massy, France. 12. Fajklewicz, Z. J., 1976, Gravity vertical gradient

  3. The potentially neglected culprit of DC surface flashover: electron migration under temperature gradients.

    Science.gov (United States)

    Li, Chuanyang; Hu, Jun; Lin, Chuanjie; He, Jinliang

    2017-06-12

    This report intends to reveal the role of electron migration and its effects in triggering direct current (DC) surface flashover under temperature gradient conditions when using epoxy-based insulating composites. The surface potential and the surface flashover voltage are both measured using insulators that are bridged between two thermo-regulated electrodes. The space charge injection and migration properties under different temperature are detected. The results show that the surface potential rises significantly because of electron migration near the high voltage (HV) electrode under high temperature conditions, thus creating an "analogous ineffective region". The expansion of this "analogous ineffective region" results in most of the voltage drop occurring near the ground electrode, which serves as an important factor triggering positive streamers across the insulation surface. This work is helpful in understanding of DC surface flashover mechanism from a new perspective and also has important significance in design of a suitable DC insulator to avoid surface flashover problem.

  4. Plasma gradient effects on double-probe measurements in the magnetosphere

    Directory of Open Access Journals (Sweden)

    H. Laakso

    1995-02-01

    Full Text Available The effects on double-probe electric field measurements induced by electron density and temperature gradients are investigated. We show that on some occasions such gradients may lead to marked spurious electric fields if the probes are assumed to lie at the same probe potential with respect to the plasma. The use of a proper bias current will decrease the magnitude of such an error. When the probes are near the plasma potential, the magnitude of these error signals, ∆E, can vary as ∆E ~ Te(∆ne/ne+0.5∆Te, where Te is the electron temperature, ∆ne/ne the relative electron density variation between the two sensors, and ∆Te the electron temperature difference between the two sensors. This not only implies that the error signals will increase linearly with the density variations but also that such signatures grow with Te, i.e., such effects are 10 times larger in a 10-eV plasma than in a 1-eV plasma. This type of error is independent of the probe separation distance provided the gradient scale length is much larger than this distance. The largest errors occur when the probes are near to the plasma potential. At larger positive probe potentials with respect to the plasma potential, the error becomes smaller if the probes are biased, as is usually the case with spherical double-probe experiments in the tenuous magnetospheric plasmas. The crossing of a plasma boundary (like the plasmapause or magnetopause yields an error signal of a single peak. During the crossing of a small structure (e.g., a double layer the error signal appears as a bipolar signature. Our analysis shows that errors in double-probe measurements caused by plasma gradients are not significant at large scale (»1 km plasma boundaries, and may only be important in cases where small-scale (<1 km, internal gradient structures exist. Bias currents tailored for each plasma parameter regime (i.e., variable bias current would o1q1improve the double-probe response to gradient

  5. A Rotation Measure Gradient on the M87 VLA Jet

    Directory of Open Access Journals (Sweden)

    Algaba Juan Carlos

    2013-12-01

    Full Text Available Rotation measures (RMs have proven to be an excellent tool to study magnetic field structures in AGNs. Here we study RM properties on kiloparsec scales of theM87 jet via stacked multi wavelength polarized VLA observations. Our results show for the first time an indication of the RM gradient transverse to the jet in knot A, and possibly knot C and HST-1. Motivated by the shape of the RM in knots A and B, we discuss that part of it may be a filamentary structure of higher RM due to an external Faraday screen, although we consider this unlikely The data presented here can be easily explained by a helical magnetic field. By combining this result together with polarization direction plus the shape and degree of the fractional polarization across the jet, we can fairly conclude the presence of systematically wrapped, possibly helical, magnetic fields tightly wounded in knots A and C, in agreement with an MHD quad shock model.

  6. Measurement of water vapour transport through a porous non-hygroscopic material in a temperature gradient

    DEFF Research Database (Denmark)

    Hansen, Thor; Padfield, Tim; Hansen, Kurt Kielsgaard

    2014-01-01

    This was an experiment to identify the driving potential for water vapour diffusion through porous materials in a temperature gradient. The specimen of mineral fibre insulation was placed between a space with controlled temperature and relative humidity and a space with a controlled, higher...... temperature, and a measured but not controlled relative humidity (RH). This assembly was allowed to reach equilibrium with no vapour movement between the spaces, as tested by a constant RH on each side and by zero flux of water vapour measured in the cold side chamber. The RH and temperature values were...

  7. A measurement of the local ion temperature gradient in the PLT tokamak

    International Nuclear Information System (INIS)

    Lovberg, J.A.; Strachan, J.D.; Princeton Univ., NJ

    1989-12-01

    Local ion temperature gradients were measured at two radial positions in the PLT tokamak by counting escaping d(d,p)t protons on orbits at closely spaced intervals. A single surface barrier detector was used to make each gradient measurement, eliminating relative calibration uncertainties. The ion thermal diffusivities inferred through ion energy balance with the measured temperature gradients are within a factor of two of Chang-Hinton neoclassical values for the 3 He-minority ICRH plasmas. 12 refs., 8 figs

  8. The Exit Gradient As a Measure of Groundwater Dependency of Watershed Ecosystem Services

    Science.gov (United States)

    Faulkner, B. R.; Canfield, T. J.; Justin, G. F.

    2014-12-01

    Flux of groundwater to surface water is often of great interest for the determination of the groundwater dependency of ecosystem services, such as maintenance of wetlands and of baseflow as a contributor to stream channel storage. It is difficult to measure. Most methods are based on coarse mass balance estimates or seepage meters. One drawback of these methods is they are not entirely spatially explicit. The exit gradient is commonly used in engineering studies of hydraulic structures affected by groundwater flow. It can be simply defined in the groundwater modeling context as the ratio of the difference between the computed head and the land surface elevation, for each computational cell, to the thickness of the cell, as it varies in space. When combined with calibrated groundwater flow models, it also has the potential to be useful in watershed scale evaluations of groundwater dependency in a spatially explicit way. We have taken advantage of calibrated models for the Calapooia watershed, Oregon, to map exit gradients for the watershed. Streams in the Calapooia are hydraulically well connected with groundwater. Not surprisingly, we found large variations in exit gradients between wet and dry season model runs, supporting the notion of stream expansion, as observed in the field, which may have a substantial influence on water quality. We have mapped the exit gradients in the wet and dry seasons, and compared them to regions which have been mapped in wetland surveys. Those classified as Palustrine types fell largest in the area of contribution from groundwater. In many cases, substantially high exit gradients, even on average, did not correspond to mapped wetland areas, yet nutrient retention ecosystem services may still be playing a role in these areas. The results also reinforce the notion of the importance of baseflow to maintenance of stream flow, even in the dry summer season in this Temperate/Mediterranean climate. Exit gradient mapping is a simple, yet

  9. Fuzzy logic-based assessment for mapping potential infiltration areas in low-gradient watersheds.

    Science.gov (United States)

    Quiroz Londoño, Orlando Mauricio; Romanelli, Asunción; Lima, María Lourdes; Massone, Héctor Enrique; Martínez, Daniel Emilio

    2016-07-01

    This paper gives an account of the design a logic-based approach for identifying potential infiltration areas in low-gradient watersheds based on remote sensing data. This methodological framework is applied in a sector of the Pampa Plain, Argentina, which has high level of agricultural activities and large demands for groundwater supplies. Potential infiltration sites are assessed as a function of two primary topics: hydrologic and soil conditions. This model shows the state of each evaluated subwatershed respecting to its potential contribution to infiltration mainly based on easily measurable and commonly used parameters: drainage density, geomorphologic units, soil media, land-cover, slope and aspect (slope orientation). Mapped outputs from the logic model displayed 42% very low-low, 16% moderate, 41% high-very high contribution to potential infiltration in the whole watershed. Subwatersheds in the upper and lower section were identified as areas with high to very high potential infiltration according to the following media features: low drainage density (drainage plain and, dunes and beaches. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Characterization of two-scale gradient Young measures and application to homogenization

    OpenAIRE

    Babadjian, Jean-Francois; Baia, Margarida; Santos, Pedro M.

    2006-01-01

    This work is devoted to the study of two-scale gradient Young measures naturally arising in nonlinear elasticity homogenization problems. Precisely, a characterization of this class of measures is derived and an integral representation formula for homogenized energies, whose integrands satisfy very weak regularity assumptions, is obtained in terms of two-scale gradient Young measures.

  11. A gradient approximation for calculating Debye temperatures from pairwise interatomic potentials

    International Nuclear Information System (INIS)

    Jackson, D.P.

    1975-09-01

    A simple gradient approximation is given for calculating the effective Debye temperature of a cubic crystal from central pairwise interatomic potentials. For examples of the Morse potential applied to cubic metals the results are in generally good agreement with experiment. (author)

  12. Measure Your Gradient”: A New Way to Measure Gradients in High Performance Liquid Chromatography by Mass Spectrometric or Absorbance Detection

    Science.gov (United States)

    Magee, Megan H.; Manulik, Joseph C.; Barnes, Brian B.; Abate-Pella, Daniel; Hewitt, Joshua T.; Boswell, Paul G.

    2014-01-01

    The gradient produced by an HPLC is never the same as the one it is programmed to produce, but non-idealities in the gradient can be taken into account if they are measured. Such measurements are routine, yet only one general approach has been described to make them: both HPLC solvents are replaced with water, solvent B is spiked with 0.1% acetone, and the gradient is measured by UV absorbance. Despite the widespread use of this procedure, we found a number of problems and complications with it, mostly stemming from the fact that it measures the gradient under abnormal conditions (e.g. both solvents are water). It is also generally not amenable to MS detection, leaving those with only an MS detector no way to accurately measure their gradients. We describe a new approach called “Measure Your Gradient” that potentially solves these problems. One runs a test mixture containing 20 standards on a standard stationary phase and enters their gradient retention times into open-source software available at www.measureyourgradient.org. The software uses the retention times to back-calculate the gradient that was truly produced by the HPLC. Here we present a preliminary investigation of the new approach. We found that gradients measured this way are comparable to those measured by a more accurate, albeit impractical, version of the conventional approach. The new procedure worked with different gradients, flow rates, column lengths, inner diameters, on two different HPLCs, and with six different batches of the standard stationary phase. PMID:25441073

  13. A rapid and robust gradient measurement technique using dynamic single-point imaging.

    Science.gov (United States)

    Jang, Hyungseok; McMillan, Alan B

    2017-09-01

    We propose a new gradient measurement technique based on dynamic single-point imaging (SPI), which allows simple, rapid, and robust measurement of k-space trajectory. To enable gradient measurement, we utilize the variable field-of-view (FOV) property of dynamic SPI, which is dependent on gradient shape. First, one-dimensional (1D) dynamic SPI data are acquired from a targeted gradient axis, and then relative FOV scaling factors between 1D images or k-spaces at varying encoding times are found. These relative scaling factors are the relative k-space position that can be used for image reconstruction. The gradient measurement technique also can be used to estimate the gradient impulse response function for reproducible gradient estimation as a linear time invariant system. The proposed measurement technique was used to improve reconstructed image quality in 3D ultrashort echo, 2D spiral, and multi-echo bipolar gradient-echo imaging. In multi-echo bipolar gradient-echo imaging, measurement of the k-space trajectory allowed the use of a ramp-sampled trajectory for improved acquisition speed (approximately 30%) and more accurate quantitative fat and water separation in a phantom. The proposed dynamic SPI-based method allows fast k-space trajectory measurement with a simple implementation and no additional hardware for improved image quality. Magn Reson Med 78:950-962, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. Measurement of gradient index profiles by Babinet fringe analysis.

    Science.gov (United States)

    Pandya, T P; Saxena, A K

    1979-03-01

    A theory for determining one-dimensional ray deflections with the help of distorted Babinet fringes has been developed. An approach for investigating two-dimensional ray deflections has been presented. Applications of the techniques for the study of gradient index glass have been described.

  15. Measurement of proton autoneutralization potential

    International Nuclear Information System (INIS)

    Garcia, M.

    1984-09-01

    A proton space charge having multi-MeV kinetic energy was injected through a thin ground plane to extract electrons and produce a time-dependent autoneutralization space potential. An electon-emitting floating-potential resistive divider was used to measure the space potential during 20 ns of the proton current pulse. During this time, proton kinetic energy fell from 10.6 MeV to 8.5 MeV and thus the space potential (taken as 1.09 x the floating potential) fell from 5.8 kV to 4.6 kV

  16. Are There Rotation Measure Gradients Across Active Galactic Nuclei Jets?

    Science.gov (United States)

    2010-10-20

    transverse RM gradient exists. We assume H0 = 71 km s−1 Mpc−1 and a ΛCDM cosmology with Ωλ = 0.7 and Ωm = 0.3 (e.g., Eisenstein et al. 2005; Hinshaw...O’Sullivan, S. P., & Gabuzda, D. C. 2010, MNRAS, 402, 259 Denn, G. R., Mutel, R. L., & Marscher, A. P. 2000, ApJS, 129, 61 Eisenstein , D. J., et al. 2005

  17. Potential measurements in tandem mirrors

    International Nuclear Information System (INIS)

    Glowienka, J.C.

    1985-11-01

    The US mirror program has begun conducting experiments with a thermal barrier tandem mirror configuration. This configuration requires a specific axial potential profile and implies measurements of potential for documentation and optimization of the configuration. This report briefly outlines the motivation for the thermal barrier tandem mirror and then outlines the techniques used to document the potential profile in conventional and thermal barrier tandem mirrors. Examples of typical data sets from the world's major tandem mirror experiments, TMX and TMX-U at Lawrence Livermore National Laboratory (LLNL) and Gamma 10 at Tsukuba University in Japan, and the current interpretation of the data are discussed together with plans for the future improvement of measurements of plasma potential

  18. Measurement of the vertical temperature gradient at the Saclay Nuclear Research Centre

    International Nuclear Information System (INIS)

    Santelli, F.; Le Quino, R.

    1962-01-01

    A 109 m mast has been erected at the Saclay Nuclear Research Centre for the precise measurement of thermal gradients and gaseous effluents. This note describes the temperature measurement devices (thermocouple and thermo-resistor) and the first results obtained

  19. Simultaneous measurement of gravity acceleration and gravity gradient with an atom interferometer

    International Nuclear Information System (INIS)

    Sorrentino, F.; Lien, Y.-H.; Rosi, G.; Tino, G. M.; Bertoldi, A.; Bodart, Q.; Cacciapuoti, L.; Angelis, M. de; Prevedelli, M.

    2012-01-01

    We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.

  20. Streaming potential measurements of biosurfaces

    Science.gov (United States)

    Van Wagenen, R. A.; Andrade, J. D.; Hibbs, J. B., Jr.

    1976-01-01

    A technique based on the measurement of streaming potentials has been developed to evaluate the electrokinetic region of the cell periphery. This approach is feasible for cell lines propagated in in-vitro cell cultures in monolayer form. The advantage of this system is that cells may be evaluated in the living state atttached to a substrate; it is not necessary to subject the cells to enzymatic, chemical, or mechanical trauma required to obtain monodisperse suspensions which are then normally evaluated by microelectrophoresis. In this manner, it should be possible to study the influence of substrate and environmental factors on the charge density and potential at the cell periphery. The apparatus and procedure are described as well as some results concerning the electrokinetic potential of borosilicate capillaries as a function of ionic strength, pH, and temperature. The effect that turbulence and entrance flow conditions have on accurate streaming-potential measurements is discussed. The electrokinetic potential of BALB/c 3T12 fibroblasts has been quantified as a function of pH, ionic strength, glutaraldehyde fixation, and Giemsa staining.

  1. [Does a lateral gradient of membrane potential on the plasma membrane of growing pollen tube of germinating pollen grain exist?].

    Science.gov (United States)

    Andreev, I M

    2011-01-01

    The data presented in the article by Breigina et al. (2009) "Changes in the membrane potential during pollen grain germination and pollen tube growth" (Tsitologiya. 51 (10): 815-823) and concerning the measurement of electric membrane potential (Delta Psi) on the plasma membrane of growing pollen tube of germinating pollen grain with the use of fluorescent potential-sensitive dye, di-4-ANEPPS, were critically analyzed in order to clarify whether a lateral gradient of Delta Psi on this membrane indeed exists. This analysis showed that the main conclusion of the authors of the above article on the existence of polar distribution of Delta Psi along the pollen tube plasma membrane is not in accordance with a number of known peculiarities of di-4-ANEPPS behavior in biological membranes and requires a significant revision. The findings in question reported by the authors, in my opinion, might be interpreted as evidence for the presence on the plasma membrane of growing pollen tube not only the membrane potential Delta Psi but also lateral gradient of so called intra-membrane dipole potential. Based on the comments made, another interpretation of the experimental results described by Breigina et al. has been offered. In addition, some drawbacks in the methodology used by the authors for measurement of Delta Psi with other fluorescent potential-sensitive dye, DiBAC3(3), are also shortly considered.

  2. Modified Fourth-Order Kinetic Energy Gradient Expansion with Hartree Potential-Dependent Coefficients.

    Science.gov (United States)

    Constantin, Lucian A; Fabiano, Eduardo; Della Sala, Fabio

    2017-09-12

    Using the semiclassical neutral atom theory, we developed a modified fourth-order kinetic energy (KE) gradient expansion (GE4m) that keeps unchanged all the linear-response terms of the uniform electron gas and gives a significant improvement with respect to the known semilocal functionals for both large atoms and jellium surfaces. On the other hand, GE4m is not accurate for light atoms; thus, we modified the GE4m coefficients making them dependent on a novel ingredient, the reduced Hartree potential, recently introduced in the Journal of Chemical Physics 2016, 145, 084110, in the context of exchange functionals. The resulting KE gradient expansion functional, named uGE4m, belongs to the novel class of u-meta-generalized-gradient-approximations (uMGGA) whose members depend on the conventional ingredients (i.e., the reduced gradient and Laplacian of the density) as well as on the reduced Hartree potential. To test uGE4m, we defined an appropriate benchmark (including total KE and KE differences for atoms, molecules and jellium clusters) for gradient expansion functionals, that is, including only those systems which are mainly described by a slowly varying density regime. While most of the GGA and meta-GGA KE functionals (we tested 18 of them) are accurate for some properties and inaccurate for others, uGE4m shows a consistently good performance for all the properties considered. This represents a qualitative boost in the KE functional development and highlights the importance of the reduced Hartree potential for the construction of next-generation KE functionals.

  3. Experimental measurements of the SP response to concentration and temperature gradients in sandstones with application to subsurface geophysical monitoring

    Science.gov (United States)

    Leinov, E.; Jackson, M. D.

    2014-09-01

    Exclusion-diffusion potentials arising from temperature gradients are widely neglected in self-potential (SP) surveys, despite the ubiquitous presence of temperature gradients in subsurface settings such as volcanoes and hot springs, geothermal fields, and oil reservoirs during production via water or steam injection. Likewise, with the exception of borehole SP logging, exclusion-diffusion potentials arising from concentration gradients are also neglected or, at best, it is assumed that the diffusion potential dominates. To better interpret these SP sources requires well-constrained measurements of the various coupling terms. We report measurements of thermoelectric and electrochemical exclusion-diffusion potentials across sandstones saturated with NaCl brine and find that electrode effects can dominate the measured voltage. After correcting for these, we find that Hittorf transport numbers are the same within experimental error regardless of whether ion transport occurs in response to temperature or concentration gradients over the range of NaCl concentration investigated that is typical of natural systems. Diffusion potentials dominate only if the pore throat radius is more than approximately 4000 times larger than the diffuse layer thickness. In fine-grained sandstones with small pore throat diameter, this condition is likely to be met only if the saturating brine is of relatively high salinity; thus, in many cases of interest to earth scientists, exclusion-diffusion potentials will comprise significant contributions from both ionic diffusion through, and ionic exclusion from, the pore space of the rock. However, in coarse-grained sandstones, or sandstones saturated with high-salinity brine, exclusion-diffusion potentials can be described using end-member models in which ionic exclusion is neglected. Exclusion-diffusion potentials in sandstones depend upon pore size and salinity in a complex way: they may be positive, negative, or zero depending upon sandstone

  4. Precise measurements and shimming of magnetic field gradients in the low field regime

    Energy Technology Data Exchange (ETDEWEB)

    Allmendinger, Fabian; Schmidt, Ulrich [Physikalisches Institut, Universitaet Heidelberg (Germany); Grasdijk, Olivier; Jungmann, Klaus; Willmann, Lorenz [University of Groningen (Netherlands); Heil, Werner; Karpuk, Sergei; Repetto, Maricel; Sobolev, Yuri; Zimmer, Stefan [Institut fuer Physik, Universitaet Mainz (Germany); Krause, Hans-Joachim; Offenhaeuser, Andreas [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); Collaboration: MIXed-Collaboration

    2016-07-01

    For many experiments at the precision frontier of fundamental physics, the accurate measurement and knowledge of magnetic field gradients in particular in the low field regime (<μT) is a necessity: On the one hand, in the search for an Electric Dipole Moment (EDM) of free neutrons or atoms, field gradients contribute to geometric-phase-induced false EDM signals for particles in traps. On the other hand, clock comparison experiments like the {sup 3}He/{sup 129}Xe spin clock experiment suffer from gradients, since the coherent T{sub 2}*-time of free spin precession, and thus the measurement sensitivity, scales ∝ ∇ vector B{sup -2}. Here we report on a new and very effective method, to shim and to measure tiny magnetic field gradients in the range of pT/cm by using effective T{sub 2}*-measurement sequences in varying the currents of trim coils of known geometry.

  5. Enhancing tube hydroformability by reducing the local strain gradient at potential necking sites

    International Nuclear Information System (INIS)

    Shin, S. G. R.; Joo, B. D.; Moon, Y. H.; Tyne, C. J. Van

    2014-01-01

    Bursting in tube hydroforming is preceded by localized deformation, which is often called necking. The retardation of the initiation of necking is a means to enhance hydroformability. Since high strain gradients occur at necking sites, a decrease in local strain gradients is an effective way to retard the initiation of necking. In the current study, the expansion at potential necking sites was intentionally restricted in order to reduce the strain gradient at potential necking sites. From the strain distribution obtained from FEM, it is possible to determine strain concentrated zones, which are the potential necking sites. Prior to the hydroforming of a trailing arm, lead patch is attached to the tube where the strain concentration would occur. Due to the incompressibility of lead, the tube expansion is locally restricted, and the resultant strain extends to adjacent regions of the tube during hydroforming. After the first stage of hydroforming, the lead is removed from the tube, and the hydroforming continues to obtain the targeted shape without the local restriction. This method was successfully used to fabricate a complex shaped automotive trailing arm that had previously failed during traditional hydroforming processing.

  6. Analysis of Light-Induced Transmembrane Ion Gradients and Membrane Potential in Photosystem I Proteoliposomes

    International Nuclear Information System (INIS)

    Pennisi, Cristian P.; Greenbaum, Elias; Yoshida, Ken

    2010-01-01

    Photosystem I (PSI) complexes can support a light-driven electrochemical gradient for protons, which is the driving force for energy-conserving reactions across biological membranes. In this work, a computational model that enables a quantitative description of the light-induced proton gradients across the membrane of PSI proteoliposomes is presented. Using a set of electrodiffusion equations, a compartmental model of a vesicle suspended in aqueous medium was studied. The light-mediated proton movement was modeled as a single proton pumping step with backpressure of the electric potential. The model fits determinations of pH obtained from PSI proteoliposomes illuminated in the presence of mediators of cyclic electron transport. The model also allows analysis of the proton gradients in relation to the transmembrane ion fluxes and electric potential. Sensitivity analysis enabled a determination of the parameters that have greater influence on steady-state levels and onset/decay rates of transmembrane pH and electric potential. This model could be used as a tool for optimizing PSI proteoliposomes for photo-electrochemical applications.

  7. PHASE GRADIENT METHOD OF MAGNETIC FIELD MEASUREMENTS IN ELECTRIC VEHICLES

    Directory of Open Access Journals (Sweden)

    N. G. Ptitsyna

    2013-01-01

    Full Text Available Operation of electric and hybrid vehicles demands real time magnetic field control, for instance, for fire and electromagnetic safety. The article deals with a method of magnetic field measurements onboard electric cars taking into account peculiar features of these fields. The method is based on differential methods of measurements, and minimizes the quantity of magnetic sensors.

  8. Characterization of Generalized Young Measures Generated by Symmetric Gradients

    Science.gov (United States)

    De Philippis, Guido; Rindler, Filip

    2017-06-01

    This work establishes a characterization theorem for (generalized) Young measures generated by symmetric derivatives of functions of bounded deformation (BD) in the spirit of the classical Kinderlehrer-Pedregal theorem. Our result places such Young measures in duality with symmetric-quasiconvex functions with linear growth. The "local" proof strategy combines blow-up arguments with the singular structure theorem in BD (the analogue of Alberti's rank-one theorem in BV), which was recently proved by the authors. As an application of our characterization theorem we show how an atomic part in a BD-Young measure can be split off in generating sequences.

  9. In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

    International Nuclear Information System (INIS)

    Smith, R.L.; Howes, B.L.; Garabedian, S.P.

    1991-01-01

    Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of 13 C-enriched carbon dioxide in experiments in which 13 C-enriched methane was used as the tracer. A V max for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K m values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 μM for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems

  10. Non-invasive measurement of pressure gradients using ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes

    2013-01-01

    for isotropic fluids to the estimated velocity fields. The velocity fields were measured for a steady flow on a carotid bifurcation phantom (Shelley Medical, Canada) with a 70% constriction on the internal branch. Scanning was performed with a BK8670 linear transducer (BK Medical, Denmark) connected to a BK...

  11. Development of the CARS method for measurement of pressure and temperature gradients in centrifuges

    International Nuclear Information System (INIS)

    Zeltmann, A.H.; Valentini, J.J.

    1983-12-01

    These experiments evaluated the feasibility of applying the CARS technique to the measurement of UF 6 concentrations and pressure gradients in a gas centrifuge. The resultant CARS signals were properly related to system parameters as suggested by theory. The results have been used to guide design of an apparatus for making CARS measurements in a UF 6 gas centrifuge. Ease of measurement is expected for pressures as low as 0.1 torr. Temperature gradients can be measured by this technique with changes in the data acquisition method. 16 references, 8 figures, 2 tables

  12. Localisation of a neutron source using measurements and calculation of the neutron flux and its gradient

    CERN Document Server

    Linden, P; Dahl, B; Pázsit, I; Por, G

    1999-01-01

    We have performed laboratory measurements of the neutron flux and its gradient in a static model experiment, similar to a model problem proposed in Pazsit (Ann. Nucl. Energy 24 (1997) 1257). The experimental system consists of a radioactive neutron source located in a water tank. The measurements are performed using a recently developed very small optical fibre detector. The measured values of the flux and its gradient are then used to test the possibility of localising the source. The results show that it is possible to measure the flux on the circumference of a circle and from this calculate the flux gradient vector. Then, by comparison of the measured quantities with corresponding MCNP calculations, both the direction and the distance to the source are found and thus the position of the source can be determined.

  13. Measurement of hepatic venous pressure gradient revisited: Catheter wedge vs balloon wedge techniques

    Directory of Open Access Journals (Sweden)

    S Timothy Chelliah

    2011-01-01

    Full Text Available Aims: To evaluate the accuracy of measurement of hepatic venous pressure gradient by catheter wedge as compared to balloon wedge (the gold standard. Materials and Methods: Forty-five patients having a clinical diagnosis of intrahepatic portal hypertension were subjected to the two different types of pressure measurements (catheter wedge and balloon wedge during transjugular liver biopsy under fluoroscopic guidance. Statistical Analysis: Spearman′s rank correlation coefficient, Bland-Altman plot for agreement, and single measure intraclass correlation were used for analysis of data. Results: There was a close correlation between the results obtained by both the techniques, with highly significant concordance (P < 0.0001. Hepatic venous pressure gradients as measured by the catheter wedge technique were either equal to or less than those obtained by the balloon wedge technique. Conclusions: The difference in hepatic venous pressure gradients measured by the two techniques is insignificant.

  14. Applicability of Stokes method for measuring viscosity of mixtures with concentration gradient

    Directory of Open Access Journals (Sweden)

    César Medina

    2017-12-01

    Full Text Available After measuring density and viscosity of a mixture of glycerin and water contained in a vertical pipe, a variation of these properties according to depth is observed. These gradients are typical of non-equilibrium states related to the lower density of water and the fact that relatively long times are necessary to achieve homogeneity. In the same pipe, the falling velocity of five little spheres is measured as a function of depth, and then a numerical fit is performed which agrees very well with experimental data. Based on the generalization of these results, the applicability of Stokes method is discussed for measuring viscosity of mixtures with a concentration gradient.

  15. Analysis and correction of gradient nonlinearity bias in apparent diffusion coefficient measurements.

    Science.gov (United States)

    Malyarenko, Dariya I; Ross, Brian D; Chenevert, Thomas L

    2014-03-01

    Gradient nonlinearity of MRI systems leads to spatially dependent b-values and consequently high non-uniformity errors (10-20%) in apparent diffusion coefficient (ADC) measurements over clinically relevant field-of-views. This work seeks practical correction procedure that effectively reduces observed ADC bias for media of arbitrary anisotropy in the fewest measurements. All-inclusive bias analysis considers spatial and time-domain cross-terms for diffusion and imaging gradients. The proposed correction is based on rotation of the gradient nonlinearity tensor into the diffusion gradient frame where spatial bias of b-matrix can be approximated by its Euclidean norm. Correction efficiency of the proposed procedure is numerically evaluated for a range of model diffusion tensor anisotropies and orientations. Spatial dependence of nonlinearity correction terms accounts for the bulk (75-95%) of ADC bias for FA = 0.3-0.9. Residual ADC non-uniformity errors are amplified for anisotropic diffusion. This approximation obviates need for full diffusion tensor measurement and diagonalization to derive a corrected ADC. Practical scenarios are outlined for implementation of the correction on clinical MRI systems. The proposed simplified correction algorithm appears sufficient to control ADC non-uniformity errors in clinical studies using three orthogonal diffusion measurements. The most efficient reduction of ADC bias for anisotropic medium is achieved with non-lab-based diffusion gradients. Copyright © 2013 Wiley Periodicals, Inc.

  16. Measurement and Analysis of the Temperature Gradient of Blackbody Cavities, for Use in Radiation Thermometry

    Science.gov (United States)

    De Lucas, Javier; Segovia, José Juan

    2018-05-01

    Blackbody cavities are the standard radiation sources widely used in the fields of radiometry and radiation thermometry. Its effective emissivity and uncertainty depend to a large extent on the temperature gradient. An experimental procedure based on the radiometric method for measuring the gradient is followed. Results are applied to particular blackbody configurations where gradients can be thermometrically estimated by contact thermometers and where the relationship between both basic methods can be established. The proposed procedure may be applied to commercial blackbodies if they are modified allowing secondary contact temperature measurement. In addition, the established systematic may be incorporated as part of the actions for quality assurance in routine calibrations of radiation thermometers, by using the secondary contact temperature measurement for detecting departures from the real radiometrically obtained gradient and the effect on the uncertainty. On the other hand, a theoretical model is proposed to evaluate the effect of temperature variations on effective emissivity and associated uncertainty. This model is based on a gradient sample chosen following plausible criteria. The model is consistent with the Monte Carlo method for calculating the uncertainty of effective emissivity and complements others published in the literature where uncertainty is calculated taking into account only geometrical variables and intrinsic emissivity. The mathematical model and experimental procedure are applied and validated using a commercial type three-zone furnace, with a blackbody cavity modified to enable a secondary contact temperature measurement, in the range between 400 °C and 1000 °C.

  17. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    NARCIS (Netherlands)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C.; ASDEX Upgrade team,; EUROfusion MST1 Team,

    2018-01-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T-e) and its fluctuations (delta T-e). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects,

  18. Sub-Angstrom oscillation amplitude non-contact atomic force microscopy for lateral force gradient measurement

    International Nuclear Information System (INIS)

    Atabak, Mehrdad; Unverdi, Ozhan; Ozer, H. Ozguer; Oral, Ahmet

    2009-01-01

    We report the first results from novel sub-Angstrom oscillation amplitude non-contact atomic force microscopy developed for lateral force gradient measurements. Quantitative lateral force gradients between a tungsten tip and Si(1 1 1)-(7 x 7) surface can be measured using this microscope. Simultaneous lateral force gradient and scanning tunnelling microscope images of single and multi atomic steps are obtained. In our measurement, tunnel current is used as feedback. The lateral stiffness contrast has been observed to be 2.5 N/m at single atomic step, in contrast to 13 N/m at multi atomic step on Si(1 1 1) surface. We also carried out a series of lateral stiffness-distance spectroscopy. We observed lateral stiffness-distance curves exhibit sharp increase in the stiffness as the sample is approached towards the surface. We usually observed positive stiffness and sometimes going into slightly negative region.

  19. Aortic-Brachial Pulse Wave Velocity Ratio: A Measure of Arterial Stiffness Gradient Not Affected by Mean Arterial Pressure.

    Science.gov (United States)

    Fortier, Catherine; Desjardins, Marie-Pier; Agharazii, Mohsen

    2018-03-01

    Aortic stiffness, measured by carotid-femoral pulse wave velocity (cf-PWV), is used for the prediction of cardiovascular risk. This mini-review describes the nonlinear relationship between cf-PWV and operational blood pressure, presents the proposed methods to adjust for this relationship, and discusses a potential place for aortic-brachial PWV ratio (a measure of arterial stiffness gradient) as a blood pressure-independent measure of vascular aging. PWV is inherently dependent on the operational blood pressure. In cross-sectional studies, PWV adjustment for mean arterial pressure (MAP) is preferred, but still remains a nonoptimal approach, as the relationship between PWV and blood pressure is nonlinear and varies considerably among individuals due to heterogeneity in genetic background, vascular tone, and vascular remodeling. Extrapolations from the blood pressure-independent stiffness parameter β (β 0 ) have led to the creation of stiffness index β, which can be used for local stiffness. A similar approach has been used for cardio-ankle PWV to generate a blood pressure-independent cardio-ankle vascular index (CAVI). It was recently demonstrated that stiffness index β and CAVI remain slightly blood pressure-dependent, and a more appropriate formula has been proposed to make the proper adjustments. On the other hand, the negative impact of aortic stiffness on clinical outcomes is thought to be mediated through attenuation or reversal of the arterial stiffness gradient, which can also be influenced by a reduction in peripheral medium-sized muscular arteries in conditions that predispose to accelerate vascular aging. Arterial stiffness gradient, assessed by aortic-brachial PWV ratio, is emerging to be at least as good as cf-PWV for risk prediction, but has the advantage of not being affected by operating MAP. The negative impacts of aortic stiffness on clinical outcomes are proposed to be mediated through attenuation or reversal of arterial stiffness gradient

  20. Redox potential characterization and soil greenhouse gas concentration across a hydrological gradient in a Gulf coast forest

    Science.gov (United States)

    Yu, K.; Faulkner, S.P.; Patrick, W.H.

    2006-01-01

    Soil redox potential (Eh), concentrations of oxygen (O2) and three greenhouse gases (CO2, CH4, and N2O) were measured in the soil profile of a coastal forest at ridge, transition, and swamp across a hydrological gradient. The results delineated a distinct boundary in soil Eh and O2 concentration between the ridge and swamp with essentially no overlap between the two locations. Critical soil Eh to initiate significant CH4 production under this field conditions was about +300 mV, much higher than in the homogenous soils (about -150 mV). The strength of CH4 source to the atmosphere was strong for the swamp, minor for the transition, and negligible or even negative (consumption) for the ridge. Maximum N2O concentration in the soils was found at about Eh +250 mV, and the soil N2O emission was estimated to account for less than 4% for the ridge and transition, and almost negligible for the swamp in the cumulative global warming potential (GWP) of these three gases. The dynamic nature of this study site in response to water table fluctuations across a hydrological gradient makes it an ideal model of impact of future sea level rise to coastal ecosystems. Soil carbon (C) sequestration potential due to increasing soil water content upon sea level rise and subsidence in this coastal forest was likely limited and temporal, and at the expense of increasing soil CH4 production and emission. ?? 2005 Elsevier Ltd. All rights reserved.

  1. Measurement of electric field and gradient in the plasma sheath using clusters of floating microspheres

    International Nuclear Information System (INIS)

    Sheridan, T. E.; Katschke, M. R.; Wells, K. D.

    2007-01-01

    A method for measuring the time-averaged vertical electric field and its gradient in the plasma sheath using clusters with n=2 or 3 floating microspheres of known mass is described. The particle charge q is found by determining the ratio of the breathing frequency to the center-of-mass frequency for horizontal (in-plane) oscillations. The electric field at the position of the particles is then calculated using the measured charge-to-mass ratio, and the electric-field gradient is determined from the vertical resonance frequency. The Debye length is also found. Experimental results are in agreement with a simple sheath model

  2. Oxygen transport by oxygen potential gradient in dense ceramic oxide membranes

    Energy Technology Data Exchange (ETDEWEB)

    Maiya, P.S.; Balachandran, U.; Dusek, J.T.; Mieville, R.L. [Argonne National Lab., IL (United States). Energy Technology Div.; Kleefisch, M.S.; Udovich, C.A. [Amoco Exploration/Production, Naperville, IL (United States)

    1996-05-01

    Numerous studies have been conducted in recent years on the partial oxidation of methane to synthesis gas (syngas: CO + H{sub 2}) with air as the oxidant. In partial oxidation, a mixed-oxide ceramic membrane selectively transports oxygen from the air; this transport is driven by the oxygen potential gradient. Of the several ceramic materials the authors have tested, a mixed oxide based on the Sr-Fe-Co-O system has been found to be very attractive. Extensive oxygen permeability data have been obtained for this material in methane conversion experiments carried out in a reactor. The data have been analyzed by a transport equation based on the phenomenological theory of diffusion under oxygen potential gradients. Thermodynamic calculations were used to estimate the driving force for the transport of oxygen ions. The results show that the transport equation deduced from the literature describes the permeability data reasonably well and can be used to determine the diffusion coefficients and the associated activation energy of oxygen ions in the ceramic membrane material.

  3. On the divergence of gradient expansions for kinetic energy functionals in the potential functional theory

    International Nuclear Information System (INIS)

    Sergeev, Alexey; Jovanovic, Raka; Kais, Sabre; Alharbi, Fahhad H

    2016-01-01

    We consider the density of a fermionic system as a functional of the potential, in one-dimensional case, where it is approximated by the Thomas–Fermi term plus semiclassical corrections through the gradient expansion. We compare this asymptotic series with the exact answer for the case of the harmonic oscillator and the Morse potential. It is found that the leading (Thomas–Fermi) term is in agreement with the exact density, but the subdominant term does not agree in terms of the asymptotic behavior because of the presence of oscillations in the exact density, but their absence in the gradient expansion. However, after regularization of the density by convolution with a Gaussian, the agreement can be established even in the subdominant term. Moreover, it is found that the expansion is always divergent, and its terms grow proportionally to the factorial function of the order, similar to the well-known divergence of perturbation series in field theory and the quantum anharmonic oscillator. Padé–Hermite approximants allow summation of the series, and one of the branches of the approximants agrees with the density. (paper)

  4. Induced electric currents in the Alaska oil pipeline measured by gradient, fluxgate, and SQUID magnetometers

    Science.gov (United States)

    Campbell, W. H.; Zimmerman, J. E.

    1979-01-01

    The field gradient method for observing the electric currents in the Alaska pipeline provided consistent values for both the fluxgate and SQUID method of observation. These currents were linearly related to the regularly measured electric and magnetic field changes. Determinations of pipeline current were consistent with values obtained by a direct connection, current shunt technique at a pipeline site about 9.6 km away. The gradient method has the distinct advantage of portability and buried- pipe capability. Field gradients due to the pipe magnetization, geological features, or ionospheric source currents do not seem to contribute a measurable error to such pipe current determination. The SQUID gradiometer is inherently sensitive enough to detect very small currents in a linear conductor at 10 meters, or conversely, to detect small currents of one amphere or more at relatively great distances. It is fairly straightforward to achieve imbalance less than one part in ten thousand, and with extreme care, one part in one million or better.

  5. A Magnetic Resonance Measurement Technique for Rapidly Switched Gradient Magnetic Fields in a Magnetic Resonance Tomograph

    Directory of Open Access Journals (Sweden)

    K. Bartušek

    2003-01-01

    Full Text Available This paper describes a method for measuring of the gradient magnetic field in Nuclear Magnetic Resonance (NMR tomography, which is one of the modern medical diagnostic methods. A very important prerequisite for high quality imaging is a gradient magnetic field in the instrument with exactly defined properties. Nuclear magnetic resonance enables us to measure the pulse gradient magnetic field characteristics with high accuracy. These interesting precise methods were designed, realised, and tested at the Institute of Scientific Instruments (ISI of the Academy of Sciences of the Czech Republic. The first of them was the Instantaneous Frequency (IF method, which was developed into the Instantaneous Frequency of Spin Echo (IFSE and the Instantaneous Frequency of Spin Echo Series (IFSES methods. The above named methods are described in this paper and their a comparison is also presented.

  6. Techniques for Ultra-high Magnetic Field Gradient NMR Diffusion Measurements

    Science.gov (United States)

    Sigmund, Eric E.; Mitrovic, Vesna F.; Calder, Edward S.; Will Thomas, G.; Halperin, William P.; Reyes, Arneil P.; Kuhns, Philip L.; Moulton, William G.

    2001-03-01

    We report on development and application of techniques for ultraslow diffusion coefficient measurements through nuclear magnetic resonance (NMR) in high magnetic field gradients. We have performed NMR experiments in a steady fringe field gradient of 175 T/m from a 23 T resistive Bitter magnet, as well as in a gradient of 42 T/m from an 8 T superconducting magnet. New techniques to provide optimum sensitivity in these experiments are described. To eliminate parasitic effects of the temporal instability of the resistive magnet, we have introduced a passive filter: a highly conductive cryogen-cooled inductive shield. We show experimental demonstration of such a shield’s effect on NMR performed in the Bitter magnet. For enhanced efficiency, we have employed “frequency jumping” in our spectrometer system. Application of these methods has made possible measurements of diffusion coefficients as low as 10-10 cm^2/s, probing motion on a 250 nm length scale.

  7. Stable Computation of the Vertical Gradient of Potential Field Data Based on Incorporating the Smoothing Filters

    Science.gov (United States)

    Baniamerian, Jamaledin; Liu, Shuang; Abbas, Mahmoud Ahmed

    2018-04-01

    The vertical gradient is an essential tool in interpretation algorithms. It is also the primary enhancement technique to improve the resolution of measured gravity and magnetic field data, since it has higher sensitivity to changes in physical properties (density or susceptibility) of the subsurface structures than the measured field. If the field derivatives are not directly measured with the gradiometers, they can be calculated from the collected gravity or magnetic data using numerical methods such as those based on fast Fourier transform technique. The gradients behave similar to high-pass filters and enhance the short-wavelength anomalies which may be associated with either small-shallow sources or high-frequency noise content in data, and their numerical computation is susceptible to suffer from amplification of noise. This behaviour can adversely affect the stability of the derivatives in the presence of even a small level of the noise and consequently limit their application to interpretation methods. Adding a smoothing term to the conventional formulation of calculating the vertical gradient in Fourier domain can improve the stability of numerical differentiation of the field. In this paper, we propose a strategy in which the overall efficiency of the classical algorithm in Fourier domain is improved by incorporating two different smoothing filters. For smoothing term, a simple qualitative procedure based on the upward continuation of the field to a higher altitude is introduced to estimate the related parameters which are called regularization parameter and cut-off wavenumber in the corresponding filters. The efficiency of these new approaches is validated by computing the first- and second-order derivatives of noise-corrupted synthetic data sets and then comparing the results with the true ones. The filtered and unfiltered vertical gradients are incorporated into the extended Euler deconvolution to estimate the depth and structural index of a magnetic

  8. Measurement of asymmetric optical pumping of ions accelerating in a magnetic-field gradient

    International Nuclear Information System (INIS)

    Sun Xuan; Scime, Earl; Miah, Mahmood; Cohen, Samuel; Skiff, Frederick

    2004-01-01

    We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic-field gradient. The signature is a difference in the laser-induced-fluorescence emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities

  9. Measurement of Asymmetric Optical Pumping of Ions Accelerating in a Magnetic-field Gradient

    Energy Technology Data Exchange (ETDEWEB)

    Xuan Sun; Earl Scime; Mahmood Miah; Samuel Cohen; Frederick Skiff

    2004-10-28

    We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic field gradient. The signature is a difference in the laser-induced-fluorescence (LIF) emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities.

  10. Gradient heat flux measurement as monitoring method for the diesel engine

    Science.gov (United States)

    Sapozhnikov, S. Z.; Mityakov, V. Yu; Mityakov, A. V.; Vintsarevich, A. V.; Pavlov, A. V.; Nalyotov, I. D.

    2017-11-01

    The usage of gradient heat flux measurement for monitoring of heat flux on combustion chamber surface and optimization of diesel work process is proposed. Heterogeneous gradient heat flux sensors can be used at various regimes for an appreciable length of time. Fuel injection timing is set by the position of the maximum point on the angular heat flux diagram however, the value itself of the heat flux may not be considered. The development of such an approach can be productive for remote monitoring of work process in the cylinders of high-power marine engines.

  11. Measurement of Asymmetric Optical Pumping of Ions Accelerating in a Magnetic-field Gradient

    International Nuclear Information System (INIS)

    Xuan Sun; Earl Scime; Mahmood Miah; Samuel Cohen; Frederick Skiff

    2004-01-01

    We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic field gradient. The signature is a difference in the laser-induced-fluorescence (LIF) emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities

  12. Measurements of ultimate accelerating gradients in the SLAC disk-loaded structure. Part I

    International Nuclear Information System (INIS)

    Wang, J.W.; Loew, G.A.

    1985-01-01

    The work reported here describes measurements made to study the maximum attainable accelerating gradients in a conventional SLAC disk-loaded accelerator section of the constant-gradient type running at 2856 MHz. The objective was to reach an accelerating gradient of at least 100 MV/m. The accelerating gradient at which the SLAC disk-loaded waveguide runs routinely is approx. 9 MV/m (36 MW tubes without SLED) and approx. 12 MV/m with SLED I (2.5 μsec pulse). To reach 100 MV/m in a conventional 3 m constant-gradient section, one would need a klystron with a peak power output of 900 MW. since such a tube is not available, we decided to use a short standing-wave section in which the resonant fields would be allowed to build up. The design criteria for this section, the fabrication, matching and tuning, the experimental set-up and the results are described below

  13. Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Sanna F.; Knipe, Kevin; Manero, Albert; Raghavan, Seetha [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Meid, Carla; Wischek, Janine; Bartsch, Marion [German Aerospace Center (DLR), Institute of Materials Research, 51147 Cologne (Germany); Okasinski, John; Almer, Jonathan [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Karlsson, Anette M. [Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115 (United States)

    2013-08-15

    Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

  14. Microcosm investigation of growth and phytoremediation potential of Azolla japonica along nitrogen gradients.

    Science.gov (United States)

    Park, Hun; Song, Uhram

    2017-10-03

    Although Azolla species are among the most promising plants for use in phytoremediation, more studies on their growth and nitrogen (N) uptake along the N gradients of growing media are required. In this study, N concentration-dependent growth in growing media and phosphorus (P) and N accumulation by Azolla japonica were studied by estimating direct N uptake from media by molybdenum-iron proteins. The doubling time of A. japonica was less than a week, regardless of the N concentration (0, 5, and 25 mg N/L) present in the growth media, indicating that this plant is suitable for remediation. Plants showed a high uptake of P, probably via plant-bacteria symbiosis, indicating their potential for effective P remediation. A. japonica also showed more than 4% N content regardless of the treatment and accumulated more than 40 mg of N per microcosm in 3 weeks. iron and molybdenum levels in plants were strongly associated with N fixation, and N uptake from media was estimated to be more than 25 mg per microcosm in 3 weeks, indicating that A. japonica has N remediation potential. As A. japonica is a rapidly growing plant, capable of efficient P and N remediation, it has great potential for use in phytoremediation of nutrient-enriched waters such as agricultural or urban wastewater and eutrophicated aquatic ecosystems.

  15. Temperature gradient scale length measurement: A high accuracy application of electron cyclotron emission without calibration

    Energy Technology Data Exchange (ETDEWEB)

    Houshmandyar, S., E-mail: houshmandyar@austin.utexas.edu; Phillips, P. E.; Rowan, W. L. [Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States); Yang, Z. J. [Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Hubbard, A. E.; Rice, J. E.; Hughes, J. W.; Wolfe, S. M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02129 (United States)

    2016-11-15

    Calibration is a crucial procedure in electron temperature (T{sub e}) inference from a typical electron cyclotron emission (ECE) diagnostic on tokamaks. Although the calibration provides an important multiplying factor for an individual ECE channel, the parameter ΔT{sub e}/T{sub e} is independent of any calibration. Since an ECE channel measures the cyclotron emission for a particular flux surface, a non-perturbing change in toroidal magnetic field changes the view of that channel. Hence the calibration-free parameter is a measure of T{sub e} gradient. B{sub T}-jog technique is presented here which employs the parameter and the raw ECE signals for direct measurement of electron temperature gradient scale length.

  16. Self-diffusion measurements in heterogeneous systems using NMR pulsed field gradient technique

    International Nuclear Information System (INIS)

    Heink, W.; Kaerger, J.; Walter, A.

    1978-01-01

    The experimental pecularities of the NMR pulsed field gradient technique are critical surveyed in its application to zeolite adsorbate adsorbent systems. After a presentation of the different transport parameters accessible by this technique, the consequences of the existence of inner field gradients being inherent to heterogeneous systems are analyzed. Experimental conditions and consequences of an application of pulsed field gradients of high intensity which are necessary for the measurement of small intracrystalline self-diffusion coefficients, are discussed. Gradient pulses of 0.15 Tcm -1 with pulse widths of 2 ms maximum and relative deviations of less than 0.01 per mille can be realized. Since for a number of adsorbate adsorbent systems a distinct dependence of the intracrystalline self-diffusion coeffcients on adsorbate concentration is observed, determination of zeolite pore fiiling factor is of considerable importance for the interpretation of the diffusivities obtained. It is demonstrated that also this information can be obtained by NMR technique in a straightforward way with a mean error of less than 5 to 10 %. Applying this new method and using an optimum experimental device as described, pore filling factor dependences of the self-diffusion coefficients of alkanes in NaX zeolites can be followed over more than two orders of magnitude. (author)

  17. Microgravity vertical gradient measurement in the site of VIRGO interferometric antenna (Pisa plain, Italy

    Directory of Open Access Journals (Sweden)

    F. Fidecaro

    2008-06-01

    Full Text Available The site of the European Gravitational Observatory (EGO located in the countryside near Pisa (Tuscany, Italy was investigated by a microgravity vertical gradient (MVG survey. The EGO site houses the VIRGO interferometric antenna for gravitational waves detection. The microgravity survey aims to highlight the gravity anomalies of high-frequency related to more superficial geological sources in order to obtain a detailed model of the lithologic setting of the VIRGO site, that will allow an estimate of the noise induced by seismic waves and by Newtonian interference. This paper presents the results of the gradiometric survey of 2006 in the area of the interferometric antenna. MVG measurements allow us to enhance the high frequency signal strongly associated with the shallow structures. The gradient gravity map shows a main negative pattern that seems related to the trending of the high density layer of gravel that was evidenced in geotechnical drillings executed along the orthogonal arms during the construction of the VIRGO complex. Calibrating the relationship between the vertical gradient and the depth of the gravel interface we have computed a model of gravity gradient for the whole VIRGO site, defining the 3D distribution of the top surface of this layer. This latter shows a NE-SW negative pattern that may represent a palaeo-bed alluvial of the Serchio from the Bientina River system.

  18. Differential calculus for Dirichlet forms: The measure-valued gradient preserved by image

    OpenAIRE

    Bouleau, Nicolas

    2005-01-01

    In order to develop a differential calculus for error propagation we study local Dirichlet forms on probability spaces with square field operator $\\Gamma$ -- i.e. error structures -- and we are looking for an object related to $\\Gamma$ which is linear and with a good behaviour by images. For this we introduce a new notion called the measure valued gradient which is a randomized square root of $\\Gamma$. The exposition begins with inspecting some natural notions candidate to solve the problem b...

  19. Measurement of magnetic field gradients using Raman spectroscopy in a fountain

    Science.gov (United States)

    Srinivasan, Arvind; Zimmermann, Matthias; Efremov, Maxim A.; Davis, Jon P.; Narducci, Frank A.

    2017-02-01

    In many experiments involving cold atoms, it is crucial to know the strength of the magnetic field and/or the magnetic field gradient at the precise location of a measurement. While auxiliary sensors can provide some of this information, the sensors are usually not perfectly co-located with the atoms and so can only provide an approximation to the magnetic field strength. In this article, we describe a technique to measure the magnetic field, based on Raman spectroscopy, using the same atomic fountain source that will be used in future magnetically sensitive measurements.

  20. Forest structure, diversity and regeneration potential along altitudinal gradient in Dhanaulti of Garhwal Himalaya

    Energy Technology Data Exchange (ETDEWEB)

    Saha, S.; Rajwar, G.S.; Kumar, M.

    2016-07-01

    Aim of the study: The aim of the present study was to understatnd the forest composition, structure, diversity and regeneration potential along altitudinal gradient. Area of study: The study was carried out in Dhanaulti forest which falls under temperate region of Garhwal Himalaya in Uttarakhand state, India. Material and Methods: Vegetation analysis was carried out using 10 quadrats at each altitude using a quadrate size of 10×10 m2. In each quadrate, categories of trees >30 cm cbh were considered as trees, 10-30cm cbh as saplings and <10 cm cbh as seedlings. The data were quantitatively analyzed. Main results: In upper and middle altitudes, Cedrus deodara was reported dominant tree whereas, in lower altitude Quercus leucotrichophora was reported dominant. Tree density was highest in lower altitude which reduced middle and upper altitudes whereas, total basal cover increased with increasing altitude. The increasing total basal cover with altitude could be because of the presence of Cedrus deodara trees having higher girth classes. In tree, sapling and seedling layers, diversity (H) and equitabiltiy (EC) decreased with increasing altitude. However, concentrations of dominace (CD) and beta diversity (BD have shown reverse trend with H and EC which increased with increasing altitudes, in each layer of tree, sapling and seedling. The distribution pattern of most species in all layers of trees, saplings and seedlings was contagious. The regeneration potential of the species has shown that some of the species in the absence of tree layer are still regenerating particularly, Rhododendron arboreum, Benthamidia capitata, Neolitsea pallens etc. It indicates that most of the species are shifting upward as they are getting suitable conditions. Research highlights: Altitude influence species composition, diversity and regeneration potential of species. (Author)

  1. A Miniature Four-Hole Probe for Measurement of Three-Dimensional Flow with Large Gradients

    Directory of Open Access Journals (Sweden)

    Ravirai Jangir

    2014-01-01

    Full Text Available A miniature four-hole probe with a sensing area of 1.284 mm2 to minimise the measurement errors due to the large pressure and velocity gradients that occur in highly three-dimensional turbomachinery flows is designed, fabricated, calibrated, and validated. The probe has good spatial resolution in two directions, thus minimising spatial and flow gradient errors. The probe is calibrated in an open jet calibration tunnel at a velocity of 50 m/s in yaw and pitch angles range of ±40 degrees with an interval of 5 degrees. The calibration coefficients are defined, determined, and presented. Sensitivity coefficients are also calculated and presented. A lookup table method is used to determine the four unknown quantities, namely, total and static pressures and flow angles. The maximum absolute errors in yaw and pitch angles are 2.4 and 1.3 deg., respectively. The maximum absolute errors in total, static, and dynamic pressures are 3.4, 3.9, and 4.9% of the dynamic pressures, respectively. Measurements made with this probe, a conventional five-hole probe and a miniature Pitot probe across a calibration section, demonstrated that the errors due to gradient and surface proximity for this probe are considerably reduced compared to the five-hole probe.

  2. Correcting the error in neutron moisture probe measurements caused by a water density gradient

    International Nuclear Information System (INIS)

    Wilson, D.J.

    1988-01-01

    If a neutron probe lies in or near a water density gradient, the probe may register a water density different to that at the measuring point. The effect of a thin stratum of soil containing an excess or depletion of water at various distances from a probe in an otherwise homogeneous system has been calculated, producing an 'importance' curve. The effect of these strata can be integrated over the soil region in close proximity to the probe resulting in the net effect of the presence of a water density gradient. In practice, the probe is scanned through the point of interest and the count rate at that point is corrected for the influence of the water density on each side of it. An example shows that the technique can reduce an error of 10 per cent to about 2 per cent

  3. Occupational exposure measurements of static and pulsed gradient magnetic fields in the vicinity of MRI scanners

    Energy Technology Data Exchange (ETDEWEB)

    Kaennaelae, Sami; Toivo, Tim; Jokela, Kari [STUK-Radiation and Nuclear Safety Authority, PO Box 14, 00881 Helsinki (Finland); Alanko, Tommi [Finnish Institute of Occupational Health, New Technologies and Risks, Topeliuksenkatu 41a A, 00250 Helsinki (Finland)], E-mail: sami.kannala@stuk.fi

    2009-04-07

    Recent advances in magnetic resonance imaging (MRI) have increased occupational exposure to magnetic fields. In this study, we examined the assessment of occupational exposure to gradient magnetic fields and time-varying magnetic fields generated by motion in non-homogeneous static magnetic fields of MRI scanners. These magnetic field components can be measured simultaneously with an induction coil setup that detects the time rate of change of magnetic flux density (dB/dt). The setup developed was used to measure the field components around two MRI units (1 T open and 3 T conventional). The measured values can be compared with dB/dt reference levels derived from magnetic flux density reference levels given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The measured motion-induced dB/dt values were above the dB/dt reference levels for both MRI units. The measured values for the gradient fields (echo planar imaging (EPI) and fast field echo (FFE) sequences) also exceeded the dB/dt reference levels in positions where the medical staff may have access during interventional procedures. The highest motion-induced dB/dt values were 0.7 T s{sup -1} for the 1 T scanner and 3 T s{sup -1} for the 3 T scanner when only the static field was present. Even higher values (6.5 T s{sup -1}) were measured for simultaneous exposure to motion-induced and gradient fields in the vicinity of the 3 T scanner.

  4. Potential uses of high gradient magnetic filtration for high-temperature water purification in boiling water reactors

    International Nuclear Information System (INIS)

    Elliott, H.H.; Holloway, J.H.; Abbott, D.G.

    1979-01-01

    Studies of various high-temperature filter devices indicate a potentially positive impact for high gradient magnetic filtration on boiling water reactor radiation level reduction. Test results on in-plant water composition and impurity crystallography are presented for several typical boiling water reactors (BWRs) on plant streams where high-temperature filtration may be particularly beneficial. An experimental model on the removal of red iron oxide (hematite) from simulated reactor water with a high gradient magnetic filter is presented, as well as the scale-up parameters used to predict the filtration efficiency on various high temperature, in-plant streams. Numerical examples are given to illustrate the crud removal potential of high gradient magnetic filters installed at alternative stream locations under typical, steady-state, plant operating conditions

  5. Variance gradients and uncertainty budgets for nonlinear measurement functions with independent inputs

    International Nuclear Information System (INIS)

    Campanelli, Mark; Kacker, Raghu; Kessel, Rüdiger

    2013-01-01

    A novel variance-based measure for global sensitivity analysis, termed a variance gradient (VG), is presented for constructing uncertainty budgets under the Guide to the Expression of Uncertainty in Measurement (GUM) framework for nonlinear measurement functions with independent inputs. The motivation behind VGs is the desire of metrologists to understand which inputs' variance reductions would most effectively reduce the variance of the measurand. VGs are particularly useful when the application of the first supplement to the GUM is indicated because of the inadequacy of measurement function linearization. However, VGs reduce to a commonly understood variance decomposition in the case of a linear(ized) measurement function with independent inputs for which the original GUM readily applies. The usefulness of VGs is illustrated by application to an example from the first supplement to the GUM, as well as to the benchmark Ishigami function. A comparison of VGs to other available sensitivity measures is made. (paper)

  6. A STUDY OF SOLAR PHOTOSPHERIC TEMPERATURE GRADIENT VARIATION USING LIMB DARKENING MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Criscuoli, Serena [National Solar Observatory, Boulder, CO 80303 (United States); Foukal, Peter [192 Willow Road, Nahant, MA 01908 (United States)

    2017-01-20

    The variation in area of quiet magnetic network measured over the sunspot cycle should modulate the spatially averaged photospheric temperature gradient, since temperature declines with optical depth more gradually in magnetic flux tube atmospheres. Yet, limb darkening measurements show no dependence upon activity level, even at an rms precision of 0.04%. We study the sensitivity of limb darkening to changes in area filling factor using a 3D MHD model of the magnetized photosphere. The limb darkening change expected from the measured 11-year area variation lies below the level of measured limb darkening variations, for a reasonable range of magnetic flux in quiet network and internetwork regions. So the remarkably constant limb darkening observed over the solar activity cycle is not inconsistent with the measured 11-year change in area of quiet magnetic network. Our findings offer an independent constraint on photospheric temperature gradient changes reported from measurements of the solar spectral irradiance from the Spectral Irradiance Monitor, and recently, from wavelength-differential spectrophotometry using the Solar Optical Telescope aboard the HINODE spacecraft.

