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Sample records for relaxation measurements comparison

  1. Finite magnetic relaxation in x-space magnetic particle imaging: Comparison of measurements and ferrohydrodynamic models.

    Science.gov (United States)

    Dhavalikar, R; Hensley, D; Maldonado-Camargo, L; Croft, L R; Ceron, S; Goodwill, P W; Conolly, S M; Rinaldi, C

    2016-08-03

    Magnetic Particle Imaging (MPI) is an emerging tomographic imaging technology that detects magnetic nanoparticle tracers by exploiting their non-linear magnetization properties. In order to predict the behavior of nanoparticles in an imager, it is possible to use a non-imaging MPI relaxometer or spectrometer to characterize the behavior of nanoparticles in a controlled setting. In this paper we explore the use of ferrohydrodynamic magnetization equations for predicting the response of particles in an MPI relaxometer. These include a magnetization equation developed by Shliomis (Sh) which has a constant relaxation time and a magnetization equation which uses a field-dependent relaxation time developed by Martsenyuk, Raikher and Shliomis (MRSh). We compare the predictions from these models with measurements and with the predictions based on the Langevin function that assumes instantaneous magnetization response of the nanoparticles. The results show good qualitative and quantitative agreement between the ferrohydrodynamic models and the measurements without the use of fitting parameters and provide further evidence of the potential of ferrohydrodynamic modeling in MPI.

  2. Quantitative comparison of errors in 15N transverse relaxation rates measured using various CPMG phasing schemes

    International Nuclear Information System (INIS)

    Myint Wazo; Cai Yufeng; Schiffer, Celia A.; Ishima, Rieko

    2012-01-01

    Nitrogen-15 Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation experiment are widely used to characterize protein backbone dynamics and chemical exchange parameters. Although an accurate value of the transverse relaxation rate, R 2 , is needed for accurate characterization of dynamics, the uncertainty in the R 2 value depends on the experimental settings and the details of the data analysis itself. Here, we present an analysis of the impact of CPMG pulse phase alternation on the accuracy of the 15 N CPMG R 2 . Our simulations show that R 2 can be obtained accurately for a relatively wide spectral width, either using the conventional phase cycle or using phase alternation when the r.f. pulse power is accurately calibrated. However, when the r.f. pulse is miscalibrated, the conventional CPMG experiment exhibits more significant uncertainties in R 2 caused by the off-resonance effect than does the phase alternation experiment. Our experiments show that this effect becomes manifest under the circumstance that the systematic error exceeds that arising from experimental noise. Furthermore, our results provide the means to estimate practical parameter settings that yield accurate values of 15 N transverse relaxation rates in the both CPMG experiments.

  3. Characterization of dynamics in complex lyophilized formulations: I. Comparison of relaxation times measured by isothermal calorimetry with data estimated from the width of the glass transition temperature region.

    Science.gov (United States)

    Chieng, Norman; Mizuno, Masayasu; Pikal, Michael

    2013-10-01

    The purposes of this study are to characterize the relaxation dynamics in complex freeze dried formulations and to investigate the quantitative relationship between the structural relaxation time as measured by thermal activity monitor (TAM) and that estimated from the width of the glass transition temperature (ΔT(g)). The latter method has advantages over TAM because it is simple and quick. As part of this objective, we evaluate the accuracy in estimating relaxation time data at higher temperatures (50 °C and 60 °C) from TAM data at lower temperature (40 °C) and glass transition region width (ΔT(g)) data obtained by differential scanning calorimetry. Formulations studied here were hydroxyethyl starch (HES)-disaccharide, HES-polyol, and HES-disaccharide-polyol at various ratios. We also re-examine, using TAM derived relaxation times, the correlation between protein stability (human growth hormone, hGH) and relaxation times explored in a previous report, which employed relaxation time data obtained from ΔT(g). Results show that most of the freeze dried formulations exist in single amorphous phase, and structural relaxation times were successfully measured for these systems. We find a reasonably good correlation between TAM measured relaxation times and corresponding data obtained from estimates based on ΔT(g), but the agreement is only qualitative. The comparison plot showed that TAM data are directly proportional to the 1/3 power of ΔT(g) data, after correcting for an offset. Nevertheless, the correlation between hGH stability and relaxation time remained qualitatively the same as found with using ΔT(g) derived relaxation data, and it was found that the modest extrapolation of TAM data to higher temperatures using ΔT(g) method and TAM data at 40 °C resulted in quantitative agreement with TAM measurements made at 50 °C and 60 °C, provided the TAM experiment temperature, is well below the Tg of the sample. Copyright © 2013 Elsevier B.V. All rights

  4. Relaxation strain measurements in cellular dislocation structures

    International Nuclear Information System (INIS)

    Tsai, C.Y.; Quesnel, D.J.

    1984-01-01

    The conventional picture of what happens during a stress relaxation usually involves imagining the response of a single dislocation to a steadily decreasing stress. The velocity of this dislocation decreases with decreasing stress in such a way that we can measure the stress dependence of the dislocation velocity. Analysis of the data from a different viewpoint enables us to calculate the apparent activation volume for the motion of the dislocation under the assumption of thermally activated glie. Conventional thinking about stress relaxation, however, does not consider the eventual fate of this dislocation. If the stress relaxes to a low enough level, it is clear that the dislocation must stop. This is consistent with the idea that we can determine the stress dependence of the dislocation velocity from relaxation data only for those cases where the dislocation's velocity is allowed to approach zero asymptotically, in short, for those cases where the dislocation never stops. This conflict poses a dilemma for the experimentalist. In real crystals, however, obstacles impede the dislocation's progress so that those dislocations which are stopped at a given stress will probably never resume motion under the influence of the steadily declining stress present during relaxation. Thus one could envision stress relaxation as a process of exhaustion of mobile dislocations, rather than a process of decreasing dislocation velocity. Clearly both points of view have merit and in reality both mechanisms contribute to the phenomena

  5. 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

  6. Comparison of Physiological and Psychological Relaxation Using Measurements of Heart Rate Variability, Prefrontal Cortex Activity, and Subjective Indexes after Completing Tasks with and without Foliage Plants.

    Science.gov (United States)

    Park, Sin-Ae; Song, Chorong; Oh, Yun-Ah; Miyazaki, Yoshifumi; Son, Ki-Cheol

    2017-09-20

    The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV), prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb) concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD) method and a profile of mood state questionnaire (POMS). Results showed that the natural logarithmic (ln) ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2-3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.

  7. Comparison of Physiological and Psychological Relaxation Using Measurements of Heart Rate Variability, Prefrontal Cortex Activity, and Subjective Indexes after Completing Tasks with and without Foliage Plants

    Directory of Open Access Journals (Sweden)

    Sin-Ae Park

    2017-09-01

    Full Text Available The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV, prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD method and a profile of mood state questionnaire (POMS. Results showed that the natural logarithmic (ln ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2–3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.

  8. Picosecond absorption relaxation measured with nanosecond laser photoacoustics

    OpenAIRE

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2010-01-01

    Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, b...

  9. Picosecond absorption relaxation measured with nanosecond laser photoacoustics.

    Science.gov (United States)

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2010-10-18

    Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials.

  10. Experimental comparison of diffusional nuclear magnetic relaxation theories using ZrHsub(1.684)

    International Nuclear Information System (INIS)

    Korn, C.; Goren, S.

    1984-01-01

    The spin-lattice relaxation time of hydrogen in ZrHsub(1.684) was measured at a resonance frequency of 16.69 MHz as a function of temperature in a temperature range where the major relaxation mechanism was hydrogen diffusion. This parameter was used to calculate the hydrogen jump frequencies using the theories of Bloembergen, Purcell and Pound (BPP), of Bustard and of Barton and Sholl. A comparison shows that the BPP theory gives results closest to Arrhenius-type behaviour. The diffusional activation energy was found to be 13.3 kcal mol -1 . (Auth.)

  11. MR pulse sequences for selective relaxation time measurements: a phantom study

    DEFF Research Database (Denmark)

    Thomsen, C; Jensen, K E; Jensen, M

    1990-01-01

    a Siemens Magnetom wholebody magnetic resonance scanner operating at 1.5 Tesla was used. For comparison six imaging pulse sequences for relaxation time measurements were tested on the same phantom. The spectroscopic pulse sequences all had an accuracy better than 10% of the reference values....

  12. Measuring the equations of state in a relaxed magnetohydrodynamic plasma

    Science.gov (United States)

    Kaur, M.; Barbano, L. J.; Suen-Lewis, E. M.; Shrock, J. E.; Light, A. D.; Brown, M. R.; Schaffner, D. A.

    2018-01-01

    We report measurements of the equations of state of a fully relaxed magnetohydrodynamic (MHD) laboratory plasma. Parcels of magnetized plasma, called Taylor states, are formed in a coaxial magnetized plasma gun, and are allowed to relax and drift into a closed flux conserving volume. Density, ion temperature, and magnetic field are measured as a function of time as the Taylor states compress and heat. The theoretically predicted MHD and double adiabatic equations of state are compared to experimental measurements. We find that the MHD equation of state is inconsistent with our data.

  13. Introduction to electronic relaxation in solids: mechanisms and measuring techniques

    International Nuclear Information System (INIS)

    Bonville, P.

    1983-01-01

    The fluctuations of electronic magnetic moments in solids may be investigated by several techniques, either electronic or nuclear. This paper is an introduction of the most frequently encountered paramagnetic relaxation mechanisms (phonons, conduction electrons, exchange or dipolar interactions) in condensed matter, and to the different techniques used for measuring relaxation frequencies: electronic paramagnetic resonance, nuclear magnetic resonance, Moessbauer spectroscopy, inelastic neutron scattering, measurement of longitudinal ac susceptibility and γ-γ perturbed angular correlations. We mainly focus our attention on individual ionic fluctuation spectra, the majority of the experimental work refered to concerning rare earth systems [fr

  14. Resonant tunneling measurements of size-induced strain relaxation

    Science.gov (United States)

    Akyuz, Can Deniz

    Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of

  15. Comparison of the two relaxation peaks in the Ti50Ni48Fe2 alloy

    International Nuclear Information System (INIS)

    Fan Genlian; Zhou Yumei; Otsuka, Kazuhiro; Ren Xiaobing; Suzuki, Tetsuro; Yin Fuxing

    2009-01-01

    The internal friction (tan δ) and storage modulus of Ti 50 Ni 48 Fe 2 alloy were studied by dynamic mechanical analysis (DMA). On cooling, a broad relaxation peak with tan δ value as high as 0.2 was detected in R-phase. On heating, another relaxation peak with tan δ value of 0.06 was found in B19' martensite. Both relaxation peaks disappeared when the alloy was dehydrogenated in a dynamic vacuum furnace. Thus, the origin of both relaxation peaks was attributed to the interaction between twin boundaries and hydrogen atoms, as recently proved in Ti-Ni-Cu alloy. The direct comparison of these two relaxation peaks in the same sample indicates that the height of relaxation peaks increases with the decreasing of twinning shear.

  16. A Comparison of Meditation with Other Relaxation Techniques.

    Science.gov (United States)

    Fling, Sheila

    This paper critiques a negative 1984 review, "Meditation and Somatic Arousal Reduction" (Holmes), on the absolute effectiveness of meditation in reducing somatic arousal and reviews research on the relative effectiveness of meditation compared to techniques such as biofeedback, hypnosis, progressive muscle relaxation, and autogenics in…

  17. Plasma density measurements from the GEOS-1 relaxation sounder

    International Nuclear Information System (INIS)

    Etcheto, J.; Bloch, J.J.

    1978-01-01

    The relaxation sounder uses the characteristics of the propagation of radiowaves to sound the plasma surrounding the spacecraft. It determines, in particular, the plasma frequency, which gives the electron density. Measurements over the whole dayside of the magnetosphere, from the evening to the night sectors, are now available. The behaviour of the plasma resonance depends on local time, the nighttime echoes being generally weaker. Density measurements thus obtained are shown and discussed in the context of what is presently known about the plasma distribution in the magnetosphere. In particular, the density around apogee is studied as a function of magnetic activity. On the dayside, it appears to vary between a few and a few tens of electrons per cubic centimeter. The evolution of the density profile for several consecutive days is studied and interpreted tracing back the drift of the particles. (Auth.)

  18. A simple measurement method of molecular relaxation in a gas by reconstructing acoustic velocity dispersion

    Science.gov (United States)

    Zhu, Ming; Liu, Tingting; Zhang, Xiangqun; Li, Caiyun

    2018-01-01

    Recently, a decomposition method of acoustic relaxation absorption spectra was used to capture the entire molecular multimode relaxation process of gas. In this method, the acoustic attenuation and phase velocity were measured jointly based on the relaxation absorption spectra. However, fast and accurate measurements of the acoustic attenuation remain challenging. In this paper, we present a method of capturing the molecular relaxation process by only measuring acoustic velocity, without the necessity of obtaining acoustic absorption. The method is based on the fact that the frequency-dependent velocity dispersion of a multi-relaxation process in a gas is the serial connection of the dispersions of interior single-relaxation processes. Thus, one can capture the relaxation times and relaxation strengths of N decomposed single-relaxation dispersions to reconstruct the entire multi-relaxation dispersion using the measurements of acoustic velocity at 2N  +  1 frequencies. The reconstructed dispersion spectra are in good agreement with experimental data for various gases and mixtures. The simulations also demonstrate the robustness of our reconstructive method.

  19. Solute induced relaxation in glassy polymers: Experimental measurements and nonequilibrium thermodynamic model

    International Nuclear Information System (INIS)

    Minelli, Matteo; Doghieri, Ferruccio

    2014-01-01

    Data for kinetics of mass uptake from vapor sorption experiments in thin glassy polymer samples are here interpreted in terms of relaxation times for volume dilation. To this result, both models from non-equilibrium thermodynamics and from mechanics of volume relaxation contribute. Different kind of sorption experiments have been considered in order to facilitate the direct comparison between kinetics of solute induced volume dilation and corresponding data from process driven by pressure or temperature jumps

  20. Development of stress relaxation measurement by a small size C-ring specimen method

    International Nuclear Information System (INIS)

    Shimanuki, Shizuka; Nakata, Kiyotomo; Kasahara, Shigeki; Kuniya, Jiro

    2002-01-01

    A stress relaxation measurement method has been developed by using C-ring specimens, and a specimen size effect has been evaluated taking radiation-induced stress relaxation into consideration. C-ring specimens were stressed by forcing a wedge in the gap. Giving an appropriate eccentric configuration in the half of the ring opposite the gap, the stress gradient along the circumference was eliminated in the section and the stress level could be varied by changing the gap spacing. The validity of the C-ring test method was confirmed by thermally stress relaxation experiments at annealing temperatures from 300 to 600degC for 1 min to 200 h in carbon steel: considerable stress relaxation could be measured for all levels of applied stress even at relatively low annealing temperatures. The relaxation results obtained from the C-ring test were in good agreement with those from a uniaxial tensile stress relaxation test. The smaller C-ring specimen with about 40 mm diameter, which is required for radiation-induced stress relaxation test, also showed adequate accuracy on stress relaxation at 600 to 830degC in stainless steel, compared with the large size C-ring specimen test. (author)

  1. Relaxation parameter estimation and comparison of NLS and LLS methods for DCE MRI in the cervix

    DEFF Research Database (Denmark)

    Mariager, Christian; Kallehauge, Jesper; Tanderup, Kari

    Dynamic Contrast Enhanced (DCE) MRI is a promising tool for tumor treatment planning. However, prior knowledge of the T1 value within each tumor voxel is needed to utilize this technique. Therefore, a T1 relaxation measurement is performed before the DCE experiment to establish a baseline, before...... any injection of contrast agent. This T1 relaxation measurement is often performed using a variable flip angle spoiled gradient recalled echo (SPGR) sequence. T1 can then be estimated using either a linear least squares (LLS) or a non-linear least squares (NLS) fitting algorithm....

  2. Suppression of Raman electron spin relaxation of radicals in crystals. Comparison of Cu2+ and free radical relaxation in triglycine sulfate and Tutton salt single crystals.

    Science.gov (United States)

    Hoffmann, S K; Goslar, J; Lijewski, S

    2011-08-31

    Electron spin-lattice relaxation was measured by the electron spin echo method in a broad temperature range above 4.2 K for Cu(2+) ions and free radicals produced by ionizing radiation in triglycine sulfate (TGS) and Tutton salt (NH4)(2)Zn(SO4)2 ⋅ 6H2O crystals. Localization of the paramagnetic centres in the crystal unit cells was determined from continuous wave electron paramagnetic resonance spectra. Various spin relaxation processes and mechanisms are outlined. Cu(2+) ions relax fast via two-phonon Raman processes in both crystals involving the whole phonon spectrum of the host lattice. This relaxation is slightly slower for TGS where Cu(2+) ions are in the interstitial position. The ordinary Raman processes do not contribute to the radical relaxation which relaxes via the local phonon mode. The local mode lies within the acoustic phonon band for radicals in TGS but within the optical phonon range in (NH4)(2)Zn(SO4)2 ⋅ 6H2O. In the latter the cross-relaxation was considered. A lack of phonons around the radical molecules suggested a local crystal amorphisation produced by x- or γ-rays.

  3. The influence of measurement and relaxation time on flux jumps in high temperature superconductors

    International Nuclear Information System (INIS)

    Yang Xiaobin; Zhou Youhe; Tu Shandong

    2010-01-01

    The influence of the magnetization and relaxation time on flux jumps in high temperature superconductors (HTSC) under varying magnetic field is studied using the fundamental electromagnetic field equations and the thermal diffusion equation; temperature variety corresponding to flux jump is also discussed. We find that for a low sweep rate of the applied magnetic field, the measurement and relaxation times can reduce flux jump and to constrain the number of flux jumps, even stabilizing the HTSC, since much heat produced by the motion of magnetic flux can transfer into coolant during the measurement and relaxation times. As high temperature superconductors are subjected to a high sweep rate or a strong pulsed magnetic field, magnetization undergoes from stability or oscillation to jump for different pause times. And the period of temperature oscillation is equal to the measurement and relaxation time.

  4. Structural relaxation of polydisperse hard spheres: comparison of the mode-coupling theory to a Langevin dynamics simulation.

    Science.gov (United States)

    Weysser, F; Puertas, A M; Fuchs, M; Voigtmann, Th

    2010-07-01

    We analyze the slow glassy structural relaxation as measured through collective and tagged-particle density correlation functions obtained from Brownian dynamics simulations for a polydisperse system of quasi-hard spheres in the framework of the mode-coupling theory (MCT) of the glass transition. Asymptotic analyses show good agreement for the collective dynamics when polydispersity effects are taken into account in a multicomponent calculation, but qualitative disagreement at small q when the system is treated as effectively monodisperse. The origin of the different small-q behavior is attributed to the interplay between interdiffusion processes and structural relaxation. Numerical solutions of the MCT equations are obtained taking properly binned partial static structure factors from the simulations as input. Accounting for a shift in the critical density, the collective density correlation functions are well described by the theory at all densities investigated in the simulations, with quantitative agreement best around the maxima of the static structure factor and worst around its minima. A parameter-free comparison of the tagged-particle dynamics however reveals large quantitative errors for small wave numbers that are connected to the well-known decoupling of self-diffusion from structural relaxation and to dynamical heterogeneities. While deviations from MCT behavior are clearly seen in the tagged-particle quantities for densities close to and on the liquid side of the MCT glass transition, no such deviations are seen in the collective dynamics.

  5. Measurements of spin-lattice relaxation time in mixed alkali halide crystals

    International Nuclear Information System (INIS)

    Tannus, A.

    1983-01-01

    Using magneto-optic techniques the ground state spin-lattice relaxation times (T1) of 'F' centers in mixed Alkali Halide cristals (KCl-KBr), was studied. A computer assisted system to optically measure short relaxation times (approx. = 1mS), was described. The technique is based on the measurement of the Magnetic Circular Dicroism (MCD) presented by F centers. The T1 magnetic field dependency at 2 K (up to 65 KGauss), was obtained as well as the MCD spectra for different relative concentration at the mixed matrices. The theory developed by Panepucci and Mollenauer for F centers spin-lattice relaxation in pure matrices was modified to explain the behaviour of T1 in mixed cristals. The Direct Process results (T approx. = 2.0 K) compared against that theory shows that the main relaxation mecanism, up to 25 KGauss, continues to be phonon modulation of the hiperfine iteraction between F electrons and surrounding nuclei. (Author) [pt

  6. Preference for different relaxation techniques by COPD patients: comparison between six techniques

    Directory of Open Access Journals (Sweden)

    Hyl

    2016-09-01

    Full Text Available Michael E Hyland,1 David MG Halpin,2 Sue Blake,3 Clare Seamark,3 Margaret Pinnuck,3 David Ward,3 Ben Whalley,1 Colin J Greaves,4 Adam L Hawkins,5 Dave Seamark3 1School of Psychology, University of Plymouth, Plymouth, 2Department of Respiratory Medicine, Royal Devon and Exeter Hospital, Exeter, 3Honiton Group Practice, Honiton, 4University of Exeter Medical School, Exeter, 5GSK House, Brentford, UK Background: A review of the effectiveness of relaxation techniques for chronic obstructive pulmonary disease patients has shown inconsistent results, but studies have varied in terms of technique and outcome measures. Aim: To determine patient preference for different relaxation techniques. Methods: Chronic obstructive pulmonary disease patients were presented with six techniques via a DVD and asked to rate the techniques in terms of effectiveness, rank in order of likely use, and comment. Results: Patients differed in the technique preferred and reason for that preference, but the most commonly preferred technique both for effectiveness and ease of use was “thinking of a nice place” followed by progressive relaxation and counting. Familiarity and ease of activity were commonly given reasons for preference. Conclusion: Rather than providing patients with a single technique that they might find difficult to implement, these results suggest that it would be better to give a choice. “Thinking of a nice place” is a popular but under-investigated technique. Keywords: COPD exacerbation, anxiety, relaxation techniques

  7. Novel spin dynamics in ferrimagnetic molecular chains from 1H NMR and μSR spin-lattice relaxation measurements

    International Nuclear Information System (INIS)

    Micotti, E.; Lascialfari, A.; Rigamonti, A.; Aldrovandi, S.; Caneschi, A.; Gatteschi, D.; Bogani, L.

    2004-01-01

    The spin dynamics in the helical chain Co(hfac) 2 NITPhOMe has been investigated by 1 H NMR and μSR relaxation. In the temperature range 15< T<60 K, the results are consistent with the relaxation of the homogeneous magnetization. For T≤15 K, NMR and μSR evidence a second spin relaxation mechanism, undetected by the magnetization measurements. From the analysis of these data, insights on this novel relaxation process are derived

  8. Novel spin dynamics in ferrimagnetic molecular chains from 1H NMR and μSR spin-lattice relaxation measurements

    Science.gov (United States)

    Micotti, E.; Lascialfari, A.; Rigamonti, A.; Aldrovandi, S.; Caneschi, A.; Gatteschi, D.; Bogani, L.

    2004-05-01

    The spin dynamics in the helical chain Co(hfac) 2NITPhOMe has been investigated by 1H NMR and μSR relaxation. In the temperature range 15relaxation of the homogeneous magnetization. For T⩽15 K, NMR and μSR evidence a second spin relaxation mechanism, undetected by the magnetization measurements. From the analysis of these data, insights on this novel relaxation process are derived.

  9. Multidimensional dynamic piezoresponse measurements. Unraveling local relaxation behavior in relaxor-ferroelectrics via big data

    International Nuclear Information System (INIS)

    Vasudevan, Rama K.; Zhang, Shujun; Okatan, Mahmut Baris; Jesse, Stephen; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

    2015-01-01

    Compositional and charge disorder in ferroelectric relaxors lies at the heart of the unusual properties of these systems, such as aging and non-ergodicity, polarization rotations, and a host of temperature and field-driven phase transitions. However, much information about the field-dynamics of the polarization in the prototypical ferroelectric relaxor (1-x)Pb(Mg 1/3 Nb 2/3 )O 3-x PbTiO 3 (PMN-xPT) remains unprobed at the mesoscopic level. We use a piezoresponse force microscopy-based dynamic multimodal relaxation spectroscopy technique, enabling the study of ferroelectric switching and polarization relaxation at mesoscopic length scales, and carry out measurements on a PMN-0.28PT sample with minimal polishing. Results indicate that beyond a threshold DC bias the average relaxation increases as the system attempts to relax to the previous state. Phenomenological fitting reveals the presence of mesoscale heterogeneity in relaxation amplitudes and clearly suggests the presence of two distinct amplitudes. Independent component analysis reveals the presence of a disorder component of the relaxation, which is found to be strongly anti-correlated with the maximum piezoresponse at that location, suggesting smaller disorder effects where the polarization reversal is large and vice versa. The disorder in the relaxation amplitudes is postulated to arise from rhombohedral and field-induced tetragonal phase in the crystal, with each phase associated with its own relaxation amplitude. As a result, these studies highlight the crucial importance of the mixture of ferroelectric phases in the compositions in proximity of the morphotropic phase boundary in governing the local response and further highlight the ability of PFM voltage and time spectroscopies, in conjunction with big-data multivariate analyses, to locally map disorder and correlate it with parameters governing the dynamic behavior

  10. The effects of music relaxation and muscle relaxation techniques on sleep quality and emotional measures among individuals with posttraumatic stress disorder

    Directory of Open Access Journals (Sweden)

    Iris Haimov

    2012-07-01

    Full Text Available Posttraumatic stress disorder (PTSD, an anxiety disorder with lifetime prevalence of 7.8%, is characterized by symptoms that develop following exposure to traumatic life events and that cause an immediate experience of intense fear, helplessness or horror. PTSD is marked by recurrent nightmares typified by the recall of intrusive experiences and by extended disturbance throughout sleep. Individuals with PTSD respond poorly to drug treatments for insomnia. The disadvantages of drug treatment for insomnia underline the importance of non-pharmacological alternatives. Thus, the present study had three aims: first, to compare the efficiency of two relaxation techniques (muscular relaxation and progressive music relaxation in alleviating insomnia among individuals with PTSD using both objective and subjective measures of sleep quality; second, to examine whether these two techniques have different effects on psychological indicators of PTSD, such as depression and anxiety; and finally, to examine how initial PTSD symptom severity and baseline emotional measures are related to the efficiency of these two relaxation methods. Thirteen PTSD patients with no other major psychiatric or neurological disorders participated in the study. The study comprised one seven-day running-in, no-treatment period, followed by two seven-day experimental periods. The treatments constituted either music relaxation or muscle relaxation techniques at desired bedtime. These treatments were randomly assigned. During each of these three experimental periods, subjects’ sleep was continuously monitored with a wrist actigraph (Ambulatory Monitoring, Inc., and subjects were asked to fill out several questionnaires concerned with a wide spectrum of issues, such as sleep, depression, and anxiety. Analyses revealed a significant increase in objective and subjective sleep efficiency and a significant reduction in depression level following music relaxation. Moreover, following music

  11. Improved labeling strategy for 13C relaxation measurements of methyl groups in proteins

    International Nuclear Information System (INIS)

    Lee, Andrew L.; Urbauer, Jeffrey L.; Wand, A. Joshua

    1997-01-01

    Selective incorporation of 13 C into the methyl groups of protein side chains is described as a means for simplifying the measurement and interpretation of 13 C relaxation parameters.High incorporation (>90%) is accomplished by using pyruvate(3- 13 C, 99%) as the sole carbon source in the growth media for protein overexpression in E. coli. This improved labeling scheme increases the sensitivity of the relaxation experiments by approximately fivefold when compared to randomly fractionally 13 C-labeled protein, allowing high-quality measurements on relatively dilute (<1 mM)protein samples at a relatively low cost

  12. Relaxation time measurements of white and grey matter in multiple sclerosis patients

    International Nuclear Information System (INIS)

    Rinck, P.A.; Appel, B.; Moens, E.; Academisch Ziekenhuis Middelheim, Antwerp

    1987-01-01

    In a patient population of some 450 with definite, probable, and possible multiple sclerosis referred to us for MRI, some 40 suffering from definite MS were chosen randomly for relaxation time measurements of plaque-free grey and white matter. T 1 values could not be used for diagnostic purposes owing to their broad standard deviation. Overall white matter T 2 was slightly higher in MS patients than in a non-MS population (94 ms versus 89 ms). Because these changes are not visible in MR images, relaxation time measurements may prove valuable for differential diagnosis. (orig.) [de

  13. MR imaging of the stomach and relaxation measurement with intraluminal hyperpolarized 129Xenon gas

    International Nuclear Information System (INIS)

    Yanagawa, Yasuhiro; Kimura, Atsuomi; Fujiwara, Hideaki; Kinoshita, Yoshimasa; Hattori, Mineyuki; Hiraga, Takashi; Iida, Hidehiro

    2001-01-01

    Using laser optical pumping, the nuclear spin polarization of noble gases can be strongly enhanced. The purpose of this study was to make a simple apparatus that can provide hyperpolarized 129 Xe gas, which can then be used in an attempt to obtain magnetic resonance imaging (MRI). We would also like to study the relaxation behavior of hyperpolarized 129 Xe gas through the measurement of the relaxation time. First, we demonstrated that hyperpolarized 129 Xe gas can be applied to magnetic resonance imaging of the stomach, by using a rat as a model. This was performed under a 4.7 T magnet field using the following imaging parameters for the hyperpolarized 129 Xe gas: TR=50 ms, TE=15 ms, FOV=10 x 10 cm 2 , matrix size 64 x 64, THK=2.54 cm. By using these parameters, we were able to obtain a hyperpolarized image of the stomach in rats for the first time. Next, we measured the relaxation times of the hyperpolarized 129 Xe gas enclosed in cavities such as the stomach of rats as well as in phantoms created by glass and gelatin bulbs. The cavity size dependency of the relaxation time was analyzed on the basis of the kinetic theory of gases. This analysis showed a linear relationship between the relaxation rate (1/T 1 ) and a square inverse of the cavity diameter (1/d 2 ). From this relationship, the wall effect on the 129 Xe relaxation can be estimated in the novel parameter t 1 , wall . This shows drastic dependency on the material of the wall, suggesting a potential use of the relaxation experiment as a diagnostic tool for organ surfaces in the future. (author)

  14. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)

    International Nuclear Information System (INIS)

    Kretzschmar, M.; Hainc, N.; Studler, U.; Bieri, O.; Miska, M.; Wiewiorski, M.; Valderrabano, V.

    2015-01-01

    The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm 2 /ms) was significantly higher compared to normal cartilage (1.46 μm 2 /ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. (orig.)

  15. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, M.; Hainc, N.; Studler, U. [University Hospital Basel, Department of Radiology, Basel (Switzerland); Bieri, O. [University Hospital Basel, Division of Radiological Physics, Basel (Switzerland); Miska, M. [University Hospital, Department of Orthopedics, Heidelberg (Germany); Wiewiorski, M.; Valderrabano, V. [University Hospital Basel, Department of Orthopedic Surgery, Basel (Switzerland)

    2015-04-01

    The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm{sup 2}/ms) was significantly higher compared to normal cartilage (1.46 μm{sup 2}/ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. (orig.)

  16. On-chip Brownian relaxation measurements of magnetic nanobeads in the time domain

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2013-01-01

    the time and frequency domain methods on Brownian relaxation detection of clustering of streptavidin coated magnetic beads in the presence of different concentrations of biotin-conjugated bovine serum albumin and obtain comparable results. In the time domain, a measurement is carried out in less than 30 s...

  17. Carboxylated magnetic nanoparticles as MRI contrast agents: Relaxation measurements at different field strengths

    Energy Technology Data Exchange (ETDEWEB)

    Jedlovszky-Hajdu, Angela, E-mail: angela.hajdu@net.sote.hu [Laboratory of Nanochemistry, Department of Biophysics and Radiation Biology, Semmelweis University, Nagyvarad Sq 4, H-1089 Budapest (Hungary); Tombacz, Etelka, E-mail: tombacz@chem.u-szeged.hu [Department of Physical Chemistry and Material Science, University of Szeged, Aradi Vt. Sq 1, Szeged 6720 (Hungary); Banyai, Istvan, E-mail: banyai.istvan@science.unideb.hu [Department of Colloid and Environmental Chemistry, University of Debrecen (Hungary); Babos, Magor, E-mail: babosmagor@yahoo.com [Euromedic Diagnostics Szeged Ltd., Semmelweis St 6, Szeged 6720 (Hungary); Palko, Andras, E-mail: palko@radio.szote.u-szeged.hu [Faculty of Medicine, Department of Radiology, University of Szeged (Hungary)

    2012-09-15

    At the moment the biomedical applications of magnetic fluids are the subject of intensive scientific interest. In the present work, magnetite nanoparticles (MNPs) were synthesized and stabilized in aqueous medium with different carboxylic compounds (citric acid (CA), polyacrylic acid (PAA), and sodium oleate (NaOA)), in order to prepare well stabilized magnetic fluids (MFs). The magnetic nanoparticles can be used in the magnetic resonance imaging (MRI) as contrast agents. Magnetic resonance relaxation measurements of the above MFs were performed at different field strengths (i.e., 0.47, 1.5 and 9.4 T) to reveal the field strength dependence of their magnetic responses, and to compare them with that of ferucarbotran, a well-known superparamagnetic contrast agent. The measurements showed characteristic differences between the tested magnetic fluids stabilized by carboxylic compounds and ferucarbotran. It is worthy of note that our magnetic fluids have the highest r2 relaxivities at the field strength of 1.5 T, where the most of the MRI works in worldwide. - Highlights: Black-Right-Pointing-Pointer Magnetic resonance relaxation measurements were done at different field strengths. Black-Right-Pointing-Pointer Results show characteristic differences between the tested carboxylated MFs. Black-Right-Pointing-Pointer r1 and r2 relaxivities depend on the thickness of the protecting layer. Black-Right-Pointing-Pointer MFs have high r2/r1 ratios at each magnetic field.

  18. Musculoskeletal MRI at 3.0 T and 7.0 T: a comparison of relaxation times and image contrast.

    Science.gov (United States)

    Jordan, Caroline D; Saranathan, Manojkumar; Bangerter, Neal K; Hargreaves, Brian A; Gold, Garry E

    2013-05-01

    The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T. We measured the T₁ and T₂ relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T₁ relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T₂ relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T₁ and T₂ measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency. The T₁ relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T₂ relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T₂-weighted FSE, and 3D-FSE-Cube. The T₁ and T₂ changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  19. Musculoskeletal MRI at 3.0 T and 7.0 T: A comparison of relaxation times and image contrast

    International Nuclear Information System (INIS)

    Jordan, Caroline D.; Saranathan, Manojkumar; Bangerter, Neal K.; Hargreaves, Brian A.; Gold, Garry E.

    2013-01-01

    Objective: The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T. Materials and methods: We measured the T 1 and T 2 relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T 1 relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T 2 relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T 1 and T 2 measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency. Results: The T 1 relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T 2 relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T 2 -weighted FSE, and 3D-FSE-Cube. Conclusion: The T 1 and T 2 changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols

  20. Measurement of short transverse relaxation times by pseudo-echo nutation experiments

    Science.gov (United States)

    Ferrari, Maude; Moyne, Christian; Canet, Daniel

    2018-07-01

    Very short NMR transverse relaxation times may be difficult to measure by conventional methods. Nutation experiments constitute an alternative approach. Nutation is, in the rotating frame, the equivalent of precession in the laboratory frame. It consists in monitoring the rotation of magnetization around the radio-frequency (rf) field when on-resonance conditions are fulfilled. Depending on the amplitude of the rf field, nutation may be sensitive to the two relaxation rates R1 and R2. A full theoretical development has been worked out for demonstrating how these two relaxation rates could be deduced from a simple nutation experiment, noticing however that inhomogeneity of the rf field may lead to erroneous results. This has led us to devise new experiments which are the equivalent of echo techniques in the rotating frame (pseudo spin-echo nutation experiment and pseudo gradient-echo experiment). Full equations of motion have been derived. Although complicated, they indicate that the sum of the two relaxation rates can be obtained very accurately and not altered by rf field inhomogeneity. This implies however an appropriate data processing accounting for the oscillations which are superposed to the echo decays and, anyway, theoretically predicted. A series of experiments has been carried out for different values of the rf field amplitude on samples of water doped with a paramagnetic compound at different concentrations. Pragmatically, as R1 can be easily measured by conventional methods, its value is entered in the data processing algorithm which then returns exclusively the value of the transverse relaxation time. Very consistent results are obtained that way.

  1. State of health assessment for lithium batteries based on voltage–time relaxation measure

    International Nuclear Information System (INIS)

    Baghdadi, Issam; Briat, Olivier; Gyan, Philippe; Vinassa, Jean Michel

    2016-01-01

    Highlights: • Calendar aging under different storage conditions for three different battery technologies studied. • Two scenarios of aging under power cycling at two different temperatures investigated for one battery technology. • Relaxation profile of battery voltage just after full charge is highly correlated to aging. • Linear dependence between just after charge open circuit voltage and remaining capacity demonstrated. • No computational method and direct prediction of battery state of health or remaining capacity. - Abstract: The performance of lithium batteries degrades over time. The degradation rate strongly depends on stress conditions during use and even at rest. Thus, accurate and rapid diagnosis of battery state of health (SOH) is necessary for electric vehicle manufacturers to manage their vehicle fleets and warranties. This paper demonstrates a simple method for assessing SOH related to battery energy capability (SOH E ). The presented method is based on the monitoring of U relax over aging. U relax is the open-circuit voltage of the battery measured after full charging and 30 min of rest. A linear dependence between U relax and remaining capacity is noted. This correlation is demonstrated for three different commercial battery technologies (different chemistries) aged under different calendar and power cycling aging conditions. It was determined that the difference between two U relax voltages measured at two different aging states is proportional to SOH E decay. The mean error of the linear model is less than 2% for certain cases. This method could also be a highly useful and rapid tool for a complete battery pack diagnosis.

  2. Transverse magnetic field effects on the relaxation time of the magnetization in Mn12 measured by 55Mn-NMR

    International Nuclear Information System (INIS)

    Furukawa, Y.; Watanabe, K.; Kumagai, K.; Borsa, F.; Gatteschi, D.

    2003-01-01

    The longitudinal (H Z ) and transverse (H T ) magnetic field dependence of the relaxation time of the magnetization in Mn12 in its S=10 ground state was measured by NMR. The minima in the relaxation time at the fields for level crossing are due to the quantum tunneling of the magnetization. The shortening of the relaxation time under the application of H T is shown to be due mainly to the reduction of the energy barrier

  3. Treating children traumatized by war and Tsunami: A comparison between exposure therapy and meditation-relaxation in North-East Sri Lanka

    Directory of Open Access Journals (Sweden)

    Ruf Martina

    2009-05-01

    Full Text Available Abstract Background The North-Eastern part of Sri Lanka had already been affected by civil war when the 2004 Tsunami wave hit the region, leading to high rates of posttraumatic stress disorder (PTSD in children. In the acute aftermath of the Tsunami we tested the efficacy of two pragmatic short-term interventions when applied by trained local counselors. Methods A randomized treatment comparison was implemented in a refugee camp in a severely affected community. 31 children who presented with a preliminary diagnosis of PTSD were randomly assigned either to six sessions Narrative Exposure Therapy for children (KIDNET or six sessions of meditation-relaxation (MED-RELAX. Outcome measures included severity of PTSD symptoms, level of functioning and physical health. Results In both treatment conditions, PTSD symptoms and impairment in functioning were significantly reduced at one month post-test and remained stable over time. At 6 months follow-up, recovery rates were 81% for the children in the KIDNET group and 71% for those in the MED-RELAX group. There was no significant difference between the two therapy groups in any outcome measure. Conclusion As recovery rates in the treatment groups exceeded the expected rates of natural recovery, the study provides preliminary evidence for the effectiveness of NET as well as meditation-relaxation techniques when carried out by trained local counselors for the treatment of PTSD in children in the direct aftermath of mass disasters. Trial registration ClinicalTrials.gov Identifier:NCT00820391

  4. Evaluation of relaxation time measurements by magnetic resonance imaging. A phantom study

    DEFF Research Database (Denmark)

    Kjaer, L; Thomsen, C; Henriksen, O

    1987-01-01

    Several circumstances may explain the great variation in reported proton T1 and T2 relaxation times usually seen. This study was designed to evaluate the accuracy of relaxation time measurements by magnetic resonance imaging (MRI) operating at 1.5 tesla. Using a phantom of nine boxes with different...... concentrations of CuSO4 and correlating the calculated T1 and T2 values with reference values obtained by two spectrometers (corrected to MRI-proton frequency = 64 MHz) we found a maximum deviation of about 10 per cent. Measurements performed on a large water phantom in order to evaluate the homogeneity...... in the imaging plane showed a variation of less than 10 per cent within 10 cm from the centre of the magnet in all three imaging planes. Changing the gradient field strength apparently had no influence on the T2 values recorded. Consequently diffusion processes seem without significance. It is concluded...

  5. Transport relaxation measurements and glassy state effects in superconducting MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Olutas, M. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)], E-mail: olutas_m@ibu.edu.tr; Yetis, H.; Altinkok, A.; Kilic, A.; Kilic, K. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)

    2008-09-15

    Time dependent effects in superconducting MgB{sub 2} have been studied systematically for the first time by transport relaxation measurements (V-t curves) as a function of transport current (I), temperature (T) and external magnetic field (H). At very low dissipation levels (below {approx}1 {mu}V), it was observed that the sample voltage grows up smoothly in time by exhibiting the details of initial stage of relaxation process. At high dissipation levels, steady state corresponding to constant flow rate is maintained within a very short time and monitoring of details of flux dynamic evolving along sample becomes difficult on long time scales. Another interesting behavior is the appearance of voltage peak when the transport current was reduced to a finite value. After peak, it was observed that the sample voltage relaxes smoothly by leveling off within a very short time. The evolution of V-t curves suggests that formation of resistive flow channels along sample develops easily, which is quite similar to that of obtained for the superconducting ceramic samples whose grain boundaries are improved. Time dependent effects were also observed in magnetovoltage measurements (V-H curves) as the field sweep rate (dH/dt) varies. The observations were interpreted mainly in terms of flux trapping in grains.

  6. Transport relaxation measurements and glassy state effects in superconducting MgB2

    International Nuclear Information System (INIS)

    Olutas, M.; Yetis, H.; Altinkok, A.; Kilic, A.; Kilic, K.

    2008-01-01

    Time dependent effects in superconducting MgB 2 have been studied systematically for the first time by transport relaxation measurements (V-t curves) as a function of transport current (I), temperature (T) and external magnetic field (H). At very low dissipation levels (below ∼1 μV), it was observed that the sample voltage grows up smoothly in time by exhibiting the details of initial stage of relaxation process. At high dissipation levels, steady state corresponding to constant flow rate is maintained within a very short time and monitoring of details of flux dynamic evolving along sample becomes difficult on long time scales. Another interesting behavior is the appearance of voltage peak when the transport current was reduced to a finite value. After peak, it was observed that the sample voltage relaxes smoothly by leveling off within a very short time. The evolution of V-t curves suggests that formation of resistive flow channels along sample develops easily, which is quite similar to that of obtained for the superconducting ceramic samples whose grain boundaries are improved. Time dependent effects were also observed in magnetovoltage measurements (V-H curves) as the field sweep rate (dH/dt) varies. The observations were interpreted mainly in terms of flux trapping in grains

  7. Comparison of Hypnotherapy with Systematic Relaxation in the Treatment of Cigarette Habituation.

    Science.gov (United States)

    Schubert, Donald K.

    1983-01-01

    Studied the effectiveness of hypnosis in the treatment of cigarette habituation. Volunteers (N=87) were randomly assigned to hypnosis, relaxation, or waiting list control groups. Hypnosis was found to be superior to relaxation only for subjects high in hypnotic susceptibility. Those who quit smoking increased food consumption. (Author/JAC)

  8. Microwave Amplitude Modulation Technique to Measure Spin-Lattice (T 1) and Spin-Spin (T 2) Relaxation Times

    Science.gov (United States)

    Misra, Sushil K.

    The measurement of very short spin-lattice, or longitudinal, relaxation (SLR) times (i.e., 10-10 Misra, 1998), and polymer resins doped with rare-earth ions (Pescia et al., 1999a; Pescia et al. 1999b). The ability to measure such fast SLR data on amorphous Si and copper-chromium-tin spinel led to an understanding of the role of exchange interaction in affecting spin-lattice relaxation, while the data on polymer resins doped with rare-earth ions provided evidence of spin-fracton relaxation (Pescia et al., 1999a, b). But such fast SLR times are not measurable by the most commonly used techniques of saturation- and inversion-recovery (Poole, 1982; Alger, 1968), which only measure spin-lattice relaxation times longer than 10-6 s. A summary of relevant experimental data is presented in Table 1.

  9. Towards quantitative measurements of relaxation times and other parameters in the brain

    International Nuclear Information System (INIS)

    Tofts, P.S.; Du Boulay, E.P.G.H.

    1990-01-01

    The nature and physical significance of the relaxation times T1 and T2 and of proton density are described. Methods of measuring T1 and T2 are discussed with emphasis on the establishment of precision and the maintenance of accuracy. Reported standards of success are briefly reviewed. We expect sensitivities of the order of 1% to be achievable in serial studies. Although early hopes of disease diagnosis by tissue characterisation were not realised, strict scientific method and careful calibration have made it pracitcable to apply relaxation time measurement to research into disease process. Serial measurements in patients and correlation with similar studies in animal models, biopsy results and autopsy material taken together have provided new knowledge about cerebral oedema, water compartmentation, alcoholism and the natural history of multiple sclerosis. There are prospects of using measurement to monitor treatment in other diseases with diffuse brain abnormalities invisible on the usual images. Secondarily derived parameters and notably the quantification of blood-brain barrier defect after injection of Gadolinium-DTPA also offer prospects of valuable data. (orig.)

  10. On-chip measurements of Brownian relaxation vs. concentration of 40nm magnetic beads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2012-01-01

    We present on-chip Brownian relaxation measurements on a logarithmic dilution series of 40 nm beads dispersed in water with bead concentrations between 16 mu g/ml and 4000 mu g/ml. The measurements are performed using a planar Hall effect bridge sensor at frequencies up to 1 MHz. No external fields...... are needed as the beads are magnetized by the field generated by the applied sensor bias current. We show that the Brownian relaxation frequency can be extracted from fitting the Cole-Cole model to measurements for bead concentrations of 64 mu g/ml or higher and that the measured dynamic magnetic response...... is proportional to the bead concentration. For bead concentrations higher than or equal to 500 mu g/ml, we extract a hydrodynamic diameter of 47(1) nm for the beads, which is close to the nominal bead size of 40 nm. Furthermore, we study the signal vs. bead concentration at a fixed frequency close to the Brownian...

  11. Fast hydrogen exchange affects 15N relaxation measurements in intrinsically disordered proteins

    International Nuclear Information System (INIS)

    Kim, Seho; Wu, Kuen-Phon; Baum, Jean

    2013-01-01

    Unprotected amide protons can undergo fast hydrogen exchange (HX) with protons from the solvent. Generally, NMR experiments using the out-and-back coherence transfer with amide proton detection are affected by fast HX and result in reduced signal intensity. When one of these experiments, 1 H– 15 N HSQC, is used to measure the 15 N transverse relaxation rate (R 2 ), the measured R 2 rate is convoluted with the HX rate (k HX ) and has higher apparent R 2 values. Since the 15 N R 2 measurement is important for analyzing protein backbone dynamics, the HX effect on the R 2 measurement is investigated and described here by multi-exponential signal decay. We demonstrate these effects by performing 15 N R 2 CPMG experiments on α-synuclein, an intrinsically disordered protein, in which the amide protons are exposed to solvent. We show that the HX effect on R 2 CPMG can be extracted by the derived equation. In conclusion, the HX effect may be pulse sequence specific and results from various sources including the J coupling evolution, the change of steady state water proton magnetization, and the D 2 O content in the sample. To avoid the HX effect on the analysis of relaxation data of unprotected amides, it is suggested that NMR experimental conditions insensitive to the HX should be considered or that intrinsic R 2 CPMG values be obtained by methods described herein.

  12. Vibrational relaxation in liquids: Comparisons between gas phase and liquid phase theories

    International Nuclear Information System (INIS)

    Russell, D.J.

    1990-12-01

    The vibrational relaxation of iodine in liquid xenon was studied to understand what processes are important in determining the density dependence of the vibrational relaxation. This examination will be accomplished by taking simple models and comparing the results to both experimental outcomes and the predictions of molecular dynamics simulations. The vibration relaxation of iodine is extremely sensitive to the iodine potential. The anharmonicity of iodine causes vibrational relaxation to be much faster at the top of the iodine well compared to the vibrational relaxation at the bottom. A number of models are used in order to test the ability of the Isolated Binary Collision theory's ability to predict the density dependence of the vibrational relaxation of iodine in liquid xenon. The models tested vary from the simplest incorporating only the fact that the solvent occupies volume to models that incorporate the short range structure of the liquid in the radial distribution function. None of the models tested do a good job of predicting the actual relaxation rate for a given density. This may be due to a possible error in the choice of potentials to model the system

  13. Fast-electron-relaxation measurement for laser-solid interaction at relativistic laser intensities

    International Nuclear Information System (INIS)

    Chen, H.; Shepherd, R.; Chung, H. K.; Kemp, A.; Hansen, S. B.; Wilks, S. C.; Ping, Y.; Widmann, K.; Fournier, K. B.; Beiersdorfer, P.; Dyer, G.; Faenov, A.; Pikuz, T.

    2007-01-01

    We present measurements of the fast-electron-relaxation time in short-pulse (0.5 ps) laser-solid interactions for laser intensities of 10 17 , 10 18 , and 10 19 W/cm 2 , using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. We find that the laser coupling to hot electrons increases as the laser intensity becomes relativistic, and that the thermalization of fast electrons occurs over time scales on the order of 10 ps at all laser intensities. The experimental data are analyzed using a combination of models that include Kα generation, collisional coupling, and plasma expansion

  14. Analysis of the backbone dynamics of capsicein using 15N NMR relaxation rate measurements

    International Nuclear Information System (INIS)

    Van Heijenoort, C.; Bouaziz, S.; Guittet, E.

    1994-01-01

    15 N relaxation times T 1 and T 1ρ , and heteronuclear steady state nOes, were measured on capsicein, a 98 residue protein. The classical analysis of these data using directly the Lipari and Szabo formalism was shown to give incoherent results, probably due to the presence of a slow exchange along the whole protein. This global exchange broadening made the usual preliminary evaluation of the overall correlation time of capsicein using the Lipari and Szabo expression for the spectral densities impossible. (authors). 2 figs., 23 refs

  15. COMPARISON BETWEEN POST ISOMETRIC RELAXATION AND RECIPROCAL INHIBITION MANUEVERS ON HAMSTRING FLEXIBILITY IN YOUNG HEALTHY ADULTS: RANDOMIZED CLINICAL TRIAL

    Directory of Open Access Journals (Sweden)

    Agrawal Sonal S

    2016-01-01

    Full Text Available Background & Purpose: Variations in the application of muscle energy technique (MET for increasing the extensibility of muscles have been advocated, but little evidence exists to support the relative merit of a particular approach. This study investigated two types of muscle energy techniques that have been advocated in the osteopathic literature that differ primarily in the muscle group targeted. Aim: To compare the efficacy of Post Isometric Relaxation (PIR and Reciprocal Inhibition (RI on hamstring length in young healthy adults Methodology: Randomized clinical trial 100 college students aged between 18-25 years were included. The subjects were randomly assigned to PIR and RI group. Each group consisted of 50 subjects (25 male, 25 female. Knee extension limitation was measured by using active knee extension test (AKET pre & post-intervention, i.e. after 3 weeks of stretching regimen, with the help of universal full circle goniometer. Results: There was significant improvement in hamstrings flexibility (p=0.000 in both PIR and RI groups. Statistical comparison of the results of both the technique showed that PIR group had greater improvement than the RI group (p=0.000 Conclusion: PIR and RI were both found to be effective in improving hamstring flexibility but, PIR is more effective therapeutic maneuver.

  16. The effects of some parameters on the calculated 1H NMR relaxation times of cell water

    International Nuclear Information System (INIS)

    Koivula, A.; Suominen, K.; Kiviniitty, K.

    1976-01-01

    The effect of some parameters on the longitudinal and transverse relaxation times is calculated and a comparison between the calculated relaxation times with the results of different measurements is made. (M.S.)

  17. Measuring 13Cβ chemical shifts of invisible excited states in proteins by relaxation dispersion NMR spectroscopy

    International Nuclear Information System (INIS)

    Lundstroem, Patrik; Lin Hong; Kay, Lewis E.

    2009-01-01

    A labeling scheme is introduced that facilitates the measurement of accurate 13 C β chemical shifts of invisible, excited states of proteins by relaxation dispersion NMR spectroscopy. The approach makes use of protein over-expression in a strain of E. coli in which the TCA cycle enzyme succinate dehydrogenase is knocked out, leading to the production of samples with high levels of 13 C enrichment (30-40%) at C β side-chain carbon positions for 15 of the amino acids with little 13 C label at positions one bond removed (∼5%). A pair of samples are produced using [1- 13 C]-glucose/NaH 12 CO 3 or [2- 13 C]-glucose as carbon sources with isolated and enriched (>30%) 13 C β positions for 11 and 4 residues, respectively. The efficacy of the labeling procedure is established by NMR spectroscopy. The utility of such samples for measurement of 13 C β chemical shifts of invisible, excited states in exchange with visible, ground conformations is confirmed by relaxation dispersion studies of a protein-ligand binding exchange reaction in which the extracted chemical shift differences from dispersion profiles compare favorably with those obtained directly from measurements on ligand free and fully bound protein samples

  18. In vivo measurements of relaxation process in the human liver by MRI. The role of respiratory gating/triggering

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1988-01-01

    In vivo estimation of relaxation processes in the liver by magnetic resonance imaging (MRI) may be helpful for characterization of various pathological conditions in the liver. However, such measurements may be significantly hampered by movement of the liver with the respiration. The effect...... of synchronization of data acquisition to the respiratory cycle on measured T1- and T2-relaxation curves was studied in normal subjects, patients with diffuse liver disease, and patients with focal liver pathology. Multi spin echo sequences with five different repetition times were used. The measurements were...... carried out with and without respiratory gating/triggering. In the healthy subjects as well as in the patients with diffuse liver diseases respiratory synchronization did not alter the obtained relaxation curves. However, in the patients with focal pathology the relaxation curves were significantly...

  19. Inducing Assertive Behavior in Chronic Schizophrenics: A Comparison of Socioenvironmental Desensitization, and Relaxation Therapies

    Science.gov (United States)

    Weinman, Bernard; And Others

    1972-01-01

    It is concluded that systematic desensitization or relaxation therapy is not effective in inducing assertive behavior in the male chronic schizophrenic. The treatment of choice for the older chronic male schizophrenic remains socioenvironmental therapy. (Author)

  20. Relaxation model for extended magnetohydrodynamics: Comparison to magnetohydrodynamics for dense Z-pinches

    International Nuclear Information System (INIS)

    Seyler, C. E.; Martin, M. R.

    2011-01-01

    It is shown that the two-fluid model under a generalized Ohm's law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm's law determines the current density to a system where Ohm's law determines the electric field. This result is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.

  1. In vivo measurements of the T1 relaxation processes in the bone marrow in patients with myelodysplastic syndrome

    International Nuclear Information System (INIS)

    Jensen, K.E.; Nielsen, H.; Thomsen, C.; Soerensen, P.G.; Karle, H.; Christoffersen, P.; Henriksen, O.; Hvidovre Hospital, Copenhagen; Hvidovre Hospital, Copenhagen

    1989-01-01

    Nine patients with myelodysplastic syndrome (MDS) were examined with magnetic resonance imaging and in vivo T1 relaxation time measurements of the vertebral bone marrow in a 1.5 tesla whole body scanner. Two patients underwent transformation to acute myeloid leukemia and were evaluated at follow-up examinations. At the time of diagnosis the T1 relaxation times of the vertebral bone marrow were significantly prolonged compared with normal values. The T1 relaxation times of the vertebral bone marrow in patients with MDS showed significantly lower values compared with patients with acute leukemia and did not differ from patients with polycythemia vera. (orig.)

  2. Instrumentation problems in the measurement of relaxation time T1 in MRI

    International Nuclear Information System (INIS)

    Leroy-Willig, A.; Roucayrol, J.C.; Bittoun, J.; Courtieu, J.

    1986-01-01

    Longitudinal relaxation (T 1 ) of protons is a sensitive though non specific tool of tissue characterization. T 1 measurement from magnetic resonance images is unprecise, due to several phenomena that we review: time intervals shorter than in spectroscopic sequences; flip angle inhomogeneity; slice selection and spin echoes. In vivo the molecular inhomogeneity can prevent to measure a true T 1 ; motion and blood flow are important causes of errors. The relative effects of these factors are examined from in vitro and in vivo images acquired at 1.5 T. From a mono-echo single-slice saturation sequence reliable values of T 1 are obtained in vitro, the measurement time being compatible with clinical imaging. In vivo, problems due to various causes of motions are still unresolved [fr

  3. The feasibility of parameterizing four-state equilibria using relaxation dispersion measurements

    International Nuclear Information System (INIS)

    Li Pilong; Martins, Ilídio R. S.; Rosen, Michael K.

    2011-01-01

    Coupled equilibria play important roles in controlling information flow in biochemical systems, including allosteric molecules and multidomain proteins. In the simplest case, two equilibria are coupled to produce four interconverting states. In this study, we assessed the feasibility of determining the degree of coupling between two equilibria in a four-state system via relaxation dispersion measurements. A major bottleneck in this effort is the lack of efficient approaches to data analysis. To this end, we designed a strategy to efficiently evaluate the smoothness of the target function surface (TFS). Using this approach, we found that the TFS is very rough when fitting benchmark CPMG data to all adjustable variables of the four-state equilibria. After constraining a portion of the adjustable variables, which can often be achieved through independent biochemical manipulation of the system, the smoothness of TFS improves dramatically, although it is still insufficient to pinpoint the solution. The four-state equilibria can be finally solved with further incorporation of independent chemical shift information that is readily available. We also used Monte Carlo simulations to evaluate how well each adjustable parameter can be determined in a large kinetic and thermodynamic parameter space and how much improvement can be achieved in defining the parameters through additional measurements. The results show that in favorable conditions the combination of relaxation dispersion and biochemical manipulation allow the four-state equilibrium to be parameterized, and thus coupling strength between two processes to be determined.

  4. Dielectric Relaxation of Water: Theory and Experiment

    International Nuclear Information System (INIS)

    Adhikari, Narayan Prasad; Paudyal, Harihar; Johri, Manoj

    2010-06-01

    We have studied the hydrogen bond dynamics and methods for evaluation of probability and relaxation time for hydrogen bond network. Further, dielectric relaxation time has been calculated by using a diagonalization procedure by obtaining eigen values (inverse of relaxation time) of a master equation framed on the basis of Fokker-Planck equations. Microwave cavity spectrometer has been described to make measurements of relaxation time. Slater's perturbation equations are given for the analysis of the data. A comparison of theoretical and experimental data shows that there is a need for improvements in the theoretical model and experimental techniques to provide exact information about structural properties of water. (author)

  5. Measurement of N and C diffusion in Sm2Fe17 by magnetic relaxation

    International Nuclear Information System (INIS)

    Mommer, N.; Hirscher, M.; Gerlach, M.; Van Lier, J.; Kronmueller, H.; Kubis, M.; Mueller, K.-H.

    1998-01-01

    Magnetic after-effect (MAE) measurements of nitrided and carburized Sm 2 Fe 17 compounds were performed in the temperature range of 140 K to 480 K. Both nitrided and carburized compounds show relaxation maxima at 285 and 300 K, respectively, which are absent in pure Sm 2 Fe 17 compounds. Therefore, these relaxation maxima are attributed to jumps of interstitially dissolved nitrogen or carbon atoms. Numerical evaluation yielded an activation enthalpy Q N (0.84±0.05) eV and a pre-exponential factor τ 0 N =3.10 -15±1 s for the short-range diffusion of N atoms. The corresponding values for the carbon diffusion are Q C =(0.91±0.05) eV and τ 0 C =1.10 -15±1 s. The carbon and nitrogen content of the samples was determined from the increase in mass during nitrogenation or carburization to Sm 2 Fe 17 N 1.2 and Sm 2 Fe 17 C 2.6 . (orig.)

  6. Fast hydrogen exchange affects {sup 15}N relaxation measurements in intrinsically disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seho; Wu, Kuen-Phon; Baum, Jean, E-mail: jean.baum@rutgers.edu [Rutgers University, Department of Chemistry and Chemical Biology (United States)

    2013-03-15

    Unprotected amide protons can undergo fast hydrogen exchange (HX) with protons from the solvent. Generally, NMR experiments using the out-and-back coherence transfer with amide proton detection are affected by fast HX and result in reduced signal intensity. When one of these experiments, {sup 1}H-{sup 15}N HSQC, is used to measure the {sup 15}N transverse relaxation rate (R{sub 2}), the measured R{sub 2} rate is convoluted with the HX rate (k{sub HX}) and has higher apparent R{sub 2} values. Since the {sup 15}N R{sub 2} measurement is important for analyzing protein backbone dynamics, the HX effect on the R{sub 2} measurement is investigated and described here by multi-exponential signal decay. We demonstrate these effects by performing {sup 15}N R{sub 2}{sup CPMG} experiments on {alpha}-synuclein, an intrinsically disordered protein, in which the amide protons are exposed to solvent. We show that the HX effect on R{sub 2}{sup CPMG} can be extracted by the derived equation. In conclusion, the HX effect may be pulse sequence specific and results from various sources including the J coupling evolution, the change of steady state water proton magnetization, and the D{sub 2}O content in the sample. To avoid the HX effect on the analysis of relaxation data of unprotected amides, it is suggested that NMR experimental conditions insensitive to the HX should be considered or that intrinsic R{sub 2}{sup CPMG} values be obtained by methods described herein.

