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  • 1995-1999  (5)
  • 1890-1899
  • 1999  (5)
  • 1
    Digitale Medien
    Digitale Medien
    Drift mode growth rates and associated transport (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 1162-1167 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Drift mode linear growth rates and quasilinear transport are investigated using the FULL kinetic stability code [Rewoldt et al., Phys. Plasmas 5, 1815 (1998)] and a version of the Weiland transport model [Strand et al., Nucl. Fusion 38, 545 (1998)]. It is shown that the drift mode growth rates (as well as the marginal stability temperature gradient) obtained using the FULL code are dependent on the accuracy of the equilibrium employed. In particular, when an approximate equilibrium model is utilized by the FULL code, the results can differ significantly from those obtained using a more accurate numerical equilibrium. Also investigated are the effects of including full electron physics. It is shown, using both the FULL code and the Weiland model, that the nonadiabatic (e.g., trapped) electron response produces a significant increase in the linear growth rate of the ion-temperature-gradient (ITG) driven branch of the drift instability. Other consequences of the nonadiabatic electron response include a reduction in the marginal temperature gradient for the onset of the ITG mode and an additional contribution to transport due to the excitation of the Trapped Electron Mode (TEM). Physical explanations are given for the sensitivity of the mode growth rates to the equilibrium and the nonadiabatic electron response. Finally, linear growth rates for the ITG mode computed using the FULL code are compared with growth rates obtained using the Weiland model. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.873360
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  • 2
    Digitale Medien
    Digitale Medien
    Effect of isotope mass on transport simulations of Joint European Torus high-mode plasmas with Edge Localized Modes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 4607-4614 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The effect of isotopic mass on heat and particle transport in Joint European Torus (JET) [P.-H. Rebut et al., Nucl. Fusion 25, 1011 (1985)] plasma discharges is studied using the Multi-Mode model in the BALDUR predictive transport code [Bateman et al., Phys. Plasmas 5, 1793 (1998)]. Temperature and density profiles from these simulations generally agree with the experimentally measured profiles for high-mode JET discharges with Edge Localized Modes in hydrogen, deuterium, and tritium discharges. It is surprising that a purely gyro-Bohm transport model, used in these simulations, correctly predicts the experimentally observed improvement in confinement as the isotope mass is increased—given the fact that gyro-Bohm diffusion coefficients increase with isotope mass when the shapes of all the plasma profiles are held fixed. However, in the JET experiment, it was found that the electron and ion temperature at the top of the edge pedestal increases systematically as the isotope mass in increased (J. G. Cordey et al., Report No. JET-P (98)53, 1998). The numerical simulations reported here show that this increase in the edge temperatures and subsequent broadening of the temperature profiles account for the improvement in confinement as the isotope mass is increased. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.873724
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  • 3
    Digitale Medien
    Digitale Medien
    Restoration of expression of signal-transduction molecules in lymphocytes from patients with metastatic renal cell cancer after combination immunotherapy (1999)
    Springer
    Cancer immunology immunotherapy 48 (1999), S. 263-269 
    Details
    ISSN: 1432-0851
    Schlagwort(e): Key words Signal transduction ; Lymphocytes ; Immunotherapy ; Renal cell carcinoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A decrease in lymphocyte signal-transduction molecules, described in cancer patients and patients with chronic infectious diseases, has been proposed as a possible mechanism leading to an impaired immune response in cancer patients. Here we report the effects of combination immunotherapy on the levels of T cell receptor ζ chain and p56lck tyrosine kinase in a retrospective study of cryopreserved lymphocytes from 26 metastatic renal cell carcinoma patients treated with high-dose interleukin-2 (IL-2), interferon α(INFα) and ex vivo IL-2-activated lymphocytes. Of the 26 patients, 12 were responders (5 complete and 7 partial) and 14 were non-responders (6 stable and 8 with progressive disease). Prior to treatment, 21 of 26 patients (81%) and 13 of 21 patients (62%) respectively expressed ζ chain and p56lck at less than 50% of the levels observed in healthy controls. During therapy, this low