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  • 1
    Electronic Resource
    Electronic Resource
    Real-time phase-selective data acquisition system for measurement of wave phenomena in pulsed plasma discharges (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 2027-2031 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel data acquisition system and methodology have been developed for the study of wave phenomena in pulsed plasma discharges. The method effectively reduces experimental uncertainty due to shot-to-shot fluctuations in high repetition rate experiments. Real-time analysis of each wave form allows classification of discharges by wave amplitude, phase, or other features. Measurements can then be constructed from subsets of discharges having similar wave properties. The method clarifies the trade-offs between experimental uncertainty reduction and increased demand for data storage capacity and acquisition time. Finally, this data acquisition system is simple to implement and requires relatively little equipment: only a wave form digitizer and a moderately fast computer. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148893
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of the H− thermal energy in a volume ion source plasma (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1212-1219 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The H− negative ion thermal energy measured using the two-laser-pulse photodetachment technique is reported to be in the range from 0.1 to 0.7 eV for various conditions of volume ion source operation (pressure−from 2 to 7 mTorr, discharge current−from 1.5 to 20 A). The hydrogen pressure has a significant effect in lowering the negative ion temperature, while the increase of the discharge current leads to a rise in T−. It is found that T− is a fraction of the electron temperature, Te. This fraction is strongly dependent on the gas pressure. T− scales linearly with the electron temperature and exceeds the highest values predicted by the theory of dissociative attachment. The possible mechanisms for H− ion heating are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349575
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  • 3
    Electronic Resource
    Electronic Resource
    Observations of fast anisotropic ion heating, ion cooling, and ion recycling in large-amplitude drift waves (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 716-728 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Large-amplitude drift wave fluctuations are observed to cause severe ion temperature oscillations in plasmas of the Caltech Encore tokamak [J. M. McChesney, P. M. Bellan, and R. A. Stern, Phys. Fluids B 3, 3370 (1991)]. Experimental investigations of the complete ion dynamical behavior in these waves are presented. The wave electric field excites stochastic ion orbits in the plane normal (⊥) to B, resulting in rapid ⊥ heating. Ion–ion collisions impart energy along ((parallel)) B, relaxing the ⊥-(parallel) temperature anisotropy. Hot ions with large orbit radii escape confinement, reaching the chamber wall and cooling the distribution. Cold ions from the plasma edge convect back into the plasma (i.e., recycle), causing further cooling and significantly replenishing the density depleted by orbit losses. The ion–ion collision period τii∼T3/2/n fluctuates strongly with the drift wave phase, due to intense ((approximate)50%) fluctuations in n and T. Evidence for particle recycling is given by observations of bimodal ion velocity distributions near the plasma edge, indicating the presence of cold ions (0.4 eV) superposed atop the hot (4–8 eV) plasma background. These appear periodically, synchronous with the drift wave phase at which ion fluid flow from the wall toward the plasma center peaks. Evidence is presented that such a periodic heat/loss/recycle/cool process is expected in plasmas with strong stochastic heating. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872758
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  • 4
    Electronic Resource
    Electronic Resource
    Poincaré maps define topography of Vlasov distribution functions consistent with stochastic dynamics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2963-2969 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In a recent paper [A. D. Bailey et al., Phys. Rev. Lett. 34, 3124 (1993)], the authors presented direct planar laser induced fluorescence measurements of the oscillatory ion fluid velocity field in the presence of a large amplitude drift-Alfven wave. Surprisingly, the measured speeds were an order of magnitude lower than predicted by standard fluid theory, yet the flow pattern was consistent with the fluid theory. A new model, based on the connection between stochasticity and bulk behavior, is presented which gives insights into the cause of this behavior. It is shown that when particle motion is stochastic, invariant sets of a ‘Poincaré map' define a flat-topped particle distribution function consistent with both the electromagnetic field driving the Vlasov equation and the fine-scale single particle dynamics. The approach is described for the general case and explored for a slab model of the observed drift wave. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871194
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  • 5
    Electronic Resource
    Electronic Resource
    Observation of fast stochastic ion heating by drift waves (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 3363-3378 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Anomalously fast ion heating has been observed in the Caltech Encore tokamak [Phys. Rev. Lett. 59, 1436 (1987)], with the use of laser-induced fluorescence. This heating was found to be independent of electron temperature, but was well correlated with the presence of large-amplitude drift-Alfvén waves. Evidence is presented that suggests that the heating is stochastic and occurs when the ion displacement due to polarization drift becomes comparable to the perpendicular wavelength, i.e., when k⊥ (mik⊥ φ0/qB2)∼1. Stochastic heating may also be the cause of the anomalously high ion temperatures observed in reversed-field pinches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859768
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  • 6
    Electronic Resource