  7. Residual stress relaxation measurements across interfaces at macro-and micro-scales using slitting and DIC

    Energy Technology Data Exchange (ETDEWEB)

    Blair, A; Daynes, N; Hamilton, D; Horne, G; Hodgson, D Z L; Shterenlikht, A [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Heard, P J; Scott, T B, E-mail: mexas@bristol.ac.u [Interface Analysis Centre, University of Bristol, Bristol BS2 8BS (United Kingdom)

    2009-08-01

    In this paper digital image correlation is used to measure relaxation of residual stresses across an interface. On the macro scale the method is applied to a tri-layer bonded aluminium sample, where the middle layer is in tension and the top and the bottom layers are in compression. High contrast speckle pattern was sprayed onto the surface. The relaxation was done with the slitting saw. Three dimensional image correlation was used. On the micro scale the technique was applied to a heat treated large grain brass loaded in tension. Mechanical and electro polishing was used for surface preparation. A focused ion beam was used for slitting across a grain boundary and for imaging. Grain orientation was measured using electron back-scattering diffraction. Two dimensional image correlation was employed. In all macro- and micro-scale experiments the range of measured relaxation was sub-pixel, almost at the limit of the resolution of the image correlation algorithms. In the macro-scale experiments, the limiting factor was low residual stress, due to low shear strength of the Araldite glue used for bonding. Finite element simulation of the relaxation agreed only qualitatively with the experimental results at both size scales. The methodology is intended for use with inverse methods, i.e. the measured relaxation is applied as the boundary conditions to an appropriate FE model which produces stresses equal to the relaxed residual stresses, but with opposite sign. The main conclusion is that the digital image correlation method could be used to measure relaxation caused by slitting in heterogeneous materials and structures at both macro- and micro-scales. However, the repeatability of the techniques needs to be improved before residual stresses can be determined confidently. Acknowledgments The authors gratefully acknowledge Airbus UK for provision of materials. They thank Dr Richard Burguete, Airbus UK, and Prof Peter Flewitt, Department of Physics, University of Bristol, for

  8. Residual stress relaxation measurements across interfaces at macro-and micro-scales using slitting and DIC

    International Nuclear Information System (INIS)

    Blair, A; Daynes, N; Hamilton, D; Horne, G; Hodgson, D Z L; Shterenlikht, A; Heard, P J; Scott, T B

    2009-01-01

    In this paper digital image correlation is used to measure relaxation of residual stresses across an interface. On the macro scale the method is applied to a tri-layer bonded aluminium sample, where the middle layer is in tension and the top and the bottom layers are in compression. High contrast speckle pattern was sprayed onto the surface. The relaxation was done with the slitting saw. Three dimensional image correlation was used. On the micro scale the technique was applied to a heat treated large grain brass loaded in tension. Mechanical and electro polishing was used for surface preparation. A focused ion beam was used for slitting across a grain boundary and for imaging. Grain orientation was measured using electron back-scattering diffraction. Two dimensional image correlation was employed. In all macro- and micro-scale experiments the range of measured relaxation was sub-pixel, almost at the limit of the resolution of the image correlation algorithms. In the macro-scale experiments, the limiting factor was low residual stress, due to low shear strength of the Araldite glue used for bonding. Finite element simulation of the relaxation agreed only qualitatively with the experimental results at both size scales. The methodology is intended for use with inverse methods, i.e. the measured relaxation is applied as the boundary conditions to an appropriate FE model which produces stresses equal to the relaxed residual stresses, but with opposite sign. The main conclusion is that the digital image correlation method could be used to measure relaxation caused by slitting in heterogeneous materials and structures at both macro- and micro-scales. However, the repeatability of the techniques needs to be improved before residual stresses can be determined confidently. Acknowledgments The authors gratefully acknowledge Airbus UK for provision of materials. They thank Dr Richard Burguete, Airbus UK, and Prof Peter Flewitt, Department of Physics, University of Bristol, for

  9. Comparison of relaxation with counterpressure massage techniques for reduce pain first stage of labor

    Science.gov (United States)

    Lisa, U. F.; Jalina, M.; Marniati

    2017-09-01

    Based on interviews of so me mother who entered the first stage of labor lack of care from health workers to the effort to reducing the acuteof labor. Health care workers appertain hospital in effective in implement maternity nursing interventions in reducing acute the first stage of labor. The reducing acute have two method are pharmacological and non-pharmacological. In this case, has several techniques there are: relaxation and counterpressure massage techniques that capable to reducing acute first stage of labor. The of non-pharmacological is one of authority which must be implemented by midwives especially breathing relaxation techniquesand massage. The research is Quasi Exsperimen with pretes-posttest design. The statistic test has T test paired and unpairedt test. To indicatea reducing the level of acute before and after given relaxation technique result p-value pain. Therefore, the health of workers, especially for a study to apply relaxation and massage to provide of mother care, mainly to the primigravida who in experienced in process of labor.

  10. Comparison of Relaxation as Self-control and Systematic Desensitization in the Treatment of Test Anxiety

    Science.gov (United States)

    Snyder, Arden L.; Deffenbacher, Jerry L.

    1977-01-01

    Relaxation as self-control and desensitization were compared to a wait-list control in reduction of rest and other anxieties. Active treatments differed significantly from the control treatment. Subjects in both treatments reported less debilitating test anxiety, whereas desensitization subjects showed greater facilitating test anxiety. (Author)

  11. Consequences of recent loophole-free experiments on a relaxation of measurement independence

    Science.gov (United States)

    Hnilo, Alejandro A.

    2017-02-01

    Recent experiments using innovative optical detectors and techniques have strongly increased the capacity of testing the violation of the Bell's inequalities in Nature. Most of them have used the Eberhard's inequality (EI) to close the "detection" loophole. Closing the "locality" loophole has been attempted by spacelike separated detections and fast changes of the bases of observation, driven by random number generators of new design. Also, pulsed pumping and time-resolved data recording to close the "time-coincidence" loophole, and sophisticated statistical methods to close the "memory" loophole, have been used. In this paper, the meaning of the EI is reviewed. A simple hidden variables theory based on a relaxation of the condition of "measurement independence," which was devised long ago for the Clauser-Horne-Shimony and Holt inequality, is adapted to the EI case. It is used here to evaluate the significance of the results of the recent experiments, which are briefly described. A table summarizes the main results.

  12. Measurement and Characterization of Hydrogen-Deuterium Exchange Chemistry Using Relaxation Dispersion NMR Spectroscopy.

    Science.gov (United States)

    Khirich, Gennady; Holliday, Michael J; Lin, Jasper C; Nandy, Aditya

    2018-03-01

    One-dimensional heteronuclear relaxation dispersion NMR spectroscopy at 13 C natural abundance successfully characterized the dynamics of the hydrogen-deuterium exchange reaction occurring at the N ε position in l-arginine by monitoring C δ in varying amounts of D 2 O. A small equilibrium isotope effect was observed and quantified, corresponding to ΔG = -0.14 kcal mol -1 . A bimolecular rate constant of k D = 5.1 × 10 9 s -1 M -1 was determined from the pH*-dependence of k ex (where pH* is the direct electrode reading of pH in 10% D 2 O and k ex is the nuclear spin exchange rate constant), consistent with diffusion-controlled kinetics. The measurement of ΔG serves to bridge the millisecond time scale lifetimes of the detectable positively charged arginine species with the nanosecond time scale lifetime of the nonobservable low-populated neutral arginine intermediate species, thus allowing for characterization of the equilibrium lifetimes of the various arginine species in solution as a function of fractional solvent deuterium content. Despite the system being in fast exchange on the chemical shift time scale, the magnitude of the secondary isotope shift due to the exchange reaction at N ε was accurately measured to be 0.12 ppm directly from curve-fitting D 2 O-dependent dispersion data collected at a single static field strength. These results indicate that relaxation dispersion NMR spectroscopy is a robust and general method for studying base-catalyzed hydrogen-deuterium exchange chemistry at equilibrium.

  13. Chip-Based Measurements of Brownian Relaxation of Magnetic Beads Using a Planar Hall Effect Magnetic Field Sensor

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Dalslet, Bjarke Thomas; Snakenborg, Detlef

    2010-01-01

    using only the self-field arising from the bias current applied to the sensors as excitation field. We present measurements on a suspension of magnetic beads with a nominal diameter of 250 nm vs. temperature and find that the observations are consistent with the Cole-Cole model for Brownian relaxation...... with a constant hydrodynamic bead diameter when the temperature dependence of the viscosity of water is taken into account. These measurements demonstrate the feasibility of performing measurements of the Brownian relaxation response in a lab-on-a-chip system and constitute the first step towards an integrated...... biosensor based on the detection of the dynamic response of magnetic beads....

  14. [Quantitative magnetic resonance imaging of brain iron deposition: comparison between quantitative susceptibility mapping and transverse relaxation rate (R2*) mapping].

    Science.gov (United States)

    Guan, Ji-Jing; Feng, Yan-Qiu

    2018-03-20

    To evaluate the accuracy and sensitivity of quantitative susceptibility mapping (QSM) and transverse relaxation rate (R2*) mapping in the measurement of brain iron deposition. Super paramagnetic iron oxide (SPIO) phantoms and mouse models of Parkinson's disease (PD) related to iron deposition in the substantia nigra (SN) underwent 7.0 T magnetic resonance (MR) scans (Bruker, 70/16) with a multi-echo 3D gradient echo sequence, and the acquired data were processed to obtain QSM and R2*. Linear regression analysis was performed for susceptibility and R2* in the SPIO phantoms containing 5 SPIO concentrations (30, 15, 7.5, 3.75 and 1.875 µg/mL) to evaluate the accuracy of QSM and R2* in quantitative iron analysis. The sensitivities of QSM and R2* mapping in quantitative detection of brain iron deposition were assessed using mouse models of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahy-dropyridine (MPTP) in comparison with the control mice. In SPIO phantoms, QSM provided a higher accuracy than R2* mapping and their goodness-of-fit coefficients (R 2 ) were 0.98 and 0.89, respectively. In the mouse models of PD and control mice, the susceptibility of the SN was significantly higher in the PD models (5.19∓1.58 vs 2.98∓0.88, n=5; Pbrain iron deposition than R2*, and the susceptibility derived by QSM can be a potentially useful biomarker for studying PD.

  15. Novel spin dynamics in ferrimagnetic molecular chains from {sup 1}H NMR and {mu}SR spin-lattice relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Micotti, E. E-mail: micotti@fisicavolta.unipv.it; Lascialfari, A.; Rigamonti, A.; Aldrovandi, S.; Caneschi, A.; Gatteschi, D.; Bogani, L

    2004-05-01

    The spin dynamics in the helical chain Co(hfac){sub 2}NITPhOMe has been investigated by {sup 1}H NMR and {mu}SR relaxation. In the temperature range 15relaxation of the homogeneous magnetization. For T{<=}15 K, NMR and {mu}SR evidence a second spin relaxation mechanism, undetected by the magnetization measurements. From the analysis of these data, insights on this novel relaxation process are derived.

  16. Measurement accuracy of a stressed contact lens during its relaxation period

    Science.gov (United States)

    Compertore, David C.; Ignatovich, Filipp V.

    2018-02-01

    We examine the dioptric power and transmitted wavefront of a contact lens as it releases its handling stresses. Handling stresses are introduced as part of the contact lens loading process and are common across all contact lens measurement procedures and systems. The latest advances in vision correction require tighter quality control during the manufacturing of the contact lenses. The optical power of contact lenses is one of the critical characteristics for users. Power measurements are conducted in the hydrated state, where the lens is resting inside a solution-filled glass cuvette. In a typical approach, the contact lens must be subject to long settling times prior to any measurements. Alternatively, multiple measurements must be averaged. Apart from potential operator dependency of such approach, it is extremely time-consuming, and therefore it precludes higher rates of testing. Comprehensive knowledge about the settling process can be obtained by monitoring multiple parameters of the lens simultaneously. We have developed a system that combines co-aligned a Shack-Hartmann transmitted wavefront sensor and a time-domain low coherence interferometer to measure several optical and physical parameters (power, cylinder power, aberrations, center thickness, sagittal depth, and diameter) simultaneously. We monitor these parameters during the stress relaxation period and show correlations that can be used by manufacturers to devise methods for improved quality control procedures.

  17. Relaxation of energetic S(1D) atoms in Xe gas: comparison of ab initio calculations with experimental data.

    Science.gov (United States)

    Bovino, S; Zhang, P; Kharchenko, V; Dalgarno, A

    2011-07-14

    In this paper, we report our investigation of the translational energy relaxation of fast S((1)D) atoms in a Xe thermal bath. The interaction potential of Xe-S was constructed using ab initio methods. Total and differential cross sections were then calculated. The latter have been incorporated into the construction of the kernel of the Boltzmann equation describing the energy relaxation process. The solution of the Boltzmann equation was obtained and results were compared with those reported in experiments [G. Nan, and P. L. Houston, J. Chem. Phys. 97, 7865 (1992)]. Good agreement with the measured time-dependent relative velocity of fast S((1)D) atoms was obtained except at long relaxation times. The discrepancy may be due to the error accumulation caused by the use of hard sphere approximation and the Monte Carlo analysis of the experimental data. Our accurate description of the energy relaxation process led to an increase in the number of collisions required to achieve equilibrium by an order of magnitude compared to the number given by the hard-sphere approximation.

  18. A comparison of the effects of reflexology and relaxation on pain in women with multiple sclerosis.

    Science.gov (United States)

    Nazari, Fatemeh; Soheili, Mozhgan; Hosseini, SayedMohsen; Shaygannejad, Vahid

    2016-03-01

    Pain is a common and significant symptom in many individuals with multiple sclerosis (MS). The presence and severity of pain in individuals with MS has also been shown to be associated with higher levels of depression, functional impairment, and fatigue. It is common for MS patients and their caregivers to worry about narcotic addiction in the management of chronic pain. Therefore, this study aimed to determine and compare the effects of reflexology and relaxation on pain in women suffering from MS. This study was a single-blind randomized clinical trial performed on 75 patients with MS referred to the MS Clinic of Ayatollah Kashani Hospital (Isfahan, Iran). After simple non-random sampling, using the minimization method, participants were randomly assigned to the three groups of reflexology, relaxation, and control. In the experimental groups, foot reflexology and relaxation interventions (Jacobson and Benson) were performed within 4 weeks, twice a week for 40 min. The control group received routine care and medical treatment as directed by a doctor. Data were collected using the Numerical Rating Scale before, immediately after, and 2 months after interventions in all three groups. Data analysis was performed using SPSS version 18 and descriptive and inferential statistical tests. Findings obtained from analysis of variance (ANOVA) showed no significant differences between mean pain intensity scores in the three groups preintervention and 2 months after interventions (p > 0.05). However, this difference was statistically significant immediately after the study (p reflexology and relaxation (p  0.05). Furthermore, Fisher's least significant difference (LSD) revealed a significantly higher reduction in pain intensity scores in the reflexology group after the intervention, compared with the two other groups, but showed no significant differences between relaxation and control groups. There were no significant differences between the three groups 2 months

  19. A comparison the effects of reflexology and relaxation on the psychological symptoms in women with multiple sclerosis.

    Science.gov (United States)

    Soheili, Mozhgan; Nazari, Fatemeh; Shaygannejad, Vahid; Valiani, Mahboobeh

    2017-01-01

    Multiple sclerosis (MS) occurs with a variety of physical and psychological symptoms, yet there is not a conclusive cure for this disease. Complementary medicine is a current treatment which seems is effective in relieving symptoms of patients with MS. Therefore, this study is aimed to determine and compare the effects of reflexology and relaxation on anxiety, stress, and depression in women with MS. This study is a randomized clinical trial that is done on 75 women with MS referred to MS Clinic of Kashani Hospital. After simple non random sampling, participants were randomly assigned by minimization method to three groups: reflexology, relaxation and control (25 patients in each group). In the experimental groups were performed reflexology and relaxation interventions within 4 weeks, twice a week for 40 min and the control group were received only routine treatment as directed by a doctor. Data were collected through depression anxiety and stress scale questionnaire, before, immediately after and 2 months after interventions in all three groups. Chi-square, Kruskal-Wallis, repeated measures analysis of variance and one-way analysis of variance and least significant difference post hoc test via SPSS version 18 were used to analyze the data ( P < 0.05) was considered as significant level. The results showed a significant reduction in the severity of anxiety, stress and depression during the different times in the reflexology and relaxation groups as compared with the control group ( P < 0.05). The results showed that reflexology and relaxation in relieving anxiety, stress and depression are effective in women with MS. Hence, these two methods, as effective techniques, can be recommended.

  20. Comparison of sensory modes of biofeedback in relaxation training of frontalis muscle.

    Science.gov (United States)

    Chen, W

    1981-12-01

    The purpose of this study was to compare the effectiveness of various sensory modes of EMG biofeedback to relaxation training of the frontalis muscle. 19 male and 29 female subjects were randomly selected from a pool of college volunteers. They were then randomly assigned 12 each to audiofeedback, visual feedback, audiovisual feedback, and no feedback groups. There were 11 20-min. sessions per subject. Subjects in the biofeedback groups were trained to reduce muscle tension voluntarily by utilizing Cyborg J33 EMG portable trainers. The subjects in the three feedback groups exhibited significantly lower muscle tension than did the subjects in the no-feedback control group. There were no significant differences in relaxation among the three feedback groups.

  1. Comparison of Vibrational Relaxation Modeling for Strongly Non-Equilibrium Flows

    Science.gov (United States)

    2014-01-01

    important pro- cess in a wide range of high speed flows. High temperature shock layers that form in front of hypersonic vehicles can lead to significant...continuum flows for use in traditional Computational Fluid Dynamics ( CFD ) and non-continuum flows for use with rarefied flow de- scriptions, such as the...145 .98 4396 V. Summary and Conclusions The form of two vibrational relaxation models that are commonly used in DSMC and CFD simula- tions have been

  2. A Microstructural Study of Load Distribution in Cartilage: A Comparison of Stress Relaxation versus Creep Loading

    Directory of Open Access Journals (Sweden)

    Ashvin Thambyah

    2015-01-01

    Full Text Available The compressive response of articular cartilage has been extensively investigated and most studies have focussed largely on the directly loaded matrix. However, especially in relation to the tissue microstructure, less is known about load distribution mechanisms operating outside the directly loaded region. We have addressed this issue by using channel indentation and DIC microscopy techniques that provide visualisation of the matrix microstructural response across the regions of both direct and nondirect loading. We hypothesise that, by comparing the microstructural response following stress relaxation and creep compression, new insights can be revealed concerning the complex mechanisms of load bearing. Our results indicate that, with stress relaxation, the initial mode of stress decay appears to primarily involve relaxation of the surface layer. In the creep loading protocol, the main mode of stress release is a lateral distribution of load via the mid matrix. While these two modes of stress redistribution have a complex relationship with the zonally differentiated tissue microstructure and the depth of strain, four mechanostructural mechanisms are proposed to describe succinctly the load responses observed.

  3. Direct measurements of relaxation times of phosphorus metabolites in the human myocardium

    International Nuclear Information System (INIS)

    Schindler, R.; Krahe, T.; Neubauer, S.; Hillenbrand, H.; Entzeroth, C.; Horn, M.; Lackner, K.; Ertl, G.

    1992-01-01

    The T 1 relaxation times of the phosphorus metabolites in human heart muscle measurable by 31 P-MR spectra were determined in 12 individuals using a 1.5 Tesla system. Several spectra were recorded consecutively with a pulse repetition time of 1.6s to 24 s. The T 1 times of creatine phosphate (CP), of γ-, α-, β-adenosintriphosphate (ATP), 2,3-diphosphoglycerate (2,3-DPG) together with anorganic phosphate) and phosphodiester (PDE) showed mean measurements of 6.1±0.5, 5.4±0.5, 5.0±0.5, 5.8±1.0, 7.6±1.0, and 5.0±1.0s (M±SE). The accuracy of the ISIS technique was tested with a special phantom. T 1 times were also measured in standard solutions (20mM CP, 10mM ATP); CP was 8.7±0.2s and γ-ATP was 9.9±0.7s. Corrections for partially saturated 31 P-MR spectra - at least for CP/ATP ratios - are relatively small. (orig.) [de

  4. 13C spin relaxation measurements in RNA: Sensitivity and resolution improvement using spin-state selective correlation experiments

    International Nuclear Information System (INIS)

    Boisbouvier, Jerome; Brutscher, Bernhard; Simorre, Jean-Pierre; Marion, Dominique

    1999-01-01

    A set of new NMR pulse sequences has been designed for the measurement of 13 C relaxation rate constants in RNA and DNA bases: the spin-lattice relaxation rate constant R(C z ), the spin-spin relaxation rate constant R(C + ), and the CSA-dipolar cross-correlated relaxation rate constant Γ C,CH xy . The use of spin-state selective correlation techniques provides increased sensitivity and spectral resolution. Sensitivity optimised C-C filters are included in the pulse schemes for the suppression of signals originating from undesired carbon isotopomers. The experiments are applied to a 15% 13 C-labelled 33-mer RNA-theophylline complex. The measured R(C + )/Γ C,CH xy ratios indicate that 13 C CSA tensors do not vary significantly for the same type of carbon (C 2 , C 6 , C 8 ), but that they differ from one type to another. In addition, conformational exchange effects in the RNA bases are detected as a change in the relaxation decay of the narrow 13 C doublet component when varying the spacing of a CPMG pulse train. This new approach allows the detection of small exchange effects with a higher precision compared to conventional techniques

  5. Intrinsic spin and momentum relaxation in organic single-crystalline semiconductors probed by ESR and Hall measurements

    Science.gov (United States)

    Tsurumi, Junto; Häusermann, Roger; Watanabe, Shun; Mitsui, Chikahiko; Okamoto, Toshihiro; Matsui, Hiroyuki; Takeya, Jun

    Spin and charge momentum relaxation mechanism has been argued among organic semiconductors with various methods, devices, and materials. However, little is known in organic single-crystalline semiconductors because it has been hard to obtain an ideal organic crystal with an excellent crystallinity and controllability required for accurate measurements. By using more than 1-inch sized single crystals which are fabricated via contentious edge-casting method developed by our group, we have successfully demonstrated a simultaneous determination of spin and momentum relaxation time for gate-induced charges of 3,11-didecyldinaphtho[2,3- d:2',3'- d']benzo[1,2- b:4,5- b']dithiophene, by combining electron spin resonance (ESR) and Hall effect measurements. The obtained temperature dependences of spin and momentum relaxation times are in good agreement in terms of power law with a factor of approximately -2. It is concluded that Elliott-Yafet spin relaxation mechanism can be dominant at room temperature regime (200 - 300 K). Probing characteristic time scales such as spin-lattice, spin-spin, and momentum relaxation times, demonstrated in the present work, would be a powerful tool to elucidate fundamental spin and charge transport mechanisms. We acknowledge the New Energy and Industrial Technology Developing Organization (NEDO) for financial support.

  6. Ethene, propene, butene and isoprene emissions from a ponderosa pine forest measured by relaxed eddy accumulation

    Science.gov (United States)

    Rhew, Robert C.; Deventer, Malte Julian; Turnipseed, Andrew A.; Warneke, Carsten; Ortega, John; Shen, Steve; Martinez, Luis; Koss, Abigail; Lerner, Brian M.; Gilman, Jessica B.; Smith, James N.; Guenther, Alex B.; de Gouw, Joost A.

    2017-11-01

    Alkenes are reactive hydrocarbons that influence local and regional atmospheric chemistry by playing important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. The simplest alkene, ethene (ethylene), is a major plant hormone and ripening agent for agricultural commodities. The group of light alkenes (C2-C4) originates from both biogenic and anthropogenic sources, but their biogenic sources are poorly characterized, with limited field-based flux observations. Here we report net ecosystem fluxes of light alkenes and isoprene from a semiarid ponderosa pine forest in the Rocky Mountains of Colorado, USA using the relaxed eddy accumulation (REA) technique during the summer of 2014. Ethene, propene, butene and isoprene emissions have strong diurnal cycles, with median daytime fluxes of 123, 95, 39 and 17 µg m-2 h-1, respectively. The fluxes were correlated with each other, followed general ecosystem trends of CO2 and water vapor, and showed similar sunlight and temperature response curves as other biogenic VOCs. The May through October flux, based on measurements and modeling, averaged 62, 52, 24 and 18 µg m-2 h-1 for ethene, propene, butene and isoprene, respectively. The light alkenes contribute significantly to the overall biogenic source of reactive hydrocarbons: roughly 18 % of the dominant biogenic VOC, 2-methyl-3-buten-2-ol. The measured ecosystem scale fluxes are 40-80 % larger than estimates used for global emissions models for this type of ecosystem.

  7. Disentangling distribution effects and nature of the dynamics in relaxation measurements: the RMR method

    CERN Document Server

    Sappey, R; Ocio, M; Hammann, J

    2000-01-01

    We discuss here the nature of the low-temperature magnetic relaxation in samples of magnetic nanoparticles. In addition to usual magnetic viscosity measurement, we have used the residual memory ratio (RMR) method. This procedure enables us to overcome the uncertainties usually associated with the energy barrier distribution, thus giving a more detailed insight on the nature of the observed dynamics. A custom-made apparatus coupling dilution refrigeration and SQUID magnetometry allowed measurements of very diluted samples at temperatures ranging between 60 mK and 7 K. Two types of particles have been studied: gamma-Fe sub 2 O sub 3 of moderate anisotropy, and CoFe sub 2 O sub 4 of higher anisotropy where quantum effects are more likely to occur. In both cases, the data cannot simply be interpreted in terms of mere thermally activated dynamics of independent particles. The deviation from thermal activation seems to go opposite of what is expected from the possible effect of particle interactions. We therefore b...

  8. 31P spin-lattice relaxation time measurements in biological systems

    International Nuclear Information System (INIS)

    Suzuki, Eiji; Maeda, Munehiro; Kuki, Satoru; Tsukamoto, Kenji; Kawakami, Tsuyoshi; Seo, Yoshiteru; Murakami, Masataka; Watari, Hiroshi

    1989-01-01

    Spin-lattice relaxation time (T 1 ) of phosphorus compounds in the perfused heart, liver, kidney and erythrocytes of rats were measured by the DESPOT (Driven-equilibrium single-pulse observation of T 1 ) method at 8.45 T. This method is a rapid and accurate technique for the measurement of T 1 values. T 1 values of phosphomonoesters (PME), 2, 3-diphosphoglycerate (DPG), inorganic phosphate (Pi), phosphodiesters (PDE), phosphocreatine (PCr) and three phosphates of ATP were ranged from 0.15±0.02 sec (β-ATP in the liver) to 8.5±1.6 sec (PDE in the kidney). T 1 value of β-ATP in the liver was 1/4-1/5 of those in the mandibular gland, heart, erythrocytes and kidney. T 1 values obtained from biological materials are useful for selecting the optimal pulse repetition times and pulse angles to maximize the signal-to-noise ratio of 13 P spectra, and for correcting distortions of signal intensities in the spectra. (author)

  9. A relaxed eddy accumulation system for measuring vertical fluxes of nitrous acid

    Directory of Open Access Journals (Sweden)

    X. Ren

    2011-10-01

    Full Text Available A relaxed eddy accumulation (REA system combined with a nitrous acid (HONO analyzer was developed to measure atmospheric HONO vertical fluxes. The system consists of three major components: (1 a fast-response sonic anemometer measuring both vertical wind velocity and air temperature, (2 a fast-response controlling unit separating air motions into updraft and downdraft samplers by the sign of vertical wind velocity, and (3 a highly sensitive HONO analyzer based on aqueous long path absorption photometry that measures HONO concentrations in the updrafts and downdrafts. A dynamic velocity threshold (±0.5σw, where σw is a standard deviation of the vertical wind velocity was used for valve switching determined by the running means and standard deviations of the vertical wind velocity. Using measured temperature as a tracer and the average values from two field deployments, the flux proportionality coefficient, β, was determined to be 0.42 ± 0.02, in good agreement with the theoretical estimation. The REA system was deployed in two ground-based field studies. In the California Research at the Nexus of Air Quality and Climate Change (CalNex study in Bakersfield, California in summer 2010, measured HONO fluxes appeared to be upward during the day and were close to zero at night. The upward HONO flux was highly correlated to the product of NO2 and solar radiation. During the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX 2009 at Blodgett Forest, California in July 2009, the overall HONO fluxes were small in magnitude and were close to zero. Causes for the different HONO fluxes in the two different environments are briefly discussed.

  10. Metastability exchange optical pumping in 3He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    International Nuclear Information System (INIS)

    Batz, Marion

    2011-01-01

    Advances in metastability exchange optical pumping (MEOP) of 3 He at high laser powers, with its various applications, but also at high gas pressures p 3 and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B≤30 mT and p 3 =0.63-2.45 mbar. 3 He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  11. First measurements of H2O2 and organic peroxide surface fluces by the Relaxed Eddy Accumulation technique

    NARCIS (Netherlands)

    Valverde-Canossa, J.; Ganzeveld, L.N.; Rappenglück, B.; Steinbrecher, R.; Klemm, O.; Schuster, G.; Moortgat, G.K.

    2006-01-01

    The relaxed eddy-accumulation (REA) technique was specially adapted to a high-performance liquid chromatographer (enzymatic method) and scrubbing coils to measure concentrations and fluxes of hydrogen peroxide (H2O2) and organic peroxides with a carbon chain C4, of which only methylhydroperoxide

  12. Structure, Dynamics, and Kinetics of Weak Protein-Protein Complexes from NMR Spin Relaxation Measurements of Titrated Solutions

    International Nuclear Information System (INIS)

    Salmon, L.; Licinio, A.; Jensen, M.R.; Blackledge, M.; Ortega Roldan, J.L.; Van Nuland, N.; Lescop, E.

    2011-01-01

    We have recently presented a titration approach for the determination of residual dipolar couplings (RDCs) from experimentally inaccessible complexes. Here, we extend this approach to the measurement of 15 N spin relaxation rates and demonstrate that this can provide long-range structural, dynamic, and kinetic information about these elusive systems. (authors)

  13. USE OF RELAXED EDDY ACCUMULATION TO MEASURE BIOSPHERE-ATMOSPHERE EXCHANGE OF ISOPRENE AND OTHER BIOLOGICAL TRACE GASES

    Science.gov (United States)

    The micrometeorological flux measurement technique known as relaxed eddy accumulation (REA) holds promise as a powerful new tool for ecologists. The more popular eddy covariance (eddy correlation) technique requires the use of sensors that can respond at fast rates (10 Hz), and t...

  14. Comparison of Property-Oriented Basis Sets for the Computation of Electronic and Nuclear Relaxation Hyperpolarizabilities.

    Science.gov (United States)

    Zaleśny, Robert; Baranowska-Łączkowska, Angelika; Medveď, Miroslav; Luis, Josep M

    2015-09-08

    In the present work, we perform an assessment of several property-oriented atomic basis sets in computing (hyper)polarizabilities with a focus on the vibrational contributions. Our analysis encompasses the Pol and LPol-ds basis sets of Sadlej and co-workers, the def2-SVPD and def2-TZVPD basis sets of Rappoport and Furche, and the ORP basis set of Baranowska-Łączkowska and Łączkowski. Additionally, we use the d-aug-cc-pVQZ and aug-cc-pVTZ basis sets of Dunning and co-workers to determine the reference estimates of the investigated electric properties for small- and medium-sized molecules, respectively. We combine these basis sets with ab initio post-Hartree-Fock quantum-chemistry approaches (including the coupled cluster method) to calculate electronic and nuclear relaxation (hyper)polarizabilities of carbon dioxide, formaldehyde, cis-diazene, and a medium-sized Schiff base. The primary finding of our study is that, among all studied property-oriented basis sets, only the def2-TZVPD and ORP basis sets yield nuclear relaxation (hyper)polarizabilities of small molecules with average absolute errors less than 5.5%. A similar accuracy for the nuclear relaxation (hyper)polarizabilites of the studied systems can also be reached using the aug-cc-pVDZ basis set (5.3%), although for more accurate calculations of vibrational contributions, i.e., average absolute errors less than 1%, the aug-cc-pVTZ basis set is recommended. It was also demonstrated that anharmonic contributions to first and second hyperpolarizabilities of a medium-sized Schiff base are particularly difficult to accurately predict at the correlated level using property-oriented basis sets. For instance, the value of the nuclear relaxation first hyperpolarizability computed at the MP2/def2-TZVPD level of theory is roughly 3 times larger than that determined using the aug-cc-pVTZ basis set. We link the failure of the def2-TZVPD basis set with the difficulties in predicting the first-order field

  15. Stress relaxation of bi-disperse polystyrene melts

    DEFF Research Database (Denmark)

    Hengeller, Ludovica; Huang, Qian; Dorokhin, Andriy

    2016-01-01

    We present start-up of uniaxial extension followed by stress relaxation experiments of a bi-disperse 50 % by weight blend of 95k and 545k molecular weight polystyrene. We also show, for comparison, stress relaxation measurements of the polystyrene melts with molecular weight 95k and 545k, which...... are the components of the bi-disperse melt. The measurements show three separated relaxation regimes: a fast regime, a transition regime, and a slow regime. In the fast regime, the orientation of the long chains is frozen and the stress relaxation is due to stretch relaxation of the short chains primarily....... Conversely in the slow regime, the long chains have retracted and undergo relaxation of orientation in fully relaxed short chains....

  16. Comparison of hypnosis with conventional relaxation for antenatal and intrapartum use: a feasibility study in general practice

    Science.gov (United States)

    Brann, Les R.; Guzvica, Sally A.

    1987-01-01

    A hypnosis programme for antenatal and intrapartum use has been developed and successfully introduced into a practice as an alternative to conventional relaxation training. Of 96 women from the practice who delivered during the 10-month period of the study 51 opted for the psychoprophylaxis and 45 for the hypnosis. Details of the pregnancy, labour and postnatal period were collected for both groups, together with a subjective assessment of their satisfaction with labour. Disparity between the ages and parity of the two groups made comparisons difficult. The duration of the first stage of labour was markedly reduced in the hypnosis group by 98 minutes for primiparas and 40 minutes for multiparas. A small (five minutes) increase in the length of the second stage may have been a result of the hypnotic relaxation. The verbalization has been amended accordingly. The hypnosis group were more satisfied with labour than the psychoprophylaxis group (mean satisfaction score 7.4 versus 5.6) and they reported other benefits of hypnosis, for example, reduction in anxiety and help with getting to sleep.Further studies are planned. PMID:3333169

  17. Comparison of Semidefinite Relaxation Detectors for High-Order Modulation MIMO Systems

    Directory of Open Access Journals (Sweden)

    Z. Y. Shao

    2014-01-01

    Full Text Available Multiple-input multiple-output (MIMO system is considered to be one of the key technologies of LTE since it achieves requirements of high throughput and spectral efficiency. The semidefinite relaxation (SDR detection for MIMO systems is an attractive alternative to the optimum maximum likelihood (ML decoding because it is very computationally efficient. We propose a new SDR detector for 256-QAM MIMO system and compare its performance with two other SDR detectors, namely, BC-SDR detector and VA-SDR detector. The tightness and complexity of these three SDR detectors are analyzed. Both theoretical analysis and simulation results demonstrate that the proposed SDR can provide the best BLER performance among the three detectors, while the BC-SDR detector and the VA-SDR detector provide identical BLER performance. Moreover, the BC-SDR has the lowest computational complexity and the VA-SDR has the highest computational complexity, while the proposed SDR is in between.

  18. Relaxation of a steep density gradient in a simple fluid: Comparison between atomistic and continuum modeling

    International Nuclear Information System (INIS)

    Pourali, Meisam; Maghari, Ali; Meloni, Simone; Magaletti, Francesco; Casciola, Carlo Massimo; Ciccotti, Giovanni

    2014-01-01

    We compare dynamical nonequilibrium molecular dynamics and continuum simulations of the dynamics of relaxation of a fluid system characterized by a non-uniform density profile. Results match quite well as long as the lengthscale of density nonuniformities are greater than the molecular scale (∼10 times the molecular size). In presence of molecular scale features some of the continuum fields (e.g., density and momentum) are in good agreement with atomistic counterparts, but are smoother. On the contrary, other fields, such as the temperature field, present very large difference with respect to reference (atomistic) ones. This is due to the limited accuracy of some of the empirical relations used in continuum models, the equation of state of the fluid in the present example

  19. Solution conformation and dynamics of a tetrasaccharide related to the LewisX antigen deduced by NMR relaxation measurements

    International Nuclear Information System (INIS)

    Poveda, Ana; Asensio, Juan Luis; Martin-Pastor, Manuel; Jimenez-Barbero, Jesus

    1997-01-01

    1 H-NMR cross-relaxation rates and nonselective longitudinal relaxation times have been obtained at two magnetic fields (7.0 and 11.8 T) and at a variety of temperatures for the branched tetrasaccharide methyl 3-O-α-N-acetyl-galactosaminyl-β-galactopyranosyl-(1 → 4)[3-O-α-fucosyl] -glucopyranoside (1), an inhibitor of astrocyte growth. In addition, 13 C-NMR relaxation data have also been recorded at both fields. The 1 H-NMR relaxation data have been interpreted using different motional models to obtain proton-proton correlation times. The results indicate that the GalNAc and Fuc rings display more extensive local motion than the two inner Glc and Gal moieties, since those present significantly shorter local correlation times. The 13 C-NMR relaxation parameters have been interpreted in terms of the Lipari-Szabo model-free approach. Thus, order parameters and internal motion correlation times have been deduced. As obtained for the 1 H-NMR relaxation data, the two outer residues possess smaller order parameters than the two inner rings. Internal correlation times are in the order of 100 ps. The hydroxymethyl groups have also different behaviour,with the exocyclic carbon on the glucopyranoside unit showing the highestS 2 . Molecular dynamics simulations using a solvated system have also been performed and internal motion correlation functions have been deduced from these calculations. Order parameters and interproton distances have been compared to those inferred from the NMR measurements. The obtained results are in fair agreement with the experimental data

  20. Solution conformation and dynamics of a tetrasaccharide related to the Lewis{sup X} antigen deduced by NMR relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Poveda, Ana [Universidad Autonoma de Madrid, Servicio Interdepartamental de Investigacion (Spain); Asensio, Juan Luis; Martin-Pastor, Manuel; Jimenez-Barbero, Jesus [Instituto de Quimica Organica, CSIC, Grupo de Carbohidratos (Spain)

    1997-07-15

    {sup 1}H-NMR cross-relaxation rates and nonselective longitudinal relaxation times have been obtained at two magnetic fields (7.0 and 11.8 T) and at a variety of temperatures for the branched tetrasaccharide methyl 3-O-{alpha}-N-acetyl-galactosaminyl-{beta}-galactopyranosyl-(1{sup {yields}}4)[3-O-{alpha}-fucosyl] -glucopyranoside (1), an inhibitor of astrocyte growth. In addition, {sup 13}C-NMR relaxation data have also been recorded at both fields. The {sup 1}H-NMR relaxation data have been interpreted using different motional models to obtain proton-proton correlation times. The results indicate that the GalNAc and Fuc rings display more extensive local motion than the two inner Glc and Gal moieties, since those present significantly shorter local correlation times. The{sup 13}C-NMR relaxation parameters have been interpreted in terms of the Lipari-Szabo model-free approach. Thus, order parameters and internal motion correlation times have been deduced. As obtained for the{sup 1}H-NMR relaxation data, the two outer residues possess smaller order parameters than the two inner rings. Internal correlation times are in the order of 100 ps. The hydroxymethyl groups have also different behaviour,with the exocyclic carbon on the glucopyranoside unit showing the highestS{sup 2}. Molecular dynamics simulations using a solvated system have also been performed and internal motion correlation functions have been deduced from these calculations. Order parameters and interproton distances have been compared to those inferred from the NMR measurements. The obtained results are in fair agreement with the experimental data.

  1. Multilayer Relaxation and Surface Energies of Metallic Surfaces

    Science.gov (United States)

    Bozzolo, Guillermo; Rodriguez, Agustin M.; Ferrante, John

    1994-01-01

    The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for AI(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included.

  2. On-chip measurements of Brownian relaxation of magnetic beads with diameters from 10 nm to 250 nm

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2013-01-01

    We demonstrate the use of planar Hall effect magnetoresistive sensors for AC susceptibility measurements of magnetic beads with frequencies ranging from DC to 1 MHz. This wide frequency range allows for measuring Brownian relaxation of magnetic beads with diameters ranging from 10 nm to 250 nm....... Brownian relaxation is measured for six different magnetic bead types and their hydrodynamic diameters are determined. The hydrodynamic diameters are found to be within 40% of the nominal bead diameters. We discuss the applicability of the different bead types for volume-based biosensing with respect...... to sedimentation, magnetic trapping, and signal per bead. Among the investigated beads, we conclude that the beads with a nominal diameter of 80 nm are best suited for future on-chip volume-based biosensing experiments using planar Hall effect sensors....

  3. European Measurement Comparisons of Environmental Radioactivity

    International Nuclear Information System (INIS)

    Waetjen, Uwe

    2008-01-01

    The scheme of European measurement comparisons to verify radioactivity monitoring in the European Union is briefly explained. After a review of comparisons conducted during the years 1990, the approach of IRMM organising these comparisons since 2003 is presented. IRMM is providing comparison samples with a reference value traceable to the SI units and which is fully documented to all participants and national authorities after completion of the comparison. The sample preparation and determination of traceable reference values at IRMM, the sample treatment and measurement in the participating laboratories, as well as the evaluation of comparison results are described in some detail using the example of an air filter comparison. The results of a comparison to determine metabolised 40 K, 90 Sr and 137 Cs in milk powder are presented as well. The necessary improvements in the estimation of measurement uncertainty by the participating laboratories are discussed. The performance of individual laboratories which have participated in at least four comparison exercises over the years is studied in terms of observable trends

  4. Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein ubiquinone oxidoreductase (ETF QO)

    Science.gov (United States)

    Fielding, Alistair J.; Usselman, Robert J.; Watmough, Nicholas; Simkovic, Martin; Frerman, Frank E.; Eaton, Gareth R.; Eaton, Sandra S.

    2008-02-01

    Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S] 2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S] + cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S] + between 8 and 18 K and for semiquinone between 25 and 65 K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S] + were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S] + and obtain point-dipole interspin distances of 18.6 ± 1 Å for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.

  5. Transverse magnetic field effects on the relaxation time of the magnetization in Mn12 measured by {sup 55}Mn-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Y.; Watanabe, K.; Kumagai, K.; Borsa, F.; Gatteschi, D

    2003-05-01

    The longitudinal (H{sub Z}) and transverse (H{sub T}) magnetic field dependence of the relaxation time of the magnetization in Mn12 in its S=10 ground state was measured by NMR. The minima in the relaxation time at the fields for level crossing are due to the quantum tunneling of the magnetization. The shortening of the relaxation time under the application of H{sub T} is shown to be due mainly to the reduction of the energy barrier.

  6. HIGHLY RESOLVED MEASUREMENTS OF PERIODIC RADIAL ELECTRIC FIELD AND ASSOCIATED RELAXATIONS IN EDGE BIASING EXPERIMENTS

    Czech Academy of Sciences Publication Activity Database

    Peleman, P.; Xu, Y.; Spolaore, M.; Brotánková, Jana; Devynck, P.; Stöckel, Jan; Van Oost, G.; Boucher, C.

    363-365, č. 17 (2007), s. 638-642 ISSN 0022-3115. [ Plasma Surface Interactions in Controlled Fusion Devices/17th./. Hefei, 22.05.2007-26.05.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Relaxations * Edge transport * Plasma flow * Radial electric fields Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.643, year: 2007

  7. On-chip measurement of the Brownian relaxation frequency of magnetic beads using magnetic tunneling junctions

    DEFF Research Database (Denmark)

    Donolato, M.; Sogne, E.; Dalslet, Bjarke Thomas

    2011-01-01

    We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free...

  8. In-vivo measurement of proton relaxation time (T1 and T2) in paediatric brain by MRI

    International Nuclear Information System (INIS)

    Masumura, Michio

    1986-01-01

    The clinical application of MRI led to the detailed imaging of the three-dimentional structure of the brain. Thus, significant information has been obtained with respect to the diagnosis of various diseases, rating severity, evaluation of curative effects, etc. On the other hand, the proportion of the comparative length of the relaxation time to the signal intensity of the images (especially the Spin-Echo image) was not necessarily linear. Consquently, the evaluation of severity was not easy to make. However, if we can obtain T 1 and T 2 precisely as the parameters costituting the images, it will be possible to overcome the above-mentioned difficulties. Further, the usefulness of MRI in activities such as determining the water metabolism of the brain is expected to increase even more. By means of VISTA-MR (0.15 Tesla, resistive magnet ; Picker International Co.) we measured the proton relaxation time (spin-lattice relaxation time (T 1 ) and spin-spin relaxation time (T 2 )) of various intracerebral lesions in paediatric cases. As the control group, 43 children, 4 adolescents and 6 adults were used. The T 1 and T 2 in the normal infantile cases prolonged significantly as compared with adult case. Thereafter, they become shortened by aging. In the age of two or three years, they reach the normal level of adult case. In the cases of degenerative disease, brain tumor, and cerebral contusion, the remarkable prolongation of both T 1 and T 2 , compared with normal value of the same age was observed. In the cases of brain atrophy and epilepsy, T 1 and T 2 were slightly short or within normal value of the same age. In the cases of intracerebral hemorrhage, T 1 was shortened. The in-vivo proton relaxation time obtained by MRI have various limits, but they can be a noninvasive and useful index in evaluation of severity or curative effects in various cerebral diseases. (author)

  9. Comparison between the results of stress relaxation - and creep tests in a stainless steel 316 at 8000C

    International Nuclear Information System (INIS)

    Miranda, P.E.V. de.

    1978-07-01

    A sequence of stress relaxation tests from the same initial stress showed an estabilization of the relaxed fraction of stress of a 316 stainless steel at 800 0 C. This represents the exhaustion of the deformation process of the material at this temperature. Results from the relaxation tests were obtained by utilizing a recently proposed model. The slope in from the log epsilon sup(.) x logσ/E curve obtained by relaxation (n = 6,80) closely matched that determined by creep tests (n = 6,50). This presents a possibility of determined by stress relaxation of the parameters usually calculated by creep. (Author) [pt

  10. Redox-controlled backbone dynamics of human cytochrome c revealed by 15N NMR relaxation measurements

    International Nuclear Information System (INIS)

    Sakamoto, Koichi; Kamiya, Masakatsu; Uchida, Takeshi; Kawano, Keiichi; Ishimori, Koichiro

    2010-01-01

    Research highlights: → The dynamic parameters for the backbone dynamics in Cyt c were determined. → The backbone mobility of Cyt c is highly restricted due to the covalently bound heme. → The backbone mobility of Cyt c is more restricted upon the oxidation of the heme. → The redox-dependent dynamics are shown in the backbone of Cyt c. → The backbone dynamics of Cyt c would regulate the electron transfer from Cyt c. -- Abstract: Redox-controlled backbone dynamics in cytochrome c (Cyt c) were revealed by 2D 15 N NMR relaxation experiments. 15 N T 1 and T 2 values and 1 H- 15 N NOEs of uniformly 15 N-labeled reduced and oxidized Cyt c were measured, and the generalized order parameters (S 2 ), the effective correlation time for internal motion (τ e ), the 15 N exchange broadening contributions (R ex ) for each residue, and the overall correlation time (τ m ) were estimated by model-free dynamics formalism. These dynamic parameters clearly showed that the backbone dynamics of Cyt c are highly restricted due to the covalently bound heme that functions as the stable hydrophobic core. Upon oxidation of the heme iron in Cyt c, the average S 2 value was increased from 0.88 ± 0.01 to 0.92 ± 0.01, demonstrating that the mobility of the backbone is further restricted in the oxidized form. Such increases in the S 2 values were more prominent in the loop regions, including amino acid residues near the thioether bonds to the heme moiety and positively charged region around Lys87. Both of the regions are supposed to form the interaction site for cytochrome c oxidase (CcO) and the electron pathway from Cyt c to CcO. The redox-dependent mobility of the backbone in the interaction site for the electron transfer to CcO suggests an electron transfer mechanism regulated by the backbone dynamics in the Cyt c-CcO system.

  11. Brain connectivity measures: computation and comparison

    Directory of Open Access Journals (Sweden)

    Jovanović Aleksandar

    2013-12-01

    Full Text Available In this article computation and comparison of causality measures which are used in determination of brain connectivity patterns is investigated. Main analyzed examples included published computation and comparisons of Directed Transfer Function ‐ DTF and Partial Directed Coherence ‐ PDC. It proved that serious methodology mistakes were involved in measure computations and comparisons. It is shown that the neighborhood of zero is of accented importance in such evaluations and that the issues of semantic stability have to be treated with more attention. Published results on the relationship of these two important measures are partly unstable with small changes of zero threshold and pictures of involved brain structures deduced from the cited articles have to be corrected. Analysis of the operators involved in evaluation and comparisons is given with suggestions for their improvement and complementary additional actions.

  12. Measuring oxygen surface exchange kinetics on mixed-conducting composites by electrical conductivity relaxation

    NARCIS (Netherlands)

    Hu, Bobing; Wang, Yunlong; Zhu, Zhuoying; Xia, Changrong; Bouwmeester, Henricus J.M.

    2015-01-01

    The oxygen release kinetics of mixed-conducting Sr2Fe1.5Mo0.5O6 d–Sm0.2Ce0.8O2 d (SFM–SDC) dualphase composites has been investigated, at 750 C, as a function of the SDC phase volume fraction using electrical conductivity relaxation (ECR) under reducing atmospheres, extending our previous work on

  13. In vivo relaxation time measurements on a murine tumor model--prolongation of T1 after photodynamic therapy.

    Science.gov (United States)

    Liu, Y H; Hawk, R M; Ramaprasad, S

    1995-01-01

    RIF tumors implanted on mice feet were investigated for changes in relaxation times (T1 and T2) after photodynamic therapy (PDT). Photodynamic therapy was performed using Photofrin II as the photosensitizer and laser light at 630 nm. A home-built proton solenoid coil in the balanced configuration was used to accommodate the tumors, and the relaxation times were measured before, immediately after, and up to several hours after therapy. Several control experiments were performed untreated tumors, tumors treated with Photofrin II alone, or tumors treated with laser light alone. Significant increases in T1s of water protons were observed after PDT treatment. In all experiments, 31P spectra were recorded before and after the therapy to study the tumor status and to confirm the onset of PDT. These studies show significant prolongation of T1s after the PDT treatment. The spin-spin relaxation measurements, on the other hand, did not show such prolongation in T2 values after PDT treatment.

  14. Relaxation times T1, T2, and T2* of apples, pears, citrus fruits, and potatoes with a comparison to human tissues

    International Nuclear Information System (INIS)

    Werz, Karin; Braun, Hans; Vitha, Dominik; Bruno, Graziano; Martirosian, Petros; Steidle, Guenter; Schick, Fritz

    2011-01-01

    The aim of the project was a systematic assessment of relaxation times of different fruits and vegetables and a comparison to values of human tissues. Results provide an improved basis for selection of plant phantoms for development of new MR techniques and sequences. Vessels filled with agar gel are mostly used for this purpose, preparation of which is effortful and time-consuming. In the presented study apples, (malus, 8 species), pears, (pyrus, 2 species), citrus fruits (citrus, 5 species) and uncooked potatoes (solanum tuberosum, 8 species) from the supermarket were examined which are easily available nearly all-the-year. T1, T2 and T2 * relaxation times of these nature products were measured on a 1.5 Tesla MR system with adapted examination protocols and mono-exponential fitting, and compared to literature data of human parenchyma tissues, fatty tissue and body fluid (cerebrospinal fluid). Resulting values were as follows: apples: T1: 1486 - 1874 ms, T2: 163 - 281 ms, T2 * : 2,3 - 3,2 ms; pears: T1: 1631 - 1969 ms, T2: 119 - 133 ms, T2 * : 10,1 - 10,6 ms, citrus fruits (pulp) T1: 2055 - 2632 ms, T2: 497 - 998 ms, T2 * : 151 - 182 ms; citrus fruits (skin) T1: 561 - 1669 ms, T2: 93 - 119 ms; potatoes: T1: 1011 - 1459 ms, T2: 166 - 210 ms, T2 * : 20 - 30 ms. All T1-values of the examined objects (except for potatoes and skins of citrus fruits) were longer than T1 values of human tissues. Also T2 values (except for pears and skins of citrus fruits) of the fruits and the potatoes tended to be longer. T2 * values of apples, pears and potatoes were shorter than in healthy human tissue. Results show relaxation values of many fruits to be not exactly fitting to human tissue, but with suitable selection of the fruits and optionally with an adaption of measurement parameters one can achieve suitable contrast and signal characteristics for some purposes. (orig.)

  15. Mesures de contraintes in-situ. Méthode de relaxation des carottes Measuring in-Situ Stresses. Relaxation Method with Core Samples

    Directory of Open Access Journals (Sweden)

    Perreau P.

    2006-11-01

    Full Text Available Dans cet article, on se propose de présenter les premiers résultats de l'étude de la méthode d'évaluation des contraintes par mesure de déformations différées d'une carotte après son extraction. Le travail correspondant a été réalisé dans le cadre du projet ARTEP Fracturation hydraulique . Les principes de cette méthode et les quelques éléments d'interprétation récemment publiés dans la littérature sont exposés dans un premier temps. Les résultats de deux campagnes de mesures sur deux puits de la SNEA-P (Soudron, novembre 1985 et Lanot, juillet 1986 sont ensuite présentés. Ces essais ont mis en évidence que les déformations différées d'une carotte dues au relachement des contraintes sont effectivement mesurables. Cependant, une interprétation quantitative de ces mesures nécessite une amélioration des conditions expérimentales (stabilisation thermique, stabilisation de l'état de saturation. This article describes the first results of research on a method of evaluating stresses by measuring the differred deformations of a core sample after it has been extracted. The corresponding research was done within the framework of an ARTEP project on Hydraulic Fracturing . The principles of this method and several interpretation aspects published recently in the literature are described in the first part. Then the results of two measurement campaigns using two SNEA-P wells (Soudron in November 1985 and Lanot in July 1986 are described. These tests revealed that the differed deformations of a core sample due to the relaxing of stresses can effectively be measured. However, a quantitative interpretation of these measurements requires an improvement to be made in the experimental conditions (thermal stabilization, stabilization of the state of saturation.

  16. Metastability exchange optical pumping in {sup 3}He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Batz, Marion

    2011-07-08

    Advances in metastability exchange optical pumping (MEOP) of {sup 3}He at high laser powers, with its various applications, but also at high gas pressures p{sub 3} and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B{<=}30 mT and p{sub 3}=0.63-2.45 mbar. {sup 3}He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  17. Mechanical relaxation in glasses

    International Nuclear Information System (INIS)

    Hiki, Y.

    2004-01-01

    The basic properties of glasses and the characteristics of mechanical relaxation in glasses were briefly reviewed, and then our studies concerned were presented. Experimental methods adopted were viscosity, internal friction, ultrasonic attenuation, and Brillouin scattering measurements. The specimens used were several kinds of inorganic, organic, and metallic glasses. The measurements were mainly carried out from the room temperature up to the glass transition temperature, and the relaxation time was determined as a function of temperature. The 'double relaxation' composed of two Arrhenius-type relaxations was observed in many materials. In both relaxations, the 'compensation effect' showing a correlation of the pre-exponential factor and the activation energy was observed. These results were explained by considering the 'complex relaxation' due to cooperative motions of atoms or group of atoms. Values of activation energy near the glass transition determined by the various experimental methods were compared with each other

  18. Restricted lithium ion dynamics in PEO-based block copolymer electrolytes measured by high-field nuclear magnetic resonance relaxation

    Science.gov (United States)

    Huynh, Tan Vu; Messinger, Robert J.; Sarou-Kanian, Vincent; Fayon, Franck; Bouchet, Renaud; Deschamps, Michaël

    2017-10-01

    The intrinsic ionic conductivity of polyethylene oxide (PEO)-based block copolymer electrolytes is often assumed to be identical to the conductivity of the PEO homopolymer. Here, we use high-field 7Li nuclear magnetic resonance (NMR) relaxation and pulsed-field-gradient (PFG) NMR diffusion measurements to probe lithium ion dynamics over nanosecond and millisecond time scales in PEO and polystyrene (PS)-b-PEO-b-PS electrolytes containing the lithium salt LiTFSI. Variable-temperature longitudinal (T1) and transverse (T2) 7Li NMR relaxation rates were acquired at three magnetic field strengths and quantitatively analyzed for the first time at such fields, enabling us to distinguish two characteristic time scales that describe fluctuations of the 7Li nuclear electric quadrupolar interaction. Fast lithium motions [up to O (ns)] are essentially identical between the two polymer electrolytes, including sub-nanosecond vibrations and local fluctuations of the coordination polyhedra between lithium and nearby oxygen atoms. However, lithium dynamics over longer time scales [O (10 ns) and greater] are slower in the block copolymer compared to the homopolymer, as manifested experimentally by their different transverse 7Li NMR relaxation rates. Restricted dynamics and altered thermodynamic behavior of PEO chains anchored near PS domains likely explain these results.

  19. Application of potential relaxation transient measurements to corrosion of steel in concrete

    International Nuclear Information System (INIS)

    Benjamin, S.E.; Skyes, J.M.

    1993-01-01

    Corrosion of steel in concrete is an electrochemical process that involves the process occurring at the interface and also in the bulk diffusion of species. This paper present studies on corrosion of Swedish Iron in concrete utilizing potential relaxation transients. This rapid new D.C. technique (developed at Oxford University, U.K.) analyzes the decay in terms of different resistor (R) - capacitor(c) combinations, thus identifying the individual processes as their time constants(tau). The resistance of the concrete is also separated. The merits and demerits of the technique are discussed. (author)

  20. Muon spin relaxation measurements of spin-correlation decay in spin-glass AgMn

    Energy Technology Data Exchange (ETDEWEB)

    Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E. (Los Alamos National Lab., NM (USA)); MacLaughlin, D.E.; Gupta, L.C. (California Univ., Riverside (USA))

    1984-01-01

    The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin glass temperature in AgMn is found to obey an algebraic form given by (H)sup(..gamma..-1), with ..gamma.. = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as tsup(-..gamma..), in agreement with mean field theories of spin-glass dynamics which yield ..gamma..

  1. Muon spin relaxation measurements of spin-correlation decay in spin-glass AgMn

    International Nuclear Information System (INIS)

    Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Gupta, L.C.

    1984-01-01

    The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin glass temperature in AgMn is found to obey an algebraic form given by (H)sup(γ-1), with γ = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as tsup(-γ), in agreement with mean field theories of spin-glass dynamics which yield γ < approx. 0.5. Near the glass temperature the agreement between the data and theory is not as good. (Auth.)

  2. Increasing the sensitivity of NMR diffusion measurements by paramagnetic longitudinal relaxation enhancement, with application to ribosome–nascent chain complexes

    International Nuclear Information System (INIS)

    Chan, Sammy H. S.; Waudby, Christopher A.; Cassaignau, Anaïs M. E.; Cabrita, Lisa D.; Christodoulou, John

    2015-01-01

    The translational diffusion of macromolecules can be examined non-invasively by stimulated echo (STE) NMR experiments to accurately determine their molecular sizes. These measurements can be important probes of intermolecular interactions and protein folding and unfolding, and are crucial in monitoring the integrity of large macromolecular assemblies such as ribosome–nascent chain complexes (RNCs). However, NMR studies of these complexes can be severely constrained by their slow tumbling, low solubility (with maximum concentrations of up to 10 μM), and short lifetimes resulting in weak signal, and therefore continuing improvements in experimental sensitivity are essential. Here we explore the use of the paramagnetic longitudinal relaxation enhancement (PLRE) agent NiDO2A on the sensitivity of 15 N XSTE and SORDID heteronuclear STE experiments, which can be used to monitor the integrity of these unstable complexes. We exploit the dependence of the PLRE effect on the gyromagnetic ratio and electronic relaxation time to accelerate recovery of 1 H magnetization without adversely affecting storage on N z during diffusion delays or introducing significant transverse relaxation line broadening. By applying the longitudinal relaxation-optimized SORDID pulse sequence together with NiDO2A to 70S Escherichia coli ribosomes and RNCs, NMR diffusion sensitivity enhancements of up to 4.5-fold relative to XSTE are achieved, alongside ∼1.9-fold improvements in two-dimensional NMR sensitivity, without compromising the sample integrity. We anticipate these results will significantly advance the use of NMR to probe dynamic regions of ribosomes and other large, unstable macromolecular assemblies.Graphical Abstract

  3. A Comparison of Paraprofessionally Trained and Self-Instructed Relaxation Training for the Reduction in Frequency of Tension Headaches.

    Science.gov (United States)

    Hartman, Bruce W.; Utz, Patrick W.

    Previous research has demonstrated the effectiveness of using paraprofessional trainers in teaching students with tension headaches to relax, thus reducing the frequency of their headaches. A technique for automated self-instructed relaxation training was compared to a paraprofessionally trained group and a no-treatment control group over a 3-week…

  4. A comparison of methods for calculating NMR cross-relaxation rates (NOESY and ROESY intensities) in small peptides

    NARCIS (Netherlands)

    Feenstra, K Anton; Peter, Christine; Scheek, Ruud M; van Gunsteren, Wilfred F; Mark, Alan E

    Three methods for calculating nuclear magnetic resonance cross-relaxation rates from molecular dynamics simulations of small flexible molecules have been compared in terms of their ability to reproduce relaxation data obtained experimentally and to produce consistent descriptions of the system. The

  5. Surface-NMR measurements of the longitudinal relaxation time T1 in a homogeneous sandy aquifer in Skive, Denmark

    Science.gov (United States)

    Walbrecker, J.; Behroozmand, A.

    2011-12-01

    Efficient groundwater management requires reliable means of characterizing shallow groundwater aquifers. One key parameter in this respect is hydraulic conductivity. Surface nuclear magnetic resonance (NMR) is a geophysical exploration technique that can potentially provide this type of information in a noninvasive, cost-effective way. The technique is based on measuring the precession of nuclear spins of protons in groundwater molecules. It involves large loop antennas deployed on Earth's surface to generate electromagnetic pulses tuned to specifically excite and detect groundwater proton spins. Naturally, the excited state of spins is transitory - once excited, spins relax back to their equilibrium state. This relaxation process is strongly influenced by the spin environment, which, in the case of groundwater, is defined by the aquifer. By employing empirical relations, changes in relaxation behavior can be used to identify changes in aquifer hydraulic conductivity, making the NMR relaxation signal a very important piece of information. Particularly, efforts are made to record the longitudinal relaxation parameter T1, because it is known from laboratory studies that it often reliably correlates with hydraulic conductivity, even in the presence of magnetic species. In surface NMR, T1 data are collected by recording the NMR signal amplitude following two sequential excitation pulses as a function of the delay time τ between the two pulses. In conventional acquisition, the two pulses have a mutual phase shift of π. Based on theoretical arguments it was recently shown that T1 times acquired according to this conventional surface-NMR scheme are systematically biased. It was proposed that the bias can be minimized by cycling the phase of the two pulses between π and zero in subsequent double-pulse experiments, and subtracting the resulting signal amplitudes (phase-cycled pseudosaturation recovery scheme, pcPSR). We present the first surface-NMR T1 data set recorded

  6. A comparison of goniophotometric measurement facilities

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Dam-Hansen, Carsten

    2016-01-01

    In this paper, we present the preliminary results of a comparison between widely different goniophotometric and goniospectroradiometric measurement facilities. The objective of the comparison is to increase consistency and clarify the capabilities among Danish test laboratories. The study will seek...... to find the degree of equivalence between the various facilities and methods. The collected data is compared by using a three-way variation of principal component analysis, which is well suited for modelling large sets of correlated data. This method drastically decreases the number of numerical values...