  7. Measurement of time dependent fields in high gradient superconducting quadrupoles for the Tevatron

    International Nuclear Information System (INIS)

    Lamm, M.J.; Coulter, K.; Gourlay, S.; Jaffery, T.S.

    1990-10-01

    Magnetic field measurements have been performed on prototype and production magnets from two high gradient superconducting quadrupoles designs. One design is a double shell quadrupole with 36 strand Rutherford cable. The other design is a single shell quadrupole with 5 individually monolithic strands connected in series. These magnets have similar bore diameters and cable dimensions. However, there are significant differences between the two designs, as well as differences between prototype and production magnets within each design, with regard to Cu to superconductor ratio, filament diameter and filament spacing to strand diameter. The time dependence of fixed currents of the measured magnetic fields is discussed. 9 refs., 6 figs., 1 tab

  8. Magnetic field gradients inferred from multi-point measurements of Cluster FGM and EDI

    Science.gov (United States)

    Teubenbacher, Robert; Nakamura, Rumi; Giner, Lukas; Plaschke, Ferdinand; Baumjohann, Wolfgang; Magnes, Werner; Eichelberger, Hans; Steller, Manfred; Torbert, Roy

    2013-04-01

    We use Cluster data from fluxgate magnetometer (FGM) and electron drift instrument (EDI) to determine the magnetic field gradients in the near-Earth magnetotail. Here we use the magnetic field data from FGM measurements as well as the gyro-time data of electrons determined from the time of flight measurements of EDI. The results are compared with the values estimated from empirical magnetic field models for different magnetospheric conditions. We also estimated the spin axis offset of FGM based on comparison between EDI and FGM data and discuss the possible effect in determining the current sheet characteristics.

  9. Vertical gradients of nitrous acid (HONO) measured in Beijing during winter smog events.

    Science.gov (United States)

    Kramer, Louisa; Crilley, Leigh; Thomson, Steven; Bloss, William; Tong, Shengrui

    2017-04-01

    HONO is an important atmospheric constituent, as the photolysis of HONO leads to the formation of OH radicals in the boundary layer, with contributions of up to 60% in urban regions. This is particularly important in mega-cities, such as Beijing, where measured HONO levels can reach parts per billion. Research has shown that direct emissions, homogeneous gas phase reactions and heterogeneous conversion of NO2 on surfaces all contribute to HONO in urban areas. There are, however, still uncertainties regarding the magnitude of these sources, and models are still unable to account for total measured HONO mixing ratios. To assess the sources of HONO, vertical profile measurements were performed up to an altitude of 260 m on the Institute of Atmospheric Physics (IAP) Meteorological Tower in Beijing. These measurements were performed as part of the Air Pollution and Human Health (APHH) project, during Nov/Dec 2016. Here we present HONO profile measurements using a long-path absorption photometer (LOPAP), during both clear and hazy days. HONO levels near the ground were very high during smog events with concentrations over 10 ppb observed. The data show a strong negative gradient with altitude, suggesting a source close to the surface. The largest gradients were observed overnight during smog events, with differences in HONO between the ground and the highest level up to 6 ppb.

  10. Coherent gradient sensing method for measuring thermal stress field of thermal barrier coating structures

    Directory of Open Access Journals (Sweden)

    Kang Ma

    2017-01-01

    Full Text Available Coherent gradient sensing (CGS method can be used to measure the slope of a reflective surface, and has the merits of full-field, non-contact, and real-time measurement. In this study, the thermal stress field of thermal barrier coating (TBC structures is measured by CGS method. Two kinds of powders were sprayed onto Ni-based alloy using a plasma spraying method to obtain two groups of film–substrate specimens. The specimens were then heated with an oxy-acetylene flame. The resulting thermal mismatch between the film and substrate led to out-of-plane deformation of the specimen. The deformation was measured by the reflective CGS method and the thermal stress field of the structure was obtained through calibration with the help of finite element analysis. Both the experiment and numerical results showed that the thermal stress field of TBC structures can be successfully measured by CGS method.

  11. Relative nitrogen mineralization and nitrification potentials in relation to soil chemistry in oak forest soils along a historical deposition gradient

    Science.gov (United States)

    Ralph E. J. Boerner; Elaine Kennedy Sutherland

    1996-01-01

    This study quantified soil nutrient status and N mineralization/nitrification potentials in soils of oak-dominated, unmanaged forest stands in seven USDA Forest Service experimental forests (EF) ranging along a historical and current acidic deposition gradient from southern Illinois to central West Virginia.

  12. Measurement of human potential in organizations

    Directory of Open Access Journals (Sweden)

    Rosa María Fuchs Ángeles

    2015-09-01

    Full Text Available Companies around the world are concerned about talent management in their organizations. The concern is to retain talented employees and this may not be possible if they are not properly identified. Performance and potential evaluations become then important. Performance evaluations qualify the historical record of the employee, so their measurement is provided. However, measuring the potential performance assesses potential future charges, therefore it is not a simple task. In this paper, characteristics evaluated in potential employees and tools that are commonly used are presented. Also, the case of four companies operating in Peru is shown.

  13. Influence of internal refractive index gradients on size measurements of spherically symmetric particles by phase Doppler anemometry.

    Science.gov (United States)

    Schneider, M; Hirleman, E D

    1994-04-20

    A model based on geometric optics for predicting the response of interferometric (phase Doppler) instruments for size measurements of particles with radially symmetric but inhomogeneous internal refractive index profiles is developed. The model and results are important for applications in which heat or mass transfer from the particles or droplets is significant, for example, in liquid-fuel combustion. To quantify the magnitude of potential bias errors introduced by the classical assumption of uniform internal properties on phase Doppler measurements, we compute calibration curves for a sequence of times during the evaporation of a decane droplet immersed in an environment of T = 2000 K and p = 10 bars. The results reveal considerable effects on the relation between phase difference and droplet diameter caused by the refractive index gradients present. The model provides an important tool to assess sizing uncertainties that can be expected when applying conventional (based on uniform properties) phase Doppler calibration curves in spray combustion and similar processes.

  14. Ellipsometry measurements of glass transition breadth in bulk films of random, block, and gradient copolymers.

    Science.gov (United States)

    Mok, M M; Kim, J; Marrou, S R; Torkelson, J M

    2010-03-01

    Bulk films of random, block and gradient copolymer systems were studied using ellipsometry to demonstrate the applicability of the numerical differentiation technique pioneered by Kawana and Jones for studying the glass transition temperature (T (g)) behavior and thermal expansivities of copolymers possessing different architectures and different levels of nanoheterogeneity. In a series of styrene/n -butyl methacrylate (S/nBMA) random copolymers, T (g) breadths were observed to increase from approximately 17( degrees ) C in styrene-rich cases to almost 30( degrees ) C in nBMA-rich cases, reflecting previous observations of significant nanoheterogeneity in PnBMA homopolymers. The derivative technique also revealed for the first time a substantial increase in glassy-state expansivity with increasing nBMA content in S/nBMA random copolymers, from 1.4x10(-4) K-1 in PS to 3.5x10(-4) K-1 in PnBMA. The first characterization of block copolymer T (g) 's and T (g) breadths by ellipsometry is given, examining the impact of nanophase-segregated copolymer structure on ellipsometric measurements of glass transition. The results show that, while the technique is effective in detecting the two T (g) 's expected in certain block copolymer systems, the details of the glass transition can become suppressed in ellipsometry measurements of a rubbery minor phase under conditions where the matrix is glassy; meanwhile, both transitions are easily discernible by differential scanning calorimetry. Finally, broad glass transition regions were measured in gradient copolymers, yielding in some cases extraordinary T (g) breadths of 69- 71( degrees ) C , factors of 4-5 larger than the T (g) breadths of related homopolymers and random copolymers. Surprisingly, one gradient copolymer demonstrated a slightly narrower T (g) breadth than the S/nBMA random copolymers with the highest nBMA content. This highlights the fact that nanoheterogeneity relevant to the glass transition response in selected

  15. Diffusion-assisted selective dynamical recoupling: A new approach to measure background gradients in magnetic resonance

    Science.gov (United States)

    Álvarez, Gonzalo A.; Shemesh, Noam; Frydman, Lucio

    2014-02-01

    Dynamical decoupling, a generalization of the original NMR spin-echo sequence, is becoming increasingly relevant as a tool for reducing decoherence in quantum systems. Such sequences apply non-equidistant refocusing pulses for optimizing the coupling between systems, and environmental fluctuations characterized by a given noise spectrum. One such sequence, dubbed Selective Dynamical Recoupling (SDR) [P. E. S. Smith, G. Bensky, G. A. Álvarez, G. Kurizki, and L. Frydman, Proc. Natl. Acad. Sci. 109, 5958 (2012)], allows one to coherently reintroduce diffusion decoherence effects driven by fluctuations arising from restricted molecular diffusion [G. A. Álvarez, N. Shemesh, and L. Frydman, Phys. Rev. Lett. 111, 080404 (2013)]. The fully-refocused, constant-time, and constant-number-of-pulses nature of SDR also allows one to filter out "intrinsic" T1 and T2 weightings, as well as pulse errors acting as additional sources of decoherence. This article explores such features when the fluctuations are now driven by unrestricted molecular diffusion. In particular, we show that diffusion-driven SDR can be exploited to investigate the decoherence arising from the frequency fluctuations imposed by internal gradients. As a result, SDR presents a unique way of probing and characterizing these internal magnetic fields, given an a priori known free diffusion coefficient. This has important implications in studies of structured systems, including porous media and live tissues, where the internal gradients may serve as fingerprints for the system's composition or structure. The principles of this method, along with full analytical solutions for the unrestricted diffusion-driven modulation of the SDR signal, are presented. The potential of this approach is demonstrated with the generation of a novel source of MRI contrast, based on the background gradients active in an ex vivo mouse brain. Additional features and limitations of this new method are discussed.

  16. Diffusion-assisted selective dynamical recoupling: A new approach to measure background gradients in magnetic resonance

    International Nuclear Information System (INIS)

    Álvarez, Gonzalo A.; Shemesh, Noam; Frydman, Lucio

    2014-01-01

    Dynamical decoupling, a generalization of the original NMR spin-echo sequence, is becoming increasingly relevant as a tool for reducing decoherence in quantum systems. Such sequences apply non-equidistant refocusing pulses for optimizing the coupling between systems, and environmental fluctuations characterized by a given noise spectrum. One such sequence, dubbed Selective Dynamical Recoupling (SDR) [P. E. S. Smith, G. Bensky, G. A. Álvarez, G. Kurizki, and L. Frydman, Proc. Natl. Acad. Sci. 109, 5958 (2012)], allows one to coherently reintroduce diffusion decoherence effects driven by fluctuations arising from restricted molecular diffusion [G. A. Álvarez, N. Shemesh, and L. Frydman, Phys. Rev. Lett. 111, 080404 (2013)]. The fully-refocused, constant-time, and constant-number-of-pulses nature of SDR also allows one to filter out “intrinsic” T 1 and T 2 weightings, as well as pulse errors acting as additional sources of decoherence. This article explores such features when the fluctuations are now driven by unrestricted molecular diffusion. In particular, we show that diffusion-driven SDR can be exploited to investigate the decoherence arising from the frequency fluctuations imposed by internal gradients. As a result, SDR presents a unique way of probing and characterizing these internal magnetic fields, given an a priori known free diffusion coefficient. This has important implications in studies of structured systems, including porous media and live tissues, where the internal gradients may serve as fingerprints for the system's composition or structure. The principles of this method, along with full analytical solutions for the unrestricted diffusion-driven modulation of the SDR signal, are presented. The potential of this approach is demonstrated with the generation of a novel source of MRI contrast, based on the background gradients active in an ex vivo mouse brain. Additional features and limitations of this new method are discussed

  17. Characterization of the startup transient electrokinetic flow in rectangular channels of arbitrary dimensions, zeta potential distribution, and time-varying pressure gradient.

    Science.gov (United States)

    Miller, Andrew; Villegas, Arturo; Diez, F Javier

    2015-03-01

    The solution to the startup transient EOF in an arbitrary rectangular microchannel is derived analytically and validated experimentally. This full 2D transient solution describes the evolution of the flow through five distinct periods until reaching a final steady state. The derived analytical velocity solution is validated experimentally for different channel sizes and aspect ratios under time-varying pressure gradients. The experiments used a time resolved micro particle image velocimetry technique to calculate the startup transient velocity profiles. The measurements captured the effect of time-varying pressure gradient fields derived in the analytical solutions. This is tested by using small reservoirs at both ends of the channel which allowed a time-varying pressure gradient to develop with a time scale on the order of the transient EOF. Results showed that under these common conditions, the effect of the pressure build up in the reservoirs on the temporal development of the transient startup EOF in the channels cannot be neglected. The measurements also captured the analytical predictions for channel walls made of different materials (i.e., zeta potentials). This was tested in channels that had three PDMS and one quartz wall, resulting in a flow with an asymmetric velocity profile due to variations in the zeta potential between the walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Evaluation of stress gradient by x-ray stress measurement based on change in angle phi

    International Nuclear Information System (INIS)

    Sasaki, Toshihiko; Kuramoto, Makoto; Yoshioka, Yasuo.

    1985-01-01

    A new principle of X-ray stress evaluation for a sample with steep stress gradient has been prosed. The feature of this method is that the stress is determined by using so-called phi-method based on the change of phi-angle and thus has no effect on the penetration depth of X-rays. The procedure is as follows; firstly, an average stress within the penetration depth of X-rays is determined by changing only phi-angle under a fixed psi-angle, and then a distribution of the average stress vs. the penetration depth of X-rays is detected by repeating the similar procedure at different psi-angles. The following conclusions were found out as the result of residual stress measurements on a carbon steel of type S 55 C polished by emery paper. This method is practical enough to use for a plane stress problem. And the assumption of a linear stress gradient adopted in the authors' previous investigations is valid. In case of a triaxial stress analysis, this method is effective for the solution of three shearing stresses. However, three normal stresses can not be solved perfectly except particular psi-angles. (author)

  19. Adaptive filtering of GOCE-derived gravity gradients of the disturbing potential in the context of the space-wise approach

    Science.gov (United States)

    Piretzidis, Dimitrios; Sideris, Michael G.

    2017-09-01

    Filtering and signal processing techniques have been widely used in the processing of satellite gravity observations to reduce measurement noise and correlation errors. The parameters and types of filters used depend on the statistical and spectral properties of the signal under investigation. Filtering is usually applied in a non-real-time environment. The present work focuses on the implementation of an adaptive filtering technique to process satellite gravity gradiometry data for gravity field modeling. Adaptive filtering algorithms are commonly used in communication systems, noise and echo cancellation, and biomedical applications. Two independent studies have been performed to introduce adaptive signal processing techniques and test the performance of the least mean-squared (LMS) adaptive algorithm for filtering satellite measurements obtained by the gravity field and steady-state ocean circulation explorer (GOCE) mission. In the first study, a Monte Carlo simulation is performed in order to gain insights about the implementation of the LMS algorithm on data with spectral behavior close to that of real GOCE data. In the second study, the LMS algorithm is implemented on real GOCE data. Experiments are also performed to determine suitable filtering parameters. Only the four accurate components of the full GOCE gravity gradient tensor of the disturbing potential are used. The characteristics of the filtered gravity gradients are examined in the time and spectral domain. The obtained filtered GOCE gravity gradients show an agreement of 63-84 mEötvös (depending on the gravity gradient component), in terms of RMS error, when compared to the gravity gradients derived from the EGM2008 geopotential model. Spectral-domain analysis of the filtered gradients shows that the adaptive filters slightly suppress frequencies in the bandwidth of approximately 10-30 mHz. The limitations of the adaptive LMS algorithm are also discussed. The tested filtering algorithm can be

  20. Electron critical gradient scale length measurements of ICRF heated L-mode plasmas at Alcator C-Mod tokamak

    Science.gov (United States)

    Houshmandyar, S.; Hatch, D. R.; Horton, C. W.; Liao, K. T.; Phillips, P. E.; Rowan, W. L.; Zhao, B.; Cao, N. M.; Ernst, D. R.; Greenwald, M.; Howard, N. T.; Hubbard, A. E.; Hughes, J. W.; Rice, J. E.

    2018-04-01

    A profile for the critical gradient scale length (Lc) has been measured in L-mode discharges at the Alcator C-Mod tokamak, where electrons were heated by an ion cyclotron range of frequency through minority heating with the intention of simultaneously varying the heat flux and changing the local gradient. The electron temperature gradient scale length (LTe-1 = |∇Te|/Te) profile was measured via the BT-jog technique [Houshmandyar et al., Rev. Sci. Instrum. 87, 11E101 (2016)] and it was compared with electron heat flux from power balance (TRANSP) analysis. The Te profiles were found to be very stiff and already above the critical values, however, the stiffness was found to be reduced near the q = 3/2 surface. The measured Lc profile is in agreement with electron temperature gradient (ETG) models which predict the dependence of Lc-1 on local Zeff, Te/Ti, and the ratio of the magnetic shear to the safety factor. The results from linear Gene gyrokinetic simulations suggest ETG to be the dominant mode of turbulence in the electron scale (k⊥ρs > 1), and ion temperature gradient/trapped electron mode modes in the ion scale (k⊥ρs < 1). The measured Lc profile is in agreement with the profile of ETG critical gradients deduced from Gene simulations.

  1. Spatial analyses of benthic habitats to define coral reef ecosystem regions and potential biogeographic boundaries along a latitudinal gradient.

    Directory of Open Access Journals (Sweden)

    Brian K Walker

    Full Text Available Marine organism diversity typically attenuates latitudinally from tropical to colder climate regimes. Since the distribution of many marine species relates to certain habitats and depth regimes, mapping data provide valuable information in the absence of detailed ecological data that can be used to identify and spatially quantify smaller scale (10 s km coral reef ecosystem regions and potential physical biogeographic barriers. This study focused on the southeast Florida coast due to a recognized, but understudied, tropical to subtropical biogeographic gradient. GIS spatial analyses were conducted on recent, accurate, shallow-water (0-30 m benthic habitat maps to identify and quantify specific regions along the coast that were statistically distinct in the number and amount of major benthic habitat types. Habitat type and width were measured for 209 evenly-spaced cross-shelf transects. Evaluation of groupings from a cluster analysis at 75% similarity yielded five distinct regions. The number of benthic habitats and their area, width, distance from shore, distance from each other, and LIDAR depths were calculated in GIS and examined to determine regional statistical differences. The number of benthic habitats decreased with increasing latitude from 9 in the south to 4 in the north and many of the habitat metrics statistically differed between regions. Three potential biogeographic barriers were found at the Boca, Hillsboro, and Biscayne boundaries, where specific shallow-water habitats were absent further north; Middle Reef, Inner Reef, and oceanic seagrass beds respectively. The Bahamas Fault Zone boundary was also noted where changes in coastal morphologies occurred that could relate to subtle ecological changes. The analyses defined regions on a smaller scale more appropriate to regional management decisions, hence strengthening marine conservation planning with an objective, scientific foundation for decision making. They provide a framework

  2. Computer simulation of pitting potential measurements

    International Nuclear Information System (INIS)

    Laycock, N.J.; Noh, J.S.; White, S.P.; Krouse, D.P.

    2005-01-01

    A deterministic model for the growth of single pits in stainless steel has been combined with a purely stochastic model of pit nucleation. Monte-Carlo simulations have been used to compare the predictions of this model with potentiodynamic experimental measurements of the pitting potential. The quantitative agreement between model and experiment is reasonable for both 304 and 316 stainless steel, and the effects of varying surface roughness, solution chloride concentration and potential sweep rate have been considered

  3. Theoretical repeatability assessment without repetitive measurements in gradient high-performance liquid chromatography.

    Science.gov (United States)

    Kotani, Akira; Tsutsumi, Risa; Shoji, Asaki; Hayashi, Yuzuru; Kusu, Fumiyo; Yamamoto, Kazuhiro; Hakamata, Hideki

    2016-07-08

    This paper puts forward a time and material-saving method for evaluating the repeatability of area measurements in gradient HPLC with UV detection (HPLC-UV), based on the function of mutual information (FUMI) theory which can theoretically provide the measurement standard deviation (SD) and detection limits through the stochastic properties of baseline noise with no recourse to repetitive measurements of real samples. The chromatographic determination of terbinafine hydrochloride and enalapril maleate is taken as an example. The best choice of the number of noise data points, inevitable for the theoretical evaluation, is shown to be 512 data points (10.24s at 50 point/s sampling rate of an A/D converter). Coupled with the relative SD (RSD) of sample injection variability in the instrument used, the theoretical evaluation is proved to give identical values of area measurement RSDs to those estimated by the usual repetitive method (n=6) over a wide concentration range of the analytes within the 95% confidence intervals of the latter RSD. The FUMI theory is not a statistical one, but the "statistical" reliability of its SD estimates (n=1) is observed to be as high as that attained by thirty-one measurements of the same samples (n=31). Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    Science.gov (United States)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C., Jr.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2018-04-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T e ) and its fluctuations (δT e ). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects, the scrape-off layer region is not accessible to the ECEI measurements in steady state conditions and that the signal is dominated by the shine-through emission. Transient effects, such as filaments, can change the radiation transport locally, but cannot be distinguished from the shine-through. Local density measurements are essential for the correct interpretation of the electron cyclotron emission, since the density fluctuations influence the temperature measurements at the plasma edge. As an example, a low frequency 8 kHz mode, which causes 10%-15% fluctuations in the signal level of the ECEI, is analysed. The same mode has been measured with the lithium beam emission spectroscopy density diagnostic, and is very well correlated in time with high frequency magnetic fluctuations. With radiation transport modelling of the electron cyclotron radiation in the ECEI geometry, it is shown that the density contributes significantly to the radiation temperature (T rad) and the experimental observations have shown the amplitude modulation in both density and temperature measurements. The poloidal velocity of the low frequency mode measured by the ECEI is 3 km s-1. The calculated velocity of the high frequency mode measured with the magnetic pick-up coils is about 25 km s-1. Velocities are compared with the E × B background flow velocity and possible explanations for the origin of the low frequency mode are discussed.

  5. Real-time positioning technology in horizontal directional drilling based on magnetic gradient tensor measurement

    Science.gov (United States)

    Deng, Guoqing; Yao, Aiguo

    2017-04-01

    Horizontal directional drilling (HDD) technology has been widely used in Civil Engineering. The dynamic position of the drill bit during construction is one of significant facts determining the accuracy of the trajectory of HDD. A new method now has been proposed to detecting the position of drill bit by measuring the magnetic gradient tensor of the ground solenoid magnetic beacon. Compared with traditional HDD positioning technologies, this new model is much easier to apply with lower request for construction sites and higher positioning efficiency. A direct current (DC) solenoid as a magnetic dipole is placed on ground near the drill bit, and related sensors array which contains four Micro-electromechanical Systems (MEMS ) tri-axial magnetometers, one MEMS tri-axial accelerometer and one MEMS tri-axial gyroscope is set up for measuring the magnetic gradient tensor of the magnetic dipole. The related HDD positioning model has been established and simulation experiments have been carried out to verify the feasibility and reliability of the proposed method. The experiments show that this method has good positioning accuracy in horizontal and vertical direction, and totally avoid the impact of the environmental magnetic field. It can be found that the posture of the magnetic beacon will impact the remote positioning precision within valid positioning range, and the positioning accuracy is higher with longer baseline for limited space in drilling tools. The results prove that the relative error can be limited in 2% by adjusting position of the magnetic beacon, the layers of the enameled coil, the sensitive of magnetometers and the baseline distance. Conclusion can be made that this new method can be applied in HDD positioning with better effect and wider application range than traditional method.

  6. MRI measurements of intracranial pressure in the upright posture: The effect of the hydrostatic pressure gradient.

    Science.gov (United States)

    Alperin, Noam; Lee, Sang H; Bagci, Ahmet M

    2015-10-01

    To add the hydrostatic component of the cerebrospinal fluid (CSF) pressure to magnetic resonance imaging (MRI)-derived intracranial pressure (ICP) measurements in the upright posture for derivation of pressure value in a central cranial location often used in invasive ICP measurements. Additional analyses were performed using data previously collected from 10 healthy subjects scanned in supine and sitting positions with a 0.5T vertical gap MRI scanner (GE Medical). Pulsatile blood and CSF flows to and from the brain were quantified using cine phase-contrast. Intracranial compliance and pressure were calculated using a previously described method. The vertical distance between the location of the CSF flow measurement and a central cranial location was measured manually in the mid-sagittal T1 -weighted image obtained in the upright posture. The hydrostatic pressure gradient of a CSF column with similar height was then added to the MR-ICP value. After adjustment for the hydrostatic component, the mean ICP value was reduced by 7.6 mmHg. Mean ICP referenced to the central cranial level was -3.4 ± 1.7 mmHg compared to the unadjusted value of +4.3 ± 1.8 mmHg. In the upright posture, the hydrostatic pressure component needs to be added to the MRI-derived ICP values for compatibility with invasive ICP at a central cranial location. © 2015 Wiley Periodicals, Inc.

  7. Potential use of gradient denaturing gel electrophoresis in obtaining mutational spectra from human cells

    International Nuclear Information System (INIS)

    Thilly, W.G.

    1985-01-01

    A method is described to isolate mutations in DNA in human cells. When a double-stranded DNA migrates through an electric field on an electrophoretic gel, it is compact hydrodynamic structure relative to the same material in a melted form. Normally the solution in electrophoretic gels is uniform, but a way has been devised to set up a stable gradient of increasing solute concentration in the direction of DNA motion. Thus, as a double-stranded DNA molecule is drawn by the electric field into higher and higher concentrations of urea/formamide, it will eventually reach a point at which the concentration is high enough to melt the lower-melting-point region. The melting results in an essentially immobile structure within the gel so that the position at which the DNA molecule stops on the gradient gel is determined by its melting point, which is uniquely determined by its nucleotide sequence. A single base pair substitution within a low melting point sequence of some 100 base pairs changed the expected melting point by 0.4 0 C and resulted in about a 2-cm displacement under appropriate denaturing gel conditions. This expectation leads to the idea that if a mixture of DNA sequences derived from point mutations within the same restriction fragment were permitted to anneal with a complementary wild-type sequence, the melting point of each type of heteroduplex would differ depending on the kind and position of each mutation

  8. Calibration of colour gradient bias in shear measurement using HST/CANDELS data

    Science.gov (United States)

    Er, X.; Hoekstra, H.; Schrabback, T.; Cardone, V. F.; Scaramella, R.; Maoli, R.; Vicinanza, M.; Gillis, B.; Rhodes, J.

    2018-06-01

    Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity for a broad-band observation can lead to new subtle effects that could hitherto be ignored: the PSF of a galaxy is no longer uniquely defined and spatial variations in the colours of galaxies result in biases in the inferred lensing signal. Taking Euclid as a reference, we show that this colour gradient bias (CG bias) can be quantified with high accuracy using available multicolour Hubble Space Telescope (HST) data. In particular we study how noise in the HST observations might impact such measurements and find this to be negligible. We determine the CG bias using HST observations in the F606W and F814W filters and observe a correlation with the colour, in line with expectations, whereas the dependence with redshift is weak. The biases for individual galaxies are generally well below 1 per cent, which may be reduced further using morphological information from the Euclid data. Our results demonstrate that CG bias should not be ignored, but it is possible to determine its amplitude with sufficient precision, so that it will not significantly bias the weak lensing measurements using Euclid data.

  9. Standard Test Method for Measuring Heat Flux Using Flush-Mounted Insert Temperature-Gradient Gages

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method describes the measurement of the net heat flux normal to a surface using gages inserted flush with the surface. The geometry is the same as heat-flux gages covered by Test Method E 511, but the measurement principle is different. The gages covered by this standard all use a measurement of the temperature gradient normal to the surface to determine the heat that is exchanged to or from the surface. Although in a majority of cases the net heat flux is to the surface, the gages operate by the same principles for heat transfer in either direction. 1.2 This general test method is quite broad in its field of application, size and construction. Two different gage types that are commercially available are described in detail in later sections as examples. A summary of common heat-flux gages is given by Diller (1). Applications include both radiation and convection heat transfer. The gages used for aerospace applications are generally small (0.155 to 1.27 cm diameter), have a fast time response ...

  10. AirSWOT Measurements of Water Surface Elevations and Hydraulic Gradients over the Yukon Flats, Alaska

    Science.gov (United States)

    Pitcher, L. H.; Pavelsky, T.; Smith, L. C.; Moller, D.; Altenau, E. H.; Lion, C.; Bertram, M.; Cooley, S. W.

    2017-12-01

    AirSWOT is an airborne, Ka-band synthetic aperture radar interferometer (InSAR) intended to quantify surface water fluxes by mapping water surface elevations (WSE). AirSWOT will also serve as a calibration/validation tool for the Surface Water and Ocean Topography (SWOT) satellite mission (scheduled for launch in 2021). The hydrology objectives for AirSWOT and SWOT are to measure WSE with accuracies sufficient to estimate hydrologic fluxes in lakes, wetlands and rivers. However, current understanding of the performance of these related though not identical instruments when applied to complex river-lake-wetland fluvial environments remains predominantly theoretical. We present AirSWOT data acquired 15-June-2015 over the Yukon Flats, Alaska, USA, together with in situ field surveys, to assess the accuracy of AirSWOT WSE measurements in lakes and rivers. We use these data to demonstrate that AirSWOT can be used to estimate large-scale hydraulic gradients across wetland complexes. Finally, we present key lessons learned from this AirSWOT analysis for consideration in future campaigns, including: maximizing swath overlap for spatial averaging to minimize uncertainty as well as orienting flight paths parallel to river flow directions to reduce along track aircraft drift for neighboring flight paths. We conclude that spatially dense AirSWOT measurements of river and lake WSEs can improve geospatial understanding of surface water hydrology and fluvial processes.

  11. Accounting for the effect of horizontal gradients in limb measurements of scattered sunlight

    Directory of Open Access Journals (Sweden)

    J. Puķīte

    2008-06-01

    Full Text Available Limb measurements provided by the SCanning Imaging Absorption spectrometer for Atmospheric CHartographY (SCIAMACHY on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale, among them BrO for the first time. For limb observations in the UV/VIS spectral region the instrument measures scattered light with a complex distribution of light paths: the light is measured at different tangent heights and can be scattered or absorbed in the atmosphere or reflected by the ground. By means of spectroscopy and radiative transfer modelling these measurements can be inverted to retrieve the vertical distribution of stratospheric trace gases.

    The fully spherical 3-D Monte Carlo radiative transfer model "Tracy-II" is applied in this study. The Monte Carlo method benefits from conceptual simplicity and allows realizing the concept of full spherical geometry of the atmosphere and also its 3-D properties, which is important for a realistic description of the limb geometry. Furthermore it allows accounting for horizontal gradients in the distribution of trace gases.

    In this study the effect of horizontally inhomogeneous distributions of trace gases along flight/viewing direction on the retrieval of profiles is investigated. We introduce a tomographic method to correct for this effect by combining consecutive limb scanning sequences and utilizing the overlap in their measurement sensitivity regions. It is found that if horizontal inhomogenity is not properly accounted for, typical errors of 20% for NO2 and up to 50% for OClO around the altitude of the profile peak can arise for measurements close to the Arctic polar vortex boundary in boreal winter.

  12. Measurements of ammonia emissions from spreading of manure using gradient FTIR techniques

    DEFF Research Database (Denmark)

    Galle, B.; Klemedtsson, L.; Bergqvist, B.

    2000-01-01

    is derived from simultaneous measurements of a tracer gas released over the area under study. Although not ideal in the actual measurement situation, this latter method has a potential for use on more local sources with less restrictions on micrometeorological conditions, and is thus included for validation...

  13. Insights into soil carbon dynamics across climatic and geologic gradients from temporally-resolved radiocarbon measurements

    Science.gov (United States)

    van der Voort, T. S.; Hagedorn, F.; Mannu, U.; Walthert, L.; McIntyre, C.; Eglinton, T. I.

    2016-12-01

    Soil carbon constitutes the largest terrestrial reservoir of organic carbon, and therefore quantifying soil organic matter dynamics (carbon turnover, stocks and fluxes) across spatial gradients is essential for an understanding of the carbon cycle and the impacts of global change. In particular, links between soil carbon dynamics and different climatic and compositional factors remains poorly understood. Radiocarbon constitutes a powerful tool for unraveling soil carbon dynamics. Temporally-resolved radiocarbon measurements, which take advantage of "bomb-radiocarbon"-driven changes in atmospheric 14C, enable further constraints to be placed on C turnover times. These in turn can yield more precise flux estimates for both upper and deeper soil horizons. This project combines bulk radiocarbon measurements on a suite of soil profiles spanning strong climatic (MAT 1.3-9.2°C, MAP 600 to 2100 mm m-2y-1) and geologic gradients with a more in-depth approach for a subset of locations. For this subset, temporal and carbon-fraction specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Resulting temporally-resolved turnover estimates are coupled to carbon stocks, fluxes across this wide range of forest ecosystems and are examined in the context of environmental drivers (temperature, precipitation, primary production and soil moisture) as well as composition (sand, silt and clay content). Statistical analysis on the region-scale - correlating radiocarbon signature with climatic variables such as temperature, precipitation, primary production and elevation - indicates that composition rather than climate is a key driver of ­­Δ14C signatures. Estimates of carbon turnover, stocks and fluxes derived from temporally-resolved measurements highlight the pivotal role of soil moisture as a

  14. Oxygen gradients in tissue-engineered PEGT/PBT cartilaginous constructs: Measurement and modeling

    NARCIS (Netherlands)

    Malda, J.; Rouwkema, Jeroen; Martens, D.E.; le Comte, EP; Kooy, F.K.; Tramper, J.; van Blitterswijk, Clemens; Riesle, J.U.

    2004-01-01

    The supply of oxygen within three-dimensional tissue-engineered (TE) cartilage polymer constructs is mainly by diffusion. Oxygen consumption by cells results in gradients in the oxygen concentration. The aims of this study were, firstly, to identify the gradients within TE cartilage polymer

  15. Oxygen gradients in tissue-engineered PEGT/PBT cartilaginous constructs: measurement and modeling

    NARCIS (Netherlands)

    Malda, J.; Rouwkema, J.; Martens, D.E.; Paul le Comte, E.; Kooy, F.K.; Tramper, J.; Blitterswijk, van C.A.; Riesle, J.

    2004-01-01

    The supply of oxygen within three-dimensional tissue-engineered (TE) cartilage polymer constructs is mainly by diffusion. Oxygen consumption by cells results in gradients in the oxygen concentration. The aims of this study were, firstly, to identify the gradients within TE: cartilage polymer

  16. Relating soil solution Zn concentration to diffusive gradients in thin films measurements in contaminated soils.

    Science.gov (United States)

    Degryse, Fien; Smolders, Erik; Oliver, Ian; Zhang, Hao

    2003-09-01

    The technique of diffusive gradients in thin films (DGT) has been suggested to sample an available fraction of metals in soil. The objectives of this study were to compare DGT measurements with commonly measured fractions of Zn in soil, viz, the soil solution concentration and the total Zn concentration. The DGT technique was used to measure fluxes and interfacial concentrations of Zn in three series of field-contaminated soils collected in transects toward galvanized electricity pylons and in 15 soils amended with ZnCl2 at six rates. The ratio of DGT-measured concentration to pore water concentration of Zn, R, varied between 0.02 and 1.52 (mean 0.29). This ratio decreased with decreasing distribution coefficient, Kd, of Zn in the soil, which is in agreement with the predictions of the DGT-induced fluxes in soils (DIFS) model. The R values predicted with the DIFS model were generally larger than the observed values in the ZnCl2-amended soils at the higher Zn rates. A modification of the DIFS model indicated that saturation of the resin gel was approached in these soils, despite the short deployment times used (2 h). The saturation of the resin with Zn did not occur in the control soils (no Zn salt added) or the field-contaminated soils. Pore water concentration of Zn in these soils was predicted from the DGT-measured concentration and the total Zn content. Predicted values and observations were generally in good agreement. The pore water concentration was more than 5 times underpredicted for the most acid soil (pH = 3) and for six other soils, for which the underprediction was attributed to the presence of colloidal Zn in the soil solution.

  17. Measurement of Redox Potential in Nanoecotoxicological Investigations

    Directory of Open Access Journals (Sweden)

    Ratna Tantra

    2012-01-01

    Full Text Available Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO or cerium oxide (CeO2 dispersions were measured using an oxidation-reduction potential (ORP electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

  18. Measurement of redox potential in nanoecotoxicological investigations.

    Science.gov (United States)

    Tantra, Ratna; Cackett, Alex; Peck, Roger; Gohil, Dipak; Snowden, Jacqueline

    2012-01-01

    Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO(2))) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

  19. Carbon potential measurement on some actinide carbides

    International Nuclear Information System (INIS)

    Anthonysamy, S.; Ananthasivan, K.; Kaliappan, I.; Chandramouli, V.; Vasudeva Rao, P.R.; Mathews, C.K.; Jacob, K.T.

    1994-01-01

    Uranium-Plutonium mixed carbides with a Pu/(U+Pu) ratio of 0.55 are to be used as the fuel in the Fast Breeder Test Reactor (FBTR) at Kalpakkam, India. Carburization of the stainless steel clad by this fuel is determined by its carbon potential. Because the carbon potential of this fuel composition is not available in the literature, it was measured by the methane-hydrogen gas equilibration technique. The sample was equilibrated with purified hydrogen and the equilibrium methane-to-hydrogen ratio in the gas phase was measured with a flame ionization detector. The carbon potential of the ThC-ThC 2 as well as Mo-Mo 2 C system, which is an important binary in the actinide-fission product-carbon systems, were also measured by this technique in the temperature range 973 to 1,173 K. The data for the Mo-Mo 2 C system are in agreement with values reported in the literature. The results for the ThC-ThC 2 system are different from estimated values with large uncertainty limits given in the literature. The data on (U, Pu) mixed carbides indicates the possibility of stainless steel clad attack under isothermal equilibrium conditions

  20. Effect of diffraction and film-thickness gradients on wafer-curvature measurements of thin-film stress

    International Nuclear Information System (INIS)

    Breiland, W.G.; Lee, S.R.; Koleske, D.D.

    2004-01-01

    When optical measurements of wafer curvature are used to determine thin-film stress, the laser beams that probe the sample are usually assumed to reflect specularly from the curved surface of the film and substrate. Yet, real films are not uniformly thick, and unintended thickness gradients produce optical diffraction effects that steer the laser away from the ideal specular condition. As a result, the deflection of the laser in wafer-curvature measurements is actually sensitive to both the film stress and the film-thickness gradient. We present a Fresnel-Kirchhoff optical diffraction model of wafer-curvature measurements that provides a unified description of these combined effects. The model accurately simulates real-time wafer-curvature measurements of nonuniform GaN films grown on sapphire substrates by vapor-phase epitaxy. During thin-film growth, thickness gradients cause the reflected beam to oscillate asymmetrically about the ideal position defined by the stress-induced wafer curvature. This oscillating deflection has the same periodicity as the reflectance of the growing film, and the deflection amplitude is a function of the film-thickness gradient, the mean film thickness, the wavelength distribution of the light source, the illuminated spot size, and the refractive indices of the film and substrate. For typical GaN films grown on sapphire, misinterpretation of these gradient-induced oscillations can cause stress-measurement errors that approach 10% of the stress-thickness product; much greater errors occur in highly nonuniform films. Only transparent films can exhibit substantial gradient-induced deflections; strongly absorbing films are immune

  1. Application of an online ion-chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur

    Science.gov (United States)

    Rumsey, Ian C.; Walker, John T.

    2016-06-01

    The dry component of total nitrogen and sulfur atmospheric deposition remains uncertain. The lack of measurements of sufficient chemical speciation and temporal extent make it difficult to develop accurate mass budgets and sufficient process level detail is not available to improve current air-surface exchange models. Over the past decade, significant advances have been made in the development of continuous air sampling measurement techniques, resulting with instruments of sufficient sensitivity and temporal resolution to directly quantify air-surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. Here, the performance of the Monitor for AeRosols and GAses in ambient air (MARGA 2S), a commercially available online ion-chromatography-based analyzer is characterized for the first time as applied for air-surface exchange measurements of HNO3, NH3, NH4+, NO3-, SO2 and SO42-. Analytical accuracy and precision are assessed under field conditions. Chemical concentrations gradient precision are determined at the same sampling site. Flux uncertainty measured by the aerodynamic gradient method is determined for a representative 3-week period in fall 2012 over a grass field. Analytical precision and chemical concentration gradient precision were found to compare favorably in comparison to previous studies. During the 3-week period, percentages of hourly chemical concentration gradients greater than the corresponding chemical concentration gradient detection limit were 86, 42, 82, 73, 74 and 69 % for NH3, NH4+, HNO3, NO3-, SO2 and SO42-, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly smaller gradients relative to gas phase species. Relative hourly median flux uncertainties were 31, 121, 42, 43, 67 and 56 % for NH3, NH4+, HNO3, NO3-, SO2 and SO42-, respectively. Flux

  2. Auditory evoked potential measurements in elasmobranchs

    Science.gov (United States)

    Casper, Brandon; Mann, David

    2005-04-01

    Auditory evoked potentials (AEP) were first used to examine hearing in elasmobranchs by Corwin and Bullock in the late 1970s and early 1980s, marking the first time AEPs had been measured in fishes. Results of these experiments identified the regions of the ear and brain in which sound is processed, though no actual hearing thresholds were measured. Those initial experiments provided the ground work for future AEP experiments to measure fish hearing abilities in a manner that is much faster and more convenient than classical conditioning. Data will be presented on recent experiments in which AEPs were used to measure the hearing thresholds of two species of elasmobranchs: the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicencis. Audiograms were analyzed and compared to previously published audiograms obtained using classical conditioning with results indicating that hearing thresholds were similar for the two methods. These data suggest that AEP testing is a viable option when measuring hearing in elasmobranchs and can increase the speed in which future hearing measurements can be obtained.

  3. Leishmania amazonensis chemotaxis under glucose gradient studied by the strength and directionality of forces measured with optical tweezers

    Science.gov (United States)

    de Ysasa Pozzo, Liliana; Fontes, Adriana; de Thomaz, André A.; Barbosa, Luiz Carlos; Ayres, Diana Copi; Giorgio, Selma; Cesar, Carlos Lenz

    2007-02-01

    Chemotaxis is the mechanism microorganisms use to sense the environment surrounding them and to direct their movement towards attractive, or away from the repellent, chemicals. The biochemical sensing is almost the only way for communication between unicellular organisms. Prokaryote and Eukaryote chemotaxis has been mechanically studied mainly by observing the directionality and timing of the microorganisms movements subjected to a chemical gradient, but not through the directionality and strength of the forces it generates. To observe the vector force of microorganisms under a chemical gradient we developed a system composed of two large chambers connected by a tiny duct capable to keep the chemical gradient constant for more than ten hours. We also used the displacements of a microsphere trapped in an Optical Tweezers as the force transducer to measure the direction and the strength of the propulsion forces of flagellum of the microorganism under several gradient conditions. A 9μm diameter microsphere particle was trapped with a Nd:YAG laser and its movement was measured through the light scattered focused on a quadrant detector. We observed the behavior of the protozoa Leishmania amazonensis (eukaryote) under several glucose gradients. This protozoa senses the gradient around it by swimming in circles for three to five times following by tumbling, and not by the typical straight swimming/tumbling of bacteria. Our results also suggest that force direction and strength are also used to control its movement, not only the timing of swimming/tumbling, because we observed a higher force strength clearly directed towards the glucose gradient.

  4. Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

    Science.gov (United States)

    Tang, Enling; Zhao, Liangliang; Han, Yafei; Zhang, Qingming; Wang, Ruizhi; He, Liping; Liu, Shuhua

    2018-04-01

    Due to the actual situation of spacecraft surface' charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane), respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low-potential target by forming

  5. Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

    Directory of Open Access Journals (Sweden)

    Enling Tang

    2018-04-01

    Full Text Available Due to the actual situation of spacecraft surface’ charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane, respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low-potential

  6. Finite Element Analysis of Multilayered and Functionally Gradient Tribological Coatings With Measured Material Properties (Preprint)

    National Research Council Canada - National Science Library

    Kang, Young S; Sharma, Shashi K; Sanders, Jeffrey H; Voevodin, Andrey A

    2006-01-01

    ...) gradient coatings with diamond like carbon (DLC) coating on 440C stainless steel substrate were assumed as a series of perfectly bonded layers with unique material properties and layer thickness...

  7. Precise measurement of magnetic field gradients from free spin precession signals of He-3 and Xe-129 magnetometers

    NARCIS (Netherlands)

    Allmendinger, Fabian; Blümler, Peter; Doll, Michael; Grasdijk, Oliver; Heil, Werner; Jungmann, Klaus; Karpuk, Sergej; Krause, Hans-Joachim; Offenhäuser, Andreas; Repetto, Maricel; Schmidt, Ulrich; Sobolev, Yuri; Tullney, Kathlyne; Willmann, Lorenz; Zimmer, Stefan

    2017-01-01

    We report on precise measurements of magnetic field gradients extracted from transverse relaxation rates of precessing spin samples. The experimental approach is based on the free precession of gaseous, nuclear spin polarized He-3 and (12)9Xe atoms in a spherical cell inside a magnetic guiding field

  8. Measuring Soil Water Potential for Water Management in Agriculture: A Review

    Directory of Open Access Journals (Sweden)

    Marco Bittelli

    2010-05-01

    Full Text Available Soil water potential is a soil property affecting a large variety of bio-physical processes, such as seed germination, plant growth and plant nutrition. Gradients in soil water potential are the driving forces of water movement, affecting water infiltration, redistribution, percolation, evaporation and plants’ transpiration. The total soil water potential is given by the sum of gravity, matric, osmotic and hydrostatic potential. The quantification of the soil water potential is necessary for a variety of applications both in agricultural and horticultural systems such as optimization of irrigation volumes and fertilization. In recent decades, a large number of experimental methods have been developed to measure the soil water potential, and a large body of knowledge is now available on theory and applications. In this review, the main techniques used to measure the soil water potential are discussed. Subsequently, some examples are provided where the measurement of soil water potential is utilized for a sustainable use of water resources in agriculture.

  9. Wettability Studies Using Zeta Potential Measurements

    Directory of Open Access Journals (Sweden)

    Ghada Bassioni

    2015-01-01

    Full Text Available Wettability studies have been carried out on reservoir rocks using different techniques such as the Amott-Harvey method, the USBM method, and the contact angle method, all with limitations. In this study, the wettability is studied by discussing the surface charge using zeta potential measurements. The study relies on the finding that carbonated reservoir rocks, consisting of CaCO3 mainly, are positively charged and their surface has the potential to adsorb significant quantities of anions. Moreover, heavy fractions such as asphaltenes are reported to remain afloat depending on dispersive forces present in the oil and its various fractions. Experiments are carried out on aqueous limestone suspension with the addition of crude oil. The experiment is repeated with the use of polymeric inhibitors, A and B. The zeta potential is found to alter depending on the sequence of polymeric inhibitor in oil/water addition. The inhibitor is found to adsorb on the limestone surface, with a net negative charge, causing repulsion between crude oil and the inhibitor and, hence, preventing the deposition of heavy fractions and particularly asphaltenes. This study gives a comprehensive insight on the mechanism of polymeric inhibitor interaction with the surface and the effect of wettability on its performance.

  10. Assessment of plasma impedance probe for measuring electron density and collision frequency in a plasma with spatial and temporal gradients

    International Nuclear Information System (INIS)

    Hopkins, Mark A.; King, Lyon B.

    2014-01-01

    Numerical simulations and experimental measurements were combined to determine the ability of a plasma impedance probe (PIP) to measure plasma density and electron collision frequency in a plasma containing spatial gradients as well as time-varying oscillations in the plasma density. A PIP is sensitive to collision frequency through the width of the parallel resonance in the Re[Z]-vs.-frequency characteristic, while also being sensitive to electron density through the zero-crossing of the Im[Z]-vs.-frequency characteristic at parallel resonance. Simulations of the probe characteristic in a linear plasma gradient indicated that the broadening of Re[Z] due to the spatial gradient obscured the broadening due to electron collision frequency, preventing a quantitative measurement of the absolute collision frequency for gradients considered in this study. Simulation results also showed that the PIP is sensitive to relative changes in electron collision frequency in a spatial density gradient, but a second broadening effect due to time-varying oscillations made collision frequency measurements impossible. The time-varying oscillations had the effect of causing multiple zero-crossings in Im[Z] at parallel resonance. Results of experiments and simulations indicated that the lowest-frequency zero-crossing represented the lowest plasma density in the oscillations and the highest-frequency zero-crossing represented the highest plasma density in the oscillations, thus the PIP probe was found to be an effective tool to measure both the average plasma density as well as the maximum and minimum densities due to temporal oscillations

  11. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...... tensor elements. Furthermore, in current free regions the magnetic gradient tensor becomes symmetric, further reducing the number of independent elements to five. In that case B is a Laplacian potential field and the gradient tensor can be expressed in series of spherical harmonics. We present properties...... of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination...

  12. Regional applicability and potential of salt-gradient solar ponds in the United States. Volume 2: Detailed report

    Science.gov (United States)

    Lin, E. I. H.

    1982-03-01

    A comprehensive assessment of the regional applicability and potential of salt-gradient solar ponds in the United States is provided. The assessment is focused on the general characteristics of twelve defined geographic regions. Natural resources essential to solar ponds are surveyed. Meteorological and hydrogeological conditions affecting pond performance are examined. Potentially favorable pond sites are identified. Regional thermal and electrical energy output from solar ponds is calculated. Selected pond design cases are studied. Five major potential market sectors are evaluated in terms of technical and energy-consumption characteristics, and solar-pond applicability and potential. Relevant pond system data and financial factors are analyzed. Solar-pond energy costs are compared with conventional energy costs. The assessment concludes that, excepting Alaska, ponds are applicable in all regions for at least two market sectors. Total solar pond energy supply potential in the five market sectors examined is estimated to be 8.94 quads/yr by the year 2000, approximately 7.2% of the projected total national energy demand.

  13. Broth and agar hop-gradient plates used to evaluate the beer-spoilage potential of Lactobacillus and Pediococcus isolates.

    Science.gov (United States)

    Haakensen, M; Schubert, A; Ziola, B

    2009-03-15

    Identification of the beer-spoilage Lactobacillus and Pediococcus bacteria has largely taken two approaches; identification of spoilage-associated genes or identification of specific species of bacteria regardless of ability to grow in beer. The problem with these two approaches is that they are either overly inclusive (i.e., detect all bacteria of a given species regardless of spoilage potential) or overly selective (i.e., rely upon individual, putative spoilage-associated genes). Our goal was to design a method to assess the ability of Lactobacillus and Pediococcus to spoil beer that is independent of speciation or genetic background. In searching for a method by which to differentiate between beer-spoilage bacteria and bacteria that cannot grow in beer, we explored the ability of lactobacilli and pediococci isolates to grow in the presence of varying concentrations of hop-compounds and ethanol in broth medium versus on agar medium. The best method for differentiating between bacteria that can grow in beer and bacteria that do not pose a threat as beer-spoilage organisms was found to be a hop-gradient agar plate containing ethanol. This hop-gradient agar plate technique provides a rapid and simple solution to the dilemma of assessing the ability of Lactobacillus and Pediococcus isolates to grow in beer, and provides new insights into the different strategies used by these bacteria to survive under the stringent conditions of beer.

  14. Temperature gradient measurements by using thermoelectric effect in CNTs-silicone adhesive composite.

    Directory of Open Access Journals (Sweden)

    Muhammad Tariq Saeed Chani

    Full Text Available This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT and silicone adhesive. The composite contains CNT and silicon adhesive 1∶1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results.

  15. Finite Element Analysis of Multilayered and Functionally Gradient Tribological Coatings With Measured Material Properties (Preprint)

    Science.gov (United States)

    2006-11-01

    gradient coatings with diamond like carbon (DLC) coating on 440C stainless steel substrate were assumed as a series of perfectly bonded layers with...resistance and low friction. Ti1-xCx (0≤ x ≤1) gradient coatings with diamond like carbon (DLC) coating on 440C stainless steel substrate were...indenter tip was used for the FEA model. Each coating sample consists of 1 μm thick coating and 440C stainless steel substrate. The area function for

  16. Direct Measurements of Oxygen Gradients in Spheroid Culture System Using Electron Parametric Resonance Oximetry.

    Directory of Open Access Journals (Sweden)

    Laura M Langan

    Full Text Available Advanced in vitro culture from tissues of different origin includes three-dimensional (3D organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells using Electron Paramagnetic Resonance (EPR oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (∼2,500 cells/spheroid and absolute size (118±32 μm allow control of factors such as pre-existing stresses (e.g. ∼ 2% normoxic/hypoxic interface for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid cultures in biomedical and

  17. Ultrasonic measurement of through-thickness stress gradients in textured sheet metals

    International Nuclear Information System (INIS)

    Man Chising; Li Jianbo; Fan Xingyan; Lu Weiyang

    2000-01-01

    The objective of this investigation is to explore the possibility of using the dispersion of high-frequency Rayleigh waves for the evaluation of through-thickness stress gradients at the surface of metal sheets. We consider an orthorhombic sheet of cubic metal with through-thickness inhomogeneities in stress and texture, and adopt a coordinate system under which the rolling (RD), transverse (TD), and normal direction (ND) of the sheet are taken as the 1-, 2-, and 3-direction, respectively. We restrict our attention to the special case where only the stress components T 11 (x 3 ) and T 22 (x 3 ) in the sheet are nonzero, and consider only Rayleigh waves of sufficiently high frequency for which the sheet can be taken as the half-space x 3 ≥0. For Rayleigh waves of two different frequencies (with wave numbers k 1 and k k 2 respectively) propagating on the same wave path along either RD or TD, we appeal to an analysis of J. Li and Man to obtain a high-frequency asymptotic formula which gives the relative change in time-of-flight Δt/t 0 as (1/k 1 -1/k 2 ) times a linear combination of the derivatives T 11 ' (0), T 22 ' (0), W 4m0 ' (0)(m=0,2,4) and W 6m0 (0)(m=0,2,4,6) at the surface are ascertained and the material constants in the acoustoelastic consitutive equation of this polycrystal are known. An experiment was performed on an AA7075-T651 aluminum alloy beam, in which Δt/t 0 was measured for various values of T 11 (0) and T 11 ' (0) produced by beam bending (with (T 22 ≡0). The relevant texture coefficients of the beam were measured by X-ray diffraction. To obtain specific predictions from the aforementioned symptotic formula, we replace the material constants of the sample by their counterparts predicted for polycrystalline (pure) aluminum by the Man-Paroni model. The predictions and Δt/t 0 are then compared with the experimental results

  18. Block-conjugate-gradient method

    International Nuclear Information System (INIS)

    McCarthy, J.F.

    1989-01-01

    It is shown that by using the block-conjugate-gradient method several, say s, columns of the inverse Kogut-Susskind fermion matrix can be found simultaneously, in less time than it would take to run the standard conjugate-gradient algorithm s times. The method improves in efficiency relative to the standard conjugate-gradient algorithm as the fermion mass is decreased and as the value of the coupling is pushed to its limit before the finite-size effects become important. Thus it is potentially useful for measuring propagators in large lattice-gauge-theory calculations of the particle spectrum

  19. Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements.

    Science.gov (United States)

    Shlyonsky, Vadim

    2013-12-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and n-decane. The electrical resistance and potential difference across these membranes can be easily measured using a low-cost volt-ohm meter and home-made Ag/AgCl electrodes. The advantage of the model is the lack of ionic selectivity of the membrane, which can be modified by the introduction of different ionophores to the organic liquid mixture. A membrane treated with the mixture containing valinomycin generates voltages from -53 to -25 mV in the presence of a 10-fold KCl gradient (in to out) and from -79 to -53 mV in the presence of a bi-ionic KCl/NaCl gradient (in to out). This latter bi-ionic gradient potential reverses to a value from +9 to +20 mV when monensin is present in the organic liquid mixture. Thus, the model can be build stepwise, i.e., all factors leading to the development of diffusion potentials can be introduced sequentially, helping students to understand the quantitative relationships of ionic gradients and differential membrane permeability in the generation of cell electrical signals.

  20. Optimized phase gradient measurements and phase-amplitude interplay in optical coherence elastography

    Science.gov (United States)

    Zaitsev, Vladimir Y.; Matveyev, Alexander L.; Matveev, Lev A.; Gelikonov, Grigory V.; Sovetsky, Aleksandr A.; Vitkin, Alex

    2016-11-01

    In compressional optical coherence elastography, phase-variation gradients are used for estimating quasistatic strains created in tissue. Using reference and deformed optical coherence tomography (OCT) scans, one typically compares phases from pixels with the same coordinates in both scans. Usually, this limits the allowable strains to fairly small values advantages of the proposed optimized phase-variation methodology.

  1. Xenognosin methylation is critical in defining the chemical potential gradient that regulates the potential distribution in Striga pathogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Fate, G.D.; Lynn, D.G. [Univ. of Chicago, IL (United States)

    1996-11-20

    Striga asiatica (Scrophulariaceae) is a parasitic plant requiring a host-derived signal, xenognosin, to initiate a cascade of events necessary for the establishment of host contact. By attempting to model the distribution of the xenognosin around the host, the activity of the signal is shown to be strongly dependent on the presence of another component in the host exudate. Surprisingly this component, characterized as 4,6-dimethoxy-2-[(8`Z.11`Z)-8`,11`, -14`-pentadecatriene]resorcinol, is structurally related and shares the same biosynthetic pathway as the xenognosin. This compound is shown to function as an antioxidant and its ability to enhance the activity of the xenognosin is consistent with its ability to extend its lifetime in the exudate. This endogenous antioxidant activity is required to explain the spatial sensing in the establishment of the host-parasite interface and its characterization provides insight into how chemical potential may be regulated within and around plant tissues. 23 refs., 7 figs., 1 tab.

  2. Experimental measurements of thermoelectric and electrochemical potentials in sandstones saturated with NaCl electrolyte

    Science.gov (United States)

    Leinov, E.; Jackson, M.

    2013-12-01

    Measurements of the self-potential (SP) have been used to characterize subsurface flow in numerous settings, including volcanoes, earthquake zones, and geothermal fields. Thermoelectric (TE) and electrochemical (EC) potentials contribute to the measured SP if gradients in temperature and/or concentration are present, yet few experimental measurements of EC and TE potentials in natural porous media have been reported. Each is the sum of a diffusion and exclusion potential: the former arises when ions of contrasting mobility migrate at different rates down a temperature or concentration gradient; the latter arises when there is a temperature or concentration gradient across an electrically charged porous medium in which co-ions of the same polarity have been excluded from the pore-space. Here we report measurements of the SP arising from temperature or concentration gradients across clean (clay-free) sandstone samples saturated with NaCl electrolyte over the salinity range 5x10-5 to 1M. Electrical potentials are measured using non-polarizing Ag/AgCl electrodes, and temperature or salinity gradients are induced by placing the saturated samples in contact with electrolyte reservoirs of contrasting temperature or concentration. Our experimental methodology accounts for the temperature- and concentration-dependent electrode response. We find that the TE potential responds linearly to the applied temperature difference, allowing a TE potential coupling coefficient to be determined; the value of this decreases as the electrolyte concentration increases, from +0.056mV/K at 10-4 M to -0.126mV/K at 1M. The EC potential increases as the concentration ratio increases, from a minimum of 1.8mV at a salinity ratio of 1.13, to a maximum of 24.8mV at salinity ratio of 102, before decreasing to 19.5mV at salinity ratio of 103. In both cases, at high values of concentration (>0.01M) the measured potential is diffusion dominated, while at lower concentration the exclusion potential is

  3. Measurements of the ripple effect and geometric distribution of switched gradient fields inside a magnetic resonance scanner.

    Science.gov (United States)

    Sundström, Henrik; Mild, Kjell Hansson; Wilén, Jonna

    2015-02-01

    Knowledge of patient exposure during magnetic resonance imaging (MRI) procedures is limited, and the need for such knowledge has been demonstrated in recent in vitro and in vivo studies of the genotoxic effects of MRI. This study focuses on the dB/dt of the switched gradient field (SGF) and its geometric distribution. These values were characterized by measuring the peak dB/dt generated by a programmed gradient current of alternating triangles inside a 1.5T MR scanner. The maximum dB/dt exposure to the gradient field was 6-14 T/s, and this occurred at the edges of the field of view (FOV) 20-25 cm from the isocenter in the longitudinal direction. The dB/dt exposure dropped off to roughly half the maximum (3-7 T/s) at the edge of the bore. It was found that the dB/dt of the SGF was distorted by a 200 kHz ripple arising from the amplifier. The ripple is small in terms of B-field, but the high frequency content contributes to a peak dB/dt up to 18 times larger than that predicted by the slew rate (4 T/s m) and the distance from the isocenter. Measurements on a 3 T MRI scanner, however, revealed a much smaller filtered ripple of 100 kHz in dB/dt. These findings suggest that the gradient current to each coil together with information on the geometrical distribution of the gradient field and ripple effects could be used to assess the SGF exposure within an MRI bore. © 2014 Wiley Periodicals, Inc.