    Electronic Resource
    Beneficial effect of granulocyte–colony stimulating factor in scleromyxoedema associated with severe idiopathic neutropenia (1996)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 135 (1996), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary The treatment of scleromyxoedema is notoriously difficult. We present a patient with long-standing diffuse scleromyxoedema associated with functional impairment who developed chronic idiopathic neutropenia complicated by recurrent life-threatening infections. Treatment with recombinant granulocyte-colony stimulating factor led to normalization of the neutrophil count, prevented further systemic infections, and unexpectedly was associated with a striking clinical improvement of her skin disorder and decrease in mucin deposition in the dermis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.1996.d01-1055.x
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  • 7
    Electronic Resource
    Electronic Resource
    H− and D− temperature in volume sources : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2686-2688 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new technique using laser induced photodetachment has been developed for measuring the negative ion temperature in H− and D− sources. Using this technique, we have investigated the dependence of the negative ion temperature on source parameters such as pressure, discharge current, and electron temperature. Simultaneous measurements of negative ion density, temperature, and extracted current lead to the conclusion that the extracted negative ion current is, at most, equal to the thermal flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142823
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  • 8
    Electronic Resource
    Electronic Resource
    ARC Assembly and Continental Collision in the Neoproterozoic East African Orogen: Implications for the Consolidation of Gondwanaland (1994)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Earth and Planetary Sciences 22 (1994), S. 319-351 
    Details
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ea.22.050194.001535
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  • 9
    Electronic Resource
    Electronic Resource
    Simultaneous force measurements in 3 dimensions on oral endosseous implants in vitro and in vivo. A methodological study. (1996)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 7 (1996), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A novel piezo-electric force transducer was developed that is mounted directly on ITI-implants and allows for simultaneous force measurements in 3 dimensions. The reliability of this measuring method in vitro and in vivo was evaluated. For test and calibration measurements 5 edentulous patients with 2 mandibular implants were selected and master casts obtained with original implants in situ. Preload of the abutment screw was measured with a torque controller by repeated tightening and loosening. The introduction of additional preloads when bar connectors or telescopes were mounted was examined on the casts and in the mouth. Tests were carried out to identify the influence of screw tensions on force measurements by loading the implants in vertical and transverse directions. Calibration measurements in vivo and in vitro were carried out by means of a spring balance. A regression model was calculated to analyze the influence of the applied preload on measured forces. The mean preload value was 315, ranging from 200 to 480N. A significant correlation of applied loads to measured forces was found (r=0.99). It was independent of the preload in vertical direction but dependent in transverse direction. No additional tension of the abutment screw was ever observed when bars were mounted. Calibration measurements with the spring balance showed that bars contribute to load sharing between the implants. Comparable results were found for all measurements in vitro and in vivo. It was concluded that the new piezo-electric transducer is an adequate instrument to measure forces in 3 dimensions on ITI-implants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.1996.070412.x
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  • 10
    Electronic Resource
    Electronic Resource
    3-D in vivo force measurements on mandibular implants supporting overdentures. A comparative study. (1996)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 7 (1996), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Force transmission onto implants supporting overdentures was measured in viva by means of piezoelectric transducers that allow for simultaneous force registrations in 3 dimensions. The transducers are directly mounted onto the implants, beneath the anchorage device. The force registrations were analyzed with regard to the anchorage device and retention mechanism of overdenture support. The 3 types of denture anchorage were a U-shaped bar, a round clip-bar and single telescopes. Forces were measured in the following test situations: maximum force when biting in centric occlusion, maximum bite force during biting on a bite plate, grinding and chewing bread. Multiple regression showed that the vertical component of maximum forces was dependent on the anchorage device and test situation. The transverse components reached 10 to 50% of the vertical force magnitude. With the bite plate in situ maximum forces measured in vertical direction were significantly higher on the ipsilateral implant with telescopes than with bars (p〈0.01 and p〈0.001). Chewing and grinding resulted in lower vertical forces compared to maximum biting. In transverse dimensions, mainly in the anterior-posterior direction, registered forces reached magnitudes that resembled the vertical component (50 to 100%). Force magnitudes of chewing and grinding were similar for all three anchorage devices. However, differences were observed between bars and telescopes with regard to the direction of transverse force components. The results of this study do not suggest the preference of one specific anchorage system or retention mechanism for overdenture support. However, rigid bars contribute to load sharing and stress distribution onto the implants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.1996.070413.x
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