  7. In-situ grazing incidence X-ray diffraction measurements of relaxation in Fe/MgO/Fe epitaxial magnetic tunnel junctions during annealing

    Energy Technology Data Exchange (ETDEWEB)

    Eastwood, D.S. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Ali, M.; Hickey, B.J. [Department of Physics and Astronomy, University of Leeds, Leeds LS2 1JT (United Kingdom); Tanner, B.K., E-mail: b.k.tanner@dur.ac.uk [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

    2013-12-15

    The relaxation of Fe/MgO/Fe tunnel junctions grown epitaxially on (001) MgO substrates has been measured by in-situ grazing incidence in-plane X-ray diffraction during the thermal annealing cycle. We find that the Fe layers are fully relaxed and that there are no irreversible changes during annealing. The MgO tunnel barrier is initially strained towards the Fe but on annealing, relaxes and expands towards the bulk MgO value. The strain dispersion is reduced in the MgO by about 40% above 480 K post-annealing. There is no significant change in the “twist” mosaic. Our results indicate that the final annealing stage of device fabrication, crucial to attainment of high TMR, induces substantial strain relaxation at the MgO barrier/lower Fe electrode interface. - Highlights: • Lattice relaxation of Fe/MgO/Fe epitaxial magnetic tunnel junctions measured. • In-plane lattice parameter of Fe equal to bulk value; totally relaxed. • MgO barrier initially strained towards the Fe but relaxes on annealing. • Reduction in strain dispersion in the MgO barrier by 40% above about 470 K. • No change in the in-plane “twist” mosaic throughout the annealing cycle.

  8. In vivo measurements of the T1 relaxation processes in the bone marrow in patients with myelodysplastic syndrome. A magnetic resonance imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K.E.; Nielsen, H.; Thomsen, C.; Soerensen, P.G.; Karle, H.; Christoffersen, P.; Henriksen, O. (Hvidovre Hospital, Copenhagen (Denmark). Dept. of Magnetic Resonance; Hvidovre Hospital, Copenhagen (Denmark). Dept. of Hematology; Hvidovre Hospital, Copenhagen (Denmark). Dept. of Pathology)

    Nine patients with myelodysplastic syndrome (MDS) were examined with magnetic resonance imaging and in vivo T1 relaxation time measurements of the vertebral bone marrow in a 1.5 tesla whole body scanner. Two patients underwent transformation to acute myeloid leukemia and were evaluated at follow-up examinations. At the time of diagnosis the T1 relaxation times of the vertebral bone marrow were significantly prolonged compared with normal values. The T1 relaxation times of the vertebral bone marrow in patients with MDS showed significantly lower values compared with patients with acute leukemia and did not differ from patients with polycythemia vera. (orig.).

  9. Proton T2 relaxation effect of superparamagnetic iron oxide. Comparison between fast spin echo and conventional spin echo sequence

    International Nuclear Information System (INIS)

    Tanimoto, Akihiro; Satoh, Yoshinori; Higuchi, Nobuya; Izutsu, Mutsumu; Yuasa, Yuji; Hiramatsu, Kyoichi

    1995-01-01

    Superparamagnetic iron oxide (SPIO) particles have been known to show a great T 2 relaxation effect in the liver, which contributes to significant liver signal decrease and detection of hepatic neoplasms. Recently, fast spin echo (FSE) sequence with less scanning time than conventional spin echo (SE) sequence has been rapidly introduced in clinical MR imaging. To investigate whether SPIO would show decreased T 2 relaxation effect on FSE, we obtained T 2 relaxivity (R2) of SPIO in vitro and liver signal decrease caused by SPIO in vivo. SPIO showed 20% less R2 on Carr-Purcell-Meiboom-Gill (CPMG) sequence than on SE. Relative liver signal-to-noise ratio (SNR) decrease caused by SPIO was significantly smaller (p 2 relaxation effect on FSE than on SE. However, further studies will be required to assess the diagnostic capability of SPIO on FSE, in the detection of hepatic neoplasms. (author)

  10. An analysis of the NMR-CT image by the measurement of proton-relaxation times in tissue

    International Nuclear Information System (INIS)

    Naruse, Shoji; Horikawa, Yoshiharu; Tanaka, Chuzo; Hirakawa, Kimiyoshi; Nishikawa, Hiroyasu; Shimizu, Koji; Kiri, Motosada.

    1984-01-01

    NMR-CT images were analyzed by measuring the proton-relaxation times in tissues. The NMR-CT images were obtained in 10 normal volunteers and 16 patients with brain tumors with a prototype superconducting magnet (Shimadzu Corp., Japan) operating at 0.2 T and 0.375 T. A smooth T 1 relaxation curve was obtained in each part of the brain and the brain tumor by the use of the data of the NMR-CT image; consequently, the in vivo T 1 value was proved to be reliable. The in vivo T 1 value showed the specific value corresponding to each region of the normal brain in all cases. Cerebral gray matter normally had the longest T 1 value, followed by the medulla oblongata, the pons, and white matter. The T 1 value of each region of the brain varied to the same degree in proportion to the strength of the static magnetic field. The in vivo T 1 values of the brain tumor varied with the histological type. All were longer than any part of the brain parenchyma, being between 480 and 780 msec at 0.2 T. The prolongation of the T 1 value does not always correspond to the degree of the malignancy in a tumor. The in vitro T 1 and T 2 values were also prolonged in all tumors. Although the absolute value of T 1 did not coincide between the in vitro and in vivo data, the tendency of the prolongation was the same between them. This result indicated that the NMR-CT images could be analysed by the use of the data of the in vitro T 1 and T 2 values in the tumor tissues. It is important to analyse the NMR-CT image by both in vivo and in vitro examinations of the relaxation times. (J.P.N.)

  11. Comparison of pressure profiles of massive relaxed galaxy clusters using the Sunyaev-Zel'dovich and x-ray data

    International Nuclear Information System (INIS)

    Bonamente, Massimiliano; Hasler, Nicole; Bulbul, Esra; Landry, David; Carlstrom, John E; Culverhouse, Thomas L; Gralla, Megan; Greer, Christopher; Hennessy, Ryan; Leitch, Erik M; Plagge, Thomas; Pryke, Clem; Hawkins, David; Lamb, James W; Muchovej, Stephen; Joy, Marshall; Kolodziejczak, Jeffery; Marrone, Daniel P; Miller, Amber; Mroczkowski, Tony

    2012-01-01

    We present the Sunyaev-Zel'dovich (SZ) effect observations of a sample of 25 massive relaxed galaxy clusters observed with the Sunyaev-Zel'dovich array (SZA), an eight-element interferometer that is part of the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We performed an analysis of new SZA data and archival Chandra observations of this sample to investigate the integrated pressure—a proxy for cluster mass—determined from x-ray and SZ observations, two independent probes of the intra-cluster medium (ICM). This analysis makes use of a model for the ICM introduced by Bulbul (2010 Astrophys. J. 720 1038) which can be applied simultaneously to the SZ and x-ray data. With this model, we estimated the pressure profile for each cluster using a joint analysis of the SZ and x-ray data, and using the SZ data alone. We found that the integrated pressures measured from the x-ray and SZ data are consistent. This conclusion is in agreement with recent results obtained using WMAP and Planck data, confirming that SZ and x-ray observations of massive clusters detect the same amount of thermal pressure from the ICM. To test for possible biases introduced by our choice of model, we also fitted the SZ data using the universal pressure profile proposed by Arnaud (2010 Astron. Astrophys. 517 A92) and found consistency between the two models out to r 500 in the pressure profiles and integrated pressures. (paper)

  12. Measurement of N and C diffusion in Sm{sub 2}Fe{sub 17} by magnetic relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Mommer, N.; Hirscher, M.; Gerlach, M.; Van Lier, J.; Kronmueller, H. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany); Kubis, M.; Mueller, K.-H. [Institut fuer Festkoerper und Werkstofforschung, Institut fuer Metallische Werkstoffe, D-01171 Dresden (Germany)

    1998-10-02

    Magnetic after-effect (MAE) measurements of nitrided and carburized Sm{sub 2}Fe{sub 17} compounds were performed in the temperature range of 140 K to 480 K. Both nitrided and carburized compounds show relaxation maxima at 285 and 300 K, respectively, which are absent in pure Sm{sub 2}Fe{sub 17} compounds. Therefore, these relaxation maxima are attributed to jumps of interstitially dissolved nitrogen or carbon atoms. Numerical evaluation yielded an activation enthalpy Q{sup N} (0.84{+-}0.05) eV and a pre-exponential factor {tau}{sub 0}{sup N}=3.10{sup -15{+-}1} s for the short-range diffusion of N atoms. The corresponding values for the carbon diffusion are Q{sup C}=(0.91{+-}0.05) eV and {tau}{sub 0}{sup C}=1.10{sup -15{+-}1} s. The carbon and nitrogen content of the samples was determined from the increase in mass during nitrogenation or carburization to Sm{sub 2}Fe{sub 17}N{sub 1.2} and Sm{sub 2}Fe{sub 17}C{sub 2.6}. (orig.) 18 refs.

  13. Measurement of in-plane magnetic relaxation in RE-123 coated conductors by use of scanning Hall probe microscopy

    International Nuclear Information System (INIS)

    Shiohara, K.; Higashikawa, K.; Inoue, M.; Kiss, T.; Iijima, Y.; Saitoh, T.; Yoshizumi, M.; Izumi, T.

    2013-01-01

    Highlights: ► We have investigated electric field criterion of in-plane critical current density. ► We could measure magnetic relaxation in a remanent state. ► The SHPM results show good agreement with the measurements by the 4-probe method. -- Abstract: We have investigated electric field criterion of in-plane critical current density in a coated conductor characterized by scanning Hall-probe microscopy (SHPM). From remanent field distribution and its relaxation measurements, we could obtain critical current distribution and induced electric field simultaneously by considering the Biot-Savart law and the Faraday’s law, respectively. These results lead us to evaluate a distribution of local critical current density and the corresponding criterion of electric field. As a result, it was found that the electric field criterion for the SHPM analysis was several orders lower than that used in the conventional 4-probe resistive method. However, the data point obtained by the SHPM shows good agreement with E–J curve analytically extended from the measurements by the 4-probe method. This means that we could characterize in-plane distribution of critical current density in a coated conductor at an electric field criterion quantitatively by this method in a nondestructive manner. These findings will be very important information since the uniformity of local critical current density in a coated conductor at extremely low electric fields is a key issue (1) especially for DC applications, (2) for quality control of coated conductors, and (3) for the standardization of the characterization of critical current among different methods

  14. Zeeman relaxation of MnH (X7Σ+) in collisions with 3He: Mechanism and comparison with experiment

    International Nuclear Information System (INIS)

    Turpin, F.; Stoecklin, T.; Halvick, Ph.

    2011-01-01

    We present a theoretical study of the Zeeman relaxation of the magnetically trappable lowest field seeking state of MnH ( 7 Σ) in collisions with 3 He. We analyze the collisional Zeeman transition mechanism as a function of the final diatomic state and its variation as a function of an applied magnetic field. We show that as a result of this mechanism the levels with ΔM j >2 give negligible contributions to the Zeemam relaxation cross section. We also compare our results to the experimental cross sections obtained from the buffer-gas cooling and magnetic trapping of this molecule and investigate the dependence of the Zeeman relaxation cross section on the accuracy of the three-body interaction at ultralow energies.

  15. Zeeman relaxation of MnH (X7Σ+) in collisions with He3: Mechanism and comparison with experiment

    Science.gov (United States)

    Turpin, F.; Stoecklin, T.; Halvick, Ph.

    2011-03-01

    We present a theoretical study of the Zeeman relaxation of the magnetically trappable lowest field seeking state of MnH (7Σ) in collisions with He3. We analyze the collisional Zeeman transition mechanism as a function of the final diatomic state and its variation as a function of an applied magnetic field. We show that as a result of this mechanism the levels with ΔMj>2 give negligible contributions to the Zeemam relaxation cross section. We also compare our results to the experimental cross sections obtained from the buffer-gas cooling and magnetic trapping of this molecule and investigate the dependence of the Zeeman relaxation cross section on the accuracy of the three-body interaction at ultralow energies.

  16. Optical Transient-Grating Measurements of Spin Diffusion and Relaxation in a Two-Dimensional Electron Gas

    International Nuclear Information System (INIS)

    Weber, Christopher P.

    2005-01-01

    Spin diffusion in n-GaAs quantum wells, as measured by our optical transient-grating technique, is strongly suppressed relative to that of charge. Over a broad range of temperatures and dopings, the suppression of Ds relative to Dc agrees quantitatively with the prediction of ''spin Coulomb dra'' theory, which takes into account the exchange of spin in electron-electron collisions. Moreover, the spin-diffusion length, Ls, is a nearly constant 1 micrometer over the same range of T and n, despite Ds's varying by nearly two orders of magnitude. This constancy supports the D'yakonov-Perel'-Kachorovskii model of spin relaxation through interrupted precessional dephasing in the spin-orbit field

  17. Measurement of the relaxation rate of the magnetization in Mn12O12-acetate using proton NMR echo

    Science.gov (United States)

    Jang; Lascialfari; Borsa; Gatteschi

    2000-03-27

    We present a novel method to measure the relaxation rate W of the magnetization of Mn 12O (12)-acetate (Mn12) magnetic molecular cluster in its S = 10 ground state at low T. It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions.

  18. Measurement of the Relaxation Rate of the Magnetization in Mn12O12 -Acetate Using Proton NMR Echo

    International Nuclear Information System (INIS)

    Jang, Z. H.; Lascialfari, A.; Borsa, F.; Gatteschi, D.

    2000-01-01

    We present a novel method to measure the relaxation rate W of the magnetization of Mn 12 O 12 -acetate (Mn12) magnetic molecular cluster in its S=10 ground state at low T . It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions. (c) 2000 The American Physical Society

  19. Optical Transient-Grating Measurements of Spin Diffusion andRelaxation in a Two-Dimensional Electron Gas

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Christopher Phillip [Univ. of California, Berkeley, CA (United States)

    2005-01-01

    Spin diffusion in n-GaAs quantum wells, as measured by our optical transient-grating technique, is strongly suppressed relative to that of charge. Over a broad range of temperatures and dopings, the suppression of Ds relative to Dc agrees quantitatively with the prediction of ''spin Coulomb dra'' theory, which takes into account the exchange of spin in electron-electron collisions. Moreover, the spin-diffusion length, Ls, is a nearly constant 1 micrometer over the same range of T and n, despite Ds's varying by nearly two orders of magnitude. This constancy supports the D'yakonov-Perel'-Kachorovskii model of spin relaxation through interrupted precessional dephasing in the spin-orbit field.

  20. Carbonyl carbon transverse relaxation dispersion measurements and ms-{mu}s timescale motion in a protein hydrogen bond network

    Energy Technology Data Exchange (ETDEWEB)

    Ishima, Rieko [National Institute of Dental and Craniofacial Research, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Molecular Structural Biology Unit (United States); Baber, James; Louis, John M.; Torchia, Dennis A. [National Institute of Dental and Craniofacial Research, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Molecular Structural Biology Unit (United States)

    2004-06-15

    A constant-time, Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation, R{sub 2}, dispersion experiment for carbonyl carbons was designed and executed to detect {mu}s-ms time-scale dynamics of protein backbone carbonyl sites. Because of the large (ca. 55 Hz) C{sub {alpha}}-C' J-coupling, the carbonyl signal intensity is strongly modulated as the spacing between CPMG pulses is varied, in uniformly {sup 13}C enriched proteins, unless care is taken to minimize the perturbation of the C{sub {alpha}} magnetization by the CPMG pulses. CPMG pulse trains consisting of either a band-selective pulse, such as RE-BURP, or rectangular (with an excitation null in the C{sub {alpha}} region of the spectrum) pulses were employed in order to minimize C' signal modulation by C{sub {alpha}}-C' J-coupling. The performance of these types of CPMG refocusing pulses was assessed by computer simulation, and by comparing dispersion profiles measured for (1) uniformly [{sup 13}C,{sup 15}N, {sup 2}H] ({sup 2}H at non-labile hydrogen sites) labeled, and (2) uniformly {sup 15}N/selectively-{sup 13}C' labeled samples of HIV-1 protease bound to a potent inhibitor, DMP323. In addition, because the uniformly {sup 13}C/{sup 15}N/{sup 2}H labeled sample was well suited to measure {sup 15}N and {sup 1}H R{sub 2} dispersion as well as {sup 13}C' dispersion, conformational exchange in the inter subunit {beta}-sheet hydrogen-bond network of the inhibitor-bound protease was elucidated using relaxation dispersion data of all three types of nuclei.

  1. Carbonyl carbon transverse relaxation dispersion measurements and ms-μs timescale motion in a protein hydrogen bond network

    International Nuclear Information System (INIS)

    Ishima, Rieko; Baber, James; Louis, John M.; Torchia, Dennis A.

    2004-01-01

    A constant-time, Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation, R 2 , dispersion experiment for carbonyl carbons was designed and executed to detect μs-ms time-scale dynamics of protein backbone carbonyl sites. Because of the large (ca. 55 Hz) C α -C' J-coupling, the carbonyl signal intensity is strongly modulated as the spacing between CPMG pulses is varied, in uniformly 13 C enriched proteins, unless care is taken to minimize the perturbation of the C α magnetization by the CPMG pulses. CPMG pulse trains consisting of either a band-selective pulse, such as RE-BURP, or rectangular (with an excitation null in the C α region of the spectrum) pulses were employed in order to minimize C' signal modulation by C α -C' J-coupling. The performance of these types of CPMG refocusing pulses was assessed by computer simulation, and by comparing dispersion profiles measured for (1) uniformly [ 13 C, 15 N, 2 H] ( 2 H at non-labile hydrogen sites) labeled, and (2) uniformly 15 N/selectively- 13 C' labeled samples of HIV-1 protease bound to a potent inhibitor, DMP323. In addition, because the uniformly 13 C/ 15 N/ 2 H labeled sample was well suited to measure 15 N and 1 H R 2 dispersion as well as 13 C' dispersion, conformational exchange in the inter subunit β-sheet hydrogen-bond network of the inhibitor-bound protease was elucidated using relaxation dispersion data of all three types of nuclei

  2. State resolved vibrational relaxation modeling for strongly nonequilibrium flows

    Science.gov (United States)

    Boyd, Iain D.; Josyula, Eswar

    2011-05-01

    Vibrational relaxation is an important physical process in hypersonic flows. Activation of the vibrational mode affects the fundamental thermodynamic properties and finite rate relaxation can reduce the degree of dissociation of a gas. Low fidelity models of vibrational activation employ a relaxation time to capture the process at a macroscopic level. High fidelity, state-resolved models have been developed for use in continuum gas dynamics simulations based on computational fluid dynamics (CFD). By comparison, such models are not as common for use with the direct simulation Monte Carlo (DSMC) method. In this study, a high fidelity, state-resolved vibrational relaxation model is developed for the DSMC technique. The model is based on the forced harmonic oscillator approach in which multi-quantum transitions may become dominant at high temperature. Results obtained for integrated rate coefficients from the DSMC model are consistent with the corresponding CFD model. Comparison of relaxation results obtained with the high-fidelity DSMC model shows significantly less excitation of upper vibrational levels in comparison to the standard, lower fidelity DSMC vibrational relaxation model. Application of the new DSMC model to a Mach 7 normal shock wave in carbon monoxide provides better agreement with experimental measurements than the standard DSMC relaxation model.

  3. Intraindividual comparison of T1 relaxation times after gadobutrol and Gd-DTPA administration for cardiac late enhancement imaging

    Energy Technology Data Exchange (ETDEWEB)

    Doeblin, Patrick, E-mail: Patrick.doeblin@charite.de [Department of Cardiology, Charité – Universitätsmedizin Berlin, Charité Campus Benjamin Franklin, Berlin (Germany); Schilling, Rene, E-mail: rene.schilling@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Wagner, Moritz, E-mail: moritz.wagner@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Luhur, Reny, E-mail: renyluhur@yahoo.com [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Huppertz, Alexander, E-mail: alexander.huppertz@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Imaging Science Institute, Charité, Berlin (Germany); Hamm, Bernd, E-mail: bernd.hamm@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Taupitz, Matthias, E-mail: matthias.taupitz@harite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); and others

    2014-04-15

    Purpose: To evaluate T1-relaxation times of chronic myocardial infarction (CMI) using gadobutrol and gadopentetate dimeglumine (Gd-DTPA) over time and to determine the optimal imaging window for late enhancement imaging with both contrast agents. Material and methods: Twelve patients with CMI were prospectively included and examined on a 1.5 T magnetic resonance (MR) system using relaxivity-adjusted doses of gadobutrol (0.15 mmol/kg) and Gd-DTPA (0.2 mmol/kg) in random order. T1-relaxation times of remote myocardium (RM), infarcted myocardium (IM), and left ventricular cavity (LVC) were assessed from short-axis TI scout imaging using the Look–Locker approach and compared intraindividually using a Wilcoxon paired signed-rank test (α < 0.05). Results: Within 3 min of contrast agent administration (CA), IM showed significantly lower T1-relaxation times than RM with both contrast agents, indicating beginning cardiac late enhancement. Differences between gadobutrol and Gd-DTPA in T1-relaxation times of IM and RM were statistically not significant through all time points. However, gadobutrol led to significantly higher T1-relaxation times of LVC than Gd-DTPA from 6 to 9 min (220 ± 15 ms vs. 195 ± 30 ms p < 0.01) onwards, resulting in a significantly greater ΔT1 of IM to LVC at 9–12 min (−20 ± 35 ms vs. 0 ± 35 ms, p < 0.05) and 12–15 min (−25 ± 45 ms vs. −10 ± 60 ms, p < 0.05). Using Gd-DTPA, comparable ΔT1 values were reached only after 25–35 min. Conclusion: This study indicates good delineation of IM to RM with both contrast agents as early as 3 min after administration. However, we found significant differences in T1 relaxation times with greater ΔT1 IM–LVC using 0.15 mmol/kg gadobutrol compared to 0.20 mmol/kg Gd-DTPA after 9–15 min post-CA suggesting earlier differentiability of IM and LVC using gadobutrol.

  4. Interpreting equilibrium-conductivity and conductivity-relaxation measurements to establish thermodynamic and transport properties for multiple charged defect conducting ceramics.

    Science.gov (United States)

    Zhu, Huayang; Ricote, Sandrine; Coors, W Grover; Kee, Robert J

    2015-01-01

    A model-based interpretation of measured equilibrium conductivity and conductivity relaxation is developed to establish thermodynamic, transport, and kinetics parameters for multiple charged defect conducting (MCDC) ceramic materials. The present study focuses on 10% yttrium-doped barium zirconate (BZY10). In principle, using the Nernst-Einstein relationship, equilibrium conductivity measurements are sufficient to establish thermodynamic and transport properties. However, in practice it is difficult to establish unique sets of properties using equilibrium conductivity alone. Combining equilibrium and conductivity-relaxation measurements serves to significantly improve the quantitative fidelity of the derived material properties. The models are developed using a Nernst-Planck-Poisson (NPP) formulation, which enables the quantitative representation of conductivity relaxations caused by very large changes in oxygen partial pressure.

  5. Relaxed Bell inequalities and Kochen-Specker theorems

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Michael J. W. [Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2011-08-15

    The combination of various physically plausible properties, such as no signaling, determinism, and experimental free will, is known to be incompatible with quantum correlations. Hence, these properties must be individually or jointly relaxed in any model of such correlations. The necessary degrees of relaxation are quantified here via natural distance and information-theoretic measures. This allows quantitative comparisons between different models in terms of the resources, such as the number of bits of randomness, communication, and/or correlation, that they require. For example, measurement dependence is a relatively strong resource for modeling singlet-state correlations, with only 1/15 of one bit of correlation required between measurement settings and the underlying variable. It is shown how various ''relaxed'' Bell inequalities may be obtained, which precisely specify the complementary degrees of relaxation required to model any given violation of a standard Bell inequality. The robustness of a class of Kochen-Specker theorems, to relaxation of measurement independence, is also investigated. It is shown that a theorem of Mermin remains valid unless measurement independence is relaxed by 1/3. The Conway-Kochen ''free will'' theorem and a result of Hardy are less robust, failing if measurement independence is relaxed by only 6.5% and 4.5%, respectively. An appendix shows that existence of an outcome-independent model is equivalent to existence of a deterministic model.

  6. Arousal vs. Relaxation: A Comparison of the Neurophysiological and Cognitive Correlates of Vajrayana and Theravada Meditative Practices

    Science.gov (United States)

    Amihai, Ido; Kozhevnikov, Maria

    2014-01-01

    Based on evidence of parasympathetic activation, early studies defined meditation as a relaxation response. Later research attempted to categorize meditation as either involving focused or distributed attentional systems. Neither of these hypotheses received strong empirical support, and most of the studies investigated Theravada style meditative practices. In this study, we compared neurophysiological (EEG, EKG) and cognitive correlates of meditative practices that are thought to utilize either focused or distributed attention, from both Theravada and Vajrayana traditions. The results of Study 1 show that both focused (Shamatha) and distributed (Vipassana) attention meditations of the Theravada tradition produced enhanced parasympathetic activation indicative of a relaxation response. In contrast, both focused (Deity) and distributed (Rig-pa) meditations of the Vajrayana tradition produced sympathetic activation, indicative of arousal. Additionally, the results of Study 2 demonstrated an immediate dramatic increase in performance on cognitive tasks following only Vajrayana styles of meditation, indicating enhanced phasic alertness due to arousal. Furthermore, our EEG results showed qualitatively different patterns of activation between Theravada and Vajrayana meditations, albeit highly similar activity between meditations within the same tradition. In conclusion, consistent with Tibetan scriptures that described Shamatha and Vipassana techniques as those that calm and relax the mind, and Vajrayana techniques as those that require ‘an awake quality’ of the mind, we show that Theravada and Vajrayana meditations are based on different neurophysiological mechanisms, which give rise to either a relaxation or arousal response. Hence, it may be more appropriate to categorize meditations in terms of relaxation vs. arousal, whereas classification methods that rely on the focused vs. distributed attention dichotomy may need to be reexamined. PMID:25051268

  7. Arousal vs. relaxation: a comparison of the neurophysiological and cognitive correlates of Vajrayana and Theravada meditative practices.

    Directory of Open Access Journals (Sweden)

    Ido Amihai

    Full Text Available Based on evidence of parasympathetic activation, early studies defined meditation as a relaxation response. Later research attempted to categorize meditation as either involving focused or distributed attentional systems. Neither of these hypotheses received strong empirical support, and most of the studies investigated Theravada style meditative practices. In this study, we compared neurophysiological (EEG, EKG and cognitive correlates of meditative practices that are thought to utilize either focused or distributed attention, from both Theravada and Vajrayana traditions. The results of Study 1 show that both focused (Shamatha and distributed (Vipassana attention meditations of the Theravada tradition produced enhanced parasympathetic activation indicative of a relaxation response. In contrast, both focused (Deity and distributed (Rig-pa meditations of the Vajrayana tradition produced sympathetic activation, indicative of arousal. Additionally, the results of Study 2 demonstrated an immediate dramatic increase in performance on cognitive tasks following only Vajrayana styles of meditation, indicating enhanced phasic alertness due to arousal. Furthermore, our EEG results showed qualitatively different patterns of activation between Theravada and Vajrayana meditations, albeit highly similar activity between meditations within the same tradition. In conclusion, consistent with Tibetan scriptures that described Shamatha and Vipassana techniques as those that calm and relax the mind, and Vajrayana techniques as those that require 'an awake quality' of the mind, we show that Theravada and Vajrayana meditations are based on different neurophysiological mechanisms, which give rise to either a relaxation or arousal response. Hence, it may be more appropriate to categorize meditations in terms of relaxation vs. arousal, whereas classification methods that rely on the focused vs. distributed attention dichotomy may need to be reexamined.

  8. A study on magnetic relaxation times of various organs and body fluids using superconducting magnetic resonance imaging system part I: measurement of relative signal intensity and T2 relaxation time in various portions of brain and cerebrospinal fluid

    International Nuclear Information System (INIS)

    Chang, Kee Hyun; Lee, Ghi Jai; Han, Moon Hee; Kim, Jae Ho; Han, Man Chang; Kim, Chu Wan

    1988-01-01

    This study was undertake to determine if routine clinical magnetic resonance imaging sequences using only two different repetition times (TRs) and with only two sequential echo times (TEs) can be used to measure reproducible relative signal intensity and T2 relaxation time for normal brain tissues and cerebrospinal fluid using a 2.0T superconducting system. In 47 patients 6 different anatomic sites were measured. For each anatomic location, the mean and standard deviation of these values were determined. On T1-weighted (SE 500msec/30msec) images, in globus pallidus and thalamus, of the CSF, cortical gray matter and retrobulbar fat tissue varied more, with a standard deviation of 11-14% on T1-weighted images. On T2-weighted (SE 3000msec/30msec and 3000msec/80msec) images, the relative signal intensity of all anatomic regions varied more than on T1-weighted images. The standard deviation of T2 relaxation times also varied from 10% (fat tissue) to 18% (CSF). These variations might be due to partial volume averaging, signal alteration of CSF secondary to CSF pulsatile motion, etc. Knowing that relative signal intensity and T2 relaxation times calculated from routine imaging sequences are reproducible in only limited area, these normal ranges can be used to investigate changes occurring in disease states of the limited regions.

  9. Real T1 relaxation time measurement and diurnal variation analysis of intervertebral discs in a healthy population of 50 volunteers

    International Nuclear Information System (INIS)

    Galley, J.; Maestretti, G.; Koch, G.; Hoogewoud, H-M.

    2017-01-01

    Purpose: To measure the real T1 relaxation time of the lumbar intervertebral discs in a young and healthy population, using different inversion recovery times, and assess diurnal variation. Material and methods: Intervertebral discs from D12 to S1 of 50 healthy volunteers from 18 to 25 years old were evaluated twice the same day, in the morning and in the late afternoon. Dedicated MRI sequences with different inversion recovery times (from 100 to 2500 ms) were used to calculate the real T1 relaxation time. Three regions of interest (ROIs) were defined in each disc, the middle representing the nucleus pulposus (NP) and the outer parts the annulus fibrosus (AF) anterior and posterior. Diurnal variation and differences between each disc level were analyzed. Results: T1 mean values in the NP were 1142 ± 12 ms in the morning and 1085 ± 13 ms in the afternoon, showing a highly significant decrease of 57 ms (p < 0.001). A highly significant difference between the levels of the spine was found. The mean T1 of the anterior part of the AF was 577 ± 9 ms in the morning and 554 ± 8 ms in the afternoon. For the posterior part, the mean values were 633 ± 8 ms in the morning and 581 ± 7 ms in the evening. It shows a highly significant decrease of 23 ms for the anterior part and 51 ms for the posterior part (all p < 0.001). Conclusion: T1 mapping is a promising method of intervertebral disc evaluation. Significant diurnal variation and difference between levels of the lumbar spine were demonstrated. A potential use for longitudinal study in post-operative follow up or sport medicine needs to be evaluated.

  10. Real T1 relaxation time measurement and diurnal variation analysis of intervertebral discs in a healthy population of 50 volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Galley, J., E-mail: galleyjulien@gmail.com [Department of Radiology, HFR Fribourg, Hôpital Cantonal (Switzerland); Maestretti, G. [Department of Orthopedic Surgery, HFR Fribourg, Hôpital Cantonal (Switzerland); Koch, G.; Hoogewoud, H-M. [Department of Radiology, HFR Fribourg, Hôpital Cantonal (Switzerland)

    2017-02-15

    Purpose: To measure the real T1 relaxation time of the lumbar intervertebral discs in a young and healthy population, using different inversion recovery times, and assess diurnal variation. Material and methods: Intervertebral discs from D12 to S1 of 50 healthy volunteers from 18 to 25 years old were evaluated twice the same day, in the morning and in the late afternoon. Dedicated MRI sequences with different inversion recovery times (from 100 to 2500 ms) were used to calculate the real T1 relaxation time. Three regions of interest (ROIs) were defined in each disc, the middle representing the nucleus pulposus (NP) and the outer parts the annulus fibrosus (AF) anterior and posterior. Diurnal variation and differences between each disc level were analyzed. Results: T1 mean values in the NP were 1142 ± 12 ms in the morning and 1085 ± 13 ms in the afternoon, showing a highly significant decrease of 57 ms (p < 0.001). A highly significant difference between the levels of the spine was found. The mean T1 of the anterior part of the AF was 577 ± 9 ms in the morning and 554 ± 8 ms in the afternoon. For the posterior part, the mean values were 633 ± 8 ms in the morning and 581 ± 7 ms in the evening. It shows a highly significant decrease of 23 ms for the anterior part and 51 ms for the posterior part (all p < 0.001). Conclusion: T1 mapping is a promising method of intervertebral disc evaluation. Significant diurnal variation and difference between levels of the lumbar spine were demonstrated. A potential use for longitudinal study in post-operative follow up or sport medicine needs to be evaluated.

  11. Comparison of the Magnetic Anisotropy and Spin Relaxation Phenomenon of Dinuclear Terbium(III) Phthalocyaninato Single-Molecule Magnets Using the Geometric Spin Arrangement.

    Science.gov (United States)

    Morita, Takaumi; Damjanović, Marko; Katoh, Keiichi; Kitagawa, Yasutaka; Yasuda, Nobuhiro; Lan, Yanhua; Wernsdorfer, Wolfgang; Breedlove, Brian K; Enders, Markus; Yamashita, Masahiro

    2018-02-28

    Herein we report the synthesis and characterization of a dinuclear Tb III single-molecule magnet (SMM) with two [TbPc 2 ] 0 units connected via a fused-phthalocyaninato ligand. The stable and robust complex [(obPc)Tb(Fused-Pc)Tb(obPc)] (1) was characterized by using synchrotron radiation measurements and other spectroscopic techniques (ESI-MS, FT-IR, UV). The magnetic couplings between the Tb III ions and the two π radicals present in 1 were explored by means of density functional theory (DFT). Direct and alternating current magnetic susceptibility measurements were conducted on magnetically diluted and nondiluted samples of 1, indicating this compound to be an SMM with improved properties compared to those of the well-known [TbPc 2 ] -/0/+ and the axially symmetric dinuclear Tb III phthalocyaninato triple-decker complex (Tb 2 (obPc) 3 ). Assuming that the probability of quantum tunneling of the magnetization (QTM) occurring in one TbPc 2 unit is P QTM , the probability of QTM simultaneously occurring in 1 is P QTM 2 , meaning that QTM is effectively suppressed. Furthermore, nondiluted samples of 1 underwent slow magnetic relaxation times (τ ≈ 1000 s at 0.1 K), and the blocking temperature (T B ) was determined to be ca. 16 K with an energy barrier for spin reversal (U eff ) of 588 cm -1 (847 K) due to D 4d geometry and weak inter- and intramolecular magnetic interactions as an exchange bias (H bias ), reducing QTM. Four hyperfine steps were observed by micro-SQUID measurement. Furthermore, solution NMR measurements (one-dimensional, two-dimensional, and dynamic) were done on 1, which led to the determination of the high rotation barrier (83 ± 10 kJ/mol) of the obPc ligand. A comparison with previously reported Tb III triple-decker compounds shows that ambient temperature NMR measurements can indicate improvements in the design of coordination environments for SMMs. A large U eff causes strong uniaxial magnetic anisotropy in 1, leading to a χ ax value (1.39

  12. In vivo measurements of T1 relaxation times of 31P-metabolites in human skeletal muscle

    DEFF Research Database (Denmark)

    Thomsen, C; Jensen, K E; Henriksen, O

    1989-01-01

    The T1 relaxation times were estimated for 31P-metabolites in human skeletal muscle. Five healthy volunteers were examined in a 1.5 Tesla wholebody imaging system using an inversion recovery pulse sequence. The calculated T1 relaxation times ranged from 5.517 sec for phosphocreatine to 3.603 sec...

  13. Description and Results: Antenna Measurement Facility Comparisons [Measurements Corner

    DEFF Research Database (Denmark)

    Alberica Saporetti, Maria; Foged, Lars; Sierra Castañer, Manuel

    2017-01-01

    In recent years, formalized facility comparison activities have become important for the documentation and validation of laboratory proficiency and competence and mandatory for achieving accreditation such as that of the International Organization for Standardization (ISO) 17025 or similar...... for Antennas (VISTA) IC1102, including still ongoing campaigns [3]-[5]. Results of these activities have led to improvements in antenna measurement procedures and protocols in facilities and standards [6], [7]. Due to the direct benefits available to the participants, the activities have been very successful...

  14. Measurement of P-31 MR relaxation times and concentrations in human brain and brain tumors

    International Nuclear Information System (INIS)

    Roth, K.; Naruse, S.; Hubesch, B.; Gober, I.; Lawry, T.; Boska, M.; Matson, G.B.; Weiner, M.W.

    1987-01-01

    Measurements of high-energy phosphates and pH were made in human brain and brain tumors using P-31 MR imaging. Using a Philips Gyroscan 1.5-T MRMRS, MR images were used to select a cuboidal volume of interest and P-31 MR spectra were obtained from that volume using the ISIS technique. An external quantitation standard was used. T 1 s were measured by inversion recovery. Quantitative values for metabolites were calculated using B 1 field plot of the head coil. The results for normal brain phosphates are as follows; adenosine triphosphate, 2.2 mM; phosphocreatin, 5.3 mM; inorganic phosphate, 1.6 mM. Preliminary studies with human brain tumors show a decrease of all phosphate compounds. These experiments are the first to quantitate metabolites in human brain

  15. Generalized W1;1-Young Measures and Relaxation of Problems with Linear Growth

    Czech Academy of Sciences Publication Activity Database

    Baia, M.; Krömer, Stefan; Kružík, Martin

    2018-01-01

    Roč. 50, č. 1 (2018), s. 1076-1119 ISSN 0036-1410 R&D Projects: GA ČR GA14-15264S; GA ČR(CZ) GF16-34894L Institutional support: RVO:67985556 Keywords : lower semicontinuity * quasiconvexity * Young measures Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.648, year: 2016 http://library.utia.cas.cz/2018/MTR/kruzik-0487019.pdf

  16. Muon spin relaxation measurements of the fluctuation modes in spin-glass AgNm

    Energy Technology Data Exchange (ETDEWEB)

    Heffner, R.H.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Dodds, S.A.

    1983-01-01

    Recently reported zero-field ..mu..SR measurements below the spin-glass transition temperature in AgMn (1.6 at%) show a temperature dependent inhomogeneous width. The authors discuss these data in terms of a model in which the local field undergoes limited-amplitude fluctuations. The authors find that both very slow (approx. = 0.3 ..mu..s/sup -1/) and rapid (approx. = 3000 ..mu..s/sup -1/) fluctuations are required. 10 references, 1 figure, 1 table.

  17. NMR diffusion and relaxation measurements of organic molecules adsorbed in porous media

    International Nuclear Information System (INIS)

    Gjerdaaker, Lars

    2002-01-01

    The work in this thesis can be divided into two parts. The first part is focused on dynamic investigations of plastic crystals, both in bulk phases but also confined in porous materials (paper 1-3). This part was done together with professor Liudvikas Kimtys, Vilnius, Lithuania. The second part, with emphasis on diffusion, employed PFG NMR to measure the true intra-crystalline diffusivity, including development of a new pulse sequence with shorter effective diffusion time. This work was performed in collaboration with Dr. Geir H. Soerland, Trondheim, Norway and has resulted in three papers (paper 4-6). Paper 1-3: In these papers the dynamics of three organic compounds confined within mesoporous silica have been studied, and the results are discussed with reference to the bulk material. The three investigated compounds form disordered (plastic) phases of high symmetry on solidification (solid I). Thus, bulk cyclohexane exhibits a disordered phase between the solid-solid phase transition at 186 K and the melting point at 280 K. X-ray diffraction measurements have shown that solid I is face-centred cubic (Z=4, a=0.861 nm at 195 K), while the ordered solid II is monoclinic. Tert-butyl cyanide exhibits a plastic phase between the solid-solid transition point at 233 K and the melting point at 292 K. Neutron scattering techniques have established that solid I is tetragonal (Z=2, a=b=0.683 nm, c=0.674 nm, beta=90 deg at 234 K), while solid II is monoclinic. Finally, the disordered phase of pivalic acid melts at 310 K and undergoes a solid-solid phase transition at 280 K. The disordered phase is face-centred cubic, (Z=4, a=0.887 nm), while the low temperature phase (solid II) is triclinic. Paper 4-6; If one is aiming to measure true intra-crystallite diffusivities in porous media the distance travelled by the molecules during the pulse must be shorter than the size of the crystallite. The length of the diffusion time is therefore important. Working with heterogeneous media

  18. Assessing the effects of subject motion on T2 relaxation under spin tagging (TRUST) cerebral oxygenation measurements using volume navigators.

    Science.gov (United States)

    Stout, Jeffrey N; Tisdall, M Dylan; McDaniel, Patrick; Gagoski, Borjan; Bolar, Divya S; Grant, Patricia Ellen; Adalsteinsson, Elfar

    2017-12-01

    Subject motion may cause errors in estimates of blood T 2 when using the T 2 -relaxation under spin tagging (TRUST) technique on noncompliant subjects like neonates. By incorporating 3D volume navigators (vNavs) into the TRUST pulse sequence, independent measurements of motion during scanning permit evaluation of these errors. The effects of integrated vNavs on TRUST-based T 2 estimates were evaluated using simulations and in vivo subject data. Two subjects were scanned with the TRUST+vNav sequence during prescribed movements. Mean motion scores were derived from vNavs and TRUST images, along with a metric of exponential fit quality. Regression analysis was performed between T 2 estimates and mean motion scores. Also, motion scores were determined from independent neonatal scans. vNavs negligibly affected venous blood T 2 estimates and better detected subject motion than fit quality metrics. Regression analysis showed that T 2 is biased upward by 4.1 ms per 1 mm of mean motion score. During neonatal scans, mean motion scores of 0.6 to 2.0 mm were detected. Motion during TRUST causes an overestimate of T 2 , which suggests a cautious approach when comparing TRUST-based cerebral oxygenation measurements of noncompliant subjects. Magn Reson Med 78:2283-2289, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  19. Relaxation System

    Science.gov (United States)

    1987-01-01

    Environ Corporation's relaxation system is built around a body lounge, a kind of super easy chair that incorporates sensory devices. Computer controlled enclosure provides filtered ionized air to create a feeling of invigoration, enhanced by mood changing aromas. Occupant is also surrounded by multidimensional audio and the lighting is programmed to change colors, patterns, and intensity periodically. These and other sensory stimulators are designed to provide an environment in which the learning process is stimulated, because research has proven that while an individual is in a deep state of relaxation, the mind is more receptive to new information.

  20. Contrasting dynamics of fragile and non-fragile polyalcohols through the glass, and dynamical, transitions: A comparison of neutron scattering and dielectric relaxation data for sorbitol and glycerol.

    Science.gov (United States)

    Migliardo, F; Angell, C A; Magazù, S

    2017-01-01

    Glycerol and sorbitol are glass-forming hydrogen-bonded systems characterized by intriguing properties which make these systems very interesting also from the applications point of view. The goal of this work is to relate the hydrogen-bonded features, relaxation dynamics, glass transition properties and fragility of these systems, in particular to seek insight into their very different liquid fragilities. The comparison between glycerol and sorbitol is carried out by collecting the elastic incoherent neutron scattering (EINS) intensity as a function of temperature and of the instrumental energy resolution. Intensity data vs temperature and resolution are analyzed in terms of thermal restraint and Resolution Elastic Neutron Scattering (RENS) approaches. The number of OH groups, which are related to the connecting sites, is a significant parameter both in the glass transition and in the dynamical transition. On the other hand, the disordered nature of sorbitol is confirmed by the existence of different relaxation processes. From the applications point of view, glycerol and sorbitol have remarkable bioprotectant properties which make these systems useful in different technological and industrial fields. Furthermore, polyols are rich in glassforming liquid phenomenology and highly deserving of study in their own right. The comparison of EINS and calorimetric data on glycerol and sorbitol helps provide a connection between structural relaxation, dynamical transition, glass transition, and fragility. The evaluation of the inflection point in the elastic intensity behavior as a function of temperature and instrumental energy resolution provides a confirmation of the validity of the RENS approach. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016. Published by Elsevier B.V.

  1. In vivo measurements of the T1 relaxation processes in the bone marrow in patients with myelodysplastic syndrome. A magnetic resonance imaging study

    DEFF Research Database (Denmark)

    Jensen, K E; Nielsen, H; Thomsen, C

    1989-01-01

    Nine patients with myelodysplastic syndrome (MDS) were examined with magnetic resonance imaging and in vivo T1 relaxation time measurements of the vertebral bone marrow in a 1.5 tesla whole body scanner. Two patients underwent transformation to acute myeloid leukemia and were evaluated at follow-...... not differ from patients with polycythemia vera....

  2. Comparison of the Hamstring Muscle Activity and Flexion-Relaxation Ratio between Asymptomatic Persons and Computer Work-related Low Back Pain Sufferers.

    Science.gov (United States)

    Kim, Min-Hee; Yoo, Won-Gyu

    2013-05-01

    [Purpose] The purpose of this study was to compare the hamstring muscle (HAM) activities and flexion-relaxation ratios of an asymptomatic group and a computer work-related low back pain (LBP) group. [Subjects] For this study, we recruited 10 asymptomatic computer workers and 10 computer workers with work-related LBP. [Methods] We measured the RMS activity of each phase (flexion, full-flexion, and re-extension phase) of trunk flexion and calculated the flexion-relaxation (FR) ratio of the muscle activities of the flexion and full-flexion phases. [Results] In the computer work-related LBP group, the HAM muscle activity increased during the full-flexion phase compared to the asymptomatic group, and the FR ration was also significantly higher. [Conclusion] We thought that prolonged sitting of computer workers might cause the change in their HAM muscle activity pattern.

  3. A whole-air relaxed eddy accumulation measurement system for sampling vertical vapour exchange of elemental mercury

    Directory of Open Access Journals (Sweden)

    Jonas Sommar

    2013-11-01

    Full Text Available An apparatus relying on relaxed eddy accumulation (REA methodology has been designed and developed for continuous-field measurements of vertical Hg0 fluxes over cropland ecosystems. This micro-meteorological technique requires sampling of turbulent eddies into up- and downdraught channels at a constant flow rate and accurate timing, based on a threshold involving the sign of vertical wind component (w. The fully automated system is of a whole-air type drawing air at a high velocity to the REA sampling apparatus and allowing for the rejection of samples associated with w-fluctuations around zero. Conditional sampling was executed at 10-Hz resolution on a sub-stream by two fast-response three-way solenoid switching valves connected in parallel to a zero Hg0 air supply through their normally open ports. To suppress flow transients resulting from switching, pressure differentials across the two upstream ports of the conditional valves were minimised using a control unit. The Hg0 concentrations of the up- and downdraught channel were sequentially (each by two consecutive 5-minute gas samples determined after enhancement collection onto gold traps by an automated cold vapour atomic fluorescence spectrophotometer (CVAFS instrument. A protocol of regular reference sampling periods was implemented during field campaigns to continuously adjust for bias that may exist between the two conditional sampling channels. Using a 5-minute running average was conditional threshold, nearly-constant relaxation coefficients (β s of ~0.56 were determined during two bi-weekly field deployments when turbulence statistics were assured for good quality, in accordance with previously reported estimates. The fully developed REA-CVAFS system underwent Hg0 flux field trial runs at a winter wheat cropland located in the North China Plain. Over a 15-d period during early May 2012, dynamic, often bi-directional, fluxes were observed during the course of a day with a tendency of

  4. Long-term measurement of terpenoid flux above a Larix kaempferi forest using a relaxed eddy accumulation method

    Science.gov (United States)

    Mochizuki, Tomoki; Tani, Akira; Takahashi, Yoshiyuki; Saigusa, Nobuko; Ueyama, Masahito

    2014-02-01

    Terpenoids emitted from forests contribute to the formation of secondary organic aerosols and affect the carbon budgets of forest ecosystems. To investigate seasonal variation in terpenoid flux involved in the aerosol formation and carbon budget, we measured the terpenoid flux of a Larix kaempferi forest between May 2011 and May 2012 by using a relaxed eddy accumulation method. Isoprene was emitted from a fern plant species Dryopteris crassirhizoma on the forest floor and monoterpenes from the L. kaempferi. α-Pinene was the dominant compound, but seasonal variation of the monoterpene composition was observed. High isoprene and monoterpene fluxes were observed in July and August. The total monoterpene flux was dependent on temperature, but several unusual high positive fluxes were observed after rain fall events. We found a good correlation between total monoterpene flux and volumetric soil water content (r = 0.88), and used this correlation to estimate monoterpene flux after rain events and calculate annual terpenoid emissions. Annual carbon emission in the form of total monoterpenes plus isoprene was determined to be 0.93% of the net ecosystem exchange. If we do not consider the effect of rain fall, carbon emissions may be underestimated by about 50%. Our results suggest that moisture conditions in the forest soil is a key factor controlling the monoterpene emissions from the forest ecosystem.

  5. 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.

  6. VOC flux measurements using a novel Relaxed Eddy Accumulation GC-FID system in urban Houston, Texas

    Science.gov (United States)

    Park, C.; Schade, G.; Boedeker, I.

    2008-12-01

    Houston experiences higher ozone production rates than most other major cities in the US, which is related to high anthropogenic VOC emissions from both area/mobile sources (car traffic) and a large number of petrochemical facilities. The EPA forecasts that Houston is likely to still violate the new 8-h NAAQS in 2020. To monitor neighborhood scale pollutant fluxes, we established a tall flux tower installation a few kilometers north of downtown Houston. We measure energy and trace gas fluxes, including VOCs from both anthropogenic and biogenic emission sources in the urban surface layer using eddy covariance and related techniques. Here, we describe a Relaxed Eddy Accumulation (REA) system combined with a dual-channel GC-FID used for VOC flux measurements, including first results. Ambient air is sampled at approximately 15 L min-1 through a 9.5 mm OD PFA line from 60 m above ground next to a sonic anemometer. Subsamples of this air stream are extracted through an ozone scrubber and pushed into two Teflon bag reservoirs, from which they are transferred to the GC pre-concentration units consisting of carbon-based adsorption traps encapsulated in heater blocks for thermal desorption. We discuss the performance of our system and selected measurement results from the 2008 spring and summer seasons in Houston. We present diurnal variations of the fluxes of the traffic tracers benzene, toluene, ethylbenzene, and xylenes (BTEX) during different study periods. Typical BTEX fluxes ranged from -0.36 to 3.10 mg m-2 h-1 for benzene, and -0.47 to 5.04 mg m-2 h-1 for toluene, and exhibited diurnal cycles with two dominant peaks related to rush-hour traffic. A footprint analysis overlaid onto a geographic information system (GIS) will be presented to reveal the dominant emission sources and patterns in the study area.

  7. Chambers versus Relaxed Eddy Accumulation: an intercomparison study of two methods for short-term measurements of biogenic CO2 fluxes

    Science.gov (United States)

    Jasek, Alina; Zimnoch, Miroslaw; Gorczyca, Zbigniew; Chmura, Lukasz; Necki, Jaroslaw

    2014-05-01

    The presented work is a part of comprehensive study aimed at thorough characterization of carbon cycle in the urban environment of Krakow, southern Poland. In the framework of this study two independent methods were employed to quantify biogenic CO2 flux in the city: (i) closed chambers, and (ii) Relaxed Eddy Accumulation (REA). The results of a three-day intensive intercomparison campaign performed in July 2013 and utilizing both measurement methods are reported here. The chamber method is a widely used approach for measurements of gas exchange between the soil and the atmosphere. The system implemented in this study consisted of a single chamber operating in a closed-dynamic mode, combined with Vaisala CarboCAP infrared CO2 sensor in a mobile setup. An alternative flux measurement method, covering larger area is represented by REA, which is a modification of the eddy covariance method. It consists of a 3D anemometer (Gill Windmaster Pro) and the system collecting updraft and downdraft samples to 5-litre Tedlar bags. The CO2 mixing ratios in the collected samples are measured by Picarro G2101i analyzer. The setup consists of two sets of bags so that the sampling can be performed continuously with 15-min temporal resolution. A 48-hectares open meadow located close the city center was chosen as a test site for comparison of the two methods of CO2 flux measurements outlined above. In the middle of the meadow a 3-metre high tripod was installed with the anemometer and REA inlet system. For a period of 46 hours the system was measuring net CO2 flux from the surrounding area. A meteorological conditions and intensity of photosynthetically active radiation (PAR) were also recorded. In the same time, CO2 flux from several points around the REA inlet was measured with the chamber system, resulting in 93 values for both respiration and net CO2 flux. Chamber results show rather homogenous distribution of the soil CO2 flux (the mean value equal to 40.9 ± 2.2 mmol/m2h), with

  8. Theory of nuclear spin relaxation in disordered systems: comparison of Bloembergen-Purcell-Pound models and Monte Carlo simulations

    International Nuclear Information System (INIS)

    Luo Xinjun; Sholl, C.A.

    2002-01-01

    Two Bloembergen-Purcell-Pound (BPP) models for analysing nuclear spin relaxation data for translational diffusion in disordered systems are compared with Monte Carlo simulations. One model (the a-BPP model, 'a' standing for average) is commonly used for disordered systems and the other (the Cameron-Sholl BPP model) is more rigorously based and can distinguish between site-and barrier-energy disorder. Simulated relaxation data produced using Gaussian distributions of energy disorder are analysed using the models, and the parameters obtained from the fits are compared with the values used for the simulations. It is found that both models can give reasonable fits to the data. Both models also give reasonable agreement with the simulation parameters provided that the standard deviation of the energy distribution for the a-BPP model is interpreted as the average of the site-and barrier-energy standard deviations. Quantitative estimates are given of the accuracy of the parameters from the fits. (author)

  9. Comparison of T2* relaxation times of articular cartilage of the knee in elite professional football players and age-and BMI-matched amateur athletes

    Energy Technology Data Exchange (ETDEWEB)

    Behzadi, C., E-mail: c.behzadi@uke.de [Department of Diagnostic and Interventional Radiology and Nuclearmedicine, University Medical Center Hamburg-Eppendorf, Hamburg, 20246 (Germany); Welsch, G.H. [Department of Sports Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, 20246 (Germany); Laqmani, A.; Henes, F.O.; Kaul, M.G. [Department of Diagnostic and Interventional Radiology and Nuclearmedicine, University Medical Center Hamburg-Eppendorf, Hamburg, 20246 (Germany); Schoen, G. [Department of Medical Biometry and Epidemiology, University Medical Center, Hamburg-Eppendorf, Hamburg, 20246 (Germany); Adam, G.; Regier, M. [Department of Diagnostic and Interventional Radiology and Nuclearmedicine, University Medical Center Hamburg-Eppendorf, Hamburg, 20246 (Germany)

    2017-01-15

    Objective: Recent investigation has underlined the potential of quantitative MR imaging to be used as a complementary tool for the diagnosis of cartilage degeneration at an early state. The presented study analyses T2* relaxation times of articular cartilage of the knee in professional athletes and compares the results to age- and BMI (Body Mass Index)-matched healthy amateur athletes. Materials and methods: 22 professional football players and 22 age- and BMI-matched individuals were underwent knee Magnetic Resonance Imaging (MRI) at 3T including qualitative and quantitative analysis. Qualitative analysis included e.g. meniscal tears, joint effusion and bone edema. For quantitative analysis T2* (22 ET: 4.6-53.6 ms) measurements in 3D data acquisition were performed. Deep and superficial layers of 22 predefined cartilage segments were analysed. All data sets were postprocessed using a dedicated software tool. Statistical analysis included Student t-test, confidence intervals and a random effects model. Results: In both groups, T2* relaxation times were significantly higher in the superficial compared to the deep layers (p < 0.001). Professional athletes had significantly higher relaxation times in eight superficial and three deep cartilage layers in the predefined cartilage segments (p < 0.05). Highly significant differences were found in the weight-bearing segments of the lateral superficial femoral condyle (p < 0.001). Conclusion: Elevated T2* values in cartilage layers of professional football players compared to amateur athletes were noted. The effects seem to predominate in superficial cartilage layers.

  10. Comparison of T2* relaxation times of articular cartilage of the knee in elite professional football players and age-and BMI-matched amateur athletes

    International Nuclear Information System (INIS)

    Behzadi, C.; Welsch, G.H.; Laqmani, A.; Henes, F.O.; Kaul, M.G.; Schoen, G.; Adam, G.; Regier, M.

    2017-01-01

    Objective: Recent investigation has underlined the potential of quantitative MR imaging to be used as a complementary tool for the diagnosis of cartilage degeneration at an early state. The presented study analyses T2* relaxation times of articular cartilage of the knee in professional athletes and compares the results to age- and BMI (Body Mass Index)-matched healthy amateur athletes. Materials and methods: 22 professional football players and 22 age- and BMI-matched individuals were underwent knee Magnetic Resonance Imaging (MRI) at 3T including qualitative and quantitative analysis. Qualitative analysis included e.g. meniscal tears, joint effusion and bone edema. For quantitative analysis T2* (22 ET: 4.6-53.6 ms) measurements in 3D data acquisition were performed. Deep and superficial layers of 22 predefined cartilage segments were analysed. All data sets were postprocessed using a dedicated software tool. Statistical analysis included Student t-test, confidence intervals and a random effects model. Results: In both groups, T2* relaxation times were significantly higher in the superficial compared to the deep layers (p < 0.001). Professional athletes had significantly higher relaxation times in eight superficial and three deep cartilage layers in the predefined cartilage segments (p < 0.05). Highly significant differences were found in the weight-bearing segments of the lateral superficial femoral condyle (p < 0.001). Conclusion: Elevated T2* values in cartilage layers of professional football players compared to amateur athletes were noted. The effects seem to predominate in superficial cartilage layers.

  11. Treatment of anxiety: a comparison of the usefulness of self-hypnosis and a meditational relaxation technique. An overview.

    Science.gov (United States)

    Benson, H; Frankel, F H; Apfel, R; Daniels, M D; Schniewind, H E; Nemiah, J C; Sifneos, P E; Crassweller, K D; Greenwood, M M; Kotch, J B; Arns, P A; Rosner, B

    1978-01-01

    We have investigated prospectively the efficacy of two nonpharmacologic relaxation techniques in the therapy of anxiety. A simple, meditational relaxation technique (MT) that elicits the changes of decreased sympathetic nervous system activity was compared to a self-hypnosis technique (HT) in which relaxation, with or without altered perceptions, was suggested. 32 patients with anxiety neurosis were divided into 2 groups on the basis of their responsivity to hypnosis: moderate-high and low responsivity. The MT or HT was then randomly assigned separately to each member of the two responsivity groups. Thus, 4 treatment groups were studied: moderate-high responsivity MT; low responsivity MT; moderate-high responsivity HT; and low responsivity HT. The low responsivity HT group, by definition largely incapable of achieving the altered perceptions essential to hypnosis, was designed as the control group. Patients were instructed to practice the assigned technique daily for 8 weeks. Change in anxiety was determined by three types of evaluation: psychiatric assessment; physiologic testing; and self-assessment. There was essentially no difference between the two techniques in therapeutic efficacy according to these evaluations. Psychiatric assessment revealed overall improvement in 34% of the patients and the self-rating assessment indicated improvement in 63% of the population. Patients who had moderate-high hypnotic responsivity, independent of the technique used, significantly improved on psychiatric assessment (p = 0.05) and decreased average systolic blood pressure from 126.1 to 122.5 mm Hg over the 8-week period (p = 0.048). The responsivity scores at the higher end of the hypnotic responsivity spectrum were proportionately correlated to greater decreases in systolic blood pressure (p = 0.075) and to improvement by psychiatric assessment (p = 0.003). There was, however, no consistent relation between hypnotic responsivity and the other assessments made, such as

  12. Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO).

    Science.gov (United States)

    Fielding, Alistair J; Usselman, Robert J; Watmough, Nicholas; Simkovic, Martin; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

    2008-02-01

    Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S](2+,1+) cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S](+) cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S](+) between 8 and 18K and for semiquinone between 25 and 65K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S](+) were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S](+) and obtain point-dipole interspin distances of 18.6+/-1A for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.

  13. DEVICE FOR MEASURMENT OF RELAXATION TIME OF THE BLEACHED STATE OF OPTICAL MATERIALS BY THE «PUMP-PROBE» METHOD IN SUB-ΜS TIME DOMAIN

    Directory of Open Access Journals (Sweden)

    I. V. Glazunov

    2016-01-01

    Full Text Available The use of passive shutters to control the duration of the light pulses is an important aspect in the miniature and microchip lasers. One of the key spectroscopic characteristics which determine the properties of the material, which can be used as a passive shutter is relaxation time of its bleached state.We describe a device for determination of relaxation time of the bleached state in optical materials by the «pump-probe» method in the sub-μs time domain. This device allows one to determine relaxation times for materials which absorb at the light wavelength of 1.5 μm, e.g., materials doped with cobalt ions Co2+. The results of test examinations of the device are described, and the relaxation time of the bleached state of Co2+ ions is measured for a novel material – transparent glass-ceramics with Co2+:Ga2 O3 nanophase – amounting to 190 ± 6 ns. 

  14. The impact of muscle relaxation techniques on the quality of life of cancer patients, as measured by the FACT-G questionnaire.

