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  • 1995-1999  (7)
  • 1940-1944
  • 1890-1899
  • 1998  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Predictive simulations of tokamak plasmas with a model for ion-temperature-gradient-driven turbulence (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 1369-1379 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A drift wave transport model, recently developed by Ottaviani, Horton and Erba (OHE) [Ottaviani et al., Plasma Phys. Controlled Fusion 39, 1461 (1997)], has been implemented and tested in a time-dependent predictive transport code. This OHE model assumes that anomalous transport is due to turbulence driven by ion temperature gradients and that the fully developed turbulence will extend into linearly stable regions, as described in the reference cited above. A multiplicative elongation factor is introduced in the OHE model and simulations are carried out for 12 discharges from major tokamak experiments, including both L- and H-modes (low- and high-confinement modes) and both circular and elongated discharges. Good agreement is found between the OHE model predictions and experiment. This OHE model is also used to describe the performance of the International Thermonuclear Experimental Reactor (ITER) [Putvinski et al., in Proceedings of the 16th IAEA Fusion Energy Conference, Montréal, Canada, 1996 (International Atomic Energy Agency, Vienna, 1997), Vol. 2, p. 737.] A second version of the OHE model, in which the turbulent transport is not allowed to penetrate into linearly stable regions, has also been implemented and tested. In simulations utilizing this version of the model, the linear stability of the plasma core eliminates the anomalous thermal transport near the magnetic axis, resulting in an increase in the core temperatures to well above the experimental values. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872797
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  • 2
    Electronic Resource
    Electronic Resource
    Predicting temperature and density profiles in tokamaks : The 39th annual meeting of division of plasma physics of APS (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 1793-1799 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A fixed combination of theory-based transport models, called the Multi-Mode Model, is used in the BALDUR [C. E. Singer et al., Comput. Phys. Commun. 49, 275 (1988)] transport simulation code to predict the temperature and density profiles in tokamaks. The choice of the Multi-Mode Model has been guided by the philosophy of using the best transport theories available for the various modes of turbulence that dominate in different parts of the plasma. The Multi-Mode model has been found to provide a better match to temperature and density profiles than any of the other theory-based models currently available. A description and partial derivation of the Multi-Mode Model is presented, together with three new examples of simulations of the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)]. The first simulation shows the strong effect of recycling on the ion temperature profile in TFTR supershot simulations. The second simulation explores the effect of a plasma current ramp—where the plasma energy content changes slowly on the energy confinement time scale. The third simulation shows that the Multi-Mode Model reproduces the experimentally measured profiles when tritium is used as the hydrogenic isotope in L-mode (low confinement mode) plasmas. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872848
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  • 3
    Electronic Resource
    Electronic Resource
    Multi-Mode transport modeling of the International Thermonuclear Experimental Reactor (ITER) (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 2355-2362 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Predictions are made for the performance of the International Thermonuclear Experimental Reactor (ITER) [R. Aymar, V. Chuyanov, M. Huguet, R. Parker, and Y. Shimomura, in Proceedings of the Sixteenth International Atomic Energy Agency Fusion Energy Conference, Montréal, Canada 1996 (International Atomic Energy Agency, Vienna, 1997), Paper IAEA-CN-64/01-1] design using the Multi-Mode model in the time-dependent one- and one-half-dimensional (1-1/2-D) BALDUR [C. E. Singer et al., Comput. Phys. Commun. 49, 275 (1988)] transport code. This model predicts the temperature and density profiles observed in present-day tokamak experiments more closely on the average than other models currently available. Simulations using the Multi-Mode transport model, with its inherent gyro-Bohm scaling, indicate that ITER will ignite, even with edge temperatures as low as 0.25 keV (L-mode, or low-confinement mode, boundary conditions) or with volume averaged density as low as 0.775×1020 m−3 (just below the Greenwald density limit, when Tedge=0.75 keV). The ignition is found to be thermally stable, and the fusion power production is easily controlled by varying plasma density, impurity content, or edge temperatures. The nonequilibrium impurity radiation model used in these simulations predicts that a significant fraction of the fusion power is radiated when conditions are close to marginal ignition. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872909
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  • 4
    Electronic Resource
    Electronic Resource