  4. Energetic Neutral Atom (ENA) intensity gradients in the heliotail during year 2003, using Cassini/INCA measurements

    International Nuclear Information System (INIS)

    Dialynas, K; Krimigis, S M; Mitchell, D G; Roelof, E C

    2015-01-01

    In the present study we use all-sky energy-resolved (5-55 keV) energetic neutral atom (ENA) maps obtained by the Ion and Neutral CAmera (INCA) on board Cassini during the time period DOY 265/2003 to 268/2003, to investigate the properties of the peak-to-basin ENA emissions in the direction of the heliotail. Our conclusions can be summarized as follows: (1) a relatively smooth boundary (called t ransition region ) between the very low (basin) and high (tail) ENA emissions from the heliosheath, with a spatial width of ∼30° deg in ecl. longitude, that no theory had predicted to date, is identified in the energy range of 5-55 keV; (2) the ENA intensity gradient in this transition region is almost invariant as a function of both ecl. Latitude and energy, with an average value of ∼2.4% per degree; (3) the deduced partial plasma pressure distributions in the 5-55 keV energy range are consistent with the ENA intensity distributions in the same energy range, while the ENA intensity gradient translates to a corresponding partial pressure gradient that occurs in the transition region; and (4) this partial pressure gradient is possibly not consistent with a tail magnetic field configuration that is similar to the measured magnetic fields by the Voyagers in the nose hemisphere

  5. Dynamic microscale temperature gradient in a gold nanorod solution measured by diffraction-limited nanothermometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chengmingyue; Gan, Xiaosong; Li, Xiangping; Gu, Min, E-mail: mgu@swin.edu.au [Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

    2015-09-21

    We quantify the dynamic microscale temperature gradient in a gold nanorod solution using quantum-dot-based microscopic fluorescence nanothermometry. By incorporating CdSe quantum dots into the solution as a nanothermometer, precise temperature mapping with diffraction-limited spatial resolution and sub-degree temperature resolution is achieved. The acquired data on heat generation and dissipation show an excellent agreement with theoretical simulations. This work reveals an effective approach for noninvasive temperature regulation with localized nanoheaters in microfluidic environment.

  6. Peptide self-association in aqueous trifluoroethanol monitored by pulsed field gradient NMR diffusion measurements

    Energy Technology Data Exchange (ETDEWEB)

    Yao Shenggen [Biomolecular Research Institute (Australia); Howlett, Geoffrey J. [University of Melbourne, Department of Biochemistry and Molecular Biology (Australia); Norton, Raymond S. [Biomolecular Research Institute (Australia)

    2000-02-15

    Defining the self-association state of a molecule in solution can be an important step in NMR-based structure determination. This is particularly true of peptides, where there can be a relatively small number of long-range interactions and misinterpretation of an intermolecular NOE as an intramolecular contact can have a dramatic influence on the final calculated structure. In this paper, we have investigated the use of translational self-diffusion coefficient measurements to detect self-association in aqueous trifluoroethanol of three peptides which are analogues of the C-terminal region of human neuropeptide Y. Experimentally measured diffusion coefficients were extrapolated to D{sup 0}, the limiting value as the peptide concentration approaches zero, and then converted to D{sub 20,w}, the diffusion coefficient after correction for temperature and the viscosity of the solvent. A decrease in D{sub 20,w} of about 16% was found for all three peptides in aqueous TFE (30% by volume) compared with water, which is in reasonable agreement with the expected decrease upon dimerisation, the presence of which was indicated by sedimentation equilibrium measurements. Apparent molecular masses of these peptides in both solutions were also calculated from their diffusion coefficients and similar results were obtained. Several potential internal standards, including acetone, acetonitrile, dimethylsulfoxide and dioxane, were assessed as monitors of solution viscosity over a range of trifluoroethanol concentrations. Compared with independent measurements of viscosity, acetonitrile was the most accurate standard among these four. The practical limitations of a quantitative assessment of peptide self-association from translational diffusion coefficients measured by PFGNMR, including the calculation of apparent molecular mass, are also discussed.

  7. Extensive phenotypic plasticity of a Red Sea coral over a strong latitudinal temperature gradient suggests limited acclimatization potential to warming

    KAUST Repository

    Sawall, Yvonne

    2015-03-10

    Global warming was reported to cause growth reductions in tropical shallow water corals in both, cooler and warmer, regions of the coral species range. This suggests regional adaptation with less heat-tolerant populations in cooler and more thermo-tolerant populations in warmer regions. Here, we investigated seasonal changes in the in situ metabolic performance of the widely distributed hermatypic coral Pocillopora verrucosa along 12° latitudes featuring a steep temperature gradient between the northern (28.5°N, 21-27°C) and southern (16.5°N, 28-33°C) reaches of the Red Sea. Surprisingly, we found little indication for regional adaptation, but strong indications for high phenotypic plasticity: Calcification rates in two seasons (winter, summer) were found to be highest at 28-29°C throughout all populations independent of their geographic location. Mucus release increased with temperature and nutrient supply, both being highest in the south. Genetic characterization of the coral host revealed low inter-regional variation and differences in the Symbiodinium clade composition only at the most northern and most southern region. This suggests variable acclimatization potential to ocean warming of coral populations across the Red Sea: high acclimatization potential in northern populations, but limited ability to cope with ocean warming in southern populations already existing at the upper thermal margin for corals.

  8. Extensive phenotypic plasticity of a Red Sea coral over a strong latitudinal temperature gradient suggests limited acclimatization potential to warming

    KAUST Repository

    Sawall, Yvonne; Al-Sofyani, Abdulmoshin; Hohn, Sö nke; Banguera Hinestroza, Eulalia; Voolstra, Christian R.; Wahl, Martin

    2015-01-01

    Global warming was reported to cause growth reductions in tropical shallow water corals in both, cooler and warmer, regions of the coral species range. This suggests regional adaptation with less heat-tolerant populations in cooler and more thermo-tolerant populations in warmer regions. Here, we investigated seasonal changes in the in situ metabolic performance of the widely distributed hermatypic coral Pocillopora verrucosa along 12° latitudes featuring a steep temperature gradient between the northern (28.5°N, 21-27°C) and southern (16.5°N, 28-33°C) reaches of the Red Sea. Surprisingly, we found little indication for regional adaptation, but strong indications for high phenotypic plasticity: Calcification rates in two seasons (winter, summer) were found to be highest at 28-29°C throughout all populations independent of their geographic location. Mucus release increased with temperature and nutrient supply, both being highest in the south. Genetic characterization of the coral host revealed low inter-regional variation and differences in the Symbiodinium clade composition only at the most northern and most southern region. This suggests variable acclimatization potential to ocean warming of coral populations across the Red Sea: high acclimatization potential in northern populations, but limited ability to cope with ocean warming in southern populations already existing at the upper thermal margin for corals.

  9. A preliminary investigation into the measurement of global thunderstorm incidence and electrosphere potential at Sanae, Antarctica

    International Nuclear Information System (INIS)

    Smart, C.A.

    1980-01-01

    One of the atmospheric parameters that may be affected by variations in the electrosphere potential is thunderstorm activity. The author made preliminary investigations into the simultaneous monitoring of global thunderstorm incidence and electrosphere potential. The author looked at the structure of the sun and the earth solar activity and solar emissions as well as the sun-weather relationships. Measurement were made by the author during 1978 at Sanae, Antarctica. The objective was to investigate the fluctuations of global thunderstorm activity and electrosphere potential and to establish some link between these and with solar activity. Potential gradient of the lower atmosphere was measured by means of a field mill and fluctuations taken to be representative of those of the electrosphere potential. Thunderstorm incidence was monitored by measurement of extra low frequency (ELF) electromagnetic noise radiated by lightning. A dipole or loop antenna was used for the recording of extra low frequency electromagnetic noise. A computer program was developed to facilitate the data analysis

  10. Measurement of electric potential distribution in dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Veretel' nik, V I; Dergozubov, K A; Evdokimov, O B; Shevelev, G E [Tomskij Politekhnicheskij Inst. (USSR). Nauchno-Issledovatel' skij Inst. Ehlektronnoj Introskopii

    1976-05-01

    A radiation method of potential probing in a substance is described. The method is based upon the influence of the electric field upon the emission of secondary electrons expelled by ..gamma..-irradiation from the studied sample.

  11. Thermoelectric potential in UO2 and (U,Pu)O2 and its influence on oxygen migration in presence of a temperature gradient

    International Nuclear Information System (INIS)

    D'Annucci, F.

    1979-09-01

    Measurement of the thermoelectric power have been carried out in sintered pellets of uranium-oxide and uranium-plutonium mixed oxides up to 1800 K. For the thermal treatment an inducting furnace is used. The temperatures and the thermoelectric potential are measured with two thermocouples wich are contained in two holes in the lower end of the pellet. During the experiments a temperature difference of 80 K is maintained between the two measuring points. The Seebeck coefficients are calculated from the EMF measurements as a function of temperature and of the O/M ratio. The results show that these oxides have the typical electric properties of a classic semiconductor. The conductivity is of p-type up to a defined temperature wich is a function of the stoichiometry. The Seebeck coefficients are characterized by a defined energy of activation wich is independent from the stochiometry in the regions of hypo- and hyperstochiometric oxides. The thermoelectric forces and the lattice forces drive ions along the temperature gradients. Both forces can be described by the heat of transport of oxygen ions wich contains a thermoelectric and a thermal part. The thermoelectric part of the heat of transport is calculated with the values of the Seebeck coefficients and the contribution to the total heat of transport is discussed. (orig.) [de

  12. Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in Southwestern Saudi Arabian Dune Sand

    KAUST Repository

    Mughal, Iqra

    2013-05-01

    In arid lands, a major contribution to water loss is by soil water evaporation. Desert sand dunes in arid regions are devoid of runoff and have high rates of infiltration. Rainwater is commonly stored within them because of the low permeability soils in the underlying desert pavement. In such cases, moisture is confined in the sand dune below a depth, termed as the “extinction depth”, where it is protected from evaporation during long dry periods. Moreover, desert sand dunes have sparse vegetation, which results in low transpiration losses from the stored water. The water accumulated below the extinction depth of the sand dunes can be utilized for various purposes such as in irrigation to support desert agriculture. In this study, field experiments were conducted in Western Saudi Arabia to monitor the soil moisture gradients and determine the diffusive extinction depth of dune sand. The dune sand was saturated with water and was exposed to natural conditions (evaporation and precipitation). The decline of the water level in the sand column was continuously recorded using transducers and sensors installed at different depths monitored the temporal variation of temperature and moisture content within the sand. The hydrological simulator HYDRUS-1D was used to construct the vertical profiles of soil water content and temperature and the results obtained from HYDRUS-1D were compared to the gradients monitored by the sensors.

  13. Dead wood biomass and turnover time, measured by radiocarbon, along a subalpine elevation gradient.

    Science.gov (United States)

    Kueppers, Lara M; Southon, John; Baer, Paul; Harte, John

    2004-12-01

    Dead wood biomass can be a substantial fraction of stored carbon in forest ecosystems, and coarse woody debris (CWD) decay rates may be sensitive to climate warming. We used an elevation gradient in Colorado Rocky Mountain subalpine forest to examine climate and species effects on dead wood biomass, and on CWD decay rate. Using a new radiocarbon approach, we determined that the turnover time of lodgepole pine CWD (340+/-130 years) was roughly half as long in a site with 2.5-3 degrees C warmer air temperature, as that of pine (630+/-400 years) or Engelmann spruce CWD (800+/-960 and 650+/-410 years) in cooler sites. Across all sites and both species, CWD age ranged from 2 to 600 years, and turnover time was 580+/-180 years. Total standing and fallen dead wood biomass ranged from 4.7+/-0.2 to 54+/-1 Mg ha(-1), and from 2.8 to 60% of aboveground live tree biomass. Dead wood biomass increased 75 kg ha(-1) per meter gain in elevation and decreased 13 Mg ha(-1) for every degree C increase in mean air temperature. Differences in biomass and decay rates along the elevation gradient suggest that climate warming will lead to a loss of dead wood carbon from subalpine forest.

  14. Emotioncy: A Potential Measure of Readability

    Science.gov (United States)

    Pishghadamn, Reza; Abbasnejad, Hannaheh

    2016-01-01

    Given the deficiencies of readability formulae as reliable tools for measuring text readability in educational settings, this study aims to offer a new measure to improve the current methods of testing the readability levels of texts through the incorporation of the newly-developed concept of emotioncy. To this end, a group of 221 students were…

  15. Yukawa Potential, Panharmonic Measure and Brownian Motion

    Directory of Open Access Journals (Sweden)

    Antti Rasila

    2018-05-01

    Full Text Available This paper continues our earlier investigation, where a walk-on-spheres (WOS algorithm for Monte Carlo simulation of the solutions of the Yukawa and the Helmholtz partial differential equations (PDEs was developed by using the Duffin correspondence. In this paper, we investigate the foundations behind the algorithm for the case of the Yukawa PDE. We study the panharmonic measure, which is a generalization of the harmonic measure for the Yukawa PDE. We show that there are natural stochastic definitions for the panharmonic measure in terms of the Brownian motion and that the harmonic and the panharmonic measures are all mutually equivalent. Furthermore, we calculate their Radon–Nikodym derivatives explicitly for some balls, which is a key result behind the WOS algorithm.

  16. Status and first measurement results for a high gradient CH-cavity

    Energy Technology Data Exchange (ETDEWEB)

    Almomani, Ali; Ratzinger, Ulrich [Institut fuer Angewandte Physik, Frankfurt Universitaet, Frankfurt am Main (Germany)

    2016-07-01

    This pulsed linac activity aims on compact designs and on a considerable increase of the voltage gain per meter. A high gradient CH {sup *} cavity operated at 325 MHz was developed at IAP {sup *} Frankfurt. The mean effective accelerating field for this cavity is expected well above 10 MV/m at β=0.164. This cavity is developed within a funded project. The results might influence the rebuilt of the UNILAC {sup *} Alvarez section, aiming to achieve the beam intensities specified for the GSI {sup *} FAIR project (15 mA U28+). Another motivation is the development of an efficient pulsed ion accelerator for significantly higher energies like 60 AMeV. The new GSI 3 MW Thales klystron test stand will be used for the cavity RF power tests. Detailed studies on two different types of copper plating will be performed with this cavity.

  17. A novel method for the in situ determination of concentration gradients in the electrolyte of Li-ion Batteries

    NARCIS (Netherlands)

    Zhou, J.; Danilov, D.; Notten, P.H.L.

    2006-01-01

    An electrochemical method has been developed for the in situ determination of concentration gradients in the electrolyte of sealed Li-ion batteries by measuring the potential difference between microreference electrodes. Formulas relating the concentration gradient and the potential difference

  18. Influence of accommodative lag upon the far-gradient measurement of accommodative convergence to accommodation ratio in strabismic patients.

    Science.gov (United States)

    Miyata, Manabu; Hasebe, Satoshi; Ohtsuki, Hiroshi

    2006-01-01

    To determine the influence of the lag of accommodation (LOA) on the accommodative convergence to accommodation (AC/A) ratio measured by the far-gradient method in strabismic patients. The AC/A ratio was measured with a distance target viewed with and without -3.00 diopter (D) addition lenses in 63 patients with different types of strabismus (age range, 7-34 years; range of strabismic angle, -60 to +40 prism diopters; refractive error range, -7.33 to +6.63 D). The LOA for the same lens was measured with an open-view-type autorefractometer. The stimulus AC/A ratio and the AC/A ratio adjusted by the individually measured LOA (adjusted AC/A ratio) were compared. The mean +/- SD of the LOA to the -3.00 D lenses was 1.06 +/- 0.43 D. The mean adjusted AC/A ratio was 41% greater than the stimulus AC/A ratio. The LOA differed widely among patients (0.13 to 2.14 D), and a large LOA tended to appear in myopic or young patients. The AC/A ratio obtained using the conventional far-gradient method is significantly biased by the LOA, and thus does not always represent the actual relationship between accommodation and vergence control systems. Copyright Japanese Ophthalmological Society 2006.

  19. Measuring Officer Potential Using the OER

    Science.gov (United States)

    2015-06-12

    States Army War College Press. Creswell , John . 2013. Qualitative Inquiry and Research Design : Choosing Among Five Approaches, 3rd ed. Los Angeles, CA...significance of this research study. In early 2014, the Army adopted a new officer evaluation report distinctly designed to capture the performance and...can inspire a person to reach her potential. — John C. Maxwell Purpose The purpose of this literature review is to answer the primary research

  20. Potential transportation demand management programs and measures

    Energy Technology Data Exchange (ETDEWEB)

    Litman, T. [Victoria Transport Policy Institute, Victoria, BC (Canada)

    1997-02-07

    The advantages of transportation demand management (TDM) programs were discussed. TDM includes several policies, programs and measures designed to change travel patterns. TDM programs include commute trip reductions, pricing policies, land use management strategies, and programs to support alternative modes of transportation such as public transit, carpooling, bicycling, walking and telecommuting. TDM programs are designed to reduce traffic congestion and air pollution. Some other TDM programs and measures include: enabling programs, alternative mode encouragement, driving disincentives, parking programs, marginalizing user costs, reducing automobile ownership, and land use management.

  1. ATLAS Potential for Beauty Physics Measurements

    International Nuclear Information System (INIS)

    Smizanska, M.

    2001-01-01

    The main focus of ATLAS b physics has traditionally been on the standard model. In the last few years also the aspects of new physics in B-decays has been addressed. Another new field of studies started recently is a beauty production. We give an overview of the older as well as more recent results. After an introduction outlining selected trigger and detector performance characteristics, we explain methods and goals of CP violation measurements in decay channels of B d 0 meson, physics of B s 0 system and of rare decays. Finally, the ATLAS program for beauty production measurements is presented. (author)

  2. In-situ measurement of magnetic field gradient in a magnetic shield by a spin-exchange relaxation-free magnetometer

    International Nuclear Information System (INIS)

    Fang Jian-Cheng; Wang Tao; Li Yang; Cai Hong-Wei; Zhang Hong

    2015-01-01

    A method of measuring in-situ magnetic field gradient is proposed in this paper. The magnetic shield is widely used in the atomic magnetometer. However, there is magnetic field gradient in the magnetic shield, which would lead to additional gradient broadening. It is impossible to use an ex-situ magnetometer to measure magnetic field gradient in the region of a cell, whose length of side is several centimeters. The method demonstrated in this paper can realize the in-situ measurement of the magnetic field gradient inside the cell, which is significant for the spin relaxation study. The magnetic field gradients along the longitudinal axis of the magnetic shield are measured by a spin-exchange relaxation-free (SERF) magnetometer by adding a magnetic field modulation in the probe beam’s direction. The transmissivity of the cell for the probe beam is always inhomogeneous along the pump beam direction, and the method proposed in this paper is independent of the intensity of the probe beam, which means that the method is independent of the cell’s transmissivity. This feature makes the method more practical experimentally. Moreover, the AC-Stark shift can seriously degrade and affect the precision of the magnetic field gradient measurement. The AC-Stark shift is suppressed by locking the pump beam to the resonance of potassium’s D1 line. Furthermore, the residual magnetic fields are measured with σ + - and σ – -polarized pump beams, which can further suppress the effect of the AC-Stark shift. The method of measuring in-situ magnetic field gradient has achieved a magnetic field gradient precision of better than 30 pT/mm. (paper)

  3. Dry deposition of O_3 and SO_2 estimated from gradient measurements above a temperate mixed forest

    International Nuclear Information System (INIS)

    Wu, Zhiyong; Staebler, Ralf; Vet, Robert; Zhang, Leiming

    2016-01-01

    Vertical profiles of O_3 and SO_2 concentrations were monitored at the Borden Forest site in southern Ontario, Canada from May 2008 to April 2013. A modified gradient method (MGM) was applied to estimate O_3 and SO_2 dry deposition fluxes using concentration gradients between a level above and a level below the canopy top. The calculated five-year mean (median) dry deposition velocity (V_d) were 0.35 (0.27) and 0.59 (0.54) cm s"−"1, respectively, for O_3 and SO_2. V_d(O_3) exhibited large seasonal variations with the highest monthly mean of 0.68 cm s"−"1 in August and the lowest of 0.09 cm s"−"1 in February. In contrast, seasonal variations of V_d(SO_2) were smaller with monthly means ranging from 0.48 (May) to 0.81 cm s"−"1 (December). The different seasonal variations between O_3 and SO_2 were caused by the enhanced SO_2 uptake by snow surfaces in winter. Diurnal variations showed a peak value of V_d in early morning in summer months for both O_3 and SO_2. Canopy wetness increased the non-stomatal uptake of O_3 while decreasing the stomatal uptake. This also applied to SO_2, but additional factors such as surface acidity also played an important role on the overall uptake. - Highlights: • Application of a modified gradient-method for quantifying dry deposition is demonstrated. • A five-year dry deposition database is developed for O_3 and SO_2 over a mixed forest. • Canopy wetness enhances non-stomatal O_3 uptake while inhibits stomatal uptake. • High surface acidity reduces SO_2 dry deposition. - Capsule: A five-year dataset of O_3 and SO_2 dry deposition velocities was generated from concentration gradient measurement data using a modified gradient method.

  4. Gibbsian segregating alloys driven by thermal and concentration gradients: A potential grazing collector optics used in EUV lithography

    Science.gov (United States)

    Qiu, Huatan

    A critical issue for EUV lithography is the minimization of collector degradation from intense plasma erosion and debris deposition. Reflectivity and lifetime of the collector optics will be heavily dependent on surface chemistry interactions between fuels and various mirror materials, in addition to high-energy ion and neutral particle erosion effects. An innovative Gibbsian segregation (GS) concept has been developed for being a self-healing, erosion-resistant collector optics. A Mo-Au GS alloy is developed on silicon using a DC dual-magnetron co-sputtering system in order for enhanced surface roughness properties, erosion resistance, and self-healing characteristics to maintain reflectivity over a longer period of mirror lifetime. A thin Au segregating layer will be maintained through segregation during exposure, even though overall erosion is taking place. The reflective material, Mo, underneath the segregating layer will be protected by this sacrificial layer which is lost due to preferential sputtering. The two dominant driving forces, thermal (temperature) and surface concentration gradient (surface removal flux), are the focus of this work. Both theoretical and experimental efforts have been performed to prove the effectiveness of the GS alloy used as EUV collection optics, and to elucidate the underlying physics behind it. The segregation diffusion, surface balance, erosion, and in-situ reflectivity will be investigated both qualitatively and quantitatively. Results show strong enhancement effect of temperature on GS performance, while only a weak effect of surface removal rate on GS performance. When equilibrium between GS and erosion is reached, the surface smoothness could be self-healed and reflectivity could be maintained at an equilibrium level, instead of continuously dropping down to an unacceptable level as conventional optic mirrors behave. GS process also shows good erosion resistance. The effectiveness of GS alloy as EUV mirror is dependent on

  5. An FPGA Architecture for Extracting Real-Time Zernike Coefficients from Measured Phase Gradients

    Science.gov (United States)

    Moser, Steven; Lee, Peter; Podoleanu, Adrian

    2015-04-01

    Zernike modes are commonly used in adaptive optics systems to represent optical wavefronts. However, real-time calculation of Zernike modes is time consuming due to two factors: the large factorial components in the radial polynomials used to define them and the large inverse matrix calculation needed for the linear fit. This paper presents an efficient parallel method for calculating Zernike coefficients from phase gradients produced by a Shack-Hartman sensor and its real-time implementation using an FPGA by pre-calculation and storage of subsections of the large inverse matrix. The architecture exploits symmetries within the Zernike modes to achieve a significant reduction in memory requirements and a speed-up of 2.9 when compared to published results utilising a 2D-FFT method for a grid size of 8×8. Analysis of processor element internal word length requirements show that 24-bit precision in precalculated values of the Zernike mode partial derivatives ensures less than 0.5% error per Zernike coefficient and an overall error of RAM usage is <16% for Shack-Hartmann grid sizes up to 32×32.

  6. The effects of frequency-encoding gradient upon detectability of the margins and height measurements of normal adult pituitary glands

    International Nuclear Information System (INIS)

    Taketomi, A.; Sato, N.; Aoki, J.; Endo, K.

    2004-01-01

    We investigated the effects of frequency-encoding gradient (FEG) upon detectability and height measurements of the normal adult pituitary gland. We obtained two sets of T1-weighted sagittal images of the pituitary gland from 70 adult subjects without known pituitary dysfunction using 1.5 tesla imagers; one with an inferior-superior FEG, and one with an anterior-posterior FEG. We classified the subjects into three types according to the distribution of fatty marrow in the clivus. Each set of images was assessed for pituitary height on midline sagittal images, and detectability of pituitary margins. Height measurements and detectability scores were evaluated for significant difference between the two FEGs. In subjects with fatty marrow in the clivus, there was significant difference between pituitary height measurements (P<0.005) and pituitary margin detectability (P<0.001). Care should be taken to image the pituitary gland using an anterior-posterior FEG. (orig.)

  7. Gradient flux measurements of sea–air DMS transfer during the Surface Ocean Aerosol Production (SOAP experiment

    Directory of Open Access Journals (Sweden)

    M. J. Smith

    2018-04-01

    Full Text Available Direct measurements of marine dimethylsulfide (DMS fluxes are sparse, particularly in the Southern Ocean. The Surface Ocean Aerosol Production (SOAP voyage in February–March 2012 examined the distribution and flux of DMS in a biologically active frontal system in the southwest Pacific Ocean. Three distinct phytoplankton blooms were studied with oceanic DMS concentrations as high as 25 nmol L−1. Measurements of DMS fluxes were made using two independent methods: the eddy covariance (EC technique using atmospheric pressure chemical ionization–mass spectrometry (API-CIMS and the gradient flux (GF technique from an autonomous catamaran platform. Catamaran flux measurements are relatively unaffected by airflow distortion and are made close to the water surface, where gas gradients are largest. Flux measurements were complemented by near-surface hydrographic measurements to elucidate physical factors influencing DMS emission. Individual DMS fluxes derived by EC showed significant scatter and, at times, consistent departures from the Coupled Ocean–Atmosphere Response Experiment gas transfer algorithm (COAREG. A direct comparison between the two flux methods was carried out to separate instrumental effects from environmental effects and showed good agreement with a regression slope of 0.96 (r2 = 0.89. A period of abnormal downward atmospheric heat flux enhanced near-surface ocean stratification and reduced turbulent exchange, during which GF and EC transfer velocities showed good agreement but modelled COAREG values were significantly higher. The transfer velocity derived from near-surface ocean turbulence measurements on a spar buoy compared well with the COAREG model in general but showed less variation. This first direct comparison between EC and GF fluxes of DMS provides confidence in compilation of flux estimates from both techniques, as well as in the stable periods when the observations are not well predicted by the COAREG

  8. Gradient flux measurements of sea-air DMS transfer during the Surface Ocean Aerosol Production (SOAP) experiment

    Science.gov (United States)

    Smith, Murray J.; Walker, Carolyn F.; Bell, Thomas G.; Harvey, Mike J.; Saltzman, Eric S.; Law, Cliff S.

    2018-04-01

    Direct measurements of marine dimethylsulfide (DMS) fluxes are sparse, particularly in the Southern Ocean. The Surface Ocean Aerosol Production (SOAP) voyage in February-March 2012 examined the distribution and flux of DMS in a biologically active frontal system in the southwest Pacific Ocean. Three distinct phytoplankton blooms were studied with oceanic DMS concentrations as high as 25 nmol L-1. Measurements of DMS fluxes were made using two independent methods: the eddy covariance (EC) technique using atmospheric pressure chemical ionization-mass spectrometry (API-CIMS) and the gradient flux (GF) technique from an autonomous catamaran platform. Catamaran flux measurements are relatively unaffected by airflow distortion and are made close to the water surface, where gas gradients are largest. Flux measurements were complemented by near-surface hydrographic measurements to elucidate physical factors influencing DMS emission. Individual DMS fluxes derived by EC showed significant scatter and, at times, consistent departures from the Coupled Ocean-Atmosphere Response Experiment gas transfer algorithm (COAREG). A direct comparison between the two flux methods was carried out to separate instrumental effects from environmental effects and showed good agreement with a regression slope of 0.96 (r2 = 0.89). A period of abnormal downward atmospheric heat flux enhanced near-surface ocean stratification and reduced turbulent exchange, during which GF and EC transfer velocities showed good agreement but modelled COAREG values were significantly higher. The transfer velocity derived from near-surface ocean turbulence measurements on a spar buoy compared well with the COAREG model in general but showed less variation. This first direct comparison between EC and GF fluxes of DMS provides confidence in compilation of flux estimates from both techniques, as well as in the stable periods when the observations are not well predicted by the COAREG model.

  9. Calorimeter measures high nuclear heating rates and their gradients across a reactor test hole

    Science.gov (United States)

    Burwell, D.; Coombe, J. R.; Mc Bride, J.

    1970-01-01

    Pedestal-type calorimeter measures gamma-ray heating rates from 0.5 to 7.0 watts per gram of aluminum. Nuclear heating rate is a function of cylinder temperature change, measured by four chromel-alumel thermocouples attached to the calorimeter, and known thermoconductivity of the tested material.

  10. Minimal hepatic encephalopathy in patients with cirrhosis by measuring liver stiffness and hepatic venous pressure gradient.

    Science.gov (United States)

    Sharma, Praveen; Kumar, Ashish

    2012-01-01

    Transient elastography (TE) of liver and hepatic venous pressure gradient (HVPG) allows accurate prediction of cirrhosis and its complications in patients with chronic liver disease. There is no study on prediction of minimal hepatic encephalopathy (MHE) using TE and HVPG in patients with cirrhosis. Consecutive cirrhotic patients who never had an episode of hepatic encephalopathy (HE) were enrolled. All patients were assessed by psychometry (number connection test (NCT-A and B), digit symbol test (DST), serial dot test (SDT), line tracing test (LTT)), critical flicker frequency test (CFF), TE by FibroScan and HVPG. MHE was diagnosed if there were two or more abnormal psychometry tests (± 2 SD controls). 150 patients with cirrhosis who underwent HVPG were screened; 91 patients (61%, age 44.0 ± 11.4 years, M:F:75:16, Child's A:B:C 18:54:19) met the inclusion criteria. Fifty three (58%) patients had MHE (Child A (7/18, 39%), Child B (32/54, 59%) and Child C (14/19, 74%)). There was no significant difference between alanine aminotranferease (ALT), aspartate aminotransferase (AST) and total bilirubin level in patients with MHE versus non MHE. Patients with MHE had significantly lower CFF than non MHE patients (38.4 ± 3.0 vs. 40.2 ± 2.2 Hz, P = 0.002). TE and HVPG in patients with MHE did not significantly differ from patients with no MHE (30.9 ± 17.2 vs. 29.8 ± 18.2 KPas, P = 0.78; and 13.6 ± 2.7 vs. 13.6 ± 3.2 mmHg, P = 0.90, respectively).There was significant correlation of TE with Child's score (0.25, P = 0.01), MELD (0.40, P = 0.001) and HVPG (0.72, P = 0.001) while no correlation with psychometric tests, CFF and MHE. TE by FibroScan and HVPG cannot predict minimal hepatic encephalopathy in patients with cirrhosis.

  11. Measuring diffusion-relaxation correlation maps using non-uniform field gradients of single-sided NMR devices.

    Science.gov (United States)

    Nogueira d'Eurydice, Marcel; Galvosas, Petrik

    2014-11-01

    Single-sided NMR systems are becoming a relevant tool in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For a class of these devices, the configuration of the permanent magnets provides a linear variation of the magnetic field and can be used in diffusion measurements. However, magnet design depends directly on its application and, according to the purpose, the field homogeneity may significantly be compromised. This may prevent the determination of diffusion properties of fluids based on the natural inhomogeneity of the field using known techniques. This work introduces a new approach that extends the applicability of diffusion-editing CPMG experiments to NMR devices with highly inhomogeneous magnetic fields, which do not vary linearly in space. Herein, we propose a method to determine a custom diffusion kernel based on the gradient distribution, which can be seen as a signature of each NMR device. This new diffusion kernel is then utilised in the 2D inverse Laplace transform (2D ILT) in order to determine diffusion-relaxation correlation maps of homogeneous multi-phasic fluids. The experiments were performed using NMR MObile Lateral Explore (MOLE), which is a single-sided NMR device designed to maximise the volume at the sweet spot with enhanced depth penetration. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Comparison of methods for measuring flux gradients in type II superconductors

    International Nuclear Information System (INIS)

    Kroeger, D.M.; Koch, C.C.; Charlesworth, J.P.

    1975-01-01

    A comparison has been made of four methods of measuring the critical current density J/sub c/ in hysteretic type II superconductors, having a wide range of K and J/sub c/ values, in magnetic fields up to 70 kOe. Two of the methods, (a) resistive measurements and (b) magnetization measurements, were carried out in static magnetic fields. The other two methods involved analysis of the response of the sample to a small alternating field superimposed on the static field. The response was analyzed either (c) by measuring the third-harmonic content or (d) by integration of the waveform to obtain measure of flux penetration. The results are discussed with reference to the agreement between the different techniques and the consistency of the critical state hypothesis on which all these techniques are based. It is concluded that flux-penetration measurements by method (d) provide the most detailed information about J/sub c/ but that one must be wary of minor failures of the critical state hypothesis. Best results are likely to be obtained by using more than one method. (U.S.)

  13. Fast Plasma Potential Measurements Using an Emissive Probe

    Science.gov (United States)

    Ready, Amanda; Clark, Michael; Endrizzi, Douglass; Forest, Cary; Peterson, Ethan

    2017-10-01

    A heated emissive probe was developed for making direct plasma potential (Vp) measurements in rapidly fluctuating plasmas. Previous experiments on the Big Red Ball (BRB) were hindered by sudden potential drops, making Langmuir measurements of the plasma potential difficult. DC heating of a tungsten filament to emission allowed for fast (4 MHz) floating potential measurements that closely matched Vp. Two BRB experiments currently use the emissive probe. The investigation of unmagnetized, collisionless shocks used plasma potential measurements to study the sub-structure of strong plasma shocks. A separate investigation of emulated magnetospheres in laboratory plasmas used the plasma potential to map the equilibria and instabilities in the electric field of such structures. Results showing electric field measurements and comparison with cold Langmuir measurements will be presented. Future plans for probe modifications and applications to other experiments on the BRB will also be shown.

  14. Two-photon microscopy measurement of CMRO2 using periarteriolar PO2 gradients(Conference Presentation)

    Science.gov (United States)

    Sakadžić, Sava; Yaseen, Mohammad A.; Jaswal, Rajeshwer S.; Roussakis, Emmanuel; Dale, Anders M.; Buxton, Richard B.; Vinogradov, Sergei A.; Boas, David A.; Devor, Anna

    2017-02-01

    The cerebral metabolic rate of oxygen (CMRO2) is an essential parameter for evaluating brain function and pathophysiology. Measurements of CMRO2 with high spatio-temporal resolution are critically important for understanding how the brain copes with metabolic and blood perfusion changes associated with various clinical conditions, such as stroke, periinfarct depolarizations, and various microvasculopathies (e.g., Alzheimer's disease, chronic hypertension). CMRO2 measurements are also important for understanding the physiological underpinnings of functional Magnetic Resonance Imaging signals. However, the currently available approaches for quantifying CMRO2 rely on complex multimodal imaging and mathematical modeling. Here, we introduce a novel method that allows estimation of CMRO2 based on a single measurement modality - two-photon phosphorescence lifetime microscopy (2PLM) imaging of the partial pressure of oxygen (PO2) in cortical tissue. CMRO2 is estimated by fitting the changes of tissue PO2 around cortical penetrating arterioles with the Krogh cylinder model of oxygen diffusion. We measured the baseline CMRO2 in anesthetized rats, and modulated tissue PO2 levels by manipulating the depth of anesthesia. This method has a spatial resolution of approximately 200 μm and it may provide CMRO2 measurements in individual cortical layers or within confined cortical regions such as in ischemic penumbra and the foci of functional activation.

  15. Device for the measurement and recording of the vertical temperature gradient close to the ground

    International Nuclear Information System (INIS)

    Chassany, J. Ph.; Cottignies, S.

    1963-01-01

    The temperature measurement device described in this note is made of 2 series of 15 copper-constantan thermocouples each, disposed along a mast at 5 m and 20 m from the ground, respectively. Thermocouples are protected against direct sunlight and connected to a recorder

  16. Measurement of the temperature Gradient in air using Talbot effect and Moire technique

    International Nuclear Information System (INIS)

    Tavassoly, M.T.; Rasouli, S.

    2000-01-01

    In this paper we have exploited the self-imaging or Talbot effect and Moire technique to measure the temperature distribution in the air enclosed between two paral led plates of different temperatures. This study shows that for the plates width of 60 cm a change of 1 d egC in 1 cm can be easily detected

  17. Quantitation of chemical exchange rates using pulsed-field-gradient diffusion measurements

    International Nuclear Information System (INIS)

    Andrec, Michael; Prestegard, James H.

    1997-01-01

    A new approach to the quantitation of chemical exchange rates is presented, and its utility is illustrated with application to the exchange of protein amide protons with bulk water. The approach consists of a selective-inversion exchange HMQC experiment in which a short spin echo diffusion filter has been inserted into the exchange period. In this way, the kinetics of exchange are encoded directly in an apparent diffusion coefficient which is a function of the position of the diffusion filter in the pulse sequence. A detailed theoretical analysis of this experiment indicates that, in addition to the measurement of simple exchange rates, the experiment is capable of measuring the effect of mediated exchange, e.g. the transfer of magnetization from bulk water to an amide site mediated by an internal bound water molecule or a labile protein side-chain proton in fast exchange with bulk water. Experimental results for rapid water/amide exchange in acyl carrier protein are shown to be quantitatively consistent with the exchange rates measured using a selective-inversion exchange experiment

  18. Measuring and modelling above-ground carbon and tree allometry along a tropical elevation gradient

    DEFF Research Database (Denmark)

    Marshall, A.R.; Willcock, S.; Platts, P.J.

    2012-01-01

    of physical, climatic and edaphic predictors of AGC and tree stature. AGC estimates using stem diameter, height and wood density, gave a mean value of 174.6 t ha−1, compared with 229.6 t ha−1 when height was excluded. Regression models revealed that stems were tallest for a given diameter at mid......:benefit of different measurements and recommend a tiered approach to AGC monitoring, depending on available resources. AGC assessments in African forests could exclude small stems, but should aim to record disturbance, topography and species. Stem height is vital for AGC estimation and valuation; when excluding height...... our 55 t ha−1 over-estimation of AGC would have over-valued the carbon resource by 24% (US$3300 ha−1)....

  19. Automated Measurement for Sensitivity Analysis of Runoff-Sediment Load at Varying Surface Gradients

    Directory of Open Access Journals (Sweden)

    Imanogor P.A.

    2015-07-01

    Full Text Available Direct measurement of surface runoff is often associated with errors and inaccuracies which results to unreliable hydrological data. An automatic Runoff-meter using tipping buckets arrangement calibrated to tip 0.14 liter of runoff water per tip with an accuracy of ± 0.001 litre was used to measure surface runoff from a steel bounded soil tray of dimension (1200 mm X 900 mm X 260 mm filled with sand loamy to the depth of 130 mm and inclined at angle (0 0 , 5 0 ,12 0 and 15 0 horizontal to the instrument. The effect of varying angles of inclination on runoff intensity, sediment loss rate and sediment loss is significant at 5 % confidence level, while surface runoff is not significant at 5 % confidence level. Total highest sediment loss of 458.2 g and 313.4 g were observed at angle 15 0 and 12 0 respectively. Total surface runoff of 361.5 mm and 445.8 mm were generated at inclined angle of 0 0 and 5 0 , while at angle 12 0 and 15 0 , 564.3 mm and 590.0 mm of surface runoff were generated. In addition, runoff intensity and sediment loss rate were highest at angle 15 0 , while the lowest values of 1.5mm/min and 5.43 g/min were obtained at angle of inclination 5 0 . The results showed that strong relationship existed among the hydrological variables as a result of subjecting the steel bounded soil tray to different angles of inclination. Such results would provide useful data for the running of physics-based deterministic model of surface runoff and erosion which will be useful for the design of hydrological structures, land use planning and management.

  20. Novel, cyclic heat dissipation method for the correction of natural temperature gradients in sap flow measurements. Part 2. Laboratory validation.

    Science.gov (United States)

    Reyes-Acosta, J Leonardo; Vandegehuchte, Maurits W; Steppe, Kathy; Lubczynski, Maciek W

    2012-07-01

    Sap flow measurements conducted with thermal dissipation probes (TDPs) are vulnerable to natural temperature gradient (NTG) bias. Few studies, however, attempted to explain the dynamics underlying the NTG formation and its influence on the sensors' signal. This study focused on understanding how the TDP signals are affected by negative and positive temperature influences from NTG and tested the novel cyclic heat dissipation (CHD) method to filter out the NTG bias. A series of three experiments were performed in which gravity-driven water flow was enforced on freshly cut stem segments of Fagus sylvatica L., while an artificial temperature gradient (ATG) was induced. The first experiment sought to confirm the incidence of the ATG on sensors. The second experiment established the mis-estimations caused by the biasing effect of the ATG on standard TDP measurements. The third experiment tested the accuracy of the CHD method to account for the ATG biasing effect, as compared with other cyclic correction methods. During experiments, sap flow measured by TDP was assessed against gravimetric measurements. The results show that negative and positive ATGs were comparable in pattern but substantially larger than field NTGs. Second, the ATG bias caused an overestimation of the standard TDP sap flux density of ∼17 cm(3) cm(-2) h(-1) by 76%, and the sap flux density of ∼2 cm(3) cm(-2) h(-1) by over 800%. Finally, the proposed CHD method successfully reduced the max. ATG bias to 25% at ∼11 cm(3) cm(-2) h(-1) and to 40% at ∼1 cm(3) cm(-2) h(-1). We concluded that: (i) the TDP method is susceptible to NTG especially at low flows; (ii) the CHD method successfully corrected the TDP signal and resulted in generally more accurate sap flux density estimates (mean absolute percentage error ranging between 11 and 21%) than standard constant power TDP method and other cyclic power methods; and (iii) the ATG enforcing system is a suitable way of re-creating NTG for future tests.

  1. Potential measurement and radial transport in GAMMA 10 tandem mirror

    International Nuclear Information System (INIS)

    Ishii, K.; Katanuma, I.; Segawa, T.; Ohkawara, H.; Mase, A.; Miyoshi, S.

    1989-01-01

    GAMMA 10 is an effectively axisymmetric tandem mirror with thermal barriers. Potential information is important to investigate the plasma confinement. The barrier and central space potentials are determined by means of two gold neutral beam probes. Two-dimensional potential profiles have been measured in the barrier cell. In GAMMA 10, to assure magneto-hydrodynamic (MHD) stability, the nonaxisymmetric minimum-B mirror cells are contained between the central-solenoid and the plug/barrier cells at the ends of the machine. From the point of view of neoclassical resonant-plateau transport in circular equipotential contours, this effective axisymmetrization is successful. The measured potential profiles are slightly elongated during the onset of ω ce ECRH. In this paper we report the beam probe potential measurement, the neoclassical ion radial transport in the noncircular equipotential surface and the thermal barrier potential. (author) 6 refs., 5 figs

  2. Space potential, temperature, and density profile measurements on RENTOR

    International Nuclear Information System (INIS)

    Schoch, P.M.

    1983-05-01

    Radial profiles of the space potential, electron temperature, and density have been measured on RENTOR with a heavy-ion-beam probe. The potential profile has been compared to predictions from a stochastic magnetic field fluctuation theory, using the measured temperature and density profiles. The comparison shows strong qualitative agreement in that the potential is positive and the order of T/sub e//e. There is some quantitative disagreement in that the measured radial electric fields are somewhat smaller than the theoretical predictions. To facilitate this comparison, a detailed analysis of the possible errors has been completed

  3. Field comparison of an eddy accumulation and an aerodynamic-gradient system for measuring pesticide volatilization fluxes

    Science.gov (United States)

    Majewski, M.; Desjardina, R.; Rochette, P.; Pattey, E.; Selber, J.; Glotfelty, D.

    1993-01-01

    The field experiment reported here applied the relaxed eddy accumulation (REA) technique to the measurement of triallate (TA) and trifluralin (TF) volatilization from fallow soil. A critical analysis of the REA system used in this experiment is done, and the fluxes are compared to those obtained by the aerodynamic-gradient (AG) technique. The measured cumulative volatilization losses, corrected for the effective upwind source area (footprint), for the AG system were higher than with the REA system. The differences between the methods over the first 5 days of the experiment were 27 and 13% for TA and TF, respectively. A mass balance based on the amount of parent compounds volatilized from soil during the first 5 days of the experiment showed a 110 and 70% and a 79 and 61% accountability for triallate and trifluralin by the AG and REA methods, respectively. These results also show that the non-footprint-corrected AG flux values underestimated the volatilization flux by approximately 16%. The footprint correction model used in this experiment does not presently have the capability of accounting for changes in atmospheric stability. However, these values still provide an indication of the most likely upwind area affecting the evaporative flux estimations. The soil half-lives for triallate and trifluralin were 9.8 and 7.0 days, respectively. ?? 1992 American Chemical Society.

  4. The household food insecurity gradient and potential reductions in adverse population mental health outcomes in Canadian adults.

    Science.gov (United States)

    Jessiman-Perreault, Geneviève; McIntyre, Lynn

    2017-12-01

    Household food insecurity is related to poor mental health. This study examines whether the level of household food insecurity is associated with a gradient in the risk of reporting six adverse mental health outcomes. This study further quantifies the mental health impact if severe food insecurity, the extreme of the risk continuum, were eliminated in Canada. Using a pooled sample of the Canadian Community Health Survey (N = 302,683), we examined the relationship between level of food insecurity, in adults 18-64 years, and reporting six adverse mental health outcomes. We conducted a probit analysis adjusted for multi-variable models, to calculate the reduction in the odds of reporting mental health outcomes that might accrue from the elimination of severe food insecurity. Controlling for various demographic and socioeconomic covariates, a food insecurity gradient was found in six mental health outcomes. We calculated that a decrease between 8.1% and 16.0% in the reporting of these mental health outcomes would accrue if those who are currently severely food insecure became food secure, after controlling for covariates. Household food insecurity has a pervasive graded negative effect on a variety of mental health outcomes, in which significantly higher levels of food insecurity are associated with a higher risk of adverse mental health outcomes. Reduction of food insecurity, particularly at the severe level, is a public health concern and a modifiable structural determinant of health worthy of macro-level policy intervention.

  5. Measurement of nuclear potentials from fusion excitation functions

    International Nuclear Information System (INIS)

    Huizenga, J.R.; Birkelund, J.R.

    1984-01-01

    The basis for measuring nuclear potentials from fusion excitation functions at energies above barrier is reviewed. It is argued that because of experimental and conceptual problems fusion excitation functions at high energies cannot lead to model independent measurements of internuclear potential at small separations. The Al 27 + Ne 20 reaction previously analyzed by others is used as an example of problems arising from the inability to distinguish complete and incomplete fusion in experimental data

  6. Temperature responses of a coccolithophorid, Cricosphaera carterae, measured in a simple and inexpensive thermal-gradient device

    International Nuclear Information System (INIS)

    Blankley, W.F.; Lewin, R.A.

    1976-01-01

    An illuminated thermal-gradient device is described which is of simple construction, very low cost, and wide adaptability to various culture vessels. It can be readily adapted for use in crossed gradients with temperature along one axis. The thermal gradient produced depends on several factors including the heat source (one or more incandescent lamps), heat sink (cold air in a refrigerated box or room), and type of culture vessel. By use of the device, the temperature range for growth of Cricosphaera carterae was found to be 10-26 degrees C, with a maximal growth rate at 20 degrees C

  7. Four-point probe measurements using current probes with voltage feedback to measure electric potentials

    Science.gov (United States)

    Lüpke, Felix; Cuma, David; Korte, Stefan; Cherepanov, Vasily; Voigtländer, Bert

    2018-02-01

    We present a four-point probe resistance measurement technique which uses four equivalent current measuring units, resulting in minimal hardware requirements and corresponding sources of noise. Local sample potentials are measured by a software feedback loop which adjusts the corresponding tip voltage such that no current flows to the sample. The resulting tip voltage is then equivalent to the sample potential at the tip position. We implement this measurement method into a multi-tip scanning tunneling microscope setup such that potentials can also be measured in tunneling contact, allowing in principle truly non-invasive four-probe measurements. The resulting measurement capabilities are demonstrated for \

  8. Timing Affects Measurement of Portal Pressure Gradient After Placement of Transjugular Intrahepatic Portosystemic Shunts in Patients With Portal Hypertension.

    Science.gov (United States)

    Silva-Junior, Gilberto; Turon, Fanny; Baiges, Anna; Cerda, Eira; García-Criado, Ángeles; Blasi, Annabel; Torres, Ferran; Hernandez-Gea, Virginia; Bosch, Jaume; Garcia-Pagan, Juan Carlos

    2017-05-01

    A reduction in portal pressure gradient (PPG) to portal hypertension who received placement of TIPS from January 2008 through October 2015; patients were followed until March 2016. We compared PPG values measured at different time points and under different conditions: immediately after placement of TIPS (immediate PPG); at least 24 hours after placement to TIPS into hemodynamically stable patients, without sedation (early PPG); and again 1 month after TIPS placement (late PPG). The immediate PPG differed significantly from the early PPG, regardless of whether the TIPS was placed using general anesthesia (8.5 ± 3.5 mm Hg vs 10 ± 3.5 mm Hg; P = .015) or deep sedation (12 ± 4 mm Hg vs 10.5 ± 4 mm Hg; P <.001). In considering the 12 mm Hg threshold, concordance between immediate PPG and early PPG values was poor. However, there was no significant difference between mean early PPG and late PPG values (8.5 ± 2.5 mm Hg vs 8 ± 3 mm Hg), or between proportions of patients with early PPG vs late PPG values <12 mm Hg threshold. Maintenance of a PPG value <12 mm Hg during the follow-up period was associated with a lower risk of recurrent or de novo variceal bleeding or ascites (hazard ratio, 0.11; 95% confidence interval, 0.04 0.27; P < .001). In a retrospective study of patients with PPG values measured at different time points after TIPS placement, we found measurements of PPG in awake, hemodynamically stable patients at least 24 hours after TIPS to be the best maintained values. Our findings support the concept that PPG value <12 mm Hg after TIPS placement is associated with reduced risk of bleeding and ascites. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

  9. Focus measure method based on the modulus of the gradient of the color planes for digital microscopy

    Science.gov (United States)

    Hurtado-Pérez, Román; Toxqui-Quitl, Carina; Padilla-Vivanco, Alfonso; Aguilar-Valdez, J. Félix; Ortega-Mendoza, Gabriel

    2018-02-01

    The modulus of the gradient of the color planes (MGC) is implemented to transform multichannel information to a grayscale image. This digital technique is used in two applications: (a) focus measurements during autofocusing (AF) process and (b) extending the depth of field (EDoF) by means of multifocus image fusion. In the first case, the MGC procedure is based on an edge detection technique and is implemented in over 15 focus metrics that are typically handled in digital microscopy. The MGC approach is tested on color images of histological sections for the selection of in-focus images. An appealing attribute of all the AF metrics working in the MGC space is their monotonic behavior even up to a magnification of 100×. An advantage of the MGC method is its computational simplicity and inherent parallelism. In the second application, a multifocus image fusion algorithm based on the MGC approach has been implemented on graphics processing units (GPUs). The resulting fused images are evaluated using a nonreference image quality metric. The proposed fusion method reveals a high-quality image independently of faulty illumination during the image acquisition. Finally, the three-dimensional visualization of the in-focus image is shown.

  10. Development and evaluation of a diffusive gradients in a thin film technique for measuring ammonium in freshwaters

    DEFF Research Database (Denmark)

    Huang, Jianyin; Bennett, William W.; Welsh, David T.

    2016-01-01

    A new diffusive gradients in a thin film (DGT) technique, using Microlite PrCH cation exchange resin, was developed and evaluated for measuring NH4-N in freshwaters. Microlite PrCH had high uptake (>92.5%) and elution efficiencies (87.2% using 2 mol L-1 NaCl). Mass vs. time validation experiments...... over 24 h demonstrated excellent linearity (R2 ≥ 0.996). PrCH-DGT binding layers had an extremely high intrinsic binding capacity for NH4-N (~3000 μg). NH4-N uptake was quantitative over pH ranges 3.5-8.5 and ionic strength (up to 0.012 mol L-1 as NaCl) typical of freshwater systems. Several cations...... (Na+, K+, Ca2+ and Mg2+) were found to compete with NH4-N for uptake by PrCH-DGT, but NH4-N uptake was quantitative over concentration ranges typical of freshwater (up to 0.012 mol L-1 Na+, 0.006 mol L-1 K+, 0.003 mol L-1 Ca2+ and 0.004 mol L-1 Mg2+). Effective diffusion coefficients determined from...

  11. Correlation between thermal gradient and flexure-type deformation as a potential trigger for exfoliation-related rock falls (Invited)

    Science.gov (United States)

    Collins, B. D.; Stock, G. M.

    2010-12-01

    Stress-induced exfoliation of granitic rocks is an important means by which cliffs deform and subsequently erode. During exfoliation, fractures are formed, and when exposed in cliff faces, are susceptible to subsequent rock falls. This is the case in Yosemite National Park, California, where exfoliation continues to play a primary role in cliff evolution. In Yosemite, numerous mechanisms are inferred to trigger rock falls; nevertheless, many rock falls have no recognized triggers. As a result, several potential, but as yet unquantified, triggering mechanisms have been proposed. One of these, thermally induced flexure, wherein solar radiation and temperature variation drives cumulative deformation of partially detached rock flakes, has the potential to explain several recent rock falls in Yosemite. We explore this potential mechanism by quantifying the deformation, temperature, and solar radiation exposure of a near-vertical rock flake in Yosemite Valley. The flake, 14 m tall, 4 m wide and 12 cm thick, receives direct sunlight during most of the day. Whereas the flake is attached to the cliff face at its bottom and top, the sides are detached from the cliff by a 10 cm wide crack on one side, tapering to a 1 cm wide crack on the opposite side. Instrumentation consists of three custom-designed crackmeters placed between the flake and the adjacent cliff face, three air temperature sensors located behind the flake, and three dual air temperature-light sensors located on the outside surface of the flake. Nearby relative humidity and barometric pressure sensors complete the instrumentation. Five-minute interval data from spring - fall 2010 indicate the flake undergoes maximum deformation at mid-span between attachment points and that it deforms from both diurnal and climatic temperature fluctuations. Recorded maximum deformations, measured perpendicular to crack orientation, are 1 cm diurnally and nearly 1.5 cm (including diurnal effect) over a 5-day period of cooler

  12. Influence of natural temperature gradients on measurements of xylem sap flow with thermal dissipation probes. 1. Field observations and possible remedies.

    Science.gov (United States)

    Do, F; Rocheteau, A

    2002-06-01

    The thermal dissipation method is simple and widely used for measuring sap flow in large stems. As with several other thermal methods, natural temperature gradients are assumed to be negligible in the sapwood being measured. We studied the magnitude and variability of natural temperature gradients in sapwood of Acacia trees growing in the Sahelian zone of Senegal, analyzed their effects on sap flow measurements, and investigated possible solutions. A new measurement approach employing cyclic heating (45 minutes of heating and 15 minutes of cooling; 45/15) was also tested. Three-day measurement sequences that included 1 day without heating, a second day with continuous heating and a third day with cyclic heating were recorded during a 6.5-month period using probes installed at three azimuths in a tree trunk. Natural temperature gradients between the two probes of the sensor unit, spaced 8 to 10 cm vertically, were rarely negligible (i.e., solar radiation and low sap flow rate. However, for all applications of the thermal dissipation method, it is wise to check regularly for natural temperature gradients by switching off the heater.

  13. Measuring Polanyi Potentials for Chemsorb 1000 and Chemsorb 3800

    Science.gov (United States)

    Monje, Oscar; Surma, Jan M.; Kayatin, Matthew J.; Perry, Jay L.

    2016-01-01

    Polanyi adsorption potential plots are used to predict the adsorptive capacities of volatile organic compounds onto activated carbons. The design and construction of a test rig for measuring equilibrium adsorption capacities suitable for constructing Polanyi adsorption potential plots for candidate sorbents suitable for use in ECLS systems is presented. The adsorptive capacities of Chemsorb(TradeMark) 1000 and Chemsorb(TradeMark) 800 for ethanol and acetone were measured. The capacities and Polanyi adsorption potential plots for these commercially-available sorbents were compared to that of Barnebey Sutcliffe Type 3032, an acid-impregnated activated carbon utilized aboard the International Space Station.

  14. Determination Gradients of the Earth's Magnetic Field from the Measurements of the Satellites and Inversion of the Kursk Magnetic Anomaly

    Science.gov (United States)

    Karoly, Kis; Taylor, Patrick T.; Geza, Wittmann

    2014-01-01

    We computed magnetic field gradients at satellite altitude, over Europe with emphasis on the Kursk Magnetic Anomaly (KMA). They were calculated using the CHAMP satellite total magnetic anomalies. Our computations were done to determine how the magnetic anomaly data from the new ESA/Swarm satellites could be utilized to determine the structure of the magnetization of the Earths crust, especially in the region of the KMA. Since the ten years of 2 CHAMP data could be used to simulate the Swarm data. An initial East magnetic anomaly gradient map of Europe was computed and subsequently the North, East and Vertical magnetic gradients for the KMA region were calculated. The vertical gradient of the KMA was determined using Hilbert transforms. Inversion of the total KMA was derived using Simplex and Simulated Annealing algorithms. Our resulting inversion depth model is a horizontal quadrangle with upper 300-329 km and lower 331-339 km boundaries.

  15. Measurement of water potential in low-level waste management

    International Nuclear Information System (INIS)

    Jones, T.L.; Gee, G.W.; Kirkham, R.R.; Gibson, D.D.

    1982-08-01

    The measurement of soil water is important to the shallow land burial of low-level waste. Soil water flow is the principle mechanism of radionuclide transport, allows the establishment of stabilizing vegetation and also governs the dissolution and release rates of the waste. This report focuses on the measurement of soil water potential and provides an evaluation of several field instruments that are available for use to monitor waste burial sites located in arid region soils. The theoretical concept of water potential is introduced and its relationship to water content and soil water flow is discussed. Next, four major areas of soils research are presented in terms of their dependence on the water potential concept. There are four basic types of sensors used to measure soil water potential. These are: (1) tensiometers; (2) soil psychrometers; (3) electrical resistance blocks; and (4) heat dissipation probes. Tensiometers are designed to measure the soil water potential directly by measuring the soil water pressure. Monitoring efforts at burial sites require measurements of soil water over long time periods. They also require measurements at key locations such as waste-soil interfaces and within any barrier system installed. Electrical resistance blocks are well suited for these types of measurements. The measurement of soil water potential can be a difficult task. There are several sensors commercially available; however, each has its own limitations. It is important to carefully select the appropriate sensor for the job. The accuracy, range, calibration, and stability of the sensor must be carefully considered. This study suggests that for waste management activities, the choice of sensor will be the tensiometer for precise soil characterization studies and the electrical resistance block for long term monitoring programs

  16. Characteristic features of net information measures for constrained Coulomb potentials

    International Nuclear Information System (INIS)

    Patil, S H; Sen, K D; Watson, N A; Jr, H E Montgomery

    2007-01-01

    The dimensional analyses of the position and momentum variance based quantum mechanical Heisenberg uncertainty measure and the other useful net entropic information measures for the bound states of two constrained Coulomb potentials are reported for the first time. The potentials describe an electron moving in the central field due to a nucleus of charge Z with radius R defining the constraints as (a) the truncated potential given by -Z/(r n +R n ) 1/n , and (b) the radius of the impenetrable spherical wall. The net information measures for the two potentials are explicitly shown to be independent of the scaling of the set [Z, R] at a fixed value of ZR. Analytic proof is presented, for the first time, showing the presence of a characteristic extremum in the variation of the net information entropy as a function of the radius R with its location scaling as Z -1 . Numerical results are presented which support the validity of the scaling properties

  17. Potential barrier classification by short-time measurement

    International Nuclear Information System (INIS)

    Granot, Er'el; Marchewka, Avi

    2006-01-01

    We investigate the short-time dynamics of a delta-function potential barrier on an initially confined wave packet. There are mainly two conclusions: (A) At short times the probability density of the first particles that passed through the barrier is unaffected by it. (B) When the barrier is absorptive (i.e., its potential is imaginary) it affects the transmitted wave function at shorter times than a real potential barrier. Therefore, it is possible to distinguish between an imaginary and a real potential barrier by measuring its effect at short times only on the transmitting wave function

  18. Potential barrier classification by short-time measurement

    Science.gov (United States)

    Granot, Er'El; Marchewka, Avi

    2006-03-01

    We investigate the short-time dynamics of a delta-function potential barrier on an initially confined wave packet. There are mainly two conclusions: (A) At short times the probability density of the first particles that passed through the barrier is unaffected by it. (B) When the barrier is absorptive (i.e., its potential is imaginary) it affects the transmitted wave function at shorter times than a real potential barrier. Therefore, it is possible to distinguish between an imaginary and a real potential barrier by measuring its effect at short times only on the transmitting wave function.