    Science.gov (United States)

    Parás-Bravo, Paula; Salvadores-Fuentes, Paloma; Alonso-Blanco, Cristina; Paz-Zulueta, María; Santibañez-Margüello, Miguel; Palacios-Ceña, Domingo; Boixadera-Planas, Ester; Fernández-de-Las-Peñas, César

    2017-01-01

    Patients with cancer frequently suffer from emotional distress, characterized by psychological symptoms such as anxiety or depression. The presence of psychological symptoms combined with the complex nature of oncology processes can negatively impact patients' quality of life. We aimed to determine the impact of a relaxation protocol on improving quality of life in a sample of oncological patients treated in the Spanish National Public Health System. We conducted a multicenter interventional study without a control group. In total, 272 patients with different oncologic pathologies and showing symptoms of anxiety were recruited from 10 Spanish public hospitals. The intervention comprised abbreviated progressive muscle relaxation training, according to Bernstein and Borkovec. This was followed by weekly telephone calls to each patient over a 1-month period. We collected sociodemographic variables related to the disease process, including information about mental health and the intervention. Patients' quality of life was assessed using the Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire. Bivariate and univariate analyses were performed, along with an analysis of multiple correspondences to identify subgroups of patients with similar variations on the FACT-G. Patients showed statistically significant improvements on the FACT-G overall score (W = 16806; pPatients with cancer who learned and practiced abbreviated progressive muscle relaxation experienced improvement in their perceived quality of life as measured by the FACT-G. Our findings support a previous assumption that complementary techniques (including relaxation techniques) are effective in improving the quality of life of patients with cancer.

  15. On the Use of Molecular Weight Cutoff Cassettes to Measure Dynamic Relaxivity of Novel Gadolinium Contrast Agents: Example Using Hyaluronic Acid Polymer Complexes in Phosphate-Buffered Saline

    Directory of Open Access Journals (Sweden)

    Nima Kasraie

    2011-01-01

    Full Text Available The aims of this study were to determine whether standard extracellular contrast agents of Gd(III ions in combination with a polymeric entity susceptible to hydrolytic degradation over a finite period of time, such as Hyaluronic Acid (HA, have sufficient vascular residence time to obtain comparable vascular imaging to current conventional compounds and to obtain sufficient data to show proof of concept that HA with Gd-DTPA ligands could be useful as vascular imaging agents. We assessed the dynamic relaxivity of the HA bound DTPA compounds using a custom-made phantom, as well as relaxation rates at 10.72 MHz with concentrations ranging between 0.09 and 7.96 mM in phosphate-buffered saline. Linear dependences of static longitudinal relaxation rate (R1 on concentration were found for most measured samples, and the HA samples continued to produce high signal strength after 24 hours after injection into a dialysis cassette at 3T, showing superior dynamic relaxivity values compared to conventional contrast media such as Gd-DTPA-BMA.

  16. Oxygen surface exchange kinetics measurement by simultaneous optical transmission relaxation and impedance spectroscopy: Sr(Ti,Fe)O3-x thin film case study.

    Science.gov (United States)

    Perry, Nicola H; Kim, Jae Jin; Tuller, Harry L

    2018-01-01

    We compare approaches to measure oxygen surface exchange kinetics, by simultaneous optical transmission relaxation (OTR) and AC-impedance spectroscopy (AC-IS), on the same mixed conducting SrTi 0.65 Fe 0.35 O 3-x film. Surface exchange coefficients were evaluated as a function of oxygen activity in the film, controlled by gas partial pressure and/or DC bias applied across the ionically conducting yttria-stabilized zirconia substrate. Changes in measured light transmission through the film over time (relaxations) resulted from optical absorption changes in the film corresponding to changes in its oxygen and oxidized Fe (~Fe 4+ ) concentrations; such relaxation profiles were successfully described by the equation for surface exchange-limited kinetics appropriate for the film geometry. The k chem values obtained by OTR were significantly lower than the AC-IS derived k chem values and k q values multiplied by the thermodynamic factor (bulk or thin film), suggesting a possible enhancement in k by the metal current collectors (Pt, Au). Long-term degradation in k chem and k q values obtained by AC-IS was also attributed to deterioration of the porous Pt current collector, while no significant degradation was observed in the optically derived k chem values. The results suggest that, while the current collector might influence measurements by AC-IS, the OTR method offers a continuous, in situ , and contact-free method to measure oxygen exchange kinetics at the native surfaces of thin films.

  17. Oxygen surface exchange kinetics measurement by simultaneous optical transmission relaxation and impedance spectroscopy: Sr(Ti,Fe)O3-x thin film case study

    Science.gov (United States)

    Perry, Nicola H.; Kim, Jae Jin; Tuller, Harry L.

    2018-01-01

    Abstract We compare approaches to measure oxygen surface exchange kinetics, by simultaneous optical transmission relaxation (OTR) and AC-impedance spectroscopy (AC-IS), on the same mixed conducting SrTi0.65Fe0.35O3-x film. Surface exchange coefficients were evaluated as a function of oxygen activity in the film, controlled by gas partial pressure and/or DC bias applied across the ionically conducting yttria-stabilized zirconia substrate. Changes in measured light transmission through the film over time (relaxations) resulted from optical absorption changes in the film corresponding to changes in its oxygen and oxidized Fe (~Fe4+) concentrations; such relaxation profiles were successfully described by the equation for surface exchange-limited kinetics appropriate for the film geometry. The kchem values obtained by OTR were significantly lower than the AC-IS derived kchem values and kq values multiplied by the thermodynamic factor (bulk or thin film), suggesting a possible enhancement in k by the metal current collectors (Pt, Au). Long-term degradation in kchem and kq values obtained by AC-IS was also attributed to deterioration of the porous Pt current collector, while no significant degradation was observed in the optically derived kchem values. The results suggest that, while the current collector might influence measurements by AC-IS, the OTR method offers a continuous, in situ, and contact-free method to measure oxygen exchange kinetics at the native surfaces of thin films. PMID:29511391

  18. Four-year measurement of methane flux over a temperate forest with a relaxed eddy accumulation method

    Science.gov (United States)

    Sakabe, A.; Kosugi, Y.; Ueyama, M.; Hamotani, K.; Takahashi, K.; Iwata, H.; Itoh, M.

    2013-12-01

    Forests are generally assumed to be an atmospheric methane (CH4) sink (Le Mer and Roger, 2001). However, under Asian monsoon climate, forests are subject to wide spatiotemporal range in soil water status, where forest soils often became water-saturated condition heterogeneously. In such warm and humid conditions, forests may act as a CH4 source and/or sink with considerable spatiotemporal variations. Micrometeorological methods such as eddy covariance (EC) method continuously measure spatially-representative flux at a canopy scale without artificial disturbance. In this study, we measured CH4 fluxes over a temperate forest during four-year period using a CH4 analyzer based on tunable diode laser spectroscopy detection with a relaxed eddy accumulation (REA) method (Hamotani et al., 1996, 2001). We revealed the amplitude and seasonal variations of canopy-scale CH4 fluxes. The REA method is the attractive alternative to the EC method to measure trace-gas flux because it allows the use of analyzers with an optimal integration time. We also conducted continuous chamber measurements on forest floor to reveal spatial variations in soil CH4 fluxes and its controlling processes. The observations were made in an evergreen coniferous forest in central Japan. The site has a warm temperate monsoon climate with wet summer. Some wetlands were located in riparian zones along streams within the flux footprint area. For the REA method, the sonic anemometer (SAT-550, Kaijo) was mounted on top of the 29-m-tall tower and air was sampled from just below the sonic anemometer to reservoirs according to the direction of vertical wind velocity (w). After accumulating air for 30 minutes, the air in the reservoirs was pulled into a CO2/H2O gas analyzer (LI-840, Li-Cor) and a CH4 analyzer (FMA-200, Los Gatos Research). Before entering the analyzers, the sampled air was dried using a gas dryer (PD-50 T-48; Perma Pure Inc.). The REA flux is obtained from the difference in the mean concentrations

  19. Quantitative MRI T2 relaxation time evaluation of knee cartilage: comparison of meniscus-intact and -injured knees after anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Li, Hong; Chen, Shuang; Tao, Hongyue; Chen, Shiyi

    2015-04-01

    Associated meniscal injury is well recognized at anterior cruciate ligament (ACL) reconstruction, and it is a known risk factor for osteoarthritis. To evaluate and characterize the postoperative appearance of articular cartilage after different meniscal treatment in ACL-reconstructed knees using T2 relaxation time evaluation on MRI. Cohort study; Level of evidence, 3. A total of 62 consecutive patients who under ACL reconstruction were recruited in this study, including 23 patients undergoing partial meniscectomy (MS group), 21 patients undergoing meniscal repair (MR group), and 18 patients with intact menisci (MI group) at time of surgery. Clinical evaluation, including subjective functional scores and physical examination, was performed on the same day as the MRI examination and at follow-up times ranging from 2 to 4.2 years. The MRI multiecho sagittal images were segmented to determine the T2 relaxation time value of each meniscus and articular cartilage plate. Differences in each measurement were compared among groups. No patient had joint-line tenderness or reported pain or clicking on McMurray test or instability. There were also no statistically significant differences in functional scores or medial or lateral meniscus T2 values among the 3 groups (P > .05 for both). There was a significantly higher articular cartilage T2 value in the medial femorotibial articular cartilage for the MS group (P T2 value between the MS and MR groups (P > .05) in each articular cartilage plate. The medial tibial articular cartilage T2 value had a significant positive correlation with medial meniscus T2 value (r = 0.287; P = .024) CONCLUSION: This study demonstrates that knees with meniscectomy or meniscal repair had articular cartilage degeneration at 2 to 4 years postoperatively, with higher articular cartilage T2 relaxation time values compared with the knees with an intact meniscus. © 2015 The Author(s).

  20. Controlled comparison of family cognitive behavioral therapy and psychoeducation/relaxation training for child obsessive-compulsive disorder.

    Science.gov (United States)

    Piacentini, John; Bergman, R Lindsey; Chang, Susanna; Langley, Audra; Peris, Tara; Wood, Jeffrey J; McCracken, James

    2011-11-01

    To examine the efficacy of exposure-based cognitive-behavioral therapy (CBT) plus a structured family intervention (FCBT) versus psychoeducation plus relaxation training (PRT) for reducing symptom severity, functional impairment, and family accommodation in youths with obsessive-compulsive disorder (OCD). A total of 71 youngsters 8 to 17 years of age (mean 12.2 years; range, 8-17 years, 37% male, 78% Caucasian) with primary OCD were randomized (70:30) to 12 sessions over 14 weeks of FCBT or PRT. Blind raters assessed outcomes with responders followed for 6 months to assess treatment durability. FCBT led to significantly higher response rates than PRT in ITT (57.1% vs 27.3%) and completer analyses (68.3% vs. 35.3%). Using HLM, FCBT was associated with significantly greater change in OCD severity and child-reported functional impairment than PRT and marginally greater change in parent-reported accommodation of symptoms. These findings were confirmed in some, but not all, secondary analyses. Clinical remission rates were 42.5% for FCBT versus 17.6% for PRT. Reduction in family accommodation temporally preceded improvement in OCD for both groups and child functional status for FCBT only. Treatment gains were maintained at 6 months. FCBT is effective for reducing OCD severity and impairment. Importantly, treatment also reduced parent-reported involvement in symptoms with reduced accommodation preceding reduced symptom severity and functional impairment. CLINICAL TRIALS REGISTRY INFORMATION: Behavior Therapy for Children and Adolescents with Obsessive-Compulsive Disorder (OCD); http://www.clinicaltrials.gov; NCT00000386. Copyright © 2011 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Comparison of clinical outcomes between limbal relaxing incisions and toric intraocular lenses in eyes with astigmatic corneas

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2014-01-01

    Full Text Available Objective: To compare refractive and vectorial outcomes of limbal relaxing incisions (LRI versus toric intraocular lenses (IOL in the treatment of preexisting corneal astigmatism at the time of phacoemulsification. Methods: This longitudinal observational case series assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted in two groups: one assigned to receive AcrySof Toric™ IOL in both eyes, and another one assigned to have AcrySof Natural™ IOL associated with LRI, also in both eyes. All patients were re-evaluated, postoperatively, at 1, 3 and 6 months, when refractive astigmatism analysis was performed using vectorial methods proposed by Thibos. Variability of outcomes within each group and between groups were assessed and compared. Results: Manifest refractive cylinder, in diopters (D, as means ± standard deviation, in the LRI group for 1-month, 3-month and 6-month re-evalutions were respectively -0.66 ± 0.30; -0.70 ± 0.21 and -0.74 ± 0.26 when compared to -0.58 ± 0.24; -0.63 ± 0.20, and -0.62 ± 0.17 in the toric IOL group. (p value ≥ 0.06. Vectorial analysis evidenced greater astigmatism reduction in the toric IOL group in the 6th postoperative month, when postoperative mean astigmatic power vector was 0.31 D, when compared to 0.37 D in the LRI group (p value = 0.00. Conclusions: A trend of slightly better refractive outcomes favoring toric IOL group was seen, although such a trend was not statistically significant. Vectorial analysis, however, suggests that the use of toric IOL may constitute a more advantageous approach in the treatment of pre-existing corneal astigmatism, simultaneously with phacoemulsification.

  2. In-situ measurement of the strain relaxation of GaN nanograins during X-ray irradiation

    International Nuclear Information System (INIS)

    Choe, Hyeokmin; Lee, Sanghwa; Sohn, Yuri; Kim, Chinkyo

    2008-01-01

    GaN nanograins were grown on a c-plane sapphire substrate and their strain relaxation due to X-ray irradiation was investigated in-situ by utilizing synchrotron xray scattering. The GaN nanograins were constantly exposed to the synchrotron X-ray and θ-2θ scans through the (002) Bragg peak of GaN were repeatedly carried out during the irradiation. The Bragg peak of the compressively strained GaN nanograins gradually shifted toward higher angle, which implies that the GaN nanograins in compressive strain experienced strain relaxation during X-ray irradiation. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Assessment of a relaxed eddy accumulation for measurements of fluxes of biogenic volatile organic compounds: Study over arable crops and a mature beech forest

    DEFF Research Database (Denmark)

    Gallagher, M.W.; Clayborough, R.; Beswick, K.M.

    2000-01-01

    A relaxed eddy accumulation (REA) system, based on the design by Beverland et al. (Journal of Geophysics Research 101 (D17) 22, 807-22, 815), for the measurement of biogenic VOC species was evaluated by intercomparison with an eddy correlation CO2 flux system over a mature deciduous beech canopy...... (Fagus Sylvatica) during the FOREXNOX program. Measurements from a site where winter wheat and barley (Hordeum Vulgare ann Triticum Aestivum) were being harvested are also presented. The system was inter-compared with two different eddy correlation systems for measuring CO2 fluxes. Good results were...

  4. A comparison of RAM importance measures

    International Nuclear Information System (INIS)

    Atwood, C.L.; Wolford, A.J.; Wright, R.E.

    1989-01-01

    In this paper measures of importance of components and cut sets of a system are reviewed. The measures considered are based on reliability, availability, and maintainability, the three elements of the acronym RAM. They follow the approaches of Fussell and Vesely and of Birnbaum. A new Birnbaum-type unmaintainability importance measure is proposed. The measures are compared in a simple example, and the appropriate use of unmaintainability importance is discussed

  5. A comparison of 'radon' measurement devices

    International Nuclear Information System (INIS)

    Rolle, R.

    2004-01-01

    For the indoor concentration measurement of Rn decay chain members, instruments ranging from long-term integrating passive devices to far more sensitive active devices with good time resolution are in use. The former are used mainly to screen for potentially high exposure locations, while the latter are useful for assessing the exposure dynamics of encumbered premises, with potential clarification (modelling) for optimal remediation, before, during and after such process. Concentration measurement of any one decay chain member always involves its complete decay chain. The 222 Rn gas concentration can be measured with gas measuring devices or with spectrometric measuring instruments that concentrate the decay products. The latter generally offer far more accurate measurement per time of the 222 Rn concentration, than mere Rn gas measuring devices, and also give the decay product concentrations and thus activity ratios which are related to air exchange. The concentrations of the unattached Rn decay products may be measured simultaneously with inline screen measurement. In premises steady state ventilation conditions are rare. Rapidly changing concentrations can be measured more accurately with the more sensitive concentrating instruments - the inherent instrumental time lag of detected signals from chain decay, relative to time of sampling, should however be corrected where rates of concentration change approximate chain decay constants. Counting of beta-signals in addition to alpha-spectrometry, and quasi-continuous sampling while continuously measuring, enhances the sensitivity, and particularly measurement time lag correction, where concentration ratios are sought for elucidating air exchange. Appropriate software ought to be made available to evaluate the spectrometric data and to link it to suitable compartment ventilation models (automatic adjustment for a dynamic change in alpha-calibration could be incorporated) - this would constitute the modern version of

  6. Comparison of asphere measurements by tactile and optical metrological instruments

    NARCIS (Netherlands)

    Bergmans, R.H.; Nieuwenkamp, H.J.; Kok, G.J.P.; Blobel, G.; Nouira, H.; Küng, A.; Baas, M.; Voert, M.J.A. te; Baer, G.; Stuerwald, S.

    2015-01-01

    A comparison of topography measurements of aspherical surfaces was carried out by European metrology institutes, other research institutes and a company as part of an European metrology research project. In this paper the results of this comparison are presented. Two artefacts were circulated, a

  7. Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H., E-mail: hongye18@mm.kyushu-u.ac.jp [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, K.; Hata, S.; Nakashima, H. [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang, D.; Nakashima, H. [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2011-04-15

    Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si{sub x}N{sub y}, plasma-enhanced (PE) Si{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi{sub x}N{sub y}/Si sample, those along the length of the FSSM are tensile in PESi{sub x}N{sub y}/Si and Si{sub x}Ge{sub 1-x}/Si samples. The average absolute values of strains are different in FSSM with LPSi{sub x}N{sub y}, PESi{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

  8. Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

    International Nuclear Information System (INIS)

    Gao, H.; Ikeda, K.; Hata, S.; Nakashima, H.; Wang, D.; Nakashima, H.

    2011-01-01

    Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si x N y , plasma-enhanced (PE) Si x N y and Si x Ge 1-x stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi x N y /Si sample, those along the length of the FSSM are tensile in PESi x N y /Si and Si x Ge 1-x /Si samples. The average absolute values of strains are different in FSSM with LPSi x N y , PESi x N y and Si x Ge 1-x as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

  9. Muon spin-relaxation measurements of spin-correlation decay in spin-glass AgMn

    International Nuclear Information System (INIS)

    Heffner, R.H.; Cooke, D.W.; Leon, M.; Schillaci, M.E.; MacLaughlin, D.E.; Gupta, L.C.

    1983-01-01

    The field (H) dependence of the muon longitudinal spin-lattice relaxation rate well below the spin-glass temperature in AgMn is found to obey an algebraic form given by (H)/sup nu-1/, with nu = 0.54 +- 0.05. This suggests that Mn spin correlations decay with time as t - /sup nu/, in agreement with mean field theories of spin-glass dynamics which yield nu less than or equal to 0.5. Near the glass temperature the agreement between the data and theory is not as good

  10. The impact of muscle relaxation techniques on the quality of life of cancer patients, as measured by the FACT-G questionnaire.

    Directory of Open Access Journals (Sweden)

    Paula Parás-Bravo

    Full Text Available Patients with cancer frequently suffer from emotional distress, characterized by psychological symptoms such as anxiety or depression. The presence of psychological symptoms combined with the complex nature of oncology processes can negatively impact patients' quality of life. We aimed to determine the impact of a relaxation protocol on improving quality of life in a sample of oncological patients treated in the Spanish National Public Health System.We conducted a multicenter interventional study without a control group. In total, 272 patients with different oncologic pathologies and showing symptoms of anxiety were recruited from 10 Spanish public hospitals. The intervention comprised abbreviated progressive muscle relaxation training, according to Bernstein and Borkovec. This was followed by weekly telephone calls to each patient over a 1-month period. We collected sociodemographic variables related to the disease process, including information about mental health and the intervention. Patients' quality of life was assessed using the Functional Assessment of Cancer Therapy-General (FACT-G questionnaire. Bivariate and univariate analyses were performed, along with an analysis of multiple correspondences to identify subgroups of patients with similar variations on the FACT-G.Patients showed statistically significant improvements on the FACT-G overall score (W = 16806; p<0.001, with an initial mean score of 55.33±10.42 and a final mean score of 64.49±7.70. We also found significant improvements for all subscales: emotional wellbeing (W = 13118; p<0.001, functional wellbeing (W = 16155.5; p<0.001, physical wellbeing (W = 8885.5; p<0.001, and social and family context (W = -1840; p = 0.037.Patients with cancer who learned and practiced abbreviated progressive muscle relaxation experienced improvement in their perceived quality of life as measured by the FACT-G. Our findings support a previous assumption that complementary techniques (including

  11. Capturing molecular multimode relaxation processes in excitable gases based on decomposition of acoustic relaxation spectra

    Science.gov (United States)

    Zhu, Ming; Liu, Tingting; Wang, Shu; Zhang, Kesheng

    2017-08-01

    Existing two-frequency reconstructive methods can only capture primary (single) molecular relaxation processes in excitable gases. In this paper, we present a reconstructive method based on the novel decomposition of frequency-dependent acoustic relaxation spectra to capture the entire molecular multimode relaxation process. This decomposition of acoustic relaxation spectra is developed from the frequency-dependent effective specific heat, indicating that a multi-relaxation process is the sum of the interior single-relaxation processes. Based on this decomposition, we can reconstruct the entire multi-relaxation process by capturing the relaxation times and relaxation strengths of N interior single-relaxation processes, using the measurements of acoustic absorption and sound speed at 2N frequencies. Experimental data for the gas mixtures CO2-N2 and CO2-O2 validate our decomposition and reconstruction approach.

  12. Comparison of radiological measures for diagnosing flatfoot

    International Nuclear Information System (INIS)

    Lo, Huan-Chu; Chu, Wencheng; Wu, Weikai; Hsieh, Hsin; Chou, Chiehping; Sun, Shaoen; Chou, Pinya; Liao, Chenhui; Guan, Xiaoyun; Li, Shuchee

    2012-01-01

    Background. In the Taiwanese military, flatfoot is indicated by a calcaneal-fifth metatarsal angle (arch angle) =165 deg . However, the arch angle is not always easily defined. Purpose. To assess correlations between the arch angle and other radiographic measures and thus identify an alternative radiographic measure for diagnosing flatfoot. Material and Methods Eighty-seven male Taiwanese military recruits were studied (median age 22 years, interquartile range 20-23 years). Lateral, weight-bearing radiographs were taken. Five radiographic measurements, including the calcaneal-fifth metatarsal angle (arch angle), medial arch angle (MAA), calcaneal pitch angle (CP), talus angle (TA), and talar-first metatarsal angle (TFM) were made. Correlations between the arch angle and all other measures were determined. A cut-off value for predicting flatfoot (arch angle ≥165 deg ) was determined for each measure using the Youden index and receiver-operating characteristic (ROC) curves were generated for each measure to assess diagnostic accuracy. Results. All measures were significantly correlated with arch angle (P 9.5 deg ) had the highest specificity (90.3% vs. 88.75 for CP <12.3 deg ). Conclusion. CP is inversely correlated with arch angle in Taiwanese male military recruits. CP < 12.3 deg is a significant predictor of flatfoot. Assessment of CP may be used as an alternative means of diagnosing flatfoot when the arch angle is not easily defined

  13. Interlaboratory comparison of the measurement of retention curves

    DEFF Research Database (Denmark)

    Hansen, M. H.; Houvenaghel, G.; Janz, M.

    1999-01-01

    The results of an interlaboratory comparison of the measurement of apparent density, solid density, open porosity and retention curves are presented. Baumberger sandstone and Sander sandstone were used as test materials.Repeatability standard deviation and reproducibility standard deviation...

  14. Comparison of GRACE with in situ hydrological measurement data ...

    African Journals Online (AJOL)

    Comparison of GRACE with in situ hydrological measurement data shows storage depletion in Hai River basin, Northern China. ... of the world, their application in conjunction with hydrological models could improve hydrological studies.

  15. Comparison of soybean evapotranspirations measured by weighing ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-07-26

    Jul 26, 2010 ... of the surface, integrating latent heat fluxes over large areas ... to determine whether Bowen ratio system could provide accurate .... glass electrode pH-meter. ... measured in soil paste using standard Wheatstone resistance.

  16. Experiments in paramagnetic relaxation

    International Nuclear Information System (INIS)

    Lijphart, E.E.

    1976-01-01

    This thesis presents two attempts to improve the resolving power of the relaxation measurement technique. The first attempt reconsiders the old technique of steady state saturation. When used in conjunction with the pulse technique, it offers the possibility of obtaining additional information about the system in which all-time derivatives are zero; in addition, non-linear effects may be distinguished from each other. The second attempt involved a systematic study of only one system: Cu in the Tutton salts (K and Rb). The systematic approach, the high accuracy of the measurement and the sheer amount of experimental data for varying temperature, magnetic field and concentration made it possible in this case to separate the prevailing relaxation mechanisms reliably

  17. Comparison of different pulse sequences for in vivo determination of T1 relaxation times in the human brain

    DEFF Research Database (Denmark)

    Kjaer, L; Henriksen, O

    1988-01-01

    ). T1 measurements were performed on the human brain using a whole body MR scanner operating at 1.5 tesla. Three different pulse sequences were compared including two 6-points inversion recovery (IR) sequences with TR = 2.0 s and 4.0, respectively, and a 12-points partial saturation inversion recovery...

  18. A comparison of RNA folding measures

    Directory of Open Access Journals (Sweden)

    Gardner Paul P

    2005-10-01

    Full Text Available Abstract Background In the last few decades there has been a great deal of discussion concerning whether or not noncoding RNA sequences (ncRNAs fold in a more well-defined manner than random sequences. In this paper, we investigate several existing measures for how well an RNA sequence folds, and compare the behaviour of these measures over a large range of Rfam ncRNA families. Such measures can be useful in, for example, identifying novel ncRNAs, and indicating the presence of alternate RNA foldings. Results Our analysis shows that ncRNAs, but not mRNAs, in general have lower minimal free energy (MFE than random sequences with the same dinucleotide frequency. Moreover, even when the MFE is significant, many ncRNAs appear to not have a unique fold, but rather several alternative folds, at least when folded in silico. Furthermore, we find that the six investigated measures are correlated to varying degrees. Conclusion Due to the correlations between the different measures we find that it is sufficient to use only two of them in RNA folding studies, one to test if the sequence in question has lower energy than a random sequence with the same dinucleotide frequency (the Z-score and the other to see if the sequence has a unique fold (the average base-pair distance, D.

  19. A comparison of RNA folding measures

    DEFF Research Database (Denmark)

    Freyhult, E.; Gardner, P. P.; Moulton, V.

    2005-01-01

    the behaviour of these measures over a large range of Rfam ncRNA families. Such measures can be useful in, for example, identifying novel ncRNAs, and indicating the presence of alternate RNA foldings. Results Our analysis shows that ncRNAs, but not mRNAs, in general have lower minimal free energy (MFE) than....... Conclusion Due to the correlations between the different measures we find that it is sufficient to use only two of them in RNA folding studies, one to test if the sequence in question has lower energy than a random sequence with the same dinucleotide frequency (the Z-score) and the other to see......Background In the last few decades there has been a great deal of discussion concerning whether or not noncoding RNA sequences (ncRNAs) fold in a more well-defined manner than random sequences. In this paper, we investigate several existing measures for how well an RNA sequence folds, and compare...

  20. Comparison of cardiac output measurement techniques

    DEFF Research Database (Denmark)

    Espersen, K; Jensen, E W; Rosenborg, D

    1995-01-01

    Simultaneously measured cardiac output obtained by thermodilution (TD), transcutaneous suprasternal ultrasonic Doppler (DOP), CO2-rebreathing (CR) and the direct Fick method (FI) were compared in eleven healthy subjects in a supine position (SU), a sitting position (SI), and during sitting exercise...

  1. Devise for measuring the nuclear quadrupole resonance weak signal relaxation at the ISSh-1-12 spectrometer with the SIGMA digital storage

    International Nuclear Information System (INIS)

    Chernyavskij, V.N.; Konstantinov, G.I.

    1984-01-01

    The device, consisting of an analog memory device and the Karr-Parsell pulse programming device (radio frequency pulse train is 90 deg - tau - 180 deg - 2 tau - 180 deg - 2 tau ..., where tau is the interval between 90 deg - and 180 deg - pulses), is described. The device is destined for measurement of the time T 2 of nuclear quadrupole resonance spin-spin relaxation weak signal with signal-to-noise ratio 0 - 10 4 ), pulse numbers in series are 2-1024, start output signal amplitude >= 22 V, duration is 1 μs. The device may be also used in pulsed nuclear magnetic and electron paramagnetic resonance spectroscopy

  2. Measurement of solute proton spin-lattice relaxation times in water using the 1,3,3,1 sequence

    International Nuclear Information System (INIS)

    Sankar, S.S.; Mole, P.A.; Coulson, R.L.

    1986-01-01

    1 H NMR spin-lattice relaxation times (T1) of the N-CH3 proton resonances of phosphocreatine (PCr) and creatine (Cr) in water solutions were obtained using the 1,3,3,1 pulse sequence. These T1 values were equivalent to those obtained in D 2 O and water using either the conventional inversion-recovery experiment or the 1,3,3,1 pulse sequence. Thus, the 1,3,3,1 sequence of proton NMR can provide an independent means along with phosphorous NMR for assess PCr and for the study of the creatine kinase reaction (PCr + ADP in equilibrium ATP + Cr) in aqueous solutions and perhaps in biological preparations

  3. Comparison of two creativity style measures.

    Science.gov (United States)

    Houtz, John C; Selby, Edwin; Esquivel, Giselle B; Okoye, Ruth A; Peters, Kristen M; Treffinger, Donald J

    2003-02-01

    The purpose of this study was to examine the relation between two measures of creativity style for a sample of beginning teachers. 116 student teachers enrolled in an undergraduate teacher-education program in a medium-sized, metropolitan university completed the Kirton Adaption-Innovation Inventory and Basadur Creative Problem Solving Profile measures. A preference for an Innovator style (higher scores on Kirton's inventory) was correlated with the Generator profile on the Basadur profile (r=.36, p<.01). The KAI Efficiency scores, suggesting a preference for broad, global ideas as opposed to narrow, specific ones, was correlated with the Basadur Conceptualizer scores (r=.26, p<.01). Implications are discussed for teachers who must adapt to newer instructional and assessment methods designed to foster students' higher-level thinking skills.

  4. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

    Science.gov (United States)

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

  5. Measuring situation awareness in complex systems: Comparison of measures study

    OpenAIRE

    Salmon, PM; Stanton, NA; Walker, GH; Jenkins, DP; Ladva, D; Rafferty, L; Young, MS

    2008-01-01

    Situation Awareness (SA) is a distinct critical commodity for teams working in complex industrial systems and its measurement is a key provision in system, procedural and training design efforts. This article describes a study that was undertaken in order to compare three different SA measures (a freeze probe recall approach, a post trial subjective rating approach and a critical incident interview technique) when used to assess participant SA during a military planning task. The results indi...

  6. Time course of action and endotracheal intubating conditions of Org 9487, a new short-acting steroidal muscle relaxant; a comparison with succinylcholine

    NARCIS (Netherlands)

    Wierda, JMKH; van den Broek, L; Proost, JH; Verbaan, BW; Hennis, PJ

    In a randomized study, we evaluated lag time (time from the end of injection of muscle relaxant until the first depression of the train-of-four response [TOF]), onset time (time from the end of injection of muscle relaxant until the maximum depression of the first twitch of the TOF [T1]),

  7. The relationships between suggestibility, influenceability, and relaxability.

    Science.gov (United States)

    Polczyk, Romuald; Frey, Olga; Szpitalak, Malwina

    2013-01-01

    This research explores the relationships between relaxability and various aspects of suggestibility and influenceability. The Jacobson Progressive Muscle Relaxation procedure was used to induce relaxation. Tests of direct suggestibility, relating to the susceptibility of overt suggestions, and indirect suggestibility, referring to indirect hidden influence, as well as self-description questionnaires on suggestibility and the tendency to comply were used. Thayer's Activation-Deactivation Adjective Check List, measuring various kinds of activation and used as a pre- and posttest, determined the efficacy of the relaxation procedure. Indirect, direct, and self-measured suggestibility proved to be positively related to the ability to relax, measured by Thayer's subscales relating to emotions. Compliance was not related to relaxability. The results are discussed in terms of the aspects of relaxation training connected with suggestibility.

  8. Relaxation property of the fractional Brownian particle

    International Nuclear Information System (INIS)

    Wang Litan; Lung, C.W.

    1988-08-01

    Dynamic susceptibility of a diffusion system associated with the fractional Brownian motion (fBm) was examined for the fractal property of the Non-Debye relaxation process. The comparisons between fBm and other approaches were made. Anomalous diffusion and the Non-Debye relaxation processes were discussed with this approach. (author). 8 refs, 1 fig

  9. Comparison of microstickies measurement methods. Part I, sample preparation and measurement methods

    Science.gov (United States)

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

    2003-01-01

    Recently, we completed a project on the comparison of macrostickies measurement methods. Based on the success of the project, we decided to embark on this new project on comparison of microstickies measurement methods. When we started this project, there were some concerns and doubts principally due to the lack of an accepted definition of microstickies. However, we...

  10. 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)

  11. 31P and 1H NMR studies of the structure of enzyme-bound substrate complexes of lobster muscle arginine kinase: Relaxation measurements with Mn(II) and Co(II)

    International Nuclear Information System (INIS)

    Jarori, G.K.; Ray, B.D.; Rao, B.D.N.

    1989-01-01

    The paramagnetic effects of Mn(II) and Co(II) on the spin-lattice relaxation rates of 31 P nuclei of ATP and ADP and of Mn(II) on the spin-lattice relaxation rate of the δ protons of arginine bound to arginine kinase from lobster tail muscle have been measured. Temperature variation of 31 P relaxation rates in E-MnADP and E-MnATP yields activation energies (ΔE) in the range 6-10 kcal/mol. Thus, the 31 P relaxation rates in these complexes are exchange limited and cannot provide structural information. However, the relaxation rates in E-CoADP and E-CoATP exhibit frequency dependence and ΔE values in the range 1-2 kcal/mol; i.e., these rates depend upon 31 P-Co(II) distances. These distances were calculated to be in the range 3.2-4.5 angstrom, appropriate for direct coordination between Co(II) and the phosphoryl groups. The paramagnetic effect of Mn(II) on the 1 H spin-lattice relaxation rate of the δ protons of arginine in the E-MnADP-Arg complex was also measured at three frequencies. From the frequency dependence of the relaxation rate an effective τ C of 0.6 ns has also been calculated, which is most likely to be the electron spin relaxation rate (τ S1 ) for Mn(II) in this complex. The distance estimated on the basis of the reciprocal sixth root of the average relaxation rate of the δ protons was 10.9 ± 0.3 angstrom

  12. International price comparisons for pharmaceuticals. Measurement and policy issues.

    Science.gov (United States)

    Danzon, P M; Kim, J D

    1998-01-01

    Cross-national price comparisons for pharmaceuticals are commonly used for two purposes. Comparisons based on a sample of products are used to draw conclusions about differences in average price levels. Cross-national comparisons applied to individual products are also used by governments to set domestic prices. This paper examines the major methodological issues raised by international price comparisons, focusing on measurement of differences in average price levels and the validity of policy conclusions drawn from such price comparison studies. It argues that valid measures of average price levels can only be obtained from comparisons based on a comprehensive or representative sample of products, appropriately weighted, following standard index number methods. Comparisons of individual product prices should take into account the manufacturer's entire product portfolio over time rather than focus narrowly on a single product at a point in time. Because of the great variation across countries in both the range of drug compounds available and the dosage forms, strengths and pack sizes for each compound, obtaining a broadly comprehensive or representative sample is problematical. If products are required to match on all dimensions, including molecule, manufacturer, strength and pack, as is common in most international price comparisons, then only a very small and unrepresentative sample of the drugs available in each country can be included in the analysis. A trade-off between the desire to compare only identical products and the need to compare a truly representative sample of a country's pharmaceutical market is therefore necessary. A valid comparison of average drug prices should include generics and over-the-counter products that are good substitutes for branded prescription drugs, with all forms, strengths and packs. To achieve this broad representation, however, the requirements of same manufacturer, same brand, dosage form, strength and pack size must be

  13. Bilateral Comparison CIEMAT-CENTIS-DMR for radionuclide activity measurements

    International Nuclear Information System (INIS)

    Oropesa Verdecia, P.; Garcia-Torano, E.

    2004-01-01

    We present the results of a bilateral comparison of radionuclide activity measurements between the Radionuclide Metrology Department of the Center of Isotopes of Cuba (CENTIS-DMR), and the Ionising Radiation Metrology Laboratory (LMRI) of the Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT) of Spain. The aim of the comparison was to establish the comparability of the measurement instruments and methods used to obtain radioactive reference materials of some gamma-emitting nuclides at CENTIS-DMR. The results revealed that there are no statistically significant differences between the data reported by both laboratories. (Author) 7 refs

  14. Enhanced atomic mobility due to low dose neutron irradiation as measured in a 30Ag at % Zn alloy by Zener relaxation methods

    International Nuclear Information System (INIS)

    Halbwachs, M.; Hillairet, J.; Gonzalez, H.; Cost, J.

    1975-01-01

    Mean atomic jump rates were measured during and after short-time neutron irradiations of a fcc Ag-30 at. percent Zn alloy by monitoring the rate of the Zener relaxation. Measurements made at 40 0 C immediately after rapid suppression of the flux showed significant enhancement of the atomic mobility for a flux of approximately 10 11 fast n/cm 2 .sec and an irradiation time of only 30 sec. The subsequent decrease of the atomic mobility to the thermal equilibrium value was studied and found to follow simple exponential decay. The results are discussed in terms of the nature and concentration of mobile defects created by cascades, the mechanism for defect annihilation and the concentration of sinks

  15. Pressure dependence of thermal conductivity and specific heat in CeRh2Si2 measured by an extended thermal relaxation method

    Science.gov (United States)

    Nishigori, Shijo; Seida, Osamu

    2018-05-01

    We have developed a new technique for measuring thermal conductivity and specific heat under pressure by improving a thermal relaxation method. In this technique, a cylindrical sample with a small disc heater is embedded in the pressure-transmitting medium, then temperature variations of the sample and heater were directly measured by thermocouples during a heating and cooling process. Thermal conductivity and specific heat are estimated by comparing the experimental data with temperature variations simulated by a finite element method. The obtained thermal conductivity and specific heat of the test sample CeRh2Si2 exhibit a small enhancement and a clear peak arising from antiferromagnetic transition, respectively. The observation of these typical behaviors for magnetic compounds indicate that the technique is valid for the study on thermal properties under pressure.

  16. Comparison of different methods for thoron progeny measurement

    International Nuclear Information System (INIS)

    Bi Lei; Zhu Li; Shang Bing; Cui Hongxing; Zhang Qingzhao

    2009-01-01

    Four popular methods for thoron progeny measurement were discussed, including the aspects of detector,principle, precondition, calculation advantages and disadvantages. Comparison experiments were made in mine and houses with high background in Yunnan Province. Since indoor thoron progeny changes with time obviously and with no rule, α track method is recommended in the area of radiation protection for environmental detection and assessment. (authors)

  17. Measurement of the Relaxation Rate of the Magnetization in Mn{sub 12}O{sub 12} -Acetate Using Proton NMR Echo

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Z. H. [Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Lascialfari, A. [Dipartimento di Fisica ' ' A. Volta' ' e Unita' , INFM di Pavia, Via Bassi 6, 27100 Pavia, (Italy); Borsa, F. [Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Dipartimento di Fisica ' ' A. Volta' ' e Unita' , INFM di Pavia, Via Bassi 6, 27100 Pavia, (Italy); Gatteschi, D. [Department of Chemistry, University of Florence, Via Maragliano 77, 50144 Firenze, (Italy)

    2000-03-27

    We present a novel method to measure the relaxation rate W of the magnetization of Mn{sub 12}O {sub 12} -acetate (Mn12) magnetic molecular cluster in its S=10 ground state at low T . It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions. (c) 2000 The American Physical Society.

  18. The inverted chevron plot measured by NMR relaxation reveals a native-like unfolding intermediate in acyl-CoA binding protein

    DEFF Research Database (Denmark)

    Teilum, Kaare; Poulsen, F. M.; Akke, M.

    2006-01-01

    those from stopped-flow kinetics and define an "inverted chevron" plot. The combination of NMR relaxation and stopped-flow kinetic measurements allowed determination of k f and k u in the range from 0.48 M GuHCl to 1.28 M GuHCl. Individually, the stopped-flow and NMR data fit two-state models...... for folding. However, although the values of k f determined by the two methods agree, the values of k u do not. As a result, a combined analysis of all data does not comply with a two-state model but indicates that an unfolding intermediate exists on the native side of the dominant energy barrier...

  19. MCNP6.1 simulations for low-energy atomic relaxation: Code-to-code comparison with GATEv7.2, PENELOPE2014, and EGSnrc

    Science.gov (United States)

    Jung, Seongmoon; Sung, Wonmo; Lee, Jaegi; Ye, Sung-Joon

    2018-01-01

    Emerging radiological applications of gold nanoparticles demand low-energy electron/photon transport calculations including details of an atomic relaxation process. Recently, MCNP® version 6.1 (MCNP6.1) has been released with extended cross-sections for low-energy electron/photon, subshell photoelectric cross-sections, and more detailed atomic relaxation data than the previous versions. With this new feature, the atomic relaxation process of MCNP6.1 has not been fully tested yet with its new physics library (eprdata12) that is based on the Evaluated Atomic Data Library (EADL). In this study, MCNP6.1 was compared with GATEv7.2, PENELOPE2014, and EGSnrc that have been often used to simulate low-energy atomic relaxation processes. The simulations were performed to acquire both photon and electron spectra produced by interactions of 15 keV electrons or photons with a 10-nm-thick gold nano-slab. The photon-induced fluorescence X-rays from MCNP6.1 fairly agreed with those from GATEv7.2 and PENELOPE2014, while the electron-induced fluorescence X-rays of the four codes showed more or less discrepancies. A coincidence was observed in the photon-induced Auger electrons simulated by MCNP6.1 and GATEv7.2. A recent release of MCNP6.1 with eprdata12 can be used to simulate the photon-induced atomic relaxation.

  20. Diastolic Function in Normal Sinus Rhythm vs. Chronic Atrial Fibrillation: Comparison by Fractionation of E-wave Deceleration Time into Stiffness and Relaxation Components.

    Science.gov (United States)

    Mossahebi, Sina; Kovács, Sándor J

    2014-01-01

    Although the electrophysiologic derangement responsible for atrial fibrillation (AF) has been elucidated, how AF remodels the ventricular chamber and affects diastolic function (DF) has not been fully characterized. The previously validated Parametrized Diastolic Filling (PDF) formalism models suction-initiated filling kinematically and generates error-minimized fits to E-wave contours using unique load (x o ), relaxation (c), and stiffness (k) parameters. It predicts that E-wave deceleration time (DT) is a function of both stiffness and relaxation. Ascribing DT s to stiffness and DTr to relaxation such that DT=DT s +DT r is legitimate because of causality and their predicted and observed high correlation (r=0.82 and r=0.94) with simultaneous (diastatic) chamber stiffness (dP/dV) and isovolumic relaxation (tau), respectively. We analyzed simultaneous echocardiography-cardiac catheterization data and compared 16 age matched, chronic AF subjects to 16, normal sinus rhythm (NSR) subjects (650 beats). All subjects had diastatic intervals. Conventional DF parameters (DT, AT, E peak , E dur , E-VTI, E/E') and E-wave derived PDF parameters (c, k, DT s , DT r ) were compared. Total DT and DT s , DT r in AF were shorter than in NSR (pwave DT in AF is due to stiffness compared to NSR. By trending individual subjects, this method can elucidate and characterize the beneficial or adverse long-term effects on chamber remodeling due to alternative therapies in terms of chamber stiffness and relaxation.

  1. Assessment of quality of measurement results in interlaboratory comparisons

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Matel, L.; Rajec, P.

    2009-01-01

    Testing laboratory accredited according to ISO/IEC 17025:2005 has to ensure the quality of their results. Important aspect of correct evaluation of the result is the accuracy and uncertainty. Requirement of ISO/IEC 17025:2005 is the accredited laboratories to express their results with the corresponding uncertainty. Participation of laboratories in interlaboratory comparisons provides objective evidence of the level of reliability and quality of their results. Thereby the competency of accredited laboratories verified, including the verification of the declared measurement uncertainty. Some interlaboratory comparisons in which took participation the Testing Laboratory of Radiochemical Analysis (LARCHA) are presented.

  2. Breathing and Relaxation

    Science.gov (United States)

    ... Find a Doctor Relaxation is the absence of tension in muscle groups and a minimum or absence ... Drill Meditation Progressive Muscle Relaxation Minimizing Shortness of Breath Visualization This information has been approved by Shelby ...

  3. Measurement of alveolar oxygen partial pressure in the rat lung using Carr-Purcell-Meiboom-Gill spin-spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT.

    Science.gov (United States)

    Kraayvanger, Ryan J; Bidinosti, Christopher P; Dominguez-Viqueira, William; Parra-Robles, Juan; Fox, Matthew; Lam, Wilfred W; Santyr, Giles E

    2010-11-01

    Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, (3) He and (129) Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R(2) ) of (3) He at low magnetic field strengths (oxygen partial pressure measurements based on Carr-Purcell-Meiboom-Gill R(2) values of hyperpolarized (3) He and (129) Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for (3) He and (129) Xe were determined to be (5.2 ± 0.6) × 10(-6) Pa(-1) sec(-1) and (7.3 ± 0.4) × 10(-6) Pa(-1) s(-1) compared with spin-lattice relaxivity constants of (4.0 ± 0.4) × 10(-6) Pa(-1) s(-1) and (4.3 ± 1.3) × 10(-6) Pa(-1) s(-1), respectively. In vivo experimental measurements of alveolar oxygen partial pressure using (3) He in whole rat lung show good agreement (r(2) = 0.973) with predictions based on lung volumes and ventilation parameters. For (129) Xe, multicomponent relaxation was observed with one component exhibiting an increase in R(2) with decreasing alveolar oxygen partial pressure. Copyright © 2010 Wiley-Liss, Inc.

  4. Comparison of simulated and measured quantities of a duplex reactor

    Energy Technology Data Exchange (ETDEWEB)

    Koskela, M.; Kajava, M. [ABB Marine, Helsinki (Finland)

    1997-12-31

    The purpose of this article is to illustrate the use of an analog simulator as a design tool when designing new power electric equipment. The purpose of simulation is to predict the functionality of electrical equipment to be constructed. Duplex reactor is an electromagnetic device designed to reduce voltage harmonics and short circuit currents in the ship electrical network. In this report a comparison between simulated and measured electrical quantities of a duplex reactor has been made. The purpose of the measurements was to show the correct functioning of the reactor. The simulation results and the measured waveforms corresponds well to each other. (orig.) 4 refs.

  5. SUPPLEMENTARY COMPARISON: EUROMET.L-S10 Comparison of squareness measurements

    Science.gov (United States)

    Mokros, Jiri

    2005-01-01

    The idea of performing a comparison of squareness resulted from the need to review the MRA Appendix C, Category 90° square. At its meeting in October 1999 (in Prague) it was decided upon a first comparison of squareness measurements in the framework of EUROMET, numbered #570, starting in 2000, with the Slovak Institute of Metrology (SMU) as the pilot laboratory. During the preparation stage of the project, it was agreed that it should be submitted as a EUROMET supplementary comparison in the framework of the Mutual Recognition Arrangement (MRA) of the Metre Convention and would boost confidence in calibration and measurement certificates issued by the participating national metrology institutes. The aim of the comparison of squareness measurement was to compare and verify the declared calibration measurement capabilities of participating laboratories and to investigate the effect of systematic influences in the measurement process and their elimination. Eleven NMIs from the EUROMET region carried out this project. Two standards were calibrated: granite squareness standard of rectangular shape, cylindrical squareness standard of steel with marked positions for the profile lines. The following parameters had to be calibrated: granite squareness standard: interior angle γB between two lines AB and AC (envelope - LS regression) fitted through the measured profiles, and/or granite squareness standard: interior angle γLS between two LS regression lines AB and AC fitted through the measured profiles, cylindrical squareness standard: interior angles γ0°, γ90°, γ180°, γ270° between the LS regression line fitted through the measurement profiles at 0°, 90°, 180°, 270° and the envelope plane of the basis (resting on a surface plate), local LS straightness deviation for all measured profiles (2 and 4) of both standards. The results of the comparison are the deviations of profiles and angles measured by the individual NMIs from the reference values. These resulted

  6. Recent activity of international comparison for nanoparticle size measurement

    Science.gov (United States)

    Takahashi, Kayori; Takahata, Keiji; Misumi, Ichiko; Sugawara, Kentaro; Gonda, Satoshi; Ehara, Kensei

    2014-08-01

    Nanoparticle sizing is the most fundamental measurement for producing nanomaterials, evaluation of nanostructure, and the risk assessment of nanomaterials for human health. Dynamic light scattering (DLS) is widely used as a useful and convenient technique for determining nanoparticle size in liquid; however, the precision of this technique has been unclear. Some international comparisons are now in progress to verify the measurement accuracy of nanoparticle sizing, as a typical example of Asia Pacific Metrology Programme Supplementary Comparison. In this study, we evaluated the precision of DLS technique for nanoparticle sizing and estimated the uncertainty of the DLS data for polystyrene latex suspensions. The extrapolations of apparent diffusion coefficients to infinite dilution and to lower angles yielded more precise values than those obtained at one angle and one concentration. The extrapolated particle size measured by DLS was compared to the size determined by differential mobility analyzer (DMA), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Before the comparison, the intensity-averaged size measured by DLS was recalculated to the number-averaged size, and the thickness of water layer attaching on the surface of particles were added into uncertainty of particle sizing by DLS. After the recalculation, the consistent values of mean particle diameter were obtained between those by DLS and by DMA, AFM, and SEM within the estimated uncertainties.

  7. Structural relaxation in annealed hyperquenched basaltic glasses

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, John C.; Potuzak, M.

    2012-01-01

    The enthalpy relaxation behavior of hyperquenched (HQ) and annealed hyperquenched (AHQ) basaltic glass is investigated through calorimetric measurements. The results reveal a common onset temperature of the glass transition for all the HQ and AHQ glasses under study, indicating that the primary...... relaxation is activated at the same temperature regardless of the initial departure from equilibrium. The analysis of secondary relaxation at different annealing temperatures provides insights into the enthalpy recovery of HQ glasses....

  8. Detailed comparison between computed and measured FBR core seismic responses

    International Nuclear Information System (INIS)

    Forni, M.; Martelli, A.; Melloni, R.; Bonacina, G.

    1988-01-01

    This paper presents a detailed comparison between seismic calculations and measurements performed for various mock-ups consisting of groups of seven and nineteen simplified elements of the Italian PEC fast reactor core. Experimental tests had been performed on shaking tables in air and water (simulating sodium) with excitations increasing up to above Safe Shutdown Earthquake. The PEC core-restraint ring had been simulated in some tests. All the experimental tests have been analysed by use of both the one-dimensional computer program CORALIE and the two-dimensional program CLASH. Comparisons have been made for all the instrumented elements, in both the time and the frequency domains. The good agreement between calculations and measurements has confirmed adequacy of the fluid-structure interaction model used for PEC core seismic design verification

  9. Bovine spongiform encephalopathy: is it time to relax BSE-related measures in the context of international trade?

    Science.gov (United States)

    Matthews, D; Adkin, A

    2011-04-01

    Bovine spongiform encephalopathy (BSE) has presented serious challenges to both the World Organisation for Animal Health and national governments, in defining and implementing appropriate national control measures, and in agreeing trade rules that permit safe trade in cattle and bovine products. Precautionary trade rules were initially necessary, based upon the science of sheep scrapie, but research into BSE later enabled BSE-specific trade rules to be developed. As a result, current rules on trade are underpinned by a sound body of knowledge on BSE. Declining epidemics in most affected countries confirm the appropriateness of current precautions. Nevertheless, risk is primarily dependent on the prevalence of infection with BSE. In the face of low prevalence scenarios, certain precautionary measures in the Terrestrial Animal Health Code may now be considered excessive. A thorough review is therefore deemed appropriate.

  10. National comparison on volume sample activity measurement methods

    International Nuclear Information System (INIS)

    Sahagia, M.; Grigorescu, E.L.; Popescu, C.; Razdolescu, C.

    1992-01-01

    A national comparison on volume sample activity measurements methods may be regarded as a step toward accomplishing the traceability of the environmental and food chain activity measurements to national standards. For this purpose, the Radionuclide Metrology Laboratory has distributed 137 Cs and 134 Cs water-equivalent solid standard sources to 24 laboratories having responsibilities in this matter. Every laboratory has to measure the activity of the received source(s) by using its own standards, equipment and methods and report the obtained results to the organizer. The 'measured activities' will be compared with the 'true activities'. A final report will be issued, which plans to evaluate the national level of precision of such measurements and give some suggestions for improvement. (Author)

  11. Continuous Flow Hygroscopicity-Resolved Relaxed Eddy Accumulation (Hy-Res REA) Method of Measuring Size-Resolved Sea-Salt Particle Fluxes

    Science.gov (United States)

    Meskhidze, N.; Royalty, T. M.; Phillips, B.; Dawson, K. W.; Petters, M. D.; Reed, R.; Weinstein, J.; Hook, D.; Wiener, R.

    2017-12-01

    The accurate representation of aerosols in climate models requires direct ambient measurement of the size- and composition-dependent particle production fluxes. Here we present the design, testing, and analysis of data collected through the first instrument capable of measuring hygroscopicity-based, size-resolved particle fluxes using a continuous-flow Hygroscopicity-Resolved Relaxed Eddy Accumulation (Hy-Res REA) technique. The different components of the instrument were extensively tested inside the US Environmental Protection Agency's Aerosol Test Facility for sea-salt and ammoniums sulfate particle fluxes. The new REA system design does not require particle accumulation, therefore avoids the diffusional wall losses associated with long residence times of particles inside the air collectors of the traditional REA devices. The Hy-Res REA system used in this study includes a 3-D sonic anemometer, two fast-response solenoid valves, two Condensation Particle Counters (CPCs), a Scanning Mobility Particle Sizer (SMPS), and a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA). A linear relationship was found between the sea-salt particle fluxes measured by eddy covariance and REA techniques, with comparable theoretical (0.34) and measured (0.39) proportionality constants. The sea-salt particle detection limit of the Hy-Res REA flux system is estimated to be 6x105 m-2s-1. For the conditions of ammonium sulfate and sea-salt particles of comparable source strength and location, the continuous-flow Hy-Res REA instrument was able to achieve better than 90% accuracy of measuring the sea-salt particle fluxes. In principle, the instrument can be applied to measure fluxes of particles of variable size and distinct hygroscopic properties (i.e., mineral dust, black carbon, etc.).

  12. Accurate determination of rates from non-uniformly sampled relaxation data

    Energy Technology Data Exchange (ETDEWEB)

    Stetz, Matthew A.; Wand, A. Joshua, E-mail: wand@upenn.edu [University of Pennsylvania Perelman School of Medicine, Johnson Research Foundation and Department of Biochemistry and Biophysics (United States)

    2016-08-15

    The application of non-uniform sampling (NUS) to relaxation experiments traditionally used to characterize the fast internal motion of proteins is quantitatively examined. Experimentally acquired Poisson-gap sampled data reconstructed with iterative soft thresholding are compared to regular sequentially sampled (RSS) data. Using ubiquitin as a model system, it is shown that 25 % sampling is sufficient for the determination of quantitatively accurate relaxation rates. When the sampling density is fixed at 25 %, the accuracy of rates is shown to increase sharply with the total number of sampled points until eventually converging near the inherent reproducibility of the experiment. Perhaps contrary to some expectations, it is found that accurate peak height reconstruction is not required for the determination of accurate rates. Instead, inaccuracies in rates arise from inconsistencies in reconstruction across the relaxation series that primarily manifest as a non-linearity in the recovered peak height. This indicates that the performance of an NUS relaxation experiment cannot be predicted from comparison of peak heights using a single RSS reference spectrum. The generality of these findings was assessed using three alternative reconstruction algorithms, eight different relaxation measurements, and three additional proteins that exhibit varying degrees of spectral complexity. From these data, it is revealed that non-linearity in peak height reconstruction across the relaxation series is strongly correlated with errors in NUS-derived relaxation rates. Importantly, it is shown that this correlation can be exploited to reliably predict the performance of an NUS-relaxation experiment by using three or more RSS reference planes from the relaxation series. The RSS reference time points can also serve to provide estimates of the uncertainty of the sampled intensity, which for a typical relaxation times series incurs no penalty in total acquisition time.

  13. CdZnTe quantum dots study: energy and phase relaxation process

    International Nuclear Information System (INIS)

    Viale, Yannick

    2004-01-01

    We present a study of the electron-hole pair energy and phase relaxation processes in a CdTe/ZnTe heterostructure, in which quantum dots are embedded. CdZnTe quantum wells with a high Zinc concentration, separated by ZnTe barriers, contain islands with a high cadmium concentration. In photoluminescence excitation spectroscopy experiments, we evidence two types of electron hole pair relaxation processes. After being excited in the CdZnTe quantum well, the pairs relax their energy by emitting a cascade of longitudinal optical phonons until they are trapped in the quantum dots. Before their radiative recombination follows an intra-dot relaxation, which is attributed to a lattice polarization mechanism of the quantum dots. It is related to the coupling between the electronic and the vibrational states. Both relaxation mechanisms are reinforced by the strong polar character of the chemical bond in II-VI compounds. Time resolved measurements of transmission variations in a pump-probe configuration allowed us to investigate the population dynamics of the electron-hole pairs during the relaxation process. We observe a relaxation time of about 2 ps for the longitudinal phonon emission cascade in the quantum well before a saturation of the quantum dot transition. We also measured an intra-box relaxation time of 25 ps. The comparison of various cascades allows us to estimate the emission time of a longitudinal optical phonon in the quantum well to be about 100 fs. In four waves mixing experiments, we observe oscillations that we attribute to quantum beats between excitonic and bi-excitonic transitions. The dephasing times that we measure as function of the density of photons shows that excitons are strongly localized in the quantum dots. The excitonic dephasing time is much shorter than the radiative lifetime and is thus controlled by the intra-dot relaxation time. (author) [fr

  14. A comparison of new measurements of total monoterpene flux with improved measurements of speciated monoterpene flux

    Directory of Open Access Journals (Sweden)

    A. Lee

    2005-01-01

    Full Text Available Many monoterpenes have been identified in forest emissions using gas chromatography (GC. Until now, it has been impossible to determine whether all monoterpenes are appropriately measured using GC techniques. We used a proton transfer reaction mass spectrometer (PTR-MS coupled with the eddy covariance (EC technique to measure mixing ratios and fluxes of total monoterpenes above a ponderosa pine plantation. We compared PTR-MS-EC results with simultaneous measurements of eight speciated monoterpenes, β-pinene, α-pinene, 3-carene, d-limonene, β-phellandrene, α-terpinene, camphene, and terpinolene, made with an automated, in situ gas chromatograph with flame ionization detectors (GC-FID, coupled to a relaxed eddy accumulation system (REA. Monoterpene mixing ratios and fluxes measured by PTR-MS averaged 30±2.3% and 31±9.2% larger than by GC-FID, with larger mixing ratio discrepancies between the two techniques at night than during the day. Two unidentified peaks that correlated with β-pinene were resolved in the chromatograms and completely accounted for the daytime difference and reduced the nighttime mixing ratio difference to 20±2.9%. Measurements of total monoterpenes by PTR-MS-EC indicated that GC-FID-REA measured the common, longer-lived monoterpenes well, but that additional terpenes were emitted from the ecosystem that represented an important contribution to the total mixing ratio above the forest at night.

  15. Collisional relaxation of electron tail distribution

    International Nuclear Information System (INIS)

    Yamagiwa, Mitsuru; Okamoto, Masao.

    1985-05-01

    Relaxation due to the Coulomb collisions of the electron velocity distribution function with a high energy tail is investigated in detail. In the course of the relaxation, a 'saddle' point can be created in velocity space owing to upsilon -3 dependence of the deflection rate and a positive slope or a 'dip' appears in the tail direction. The time evolution of the electron tail is studied analytically. A comparison is made with numerical results by using a Fokker-Planck code. Also discussed is the kinetic instability concerned with the positive slope during the relaxation. (author)

  16. The effects of progressive muscle relaxation and autogenic relaxation on young soccer players' mood states.

    Science.gov (United States)

    Hashim, Hairul Anuar; Hanafi Ahmad Yusof, Hazwani

    2011-06-01

    This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players' mood states.

  17. The Effects of Progressive Muscle Relaxation and Autogenic Relaxation on Young Soccer Players’ Mood States

    Science.gov (United States)

    Hashim, Hairul Anuar; Hanafi@Ahmad Yusof, Hazwani

    2011-01-01

    Purpose This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. Methods Sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Results Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. Conclusion These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players’ mood states. PMID:22375225

  18. Self-Active Relaxation Therapy (SART) and Self-Regulation: A Comprehensive Review and Comparison of the Japanese Body Movement Approach

    Science.gov (United States)

    Kabir, Russell S.; Haramaki, Yutaka; Ki, Hyeyoung; Ohno, Hiroyuki

    2018-01-01

    Relaxation programs are known for their versatility, cost-effectiveness, and ability to help people obtain skills to regulate their mental states and promote and maintain health. Self-Active Relaxation Therapy (SART) is a body-oriented approach to psychological rehabilitation that grew out of the suite of movement tasks developed in the Japanese psychotherapy known as Dohsa-hou, or the body movement method. The program for SART is designed to stretch, twist, and release areas of the upper, lower, and whole body through a set of movements which are guided by the practitioner and performed “self-actively” by the client to empower them to learn to recognize points of tension in the body and act on their own to achieve a relaxed state. Numerous studies have showed that SART is associated with reduced negative mood states and enhanced body awareness. A short version of SART has been investigated as a psychological support salon activity for the elderly, mothers raising children, special needs students, and children adapting to school. The full program has also been applied in clinical settings to address or supplement treatments for psychological and developmental conditions, and longitudinally employed in community contexts to assist residents facing long-term disaster recovery circumstances in Japan. This paper reviews the research and applications of SART as a bodymind approach by critically examining evidence and research gaps for future studies, comparing it with techniques established in the literature, and positing a self-regulatory framework for SART as a tool to become aware of bodily states, regulate mood, and manage stress through the deliberate practice of relaxation. PMID:29472851

  19. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies...