    Gulf Stream shifts following ENSO events (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 393 (1998), S. 638-638 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Over the past three decades the annual mean latitude of the Gulf Stream off the coast of the United States has been forecastable from the intensity of the North Atlantic Oscillation (NAO), the predictions accounting for more than half the variance. Here we show that much of the unexplained ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/31380
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  • 5
    Electronic Resource
    Electronic Resource
    Preoperative Functional Magnetic Resonance Imaging (fMRI) of the Motor System in Patients with Tumours in the Parietal Lobe (1998)
    Springer
    Acta neurochirurgica 140 (1998), S. 1223-1229 
    Details
    ISSN: 0942-0940
    Keywords: Keywords: Functional magnetic resonance imaging; fMRI; sensorimotor cortex; brain tumour.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Intracranial lesions may compromise structures critical for motor performance, and mapping of the cortex, especially of the motor hand area, is important to reduce postoperative morbidity. We investigated nine patients with parietal lobe tumours and used functional MRI sensitized to changes in blood oxygenation to define the different motor areas, especially the primary sensorimotor cortex, in relation to the localization of the tumour. Activation was determined by pixel-by-pixel correlation of the signal intensity time course with a reference waveform equivalent to the stimulus protocol. All subjects showed significant activation of the primary sensorimotor cortex while performing a finger opposition task with the affected and unaffected side. In five patients the finger opposition task additionally activated the ipsilateral sensorimotor cortex and the supplementary motor area (SMA). Extension and flexion of the foot, additionally performed in two patients, also activated the sensorimotor cortex, in one case within the perifocal oedema of the tumour. Tumour localization near the central sulcus induced displacement of the sensorimotor cortex as compared to the unaffected side in all patients with a relevant mass effect. The results of our study demonstrate that functional MRI at 1.5 T with a clinically used tomograph can reproducibly localize critical brain regions in patients with intracranial lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007010050242
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  • 6
    Electronic Resource
    Electronic Resource
    Support Networks of Gay Male and Lesbian Youth (1998)
    Springer
    International journal of sexuality and gender studies 3 (1998), S. 27-46 
    Details
    ISSN: 1573-8167
    Keywords: gay ; lesbian ; youth ; support networks ; urban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Sociology
    Notes: Abstract The support networks of 90 self-identified urban gay male and lesbian youth (ages 14 to 21 years) are examined. The youth, who are predominantly black and Latino/a, indicated an average of eight persons in their support networks, most of whom were close friends. Other significant groups included were parents, siblings, other relatives, and lovers or partners. A large majority of the support network members knew that the youth were gay or lesbian. Youth were moderately to very satisfied with the support they received from the network members—being more satisfied with the support provided by those who knew of their homosexuality compared to those who suspected or were unaware. Nonetheless, most youth felt that they did not have enough friends, and that they often to seldom felt lonely. These two feelings correlated positively with suicide ideation and attempts; and feeling lonely also correlated positively with drug use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026252124173
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  • 7
    Electronic Resource
    Electronic Resource
    Nonradioactive Northern blotting with biotinylated and digoxigenin-labeled RNA probes (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1351-1355 
    Details
    ISSN: 0173-0835
    Keywords: Stripping ; Chemiluminescence ; Alkaline phosphatase ; Nonradioactive blotting ; Peroxidase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The application of nonradioactive RNA probes for Northern blotting offers the advantage of a rapid turn-around time for results without the loss of sensitivity for target mRNA detection. However, a problem that has impeded the widespread use of nonradioactive RNA probes for use in Northern blotting is the difficulty in stripping these probes from nylon membranes after hybridization. In this report we describe two protocols for stripping digoxigenin (Dig)-labeled RNA probes from nylon membranes. One protocol utilizes a phosphate-buffered formamide stripping solution to remove nonchemically modified (regular) RNA probes while the other method utilizes strippable probes that were produced with a chemically modified nucleotide (CTP) and removed by a specific stripping solution. This latter method was developed by Ambion Inc. and is called Strip-EZ™. We also describe a protocol for the detection of two separate rat mRNAs using both biotin and digoxigenin-labeled RNA probes that does not require stripping the membrane after hybridization. Finally, we describe the use of another new labeling technology, called ChemLink™, that quickly and conveniently labels RNA for use in Northern blotting.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190825
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