  19. Measurement of gastrointestinal transmural electric potential difference in man.

    Science.gov (United States)

    Geall, M G; Code, C F; McIlrath, D C; Summerskill, W H

    1970-01-01

    Measurement, in man, of the electric potential difference between venous blood and the mucosal surface of the gastrointestinal tract gave identical values to the potential difference between mucosa and serosa. Various parts of the peritoneum were equipotential with venous blood. By contrast, skin-enteric potential difference varied with time and among different subjects because of a potential difference between skin and blood that is unpredictably reduced by skin injury. The results with electrolyte bridges of KCl in agar or of flowing KCl were identical.

  20. Exercise-induced intra-ventricular gradients as a frequent potential cause of myocardial ischemia in cardiac syndrome X patients

    Directory of Open Access Journals (Sweden)

    Almeida Ana G

    2008-01-01

    Full Text Available Abstract Background The development of intra-ventricular gradients (IVG during dobutamine or exercise stress is not infrequent, and can be associated to symptoms during stress. The purpose of this study was to assess the occurrence of IVG during exercise stress echocardiography in cardiac syndrome X patients. Methods We prospectively evaluated 91 patients (pts mean aged 51 ± 12 years (age ranged 20 to 75 years old, 44 of whom were women. All pts had angina, positive exercise ECG treadmill testing, normal rest echocardiogram and no coronary artery disease on coronary angiogram (cardiac X syndrome. After complete Doppler echocardiographic evaluation with determination of left ventricular outflow tract index (LVOTi, relative left ventricular wall thickness (RLVWT and left ventricular end-diastolic volume index (LVDVi, all patients underwent stress echocardiography with two-dimensional and Doppler echographic evaluation during and after treadmill exercise. Results For analysis purpose patients were divided in 2 groups, according to the development of IVG. Doppler evidence of IVG was found in 33 (36% of the patients (Group A, with mean age 47 ± 14 years old (age ranged 20 to 72 years and with a mean end-systolic peak gradient of 86 ± 34 mmHg (ranging from 30 to 165 mmHg. The IVG development was accompanied by SAM of the mitral valve in 23 pts. Three of these pts experienced symptomatic hypotension. Ten were women (30% pts. 58 pts in group B, 34 of whom were women (59% (p = 0,01 vs group A, mean aged 53,5 ± 10,9 years old (age ranged 34 to 75 years (p = 0,03 vs group A, did not develop IVG. LVOTi was 10,29 ± 0,9 mm/m2 in group A and 11,4 ± 1 mm/m2 in group B (p 2 in group A and 56 ± 11,6 ml/m2 in group B (p = 0,000. Conclusion 1. A significant number of patients with cardiac X syndrome developed IVG during upright exercise in treadmill. These pts (group A are mainly males and younger than those who did not develop IVG. 2. The development of IVG

  1. Simultaneous measurement of trace metal and oxyanion concentrations in water using diffusive gradients in thin films with a chelex-metsorb mixed binding layer

    DEFF Research Database (Denmark)

    Panther, Jared G.; Bennett, William W.; Welsh, David T.

    2014-01-01

    A new diffusive gradients in thin films (DGT) technique with a mixed binding layer (Chelex-100 and the titanium dioxide based adsorbent Metsorb) is described for the simultaneous measurement of labile trace metal (Mn, Co, Ni, Cu, Cd, and Pb) and oxyanion (V, As, Mo, Sb, W, and P) concentrations i...

  2. Potential drop crack measurement systems for CANDU components

    Energy Technology Data Exchange (ETDEWEB)

    Sahney, R [Carleton Univ., Ottawa, ON (Canada)

    1994-12-31

    A project to develop an automated crack measurement system for CANDU pressure tube burst testing is currently underway. The system will utilize either Direct Current Potential Drop (DCPD) or Alternating Current Potential Drop (ACPD) techniques for crack measurement. The preliminary stage of the project involves testing and comparison of both ACPD and DCPD methods on a Zr - 2.5% Nb alloy plate with saw cuts (used to simulate cracks). Preliminary results show that both ACPD and DCPD techniques are capable of detecting cracks; further testing is in progress to determine the ability of each of the two systems to make accurate crack depth measurements. This paper will describe the two potential drop techniques and will present test results from the experimental program. (author). 10 refs., 7 figs.

  3. Thermal and epithermal neutron fluence rate gradient measurements by PADC detectors in LINAC radiotherapy treatments-field

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, M. T., E-mail: mariate9590@gmail.com; Barros, H.; Pino, F.; Sajo-Bohus, L. [Universidad Simón Bolívar, Nuclear Physics Laboratory, Sartenejas, Caracas (Venezuela, Bolivarian Republic of); Dávila, J. [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    LINAC VARIAN 2100 is where energetic electrons produce Bremsstrahlung radiation, with energies above the nucleon binding energy (E≈5.5MeV). This radiation induce (γ,n) and (e,e’n) reactions mainly in the natural tungsten target material (its total photoneutron cross section is about 4000 mb in a energy range from 9-17 MeV). These reactions may occur also in other components of the system (e.g. multi leaf collimator). During radiation treatment the human body may receive an additional dose inside and outside the treated volume produced by the mentioned nuclear reactions. We measured the neutron density at the treatment table using nuclear track detectors (PADC-NTD). These covered by a boron-converter are employed, including a cadmium filter, to determine the ratio between two groups of neutron energy, i.e. thermal and epithermal. The PADC-NTD detectors were exposed to the radiation field at the iso-center during regular operation of the accelerator. Neutron are determined indirectly by the converting reaction {sup 10}B(n,α){sup 7}Li the emerging charged particle leave their kinetic energy in the PADC forming a latent nuclear track, enlarged by chemical etching (6N, NaOH, 70°C). Track density provides information on the neutron density through calibration coefficient (∼1.6 10{sup 4} neutrons /track) obtained by a californium source. We report the estimation of the thermal and epithermal neutron field and its gradient for photoneutrons produced in radiotherapy treatments with 18 MV linear accelerators. It was obsered that photoneutron production have higher rate at the iso-center.

  4. Four-point potential drop measurements for materials characterization

    International Nuclear Information System (INIS)

    Bowler, Nicola

    2011-01-01

    The technique of measuring the voltage difference (potential drop) between two of the four electrodes of a four-point probe, in order to determine conductivity or surface resistivity of a test piece, is well established in the direct-current (dc) or quasi-dc regime. The technique finds wide usage in the semiconductor industry for the purpose of measuring surface resistivity of semiconductors, and also in the measurement of conductivity of metals, particularly of ferromagnetic metals for which conductivity cannot be easily measured using eddy-current nondestructive evaluation (NDE). In these applications, the conductivity of the test piece is deduced from an analytic formula that depends on the geometry of the probe and test piece. Such a formula requires, as an input, the measured value of the potential drop. Several analytical expressions exist for a variety of test-piece geometries and probe arrangements. Recently, it has been shown that broadband measurements of the potential drop, known as 'alternating current potential drop' (ac PD) measurements, can be used not only to obtain the conductivity of a test piece, but also its linear permeability μ. The beauty of this measurement is that the two parameters are completely decoupled in the quasi-static regime. In fact, μ does not appear in the quasi-static expression for σ. Hence, σ may be obtained from low-frequency ac PD measurements and then μ may be deduced as the frequency increases beyond the quasi-static regime, once σ is known. In this review, both dc and ac solutions that are useful in determining the conductivity of metals and semiconductors, and the permeability of ferromagnetic conductors, are summarized. In particular, flat test pieces with arbitrary thickness are considered. At the next level of complexity, a solution for a half-space coated with a surface layer is given, along with a discussion of the use of the four-point potential drop method for determining thickness of a surface layer, such

  5. Developing alternative indices of reproductive potential for use in fisheries management : Case studies for stocks spanning an information gradient

    DEFF Research Database (Denmark)

    Marshall, C.T.; O'Brien, L.; Tomkiewicz, Jonna

    2003-01-01

    There is accumulating evidence to suggest that spawning stock biomass (SSB) may not bedirectly proportional to reproductive potential. The wide-ranging implications of this conclu-sion necessitate that it be tested for as many stocks as possible. Undertaking such tests iscomplicated by the fact...... that fish stocks vary in the amount and type of information that isavailable to estimate reproductive potential. In this review, nine stocks illustrate the range of approaches that are being taken to developing alternative indices of reproductive potential fromexisting data resources. Three stocks had...... sufficient data to reconstruct a time series of total eggproduction (TEP), whereas, the remaining stocks were limited to estimating proxies for stockreproductive potential. For some of the case studies the alternative indices explained a higheramount of recruitment variation than did SSB. Other case studies...

  6. SCANNING VOLTA POTENTIALS MEASUREMENTS OF METALS IN IRRADIATED AIR.

    Energy Technology Data Exchange (ETDEWEB)

    ISAACS, H.S.; ADZIC, G.; AND ENERGY SCIENCES AND TECHNOLOGY DEPARTMENT; JEFFCOATE, C.S.

    2000-10-22

    A method for direct dc measurement of the Volta potential is presented. High intensity synchrotron x-ray beams were used to locally irradiate the atmosphere adjacent to the metal surface and produce a conducting path between a sample and a reference probe. The direct measurements of potential in the ionized air could be made at probe heights of around 1 mm compared to less than 0.1 mm for the Kelvin probe. The measurements were similar to traditional Kelvin probe measurements, but had a poorer spatial resolution. In contrast to the Kelvin probe methods, the approach described allows observation of the current as a function of impressed voltage. Methods to improve the special resolution of the technique and applications to corrosion under coating will be presented.

  7. Measurements of the electric field gradient at cadmium in YBa2Cu3Ox, Y2BaCuO5 and Y2Cu2O5

    International Nuclear Information System (INIS)

    Saitovitch, H.; Silva, P.R.J.

    1990-01-01

    The electric Field Gradient (EFG) at diluted Cd sup(111) in YBa sub(2)Cu sub(3)O sub(x) was measured by Angular Correlation (AC). In order to determine the atom-probe localization, AC measurements were also, performed on Y sub(2)BaCuO sub(5). A nuclear electric quadrupole interaction frequency (NQIF) was associated with Cd sup(111) in YBa sub(2)Cu sub(3) O sub(x) Cu(1) site. (author)

  8. Investigating intra-tumor heterogeneity and expression gradients of miR-21, miR-92a and miR-200c and their potential of predicting lymph node metastases in early colorectal cancer

    DEFF Research Database (Denmark)

    Jepsen, Rikke Karlin; Novotny, Guy Wayne; Klarskov, Louise Laurberg

    2016-01-01

    Introduction miR-21, miR-92a and miR-200c are regulators of pathways involved in migration, intravasation and metastasis, and their tumor expression levels have been proposed as potential prognostic markers in colorectal cancer (CRC). In two parallel cohorts we examine intra-tumor expression levels...... in early stage CRC tissue in order to determine intra-tumor heterogeneity, potential systematic intra-tumor expression gradients of the miRNAs and to investigate the association to metastatic disease in early stage CRC. Material and methods Two parallel studies on archived formalin-fixed paraffin......-embedded (FFPE) CRC tissue. Intra-tumor and inter-patient variances were analyzed in 9 early metastatic CRCs by measuring expression levels by qRT-PCR on isolated tissue samples from luminal, central and invasive border zones. Associations between miRNA expression levels and early metastasizing tumors...

  9. Influence of beverage composition on the results of erosive potential measurement by different measurement techniques

    NARCIS (Netherlands)

    Jager, D. H. J.; Vieira, A. M.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2008-01-01

    The influence of beverage composition on the measurement of erosive potential is unclear. The aim of this study was to evaluate whether beverage composition influences the measurement of erosive potential and to evaluate the influence of exposure in small and large volumes. Eleven beverages were

  10. Influence of beverage composition on the results of erosive potential measurement by different measurement techniques.

    NARCIS (Netherlands)

    Jager, D.H.; Vieira, A.M.; Ruben, J.L.; Huysmans, M.C.D.N.J.M.

    2008-01-01

    The influence of beverage composition on the measurement of erosive potential is unclear. The aim of this study was to evaluate whether beverage composition influences the measurement of erosive potential and to evaluate the influence of exposure in small and large volumes. Eleven beverages were

  11. Temperature Gradient in Hall Thrusters

    International Nuclear Information System (INIS)

    Staack, D.; Raitses, Y.; Fisch, N.J.

    2003-01-01

    Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons

  12. Methods for direct measurement of the plasma potential

    DEFF Research Database (Denmark)

    Andersen, S. A.; Christoffersen, G. B.; Jensen, Vagn Orla

    1972-01-01

    Reports on a simple experimental technique which can be used for determination of the plasma where the plasma potential prevails; these ions are accepted by the analyser plate when phi c= phi pl. Part of this technique has been used by Andersen, Jensen, Michelsen and Nielsen (1971) in measurements...

  13. Automatic measurement for monitoring crack growth with electric potential technique

    International Nuclear Information System (INIS)

    Nakajima, Nobuya; Kikuchi, Masaaki; Shima, Seishi

    1981-10-01

    In the study of fracture mechanics, it is one of the most important problems to monitor the crack growth phenomena. Recently, many experimental methods have been developed. In this report, the Direct Current (DC) potential method is employed for measuring the crack growth length in the pressuried high temperature water. The objective of the current investigation is to develop an experimental method to quantify the sensitivity of this method in the air environment using the Compact Tension (CT) specimen. The main results obtained are as follows: 1) It is ignored that the electrical potential changes with plastic deformation at the crack tip of the specimen. 2) Using the Reversible Direct Current (RDC) Method, the measurement system gives no effect on the electrical stability for a long time. 3) For the fatigue and statical crack growth length, good relation is observed between the crack length-to-specimen width ratio (a/W) and potential ratio (Va/Vo). (author)

  14. Measuring canopy loss and climatic thresholds from an extreme drought along a fivefold precipitation gradient across Texas.

    Science.gov (United States)

    Schwantes, Amanda M; Swenson, Jennifer J; González-Roglich, Mariano; Johnson, Daniel M; Domec, Jean-Christophe; Jackson, Robert B

    2017-12-01

    Globally, trees are increasingly dying from extreme drought, a trend that is expected to increase with climate change. Loss of trees has significant ecological, biophysical, and biogeochemical consequences. In 2011, a record drought caused widespread tree mortality in Texas. Using remotely sensed imagery, we quantified canopy loss during and after the drought across the state at 30-m spatial resolution, from the eastern pine/hardwood forests to the western shrublands, a region that includes the boundaries of many species ranges. Canopy loss observations in ~200 multitemporal fine-scale orthophotos (1-m) were used to train coarser Landsat imagery (30-m) to create 30-m binary statewide canopy loss maps. We found that canopy loss occurred across all major ecoregions of Texas, with an average loss of 9.5%. The drought had the highest impact in post oak woodlands, pinyon-juniper shrublands and Ashe juniper woodlands. Focusing on a 100-km by ~1,000-km transect spanning the State's fivefold east-west precipitation gradient (~1,500 to ~300 mm), we compared spatially explicit 2011 climatic anomalies to our canopy loss maps. Much of the canopy loss occurred in areas that passed specific climatic thresholds: warm season anomalies in mean temperature (+1.6°C) and vapor pressure deficit (VPD, +0.66 kPa), annual percent deviation in precipitation (-38%), and 2011 difference between precipitation and potential evapotranspiration (-1,206 mm). Although similarly low precipitation occurred during the landmark 1950s drought, the VPD and temperature anomalies observed in 2011 were even greater. Furthermore, future climate data under the representative concentration pathway 8.5 trajectory project that average values will surpass the 2011 VPD anomaly during the 2070-2099 period and the temperature anomaly during the 2040-2099 period. Identifying vulnerable ecological systems to drought stress and climate thresholds associated with canopy loss will aid in predicting how forests will

  15. Detecting rapid mass movements using electrical self-potential measurements

    Science.gov (United States)

    Heinze, Thomas; Limbrock, Jonas; Pudasaini, Shiva P.; Kemna, Andreas

    2017-04-01

    Rapid mass movements are a latent danger for lives and infrastructure in almost any part of the world. Often such mass movements are caused by increasing pore pressure, for example, landslides after heavy rainfall or dam breaking after intrusion of water in the dam. Among several other geophysical methods used to observe water movement, the electrical self-potential method has been applied to a broad range of monitoring studies, especially focusing on volcanism and dam leakage but also during hydraulic fracturing and for earthquake prediction. Electrical self-potential signals may be caused by various mechanisms. Though, the most relevant source of the self-potential field in the given context is the streaming potential, caused by a flowing electrolyte through porous media with electrically charged internal surfaces. So far, existing models focus on monitoring water flow in non-deformable porous media. However, as the self-potential is sensitive to hydraulic parameters of the soil, any change in these parameters will cause an alteration of the electric signal. Mass movement will significantly influence the hydraulic parameters of the solid as well as the pressure field, assuming that fluid movement is faster than the pressure diffusion. We will present results of laboratory experiments under drained and undrained conditions with fluid triggered as well as manually triggered mass movements, monitored with self-potential measurements. For the undrained scenarios, we observe a clear correlation between the mass movements and signals in the electric potential, which clearly differ from the underlying potential variations due to increased saturation and fluid flow. In the drained experiments, we do not observe any measurable change in the electric potential. We therefore assume that change in fluid properties and release of the load causes disturbances in flow and streaming potential. We will discuss results of numerical simulations reproducing the observed effect. Our

  16. Proper orthogonal decomposition-based estimations of the flow field from particle image velocimetry wall-gradient measurements in the backward-facing step flow

    International Nuclear Information System (INIS)

    Nguyen, Thien Duy; Wells, John Craig; Mokhasi, Paritosh; Rempfer, Dietmar

    2010-01-01

    In this paper, particle image velocimetry (PIV) results from the recirculation zone of a backward-facing step flow, of which the Reynolds number is 2800 based on bulk velocity upstream of the step and step height (h = 16.5 mm), are used to demonstrate the capability of proper orthogonal decomposition (POD)-based measurement models. Three-component PIV velocity fields are decomposed by POD into a set of spatial basis functions and a set of temporal coefficients. The measurement models are built to relate the low-order POD coefficients, determined from an ensemble of 1050 PIV fields by the 'snapshot' method, to the time-resolved wall gradients, measured by a near-wall measurement technique called stereo interfacial PIV. These models are evaluated in terms of reconstruction and prediction of the low-order temporal POD coefficients of the velocity fields. In order to determine the estimation coefficients of the measurement models, linear stochastic estimation (LSE), quadratic stochastic estimation (QSE), principal component regression (PCR) and kernel ridge regression (KRR) are applied. We denote such approaches as LSE-POD, QSE-POD, PCR-POD and KRR-POD. In addition to comparing the accuracy of measurement models, we introduce multi-time POD-based estimations in which past and future information of the wall-gradient events is used separately or combined. The results show that the multi-time estimation approaches can improve the prediction process. Among these approaches, the proposed multi-time KRR-POD estimation with an optimized window of past wall-gradient information yields the best prediction. Such a multi-time KRR-POD approach offers a useful tool for real-time flow estimation of the velocity field based on wall-gradient data

  17. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Armitage, Heather F., E-mail: h.armitage@abdn.ac.u [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Britton, Andrea J. [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Woodin, Sarah J. [Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Wal, Rene van der [Aberdeen Centre for Environmental Sustainability (ACES), School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom)

    2011-01-15

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha{sup -1} yr{sup -1}) and a low N deposition site, Ben Wyvis (7.2 kg ha{sup -1} yr{sup -1}). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  18. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    International Nuclear Information System (INIS)

    Armitage, Heather F.; Britton, Andrea J.; Woodin, Sarah J.; Wal, Rene van der

    2011-01-01

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha -1 yr -1 ) and a low N deposition site, Ben Wyvis (7.2 kg ha -1 yr -1 ). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  19. Fundamental limits to position determination by concentration gradients.

    Directory of Open Access Journals (Sweden)

    Filipe Tostevin

    2007-04-01

    Full Text Available Position determination in biological systems is often achieved through protein concentration gradients. Measuring the local concentration of such a protein with a spatially varying distribution allows the measurement of position within the system. For these systems to work effectively, position determination must be robust to noise. Here, we calculate fundamental limits to the precision of position determination by concentration gradients due to unavoidable biochemical noise perturbing the gradients. We focus on gradient proteins with first-order reaction kinetics. Systems of this type have been experimentally characterised in both developmental and cell biology settings. For a single gradient we show that, through time-averaging, great precision potentially can be achieved even with very low protein copy numbers. As a second example, we investigate the ability of a system with oppositely directed gradients to find its centre. With this mechanism, positional precision close to the centre improves more slowly with increasing averaging time, and so longer averaging times or higher copy numbers are required for high precision. For both single and double gradients, we demonstrate the existence of optimal length scales for the gradients for which precision is maximized, as well as analyze how precision depends on the size of the concentration-measuring apparatus. These results provide fundamental constraints on the positional precision supplied by concentration gradients in various contexts, including both in developmental biology and also within a single cell.

  20. Attention effects at auditory periphery derived from human scalp potentials: displacement measure of potentials.

    Science.gov (United States)

    Ikeda, Kazunari; Hayashi, Akiko; Sekiguchi, Takahiro; Era, Shukichi

    2006-10-01

    It is known in humans that electrophysiological measures such as the auditory brainstem response (ABR) are difficult to identify the attention effect at the auditory periphery, whereas the centrifugal effect has been detected by measuring otoacoustic emissions. This research developed a measure responsive to the shift of human scalp potentials within a brief post-stimulus period (13 ms), that is, displacement percentage, and applied it to an experiment to retrieve the peripheral attention effect. In the present experimental paradigm, tone pips were exposed to the left ear whereas the other ear was masked by white noise. Twelve participants each conducted two conditions of either ignoring or attending to the tone pips. Relative to averaged scalp potentials in the ignoring condition, the shift of the potentials was found within early component range during the attentive condition, and displacement percentage then revealed a significant magnitude difference between the two conditions. These results suggest that, using a measure representing the potential shift itself, the peripheral effect of attention can be detected from human scalp potentials.

  1. Surface contact potential patches and Casimir force measurements

    International Nuclear Information System (INIS)

    Kim, W. J.; Sushkov, A. O.; Lamoreaux, S. K.; Dalvit, D. A. R.

    2010-01-01

    We present calculations of contact potential surface patch effects that simplify previous treatments. It is shown that, because of the linearity of Laplace's equation, the presence of patch potentials does not affect an electrostatic calibration of a two-plate Casimir measurement apparatus. Using models that include long-range variations in the contact potential across the plate surfaces, a number of experimental observations can be reproduced and explained. For these models, numerical calculations show that if a voltage is applied between the plates which minimizes the force, a residual electrostatic force persists, and that the minimizing potential varies with distance. The residual force can be described by a fit to a simple two-parameter function involving the minimizing potential and its variation with distance. We show the origin of this residual force by use of a simple parallel capacitor model. Finally, the implications of a residual force that varies in a manner different from 1/d on the accuracy of previous Casimir measurements is discussed.

  2. A novel MR-compatible sensor to assess active medical device safety: stimulation monitoring, rectified radio frequency pulses, and gradient-induced voltage measurements.

    Science.gov (United States)

    Barbier, Thérèse; Aissani, Sarra; Weber, Nicolas; Pasquier, Cédric; Felblinger, Jacques

    2018-03-30

    To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations. An MRI-compatible voltage probe with a bandwidth of 0-40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1.5 T (64 MHz) MR scanner. The sensor exhibits a measurement range of ± 15 V with an amplitude resolution of 7 mV and a temporal resolution of 10 µs. Rectification was measured on the bench with the overvoltage protection circuit. Linear proportionality was confirmed between the induced voltage and the magnetic field gradient slew rate. The pacemaker pacing was recorded successfully during MRI scans. The characteristics of this low-frequency voltage probe allow its use with extreme RF transmission power and magnetic field gradient positioning for MR safety test of AIMD during MRI scans.

  3. The discrepancy between human peripheral nerve chronaxie times as measured using magnetic and electric field stimuli: the relevance to MRI gradient coil safety

    International Nuclear Information System (INIS)

    Recoskie, Bryan J; Chronik, Blaine A; Scholl, Timothy J

    2009-01-01

    Peripheral nerve stimulation (PNS) resulting from electric fields induced from the rapidly changing magnetic fields of gradient coils is a concern in MRI. Nerves exposed to either electric fields or changing magnetic fields would be expected to display consistent threshold characteristics, motivating the direct application of electric field exposure criteria from the literature to guide the development of gradient magnetic field exposure criteria for MRI. The consistency of electric and magnetic field exposures was tested by comparing chronaxie times for electric and magnetic PNS curves for 22 healthy human subjects. Electric and magnetic stimulation thresholds were measured for exposure of the forearm using both surface electrodes and a figure-eight magnetic coil, respectively. The average chronaxie times for the electric and magnetic field conditions were 109 ± 11 μs and 651 ± 53 μs (±SE), respectively. We do not propose that these results call into question the basic mechanism, namely that rapidly switched gradient magnetic fields induce electric fields in human tissues, resulting in PNS. However, this result does motivate us to suggest that special care must be taken when using electric field exposure data from the literature to set gradient coil PNS safety standards in MRI.

  4. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  5. Heating/ethanol-response of poly methyl methacrylate (PMMA) with gradient pre-deformation and potential temperature sensor and anti-counterfeit applications

    International Nuclear Information System (INIS)

    Lu, Haibao; Huang, Wei Min; Ge, Yu Chun; Zhang, Fan; Zhao, Yong; Wu, Xue Lian; Geng, Junfeng

    2014-01-01

    In this paper, the heating/ethanol-response of a commercial poly methyl methacrylate (PMMA) is investigated. All PMMA samples are pre-deformed by means of impression (surface compression with a mold) to introduce a gradient pre-strain/stress field. Two types of molds are applied in impression. One is a Singaporean coin and the other is a particularly designed mold with a variable protrusive feature on top. Two potential applications—temperature sensors to monitor overheating temperatures and anti-counterfeit labels with a water-mark that appears only upon heating to a particular temperature—are demonstrated. Since the heating-responsive shape memory effect (SME) is an intrinsic feature of almost all polymers, other conventional polymers may be used in such applications as well. (technical note)

  6. Measuring the inward FDI potential of South African regions

    Directory of Open Access Journals (Sweden)

    W. Krugell

    2008-12-01

    Full Text Available Purpose: The purpose of this paper is to construct an index that captures the factors expected to affect a local economy's attractiveness to foreign investors. Problem statement: Following South Africa's reintegration into the world economy in 1994, foreign direct investment has been seen as a potential driver of growth and development. Concerns about the low investment rate in South Africa raise the possibility of augmenting domestic with foreign investment expenditure. The potential of technology spillovers and skills transfer from foreign direct investment have also been emphasised. As a result, Trade and Investment South Africa is involved in identifying, packaging and promoting investment opportunities. However, investments tend to be place-specific and this has lead to the decentralisation of foreign direct investment promotion. Currently the nine provincial development agencies are competing to attract investors and the larger local governments are also getting involved in the fray. This paper argues that some places have better potential to attract foreign investment than others. A first step to use scarce investment promotion resources more efficiently would be to measure the inward FDI potential of South African regions. Approach: This paper uses principal components analysis to construct an index that captures the factors expected to affect a local economy's attractiveness to foreign investors. This approach draws on UNCTAD's Inward FDI Potential Index and applies it to 354 magisterial districts in South Africa for the periods 1996, 2001 and 2006. The index creates a summary measure of FDI potential. Findings: The results show that different places present differential potential in urbanization and localization economies and market size. The high-potential locations are typically found in or around the major agglomerations, but there are a few smaller places on the periphery that offer FDI potential. Contribution: The index should aid

  7. Development of negative heavy ion sources for plasma potential measurement

    International Nuclear Information System (INIS)

    Sasao, M.; Okabe, Y.; Fujisawa, A.; Iguchi, H.; Fujita, J.; Yamaoka, H.; Wada, M.

    1991-10-01

    A plasma sputter negative ion source was studied for its applicability to the potential measurement of a fusion plasma. Both the beam current density and the beam energy spread are key issues. Energy spectra of a self extracted Au - beam from the source were measured under the condition of a constant work function of the production surface. The full width of half maximum (FWHM) increases from 3 eV to 9 eV monotonically as the target voltage increases from 50 V to 300 V, independently from the target surface work function of 2.2 - 3 eV. (author)

  8. Travelling gradient thermocouple calibration

    International Nuclear Information System (INIS)

    Broomfield, G.H.

    1975-01-01

    A short discussion of the origins of the thermocouple EMF is used to re-introduce the idea that the Peltier and Thompson effects are indistinguishable from one another. Thermocouples may be viewed as devices which generate an EMF at junctions or as integrators of EMF's developed in thermal gradients. The thermal gradient view is considered the more appropriate, because of its better accord with theory and behaviour, the correct approach to calibration, and investigation of service effects is immediately obvious. Inhomogeneities arise in thermocouples during manufacture and in service. The results of travelling gradient measurements are used to show that such effects are revealed with a resolution which depends on the length of the gradient although they may be masked during simple immersion calibration. Proposed tests on thermocouples irradiated in a nuclear reactor are discussed

  9. Activity concentration measurements using a conjugate gradient (Siemens xSPECT) reconstruction algorithm in SPECT/CT.

    Science.gov (United States)

    Armstrong, Ian S; Hoffmann, Sandra A

    2016-11-01

    The interest in quantitative single photon emission computer tomography (SPECT) shows potential in a number of clinical applications and now several vendors are providing software and hardware solutions to allow 'SUV-SPECT' to mirror metrics used in PET imaging. This brief technical report assesses the accuracy of activity concentration measurements using a new algorithm 'xSPECT' from Siemens Healthcare. SPECT/CT data were acquired from a uniform cylinder with 5, 10, 15 and 20 s/projection and NEMA image quality phantom with 25 s/projection. The NEMA phantom had hot spheres filled with an 8 : 1 activity concentration relative to the background compartment. Reconstructions were performed using parameters defined by manufacturer presets available with the algorithm. The accuracy of activity concentration measurements was assessed. A dose calibrator-camera cross-calibration factor (CCF) was derived from the uniform phantom data. In uniform phantom images, a positive bias was observed, ranging from ∼6% in the lower count images to ∼4% in the higher-count images. On the basis of the higher-count data, a CCF of 0.96 was derived. As expected, considerable negative bias was measured in the NEMA spheres using region mean values whereas positive bias was measured in the four largest NEMA spheres. Nonmonotonically increasing recovery curves for the hot spheres suggested the presence of Gibbs edge enhancement from resolution modelling. Sufficiently accurate activity concentration measurements can easily be measured on images reconstructed with the xSPECT algorithm without a CCF. However, the use of a CCF is likely to improve accuracy further. A manual conversion of voxel values into SUV should be possible, provided that the patient weight, injected activity and time between injection and imaging are all known accurately.

  10. Measurement of event-related potentials and placebo

    Directory of Open Access Journals (Sweden)

    Sovilj Platon

    2014-01-01

    Full Text Available ERP is common abbreviation for event-related brain potentials, which are measured and used in clinical practice as well as in research practice. Contemporary studies of placebo effect are often based on functional neuromagnetic resonance (fMRI, positron emission tomography (PET, and event related potentials (ERP. This paper considers an ERP instrumentation system used in experimental researches of placebo effect. This instrumentation system can be divided into four modules: electrodes and cables, conditioning module, digital measurement module, and PC module for stimulations, presentations, acquisition and data processing. The experimental oddball paradigm is supported by the software of the instrumentation. [Projekat Ministarstva nauke Republike Srbije, br. TR32019 and Provincial Secretariat for Science and Technological Development of Autonomous Province of Vojvodina (Republic of Serbia under research grant No. 114-451-2723

  11. FAIR VALUE MEASUREMENT IN AGRICULTURE AND THE POTENTIAL TO MISLEAD

    Directory of Open Access Journals (Sweden)

    VLADU ALINA BEATTRICE

    2013-08-01

    Full Text Available Applying fair value measurement to tangible and intangible assets in agriculture cannot be risk free. Twofoldreasons can be brought into attention for the above statement: fair value estimation and the specific of agriculturefield. The purpose of this discussion paper is to underline potential creative accounting demarches that can appear inthis context. The paper concludes based on the discussions approached in the literature. Further avenues of researchare discussed.

  12. Classifying Floating Potential Measurement Unit Data Products as Science Data

    Science.gov (United States)

    Coffey, Victoria; Minow, Joseph

    2015-01-01

    We are Co-Investigators for the Floating Potential Measurement Unit (FPMU) on the International Space Station (ISS) and members of the FPMU operations and data analysis team. We are providing this memo for the purpose of classifying raw and processed FPMU data products and ancillary data as NASA science data with unrestricted, public availability in order to best support science uses of the data.

  13. Surface characterization of hemodialysis membranes based on streaming potential measurements.

    Science.gov (United States)

    Werner, C; Jacobasch, H J; Reichelt, G

    1995-01-01

    Hemodialysis membranes made from cellulose (CUPROPHAN, HEMOPHAN) and sulfonated polyethersulfone (SPES) were characterized using the streaming potential technique to determine the zeta potential at their interfaces against well-defined aqueous solutions of varied pH and potassium chloride concentrations. Streaming potential measurements enable distinction between different membrane materials. In addition to parameters of the electrochemical double layer at membrane interfaces, thermodynamic characteristics of adsorption of different solved species were evaluated. For that aim a description of double layer formation as suggested by Börner and Jacobasch (in: Electrokinetic Phenomena, p. 231. Institut für Technologie der Polymere, Dresden (1989)) was applied which is based on the generally accepted model of the electrochemical double layer according to Stern (Z. Elektrochemie 30, 508 (1924)) and Grahame (Chem. Rev. 41, 441 (1947)). The membranes investigated show different surface acidic/basic and polar/nonpolar behavior. Furthermore, alterations of membrane interfaces through adsorption processes of components of biologically relevant solutions were shown to be detectable by streaming potential measurements.

  14. Spatial gradients of GCR protons in the inner heliosphere derived from Ulysses COSPIN/KET and PAMELA measurements

    Science.gov (United States)

    Gieseler, J.; Heber, B.

    2016-05-01

    Context. During the transition from solar cycle 23 to 24 from 2006 to 2009, the Sun was in an unusual solar minimum with very low activity over a long period. These exceptional conditions included a very low interplanetary magnetic field (IMF) strength and a high tilt angle, which both play an important role in the modulation of galactic cosmic rays (GCR) in the heliosphere. Thus, the radial and latitudinal gradients of GCRs are very much expected to depend not only on the solar magnetic epoch, but also on the overall modulation level. Aims: We determine the non-local radial and the latitudinal gradients of protons in the rigidity range from ~0.45 to 2 GV. Methods: This was accomplished by using data from the satellite-borne experiment Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) at Earth and the Kiel Electron Telescope (KET) onboard Ulysses on its highly inclined Keplerian orbit around the Sun with the aphelion at Jupiter's orbit. Results: In comparison to the previous A> 0 solar magnetic epoch, we find that the absolute value of the latitudinal gradient is lower at higher and higher at lower rigidities. This energy dependence is therefore a crucial test for models that describe the cosmic ray transport in the inner heliosphere.

  15. A healthy lifestyle composite measure: Significance and potential uses.

    Science.gov (United States)

    Adams, Mary L; Katz, David L; Shenson, Douglas

    2016-03-01

    Our objective was to create and explore potential uses of a composite "Healthy Lifestyle" measure based on Healthy People 2020 (HP2020) Objectives for behaviors shown to be associated with morbidity and mortality. Data were from the 2013 Behavioral Risk Factor Surveillance System (N=412,942) on five modifiable behaviors with HP2020 Objectives (leisure time exercise, eating fruits and vegetables 5 or more times/day, getting ≥7h of sleep/24h, not smoking and not drinking excessively). These indicators were combined to form an all-or-none composite Healthy Lifestyle (HLS) measure. Associations between the HLS measure and demographic and other measures, plus details of component measures, were reported. Results indicated that only 7.7% of adults reported a HLS with wide variation among states and demographic groups. Both unadjusted and logistic regression results found associations between a HLS and better health, lower rates of chronic disease and better access to health care. Over one fourth of all respondents (28.0%) needed to only improve fruit and vegetable consumption to be practicing a HLS. In conclusion, few adults were practicing five behaviors that are generally recognized as healthy. All-or-none metrics like this HLS measure offer a fresh perspective on modifiable behaviors and the need for improvement. Examination of measure components can help explain demographic differences and identify strategies for improvement. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Potential environmental effects of energy conservation measures in northwest industries

    Energy Technology Data Exchange (ETDEWEB)

    Baechler, M C; Gygi, K F; Hendrickson, P L

    1992-01-01

    The Bonneville Power Administration (Bonneville) has identified 101 plants in the Pacific Northwest that account for 80% of the region's industrial electricity consumption. These plants offer a precise target for a conservation program. PNL determined that most of these 101 plants were represented by 11 major industries. We then reviewed 36 major conservation technologies used in these 11 industrial settings to determine their potential environmental impacts. Energy efficiency technologies designed for industrial use may result in direct or indirect environmental impacts. Effects may result from the production of the conservation measure technology, changes in the working environment due to different energy and material requirements, or changes to waste streams. Industry type, work-place conditions, worker training, and environmental conditions inside and outside the plant are all key variables that may affect environmental outcomes. To address these issues this report has three objectives: Describe potential conservation measures that Bonneville may employ in industrial programs and discuss potential primary impacts. Characterize industrial systems and processes where the measure may be employed and describe general environmental issues associated with each industry type. Review environmental permitting, licensing, and other regulatory actions required for industries and summarize the type of information available from these sources for further analysis.

  17. Electrochemical corrosion potential and noise measurement in high temperature water

    International Nuclear Information System (INIS)

    Fong, Clinton; Chen, Yaw-Ming; Chu, Fang; Huang, Chia-Shen

    2000-01-01

    Hydrogen water chemistry (HWC) is one of the most important methods in boiling water reactor(BWR) system to mitigate and prevent stress corrosion cracking (SCC) problems of stainless steel components. Currently, the effectiveness of HWC in each BWR is mainly evaluated by the measurement of electrochemical corrosion potentials (ECP) and on-line monitoring of SCC behaviors of stainless steels. The objective of this work was to evaluate the characteristics and performance of commercially available high temperature reference electrodes. In addition, SCC monitoring technique based on electrochemical noise analysis (ECN) was also tested to examine its crack detection capability. The experimental work on electrochemical corrosion potential (ECP) measurements reveals that high temperature external Ag/AgCl reference electrode of highly dilute KCl electrolyte can adequately function in both NWC and HWC environments. The high dilution external Ag/AgCl electrode can work in conjunction with internal Ag/AgCl reference electrode, and Pt electrode to ensure the ECP measurement reliability. In simulated BWR environment, the electrochemical noise tests of SCC were carried out with both actively and passively loaded specimens of type 304 stainless steel with various electrode arrangements. From the coupling current and corrosion potential behaviors of the passive loading tests during immersion test, it is difficult to interpret the general state of stress corrosion cracking based on the analytical results of overall current and potential variations, local pulse patterns, statistical characteristics, or power spectral density of electrochemical noise signals. However, more positive SCC indication was observed in the power spectral density analysis. For aqueous environments of high solution impedance, successful application of electrochemical noise technique for SCC monitoring may require further improvement in specimen designs and analytical methods to enhance detection sensitivity

  18. Rocket potential measurements during electron beam injection into the ionosphere

    International Nuclear Information System (INIS)

    Gringauz, K.I.; Shutte, N.M.

    1981-01-01

    Electron flux measurements were made during pulsed injection of electron beams at a current of about 0.5 A and energy of 15 or 27 keV, using a retarding potential analyzer which was mounted on the lateral surface of the Eridan rocket during the ARAKS experiment of January 26, 1975. The general character of the retardation curves was found to be the same regardless of the electron injection energy, and regardless of the fact whether the plasma generator, injecting quasineutral cesium plasma with an ion current of about 10 A, was switched on. A sharp current increase in the interval between 10 to the -7th and 10 to the -6th A was observed with a decrease of the retarding potential. The rocket potential did not exceed approximately 150 V at about 130 to 190 km, and decreased to 20 V near 100 km. This was explained by the formation of a highly conducting region near the rocket, which was formed via intense plasma waves generated by the beam. Measurements of electron fluxes with energies of 1 to 3 keV agree well with estimates based on the beam plasma discharge theory

  19. Significant geographic gradients in particulate sulfate over Japan determined from multiple-site measurements and a chemical transport model: Impacts of transboundary pollution from the Asian continent

    Science.gov (United States)

    Aikawa, Masahide; Ohara, Toshimasa; Hiraki, Takatoshi; Oishi, Okihiro; Tsuji, Akihiro; Yamagami, Makiko; Murano, Kentaro; Mukai, Hitoshi

    2010-01-01

    We found a significant geographic gradient (longitudinal and latitudinal) in the sulfate (SO 42-) concentrations measured at multiple sites over the East Asian Pacific Rim region. Furthermore, the observed gradient was well reproduced by a regional chemical transport model. The observed and modeled SO 42- concentrations were higher at the sites closer to the Asian continent. The concentrations of SO 42- from China as calculated by the model also showed the fundamental features of the longitudinal/latitudinal gradient. The proportional contribution of Chinese SO 42- to the total in Japan throughout the year was above 50-70% in the control case, using data for Chinese sulfur dioxide (SO 2) emission from the Regional Emission Inventory in Asia (40-60% in the low Chinese emissions case, using Chinese SO 2 emissions data from the State Environmental Protection Administration of China), with a winter maximum of approximately 65-80%, although the actual concentrations of SO 42- from China were highest in summer. The multiple-site measurements and the model analysis strongly suggest that the SO 42- concentrations in Japan were influenced by the outflow from the Asian continent, and this influence was greatest in the areas closer to the Asian continent. In contrast, we found no longitudinal/latitudinal gradient in SO 2 concentrations; instead SO 2 concentrations were significantly correlated with local SO 2 emissions. Our results show that large amounts of particulate sulfate are transported over long distances from the East Asian Pacific Rim region, and consequently the SO 42- concentrations in Japan are controlled by the transboundary outflow from the Asian continent.

  20. Measurements of the potential ozone production rate in a forest

    Science.gov (United States)

    Crilley, L.; Sklaveniti, S.; Kramer, L.; Bloss, W.; Flynn, J. H., III; Alvarez, S. L.; Erickson, M.; Dusanter, S.; Locoge, N.; Stevens, P. S.; Millet, D. B.; Alwe, H. D.

    2017-12-01

    Biogenic volatile organic compounds (BVOC) are a significant source of organic compounds globally and alongside NOx play a key role in the formation of ozone in the troposphere. Understanding how changes in NOx concentrations feed through to altered ozone production in BVOC dominated environments will aid our understanding of future atmospheric composition, notably as developing nations transition from NOx dominated to NOx limited chemistry as a result of mitigation strategies. Here we empirically investigate this ambient ozone formation potential. We report deployment of a custom built instrument to measure in near real time the potential for in situ chemical ozone production, using an artificial light source. Our results are thus indicative of the ozone formation potential for a sampled ambient air mixture, including full VOC complexity, i.e. independent of characterization of individual organic compounds. Ground level measurements were performed as part of the PROPHET-AMOS 2016 field campaign, at a site located within a Northern Michigan forest that has typically low NOx abundance, but high isoprene and terpenoid loadings. As the ambient NOx concentrations were low during the campaign, experiments were performed in which NO was artificially added to the sampled ambient air mixture, to quantify changes in the potential ozone production rate as a function of NOx, and hence the ozone forming characteristics of the ambient air. Preliminarily results from these experiments are presented, and indicate that while ozone production increases with added NO, significant variation was observed for a given NO addition, reflecting differences in the ambient VOC chemical reactivity and ozone formation tendency.

  1. Measurement of Spectral Functions of Ultracold Atoms in Disordered Potentials

    Science.gov (United States)

    Volchkov, Valentin V.; Pasek, Michael; Denechaud, Vincent; Mukhtar, Musawwadah; Aspect, Alain; Delande, Dominique; Josse, Vincent

    2018-02-01

    We report on the measurement of the spectral functions of noninteracting ultracold atoms in a three-dimensional disordered potential resulting from an optical speckle field. Varying the disorder strength by 2 orders of magnitude, we observe the crossover from the "quantum" perturbative regime of low disorder to the "classical" regime at higher disorder strength, and find an excellent agreement with numerical simulations. The method relies on the use of state-dependent disorder and the controlled transfer of atoms to create well-defined energy states. This opens new avenues for experimental investigations of three-dimensional Anderson localization.

  2. Dry deposition of O3 and SO2 estimated from gradient measurements above a temperate mixed forest.

    Science.gov (United States)

    Wu, Zhiyong; Staebler, Ralf; Vet, Robert; Zhang, Leiming

    2016-03-01

    Vertical profiles of O3 and SO2 concentrations were monitored at the Borden Forest site in southern Ontario, Canada from May 2008 to April 2013. A modified gradient method (MGM) was applied to estimate O3 and SO2 dry deposition fluxes using concentration gradients between a level above and a level below the canopy top. The calculated five-year mean (median) dry deposition velocity (Vd) were 0.35 (0.27) and 0.59 (0.54) cm s(-1), respectively, for O3 and SO2. Vd(O3) exhibited large seasonal variations with the highest monthly mean of 0.68 cm s(-1) in August and the lowest of 0.09 cm s(-1) in February. In contrast, seasonal variations of Vd(SO2) were smaller with monthly means ranging from 0.48 (May) to 0.81 cm s(-1) (December). The different seasonal variations between O3 and SO2 were caused by the enhanced SO2 uptake by snow surfaces in winter. Diurnal variations showed a peak value of Vd in early morning in summer months for both O3 and SO2. Canopy wetness increased the non-stomatal uptake of O3 while decreasing the stomatal uptake. This also applied to SO2, but additional factors such as surface acidity also played an important role on the overall uptake. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  3. Direct measurement of the plasma potential in the edge of ASDEX Upgrade using a self emitting probe

    International Nuclear Information System (INIS)

    Rohde, V.; Laux, M.; Bachmann, P.; Herrmann, A.; Weinlich, M.

    1997-01-01

    In this paper we present first measurements of the plasma potential close to the separatrix in ASDEX Upgrade using a self emitting tip. The probe was inserted into the edge plasma of AUG using the midplane manipulator. Assuming Maxwellian plasmas, the observations agree with the predicted voltage drop in the plasma sheath, V pl ps -V fl =2.5T e , where V pl ps is the plasma potential at the presheath boundary and V fl the floating potential. Applying this technique a rapid change of the plasma potential was observed close to the separatrix during Ohmic discharges. From the gradient we derive a radial electric field E r of about -5 kV/m close to separatrix. Further out the field strength changes sign and we find up to +7 kV/m in the SOL. (orig.)

  4. Lean Principles’Potential Measurement Framework for Service Organization

    Directory of Open Access Journals (Sweden)

    M. D. Vadhvani

    2016-06-01

    Full Text Available Role of service sector can be considered vital as these industries are accountable for accelerating the major functions of the secondary organizations. Hence it is a very important element of economy in enhancing competitive dimensions- quality, flexibility, cost and delivery. Improvement initiatives such as Total Quality Management, Lean Practices, and Leansigma focus on increasing the competitive dimensions. Among these Lean Practices are having the inherent principles of reducing the cost and increasing the quality by focusing the non value added activities from the value chain of the service or product. Lean Principles (LPs are being practiced since long by the organizations of secondary sectors and followed by that of the tertiary sectors. Albeit the reported improvement achieved are limited by the drawbacks such as lack of proper set of guidelines, partial features of measurable characteristics, lack of guideline for measurement. Present work proposes a measurement frame work with aids of flowchart and questionnaire for measuring the potential of LPs in service organization which help them to take accompanying initiatives to implement the LPs.

  5. Online monitoring of Mezcal fermentation based on redox potential measurements.

    Science.gov (United States)

    Escalante-Minakata, P; Ibarra-Junquera, V; Rosu, H C; De León-Rodríguez, A; González-García, R

    2009-01-01

    We describe an algorithm for the continuous monitoring of the biomass and ethanol concentrations as well as the growth rate in the Mezcal fermentation process. The algorithm performs its task having available only the online measurements of the redox potential. The procedure combines an artificial neural network (ANN) that relates the redox potential to the ethanol and biomass concentrations with a nonlinear observer-based algorithm that uses the ANN biomass estimations to infer the growth rate of this fermentation process. The results show that the redox potential is a valuable indicator of the metabolic activity of the microorganisms during Mezcal fermentation. In addition, the estimated growth rate can be considered as a direct evidence of the presence of mixed culture growth in the process. Usually, mixtures of microorganisms could be intuitively clear in this kind of processes; however, the total biomass data do not provide definite evidence by themselves. In this paper, the detailed design of the software sensor as well as its experimental application is presented at the laboratory level.

  6. Measurements of the sheath potential in low density plasmas

    International Nuclear Information System (INIS)

    Bradley, J.W.; Khamis, R.A.; Sanduk, M.I.; Elliott, J.A.; Rusbridge, M.G.

    1992-01-01

    We have measured the sheath potential around a probe in a range of different plasma conditions in the UMIST, University of Manchester Institute of Science and Technology, quadrupole GOLUX and in a related experiment in which the plasma expands freely to supersonic velocity. In the latter case, the sheath potential agrees well with an appropriately modified form of the usual expression for a field-free plasma, for both hydrogen and argon plasmas. In GOLUX, however, the sheath potential is found to be significantly less than the accepted value, even when the magnetic field is taken into account. For the slow moving plasma in the outer part of the quadrupole confining field, we present both theoretical and experimental results showing that the reduction is due to truncation of the electron velocity distribution as the probe drains electrons from a closed flux tube faster than they can be replaced. In the central hot plasma, however, this explanation cannot apply. Here, the plasma is moving at about sonic speed and magnetic effects are weak. Nevertheless, the results are significantly different from both in the field free experiment. (author)

  7. Irradiance gradients

    International Nuclear Information System (INIS)

    Ward, G.J.; Heckbert, P.S.; Technische Hogeschool Delft

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques

  8. Co-occurrence patterns of trees along macro-climatic gradients and their potential influence on the present and future distribution of Fagus sylvatica L.

    Science.gov (United States)

    Meier, E.S.; Edwards, T.C.; Kienast, Felix; Dobbertin, M.; Zimmermann, N.E.

    2011-01-01

    Aim During recent and future climate change, shifts in large-scale species ranges are expected due to the hypothesized major role of climatic factors in regulating species distributions. The stress-gradient hypothesis suggests that biotic interactions may act as major constraints on species distributions under more favourable growing conditions, while climatic constraints may dominate under unfavourable conditions. We tested this hypothesis for one focal tree species having three major competitors using broad-scale environmental data. We evaluated the variation of species co-occurrence patterns in climate space and estimated the influence of these patterns on the distribution of the focal species for current and projected future climates.Location Europe.Methods We used ICP Forest Level 1 data as well as climatic, topographic and edaphic variables. First, correlations between the relative abundance of European beech (Fagus sylvatica) and three major competitor species (Picea abies, Pinus sylvestris and Quercus robur) were analysed in environmental space, and then projected to geographic space. Second, a sensitivity analysis was performed using generalized additive models (GAM) to evaluate where and how much the predicted F. sylvatica distribution varied under current and future climates if potential competitor species were included or excluded. We evaluated if these areas coincide with current species co-occurrence patterns.Results Correlation analyses supported the stress-gradient hypothesis: towards favourable growing conditions of F. sylvatica, its abundance was strongly linked to the abundance of its competitors, while this link weakened towards unfavourable growing conditions, with stronger correlations in the south and at low elevations than in the north and at high elevations. The sensitivity analysis showed a potential spatial segregation of species with changing climate and a pronounced shift of zones where co-occurrence patterns may play a major role

  9. Control of electron transfer in the cytochrome system of mitochondria by pH, transmembrane pH gradient and electrical potential. The cytochromes b-c segment.

    Science.gov (United States)

    Papa, S; Lorusso, M; Izzo, G; Capuano, F

    1981-02-15

    1. A study is presented of the effects of pH, transmembrane pH gradient and electrical potential on oxidoreductions of b and c cytochromes in ox heart mitochondria and 'inside-out' submitochondrial particles. 2. Kinetic analysis shows that, in mitochondria at neutral pH, there is a restraint on the aerobic oxidation of cytochrome b566 with respect to cytochrome b562. Valinomycin plus K+ accelerates cytochrome b566 oxidation and retards net oxidation of cytochrome b562. At alkaline pH the rate of cytochrome b566 oxidation approaches that of cytochrome b562 and the effects of valinomycin on b cytochromes are impaired. 3. At slightly acidic pH, oxygenation of antimycin-supplemented mitochondria causes rapid reduction of cytochrome b566 and small delayed reduction of cytochrome b562. Valinomycin or a pH increase in the medium promote reduction of cytochrome b562 and decrease net reduction of cytochrome b566. 4. Addition of valinomycin to mitochondria and submitochondrial particles in the respiring steady state causes, at pH values around neutrality, preferential oxidation of cytochrome b566 with respect to cytochrome b562. The differential effect of valinomycin on oxidation of cytochromes b566 and b562 is enhanced by substitution of 1H2O of the medium with 2H2O and tends to disappear as the pH of the medium is raised to alkaline values. 5. Nigericin addition in the aerobic steady state causes, both in mitochondria and submitochondrial particles, preferential oxidation of cytochrome b562 with respect to cytochrome b566. This is accompanied by c cytochrome oxidation in mitochondria but c cytochrome reduction in submitochondrial particles. 6. In mitochondria as well as in submitochondrial particles, the aerobic transmembrane potential (delta psi) does not change by raising the pH of the external medium from neutrality to alkalinity. The transmembrane pH gradient (delta pH) on the other hand, decrease slightly. 7. The results presented provide evidence that the delta psi

  10. Measurement of the first ionization potential of lawrencium, element 103.

    Science.gov (United States)

    Sato, T K; Asai, M; Borschevsky, A; Stora, T; Sato, N; Kaneya, Y; Tsukada, K; Düllmann, Ch E; Eberhardt, K; Eliav, E; Ichikawa, S; Kaldor, U; Kratz, J V; Miyashita, S; Nagame, Y; Ooe, K; Osa, A; Renisch, D; Runke, J; Schädel, M; Thörle-Pospiech, P; Toyoshima, A; Trautmann, N

    2015-04-09

    The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row--including the actinides--even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by the difficulty in obtaining the heaviest elements on scales of more than one atom at a time. Here we report that the experimentally obtained IP1 of the heaviest actinide, lawrencium (Lr, atomic number 103), is 4.96(+0.08)(-0.07) electronvolts. The IP1 of Lr was measured with (256)Lr (half-life 27 seconds) using an efficient surface ion-source and a radioisotope detection system coupled to a mass separator. The measured IP1 is in excellent agreement with the value of 4.963(15) electronvolts predicted here by state-of-the-art relativistic calculations. The present work provides a reliable benchmark for theoretical calculations and also opens the way for IP1 measurements of superheavy elements (that is, transactinides) on an atom-at-a-time scale.

  11. Fluid-flow measurements in low permeability media with high pressure gradients using neutron imaging: Application to concrete

    Science.gov (United States)

    Yehya, Mohamad; Andò, Edward; Dufour, Frédéric; Tengattini, Alessandro

    2018-05-01

    This article focuses on a new experimental apparatus for investigating fluid flow under high pressure gradients within low-permeability porous media by means of neutron imaging. A titanium Hassler cell which optimises neutron transparency while allowing high pressure confinement (up to 50 MPa) and injection is designed for this purpose and presented here. This contribution focuses on the development of the proposed methodology thanks to some preliminary results obtained using a new neutron imaging facility named NeXT on the D50 beamline at the Institute Laue Langevin (Grenoble). The preliminary test was conducted by injecting normal water into concrete sample prepared and saturated with heavy water to take advantage of the isotope sensitivity of neutrons. The front between these two types of water is tracked in space and time with a combination of neutron radiography and tomography.

  12. Influence of the external conditions on salt retention and pressure-induced electrical potential measured across a composite membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1999-01-01

    Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence on these paramet......Transport on single electrolyte solutions (NaCl and MgCl2) due to pressure gradients across a commercial reverse osmosis membrane was studied by measuring volume flux (J(v)), salt rejection (S) and pressure induced electrical potential (Delta E) in a crossflow cell. The influence......, r = 1, 0.5 and 0.1), respectively. Results show that J(v), S and Delta E values slightly increase when the velocity of the feed solution increases, but the mixed electrolytes strongly affect both salt rejection and pressure-induced electrical potential. A change in the sign of both parameters...... with respect to the value determined with single electrolytes at the same concentration was obtained, which is attributed to a strong coupling among the fluxes of individual ions and their distribution in the membrane when transport of mixed salt is studied. (C) 1999 Elsevier Science B.V. All rights reserved....

  13. Junction Potentials Bias Measurements of Ion Exchange Membrane Permselectivity.

    Science.gov (United States)

    Kingsbury, Ryan S; Flotron, Sophie; Zhu, Shan; Call, Douglas F; Coronell, Orlando

    2018-04-17

    Ion exchange membranes (IEMs) are versatile materials relevant to a variety of water and waste treatment, energy production, and industrial separation processes. The defining characteristic of IEMs is their ability to selectively allow positive or negative ions to permeate, which is referred to as permselectivity. Measured values of permselectivity that equal unity (corresponding to a perfectly selective membrane) or exceed unity (theoretically impossible) have been reported for cation exchange membranes (CEMs). Such nonphysical results call into question our ability to correctly measure this crucial membrane property. Because weighing errors, temperature, and measurement uncertainty have been shown to not explain these anomalous permselectivity results, we hypothesized that a possible explanation are junction potentials that occur at the tips of reference electrodes. In this work, we tested this hypothesis by comparing permselectivity values obtained from bare Ag/AgCl wire electrodes (which have no junction) to values obtained from single-junction reference electrodes containing two different electrolytes. We show that permselectivity values obtained using reference electrodes with junctions were greater than unity for CEMs. In contrast, electrodes without junctions always produced permselectivities lower than unity. Electrodes with junctions also resulted in artificially low permselectivity values for AEMs compared to electrodes without junctions. Thus, we conclude that junctions in reference electrodes introduce two biases into results in the IEM literature: (i) permselectivity values larger than unity for CEMs and (ii) lower permselectivity values for AEMs compared to those for CEMs. These biases can be avoided by using electrodes without a junction.

  14. Manipulating the Gradient

    Science.gov (United States)

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  15. Helicon plasma potential measurements using a heavy ion beam probe

    International Nuclear Information System (INIS)

    P. Schoch; K. Connor; J. Si

    2005-01-01

    A Heavy Ion Beam Probe, HIBP, has been installed on a helicon plasma device. The objective was to measure plasma fluctuations at the 13.55MHz RF frequency. This offers a unique challenge for the HIBP, because the transit time of the probing ion is long compared to the fluctuations of interest. For previous HIBPs, the transit time has been short compared to the period of the fluctuations which permits one to assume that the magnetic and electric fields are static. Modeling has shown that the diagnostic will still accurately measure the average potential. The fluctuating potential was to be detected but the absolute magnitude is difficult to determine with signal from a single point. However, modeling indicates multipoint measurements will allow one to resolve the absolute fluctuation magnitude. Work supported by DOE Grant No. DE-FG02-99ER5452985 During the funding of this grant, a helicon plasma discharge device was built and operated. A Heavy Ion Beam Probe primary system was installed and operated. A primary beam detector was installed and primary beam was detected both with and without plasma. Attempts were made to detect secondary ions using the primary beam detector, without success. Given the lack of a detectable signal, the energy analyzer of the HIBP system was never installed. It is available for installation if there is a reason to do so in the future. Analysis of the system indicated that the plasma electron temperature, estimated to be a few eV, was the likely reason for the lack of detectable secondary ions. A change of ion species to either Boron or Magnesium would greatly increase the signal, but neither of these ions have been used in a HIBP system. The ion source used in this system is made by using a charge exchange process to create a zeolite loaded with the desired ion. Attempts were made to use charge exchange to load Magnesium into a zeolite, and were not successful. It is felt that Magnesium and/or Boron zeolite sources could be created, but

  16. Numerical simulation of kinetic demixing and decomposition in a LaCoO3-δ oxygen membrane under an oxygen potential gradient

    DEFF Research Database (Denmark)

    Ta, Na; Chen, Ming; Zhang, Lijun

    2018-01-01

    A composition- and temperature-dependent mobility database of all ionic species in the LaCoO3-δ phase was developed and combined with a La-Co-O thermodynamic database to simulate kinetic demixing and partial decomposition in LaCoO3-δ oxygen membranes operated under a 0.0001/0.21 bar oxygen partial...... pressure difference at 1073 K for 1 year. Formation of La2O3, Co3O4 and CoO phases across the membrane is predicted. The kinetic demixing process can be divided into two stages, namely, establishment of the oxygen potential gradient (fast) and demixing of the cations (slow); the former is controlled...... by the mobility of oxygen ions, and the latter is determined by the higher mobility of Co ions as compared to the La ion in the ABO3-type perovskite. A drift motion of both oxide surfaces towards the high PO2 side occurs with the movement of cations....

  17. Gradient pattern analysis applied to galaxy morphology

    Science.gov (United States)

    Rosa, R. R.; de Carvalho, R. R.; Sautter, R. A.; Barchi, P. H.; Stalder, D. H.; Moura, T. C.; Rembold, S. B.; Morell, D. R. F.; Ferreira, N. C.