  20. Comparison of quality of life measures in a depressed population.

    Science.gov (United States)

    Wisniewski, Stephen R; Rush, A John; Bryan, Charlene; Shelton, Richard; Trivedi, Madhukar H; Marcus, Sheila; Husain, Mustafa M; Hollon, Steven D; Fava, Maurizio

    2007-03-01

    Measures of quality of life have been increasingly used in clinical trials. When designing a study, researchers must decide which quality of life measure to use. Some literature provides guidance through general recommendations, though lacks quantitative comparisons. In this report, 2 general quality of life measures, the 12-Item Short Form Health Survey (SF-12) and the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q), are compared in a depressed population. STAR*D data were used to analyze the associations among the SF-12 and the Q-LES-Q. Each measure covers 6 domains, overlapping on 5 (health, self-esteem/well-being, community/productivity, social/love relationships, leisure/creativity), with the SF-12 addressing family and the Q-LES-Q addressing living situations. Strong item-by-item associations exist only between the Q-LES-Q and the SF-12 physical health items. The 2 measures overlap on the domains covered while the lack of correlation between the 2 measures may be attributed to the perspective of each question as the Q-LES-Q measures satisfaction while the SF-12 measures the patient's perception of function.

  1. Comparison of Thermal Properties Measured by Different Methods

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, Jan [Geo Innova AB, Linkoeping (Sweden); Kukkonen, Ilmo [Geological Survey of Finland, Helsinki (Finland); Haelldahl, Lars [Hot Disk AB, Uppsala (Sweden)

    2003-04-01

    A strategy for a thermal site descriptive model of bedrock is under development at SKB. In the model different kinds of uncertainties exist. Some of these uncertainties are related to the potential errors in the methods used for determining thermal properties of rock. In two earlier investigations thermal properties of rock samples were analysed according to the TPS method (transient plane source). Thermal conductivity and thermal diffusivity were determined using the TPS method. For a comparison, the same samples have been measured at the Geological Survey of Finland (GSF), using different laboratory methods. In this later investigation, the thermal conductivity was determined using the divided-bar method and the specific heat capacity using a calorimetric method. The mean differences between the results of different methods are relatively low but the results of individual samples show large variations. The thermal conductivity measured by the divided bar method gives for most samples slightly higher values, in average about 3%, than the TPS method. The specific heat capacity measured by the calorimetric method gives lower values, in average about 2%, than the TPS method. Consequently, the thermal diffusivity calculated from thermal conductivity and specific heat capacity gives higher values, in average about 6%, than the TPS method. Reasons for the differences are estimated mainly to be dependent on differences between the samples, errors in the temperature dependence of specific heat and in the transformation from volumetric to specific heat. The TPS measurements are performed using two pieces (sub-samples) of rock. Only one of these two sub-samples was measured using the divided bar method and the calorimetric method. Further, sample preparation involved changes in the size of some of the samples. The mean differences between the results of different methods are within the margins of error reported by the measuring laboratories. However, systematic errors in

  2. Comparison of Thermal Properties Measured by Different Methods

    International Nuclear Information System (INIS)

    Sundberg, Jan; Kukkonen, Ilmo; Haelldahl, Lars

    2003-04-01

    A strategy for a thermal site descriptive model of bedrock is under development at SKB. In the model different kinds of uncertainties exist. Some of these uncertainties are related to the potential errors in the methods used for determining thermal properties of rock. In two earlier investigations thermal properties of rock samples were analysed according to the TPS method (transient plane source). Thermal conductivity and thermal diffusivity were determined using the TPS method. For a comparison, the same samples have been measured at the Geological Survey of Finland (GSF), using different laboratory methods. In this later investigation, the thermal conductivity was determined using the divided-bar method and the specific heat capacity using a calorimetric method. The mean differences between the results of different methods are relatively low but the results of individual samples show large variations. The thermal conductivity measured by the divided bar method gives for most samples slightly higher values, in average about 3%, than the TPS method. The specific heat capacity measured by the calorimetric method gives lower values, in average about 2%, than the TPS method. Consequently, the thermal diffusivity calculated from thermal conductivity and specific heat capacity gives higher values, in average about 6%, than the TPS method. Reasons for the differences are estimated mainly to be dependent on differences between the samples, errors in the temperature dependence of specific heat and in the transformation from volumetric to specific heat. The TPS measurements are performed using two pieces (sub-samples) of rock. Only one of these two sub-samples was measured using the divided bar method and the calorimetric method. Further, sample preparation involved changes in the size of some of the samples. The mean differences between the results of different methods are within the margins of error reported by the measuring laboratories. However, systematic errors in

  3. Assessment and comparison of methods for solar ultraviolet radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Leszczynski, K

    1995-06-01

    In the study, the different methods to measure the solar ultraviolet radiation are compared. The methods included are spectroradiometric, erythemally weighted broadband and multi-channel measurements. The comparison of the different methods is based on a literature review and assessments of optical characteristics of the spectroradiometer Optronic 742 of the Finnish Centre for Radiation and Nuclear Safety (STUK) and of the erythemally weighted Robertson-Berger type broadband radiometers Solar Light models 500 and 501 of the Finnish Meteorological Institute and STUK. An introduction to the sources of error in solar UV measurements, to methods for radiometric characterization of UV radiometers together with methods for error reduction are presented. Reviews on experiences from world-wide UV monitoring efforts and instrumentation as well as on the results from international UV radiometer intercomparisons are also presented. (62 refs.).

  4. Assessment and comparison of methods for solar ultraviolet radiation measurements

    International Nuclear Information System (INIS)

    Leszczynski, K.

    1995-06-01

    In the study, the different methods to measure the solar ultraviolet radiation are compared. The methods included are spectroradiometric, erythemally weighted broadband and multi-channel measurements. The comparison of the different methods is based on a literature review and assessments of optical characteristics of the spectroradiometer Optronic 742 of the Finnish Centre for Radiation and Nuclear Safety (STUK) and of the erythemally weighted Robertson-Berger type broadband radiometers Solar Light models 500 and 501 of the Finnish Meteorological Institute and STUK. An introduction to the sources of error in solar UV measurements, to methods for radiometric characterization of UV radiometers together with methods for error reduction are presented. Reviews on experiences from world-wide UV monitoring efforts and instrumentation as well as on the results from international UV radiometer intercomparisons are also presented. (62 refs.)

  5. Quantitation of movement of the phosphoryl group during catalytic transfer in the arginine kinase reaction: {sup 31}P relaxation measurements on enzyme-bound equilibrium mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Bruce D. [Indiana University, Purdue University at Indianapolis (IUPUI), Department of Physics (United States); Jarori, Gotam K. [Tata Institute of Fundamental Research (India); Nageswara Rao, B.D. [Indiana University, Purdue University at Indianapolis (IUPUI), Department of Physics (United States)], E-mail: brao@iupui.edu

    2002-05-15

    {sup 31}P nuclear spin relaxation measurements have been made on enzyme-bound equilibrium mixtures of lobster-muscle arginine kinase in the presence of substituent activating paramagnetic cation Co(II) (in place of Mg(II)), i.e., on samples in which the reaction, E{center_dot}CoATP{center_dot}arginine {r_reversible} E{center_dot}CoADP{center_dot}P-arginine, is in progress. The results have been analyzed on the basis of a previously published theory (Nageswara Rao, B.D. (1995) J. Magn. Reson., B108, 289-293) to determine the structural changes in the reaction complex accompanying phosphoryl transfer. The analysis enables the determination of the change in the Co(II)-{sup 31}P ({gamma}-P(ATP)) vector as the transferable phosphoryl group moves over and attaches to arginine to form P-arginine. It is shown that the Co(II)-{sup 31}P distance of {approx}3.0 A, representing direct coordination of Co(II) to {gamma}-P(ATP), changes to {approx}4.0 A when P-arginine is formed in the enzyme-bound reaction complex. This elongation of the Co(II)-{sup 31}P vector implies an excursion of at least 1.0 A for the itinerant phosphoryl group on the surface of the enzyme.

  6. Quantitation of movement of the phosphoryl group during catalytic transfer in the arginine kinase reaction: 31P relaxation measurements on enzyme-bound equilibrium mixtures

    International Nuclear Information System (INIS)

    Ray, Bruce D.; Jarori, Gotam K.; Nageswara Rao, B.D.

    2002-01-01

    31 P nuclear spin relaxation measurements have been made on enzyme-bound equilibrium mixtures of lobster-muscle arginine kinase in the presence of substituent activating paramagnetic cation Co(II) (in place of Mg(II)), i.e., on samples in which the reaction, E·CoATP·arginine ↔ E·CoADP·P-arginine, is in progress. The results have been analyzed on the basis of a previously published theory (Nageswara Rao, B.D. (1995) J. Magn. Reson., B108, 289-293) to determine the structural changes in the reaction complex accompanying phosphoryl transfer. The analysis enables the determination of the change in the Co(II)- 31 P (γ-P(ATP)) vector as the transferable phosphoryl group moves over and attaches to arginine to form P-arginine. It is shown that the Co(II)- 31 P distance of ∼3.0 A, representing direct coordination of Co(II) to γ-P(ATP), changes to ∼4.0 A when P-arginine is formed in the enzyme-bound reaction complex. This elongation of the Co(II)- 31 P vector implies an excursion of at least 1.0 A for the itinerant phosphoryl group on the surface of the enzyme

  7. Quantitative measurement of exchange dynamics in proteins via {sup 13}C relaxation dispersion of {sup 13}CHD{sub 2}-labeled samples

    Energy Technology Data Exchange (ETDEWEB)

    Rennella, Enrico; Schuetz, Anne K.; Kay, Lewis E., E-mail: kay@pound.med.utoronto.ca [University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)

    2016-06-15

    Methyl groups have emerged as powerful probes of protein dynamics with timescales from picoseconds to seconds. Typically, studies involving high molecular weight complexes exploit {sup 13}CH{sub 3}- or {sup 13}CHD{sub 2}-labeling in otherwise highly deuterated proteins. The {sup 13}CHD{sub 2} label offers the unique advantage of providing {sup 13}C, {sup 1}H and {sup 2}H spin probes, however a disadvantage has been the lack of an experiment to record {sup 13}C Carr–Purcell–Meiboom–Gill relaxation dispersion that monitors millisecond time-scale dynamics, implicated in a wide range of biological processes. Herein we develop an experiment that eliminates artifacts that would normally result from the scalar coupling between {sup 13}C and {sup 2}H spins that has limited applications in the past. The utility of the approach is established with a number of applications, including measurement of ms dynamics of a disease mutant of a 320 kDa p97 complex.

  8. Experimental comparison of particle interaction measurement techniques using optical traps

    International Nuclear Information System (INIS)

    Koehler, Timothy P.; Grillet, Anne Mary; Brotherton, Christopher M.; Molecke, Ryan A.

    2008-01-01

    Optical tweezers has become a powerful and common tool for sensitive determination of electrostatic interactions between colloidal particles. Recently, two techniques, 'blinking' tweezers and direct force measurements, have become increasingly prevalent in investigations of inter-particle potentials. The 'blinking' tweezers method acquires physical statistics of particle trajectories to determine drift velocities, diffusion coefficients, and ultimately colloidal forces as a function of the center-center separation of two particles. Direct force measurements monitor the position of a particle relative to the center of an optical trap as the separation distance between two continuously trapped particles is gradually decreased. As the particles near each other, the displacement from the trap center for each particle increases proportional to the inter-particle force. Although commonly employed in the investigation of interactions of colloidal particles, there exists no direct comparison of these experimental methods in the literature. In this study, an experimental apparatus was developed capable of performing both methods and is used to quantify electrostatic potentials between particles in several particle/solvent systems. Comparisons are drawn between the experiments conducted using the two measurement techniques, theory, and existing literature. Forces are quantified on the femto-Newton scale and results agree well with literature values

  9. Study of vortex dynamics with local magnetic relaxation measurements in the superconducting compound Bi2Sr2CaCu2O8

    International Nuclear Information System (INIS)

    Berry, St.

    2000-01-01

    This experimental study of the magnetic field-temperature phase diagram and of the vortex dynamics in high- T c superconductors focuses on Bismuth-based cuprates: Bi 2 Sr 2 CaCu 2 O 8 . In type-II superconductors, mixed state characterized by the presence of vortices (quanta of magnetic flux) is divided by a transition line determined by two features of magnetization loops. For T > 40 K, magnetization loops vs applied field show a step evidence of a first order transition. From 20 to 40 K, a second peak replacing the step correspond to an abrupt increase of irreversibility interpreted as a bulk current. We want to understand the nature of the second peak (thermodynamic or nonequilibrium property) and separate phenomena contributing to irreversibility (flux pinning, geometrical or surface effects). Magnetic measurement techniques are nondestructive and have a resolution of few microns. Bi 2 Sr 2 CaCu 2 O 8 single crystals are optimized by localizing defectives regions with a magneto-optic technique for flux imaging and elimination of these regions with a wire saw. Local magnetization loops and relaxation measurements performed with a microscopic Hall probe array allow to distinguish irreversibility sources. The shape of induction profiles indicates which current dominate between surface current and bulk pinning induced current. Two crossover with time and a direct observation of two phases coexistence in induction profiles enlighten phenomena in play. The measured electric field-current density characteristics lead to barrier energy U(j) controlling thermally activated flux motion. Three relations (U(j) (surface, bulk low and high field) explain second peak. (author)

  10. Comparisons of Air Radiation Model with Shock Tube Measurements

    Science.gov (United States)

    Bose, Deepak; McCorkle, Evan; Bogdanoff, David W.; Allen, Gary A., Jr.

    2009-01-01

    This paper presents an assessment of the predictive capability of shock layer radiation model appropriate for NASA s Orion Crew Exploration Vehicle lunar return entry. A detailed set of spectrally resolved radiation intensity comparisons are made with recently conducted tests in the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. The spectral range spanned from vacuum ultraviolet wavelength of 115 nm to infrared wavelength of 1400 nm. The analysis is done for 9.5-10.5 km/s shock passing through room temperature synthetic air at 0.2, 0.3 and 0.7 Torr. The comparisons between model and measurements show discrepancies in the level of background continuum radiation and intensities of atomic lines. Impurities in the EAST facility in the form of carbon bearing species are also modeled to estimate the level of contaminants and their impact on the comparisons. The discrepancies, although large is some cases, exhibit order and consistency. A set of tests and analyses improvements are proposed as forward work plan in order to confirm or reject various proposed reasons for the observed discrepancies.

  11. Relaxation characteristics of hastelloy X

    International Nuclear Information System (INIS)

    Suzuki, Kazuhiko

    1980-02-01

    Relaxation diagrams of Hastelloy X (relaxation curves, relaxation design diagrams, etc.) were generated from the creep constitutive equation of Hastelloy X, using inelastic stress analysis code TEPICC-J. These data are in good agreement with experimental relaxation data of ORNL-5479. Three typical inelastic stress analyses were performed for various relaxation behaviors of the high-temperature structures. An attempt was also made to predict these relaxation behaviors by the relaxation curves. (author)

  12. Nuclear magnetic resonance relaxation in multiple sclerosis

    DEFF Research Database (Denmark)

    Larsson, H B; Barker, G J; MacKay, A

    1998-01-01

    OBJECTIVES: The theory of relaxation processes and their measurements are described. An overview is presented of the literature on relaxation time measurements in the normal and the developing brain, in experimental diseases in animals, and in patients with multiple sclerosis. RESULTS...... AND CONCLUSION: Relaxation time measurements provide insight into development of multiple sclerosis plaques, especially the occurrence of oedema, demyelination, and gliosis. There is also evidence that normal appearing white matter in patients with multiple sclerosis is affected. What is now needed are fast...

  13. Magnetic Resonance Fingerprinting with short relaxation intervals.

    Science.gov (United States)

    Amthor, Thomas; Doneva, Mariya; Koken, Peter; Sommer, Karsten; Meineke, Jakob; Börnert, Peter

    2017-09-01

    The aim of this study was to investigate a technique for improving the performance of Magnetic Resonance Fingerprinting (MRF) in repetitive sampling schemes, in particular for 3D MRF acquisition, by shortening relaxation intervals between MRF pulse train repetitions. A calculation method for MRF dictionaries adapted to short relaxation intervals and non-relaxed initial spin states is presented, based on the concept of stationary fingerprints. The method is applicable to many different k-space sampling schemes in 2D and 3D. For accuracy analysis, T 1 and T 2 values of a phantom are determined by single-slice Cartesian MRF for different relaxation intervals and are compared with quantitative reference measurements. The relevance of slice profile effects is also investigated in this case. To further illustrate the capabilities of the method, an application to in-vivo spiral 3D MRF measurements is demonstrated. The proposed computation method enables accurate parameter estimation even for the shortest relaxation intervals, as investigated for different sampling patterns in 2D and 3D. In 2D Cartesian measurements, we achieved a scan acceleration of more than a factor of two, while maintaining acceptable accuracy: The largest T 1 values of a sample set deviated from their reference values by 0.3% (longest relaxation interval) and 2.4% (shortest relaxation interval). The largest T 2 values showed systematic deviations of up to 10% for all relaxation intervals, which is discussed. The influence of slice profile effects for multislice acquisition is shown to become increasingly relevant for short relaxation intervals. In 3D spiral measurements, a scan time reduction of 36% was achieved, maintaining the quality of in-vivo T1 and T2 maps. Reducing the relaxation interval between MRF sequence repetitions using stationary fingerprint dictionaries is a feasible method to improve the scan efficiency of MRF sequences. The method enables fast implementations of 3D spatially

  14. A cool-temperate young larch plantation as a net methane source - A 4-year continuous hyperbolic relaxed eddy accumulation and chamber measurements

    Science.gov (United States)

    Ueyama, Masahito; Yoshikawa, Kota; Takagi, Kentaro

    2018-07-01

    Upland forests are thought to be methane (CH4) sinks due to oxidation by methanotrophs in aerobic soils. However, CH4 budget for upland forests are not well quantified at the ecosystem scale, when possible CH4 sources, such as small wet areas, exists in the ecosystem. Here, we quantified CH4 fluxes in a cool-temperate larch plantation based on four-year continuous measurements using the hyperbolic relaxed eddy accumulation (HREA) method and dynamic closed chambers with a laser-based analyzer. After filling data gaps for half-hourly data using machine-learning-based regressions, we found that the forest acted as a net CH4 source at the canopy scale: 30 ± 11 mg CH4 m-2 yr-1 in 2014, 56 ± 8 mg CH4 m-2 yr-1 in 2015, 154 ± 5 mg CH4 m-2 yr-1 in 2016, and 132 ± 6 mg CH4 m-2 yr-1 in 2017. Hotspot emissions from the edge of the pond could strongly contribute to the canopy-scale emissions. The magnitude of the hotspot emissions was 10-100 times greater than the order of the canopy-scale and chamber-based CH4 fluxes at the dry soils. The high temperatures with wet conditions stimulated the hotspot emissions, and thus induced canopy-scale CH4 emissions in the summer. Understanding and modeling the dynamics of hotspot emissions are important for quantifying CH4 budgets of upland forests. Micrometeorological measurements at various forests are required for revisiting CH4 budget of upland forests.

  15. Objective measurement of minimal fat in normal skeletal muscles of healthy children using T2 relaxation time mapping (T2 maps) and MR spectroscopy.

    Science.gov (United States)

    Kim, Hee Kyung; Serai, Suraj; Merrow, Arnold C; Wang, Lily; Horn, Paul S; Laor, Tal

    2014-02-01

    Various skeletal muscle diseases result in fatty infiltration, making it important to develop noninvasive biomarkers to objectively measure muscular fat. We compared T2 relaxation time mapping (T2 maps) and magnetic resonance spectroscopy (MRS) with physical characteristics previously correlated with intramuscular fat to validate T2 maps and MRS as objective measures of skeletal muscle fat. We evaluated gluteus maximus muscles in 30 healthy boys (ages 5-19 years) at 3 T with T1-weighted images, T2-W images with fat saturation, T2 maps with and without fat saturation, and MR spectroscopy. We calculated body surface area (BSA), body mass index (BMI) and BMI percentile (BMI %). We performed fat and inflammation grading on T1-W imaging and fat-saturated T2-W imaging, respectively. Mean T2 values from T2 maps with fat saturation were subtracted from T2 maps without fat saturation to determine T2 fat values. We obtained lipid-to-water ratios by MR spectroscopy. Pearson correlation was used to assess relationships between BSA, BMI, BMI %, T2 fat values, and lipid-to-water ratios for each boy. Twenty-four boys completed all exams; 21 showed minimal and 3 showed no fatty infiltration. None showed muscle inflammation. There was correlation between BSA, BMI, and BMI %, and T2 fat values (P values and lipid-to-water ratios (P skeletal muscles, even in microscopic amounts, and validate each other. Both techniques might enable detection of minimal pathological fatty infiltration in children with skeletal muscle disorders.

  16. Comparison of Different Approaches for Measuring Tibial Cartilage Thickness

    Directory of Open Access Journals (Sweden)

    Maier Jennifer

    2017-07-01

    Full Text Available Osteoarthritis is a degenerative disease affecting bones and cartilage especially in the human knee. In this context, cartilage thickness is an indicator for knee cartilage health. Thickness measurements are performed on medical images acquired in-vivo. Currently, there is no standard method agreed upon that defines a distance measure in articular cartilage. In this work, we present a comparison of different methods commonly used in literature. These methods are based on nearest neighbors, surface normal vectors, local thickness and potential field lines. All approaches were applied to manual segmentations of tibia and lateral and medial tibial cartilage performed by experienced raters. The underlying data were contrast agent-enhanced cone-beam C-arm CT reconstructions of one healthy subject’s knee. The subject was scanned three times, once in supine position and two times in a standing weight-bearing position. A comparison of the resulting thickness maps shows similar distributions and high correlation coefficients between the approaches above 0.90. The nearest neighbor method results on average in the lowest cartilage thickness values, while the local thickness approach assigns the highest values. We showed that the different methods agree in their thickness distribution. The results will be used for a future evaluation of cartilage change under weight-bearing conditions.

  17. Comparison of TLD air kerma measurements in mammography

    International Nuclear Information System (INIS)

    Pernicka, F.

    2002-01-01

    The mammography examination is usually targeted at asymptomatic women so the narrow balance between benefit and undesirable effects is important. During the past few decades there have been significant advances in the equipment used for mammography. Even when the latest equipment and imaging systems are used, there is considerable variation from centre-to-centre in the choice of imaging parameters and techniques. There may be quite large differences in image quality and breast dose among the centres. A Co-ordinated Research Programme on 'Image quality and patient dose optimization in mammography in Eastern European Countries' was conducted by the IAEA, aiming at defining a methodology for the implementation of a quality assurance (QA) programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in East European countries. Selected mammography clinics from Czech Republic, Hungary, Poland, Romania and Slovakia participate in the project. The teams consisted of experienced clinicians and physicists. They were supported by a group of experts (clinicians and medical physicists) from France, Italy and Spain. As an outcome of the project, improvements in these indicators (image quality and patient dose) after the implementation of the QA programme are expected. A comparison of dosimetry systems has been organized to assure that dosimetry measurements done in the frame of the project are comparable and traceable to the international measurement system. All five East European countries plus Spain took part in the exercise. The thermoluminescent (TL) method was selected for the comparison

  18. Specific activity measurement of 64Cu: A comparison of methods

    International Nuclear Information System (INIS)

    Mastren, Tara; Guthrie, James; Eisenbeis, Paul; Voller, Tom; Mebrahtu, Efrem; Robertson, J. David; Lapi, Suzanne E.

    2014-01-01

    Effective specific activity of 64 Cu (amount of radioactivity per µmol metal) is important in order to determine purity of a particular 64 Cu lot and to assist in optimization of the purification process. Metal impurities can affect effective specific activity and therefore it is important to have a simple method that can measure trace amounts of metals. This work shows that ion chromatography (IC) yields similar results to ICP mass spectrometry for copper, nickel and iron contaminants in 64 Cu production solutions. - Highlights: • Comparison of TETA titration, ICP mass spectrometry, and ion chromatography to measure specific activity. • Validates ion chromatography by using ICP mass spectrometry as the “gold standard”. • Shows different types and amounts of metal impurities present in 64 Cu

  19. TEACHING NEUROMUSCULAR RELAXATION.

    Science.gov (United States)

    NORRIS, JEANNE E.; STEINHAUS, ARTHUR H.

    THIS STUDY ATTEMPTED TO FIND OUT WHETHER (1) THE METHODS FOR ATTAINING NEUROMUSCULAR RELAXATION THAT HAVE PROVED FRUITFUL IN THE ONE-TO-ONE RELATIONSHIP OF THE CLINIC CAN BE SUCCESSFULLY ADAPTED TO THE TEACHER-CLASS RELATIONSHIP OF THE CLASSROOM AND GYMNASIUM, AND (2) NEUROMUSCULAR RELAXATION CAN BE TAUGHT SUCCESSFULLY BY AN APPROPRIATELY TRAINED…

  20. Relaxation of Anisotropic Glasses

    DEFF Research Database (Denmark)

    Deubener, Joachim; Martin, Birgit; Wondraczek, Lothar

    2004-01-01

    . When the load was removed at room temperature a permanent optical anisotropy (birefringence) was observed only perpendicular to cylinder axis and the pressure direction indicating complete elimination of thermal stresses. Relaxation of structural anisotropy was studied from reheating experiments using...... the energy release, thermo-mechanical and optical relaxation behaviour are drawn....

  1. Relaxation techniques for stress

    Science.gov (United States)

    ... raise your heart rate. This is called the stress response. Relaxation techniques can help your body relax and lower your blood pressure ... also many other types of breathing techniques you can learn. In many cases, you do not need much ... including those that cause stress. Meditation has been practiced for thousands of years, ...

  2. Viscoelastic characterization of compacted pharmaceutical excipient materials by analysis of frequency-dependent mechanical relaxation processes

    Science.gov (United States)

    Welch, K.; Mousavi, S.; Lundberg, B.; Strømme, M.

    2005-09-01

    A newly developed method for determining the frequency-dependent complex Young's modulus was employed to analyze the mechanical response of compacted microcrystalline cellulose, sorbitol, ethyl cellulose and starch for frequencies up to 20 kHz. A Debye-like relaxation was observed in all the studied pharmaceutical excipient materials and a comparison with corresponding dielectric spectroscopy data was made. The location in frequency of the relaxation peak was shown to correlate to the measured tensile strength of the tablets, and the relaxation was interpreted as the vibrational response of the interparticle hydrogen and van der Waals bindings in the tablets. Further, the measured relaxation strength, holding information about the energy loss involved in the relaxation processes, showed that the weakest material in terms of tensile strength, starch, is the material among the four tested ones that is able to absorb the most energy within its structure when exposed to external perturbations inducing vibrations in the studied frequency range. The results indicate that mechanical relaxation analysis performed over relatively broad frequency ranges should be useful for predicting material properties of importance for the functionality of a material in applications such as, e.g., drug delivery, drug storage and handling, and also for clarifying the origin of hitherto unexplained molecular processes.

  3. A wrinkling-based method for investigating glassy polymer film relaxation as a function of film thickness and temperature.

    Science.gov (United States)

    Chung, Jun Young; Douglas, Jack F; Stafford, Christopher M

    2017-10-21

    We investigate the relaxation dynamics of thin polymer films at temperatures below the bulk glass transition T g by first compressing polystyrene films supported on a polydimethylsiloxane substrate to create wrinkling patterns and then observing the slow relaxation of the wrinkled films back to their final equilibrium flat state by small angle light scattering. As with recent relaxation measurements on thin glassy films reported by Fakhraai and co-workers, we find the relaxation time of our wrinkled films to be strongly dependent on film thickness below an onset thickness on the order of 100 nm. By varying the temperature between room temperature and T g (≈100 °C), we find that the relaxation time follows an Arrhenius-type temperature dependence to a good approximation at all film thicknesses investigated, where both the activation energy and the relaxation time pre-factor depend appreciably on film thickness. The wrinkling relaxation curves tend to cross at a common temperature somewhat below T g , indicating an entropy-enthalpy compensation relation between the activation free energy parameters. This compensation effect has also been observed recently in simulated supported polymer films in the high temperature Arrhenius relaxation regime rather than the glassy state. In addition, we find that the film stress relaxation function, as well as the height of the wrinkle ridges, follows a stretched exponential time dependence and the short-time effective Young's modulus derived from our modeling decreases sigmoidally with increasing temperature-both characteristic features of glassy materials. The relatively facile nature of the wrinkling-based measurements in comparison to other film relaxation measurements makes our method attractive for practical materials development, as well as fundamental studies of glass formation.

  4. Relationship between Structural and Stress Relaxation in a Block-Copolymer Melt

    International Nuclear Information System (INIS)

    Patel, Amish J.; Narayanan, Suresh; Sandy, Alec; Mochrie, Simon G. J.; Garetz, Bruce A.; Watanabe, Hiroshi; Balsara, Nitash P.

    2006-01-01

    The relationship between structural relaxation on molecular length scales and macroscopic stress relaxation was explored in a disordered block-copolymer melt. Experiments show that the structural relaxation time, measured by x-ray photon correlation spectroscopy is larger than the terminal stress relaxation time, measured by rheology, by factors as large as 100. We demonstrate that the structural relaxation data are dominated by the diffusion of intact micelles while the stress relaxation data are dominated by contributions due to disordered concentration fluctuations

  5. Quantitative Skeletal Muscle MRI: Part 2, MR Spectroscopy and T2 Relaxation Time Mapping-Comparison Between Boys With Duchenne Muscular Dystrophy and Healthy Boys.

    Science.gov (United States)

    Kim, Hee Kyung; Serai, Suraj; Lindquist, Diana; Merrow, Arnold C; Horn, Paul S; Kim, Dong Hoon; Wong, Brenda L

    2015-08-01

    The purpose of this study is to validate the use of MR spectroscopy (MRS) in measuring muscular fat and to compare it with T2 maps in differentiating boys with Duchenne muscular dystrophy (DMD) from healthy boys. Forty-two boys with DMD and 31 healthy boys were evaluated with MRI with (1)H-MRS and T2 maps. Grading of muscle fat and edema on conventional images, calculation of fat fractions ([fat / fat] + water) on MRS, and calculation of T2 fat values on T2 maps of the gluteus maximus and vastus lateralis muscles were performed. Group comparisons were made. The 95% reference interval (RI) of fat fraction for the control group was applied and compared with T2 map results. Minimal fat on T1-weighted images was seen in 90.3% (gluteus maximus) and 71.0% (vastus lateralis) of healthy boys, versus 33.3% (gluteus maximus) and 52.4% (vastus lateralis) of boys with DMD. Muscle edema was seen in none of the healthy boys versus 52.4% (gluteus maximus) and 57.1% (vastus lateralis) of the boys with DMD. Fat fractions were higher in the DMD group (52.7%, gluteus maximus; 27.3%, vastus lateralis) than in the control group (12.8%, gluteus maximus; 13.7%, vastus lateralis) (p muscle edema in DMD.

  6. An interlaboratory comparison of methods for measuring rock matrix porosity

    International Nuclear Information System (INIS)

    Rasilainen, K.; Hellmuth, K.H.; Kivekaes, L.; Ruskeeniemi, T.; Melamed, A.; Siitari-Kauppi, M.

    1996-09-01

    An interlaboratory comparison study was conducted for the available Finnish methods of rock matrix porosity measurements. The aim was first to compare different experimental methods for future applications, and second to obtain quality assured data for the needs of matrix diffusion modelling. Three different versions of water immersion techniques, a tracer elution method, a helium gas through-diffusion method, and a C-14-PMMA method were tested. All methods selected for this study were established experimental tools in the respective laboratories, and they had already been individually tested. Rock samples for the study were obtained from a homogeneous granitic drill core section from the natural analogue site at Palmottu. The drill core section was cut into slabs that were expected to be practically identical. The subsamples were then circulated between the different laboratories using a round robin approach. The circulation was possible because all methods were non-destructive, except the C-14-PMMA method, which was always the last method to be applied. The possible effect of drying temperature on the measured porosity was also preliminarily tested. These measurements were done in the order of increasing drying temperature. Based on the study, it can be concluded that all methods are comparable in their accuracy. The selection of methods for future applications can therefore be based on practical considerations. Drying temperature seemed to have very little effect on the measured porosity, but a more detailed study is needed for definite conclusions. (author) (4 refs.)

  7. Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

    International Nuclear Information System (INIS)

    Miah, M Idrish

    2008-01-01

    We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs

  8. Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M Idrish [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

    2008-09-21

    We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs.

  9. Comparison of ventilation measurement techniques in real conditions

    International Nuclear Information System (INIS)

    Jilek, K.; Tomasek, L.

    2001-01-01

    Ventilation and radon entry rate are the only two quantities that influence on indoor radon behaviour. In order to investigate the effect of ventilation and radon entry rate on indoor radon behaviour separately , the Institute was equipped with continuous monitor of carbon monoxide (CO). Carbon monoxide serves as a tracer gas for the determination of air exchange rate. The use of a continuous radon monitor and the continuous monitor of CO gas at the same time enables to measure the radon entry rate and the air exchange rate separately. In the lecture are summarized results of comparison of the following three basic methods performed in real living conditions: - constant decay method; - constant tracer method; and steady rate of tracer injection to determine the air exchange rate for 222 Rn and CO gas, which were used as tracer gases. (authors)

  10. Biases and power for groups comparison on subjective health measurements.

    Science.gov (United States)

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

    2012-01-01

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

  11. Biases and power for groups comparison on subjective health measurements.

    Directory of Open Access Journals (Sweden)

    Jean-François Hamel

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

  12. Biases and Power for Groups Comparison on Subjective Health Measurements

    Science.gov (United States)

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

    2012-01-01

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

  13. The relaxation time approximation

    International Nuclear Information System (INIS)

    Gairola, R.P.; Indu, B.D.

    1991-01-01

    A plausible approximation has been made to estimate the relaxation time from a knowledge of the transition probability of phonons from one state (r vector, q vector) to other state (r' vector, q' vector), as a result of collision. The relaxation time, thus obtained, shows a strong dependence on temperature and weak dependence on the wave vector. In view of this dependence, relaxation time has been expressed in terms of a temperature Taylor's series in the first Brillouin zone. Consequently, a simple model for estimating the thermal conductivity is suggested. the calculations become much easier than the Callaway model. (author). 14 refs

  14. A Comparison Of GADRAS Simulated And Measured Gamma Ray Spectra

    International Nuclear Information System (INIS)

    Jeffcoat, R.; Salaymeh, S.

    2010-01-01

    Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.

  15. Comparison of mixing height parameterizations with profiles measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jaquier, A.; Stuebi, R.; Tercier, P. [Swiss Meteorological Inst., SMI - MeteoSwiss, Payerne (Switzerland)

    1997-10-01

    Different meteorological pre-processors for dispersion studies are available to derive the atmospheric boundary layer mixing height (MH). The analysis of their performances has been reviewed in the framework of the European COST Action 710. In this project, the computed mixing height values have been compared with data derived mostly from aero-logical sounding analysis and Sodar measurements. Since then, a new analysis of a low-tropospheric wind profiler (WP) data has been performed taking advantage of its high data sampling ({delta}t {approx} 30 sec.). The comparison between these recent results and aero-logical sounding, Sodar data, as well as to meteorological pre-processors calculations are reported for three periods of several days corresponding to different meteorological situations. In convective conditions, the pre-processors give reasonable level, the mixing height growing rate is in fair agreement with the measured one. In stable cloudy daytime conditions, the modeled mixing height does not correspond to any measured height. (LN)

  16. Calculation of nuclear-spin-relaxation rate for spin-polarized atomic hydrogen

    International Nuclear Information System (INIS)

    Ahn, R.M.C.; Eijnde, J.P.H.W.V.; Verhaar, B.J.

    1983-01-01

    Approximations introduced in previous calculations of spin relaxation for spin-polarized atomic hydrogen are investigated by carrying out a more exact coupled-channel calculation. With the exception of the high-temperature approximation, the approximations turn out to be justified up to the 10 -3 level of accuracy. It is shown that at the lowest temperatures for which experimental data are available, the high-temperature limit underestimates relaxation rates by a factor of up to 2. For a comparison with experimental data it is also of interest to pay attention to the expression for the atomic hydrogen relaxation rates in terms of transition amplitudes for two-particle collisions. Discrepancies by a factor of 2 among previous derivations of relaxation rates are pointed out. To shed light on these discrepancies we present two alternative derivations in which special attention is paid to identical-particle aspects. Comparing with experiment, we find our theoretical volume relaxation rate to be in better agreement with measured values than that obtained by other groups. The theoretical surface relaxation rate, however, still shows a discrepancy with experiment by a factor of order 50

  17. Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

    Science.gov (United States)

    Pfeiffer, M.; Nizenkov, P.; Mirza, A.; Fasoulas, S.

    2016-02-01

    Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn's Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder.

  18. Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

    International Nuclear Information System (INIS)

    Pfeiffer, M.; Nizenkov, P.; Mirza, A.; Fasoulas, S.

    2016-01-01

    Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn’s Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder

  19. Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, M., E-mail: mpfeiffer@irs.uni-stuttgart.de; Nizenkov, P., E-mail: nizenkov@irs.uni-stuttgart.de; Mirza, A., E-mail: mirza@irs.uni-stuttgart.de; Fasoulas, S., E-mail: fasoulas@irs.uni-stuttgart.de [Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany)

    2016-02-15

    Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn’s Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder.

  20. Vibrational relaxation in OCS mixtures

    International Nuclear Information System (INIS)

    Simpson, C.J.S.M.; Gait, P.D.; Simmie, J.M.

    1976-01-01

    Experimental measurements are reported of vibrational relaxation times which may be used to show whether there is near resonant vibration-rotation energy transfer between OCS and H 2 , D 2 or HD. Vibrational relaxation times have been measured in OCS and OCS mixtures over the temperature range 360 to 1000 K using a shock tube and a laser schlieren system. The effectiveness of the additives in reducing the relaxation time of OCS is in the order 4 He 3 He 2 2 and HD. Along this series the effect of an increase in temperature changes from the case of speeding up the rate with 4 He to retarding it with D 2 , HD and H 2 . There is no measurable difference in the effectiveness of n-D 2 and o-D 2 and little, or no, difference between n-H 2 and p-H 2 . Thus the experimental results do not give clear evidence for rotational-vibration energy transfer between hydrogen and OCS. This contrasts with the situation for CO 2 + H 2 mixtures. (author)

  1. Comparison of measurement methods for benzene and toluene

    Science.gov (United States)

    Wideqvist, U.; Vesely, V.; Johansson, C.; Potter, A.; Brorström-Lundén, E.; Sjöberg, K.; Jonsson, T.

    Diffusive sampling and active (pumped) sampling (tubes filled with Tenax TA or Carbopack B) were compared with an automatic BTX instrument (Chrompack, GC/FID) for measurements of benzene and toluene. The measurements were made during differing pollution levels and different weather conditions at a roof-top site and in a densely trafficked street canyon in Stockholm, Sweden. The BTX instrument was used as the reference method for comparison with the other methods. Considering all data the Perkin-Elmer diffusive samplers, containing Tenax TA and assuming a constant uptake rate of 0.406 cm3 min-1, showed about 30% higher benzene values compared to the BTX instrument. This discrepancy may be explained by a dose-dependent uptake rate with higher uptake rates at lower dose as suggested by laboratory experiments presented in the literature. After correction by applying the relationship between uptake rate and dose as suggested by Roche et al. (Atmos. Environ. 33 (1999) 1905), the two methods agreed almost perfectly. For toluene there was much better agreement between the two methods. No sign of a dose-dependent uptake could be seen. The mean concentrations and 95% confidence intervals of all toluene measurements (67 values) were (10.80±1.6) μg m -3 for diffusive sampling and (11.3±1.6) μg m -3 for the BTX instrument, respectively. The overall ratio between the concentrations obtained using diffusive sampling and the BTX instrument was 0.91±0.07 (95% confidence interval). Tenax TA was found to be equal to Carbopack B for measuring benzene and toluene in this concentration range, although it has been proposed not to be optimal for benzene. There was also good agreement between the active samplers and the BTX instrument.

  2. Methane airborne measurements and comparison to global models during BARCA

    Science.gov (United States)

    Beck, Veronika; Chen, Huilin; Gerbig, Christoph; Bergamaschi, Peter; Bruhwiler, Lori; Houweling, Sander; Röckmann, Thomas; Kolle, Olaf; Steinbach, Julia; Koch, Thomas; Sapart, Célia J.; van der Veen, Carina; Frankenberg, Christian; Andreae, Meinrat O.; Artaxo, Paulo; Longo, Karla M.; Wofsy, Steven C.

    2012-08-01

    Tropical regions, especially the Amazon region, account for large emissions of methane (CH4). Here, we present CH4 observations from two airborne campaigns conducted within the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) project in the Amazon basin in November 2008 (end of the dry season) and May 2009 (end of the wet season). We performed continuous measurements of CH4 onboard an aircraft for the first time in the Amazon region, covering the whole Amazon basin with over 150 vertical profiles between altitudes of 500 m and 4000 m. The observations support the finding of previous ground-based, airborne, and satellite measurements that the Amazon basin is a large source of atmospheric CH4. Isotope analysis verified that the majority of emissions can be attributed to CH4 emissions from wetlands, while urban CH4 emissions could be also traced back to biogenic origin. A comparison of five TM5 based global CH4 inversions with the observations clearly indicates that the inversions using SCIAMACHY observations represent the BARCA observations best. The calculated CH4 flux estimate obtained from the mismatch between observations and TM5-modeled CH4 fields ranges from 36 to 43 mg m-2 d-1 for the Amazon lowland region.

  3. Relaxation of polarized nuclei in superconducting rhodium

    DEFF Research Database (Denmark)

    Knuuttila, T.A.; Tuoriniemi, J.T.; Lefmann, K.

    2000-01-01

    Nuclear spin lattice relaxation rates were measured in normal and superconducting (sc) rhodium with nuclear polarizations up to p = 0.55. This was sufficient to influence the sc state of Rh, whose T, and B-c, are exceptionally low. Because B-c ... is unchanged, the nuclear spin entropy was fully sustained across the sc transition. The relaxation in the sc state was slower at all temperatures without the coherence enhancement close to T-c. Nonzero nuclear polarization strongly reduced the difference between the relaxation rates in the sc and normal...

  4. Prediction of Landing Gear Noise Reduction and Comparison to Measurements

    Science.gov (United States)

    Lopes, Leonard V.

    2010-01-01

    Noise continues to be an ongoing problem for existing aircraft in flight and is projected to be a concern for next generation designs. During landing, when the engines are operating at reduced power, the noise from the airframe, of which landing gear noise is an important part, is equal to the engine noise. There are several methods of predicting landing gear noise, but none have been applied to predict the change in noise due to a change in landing gear design. The current effort uses the Landing Gear Model and Acoustic Prediction (LGMAP) code, developed at The Pennsylvania State University to predict the noise from landing gear. These predictions include the influence of noise reduction concepts on the landing gear noise. LGMAP is compared to wind tunnel experiments of a 6.3%-scale Boeing 777 main gear performed in the Quiet Flow Facility (QFF) at NASA Langley. The geometries tested in the QFF include the landing gear with and without a toboggan fairing and the door. It is shown that LGMAP is able to predict the noise directives and spectra from the model-scale test for the baseline configuration as accurately as current gear prediction methods. However, LGMAP is also able to predict the difference in noise caused by the toboggan fairing and by removing the landing gear door. LGMAP is also compared to far-field ground-based flush-mounted microphone measurements from the 2005 Quiet Technology Demonstrator 2 (QTD 2) flight test. These comparisons include a Boeing 777-300ER with and without a toboggan fairing that demonstrate that LGMAP can be applied to full-scale flyover measurements. LGMAP predictions of the noise generated by the nose gear on the main gear measurements are also shown.

  5. A COMPARISON OF STELLAR ELEMENTAL ABUNDANCE TECHNIQUES AND MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Hinkel, Natalie R.; Young, Patrick A.; Pagano, Michael D.; Desch, Steven J.; Anbar, Ariel D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Adibekyan, Vardan; Mena, Elisa Delgado; Sousa, Sergio G.; Santos, Nuno C. [Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto (Portugal); Blanco-Cuaresma, Sergi [Observatoire de Genève, Université de Genève, CH-1290 Versoix (Switzerland); Carlberg, Joleen K. [NASA Goddard Space Flight Center, Code 667, Greenbelt MD 20771 (United States); Liu, Fan [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Nordlander, Thomas; Korn, Andreas; Gruyters, Pieter; Heiter, Ulrike [Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala (Sweden); Jofré, Paula [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Soubiran, Caroline, E-mail: natalie.hinkel@gmail.com [CNRS/Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac (France)

    2016-09-01

    Stellar elemental abundances are important for understanding the fundamental properties of a star or stellar group, such as age and evolutionary history, as well as the composition of an orbiting planet. However, as abundance measurement techniques have progressed, there has been little standardization between individual methods and their comparisons. As a result, different stellar abundance procedures determine measurements that vary beyond the quoted error for the same elements within the same stars. The purpose of this paper is to better understand the systematic variations between methods and offer recommendations for producing more accurate results in the future. We invited a number of participants from around the world (Australia, Portugal, Sweden, Switzerland, and the United States) to calculate 10 element abundances (C, O, Na, Mg, Al, Si, Fe, Ni, Ba, and Eu) using the same stellar spectra for four stars (HD 361, HD 10700, HD 121504, and HD 202206). Each group produced measurements for each star using (1) their own autonomous techniques, (2) standardized stellar parameters, (3) a standardized line list, and (4) both standardized parameters and a line list. We present the resulting stellar parameters, absolute abundances, and a metric of data similarity that quantifies the homogeneity of the data. We conclude that standardization of some kind, particularly stellar parameters, improves the consistency between methods. However, because results did not converge as more free parameters were standardized, it is clear there are inherent issues within the techniques that need to be reconciled. Therefore, we encourage more conversation and transparency within the community such that stellar abundance determinations can be reproducible as well as accurate and precise.

  6. Comparison of MRI T2 Relaxation Changes of Knee Articular Cartilage before and after Running between Young and Old Amateur Athletes

    International Nuclear Information System (INIS)

    Cha, Jang Gyu; Jeon, Chan Hong; Lee, Eun Hye; Lee, Jae Chul; Kim, Hyun Joo; Han, Jong Kyu; Kim, Yong Dai

    2012-01-01

    To compare changes in T2 relaxation on magnetic resonance (MR) images of knee articular cartilage in younger and older amateur athletes before and after running. By using a 3.0-T MR imager, quantitative T2 maps of weight-bearing femoral and tibial articular cartilages in 10 younger and 10 older amateur athletes were acquired before, immediately after, and 2 hours after 30 minutes of running. Changes in global cartilage T2 signals of the medial and lateral condyles of the femur and tibia and regional cartilage T2 signals in the medial condyles of femoral and tibia in response to exercise were compared between the two age groups. Changes in global cartilage T2 values after running did not differ significantly between the age groups. In terms of the depth variation, relatively higher T2 values in the older group than in the younger group were observed mainly in the superficial layers of the femoral and tibial cartilage (p < 0.05). Age-related cartilage changes may occur mainly in the superficial layer of cartilage where collagen matrix degeneration is primarily initiated. However, no trend is observed regarding a global T2 changes between the younger and older age groups in response to exercise.

  7. Comparison of design and torque measurements of various manual wrenches.

    Science.gov (United States)

    Neugebauer, Jörg; Petermöller, Simone; Scheer, Martin; Happe, Arndt; Faber, Franz-Josef; Zoeller, Joachim E

    2015-01-01

    Accurate torque application and determination of the applied torque during surgical and prosthetic treatment is important to reduce complications. A study was performed to determine and compare the accuracy of manual wrenches, which are available in different designs with a large range of preset torques. Thirteen different wrench systems with a variety of preset torques ranging from 10 to 75 Ncm were evaluated. Three different designs were available, with a spring-in-coil or toggle design as an active mechanism or a beam as a passive mechanism, to select the preset torque. To provide a clinically relevant analysis, a total of 1,170 torque measurements in the range of 10 to 45 Ncm were made in vitro using an electronic torque measurement device. The absolute deviations in Ncm and percent deviations across all wrenches were small, with a mean of -0.24 ± 2.15 Ncm and -0.84% ± 11.72% as a shortfall relative to the preset value. The greatest overage was 8.2 Ncm (82.5%), and the greatest shortfall was 8.47 Ncm (46%). However, extreme values were rare, with 95th-percentile values of -1.5% (lower value) and -0.16% (upper value). A comparison with respect to wrench design revealed significantly higher deviations for coil and toggle-style wrenches than for beam wrenches. Beam wrenches were associated with a lower risk of rare extreme values thanks to their passive mechanism of achieving the selected preset torque, which minimizes the risk of harming screw connections.

  8. Muscle relaxation for individuals having tattoos removed through laser treatment: possible effects regarding anxiety and pain.

    Science.gov (United States)

    Huang, Faye; Chou, Wen-Jiun; Chen, Tien-Hsing; Chen, Ching; Hsieh, Yu-Lian; Chong, Mian-Yoon; Hung, Chi-Fa; Lin, Shu-Ching; Tsai, Hsiu-Huang; Wang, Liang-Jen

    2016-08-01

    Effectively managing pain is vital for the well-being and satisfaction of patients undergoing dermatologic treatments involving lasers. This study investigates the potential outcome of using muscle relaxation techniques to reduce pain among people having their tattoos removed with laser treatment. This study consists of 56 participants (mean age 18.1 ± 2.1 years) that had tattoos removed using the principle of selective photothermolysis. These participants underwent muscle relaxation before receiving the laser treatment. Their peripheral skin temperatures (PST) were measured both at the beginning and the end of the muscle relaxation period. Then, the Beck Anxiety Inventory was applied to evaluate anxiety levels. Once the laser treatment was completed, pain levels were measured using a visual analogue scale. A total of 125 person-sessions of laser treatment and psychometric assessments were performed in this study. The muscle relaxation method significantly increased the PST of the participants while reducing the levels of anxiety and pain throughout the course of the laser treatment procedure. The PST, anxiety scores, and pain scores all showed significant correlations with one another. According to the results obtained, this study proposes that muscle relaxation techniques be considered possibly auxiliary treatment options for individuals having tattoos removed through laser treatment. Additional studies with a comparison group and a larger sample size are required in the future to confirm the effectiveness of such intervention.

  9. Comparison of Physician-Predicted to Measured Low Vision Outcomes

    Science.gov (United States)

    Chan, Tiffany L.; Goldstein, Judith E.; Massof, Robert W.

    2013-01-01

    Purpose To compare low vision rehabilitation (LVR) physicians’ predictions of the probability of success of LVR to patients’ self-reported outcomes after provision of usual outpatient LVR services; and to determine if patients’ traits influence physician ratings. Methods The Activity Inventory (AI), a self-report visual function questionnaire, was administered pre and post-LVR to 316 low vision patients served by 28 LVR centers that participated in a collaborative observational study. The physical component of the Short Form-36, Geriatric Depression Scale, and Telephone Interview for Cognitive Status were also administered pre-LVR to measure physical capability, depression and cognitive status. Following patient evaluation, 38 LVR physicians estimated the probability of outcome success (POS), using their own criteria. The POS ratings and change in functional ability were used to assess the effects of patients’ baseline traits on predicted outcomes. Results A regression analysis with a hierarchical random effects model showed no relationship between LVR physician POS estimates and AI-based outcomes. In another analysis, Kappa statistics were calculated to determine the probability of agreement between POS and AI-based outcomes for different outcome criteria. Across all comparisons, none of the kappa values were significantly different from 0, which indicates the rate of agreement is equivalent to chance. In an exploratory analysis, hierarchical mixed effects regression models show that POS ratings are associated with information about the patient’s cognitive functioning and the combination of visual acuity and functional ability, as opposed to visual acuity or functional ability alone. Conclusions Physicians’ predictions of LVR outcomes appear to be influenced by knowledge of patients’ cognitive functioning and the combination of visual acuity and functional ability - information physicians acquire from the patient’s history and examination. However

  10. Relaxation techniques for pain management in labour.

    Science.gov (United States)

    Smith, Caroline A; Levett, Kate M; Collins, Carmel T; Armour, Mike; Dahlen, Hannah G; Suganuma, Machiko

    2018-03-28

    therefore the effects below should be interpreted with caution.RelaxationWe found that relaxation compared to usual care provided lowered the intensity of pain (measured on a scale of 0 to 10 with low scores indicating less pain) during the latent phase of labour (mean difference (MD) -1.25, 95% confidence interval (CI) -1.97 to -0.53, one trial, 40 women). Four trials reported pain intensity in the active phase; there was high heterogeneity between trials and very low-quality evidence suggested that there was no strong evidence that the effects were any different between groups for this outcome (MD -1.08, 95% CI -2.57 to 0.41, four trials, 271 women, random-effects analysis). Very low-quality evidence showed that women receiving relaxation reported greater satisfaction with pain relief during labour (risk ratio (RR) 8.00, 95% CI 1.10 to 58.19, one trial, 40 women), and showed no clear benefit for satisfaction with childbirth experience (assessed using different scales) (standard mean difference (SMD) -0.03, 95% CI -0.37 to 0.31, three trials, 1176 women). For safety outcomes there was very low-quality evidence of no clear reduction in assisted vaginal birth (average RR 0.61, 95% CI 0.20 to 1.84, four trials, 1122 women) or in caesarean section rates (average RR 0.73, 95% CI 0.26 to 2.01, four trials, 1122 women). Sense of control in labour, and breastfeeding were not reported under this comparison.YogaWhen comparing yoga to control interventions there was low-quality evidence that yoga lowered pain intensity (measured on a scale of 0 to 10) with low scores indicating less pain) (MD -6.12, 95% CI -11.77 to -0.47, one trial, 66 women), greater satisfaction with pain relief (MD 7.88, 95% CI 1.51 to 14.25, one trial, 66 women) and greater satisfaction with childbirth experience (MD 6.34, 95% CI 0.26 to 12.42 one trial, 66 women (assessed using the Maternal Comfort Scale with higher score indicating greater comfort). Sense of control in labour, breastfeeding, assisted vaginal

  11. Relaxed Binaural LCMV Beamforming

    NARCIS (Netherlands)

    Koutrouvelis, A.; Hendriks, R.C.; Heusdens, R.; Jensen, Jesper Rindom

    2017-01-01

    In this paper, we propose a new binaural beamforming technique, which can be seen as a relaxation of the linearly constrained minimum variance (LCMV) framework. The proposed method can achieve simultaneous noise reduction and exact binaural cue preservation of the target source, similar to the

  12. Relaxation times T1, T2, and T2{sup *} of apples, pears, citrus fruits, and potatoes with a comparison to human tissues; T1-, T2- und T2{sup *}-Relaxationswerte von Aepfeln, Birnen, Zitrusfruechten und Kartoffeln im Vergleich zu menschlichen Geweben

    Energy Technology Data Exchange (ETDEWEB)

    Werz, Karin; Braun, Hans; Vitha, Dominik; Bruno, Graziano; Martirosian, Petros; Steidle, Guenter; Schick, Fritz [Tuebingen Univ. (Germany). Sektion fuer Experimentelle Radiologie

    2011-07-01

    The aim of the project was a systematic assessment of relaxation times of different fruits and vegetables and a comparison to values of human tissues. Results provide an improved basis for selection of plant phantoms for development of new MR techniques and sequences. Vessels filled with agar gel are mostly used for this purpose, preparation of which is effortful and time-consuming. In the presented study apples, (malus, 8 species), pears, (pyrus, 2 species), citrus fruits (citrus, 5 species) and uncooked potatoes (solanum tuberosum, 8 species) from the supermarket were examined which are easily available nearly all-the-year. T1, T2 and T2{sup *} relaxation times of these nature products were measured on a 1.5 Tesla MR system with adapted examination protocols and mono-exponential fitting, and compared to literature data of human parenchyma tissues, fatty tissue and body fluid (cerebrospinal fluid). Resulting values were as follows: apples: T1: 1486 - 1874 ms, T2: 163 - 281 ms, T2{sup *}: 2,3 - 3,2 ms; pears: T1: 1631 - 1969 ms, T2: 119 - 133 ms, T2{sup *}: 10,1 - 10,6 ms, citrus fruits (pulp) T1: 2055 - 2632 ms, T2: 497 - 998 ms, T2{sup *}: 151 - 182 ms; citrus fruits (skin) T1: 561 - 1669 ms, T2: 93 - 119 ms; potatoes: T1: 1011 - 1459 ms, T2: 166 - 210 ms, T2{sup *}: 20 - 30 ms. All T1-values of the examined objects (except for potatoes and skins of citrus fruits) were longer than T1 values of human tissues. Also T2 values (except for pears and skins of citrus fruits) of the fruits and the potatoes tended to be longer. T2{sup *} values of apples, pears and potatoes were shorter than in healthy human tissue. Results show relaxation values of many fruits to be not exactly fitting to human tissue, but with suitable selection of the fruits and optionally with an adaption of measurement parameters one can achieve suitable contrast and signal characteristics for some purposes. (orig.)

  13. Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder.

    Science.gov (United States)

    Thurber, Kent R; Tycko, Robert

    2009-01-01

    Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of (79)Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determination of internal sample temperatures. Advantages of this method include high signal-to-noise, proximity of the (79)Br NMR frequency to that of (13)C, applicability from 20 K to 320 K or higher, and simultaneity with adjustment of the MAS axis direction. We show that spin-lattice relaxation in KBr is driven by a quadrupolar mechanism. We demonstrate a simple approach to including KBr powder in hydrated samples, such as biological membrane samples, hydrated amyloid fibrils, and hydrated microcrystalline proteins, that allows direct assessment of the effects of frictional and radio-frequency heating under experimentally relevant conditions.

  14. Interlaboratory Comparison of a physical and a virtual assembly measured by CT

    DEFF Research Database (Denmark)

    Stolfi, Alessandro; De Chiffre, Leonardo

    2018-01-01

    In a comparison including 20 laboratories, a physical as well as a virtual assembly provided as two data sets were used to investigate measuring and post-processing approaches in Computed Tomography, CT. Different procedures were used in the comparison including one simulating in-line measurement....... The comparison demonstrated that: (i) a tangible improvement in the use of CT compared to previous comparisons; (ii) most of the participants were able to reduce their scanning time by more than 70% without increasing the length measurement errors; and (iii) most of the participants can further reduce...... their uncertainties, thereby reducing the tolerance size that can be inspected using CT in industry....

  15. Mechanisms of relaxation and spin decoherence in nanomagnets

    Science.gov (United States)

    van Tol, Johan

    Relaxation in spin systems is of great interest with respect to various possible applications like quantum information processing and storage, spintronics, and dynamic nuclear polarization (DNP). The implementation of high frequencies and fields is crucial in the study of systems with large zero-field splitting or large interactions, as for example molecular magnets and low dimensional magnetic materials. Here we will focus on the implementation of pulsed Electron Paramagnetic Resonance (ERP) at multiple frequencies of 10, 95, 120, 240, and 336 GHz, and the relaxation and decoherence processes as a function of magnetic field and temperature. Firstly, at higher frequencies the direct single-phonon spin-lattice relaxation (SLR) is considerably enhanced, and will more often than not be the dominant relaxation mechanism at low temperatures, and can be much faster than at lower fields and frequencies. In principle the measurement of the SLR rates as a function of the frequency provides a means to map the phonon density of states. Secondly, the high electron spin polarization at high fields has a strong influence on the spin fluctuations in relatively concentrated spin systems, and the contribution of the electron-electron dipolar interactions to the coherence rate can be partially quenched at low temperatures. This not only allows the study of relatively concentrated spin systems by pulsed EPR (as for example magnetic nanoparticles and molecular magnets), it enables the separation of the contribution of the fluctuations of the electron spin system from other decoherence mechanisms. Besides choice of temperature and field, several strategies in sample design, pulse sequences, or clock transitions can be employed to extend the coherence time in nanomagnets. A review will be given of the decoherence mechanisms with an attempt at a quantitative comparison of experimental rates with theory.

  16. Observation of relaxation on time scale of core hole decay by coincidence photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    It is shown by a many-body theory that when the relaxation time of a metastable core hole state(s) to the most stable one is comparable to or shorter than core hole decay time of the former state(s), a comparison between the singles (noncoincidence) photoelectron spectroscopy (PES) spectrum and the coincidence one provides a direct evidence of the relaxation. In principle the variation with photoelectron kinetic energy of relaxation (or charge transfer (CT)) time can be determined. By singles measurement the correlation of a photoelectron generated by creation of the metastable states not only with an Auger electron generated by annihilation of the same core hole state but also with an Auger electron generated by annihilation of the stable state via relaxation of the metastable state, is completely lost, unless only the metastable state is observed by PES, whereas the correlation often manifests directly in the coincidence spectra. Thus, compared to the coincidence spectroscopy the singles one is often much less capable of elucidating the competition between relaxation and core hole decay of a metastable state. Such examples are discussed

  17. Relaxation to equilibrium following photoacid dissociation in mineral acids and buffer solutions

    International Nuclear Information System (INIS)

    Pines, D; Nibbering, E T J; Pines, E

    2007-01-01

    The relaxation to the dissociation equilibrium of a weak acid undergoing a transient pK a change in the presence of a strong mineral acid has been the subject of considerable interest both experimentally and theoretically. Here we compare this process with the analogue event taking place in a buffer solution of a weak carboxylic acid. The comparison has been performed in identical pH and ionic strength conditions and at a sufficiently short timescale where the buffer can only affect the weak acid relaxation by proton scavenging. Although the two relaxation processes have been found to differ in their temporal behaviour, they have both resulted in identical equilibrium amplitudes of the photoacid. This observation reassures the well-known chemical wisdom that pK a values measured in buffer solutions do not depend on the specific chemical reactivity of the buffer. We analyse the essentially many-body relaxation problem in terms of a re-normalized geminate recombination reaction which persists over longer times than the exponential relaxation to equilibrium of homogenously distributed populations of the reactants

  18. Idiosyncratic reality claims, relaxation dispositions, and ABC relaxation theory: happiness, literal christianity, miraculous powers, metaphysics, and the paranormal.

    Science.gov (United States)

    Smith, Jonathan C; Karmin, Aaron D

    2002-12-01

    This study examined idiosyncratic reality claims, that is, irrational or paranormal beliefs often claimed to enhance relaxation and happiness and reduce stress. The Smith Idiosyncratic Reality Claims Inventory and the Smith Relaxation Dispositions Inventory (which measures relaxation and stress dispositions, or enduring states of mind frequently associated with relaxation or stress) were given to 310 junior college student volunteers. Principal components factor analysis with varimax rotation identified five idiosyncratic reality claim factors: belief in Literal Christianity; Magic; Space Aliens: After Death experiences; and Miraculous Powers of Meditation, Prayer, and Belief. No factor correlated with increased relaxation dispositions Peace, Energy, or Joy, or reduced dispositional somatic stress, worry, or negative emotion on the Smith Relaxation Dispositions Inventory. It was concluded that idiosyncratic reality claims may not be associated with reported relaxation, happiness, or stress. In contrast, previous research strongly supported self-affirming beliefs with few paranormal assumptions display such an association.