ζ chain and p56lck expression increased to at least 50% of normal in 13 of the 21 patients (62%) and in 6 of the 13 patients (46%) respectively; in the remaining patients expression levels remained at 50% of normal or more, or declined. Although, in this limited study, pretreatment levels of ζ and p56lck did not show significant correlation with antitumor response, 4 of 5 patients that achieved a complete response (80%) corrected bothζ chain and p56lck levels to at least 50% of normal, while restoration of both signal-transduction molecules to such levels was only observed in 3 of 7 partial responders (43%), 1 of 5 patients with stable disease (20%) and 2 of 7 patients with progressive disease (29%). Thus, these results suggest that analysis of changes in signal-transduction molecules may a be useful tool for immunological monitoring of patients throughout immunotherapy, and could provide important information for designing new clinical trials that restore impaired signal transduction while activating T cell responses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002620050574
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  • 4
    Digitale Medien
    Digitale Medien
    Typha control efficiency of a weed-cutting boat in the Lac de Guiers in Senegal: a preliminary study on mowing speed and re-growth capacity (1999)
    Springer
    Hydrobiologia 415 (1999), S. 249-255 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Typha australis ; Senegal River ; Lac de Guiers ; mowing boat ; aquatic weed ; control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Prolific growth of Typha australis in the lower part of the Senegal River and the Lac de Guiers resulted from changed ecological conditions following the construction of two high dams in the Senegal River. Fluctuation of the water level has decreased markedly and the water has changed from brackish to fresh as the inflow of salt water from the ocean is prevented. The efficiency of a hydraulic weed cutting boat (model Conver 480 H) has been tested in various plots in the Lac de Guiers. This lake, connected with the Senegal River, is economically very important as it is the city of Dakar's major drinking water supply and also provides irrigation water for vast agricultural areas. Cutting, performed at 20 cm and 50 cm below the water surface, was very effective in removing Typha stands. However, due to the excessively thick stems of the Typha plants, cutting took much more time compared to similar operations in Europe. It was estimated that approximately 35 h were required to clear one ha of dense Typhastands. Directly after cutting re-growth was observed during a relatively brief period (approximately three months), however, subsequently all newly formed growth tips in the plots had suddenly disappeared. It was concluded that this sudden collapse was linked to a destruction of the root zone due to anoxic conditions. Eventual re-growth was relatively slow as after one year the plots were still largely free from Typha plants. Efficiency of mowing was not related significantly to depth of cutting.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003877201612
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  • 5
    Digitale Medien
    Digitale Medien
    Survival strategy of Pistia stratiotes L. in the Djoudj National Park in Senegal (1999)
    Springer
    Hydrobiologia 415 (1999), S. 21-27 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Pistia stratiotes ; seed formation ; flowering ; habitat factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The water level in the Senegal River is now regulated due to the construction of two high dams (1986 and 1988). In consequence, large parts of the floodplains have permanently dried up and the brackish water in the lower part of the river has become fresh. The Djoudj National Park, situated approximately 60 km upstream from Saint Louis in Senegal in the former floodplain, is artificially flooded when inlets from the river are opened during the rainy season. This change in ecological conditions has led to an annually recurrent, explosive development of the floating aquatic weed Pistia stratiotes L. in the Park during the first half of the dry season. A rapid increase in the salt content of the water in the Park, in the course of the dry season (due to the high salt content of the soils and evaporation), eventually causes massive die back of Pistia. Rapid seed production by Pistia permits it to survive these unfavourable conditions, i.e. high salinity coupled with drought during the second half of the dry season. This applies in particular to an area where the water is fertilised by excreta from a pelican colony. Flowering of Pistiaappears to be markedly enhanced when vegetative reproduction is inhibited by crowding.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003817213753
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