    2018-06-01

    Gradient pattern analysis (GPA) is a well-established technique for measuring gradient bilateral asymmetries of a square numerical lattice. This paper introduces an improved version of GPA designed for galaxy morphometry. We show the performance of the new method on a selected sample of 54 896 objects from the SDSS-DR7 in common with Galaxy Zoo 1 catalogue. The results suggest that the second gradient moment, G2, has the potential to dramatically improve over more conventional morphometric parameters. It separates early- from late-type galaxies better (˜ 90 per cent) than the CAS system (C˜ 79 per cent, A˜ 50 per cent, S˜ 43 per cent) and a benchmark test shows that it is applicable to hundreds of thousands of galaxies using typical processing systems.

  18. Measurement of electric field gradient at {sup 117}In on the Cu-site in mavicyanin by perturbed angular correlation of {gamma}-rays

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, A., E-mail: yokoyama@cacheibm.s.kanazawa-u.ac.jp; Hashimoto, T.; Ihara, K.; Kikunaga, H.; Kinoshita, N.; Yamazaki, I.; Kataoka, K.; Yanase, M.; Takata, M. [Kanazawa University, Faculty of Science and Graduate School of Natural Science and Technology (Japan); Murakami, Y.; Takamiya, K.; Tanigaki, M.; Ohkubo, Y. [Kyoto University, Research Reactor Institute (Japan)

    2008-01-15

    The structure around the metal site of mavicyanin, a protein molecule with a copper site, was investigated in solution by using time-differential perturbed angular correlation of {sup 117}In. The electric field gradient (EFG) of the metal site was deduced from the measurement. It demonstrated that the site in a mutant-type mavicyanin, Thr15Ala-Mav, gives an EFG different from that in the wild-type mavicyanin does. The pH dependence of the EFG was also observed for both proteins.

  19. Nonlinear Growth Models as Measurement Models: A Second-Order Growth Curve Model for Measuring Potential.

    Science.gov (United States)

    McNeish, Daniel; Dumas, Denis

    2017-01-01

    Recent methodological work has highlighted the promise of nonlinear growth models for addressing substantive questions in the behavioral sciences. In this article, we outline a second-order nonlinear growth model in order to measure a critical notion in development and education: potential. Here, potential is conceptualized as having three components-ability, capacity, and availability-where ability is the amount of skill a student is estimated to have at a given timepoint, capacity is the maximum amount of ability a student is predicted to be able to develop asymptotically, and availability is the difference between capacity and ability at any particular timepoint. We argue that single timepoint measures are typically insufficient for discerning information about potential, and we therefore describe a general framework that incorporates a growth model into the measurement model to capture these three components. Then, we provide an illustrative example using the public-use Early Childhood Longitudinal Study-Kindergarten data set using a Michaelis-Menten growth function (reparameterized from its common application in biochemistry) to demonstrate our proposed model as applied to measuring potential within an educational context. The advantage of this approach compared to currently utilized methods is discussed as are future directions and limitations.

  20. Noncontact measurement of electrostatic fields: Verification of modeled potentials within ion mobility spectrometer drift tube designs

    International Nuclear Information System (INIS)

    Scott, Jill R.; Tremblay, Paul L.

    2007-01-01

    The heart of an ion mobility spectrometer is the drift region where ion separation occurs. While the electrostatic potentials within a drift tube design can be modeled, no method for independently validating the electrostatic field has previously been reported. Two basic drift tube designs were modeled using SIMION 7.0 to reveal the expected electrostatic fields: (1) A traditional alternating set of electrodes and insulators and (2) a truly linear drift tube. One version of the alternating electrode/insulator drift tube and two versions of linear drift tubes were then fabricated. The stacked alternating electrodes/insulators were connected through a resistor network to generate the electrostatic gradient in the drift tube. The two linear drift tube designs consisted of two types of resistive drift tubes with one tube consisting of a resistive coating within an insulating tube and the other tube composed of resistive ferrites. The electrostatic fields within each type of drift tube were then evaluated by a noncontact method using a Kelvin-Zisman type electrostatic voltmeter and probe (results for alternative measurement methods provided in supplementary material). The experimental results were then compared with the electrostatic fields predicted by SIMION. Both the modeling and experimental measurements reveal that the electrostatic fields within a stacked ion mobility spectrometer drift tube are only pseudo-linear, while the electrostatic fields within a resistive drift tube approach perfect linearity

  1. Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Volfbeyn, P.; Bekefi, G. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-12-31

    We report the results of temporal and spatial measurements of phase of a pulsed free electron laser amplifier (FEL) operating in combined wiggler and axial guide magnetic fields. The 33 GHz FEL is driven by a mildly relativistic electron beam (750 kV, 90-300 A, 30 ns) and generates 61 MW of radiation with a high power magnetron as the input source. The phase is measured by an interferometric technique from which frequency shifting is determined. The results are simulated with a computer code. Experimental studies on a CERN-CLIC 32.98 GHz 26-cell high gradient accelerating section (HGA) were carried out for input powers from 0.1 MW to 35 MW. The FEL served as the r.f. power source for the HGA. The maximum power in the transmitted pulse was measured to be 15 MW for an input pulse of 35 MW. The theoretically calculated shunt impedance of 116 M{Omega}/m predicts a field gradient of 65 MeV/m inside the HGA. For power levels >3MW the pulse transmitted through the HGA was observed to be shorter than the input pulse and pulse shortening became more serious with increasing power input. At the highest power levels the output pulse length (about 5 nsec) was about one quarter of the input pulse length. Various tests suggest that these undesirable effects occur in the input coupler to the HGA. Light and X-ray production inside the HGA have been observed.

  2. Development of a potential screening measure for adolescent depression.

    Science.gov (United States)

    Taouk, Mona; Meiser, Bettina; Hadzi-Pavlovic, Dusan; Dudley, Michael; Mitchell, Philip B

    2017-06-01

    Few adolescent-specific depression screening instruments have been developed in recent years using multi-method approaches (qualitative and quantitative), and some of those available have limitations with an adolescent audience. We describe the development of a potential measure - the Taouk Scale for Adolescent Depression. Draft items were informed by findings from focus groups and reviews by adolescents and healthcare professionals, resulting in a provisional 97-item scale. This was administered to a nation-wide sample of 3087 secondary students. Exploratory factor analysis was used in a development subset to examine dimensionality of items and reduce their number, with the final item set evaluated in a validation subset. Four reliable factors - negative outlook, emotional distress, behavioural changes and cognitive and somatic disturbances - were obtained from the exploratory factor analysis, resulting in a 28-item instrument, which was corroborated by confirmatory factor analysis. The final scale includes a number of novel items not included in current measures, i.e., whether respondents wear more black clothing than usual, deliberately damage property, take more risks, 'space out' at school and are engaged in substance abuse and/or increased sexual activity. The Taouk Scale for Adolescent Depression demonstrated sound psychometric properties and may have utility for future screening and future epidemiological purposes. It appears to be a valid and reliable screening instrument for adolescent depression that includes a number of novel items. Further research is necessary to confirm its criterion validity in clinically depressed samples.

  3. Measurement of the first ionization potential of lawrencium (element 103)

    CERN Document Server

    Sato, T K; Borschevsky, A; Stora, T; Sato, N; Kaneya, Y; Tsukada, K; Düllmann, Ch E; Eberhardt, K; Eliav, E; Ichikawa, S; Kaldor, U; Kratz, J V; Miyashita, S; Nagame, Y; Ooe, K; Osa, A; Renisch, D; Runke, J; Schädel, M; Thörle-Pospiech, P; Toyoshima, A; Trautmann, N

    2015-01-01

    The chemical properties of an element are primarily governed by the configuration of electrons in the valence shell. Relativistic effects influence the electronic structure of heavy elements in the sixth row of the periodic table, and these effects increase dramatically in the seventh row—including the actinides—even affecting ground-state configurations. Atomic s and p1/2 orbitals are stabilized by relativistic effects, whereas p3/2, d and f orbitals are destabilized, so that ground-state configurations of heavy elements may differ from those of lighter elements in the same group. The first ionization potential (IP1) is a measure of the energy required to remove one valence electron from a neutral atom, and is an atomic property that reflects the outermost electronic configuration. Precise and accurate experimental determination of IP1 gives information on the binding energy of valence electrons, and also, therefore, on the degree of relativistic stabilization. However, such measurements are hampered by ...

  4. Defining Tsunami Magnitude as Measure of Potential Impact

    Science.gov (United States)

    Titov, V. V.; Tang, L.

    2016-12-01

    The goal of tsunami forecast, as a system for predicting potential impact of a tsunami at coastlines, requires quick estimate of a tsunami magnitude. This goal has been recognized since the beginning of tsunami research. The work of Kajiura, Soloviev, Abe, Murty, and many others discussed several scales for tsunami magnitude based on estimates of tsunami energy. However, difficulties of estimating tsunami energy based on available tsunami measurements at coastal sea-level stations has carried significant uncertainties and has been virtually impossible in real time, before tsunami impacts coastlines. The slow process of tsunami magnitude estimates, including collection of vast amount of available coastal sea-level data from affected coastlines, made it impractical to use any tsunami magnitude scales in tsunami warning operations. Uncertainties of estimates made tsunami magnitudes difficult to use as universal scale for tsunami analysis. Historically, the earthquake magnitude has been used as a proxy of tsunami impact estimates, since real-time seismic data is available of real-time processing and ample amount of seismic data is available for an elaborate post event analysis. This measure of tsunami impact carries significant uncertainties in quantitative tsunami impact estimates, since the relation between the earthquake and generated tsunami energy varies from case to case. In this work, we argue that current tsunami measurement capabilities and real-time modeling tools allow for establishing robust tsunami magnitude that will be useful for tsunami warning as a quick estimate for tsunami impact and for post-event analysis as a universal scale for tsunamis inter-comparison. We present a method for estimating the tsunami magnitude based on tsunami energy and present application of the magnitude analysis for several historical events for inter-comparison with existing methods.

  5. New diffusive gradients in a thin film technique for measuring inorganic arsenic and selenium(IV) using a titanium dioxide based adsorbent

    DEFF Research Database (Denmark)

    Bennett, William W.; Teasdale, Peter R.; Panther, Jared G.

    2010-01-01

    A new diffusive gradients in a thin film (DGT) technique, using a titanium dioxide based adsorbent (Metsorb), has been developed and evaluated for the determination of dissolved inorganic arsenic and selenium. AsIII, AsV, and SeIV were found to be quantitatively accumulated by the adsorbent (uptake...... measurement of inorganic arsenic. Reproducibility of the technique in field deployments was good (relative standard deviation arsenic and 0.05 μg L-1 for SeIV. The results of this study confirmed that DGT with Metsorb was a reliable...... and robust method for the measurement of inorganic arsenic and the selective measurement of SeIV within useful limits of accuracy....

  6. Measurement of the Tracer Gradient and Sampling System Bias of the Hot Fuel Examination Facility Stack Air Monitoring System

    Energy Technology Data Exchange (ETDEWEB)

    Glissmeyer, John A.; Flaherty, Julia E.

    2011-07-20

    This report describes tracer gas uniformity and bias measurements made in the exhaust air discharge of the Hot Fuel Examination Facility at Idaho National Laboratory. The measurements were a follow-up on earlier measurements which indicated a lack of mixing of the two ventilation streams being discharged via a common stack. The lack of mixing is detrimental to the accuracy of air emission measurements. The lack of mixing was confirmed in these new measurements. The air sampling probe was found to be out of alignment and that was corrected. The suspected sampling bias in the air sample stream was disproved.

  7. Measuring significant inhomogeneity and anisotropy in indoor convective air turbulence in the presence of 2D temperature gradient

    International Nuclear Information System (INIS)

    Razi, E Mohammady; Rasouli, Saifollah

    2014-01-01

    Using a novel set up, experimental study of the statistical properties of a light beam propagating horizontally through indoor convective air turbulence in the presence of a 2D temperature gradient (TG) is presented. A laser beam enters a telescope from its back focal point by virtue of an optical fiber and is expanded and recollimated by it and then passes through the turbulent area. Then the beam enters another telescope’s aperture. A mask consisting of four similar widely separated small subapertures was installed in front of the second telescope’s aperture. The subapertures were equidistant from the optical axis of the telescope and located at the corners of a square. A flat plane heater is used to produce a vertical TG in the medium. Due to the limited width of the heater, a horizontal component for the TG appeared. Near the focal plane of the second telescope, four distinct images of the source are formed and recorded by a CCD camera. Due to the turbulence all the images (spots) in the successive frames fluctuate. Using the four spot displacements we have calculated the fluctuations of the angle of arrival (AA) over the subapertures. The statistical properties of the optical turbulence are investigated using variance analysis of the AA component fluctuations at horizontal and vertical directions over the subapertures for different temperatures of the heater at different heights of the beam path from the heater. Experimental results show that when the heater is turned off, the variances of horizontal and vertical components of the AA fluctuations are approximately equal to zero over all the subapertures. When it is turned on, the variance of the horizontal component of the AA fluctuations over all of the subapertures are larger than those from the vertical one. In addition, in this case, we find a significant dependence of the variance of the AA components on the height from the heater. (paper)

  8. Crack Growth Monitoring in Harsh Environments by Electric Potential Measurements

    International Nuclear Information System (INIS)

    Lloyd, Wilson Randolph; Reuter, Walter Graham; Weinberg, David Michael

    1999-01-01

    Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique applicable is many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed

  9. Transmural recording of shock potential gradient fields, early postshock activations, and refibrillation episodes associated with external defibrillation of long-duration ventricular fibrillation in swine.

    Science.gov (United States)

    Allred, James D; Killingsworth, Cheryl R; Allison, J Scott; Dosdall, Derek J; Melnick, Sharon B; Smith, William M; Ideker, Raymond E; Walcott, Gregory P

    2008-11-01

    Knowledge of the shock potential gradient (nablaV) and postshock activation is limited to internal defibrillation of short-duration ventricular fibrillation (SDVF). The purpose of this study was to determine these variables after external defibrillation of long-duration VF (LDVF). In six pigs, 115-20 plunge needles with three to six electrodes each were inserted to record throughout both ventricles. After the chest was closed, the biphasic defibrillation threshold (DFT) was determined after 20 seconds of SDVF with external defibrillation pads. After 7 minutes of LDVF, defibrillation shocks that were less than or equal to the SDVF DFT strength were given. For DFT shocks (1632 +/- 429 V), the maximum minus minimum ventricular voltage (160 +/- 100 V) was 9.8% of the shock voltage. Maximum cardiac nablaV (28.7 +/- 17 V/cm) was 4.7 +/- 2.0 times the minimum nablaV (6.2 +/- 3.5 V/cm). Although LDVF did not increase the DFT in five of the six pigs, it significantly lengthened the time to earliest postshock activation following defibrillation (1.6 +/- 2.2 seconds for SDVF and 4.9 +/- 4.3 seconds for LDVF). After LDVF, 1.3 +/- 0.8 episodes of spontaneous refibrillation occurred per animal, but there was no refibrillation after SDVF. Compared with previous studies of internal defibrillation, during external defibrillation much less of the shock voltage appears across the heart and the shock field is much more even; however, the minimum nablaV is similar. Compared with external defibrillation of SDVF, the biphasic external DFT for LDVF is not increased; however, time to earliest postshock activation triples. Refibrillation is common after LDVF but not after SDVF in these normal hearts, indicating that LDVF by itself can cause refibrillation without requiring preexisting heart disease.

  10. Streaming Potential and Electroosmosis Measurements to Characterize Porous Materials

    NARCIS (Netherlands)

    Luong, D.T.; Sprik, R.

    2013-01-01

    Characterizing the streaming potential and electroosmosis properties of porous media is essential in applying seismoelectric and electroseismic phenomena for oil exploration. Some parameters such as porosity, permeability, formation factor, pore size, the number of pores, and the zeta potential of

  11. Monophasic action potentials and activation recovery intervals as measures of ventricular action potential duration: experimental evidence to resolve some controversies

    NARCIS (Netherlands)

    Coronel, Ruben; de Bakker, Jacques M. T.; Wilms-Schopman, Francien J. G.; Opthof, Tobias; Linnenbank, André C.; Belterman, Charly N.; Janse, Michiel J.

    2006-01-01

    BACKGROUND: Activation recovery intervals (ARIs) and monophasic action potential (MAP) duration are used as measures of action potential duration in beating hearts. However, controversies exist concerning the correct way to record MAPs or calculate ARIs. We have addressed these issues

  12. Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D.

    Science.gov (United States)

    Haskey, S R; Grierson, B A; Burrell, K H; Chrystal, C; Groebner, R J; Kaplan, D H; Pablant, N A; Stagner, L

    2016-11-01

    Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.

  13. Effects of water chemistry and potential distribution on electrochemical corrosion potential measurements in 553 K pure water

    International Nuclear Information System (INIS)

    Ishida, Kazushige; Wada, Yoichi; Tachibana, Masahiko; Ota, Nobuyuki; Aizawa, Motohiro

    2013-01-01

    The effects of water chemistry distribution on the potential of a reference electrode and of the potential distribution on the measured potential should be known qualitatively to obtain accurate electrochemical corrosion potential (ECP) data in BWRs. First, the effects of oxygen on a platinum reference electrode were studied in 553 K pure water containing dissolved hydrogen (DH) concentration of 26 - 10 5 μg kg -1 (ppb). The platinum electrode worked in the same way as the theoretical hydrogen electrode under the condition that the molar ratio of DH to dissolved oxygen (DO) was more than 10 and that DO was less than 100 ppb. Second, the effects of potential distribution on the measured potential were studied by using the ECP measurement part without platinum deposition on the surfaces connected to another ECP measurement part with platinum deposition on the surfaces in 553 K pure water containing 100 - 130 ppb of DH or 100 - 130 ppb of DH plus 400 ppb of hydrogen peroxide. Measured potentials for each ECP measurement part were in good agreement with literature data for each surface condition. The lead wire connecting point did not affect the measured potential. Potential should be measured at the nearest point from the reference electrode in which case it will be not affected by either the potential distribution or the connection point of the lead wire in pure water. (author)

  14. Cross-field gradients: general concept, importance of multi-spacecraft measurements and study at 1 AU of the source intensity gradient for E > 30 keV solar event electrons

    Directory of Open Access Journals (Sweden)

    P. A. Chaizy

    Full Text Available Three main physical processes (and associated properties are currently used to describe the flux and anisotropy time profiles of solar energetic par- ticle events, called SEP profiles. They are (1 the particle scattering (due to magnetic waves, (2 the particle focusing (due to the decrease of the amplitude of the interplanetary magnetic field (IMF with the radial distance to the Sun and (3 the finite injection profile at the source. If their features change from one field line to another, i.e. if there is a cross IMF gradient (CFG, then the shape of the SEP profiles will depend, at onset time, on the relative position of the spacecraft to the IMF and might vary significantly on small distance scale (e.g. 106 km. One type of CFG is studied here. It is called intensity CFG and considers variations, at the solar surface, only of the intensity of the event. It is shown here that drops of about two orders of magnitude over distances of ~104 km at the Sun (1° of angular distance can influence dramatically the SEP profiles at 1 AU. This CFG can lead to either an under or overestimation of both the parallel mean free path and of the injection parameters by factor up to, at least, ~2-3 and 18, respectively. Multi-spacecraft analysis can be used to identify CFG. Three basic requirements are proposed to identify, from the observation, the type of the CFG being measured.

    Key words: Solar physics, astrophysics, and astronomy (energetic particles; flares and mass ejections - Space plasma physics (transport processes

  15. Phenotypic divergence along geographic gradients reveals potential for rapid adaptation of the White-nose Syndrome pathogen, Pseudogymnoascus destructans, in North America.

    Science.gov (United States)

    Forsythe, Adrian; Giglio, Victoria; Asa, Jonathan; Xu, Jianping

    2018-06-18

    White-nose Syndrome (WNS) is an ongoing epizootic affecting multiple species of North American bats, caused by epidermal infections of the psychrophilic filamentous fungus, Pseudogymnoascus destructans Since its introduction from Europe, WNS has spread rapidly across eastern North America and resulted in high mortality rates in bats. At present, the mechanisms behind its spread and the extent of its adaptation to different geographic and ecological niches remain unknown. The objective of this study was to examine the geographic patterns of phenotypic variation and the potential evidence for adaptation among strains representing broad geographic locations in eastern North America. The morphological features of these strains were evaluated on artificial medium, and the viability of asexual arthroconidia of representative strains were investigated after storage at high (23°C), moderate (14°C), and low (4°C) temperatures at different lengths of times. Our analyses identified evidence for a geographic pattern of colony morphology changes among the clonal descendants of the fungus, with trait values correlated with increased distance from the epicenter of WNS. Our genomic comparisons of three representative isolates revealed novel genetic polymorphisms and suggested potential candidate mutations that might be related to some of the phenotypic changes. These results show that even though this pathogen arrived in North America only recently and reproduces asexually, there has been substantial evolution and phenotypic diversification during its rapid clonal expansion. Importance The causal agent of White-nose Syndrome in bats is Pseudogymnoascus destructans , a filamentous fungus recently introduced from its native range in Europe. Infections caused by P. destructans have progressed across the eastern parts of Canada and the United States over the last ten years. It is not clear how the disease is spread as the pathogen is unable to grow above 23°C and ambient

  16. Measurements of Dissipation Rate and Velocity/Pressure Gradient Correlation for Improvements to Gas Turbine Turbulent Flow Models

    National Research Council Canada - National Science Library

    Simpson, Roger L; Lowe, K. T; Orsi, Edgar

    2006-01-01

    ... Reynolds number turbulent flows. With at least 4 particles at a given instant this results in the fine-spatial-resolution instantaneous measurement of the complete rate-of-strain and vorticity tensors and the dissipative...

  17. Investigation of human body potential measured by a non-contact measuring system.

    Science.gov (United States)

    Ichikawa, Norimitsu

    2016-12-07

    A human body is occasionally electrified in a room. This charged object will be a source of electrostatic accidents, including the malfunction of electronic equipment. Hence, prevention of these accidents is required. Accidents occasionally occur, even though antistatic clothes and shoes are used. One of the causes for these accidents is that there is a lack of the preventive measures. This situation occurs when using, for example, unconductive wax. In this study, human body potential (voltage) is measured using a non-contact measuring system. An investigation of the human body's voltage when using this system is conducted. The result demonstrates that the voltage of a human body wearing antistatic clothes and shoes or light clothes and slippers exceeds a malfunctioning voltage of a microelectronics device when the body walks on floors. Thus, accidents may occur even if a human body wearing the antistatic clothes walks on flooring. These results will be useful in estimating determination whether electrostatic accidents occur or not.

  18. Heterogeneity in white blood cells has potential to confound DNA methylation measurements.

    Directory of Open Access Journals (Sweden)

    Bjorn T Adalsteinsson

    Full Text Available Epigenetic studies are commonly conducted on DNA from tissue samples. However, tissues are ensembles of cells that may each have their own epigenetic profile, and therefore inter-individual cellular heterogeneity may compromise these studies. Here, we explore the potential for such confounding on DNA methylation measurement outcomes when using DNA from whole blood. DNA methylation was measured using pyrosequencing-based methodology in whole blood (n = 50-179 and in two white blood cell fractions (n = 20, isolated using density gradient centrifugation, in four CGIs (CpG Islands located in genes HHEX (10 CpG sites assayed, KCNJ11 (8 CpGs, KCNQ1 (4 CpGs and PM20D1 (7 CpGs. Cellular heterogeneity (variation in proportional white blood cell counts of neutrophils, lymphocytes, monocytes, eosinophils and basophils, counted by an automated cell counter explained up to 40% (p<0.0001 of the inter-individual variation in whole blood DNA methylation levels in the HHEX CGI, but not a significant proportion of the variation in the other three CGIs tested. DNA methylation levels in the two cell fractions, polymorphonuclear and mononuclear cells, differed significantly in the HHEX CGI; specifically the average absolute difference ranged between 3.4-15.7 percentage points per CpG site. In the other three CGIs tested, methylation levels in the two fractions did not differ significantly, and/or the difference was more moderate. In the examined CGIs, methylation levels were highly correlated between cell fractions. In summary, our analysis detects region-specific differential DNA methylation between white blood cell subtypes, which can confound the outcome of whole blood DNA methylation measurements. Finally, by demonstrating the high correlation between methylation levels in cell fractions, our results suggest a possibility to use a proportional number of a single white blood cell type to correct for this confounding effect in analyses.

  19. Thermocouple psychrometer measurements of in situ water potential changes in heated welded tuff

    International Nuclear Information System (INIS)

    Mao, Nai-hsien; Wang, H.F.

    1991-05-01

    Ten thermocouple psychrometers (TCPs) to measure water potential (WP) were installed in three holes in G-Tunnel at the Nevada Test Site as part of the Prototype Engineered Barrier System Field Tests. These integrated tests measured several parameters as a function of location and time within a few meters of a heater emplaced in welded tuff. The primary goal of the TCP experiment was to find out whether the combination of laboratory calibration and field use of the TCP can provide useful data for determining the change of moisture condition in the field. We calibrated the TCPs in NaCl solutions up to 80 degree C(176 degree F) in the laboratory. In two holes, we used rubber sleeves and packers to house TCPs, and in the third hole, we used foam. All three holes were grouted behind the TCP assemblages. Field results of the heater test showed that small temperature gradients were present for all measurements. Nevertheless, the WP calibration made the necessary correction for the nonisothermal condition. A drying and re-wetting cycle peaked at about day 140 with a WP of -65 bar in borehole P3, located below the heater. A similar cycle but reduced in scale was found at about day 175 with a WP of -45 bar in borehole P2, above the heater. This difference in drying behavior above and below the heater was also observed from neutron data and was explained as a gravity effect. As temperatures increased, the evaporation rate of pore water increased, In unfractured rock, the gas-phase flow was primarily outward. Water condensed above the heater would drain back to keep the boiling region wet, but water condensed below the heater would drain away from the boiling region. This conceptual model explained both the time and magnitude differences for data from holes above and below the heater. 7 refs., 14 figs., 2 tabs

  20. Theoretical and practical aspects of measuring market potential

    Directory of Open Access Journals (Sweden)

    Bešlagić Mirza

    2016-01-01

    Full Text Available The area of research in this paper refers to the theoretical, practical and methodological aspects of the assessment of market potential. It presents the main factors relevant to assessing market potential. The process of evaluating the market potential is important, first of all, for optimal adoption of future strategic decisions in business. Planning of business processes is one of the main reasons for the assessment of the market potential and managers often face, when planning, the environmental factors that can not be influenced. Realistic and quality assessment of market potential and sales forecasting in companies becomes not only a means of gaining competitive advantage, but also a necessary condition for long-term development and survival in the market. Knowledge of the potential market increases the efficiency of business operations. To this end, the theoretical, methodological and practical problems of assessment of market potential were analyzed. The need for this is all the more pronounced because of objective, reliable and valid assessment of the market potential is a prerequisite of business improvement and long-term development of enterprises. The aim was to explain the characteristics of the market potential as one of the primary market sizes in order to carry out its assessment. In this context, it was necessary to identify the main factors influencing the assessment of market potential. Results of the study showed that factors of macro and micro environment of the company, competition and purchasing power determine the market potential of edible oil in Bosnia and Herzegovina. In the empirical part of the paper are applied most common methods of assessment of market potential.

  1. Direct measurements of the plasma potential in ELMy H-mode plasma with ball-pen probes on ASDEX Upgrade tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Adamek, J., E-mail: adamek@ipp.cas.c [Institute of Plasma Physics, Association EURATOM/IPP.CR, Prague, Za Slovankou 3, 182 00, Prague 8 (Czech Republic); Rohde, V.; Mueller, H.W.; Herrmann, A. [Institute of Plasma Physics, Association EURATOM/IPP, Garching (Germany); Ionita, C.; Schrittwieser, R.; Mehlmann, F. [Institute for Ion Physics and Applied Physics, University of Innsbruck, Association EURATOM/OAW (Austria); Stoeckel, J.; Horacek, J.; Brotankova, J. [Institute of Plasma Physics, Association EURATOM/IPP.CR, Prague, Za Slovankou 3, 182 00, Prague 8 (Czech Republic)

    2009-06-15

    Experimental investigations of the plasma potential and electric field were performed for ELMy H-mode plasmas in the vicinity of the limiter shadow of ASDEX Upgrade. A fast reciprocating probe with a probe head containing four ball-pen probes (BPPs) [J. Adamek et al., Czech. J. Phys. 54 (2004) C95 - C99.] was used on the midplane manipulator. Different gradients of the plasma potential were observed during ELMs and in between them. The temporal resolution of the direct plasma potential measurements with BPP was determined by using power-spectra analysis.

  2. Potential Denitrification: Concept and Conditions of its Measurement ...

    African Journals Online (AJOL)

    Denitrification plays important roles in nitrogen cycling and management affecting both the environment and agricultural systems. Potential denitrification has a role in comparison of denitrification magnitudes in different soils. This paper discusses the concept of potential denitrification in relation to denitrification rate and ...

  3. Assessment of the effect of parallel temperature gradients in the JET SOL on Te measured by divertor target Langmuir probes

    NARCIS (Netherlands)

    Ďuran, I.; Ješko, K.; Fuchs, V.; Groth, M.; Guillemaut, C.; Gunn, J.P.; Horáček, J.; Pitts, R.A.; Tskhakaya, D.

    2015-01-01

    Abstract Higher than expected electron temperatures (Te) are often measured by divertor Langmuir probes (LP) in high recycling and detached regimes in JET and other tokamaks. As a possible mechanism to explain this discrepancy, we investigate the effect of penetration of fast, almost collisionless

  4. Application of an online ion chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur

    Science.gov (United States)

    In North America, the dry component of total nitrogen and sulfur deposition remains uncertain due to a lack of measurements of sufficient chemical speciation and temporal extent to develop complete annual mass budgets or of sufficient process level detail to improve current air-s...

  5. Portal hypertension in patients with cirrhosis: indirect assessment of hepatic venous pressure gradient by measuring azygos flow with 2D-cine phase-contrast magnetic resonance imaging.

    Science.gov (United States)

    Gouya, Hervé; Grabar, Sophie; Vignaux, Olivier; Saade, Anastasia; Pol, Stanislas; Legmann, Paul; Sogni, Philippe

    2016-07-01

    To measure azygos, portal and aortic flow by two-dimensional cine phase-contrast magnetic resonance imaging (2D-cine PC MRI), and to compare the MRI values to hepatic venous pressure gradient (HVPG) measurements, in patients with cirrhosis. Sixty-nine patients with cirrhosis were prospectively included. All patients underwent HVPG measurements, upper gastrointestinal endoscopy and 2D-cine PC MRI measurements of azygos, portal and aortic blood flow. Univariate and multivariate regression analyses were used to evaluate the correlation between the blood flow and HVPG. The performance of 2D-cine PC MRI to diagnose severe portal hypertension (HVPG ≥ 16 mmHg) was determined by receiver operating characteristic curve (ROC) analysis, and area under the curves (AUC) were compared. Azygos and aortic flow values were associated with HVPG in univariate linear regression model. Azygos flow (p portal blood flow (AUC = 0.40 (95 % CI [0.25-0.54]). 2D-cine PC MRI is a promising technique to evaluate significant portal hypertension in patients with cirrhosis. • Noninvasive HVPG assessment can be performed with MRI azygos flow. • Azygos MRI flow is an easy-to-measure marker to detect significant portal hypertension. • MRI flow is more specific that varice grade to detect portal hypertension.

  6. Measurement of dissolved reactive phosphorus in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique.

    Science.gov (United States)

    Chen, Hong; Zhang, Meng-Han; Gu, Jia-Li; Zhao, Gang; Zhang, Yu; Li, Jian-Rong

    2014-12-17

    Diffusive gradients in thin-films (DGT) sampler with a polyquaternary ammonium salt (PQAS) aqueous solution as a binding phase and a dialysis membrane as a diffusive phase (PQAS DGT) was developed for the measurement of dissolved reactive phosphorus (DRP) in water. The performance of PQAS DGT was not dependent upon pH 3-10 and ionic strength from 1 × 10(-4) to 1 mol L(-1). The effective binding capacity of PQAS DGT containing 2.0 mL of 0.050 mol L(-1) PQAS solution was estimated as 9.9 μg cm(-2). The measurement of DRP in a synthetic solution by PQAS DGT over a 48 h deployment period demonstrated high consistency with the concentration of DRP in the synthetic solution measured directly by the ammonium molybdate spectrophotometric method. Field deployments of PQAS DGT samplers allowed for accurate measurement of the DRP concentration in situ. The advantages of PQAS DGT include no requirement of the elution steps and direct concentration measurements of the binding phase.

  7. Cerebral hemodynamic changes measured by gradient-echo or spin-echo bolus tracking and its correlation to changes in ICA blood flow measured by phase-mapping MRI

    DEFF Research Database (Denmark)

    Marstrand, J.R.; Rostrup, Egill; Garde, Ellen

    2001-01-01

    Changes in cerebral blood flow (CBF) induced by Acetazolamide (ACZ) were measured using dynamic susceptibility contrast MRI (DSC-MRI) with both spin echo (SE) EPI and gradient echo (GE) EPI, and related to changes in internal carotid artery (ICA) flow measured by phase-mapping. Also examined...... was the effect of repeated bolus injections. CBF, cerebral blood volume (CBV), and mean transit time (MTT) were calculated by singular value decomposition (SVD) and by deconvolution using an exponential function as kernel. The results showed no dependency on calculation method. GE-EPI measured a significant...... increase in CBF and CBV in response to ACZ, while SE-EPI measured a significant increase in CBV and MTT. CBV and MTT change measured by SE-EPI was sensitive to previous bolus injections. There was a significant linear relation between change in CBF measured by GE-EPI and change in ICA flow. In conclusion...

  8. Direct measured systolic pressure gradients across the aorto-iliac segment in multiple-level-obstruction arteriosclerosis

    DEFF Research Database (Denmark)

    Noer, Ivan; Praestholm, J; Tønnesen, K H

    1981-01-01

    Patients with severe ischemia due to multi-level obstructions in the leg arteries both above and below the region were assessed preoperatively by intraarterial brachial and femoral artery pressure measurements. The systolic pressure drop along aorto-iliac obstructions was compared to the angiogra....... Due to large variations, however, the angiographic information was found to be useless in the individual patient. No difference in the pressure drop was found between cases in which rich and poor collateral networks were visualized....

  9. Measuring species diversity in a subtropical forest across a tree size gradient: a comparison of diversity indices

    International Nuclear Information System (INIS)

    Ke, X.; Su, Z.; Hu, Y.; Zhou, Y.; Xu, M.

    2017-01-01

    Shannon-Wiener index and Simpson's diversity index together with other metrics, e.g., richness, number of stems per species or species-specific density (N: S ratio), and kurtosis, were applied to characterize the woody plant diversity patterns of a subtropical broadleaved forest in south China. The aims of our study were to compare the efficacy and sensitivity to community diversity measures between Shannon-Wiener index and Simpson's diversity index. Tree census data from a 5-ha sample plot was partitioned into 3 datasets by diameter class to represent 3 distinct woody plant communities for the characterization of diversity across communities. The 5-ha sample plot of the forest had a total abundance of 23,301 tree stems = 1 cm DBH and a richness of 139 species. The majority of tree stems were seedlings (41.1%) and saplings (38.8%), whereas canopy trees only accounted for 20.1% of the total tree stems. Both Shannon-Wiener index and Simpson's diversity index decreased significantly in response to a decrease in the N: S ratio across the datasets, but Shannon-Wiener index was more sensitive to plot-based richness changes and had a higher efficacy in predicting changes in species richness. Our findings are contrary to the general belief that Shannon-Wiener index is an insensitive measure of the character of the N: S relationship and have demonstrated that it remains a good measure for species diversity in plant community studies for its sensitivity and efficacy. We also suggest that the kurtosis statistic can be used as a new diversity measure due to its sensitivity to diversity change. (author)

  10. Contaminant Gradients in Trees: Directional Tree Coring Reveals Boundaries of Soil and Soil-Gas Contamination with Potential Applications in Vapor Intrusion Assessment.

    Science.gov (United States)

    Wilson, Jordan L; Samaranayake, V A; Limmer, Matthew A; Schumacher, John G; Burken, Joel G

    2017-12-19

    Contaminated sites pose ecological and human-health risks through exposure to contaminated soil and groundwater. Whereas we can readily locate, monitor, and track contaminants in groundwater, it is harder to perform these tasks in the vadose zone. In this study, tree-core samples were collected at a Superfund site to determine if the sample-collection location around a particular tree could reveal the subsurface location, or direction, of soil and soil-gas contaminant plumes. Contaminant-centroid vectors were calculated from tree-core data to reveal contaminant distributions in directional tree samples at a higher resolution, and vectors were correlated with soil-gas characterization collected using conventional methods. Results clearly demonstrated that directional tree coring around tree trunks can indicate gradients in soil and soil-gas contaminant plumes, and the strength of the correlations were directly proportionate to the magnitude of tree-core concentration gradients (spearman's coefficient of -0.61 and -0.55 in soil and tree-core gradients, respectively). Linear regression indicates agreement between the concentration-centroid vectors is significantly affected by in planta and soil concentration gradients and when concentration centroids in soil are closer to trees. Given the existing link between soil-gas and vapor intrusion, this study also indicates that directional tree coring might be applicable in vapor intrusion assessment.

  11. Quantitative method of measuring cancer cell urokinase and metastatic potential

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    1993-01-01

    The metastatic potential of tumors can be evaluated by the quantitative detection of urokinase and DNA. The cell sample selected for examination is analyzed for the presence of high levels of urokinase and abnormal DNA using analytical flow cytometry and digital image analysis. Other factors such as membrane associated urokinase, increased DNA synthesis rates and certain receptors can be used in the method for detection of potentially invasive tumors.

  12. Spatial gradient tuning in metamaterials

    Science.gov (United States)

    Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

    2011-03-01

    Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

  13. Simultaneous multipoint measurements of density gradients and temperature in a flame. Progress report, July 1, 1982-January 31, 1983

    International Nuclear Information System (INIS)

    Chang, R.K.; Chu, B.T.; Long, M.B.

    1983-02-01

    An account is given of recent progress in the development of nonintrusive optical diagnostic techniques and the application of these techniques to turbulent combustion systems. The primary focus of the work over the past year has been in: (1) the use of a broadband rotational CARS technique for the measurement of temperature in flames, and (2) the use of spontaneous Raman scattering to simultaneously map out the fuel gas concentration in a turbulent diffusion flame at 2500 points in a plane intersecting the flow. A summary of new results in each of these areas is given

  14. Selective sampling and measurement of Cr (VI) in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique.

    Science.gov (United States)

    Chen, Hong; Zhang, Yang-Yang; Zhong, Ke-Li; Guo, Lian-Wen; Gu, Jia-Li; Bo, Le; Zhang, Meng-Han; Li, Jian-Rong

    2014-04-30

    A diffusive gradients in thin films (DGT) device with polyquaternary ammonium salt (PQAS) as a novel binding agent (PQAS DGT) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed for the selective sampling and measurement of Cr (VI) in water. The performance of PQAS DGT was independent of pH 3-12 and ionic strength from 1 × 10(-3) to 1 molL(-1). DGT validation experiments showed that Cr (VI) was measured accurately as well as selectively by PQAS DGT, whereas Cr (III) was not determined quantitatively. Compared with diphenylcarbazide spectrophotometric method (DPC), the measurement of Cr (VI) with PQAS DGT was agreement with that of DPC method in the industrial wastewater. PQAS-DGT device had been successfully deployed in local freshwater. The concentrations of Cr (VI) determined by PQAS DGT coupled with GFAAS in Nuer River, Ling River and North Lake were 0.73 ± 0.09 μg L(-1), 0.50 ± 0.07 μg L(-1) and 0.61 ± 0.07 μg L(-1), respectively. The results indicate that PQAS DGT device can be used for the selective sampling and measurement Cr (VI) in water and its detection limit is lower than that of DPC method. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Portal hypertension in patients with cirrhosis: indirect assessment of hepatic venous pressure gradient by measuring azygos flow with 2D-cine phase-contrast magnetic resonance imaging

    International Nuclear Information System (INIS)

    Gouya, Herve; Vignaux, Olivier; Saade, Anastasia; Legmann, Paul; Grabar, Sophie; Pol, Stanislas; Sogni, Philippe

    2016-01-01

    To measure azygos, portal and aortic flow by two-dimensional cine phase-contrast magnetic resonance imaging (2D-cine PC MRI), and to compare the MRI values to hepatic venous pressure gradient (HVPG) measurements, in patients with cirrhosis. Sixty-nine patients with cirrhosis were prospectively included. All patients underwent HVPG measurements, upper gastrointestinal endoscopy and 2D-cine PC MRI measurements of azygos, portal and aortic blood flow. Univariate and multivariate regression analyses were used to evaluate the correlation between the blood flow and HVPG. The performance of 2D-cine PC MRI to diagnose severe portal hypertension (HVPG ≥ 16 mmHg) was determined by receiver operating characteristic curve (ROC) analysis, and area under the curves (AUC) were compared. Azygos and aortic flow values were associated with HVPG in univariate linear regression model. Azygos flow (p < 10 -3 ), aortic flow (p = 0.001), age (p = 0.001) and presence of varices (p < 10 -3 ) were independently associated with HVPG. Azygos flow (AUC = 0.96 (95 % CI) [0.91-1.00]) had significantly higher AUC than aortic (AUC = 0.64 (95 % CI) [0.51-0.77]) or portal blood flow (AUC = 0.40 (95 % CI) [0.25-0.54]). 2D-cine PC MRI is a promising technique to evaluate significant portal hypertension in patients with cirrhosis. (orig.)

  16. Study of early laser-induced plasma dynamics: Transient electron density gradients via Thomson scattering and Stark Broadening, and the implications on laser-induced breakdown spectroscopy measurements

    International Nuclear Information System (INIS)

    Diwakar, P.K.; Hahn, D.W.

    2008-01-01

    To further develop laser-induced breakdown spectroscopy (LIBS) as an analytical technique, it is necessary to better understand the fundamental processes and mechanisms taking place during the plasma evolution. This paper addresses the very early plasma dynamics (first 100 ns) using direct plasma imaging, light scattering, and transmission measurements from a synchronized 532-nm probe laser pulse. During the first 50 ns following breakdown, significant Thomson scattering was observed while the probe laser interacted with the laser-induced plasma. The Thomson scattering was observed to peak 15-25 ns following plasma initiation and then decay rapidly, thereby revealing the highly transient nature of the free electron density and plasma equilibrium immediately following breakdown. Such an intense free electron density gradient is suggestive of a non-equilibrium, free electron wave generated by the initial breakdown and growth processes. Additional probe beam transmission measurements and electron density measurements via Stark broadening of the 500.1-nm nitrogen ion line corroborate the Thomson scattering observations. In concert, the data support the finding of a highly transient plasma that deviates from local thermodynamic equilibrium (LTE) conditions during the first tens of nanoseconds of plasma lifetime. The implications of this early plasma transient behavior are discussed in the context of plasma-analyte interactions and the role on LIBS measurements

  17. Measurement campaign for wind power potential in west Greenland

    Science.gov (United States)

    Rønnow Jakobsen, Kasper

    2013-04-01

    Experiences and results from a wind resource exploring campaign 2003- in west Greenland. Like many other countries, Greenland is trying to reduce its dependency of fossil fuel by implementing renewable energy. The main challenge is that the people live on the coast in scattered settlements, without power infrastructure. Based on this a wind power potential project was established in 2002, funded by the Greenlandic government and the Technical University of Denmark. We present results and experiences of the campaign. 1 Field campaign There were only a few climate stations in or close to settlements and due to their positioning and instrumentation, they were not usable for wind resource estimation. To establish met stations in Arctic areas with complex topography, there are some challenges to face; mast positioning in complex terrain, severe weather conditions, instrumentation, data handling, installation and maintenance budget. The terrain in the ice free and populated part, mainly consists of mountains of different heights and shapes, separated by deep fjords going from the ice cap to the sea. With a generally low wind resource the focus was on the most exposed positions close to the settlements. Data from the nearest existing climate stations was studied for background estimations of predominant wind directions and extreme wind speeds, and based on that the first 10m masts were erected in 2003. 2 Instruments The first installations used standard NRG systems with low cost NRG instruments. For most of the sites this low cost setup did a good job, but there were some problems with the first design, including instrument and boom strains. In subsequent years, the systems were updated several times to be able to operate in the extreme conditions. Different types of instruments, data logger and boom systems were tested to get better data quality and reliability. Today 11 stations with heights ranging from 10-50m are installed and equipped according to the IEC standard

  18. Cerebral hemodynamic changes measured by gradient-echo or spin-echo bolus tracking and its correlation to changes in ICA blood flow measured by phase-mapping MRI

    DEFF Research Database (Denmark)

    Marstrand, J.R.; Rostrup, Egill; Garde, Ellen

    2001-01-01

    Changes in cerebral blood flow (CBF) induced by Acetazolamide (ACZ) were measured using dynamic susceptibility contrast MRI (DSC-MRI) with both spin echo (SE) EPI and gradient echo (GE) EPI, and related to changes in internal carotid artery (ICA) flow measured by phase-mapping. Also examined...... increase in CBF and CBV in response to ACZ, while SE-EPI measured a significant increase in CBV and MTT. CBV and MTT change measured by SE-EPI was sensitive to previous bolus injections. There was a significant linear relation between change in CBF measured by GE-EPI and change in ICA flow. In conclusion......, GE-EPI under the present condition was superior to SE-EPI in monitoring cerebral vascular changes...

  19. Tomographic method for measurement of the gradient refractive index of the crystalline lens. I. The spherical fish lens.

    Science.gov (United States)

    Acosta, Eva; Vazquez, Daniel; Garner, Leon; Smith, George

    2005-03-01

    We present an iterative tomographic algorithm to reconstruct refractive-index profiles for meridional planes of the lens of the spherical fish eye from measurements of deflection angles of refracted rays. Numerical simulations show that the algorithm allows accuracy up to the fourth decimal place, provided that the refractive index can be regarded as an analytical function of the radial coordinate and the experimental errors are neglected. An experimental demonstration is given by applying the algorithm to retrieve the refractive-index profile of a spherical fish lens. The method is conceptually simple and does not require matching of the index of the surrounding medium to that of the surface of the lens, and the related iterative algorithm rapidly converges.

  20. Measurement of moisture motion under a temperature gradient in a concrete for SNR-300 using thermal neutrons

    International Nuclear Information System (INIS)

    Zelinger, A.

    1975-01-01

    For describing the behavior of the moisture in the concrete of the containment of SNR-300 in a hypothetical accident parameters were determined experimentally. The method is based on transmission of thermal neutrons through a plate of concrete. When a temperature of 170 deg C was applied at one end of the plate migration of moisture and evaporation took place. This could be observed by neutron radiography giving a gross picture of moisture migration. Furthermore the intensity of the transmitted neutron beam was measured with a neutron counter. From these values profiles of the change of moisture concentration could be obtained with a spatial resolution of few millimeters. The method used is entirely different from the conventional moisture meters which use fast neutrons. From the experimental data the mass transfer coefficient of vapour, the diffusion coefficient of vapour in concrete and the porosity of the concrete could be determined

  1. Development and application of the diffusive gradients in thin films technique for the measurement of total dissolved inorganic arsenic in waters

    International Nuclear Information System (INIS)

    Panther, Jared G.; Stillwell, Kathryn P.; Powell, Kipton J.; Downard, Alison J.

    2008-01-01

    The diffusive gradients in thin films (DGT) technique, utilizing an iron-hydroxide adsorbent, has been investigated for the in situ accumulation of total dissolved inorganic As in natural waters. Diffusion coefficients of the inorganic As V and As III species in the polyacrylamide gel were measured using a diffusion cell and DGT devices and a variety of factors that may affect the adsorption of the As species to the iron-hydroxide adsorbent, or the diffusion of the individual As species, were investigated. Under conditions commonly encountered in environmental samples, solution pH and the presence of anions, cations, fulvic acid, Fe III -fulvic acid complexes and colloidal iron-hydroxide were demonstrated not to affect uptake of dissolved As. To evaluate DGT as a method for accumulation and pre-concentration of total dissolved inorganic As in natural waters, DGT was applied to two well waters and a river water that was spiked with As. For each sample, the concentration obtained with use of DGT followed by measurement by hydride generation atomic absorption spectrometry with a Pd modifier (HG-AAS) was compared with the concentration of As measured directly by HG-AAS. The results confirmed that DGT is a reliable method for pre-concentration of total dissolved As

  2. Development and application of the diffusive gradients in thin films technique for the measurement of total dissolved inorganic arsenic in waters

    Energy Technology Data Exchange (ETDEWEB)

    Panther, Jared G.; Stillwell, Kathryn P.; Powell, Kipton J. [Chemistry Department, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Downard, Alison J. [Chemistry Department, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)], E-mail: alison.downard@canterbury.ac.nz

    2008-08-01

    The diffusive gradients in thin films (DGT) technique, utilizing an iron-hydroxide adsorbent, has been investigated for the in situ accumulation of total dissolved inorganic As in natural waters. Diffusion coefficients of the inorganic As{sup V} and As{sup III} species in the polyacrylamide gel were measured using a diffusion cell and DGT devices and a variety of factors that may affect the adsorption of the As species to the iron-hydroxide adsorbent, or the diffusion of the individual As species, were investigated. Under conditions commonly encountered in environmental samples, solution pH and the presence of anions, cations, fulvic acid, Fe{sup III}-fulvic acid complexes and colloidal iron-hydroxide were demonstrated not to affect uptake of dissolved As. To evaluate DGT as a method for accumulation and pre-concentration of total dissolved inorganic As in natural waters, DGT was applied to two well waters and a river water that was spiked with As. For each sample, the concentration obtained with use of DGT followed by measurement by hydride generation atomic absorption spectrometry with a Pd modifier (HG-AAS) was compared with the concentration of As measured directly by HG-AAS. The results confirmed that DGT is a reliable method for pre-concentration of total dissolved As.

  3. Comparison of soil solution speciation and diffusive gradients in thin-films measurement as an indicator of copper bioavailability to plants.

    Science.gov (United States)

    Zhao, Fang-Jie; Rooney, Corinne P; Zhang, Hao; McGrath, Steve P

    2006-03-01

    The toxicity effect concentrations (10% effective concentration [EC10] and 50% effective concentration [EC50]) of total added Cu derived from barley root elongation and tomato growth assays varied widely among 18 European soils. We investigated whether this variation could be explained by the solubility or speciation of Cu in soil solutions or the diffusive gradients in thin-films (DGT) measurement. Solubility and Cu speciation varied greatly among the soils tested. However, the EC10 and EC50 of soil solution Cu or free Cu2+ activity varied even more widely than those based on the total added Cu, indicating that solubility or soil solution speciation alone could not explain intersoil variation in Cu toxicity. Estimated EC10 and EC50 of free Cu2+ activity correlated closely and negatively with soil pH, indicating a protective effect of H+, which is consistent with the biotic ligand model concept. The DGT measurement was found to narrow the intersoil variation in EC50 considerably and to be a better predictor of plant Cu concentrations than either soil solution Cu or free Cu2+ activity. We conclude that plant bioavailability of Cu in soil depends on Cu speciation, interactions with protective ions (particularly H+), and the resupply from the solid phase, and we conclude that the DGT measurement provides a useful indicator of Cu bioavailability in soil.

  4. Flux measurement of methanol, acetaldehyde and other oxygenated VOCs from crop harvesting using proton-transfer-reaction mass spectrometry and surface layer gradient method

    International Nuclear Information System (INIS)

    Lindinger, C.; Jordan, A.; Karl, T.; Guenther, A.; Tschiersch, J.; Ruckerbauer, F.; Paretzke, H.

    2002-01-01

    PTR-MS technique was used to measure fluxes of various VOC's including oxygenates using surface layer gradient method. The VOC concentrations and temperature were measured at heights of about 0.5 m and 3.9 m above ground at field site in St. Johann in Tirol during and after grass cutting (24th and 25th of May 2000) in order to calculate fluxes. The sensible heat flux was obtained by a sonic anemometer with turbulence data analyzer. The major crop in this part of Austria are perennial grasses used for livestock farming. We observed VOC emission fluxes including methanol and acetaldehyde as the major volatile, C 5 and C 6 leaf wound compounds with lesser amounts and traces of acetone and butanone. This composition of VOC's is very similar to that released from slashed pasture grass. At the same time, VOC fluxes were measured with PTR-MS and eddy covariance method. Comparing the flux data of methanol and acetaldehyde of both days have shown very similar results. (author)

  5. The Electrochemical H+ Gradient in the Yeast Rhodotorula glutinis

    NARCIS (Netherlands)

    Höfer, Milan; Nicolay, Klaas; Robillard, George

    1985-01-01

    The electrochemical gradient of protons, Δµ~H+, was estimated in the obligatory aerobic yeast Rhodotorula glutinis in the pH0 range from 3 to 8.5. The membrane potential, ΔΨ, was measured by steady-state distribution of the hydrophobic ions, tetraphenylphosphonium (TPP+) for negative ΔΨ above pH0

  6. The electrochemical H+ gradient in the yeast Rhodotorula glutinis

    NARCIS (Netherlands)

    Höfer, M.H.; Nicolaij, K.; Robillard, G.T.

    1985-01-01

    The electrochemical gradient of protons, delta mu H+, was estimated in the obligatory aerobic yeast Rhodotorula glutinis in the pH0 range from 3 to 8.5. The membrane potential, delta psi, was measured by steady-state distribution of the hydrophobic ions, tetraphenylphosphonium (TPP+) for negative

  7. New potential for the Leitz Infinity Coordinate Measuring Machine

    CERN Document Server

    Sanz, Claude; MAINAUD DURAND , Hélène; Schneider, Jurgen; Steffens, Norbert; Morantz , Paul; Shore , Paul

    2015-01-01

    The following study is realised within the frame of the PACMAN project: a study on Particle Accelerator Components Metrology and Alignment to the Nanometre scale, which is a Marie Curie program supported by the European commission and hosted by CERN (European Organisation for Nuclear Research). The aim of this program is to develop and build a pre-alignment bench on which each component is aligned to the required level in one single step using a stretched wire. During the operation, the centre of the stretched wire is aligned with the magnetic axis of the magnet. Then, the position of the wire is measured to the highest possible accuracy using a 3D Coordinate Measuring Machine (CMM) Leitz PMM-C Infinity from HEXAGON Metrology. The research described in this paper is two-fold: on one hand we apply a strong magnetic field to the head of the CMM and evaluate its influence on the measurement accuracy; on the other hand we measure the position

  8. Potential of energy efficiency measures in the world steel industry.

    NARCIS (Netherlands)

    Galama, Tjebbe

    2013-01-01

    SUMMARY The world steel industry plays a major role in energy use and Greenhouse Gas (GHG) emissions now and in the future. Implementing energy efficiency measures is among one of the most cost-effective investments that the industry could make in improv

  9. Novel, cyclic heat dissipation method for the correction of natural temperature gradients in sap flow measurements. Part 1. Theory and application.

    Science.gov (United States)

    Lubczynski, Maciek W; Chavarro-Rincon, Diana; Roy, Jean

    2012-07-01

    Natural temperature gradient (NTG) can be a significant problem in thermal sap flow measurements, particularly in dry environments with sparse vegetation. To resolve this problem, we propose a novel correction method called cyclic heat dissipation (CHD) in its thermal dissipation probe (TDP) application. The CHD method is based on cyclic, switching ON/OFF power schema measurements and a three-exponential model, extrapolating measured signal to steady state thermal equilibrium. The extrapolated signal OFF represents NTG, whereas the extrapolated signal ON represents standard TDP signal, biased by NTG. Therefore, subtraction of the OFF signal from the ON signal allows defining the unbiased TDP signal, finally processed according to standard Granier calibration. The in vivo Kalahari measurements were carried out in three steps on four different tree species, first as NTG, then as standard TDP and finally in CHD mode, each step for ∼1-2 days. Afterwards, each tree was separated from its stem following modified Roberts' (1977) procedure, and CHD verification was applied. The typical NTG varying from ∼0.5 °C during night-time to -1 °C during day-time, after CHD correction, resulted in significant reduction of sap flux densities (J(p)) as compared with the standard TDP, particularly distinct for low J(p). The verification of the CHD method indicated ∼20% agreement with the reference method, largely dependent on the sapwood area estimate. The proposed CHD method offers the following advantages: (i) in contrast to any other NTG correction method, it removes NTG bias from the measured signal by using in situ, extrapolated to thermal equilibrium signal; (ii) it does not need any specific calibration making use of the standard Granier calibration; (iii) it provides a physical background to the proposed NTG correction; (iv) it allows for power savings; (v) it is not tied to TDP, and so can be adapted to other thermal methods. In its current state, the CHD data

  10. Measuring the potential utility of seasonal climate predictions

    Science.gov (United States)

    Tippett, Michael K.; Kleeman, Richard; Tang, Youmin

    2004-11-01

    Variation of sea surface temperature (SST) on seasonal-to-interannual time-scales leads to changes in seasonal weather statistics and seasonal climate anomalies. Relative entropy, an information theory measure of utility, is used to quantify the impact of SST variations on seasonal precipitation compared to natural variability. An ensemble of general circulation model (GCM) simulations is used to estimate this quantity in three regions where tropical SST has a large impact on precipitation: South Florida, the Nordeste of Brazil and Kenya. We find the yearly variation of relative entropy is strongly correlated with shifts in ensemble mean precipitation and weakly correlated with ensemble variance. Relative entropy is also found to be related to measures of the ability of the GCM to reproduce observations.

  11. On local thermal equilibrium and potential gradient vs current characteristic in wall-stabilized argon plasma arc at 0.1 atm pressure

    International Nuclear Information System (INIS)

    Shindo, Haruo; Imazu, Shingo; Inaba, Tsuginori.

    1979-01-01

    In wall-stabilized arc which is a very useful means for determining the transport characteristics of high temperature gases, it is the premise that the inside of arc column is in complete local thermal equilibrium (LTE). In general, the higher the gas pressure, the easier the establishment of LTE, accordingly the experimental investigations on the characteristics of arc discharge as well as the transport characteristics so far were limited to the region of relatively high pressure. However, the authors have found that the theoretical potential vs. current characteristic obtained by the transport characteristic was greatly different from the actually measured one in low pressure region, as the fundamental characteristic of wall-stabilized argon plasma arc below atmospheric pressure. This time, they have clarified this discrepancy at 0.1 atm using the plasma parameters obtained through the spectroscopic measurements. The spectroscopic measurements have been performed through the side observation window at the position 5.5 cm away from the cathode, when arc was ignited vertically at the electrodes distant by 11 cm. Arc radius was 0.5 cm. Electron density and temperature, gas temperature and the excitation density of argon neutral atoms have been experimentally measured. The investigations showed that, in the region of low arc current, where the ratio of current to arc radius is less than 200 A/cm, the fall of gas temperature affected greatly on the decrease of axial electric field of arc column. The non-equilibrium between electron temperature and gas temperature decreased with the increase of arc current, and it was concluded that LTE has been formed at the center portion of arc column above I/R = 300 A/cm. (Wakatsuki, Y.)

  12. Selective sampling and measurement of Cr (VI) in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong, E-mail: redastar@163.com [College of Chemistry, Chemical Engineering and Food Safety, Bohai University (China); Research Institute of Food Science, Bohai University (China); Food Safety Key Lab of Liaoning Province, Jinzhou 121013 (China); Zhang, Yang-Yang; Zhong, Ke-Li; Guo, Lian-Wen [College of Chemistry, Chemical Engineering and Food Safety, Bohai University (China); Research Institute of Food Science, Bohai University (China); Food Safety Key Lab of Liaoning Province, Jinzhou 121013 (China); Gu, Jia-Li [College of Chemistry, Chemical Engineering and Food Safety, Bohai University (China); Bo, Le; Zhang, Meng-Han [College of Chemistry, Chemical Engineering and Food Safety, Bohai University (China); Research Institute of Food Science, Bohai University (China); Food Safety Key Lab of Liaoning Province, Jinzhou 121013 (China); Li, Jian-Rong, E-mail: lijianrong@zjgsu.edu.cn [College of Chemistry, Chemical Engineering and Food Safety, Bohai University (China); Research Institute of Food Science, Bohai University (China); Food Safety Key Lab of Liaoning Province, Jinzhou 121013 (China)

    2014-04-01

    Graphical abstract: - Highlights: • We develop a new DGT device for in situ sampling Cr (VI) in water. • Polyquaternary ammonium salt (PQAS) was used as binding agent of DGT device. • Cr (VI) can be accumulated in the PQAS binding phase whereas Cr (III) cannot. • The DGT performance was independent of pH 3–12 and ionic strength 1 × 10{sup −3}–1 mol L{sup −1}. - Abstract: A diffusive gradients in thin films (DGT) device with polyquaternary ammonium salt (PQAS) as a novel binding agent (PQAS DGT) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed for the selective sampling and measurement of Cr (VI) in water. The performance of PQAS DGT was independent of pH 3–12 and ionic strength from 1 × 10{sup −3} to 1 mol L{sup −1}. DGT validation experiments showed that Cr (VI) was measured accurately as well as selectively by PQAS DGT, whereas Cr (III) was not determined quantitatively. Compared with diphenylcarbazide spectrophotometric method (DPC), the measurement of Cr (VI) with PQAS DGT was agreement with that of DPC method in the industrial wastewater. PQAS-DGT device had been successfully deployed in local freshwater. The concentrations of Cr (VI) determined by PQAS DGT coupled with GFAAS in Nuer River, Ling River and North Lake were 0.73 ± 0.09 μg L{sup −1}, 0.50 ± 0.07 μg L{sup −1} and 0.61 ± 0.07 μg L{sup −1}, respectively. The results indicate that PQAS DGT device can be used for the selective sampling and measurement Cr (VI) in water and its detection limit is lower than that of DPC method.