  19. Interlaboratory comparison of measuring results of magnetic field near 400 kV overhead power line

    Directory of Open Access Journals (Sweden)

    Grbić Maja

    2012-01-01

    Full Text Available The paper presents a comparison of measured results of magnetic field near 400 kV overhead power lines obtained by three laboratories. This interlaboratory comparison was performed to ensure confidence in the quality of the test results. The measured results were analyzed with standard methods, using En number, based on which the evaluation of the laboratories was performed.

  20. Relaxation of synchronization on complex networks.

    Science.gov (United States)

    Son, Seung-Woo; Jeong, Hawoong; Hong, Hyunsuk

    2008-07-01

    We study collective synchronization in a large number of coupled oscillators on various complex networks. In particular, we focus on the relaxation dynamics of the synchronization, which is important from the viewpoint of information transfer or the dynamics of system recovery from a perturbation. We measure the relaxation time tau that is required to establish global synchronization by varying the structural properties of the networks. It is found that the relaxation time in a strong-coupling regime (K>Kc) logarithmically increases with network size N , which is attributed to the initial random phase fluctuation given by O(N-1/2) . After elimination of the initial-phase fluctuation, the relaxation time is found to be independent of the system size; this implies that the local interaction that depends on the structural connectivity is irrelevant in the relaxation dynamics of the synchronization in the strong-coupling regime. The relaxation dynamics is analytically derived in a form independent of the system size, and it exhibits good consistency with numerical simulations. As an application, we also explore the recovery dynamics of the oscillators when perturbations enter the system.

  1. Vogel-Fulcher dependence of relaxation rates in a nematic monomer and elastomer

    Science.gov (United States)

    Shenoy, D.; Filippov, S.; Aliev, F.; Keller, P.; Thomsen, D.; Ratna, B.

    2000-12-01

    Dielectric relaxation spectroscopy is used to study the relaxation processes in a nematic monomer and the corresponding cross-linked polymer nematic liquid crystal (elastomer). In the frequency window 10 mHz to 2 GHz the monomer liquid crystal shows a single relaxation whereas the polymer exhibits three relaxation processes, two of which are quantitatively analyzed. The temperature dependence of relaxation times in both the monomer and polymer follows a Vogel-Fulcher behavior. The relaxation processes are identified with specific molecular motions and activation energies are calculated in a linear approximation for comparison with literature data.

  2. Verification of Electromagnetic Field Measurements via Inter-laboratory Comparison Measurements

    Directory of Open Access Journals (Sweden)

    M. Mann

    2005-01-01

    Full Text Available An inter-laboratory comparison of field strength measurements was conducted in order to verify the comparability of high-frequency electromagnetic field measurements. For this purpose, 17 participating teams hosted by the working group "procedures of exposure determination" of the LAI (Länderausschuss für Immissionsschutz, state committee on immission control determined the field strength at given stations around a hospital situation. At those stations very different signals were generated, such as sine wave signals at 27MHz and 433MHz, signals from a diathermy device in Continuous-Wave (CW and Pulse-Width-Modulation (PWM mode, from a GSM base station at 900MHz and 1800MHz, from a UMTS base station, from a babyphone device and from a DECT cordless phone. This contribution describes the evaluation of the measured values and the approach to the computation of a reference value. Considering various sources of electromagnetic fields in the areas of personal safety at work and of immission control, the most important results are presented and the conclusions drawn are discussed.

  3. InteraqCT Comparison on Assemblies - Reference Measurements

    DEFF Research Database (Denmark)

    Stolfi, Alessandro; De Chiffre, Leonardo

    2016-01-01

    The InteraqCT comparison on assemblies is as an activity within the Marie Curie ESR Project INTERAQCT - International Network for the Training of Early stage Researchers on Advanced Quality control by Computed Tomography funded by the European Commission's 7th Framework Programme FP7-PEOPLE - Under...

  4. Hair Dye and Hair Relaxers

    Science.gov (United States)

    ... For Consumers Consumer Information by Audience For Women Hair Dye and Hair Relaxers Share Tweet Linkedin Pin it More sharing ... products. If you have a bad reaction to hair dyes and relaxers, you should: Stop using the ...

  5. STUDY TO COMPARE THE EFFECTIVENESS OF STATIC STRETCH AND HOLD RELAX TECHNIQUE OVER HAMSTRING FLEXIBILITY

    Directory of Open Access Journals (Sweden)

    Shanthi C

    2014-10-01

    Full Text Available Background: Numerous studies have documented on flexibility of muscles. Flexibility is defined as the ability of the muscles to lengthen allowing one joint or more than one joint in a series to move through a range of motion .Flexibility allows tissue to accommodate more easily to stress thus minimizing or preventing muscle injury. But this study sought to identify the study to compare the effectiveness of Static stretch and Hold relax technique over the hamstring flexibility. Methods: 30 healthy male adults with Hamstring tightness aged 21 to 35 years selected from general population through simple randomized technique. Samples are divided into two groups, static stretch Group-I(no.15 and Group-II Hold relax (no.=15.The outcome was measured with help of sit & reach test to see the Hamstring flexibility. Results: Comparison of the post test values of the group I and group II shows a significant difference between the outcomes of two groups with a “t” calculated value of 0.738 (unpaired “t” test. Conclusion: Both static stretch and hold relax Technique can cause very highly significant result in Hamstring Flexibility, further comparison shows very high significant difference between two groups and concludes that hold relax is better than static stretch in Hamstring Flexibility.

  6. Development of a Rabbit Model of Radiation-Induced Sciatic Nerve Injury: In Vivo Evaluation Using T2 Relaxation Time Measurements.

    Science.gov (United States)

    Wan, Qi; Zeng, Qian; Li, Xinchun; Sun, Chongpeng; Zhou, Jiaxuan; Zou, Qiao; Deng, Yingshi; Niu, Daoli

    2015-01-01

    To develop a rabbit model of radiation-induced sciatic nerve injury (RISNI), using computed tomography (CT)-guided stereotactic radiosurgery, and assess the value of T2 measurements of injured nerves. Twenty New Zealand rabbits were randomly divided into A (n = 5) and B (n = 15) groups. Group A rabbits underwent CT and magnetic resonance scan and were then killed for comparison of images and anatomy of sciatic nerves. One side of the sciatic nerve of group B rabbits received irradiation doses of 35, 50, or 70 Gy (n = 5 per group). Magnetic resonance imaging and functional assessments were performed before irradiation and 1, 2, 3, and 4 months thereafter. The thigh section of the sciatic nerve outside the pelvis could be observed by CT and magnetic resonance imaging. T2 values of the irradiated nerve of the 35-Gy group increased gradually, peaking at 4 months; T2 values of the 50-Gy group increased faster, peaking at 3 months. Significant differences between the 35-Gy and control groups were found at 3 and 4 months, and between the 50-Gy and control groups at 2, 3, and 4 months. Functional scores of the 50-Gy group declined progressively, whereas the 35-Gy group scores reached a low point at 3 months posttreatment and then recovered. Functional scores of the irradiated limbs demonstrated a negative correlation with T2 values (r = -0.591 and -0.595, P T2 values are useful for monitoring RISNI, they may not be sensitive enough to evaluate its severity.

  7. Relaxation from particle production

    Energy Technology Data Exchange (ETDEWEB)

    Hook, Anson; Marques-Tavares, Gustavo [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States)

    2016-12-20

    We consider using particle production as a friction force by which to implement a “Relaxion” solution to the electroweak hierarchy problem. Using this approach, we are able to avoid superplanckian field excursions and avoid any conflict with the strong CP problem. The relaxation mechanism can work before, during or after inflation allowing for inflationary dynamics to play an important role or to be completely decoupled.

  8. Magnetic relaxation in anisotropic magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1971-01-01

    The line shape and the kinematic and thermodynamic slowing down of the critical and paramagnetic relaxation in axially anisotropic materials are discussed. Kinematic slowing down occurs only in the longitudinal relaxation function. The thermodynamic slowing down occurs in either the transverse...... or longitudinal relaxation function depending on the sign of the axial anisotropy....

  9. Structural relaxation dynamics and annealing effects of sodium silicate glass.

    Science.gov (United States)

    Naji, Mohamed; Piazza, Francesco; Guimbretière, Guillaume; Canizarès, Aurélien; Vaills, Yann

    2013-05-09

    Here we report high-precision measurements of structural relaxation dynamics in the glass transition range at the intermediate and short length scale for a strong sodium silicate glass during long annealing times. We evidence for the first time the heterogeneous dynamics at the intermediate range order by probing the acoustic longitudinal frequency in the GHz region by Brillouin light scattering spectroscopy. Or, from in-situ Raman measurements, we show that relaxation is indeed homogeneous at the interatomic length scale. Our results show that the dynamics at the intermediate range order contains two distinct relaxation time scales, a fast and a slow component, differing by about a 10-fold factor below Tg and approaching to one another past the glass transition. The slow relaxation time agrees with the shear relaxation time, proving that Si-O bond breaking constitutes the primary control of structural relaxation at the intermediate range order.

  10. Momentum constraint relaxation

    International Nuclear Information System (INIS)

    Marronetti, Pedro

    2006-01-01

    Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly

  11. Pairwise Comparison and Distance Measure of Hesitant Fuzzy Linguistic Term Sets

    Directory of Open Access Journals (Sweden)

    Han-Chen Huang

    2014-01-01

    Full Text Available A hesitant fuzzy linguistic term set (HFLTS, allowing experts using several possible linguistic terms to assess a qualitative linguistic variable, is very useful to express people’s hesitancy in practical decision-making problems. Up to now, a little research has been done on the comparison and distance measure of HFLTSs. In this paper, we present a comparison method for HFLTSs based on pairwise comparisons of each linguistic term in the two HFLTSs. Then, a distance measure method based on the pairwise comparison matrix of HFLTSs is proposed, and we prove that this distance is equal to the distance of the average values of HFLTSs, which makes the distance measure much more simple. Finally, the pairwise comparison and distance measure methods are utilized to develop two multicriteria decision-making approaches under hesitant fuzzy linguistic environments. The results analysis shows that our methods in this paper are more reasonable.

  12. Theoretical methods for creep and stress relaxation studies of SSC coil

    International Nuclear Information System (INIS)

    McAdams, J.; Markley, F.

    1992-04-01

    Extrapolation of laboratory measurements of SSC coil properties to the actual construction of SSC magnets requires mathematical models of the experimental data. A variety of models were used to approximate the data collected from creep and stress relaxation experiments performed on Kapton film and SSC coil samples. The coefficients for these mathematical models were found by performing a least-squares fit via the program MINUIT. Once the semiempirical expressions for the creep data were found, they were converted to expressions for stress relaxation using an approximate I pn of the Laplace integral relating the two processes. The data sets from creep experiments were also converted directly to stress relaxation data by numeric integration. Both of these methods allow comparison of data from two different methods of measuring viscoelastic properties. Three companion papers presented at this conference will present: Stress relaxation in SSC 50mm dipole coil. Measurement of the elastic modulus of Kapton perpendicular to the plane of the film at room and cryogenic temperatures. Temperature dependence of the viscoelastic properties of SSC coil insulation (Kapton)

  13. Assessment of protein solution versus crystal structure determination using spin- diffusion-suppressed NOE and heteronuclear relaxation data

    International Nuclear Information System (INIS)

    LeMaster, David M.

    1997-01-01

    A spin-diffusion-suppressed NOE buildup series has been measured for E. coli thioredoxin.The extensive 13C and 15N relaxation data previously reported for this protein allow for direct interpretation of dynamical contributions to the 1H-1H cross-relaxation rates for a large proportion of the NOE cross peaks. Estimates of the average accuracy for these derived NOE distances are bounded by 4% and 10%, based on a comparison to the corresponding X-ray distances. An independent fluctuation model is proposed for prediction of the dynamical corrections to 1H-1H cross-relaxation rates, based solely on experimental structural and heteronuclear relaxation data. This analysis is aided by the demonstration that heteronuclear order parameters greater than 0.6 depend only on the variance of the H-X bond orientation,independent of the motional model in either one- or two-dimensional diffusion (i.e., 1- S2 = 3/4 sin2 2 θσ). The combination of spin-diffusion-suppressed NOE data and analysis of dynamical corrections to 1H-1H cross-relaxation rates based on heteronuclear relaxation data has allowed for a detailed interpretation of various discrepancies between the reported solution and crystal structures

  14. Measurement comparisons of radioactivity among European monitoring laboratories for the environment and food stuff

    International Nuclear Information System (INIS)

    Waetjen, U.; Spasova, Y.; Altzitzoglou, T.

    2008-01-01

    For more than 15 years, European Union (EU) laboratories monitoring environmental radioactivity have been obliged to participate in measurement comparisons organised by the European Commission. After a short review of comparisons conducted during the 1990s, the approach of IRMM organising these comparisons since 2003 is presented. It relies on the provision of comparison samples with reference values traceable to the International Reference System for radionuclides (SIR). The results of the most recent comparison, the determination of 40 K, 90 Sr and 137 Cs in milk powder, are presented. The influence of repetitive participation in measurement comparisons on laboratory performance is studied on the basis of data from more than 20 laboratories having participated in several exercises during the last 15 years

  15. Issues in Measurement and International Comparison of Productivity - An Overview

    NARCIS (Netherlands)

    Van Ark, Bart

    1996-01-01

    This paper reviews recent development in theory and measurement of productivity performance in an international comparative perspective. It emphasises the need for a better link between the theory and practice of measurement, in particular concerning measurement of productivity levels. The paper

  16. Magneto-optical measurement of spin-lattice relaxation time in KBr and in the Na and Cs halogenetes and Co++ ion magnetic circular dichroism study in KCl

    International Nuclear Information System (INIS)

    Carvalho, R.A.

    1977-01-01

    A magnetic circular dicroism spectrometer is described, which was used in the following experiments: 1) The spin-lattice relaxation time (T 1 ) for F centers in NaCl, NaBr, CsBr and CsCl, at 1,8 0 K in magnetic fields up to 15000Gs is described. The suitability of the theory of ref. (08) to explain the differences observed for halides of differents alkali ions as well as for different structures is verified proves that the hyperfine interaction is the most important mechanism for this kind of centers. It is also verified that, for temperatures between 6 0 K and 15 0 K, T 1 experimental values fits the theory of ref. (21) reasonably well, for F centers in KBr. This theory us an extension of that of ref. (8). 2) The MCD spectra for KCl:Co ++ and Caf 2 :Co ++ in different magnetic fields up to 56KGs, and in temperature range between 1,8 0 K and 4,2 0 K is obtained. The results are consistent with the assumption that Co ++ centers are intersticial in KCl lattice [pt

  17. Measurement of the ferric diffusion coefficient in agarose and gelatine gels by utilization of the evolution of a radiation induced edge as reflected in relaxation rate images

    International Nuclear Information System (INIS)

    Pedersen, Torje V.; Olsen, Dag R.; Skretting, Arne

    1997-01-01

    A method has been developed to determine the diffusion coefficients of ferric ions in ferrous sulphate doped gels. A radiation induced edge was created in the gel, and two spin-echo sequences were used to acquire a pair of images of the gel at different points of time. For each of these image pairs, a longitudinal relaxation rate image was derived. From profiles through these images, the standard deviations of the Gaussian functions that characterize diffusion were determined. These data provided the basis for the determination of the ferric diffusion coefficients by two different methods. Simulations indicate that the use of single spin-echo images in this procedure may in some cases lead to a significant underestimation of the diffusion coefficient. The technique was applied to different agarose and gelatine gels that were prepared, irradiated and imaged simultaneously. The results indicate that the diffusion coefficient is lower in a gelatine gel than in an agarose gel. Addition of xylenol orange to a gelatine gel lowers the diffusion coefficient from 1.45 to 0.81 mm 2 h -1 , at the cost of significantly lower R 1 sensitivity. The addition of benzoic acid to the latter gel did not increase the R 1 sensitivity. (author) OK

  18. Ultrasonic relaxations in borate glasses

    International Nuclear Information System (INIS)

    D'Angelo, G.; Tripodo, G.; Carini, G.; Cosio, E.; Bartolotta, A.; Di Marco, G.

    2004-01-01

    The attenuation and velocity of ultrasonic waves of frequencies in the range from 10 to 70 MHz have been measured in M 2 O-B 2 O 3 borate glasses (M: Li or Ag) as a function of temperature between 15 and 350 K. The velocity of sound waves decreases with increasing temperature in all the glasses, the decrease as the temperature is increased is larger in glasses containing silver than in those with lithium. A broad relaxation peak characterises the attenuation behaviour of the lithium and silver borate glasses at temperatures below 100 K and is paralleled by a corresponding dispersive behaviour of the sound velocity. Above 100 K, the ultrasonic velocity shows a nearly linear behaviour regulated by the vibrational anharmonicity, which decreases with increasing content of modifier oxide and is smaller in lithium than in silver borates. These results suggest that the relaxation of structural defects and the anharmonicity of borate glasses are strongly affected by two parameters: the number of bridging bonds per network forming ion and the polarising power of network modifier ions which occupy sites in the existing interstices

  19. Interstitial relaxations due to hydrostatic stress in niobium--oxygen alloys

    International Nuclear Information System (INIS)

    Tewari, S.N.

    1974-01-01

    Experimental investigations of the anelastic relaxation induced by hydrostatic stress in the range from ambient to 81 ksi were made for niobium--oxygen alloys. The anelastic responses, both for the pressurization and the pressure release experiments, were followed by measuring the relative length change between the oxygenated niobium sample and a pure niobium frame with a precision of about 2 A. The relaxation spectrum observed was shown to be made up of three distinct relaxations with unique relaxation times and strengths. The pressure dependence of the relaxation times gave the apparent activation volume for these relaxations of the order of 4 cm 3 /mole. The relaxations were observed to have relaxation strengths of the order of 10 -4 which were found to be independent of pressure up to 81 ksi. The relaxation times for these relaxations were found to occur in the same general temperature range as those for the Snoek relaxations of oxygen clusters in niobium. The temperature dependence of the relaxation times, however, gave activation energies of about 11 to 15 kcal/mole, as compared with roughly 27 to 29 kcal/mole for the Snoek relaxation of oxygen clusters in niobium. Several possible models for these relaxations were developed, however, none could predict the observed temperature dependence. The best interpretation of the data is that due to some anomalous competing relaxation the actual temperature dependence of these relaxations could not be observed. A completely self-consistent analysis is found which is based upon this assumption. (U.S.)

  20. Comparison of spectroscopically measured tissue alcohol concentration to blood and breath alcohol measurements

    Science.gov (United States)

    Ridder, Trent D.; Ver Steeg, Benjamin J.; Laaksonen, Bentley D.

    2009-09-01

    Alcohol testing is an expanding area of interest due to the impacts of alcohol abuse that extend well beyond drunk driving. However, existing approaches such as blood and urine assays are hampered in some testing environments by biohazard risks. A noninvasive, in vivo spectroscopic technique offers a promising alternative, as no body fluids are required. The purpose of this work is to report the results of a 36-subject clinical study designed to characterize tissue alcohol measured using near-infrared spectroscopy relative to venous blood, capillary blood, and breath alcohol. Comparison of blood and breath alcohol concentrations demonstrated significant differences in alcohol concentration [root mean square of 9.0 to 13.5 mg/dL] that were attributable to both assay accuracy and precision as well as alcohol pharmacokinetics. A first-order kinetic model was used to estimate the contribution of alcohol pharmacokinetics to the differences in concentration observed between the blood, breath, and tissue assays. All pair-wise combinations of alcohol assays were investigated, and the fraction of the alcohol concentration variance explained by pharmacokinetics ranged from 41.0% to 83.5%. Accounting for pharmacokinetic concentration differences, the accuracy and precision of the spectroscopic tissue assay were found to be comparable to those of the blood and breath assays.

  1. Comparison of electric field exposure measurement methods under power lines

    International Nuclear Information System (INIS)

    Korpinen, L.; Kuisti, H.; Tarao, H.; Paeaekkoenen, R.; Elovaara, J.

    2014-01-01

    The object of the study was to investigate extremely low frequency (ELF) electric field exposure measurement methods under power lines. The authors compared two different methods under power lines: in Method A, the sensor was placed on a tripod; and Method B required the measurer to hold the meter horizontally so that the distance from him/her was at least 1.5 m. The study includes 20 measurements in three places under 400 kV power lines. The authors used two commercial three-axis meters, EFA-3 and EFA-300. In statistical analyses, they did not find significant differences between Methods A and B. However, in the future, it is important to take into account that measurement methods can, in some cases, influence ELF electric field measurement results, and it is important to report the methods used so that it is possible to repeat the measurements. (authors)

  2. Quantitative comparison of measurements of urgent care service quality.

    Science.gov (United States)

    Qin, Hong; Prybutok, Victor; Prybutok, Gayle

    2016-01-01

    Service quality and patient satisfaction are essential to health care organization success. Parasuraman, Zeithaml, and Berry introduced SERVQUAL, a prominent service quality measure not yet applied to urgent care. We develop an instrument to measure perceived service quality and identify the determinants of patient satisfaction/ behavioral intentions. We examine the relationships among perceived service quality, patient satisfaction and behavioral intentions, and demonstrate that urgent care service quality is not equivalent using measures of perceptions only, differences of expectations minus perceptions, ratio of perceptions to expectations, and the log of the ratio. Perceptions provide the best measure of urgent care service quality.

  3. Effect of relaxation and decay of a charge transfer shakeup satellite on Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of adsorbates

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2008-01-01

    An electron excited to an unoccupied part of adsorbate-substrate hybrid states in a chemisorbed molecule by a resonant core electron excitation or charge transfer (CT) shakeup may delocalize on time scale of core-hole decay so that the excited core-hole state relaxes partly or completely to a fully relaxed one. The Auger decay of the fully relaxed core-hole state via the relaxation of the excited one introduces an additional feature in the resonant Auger-electron spectroscopy (RAES) spectrum and the AES spectrum. However, the additional feature in the RAES spectrum is a normal AES spectrum by decay of the fully relaxed core-hole state, whereas the one in the AES spectrum is the AES spectrum by decay of the fully relaxed core-hole state broadened by the photoelectron spectroscopy (PES) CT shakeup satellite weighted by the branching ratio of the relaxation width. The discrepancies between the AES spectrum measured at high above the ionization threshold and the additional feature in the RAES spectrum consist of the symmetric-like part by the decay of the fully relaxed core-hole state via the relaxation of the CT shakeup state and the asymmetric part by the direct decay of the shakeup states. The asymmetric part increases with a decrease in the hybridization strength. This explains the variation with the hybridization strength in the discrepancies between the RAES spectra and the AES spectra of chemisorbed molecules such as CO/Ni, CO/Cu and CO/Ag. A comparison of the singles PES spectrum with the one measured in coincidence with the AES main line of a selected kinetic energy (KE) provides the delocalization rate of the excited electron in the CT shakeup state as a function of photoelectron KE. The coincidence measurement to obtain the partial singles PES spectrum is discussed

  4. Comparison between Medgem and Deltatrac resting metabolic rate measurements.

    Science.gov (United States)

    Compher, C; Hise, M; Sternberg, A; Kinosian, B P

    2005-10-01

    The primary aims of this trial were to evaluate the reproducibility of a portable handheld calorimeter (Medgem) in a clinical population, and to compare its measures with a calorimeter in typical use with these patients. Cross-sectional clinical validation study. Outpatient Clinical Research Center. A total of 24 stable home nutrition support patients. In random order three measures of resting metabolic rate (RMR) were taken after a 4-h fast, 15 min rest and 2-h abstention from exercise. Two measures were taken with the same Medgem (MG) and one with the traditional calorimeter (Deltatrac). Reproducibility of MG measures and their comparability to a Deltatrac measure were assessed by Bland-Altman analysis, with >+/-250 kcal/day established a priori as a clinically unacceptable error. In addition, disagreement between the two types of measures was defined as greater than 10% difference. The mean difference between two MG measures was -6.8 kcal/day, with limits of agreement between 233 and -247 kcal/day and clinically acceptable. The mean difference between the Deltatrac and mean of two MG measures was -162 kcal/day, with limits of agreement between 577 and -253 kcal/day and clinically unacceptable. In all, 80% of the repeated MG RMR measures agreed within 10%, and the mean MG reading agreed with the Deltatrac in 60% of cases. RMR obtained using the MG calorimeter has an acceptable degree of reproducibility, and is acceptable to patients. The MG measures, however, are frequently lower than traditional measures and require further validation prior to application to practice in this vulnerable patient group.

  5. Relaxation Time of High-Density Amorphous Ice

    Science.gov (United States)

    Handle, Philip H.; Seidl, Markus; Loerting, Thomas

    2012-06-01

    Amorphous water plays a fundamental role in astrophysics, cryoelectron microscopy, hydration of matter, and our understanding of anomalous liquid water properties. Yet, the characteristics of the relaxation processes taking place in high-density amorphous ice (HDA) are unknown. We here reveal that the relaxation processes in HDA at 110-135 K at 0.1-0.2 GPa are of collective and global nature, resembling the alpha relaxation in glassy material. Measured relaxation times suggest liquid-like relaxation characteristics in the vicinity of the crystallization temperature at 145 K. By carefully relaxing pressurized HDA for several hours at 135 K, we produce a state that is closer to the ideal glass state than all HDA states discussed so far in literature.

  6. A comparison of two different sound intensity measurement principles

    DEFF Research Database (Denmark)

    Jacobsen, Finn; de Bree, Hans-Elias

    2005-01-01

    , and compares the two measurement principles with particular regard to the sources of error in sound power determination. It is shown that the phase calibration of intensity probes that combine different transducers is very critical below 500 Hz if the measurement surface is very close to the source under test...

  7. A Comparison of Two Measures of Parental Behavior

    Science.gov (United States)

    Safford, Scott M.; Alloy, Lauren B.; Pieracci, Antonia

    2007-01-01

    We compared two common measures of parenting behavior, the Children's Report of Parental Behavior Inventory (CRPBI) and the Parental Bonding Instrument (PBI), evaluating their psychometric properties and predictive ability. One hundred sixty seven college students completed the CRPBI, PBI, and measures of depression and anxiety with 123…

  8. Comparison of measures of functional disability in patients with gout

    NARCIS (Netherlands)

    ten Klooster, Peter M.; Oude Voshaar, Antonius H.; Taal, Erik; van de Laar, Mart A F J

    2011-01-01

    Objective. To compare the measurement properties of the HAQ disability index (HAQ-DI), HAQ-II and short form 36 physical functioning scale (PF-10) in patients with gout. Methods. A cross-sectional sample of 97 patients with gout completed all three measures. Reliability was assessed by examining the

  9. The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

    International Nuclear Information System (INIS)

    Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G; Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S

    2011-01-01

    Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

  10. The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G [School of Physics, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009 (Australia); Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S, E-mail: stpierre@physics.uwa.edu.au [Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States)

    2011-08-12

    Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

  11. A comparison of blood pressure measurements in newborns.

    LENUS (Irish Health Repository)

    O'Shea, Joyce

    2012-02-01

    Blood pressure monitoring is an essential component of neonatal intensive care. We compared invasive and noninvasive (Dinamap, Marquette, and Dash) recordings in newborns and also noninvasive values obtained from upper and lower limbs. Infants\\' blood pressure was recorded every 6 hours for 72 hours using three noninvasive devices and compared with invasive readings taken simultaneously. Twenty-five babies were enrolled in the study, with birth weights of 560 to 4500 g and gestation 24 + 1 to 40 + 5 weeks. Three hundred thirty-two recordings were obtained. Comparison between invasive and noninvasive readings revealed that all three noninvasive monitors overread mean blood pressure. There was no significant difference between the cuff recordings obtained from the upper or lower limbs. All three noninvasive devices overestimated mean blood pressure values compared with invasive monitoring. Clinicians may be falsely reassured by noninvasive monitoring. Mean blood pressure values obtained from the upper and lower limb are similar.

  12. Comparison of seasonal variability in European domestic radon measurements

    Science.gov (United States)

    Groves-Kirkby, C. J.; Denman, A. R.; Phillips, P. S.; Crockett, R. G. M.; Sinclair, J. M.

    2010-03-01

    Analysis of published data characterising seasonal variability of domestic radon concentrations in Europe and elsewhere shows significant variability between different countries and between regions where regional data is available. Comparison is facilitated by application of the Gini Coefficient methodology to reported seasonal variation data. Overall, radon-rich sedimentary strata, particularly high-porosity limestones, exhibit high seasonal variation, while radon-rich igneous lithologies demonstrate relatively constant, but somewhat higher, radon concentrations. High-variability regions include the Pennines and South Downs in England, Languedoc and Brittany in France, and especially Switzerland. Low-variability high-radon regions include the granite-rich Cornwall/Devon peninsula in England, and Auvergne and Ardennes in France, all components of the Devonian-Carboniferous Hercynian belt.

  13. Comparison of seasonal variability in European domestic radon measurements

    Directory of Open Access Journals (Sweden)

    C. J. Groves-Kirkby

    2010-03-01

    Full Text Available Analysis of published data characterising seasonal variability of domestic radon concentrations in Europe and elsewhere shows significant variability between different countries and between regions where regional data is available. Comparison is facilitated by application of the Gini Coefficient methodology to reported seasonal variation data. Overall, radon-rich sedimentary strata, particularly high-porosity limestones, exhibit high seasonal variation, while radon-rich igneous lithologies demonstrate relatively constant, but somewhat higher, radon concentrations. High-variability regions include the Pennines and South Downs in England, Languedoc and Brittany in France, and especially Switzerland. Low-variability high-radon regions include the granite-rich Cornwall/Devon peninsula in England, and Auvergne and Ardennes in France, all components of the Devonian-Carboniferous Hercynian belt.

  14. Variational formulation of relaxed and multi-region relaxed magnetohydrodynamics

    Science.gov (United States)

    Dewar, R. L.; Yoshida, Z.; Bhattacharjee, A.; Hudson, S. R.

    2015-12-01

    > Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor relaxation model for formation of macroscopically self-organized plasma equilibrium states, all these constraints are relaxed save for the global magnetic fluxes and helicity. A Lagrangian variational principle is presented that leads to a new, fully dynamical, relaxed magnetohydrodynamics (RxMHD), such that all static solutions are Taylor states but also allows state with flow. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-region relaxed magnetohydrodynamics (MRxMHD) is developed.

  15. NMR relaxation times of natural rubber latex

    International Nuclear Information System (INIS)

    Harun, S.; Aziz, H.; Basir, Z.

    1994-01-01

    NMR relaxation times T sub 1 and T sub 2 of natural rubber latex have been measured at 25 degree C on a pulsed NMR spectrometer. The work focuses on the variation of the relaxation times with the amount of water content from 0% to 50%. The water content was adjusted by centrifuging and removing a certain amount of water from the sample. The data were analysed using a biexponential fitting procedure which yields simultaneously either T sub 1a and T sub 1b or T sub 2a and T sub 2b. The amount of solid was compared with the known amount of dry rubber content

  16. Structural relaxation monitored by instantaneous shear modulus

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil

    1998-01-01

    time definition based on a recently proposed expression for the relaxation time, where G [infinity] reflects the fictive temperature. All parameters entering the reduced time were determined from independent measurements of the frequency-dependent shear modulus of the equilibrium liquid....

  17. Comparison of global sensitivity analysis techniques and importance measures in PSA

    International Nuclear Information System (INIS)

    Borgonovo, E.; Apostolakis, G.E.; Tarantola, S.; Saltelli, A.

    2003-01-01

    This paper discusses application and results of global sensitivity analysis techniques to probabilistic safety assessment (PSA) models, and their comparison to importance measures. This comparison allows one to understand whether PSA elements that are important to the risk, as revealed by importance measures, are also important contributors to the model uncertainty, as revealed by global sensitivity analysis. We show that, due to epistemic dependence, uncertainty and global sensitivity analysis of PSA models must be performed at the parameter level. A difficulty arises, since standard codes produce the calculations at the basic event level. We discuss both the indirect comparison through importance measures computed for basic events, and the direct comparison performed using the differential importance measure and the Fussell-Vesely importance at the parameter level. Results are discussed for the large LLOCA sequence of the advanced test reactor PSA

  18. A Comparison of two measures of quality of life of Nigerian clinic ...

    African Journals Online (AJOL)

    A Comparison of two measures of quality of life of Nigerian clinic patients with ... well-being questionnaire and the WHOQOL-BREF, a generic instrument. ... not influenced by characteristics such as age, gender, marital or educational status.

  19. Excited-state relaxation of some aminoquinolines

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The absorption and fluorescence spectra, fluorescence quantum yields and lifetimes, and fluorescence rate constants ( k f of 2-amino-3-( 2 ′ -benzoxazolylquinoline (I, 2-amino-3-( 2 ′ -benzothiazolylquinoline (II, 2-amino-3-( 2 ′ -methoxybenzothiazolyl-quinoline (III, 2-amino-3-( 2 ′ -benzothiazolylbenzoquinoline (IV at different temperatures have been measured. The shortwavelength shift of fluorescence spectra of compounds studied (23–49 nm in ethanol as the temperature decreases (the solvent viscosity increases points out that the excited-state relaxation process takes place. The rate of this process depends essentially on the solvent viscosity, but not the solvent polarity. The essential increasing of fluorescence rate constant k f (up to about 7 times as the solvent viscosity increases proves the existence of excited-state structural relaxation consisting in the mutual internal rotation of molecular fragments of aminoquinolines studied, followed by the solvent orientational relaxation.

  20. Comparison of Simulated and Measured Non-linear Ultrasound Fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2011-01-01

    In this paper results from a non-linear AS (angular spectrum) based ultrasound simulation program are compared to water-tank measurements. A circular concave transducer with a diameter of 1 inch (25.4 mm) is used as the emitting source. The measured pulses are rst compared with the linear...... simulation program Field II, which will be used to generate the source for the AS simulation. The generated non-linear ultrasound eld is measured by a hydrophone in the focal plane. The second harmonic component from the measurement is compared with the AS simulation, which is used to calculate both...... fundamental and second harmonic elds. The focused piston transducer with a center frequency of 5 MHz is excited by a waveform generator emitting a 6-cycle sine wave. The hydrophone is mounted in the focal plane 118 mm from the transducer. The point spread functions at the focal depth from Field II...

  1. Liquid scintillation cocktails comparison for tritium contamination measurements

    International Nuclear Information System (INIS)

    Bazzarri, S.; Belloni, P.

    1996-01-01

    Liquid scintillation counting is one of the most used techniques for the measurements of tritium contamination. Until few years ago a problem related to this kind of measurement was the potential toxicity of the liquid cocktails used to produce the required scintillation. Some new products that guarantee an almost negligible impact on the environment and that are no longer toxic for the operators are now available. Some of this new scintillation cocktail are suitable to be used for tritium measurement. Due to the great benefit from the health point of view of these new materials a test of their scintillation performance has been done at the ENEA centers to select the product having the best characteristics for tritium measurement. (author)

  2. Dynamics of relaxed inflation

    Science.gov (United States)

    Tangarife, Walter; Tobioka, Kohsaku; Ubaldi, Lorenzo; Volansky, Tomer

    2018-02-01

    The cosmological relaxation of the electroweak scale has been proposed as a mechanism to address the hierarchy problem of the Standard Model. A field, the relaxion, rolls down its potential and, in doing so, scans the squared mass parameter of the Higgs, relaxing it to a parametrically small value. In this work, we promote the relaxion to an inflaton. We couple it to Abelian gauge bosons, thereby introducing the necessary dissipation mechanism which slows down the field in the last stages. We describe a novel reheating mechanism, which relies on the gauge-boson production leading to strong electro-magnetic fields, and proceeds via the vacuum production of electron-positron pairs through the Schwinger effect. We refer to this mechanism as Schwinger reheating. We discuss the cosmological dynamics of the model and the phenomenological constraints from CMB and other experiments. We find that a cutoff close to the Planck scale may be achieved. In its minimal form, the model does not generate sufficient curvature perturbations and additional ingredients, such as a curvaton field, are needed.

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

    Science.gov (United States)

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

    2003-01-01

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

  4. Comparison of current tonometry techniques in measurement of intraocular pressure.

    Science.gov (United States)

    Kouchaki, Behrooz; Hashemi, Hassan; Yekta, Abbasali; Khabazkhoob, Mehdi

    2017-06-01

    To compare four tonometry techniques: Goldmann applanation tonometer (GAT), Dynamic contour tonometer (DCT), Non-contact tonometer (NCT), and Ocular Response Analyzer (ORA) in the measurement of intraocular pressure (IOP) and the impact of some corneal biomechanical factors on their performance. In this cross-sectional study, volunteers with normal ophthalmic examination and no history of eye surgery (except for uncomplicated cataract surgery) or trauma were selected. Twenty-five subjects were male, and 21 were female. The mean age was 48 ± 19.2 years. Anterior segment parameters were measured with Scheimpflug imaging. IOP was measured with GAT, DCT, NCT, and ORA in random order. A 95% limit of agreement of IOPs was analyzed. The impact of different parameters on the measured IOP with each device was evaluated by regression analysis. The average IOP measured with GAT, DCT, NCT, and ORA was 16.4 ± 3.5, 18.1 ± 3.4, 16.2 ± 3.9, and 17.3 ± 3.4 mmHg, respectively. The difference of IOP measured with NCT and GAT was not significant ( P  = 0.382). Intraocular pressure was significantly different between GAT with DCT and IOP CC ( P  tonometers.

  5. Measuring caloric response: comparison of different analysis techniques.

    Science.gov (United States)

    Mallinson, A I; Longridge, N S; Pace-Asciak, P; Ngo, R

    2010-01-01

    Electronystagmography (ENG) testing has been supplanted by newer techniques of measuring eye movement with infrared cameras (VNG). Most techniques of quantifying caloric induced nystagmus measure the slow phase velocity in some manner. Although our analysis is carried out by very experienced assessors, some systems have computer algorithms that have been "taught" to locate and quantify maximum responses. We wondered what differences in measurement might show up when measuring calorics using different techniques and systems, the relevance of this being that if there was a change in slow phase velocity between ENG and VNG testing when measuring caloric response, then normative data would have to be changed. There are also some subjective but important aspects of ENG interpretation which comment on the nature of the response (e.g. responses which might be "sporadic" or "scant"). Our experiment compared caloric responses in 100 patients analyzed four different ways. Each caloric was analyzed by our old ENG system, our new VNG system, an inexperienced assessor and the computer algorithm, and data was compared. All four systems made similar measurements but our inexperienced assessor failed to recognize responses as sporadic or scant, and we feel this is a limitation to be kept in mind in the rural setting, as it is an important aspect of assessment in complex patients. Assessment of complex VNGs should be left to an experienced assessor.

  6. Comparison of measured and calculated burn-up of AVR-Fuel-Elements

    Energy Technology Data Exchange (ETDEWEB)

    Wagemann, R.

    1974-03-15

    Burn-up comparisons are made for small batches of three types of AVR fuel elements using a coupled EREBUS-MUPO neutronic analysis compared against test results from both nondestructive gamma-ray measurements of cesium-137 activity and destructive mass spectrometry measurements of the ratio of U-233 to U-235. The comparisons are relatively good for average burn-up and reasonably good for burn-up distributions.

  7. Interlaboratory comparisons in kerma in the air measures and absorbed dose in water using 60Co beams in radiotherapy

    International Nuclear Information System (INIS)

    Rosado, Paulo Henrique Goncalves; Silva, Cosme Norival Mello da

    2013-01-01

    In order to ensure that the measures of a quantity have high reliability and traceability interlaboratory comparisons are performed. The LNMRI has participated in several these interlaboratory comparisons. In the period 2000-2013 the LNMRI participated in 5 interlaboratory comparisons for measurement of kerma coefficients in the air and absorbed dose coefficients in the water. The results of interlaboratory comparisons indicate that the measures taken are appropriate to the LNMRI regarding the accuracy and precision measuring of these quantities

  8. Wall relaxation rates for an optically pumped NA vapor

    International Nuclear Information System (INIS)

    Swenson, D.R.; Anderson, L.W.

    1986-01-01

    The wall relaxation rates for an optically pumped Na vapor have been measured for a variety of wall surfaces. We find that fluorocarbon rubber (Fluorel, Viton) and organosilicones (silicone rubber, dry film) at a temperature of 250 C have respectively relaxation rates that correspond on the average to 10 to 15 and 200 to 500 bounces before depolarization occurs. 7 refs., 3 figs

  9. Dielectric relaxation phenomena of rigid polar liquid molecules ...

    Indian Academy of Sciences (India)

    The probability of showing double relaxation is ... liquids can, however, be inferred from the measured relaxation time τ by Cole–Cole [3], ... A graphical method [13] was, soon employed from Fr¨ohlich's distribution function [14] to ...... tive to choose a few data for some systems for which chi-square values were adjusted to.

  10. Progress in organizing national and international comparisons for nuclear medicine measurements

    International Nuclear Information System (INIS)

    Sahagia, Maria; Waetjen, Anamaria C.; Ivan, Constantin

    2008-01-01

    The paper presents the progress registered by the Radionuclide Metrology Laboratory (RML) from IFIN-HH, in improvement of the quality of radiopharmaceuticals activity measurement, and assurance of the whole traceability chain from international level to the national users. The progress in organization of comparisons for radiopharmaceuticals activity measurement is analyzed. A detailed description of two recent national comparisons, and an international one, regarding 131 I solutions, within the frame of the IAEA's CRP E2.10.05 'Harmonization of quality practices for nuclear medicine radioactivity measurements' is done, with the analysis of the strong and week points in measurements. The most important outcome of the paper is the analysis of the evolution in quality of comparisons since a previously reported one. At the RML level, the improvements are: demonstration of the international equivalence of primary Romanian activity standard, improvement of the secondary standard, relevance of the comparison within the IAEA frame, implementation of a quality system in standardization and in comparisons, and implication of the RML in calibrations and metrological checks. The participants' reported improvements refer to growing of the awareness in quality of measurement and improvement of the measurement equipment. Reasons for future comparisons organization are presented. (author)

  11. Lessons learnt from participation in international inter-comparison exercise for environmental radioactivity measurement

    International Nuclear Information System (INIS)

    Jha, S.K.; Pulhani, Vandana; Sartandel, Sangeeta

    2016-06-01

    Environmental Radioactivity Measurement Section of Health Physics Division is regularly carrying out surveillance of the radioactivity concentration in the environment. The laboratory participates in the inter-comparison exercises conducted by various international agencies for quality assurance and quality control of analytical estimations. This report summarizes the results of the analysis of radioactivity in environmental matrices of the inter-comparison exercises. The participation in inter-comparison exercises has demonstrated competence in radionuclide identification and estimations, equivalence with the results of other participating laboratories, validated adopted analytical methods, introduced traceability to measurement etc. at national and international level. (author)

  12. Comparison of solar irradiances measured by SBUV, SME, and rockets

    International Nuclear Information System (INIS)

    Schlesinger, B.M.; Heath, D.F.

    1988-01-01

    Solar Backscatter Ultraviolet (SBUV) measurements of the solar irradiance between 170 and 320 nm have been compared with rocket and Solar Mesosphere Explorer (SME) ultraviolet spectrometer measurements. The SBUV and SME data were those available from the National Space Sciences Data Center (NSSDC). The published rocket measurement are sensitive enough to detect substantial systematic changes with time in other instruments and to check absolute calibration but not sufficiently sensitive to validate claims of changes in the solar ultraviolet irradiance longer than 170 nm. The SBUV irradiances show as systematic decrease with time not seen in the rocket measurements; a correction for this decrease, based on changes between the instrument properties measured in 1980--1981 and those in 1984, is introduced. Ratios of spectra in early 1982 to those in mid-1984, calculated using the SME and SBUV solar irradiances, have been compared with each other asnd with those predicted from Mg 280-nm variations. The scatter and overall structure in the SME spectra from the NSSDC is 3--5%, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1% such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the Sun. copyright American Geophysical Union 1988

  13. Comparison of non-invasive tear film stability measurement techniques.

    Science.gov (United States)

    Wang, Michael Tm; Murphy, Paul J; Blades, Kenneth J; Craig, Jennifer P

    2018-01-01

    Measurement of tear film stability is commonly used to give an indication of tear film quality but a number of non-invasive techniques exists within the clinical setting. This study sought to compare three non-invasive tear film stability measurement techniques: instrument-mounted wide-field white light clinical interferometry, instrument-mounted keratoscopy and hand-held keratoscopy. Twenty-two subjects were recruited in a prospective, randomised, masked, cross-over study. Tear film break-up or thinning time was measured non-invasively by independent experienced examiners, with each of the three devices, in a randomised order, within an hour. Significant correlation was observed between instrument-mounted interferometric and keratoscopic measurements (p 0.05). Tear film stability values obtained from the hand-held device were significantly shorter and demonstrated narrower spread than the other two instruments (all p 0.05). Good clinical agreement exists between the instrument-mounted interferometric and keratoscopic measurements but not between the hand-held device and either of the instrument-mounted techniques. The results highlight the importance of specifying the instrument employed to record non-invasive tear film stability. © 2017 Optometry Australia.

  14. A comparison of performance measures for online algorithms

    DEFF Research Database (Denmark)

    Boyar, Joan; Irani, Sandy; Larsen, Kim Skak

    2009-01-01

    is to balance greediness and adaptability. We examine how these measures evaluate the Greedy Algorithm and Lazy Double Coverage, commonly studied algorithms in the context of server problems. We examine Competitive Analysis, the Max/Max Ratio, the Random Order Ratio, Bijective Analysis and Relative Worst Order...... Analysis and determine how they compare the two algorithms. We find that by the Max/Max Ratio and Bijective Analysis, Greedy is the better algorithm. Under the other measures Lazy Double Coverage is better, though Relative Worst Order Analysis indicates that Greedy is sometimes better. Our results also...... provide the first proof of optimality of an algorithm under Relative Worst Order Analysis....

  15. Comparison of Particulate Mercury Measured with Manual and Automated Methods

    Directory of Open Access Journals (Sweden)

    Rachel Russo

    2011-01-01

    Full Text Available A study was conducted to compare measuring particulate mercury (HgP with the manual filter method and the automated Tekran system. Simultaneous measurements were conducted with the Tekran and Teflon filter methodologies in the marine and coastal continental atmospheres. Overall, the filter HgP values were on the average 21% higher than the Tekran HgP, and >85% of the data were outside of ±25% region surrounding the 1:1 line. In some cases the filter values were as much as 3-fold greater, with

  16. Repeatability and reliability of muscle relaxation properties induced by motor cortical stimulation.

    Science.gov (United States)

    Molenaar, Joery P; Voermans, Nicol C; de Jong, Lysanne A; Stegeman, Dick F; Doorduin, Jonne; van Engelen, Baziel G

    2018-03-15

    Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39.1{plus minus}12.7 and 45.3{plus minus}8.7 years old, respectively) using handgrip dynamometry. All outcome measures showed greater repeatability and reliability in TMS-induced relaxation compared to voluntary relaxation. The within-subject coefficient of variability of normalized peak relaxation rate was lower in TMS-induced relaxation than in voluntary relaxation (3.0 vs 19.7% in men, and 6.1 vs 14.3% in women). The repeatability coefficient was lower (1.3 vs 6.1 s -1 in men and 2.3 vs 3.1 s -1 in women), and the intraclass correlation coefficient was higher (0.95 vs 0.53 in men and 0.78 vs 0.69 in women), for TMS-induced relaxation compared to voluntary relaxation. TMS enabled to demonstrate slowing effects of sex, muscle cooling, and muscle fatigue on relaxation properties that voluntary relaxation could not. In conclusion, repeatability and reliability of TMS-induced muscle relaxation was greater compared to voluntary muscle relaxation. TMS-induced muscle relaxation has the potential to be used in clinical practice for diagnostic purposes and therapy effect monitoring in patients with impaired muscle relaxation.

  17. Comparison of Coordinate Measuring Machines using an Optomechanical Hole Plate

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Hansen, Hans Nørgaard; Morace, Renata Erica

    2005-01-01

    This paper describes modelling of an integrated AFM - CMM instrument, its calibration, and estimation of measurement uncertainty. Positioning errors were seen to limit the instrument performance. Software for off-line stitching of single AFM scans was developed and verified, which allows compensa...

  18. Comparison of current tonometry techniques in measurement of intraocular pressure

    Directory of Open Access Journals (Sweden)

    Behrooz Kouchaki

    2017-06-01

    Conclusion: Although the mean difference of measured IOP by NCT, DCT, and ORA with GAT was less than 2 mmHg, the limit of agreement was relatively large. CCT and CRF were important influencing factors in the four types of tonometers.

  19. Comparison of predicted and measured variations of indoor radon concentration

    International Nuclear Information System (INIS)

    Arvela, H.; Voutilainen, A.; Maekelaeinen, I.; Castren, O.; Winqvist, K.

    1988-01-01

    Prediction of the variations of indoor radon concentration were calculated using a model relating indoor radon concentration to radon entry rate, air infiltration and meteorological factors. These calculated variations have been compared with seasonal variations of 33 houses during 1-4 years, with winter-summer concentration ratios of 300 houses and the measured diurnal variation. In houses with a slab in ground contact the measured seasonal variations are quite often in agreement with variations predicted for nearly pure pressure difference driven flow. The contribution of a diffusion source is significant in houses with large porous concrete walls against the ground. Air flow due to seasonally variable thermal convection within eskers strongly affects the seasonal variations within houses located thereon. Measured and predicted winter-summer concentration ratios demonstrate that, on average, the ratio is a function of radon concentration. The ratio increases with increasing winter concentration. According to the model the diurnal maximum caused by a pressure difference driven flow occurs in the morning, a finding which is in agreement with the measurements. The model presented can be used for differentiating between factors affecting radon entry into houses. (author)

  20. Vessel size measurements in angiograms: A comparison of techniques

    International Nuclear Information System (INIS)

    Hoffmann, Kenneth R.; Nazareth, Daryl P.; Miskolczi, Laszlo; Gopal, Anant; Wang Zhou; Rudin, Stephen; Bednarek, Daniel R.

    2002-01-01

    As interventional procedures become more complicated, the need for accurate quantitative vascular information increases. In response to this need, many commercial vendors provide techniques for measurement of vessel sizes, usually based on derivative techniques. In this study, we investigate the accuracy of several techniques used in the measurement of vessel size. Simulated images of vessels having circular cross sections were generated and convolved with various focal spot distributions taking into account the magnification. These vessel images were then convolved with Gaussian image detector line spread functions (LSFs). Additionally, images of a phantom containing vessels with a range of diameters were acquired for the 4.5'', 6'', 9'', and 12'' modes of an image intensifier-TV (II-TV) system. Vessel sizes in the images were determined using a first-derivative technique, a second-derivative technique, a linear combination of these two measured sizes, a thresholding technique, a densitometric technique, and a model-based technique. For the same focal spot size, the shape of the focal spot distribution does not affect measured vessel sizes except at large magnifications. For vessels with diameters larger than the full-width-at-half-maximum (FWHM) of the LSF, accurate vessel sizes (errors ∼0.1 mm) could be obtained by using an average of sizes determined by the first and second derivatives. For vessels with diameters smaller than the FWHM of the LSF, the densitometric and model-based techniques can provide accurate vessel sizes when these techniques are properly calibrated

  1. Comparison for some measured and calculated nuclear Parameters ...

    African Journals Online (AJOL)

    The computed thermal neutron flux levels in the radial and axial direct-ions for different zones of the reactor compared favourably with measured values obtained from the zero power critical experiments. The trends of fast, slowing down, epithermal and thermal fluxes were also predicted. Journal of Applied Science and ...

  2. National comparison of activity measurements of 131I, 60Co, and 133Ba in Indonesia

    International Nuclear Information System (INIS)

    Wurdiyanto, Gatot; Marsoem, Pujadi; Widodo, Susilo; Iskandar, Dadong; Muhayatun; Hartoyo, Unggul; Sugino; Gede Sutresna, I.; Hutabarat, Tommy; Suparman, Ibon; Purwanto, Setyo

    2014-01-01

    National comparisons of radioactivity measurements of 131 I and 60 Co (in 2010) and of 133 Ba (in 2011) were carried out within the framework of the National Radiation Metrology Laboratory Program of Indonesia, coordinated by PTKMR-BATAN. Eleven laboratories took part in the comparison, and all measurements were made using gamma spectrometry, on point sources with an activity between 2000 Bq and 6000 Bq. Several laboratories reported values which were more than 10% different from the reference value for 131 I and 133 Ba. Possible reasons for these differences are discussed. This program will be continued with other radionuclides to maintain and control quality assurance for the local laboratories. - Highlights: • PTKMR-BATAN coordinated national comparison of 131 I, 60 Co and 133 Ba. • Eleven laboratories took part in the comparison. • All measurements were done using gamma spectrometry methods. • For 131 I and 133 Ba, 3 laboratories have more than 10% difference from reference laboratory value

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

    Science.gov (United States)

    Koo, A.; Clare, J. F.

    2012-06-01

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

  4. Relaxation training after stroke: potential to reduce anxiety.

    Science.gov (United States)

    Kneebone, Ian; Walker-Samuel, Natalie; Swanston, Jennifer; Otto, Elisabeth

    2014-01-01

    To consider the feasibility of setting up a relaxation group to treat symptoms of post stroke anxiety in an in-patient post-acute setting; and to explore the effectiveness of relaxation training in reducing self-reported tension. A relaxation group protocol was developed in consultation with a multidisciplinary team and a user group. Over a period of 24 months, 55 stroke patients attended group autogenic relaxation training on a rehabilitation ward. Attendance ranged between one and eleven sessions. Self-reported tension was assessed pre and post relaxation training using the Tension Rating Circles (TRCs). The TRCs identified a significant reduction in self-reported tension from pre to post training, irrespective of the number of sessions attended; z = -3.656, p training. The TRCs proved acceptable to group members, but should be validated against standard anxiety measures. Further exploration of the application of relaxation techniques in clinical practice is desirable. Implications for Rehabilitation Anxiety is prevalent after stroke and likely affects rehabilitation outcomes. Relaxation training is a well proven treatment for anxiety in the non-stroke population. A significant within session reduction in tension, a hallmark symptom of anxiety, was evidenced via group relaxation training delivered in a post-acute, in-patient stroke unit setting. Relaxation training a shows promise as a treatment for anxiety after stroke.

  5. Spin transport and relaxation in graphene

    International Nuclear Information System (INIS)

    Han Wei; McCreary, K.M.; Pi, K.; Wang, W.H.; Li Yan; Wen, H.; Chen, J.R.; Kawakami, R.K.

    2012-01-01

    We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for

  6. Comparison of nanoparticle measurement instruments for occupational health applications

    International Nuclear Information System (INIS)

    Leskinen, J.; Joutsensaari, J.; Lyyränen, J.; Koivisto, J.; Ruusunen, J.; Järvelä, M.; Tuomi, T.; Hämeri, K.; Auvinen, A.; Jokiniemi, J.

    2012-01-01

    Nanoparticles are used in many applications because of their novel properties compared to bulk material. A growing number of employees are working with nanomaterials and their exposure to nanoparticles trough inhalation must be evaluated and monitored continuously. However, there is an ongoing debate in the scientific literature about what are the relevant parameters to measure to evaluate exposure to level. In this study, three types of nanoparticles (ammonium sulphate, synthesised TiO 2 agglomerates and aerosolised TiO 2 powder, modes in a range of 30–140 nm mobility size) were measured with commonly used aerosol measurement instruments: scanning and fast mobility particle sizers (SMPS, FMPS), electrical low pressure impactor (ELPI), condensation particle counter (CPC) together with nanoparticle surface area monitor (NSAM) to achieve information about the interrelations of the outputs of the instruments. In addition, the ease of use of these instruments was evaluated. Differences between the results of different instruments can mainly be attributed to the nature of test particles. For spherical ammonium sulphate nanoparticles, the data from the instruments were in good agreement while larger differences were observed for particles with more complex morphology, the TiO 2 agglomerates and powder. For instance, the FMPS showed a smaller particle size, a higher number concentration and a narrower size distribution compared with the SMPS for TiO 2 particles. Thus, the type of the nanoparticle was observed to influence the data obtained from these different instruments. Therefore, care and expertise are essential when interpreting results from aerosol measurement instruments to estimate nanoparticle concentrations and properties.

  7. Cervical length measurement: comparison of transabdominal and transvaginal approach

    DEFF Research Database (Denmark)

    Westerway, Sue C; Pedersen, Lars Henning; Hyett, Jon

    2015-01-01

    to external cervical os. Bland- Altman plots and Wilcoxon signed rank test were used to evaluate differences between TA and TV measurements. Results: The validity of the TA method depended on cervical length. Although the TA method underestimated cervical length by 2.0 mm on average (P ... plots showed an inverse trend with shorter cervixes. In women with a cervix test to detect cervical length

  8. Measurements of proton strength functions and comparisons with theory

    International Nuclear Information System (INIS)

    Arai, E.; Ozawa, Y.

    1986-01-01

    Using a high-resolution proton beam of the Tokyo Institute of Technology Van de Graaff, precise measurements of elastic and inelastic scattering cross sections have been performed in the past 15 years. By directly observing individual proton resonances, their spins, parities and proton decay widths were deduced. From these experiments we have evaluated (1) proton strength functions in terms of target mass number and of incident proton energy and (2) Coulomb matrix elements for split analogue resonances. (orig.)

  9. Comparison of safety measures with a multicriteria decision aiding technique

    International Nuclear Information System (INIS)

    Lombard, J.

    1985-01-01

    Attributes such as political, social and psychological factors have to be taken into account for the decision-making process. Multiattribute decision-aiding techniques are used to cope with this multidimensionality of the risk management process. A simple example will be given to illustrate how such method can be helpful for the selection of proper safety measures in a rational way. (orig./HP) [de

  10. Comparisons between different techniques for measuring mass segregation

    Science.gov (United States)

    Parker, Richard J.; Goodwin, Simon P.

    2015-06-01

    We examine the performance of four different methods which are used to measure mass segregation in star-forming regions: the radial variation of the mass function {M}_MF; the minimum spanning tree-based ΛMSR method; the local surface density ΣLDR method; and the ΩGSR technique, which isolates groups of stars and determines whether the most massive star in each group is more centrally concentrated than the average star. All four methods have been proposed in the literature as techniques for quantifying mass segregation, yet they routinely produce contradictory results as they do not all measure the same thing. We apply each method to synthetic star-forming regions to determine when and why they have shortcomings. When a star-forming region is smooth and centrally concentrated, all four methods correctly identify mass segregation when it is present. However, if the region is spatially substructured, the ΩGSR method fails because it arbitrarily defines groups in the hierarchical distribution, and usually discards positional information for many of the most massive stars in the region. We also show that the ΛMSR and ΣLDR methods can sometimes produce apparently contradictory results, because they use different definitions of mass segregation. We conclude that only ΛMSR measures mass segregation in the classical sense (without the need for defining the centre of the region), although ΣLDR does place limits on the amount of previous dynamical evolution in a star-forming region.

  11. Comparison of physical chewing measures to consumer typed Mouth Behavior.

    Science.gov (United States)

    Wilson, Arran; Jeltema, Melissa; Morgenstern, Marco P; Motoi, Lidia; Kim, Esther; Hedderley, Duncan

    2018-02-15

    The purpose of this study was to investigate the hypotheses that when presented with foods that could be chewed in different ways, (1) are participants jaw movements and chewing sequence measures correlated with Mouth Behavior (MB) group, as measured by the JBMB typing tool? (2) can MB group membership can be predicted from jaw movement and chewing sequence measures? One hundred subjects (69 female and 31 male, mean age 27 ± 7.7 years) were given four different foods (Mentos, Walkers, Cheetos Puffs, Twix) and video recordings of their jaw movements made. Twenty-nine parameters were calculated on each chewing sequence with 27 also calculated for the first half and second half of chewing sequence. Subjects were assigned to a MB group using the JBMB typing tool which gives four MB groups ("Chewers," "Crunchers," "Smooshers," and "Suckers"). The differences between individual chewing parameters and MB group were assessed with analysis of variance which showed only small differences in average chewing parameters between the MB groups. By using discriminant analysis, it was possible to partially discriminate between MB groups based on changes in their chewing parameters between foods with different material properties and stages of the chewing. A 19-variable model correctly predicted 68% of the subjects' membership of a MB group. This partially confirms our first hypothesis that when presented with foods that could be chewed in different ways participants will use a chewing sequence and jaw movements that correlate with their MB as measured by the JBMB typing tool. The way consumers chew their food has an impact on their texture perception of that food. While there is a wide range of chewing behaviors between consumers, they can be grouped into broad categories to better target both product design and product testing by sensory panel. In this study, consumers who were grouped on their texture preference (MB group) had jaw movements, when chewing a range of foods, which

  12. Magnetic relaxation in analytical, coordination and bioinorganic chemistry

    International Nuclear Information System (INIS)

    Mikhajlov, O.

    1982-01-01

    Nuclear magnetic relaxation is a special type of nuclear magnetic resonance in which the rate is measured of energy transfer between the excited nuclei and their molecular medium (spin-lattice relaxation) or the whole nuclear spin system (spin-spin relaxation). Nuclear magnetic relaxation relates to nuclei with a spin of 1/2, primarily H 1 1 , and is mainly measured in water solutions. It is suitable for (1) analytical chemistry because the relaxation time rapidly reduces in the presence of paramagnetic ions, (2) the study of complex compounds, (3) the study of biochemical reactions in the presence of different metal ions. It is also suitable for testing the composition of a flowing liquid. Its disadvantage is that it requires complex and expensive equipment. (Ha)

  13. A comparison of alternative methods for measuring cigarette prices.

    Science.gov (United States)

    Chaloupka, Frank J; Tauras, John A; Strasser, Julia H; Willis, Gordon; Gibson, James T; Hartman, Anne M

    2015-05-01

    Government agencies, public health organisations and tobacco control researchers rely on accurate estimates of cigarette prices for a variety of purposes. Since the 1950s, the Tax Burden on Tobacco (TBOT) has served as the most widely used source of this price data despite its limitations. This paper compares the prices and collection methods of the TBOT retail-based data and the 2003 and 2006/2007 waves of the population-based Tobacco Use Supplement to the Current Population Survey (TUS-CPS). From the TUS-CPS, we constructed multiple state-level measures of cigarette prices, including weighted average prices per pack (based on average prices for single-pack purchases and average prices for carton purchases) and compared these with the weighted average price data reported in the TBOT. We also constructed several measures of tax avoidance from the TUS-CPS self-reported data. For the 2003 wave, the average TUS-CPS price was 71 cents per pack less than the average TBOT price; for the 2006/2007 wave, the difference was 47 cents. TUS-CPS and TBOT prices were also significantly different at the state level. However, these differences varied widely by state due to tax avoidance opportunities, such as cross-border purchasing. The TUS-CPS can be used to construct valid measures of cigarette prices. Unlike the TBOT, the TUS-CPS captures the effect of price-reducing marketing strategies, as well as tax avoidance practices and non-traditional types of purchasing. Thus, self-reported data like TUS-CPS appear to have advantages over TBOT in estimating the 'real' price that smokers face. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Cellulase activities in biomass conversion: measurement methods and comparison.

