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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 77 (1973), S. 2912-2918 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The introduction of a divertor Thomson scattering system in DIII-D [J. Luxon et al., International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1986), p. 159] has enabled accurate determination of the plasma properties in the divertor region. Two plasma regimes are identified: detached and attached. The electron temperature in the detached regime is about 2 eV, much lower than 5–10 eV determined earlier. Fluid models of the DIII-D scrape-off layer plasma successfully reproduce many of the features of these two regimes, including the boundaries for transition between them. Detailed comparison between the results obtained from the fluid models and experiment suggest the models underestimate the spatial extent of the low-temperature region associated with the detached plasma mode. Low-temperature atomic physics processes that are not included in the present models may account for this discrepancy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1417-1422 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The average value of the magnetocrystalline anisotropy field, Hk, is an important parameter for the characterization of magnetic recording media but is difficult to measure accurately due in part to the effect of interactions between the grains. In order to evaluate Hk we have studied two model CoCrPtTa magnetic films using a number of complementary techniques: high field ferromagnetic resonance (FMR) (35.0–45.0 kOe), low field (〈20 kOe) vector vibrating-sample magnetometry and torque magnetometry. The FMR measurements were performed at a number of discrete frequencies in the range 75–93 GHz using a new quasi-optical spectrometer developed at the University of St. Andrews. The values of Hk derived by FMR (10.8 kOe) are approximately 10% greater than those obtained from conventional magnetometry (9.6 kOe). This difference is believed to be due to the presence of intergranular exchange coupling which reduces the measured value of anisotropy when the applied field is not sufficiently large to completely align the magnetic moments. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 3016-3023 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A design for a high mass resolution scanning atom probe is described, which utilizes a two-conductor microelectrode held at 10–100 μm from the specimen. Field evaporation pulses are applied to the part of the counter-electrode closest to the specimen, while the output is maintained at ground. If the gap between the two conductors is small, field evaporated ions pass through the microelectrode while the pulse voltage is essentially constant, and thus the resultant spread in ion energies is small and the mass resolution in time-of-flight mass spectrometry is correspondingly improved. Initial results indicate improvements of 4–5 times over the mass resolution obtained with a simple counter electrode. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 3924-3937 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a novel cw millimeter-wave electron spin resonance (ESR) spectrometer designed to operate in the frequency range of 80–200 GHz and in the temperature range of 2.5–300 K, which may be easily scaled to higher frequencies. The spectrometer uses a bimodal reflection cavity coupled to a circular corrugated guide and uses Gaussian quasi-optics for most of the front-end signal processing. This technique has very low insertion loss and allows a number of sophisticated measurement techniques to be employed including induction operation, which significantly reduces the effect of microphonics and stray reflections. A number of examples are given illustrating the sensitivity of the instrument and the advantages of using ESR at high fields. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 49-58 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A wide acceptance angle first-order reflectron lens has been incorporated into a three-dimensional atom probe (3DAP) to provide improved mass resolution. This new 3DAP instrument is capable of resolving isotopes in the mass spectrum, with resolutions better than m/Δm=500 full width at half maximum and 250 full width at 10% maximum. However, use of a reflectron for energy compensation within an imaging system means that improvements in mass resolution result in degradation of the spatial resolution. This article addresses the detailed design of the energy compensated 3DAP, and the minimization and compensation of chromatic aberrations in the imaging performance of the instrument. Some applications of the new instrument are included to illustrate its capabilities in the atomic-scale analysis of engineering alloys. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2342-2342 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A brief description of the most common encoding methods, and their relative merits, used with position sensitive proportional detectors at synchrotron facilities will be made. While some of these systems are reaching maturity, continued development is resulting in further improvements, especially in terms of linearity and resolution. The use of detectors with special geometries for specific experiments will be described. The microstrip gas chamber will be addressed, with particular emphasis on a comparison of its capabilities with those of the multiwire proportional chamber. The development of proportional detectors intended for dynamic studies at second- and third-generation sources, with counting rate capabilities well in excess of these generally available at present, will be described. The use of gas based detectors, albeit with modest energy resolution, for photon detection in the energy regime of a few hundred electron volts will be mentioned. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 28 (2003), S. 0 
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Child 29 (2003), S. 0 
    ISSN: 1365-2214
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Background  Visual analogue scales (VAS) are used to assess the strength of perceptions of both children and adults in many clinical and research settings. Although the VAS has been shown by some authors to be reliable for use by children aged 5 years and older, others have proposed that young children, generally ≤ 7 years of age, may not have the conceptual ability to use a VAS.Objective  To identify demographic and cognitive variables that would maximize the accuracy of predicting children's abilities to use a VAS.Methods  Forty kindergarten children performed a seriation task, used a VAS to perform a calibration task and completed the Block Design and Vocabulary subtests of the Wechsler Preschool and Primary Scale of Intelligence – Revised (WPPSI-R). An estimated IQ was calculated from the WPPSI-R subtest scores. Socioeconomic status was assessed using the Hollingshead Four Factor Index of Social Status. Logistic regression was used to determine the best predictive models. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy were calculated for statistically significant predictive models.Main outcome measure  Successful completion of the calibration study by the child.Results  Only 42% of the subjects could use a VAS. The subject's age (≥ 5.6 years), combined with estimated IQ (≥ 100), was the best predictor of a child's ability to use a VAS (88% accuracy).Conclusion  The majority of kindergarten children in our study could not complete a VAS accurately. Cognitive ability, combined with chronological age, was the best predictor of a child's accurate use of a VAS, as determined by logistic regression. Paediatric researchers may need to consider alternative rating scales to measure perceptions in children under 7 years of age.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8844-8846 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation by photoluminescence (PL) spectroscopy of cross-barrier recombination between spatially separated two-dimensional electron and hole gases confined respectively in the quantum well (QW) and collector accumulation layer of a GaAs/AlGaAs double-barrier resonant tunneling structure. At the onset of the n=3(E3) resonance in the current–voltage characteristic, the energy of the cross-barrier transition Ecr is found to coincide with that of the PL peak arising from recombination of electrons from the E3 confined level in the QW with n=1 confined hole states (E3lh recombination). Similarly, at the onset of the E4 resonance, Ecr≈E4lh. We show that this behavior arises as a consequence of the symmetrical potential distribution within the structure at the onsets of the resonances. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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