  13. Selective sampling and measurement of Cr (VI) in water with polyquaternary ammonium salt as a binding agent in diffusive gradients in thin-films technique

    International Nuclear Information System (INIS)

    Chen, Hong; Zhang, Yang-Yang; Zhong, Ke-Li; Guo, Lian-Wen; Gu, Jia-Li; Bo, Le; Zhang, Meng-Han; Li, Jian-Rong

    2014-01-01

    Graphical abstract: - Highlights: • We develop a new DGT device for in situ sampling Cr (VI) in water. • Polyquaternary ammonium salt (PQAS) was used as binding agent of DGT device. • Cr (VI) can be accumulated in the PQAS binding phase whereas Cr (III) cannot. • The DGT performance was independent of pH 3–12 and ionic strength 1 × 10 −3 –1 mol L −1 . - Abstract: A diffusive gradients in thin films (DGT) device with polyquaternary ammonium salt (PQAS) as a novel binding agent (PQAS DGT) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed for the selective sampling and measurement of Cr (VI) in water. The performance of PQAS DGT was independent of pH 3–12 and ionic strength from 1 × 10 −3 to 1 mol L −1 . DGT validation experiments showed that Cr (VI) was measured accurately as well as selectively by PQAS DGT, whereas Cr (III) was not determined quantitatively. Compared with diphenylcarbazide spectrophotometric method (DPC), the measurement of Cr (VI) with PQAS DGT was agreement with that of DPC method in the industrial wastewater. PQAS-DGT device had been successfully deployed in local freshwater. The concentrations of Cr (VI) determined by PQAS DGT coupled with GFAAS in Nuer River, Ling River and North Lake were 0.73 ± 0.09 μg L −1 , 0.50 ± 0.07 μg L −1 and 0.61 ± 0.07 μg L −1 , respectively. The results indicate that PQAS DGT device can be used for the selective sampling and measurement Cr (VI) in water and its detection limit is lower than that of DPC method

  14. Physics potential for the measurement of ${\\sigma(H\

    CERN Document Server

    Milutinović-Dumbelović, G; Grefe, C; Kačarević, G; Lukić, S; Pandurović, M; Roloff, P; Smiljanić, I

    2015-01-01

    The future Compact Linear Collider (CLIC) offers a possibility for a rich precision physics programme, in particular in the Higgs sector through the energy staging. This is the first paper addressing the measurement of the Standard Model Higgs boson decay into two muons at 1.4 TeV CLIC. With respect to similar studies at future linear colliders, this paper includes several novel contributions to the statistical uncertainty of the measurement. The later includes the Equivalent Photon Approximation and realistic forward electron tagging based on energy deposition maps in the forward calorimeters, as well as several processes with the Beamstrahlung photons that results in irreducible contribution to the signal. In addition, coincidence of the Bhabha scattering with the signal and background processes is considered, altering the signal selection efficiency. The study is performed using a fully simulated CLIC_ILD detector model. It is shown that the branching ratio for the Higgs decay into a pair of muons BR(${H\\r...

  15. Changes in H(+)-ATP Synthase Activity, Proton Electrochemical Gradient, and pH in Pea Chloroplast Can Be Connected with Variation Potential.

    Science.gov (United States)

    Sukhov, Vladimir; Surova, Lyubov; Morozova, Ekaterina; Sherstneva, Oksana; Vodeneev, Vladimir

    2016-01-01

    Local stimulation induces generation and propagation of electrical signals, including the variation potential (VP) and action potential, in plants. Burning-induced VP changes the physiological state of plants; specifically, it inactivates photosynthesis. However, the mechanisms that decrease photosynthesis are poorly understood. We investigated these mechanisms by measuring VP-connected systemic changes in CO2 assimilation, parameters of light reactions of photosynthesis, electrochromic pigment absorbance shifts, and light scattering. We reveal that inactivation of photosynthesis in the pea, including inactivation of dark and light reactions, was connected with the VP. Inactivation of dark reactions decreased the rate constant of the fast relaxation of the electrochromic pigment absorbance shift, which reflected a decrease in the H(+)-ATP synthase activity. This decrease likely contributed to the acidification of the chloroplast lumen, which developed after VP induction. However, VP-connected decrease of the proton motive force across the thylakoid membrane, possibly, reflected a decreased pH in the stroma. This decrease may be another mechanism of chloroplast lumen acidification. Overall, stroma acidification can decrease electron flow through photosystem I, and lumen acidification induces growth of fluorescence non-photochemical quenching and decreases electron flow through photosystem II, i.e., pH decreases in the stroma and lumen, possibly, contribute to the VP-induced inactivation of light reactions of photosynthesis.

  16. An analysis of the uncertainty and bias in DCE-MRI measurements using the spoiled gradient-recalled echo pulse sequence

    International Nuclear Information System (INIS)

    Subashi, Ergys; Choudhury, Kingshuk R.; Johnson, G. Allan

    2014-01-01

    Purpose: The pharmacokinetic parameters derived from dynamic contrast-enhanced (DCE) MRI have been used in more than 100 phase I trials and investigator led studies. A comparison of the absolute values of these quantities requires an estimation of their respective probability distribution function (PDF). The statistical variation of the DCE-MRI measurement is analyzed by considering the fundamental sources of error in the MR signal intensity acquired with the spoiled gradient-echo (SPGR) pulse sequence. Methods: The variance in the SPGR signal intensity arises from quadrature detection and excitation flip angle inconsistency. The noise power was measured in 11 phantoms of contrast agent concentration in the range [0–1] mM (in steps of 0.1 mM) and in onein vivo acquisition of a tumor-bearing mouse. The distribution of the flip angle was determined in a uniform 10 mM CuSO 4 phantom using the spin echo double angle method. The PDF of a wide range of T1 values measured with the varying flip angle (VFA) technique was estimated through numerical simulations of the SPGR equation. The resultant uncertainty in contrast agent concentration was incorporated in the most common model of tracer exchange kinetics and the PDF of the derived pharmacokinetic parameters was studied numerically. Results: The VFA method is an unbiased technique for measuringT1 only in the absence of bias in excitation flip angle. The time-dependent concentration of the contrast agent measured in vivo is within the theoretically predicted uncertainty. The uncertainty in measuring K trans with SPGR pulse sequences is of the same order, but always higher than, the uncertainty in measuring the pre-injection longitudinal relaxation time (T1 0 ). The lowest achievable bias/uncertainty in estimating this parameter is approximately 20%–70% higher than the bias/uncertainty in the measurement of the pre-injection T1 map. The fractional volume parameters derived from the extended Tofts model were found to be

  17. Two dimensional gel electrophoresis using narrow pH 3-5.6 immobilised pH gradient strips identifies potential novel disease biomarkers in plasma or serum

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Bevin Gangadharan & Nicole Zitzmann ### Abstract Two-dimensional gel electrophoresis (2-DE) is a protein separation technique often used to separate plasma or serum proteins in an attempt to identify novel biomarkers. This protocol describes how to run 2-DE gels using narrow pH 3-5.6 immobilised pH gradient strips to separate 2 mg of serum proteins. pH 3-6 ampholytes are used to enhance the solubility of proteins in this pH range before the serum proteins are separated in the...

  18. Physics potential of precision measurements of the LHC luminosity

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The uncertainty in the determination of the LHC luminosity is rapidly becoming a limiting factor for the analysis and interpretation of many important LHC processes. In this talk first of all we discuss the theoretical accuracy of total cross sections and examine in which cases the luminosity error is or will be dominant. We then review the impact of LHC data in PDF determinations, with enphasis on the effects of the luminosity uncertainty. We explore the requirements for the accuracy of the 2011 luminosity determination from the point of view of standard candle cross section and other important processes. Finally we discuss what we can learn from the accurate measurement of cross section ratios at different center of mass energies for processes like W, ttbar and dijet production.

  19. Measuring the zeta potential. The relationships with sandstone fineness

    Directory of Open Access Journals (Sweden)

    de Luxán, M. P.

    1989-09-01

    Full Text Available The application of the zeta potential technique in the area of construction materials and Portland cement is quite recent. The initial research work involved the study of cement suspensions or suspensions of one of the components of cement, such as alite, tricalcium alumínate, in the presence of additives and, more specifically, superplasticizers. The studies of this sort were extended with the mixing of active additions into cement (fly ashes, etc.. The present study discusses the application of siliceous materials (sandstone as a basis of the research into the behaviour of sandstone mortars containing repair products.

    La aplicación de la técnica del potencial zeta en el campo de los materiales de construcción y del cemento portland es muy reciente. Las primeras investigaciones se refieren al estudio de suspensiones de cemento o de alguno de sus compuestos que lo forman como alita, aluminato tricálcico, en presencia de aditivos y, más concretamente, de superfluidificantes. Con la incorporación de adiciones activas al cemento (cenizas volantes,... se amplían los estudios de este tipo de cementos. En este trabajo se considera la aplicación a los materiales silíceos (arenisca como base para la investigación del comportamiento de los morteros de arenisca conteniendo productos de reparación.

  20. Combining Step Gradients and Linear Gradients in Density.

    Science.gov (United States)

    Kumar, Ashok A; Walz, Jenna A; Gonidec, Mathieu; Mace, Charles R; Whitesides, George M

    2015-06-16

    Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levitation of diamagnetic objects in a paramagnetic fluid within a magnetic field gradient—can be arranged to provide a near-linear gradient in effective density where the height of a levitating object above the surface of the magnet corresponds to its density; the strength of the gradient in effective density can be tuned by the choice of paramagnetic salt and its concentrations and by the strength and gradient in the magnetic field. Including paramagnetic salts (e.g., MnSO4 or MnCl2) in AMPS, and placing them in a magnetic field gradient, enables their use as media for MagLev. The potential to create large steps in density with AMPS allows separations of objects across a range of densities. The gradients produced by MagLev provide resolution over a continuous range of densities. By combining these approaches, mixtures of objects with large differences in density can be separated and analyzed simultaneously. Using MagLev to add an effective gradient in density also enables tuning the range of densities captured at an interface of an AMPS by simply changing the position of the container in the magnetic field. Further, by creating AMPS in which phases have different concentrations of paramagnetic ions, the phases can provide different resolutions in density. These results suggest that combining steps in density with gradients in density can enable new classes of separations based on density.

  1. Reduced density gradient as a novel approach for estimating QSAR descriptors, and its application to 1, 4-dihydropyridine derivatives with potential antihypertensive effects.

    Science.gov (United States)

    Jardínez, Christiaan; Vela, Alberto; Cruz-Borbolla, Julián; Alvarez-Mendez, Rodrigo J; Alvarado-Rodríguez, José G

    2016-12-01

    The relationship between the chemical structure and biological activity (log IC 50 ) of 40 derivatives of 1,4-dihydropyridines (DHPs) was studied using density functional theory (DFT) and multiple linear regression analysis methods. With the aim of improving the quantitative structure-activity relationship (QSAR) model, the reduced density gradient s( r) of the optimized equilibrium geometries was used as a descriptor to include weak non-covalent interactions. The QSAR model highlights the correlation between the log IC 50 with highest molecular orbital energy (E HOMO ), molecular volume (V), partition coefficient (log P), non-covalent interactions NCI(H4-G) and the dual descriptor [Δf(r)]. The model yielded values of R 2 =79.57 and Q 2 =69.67 that were validated with the next four internal analytical validations DK=0.076, DQ=-0.006, R P =0.056, and R N =0.000, and the external validation Q 2 boot =64.26. The QSAR model found can be used to estimate biological activity with high reliability in new compounds based on a DHP series. Graphical abstract The good correlation between the log IC 50 with the NCI (H4-G) estimated by the reduced density gradient approach of the DHP derivatives.

  2. Mercury Distribution in the Deûle River (Northern France) Measured by the Diffusive Gradients in Thin Films Technique and Conventional Methods.

    Science.gov (United States)

    Diviš, Pavel; Kadlecová, Milada; Ouddane, Baghdad

    2016-05-01

    The distribution of mercury in surface water and in sediment from Deûle River in Northern France was studied by application of conventional sampling methods and by diffusive gradients in thin films technique (DGT). Concentration of total dissolved mercury in surface water was 20.8 ± 0.8 ng l(-1). The particulate mercury concentration was 6.2 ± 0.6 µg g(-1). The particulate mercury was accumulated in sediment (9.9 ± 2.3 mg kg(-1)), and it was transformed by methylating bacteria to methylmercury, mainly in the first 2-cm layer of the sediment. Total dissolved concentration of mercury in sediment pore water obtained by application of centrifugation extraction was 17.6 ± 4.1 ng l(-1), and it was comparable with total dissolved pore water mercury concentration measured by DGT probe containing Duolite GT-73 resin gel (18.2 ± 4.3 ng l(-1)), taking the sediment heterogeneity and different principles of the applied methods into account. By application of two DGT probes with different resin gels specific for mercury, it was found that approximately 30% of total dissolved mercury in sediment pore water was present in labile forms easy available for biota. The resolution of mercury DGT depth profiles was 0.5 cm, which allows, unlike conventional techniques, to study the connection of the geochemical cycle of mercury with geochemical cycles of iron and manganese.

  3. The potential of ground gravity measurements to validate GRACE data

    Directory of Open Access Journals (Sweden)

    D. Crossley

    2003-01-01

    Full Text Available New satellite missions are returning high precision, time-varying, satellite measurements of the Earth’s gravity field. The GRACE mission is now in its calibration/- validation phase and first results of the gravity field solutions are imminent. We consider here the possibility of external validation using data from the superconducting gravimeters in the European sub-array of the Global Geodynamics Project (GGP as ‘ground truth’ for comparison with GRACE. This is a pilot study in which we use 14 months of 1-hour data from the beginning of GGP (1 July 1997 to 30 August 1998, when the Potsdam instrument was relocated to South Africa. There are 7 stations clustered in west central Europe, and one station, Metsahovi in Finland. We remove local tides, polar motion, local and global air pressure, and instrument drift and then decimate to 6-hour samples. We see large variations in the time series of 5–10µgal between even some neighboring stations, but there are also common features that correlate well over the 427-day period. The 8 stations are used to interpolate a minimum curvature (gridded surface that extends over the geographical region. This surface shows time and spatial coherency at the level of 2– 4µgal over the first half of the data and 1–2µgal over the latter half. The mean value of the surface clearly shows a rise in European gravity of about 3µgal over the first 150 days and a fairly constant value for the rest of the data. The accuracy of this mean is estimated at 1µgal, which compares favorably with GRACE predictions for wavelengths of 500 km or less. Preliminary studies of hydrology loading over Western Europe shows the difficulty of correlating the local hydrology, which can be highly variable, with large-scale gravity variations.Key words. GRACE, satellite gravity, superconducting gravimeter, GGP, ground truth

  4. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  5. Comparisons between high-resolution profiles of squared refractive index gradient M2 measured by the Middle and Upper Atmosphere Radar and unmanned aerial vehicles (UAVs during the Shigaraki UAV-Radar Experiment 2015 campaign

    Directory of Open Access Journals (Sweden)

    H. Luce

    2017-03-01

    Full Text Available New comparisons between the square of the generalized potential refractive index gradient M2, estimated from the very high-frequency (VHF Middle and Upper Atmosphere (MU Radar, located at Shigaraki, Japan, and unmanned aerial vehicle (UAV measurements are presented. These comparisons were performed at unprecedented temporal and range resolutions (1–4 min and  ∼  20 m, respectively in the altitude range  ∼  1.27–4.5 km from simultaneous and nearly collocated measurements made during the ShUREX (Shigaraki UAV-Radar Experiment 2015 campaign. Seven consecutive UAV flights made during daytime on 7 June 2015 were used for this purpose. The MU Radar was operated in range imaging mode for improving the range resolution at vertical incidence (typically a few tens of meters. The proportionality of the radar echo power to M2 is reported for the first time at such high time and range resolutions for stratified conditions for which Fresnel scatter or a reflection mechanism is expected. In more complex features obtained for a range of turbulent layers generated by shear instabilities or associated with convective cloud cells, M2 estimated from UAV data does not reproduce observed radar echo power profiles. Proposed interpretations of this discrepancy are presented.

  6. Spheroidal Integral Equations for Geodetic Inversion of Geopotential Gradients

    Science.gov (United States)

    Novák, Pavel; Šprlák, Michal

    2018-03-01

    The static Earth's gravitational field has traditionally been described in geodesy and geophysics by the gravitational potential (geopotential for short), a scalar function of 3-D position. Although not directly observable, geopotential functionals such as its first- and second-order gradients are routinely measured by ground, airborne and/or satellite sensors. In geodesy, these observables are often used for recovery of the static geopotential at some simple reference surface approximating the actual Earth's surface. A generalized mathematical model is represented by a surface integral equation which originates in solving Dirichlet's boundary-value problem of the potential theory defined for the harmonic geopotential, spheroidal boundary and globally distributed gradient data. The mathematical model can be used for combining various geopotential gradients without necessity of their re-sampling or prior continuation in space. The model extends the apparatus of integral equations which results from solving boundary-value problems of the potential theory to all geopotential gradients observed by current ground, airborne and satellite sensors. Differences between spherical and spheroidal formulations of integral kernel functions of Green's kind are investigated. Estimated differences reach relative values at the level of 3% which demonstrates the significance of spheroidal approximation for flattened bodies such as the Earth. The observation model can be used for combined inversion of currently available geopotential gradients while exploring their spectral and stochastic characteristics. The model would be even more relevant to gravitational field modelling of other bodies in space with more pronounced spheroidal geometry than that of the Earth.

  7. 77 FR 11119 - Request for Nominations of Children's Healthcare Quality Measures for Potential Inclusion in the...

    Science.gov (United States)

    2012-02-24

    ... Nominations of Children's Healthcare Quality Measures for Potential Inclusion in the CHIPRA 2013 Improved Core... quality for potential inclusion in the CHIPRA 2013 Improved Core Set of Health Care Quality Measures (the... inclusion, more information, including a copyright release (if applicable) and full measure specifications...

  8. Inter-comparison of Flux-Gradient and Relaxed Eddy Accumulation Methods for Measuring Ammonia Flux Above a Corn Canopy in Central Illinois, USA

    Science.gov (United States)

    Nelson, A. J.; Koloutsou-Vakakis, S.; Rood, M. J.; Lichiheb, N.; Heuer, M.; Myles, L.

    2017-12-01

    Ammonia (NH3) is a precursor to fine particulate matter (PM) in the ambient atmosphere. Agricultural activities represent over 80% of anthropogenic emissions of NH3 in the United States. The use of nitrogen-based fertilizers contribute > 50% of total NH3 emissions in central Illinois. The U.S. EPA Science Advisory Board has called for improved methods to measure, model, and report atmospheric NH3 concentrations and emissions from agriculture. High uncertainties in the temporal and spatial distribution of NH3 emissions contribute to poor performance of air quality models in predicting ambient PM concentrations. This study reports and compares NH­3 flux measurements of differing temporal resolution obtained with two methods: relaxed eddy accumulation (REA) and flux-gradient (FG). REA and FG systems were operated concurrently above a corn canopy at the University of Illinois at Urbana-Champaign (UIUC) Energy Biosciences Institute (EBI) Energy Farm during the 2014 corn-growing season. The REA system operated during daytime, providing average fluxes over four-hour sampling intervals, where time resolution was limited by detection limit of denuders. The FG system employed a cavity ring-down spectrometer, and was operated continuously, reporting 30 min flux averages. A flux-footprint evaluation was used for quality control, resulting in 1,178 qualified FG measurements, 82 of which were coincident with REA measurements. Similar emission trends were observed with both systems, with peak NH3 emission observed one week after fertilization. For all coincident samples, mean NH3 flux was 205 ± 300 ng-N-m2s-1 and 110 ± 256 ng-N-m2s-1 as measured with REA and FG, respectively, where positive flux indicates emission. This is the first reported inter-comparison of REA and FG methods as used for quantifying NH3 fluxes from cropland. Preliminary analysis indicates the improved temporal resolution and continuous sampling enabled by FG allow for the identification of emission pulses

  9. Sink plot for runoff measurements on semi-flat terrains: preliminary data and their potential hydrological and ecological implications

    Directory of Open Access Journals (Sweden)

    Kidron Giora J.

    2014-12-01

    Full Text Available In arid and semiarid regions where water is the main limiting factor, water redistribution is regarded as an important hydrological process of great ecological value. By providing additional water to certain loci, moist pockets of great productivity are formed, characterized by high plant biomass and biological activity. These moist pockets are often a result of runon. Yet, although runoff may take place on semi-flat undulating surfaces, runoff measurements are thus far confined to slopes, where a sufficient gradient facilitates downslope water harvesting. On undulating surfaces of mounds and depressions, such as in interdunes, no quantification of the amount of water reaching depressions is feasible due to the fact that no reliable method for measuring the runoff amounts in semi-flat terrains is available. The current paper describes specific runoff plots, designed to measure runoff in depressions (sinks. These plots, termed sink plots (SPs, were operative in the Hallamish dunefield (Negev Desert, Israel. The paper presents measurements of runoff yield that were carried out between January 2013 and January 2014 on SPs and compared them to runoff obtained from crusted slope plots and fine-grained (playa surfaces. The potential hydrological and ecological implications of water redistribution within semi-flat terrains for this and other arid ecosystems are discussed.

  10. Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES Campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean basin

    Science.gov (United States)

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Wester...

  11. Intensive measurements of gas, water, and energy exchange between vegetation and troposhere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

    NARCIS (Netherlands)

    Penuelas, J.; Guenther, A.; Rapparini, F.; Llusia, J.; Vilà-Guerau De Arellano, J.

    2013-01-01

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean

  12. The Cladistic Basis for the Phylogenetic Diversity (PD Measure Links Evolutionary Features to Environmental Gradients and Supports Broad Applications of Microbial Ecology’s “Phylogenetic Beta Diversity” Framework

    Directory of Open Access Journals (Sweden)

    Rob Knight

    2009-11-01

    Full Text Available The PD measure of phylogenetic diversity interprets branch lengths cladistically to make inferences about feature diversity. PD calculations extend conventional specieslevel ecological indices to the features level. The “phylogenetic beta diversity” framework developed by microbial ecologists calculates PD-dissimilarities between community localities. Interpretation of these PD-dissimilarities at the feature level explains the framework’s success in producing ordinations revealing environmental gradients. An example gradients space using PD-dissimilarities illustrates how evolutionary features form unimodal response patterns to gradients. This features model supports new application of existing species-level methods that are robust to unimodal responses, plus novel applications relating to climate change, commercial products discovery, and community assembly.

  13. Validation of measured poleward TEC gradient using multi-station GPS with Artificial Neural Network based TEC model in low latitude region for developing predictive capability of ionospheric scintillation

    Science.gov (United States)

    Sur, D.; Paul, A.

    2017-12-01

    The equatorial ionosphere shows sharp diurnal and latitudinal Total Electron Content (TEC) variations over a major part of the day. Equatorial ionosphere also exhibits intense post-sunset ionospheric irregularities. Accurate prediction of TEC in these low latitudes is not possible from standard ionospheric models. An Artificial Neural Network (ANN) based Vertical TEC (VTEC) model has been designed using TEC data in low latitude Indian longitude sector for accurate prediction of VTEC. GPS TEC data from the stations Calcutta (22.58°N, 88.38°E geographic, magnetic dip 32°), Baharampore (24.09°N, 88.25°E geographic, magnetic dip 35°) and Siliguri (26.72°N, 88.39°E geographic; magnetic dip 40°) are used as training dataset for the duration of January 2007-September 2011. Poleward VTEC gradients from northern EIA crest to region beyond EIA crest have been calculated from measured VTEC and compared with that obtained from ANN based VTEC model. TEC data from Calcutta and Siliguri are used to compute VTEC gradients during April 2013 and August-September 2013. It has been observed that poleward VTEC gradient computed from ANN based TEC model has shown good correlation with measured values during vernal and autumnal equinoxes of high solar activity periods of 2013. Possible correlation between measured poleward TEC gradients and post-sunset scintillations (S4 ≥ 0.4) from northern crest of EIA has been observed in this paper. From the observation, a suitable threshold poleward VTEC gradient has been proposed for possible occurrence of post-sunset scintillations at northern crest of EIA along 88°E longitude. Poleward VTEC gradients obtained from ANN based VTEC model are used to forecast possible ionospheric scintillation after post-sunset period using the threshold value. It has been observed that these predicted VTEC gradients obtained from ANN based VTEC model can forecast post-sunset L-band scintillation with an accuracy of 67% to 82% in this dynamic low latitude

  14. On invariant measures for the Vlasov equation with a regular potential

    International Nuclear Information System (INIS)

    Zhidkov, P.E.

    2003-01-01

    We consider a Vlasov equation with a smooth bounded potential of interaction between particles in a class of measure-valued solutions and construct a measure which is invariant for this problem in a sense

  15. Comparison between Random Forests, Artificial Neural Networks and Gradient Boosted Machines Methods of On-Line Vis-NIR Spectroscopy Measurements of Soil Total Nitrogen and Total Carbon

    Directory of Open Access Journals (Sweden)

    Said Nawar

    2017-10-01

    Full Text Available Accurate and detailed spatial soil information about within-field variability is essential for variable-rate applications of farm resources. Soil total nitrogen (TN and total carbon (TC are important fertility parameters that can be measured with on-line (mobile visible and near infrared (vis-NIR spectroscopy. This study compares the performance of local farm scale calibrations with those based on the spiking of selected local samples from both fields into an European dataset for TN and TC estimation using three modelling techniques, namely gradient boosted machines (GBM, artificial neural networks (ANNs and random forests (RF. The on-line measurements were carried out using a mobile, fiber type, vis-NIR spectrophotometer (305–2200 nm (AgroSpec from tec5, Germany, during which soil spectra were recorded in diffuse reflectance mode from two fields in the UK. After spectra pre-processing, the entire datasets were then divided into calibration (75% and prediction (25% sets, and calibration models for TN and TC were developed using GBM, ANN and RF with leave-one-out cross-validation. Results of cross-validation showed that the effect of spiking of local samples collected from a field into an European dataset when combined with RF has resulted in the highest coefficients of determination (R2 values of 0.97 and 0.98, the lowest root mean square error (RMSE of 0.01% and 0.10%, and the highest residual prediction deviations (RPD of 5.58 and 7.54, for TN and TC, respectively. Results for laboratory and on-line predictions generally followed the same trend as for cross-validation in one field, where the spiked European dataset-based RF calibration models outperformed the corresponding GBM and ANN models. In the second field ANN has replaced RF in being the best performing. However, the local field calibrations provided lower R2 and RPD in most cases. Therefore, from a cost-effective point of view, it is recommended to adopt the spiked European dataset

  16. Heavy metal contents of road-deposited sediment along the urban-rural gradient around Beijing and its potential contribution to runoff pollution.

    Science.gov (United States)

    Zhao, Hongtao; Li, Xuyong; Wang, Xiaomei

    2011-09-01

    Understanding the contribution of road-deposited sediment (RDS) and its washoff process is essential for controlling urban runoff pollution. Ninety-seven RDS samples were collected along the urban-suburban-rural gradient from areas of five administrative units in the Beijing metropolitan region, including central urban (UCA), urban village (UVA), central suburban county (CSA), rural town (RTA), and rural village (RVA) areas. RDS washoff was evaluated with different particle sizes using a rainfall simulator. Heavy metal elements (i.e., Cr, Cu, Ni, Pb, and Zn) were estimated in both RDS and runoff samples. The RDS mass per unit area increased in the order UCA (21 ± 24 g/m(2)) ≈ CSA (20 ± 16 g/m(2)) runoff pollution contributions per unit area. Our findings imply that controlling the first flush in the UCA and CSA, and improving existing street cleaning methods and road surface conditions in the TRA, UVA, and RVA will be appropriate strategies for controlling runoff pollution from RDS.

  17. Nitrous oxide and methane exchange in two small temperate forest catchments - effects of hydrological gradients and implications for global warming potentials of forest soils

    DEFF Research Database (Denmark)

    Christiansen, Jesper Riis; Vesterdal, Lars; Gundersen, Per

    2012-01-01

    half the catchment area at both sites, the global warming potential (GWP) derived from N2O and CH4 was more than doubled when accounting for these wet areas in the catchments. The results stress the importance of wet soils in assessments of forest soil global warming potentials, as even small...

  18. Pressure Gradients in the Inner Surf and Outer Swash Zone

    Science.gov (United States)

    Kidwell, A.; Puleo, J. A.; Torres-Freyermuth, A.

    2010-12-01

    The swash zone is a highly dynamic region of the beach profile. Although there has been significant progression in understanding the complex hydrodynamics of the swash zone, an improvement in the understanding of the sediment transport mechanisms deserves further investigation. Prior studies have demonstrated that the existing formulations derived from the energetics-type formulation do not accurately and consistently predict sediment transport. Thus, measurements and numerical modeling can contribute in the improvement of the current predictive capability of sediment transport. A potential enhancement to nearshore sediment transport is the horizontal pressure gradient. However, measuring the dynamic pressure gradient in nearshore flows is a difficult task. For instance, standard pressure sensors are generally ill-suited for this type of measurement in shallow swash flows due to the obstructing size of the sensor and the potential for flow interference. With improved measurement apparati and techniques, it is possible to obtain measurements of the horizontal pressure gradient. Our current research includes laboratory and numerical model investigation of the horizontal pressure gradient in the inner surf and outer swash zone. An inexpensive differential pressure gauge is employed allowing for a pressure port on the order of 2 mm diameter. Four pressure sensor pairs are installed 1 cm above the bed with a cross-shore spacing of 8 cm. The sensors are deployed just outside of and at various locations within the outer swash zone to determine spatio-temporal pressure variations. The measurement of total pressure coupled with the corresponding free surface measurements from co-located capacitance wave gauges yields time series of the hydrostatic and dynamic pressure and pressure gradients. A VOF-type RANS model is employed in this investigation. Firstly, the numerical model is validated with swash measurements. Then, model simulations will be performed in order to

  19. Automatic emissive probe apparatus for accurate plasma and vacuum space potential measurements

    Science.gov (United States)

    Jianquan, LI; Wenqi, LU; Jun, XU; Fei, GAO; Younian, WANG

    2018-02-01

    We have developed an automatic emissive probe apparatus based on the improved inflection point method of the emissive probe for accurate measurements of both plasma potential and vacuum space potential. The apparatus consists of a computer controlled data acquisition card, a working circuit composed by a biasing unit and a heating unit, as well as an emissive probe. With the set parameters of the probe scanning bias, the probe heating current and the fitting range, the apparatus can automatically execute the improved inflection point method and give the measured result. The validity of the automatic emissive probe apparatus is demonstrated in a test measurement of vacuum potential distribution between two parallel plates, showing an excellent accuracy of 0.1 V. Plasma potential was also measured, exhibiting high efficiency and convenient use of the apparatus for space potential measurements.

  20. Compensation of the skin effect in low-frequency potential drop measurements

    OpenAIRE

    Corcoran, J; Nagy, PB

    2016-01-01

    Potential drop measurements are routinely used in the non-destructive evaluation of component integrity. Potential drop measurements use either direct current (DC) or alternating current (AC), the latter will have superior noise performance due to the ability to perform phase sensitive detection and the reduction of flicker noise. AC measurements are however subject to the skin effect where the current is electromagnetically constricted to the surface of the component. Unfortunately, the skin...

  1. The measurement of potential distribution of plasma in MM-4 fusion device

    International Nuclear Information System (INIS)

    Tian Zhongyu; Ming Linzhou; Feng Xiaozhen; Feng Chuntang; Yi Youjun; Wang Jihai; Liu Yihua

    1988-11-01

    Some experimental results of the potential distribution in MM-4 fusion device are presented by measuring the floating potential of probe. The results showed that the distribution of axial potential is asymmetrical, but the radial potential is symmetrical. There are double ion potential wells in the plasma. The depth of the deepest potential well become deeper is the strength of the magnetic field and injection current are increasing. The location of the deepest well is moved towards the device center along with the increasing of injection energy. This is different from others results. The mechanism of causing this distribution in also discussed

  2. Measuring learning potential in people with schizophrenia: A comparison of two tasks.

    Science.gov (United States)

    Rempfer, Melisa V; McDowd, Joan M; Brown, Catana E

    2017-12-01

    Learning potential measures utilize dynamic assessment methods to capture performance changes following training on a cognitive task. Learning potential has been explored in schizophrenia research as a predictor of functional outcome and there have been calls for psychometric development in this area. Because the majority of learning potential studies have utilized the Wisconsin Card Sorting Test (WCST), we extended this work using a novel measure, the Rey Osterrieth Complex Figure Test (ROCFT). This study had the following aims: 1) to examine relationships among different learning potential indices for two dynamic assessment tasks, 2) to examine the association between WCST and ROCFT learning potential measures, and 3) to address concurrent validity with a performance-based measure of functioning (Test of Grocery Shopping Skills; TOGSS). Eighty-one adults with schizophrenia or schizoaffective disorder completed WCST and ROCFT learning measures and the TOGSS. Results indicated the various learning potential computational indices are intercorrelated and, similar to other studies, we found support for regression residuals and post-test scores as optimal indices. Further, we found modest relationships between the two learning potential measures and the TOGSS. These findings suggest learning potential includes both general and task-specific constructs but future research is needed to further explore this question. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Redox behaviors of iron by absorption spectroscopy and redox potential measurement

    International Nuclear Information System (INIS)

    Oh, Jae Yong

    2010-02-01

    This work is performed to study the redox (reduction/oxidation) behaviors of iron in aqueous system by a combination of absorption spectroscopy and redox potential measurements. There are many doubts on redox potential measurements generally showing low accuracies and high uncertainties. In the present study, redox potentials are measured by utilizing various redox electrodes such as Pt, Au, Ag, and glassy carbon (GC) electrodes. Measured redox potentials are compared with calculated redox potentials based on the chemical oxidation speciation of iron and thermodynamic data by absorption spectroscopy, which provides one of the sensitive and selective spectroscopic methods for the chemical speciation of Fe(II/III). From the comparison analyses, redox potential values measured by the Ag redox electrode are fairly consistent with those calculated by the chemical aqueous speciation of iron in the whole system. In summary, the uncertainties of measured redox potentials are closely related with the total Fe concentration and affected by the formation of mixed potentials due to Fe(III) precipitates in the pH range of 6 ∼ 9 beyond the solubility of Fe(III), whilst being independent of the initially prepared concentration ratios between Fe(II) and Fe(III)

  4. Psychometric considerations in the measurement of event-related brain potentials: Guidelines for measurement and reporting.

    Science.gov (United States)

    Clayson, Peter E; Miller, Gregory A

    2017-01-01

    Failing to consider psychometric issues related to reliability and validity, differential deficits, and statistical power potentially undermines the conclusions of a study. In research using event-related brain potentials (ERPs), numerous contextual factors (population sampled, task, data recording, analysis pipeline, etc.) can impact the reliability of ERP scores. The present review considers the contextual factors that influence ERP score reliability and the downstream effects that reliability has on statistical analyses. Given the context-dependent nature of ERPs, it is recommended that ERP score reliability be formally assessed on a study-by-study basis. Recommended guidelines for ERP studies include 1) reporting the threshold of acceptable reliability and reliability estimates for observed scores, 2) specifying the approach used to estimate reliability, and 3) justifying how trial-count minima were chosen. A reliability threshold for internal consistency of at least 0.70 is recommended, and a threshold of 0.80 is preferred. The review also advocates the use of generalizability theory for estimating score dependability (the generalizability theory analog to reliability) as an improvement on classical test theory reliability estimates, suggesting that the latter is less well suited to ERP research. To facilitate the calculation and reporting of dependability estimates, an open-source Matlab program, the ERP Reliability Analysis Toolbox, is presented. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Potential of optical spectral transmission measurements for joint inflammation measurements in rheumatoid arthritis patients

    Science.gov (United States)

    Meier, A. J. Louise; Rensen, Wouter H. J.; de Bokx, Pieter K.; de Nijs, Ron N. J.

    2012-08-01

    Frequent monitoring of rheumatoid arthritis (RA) patients enables timely treatment adjustments and improved outcomes. Currently this is not feasible due to a shortage of rheumatologists. An optical spectral transmission device is presented for objective assessment of joint inflammation in RA patients, while improving diagnostic accuracy and clinical workflow. A cross-sectional, nonrandomized observational study was performed with this device. In the study, 77 proximal interphalangeal (PIP) joints in 67 patients have been analyzed. Inflammation of these PIP joints was also assessed by a rheumatologist with a score varying from 1 (not inflamed) to 5 (severely inflamed). Out of 77 measurements, 27 were performed in moderate to strongly inflamed PIP joints. Comparison between the clinical assessment and an optical measurement showed a correlation coefficient r=0.63, p<0.001, 95% CI [0.47, 0.75], and a ROC curve (AUC=0.88) that shows a relative good specificity and sensitivity. Optical spectral transmission measurements in a single joint correlate with clinical assessment of joint inflammation, and therefore might be useful in monitoring joint inflammation in RA patients.

  6. Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade

    DEFF Research Database (Denmark)

    Horacek, J.; Adamek, J.; Müller, H.W.

    2010-01-01

    This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements of plasma density, potential and electron temperature in the edge plasma of tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate the credibility of the ball-pen probe. We demonstrate that floating...... potential fluctuations measured by a Langmuir probe are dominated by plasma electron temperature rather than potential. Spatial and temporal scales are found consistent with expectations based on interchange-driven turbulence. Conditionally averaged signals found for both potential and density are also...

  7. Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy

    International Nuclear Information System (INIS)

    Kumar, Bharat; Crittenden, Scott R

    2013-01-01

    We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson–Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length. (paper)

  8. Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy.

    Science.gov (United States)

    Kumar, Bharat; Crittenden, Scott R

    2013-11-01

    We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson-Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length.

  9. $L_{0}$ Gradient Projection.

    Science.gov (United States)

    Ono, Shunsuke

    2017-04-01

    Minimizing L 0 gradient, the number of the non-zero gradients of an image, together with a quadratic data-fidelity to an input image has been recognized as a powerful edge-preserving filtering method. However, the L 0 gradient minimization has an inherent difficulty: a user-given parameter controlling the degree of flatness does not have a physical meaning since the parameter just balances the relative importance of the L 0 gradient term to the quadratic data-fidelity term. As a result, the setting of the parameter is a troublesome work in the L 0 gradient minimization. To circumvent the difficulty, we propose a new edge-preserving filtering method with a novel use of the L 0 gradient. Our method is formulated as the minimization of the quadratic data-fidelity subject to the hard constraint that the L 0 gradient is less than a user-given parameter α . This strategy is much more intuitive than the L 0 gradient minimization because the parameter α has a clear meaning: the L 0 gradient value of the output image itself, so that one can directly impose a desired degree of flatness by α . We also provide an efficient algorithm based on the so-called alternating direction method of multipliers for computing an approximate solution of the nonconvex problem, where we decompose it into two subproblems and derive closed-form solutions to them. The advantages of our method are demonstrated through extensive experiments.

  10. Geomorphic controls on elevational gradients of species richness.

    Science.gov (United States)

    Bertuzzo, Enrico; Carrara, Francesco; Mari, Lorenzo; Altermatt, Florian; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2016-02-16

    Elevational gradients of biodiversity have been widely investigated, and yet a clear interpretation of the biotic and abiotic factors that determine how species richness varies with elevation is still elusive. In mountainous landscapes, habitats at different elevations are characterized by different areal extent and connectivity properties, key drivers of biodiversity, as predicted by metacommunity theory. However, most previous studies directly correlated species richness to elevational gradients of potential drivers, thus neglecting the interplay between such gradients and the environmental matrix. Here, we investigate the role of geomorphology in shaping patterns of species richness. We develop a spatially explicit zero-sum metacommunity model where species have an elevation-dependent fitness and otherwise neutral traits. Results show that ecological dynamics over complex terrains lead to the null expectation of a hump-shaped elevational gradient of species richness, a pattern widely observed empirically. Local species richness is found to be related to the landscape elevational connectivity, as quantified by a newly proposed metric that applies tools of complex network theory to measure the closeness of a site to others with similar habitat. Our theoretical results suggest clear geomorphic controls on elevational gradients of species richness and support the use of the landscape elevational connectivity as a null model for the analysis of the distribution of biodiversity.

  11. An improved potential drop method for measuring and monitoring defects in structures

    International Nuclear Information System (INIS)

    Oppermann, W.; Keller, H.P.

    1991-01-01

    In its advanced form, the direct-current potential probe measuring technique is a reliable and relatively exact procedure for measuring and monitoring surface defects. In addition, there is the possibility - important for practical purposes - of measuring cracks at the inaccessible side of a component part. The improved accuracy, in particular with regard to short defects, is based on advanced measuring techniques and calibration curves determined at the electrolytical tank. (orig./DG) [de

  12. A cradle-shaped gradient coil to expand the clear-bore width of an animal MRI scanner

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, K M; Gati, J S; Klassen, L M; Menon, R S [Centre for Functional and Metabolic Mapping, Robarts Research Institute, The University of Western Ontario, PO Box 5015, 100 Perth Drive, London, Ontario, N6A 5K8 (Canada)], E-mail: kgilbert@imaging.robarts.ca

    2010-01-21

    The never ending quest for higher magnetic field strengths in MRI and MRS has led to small and medium bore scanners at 9.4 T and above for both human and animal use; however, these bore diameters restrict the size of object that can be accommodated when using a conventional gradient coil. By replacing a cylindrical gradient-coil insert with a single-sided gradient coil, the scanner's functionality can be extended to include localized imaging of wider samples. As a prototype, a three-axis, cradle-shaped gradient coil was designed, fabricated and implemented in a 9.4 T animal MRI scanner. Since gradient fields are required only to be monotonic over the desired field of view, the cradle gradient coil was designed to produce high gradient efficiencies (up to 2.25 mT m{sup -1} A{sup -1} over a 5 cm imaging region) at the expense of gradient linearity. A dedicated three-dimensional algorithm was developed to correct the resultant image distortion. Preliminary images of a grid phantom and a mouse demonstrated the fidelity of the algorithm in correcting image distortion of greater than 200%. Eddy currents were measured along each gradient axis. A large 65.2 (Hz mT{sup -1} m) B{sub 0} eddy current was produced by the y-axis, suggesting potential limitations of single-sided gradient coils.

  13. Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

    Science.gov (United States)

    Peñuelas, J.; Guenther, A.; Rapparini, F.; Llusia, J.; Filella, I.; Seco, R.; Estiarte, M.; Mejia-Chang, M.; Ogaya, R.; Ibañez, J.; Sardans, J.; Castaño, L. M.; Turnipseed, A.; Duhl, T.; Harley, P.; Vila, J.; Estavillo, J. M.; Menéndez, S.; Facini, O.; Baraldi, R.; Geron, C.; Mak, J.; Patton, E. G.; Jiang, X.; Greenberg, J.

    2013-08-01

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest-warmest sites and optimal conditions in the wettest-coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC-MS, PTR-MS, meteorological sensors, O3 monitors,…) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2 mg m-2 h-1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6 mg m-2 h-1 for

  14. Out-of-equilibrium body potential measurements in pseudo-MOSFET for sensing applications

    Science.gov (United States)

    Benea, Licinius; Bawedin, Maryline; Delacour, Cécile; Ionica, Irina

    2018-05-01

    The aim of this paper is to present the out-of-equilibrium body potential behaviour in the Ψ-MOSFET configuration. Consistent measurements in this experimental setup succeeded in providing a substantial understanding of its characteristics in the depletion region. The final objective of this work is to envision this new measurement technique for biochemical sensor applications. Among its advantages, the most important are its simplicity, the good sensitivity, the measurement of a potential instead of a current and the low bias needed for detection compared to the conventional drain current measurements.

  15. Electrochemical potential measurements in boiling water reactors; relation to water chemistry and stress corrosion

    International Nuclear Information System (INIS)

    Indig, M.E.; Cowan, R.L.

    1981-01-01

    Electrochemical potential measurements were performed in operating boiling water reactors to determine the range of corrosion potentials that exist from cold standby to full power operation and the relationship of these measurements to reactor water chemistry. Once the corrosion potentials were known, experiments were performed in the laboratory under electrochemical control to determine potentials and equivalent dissolved oxygen concentrations where intergranular stress corrosion cracking (IGSCC) would and would not occur on welded Type-304 stainless steel. At 274 0 C, cracking occurred at potentials that were equivalent to dissolved oxygen concentration > 40 to 50 ppb. With decreasing temperature, IGSCC became more difficult and only severely sensitized stainless steel would crack. Recent in-reactor experiments combined with the previous laboratory data, have shown that injection of small concentrations of hydrogen during reactor operation can cause a significant decrease in corrosion potential which should cause immunity to IGSCC. (author)

  16. An induced current method for measuring zeta potential of electrolyte solution-air interface.

    Science.gov (United States)

    Song, Yongxin; Zhao, Kai; Wang, Junsheng; Wu, Xudong; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

    2014-02-15

    This paper reports a novel and very simple method for measuring the zeta potential of electrolyte solution-air interface. When a measuring electrode contacts the electrolyte solution-air interface, an electrical current will be generated due to the potential difference between the electrode-air surface and the electrolyte solution-air interface. The amplitude of the measured electric signal is linearly proportional to this potential difference; and depends only on the zeta potential at the electrolyte solution-air interface, regardless of the types and concentrations of the electrolyte. A correlation between the zeta potential and the measured voltage signal is obtained based on the experimental data. Using this equation, the zeta potential of any electrolyte solution-air interface can be evaluated quickly and easily by inserting an electrode through the electrolyte solution-air interface and measuring the electrical signal amplitude. This method was verified by comparing the obtained results of NaCl, MgCl2 and CaCl2 solutions of different pH values and concentrations with the zeta potential data reported in the published journal papers. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Reconstruction from one boundary measurement of a potential homogeneous of degree zero

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Knudsen, Kim

    We consider the inverse boundary value problem concerning the determination and reconstruction of an unknown potential in a Schrödinger equation in a bounded domain from measurements on the boundary of the domain. For the special case of a small potential homogeneous of degree zero we show that one...

  18. Reconstruction from one boundary measurement of a potential homogeneous of degree zero

    DEFF Research Database (Denmark)

    Cornean, Horia; Knudsen, Kim

    2006-01-01

    We consider the inverse boundary value problem concerning the determination and reconstruction of an unknown potential in a Schrödinger equation in a bounded domain from measurements on the boundary of the domain. For the special case of a small potential homogeneous of degree zero we show that one...

  19. Investigating transfer gate potential barrier by feed-forward effect measurement

    NARCIS (Netherlands)

    Xu, Y.; Ge, X.; Theuwissen, A.J.P.

    2015-01-01

    In a 4T pixel, the transfer gate (TG) “OFF” surface potential is one of the important parameters, which determines the pinned photodiode (PPD) full well capacity. The feed-forward effect measurement is a powerful tool to characterize the relationship of the PPD injection potential and the

  20. Surface Complexation Modeling of Calcite Zeta Potential Measurement in Mixed Brines for Carbonate Wettability Characterization

    Science.gov (United States)

    Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.

    2017-12-01

    We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).

  1. Testing the limits of gradient sensing.

    Directory of Open Access Journals (Sweden)

    Vinal Lakhani

    2017-02-01

    Full Text Available The ability to detect a chemical gradient is fundamental to many cellular processes. In multicellular organisms gradient sensing plays an important role in many physiological processes such as wound healing and development. Unicellular organisms use gradient sensing to move (chemotaxis or grow (chemotropism towards a favorable environment. Some cells are capable of detecting extremely shallow gradients, even in the presence of significant molecular-level noise. For example, yeast have been reported to detect pheromone gradients as shallow as 0.1 nM/μm. Noise reduction mechanisms, such as time-averaging and the internalization of pheromone molecules, have been proposed to explain how yeast cells filter fluctuations and detect shallow gradients. Here, we use a Particle-Based Reaction-Diffusion model of ligand-receptor dynamics to test the effectiveness of these mechanisms and to determine the limits of gradient sensing. In particular, we develop novel simulation methods for establishing chemical gradients that not only allow us to study gradient sensing under steady-state conditions, but also take into account transient effects as the gradient forms. Based on reported measurements of reaction rates, our results indicate neither time-averaging nor receptor endocytosis significantly improves the cell's accuracy in detecting gradients over time scales associated with the initiation of polarized growth. Additionally, our results demonstrate the physical barrier of the cell membrane sharpens chemical gradients across the cell. While our studies are motivated by the mating response of yeast, we believe our results and simulation methods will find applications in many different contexts.

  2. Gradient pre-emphasis to counteract first-order concomitant fields on asymmetric MRI gradient systems.

    Science.gov (United States)

    Tao, Shengzhen; Weavers, Paul T; Trzasko, Joshua D; Shu, Yunhong; Huston, John; Lee, Seung-Kyun; Frigo, Louis M; Bernstein, Matt A

    2017-06-01

    To develop a gradient pre-emphasis scheme that prospectively counteracts the effects of the first-order concomitant fields for any arbitrary gradient waveform played on asymmetric gradient systems, and to demonstrate the effectiveness of this approach using a real-time implementation on a compact gradient system. After reviewing the first-order concomitant fields that are present on asymmetric gradients, we developed a generalized gradient pre-emphasis model assuming arbitrary gradient waveforms to counteract their effects. A numerically straightforward, easily implemented approximate solution to this pre-emphasis problem was derived that was compatible with the current hardware infrastructure of conventional MRI scanners for eddy current compensation. The proposed method was implemented on the gradient driver subsystem, and its real-time use was tested using a series of phantom and in vivo data acquired from two-dimensional Cartesian phase-difference, echo-planar imaging, and spiral acquisitions. The phantom and in vivo results demonstrated that unless accounted for, first-order concomitant fields introduce considerable phase estimation error into the measured data and result in images with spatially dependent blurring/distortion. The resulting artifacts were effectively prevented using the proposed gradient pre-emphasis. We have developed an efficient and effective gradient pre-emphasis framework to counteract the effects of first-order concomitant fields of asymmetric gradient systems. Magn Reson Med 77:2250-2262, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  3. Measurement of Streaming Potential in Downhole Application: An Insight for Enhanced Oil Recovery Monitoring

    Directory of Open Access Journals (Sweden)

    Tengku Mohd Tengku Amran

    2017-01-01

    Full Text Available Downhole monitoring using streaming potential measurement has been developing in order to respond to actual reservoir condition. Most studies have emphasized on monitoring water flooding at various reservoir condition and improving the approaches of measurement. Enhanced Oil Recovery (EOR could significantly improve oil recovery and the efficiency of the process should be well-monitored. Alkaline-surfactant-polymer (ASP flooding is the most promising chemical EOR method due to its synergy of alkaline, surfactant and polymer, which could enhance the extraction of residual oil. However, limited studies have been focused on the application of streaming potential in EOR processes, particularly ASP. Thus, this paper aims to review the streaming potential measurement in downhole monitoring with an insight for EOR application and propose the potential measurement in monitoring ASP flooding. It is important for a preliminary study to investigate the synergy in ASP and the effects on oil recovery. The behaviour of streaming potential should be investigated when the environment of porous media changes with respect to ASP flooding. Numerical model can be generated from the experimental data to forecast the measured streaming potential signal during production associated with ASP flooding. Based on the streaming potential behaviour on foam assisted water alternate gas (FAWAG and water alternate gas (WAG processes, it is expected that the streaming potential could change significantly when ASP flooding alters the environment and surface properties of porous media. The findings could provide new prospect and knowledge in the relationship between streaming potential and ASP mechanisms, which could be a potential approach in monitoring the efficiency of the process.

  4. Influence of the Ambient Electric Field on Measurements of the Actively Controlled Spacecraft Potential by MMS

    Science.gov (United States)

    Torkar, K.; Nakamura, R.; Andriopoulou, M.; Giles, B. L.; Jeszenszky, H.; Khotyaintsev, Y. V.; Lindqvist, P.-A.; Torbert, R. B.

    2017-12-01

    Space missions with sophisticated plasma instrumentation such as Magnetospheric Multiscale, which employs four satellites to explore near-Earth space benefit from a low electric potential of the spacecraft, to improve the plasma measurements and therefore carry instruments to actively control the potential by means of ion beams. Without control, the potential varies in anticorrelation with plasma density and temperature to maintain an equilibrium between the plasma current and the one of photoelectrons produced at the surface and overcoming the potential barrier. A drawback of the controlled, almost constant potential is the difficulty to use it as convenient estimator for plasma density. This paper identifies a correlation between the spacecraft potential and the ambient electric field, both measured by double probes mounted at the end of wire booms, as the main responsible for artifacts in the potential data besides the known effect of the variable photoelectron production due to changing illumination of the surface. It is shown that the effect of density variations is too weak to explain the observed correlation with the electric field and that a correction of the artifacts can be achieved to enable the reconstruction of the uncontrolled potential and plasma density in turn. Two possible mechanisms are discussed: the asymmetry of the current-voltage characteristic determining the probe to plasma potential and the fact that a large equipotential structure embedded in an electric field results in asymmetries of both the emission and spatial distribution of photoelectrons, which results in an increase of the spacecraft potential.

  5. Measurement of plasma potential and electron temperature by ball-pen probes in RFX-MOD

    International Nuclear Information System (INIS)

    Brotankova, J.; Adamek, J.; Stockel, J.; Martines, E.; Spolaore, M.; Cavazzana, R.; Serianni, G.; Vianello, N.; Zuin, M.

    2009-01-01

    The ball-pen probe (BPP) is an innovative electric probe for direct measurements of the plasma potential. This probe was developed in IPP Prague and it is based on the Katsumata probe concept. Combined measurements of the plasma potential by a BPP and floating potential by a Langmuir probe provide also the value of the electron temperature. First test of the BPP on the RFX-mod reversed field pinch in Padova has been performed in November 2006. The BPP head, made of boron nitride, is equipped with four graphite collectors, which are positioned at four different radial positions h inside four shafts hollow into the probe head. The radial profile of the plasma potential and also the electron temperature were measured

  6. Effects of grid potentials and geometric dimensions on the multi-electrode probe measurements

    International Nuclear Information System (INIS)

    Elakshar, F.F.; Abdul El-Raoof, W.S.

    1986-01-01

    A hollow anode plasma source is used to produce low temperature plasma which is injected into a magnetic field. The effects of the grid potentials, collector potential and geometric dimensions on multi-electrode probe measurements, in the presence of a magnetic field, are investigated. It is found that the collector potential plays a substantial role in the measurement of temperatures and densities. The finite-size of the geometric dimensions of the probe influences the data and high values of temperature are obtained when a small ratio of the discriminator grid radius to the separation distance is used, providing that the repeller grid potentials is low. Reliable measurements can only be obtained if the multi-electrode probe is used in the presence of a magnetic field strong enough to reduce electron Larmor radii to less than the grid mesh radius. (author)

  7. Plasma potential formation and measurement in TMX-U and MFTF-B

    International Nuclear Information System (INIS)

    Grubb, D.P.

    1984-01-01

    Tandem mirrors control the axial variation of the plasma potential to create electrostatic plugs that improve the axial confinement of central cell ions and, in a thermal barrier tandem mirror, control the electron axial heat flow. Measurements of the spatial and temporal variations of the plasma potential are, therefore, important to the understanding of confinement in a tandem mirror. In this paper we discuss potential formation in a thermal barrier tandem mirror and examine the diagnostics and data obtained on the TMX-U device, including measurements of the thermal barrier potential profile using a diagnostic neutral beam and charged particle energy-spectroscopy. We then describe the heavy ion beam probe and other new plasma potential diagnostics that are under development for TMX-U and MFTF-B and examine problem areas where additional diagnostic development is desirable

  8. TEK twisted gradient flow running coupling

    CERN Document Server

    Pérez, Margarita García; Keegan, Liam; Okawa, Masanori

    2014-01-01

    We measure the running of the twisted gradient flow coupling in the Twisted Eguchi-Kawai (TEK) model, the SU(N) gauge theory on a single site lattice with twisted boundary conditions in the large N limit.

  9. Gravity gradient preprocessing at the GOCE HPF

    Science.gov (United States)

    Bouman, J.; Rispens, S.; Gruber, T.; Schrama, E.; Visser, P.; Tscherning, C. C.; Veicherts, M.

    2009-04-01

    One of the products derived from the GOCE observations are the gravity gradients. These gravity gradients are provided in the Gradiometer Reference Frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. In order to use these gravity gradients for application in Earth sciences and gravity field analysis, additional pre-processing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and non-tidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/f behaviour for low frequencies. In the outlier detection the 1/f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10-3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10-2 level with this method.

  10. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  11. Sea-to-air flux of dimethyl sulfide in the South and North Pacific Ocean as measured by proton transfer reaction-mass spectrometry coupled with the gradient flux technique

    Science.gov (United States)

    Omori, Yuko; Tanimoto, Hiroshi; Inomata, Satoshi; Ikeda, Kohei; Iwata, Toru; Kameyama, Sohiko; Uematsu, Mitsuo; Gamo, Toshitaka; Ogawa, Hiroshi; Furuya, Ken

    2017-07-01

    Exchange of dimethyl sulfide (DMS) between the surface ocean and the lower atmosphere was examined by using proton transfer reaction-mass spectrometry coupled with the gradient flux (PTR-MS/GF) system. We deployed the PTR-MS/GF system and observed vertical gradients of atmospheric DMS just above the sea surface in the subtropical and transitional South Pacific Ocean and the subarctic North Pacific Ocean. In total, we obtained 370 in situ profiles, and of these we used 46 data sets to calculate the sea-to-air flux of DMS. The DMS flux determined was in the range from 1.9 to 31 μmol m-2 d-1 and increased with wind speed and biological activity, in reasonable accordance with previous observations in the open ocean. The gas transfer velocity of DMS derived from the PTR-MS/GF measurements was similar to either that of DMS determined by the eddy covariance technique or that of insoluble gases derived from the dual tracer experiments, depending on the observation sites located in different geographic regions. When atmospheric conditions were strongly stable during the daytime in the subtropical ocean, the PTR-MS/GF observations captured a daytime versus nighttime difference in DMS mixing ratios in the surface air overlying the ocean surface. The difference was mainly due to the sea-to-air DMS emissions and stable atmospheric conditions, thus affecting the gradient of DMS. This indicates that the DMS gradient is strongly controlled by diurnal variations in the vertical structure of the lower atmosphere above the ocean surface.

  12. Ground potential rise on the high voltage substation during lightning strike measurement and simulation results

    Energy Technology Data Exchange (ETDEWEB)

    Wiater, Jaroslaw [Bialystok Technical University (Poland). Electrical Dept.], E-mail: jaroslawwiater@we.pb.edu.pl

    2007-07-01

    This paper will present a ground potential rise (GPR) measurement results. All measurements were made during normal work of the real high voltage substation and according a special procedure developed for this occasion. This procedure does not influence on the protection relays and ensures a proper work of the substation even for 6 kV surges. During measurements current and voltage surges were produced by the impulse generator - UCS 500M6B. Measurement results are compared to simulation results performed in CDEGS software for the same initial conditions. (author)

  13. Sound beam manipulation based on temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Feng [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Quan, Li; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-10-28

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

  14. Quaternion Gradient and Hessian

    OpenAIRE

    Xu, Dongpo; Mandic, Danilo P.

    2014-01-01

    The optimization of real scalar functions of quaternion variables, such as the mean square error or array output power, underpins many practical applications. Solutions typically require the calculation of the gradient and Hessian. However, real functions of quaternion variables are essentially nonanalytic, which are prohibitive to the development of quaternion-valued learning systems. To address this issue, we propose new definitions of quaternion gradient and Hessian, based on the novel gen...

  15. In situ measurements of tritium evapotranspiration (³H-ET) flux over grass and soil using the gradient and eddy covariance experimental methods and the FAO-56 model.

    Science.gov (United States)

    Connan, O; Maro, D; Hébert, D; Solier, L; Caldeira Ideas, P; Laguionie, P; St-Amant, N

    2015-10-01

    The behaviour of tritium in the environment is linked to the water cycle. We compare three methods of calculating the tritium evapotranspiration flux from grassland cover. The gradient and eddy covariance methods, together with a method based on the theoretical Penmann-Monteith model were tested in a study carried out in 2013 in an environment characterised by high levels of tritium activity. The results show that each of the three methods gave similar results. The various constraints applying to each method are discussed. The results show a tritium evapotranspiration flux of around 15 mBq m(-2) s(-1) in this environment. These results will be used to improve the entry parameters for the general models of tritium transfers in the environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Unimodal and crossmodal gradients of spatial attention

    DEFF Research Database (Denmark)

    Föcker, J.; Hötting, K.; Gondan, Matthias

    2010-01-01

    Behavioral and event-related potential (ERP) studies have shown that spatial attention is gradually distributed around the center of the attentional focus. The present study compared uni- and crossmodal gradients of spatial attention to investigate whether the orienting of auditory and visual...... spatial attention is based on modality specific or supramodal representations of space. Auditory and visual stimuli were presented from five speaker locations positioned in the right hemifield. Participants had to attend to the innermost or outmost right position in order to detect either visual...... or auditory deviant stimuli. Detection rates and event-related potentials (ERPs) indicated that spatial attention is distributed as a gradient. Unimodal spatial ERP gradients correlated with the spatial resolution of the modality. Crossmodal spatial gradients were always broader than the corresponding...