    Science.gov (United States)

    Dashtban, Mehdi; Maki, Miranda; Leung, Kam Tin; Mao, Canquan; Qin, Wensheng

    2010-12-01

    Cellulose, the major constituent of all plant materials and the most abundant organic molecule on the Earth, is a linear biopolymer of glucose molecules, connected by β-1,4-glycosidic bonds. Enzymatic hydrolysis of cellulose requires mixtures of hydrolytic enzymes including endoglucanases, exoglucanases (cellobiohydrolases), and β-glucosidases acting in a synergistic manner. In biopolymer hydrolysis studies, enzyme assay is an indispensable part. The most commonly used assays for the individual enzymes as well as total cellulase activity measurements, including their advantages and limitations, are summarized in this review article. In addition, some novel approaches recently used for enzyme assays are summarized.

  15. Comparison of L-H transition measurements with physics models

    International Nuclear Information System (INIS)

    Carlstrom, T.N.; Burrell, K.H.; Groebner, R.J.; Leonard, A.W.; Osborne, T.H.; Thomas, D.M.

    1998-12-01

    A technique of fitting a modified hyperbolic tangent to the edge profiles has improved the localization of plasma edge parameters. Non-dimensional edge parameters are broadly consistent with several theories of the L-H transition that use edge gradients in their formulation of a critical threshold parameter. The ion ∇B drift direction has only a small effect on the edge plasma conditions measured near the plasma midplane but a large effect on the divertor plasma. The dramatic change of power threshold with the direction of the ion ∇B drift implies that phenomena in the divertor region may be critical for the L-H transition

  16. Comparison of Theory with Rotation Measurements in JET ICRH Plasmas

    International Nuclear Information System (INIS)

    R.V. Budny; C.S. Chang; C. Giroud; R.J. Goldston; D. McCune; J. Ongena; F.W. Perkins; R.B. White; K.-D. Zastrow; and contributors to the EFDA-JET work programme

    2001-01-01

    Plasma rotation appears to improve plasma performance by increasing the E x B flow shearing rate, thus decreasing radial correlations in the microturbulence. Also, plasma rotation can increase the stability to resistive MHD modes. In the Joint European Torus (JET), toroidal rotation rates omega (subscript ''tor'') with high Mach numbers are generally measured in NBI-heated plasmas (since the neutral beams aim in the co-plasma current direction). They are considerably lower with only ICRH (and Ohmic) heating, but still surprisingly large considering that ICRH appears to inject relatively small amounts of angular momentum. Either the applied torques are larger than naively expected, or the anomalous transport of angular momentum is smaller than expected. Since ICRH is one of the main candidates for heating next-step tokamaks, and for creating burning plasmas in future tokamak reactors, this paper attempts to understand ICRH-induced plasma rotation

  17. A comparison of the risk measures between VHTR and LWR

    International Nuclear Information System (INIS)

    Han, Seok-Jung; Yang, Joon-Eon; Lee, Won-Jea

    2007-01-01

    Because the safety characteristics of a very high temperature reactor (VHTR) are different to that of light water reactors (LWRs), it is necessary to develop an adequate probabilistic safety assessment (PSA) methodology in order to perform a risk assessment. The inherent safety features of the VHTR are (1) simplified safety functions (2) the absence of the large release of radioactive materials such as a severe accident in LWRs. The PSA methodology for LWRs cannot be directly applied in a VHTR PSA. This paper proposes a PSA methodology for a VHTR. The essential point of the proposed methodology is to define end states of accident sequences in order to establish the risk measures for a VHTR PSA. This paper compares them with that for LWRs to discuss the differences of them

  18. Exposure to traffic pollution: comparison between measurements and a model.

    Science.gov (United States)

    Alili, F; Momas, I; Callais, F; Le Moullec, Y; Sacre, C; Chiron, M; Flori, J P

    2001-01-01

    French researchers from the Building Scientific and Technical Center have produced a traffic-exposure index. To achieve this, they used an air pollution dispersion model that enabled them to calculate automobile pollutant concentrations in front of subjects' residences and places of work. Researchers used this model, which was tested at 27 Paris canyon street sites, and compared nitrogen oxides measurements obtained with passive samplers during a 6-wk period and calculations derived from the model. There was a highly significant correlation (r = .83) between the 2 series of values; their mean concentrations were not significantly different. The results suggested that the aforementioned model could be a useful epidemiological tool for the classification of city dwellers by present-or even cumulative exposure to automobile air pollution.

  19. Comparison of L-H transition measurements with physics models

    International Nuclear Information System (INIS)

    Carlstrom, T.N.; Burrell, K.H.; Carreras, B.A.

    1999-01-01

    Sawteeth and neutrals are found to have a significant influence on the H-mode power threshold scaling. The ion ∇B drift direction has only a small effect on the edge plasma conditions measured near the plasma midplane but a large effect on the divertor plasma. Since the power threshold changes dramatically with the direction of the ion ∇B drift, this implies that phenomena in the divertor region are critical for the L-H transition. Local conditions at the plasma edge are consistent with several theories of the L-H transition that use edge gradients in their formulation of a critical threshold parameter. However, scatter in the database is too large to distinguish between conditions that lead to an L-H transition and those that remain in L-mode. (author)

  20. Comparison of L-H transition measurements with physics models

    International Nuclear Information System (INIS)

    Carlstrom, T.N.; Burrell, K.H.; Groebner, R.J.

    2001-01-01

    Sawteeth and neutrals are found to have a significant influence on the H-mode power threshold scaling. The ion ∇B drift direction has only a small effect on the edge plasma conditions measured near the plasma midplane but a large effect on the divertor plasma. Since the power threshold changes dramatically with the direction of the ion ∇B drift, this implies that phenomena in the divertor region are critical for the L-H transition. Local conditions at the plasma edge are consistent with several theories of the L-H transition that use edge gradients in their formulation of a critical threshold parameter. However, scatter in the database is too large to distinguish between conditions that lead to an L-H transition and those that remain in L-mode. (author)

  1. Measurement and comparison of nursing faculty members' critical thinking skills.

    Science.gov (United States)

    Blondy, Laurie C

    2011-03-01

    Nursing faculty members strive to teach students to think critically. It has long been assumed that nursing faculty members are good at critical thinking because they are expected to teach these skills to students, but this assumption has not been well supported empirically. Faculty members question their ability to think critically and are unsure of their skills. The purpose of this study was to address this assumption by measuring nursing faculty members' critical thinking skills and compare the faculty mean score to that of a student norming group, and to the mean scores of other nursing faculty studies. Findings can be used to increase nursing faculty members' understanding of their critical thinking skills, prompt discussion about critical thinking skills, and to help faculty members address concerns and uncertainty about the concept of critical thinking. This study also helps establish an empirical basis for future research.

  2. A comparison of high-frequency cross-correlation measures

    Science.gov (United States)

    Precup, Ovidiu V.; Iori, Giulia

    2004-12-01

    On a high-frequency scale the time series are not homogeneous, therefore standard correlation measures cannot be directly applied to the raw data. There are two ways to deal with this problem. The time series can be homogenised through an interpolation method (An Introduction to High-Frequency Finance, Academic Press, NY, 2001) (linear or previous tick) and then the Pearson correlation statistic computed. Recently, methods that can handle raw non-synchronous time series have been developed (Int. J. Theor. Appl. Finance 6(1) (2003) 87; J. Empirical Finance 4 (1997) 259). This paper compares two traditional methods that use interpolation with an alternative method applied directly to the actual time series.

  3. A comparison of four measures of moral reasoning.

    Science.gov (United States)

    Wilmoth, G H; McFarland, S G

    1977-08-01

    Kohlberg's Moral Judgment Scale, Gilligan et al.'s Sexual Moral Judgment Scale, Maitland and Goldman's Objective Moral Judgment Scale, and Hogan's Maturity of Moral Judgment Scale, were examined for reliability and inter-scale relationships. All measures except the Objective Moral Judgment Scale had good reliabilities. The obtained relations between the Moral Judgment Scale and the Sexual Moral Judgment Scale replicated previous research. The Objective Moral Judgment Scale was not found to validly assess the Kohlberg stages. The Maturity of Moral Judgment Scale scores were strongly related to the subjects's classification on the Kohlberg stages, and the scale appears to offer a reliable, quickly scored, and valid index of mature thought, although the scale's continuous scores do not permit clear stage classification.

  4. Multi-instrument comparisons of D-region plasma measurements

    Directory of Open Access Journals (Sweden)

    M. Friedrich

    2013-01-01

    Full Text Available The ECOMA (Existence and Charge state Of Meteoric dust grains in the middle Atmosphere series of sounding rocket flights consisted of nine flights with almost identical payload design and flight characteristics. All flights carried a radio wave propagation experiment together with a variety of plasma probes. Three of these measured electron densities, two ion densities. The rockets were all launched from the Andøya Rocket Range, Norway, in four campaigns between 2006 and 2010. Emphasis is on the final three flights from 2010 where the payloads were equipped with four instruments capable of measuring plasma densities in situ, among them a novel probe flown for the first time in conjunction with a wave propagation experiment. Deviation factors of all probe data relative to the wave propagation results were derived and revealed that none of the probe data were close to the wave propagation results at all heights, but – more importantly – the instruments showed very different behaviour at different altitudes. The novel multi-needle Langmuir probe exhibits the best correlation to the wave propagation data, as there is minimal influence of the payload potential, but it is still subject to aerodynamics, especially at its location at the rear of the payload. For all other probe types, the deviation factor comes closer to unity with increasing plasma density. No systematic difference of the empirical deviation factor between day and night can be found. The large negative payload potential in the last three flights may be the cause for discrepancies between electron and ion probe data below 85 km.

  5. Comparison of three protocols for measuring the maximal respiratory pressures

    Directory of Open Access Journals (Sweden)

    Isabela Maria B. Sclauser Pessoa

    Full Text Available Introduction To avoid the selection of submaximal efforts during the assessment of maximal inspiratory and expiratory pressures (MIP and MEP, some reproducibility criteria have been suggested. Criteria that stand out are those proposed by the American Thoracic Society (ATS and European Respiratory Society (ERS and by the Brazilian Thoracic Association (BTA. However, no studies were found that compared these criteria or assessed the combination of both protocols. Objectives To assess the pressure values selected and the number of maneuvers required to achieve maximum performance using the reproducibility criteria proposed by the ATS/ERS, the BTA and the present study. Materials and method 113 healthy subjects (43.04 ± 16.94 years from both genders were assessed according to the criteria proposed by the ATS/ERS, BTA and the present study. Descriptive statistics were used for analysis, followed by ANOVA for repeated measures and post hoc LSD or by Friedman test and post hoc Wilcoxon, according to the data distribution. Results The criterion proposed by the present study resulted in a significantly higher number of maneuvers (MIP and MEP – median and 25%-75% interquartile range: 5[5-6], 4[3-5] and 3[3-4] for the present study criterion, BTA and ATS/ERS, respectively; p < 0.01 and higher pressure values (MIP – mean and 95% confidence interval: 103[91.43-103.72], 100[97.19-108.83] and 97.6[94.06-105.95]; MEP: median and 25%-75% interquartile range: 124.2[101.4-165.9], 123.3[95.4-153.8] and 118.4[95.5-152.7]; p < 0.05. Conclusion The proposed criterion resulted in the selection of pressure values closer to the individual’s maximal capacity. This new criterion should be considered in future studies concerning MIP and MEP measurements.

  6. Comparison of LOFT zero power physics testing measurement results with predicted values

    International Nuclear Information System (INIS)

    Rushton, B.L.; Howe, T.M.

    1978-01-01

    The results of zero power physics testing measurements in LOFT have been evaluated to assess the adequacy of the physics data used in the safety analyses performed for the LOFT FSAR and Technical Specifications. Comparisons of measured data with computed data were made for control rod worths, temperature coefficients, boron worths, and pressure coefficients. Measured boron concentrations at exact critical points were compared with predicted concentrations. Based on these comparisons, the reactivity parameter values used in the LOFT safety analyses were assessed for conservatism

  7. A comparison of irradiance responsivity and thermodynamic temperature measurement between PTB and NIM

    International Nuclear Information System (INIS)

    Lu, X.; Yuan, Z.; Anhalt, K.; Taubert, R. D.

    2013-01-01

    This paper describes a comparison between PTB and NIM in the field of absolute spectral-band radiometry and thermodynamic temperature measurement. For the comparison a NIM made interference filter radiometer with a centre wavelength of 633 nm was taken to PTB. The filter radiometer was calibrated at NIM and PTB with respect to spectral irradiance responsivity. For the integral value in the band-pass range an agreement of 0.1% was observed in both calibrations. In a next step, the 633 nm filter radiometer was used to measure the temperature of a high-temperature blackbody in comparison to an 800 nm filter radiometer of PTB in the temperature range between 1400 K and 2750 K. The thermodynamic temperature measured by the two filter radiometers agreed to within 0.2 K to 0.5 K with an estimated measurement uncertainty ranging between 0.1 K and 0.4 K (k=1)

  8. Interlaboratory comparison on high-temperature superconductor critical-current measurements

    International Nuclear Information System (INIS)

    Wiejaczka, J.A.; Goodrich, L.F.

    1997-01-01

    An extensive interlaboratory comparison was conducted on high temperature superconductor (HTS) critical-current measurements. This study was part of an international cooperative effort through the Versailles Project on Advanced Materials and Standards (VAMAS). The study involved six US laboratories that are recognized leaders in the field of HTS. This paper includes the complete results from this comparison of critical-current measurements on Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10-x (2223) tapes. The effects of sample characteristics, specimen mounting, measurement technique, and specimen damage were studied. The future development of a standard HTS measurement method is also discussed. Most of the evolution of this emerging technology has occurred in improvement of the performance of the conductors. The successful completion of this interlaboratory comparison is an important milestone in the evolution of HTS technology and marks a level of maturity that the technology has reached

  9. Calculation of the Flux in a Square Lattice Cell and a Comparison with Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Apelqvist, G [State Power Board, Stockholm (Sweden)

    1961-05-15

    A calculation has been made of the thermal neutron flux in a square lattice cell using methods devised by Galanin. The f and L lattice parameters have been expressed in measurable quantities and a comparison made between measured and calculated values.

  10. A comparison on radar range profiles between in-flight measurements and RCS-predictions

    NARCIS (Netherlands)

    Heiden, R. van der; Ewijk, L.J. van; Groen, F.C.A.

    1998-01-01

    The validation of Radar Cross Section (RCS) prediction techniques against real measurements is crucial to acquire confidence in predictions when measurements are nut available. In this paper we present the results of a comparison on one-dimensional signatures, i.e. radar range profiles. The profiles

  11. Comparison of various measures for assessing medication refill adherence using prescription data

    NARCIS (Netherlands)

    Vink, N. M.; Klungel, O. H.; Stolk, R. P.; Denig, P.

    Background Several measures using prescription data have been developed for estimating medication refill adherence. Few Studies have made direct comparisons, and little is known about the accuracy of these measures in patients oil a multiple-drug regimen. Purpose To compare different calculation

  12. Measurement and comparison of remotely derived leaf area index predictors

    Science.gov (United States)

    Jensen, Ryan Russell

    Environmental change occurs in response to both natural and anthropogenic causes. As the world's human population continues to increase, anthropogenic change will also increase. These changes affect the health and vigor of forests throughout the world, including those in north central Florida. Leaf Area Index (LAI), the amount of leaf area per unit ground area, is an important biophysical variable that is directly related to rates of atmospheric gas exchange, biomass partitioning, and productivity. While global and local models that map biophysical parameters are prevalent in the literature, landscape to regional scale models are less common. Therefore, the ability to map and monitor LAI over landscape to regional scale areas is essential for understanding medium scale biophysical properties and how these properties affect biogeochemical cycling, biomass accumulation, and primary productivity. This study develops and verifies several new models to estimate LAI using in situ field measurements throughout north central Florida, Landsat Thematic Mapper remotely sensed imagery, remotely derived vegetation indices, simple and multiple regression, and artificial neural networks (ANNs). This study concludes that while multiple band regression and regression with individual vegetation indices (Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index, Simple Ratio, and Greenness Vegetation Index) can estimate LAI, the most accurate way to estimate regional scale LAI is to train an ANN using in situ LAI data and remote sensing brightness values measured from six different portions of the electromagnetic spectrum. The new ANN method of estimating LAI is then applied to two forest ecology studies. The first study analyzes LAI in longleaf pine/turkey oak sandhills as a function of time since last burn. It concludes that in the absence of fire, sandhill LAI increases, and this may be useful for identifying where prescribed burns need to be done. The second study

  13. National comparison of {sup 131}I measurement among nuclear medicine clinics of eight countries

    Energy Technology Data Exchange (ETDEWEB)

    Olsovcova, Veronika, E-mail: volsovcova@cmi.c [Czech Metrology Institute, Radiova 1, Praha 10, 102 00 (Czech Republic); Iwahara, Akira [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes, Instituto de Radioprotecao e Dosimetria, Av. Salvador Allende, s/no. Recreio, Rio de Janeiro, CEP 22780-160 Brazil (Brazil); Oropesa, Pilar [Centro de Isotopos, Ave. Monumental y Carretera La Rada, Km 31/2, Guanabacoa, Ciudad Habana (Cuba); Joseph, Leena; Ravindra, Anuradha [Bhabha Atomic Research Centre, Radiation Safety Systems Division, Trombay, Mumbai-400 085 (India); Ghafoori, Mostafa [SSDL, Agricultural, Medical and Industrial Research School (AMIRS). Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of); Son, Hye-Kyung [Radiation Safety Division, National Institute of Food and Drug Safety Evaluation, Korea Food and Drug Administration, 194 Tongilro, Eunpyung-Gu, Seoul, 122-704 (Korea, Republic of); Sahagia, Maria [Horia Hulubei National Institute of R and D for Physics and Engineering, POB MG-6, 077125 Bucharest (Romania); Tastan, Selma [Ankara University Medical Faculty, Department of Nuclear Medicine, Cebeci 06100, Ankara (Turkey); Zimmerman, Brian [Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, P.O. Box 100, A-1400 Vienna (Austria); Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8462 (United States)

    2010-07-15

    A generally applicable protocol for organizing comparisons among nuclear medicine clinics created within the IAEA project CRP E2.10.05 was tested in Brazil, Cuba, Czech Republic, India, Iran, Republic of Korea, Romania and Turkey in 2007. Comparisons of measurement of {sup 131}I were organized by local pilot laboratories with different backgrounds and levels of experience in this field. The results and experiences gained were compared and analyzed. A majority of results in each national comparison were within 10% of the reference value.

  14. Comparison of measurement capability with 100 μmol/mol of carbon monoxide in nitrogen

    Science.gov (United States)

    Lee, Jeongsoon; Lee, JinBok; Lim, Jeongsik; Tarhan, Tanıl; Liu, Hsin-Wang; Aggarwal, Shankar G.

    2018-01-01

    Carbon monoxide (CO) in nitrogen was one of the first types of gas mixtures used in an international key comparison. The comparison dates back to 1998 (CCQMK1a) [1]. Since then, many National Metrology Institutes (NMIs) have developed calibration and measurement capabilities (CMCs) for these mixtures. Recently, NMIs in the APMP region have actively participated in international comparisons to provide domestic services. At the 2013 APMP meeting, several NMIs requested a CO comparison to establish CO/N2 certification for industrial applications, which was to be coordinated by KRISS. Consequently, this comparison provides an opportunity for APMP regional NMIs to develop CO/N2 CMC claims. The goal of this supplementary comparison is to support CMC claim for carbon monoxide in the N2 range of 50–2000 μmol/mol. An extended range may be supported as described in the GAWG strategy for comparisons and CMC claims. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Advances in supercell calculation methods and comparison with measurements

    Energy Technology Data Exchange (ETDEWEB)

    Arsenault, B [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Baril, R; Hotte, G [Hydro-Quebec, Central Nucleaire Gentilly, Montreal, Quebec (Canada)

    1996-07-01

    In the last few years, modelling techniques have been developed in new supercell computer codes. These techniques have been used to model the CANDU reactivity devices. One technique is based on one- and two-dimensional transport calculations with the WIMS-AECL lattice code followed by super homogenization and three-dimensional flux calculations in a modified version of the MULTICELL code. The second technique is based on two- and three-dimensional transport calculations in DRAGON. The code calculates the lattice properties by solving the transport equation in a two-dimensional geometry followed by supercell calculations in three dimensions. These two calculation schemes have been used to calculate the incremental macroscopic properties of CANDU reactivity devices. The supercell size has also been modified to define incremental properties over a larger region. The results show improved agreement between the reactivity worth of zone controllers and adjusters. However, at the same time the agreement between measured and simulated flux distributions deteriorated somewhat. (author)

  16. Comparison between thermoluminiscence dosimetry and transmission ionization chamber measurements

    International Nuclear Information System (INIS)

    Hernando, I.; Torres, R.

    2001-01-01

    Radiofrequency catheter ablation is an effective option to treat life-threatening arrhythmias. Among the risks of this type of procedure are the high radiation doses to patients. The major concern for monitoring of doses has been related to skin damage. Skin dose can be measured directly with thermoluminescence dosimeters (TLDs) or can be determined from the dose-area product (DAP). In this work these two different methods are discussed. The radiation doses have been estimated in more than 20 patients with the two types of monitoring. In order to find the location of the maximum dose from the procedure with TLDs, dosimeter arrays can be placed on the patient. Unfortunately TLDs do not allow immediate feedback to the fluoroscopist. They require a fair amount of handling, calibrating, processing and annealing. On the other hand, the DAP provides immediate feedback of the cumulative dose. To obtain the skin dose from DAP the area of the radiation field on the skin must be determined, and it is necessary to correct the result by a factor that includes the variation of geometry during the procedure. Nevertheless, these and other factors can lead to significant errors in dose estimation. (author)

  17. Comparison of magnetic field meters used for Elf exposure measurement

    International Nuclear Information System (INIS)

    Magne, I.; Azoulay, A.; Lambrozo, J.; Souques, M.

    2006-01-01

    Objective The question of the biological effects of E.L.F. electromagnetic fields (50/60 Hz) has lead to many experimental and epidemiological works, in occupational exposure and in residential exposure. One of the main difficulties is to integrate the maximum of information about the environmental exposures during the everyday life without limitation to the exposure of the home. The objective of this study is to analyse experimentally the metrology associated with human exposure to 50 Hz magnetic field, in the optic of a study of the French population exposure. Method 4 meters were tested: the E.M.D.E.X. II, currently used in epidemiological studies, the E.M.D.E.X. L.I.T.E., which is more recent, the H.T.300, an Italian meter, and the F.D.3, which is made by Combinova A calibration was performed with an Helmoltz coil. The immunity of these meters to GSM signal was also tested. The influence of the sample rate was evaluated. Results and conclusion The meter chosen for performing the measurements of the exposure study will be selected in function of the following criteria: - easiness of use - precision - low sample rate - memory size and reliability of data stocking - immunity to GSM perturbations. (authors)

  18. Accuracy of surgical wound drainage measurements: an analysis and comparison.

    Science.gov (United States)

    Yue, Brian; Nizzero, Danielle; Zhang, Chunxiao; van Zyl, Natasha; Ting, Jeannette

    2015-05-01

    Surgical drain tube readings can influence the clinical management of the post-operative patient. The accuracy of these readings has not been documented in the current literature and this experimental study aims to address this paucity. Aliquots (10, 25, 40 and 90 mL) of black tea solution prepared to mimic haemoserous fluid were injected into UnoVac, RedoVac and Jackson-Pratt drain tubes. Nursing and medical staff from a tertiary hospital were asked to estimate drain volumes by direct observation; analysis of variance was performed on the results and significance level was set at 0.05. Doctors and nurses are equally accurate in estimating drain tube volumes. Jackson-Pratt systems were found to be the most accurate for intermediate volumes of 25 and 40 mL. For extreme of volumes (both high and low), all drainage systems were inaccurate. This study suggests that for intermediate volumes (25 and 40 mL), Jackson-Pratt is the drainage system of choice. The accuracy of volume measurement is diminished at the extremes of drain volumes; emptying of drainage systems is recommended to avoid overfilling of drainage systems. © 2014 Royal Australasian College of Surgeons.

  19. Aerial Measuring System (AMS)/ Israel Atomic Energy Commission (IAEC) Joint Comparison Study

    International Nuclear Information System (INIS)

    Halevy, I.; Dadon, S.; Sheinfeld, M.; Broide, A.; Rofe, S.; Yaar, I.; Wasiolek, P.

    2014-01-01

    In support of the U.S. Department of Energy (DOE) International Emergency Management and Cooperation (IEMC/NA-46) Program, the comparison of the U.S. and Israeli Aerial Measuring Systems (AMS) study was proposed and accepted. The study, organized by the DOE/National Nuclear Security Administration (NNSA) Remote Sensing Laboratory (RSL), involved the DOE/NNSA Aerial Measuring System Project based at the RSL and operated under a contractor agreement by National Security Technologies, LLC (NSTec), and the Israel Atomic Energy Commission (IAEC) Aerial Measuring System. The operational comparison was conducted at RSL-Nellis in Las Vegas, Nevada, during week of June 24–27, 2013. The Israeli system, Air RAM 2000 (figure 1, down), was shipped to RSL-Nellis and mounted together with the DOE Spectral Advanced Radiological Computer System, Model A (SPARCS-A, figure 1 up) on U.S. DOE Bell-412 helicopter for a series of aerial comparison measurements at local test ranges, including the Desert Rock Airport and Area 3 at the Nevada National Security Site (NNSS). A four-person Israeli team from the IAEC, Nuclear Research Center – Negev (NRCN) supported the activity. The main objective of this joint comparison was use the DOE/RSL Bell-412 helicopter aerial platform, perform the comparison study of measuring techniques and radiation acquisition systems utilized for emergency response by IEAC and NNSA AMS

  20. Comparison of two techniques for natural dose measurements

    International Nuclear Information System (INIS)

    Ekdal, E.; Ege, A.; Goekce, M.; Karali, T.; Derin, Z.

    2006-01-01

    In the study of luminescence dating, age of an archaeological sample is calculated by the ratio of total exposed dose to annual dose resulted from the environmental radioactivity. Determination of the annual dose level of an archaeological area is one of the most important parameter in calculating the archaeological age of the sample using luminescence techniques. Therefore, the knowledge of the concentrations of the natural radionuclides is important since naturally occurring radioactivity provides major contribution to the annual dose. The natural radioactivity is originated from natural radionuclides consisting mainly of 2 38U, 2 32Th and 4 0K isotopes together with their daughters in soils. In this study, annual dose level of the archaeological site was determined with two different methods: an indirect method that is determining the concentrations of the naturally occurring radioactive elements using gamma spectroscopy and a direct method that uses thermoluminescence dosimeters. Soil samples were collected from the Yesilova Hoeyuek archaeological site located in Izmir City at the Aegean Region of Turkey. The concentrations of the natural radioactivity ( 2 38U, 2 32Th and 4 0K) in soil samples were determined using 3 x 3 N aI (Tl) γ-ray spectrometry system. In direct method, Al 2 O 3 :C thermoluminescence dosimeters (TLD's) were used. These dosimeters were chosen because of their sensitivity and usability in dating studies. They were buried in same archaeological site, 30 cm depth from the soil surface for 30 days period. The luminescence intensity of Al 2 O 3 :C dosimeters was measured by a TLD reader and the dose level was calculated by the luminescence signals emitted by the dosimeters. The results obtained from natural radionuclides and Al 2 O 3 :C thermoluminescence dosimeters were compared and the source of the differences between two methods were discussed

  1. CT hepatic perfusion measurement: Comparison of three analytic methods

    International Nuclear Information System (INIS)

    Kanda, Tomonori; Yoshikawa, Takeshi; Ohno, Yoshiharu; Kanata, Naoki; Koyama, Hisanobu; Takenaka, Daisuke; Sugimura, Kazuro

    2012-01-01

    Objectives: To compare the efficacy of three analytic methods, maximum slope (MS), dual-input single-compartment model (CM) and deconvolution (DC), for CT measurements of hepatic perfusion and assess the effects of extra-hepatic systemic factors. Materials and methods: Eighty-eight patients who were suspected of having metastatic liver tumors underwent hepatic CT perfusion. The scans were performed at the hepatic hilum 7–77 s after administration of contrast material. Hepatic arterial and portal perfusions (HAP and HPP, ml/min/100 ml) and arterial perfusion fraction (APF, %) were calculated with the three methods, followed by correlation assessment. Partial correlation analysis was used to assess the effects on hepatic perfusion values by various factors such as age, sex, risk of cardiovascular diseases, arrival time of contrast material at abdominal aorta, transit time from abdominal aorta to hepatic parenchyma, and liver dysfunction. Results: Mean HAP of MS was significantly higher than DC. HPP of CM was significantly higher than MS and CM, and HPP of MS was significantly higher than DC. There was no significant difference in APF. HAP and APF showed significant and moderate correlations among the methods. HPP showed significant and moderate correlations between CM and DC, and poor correlation between MS and CM or DC. All methods showed weak correlations between HAP or APF and age or sex. Finally, MS showed weak correlations between HAP or HPP and arrival time or cardiovascular risks. Conclusions: Hepatic perfusion values arrived at with the three methods are not interchangeable. CM and DC are less susceptible to extra-hepatic systemic factors

  2. Asymmetries in Chickens from Lines Selected and Relaxed for High or Low Antibody Titers to Sheep Red Blood Cells

    Directory of Open Access Journals (Sweden)

    Yunjie Tu

    2015-03-01

    Full Text Available Wattle length, width, and area were measured to classify bilateral asymmetries in four lines of chickens. The lines were the S26 generation of White Leghorns selected for high (HAS or low (LAS response to sheep red blood cells and sublines in which selection had been relaxed for three generations (high antibody relaxed [HAR] and low antibody relaxed [LAR]. Antibody titers (AB were greater for HAS than for HAR with both greater than for LAS and LAR which while different for males did not differ for females. The low antibody lines were heavier and reached sexual maturity at younger age than the high antibody lines. In general, wattle length, width, and area were greater in the low than high antibody lines. In 24 comparisons for bilaterality 18 exhibited fluctuating asymmetry and 6 exhibited directional asymmetry with 5 of the 6 being for wattle length. There was not a clear pattern for changes in degree of asymmetry when selection was relaxed for 3 generations. For females, the relative asymmetry (RA of wattle area was larger (p≤0.05 for HAR than for LAR and not different from the selected lines and relaxed lines. There were no differences among lines for RA of wattle length and width of females and wattle length, width, and area of males.

  3. Study of vortex dynamics with local magnetic relaxation measurements in the superconducting compound Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}; Etude de la dynamique des vortex par des mesures locales de relaxation magnetique dans le compose supraconducteur Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Berry, St

    2000-07-01

    This experimental study of the magnetic field-temperature phase diagram and of the vortex dynamics in high- T{sub c} superconductors focuses on Bismuth-based cuprates: Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}. In type-II superconductors, mixed state characterized by the presence of vortices (quanta of magnetic flux) is divided by a transition line determined by two features of magnetization loops. For T > 40 K, magnetization loops vs applied field show a step evidence of a first order transition. From 20 to 40 K, a second peak replacing the step correspond to an abrupt increase of irreversibility interpreted as a bulk current. We want to understand the nature of the second peak (thermodynamic or nonequilibrium property) and separate phenomena contributing to irreversibility (flux pinning, geometrical or surface effects). Magnetic measurement techniques are nondestructive and have a resolution of few microns. Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals are optimized by localizing defectives regions with a magneto-optic technique for flux imaging and elimination of these regions with a wire saw. Local magnetization loops and relaxation measurements performed with a microscopic Hall probe array allow to distinguish irreversibility sources. The shape of induction profiles indicates which current dominate between surface current and bulk pinning induced current. Two crossover with time and a direct observation of two phases coexistence in induction profiles enlighten phenomena in play. The measured electric field-current density characteristics lead to barrier energy U(j) controlling thermally activated flux motion. Three relations (U(j) (surface, bulk low and high field) explain second peak. (author)

  4. Cross-correlated relaxation rates between protein backbone H–X dipolar interactions

    International Nuclear Information System (INIS)

    Vögeli, Beat

    2017-01-01

    The relaxation interference between dipole–dipole interactions of two separate spin pairs carries structural and dynamics information. In particular, when compared to individual dynamic behavior of those spin pairs, such cross-correlated relaxation (CCR) rates report on the correlation between the spin pairs. We have recently mapped out correlated motion along the backbone of the protein GB3, using CCR rates among and between consecutive H N –N and H α –C α dipole–dipole interactions. Here, we provide a detailed account of the measurement of the four types of CCR rates. All rates were obtained from at least two different pulse sequences, of which the yet unpublished ones are presented. Detailed comparisons between the different methods and corrections for unwanted pathways demonstrate that the averaged CCR rates are highly accurate and precise with errors of 1.5–3% of the entire value ranges.

  5. Cross-correlated relaxation rates between protein backbone H–X dipolar interactions

    Energy Technology Data Exchange (ETDEWEB)

    Vögeli, Beat, E-mail: beat.vogeli@ucdenver.edu [University of Colorado Denver, Department of Biochemistry and Molecular Genetics (United States)

    2017-03-15

    The relaxation interference between dipole–dipole interactions of two separate spin pairs carries structural and dynamics information. In particular, when compared to individual dynamic behavior of those spin pairs, such cross-correlated relaxation (CCR) rates report on the correlation between the spin pairs. We have recently mapped out correlated motion along the backbone of the protein GB3, using CCR rates among and between consecutive H{sup N}–N and H{sup α}–C{sup α} dipole–dipole interactions. Here, we provide a detailed account of the measurement of the four types of CCR rates. All rates were obtained from at least two different pulse sequences, of which the yet unpublished ones are presented. Detailed comparisons between the different methods and corrections for unwanted pathways demonstrate that the averaged CCR rates are highly accurate and precise with errors of 1.5–3% of the entire value ranges.

  6. Electron spin-lattice relaxation in fractals

    International Nuclear Information System (INIS)

    Shrivastava, K.N.

    1986-08-01

    We have developed the theory of the spin-fracton interaction for paramagnetic ions in fractal structures. The interaction is exponentially damped by the self-similarity length of the fractal and by the range dimensionality d Φ . The relaxation time of the spin due to the absorption and emission of the fracton has been calculated for a general dimensionality called the Raman dimensionality d R , which for the fractons differs from the Hausdorff (fractal) dimensionality, D, as well as from the Euclidean dimensionality, d. The exponent of the energy level separation in the relaxation rate varies with d R d Φ /D. We have calculated the spin relaxation rate due to a new type of Raman process in which one fracton is absorbed to affect a spin transition from one electronic level to another and later another fracton is emitted along with a spin transition such that the difference in the energies of the two fractons is equal to the electronic energy level separation. The temperature and the dimensionality dependence of such a process has been found in several approximations. In one of the approximations where the van Vleck relaxation rate for a spin in a crystal is known to vary with temperature as T 9 , our calculated variation for fractals turns out to be T 6.6 , whereas the experimental value for Fe 3+ in frozen solutions of myoglobin azide is T 6.3 . Since we used d R =4/3 and the fracton range dimensionality d Φ =D/1.8, we expect to measure the dimensionalities of the problem by measuring the temperature dependence of the relaxation times. We have also calculated the shift of the paramagnetic resonance transition for a spin in a fractal for general dimensionalities. (author)

  7. Relaxation of coupled nuclear spin systems

    International Nuclear Information System (INIS)

    Koenigsberger, E.

    1985-05-01

    The subject of the present work is the relaxation behaviour of scalarly coupled spin-1/2 systems. In the theoretical part the semiclassical Redfield equations are used. Dipolar (D), Chemical Shift Anisotropy (CSA) and Random Field (RF) interactions are considered as relaxation mechanisms. Cross correlations of dipolar interactions of different nuclei pairs and those between the D and the CSA mechanisms are important. The model of anisotropic molecular rotational relaxation and the extreme narrowing approximation are used to obtain the spectral density functions. The longitudinal relaxation data are analyzed into normal modes following Werbelow and Grant. The time evolution of normal modes is derived for the AX system with D-CSA cross terms. In the experimental part the hypothesis of dimerization in the cinnamic acid and the methyl cinnamate - AMX systems with DD cross terms - is corroborated by T 1 -time measurements and a calculation of the diffusion constants. In pentachlorobenzene - an AX system - taking into account of D-CSA cross terms enables the complete determination of movements anosotropy and the determination of the sign of the indirect coupling constant 1 Jsub(CH). (G.Q.)

  8. Stretched Exponential relaxation in pure Se glass

    Science.gov (United States)

    Dash, S.; Ravindren, S.; Boolchand, P.

    A universal feature of glasses is the stretched exponential relaxation, f (t) = exp[ - t / τ ] β . The model of diffusion of excitations to randomly distributed traps in a glass by Phillips1 yields the stretched exponent β = d[d +2] where d, the effective dimensionality. We have measured the enthalpy of relaxation ΔHnr (tw) at Tg of Se glass in modulated DSC experiments as glasses age at 300K and find β = 0.43(2) for tw in the 0 relaxation is a narrowing of the glass transition width from 7.1°C to 1.4°C, and the ΔHnr term increasing from 0.21 cal/gm to 0.92 cal/gm. In bulk GexSe100-x glasses as x increases to 20%, the length of the polymeric Sen chains between the Ge-crosslinks decreases to n = 2. and the striking relaxation effects nearly vanish. J.C. Phillips, Rep.Prog.Phys. 59 , 1133 (1996). Supported by NSF Grant DMR 08-53957.

  9. Ultra-fast relaxation kinetics in semiconductors

    International Nuclear Information System (INIS)

    Luzzi, R.

    1983-01-01

    It is presented a brief description of relaxation processes in highly excited semiconductor plasmas (HESP). Comparison with experimental data obtained by means of ultra-fast laser light spectroscopy (UFLS) is made. Some aspects of response funtion theory in systems far-from-equilibrium are reviewed in Section II. In Section III we present some comments on the question of nonequilibrium thermodynamics relevant to the problem to be considered. In last section we present a brief summary of the different aspects of the subject. (author) [pt

  10. Ultra-fast relaxation kinetics in semiconductors

    International Nuclear Information System (INIS)

    Luzzi, R.

    1983-01-01

    It is presented a brief description of relaxation processes in highly excited semiconductor plasmas (HESP). Comparison with experimental data obtained by means of ultra-fast laser light spectroscopy (UFLS) is made. Some aspects of response function theory in systems far-from-equilibrium are reviewed in Section II. In Section III some comments on the question of nonequilibrium thermodynamics relevant to the problem to be considered are presented. In last Section a brief summary of the different aspects of the subject is also presented. (Author) [pt

  11. Comparison of methods and instruments for 222Rn/220Rn progeny measurement

    International Nuclear Information System (INIS)

    Liu Yanyang; Shang Bing; Wu Yunyun; Zhou Qingzhi

    2012-01-01

    In this paper, comparisons were made among three methods of measurement (grab measurement, continuous measurement and integrating measurement) and also measurement of different instruments for a radon/thoron mixed chamber. Taking the optimized five-segment method as a comparison criterion, for the equilibrium-equivalent concentration of 222 Rn, measured results of Balm and 24 h integrating detectors are 31% and 29% higher than the criterion, the results of Wl x, however, is 20% lower; and for 220 Rn progeny, the results of Fiji-142, Kf-602D, BWLM and 24 h integrating detector are 86%, 18%, 28% and 36% higher than the criterion respectively, except that of WLx, which is 5% lower. For the differences shown, further research is needed. (authors)

  12. An efficient binomial model-based measure for sequence comparison and its application.

    Science.gov (United States)

    Liu, Xiaoqing; Dai, Qi; Li, Lihua; He, Zerong

    2011-04-01

    Sequence comparison is one of the major tasks in bioinformatics, which could serve as evidence of structural and functional conservation, as well as of evolutionary relations. There are several similarity/dissimilarity measures for sequence comparison, but challenges remains. This paper presented a binomial model-based measure to analyze biological sequences. With help of a random indicator, the occurrence of a word at any position of sequence can be regarded as a random Bernoulli variable, and the distribution of a sum of the word occurrence is well known to be a binomial one. By using a recursive formula, we computed the binomial probability of the word count and proposed a binomial model-based measure based on the relative entropy. The proposed measure was tested by extensive experiments including classification of HEV genotypes and phylogenetic analysis, and further compared with alignment-based and alignment-free measures. The results demonstrate that the proposed measure based on binomial model is more efficient.

  13. Measurements of air kerma index in computed tomography: a comparison among methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, T. C.; Mourao, A. P.; Da Silva, T. A., E-mail: alonso@cdtn.br [Universidade Federal de Minas Gerais, Programa de Ciencia y Tecnicas Nucleares, Av. Pres. Antonio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

  14. Comparison of activity measurements of the 67Ga and 123I at Brazilian nuclear medicine services

    International Nuclear Information System (INIS)

    Santos, J.A. dos; Silva, M.A.L. da; Lopes, R.T.; Iwahara, A.; Oliveira, A.E. de; Tauhata, L.

    2003-01-01

    Since 1998, the National Laboratory for Ionizing Radiations (LNMRI), of Institute for Radioprotection and Dosimetry, belonging to the Brazilian Commission for Nuclear Energy (IRD/CNEN), is conducting a comparison program for the measurements of radiopharmaceutical activities applied to to patients at the nuclear medicine sector, viewing to assessment the quality of that measurements. This work presents the results of three comparison rounds using the 67 Ga and 123 I, establishing the metrological tracking of the calibrators used by the participants. The results were analysed under the the viewpoint of the conformal with the regulatory authority and show that those comparisons are necessary to improve the quality of radiopharmaceutical measurement activities, identify failures on the equipment and technical procedures used by the nuclear medicine services all over the country

  15. Measurements of air kerma index in computed tomography: a comparison among methodologies

    International Nuclear Information System (INIS)

    Alonso, T. C.; Mourao, A. P.; Da Silva, T. A.

    2016-10-01

    Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

  16. Structural Technology Evaluation and Analysis Program (STEAP) Delivery Order 0042: Development of the Equivalent Overload Model, Demonstration of the Failure of Superposition, and Relaxation/Redistribution Measurement

    Science.gov (United States)

    2011-09-01

    life benefits of the cold-worked process. A simple empirically -derived scale factor would accomplish the objectives 2 Approved for public release...Correlation of Retro-dictions to Measured Fatigue Lives, Naturally Occurring Cracks resK .001402.0 inca == 69 Approved for public release; distribution...allow significant variations in the cold work level from 3 to 5% for a nominal 4% cold worked hole). The direct use of empirically -derived scale

  17. Irradiation creep, stress relaxation and a mechanical equation of state

    International Nuclear Information System (INIS)

    Foster, J.P.

    1976-01-01

    Irradiation creep and stress relaxation data are available from the United Kingdom for 20 percent CW M316, 20 percent CW FV 548 and FHT PE16 using pure torsion in the absence of swelling at 300 0 C. Irradiation creep models were used to calculate the relaxation and permanent deflection of the stress relaxation tests. Two relationships between irradiation creep and stress relaxation were assessed by comparing the measured and calculated stress relaxation and permanent deflection. The results show that for M316 and FV548, the stress relaxation and deflection may be calculated using irradiation creep models when the stress rate term arising from the irradiation creep model is set equal to zero. In the case of PE16, the inability to calculate the stress relaxation and permanent deflection from the irradiation creep data was attributed to differences in creep behavior arising from lot-to-lot variations in alloying elements and impurity content. A modification of the FV548 and PE16 irradiation creep coefficients was necessary in order to calculate the stress relaxation and deflection. The modifications in FV548 and PE16 irradiation creep properties reduces the large variation in the transient or incubation parameter predicted by irradiation creep tests for M316, FV548 and PE16

  18. Effectiveness of relaxation techniques before diagnostic screening of cancer patients

    Directory of Open Access Journals (Sweden)

    Montserrat Aiger

    2016-07-01

    Full Text Available Psychophysiological arousal was observed in cancer patients during the application of relaxation techniques prior to a diagnostic scan (PET-CT. The aim of the study is twofold: firstly, it is sought to establish whether such techniques can minimize patient arousal before diagnostic screening begins, and secondly to measure which of them are most effective. The dependent variable is electrodermal activity, recording the attentional level and emotional response, and the independent variable comprises the relaxation techniques used, namely Jacobson, breathing and visualization. The 39 patients were split into experimental groups to whom the relaxation techniques (Jacobson, breathing exercises, and visualization were applied before they went for the PET-CT. An activity-module procedure was applied to track electrodermal activity during the relaxation sessions, consisting of instructions, timeout; wait, task; relaxation and end of the recording session. The control group received no relaxation techniques before the PET-CT. Session-end results show that patients who perform relaxation techniques achieve greater attentional focus using Jacobson's technique (M = .212 and enhanced emotional containment using visualization (M = .206. It is concluded that relaxation techniques minimize the state of activation during the waiting period before a diagnostic scan.

  19. Comparison between theoretical values foreseen and measured during the commissioning of second cycle of Angra-1

    International Nuclear Information System (INIS)

    Angelkorte, G.; Dias, A.M.; Sakai, M.

    1988-01-01

    The purpose of this paper is to present the most important results of the comparison of the data measured during the start-up tests for the second cycle of Angra 1 with the calculated values for this cycle. This short comparison considered the following quantities: Critical boron concentration, Control rod worths, Isothermal temperature coefficient, Reaction rates of the incore detector system. The calculated results showed good agreement with the measured ones remaining within the acceptation criteria limits, confirming the fuel management calculations for the second cycle, namely that for the reload scheme obtained, the core is capable of operating at nominal power safety and without restrictions. (author) [pt

  20. Relaxed states with plasma flow

    International Nuclear Information System (INIS)

    Avinash, K.; Taylor, J.B.

    1991-01-01

    In the theory of relaxation, a turbulent plasma reaches a state of minimum energy subject to constant magnetic helicity. In this state the plasma velocity is zero. Attempts have been made by introducing a number of different constraints, to obtain relaxed states with plasma flow. It is shown that these alternative constraints depend on two self-helicities, one for ions, and one for electrons. However, whereas there are strong arguments for the effective invariance of the original magnetic-helicity, these arguments do not apply to the self-helicities. Consequently the existence of relaxed states with flow remains in doubt. (author)

  1. An interlaboratory comparison programme on radio frequency electromagnetic field measurements: the second round of the scheme

    International Nuclear Information System (INIS)

    Nicolopoulou, E.P.; Ztoupis, I.N.; Gonos, I.F.; Stathopulos, I.A.; Karabetsos, E.

    2015-01-01

    The second round of an interlaboratory comparison scheme on radio frequency electromagnetic field measurements has been conducted in order to evaluate the overall performance of laboratories that perform measurements in the vicinity of mobile phone base stations and broadcast antenna facilities. The participants recorded the electric field strength produced by two high frequency signal generators inside an anechoic chamber in three measurement scenarios with the antennas transmitting each time different signals at the FM, VHF, UHF and GSM frequency bands. In each measurement scenario, the participants also used their measurements in order to calculate the relative exposure ratios. The results were evaluated in each test level calculating performance statistics (z-scores and E n numbers). Subsequently, possible sources of errors for each participating laboratory were discussed, and the overall evaluation of their performances was determined by using an aggregated performance statistic. A comparison between the two rounds proves the necessity of the scheme. (authors)

  2. Comparison of measured and computed loss to parasitic modes in cylindrical cavities with beam ports

    International Nuclear Information System (INIS)

    Wilson, P.B.; Styles, J.B.; Bane, K.L.F.

    1977-03-01

    Good agreement was obtained between computed values and results from a bench measurement technique for the total loss to parasitic modes in several cylindrical cavities with beam ports. The measurement of loss as a function of time within the current pulse also gives results which are in good agreement with computed functions, especially considering the fact that there are questionable points concerning both the theory and the measurement technique. Within measurement errors, there is also agreement in a few cases where a comparison is possible between a bench measurement result and the heating produced directly in a component by the SPEAR beam

  3. Unique electron polarimeter analyzing power comparison and precision spin-based energy measurement

    International Nuclear Information System (INIS)

    Joseph Grames; Charles Sinclair; Joseph Mitchell; Eugene Chudakov; Howard Fenker; Arne Freyberger; Douglas Higinbotham; Poelker, B.; Michael Steigerwald; Michael Tiefenback; Christian Cavata; Stephanie Escoffier; Frederic Marie; Thierry Pussieux; Pascal Vernin; Samuel Danagoulian; Kahanawita Dharmawardane; Renee Fatemi; Kyungseon Joo; Markus Zeier; Viktor Gorbenko; Rakhsha Nasseripour; Brian Raue; Riad Suleiman; Benedikt Zihlmann

    2004-01-01

    Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Moller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beamline of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the relative analyzing powers of the five polarimeters. This is the first time a precise comparison of the analyzing powers of Compton, Moller, and Mott scattering polarimeters has been made. Statistically significant disagreements among the values of the beam polarization calculated from the asymmetry measurements made with each polarimeter reveal either errors in the values of the analyzing power, or failure to correctly include all systematic effects. The measurements reported here represent a first step toward understanding the systematic effects of these electron polarimeters. Such studies are necessary to realize high absolute accuracy (ca. 1%) electron polarization measurements, as required for some parity violation measurements planned at Jefferson Laboratory. Finally, a comparison of the value of the spin orientation exiting the injector that provides maximum longitudinal polarization in each experimental hall leads to an independent and very precise (better than 10-4) absolute measurement of the final electron beam energy

  4. Conservatively treated knee injury is associated with knee cartilage matrix degeneration measured with MRI-based T2 relaxation times. Data from the osteoarthritis initiative

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Felix C. [University of California San Francisco, Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Technical University of Munich, Department of Radiology, Munich (Germany); Neumann, Jan; Heilmeier, Ursula; Joseph, Gabby B.; Link, Thomas M. [University of California San Francisco, Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Nevitt, Michael C.; McCulloch, Charles E. [University of California San Francisco, Department of Epidemiology and Biostatistics, San Francisco, CA (United States)

    2018-01-15

    To investigate the association of cartilage degeneration with previous knee injuries not undergoing surgery, determined by morphologic and quantitative 3-T magnetic resonance imaging (MRI). We performed a nested cross-sectional study of right knee MRIs from participants in the Osteoarthritis Initiative (OAI) aged 45-79 with baseline Kellgren-Lawrence score of 0-2. Cases were 142 right knees of patients with self-reported history of injury limiting the ability to walk for at least 2 days. Controls were 426 right knees without history of injury, frequency-matched to cases on age, BMI, gender, KL scores and race (1:3 ratio). Cases and controls were compared using covariate-adjusted linear regression analysis, with the outcomes of region-specific T2 mean, laminar analysis and heterogeneity measured by texture analysis to investigate early cartilage matrix abnormalities and the Whole-Organ Magnetic Resonance Imaging Score (WORMS) to investigate morphologic knee lesions. Compared to control subjects, we found significantly higher mean T2 values in the injury [lateral tibia (28.10 ms vs. 29.11 ms, p = 0.001), medial tibia (29.70 ms vs. 30.40 ms, p = 0.014) and global knee cartilage (32.73 ms vs. 33.29 ms, p = 0.005)]. Injury subjects also had more heterogeneous cartilage as measured by GLCM texture contrast, variance and entropy (p < 0.05 in 14 out of 18 texture parameters). WORMS gradings were not significantly different between the two groups (p > 0.05). A history of knee injury not treated surgically is associated with higher and more heterogeneous T2 values, but not with morphologic knee abnormalities. Our findings suggest that significant, conservatively treated knee injuries are associated with permanent cartilage matrix abnormalities. (orig.)

  5. Conservatively treated knee injury is associated with knee cartilage matrix degeneration measured with MRI-based T2 relaxation times. Data from the osteoarthritis initiative

    International Nuclear Information System (INIS)

    Hofmann, Felix C.; Neumann, Jan; Heilmeier, Ursula; Joseph, Gabby B.; Link, Thomas M.; Nevitt, Michael C.; McCulloch, Charles E.

    2018-01-01

    To investigate the association of cartilage degeneration with previous knee injuries not undergoing surgery, determined by morphologic and quantitative 3-T magnetic resonance imaging (MRI). We performed a nested cross-sectional study of right knee MRIs from participants in the Osteoarthritis Initiative (OAI) aged 45-79 with baseline Kellgren-Lawrence score of 0-2. Cases were 142 right knees of patients with self-reported history of injury limiting the ability to walk for at least 2 days. Controls were 426 right knees without history of injury, frequency-matched to cases on age, BMI, gender, KL scores and race (1:3 ratio). Cases and controls were compared using covariate-adjusted linear regression analysis, with the outcomes of region-specific T2 mean, laminar analysis and heterogeneity measured by texture analysis to investigate early cartilage matrix abnormalities and the Whole-Organ Magnetic Resonance Imaging Score (WORMS) to investigate morphologic knee lesions. Compared to control subjects, we found significantly higher mean T2 values in the injury [lateral tibia (28.10 ms vs. 29.11 ms, p = 0.001), medial tibia (29.70 ms vs. 30.40 ms, p = 0.014) and global knee cartilage (32.73 ms vs. 33.29 ms, p = 0.005)]. Injury subjects also had more heterogeneous cartilage as measured by GLCM texture contrast, variance and entropy (p < 0.05 in 14 out of 18 texture parameters). WORMS gradings were not significantly different between the two groups (p > 0.05). A history of knee injury not treated surgically is associated with higher and more heterogeneous T2 values, but not with morphologic knee abnormalities. Our findings suggest that significant, conservatively treated knee injuries are associated with permanent cartilage matrix abnormalities. (orig.)

  6. Three-dimensional hindfoot alignment measurements based on biplanar radiographs: comparison with standard radiographic measurements

    International Nuclear Information System (INIS)

    Sutter, Reto; Pfirrmann, Christian W.A.; Buck, Florian M.; Espinosa, Norman

    2013-01-01

    To establish a hindfoot alignment measurement technique based on low-dose biplanar radiographs and compare with hindfoot alignment measurements on long axial view radiographs, which is the current reference standard. Long axial view radiographs and low-dose biplanar radiographs of a phantom consisting of a human foot skeleton embedded in acrylic glass (phantom A) and a plastic model of a human foot in three different hindfoot positions (phantoms B1-B3) were imaged in different foot positions (20 internal to 20 external rotation). Two independent readers measured hindfoot alignment on long axial view radiographs and performed 3D hindfoot alignment measurements based on biplanar radiographs on two different occasions. Time for three-dimensional (3D) measurements was determined. Intraclass correlation coefficients (ICC) were calculated. Hindfoot alignment measurements on long axial view radiographs were characterized by a large positional variation, with a range of 14 /13 valgus to 22 /27 varus (reader 1/2 for phantom A), whereas the range of 3D hindfoot alignment measurements was 7.3 /6.0 to 9.0 /10.5 varus (reader 1/2 for phantom A), with a mean and standard deviation of 8.1 ± 0.6/8.7 ± 1.4 respectively. Interobserver agreement was high (ICC = 0.926 for phantom A, and ICC = 0.886 for phantoms B1-B3), and agreement between different readouts was high (ICC = 0.895-0.995 for reader 1, and ICC = 0.987-0.994 for reader 2) for 3D measurements. Mean duration of 3D measurements was 84 ± 15/113 ± 15 s for reader 1/2. Three-dimensional hindfoot alignment measurements based on biplanar radiographs were independent of foot positioning during image acquisition and reader independent. In this phantom study, the 3D measurements were substantially more precise than the standard radiographic measurements. (orig.)

  7. 磁共振对比剂弛豫率研究及其在临床中的应用%Comparison of MRI contrast agents gadopentetate dimeglumine, gadodiamide and gadovist: their relaxation rates and effects on imaging

    Institute of Scientific and Technical Information of China (English)

    王晓; 刘伟

    2016-01-01

    Objective To evaluate the relaxation rates and imaging effects of three MRI contrast agents gadopentetate dimeglumine(0.5 mol/L),gadodiamine and gadovist(1.0 mol/L) in the nervous system.Methods Relaxation rate differences between the three contrast agents were assessed using the GE Signa HDx 3.0 T MR scanner and phantom solutions of different albumin concentrations.Twenty leukemia patients whose initial scans had been conducted with the injection of a standard dose(0.5 mol/L)of gadopentetate dimeglumine as the contrast agent were recalled to have a follow-up scan for signs of brain infections with the same imaging protocols,except that a high concentration(1.0 mol/L)gadovist was used this time as the contrast agent.CNR and SNR in the ROI were measured for quantitative analysis.Results Changes in dosage of the three contrast agents produced no difference in intensity of the image signal for each phantom solution of a specific albumin concentration(5.0 g/L:P=0.35,6.5g/L:P =0.27,8.0 g/L:P=0.23).Two sets of scans of the leukemia patients showed that high concentration(1.0 mol/L)gadovist generated higher SNR and CNR in the ROI of the white matter,gray matter and vasculature than standard concentration(0.5 mol/L) gadopentetate dimeglumine(P< 0.05).Conclusions A half dose of high concentration(1.0 mol/L) gadovist generates better imaging enhancement than standard concentration(0.5 mol/L)gadopentetate dimegluminethe.Gadopentetate dimeglumine,gadodiamide and gadovist have no significant difference in relaxation rate.%目的 评价高浓度对比剂1.0 mol/L钆布醇和标准浓度0.5 mol/L钆喷酸葡胺在神经系统中的临床应用.方法 采用GE公司Signa HDx 3.0 T成像设备,对制作的白蛋白溶液模体成像,评估三种对比剂弛豫率.复查脑组织有无感染的20位白血病患者,初次检查使用的对比剂为标准浓度0.5 mol/L钆喷酸葡胺,复查使用的对比剂为高浓度对比剂1.0 mol/L钆布醇.所有检查使用相同的成像

  8. Performance audits and laboratory comparisons for SCOS97-NARSTO measurements of speciated volatile organic compounds

    Science.gov (United States)

    Fujita, Eric M.; Harshfield, Gregory; Sheetz, Laurence

    Performance audits and laboratory comparisons were conducted as part of the quality assurance program for the 1997 Southern California Ozone Study (SCOS97-NARSTO) to document potential measurement biases among laboratories measuring speciated nonmethane hydrocarbons (NMHC), carbonyl compounds, halogenated compounds, and biogenic hydrocarbons. The results show that measurements of volatile organic compounds (VOC) made during SCOS97-NARSTO are generally consistent with specified data quality objectives. The hydrocarbon comparison involved nine laboratories and consisted of two sets of collocated ambient samples. The coefficients of variation among laboratories for the sum of the 55 PAM target compounds and total NMHC ranged from ±5 to 15 percent for ambient samples from Los Angeles and Azusa. Abundant hydrocarbons are consistently identified by all laboratories, but discrepancies occur for olefins greater than C 4 and for hydrocarbons greater than C 8. Laboratory comparisons for halogenated compounds and biogenic hydrocarbons consisted of both concurrent ambient sampling by different laboratories and round-robin analysis of ambient samples. The coefficients of variation among participating laboratories were about 10-20 percent. Performance audits were conducted for measurement of carbonyl compounds involving sampling from a standard mixture of carbonyl compounds. The values reported by most of the laboratories were within 10-20 percent of those of the reference laboratory. Results of field measurement comparisons showed larger variations among the laboratories ranging from 20 to 40 percent for C 1-C 3 carbonyl compounds. The greater variations observed in the field measurement comparison may reflect potential sampling artifacts, which the performance audits did not address.

  9. Low field NMR surface relaxivity studies of chalk and argillaceous sandstones

    DEFF Research Database (Denmark)

    Katika, Konstantina; Fordsmand, Henrik; Fabricius, Ida Lykke

    2017-01-01

    the accuracy of predictions of petrophysical properties of various rocks with the use of NMR spectrometry. We perform laboratory transverse relaxation (T2) measurements on water saturated Gorm field chalk, Stevns Klint chalk, Solsort field greensand and Berea sandstone. These rocks are of particular interest...... field chalk and Solsort field greensand have higher ρ at higher Larmor frequency. By contrast, ρ of the purely calcitic Stevns chalk and quartzitic Berea sandstone proved not to be affected by the changes in frequency. T2 distributions at temperatures ranging from 10 °C to 60 °C provided comparison...

  10. Relaxed states of tokamak plasmas

    International Nuclear Information System (INIS)

    Kucinski, M.Y.; Okano, V.

    1993-01-01

    The relaxed states of tokamak plasmas are studied. It is assumed that the plasma relaxes to a quasi-steady state which is characterized by a minimum entropy production rate, compatible with a number of prescribed conditions and pressure balance. A poloidal current arises naturally due to the anisotropic resistivity. The minimum entropy production theory is applied, assuming the pressure equilibrium as fundamental constraint on the final state. (L.C.J.A.)

  11. Negative magnetic relaxation in superconductors

    Directory of Open Access Journals (Sweden)

    Krasnoperov E.P.

    2013-01-01

    Full Text Available It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.

  12. Relaxation effects in ferrous complexes

    International Nuclear Information System (INIS)

    Nicolini, C.; Mathieu, J.P.; Chappert, J.

    1976-01-01

    The slow relaxation mechanism of the Fe 2+ ion in the tri-fluorinated TF(acac) and hexafluorinated HF(acac) complexes of Fe(II) acetylacetonate was investigated. The 300K and 77K Moessbauer spectra for TF(acac) consist in a slightly asymmetric quadrupole doublet. On the contrary, at 4.2K the higher energy line is strongly widened; that is typical of a slowing down in the electron relaxation frequency [fr

  13. Milrinone relaxes pulmonary veins in guinea pigs and humans.

    Directory of Open Access Journals (Sweden)

    Annette D Rieg

    Full Text Available INTRODUCTION: The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH. However, its action on pulmonary veins (PVs is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs and humans. MATERIAL AND METHODS: Precision-cut lung slices (PCLS were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL. RESULTS: In the IPL (GP, milrinone (10 µM lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP, milrinone relaxed naïve and pre-constricted PVs (120% and this relaxation was attenuated by inhibition of protein kinase G (KT 5823, adenyl cyclase (SQ 22536 and protein kinase A (KT 5720, but not by inhibition of NO-synthesis (L-NAME. In addition, milrinone-induced relaxation was dependent on the activation of K ATP-, BK Ca (2+- and Kv-channels. Human PVs also relaxed to milrinone (121%, however only if pre-constricted. DISCUSSION: Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on K ATP-, BK Ca (2+- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

  14. Milrinone relaxes pulmonary veins in guinea pigs and humans.

    Science.gov (United States)

    Rieg, Annette D; Suleiman, Said; Perez-Bouza, Alberto; Braunschweig, Till; Spillner, Jan W; Schröder, Thomas; Verjans, Eva; Schälte, Gereon; Rossaint, Rolf; Uhlig, Stefan; Martin, Christian

    2014-01-01

    The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH). However, its action on pulmonary veins (PVs) is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs) and humans. Precision-cut lung slices (PCLS) were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL). In the IPL (GP), milrinone (10 µM) lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP), milrinone relaxed naïve and pre-constricted PVs (120%) and this relaxation was attenuated by inhibition of protein kinase G (KT 5823), adenyl cyclase (SQ 22536) and protein kinase A (KT 5720), but not by inhibition of NO-synthesis (L-NAME). In addition, milrinone-induced relaxation was dependent on the activation of K ATP-, BK Ca (2+)- and Kv-channels. Human PVs also relaxed to milrinone (121%), however only if pre-constricted. Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on K ATP-, BK Ca (2+)- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

  15. Some results of Krsko NPP core calculations and comparison with measurements

    International Nuclear Information System (INIS)

    Trkov, A.; Zefran, B.; Kromar, M.; Ravnik, M.; Slavic, S.

    1996-01-01

    Current status of the CORD-2 package is described. Results of the predictions of some important reactor core parameters are presented for the 12 th operation cycle of the Krsko NPP. Comparison with measurements is made to illustrate that the accuracy of the calculations is acceptable. Some comments are made on the enhancements, which are currently being implemented on the package. (author)

  16. Intellectual Estimates of Hearing-Impaired Children: A Comparison of Three Measures

    Science.gov (United States)

    Ritter, David R.

    1976-01-01

    The Arthur Adaptation of the Leiter International Performance Scale, Raven's Coloured Progressive Matrices, and Wechsler Intelligence Scale for Children-Performance Section were administered to 31 children with mild to moderate hearing impairments. A comparison of test results indicated moderate convergent validity among the measures. (Author)

  17. CRIQ : An innovative measure using comparison awareness to avoid self-presentation tactics

    NARCIS (Netherlands)

    de Jong, Nicole; van Leeuwen, Rob G.J.; Hoekstra, Hans A.; van der Zee, Karen

    2014-01-01

    The article presents a new measure for career role identification, the Career Role Identification Questionnaire (CRIQ). In constructing the CRIQ, we used the Comparison Awareness Inducing Technique (CAIT), a new and innovative method to reduce the effects of self-presentation tactics. The results

  18. CRIQ : An innovative measure using comparison awareness to avoid self-presentation tactics

    NARCIS (Netherlands)

    De Jong, Nicole; van Leeuwen, Rob G.J.; Hoekstra, Hans A.; van der Zee, Karen I.

    The article presents a new measure for career role identification, the Career Role Identification Questionnaire (CRIQ). In constructing the CRIQ, we used the Comparison Awareness Inducing Technique (CAIT), a new and innovative method to reduce the effects of self-presentation tactics.The results

  19. Quality of Life Assessment for Physical Activity and Health Promotion: Further Psychometrics and Comparison of Measures

    Science.gov (United States)

    Gill, Diane L.; Reifsteck, Erin J.; Adams, Melanie M.; Shang, Ya-Ting

    2015-01-01

    Despite the clear relationship between physical activity and quality of life, few sound, relevant quality of life measures exist. Gill and colleagues developed a 32-item quality of life survey, and provided initial psychometric evidence. This study further examined that quality of life survey in comparison with the widely used short form (SF-36)…

  20. A Comparison of MMPI--2 measures of Psychopathic Deviance in a Forensic Setting

    Science.gov (United States)

    Sellbom, Martin; Ben-Porath, Yossef S.; Stafford, Kathleen P.

    2007-01-01

    We examined the convergent and discriminant validity of the Minnesota Multiphasic Personality Inventory--2 (MMPI--2) measures of psychopathy, including the Clinical Scale 4, Restructured Clinical Scale 4 (RC4), Content Scale Antisocial Practices (ASP), and Personality Psychopathology Five Scale Disconstraint (DISC). Comparisons of the empirical…

  1. International comparison of radon measurement using solid state nuclear track detectors

    International Nuclear Information System (INIS)

    Hu Dan; Yang Weigen; Song Jianfeng

    2011-01-01

    It introduces the radon measurements international comparison using solid state track detectors among Zhejiang Environmental Radiation Monitoring Center (RMTC), Japan Chemical Analysis Center (JCAC) and National Institute for Radiological Protection of China CDC (NIRP). The results of the international comparison show that: Compared to the reference values, the measurements' relative deviations of detectors from 3 labs were 2%∼22%, which were exposed in radon chambers with different radon concentration, while the measurements' relative deviations were 0.5%∼13% when exposed in the environment. The measurement's relative deviations of RMTC were 5%∼3% in radon chambers and 0.5%∼9% in the environment, the results met requirements of the relative standards both at home and abroad. (authors)

  2. On summary measure analysis of linear trend repeated measures data: performance comparison with two competing methods.

    Science.gov (United States)

    Vossoughi, Mehrdad; Ayatollahi, S M T; Towhidi, Mina; Ketabchi, Farzaneh

    2012-03-22

    The summary measure approach (SMA) is sometimes the only applicable tool for the analysis of repeated measurements in medical research, especially when the number of measurements is relatively large. This study aimed to describe techniques based on summary measures for the analysis of linear trend repeated measures data and then to compare performances of SMA, linear mixed model (LMM), and unstructured multivariate approach (UMA). Practical guidelines based on the least squares regression slope and mean of response over time for each subject were provided to test time, group, and interaction effects. Through Monte Carlo simulation studies, the efficacy of SMA vs. LMM and traditional UMA, under different types of covariance structures, was illustrated. All the methods were also employed to analyze two real data examples. Based on the simulation and example results, it was found that the SMA completely dominated the traditional UMA and performed convincingly close to the best-fitting LMM in testing all the effects. However, the LMM was not often robust and led to non-sensible results when the covariance structure for errors was misspecified. The results emphasized discarding the UMA which often yielded extremely conservative inferences as to such data. It was shown that summary measure is a simple, safe and powerful approach in which the loss of efficiency compared to the best-fitting LMM was generally negligible. The SMA is recommended as the first choice to reliably analyze the linear trend data with a moderate to large number of measurements and/or small to moderate sample sizes.

  3. A heteroscedastic measurement error model for method comparison data with replicate measurements.

    Science.gov (United States)

    Nawarathna, Lakshika S; Choudhary, Pankaj K

    2015-03-30

    Measurement error models offer a flexible framework for modeling data collected in studies comparing methods of quantitative measurement. These models generally make two simplifying assumptions: (i) the measurements are homoscedastic, and (ii) the unobservable true values of the methods are linearly related. One or both of these assumptions may be violated in practice. In particular, error variabilities of the methods may depend on the magnitude of measurement, or the true values may be nonlinearly related. Data with these features call for a heteroscedastic measurement error model that allows nonlinear relationships in the true values. We present such a model for the case when the measurements are replicated, discuss its fitting, and explain how to evaluate similarity of measurement methods and agreement between them, which are two common goals of data analysis, under this model. Model fitting involves dealing with lack of a closed form for the likelihood function. We consider estimation methods that approximate either the likelihood or the model to yield approximate maximum likelihood estimates. The fitting methods are evaluated in a simulation study. The proposed methodology is used to analyze a cholesterol dataset. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Blood pressure measurement in obese patients: comparison between upper arm and forearm measurements.

    Science.gov (United States)

    Pierin, Angela M G; Alavarce, Débora C; Gusmão, Josiane L; Halpern, Alfredo; Mion, Décio

    2004-06-01

    It is well known that blood pressure measurement with a standard 12-13 cm wide cuff is erroneous for large arms. To compare arm blood pressure measurements with an appropriate cuff and forearm blood pressure measurements (BPM) with a standard cuff, and both measurements by the Photopletismography (Finapres) method. One hundred and twenty-nine obese patients were studied (body mass index=40+/-7 kg/m2). The patients had three arm BPM taken by an automatic oscillometric device using an appropriate cuff and three forearm BPM with a standard cuff in the sitting position after a five-minute rest. Data were analysed by the analysis of variance. The correction values were obtained by the linear regression test. Systolic and diastolic arm BPM with an appropriate cuff were significantly lower (pforearm BPM with a standard cuff. The measurements obtained by Finapres were significantly lower (pforearm systolic and diastolic blood pressures and upper arm diastolic blood pressure. The equation to correct BPM in forearm in obese patients with arm circumference between 32-44 cm was: systolic BPM=33.2+/-0.68 x systolic forearm BPM, and diastolic BPM=25.2+0.59 x forearm diastolic BPM. This study showed that forearm blood pressure measurement overestimates the values of arm blood pressure measurement. In addition, it is possible to correct forearm BPM with an equation.

  5. Relaxing a large cosmological constant

    International Nuclear Information System (INIS)

    Bauer, Florian; Sola, Joan; Stefancic, Hrvoje

    2009-01-01

    The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy (DE) problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter ρ m is presently so close to the CC density ρ Λ . However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of ρ Λ at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this Letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could be able to solve the big CC problem without fine-tuning and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the ΛCDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.

  6. Parameterization of NMR relaxation curves in terms of logarithmic moments of the relaxation time distribution.

    Science.gov (United States)

    Petrov, Oleg V; Stapf, Siegfried

    2017-06-01

    This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Parameterization of NMR relaxation curves in terms of logarithmic moments of the relaxation time distribution

    Science.gov (United States)

    Petrov, Oleg V.; Stapf, Siegfried

    2017-06-01

    This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution.

  8. How best to measure implementation of school health curricula: a comparison of three measures.

    Science.gov (United States)

    Resnicow, K; Davis, M; Smith, M; Lazarus-Yaroch, A; Baranowski, T; Baranowski, J; Doyle, C; Wang, D T

    1998-06-01

    The impact of school health education programs is often attenuated by inadequate teacher implementation. Using data from a school-based nutrition education program delivered in a sample of fifth graders, this study examines the discriminant and predictive validity of three measures of curriculum implementation: class-room observation of fidelity, and two measures of completeness, teacher self-report questionnaire and post-implementation interview. A fourth measure, obtained during teacher observations, that assessed student and teacher interaction and student receptivity to the curriculum (labeled Rapport) was also obtained. Predictive validity was determined by examining the association of implementation measures with three study outcomes; health knowledge, asking behaviors related to fruit and vegetables, and fruit and vegetable intake, assessed by 7-day diary. Of the 37 teachers observed, 21 were observed for two sessions and 16 were observed once. Implementation measures were moderately correlated, an indication of discriminant validity. Predictive validity analyses indicated that the observed fidelity, Rapport and interview measures were significantly correlated with post-test student knowledge. The association between health knowledge and observed fidelity (based on dual observation only), Rapport and interview measures remained significant after adjustment for pre-test knowledge values. None of the implementation variables were significantly associated with student fruit and vegetable intake or asking behaviors controlling for pre-test values. These results indicate that the teacher self-report questionnaire was not a valid measure of implementation completeness in this study. Post-implementation completeness interviews and dual observations of fidelity and Rapport appear to be more valid, and largely independent methods of implementation assessment.

  9. Relaxation peak near 200 K in NiTi alloy

    Science.gov (United States)

    Zhu, J. S.; Schaller, R.; Benoit, W.

    1989-10-01

    Internal friction (IF), frequency ( f), electrical resistance ( R) and zero point movement of the torsion pendulum (ɛ) have been measured in near equi-atomic NiTi alloy in order to clarify the mechanism for the relaxation peak near 200 K. The height of the relaxation peak decreases successively with thermal cycling and settles down to a lower stable value in running 15 cycles. However, the electrical resistance of the sample shows a variation in contrast with the internal friction. Both of them will return to the initial state after a single annealing at 773 K for 1 h. The probable mechanism of this relaxation peak was discussed.

  10. COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for 60Co γ radiation

    International Nuclear Information System (INIS)

    Buermann, L.; Oborin, A.V.; Dobrovosky, J.; Milevsky, V.S.; Walwyn Salas, G.; Lapenas, A.

    2009-01-01

    Results are presented of the COOMET key comparison of the national measurement standards of air kerma for 60 Co γ radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. (authors)

  11. Proton NMR relaxation in hydrous melts

    International Nuclear Information System (INIS)

    Braunstein, J.; Bacarella, A.L.; Benjamin, B.M.; Brown, L.L.; Girard, C.

    1976-01-01

    Pulse and continuous wave NMR measurements are reported for protons in hydrous melts of calcium nitrate at temperatures between -4 and 120 0 C. Although measured in different temperature ranges, spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation times appear to be nearly equal to each other and proportional to the self-diffusion coefficients of solute metal cations such as Cd 2+ . At temperatures near 50 0 C, mean Arrhenius coefficients Δ H/sub T 1 / (kcal/mol) are 7.9, 7.3, and 4.8, respectively, for melts containing 2.8, 4.0, and 8.0 moles of water per mole of calcium nitrate, compared to 4.6 kcal/mol for pure water. Temperature dependence of T 1 and T 2 in Ca(NO 3 ) 2 -2.8 H 2 O between -4 and 120 0 C are non-Arrhenius and can be represented by a Fulcher-type equation with a ''zero mobility temperature'' (T 0 ) of 225 0 K, close to the value of T 0 for solute diffusion, electrical conductance and viscosity. Resolution of the relaxation rates into correlation times for intramolecular (rotational) and intermolecular (translational) diffusional motion is discussed in terms of the Bloembergen-Purcell-Pound and more recent models for dipolar relaxation

  12. Effective temperature in relaxation of Coulomb glasses.

    Science.gov (United States)

    Somoza, A M; Ortuño, M; Caravaca, M; Pollak, M

    2008-08-01

    We study relaxation in two-dimensional Coulomb glasses up to macroscopic times. We use a kinetic Monte Carlo algorithm especially designed to escape efficiently from deep valleys around metastable states. We find that, during the relaxation process, the site occupancy follows a Fermi-Dirac distribution with an effective temperature much higher than the real temperature T. Long electron-hole excitations are characterized by T(eff), while short ones are thermalized at T. We argue that the density of states at the Fermi level is proportional to T(eff) and is a good thermometer to measure it. T(eff) decreases extremely slowly, roughly as the inverse of the logarithm of time, and it should affect hopping conductance in many experimental circumstances.

  13. Computer Code for Interpreting 13C NMR Relaxation Measurements with Specific Models of Molecular Motion: The Rigid Isotropic and Symmetric Top Rotor Models and the Flexible Symmetric Top Rotor Model

    Science.gov (United States)

    2017-01-01

    top rotor superimposes an effective correlation time, τe, onto a symmetric top rotor to account for internal motion. 2. THEORY The purpose...specifically describe how simple 13C relaxation theory is used to describe quantitatively simple molecular 3 motions. More-detailed accounts ...of nuclear magnetic relaxation can be found in a number of basic textbooks (i.e., Farrar and Becker, 1971; Fukushima and Roeder, 1981; Harris, 1986

  14. Comparison measurements of the official individual dosimetry systems in the Federal Republic of Germany

    International Nuclear Information System (INIS)

    Boehm, J.

    1988-01-01

    At present, about 220,000 radiation workers are subject to individual monitoring of external radiation in the Federal Republic of Germany in accordance with the X-Ray Ordinance and the Radiation Protection Ordinance and the Radiation Protection Ordinance. Each radiation worker must wear at least one individual dosemeter provided by one of the five officially authorized dosemeter services. Requirements for these dosemeter services with respect to technical equipment and personnel are published in the form of a national directive. The five dosemeter services must participate in the comparison measurements for photon radiation with the official dosemeters issued by them. The comparison measurements are organized at least once a year by the Physicalisch-Technische Bundesanstalt (PTB) in agreement with the Federal Minister of Economics. Film dosemeters evaluated with a filter analysis procedure are most frequently used (96.% of all evaluations in 1984) to monitor the whole body exposure to photon radiation. Glass dosemeters play a minor role (0.5%). They are issued by only two officially authorized dosemeter services and are approved for measurements of photons with energies above 45 keV. According to the national directive, thermoluminescence dosemeters may be used only for partial body dosimetry of photon and beta radiation (2.8%). Nuclear track emulsion films are distributed to measure neutrons of energies above 0.5 MeV. A thermoluminescence albedo dosemeter for the measurement of less energetic neutrons is being introduced. The dosimetry systems involved in the comparison measurements and the operational radiation protection monitoring system of the Federal Republic of Germany are described elsewhere. The objective of this work is to describe the performance of the comparison measurements and to give some results obtained from 1979 to 1984

  15. Ber analysis of the box relaxation for BPSK signal recovery

    KAUST Repository

    Thrampoulidis, Christos; Abbasi, Ehsan; Xu, Weiyu; Hassibi, Babak

    2016-01-01

    We study the problem of recovering an n-dimensional BPSK signal from m linear noise-corrupted measurements using the box relaxation method which relaxes the discrete set {±1}n to the convex set [-1,1]n to obtain a convex optimization algorithm followed by hard thresholding. When the noise and measurement matrix have iid standard normal entries, we obtain an exact expression for the bit-wise probability of error Pe in the limit of n and m growing and m/n fixed. At high SNR our result shows that the Pe of box relaxation is within 3dB of the matched filter bound (MFB) for square systems, and that it approaches the (MFB) as m grows large compared to n. Our results also indicate that as m, n → ∞, for any fixed set of size k, the error events of the corresponding k bits in the box relaxation method are independent.

  16. Ber analysis of the box relaxation for BPSK signal recovery

    KAUST Repository

    Thrampoulidis, Christos

    2016-06-24

    We study the problem of recovering an n-dimensional BPSK signal from m linear noise-corrupted measurements using the box relaxation method which relaxes the discrete set {±1}n to the convex set [-1,1]n to obtain a convex optimization algorithm followed by hard thresholding. When the noise and measurement matrix have iid standard normal entries, we obtain an exact expression for the bit-wise probability of error Pe in the limit of n and m growing and m/n fixed. At high SNR our result shows that the Pe of box relaxation is within 3dB of the matched filter bound (MFB) for square systems, and that it approaches the (MFB) as m grows large compared to n. Our results also indicate that as m, n → ∞, for any fixed set of size k, the error events of the corresponding k bits in the box relaxation method are independent.

  17. Theoretical model of intravascular paramagnetic tracers effect on tissue relaxation

    DEFF Research Database (Denmark)

    Kjølby, Birgitte Fuglsang; Østergaard, Leif; Kiselev, Valerij G

    2006-01-01

    The concentration of MRI tracers cannot be measured directly by MRI and is commonly evaluated indirectly using their relaxation effect. This study develops a comprehensive theoretical model to describe the transverse relaxation in perfused tissue caused by intravascular tracers. The model takes...... into account a number of individual compartments. The signal dephasing is simulated in a semianalytical way by embedding Monte Carlo simulations in the framework of analytical theory. This approach yields a tool for fast, realistic simulation of the change in the transverse relaxation. The results indicate...... with bulk blood. The enhancement of relaxation in tissue is due to the contrast in magnetic susceptibility between blood vessels and parenchyma induced by the presence of paramagnetic tracer. Beyond the perfusion measurements, the results can be applied to quantitation of functional MRI and to vessel size...

  18. CIRP Interlaboratory Comparison of Coordinate Measuring Machines using an Optomechanical Hole Plate

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Hansen, Hans Nørgaard; Morace, Renata Erica

    An interlaboratory comparison on mechanical and optical coordinate measuring machines (CMMs) has been organized by the Centre for Geometrical Metrology (CGM), Department of Manufacturing Engineering and Management (IPL), Technical University of Denmark (DTU) and carried out within Collège...... plate [1], designed and manufactured by DTU. A measurement procedure was sent to each participant together with the hole plate to be measured. The procedure consists mainly of two parts [2]: 1) four reversal measurements, by which the systematic errors in the measuring plane (X,Y) on the CMM...... are eliminated, except the positioning errors; 2) transfer of traceability by comparator measurement using a length reference chosen by the participant, by which the positioning errors are eliminated. Furthermore, a third optional part could be carried out by the participant, using a different measurement...

  19. International comparison of activity measurements of a solution of 75Se

    Science.gov (United States)

    Ratel, Guy

    2002-04-01

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

  20. Comparison Study of Three Common Technologies for Freezing-Thawing Measurement

    Directory of Open Access Journals (Sweden)

    Xinbao Yu

    2010-01-01

    Full Text Available This paper describes a comparison study on three different technologies (i.e., thermocouple, electrical resistivity probe and Time Domain Reflectometry (TDR that are commonly used for frost measurement. Specially, the paper developed an analyses procedure to estimate the freezing-thawing status based on the dielectric properties of freezing soil. Experiments were conducted where the data of temperature, electrical resistivity, and dielectric constant were simultaneously monitored during the freezing/thawing process. The comparison uncovered the advantages and limitations of these technologies for frost measurement. The experimental results indicated that TDR measured soil dielectric constant clearly indicates the different stages of the freezing/thawing process. Analyses method was developed to determine not only the onset of freezing or thawing, but also the extent of their development. This is a major advantage of TDR over other technologies.

  1. Comparison of the inversion algorithms applied to the ozone vertical profile retrieval from SCIAMACHY limb measurements

    Directory of Open Access Journals (Sweden)

    A. Rozanov

    2007-09-01

    Full Text Available This paper is devoted to an intercomparison of ozone vertical profiles retrieved from the measurements of scattered solar radiation performed by the SCIAMACHY instrument in the limb viewing geometry. Three different inversion algorithms including the prototype of the operational Level 1 to 2 processor to be operated by the European Space Agency are considered. Unlike usual validation studies, this comparison removes the uncertainties arising when comparing measurements made by different instruments probing slightly different air masses and focuses on the uncertainties specific to the modeling-retrieval problem only. The intercomparison was performed for 5 selected orbits of SCIAMACHY showing a good overall agreement of the results in the middle stratosphere, whereas considerable discrepancies were identified in the lower stratosphere and upper troposphere altitude region. Additionally, comparisons with ground-based lidar measurements are shown for selected profiles demonstrating an overall correctness of the retrievals.

  2. Nuclear spin-lattice relaxation in carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Panich, A.M., E-mail: pan@bgu.ac.i [Department of Physics, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Sergeev, N.A. [Institute of Physics, University of Szczecin, 70-451 Szczecin (Poland)

    2010-04-15

    Interpretation of nuclear spin-lattice relaxation data in the carbon nanostructures is usually based on the analysis of fluctuations of dipole-dipole interactions of nuclear spins and anisotropic electron-nuclear interactions responsible for chemical shielding, which are caused by molecular dynamics. However, many nanocarbon systems such as fullerene and nanotube derivatives, nanodiamonds and carbon onions reveal noticeable amount of paramagnetic defects with unpaired electrons originating from dangling bonds. The interaction between nuclear and electron spins strongly influences the nuclear spin-lattice relaxation, but usually is not taken into account, thus the relaxation data are not correctly interpreted. Here we report on the temperature dependent NMR spectra and spin-lattice relaxation measurements of intercalated fullerenes C{sub 60}(MF{sub 6}){sub 2} (M=As and Sb), where nuclear relaxation is caused by both molecular rotation and interaction between nuclei and unpaired electron spins. We present a detailed theoretical analysis of the spin-lattice relaxation data taking into account both these contributions. Good agreement between the experimental data and calculations is obtained. The developed approach would be useful in interpreting the NMR relaxation data in different nanostructures and their intercalation compounds.

  3. Comparisons of 131I, 201Tl and 99mTc activity measurements in activimeters

    International Nuclear Information System (INIS)

    Oropesa Verdecia, Pilar; Hernandez Rivero, Aerulio T.; Serra Aguila, Rolando A.; Martinez Herrera, Ernesto; Varela Corona, Consuelo

    2003-01-01

    The correct administration to a patient of the a priori established activity of the radiopharmaceutical is an important factor to ensure the confidence in the diagnosis or the therapy efficiency, keeping at the same time the human exposure as low as possible. National comparisons for the 131I, 201Tl and 99mTc activity measurements in activimeters have been organized for the first time with the aim of obtaining information about the quality of the administration of radiopharmaceuticals. In the comparison run participated ten Cuban Nuclear Medicine Departments and the laboratories involved in the production of that kind of compounds. The comparison results, shown in this paper, have facilitated the identification of the problems and to initiate preventive actions. Furthermore, these results reflect the need of establishing Quality Systems in Nuclear Medicine in Cuba

  4. Measurement and estimation of dew point for SNG. [Comparison of calculated and measured values

    Energy Technology Data Exchange (ETDEWEB)

    Furuyama, Y.

    1974-08-01

    Toho Gas measured and estimated SNG dew points in high-pressure deliveries by calculating the theoretical values by the high-pressure gas-liquid equilibrium theory using the pressure-extrapolation method to reach K = 1, and the BWR method to estimate fugacity, then verifying these values experimentally. The experimental values were measured at 161.7 to 367.5 psi using the conventional static and circulation methods, in addition to a newly developed method consisting of circulating a known composition of gas mixtures, partially freezing them, and monitoring the dew point by observing the droplets on a mirror cooled by blowing liquid nitrogen. Good agreement was found between the calculated and the experimental values.

  5. Measurement of endotoxin. II. Comparison of reactivities measured by radioimmunoassay and with the limulus test

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, H [Okayama Univ. (Japan). School of Medicine

    1976-08-01

    Various endotoxins and the ether extracts of grampositive bacteria were measured immunologically by radioimmunoassay and also biologically by the Limulus test. The minimum amount of endotoxin detectable with the Limulus test was in the range from 1 ng/ml to 1 ..mu..g/ml, with the lysate of sensitivity, 100 ng ml (E. coli 0111: B4(B) lipopolysaccharide). On the other hand, by the radioimmunoassay they were estimated in the range of 0.3 to 10 times of dry weight. Endotoxin-like activity was detected in the ether extracts of grampositive bacteria at a minimum concentration between 1 ..mu..g/ml and 100 ..mu..g/ml with the Limulus test. However, most of them were estimated by the radioimmunoassay to be under 1/50 of dry weight. Various substances such as thrombin, thromboplastin, polynosinic-polycytidylic acid, polyadenylic-polyuridylic acid, carrageenan and human colonic mucosal antigen had cross reactivities of various degrees in the minimum concentration from 10 ..mu..g/ml to 10 mg/ml. Compounds such as thrombin and thromboplastin cross-reacting in the Limulus test were scarcely measured by the radioimmunoassay except for polynucleotides. From this study, it has become clear that the radioimmunoassay method is quite specific and accurate for quantitative measurements of endotoxin.

  6. Comparison of COSMIC measurements with the IRI-2007 model over the eastern Mediterranean region

    Directory of Open Access Journals (Sweden)

    P. Vryonides

    2013-05-01

    Full Text Available This paper presents a comparison of the International Reference Ionosphere (IRI-2007 model over the eastern Mediterranean region with peak ionospheric characteristics (foF2–hmF2 and electron density profiles measured by FORMOSAT-3/COSMIC satellites in terms of GPS radio occultation technique and the Cyprus digisonde. In the absence of systematic ionosonde measurements over this area, COSMIC measurements provide an opportunity to perform such a study by considering observations for year 2010 to investigate the behaviour of the IRI-2007 model over the eastern Mediterranean area.

  7. Measurement of micro moulded parts by Computed Tomography and comparison to optical and tactile techniques

    DEFF Research Database (Denmark)

    Yagüe, J.A.; Tosello, Guido; Carmignato, S

    2011-01-01

    This paper focuses on dimensional verification of two micro-injection moulded components, selected from actual industrial productions, using CT metrological tools. In addition to CT scanning, also a tactile Coordinate Measuring Machine (CMM) with sub-micrometer uncertainty and an Optical Coordinate...... Measuring Machine (OCMM) allowing fast measurements suitable for in-line quality control were employed as validation instruments. The experimental work carried out and the analysis of the results provide valuable conclusions about the advantages and drawbacks of using CT metrology in comparison with CMM...... and OCMM when these techniques are employed for quality control of micro moulded parts....

  8. Relaxation of nuclear spin on holes in semiconductors

    International Nuclear Information System (INIS)

    Gr'ncharova, E.I.; Perel', V.I.

    1977-01-01

    The longitudienal relaxation time T 1 of nuclear spins due to dipole-dipole interaction with holes in semiconductors is calculated. Expressions for T 1 in cubic and uniaxial semiconductors are obtained for non-degenerate and degenerate cases. On the basis of comparison with available experimental data for silicon the agreement with the theoretical results is obtained. It is demonstrated that in uniaxial semiconductors the time of relaxation on holes for a nuclear spin directed along the c axis is considerably greater than that for a spin in the normal direction

  9. REAL-TIME STABILITY AND PROFILE COMPARISON MEASUREMENTS BETWEEN TWO DIFFERENT LTPS

    International Nuclear Information System (INIS)

    2005-01-01

    The Long Trace Profiler (LTP) is a precise angle measurement instrument, with a sensitivity and accuracy that can be in the sub-micron radian range. LTP characteristics depend on the particular LTP system schematic design, and the quality of components and assembly. The conditions of temperature, alignment, and mirror support during the measurement process vary between different laboratories, which influences significantly the test repeatability and accuracy. In this paper we introduce a direct comparison method to test the same object at the same point in the same environment at the same time by using two LTPs, which significantly increases the reliability of the comparison. A compact, portable LTP (PTLTP), which can be carried to different laboratories around the world, is used for comparison testing. Stability Comparison experiments between the LTP II at the National Synchrotron Radiation Research Center (NSRRC), and the PTLTP of Brookhaven National Laboratory (BNL) reveal significant differences in performance between the instruments. The experiment is set up so that each optical head simultaneously records both its own sample probe beam and also the probe beam from the other optical head. The two probe beams are reflected from same point on the mirror. Tests show that the stability of the PTLTP with a monolithic beam splitter is 10 times better than the stability of the LTP II which has a separated beam splitter unit. A scheme for comparing scanning measurements of a mirror is introduced. Experimental results show a significant difference between the two LTPs due mainly to distortions in the optical components inside the optical head. A new scheme is proposed for further mirror comparison scanning tests

  10. Comparisons of MOVES Light-duty Gasoline NOx Emission Rates with Real-world Measurements

    Science.gov (United States)

    Choi, D.; Sonntag, D.; Warila, J.

    2017-12-01

    Recent studies have shown differences between air quality model estimates and monitored values for nitrogen oxides. Several studies have suggested that the discrepancy between monitored and modeled values is due to an overestimation of NOx from mobile sources in EPA's emission inventory, particularly for light-duty gasoline vehicles. EPA's MOtor Vehicle Emission Simulator (MOVES) is an emission modeling system that estimates emissions for cars, trucks and other mobile sources at the national, county, and project level for criteria pollutants, greenhouse gases, and air toxics. Studies that directly measure vehicle emissions provide useful data for evaluating MOVES when the measurement conditions are properly accounted for in modeling. In this presentation, we show comparisons of MOVES2014 to thousands of real-world NOx emissions measurements from individual light-duty gasoline vehicles. The comparison studies include in-use vehicle emissions tests conducted on chassis dynamometer tests in support of Denver, Colorado's Vehicle Inspection & Maintenance Program and remote sensing data collected using road-side instruments in multiple locations and calendar years in the United States. In addition, we conduct comparisons of MOVES predictions to fleet-wide emissions measured from tunnels. We also present details on the methodology used to conduct the MOVES model runs in comparing to the independent data.

  11. Nuclear spin-lattice relaxation in nitroxide spin-label EPR

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    that the definition of nitrogen nuclear relaxation rate Wn commonly used in the CW-EPR literature for 14N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14N spin-lattice relaxation rate, b = Wn/(2We), preserves...... of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14N-relaxation: T1 n = 1/Wn. Results are compared and contrasted...

  12. Spectroscopic Studies of the Super Relaxed State of Skeletal Muscle.

    Directory of Open Access Journals (Sweden)

    Leonardo Nogara

    Full Text Available In the super-relaxed state of myosin, ATPase activity is strongly inhibited by binding of the myosin heads to the core of the thick filament in a structure known as the interacting-heads motif. In the disordered relaxed state myosin heads are not bound to the core of the thick filament and have an ATPase rate that is 10 fold greater. In the interacting-heads motif the two regulatory light chains appear to bind to each other. We have made single cysteine mutants of the regulatory light chain, placed both paramagnetic and fluorescent probes on them, and exchanged them into skinned skeletal muscle fibers. Many of the labeled light chains tended to disrupt the stability of the super-relaxed state, and showed spectral changes in the transition from the disordered relaxed state to the super-relaxed state. These data support the putative interface between the two regulatory light chains identified by cryo electron microscopy and show that both the divalent cation bound to the regulatory light chain and the N-terminus of the regulatory light chain play a role in the stability of the super-relaxed state. One probe showed a shift to shorter wavelengths in the super-relaxed state such that a ratio of intensities at 440nm to that at 520nm provided a measure of the population of the super-relaxed state amenable for high throughput screens for finding potential pharmaceuticals. The results provide a proof of concept that small molecules that bind to this region can destabilize the super-relaxed state and provide a method to search for small molecules that do so leading to a potentially effective treatment for Type 2 diabetes and obesity.

  13. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    Science.gov (United States)

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies.

  14. Comparison of Flight Measured, Predicted and Wind Tunnel Measured Winglet Characteristics on a KC-135 Aircraft

    Science.gov (United States)

    Dodson, R. O., Jr.

    1982-01-01

    One of the objectives of the KC-135 Winglet Flight Research and Demonstration Program was to obtain experimental flight test data to verify the theoretical and wind tunnel winglet aerodynamic performance prediction methods. Good agreement between analytic, wind tunnel and flight test performance was obtained when the known differences between the tests and analyses were accounted for. The flight test measured fuel mileage improvements for a 0.78 Mach number was 3.1 percent at 8 x 10(5) pounds W/delta and 5.5 percent at 1.05 x 10(6) pounds W/delta. Correcting the flight measured data for surface pressure differences between wind tunnel and flight resulted in a fuel mileage improvement of 4.4 percent at 8 x 10(5) pounds W/delta and 7.2 percent at 1.05 x 10(6) pounds W/delta. The performance improvement obtained was within the wind tunnel test data obtained from two different wind tunnel models. The buffet boundary data obtained for the baseline configuration was in good agreement with previous established data. Buffet data for the 15 deg cant/-4 deg incidence configuration showed a slight improvement, while the 15 deg cant/-2 deg incidence and 0 deg cant/-4 deg incidence data showed a slight deterioration.

  15. Comparison of field-measured radon diffusion coefficients with laboratory-measured coefficients

    International Nuclear Information System (INIS)

    Lepel, E.A.; Silker, W.B.; Thomas, V.W.; Kalkwarf, D.R.

    1983-04-01

    Experiments were conducted to compare radon diffusion coefficients determined for 0.1-m depths of soils by a steady-state method in the laboratory and diffusion coefficients evaluated from radon fluxes through several-fold greater depths of the same soils covering uranium-mill tailings. The coefficients referred to diffusion in the total pore volume of the soils and are equivalent to values for the quantity, D/P, in the Generic Environmental Impact Statement on Uranium Milling prepared by the US Nuclear Regulatory Commission. Two soils were tested: a well-graded sand and an inorganic clay of low plasticity. For the flux evaluations, radon was collected by adsorption on charcoal following passive diffusion from the soil surface and also from air recirculating through an aluminum tent over the soil surface. An analysis of variance in the flux evaluations showed no significant difference between these two collection methods. Radon diffusion coefficients evaluated from field data were statistically indistinguishable, at the 95% confidence level, from those measured in the laboratory; however, the low precision of the field data prevented a sensitive validation of the laboratory measurements. From the field data, the coefficients were calculated to be 0.03 +- 0.03 cm 2 /s for the sand cover and 0.0036 +- 0.0004 cm 2 /s for the clay cover. The low precision in the coefficients evaluated from field data was attributed to high variation in radon flux with time and surface location at the field site

  16. Peeling mode relaxation ELM model

    International Nuclear Information System (INIS)

    Gimblett, C. G.

    2006-01-01

    This paper discusses an approach to modelling Edge Localised Modes (ELMs) in which toroidal peeling modes are envisaged to initiate a constrained relaxation of the tokamak outer region plasma. Relaxation produces both a flattened edge current profile (which tends to further destabilise a peeling mode), and a plasma-vacuum negative current sheet which has a counteracting stabilising influence; the balance that is struck between these two effects determines the radial extent (rE) of the ELM relaxed region. The model is sensitive to the precise position of the mode rational surfaces to the plasma surface and hence there is a 'deterministic scatter' in the results that has an accord with experimental data. The toroidal peeling stability criterion involves the edge pressure, and using this in conjunction with predictions of rE allows us to evaluate the ELM energy losses and compare with experiment. Predictions of trends with the edge safety factor and collisionality are also made

  17. Dynamic and structural characterisation of micellar solutions of surfactants by spin relaxation and translational diffusion

    International Nuclear Information System (INIS)

    Mahieu, Nathalie

    1992-01-01

    The work reported in this research thesis aimed at characterizing micellar phases formed by some surfactants (sodium carboxylates) in aqueous solution. After some recalls on nuclear magnetic resonance dealing with spin relaxation (longitudinal relaxation, transverse relaxation, relaxation in the rotating coordinate system, and crossed relaxation), and comments on the dipolar mechanism responsible of relaxation phenomena, the author presents the methods used for relaxation parameter measurement and the data processing software issued from experiments. He presents experiments which allowed the self-diffusion coefficient to be measured, reports data processing, and addresses problems of special diffusion and of coherence transfers during diffusion measurements. Results of proton relaxation measurements are then presented and discussed. They are used to determine the micellar state of the studied carboxylates. The case of the oleate is also addressed. Measurements of carbon-13 relaxation times are reported, and exploited in terms of structural parameters by using the Relaxator software. An original method of the hetero-nuclear Overhauser method is presented, and used to assess the average distance between water molecules and micelle surface [fr

  18. A comparison of predictions and measurements for the Stripa simulated drift experiment

    International Nuclear Information System (INIS)

    Hodgkinson, D.

    1991-02-01

    This paper presents a comparison of measurements and predictions for the simulated drift experiment based on groundwater flow to the D-holes at the SCV site. The comparison was carried out on behalf of the Stripa task force on fracture flow modelling, as a learning exercise for the validation exercise to be based on flow to the validation drift. The paper summarises the characterisation data and their preliminary interpretation, and reviews the fracture flow modelling predictions made by teams from AEA Harwell, Golder Associates and Lawrence Berkeley Laboratory. The predictions are compared with each other and with the D-hole inflow measurements, and this experience is used to provide detailed feedback to future experimental and modelling work. (35 refs.)

  19. Instruments to measure radon activity concentration or exposure to radon. Interlaboratory comparison 2011

    International Nuclear Information System (INIS)

    Foerster, Elisabeth; Beck, Thomas; Buchroeder, Helmut; Doering, Joachim; Schmidt, Volkmar

    2011-10-01

    According to the Directive 96/29/EURATOM the monitoring of occupational radiation exposures shall base on individual measurements carried out by an approved dosimetric service. Pursuant to the European Directive an approved dosimetric service is a body responsible for the calibration, reading or interpretation of individual monitoring devices.., whose capacity to act in this respect is recognized by the competent authorities. This concept will also be applied to radon services issuing passive radon measurement devices. Passive radon measurement devices 1 using solid state nuclear track detectors or electrets are recommended for individual monitoring of exposures to radon. German regulations lay down that radon measuring devices are appropriate for purposes of occupational radiation monitoring if the devices are issued by recognized radon measurement services, and the measurement service submits devices of the same type issued for radon monitoring to regular intercomparisons conducted by BfS. A radon measuring service is recognized by the competent authority if it proves its organizational and technical competence, e. g. by accreditation. These regulations have been introduced in the area of occupational radiation exposures. Nevertheless, it is recommended that radon measuring services which carry out radon measurements in other areas (e.g. dwellings) should subject themselves to these measures voluntarily. The interlaboratory comparisons comprise the organization, exposure, and evaluation of measurements of radon activity concentration or exposure to radon. The comparisons only concern radon-222; radon-220 is not in the scope. Radon services being interested can get further information from the website www.bfs.de/de/ion/radon/fachinfomessung/vergleichspruefungen.html and from the European Information System on Proficiency Testing Schemes (eptis) available in the internet. (orig.)

  20. Comparison of choose-a-movie and approach–avoidance paradigms to measure social motivation

    OpenAIRE

    Dubey, I.; Ropar, D.; Hamilton, A.

    2017-01-01

    Social motivation is a subjective state which is rather difficult to quantify. It has sometimes been conceptualised as “behavioural effort” to seek social contact. Two paradigms: approach–avoidance (AA) and choose a movie (CAM), based on the same conceptualisation, have been used to measure social motivation in people with and without autism. However, in absence of a direct comparison, it is hard to know which of these paradigms has higher sensitivity in estimating preference for social over ...

  1. Evaluating the reliability of uranium concentration and isotope ratio measurements via an interlaboratory comparison program

    International Nuclear Information System (INIS)

    Oliveira Junior, Olivio Pereira de; Oliveira, Inez Cristina de; Pereira, Marcia Regina; Tanabe, Eduardo

    2009-01-01

    The nuclear fuel cycle is a strategic area for the Brazilian development because it is associated with the generation of electricity needed to boost the country economy. Uranium is one the chemical elements in this cycle and its concentration and isotope composition must be accurately known. In this present work, the reliability of the uranium concentration and isotope ratio measurements carried out at the CTMSP analytical laboratories is evaluated by the results obtained in an international interlaboratory comparison program. (author)

  2. Comparison of measured and predicted airfoil self-noise with application to wind turbine noise reduction

    International Nuclear Information System (INIS)

    Dassen, T.; Parchen, R.; Guidati, G.; Wagner, S.; Kang, S.; Khodak, A.E.

    1998-01-01

    In the ongoing JOULE-III project 'Development of Design Tools for Reduced Aerodynamic Noise Wind Turbines (DRAW)', prediction codes for inflow-turbulence (IT) noise and turbulent boundary layer trailing-edge (TE) noise, are developed and validated. It is shown that the differences in IT noise radiation between airfoils having a different shape, are correctly predicted. The first, preliminary comparison made between predicted and measured TE noise spectra yields satisfactory results. 17 refs

  3. Strain relaxation of germanium-tin (GeSn) fins

    Science.gov (United States)

    Kang, Yuye; Huang, Yi-Chiau; Lee, Kwang Hong; Bao, Shuyu; Wang, Wei; Lei, Dian; Masudy-Panah, Saeid; Dong, Yuan; Wu, Ying; Xu, Shengqiang; Tan, Chuan Seng; Gong, Xiao; Yeo, Yee-Chia

    2018-02-01

    Strain relaxation of biaxially strained Ge1-xSnx layer when it is patterned into Ge1-xSnx fin structures is studied. Ge1-xSnx-on-insulator (GeSnOI) substrate was realized using a direct wafer bonding (DWB) technique and Ge1-xSnx fin structures were formed by electron beam lithography (EBL) patterning and dry etching. The strain in the Ge1-xSnx fins having fin widths (WFin) ranging from 1 μm down to 80 nm was characterized using micro-Raman spectroscopy. Raman measurements show that the strain relaxation increases with decreasing WFin. Finite element (FE) simulation shows that the strain component in the transverse direction relaxes with decreasing WFin, while the strain component along the fin direction remains unchanged. For various Ge1-xSnx fin widths, transverse strain relaxation was further extracted using micro-Raman spectroscopy, which is consistent with the simulation results.

  4. Dielectric relaxation studies of dilute solutions of amides

    Energy Technology Data Exchange (ETDEWEB)

    Malathi, M.; Sabesan, R.; Krishnan, S

    2003-11-15

    The dielectric constants and dielectric losses of formamide, acetamide, N-methyl acetamide, acetanilide and N,N-dimethyl acetamide in dilute solutions of 1,4-dioxan/benzene have been measured at 308 K using 9.37 GHz, dielectric relaxation set up. The relaxation time for the over all rotation {tau}{sub (1)} and that for the group rotation {tau}{sub (2)} of (the molecules were determined using Higasi's method. The activation energies for the processes of dielectric relaxation and viscous flow were determined by using Eyring's rate theory. From relaxation time behaviour of amides in non-polar solvent, solute-solvent and solute-solute type of molecular association is proposed.

  5. Mechanical properties of plant cell walls probed by relaxation spectra

    DEFF Research Database (Denmark)

    Hansen, Steen Laugesen; Ray, Peter Martin; Karlsson, Anders Ola

    2011-01-01

    Relax, that deduces relaxation spectra from appropriate rheological measurements is presented and made accessible through a Web interface. BayesRelax models the cell wall as a continuum of relaxing elements, and the ability of the method to resolve small differences in cell wall mechanical properties is demonstrated......Transformants and mutants with altered cell wall composition are expected to display a biomechanical phenotype due to the structural role of the cell wall. It is often quite difficult, however, to distinguish the mechanical behavior of a mutant's or transformant's cell walls from that of the wild...... type. This may be due to the plant’s ability to compensate for the wall modification or because the biophysical method that is often employed, determination of simple elastic modulus and breakstrength, lacks the resolving power necessary for detecting subtle mechanical phenotypes. Here, we apply...

  6. Comparison of measured and computed radial trajectories of plasma focus devices UMDPF1 and UMDPF0

    Energy Technology Data Exchange (ETDEWEB)

    Lim, L. H.; Yap, S. L., E-mail: yapsl@um.edu.my; Lim, L. K.; Lee, M. C.; Poh, H. S.; Ma, J. [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yap, S. S. [UMPEDAC, University of Malaya, 50603 Kuala Lumpur (Malaysia); Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia); Lee, S. [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); INTI International University, 71800 Nilai (Malaysia); Institute for Plasma Focus Studies, 32 Oakpark Drive, Chadstone 3148 (Australia)

    2015-09-15

    In published literature, there has been scant data on radial trajectory of the plasma focus and no comparison of computed with measured radial trajectory. This paper provides the first such comparative study. We compute the trajectories of the inward-moving radial shock and magnetic piston of UMDPF1 plasma focus and compare these with measured data taken from a streak photograph. The comparison shows agreement with the measured radial trajectory in terms of average speeds and general shape of trajectory. This paper also presents the measured trajectory of the radially compressing piston in another machine, the UMDPF0 plasma focus, confirming that the computed radial trajectory also shows similar general agreement. Features of divergence between the computed and measured trajectories, towards the end of the radial compression, are discussed. From the measured radial trajectories, an inference is made that the neutron yield mechanism could not be thermonuclear. A second inference is made regarding the speeds of axial post-pinch shocks, which are recently considered as a useful tool for damage testing of fusion-related wall materials.

  7. 中西方古典音乐放松效果及生理唤醒对比——莫扎特D大调双钢琴奏鸣曲K.448与春江花月夜曲%On the Comparison of Perceived and Physiological Indicators of Relaxation of Chinese and Western Classical Music

    Institute of Scientific and Technical Information of China (English)

    李哲; 汤永隆; 邓丽俐; 赵玉芳

    2009-01-01

    以33名大学本科生为实验对象,随机安排在10 min的莫扎特奏鸣曲K.448、春江花月夜曲或无音乐条件中,被试在实验前后自评其放松效果,记录其心率、皮温、皮电生理指标.结果表明:在清醒、注意和心率上,音乐类型和测量时间的交互作用显著;莫扎特音乐组在清醒、注意和心率均呈上升趋势,而另两组呈下降趋势;春江花月夜组心率显著下降,放松增加感高于其他两组;其他指标无显著差异.%The research conducted a comparison of the subjective and objective indicators of relaxation under Western classical music and Chinese classical music backgrounds. Thirty-three undergraduate students were randomly assigned to listen to one of two relaxation ("Mozart Sonata for Two Pianos in D Major-K. 448" or "Chun Jiang Hua Yue Ye") or control (silence) conditions for 10 minutes. The students' self-reports of arousal, attention, mood, and relaxation before and after exposure to the music condition, and records of HR, TEMP and SC biofeedback were obtained. By using MANOVA to analyze data in different music backgrounds and different experimental phases, the results indicated that arousal, attention and HR of participants showed significant interaction between music type and experimental phases. Participants' arousal, attention and HR in Mozart group have a greater increase than other two groups. In Chun Jiang Hua Yue Ye group, participants" HR has a significant greater decrease; the relaxation in Chun Jiang Hua Yue Ye group was the highest among three groups. However, no differences were found between different types of music on mood, SC and TEMP. To Chinese people, Chinese classical music has more relaxation effect than Western classical music.

  8. Survivor dosimetry. Part D. Graphical comparisons of measurements and calculations for neutrons and gamma rays

    International Nuclear Information System (INIS)

    Egbert, Stephen D.; Cullings, Harry M.

    2005-01-01

    An important part of validating the DS02 dosimetry system is the comparison of calculated initial neutron and gamma-ray radiation activation from the atomic bombs with all measurements that have been made, both before and during this current dosimetry reevaluation. All measurements that were made before the year 2002 are listed in Table 5 of Chapter 4. Many of these measurements have been compared to previous versions of the dosimetry systems for Hiroshima and Nagasaki. In this section the measurements are compared to the new dosimetry system DS02. For the purposes of showing historical context, they are also compared to the previous dosimetry system DS86. References for these measurements are found in Chapter 4. (J.P.N.)

  9. Comparison of dose measurements in water versus in air for therapy

    International Nuclear Information System (INIS)

    Nasukha

    1987-01-01

    Comparison of dose measurements in water versus in air for therapy. Dose measurements in water and in the air had been done by teletherapy unit Co-60 Picker Model V 4m/60 with Farmer dosimeter. The result of inverse square law, TAR, PDD, and PSF compared to BJR No. 17 produced a difference of more than 4,65% with SSD 80 cm. Doses in water calculated from the result of dose measurement in air using BJR tables given, was compared with direct dose measurement in water. Values of 0,9850 to 1,0302 were obtained if using inverse square law, PDD and PSF formula. Using inverse square law and TAR, values of 0,9474 to 1,0197 were obtained for 4 depths and 5 field sizes. Measurements done in 5 cm depth and 10 cm x 10 cm field size using both methods, were still good. (author). 7 figs, 8 refs

  10. [Comparison of invasive blood pressure measurement in the aorta with indirect oscillometric blood pressure measurement at the wrist and forearm].

    Science.gov (United States)

    Saul, F; Aristidou, Y; Klaus, D; Wiemeyer, A; Lösse, B

    1995-09-01

    measuring arterial blood pressure remains the measurement at the upper arm site, which nevertheless showed a systolic pseudohypertension (deviation of more than 10 mm Hg) in comparison to the invasively measured values in 15% of our selected patients and a diastolic pseudohypertension (deviation of more than 15 mm Hg) in 23% of the patients.

  11. Spectral analysis of atmospheric composition: application to surface ozone model–measurement comparisons

    Directory of Open Access Journals (Sweden)

    D. R. Bowdalo

    2016-07-01

    Full Text Available Models of atmospheric composition play an essential role in our scientific understanding of atmospheric processes and in providing policy strategies to deal with societally relevant problems such as climate change, air quality, and ecosystem degradation. The fidelity of these models needs to be assessed against observations to ensure that errors in model formulations are found and that model limitations are understood. A range of approaches are necessary for these comparisons. Here, we apply a spectral analysis methodology for this comparison. We use the Lomb–Scargle periodogram, a method similar to a Fourier transform, but better suited to deal with the gapped data sets typical of observational data. We apply this methodology to long-term hourly ozone observations and the equivalent model (GEOS-Chem output. We show that the spectrally transformed observational data show a distinct power spectrum with regimes indicative of meteorological processes (weather, macroweather and specific peaks observed at the daily and annual timescales together with corresponding harmonic peaks at one-half, one-third, etc., of these frequencies. Model output shows corresponding features. A comparison between the amplitude and phase of these peaks introduces a new comparison methodology between model and measurements. We focus on the amplitude and phase of diurnal and seasonal cycles and present observational/model comparisons and discuss model performance. We find large biases notably for the seasonal cycle in the mid-latitude Northern Hemisphere where the amplitudes are generally overestimated by up to 16 ppbv, and phases are too late on the order of 1–5 months. This spectral methodology can be applied to a range of model–measurement applications and is highly suitable for Multimodel Intercomparison Projects (MIPs.

  12. Calorimetric and relaxation properties of xylitol-water mixtures

    Science.gov (United States)

    Elamin, Khalid; Sjöström, Johan; Jansson, Helén; Swenson, Jan

    2012-03-01

    We present the first broadband dielectric spectroscopy (BDS) and differential scanning calorimetry study of supercooled xylitol-water mixtures in the whole concentration range and in wide frequency (10-2-106 Hz) and temperature (120-365 K) ranges. The calorimetric glass transition, Tg, decreases from 247 K for pure xylitol to about 181 K at a water concentration of approximately 37 wt. %. At water concentrations in the range 29-35 wt. % a plentiful calorimetric behaviour is observed. In addition to the glass transition, almost simultaneous crystallization and melting events occurring around 230-240 K. At higher water concentrations ice is formed during cooling and the glass transition temperature increases to a steady value of about 200 K for all higher water concentrations. This Tg corresponds to an unfrozen xylitol-water solution containing 20 wt. % water. In addition to the true glass transition we also observed a glass transition-like feature at 220 K for all the ice containing samples. However, this feature is more likely due to ice dissolution [A. Inaba and O. Andersson, Thermochim. Acta, 461, 44 (2007)]. In the case of the BDS measurements the presence of water clearly has an effect on both the cooperative α-relaxation and the secondary β-relaxation. The α-relaxation shows a non-Arrhenius temperature dependence and becomes faster with increasing concentration of water. The fragility of the solutions, determined by the temperature dependence of the α-relaxation close to the dynamic glass transition, decreases with increasing water content up to about 26 wt. % water, where ice starts to form. This decrease in fragility with increasing water content is most likely caused by the increasing density of hydrogen bonds, forming a network-like structure in the deeply supercooled regime. The intensity of the secondary β-relaxation of xylitol decreases noticeably already at a water content of 2 wt. %, and at a water content above 5 wt. % it has been replaced by a

  13. NO2 DOAS measurements from ground and space: comparison of ground based measurements and OMI data in Mexico City

    Science.gov (United States)

    Rivera, C.; Stremme, W.; Grutter, M.

    2012-04-01

    The combination of satellite data and ground based measurements can provide valuable information about atmospheric chemistry and air quality. In this work we present a comparison between measured ground based NO2 differential columns at the Universidad Nacional Autónoma de México (UNAM) in Mexico City, using the Differential Optical Absorption Spectroscopy (DOAS) technique and NO2 total columns measured by the Ozone Monitoring Instrument (OMI) onboard the Aura satellite using the same measurement technique. From these data, distribution maps of average NO2 above the Mexico basin were constructed and hot spots inside the city could be identified. In addition, a clear footprint was detected from the Tula industrial area, ~50 km northwest of Mexico City, where a refinery, a power plant and other industries are located. A less defined footprint was identified in the Cuernavaca basin, South of Mexico City, and the nearby cities of Toluca and Puebla do not present strong enhancements in the NO2 total columns. With this study we expect to cross-validate space and ground measurements and provide useful information for future studies.

  14. Relaxation effect of abacavir on rat basilar arteries.

    Directory of Open Access Journals (Sweden)

    Rachel Wai Sum Li

    Full Text Available The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels.The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5' nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate.Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5' nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries.Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may not be related to

  15. The Elicitation of Relaxation and Interoceptive Awareness Using Floatation Therapy in Individuals With High Anxiety Sensitivity.

    Science.gov (United States)

    Feinstein, Justin S; Khalsa, Sahib S; Yeh, Hung-Wen; Al Zoubi, Obada; Arevian, Armen C; Wohlrab, Colleen; Pantino, Marie K; Cartmell, Laci J; Simmons, W Kyle; Stein, Murray B; Paulus, Martin P

    2018-03-09

    Floatation-REST (Reduced Environmental Stimulation Therapy), an intervention that attenuates exteroceptive sensory input to the nervous system, has recently been found to reduce state anxiety across a diverse clinical sample with high levels of anxiety sensitivity (AS). To further examine this anxiolytic effect, the present study investigated the affective and physiological changes induced by Floatation-REST and assessed whether individuals with high AS experienced any alterations in their awareness for interoceptive sensation while immersed in an environment lacking exteroceptive sensation. Using a within-subject crossover design, 31 participants with high AS were randomly assigned to undergo a 90-minute session of Floatation-REST or an exteroceptive comparison condition. Measures of self-reported affect and interoceptive awareness were collected before and after each session, and blood pressure was measured during each session. Relative to the comparison condition, Floatation-REST generated a significant anxiolytic effect characterized by reductions in state anxiety and muscle tension and increases in feelings of relaxation and serenity (p 12 mm Hg). The float environment also significantly enhanced awareness and attention for cardiorespiratory sensations. Floatation-REST induced a state of relaxation and heightened interoceptive awareness in a clinical sample with high AS. The paradoxical nature of the anxiolytic effect in this sample is discussed in relation to Wolpe's theory of reciprocal inhibition and the regulation of distress via sustained attention to present moment visceral sensations such as the breath. Copyright © 2018 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  16. An investigation of methods for free-field comparison calibration of measurement microphones

    DEFF Research Database (Denmark)

    Barrera-Figueroa, Salvador; Moreno Pescador, Guillermo; Jacobsen, Finn

    2010-01-01

    Free-field comparison calibration of measurement microphones requires that a calibrated reference microphone and a test microphone are exposed to the same sound pressure in a free field. The output voltages of the microphones can be measured either sequentially or simultaneously. The sequential...... method requires the sound field to have good temporal stability. The simultaneous method requires instead that the sound pressure is the same in the positions where the microphones are placed. In this paper the results of the application of the two methods are compared. A third combined method...

  17. A Comparison Between Measured and Predicted Hydrodynamic Damping for a Jack-Up Rig Model

    DEFF Research Database (Denmark)

    Laursen, Thomas; Rohbock, Lars; Jensen, Jørgen Juncher

    1996-01-01

    An extensive set of measurements funded by the EU project Large Scale Facilities Program has been carried out on a model of a jack-up rig at the Danish Hydraulic Institute. The test serieswere conducted by MSC and include determination of base shears and overturning moments in both regular...... methods.In the comparison between the model test results and the theoretical predictions, thehydro-dynamic damping proves to be the most important uncertain parameter. It is shown thata relative large hydrodynamic damping must be assumed in the theoretical calculations in orderto predict the measured...

  18. Inter-laboratory comparison of HITU power measurement methods and capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Jenderka, K V [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Durando, G [Istituto Nazionale di Ricerca Metrologica (INRIM), Strada delle Cacce 91, 10135 Torino (Italy); Karaboece, B [Tuebitak Ulusal Metroloji Enstituesue (UME), P.K. 54 41470 Gebze-Kocaeli (Turkey); Rajagopal, S; Shaw, A, E-mail: kvjend@ieee.org [National Physical Laboratory (NPL), Hampton Road, Teddington, TW11 0LW (United Kingdom)

    2011-02-01

    High Intensity Therapeutic Ultrasound (HITU) is gaining in importance among the spectrum of therapeutic options to combat cancer. HITU has already been approved and is in clinical use for the treatment of organs like the prostate, the liver and the uterus. Nevertheless, the metrology of the applied high power ultrasound fields, and in consequence, reliable treatment planning and monitoring, is still a challenge. As part of a European Metrology Research Programme project, the four National Metrology Institutes from the UK, Germany, Italy and Turkey conducted an inter-laboratory comparison of their power measurement capabilities at power levels of 5, 25, 75 and 150 W each at frequencies of 1.1, 1.5 and 3.3 MHz. The task was to measure the total, time-averaged ultrasonic output power, emitted by the circulated transducers under specified electrical excitation conditions into an anechoic water load, and the actual rms transducer input voltage. The output value to be reported was the electro-acoustic radiation conductance including the associated standard and expanded uncertainties. Several different measurement techniques were applied to gain further insight into HITU power measurement. The deviations from the calculated comparison reference value found for the different techniques are discussed and conclusions for the further improvement of measuring procedures are drawn.

  19. Comparison of stethoscope bell and diaphragm, and of stethoscope tube length, for clinical blood pressure measurement.

    Science.gov (United States)

    Liu, Chengyu; Griffiths, Clive; Murray, Alan; Zheng, Dingchang

    2016-06-01

    This study investigated the effect of stethoscope side and tube length on auscultatory blood pressure (BP) measurement. Thirty-two healthy participants were studied. For each participant, four measurements with different combinations of stethoscope characteristics (bell or diaphragm side, standard or short tube length) were each recorded at two repeat sessions, and eight Korotkoff sound recordings were played twice on separate days to one experienced listener to determine the systolic and diastolic BPs (SBP and DBP). Analysis of variance was carried out to study the measurement repeatability between the two repeat sessions and between the two BP determinations on separate days, as well as the effects of stethoscope side and tube length. There was no significant paired difference between the repeat sessions and between the repeat determinations for both SBP and DBP (all P-values>0.10, except the repeat session for SBP using short tube and diaphragm). The key result was that there was a small but significantly higher DBP on using the bell in comparison with the diaphragm (0.66 mmHg, P=0.007), and a significantly higher SBP on using the short tube in comparison with the standard length (0.77 mmHg, P=0.008). This study shows that stethoscope characteristics have only a small, although statistically significant, influence on clinical BP measurement. Although this helps understand the measurement technique and resolves questions in the published literature, the influence is not clinically significant.

  20. Inter-laboratory comparison of HITU power measurement methods and capabilities

    International Nuclear Information System (INIS)

    Jenderka, K V; Durando, G; Karaboece, B; Rajagopal, S; Shaw, A

    2011-01-01

    High Intensity Therapeutic Ultrasound (HITU) is gaining in importance among the spectrum of therapeutic options to combat cancer. HITU has already been approved and is in clinical use for the treatment of organs like the prostate, the liver and the uterus. Nevertheless, the metrology of the applied high power ultrasound fields, and in consequence, reliable treatment planning and monitoring, is still a challenge. As part of a European Metrology Research Programme project, the four National Metrology Institutes from the UK, Germany, Italy and Turkey conducted an inter-laboratory comparison of their power measurement capabilities at power levels of 5, 25, 75 and 150 W each at frequencies of 1.1, 1.5 and 3.3 MHz. The task was to measure the total, time-averaged ultrasonic output power, emitted by the circulated transducers under specified electrical excitation conditions into an anechoic water load, and the actual rms transducer input voltage. The output value to be reported was the electro-acoustic radiation conductance including the associated standard and expanded uncertainties. Several different measurement techniques were applied to gain further insight into HITU power measurement. The deviations from the calculated comparison reference value found for the different techniques are discussed and conclusions for the further improvement of measuring procedures are drawn.