  17. A Complete Characterization of Potential Compensation Tests of Hicksian Welfare Measures

    OpenAIRE

    Donald Keenan; Arthur Snow

    1999-01-01

    In this paper, the authors present complete characterizations of the compensation tests for potential Pareto superiority proposed by Kaldor, Hicks, and Samuelson in terms of the aggregate Hicksian measures of income compensation, including compensating and equivalent variations. The key to obtaining these characterizations lies in recognizing that each potential compensation test entails a search over possible outcomes, rather than a comparison of only the new and original outcomes, as with s...

  18. Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in a Dune Sand Aquifer in Western Saudi Arabia: Assessment of Evaporation Loss for Design of an MAR System

    KAUST Repository

    Mughal, Iqra; Jadoon, Khan; Mai, Paul Martin; Al-Mashharawi, Samir; Missimer, Thomas

    2015-01-01

    A component of designing a managed aquifer recharge system in a dune aquifer is the control of diffusive evaporative loss of water which is governed by the physical properties of the sediments and the position of the water table. A critical water table position is the “extinction depth”, below which no further loss of water occurs via diffusion. Field experiments were conducted to measure the extinction depth of sediments taken from a typical dune field in the region. The soil grain size characteristics, laboratory porosity, and saturated hydraulic conductivity were measured. The sand is classified as well-sorted, very fine sand with a mean grain diameter of 0.15 mm. Soil moisture gradients and diffusion loss rates were measured using sensors in a non-weighing lysimeter that was placed below land surface. The sand was saturated carefully with water from the bottom to the top and was exposed to the natural climate for a period of about two months. The moisture gradient showed a gradual decline during measurement until extinction depth was reached at about 100 cm below surface after 56 days. Diurnal temperature changes were observed in the upper 75 cm of the column and were negligible at greater depth.

  19. Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in a Dune Sand Aquifer in Western Saudi Arabia: Assessment of Evaporation Loss for Design of an MAR System

    Directory of Open Access Journals (Sweden)

    Iqra Mughal

    2015-12-01

    Full Text Available A component of designing a managed aquifer recharge system in a dune aquifer is the control of diffusive evaporative loss of water which is governed by the physical properties of the sediments and the position of the water table. A critical water table position is the “extinction depth”, below which no further loss of water occurs via diffusion. Field experiments were conducted to measure the extinction depth of sediments taken from a typical dune field in the region. The soil grain size characteristics, laboratory porosity, and saturated hydraulic conductivity were measured. The sand is classified as well-sorted, very fine sand with a mean grain diameter of 0.15 mm. Soil moisture gradients and diffusion loss rates were measured using sensors in a non-weighing lysimeter that was placed below land surface. The sand was saturated carefully with water from the bottom to the top and was exposed to the natural climate for a period of about two months. The moisture gradient showed a gradual decline during measurement until extinction depth was reached at about 100 cm below surface after 56 days. Diurnal temperature changes were observed in the upper 75 cm of the column and were negligible at greater depth.

  20. Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in a Dune Sand Aquifer in Western Saudi Arabia: Assessment of Evaporation Loss for Design of an MAR System

    KAUST Repository

    Mughal, Iqra

    2015-12-10

    A component of designing a managed aquifer recharge system in a dune aquifer is the control of diffusive evaporative loss of water which is governed by the physical properties of the sediments and the position of the water table. A critical water table position is the “extinction depth”, below which no further loss of water occurs via diffusion. Field experiments were conducted to measure the extinction depth of sediments taken from a typical dune field in the region. The soil grain size characteristics, laboratory porosity, and saturated hydraulic conductivity were measured. The sand is classified as well-sorted, very fine sand with a mean grain diameter of 0.15 mm. Soil moisture gradients and diffusion loss rates were measured using sensors in a non-weighing lysimeter that was placed below land surface. The sand was saturated carefully with water from the bottom to the top and was exposed to the natural climate for a period of about two months. The moisture gradient showed a gradual decline during measurement until extinction depth was reached at about 100 cm below surface after 56 days. Diurnal temperature changes were observed in the upper 75 cm of the column and were negligible at greater depth.

  1. Forest gradient response in Sierran landscapes: the physical template

    Science.gov (United States)

    Urban, Dean L.; Miller, Carol; Halpin, Patrick N.; Stephenson, Nathan L.

    2000-01-01

    Vegetation pattern on landscapes is the manifestation of physical gradients, biotic response to these gradients, and disturbances. Here we focus on the physical template as it governs the distribution of mixed-conifer forests in California's Sierra Nevada. We extended a forest simulation model to examine montane environmental gradients, emphasizing factors affecting the water balance in these summer-dry landscapes. The model simulates the soil moisture regime in terms of the interaction of water supply and demand: supply depends on precipitation and water storage, while evapotranspirational demand varies with solar radiation and temperature. The forest cover itself can affect the water balance via canopy interception and evapotranspiration. We simulated Sierran forests as slope facets, defined as gridded stands of homogeneous topographic exposure, and verified simulated gradient response against sample quadrats distributed across Sequoia National Park. We then performed a modified sensitivity analysis of abiotic factors governing the physical gradient. Importantly, the model's sensitivity to temperature, precipitation, and soil depth varies considerably over the physical template, particularly relative to elevation. The physical drivers of the water balance have characteristic spatial scales that differ by orders of magnitude. Across large spatial extents, temperature and precipitation as defined by elevation primarily govern the location of the mixed conifer zone. If the analysis is constrained to elevations within the mixed-conifer zone, local topography comes into play as it influences drainage. Soil depth varies considerably at all measured scales, and is especially dominant at fine (within-stand) scales. Physical site variables can influence soil moisture deficit either by affecting water supply or water demand; these effects have qualitatively different implications for forest response. These results have clear implications about purely inferential approaches

  2. Measurements of fatigue crack length at elevated temperature by D. C. electrical potential method

    International Nuclear Information System (INIS)

    Matsumoto, Masakatsu; Yamauchi, Isamu; Kodaira, Tsuneo

    1982-07-01

    The direct current (d.c.) electrical potential method was used to automatically and continuously measure the crack length in cyclic crack growth test at elevated temperature. This report describes some results concerning the calibration curves, i.e. the relation between electrical potential change and amount of crack extention, using SUS 304 and 2 1/4Cr-1Mo steels. It can be concluded that the measurements of fatigue crack length is possible even at elevated temperature as well as at room temperature with the equivalent accuracy. (author)

  3. Assessment of clean development mechanism potential of large-scale energy efficiency measures in heavy industries

    International Nuclear Information System (INIS)

    Hayashi, Daisuke; Krey, Matthias

    2007-01-01

    This paper assesses clean development mechanism (CDM) potential of large-scale energy efficiency measures in selected heavy industries (iron and steel, cement, aluminium, pulp and paper, and ammonia) taking India and Brazil as examples of CDM project host countries. We have chosen two criteria for identification of the CDM potential of each energy efficiency measure: (i) emission reductions volume (in CO 2 e) that can be expected from the measure and (ii) likelihood of the measure passing the additionality test of the CDM Executive Board (EB) when submitted as a proposed CDM project activity. The paper shows that the CDM potential of large-scale energy efficiency measures strongly depends on the project-specific and country-specific context. In particular, technologies for the iron and steel industry (coke dry quenching (CDQ), top pressure recovery turbine (TRT), and basic oxygen furnace (BOF) gas recovery), the aluminium industry (point feeder prebake (PFPB) smelter), and the pulp and paper industry (continuous digester technology) offer promising CDM potential

  4. Development of a Corrosion Potential Measuring System Based on the Generalization of DACS Physical Scale Modeling

    Directory of Open Access Journals (Sweden)

    Song Dalei

    2015-01-01

    Full Text Available A feasible method in evaluating the protection effect and corrosion state of marine cathodic protection (CP systems is collecting sufficient electric potential data around a submarine pipeline and then establishing the mapping relations between these data and corrosion states of pipelines. However, it is difficult for scientists and researchers to obtain those data accurately due to the harsh marine environments and absence of dedicated potential measurement device. In this paper, to alleviate these two problems, firstly, the theory of dimension and conductivity scaling (DACS physical scale modeling of marine impressed current cathodic protection (ICCP systems is generalized to marine CP systems, secondly, a potential measurement device is developed specially and analogue experiment is designed according to DACS physical scale modeling to verify the feasibility of the measuring system. The experimental results show that 92 percent of the measurement errors are less than 0.25mv, thereby providing an economical and feasible measuring system to get electric potential data around an actual submarine pipeline under CP.

  5. Gradient Alloy for Optical Packaging

    Data.gov (United States)

    National Aeronautics and Space Administration — Advances in additive manufacturing, such as Laser Engineered Net Shaping (LENS), enables the fabrication of compositionally gradient microstructures, i.e. gradient...

  6. Method for Estimating Evaporative Potential (IM/CLO) from ASTM Standard Single Wind Velocity Measures

    Science.gov (United States)

    2016-08-10

    IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY MEASURES DISCLAIMER The opinions or assertions contained herein are the private views of the...USARIEM TECHNICAL REPORT T16-14 METHOD FOR ESTIMATING EVAPORATIVE POTENTIAL (IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY... ASTM STANDARD SINGLE WIND VELOCITY MEASURES Adam W. Potter Biophysics and Biomedical Modeling Division U.S. Army Research Institute of Environmental

  7. CFRMF neutron flux gradient and spectral determinations

    International Nuclear Information System (INIS)

    Rogers, J.W.; Turk, E.H.; Hogg, C.H.

    1976-01-01

    Recently more accurate and complete measurements of the flux gradient have been measured by the activation of 235 U and Au samples. Neutron spectrum characteristics were studied by making activation measurements with and without the ends of the CFRMF test region plugged with 10 B. These measurements define the flux gradient to +-1 to 2% and indicate there is no detectable streaming of thermal or resonance neutrons from the ends in the central 30 cm of the CFRMF test region. Measurements of the Cd ratio of Au foil activations were conducted and these results also indicate there is no streaming of thermal and resonance neutrons into the CFRMF test region

  8. Asymmetric Uncertainty Expression for High Gradient Aerodynamics

    Science.gov (United States)

    Pinier, Jeremy T

    2012-01-01

    When the physics of the flow around an aircraft changes very abruptly either in time or space (e.g., flow separation/reattachment, boundary layer transition, unsteadiness, shocks, etc), the measurements that are performed in a simulated environment like a wind tunnel test or a computational simulation will most likely incorrectly predict the exact location of where (or when) the change in physics happens. There are many reasons for this, includ- ing the error introduced by simulating a real system at a smaller scale and at non-ideal conditions, or the error due to turbulence models in a computational simulation. The un- certainty analysis principles that have been developed and are being implemented today do not fully account for uncertainty in the knowledge of the location of abrupt physics changes or sharp gradients, leading to a potentially underestimated uncertainty in those areas. To address this problem, a new asymmetric aerodynamic uncertainty expression containing an extra term to account for a phase-uncertainty, the magnitude of which is emphasized in the high-gradient aerodynamic regions is proposed in this paper. Additionally, based on previous work, a method for dispersing aerodynamic data within asymmetric uncer- tainty bounds in a more realistic way has been developed for use within Monte Carlo-type analyses.

  9. Measuring the impact of efficient household travel decisions on potential travel time savings and accessibility gains

    Energy Technology Data Exchange (ETDEWEB)

    Recker, W.W.; McNally, M.G. [University of California, Irvine (United States). Institute of Transportation Studies, Department of Civil and Environmental Engineering; Chen, C. [Ming-Chuan University, Taiwan (China). Department of Tourism Industry

    2001-07-01

    Using the conceptual framework of time-space geography, this paper incorporates both spatio-temporal constraints and household interaction effects into a meaningful measure of the potential of a household to interact with the built environment. Within this context, personal accessibility is described as a measure of the potential ability of individuals within a household not only to reach activity opportunities, but to do so with sufficient time available for participation in those activities, subject to the spatio-temporal constraints imposed by their daily obligations and transportation supply environment. The incorporation of activity-based concepts in the measurement of accessibility as a product of travel time savings not only explicitly acknowledges a temporal dimension in assessing the potential for spatial interaction but also expands the applicability of accessibility consideration to such real-world policy options as the promotion of ride-sharing and trip chaining behaviors. An empirical application of the model system provides an indication of the potential of activity-based modeling approaches to assess the bounds on achievable improvements in accessibility and travel time based on daily household activity patterns. It also provides an assessment of roles for trip chaining and ride-sharing as potentially effective methods to facilitate transportation policy objectives. (author)

  10. Applied potential tomography. A new noninvasive technique for measuring gastric emptying

    International Nuclear Information System (INIS)

    Avill, R.; Mangnall, Y.F.; Bird, N.C.; Brown, B.H.; Barber, D.C.; Seagar, A.D.; Johnson, A.G.; Read, N.W.

    1987-01-01

    Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant

  11. Applied potential tomography. A new noninvasive technique for measuring gastric emptying

    Energy Technology Data Exchange (ETDEWEB)

    Avill, R.; Mangnall, Y.F.; Bird, N.C.; Brown, B.H.; Barber, D.C.; Seagar, A.D.; Johnson, A.G.; Read, N.W.

    1987-04-01

    Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant.

  12. Standard test method for measurement of corrosion potentials of Aluminum alloys

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    1.1 This test method covers a procedure for measurement of the corrosion potential (see Note 1) of an aluminum alloy in an aqueous solution of sodium chloride with enough hydrogen peroxide added to provide an ample supply of cathodic reactant. Note 1—The corrosion potential is sometimes referred to as the open-circuit solution or rest potential. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  13. Argon intermolecular potential from a measurement of the total scattering cross-section

    International Nuclear Information System (INIS)

    Wong, Y.W.

    1975-01-01

    An inversion method to obtain accurate intermolecular potentials from experimental total cross section measurements is presented. This method is based on the high energy Massey--Smith approximation. The attractive portion of the potential is represented by a multi-parameter spline function and the repulsive part by a Morse function. The best fit potential is obtained by a least squares minimization based on comparison of experimental cross sections with those obtained by a Fourier transform of the reduced Massey--Smith phase shift curve. An experimental method was developed to obtain the total cross sections needed for the above inversion procedure. In this technique, integral cross sections are measured at various resolutions and the total cross section is obtained by extrapolating to infinite resolution. Experimental results obtained for the Ar--Ar system are in excellent agreement with total cross sections calculated using the Barker-Fisher-Watts potential. Inversion of the data to obtain a potential distinguishable from the BFW-potential requires an extension of the method based on the Massey--Smith approximation to permit use of JWKB phase shifts and was not attempted

  14. High Gradient Accelerator Research

    International Nuclear Information System (INIS)

    Temkin, Richard

    2016-01-01

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  15. Measurements of a potential interference with laser-induced fluorescence measurements of ambient OH from the ozonolysis of biogenic alkenes

    Science.gov (United States)

    Rickly, Pamela; Stevens, Philip S.

    2018-01-01

    Reactions of the hydroxyl radical (OH) play a central role in the chemistry of the atmosphere, and measurements of its concentration can provide a rigorous test of our understanding of atmospheric oxidation. Several recent studies have shown large discrepancies between measured and modeled OH concentrations in forested areas impacted by emissions of biogenic volatile organic compounds (BVOCs), where modeled concentrations were significantly lower than measurements. A potential reason for some of these discrepancies involves interferences associated with the measurement of OH using the laser-induced fluorescence-fluorescence assay by gas expansion (LIF-FAGE) technique in these environments. In this study, a turbulent flow reactor operating at atmospheric pressure was coupled to a LIF-FAGE cell and the OH signal produced from the ozonolysis of α-pinene, β-pinene, ocimene, isoprene, and 2-methyl-3-buten-2-ol (MBO) was measured. To distinguish between OH produced from the ozonolysis reactions and any OH artifact produced inside the LIF-FAGE cell, an external chemical scrubbing technique was used, allowing for the direct measurement of any interference. An interference under high ozone (between 2 × 1013 and 10 × 1013 cm-3) and BVOC concentrations (between approximately 0.1 × 1012 and 40 × 1012 cm-3) was observed that was not laser generated and was independent of the ozonolysis reaction time. For the ozonolysis of α- and β-pinene, the observed interference accounted for approximately 40 % of the total OH signal, while for the ozonolysis of ocimene the observed interference accounted for approximately 70 % of the total OH signal. Addition of acetic acid to the reactor eliminated the interference, suggesting that the source of the interference in these experiments involved the decomposition of stabilized Criegee intermediates (SCIs) inside the FAGE detection cell. Extrapolation of these measurements to ambient concentrations suggests that these interferences

  16. Electron beam potential measurements on an inductive-store, opening-switch accelerator

    International Nuclear Information System (INIS)

    Riordan, J.C.; Goyer, J.R.; Kortbawi, D.; Meachum, J.S.; Mendenhall, R.S.; Roth, I.S.

    1993-01-01

    Direct measurement of the accelerating potential in a relativistic electron beam accelerator is difficult, particularly when the diode is downstream from a plasma opening switch. An indirect potential measurement can be obtained from the high energy tail of the bremsstrahlung spectrum generated as the electron beam strikes the anode. The authors' time-resolved spectrometer contains 7 silicon pin diode detectors filtered with 2 to 15 mm of lead to span an electron energy range of 0.5 to 2 MeV. A Monte-Carlo transport code was used to provide calibration curves, and the resulting potential measurements have been confirmed in experiments on the PITHON accelerator. The spectrometer has recently been deployed on PM1, an inductive-store, opening-switch testbed. The diode voltage measurements from the spectrometer are in good agreement with the diode voltage measured upstream and corrected using transmission line relations. The x-ray signal and spectral voltage rise 10 ns later than the corrected electrical voltage, however, indicating plasma motion between the opening switch and the diode

  17. Standard test method for measurement of oxidation-reduction potential (ORP) of soil

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a procedure and related test equipment for measuring oxidation-reduction potential (ORP) of soil samples removed from the ground. 1.2 The procedure in Section 9 is appropriate for field and laboratory measurements. 1.3 Accurate measurement of oxidation-reduction potential aids in the analysis of soil corrosivity and its impact on buried metallic structure corrosion rates. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  18. Detection of microbial contaminations in drinking water using ATP measurements – evaluating potential for online monitoring

    DEFF Research Database (Denmark)

    Vang, Óluva Karin; Corfitzen, Charlotte B.; Albrechtsen, Hans-Jørgen

    2011-01-01

    There is an increasing call for fast and reliable methods for continuous monitoring of microbial drinking water quality in order to protect public health. The potential for Adenosine triphosphate (ATP) measurements as a real-time analysis for continuous monitoring of microbial drinking water...... quality was investigated through simulation of two contamination scenarios, i.e. drinking water contaminated with waste water and surface water at various concentrations. With ATP measurements it was possible to detect waste water diluted 1000-10,000 times in drinking water depending on sensitivity...... of reagent kit. Surface water diluted 100-1000 times was detected in drinking water with ATP measurements. ATP has the potential as an early warning tool, especially in the period when the contamination concentration is high. 2011 © American Water Works Association AWWA WQTC Conference Proceedings All Rights...

  19. The Lunar Potential Determination Using Apollo-Era Data and Modern Measurements and Models

    Science.gov (United States)

    Collier, Michael R.; Farrell, William M.; Espley, Jared; Webb, Phillip; Stubbs, Timothy J.; Webb, Phillip; Hills, H. Kent; Delory, Greg

    2008-01-01

    Since the Apollo era the electric potential of the Moon has been a subject of interest and debate. Deployed by three Apollo missions, Apollo 12, Apollo 14 and Apollo 15, the Suprathermal Ion Detector Experiment (SIDE) determined the sunlit lunar surface potential to be about +10 Volts using the energy spectra of lunar ionospheric thermal ions accelerated toward the Moon. More recently, the Lunar Prospector (LP) Electron Reflectometer used electron distributions to infer negative lunar surface potentials, primarily in shadow. We will present initial results from a study to combine lunar surface potential measurements from both SIDE and the LP/Electron Reflectometer to calibrate an advanced model of lunar surface charging which includes effects from the plasma environment, photoemission, secondaries ejected by ion impact onto the lunar surface, and the lunar wake created downstream by the solar wind-lunar interaction.

  20. Generalized Gradient Approximation Made Simple

    International Nuclear Information System (INIS)

    Perdew, J.P.; Burke, K.; Ernzerhof, M.

    1996-01-01

    Generalized gradient approximations (GGA close-quote s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. copyright 1996 The American Physical Society

  1. Potential well measurements in spherical electrostatic-inertial plasma confinement (SEIC) using a collimated proton detector

    International Nuclear Information System (INIS)

    Miley, G.H.; Nadler, J.H.; Gu, Y.B.

    1992-01-01

    A collimated proton detector has been developed for spatially resolved proton measurement in SEIC deuterium fusion experiments. The results are used to infer the potential well depth and well dynamics during SEIC operation. The SEIC operates as follows: ions enter the cathode-grid and are decelerated due to the presence of the positive space charge in the center created by the high ion density there. Since the fusion cross-section is ion-velocity dependent, the greater the height of the positive potential, the lower is the fusion reaction rate in that region. This source profile is determined by the collimated proton measurement. Analysis of the observed proton energy and parametric dependence on voltage current indicates that beam-background fusion predominantly occurs (for a typical 12-mA cathode current, 30-kV cathode voltage in a 4-mTorr D, background). Computer simulations suggest that for these parameters, a positive space charge potential of magnitude about 1/2 of the applied voltage forms inside the cathode. These results establish the first measurement of a positive potential well structure inside an ion injected SEIC device. The dynamics of the well profile with changing injected current is described along with a description of the technique used for unfolding the proton data

  2. Uniform gradient expansions

    CERN Document Server

    Giovannini, Massimo

    2015-01-01

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  3. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  4. Surface potential measurement of the insulator with secondary electron caused by negative ion implantation

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Toyota, Yoshitaka; Nagumo, Syoji; Gotoh, Yasuhito; Ishikawa, Junzo; Sakai, Shigeki; Tanjyo, Masayasu; Matsuda, Kohji.

    1994-01-01

    Ion implantation has the merit of the good controllability of implantation profile and low temperature process, and has been utilized for the impurity introduction in LSI production. However, positive ion implantation is carried out for insulator or insulated conductor substrates, their charged potential rises, which is a serious problem. As the requirement for them advanced, charge compensation method is not the effective means for resolving it. The negative ion implantation in which charging is little was proposed. When the experiment on the negative ion implantation into insulated conductors was carried out, it was verified that negative ion implantation is effective as the implantation process without charging. The method of determining the charged potential of insulators at the time of negative ion implantation by paying attention to the energy distribution of the secondary electrons emitted from substrates at the time was devised. The energy analyzer for measuring the energy distribution of secondary electrons was made, and the measurement of the charged potential of insulators was carried out. The principle of the measurement, the measuring system and the experimental results are reported. (K.I.)

  5. Inferring the gravitational potential of the Milky Way with a few precisely measured stars

    Energy Technology Data Exchange (ETDEWEB)

    Price-Whelan, Adrian M.; Johnston, Kathryn V.; Hendel, David [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Hogg, David W., E-mail: adrn@astro.columbia.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

    2014-10-10

    The dark matter halo of the Milky Way is expected to be triaxial and filled with substructure. It is hoped that streams or shells of stars produced by tidal disruption of stellar systems will provide precise measures of the gravitational potential to test these predictions. We develop a method for inferring the Galactic potential with tidal streams based on the idea that the stream stars were once close in phase space. Our method can flexibly adapt to any form for the Galactic potential: it works in phase-space rather than action-space and hence relies neither on our ability to derive actions nor on the integrability of the potential. Our model is probabilistic, with a likelihood function and priors on the parameters. The method can properly account for finite observational uncertainties and missing data dimensions. We test our method on synthetic data sets generated from N-body simulations of satellite disruption in a static, multi-component Milky Way, including a triaxial dark matter halo with observational uncertainties chosen to mimic current and near-future surveys of various stars. We find that with just eight well-measured stream stars, we can infer properties of a triaxial potential with precisions of the order of 5%-7%. Without proper motions, we obtain 10% constraints on most potential parameters and precisions around 5%-10% for recovering missing phase-space coordinates. These results are encouraging for the goal of using flexible, time-dependent potential models combined with larger data sets to unravel the detailed shape of the dark matter distribution around the Milky Way.

  6. Density and potential measurements in an intense ion-beam-generated plasma

    International Nuclear Information System (INIS)

    Abt, N.E.

    1982-05-01

    Neutral beams are created by intense large area ion beams which are neutralized in a gas cell. The interaction of the beam with the gas cell creates a plasma. Such a plasma is studied here. The basic plasma parameters, electron temperature, density, and plasma potential, are measured as a function of beam current and neutral gas pressure. These measurements are compared to a model based on the solution of Poisson's equation. Because of the cylindrical geometry the equation cannot be solved analytically. Details of the numerical method are presented

  7. Plasma potential measurements in the edge region of the ISTTOK plasma, using electron emissive probes

    International Nuclear Information System (INIS)

    Ionita, C.; Balan, P.; Schrittwieser, R.; Cabral, J.A.; Fernandes, H.; Figueiredo, H. F.C.; Varandas, C.

    2001-01-01

    We have recently started to use electron-emissive probes for direct measurements of the plasma potential and its fluctuations in the edge region of the plasma ring in the tokamak ISTTOK in Lisbon, Portugal. This method is based on the fact that the electron emission current of such a probe is able to compensate electron temperature variations and electron drifts, which can occur in the edge plasma region of magnetized fusion devices, and which are making measurements with cold probes prone to errors. In this contribution we present some of the first results of our investigations in ISTTOK.(author)

  8. A theoretical study on the accuracy of the T-history method for enthalpy–temperature curve measurement: analysis of the influence of thermal gradients inside T-history samples

    International Nuclear Information System (INIS)

    Mazo, Javier; Delgado, Mónica; Lázaro, Ana; Dolado, Pablo; Peñalosa, Conchita; Marín, José María; Zalba, Belén

    2015-01-01

    The present work analyses the effect of radial thermal gradients inside T-history samples on the enthalpy temperature curve measurement. A conduction heat transfer model has been utilized for this purpose. Some expressions have been obtained that relate the main dimensionless numbers of the experiments with the deviations in specific heat capacity, phase change enthalpy and phase change temperature estimations. Although these relations can only be strictly applied to solid materials (e.g. measurements of shape stabilized phase change materials), they can provide some useful and conservative bounds for the deviations of the T-history method. Biot numbers emerge as the most relevant dimensionless parameters in the accuracy of the specific heat capacity and phase change enthalpy estimation whereas this model predicts a negligible influence of the temperature levels used for the experiments or the Stefan number. (paper)

  9. Four-point probe measurements of a direct current potential drop on layered conductive cylinders

    International Nuclear Information System (INIS)

    Lu, Yi; Bowler, John R

    2012-01-01

    We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results. (paper)

  10. Four-point probe measurements of a direct current potential drop on layered conductive cylinders

    Science.gov (United States)

    Lu, Yi; Bowler, John R.

    2012-11-01

    We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results.

  11. An improved potential drop method for measuring and monitoring defects in metallic structures

    International Nuclear Information System (INIS)

    Oppermann, W.; Keller, H.P.

    1993-01-01

    In the developed form described the direct current potential drop method is a reliable and relatively accurate procedure for the measuring and surveillance of surface cracks in metallic materials. There are also significant possibilities in practice of surveying cracks on the inaccessible side of the structure. The basis for the improvement in accuracy, in particular for short cracks, is firstly an improved measuring technique and secondly calibration curves determined using an electrolytic tank. Practical experience gained in conventional plants is to date positive. The opportunity exists of benefitting from the advantages that would be brought about by an increased use of the potential drop method in plant surveillance. In nuclear plants specifically this would achieve a reduction in the testing personnel's exposure to radiation. (orig.)

  12. Successive measurements of streaming potential and electroosmotic pressure with the same core-holder

    Science.gov (United States)

    Yin, Chenggang; Hu, Hengshan; Yu, Chunhao; Wang, Jun

    2018-05-01

    Successive measurements of the streaming potential and electroosmotic pressure of each core sample are important for understanding the mechanisms of electrokinetic effects. In previous studies, one plug of the core-holder needs to be replaced in these two experiments, which causes the change of the fluid parameters and the boundary conditions in the core. We design a new core-holder to permit successive experiments without plug replacement, which ensures the consistency of the measurement environment. A two-direction harmonic pressure-driving source is accordingly designed. Using this new equipment, electrokinetic experiments conducted ten core samples at 0.4 mol/L NaCl solution. The results show good agreement between the electrokinetically deduced permeability and premeasured gas permeability. For high salinity saturated samples, the permeability can be inverted from electroosmotic effect instead of the streaming potential.

  13. Heavy ion beam probe development for the plasma potential measurement on the TUMAN-3M tokamak

    International Nuclear Information System (INIS)

    Askinazi, L.G.; Kornev, V.A.; Lebedev, S.V.; Tukachinsky, A.S.; Zhubr, N.A.; Dreval, N.B.; Krupnik, L.I.

    2004-01-01

    The peculiarities of the heavy ion beam probe implementation on the small aspect ratio tokamak TUMAN-3M are analyzed. The toroidal displacement of beam trajectory due to the high I pl /B tor ratio is taken into account when designing the layout of the diagnostic. Numerical calculation of beam trajectories using realistic configuration of TUMAN-3M magnetic fields and parabolic plasma current profile resulted in proper adjustment of probing and detection parameters (probing ion material, energy, entrance angles, detector location, and orientation). Secondary ion energy analyzer gain functions G and F were measured in situ using neutral hydrogen puffed in the tokamak vessel as a target for secondary ions production. The detector unit featured split-plate design and had additional electrodes for secondary electron emission suppression. As a result, the diagnostic is now capable of plasma potential evolution measurement and is sensitive enough to trace the potential profile evolution at the L-H mode transition

  14. Measurement of the first ionization potential of astatine by laser ionization spectroscopy

    Science.gov (United States)

    Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

    2013-01-01

    The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

  15. Improving Cardiac Action Potential Measurements: 2D and 3D Cell Culture.

    Science.gov (United States)

    Daily, Neil J; Yin, Yue; Kemanli, Pinar; Ip, Brian; Wakatsuki, Tetsuro

    2015-11-01

    Progress in the development of assays for measuring cardiac action potential is crucial for the discovery of drugs for treating cardiac disease and assessing cardiotoxicity. Recently, high-throughput methods for assessing action potential using induced pluripotent stem cell (iPSC) derived cardiomyocytes in both two-dimensional monolayer cultures and three-dimensional tissues have been developed. We describe an improved method for assessing cardiac action potential using an ultra-fast cost-effective plate reader with commercially available dyes. Our methods improve dramatically the detection of the fluorescence signal from these dyes and make way for the development of more high-throughput methods for cardiac drug discovery and cardiotoxicity.

  16. Stability of silver nanoparticle monolayers determined by in situ streaming potential measurements

    International Nuclear Information System (INIS)

    Morga, Maria; Adamczyk, Zbigniew; Oćwieja, Magdalena

    2013-01-01

    A silver particle suspension obtained by a chemical reduction was used in this work. Monolayers of these particles (average size 28 nm) on mica modified by poly(allylamine hydrochloride) were produced under diffusion-controlled transport. Monolayer coverages, quantitatively determined by atomic force microscopy (AFM) and SEM, was regulated by adjusting the nanoparticle deposition time and the suspension concentration. The zeta potential of the monolayers was determined by streaming potential measurements carried out under in situ (wet) conditions. These measurements performed for various ionic strengths and pH were interpreted in terms of the three-dimensional (3D) electrokinetic model. The stability of silver monolayers was also investigated using streaming potential and the AFM methods. The decrease in the surface coverage of particles as a function of time and ionic strength varied between 10 −1 and 10 −4  M was investigated. This allowed one to determine the equilibrium adsorption constant K a and the binding energy of silver particles (energy minima depth). Energy minima depth were calculated that varied between −18 kT for I = 10 −1  M and −19 kT for I = 10 −4 for pH 5.5 and T = 298 K. Our investigations suggest that the interactions between surface and nanoparticles are controlled by the electrostatic interactions among ion pairs. It was also shown that the in situ electrokinetic measurements are in accordance with those obtained by more tedious ex situ AFM measurements. This confirmed the utility of the streaming potential method for direct kinetic studies of nanoparticle deposition/release processes.Graphical Abstract

  17. Ambipolar potential measurement plans and instrumentation. Final report, 1 October 1980-30 September 1982

    International Nuclear Information System (INIS)

    Dahlbacka, G.; Stringfield, R.; Glaros, S.; Buck, V.; Larsen, J.; Burr, L.; Boyle, M.; Lepage, J.; Cirigliano, R.

    1983-03-01

    A Thomson parabola charged particle spectrometer was built with an energy resolution of 80 keV and an active silicon detector array that is read by a computer-compatible CAMAC. The instrument was checked out at the University of Rochester Omega Laser facility. Experiments to measure the ambipolar potential and the dE/dx thermonuclear target to within 50 keV are now possible. The ion temperature of the burn can be determined to within 10%

  18. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

  19. Frequency-Dependent Streaming Potential of Porous Media—Part 2: Experimental Measurement of Unconsolidated Materials

    Directory of Open Access Journals (Sweden)

    P. W. J. Glover

    2012-01-01

    Full Text Available Frequency-dependent streaming potential coefficient measurements have been made upon Ottawa sand and glass bead packs using a new apparatus that is based on an electromagnetic drive. The apparatus operates in the range 1 Hz to 1 kHz with samples of 25.4 mm diameter up to 150 mm long. The results have been analysed using theoretical models that are either (i based upon vibrational mechanics, (ii treat the geological material as a bundle of capillary tubes, or (iii treat the material as a porous medium. The best fit was provided by the Pride model and its simplification, which is satisfying as this model was conceived for porous media rather than capillary tube bundles. Values for the transition frequency were derived from each of the models for each sample and were found to be in good agreement with those expected from the independently measured effective pore radius of each material. The fit to the Pride model for all four samples was also found to be consistent with the independently measured steady-state permeability, while the value of the streaming potential coefficient in the low-frequency limit was found to be in good agreement with other steady-state streaming potential coefficient data.

  20. Time resolved measurements of plasma potential across an anode double layer

    International Nuclear Information System (INIS)

    Pohoata, V.; Popa, Gh.; Schrittwieser, R.; Ionita, Codrina

    2002-01-01

    Experimental results are presented on self-sustained oscillations produced by the dynamics of an anode double layer or fireball in a DP-machine. By additional ionisation processes the fireball is formed in front of an additional small plane anode inserted in the diffusive plasma. An annular (ring) electrode surrounds the anode. The thickness of the ion sheath in front of this ring affects the anode current by controlling its effective diameter during the fireball oscillations. The ring potential controls first the oscillation frequency of the anode current, but also other characteristics of the instability. The ring potential was chosen as a pulsed one so that only single anode double layer instability can be excited. The ring signal was used for triggering the data acquisition system. The spatial distribution of the plasma potential in front of the anode is presented as a time resolved measurement one. A negative drop potential was found that controls the charge flux particle across the double layer. Also the plasma density inside the fireball relaxes during the disrupting time controlled by ambipolar diffusion and also by the negative potential drop. (authors)

  1. Multimodal image registration based on binary gradient angle descriptor.

    Science.gov (United States)

    Jiang, Dongsheng; Shi, Yonghong; Yao, Demin; Fan, Yifeng; Wang, Manning; Song, Zhijian

    2017-12-01

    Multimodal image registration plays an important role in image-guided interventions/therapy and atlas building, and it is still a challenging task due to the complex intensity variations in different modalities. The paper addresses the problem and proposes a simple, compact, fast and generally applicable modality-independent binary gradient angle descriptor (BGA) based on the rationale of gradient orientation alignment. The BGA can be easily calculated at each voxel by coding the quadrant in which a local gradient vector falls, and it has an extremely low computational complexity, requiring only three convolutions, two multiplication operations and two comparison operations. Meanwhile, the binarized encoding of the gradient orientation makes the BGA more resistant to image degradations compared with conventional gradient orientation methods. The BGA can extract similar feature descriptors for different modalities and enable the use of simple similarity measures, which makes it applicable within a wide range of optimization frameworks. The results for pairwise multimodal and monomodal registrations between various images (T1, T2, PD, T1c, Flair) consistently show that the BGA significantly outperforms localized mutual information. The experimental results also confirm that the BGA can be a reliable alternative to the sum of absolute difference in monomodal image registration. The BGA can also achieve an accuracy of [Formula: see text], similar to that of the SSC, for the deformable registration of inhale and exhale CT scans. Specifically, for the highly challenging deformable registration of preoperative MRI and 3D intraoperative ultrasound images, the BGA achieves a similar registration accuracy of [Formula: see text] compared with state-of-the-art approaches, with a computation time of 18.3 s per case. The BGA improves the registration performance in terms of both accuracy and time efficiency. With further acceleration, the framework has the potential for

  2. Measurement error potential and control when quantifying volatile hydrocarbon concentrations in soils

    International Nuclear Information System (INIS)

    Siegrist, R.L.

    1991-01-01

    Due to their widespread use throughout commerce and industry, volatile hydrocarbons such as toluene, trichloroethene, and 1, 1,1-trichloroethane routinely appears as principal pollutants in contamination of soil system hydrocarbons is necessary to confirm the presence of contamination and its nature and extent; to assess site risks and the need for cleanup; to evaluate remedial technologies; and to verify the performance of a selected alternative. Decisions regarding these issues have far-reaching impacts and, ideally, should be based on accurate measurements of soil hydrocarbon concentrations. Unfortunately, quantification of volatile hydrocarbons in soils is extremely difficult and there is normally little understanding of the accuracy and precision of these measurements. Rather, the assumptions often implicitly made that the hydrocarbon data are sufficiently accurate for the intended purpose. This appear presents a discussion of measurement error potential when quantifying volatile hydrocarbons in soils, and outlines some methods for understanding the managing these errors

  3. Data analysis of solar potential in northern Bulgaria obtained by measurements with tall meteorological masts

    International Nuclear Information System (INIS)

    Terziev, A.; Genovski, I.; Petrov, P.; Valchev, V.

    2010-01-01

    Energy from the sun as a renewable energy source could be used for producing not only heat energy but also electricity. The maximum utilization of this type energy requires very good knowledge of the solar radiation for an exact geographical location. Determination of the solar intensity is carried out with special devices called pyranometers. This work considers solar potential data analysis based on data collected from meteorological masts installed in Northern Bulgaria. Comparison between the data from on-site measurements and some long-term data sources well known in literature is also considered. The possibility of studying the interpolation between the points where measurements are carried out in order to obtain solar radiation intensity Filed for the area limited by the points of measurement is also reviewed. Based on correlation analysis results the estimated energy production within the studied area has been calculated. (authors)

  4. Edge effects in four-point direct current potential drop measurements on metal plates

    International Nuclear Information System (INIS)

    Lu, Y; Bowler, N; Bowler, J R; Huang, Y

    2009-01-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  5. Edge effects in four-point direct current potential drop measurements on metal plates

    Science.gov (United States)

    Lu, Y.; Bowler, N.; Bowler, J. R.; Huang, Y.

    2009-07-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  6. Evaluation of commercial glucometer test strips for potential measurement of glucose in tears.

    Science.gov (United States)

    Cha, Kyoung Ha; Jensen, Gary C; Balijepalli, Anant S; Cohan, Bruce E; Meyerhoff, Mark E

    2014-02-04

    Tear glucose measurements have been suggested as a potential alternative to blood glucose monitoring for diabetic patients. While previous work has reported that there is a correlation between blood and tear glucose levels in humans, this link has not been thoroughly established and additional clinical studies are needed. Herein, we evaluate the potential of using commercial blood glucose test strips to measure glucose in tears. Of several blood glucose strips evaluated, only one brand exhibits the low detection limit required for quantitating glucose in tears. Calibration of these strips in the range of 0-100 μM glucose with an applied potential of 150 mV to the working electrode yields a sensitivity of 0.127 nA/μM and a limit of quantitation (LOQ) of 9 μM. The strips also exhibit ≤13% error (n = 3) for 25, 50, and 75 μM glucose in the presence of 10 μM acetaminophen, 100 μM ascorbic acid, and 100 μM uric acid. Measurements of glucose in tears from nine normal (nondiabetic) fasting human subjects using strips yielded glucose values within the range of 5-148 μM (mean = 47 μM, median = 43 μM), similar to those for human tears reported by others with more complex LC-MS methods. The glucometer strip method could facilitate more clinical studies to determine whether tear glucose and blood glucose levels sufficiently correlate for application to routine measurements in tears to supplement blood glucose testing. This would be especially helpful for children, adolescents, other Type 1 diabetics, and also for Type 2 diabetics who require treatment with insulin and cannot tolerate multiple finger sticks per day.

  7. Probing surface charge potentials of clay basal planes and edges by direct force measurements.

    Science.gov (United States)

    Zhao, Hongying; Bhattacharjee, Subir; Chow, Ross; Wallace, Dean; Masliyah, Jacob H; Xu, Zhenghe

    2008-11-18

    The dispersion and gelation of clay suspensions have major impact on a number of industries, such as ceramic and composite materials processing, paper making, cement production, and consumer product formulation. To fundamentally understand controlling mechanisms of clay dispersion and gelation, it is necessary to study anisotropic surface charge properties and colloidal interactions of clay particles. In this study, a colloidal probe technique was employed to study the interaction forces between a silica probe and clay basal plane/edge surfaces. A muscovite mica was used as a representative of 2:1 phyllosilicate clay minerals. The muscovite basal plane was prepared by cleavage, while the edge surface was obtained by a microtome cutting technique. Direct force measurements demonstrated the anisotropic surface charge properties of the basal plane and edge surface. For the basal plane, the long-range forces were monotonically repulsive within pH 6-10 and the measured forces were pH-independent, thereby confirming that clay basal planes have permanent surface charge from isomorphic substitution of lattice elements. The measured interaction forces were fitted well with the classical DLVO theory. The surface potentials of muscovite basal plane derived from the measured force profiles were in good agreement with those reported in the literature. In the case of edge surfaces, the measured forces were monotonically repulsive at pH 10, decreasing with pH, and changed to be attractive at pH 5.6, strongly suggesting that the charge on the clay edge surfaces is pH-dependent. The measured force profiles could not be reasonably fitted with the classical DLVO theory, even with very small surface potential values, unless the surface roughness was considered. The surface element integration (SEI) method was used to calculate the DLVO forces to account for the surface roughness. The surface potentials of the muscovite edges were derived by fitting the measured force profiles with the

  8. Dynamic Reference Electrode development for redox potential measurements in fluoride molten salt at high temperature

    International Nuclear Information System (INIS)

    Durán-Klie, Gabriela; Rodrigues, Davide; Delpech, Sylvie

    2016-01-01

    Measurement of redox potential in fluoride media is a major problem due to the difficulty to design a reference electrode with high stability, high mechanical resistance and high accuracy. In the frame of molten salt reactor studies, a dynamic reference electrode (DRE) is developed to measure redox potential in fluoride molten salt at high temperature. DRE is based on the in-situ generation of a transient redox system. The choice of the redox couple corresponds to the cathodic limit of the molten salt considered. As a preliminary step, the demonstration of feasibility of generating a DRE was done in LiF-NaF-KF (46.5–11.5–42 mol%) media at 500 °C. In this salt, the reference redox system generated by coulometry at applied current is KF/K, metallic potassium being electrodeposited on a tungsten wire electrode. The validation of the DRE response and the experimental optimization parameters for DRE generation were realized by following the NiF 2 /Ni redox potential evolution as a function of NiF 2 concentration in the fused salt. The current value applied for DRE generation was optimized. It depends on the amount of metallic cations contained in the fused salt and which can be electrochemically reduced simultaneously during the DRE generation. The current corresponding to the DRE generation has to be 4 times greater than the current corresponding to the reduction of the other elements.

  9. Bigravity from gradient expansion

    International Nuclear Information System (INIS)

    Yamashita, Yasuho; Tanaka, Takahiro

    2016-01-01

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  10. Three gradients and the perception of flat and curved surfaces.

    Science.gov (United States)

    Cutting, J E; Millard, R T

    1984-06-01

    Researchers of visual perception have long been interested in the perceived slant of a surface and in the gradients that purportedly specify it. Slant is the angle between the line of sight and the tangent to the planar surface at any point, also called the surface normal. Gradients are the sources of information that grade, or change, with visual angle as one looks from one's feet upward to the horizon. The present article explores three gradients--perspective, compression, and density--and the phenomenal impression of flat and curved surfaces. The perspective gradient is measured at right angles to the axis of tilt at any point in the optic array; that is, when looking down a hallway at the tiles of a floor receding in the distance, perspective is measured by the x-axis width of each tile projected on the image plane orthogonal to the line of sight. The compression gradient is the ratio of y/x axis measures on the projected plane. The density gradient is measured by the number of tiles per unit solid visual angle. For flat surfaces and many others, perspective and compression gradients decrease with distance, and the density gradient increases. We discuss the manner in which these gradients change for various types of surfaces. Each gradient is founded on a different assumption about textures on the surfaces around us. In Experiment 1, viewers assessed the three-dimensional character of projections of flat and curved surfaces receding in the distance. They made pairwise judgments of preference and of dissimilarity among eight stimuli in each of four sets. The presence of each gradient was manipulated orthogonally such that each stimulus had zero, one, two, or three gradients appropriate for either a flat surface or a curved surface. Judgments were made were made for surfaces with both regularly shaped and irregularly shaped textures scattered on them. All viewer assessment were then scaled in one dimension. Multiple correlation and regression on the scale values

  11. How do reference montage and electrodes setup affect the measured scalp EEG potentials?

    Science.gov (United States)

    Hu, Shiang; Lai, Yongxiu; Valdes-Sosa, Pedro A.; Bringas-Vega, Maria L.; Yao, Dezhong

    2018-04-01

    Objective. Human scalp electroencephalogram (EEG) is widely applied in cognitive neuroscience and clinical studies due to its non-invasiveness and ultra-high time resolution. However, the representativeness of the measured EEG potentials for the underneath neural activities is still a problem under debate. This study aims to investigate systematically how both reference montage and electrodes setup affect the accuracy of EEG potentials. Approach. First, the standard EEG potentials are generated by the forward calculation with a single dipole in the neural source space, for eleven channel numbers (10, 16, 21, 32, 64, 85, 96, 128, 129, 257, 335). Here, the reference is the ideal infinity implicitly determined by forward theory. Then, the standard EEG potentials are transformed to recordings with different references including five mono-polar references (Left earlobe, Fz, Pz, Oz, Cz), and three re-references (linked mastoids (LM), average reference (AR) and reference electrode standardization technique (REST)). Finally, the relative errors between the standard EEG potentials and the transformed ones are evaluated in terms of channel number, scalp regions, electrodes layout, dipole source position and orientation, as well as sensor noise and head model. Main results. Mono-polar reference recordings are usually of large distortions; thus, a re-reference after online mono-polar recording should be adopted in general to mitigate this effect. Among the three re-references, REST is generally superior to AR for all factors compared, and LM performs worst. REST is insensitive to head model perturbation. AR is subject to electrodes coverage and dipole orientation but no close relation with channel number. Significance. These results indicate that REST would be the first choice of re-reference and AR may be an alternative option for high level sensor noise case. Our findings may provide the helpful suggestions on how to obtain the EEG potentials as accurately as possible for

  12. Environmental Signatures for Habitability: What to Measure and How to Rank the Habitability Potential of Mars

    Science.gov (United States)

    Conrad, Pamela G.; Eigenbrode, Jennifer L.; Mahaffy, Paul M.; Steele, Andrew

    2011-01-01

    The environmental signatures for habitability are not necessarily biosignatures, even though on Earth, they are definitive proof of habitability. It is the constant overprint of the chemical signatures of life that makes it difficult to recognize the chemical and physical properties of a potentially habitable environment as distinct from an inhabited one. Mars Science Laboratory (MSL) will soon embark on a mission to Mars to assess its past or present habitability, so it is useful to examine how we measure habitability on Earth and prepare for how that approach may differ for Mars. This exercise includes: (a) articulation of fundamental assumptions about habitability, (b) an inventory of factors that affect habitability, (c) development of metrics, measurement approach and implementation, and (d) a new classification scheme for planetary habitability that goes beyond the binary "yes" or "no." There may be dozens of factors that affect habitability and they can be weighted as a function of specific environment. However a robotic, in situ investigation even on Earth has constraints that prevent the measurement of every environmental factor, so metrics must be reduced to the most relevant subset, given available time, cost, technical feasibility and scientific importance. Many of the factors could be measured with a combination of orbital data and the MSL payload. We propose that, at a minimum, a designation of high habitability potential requires the following conditions be met: (a) thermally stable with respect to extremes and frequency of fluctuation, (b) has more than one energy source, (c) sufficient chemical diversity to make compounds with covalent and hydrogen bonding, (d) can moderate ionizing radiation enough to allow a stable or evolving pool of organic molecules, (e) must have water or other high quality polar solvent, (f) must be able to renew chemical resources (e.g., plate tectonics, volcanism or something else we haven't envisioned). A measurement

  13. Gradient-Index Optics

    Science.gov (United States)

    2010-03-31

    nonimaging design capabilities to incorporate 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 12-04-2011 13. SUPPLEMENTARY NOTES The views, opinions...Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Imaging Optics, Nonimaging Optics, Gradient Index Optics, Camera, Concentrator...imaging and nonimaging design capabilities to incorporate manufacturable GRIN lenses can provide imaging lens systems that are compact and

  14. Soil Carbon Dynamics Along an Elevation Gradient in the Southern Appalachian Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Garten Jr., C.T.

    2004-04-13

    The role of soil C dynamics in the exchange of CO{sub 2} between the terrestrial biosphere and the atmosphere is at the center of many science questions related to global climate change. The purpose of this report is to summarize measured trends in environmental factors and ecosystem processes that affect soil C balance along elevation gradients in the southern Appalachian Mountains of eastern Tennessee and western North Carolina, USA. Three environmental factors that have potentially significant effects on soil C dynamics (temperature, precipitation, and soil N availability) vary in a predictable manner with altitude. Forest soil C stocks and calculated turnover times of labile soil C increase with elevation, and there is an apparent inverse relationship between soil C storage and mean annual temperature. Relationships between climate variables and soil C dynamics along elevation gradients must be interpreted with caution because litter chemistry, soil moisture, N availability, and temperature are confounded; all potentially interact in complex ways to regulate soil C storage through effects on decomposition. Some recommendations are presented for untangling these complexities. It is concluded that past studies along elevation gradients have contributed to a better but not complete understanding of environmental factors and processes that potentially affect soil C balance. Furthermore, there are advantages linked to the use of elevation gradients as an approach to climate change research when hypotheses are placed in a strong theoretical or mechanistic framework. Climate change research along elevation gradients can be both convenient and economical. More importantly, ecosystem processes and attributes affecting soil C dynamics along elevation gradients are usually the product of the long-term interactions between climate, vegetation, and soil type. Investigations along elevation gradients are a useful approach to the study of environmental change, and its effect

  15. Spontaneous potential and telluric measurements on Rainier Mesa relaed to the NPE

    Energy Technology Data Exchange (ETDEWEB)

    Sweeney, J.J. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    We made measurements of spontaneous potential (SP) on Rainier Mesa to see if changes in subsurface electrical properties of rock related to the Non-Proliferation Experiment (NPE) explosion can be detected at the surface. A north-south line, repeated 3 times and running within 50 m of surface ground zero (SGZ) of Hunter`s Trophy and within 20 m of SGZ of the NPE, was measured before and after the NPE. An east-west line, with one end within 20 m of SGZ of the NPE was also run before and after the NPE. High values of surface potential along the north-south line in the vicinity of the NPE apparently moved northward after the detonation. A similar change was not noted on the east-west line. A telluric line (0.025-0.1 Hz and 8.0 Hz) was also run prior to the NPE along the same north-south line as the SP measurement, but farther to the west of SGZ for Hunter`s Trophy. There is a prominent high in the 8 Hz data in the northern part that may be related to a former nuclear test, but it could also be related to local geology. Results from these geophysical methods, while showing some promise for use in an on-site monitoring regime, also emphasize the need for repeatable background reference data.

  16. Surveillance indicators for potential reduced exposure products (PREPs): developing survey items to measure awareness

    Science.gov (United States)

    Bogen, Karen; Biener, Lois; Garrett, Catherine A; Allen, Jane; Cummings, K Michael; Hartman, Anne; Marcus, Stephen; McNeill, Ann; O'Connor, Richard J; Parascandola, Mark; Pederson, Linda

    2009-01-01

    Background Over the past decade, tobacco companies have introduced cigarettes and smokeless tobacco products (known as Potential Reduced Exposure Products, PREPs) with purportedly lower levels of some toxins than conventional cigarettes and smokeless products. It is essential that public health agencies monitor awareness, interest, use, and perceptions of these products so that their impact on population health can be detected at the earliest stages. Methods This paper reviews and critiques existing strategies for measuring awareness of PREPs from 16 published and unpublished studies. From these measures, we developed new surveillance items and subjected them to two rounds of cognitive testing, a common and accepted method for evaluating questionnaire wording. Results Our review suggests that high levels of awareness of PREPs reported in some studies are likely to be inaccurate. Two likely sources of inaccuracy in awareness measures were identified: 1) the tendency of respondents to misclassify "no additive" and "natural" cigarettes as PREPs and 2) the tendency of respondents to mistakenly report awareness as a result of confusion between PREPs brands and similarly named familiar products, for example, Eclipse chewing gum and Accord automobiles. Conclusion After evaluating new measures with cognitive interviews, we conclude that as of winter 2006, awareness of reduced exposure products among U.S. smokers was likely to be between 1% and 8%, with the higher estimates for some products occurring in test markets. Recommended measurement strategies for future surveys are presented. PMID:19840394

  17. Surveillance indicators for potential reduced exposure products (PREPs: developing survey items to measure awareness

    Directory of Open Access Journals (Sweden)

    McNeill Ann

    2009-10-01

    Full Text Available Abstract Background Over the past decade, tobacco companies have introduced cigarettes and smokeless tobacco products (known as Potential Reduced Exposure Products, PREPs with purportedly lower levels of some toxins than conventional cigarettes and smokeless products. It is essential that public health agencies monitor awareness, interest, use, and perceptions of these products so that their impact on population health can be detected at the earliest stages. Methods This paper reviews and critiques existing strategies for measuring awareness of PREPs from 16 published and unpublished studies. From these measures, we developed new surveillance items and subjected them to two rounds of cognitive testing, a common and accepted method for evaluating questionnaire wording. Results Our review suggests that high levels of awareness of PREPs reported in some studies are likely to be inaccurate. Two likely sources of inaccuracy in awareness measures were identified: 1 the tendency of respondents to misclassify "no additive" and "natural" cigarettes as PREPs and 2 the tendency of respondents to mistakenly report awareness as a result of confusion between PREPs brands and similarly named familiar products, for example, Eclipse chewing gum and Accord automobiles. Conclusion After evaluating new measures with cognitive interviews, we conclude that as of winter 2006, awareness of reduced exposure products among U.S. smokers was likely to be between 1% and 8%, with the higher estimates for some products occurring in test markets. Recommended measurement strategies for future surveys are presented.

  18. Measurements of strongly localized potential well profiles in an inertial electrostatic fusion neutron source

    International Nuclear Information System (INIS)

    Yoshikawa, K.; Takiyama, K.; Koyama, T.

    2001-01-01

    Direct measurements of localized electric fields are made by the laser-induced fluorescence (LIF) method by use of the Stark effects in the central cathode core region of an Inertial-Electrostatic Confinement Fusion (IECF) neutron (proton) source, which is expected for various applications, such as luggage security inspection, non-destructive testing, land mine detector, or positron emitter production for cancer detection, currently producing continuously about 10 7 n/sec D-D neutrons. Since 1967 when the first fusion reaction was successfully proved experimentally in a very compact IECF device, potential well formation due to space charge associated with spherically converging ion beams has been a central key issue to be clarified in the beam-beam colliding fusion, which is the major mechanism of the IECF neutron source. Many experiments, but indirect, were made so far to clarify the potential well, but none of them produced definitive evidence, however. Results by the present LIF method show a double well potential profile with a slight concave for ion beams with relatively larger angular momenta, whereas for ions with smaller angular momenta, potential but much steeper peak to develop. (author)

  19. Self-induced temperature gradients in Brownian dynamics

    Science.gov (United States)

    Devine, Jack; Jack, M. W.

    2017-12-01

    Brownian systems often surmount energy barriers by absorbing and emitting heat to and from their local environment. Usually, the temperature gradients created by this heat exchange are assumed to dissipate instantaneously. Here we relax this assumption to consider the case where Brownian dynamics on a time-independent potential can lead to self-induced temperature gradients. In the same way that externally imposed temperature gradients can cause directed motion, these self-induced gradients affect the dynamics of the Brownian system. The result is a coupling between the local environment and the Brownian subsystem. We explore the resulting dynamics and thermodynamics of these coupled systems and develop a robust method for numerical simulation. In particular, by focusing on one-dimensional situations, we show that self-induced temperature gradients reduce barrier-crossing rates. We also consider a heat engine and a heat pump based on temperature gradients induced by a Brownian system in a nonequilibrium potential.

  20. High-resolution metal gradients measured by in situ DGT/DET deployment in Black Sea sediments using an autonomous benthic lander RID G-2489-2010 RID A-4901-2009

    DEFF Research Database (Denmark)

    Fones, GR; Davison, W.; Holby, O.

    2001-01-01

    DET (Diffusive equilibration in thin films) and DGT (diffusive gradients in thin films) have been deployed in situ using an autonomous benthic lander to measure concentrations and induced fluxes of Fe and Mn (DET/DGT) and trace metals (DGT) in pore waters at millimeter spatial resolutions....... The newly developed deployment system is described, and based on these first results, its strengths and weaknesses are discussed. Deployments were made in the Western Black Sea in shelf sediments overlain by well-oxygenated water at a water depth of 77 m. Maxima of the redox-sensitive metals at 4 and 8 cm...... elements by several millimeters. Detection of this functional discrimination between Fe and Mn as regulators of trace metals would not have been possible using more conventional sampling procedures....

  1. Soil gas and radon entry potential measurements in central Florida houses

    International Nuclear Information System (INIS)

    Turk, B.H.

    1993-01-01

    A technique to quantify the various parameters associated with the pressure-driven entry rate of soil gas and radon into buildings has been applied to five central Florida houses with slab-on-grade construction. Results indicate that the slabs of these Florida houses are more resistant to soil gas flow than slabs in previously studied New Jersey and New Mexico houses. The data for locations near the slab perimeter show that the resistance to soil gas flow is greater for the slab than for the underlying materials/soils, implying that the slab resistance is a slightly dominant factor controlling soil gas entry in these houses. As in the New Jersey and New Mexico houses, soil gas and radon entry potentials were highest near the slab perimeters. In contrast to the earlier studies, geometric mean radon entry potentials did not correlate well with measured indoor radon levels. (orig.). (4 refs., 1 fig., 2 tabs.)

  2. Methods for the numerical calculation of the plasma potential from measured Langmuir probe characteristics

    International Nuclear Information System (INIS)

    Seifert, W.; Johanning, D.; Bankov, N.

    1986-01-01

    In a previous paper the results of the Langmuir probe experiment carried out on board of two INTERKOSMOS satellites have been described. The experiences have shown that the usage of high quality algorithms for analyzing the current-voltage-characteristics is necessary to yield real physical parameters. The key problem is the determination of the plasma potential. This paper reviews the different methods to determine the plasma potential especially under the circumstances of computer application. The test of the well developed methods shows, that for the evaluation of the applied methods a number of different factors, discussed in the following sections of this paper, has to be taken into account. The used test data are model values or real measurements obtained by the satellite missions IK-10, IK-18 and BULGARIA-1300. The computer procedures have been realized as FORTRAN-subroutines for the BESM 6 and ES 1040. (author)

  3. The potential of continuous, local atomic clock measurements for earthquake prediction and volcanology

    Directory of Open Access Journals (Sweden)

    Bondarescu Mihai

    2015-01-01

    Full Text Available Modern optical atomic clocks along with the optical fiber technology currently being developed can measure the geoid, which is the equipotential surface that extends the mean sea level on continents, to a precision that competes with existing technology. In this proceeding, we point out that atomic clocks have the potential to not only map the sea level surface on continents, but also look at variations of the geoid as a function of time with unprecedented timing resolution. The local time series of the geoid has a plethora of applications. These include potential improvement in the predictions of earthquakes and volcanoes, and closer monitoring of ground uplift in areas where hydraulic fracturing is performed.

  4. Potential of public transit as a transportation control measure: Case studies

    Energy Technology Data Exchange (ETDEWEB)

    Sillings, M.

    1998-07-01

    This report is the final product of the Clean Air Project of the National Association of Regional Councils/NARC. It documents a nationwide study of transit projects and programs initiated in the wake of the 1990 Clean Air Act Amendments/CAAA and the Intermodal Surface Transportation Efficiency Act of 1991/ISTEA. The study purpose was to assess the experience, limitations, and value of public transit as a potential transportation control measure/TCM, i.e., generates significant air quality benefits by eliminating or reducing emissions from motor vehicles. Four in-depth case studies and six additional projects featured as innovations in transportation are offered as examples investigating the potential of transit as a TCM. These case studies and innovations highlight the efforts of ten metropolitan areas and transit agencies which have succeed in developing and implementing innovative transit strategies.

  5. Measures of maximum magnetic field in 3 GHz radio frequency superconducting cavities; Mesures du gradient accelerateur maximum dans des cavites supraconductrices en regime impulsionnel a 3 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Catherine [Paris-11 Univ., 91 Orsay (France)

    2000-01-19

    Theoretical models have shown that the maximum magnetic field in radio frequency superconducting cavities is the superheating field H{sub sh}. For niobium, H{sub sh} is 25 - 30% higher than the thermodynamical H{sub c} field: H{sub sh} within (240 - 274) mT. However, the maximum magnetic field observed so far is in the range H{sub c,max} = 152 mT for the best 1.3 GHz Nb cavities. This field is lower than the critical field H{sub c1} above which the superconductor breaks up into divided normal and superconducting zones (H{sub c1}{<=}H{sub c}). Thermal instabilities are responsible for this low value. In order to reach H{sub sh} before thermal breakdown, high power short pulses are used. The cavity needs then to be strongly over-coupled. The dedicated test bed has been built from the collaboration between Istituto Nazionale di Fisica Nucleare (INFN) - Sezione di Genoa, and the Service d'Etudes et Realisation d'Accelerateurs (SERA) of Laboratoire de l'Accelerateur Lineaire (LAL). The maximum magnetic field, H{sub rf,max}, measurements on INFN cavities give lower results than the theoretical speculations and are in agreement with previous results. The superheating magnetic fields is linked to the magnetic penetration depth. This superconducting characteristic length can be used to determine the quality of niobium through the ratio between the resistivity measured at 300 K and 4.2 K in the normal conducting state (RRR). Results have been compared to previous ones and agree pretty well. They show that the RRR measured on cavities is superficial and lower than the RRR measured on samples which concerns the volume. (author)

  6. In vivo intracellular pH measurements in tobacco and Arabidopsis reveal an unexpected pH gradient in the endomembrane system.

    Science.gov (United States)

    Martinière, Alexandre; Bassil, Elias; Jublanc, Elodie; Alcon, Carine; Reguera, Maria; Sentenac, Hervé; Blumwald, Eduardo; Paris, Nadine

    2013-10-01

    The pH homeostasis of endomembranes is essential for cellular functions. In order to provide direct pH measurements in the endomembrane system lumen, we targeted genetically encoded ratiometric pH sensors to the cytosol, the endoplasmic reticulum, and the trans-Golgi, or the compartments labeled by the vacuolar sorting receptor (VSR), which includes the trans-Golgi network and prevacuoles. Using noninvasive live-cell imaging to measure pH, we show that a gradual acidification from the endoplasmic reticulum to the lytic vacuole exists, in both tobacco (Nicotiana tabacum) epidermal (ΔpH -1.5) and Arabidopsis thaliana root cells (ΔpH -2.1). The average pH in VSR compartments was intermediate between that of the trans-Golgi and the vacuole. Combining pH measurements with in vivo colocalization experiments, we found that the trans-Golgi network had an acidic pH of 6.1, while the prevacuole and late prevacuole were both more alkaline, with pH of 6.6 and 7.1, respectively. We also showed that endosomal pH, and subsequently vacuolar trafficking of soluble proteins, requires both vacuolar-type H(+) ATPase-dependent acidification as well as proton efflux mediated at least by the activity of endosomal sodium/proton NHX-type antiporters.

  7. Alpha-Glucosidase Enzyme Biosensor for the Electrochemical Measurement of Antidiabetic Potential of Medicinal Plants.

    Science.gov (United States)

    Mohiuddin, M; Arbain, D; Islam, A K M Shafiqul; Ahmad, M S; Ahmad, M N

    2016-12-01

    A biosensor for measuring the antidiabetic potential of medicinal plants was developed by covalent immobilization of α-glucosidase (AG) enzyme onto amine-functionalized multi-walled carbon nanotubes (MWCNTs-NH2). The immobilized enzyme was entrapped in freeze-thawed polyvinyl alcohol (PVA) together with p-nitrophenyl-α-D-glucopyranoside (PNPG) on the screen-printed carbon electrode at low pH to prevent the premature reaction between PNPG and AG enzyme. The enzymatic reaction within the biosensor is inhibited by bioactive compounds in the medicinal plant extracts. The capability of medicinal plants to inhibit the AG enzyme on the electrode correlates to the potential of the medicinal plants to inhibit the production of glucose from the carbohydrate in the human body. Thus, the inhibition indicates the antidiabetic potential of the medicinal plants. The performance of the biosensor was evaluated to measure the antidiabetic potential of three medicinal plants such as Tebengau (Ehretis laevis), Cemumar (Micromelum pubescens), and Kedondong (Spondias dulcis) and acarbose (commercial antidiabetic drug) via cyclic voltammetry, amperometry, and spectrophotometry. The cyclic voltammetry (CV) response for the inhibition of the AG enzyme activity by Tebengau plant extracts showed a linear relation in the range from 0.423-8.29 μA, and the inhibition detection limit was 0.253 μA. The biosensor exhibited good sensitivity (0.422 μA/mg Tebengau plant extracts) and rapid response (22 s). The biosensor retains approximately 82.16 % of its initial activity even after 30 days of storage at 4 °C.

  8. Comparison of three different methods of perturbing the potential vorticity field in mesoscale forecasts of Mediterranean heavy precipitation events: PV-gradient, PV-adjoint and PV-satellite

    Science.gov (United States)

    Vich, M.; Romero, R.; Richard, E.; Arbogast, P.; Maynard, K.

    2010-09-01

    Heavy precipitation events occur regularly in the western Mediterranean region. These events often have a high impact on the society due to economic and personal losses. The improvement of the mesoscale numerical forecasts of these events can be used to prevent or minimize their impact on the society. In previous studies, two ensemble prediction systems (EPSs) based on perturbing the model initial and boundary conditions were developed and tested for a collection of high-impact MEDEX cyclonic episodes. These EPSs perturb the initial and boundary potential vorticity (PV) field through a PV inversion algorithm. This technique ensures modifications of all the meteorological fields without compromising the mass-wind balance. One EPS introduces the perturbations along the zones of the three-dimensional PV structure presenting the local most intense values and gradients of the field (a semi-objective choice, PV-gradient), while the other perturbs the PV field over the MM5 adjoint model calculated sensitivity zones (an objective method, PV-adjoint). The PV perturbations are set from a PV error climatology (PVEC) that characterizes typical PV errors in the ECMWF forecasts, both in intensity and displacement. This intensity and displacement perturbation of the PV field is chosen randomly, while its location is given by the perturbation zones defined in each ensemble generation method. Encouraged by the good results obtained by these two EPSs that perturb the PV field, a new approach based on a manual perturbation of the PV field has been tested and compared with the previous results. This technique uses the satellite water vapor (WV) observations to guide the correction of initial PV structures. The correction of the PV field intents to improve the match between the PV distribution and the WV image, taking advantage of the relation between dark and bright features of WV images and PV anomalies, under some assumptions. Afterwards, the PV inversion algorithm is applied to run

  9. The potential of head-space gas chromatography for VLE measurements

    International Nuclear Information System (INIS)

    Luis, Patricia; Wouters, Christine; Sweygers, Nick; Creemers, Claude; Van der Bruggen, Bart

    2012-01-01

    Highlights: ► HS-GC is a potential technique to obtain VLE data in a high throughput scenario. ► We applied HS-GC and evaluate the main issues to consider. ► Four azeotropic mixtures of industrial interest are studied. ► The thermodynamic analysis of VLE shows the strong non-ideality of the mixtures. - Abstract: Head-space gas chromatography (HS-GC) is thought to allow the performance of (vapour + liquid) equilibrium (VLE) measurements in a fast and automated way. However, two decades after the first applications of HS-GC for this purpose, the potential of this technique is not fully developed yet. Measurements of isothermal VLE and activity coefficients of mixtures can be obtained in a high throughput scenario. However, several considerations have to be taken into account before starting the analysis, such as the equilibration time or the minimum sample volume and the GC response factors. These aspects can strongly influence on the validity of the results and should therefore be determined for each mixture. In this paper, four azeotropic mixtures of interest in the pharmaceutical and chemical industry, i.e., (ethylacetate + water), which forms a heterogeneous azeotrope, (ethylacetate + isooctane), (acetonitrile + toluene) and the ternary mixture (acetonitrile + toluene + tetrahydrofuran), are considered to show the potential of HS-GC for VLE measurements. The thermodynamic analysis of VLE data leads to activity coefficients for the mixtures at (35, 50, and 70) °C. In addition, the experimental data are compared with thermodynamic models and data from the literature, when available.

  10. Recombinant albumin adsorption on mica studied by AFM and streaming potential measurements.

    Science.gov (United States)

    Kujda, Marta; Adamczyk, Zbigniew; Morga, Maria; Sofińska, Kamila

    2015-03-01

    Recombinant human serum albumin (rHSA) in monomeric state is widely used in pharmaceutical industry as a drug excipient and for preparing coatings for medical devices. In this work the adsorption process of rHSA on model mica surface at pH 3.5 was studied using the atomic force microscopy (AFM) and in situ streaming potential measurements. The kinetics of albumin adsorption was determined by a direct enumeration of single molecules over various substrate areas. These results were consistent with streaming potential measurements carried out for the parallel-plate channel flow and with theoretical predictions derived from the random sequential adsorption (RSA) model. Desorption kinetics of albumin under flow conditions was also evaluated via the streaming potential measurements. In this way, the amount of irreversibly bound albumin was quantitatively evaluated to be 0.64 and 1.2 mg m(-2) for ionic strength of 0.01 and 0.15 M, respectively. This agrees with previous results obtained for HSA and theoretical calculations derived from the RSA model. Additionally, it was demonstrated that there existed a fraction of reversibly bound albumin that can be fully eluted within a few hours. The binding energy of these fraction of molecules was -18 kT that is consistent with the electrostatic controlled adsorption mechanism of albumin at this pH. It was concluded that the rHSA monolayers of well-defined coverage can find applications for quantitatively analyzing ligand binding and for performing efficient biomaterials and immunological tests. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Gradient Learning Algorithms for Ontology Computing

    Science.gov (United States)

    Gao, Wei; Zhu, Linli

    2014-01-01

    The gradient learning model has been raising great attention in view of its promising perspectives for applications in statistics, data dimensionality reducing, and other specific fields. In this paper, we raise a new gradient learning model for ontology similarity measuring and ontology mapping in multidividing setting. The sample error in this setting is given by virtue of the hypothesis space and the trick of ontology dividing operator. Finally, two experiments presented on plant and humanoid robotics field verify the efficiency of the new computation model for ontology similarity measure and ontology mapping applications in multidividing setting. PMID:25530752

  12. Gradient Learning Algorithms for Ontology Computing

    Directory of Open Access Journals (Sweden)

    Wei Gao

    2014-01-01

    Full Text Available The gradient learning model has been raising great attention in view of its promising perspectives for applications in statistics, data dimensionality reducing, and other specific fields. In this paper, we raise a new gradient learning model for ontology similarity measuring and ontology mapping in multidividing setting. The sample error in this setting is given by virtue of the hypothesis space and the trick of ontology dividing operator. Finally, two experiments presented on plant and humanoid robotics field verify the efficiency of the new computation model for ontology similarity measure and ontology mapping applications in multidividing setting.

  13. Interface bonding in silicon oxide nanocontacts: interaction potentials and force measurements

    Science.gov (United States)

    Wierez-Kien, M.; Craciun, A. D.; Pinon, A. V.; Le Roux, S.; Gallani, J. L.; Rastei, M. V.

    2018-04-01

    The interface bonding between two silicon-oxide nanoscale surfaces has been studied as a function of atomic nature and size of contacting asperities. The binding forces obtained using various interaction potentials are compared with experimental force curves measured in vacuum with an atomic force microscope. In the limit of small nanocontacts (typically contact area which is altered by stretching speeds. The mean unbinding force is found to decrease as the contact spends time in the attractive regime. This contact weakening is featured by a negative aging coefficient which broadens and shifts the thermal-induced force distribution at low stretching speeds.

  14. Electrochemical noise measurements techniques and the reversing dc potential drop method applied to stress corrosion essays

    International Nuclear Information System (INIS)

    Aly, Omar Fernandes; Andrade, Arnaldo Paes de; MattarNeto, Miguel; Aoki, Idalina Vieira

    2002-01-01

    This paper aims to collect information and to discuss the electrochemical noise measurements and the reversing dc potential drop method, applied to stress corrosion essays that can be used to evaluate the nucleation and the increase of stress corrosion cracking in Alloy 600 and/or Alloy 182 specimens from Angra I Nuclear Power Plant. Therefore we will pretend to establish a standard procedure to essays to be realized on the new autoclave equipment on the Laboratorio de Eletroquimica e Corrosao do Departamento de Engenharia Quimica da Escola Politecnica da Universidade de Sao Paulo - Electrochemical and Corrosion Laboratory of the Chemical Engineering Department of Polytechnical School of Sao Paulo University, Brazil. (author)

  15. Potential of [11C]DASB for measuring endogenous serotonin with PET: binding studies

    International Nuclear Information System (INIS)

    Lundquist, Pinelopi; Wilking, Helena; Hoeglund, A. Urban; Sandell, Johan; Bergstroem, Mats; Hartvig, Per; Langstroem, Bengt

    2005-01-01

    The serotonin transporter radioligand [ 11 C]-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile, or [ 11 C]DASB, was examined in order to assess its potential for measuring fluctuations in endogenous serotonin concentrations with positron emission tomography. Binding characteristics of [ 11 C]DASB and the propensity for serotonin to displace the tracer were explored in rat brain homogenates. Experiments showed that serotonin displaced [ 11 C]DASB in vitro. Ex vivo experiments performed after tranylcypromine injection (3 or 15 mg/kg) showed a dose-dependent trend in radioactivity uptake and suggested that serotonin may compete with [ 11 C]DASB for transporter binding

  16. Temperature logging of groundwater in bedrock wells for geothermal gradient characterization in New Hampshire, 2012

    Science.gov (United States)

    Degnan, James; Barker, Gregory; Olson, Neil; Wilder, Leland

    2012-01-01

    The U.S. Geological Survey, in cooperation with the New Hampshire Geological Survey, measured the fluid temperature of groundwater in deep bedrock wells in the State of New Hampshire in order to characterize geothermal gradients in bedrock. All wells selected for the study had low water yields, which correspond to low groundwater flow from fractures. This reduced the potential for flow-induced temperature changes that would mask the natural geothermal gradient in the bedrock. All the wells included in this study were privately owned, and permission to use the wells was obtained from homeowners before logging.

  17. Reactor Materials Program electrochemical potential measurements by ORNL with unirradiated and irradiated stainless steel specimens

    International Nuclear Information System (INIS)

    Baumann, E.W.; Caskey, G.R. Jr.

    1993-07-01

    Effect of irradiation of stainless steel on electrochemical potential (ECP) was investigated by measurements in dilute HNO 3 and H 2 O 2 solutions, conditions simulating reactor moderator. The electrodes were made from unirradiated/irradiated, unsensitized/sensitized specimens from R-reactor piping. Results were inconclusive because of budgetary restrictions. The dose rate may have been too small to produce a significant radiolytic effect. Neither the earlier CERT corrosion susceptibility tests nor the present ECP measurements showed a pronounced effect of irradiation on susceptibility of the stainless steel to IGSCC; this is confirmed by the absence in the stainless steel of the SRS reactor tanks (except for the C Reactor tank knuckle area)

  18. Photoacoustically Measured Speeds of Sound of Liquid HBO2: On Unlocking the Fuel Potential of Boron

    Energy Technology Data Exchange (ETDEWEB)

    Bastea, S; Crowhurst, J; Armstrong, M; ., N T

    2010-03-24

    Elucidation of geodynamic, geochemical, and shock induced processes is often limited by challenges to accurately determine molecular fluid equations of state (EOS). High pressure liquid state reactions of carbon species underlie physiochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. Here we introduce a versatile photoacoustic technique developed to measure accurate and precise speeds of sound (SoS) of high pressure molecular fluids and fluid mixtures. SoS of an intermediate boron oxide, HBO{sub 2} are measured up to 0.5 GPa along the 277 C isotherm. A polarized Exponential-6 interatomic potential form, parameterized using our SoS data, enables EOS determinations and corresponding semi-empirical evaluations of > 2000 C thermodynamic states including energy release from bororganic formulations. Our thermochemical model propitiously predicts boronated hydrocarbon shock Hugoniot results.

  19. Measurement of the Fermi potential of diamond-like carbon and other materials

    International Nuclear Information System (INIS)

    Atchison, F.; Blau, B.; Daum, M.; Fierlinger, P.; Geltenbort, P.; Gupta, M.; Henneck, R.; Heule, S.; Kasprzak, M.; Knecht, A.; Kuzniak, M.; Kirch, K.; Meier, M.; Pichlmaier, A.; Reiser, R.; Theiler, B.; Zimmer, O.; Zsigmond, G.

    2007-01-01

    The Fermi potential V f of diamond-like carbon (DLC) coatings produced with laser-controlled vacuum arc deposition and that of diamond, Al, Si, Be, Cu, Fe and Ni was measured using two different methods, (i) transmission of slow neutrons through foils in a time-of-flight experiment and (ii) cold neutron reflectometry (CNR). For diamond-like carbon in transmission we obtain V f = (249 ± 14) neV. This is approximately the same as for beryllium and consistent with the theoretical expectations for the measured diamond (sp 3 ) content of 45%. For an sp 3 -content of 67%, we find V f (271 ± 13) neV from reflectometry, again in agreement with theory. These findings open new perspectives in using DLC as storage volume and neutron guide coatings for ultracold neutron sources

  20. Reactor Materials Program electrochemical potential measurements by ORNL with unirradiated and irradiated stainless steel specimens

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, E.W.; Caskey, G.R. Jr.

    1993-07-01

    Effect of irradiation of stainless steel on electrochemical potential (ECP) was investigated by measurements in dilute HNO{sub 3} and H{sub 2}O{sub 2} solutions, conditions simulating reactor moderator. The electrodes were made from unirradiated/irradiated, unsensitized/sensitized specimens from R-reactor piping. Results were inconclusive because of budgetary restrictions. The dose rate may have been too small to produce a significant radiolytic effect. Neither the earlier CERT corrosion susceptibility tests nor the present ECP measurements showed a pronounced effect of irradiation on susceptibility of the stainless steel to IGSCC; this is confirmed by the absence in the stainless steel of the SRS reactor tanks (except for the C Reactor tank knuckle area).

  1. A Measure of the Potential Impact of Hospital Community Health Activities on Population Health and Equity.

    Science.gov (United States)

    Begun, James W; Kahn, Linda M; Cunningham, Brooke A; Malcolm, Jan K; Potthoff, Sandra

    2017-12-13

    Many hospitals in the United States are exploring greater investment in community health activities that address upstream causes of poor health. Develop and apply a measure to categorize and estimate the potential impact of hospitals' community health activities on population health and equity. We propose a scale of potential impact on population health and equity, based on the cliff analogy developed by Jones and colleagues. The scale is applied to the 317 activities reported in the community health needs assessment implementation plan reports of 23 health care organizations in the Minneapolis-St Paul, Minnesota metropolitan area in 2015. Using a 5-point ordinal scale, we assigned a score of potential impact on population health and equity to each community health activity. A majority (50.2%) of health care organizations' community health activities are classified as addressing social determinants of health (level 4 on the 5-point scale), though very few (5.4%) address structural causes of health equity (level 5 on the 5-point scale). Activities that score highest on potential impact fall into the topic categories of "community health and connectedness" and "healthy lifestyles and wellness." Lower-scoring activities focus on sick or at-risk individuals, such as the topic category of "chronic disease prevention, management, and screening." Health care organizations in the Minneapolis-St Paul metropolitan area vary substantially in the potential impact of their aggregated community health activities. Hospitals can be significant contributors to investment in upstream community health programs. This article provides a scale that can be used not only by hospitals but by other health care and public health organizations to better align their community health strategies, investments, and partnerships with programming and policies that address the foundational causes of population health and equity within the communities they serve.

  2. Validation of jump squats as a practical measure of post-activation potentiation.

    Science.gov (United States)

    Nibali, Maria L; Chapman, Dale W; Robergs, Robert A; Drinkwater, Eric J

    2013-03-01

    To determine if post-activation potentiation (PAP) can augment sports performance, it is pertinent that researchers be confident that any enhancement in performance is attributable to the PAP phenomenon. However, obtaining mechanistic measures of PAP in the daily training environment of highly trained athletes is impractical. We sought to validate jump squats as a practical measure with ecological validity to sports performance against a mechanistic measure of PAP. We assessed the evoked muscle twitch properties of the knee extensors and jump squat kinetics of 8 physically trained males in response to a 5-repetition-maximum back squat conditioning stimulus (CS). Evoked muscle twitch, followed by 3 jump squats, was assessed before and at 4, 8, and 12 min post CS. Time intervals were assessed on separate occasions using a Latin square design. Linear regression was used to determine the relationship between post-pre changes in kinetic variables and muscle twitch peak force (Ft) and twitch rate of force development (RFDt). Large correlations were observed for both concentric relative and absolute mean power and Ft (r = 0.50 ± 0.30) and RFDt (r = 0.56 ± 0.27 and r = 0.58 ± 0.26). Concentric rate of force development (RFD) showed moderate correlations with Ft (r = 0.45 ± 0.33) and RFDt (r = 0.49 ± 0.32). Small-to-moderate correlations were observed for a number of kinetic variables (r = -0.42-0.43 ± 0.32-0.38). Jump squat concentric mean power and RFD are valid ecological measures of muscle potentiation, capable of detecting changes in athletic performance in response to the PAP phenomenon.

  3. Laser Cooling and Trapping of Neutral Strontium for Spectroscopic Measurements of Casimir-Polder Potentials

    Science.gov (United States)

    Cook, Eryn C.

    Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes. The spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the "magic" wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom-surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential. We have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.

  4. A tool for evaluating the potential for cost-effective outcomes measurement.

    Science.gov (United States)

    Somasekhar, Melinda M; Bove, Alfred; Rausch, Chris; Degnan, James; King, Cathy T; Meyer, Arnold

    2012-01-01

    Cost related to higher-level outcomes measurement is often very high. However, the cost burden is felt even more by smaller, less well-funded continuing medical education (CME) programs. It is possible to overcome financial and participant-related barriers to measuring Level 6 outcomes, which are patient health outcomes. The Temple University School of Medicine's Office for Continuing Medical Education developed a sequential tool for attaining cost-effective outcomes measurement for determining the likelihood of a CME intervention to produce significant changes in physician performance. The appropriate selection of the CME topic and specific practice change indictors drive this tool. This tool walks providers through a simple YES or NO decision-making list that guides them toward an accurate prediction of potential programmatic outcomes. Factors considered during the decision-making process include whether: (a) the intended change(s) will have a substantial impact on current practice; (b) the intended practice change(s) are well supported by clinical data, specialty organization/government recommendations, expert opinion, etc; (c) the potential change(s) affects a large population; (d) external factors, such as system pressures, media pressures, financial pressures, patient pressures, safety pressures, etc, are driving this intended change in performance; (e) there is a strong motivation on the part of physicians to implement the intended change(s); and (f) the intended change(s) is relatively easy to implement within any system of practice. If each of these questions can be responded to positively, there is a higher likelihood that the intended practice-related change(s) will occur. Such change can be measured using a simpler and less costly methodology.

  5. Measurements of the streaming potential of clay soils from tropical and subtropical regions using self-made apparatus.

    Science.gov (United States)

    Li, Zhong-Yi; Li, Jiu-Yu; Liu, Yuan; Xu, Ren-Kou

    2014-09-01

    The streaming potential has been wildly used in charged parallel plates, capillaries, and porous media. However, there have been few studies involving the ζ potential of clay soils based on streaming potential measurements. A laboratory apparatus was developed in this study to measure the streaming potential (ΔE) of bulk clay soils' coupling coefficient (C) and cell resistance (R) of saturated granular soil samples. Excellent linearity of ΔE versus liquid pressure (ΔP) ensured the validity of measurements. The obtained parameters of C and R can be used to calculate the ζ potential of bulk soils. The results indicated that the ζ potentials measured by streaming potential method were significantly correlated with the ζ potentials of soil colloids determined by electrophoresis (r (2) = 0.960**). Therefore, the streaming potential method can be used to study the ζ potentials of bulk clay soils. The absolute values of the ζ potentials of four soils followed the order: Ultisol from Jiangxi > Ultisol from Anhui > Oxisol from Guangdong > Oxisol from Hainan, and this was consistent with the cation exchange capacities of these soils. The type and concentration of electrolytes affected soil ζ potentials. The ζ potential became less negative with increased electrolyte concentration. The ζ potentials were more negative in monovalent than in divalent cationic electrolyte solutions because more divalent cations were distributed in the shear plane of the diffuse layer as counter-cations on the soil surfaces than monovalent cations at the same electrolyte concentration.

  6. Microstructural gradients in thin hard coatings -- tailor-made

    DEFF Research Database (Denmark)

    Pantleon, Karen; Oettel, Heinrich

    1998-01-01

    ) alternating sputtering with and without substrate voltage and (c) pulsed bias voltage. On the basis of X-ray diffraction measurements, it is demonstrated that residual stress gradients and texture gradients can be designed tailor-made. Furthermore, results of microhardness measurements and scratch tests...

  7. A gel probe equilibrium sampler for measuring arsenic porewater profiles and sorption gradients in sediments: II. Field application to Haiwee reservoir sediment

    Science.gov (United States)

    Campbell, K.M.; Root, R.; O'Day, P. A.; Hering, J.G.

    2008-01-01

    Arsenic (As) geochemistry and sorption behavior were measured in As- and iron (Fe)-rich sediments of Haiwee Reservoir by deploying undoped (clear) polyacrylamide gels and hydrous ferric oxide (HFO)-doped gels in a gel probe equilibrium sampler, which is a novel technique for directly measuring the effects of porewater composition on As adsorption to Fe oxides phases in situ. Arsenic is deposited at the sediment surface as As(V) and is reduced to As(III) in the upper layers of the sediment (0-8 cm), but the reduction of As(V) does not cause mobilization into the porewater. Dissolved As and Fe concentrations increased at depth in the sediment column driven by the reductive dissolution of amorphous Fe(III) oxyhydroxides and conversion to a mixed Fe(II, III) green rust-type phase. Adsorption of As and phosphorous (P) onto HFO-doped gels was inhibited at intermediate depths (10-20 cm), possibly due to dissolved organic or inorganic carbon, indicating that dissolved As concentrations were at least partially controlled by porewater composition rather than surface site availability. In sediments that had been recently exposed to air, the region of sorption inhibition was not observed, suggesting that prior exposure to air affected the extent of reductive dissolution, porewater chemistry, and As adsorption behavior. Arsenic adsorption onto the HFO-doped gels increased at depths >20 cm, and the extent of adsorption was most likely controlled by the competitive effects of dissolved phosphate. Sediment As adsorption capacity appeared to be controlled by changes in porewater composition and competitive effects at shallower depths, and by reductive dissolution and availability of sorption sites at greater burial depths. ?? 2008 American Chemical Society.

  8. Measurement and evaluation of the effects of pH gradients on the antimicrobial and antivirulence activities of chitosan nanoparticles in Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Fadilah Sfouq Aleanizy

    2018-01-01

    Full Text Available Objective: The purpose of this study was to study the antimicrobial activity of chitosan nanoparticles (CSNPs on Pseudomonas aeruginosa with special emphasis on their sensitivity to pH and the effect of pH on their activity. Methodology: Antimicrobial activity of CSNPs against Pseudomonas aeruginosa at different pH was tested using broth dilution method. Further assessment of antivirulence activity and sensitization of CSNPs on Pseudomonas aeruginosa were examined. Results: Significant antimicrobial effects of CSNPs against Pseudomonas aeruginosa were detected at slightly acidic pH 5, whereas the activity was abolished at a pH of greater than 7. The antivirulence activity of CSNPs was then investigated and treatment with CSNPs (1000 ppm resulted in a significant reduction or even complete inhibition of pyocyanin production by P. aeruginosa compared with untreated P. aeruginosa indicating the antivirulence activity of CSNPs. CSNPs also sensitized P. aeruginosa to the lytic effects of sodium dodecyl sulfate (SDS; such sensitization was not blocked by washing chitosan-treated cells prior to SDS exposure revealing that CSNPs disturb the outer membrane leading to irreversible sensitivity to detergent even at low concentration (100 ppm. Conclusions: These findings highlight CSNPs as potentially useful as indirect antimicrobial agents for a variety of applications. Keywords: Chitosan nanoparticles, Pseudomonas aeruginosa, pH, Antimicrobial, Virulence

  9. Energy performance contracting - energy saving potential of selected energy conservation measures (ECM)

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, M. (Dansk Energi Analyse A/S, Frederiksberg (Denmark)); Langkilde, G.; Olesen, Bjarne W. (Technical Univ. of Denmark, ICIEE, Kgs. Lyngby (Denmark)); Moerck, O. (Cenergia Energy Consultants, Herlev (Denmark)); Sundman, O. (DONG Energy, Copenhagen (Denmark)); Engelund Thomsen, K. (Aalborg Univ., SBi, Hoersholm (Denmark))

    2008-09-15

    This report has been developed under the research project 'Etablering af grundlag for energitjenester i Danmark' (project number: ENS-33031-0185) under the Danish research programme - EFP. The objective of this project has been to contribute to the utilisation of the large potential for energy conservations in the building sector within the public, industry and service sectors through the development of a better basis for decision making for both the Energy Service Companies (ESCOes) and the building owners. The EU directive on Energy Service Contracting points at the buildings as the area where the biggest potential market for energy services and energy efficiency improvements are. The EFP-project has two parts: (1) A Danish part and (2) participation in the international cooperation project 'Holistic Assesment Tool-Kit on Energy Efficient Retrofit Measures for Government Buildings (EnERGo)', Annex 46 under the IEA R and D program 'Energy Conservation In Buildings And Community Systems' (ECBCS). This report describes the Danish contributions to the IEA projects subtask B, which has a primary objective to develop a database of energy conservation measures (ECM) with descriptions and performance characteristics of these. (au)

  10. Energy performance contracting - energy saving potential of selected energy conservation measures (ECM)

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, M [Dansk Energi Analyse A/S, Frederiksberg (Denmark); Langkilde, G; Olesen, Bjarne W [Technical Univ. of Denmark, ICIEE, Kgs. Lyngby (Denmark); Moerck, O [Cenergia Energy Consultants, Herlev (Denmark); Sundman, O [DONG Energy, Copenhagen (Denmark); Engelund Thomsen, K [Aalborg Univ., SBi, Hoersholm (Denmark)

    2008-09-15

    This report has been developed under the research project 'Etablering af grundlag for energitjenester i Danmark' (project number: ENS-33031-0185) under the Danish research programme - EFP. The objective of this project has been to contribute to the utilisation of the large potential for energy conservations in the building sector within the public, industry and service sectors through the development of a better basis for decision making for both the Energy Service Companies (ESCOes) and the building owners. The EU directive on Energy Service Contracting points at the buildings as the area where the biggest potential market for energy services and energy efficiency improvements are. The EFP-project has two parts: (1) A Danish part and (2) participation in the international cooperation project 'Holistic Assesment Tool-Kit on Energy Efficient Retrofit Measures for Government Buildings (EnERGo)', Annex 46 under the IEA R and D program 'Energy Conservation In Buildings And Community Systems' (ECBCS). This report describes the Danish contributions to the IEA projects subtask B, which has a primary objective to develop a database of energy conservation measures (ECM) with descriptions and performance characteristics of these. (au)

  11. Marine and Hydrokinetic Renewable Energy Technologies: Potential Navigational Impacts and Mitigation Measures

    Energy Technology Data Exchange (ETDEWEB)

    Cool, Richard, M.; Hudon, Thomas, J.; Basco, David, R.; Rondorf, Neil, E.

    2009-12-10

    On April 15, 2008, the Department of Energy (DOE) issued a Funding Opportunity Announcement for Advanced Water Power Projects which included a Topic Area for Marine and Hydrokinetic Renewable Energy Market Acceleration Projects. Within this Topic Area, DOE identified potential navigational impacts of marine and hydrokinetic renewable energy technologies and measures to prevent adverse impacts on navigation as a sub-topic area. DOE defines marine and hydrokinetic technologies as those capable of utilizing one or more of the following resource categories for energy generation: ocean waves; tides or ocean currents; free flowing water in rivers or streams; and energy generation from the differentials in ocean temperature. PCCI was awarded Cooperative Agreement DE-FC36-08GO18177 from the DOE to identify the potential navigational impacts and mitigation measures for marine hydrokinetic technologies, as summarized herein. The contract also required cooperation with the U.S. Coast Guard (USCG) and two recipients of awards (Pacific Energy Ventures and reVision) in a sub-topic area to develop a protocol to identify streamlined, best-siting practices. Over the period of this contract, PCCI and our sub-consultants, David Basco, Ph.D., and Neil Rondorf of Science Applications International Corporation, met with USCG headquarters personnel, with U.S. Army Corps of Engineers headquarters and regional personnel, with U.S. Navy regional personnel and other ocean users in order to develop an understanding of existing practices for the identification of navigational impacts that might occur during construction, operation, maintenance, and decommissioning. At these same meetings, “standard” and potential mitigation measures were discussed so that guidance could be prepared for project developers. Concurrently, PCCI reviewed navigation guidance published by the USCG and international community. This report summarizes the results of this effort, provides guidance in the form of a

  12. A tool for evaluating the potential for cost-effective outcomes measurement

    Directory of Open Access Journals (Sweden)

    Somasekhar MM

    2012-04-01

    Full Text Available Melinda M Somasekhar1, Alfred Bove2, Chris Rausch1, James Degnan3, Cathy T King1, Arnold Meyer11The Albert J Finestone, MD, Office for Continuing Medical Education, 2Section of Cardiology, Temple University School of Medicine, Philadelphia, PA, USA; 3Measurement and Research Center, Temple University, Philadelphia, PA, USAAbstract: Cost related to higher-level outcomes measurement is often very high. However, the cost burden is felt even more by smaller, less well-funded continuing medical education (CME programs. It is possible to overcome financial and participant-related barriers to measuring Level 6 outcomes, which are patient health outcomes. The Temple University School of Medicine’s Office for Continuing Medical Education developed a sequential tool for attaining cost-effective outcomes measurement for determining the likelihood of a CME intervention to produce significant changes in physician performance. The appropriate selection of the CME topic and specific practice change indictors drive this tool. This tool walks providers through a simple YES or NO decision-making list that guides them toward an accurate prediction of potential programmatic outcomes. Factors considered during the decision-making process include whether: (a the intended change(s will have a substantial impact on current practice; (b the intended practice change(s are well supported by clinical data, specialty organization/government recommendations, expert opinion, etc; (c the potential change(s affects a large population; (d external factors, such as system pressures, media pressures, financial pressures, patient pressures, safety pressures, etc, are driving this intended change in performance; (e there is a strong motivation on the part of physicians to implement the intended change(s; and (f the intended change(s is relatively easy to implement within any system of practice. If each of these questions can be responded to positively, there is a higher likelihood

  13. Effect of potassium-salt muds on gamma ray, and spontaneous potential measurements

    International Nuclear Information System (INIS)

    Cox, J.W.; Raymer, L.L.

    1976-01-01

    Interpretations of the gamma ray and Spontaneous Potential curves generally assume the presence of sodium chloride as the dominant salt in both the formation water and the mud filtrate. However, potassium-salt muds are increasingly being used by the oil industry. The potassium cation is significantly different from the sodium cation in its radioactive and electrochemical properties. Natural potassium contains a radioactive isotope which emits gamma rays. Thus, the presence of potassium salts in the mud system may contribute to Gamma-Ray tool response. Since the Gamma Ray is used quantitatively in many geological sequences as an indicator of clay content, a way to correct for the effect of potassium in the mud column is desirable. Correction methods and charts based on laboratory measurements and field observations are presented. The effect of temperature on the resistivity of potassium muds is also briefly discussed. From data available, it appears to be similar to that for NaCl muds. On the bases of field observations and laboratory work, the electrochemical properties of potassium-chloride and potassium-carbonate muds and mud filtrates are discussed. Activity relationships are proposed, and the influence of these salts on the SP component potentials--namely, the liquid-junction, membrane, and bi-ionic potentials--is described. Several field examples are presented

  14. New Directions in EEG Measurement: an Investigation into the Fidelity of Electrical Potential Sensor Signals

    Directory of Open Access Journals (Sweden)

    M. FATOORECHI

    2015-01-01

    Full Text Available Low frequency noise performance is the key indicator in determining the signal to noise ratio of a capacitively coupled sensor when used to acquire electroencephalogram signals. For this reason, a prototype Electric Potential Sensor device based on an auto-zero operational amplifier has been developed and evaluated. The absence of 1/f noise in these devices makes them ideal for use with signal frequencies ~10 Hz or less. The active electrodes are designed to be physically and electrically robust and chemically and biochemically inert. They are electrically insulated (anodized and have diameters of 12 mm or 18 mm. In both cases, the sensors are housed in inert stainless steel machined housings with the electronics fabricated in surface mount components on a printed circuit board compatible with epoxy potting compounds. Potted sensors are designed to be immersed in alcohol for sterilization purposes. A comparative study was conducted with a commercial wet gel electrode system. These studies comprised measurements of both free running electroencephalogram and Event Related Potentials. Quality of the recorded electroencephalogram was assessed using three methods of inspection of raw signal, comparing signal to noise ratios, and Event Related Potentials noise analysis. A strictly comparable signal to noise ratio was observed and the overall conclusion from these comparative studies is that the noise performance of the new sensor is appropriate.

  15. Gradient algorithm applied to laboratory quantum control

    International Nuclear Information System (INIS)

    Roslund, Jonathan; Rabitz, Herschel

    2009-01-01

    The exploration of a quantum control landscape, which is the physical observable as a function of the control variables, is fundamental for understanding the ability to perform observable optimization in the laboratory. For high control variable dimensions, trajectory-based methods provide a means for performing such systematic explorations by exploiting the measured gradient of the observable with respect to the control variables. This paper presents a practical, robust, easily implemented statistical method for obtaining the gradient on a general quantum control landscape in the presence of noise. In order to demonstrate the method's utility, the experimentally measured gradient is utilized as input in steepest-ascent trajectories on the landscapes of three model quantum control problems: spectrally filtered and integrated second harmonic generation as well as excitation of atomic rubidium. The gradient algorithm achieves efficiency gains of up to approximately three times that of the standard genetic algorithm and, as such, is a promising tool for meeting quantum control optimization goals as well as landscape analyses. The landscape trajectories directed by the gradient should aid in the continued investigation and understanding of controlled quantum phenomena.

  16. NIF optics phase gradient specfication

    International Nuclear Information System (INIS)

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-01-01

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of ∼80 angstrom/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS ampersand T personnel

  17. Temperature measurement by thermal strain imaging with diagnostic power ultrasound, with potential for thermal index determination.

    Science.gov (United States)

    Liang, Hai-Dong; Zhou, Li-Xia; Wells, Peter N T; Halliwell, Michael

    2009-05-01

    Over the years, there has been a substantial increase in acoustic exposure in diagnostic ultrasound as new imaging modalities with higher intensities and frame rates have been introduced; and more electronic components have been packed into the probe head, so that there is a tendency for it to become hotter. With respect to potential thermal effects, including those which may be hazardous occurring during ultrasound scanning, there is a correspondingly growing need for in vivo techniques to guide the operator as to the actual temperature rise occurring in the examined tissues. Therefore, an in vivo temperature estimator would be of considerable practical value. The commonly-used method of tissue thermal index (TI) measurement with a hydrophone in water could underestimate the actual value of TI (in one report by as much as 2.9 times). To obtain meaningful results, it is necessary to map the temperature elevation in 2-D (or 3-D) space. We present methodology, results and validation of a 2-D spatial and temporal thermal strain ultrasound temperature estimation technique in phantoms, and its apparently novel application in tracking the evolution of heat deposition at diagnostic exposure levels. The same ultrasound probe is used for both transmission and reception. The displacement and thermal strain estimation methods are similar to those used in high-intensity focused ultrasound thermal monitoring. The use of radiofrequency signals permits the application of cross correlation as a similarity measurement for tracking feature displacement. The displacement is used to calculate the thermal strain directly related to the temperature rise. Good agreement was observed between the temperature rise and the ultrasound power and scan duration. Thermal strain up to 1.4% was observed during 4000-s scan. Based on the results obtained for the temperature range studied in this work, the technique demonstrates potential for applicability in phantom (and possibly in vivo tissue

  18. Evaluating the Response of Biological Assemblages as Potential Indicators for Restoration Measures in an Intermittent Mediterranean River

    Science.gov (United States)

    Hughes, Samantha Jane; Santos, Jose; Ferreira, Teresa; Mendes, Ana

    2010-08-01

    Bioindicators are essential for detecting environmental degradation and for assessing the success of river restoration initiatives. River restoration projects require the identification of environmental and pressure gradients that affect the river system under study and the selection of suitable indicators to assess habitat quality before, during and after restoration. We assessed the response of benthic macroinvertebrates, fish, bird and macrophyte assemblages to environmental and pressure gradients from sites situated upstream and downstream of a cofferdam on the River Odelouca, an intermittent Mediterranean river in southwest Portugal. The Odelouca will be permanently dammed in 2010. Principal Component Analyses (PCA) of environmental and pressure variables revealed that most variance was explained by environmental factors that clearly separated sites upstream and downstream of the partially built cofferdam. The pressure gradient describing physical impacts to the banks and channel as a result of land use change was less distinct. Redundancy Analysis revealed significant levels of explained variance to species distribution patterns in relation to environmental and pressure variables for all 4 biological assemblages. Partial Redundancy analyses revealed high levels of redundancy for pH between groups and that the avifauna was best associated with pressures acting upon the system. Patterns in invertebrates and fish were associated with descriptors of habitat quality, although fish distribution patterns were affected by reduced connectivity. Procrustean and RELATE (Mantel test) analyses gave broadly similar results and supported these findings. We give suggestions on the suitability of key indicator groups such as benthic macroinvertebrates and endemic fish species to assess in stream habitat quality and appropriate restoration measures, such as the release of peak flow patterns that mimic intermittent Mediterranean systems to combat habitat fragmentation and

  19. Gradient measurements of gaseous elemental mercury (Hg0) in the marine boundary layer of the northwest Sea of Japan (East Sea).

    Science.gov (United States)

    Kalinchuk, Viktor; Lopatnikov, Evgeny; Astakhov, Anatoly

    2018-06-01

    Gaseous elemental mercury (Hg 0 ) is a prolific and persistent contaminant in the atmosphere. Atmospheric concentrations of Hg 0 were determined from 17 September to 7 October 2015 in the northwest Sea of Japan aboard the Russian research vessel Professor Gagarinsky. Simultaneous measurements of Hg 0 concentrations were performed 2 m and 20 m above the sea surface using automatic Hg 0 analysers RA-915M and RA-915+, respectively. Concentrations ranged from 0.3 to 25.9 ng/m 3 (n = 5207) and from 0.3 to 27.8 ng/m 3 (n = 4415), with medians of 1.7 and 1.6 ng/m 3 , respectively. Elevated Hg 0 was observed during three episodes from 19 to 22 September, likely caused by one or more of the following factors: 1) atmospheric transport of Hg 0 from the west and south-west (from N. Korea, China, and the Yellow Sea region); 2) Hg 0 emission from the sea due to pollution by water from the Tumannaya River; or 3) underwater geological activities. Increased Hg 0 concentration was observed during periods when air masses flowed from the south, and low concentrations were observed when air masses came from the north. A daytime increase of Hg 0 concentrations at a height of 2 m occurred simultaneously with decreasing Hg 0 at a height of 20 m. These diurnal variations suggest that two contrasting processes occur during the daytime in the marine boundary layer (MBL): Hg 0 emission from the sea surface and Hg 0 oxidation in the MBL by active halogens formed by photolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Energy usage and technical potential for energy saving measures in the Swedish residential building stock

    International Nuclear Information System (INIS)

    Mata, Érika; Sasic Kalagasidis, Angela; Johnsson, Filip

    2013-01-01

    This paper provides an analysis of the current energy usage (net energy and final energy by fuels) and associated carbon dioxide (CO 2 ) emissions of the Swedish residential building stock, which includes single-family dwellings and multi-family dwellings. Twelve energy saving measures (ESMs) are assessed using a bottom–up modeling methodology, in which the Swedish residential stock is represented by a sample of 1400 buildings (based on data from the year 2005). Application of the ESMs studied gives a maximum technical reduction potential in energy demand of 53%, corresponding to a 63% reduction in CO 2 emissions. Although application of the investigated ESMs would reduce CO 2 emissions, the measures that reduce electricity consumption for lighting and appliances (LA) will increase CO 2 emissions, since the saved electricity production is less CO 2 -intensive than the fuel mix used for the increased space heating required to make up for the loss in indirect heating obtained from LA. - Highlights: ► Analysis of year 2005energy use and CO2 emissions of Swedish residential buildings. ► Includes all single-family dwellings and multi-family dwellings. ► Bottom–up modeling of building stock represented by 1400 buildings. ► Technical effects of 12 energy saving measures are assessed. ► Energy demand can be reduced by53% and associated CO 2 emissions by 63%

  1. Influence of crack length on crack depth measurement by an alternating current potential drop technique

    International Nuclear Information System (INIS)

    Raja, Manoj K; Mahadevan, S; Rao, B P C; Behera, S P; Jayakumar, T; Raj, Baldev

    2010-01-01

    An alternating current potential drop (ACPD) technique is used for sizing depth of surface cracks in metallic components. Crack depth estimations are prone to large deviations when ACPD measurements are made on very shallow and finite length cracks, especially in low conducting materials such as austenitic stainless steel (SS). Detailed studies have been carried out to investigate the influence of crack length and aspect ratio (length to depth) on depth estimation by performing measurements on electric discharge machined notches with the aspect ratio in the range of 1 to 40 in SS plates. In notches with finite length, an additional path for current to flow through the surface along the length is available causing the notch depths to be underestimated. The experimentally observed deviation in notch depth estimates is explained from a simple mathematical approach using the equivalent resistive circuit model based on the additional path available for the current to flow. A scheme is proposed to accurately measure the depth of cracks with finite lengths in SS components

  2. Post-use assay of vaginal rings (VRs) as a potential measure of clinical trial adherence.

    Science.gov (United States)

    Spence, Patrick; Nel, Annalene; van Niekerk, Neliëtte; Derrick, Tiffany; Wilder, Susan; Devlin, Bríd

    2016-06-05

    Adherence measurement for microbicide use within the clinical trial setting remains a challenge for the HIV prevention field. This paper describes an assay method used for determining residual dapivirine levels in post-use vaginal rings from clinical trials conducted with the Dapivirine Vaginal Matrix Ring-004 developed by the International Partnership for Microbicides to prevent male to female HIV transmission. Post-use assay results from three Ring-004 clinical trials showed that of the 25mg drug load, approximately 4mg of dapivirine is released from the matrix ring over a 28-day use period. Data obtained by both in vitro and in vivo studies indicate that dapivirine is released according to a diffusion mechanism, as determined by conformance of both data sets to the Higuchi equation. This, coupled with the low variability associated with batch production over two manufacturing sites and 20 batches of material, provides evidence that post-use ring analysis can contribute to the assessment of adherence to ring use. Limitations of this method include the potential of intra-participant and inter-participant variability and uncertainty associated with measuring the low amount of dapivirine actually released relative to the drug load. Therefore, residual drug levels should not serve as the only direct measurement for microbicide adherence in vaginal ring clinical trials but should preferably be used as part of a multi-pronged approach towards understanding and assessing adherence to vaginal ring use. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Inversion gradients for acoustic VTI wavefield tomography

    KAUST Repository

    Li, Vladimir; Wang, Hui; Tsvankin, Ilya; Dí az, Esteban; Alkhalifah, Tariq Ali

    2017-01-01

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a generalized pseudospectral operator based on a separable approximation for the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified image-power objective functions. We also obtain the gradient expressions for a data-domain objective function that can more easily incorporate borehole information necessary for stable VTI velocity analysis. These gradients are similar to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations but the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show the potential advantages of the modified image-power objective function in estimating the anellipticity parameter η.

  4. Inversion gradients for acoustic VTI wavefield tomography

    KAUST Repository

    Li, Vladimir

    2017-03-21

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a generalized pseudospectral operator based on a separable approximation for the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified image-power objective functions. We also obtain the gradient expressions for a data-domain objective function that can more easily incorporate borehole information necessary for stable VTI velocity analysis. These gradients are similar to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations but the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show the potential advantages of the modified image-power objective function in estimating the anellipticity parameter η.

  5. Wetting of flat gradient surfaces.

    Science.gov (United States)

    Bormashenko, Edward

    2018-04-01

    Gradient, chemically modified, flat surfaces enable directed transport of droplets. Calculation of apparent contact angles inherent for gradient surfaces is challenging even for atomically flat ones. Wetting of gradient, flat solid surfaces is treated within the variational approach, under which the contact line is free to move along the substrate. Transversality conditions of the variational problem give rise to the generalized Young equation valid for gradient solid surfaces. The apparent (equilibrium) contact angle of a droplet, placed on a gradient surface depends on the radius of the contact line and the values of derivatives of interfacial tensions. The linear approximation of the problem is considered. It is demonstrated that the contact angle hysteresis is inevitable on gradient surfaces. Electrowetting of gradient surfaces is discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Estudio coste-efectividad sobre la medición del gradiente de presión venosa hepática en la profilaxis secundaria de la hemorragia digestiva varicosa A cost-effectiveness study of hepatic venous pressure gradient measurement in the secondary prevention of variceal bleeding

    Directory of Open Access Journals (Sweden)

    A. Amorós

    2008-07-01

    favorable comparado con la no realización del mismo.Objective: variceal rebleeding is common following a first episode of hemorrhage in cirrhotic patients. The objective of this study was to determine the cost-effectiveness of monitoring hepatic venous pressure gradient (HVPG to guide secondary prophylaxis. Methods: we created a Markov decision model to calculate cost-effectiveness for two strategies: Group 1: HVPG monitoring to decide treatment -when portal pressure was reduced by at least 20 percent or HVPG was less than 12 mmHg after beta-blocker administration, patients received beta-blockers; when portal pressure did not meet these criteria therapy was endoscopic band ligation. Group 2: in this group there was no monitoring of HVPG. Patients with large varices received treatment with beta-blockers combined with EBL; patients with small varices received beta-blockers plus isosorbide mononitrate. Results: there was no recurrent variceal bleeding in group 1 for good responders, and for 17% of poor responders. In group 2 a 25% rebleeding rate was detected in patients with small varices and 13% for those with big varices. Overall cost in group 1 was 14,100.49 euros, and 14,677.16 in group 2. Conclusions: HVPG measurement is cost-effective for the secondary prophylaxis of variceal bleeding.

  7. Investigation of potential factors affecting the measurement of dew point temperature in oil-soaked transformers

    Science.gov (United States)

    Kraus, Adam H.

    Moisture within a transformer's insulation system has been proven to degrade its dielectric strength. When installing a transformer in situ, one method used to calculate the moisture content of the transformer insulation is to measure the dew point temperature of the internal gas volume of the transformer tank. There are two instruments commercially available that are designed for dew point temperature measurement: the Alnor Model 7000 Dewpointer and the Vaisala DRYCAPRTM Hand-Held Dewpoint Meter DM70. Although these instruments perform an identical task, the design technology behind each instrument is vastly different. When the Alnor Dewpointer and Vaisala DM70 instruments are used to measure the dew point of the internal gas volume simultaneously from a pressurized transformer, their differences in dew point measurement have been observed to vary as much as 30 °F. There is minimal scientific research available that focuses on the process of measuring dew point of a gas inside a pressurized transformer, let alone this observed phenomenon. The primary objective of this work was to determine what effect certain factors potentially have on dew point measurements of a transformer's internal gas volume, in hopes of understanding the root cause of this phenomenon. Three factors that were studied include (1) human error, (2) the use of calibrated and out-of-calibration instruments, and (3) the presence of oil vapor gases in the dry air sample, and their subsequent effects on the Q-value of the sampled gas. After completing this portion of testing, none of the selected variables proved to be a direct cause of the observed discrepancies between the two instruments. The secondary objective was to validate the accuracy of each instrument as compared to its respective published range by testing against a known dew point temperature produced by a humidity generator. In a select operating range of -22 °F to -4 °F, both instruments were found to be accurate and within their

  8. Jupiter's evolution with primordial composition gradients

    Science.gov (United States)

    Vazan, Allona; Helled, Ravit; Guillot, Tristan

    2018-02-01

    Recent formation and structure models of Jupiter suggest that the planet can have composition gradients and not be fully convective (adiabatic). This possibility directly affects our understanding of Jupiter's bulk composition and origin. In this Letter we present Jupiter's evolution with a primordial structure consisting of a relatively steep heavy-element gradient of 40 M⊕. We show that for a primordial structure with composition gradients, most of the mixing occurs in the outer part of the gradient during the early evolution (several 107 yr), leading to an adiabatic outer envelope (60% of Jupiter's mass). We find that the composition gradient in the deep interior persists, suggesting that 40% of Jupiter's mass can be non-adiabatic with a higher temperature than the one derived from Jupiter's atmospheric properties. The region that can potentially develop layered convection in Jupiter today is estimated to be limited to 10% of the mass. Movies associated to Figs. 1-3 are available at http://https://www.aanda.org

  9. Generation of tunable and pulsatile concentration gradients via microfluidic network

    KAUST Repository

    Zhou, Bingpu

    2014-06-04

    We demonstrate a compact Polydimethylsiloxane microfluidic chip which can quickly generate ten different chemical concentrations simultaneously. The concentration magnitude of each branch can be flexibly regulated based on the flow rate ratios of the two injecting streams. The temporal/pulsatile concentration gradients are achieved by integrating on-chip pneumatic actuated valves controlled by the external signals. The temporal concentration gradients can also be tuned precisely by varying applied frequency and duty cycle of the trigger signal. It is believed that such microdevice will be potentially used for some application areas of producing stable chemical gradients as well as allowing fast, pulsatile gradient transformation in seconds.

  10. Potentials and challenges associated with automated closed dynamic chamber measurements of soil CO2 fluxes

    Science.gov (United States)

    Görres, Carolyn-Monika; Kammann, Claudia; Ceulemans, Reinhart

    2015-04-01

    Soil respiration fluxes are influenced by natural factors such as climate and soil type, but also by anthropogenic activities in managed ecosystems. As a result, soil CO2 fluxes show a large intra- and interannual as well as intra- and intersite variability. Most of the available soil CO2 flux data giving insights into this variability have been measured with manually closed static chambers, but technological advances in the past 15 years have also led to an increased use of automated closed chamber systems. The great advantage of automated chambers in comparison to manually operated chambers is the higher temporal resolution of the flux data. This is especially important if we want to better understand the effects of short-term events, e.g. fertilization or heavy rainfall, on soil CO2 flux variability. However, the chamber method is an invasive measurement method which can potentially alter soil CO2 fluxes and lead to biased measurement results. In the peer-reviewed literature, many papers compare the field performance and results of different closed static chamber designs, or compare manual chambers with automated chamber systems, to identify potential biases in CO2 flux measurements, and thus help to reduce uncertainties in the flux data. However, inter-comparisons of different automated closed dynamic chamber systems are still lacking. Here we are going to present a field comparison of the most-cited automated chamber system, the LI-8100A Automated Soil Flux System, with the also commercially available Greenhouse Gas Monitoring System AGPS. Both measurement systems were installed side by side at a recently harvested poplar bioenergy plantation (POPFULL, http://uahost.uantwerpen.be/popfull/) from April 2014 until August 2014. The plantation provided optimal comparison conditions with a bare field situation after the harvest and a regrowing canopy resulting in a broad variety of microclimates. Furthermore, the plantation was planted in a double-row system with

  11. MiOXSYS: a novel method of measuring oxidation reduction potential in semen and seminal plasma.

    Science.gov (United States)

    Agarwal, Ashok; Sharma, Rakesh; Roychoudhury, Shubhadeep; Du Plessis, Stefan; Sabanegh, Edmund

    2016-09-01

    To measure oxidative reduction potential (ORP) in semen and seminal plasma and to establish their reference levels. ORP levels were measured in semen and seminal plasma. Tertiary hospital. Twenty-six controls and 33 infertile men. None. Static ORP (sORP) and capacitance ORP (cORP) were measured in semen and seminal plasma at time 0 and 120 minutes. Correlation of ORP was assessed between [1] semen and seminal plasma and [2] time 0 and 120 minutes. The association with sperm parameters was studied in (a) controls and (b) infertile patients, and a receiver operating characteristic curve was generated to establish the sORP cutoff. Semen sORP and cORP levels were associated with seminal plasma levels at time 0 and time 120 minutes. In controls and infertile patients, an inverse relationship of sORP levels was established with concentration and total sperm count in semen as well as seminal plasma at time 0 and 120 minutes. Classification of subjects based on sperm motility showed that subjects with abnormal motility present with poor concentration, total count, morphology, and elevated levels of semen and seminal plasma sORP at time 120 minutes. The sORP cutoff of 1.48 in semen and 2.09 in seminal plasma based on motility was able to distinguish subjects with normal semen quality from those with abnormal semen quality. The MiOXSYS System can reliably measure ORP levels in semen and seminal plasma. ORP levels are not affected by semen age, making this new technology easy to employ in a clinical setting. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  12. Potential denitrification in arable soil samples at winter temperatures - measurements by 15N gas analysis

    International Nuclear Information System (INIS)

    Lippold, H.; Foerster, I.; Matzel, W.

    1989-01-01

    In samples from the plough horizon of five soils taken after cereal harvest, denitrification was measured as volatilization of N 2 and N 2 O from 15 N nitrate in the absence of O 2 . Nitrate contents lower than 50 ppm N (related to soil dry matter) had only a small effect on denitrification velocity in four of the five soils. In a clay soil dependence on nitrate concentration corresponded to a first-order reaction. Available C was no limiting factor. Even at zero temperatures remarkable N amounts (on average 0.2 ppm N per day) were still denitrified. The addition of daily turnover rates in relation to soil temperatures prevailing from December to March revealed potential turnovers in the 0-to-30-cm layer of the soils to average 28 ± 5 ppm N. (author)

  13. Correlation between event-related potentials and MR measurements in chronic alcoholic patients

    International Nuclear Information System (INIS)

    Kaseda, Yumiko; Miyazato, Yoshikazu; Ogura, Chikara; Nakamoto, Haruo; Uema, Takeshi; Yamamoto, Kazuyoshi; Ohta, Ikuya

    1994-01-01

    Event-related potentials were recorded in 25 abstinent alcoholics, and 25 gender- and age-matched controls during a two-tone discrimination (odd ball) task. All the subjects were free from medication and dextral. MR images were examined in the alcoholics. The amplitudes of N100, N200 and P300 in the alcoholics were reduced compared with those of the controls. In order to identify morphological changes responsible for ERP abnormalities, linear regression analyses were performed between ERP measures and MRI parameters. The amplitude of N100 was inversely correlated with ventricular size. The amplitudes of P300 were inversely correlated with both ventricular size and width of cortical sulci. It was suggested that the N100 abnormality was related to subcortical structure, and P300 alteration was related to both subcortical and cortical structures in the alcoholics. (author)

  14. Energy Balance for a Sonoluminescence Bubble Yields a Measure of Ionization Potential Lowering

    Science.gov (United States)

    Kappus, B.; Bataller, A.; Putterman, S. J.

    2013-12-01

    Application of energy conservation between input sound and the microplasma which forms at the moment of sonoluminescence places bounds on the process, whereby the gas is ionized. Detailed pulsed Mie scattering measurements of the radius versus time for a xenon bubble in sulfuric acid provide a complete characterization of the hydrodynamics and minimum radius. For a range of emission intensities, the blackbody spectrum emitted during collapse matches the minimum bubble radius, implying opaque conditions are attained. This requires a degree of ionization >36%. Analysis reveals only 2.1±0.6eV/atom of energy available during light emission. In order to unbind enough charge, collective processes must therefore reduce the ionization potential by at least 75%. We interpret this as evidence that a phase transition to a highly ionized plasma is occurring during sonoluminescence.

  15. Finite grid radius and thickness effects on retarding potential analyzer measured suprathermal electron density and temperature

    International Nuclear Information System (INIS)

    Knudsen, W.C.

    1992-01-01

    The effect of finite grid radius and thickness on the electron current measured by planar retarding potential analyzers (RPAs) is analyzed numerically. Depending on the plasma environment, the current is significantly reduced below that which is calculated using a theoretical equation derived for an idealized RPA having grids with infinite radius and vanishingly small thickness. A correction factor to the idealized theoretical equation is derived for the Pioneer Venus (PV) orbiter RPA (ORPA) for electron gases consisting of one or more components obeying Maxwell statistics. The error in density and temperature of Maxwellian electron distributions previously derived from ORPA data using the theoretical expression for the idealized ORPA is evaluated by comparing the densities and temperatures derived from a sample of PV ORPA data using the theoret