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  • Artikel: DFG Deutsche Nationallizenzen  (64)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 1410-1422 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Characterization of the plasma density and temperature at the last closed flux surface (the separatrix) of a tokamak requires accurate knowledge of the location of the separatrix. In this paper we discuss the effect of inaccuracy in the separatrix location on the measured parameters in DIII-D [Luxon et al., International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1986), p. 159] An uncertainty in the separatrix position of ±0.5 cm, as expected in this device using magnetic reconstruction to determine the location of the separatrix, leads to unacceptably large uncertainty in the plasma parameters. Several techniques to improve the accuracy obtained from magnetic reconstruction are discussed. A new technique that is based on a characterization of the electron temperature profile is proposed. A comparison of the separatrix location defined in this manner with that obtained using magnetic reconstruction techniques suggests a systematic error in the reconstruction when the plasma is far from the walls and magnetic diagnostics. Determination of the perpendicular transport coefficients is given as an example of the improved statistics obtained using the new technique of defining the separatrix position.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 5140-5150 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Particle losses associated with edge localized mode (ELM) activity on the DIII-D tokamak [J. Luxon et al., Proceedings of the 11th International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1986, Vol. I, p. 159] are evaluated quantitatively using density profile data obtained from a Thomson scattering system. It is shown that up to 10% of the total core particle content is lost with each ELM. The particle loss varies inversely with ELM frequency. The temporally averaged ELM particle loss is shown to be about 25% of the total particle loss from the confined region under a wide variety of plasma conditions. Although this ELM loss is a small fraction of the total ion flux, it is large compared to the particle input from neutral beam heating. Hence ELM particle losses are sufficient to control the density rise associated with H-mode plasma operation with neutral beam heating. In addition to controlling the average density by enhancing the total ion flow, albeit only by 25%, it is posited that the ELMs play a role in determining the density profile in the H-mode pedestal region. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1880-1882 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Over the past three years, the total TMX-U diagnostic data base has grown to exceed 10 Mbytes from over 1300 channels; roughly triple the originally designed size. This acquisition and processing load has resulted in an experiment repetition rate exceeding 10 min per shot using the five original Hewlett–Packard HP-1000 computers with their shared disks. Our new diagnostics tend to be multichannel instruments, which, in our environment, can be more easily managed using local computers. For this purpose, we are using HP series 9000 computers for instrument control, data acquisition, and analysis. Fourteen such systems are operational with processed format output exchanged via a shared resource manager. We are presently implementing the necessary hardware and software changes to create a local area network allowing us to combine the data from these systems with our main data archive. The expansion of our diagnostic system using the parallel acquisition and processing concept allows us to increase our data base with a minimum of impact on the experimental repetition rate.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3277-3279 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: For the MTX experiment, we use a network of computers for plasma diagnostic data acquisition and analysis. This multivendor network employs VMS, UNIX, and BASIC based computers connected in a local area Ethernet network. Some of the data is acquired directly into a VAX/VMS computer cluster over a fiber-optic serial CAMAC highway. Several HP-Unix workstations and HP-BASIC instrument control computers acquire and analyze data for the more data intensive or specialized diagnostics. The VAX/VMS system is used for global analysis of the data and serves as the central data archiving and retrieval manager. Shot synchronization and control of data flow are implemented by task-to-task message passing using our interprocess communication system. The system has been in operation during our initial MTX tokamak and FEL experiments; it has operated reliably with data rates typically in the range of 5 Mbytes/shot without limiting the experimental shot rate.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In the microwave tokamak experiment (MTX) program, we are concentrating on experiments using intense, free-electron laser (FEL) generated microwave pulses. In initial FEL experiments, several diagnostic instruments were operated during injection of microwave pulses with peak powers to 0.2 GW at durations of 10 ns. Fixed and spatially scanning microwave detectors and receivers and a 48-element calorimeter on the inside wall of MTX diagnosed the GW-level FEL microwave pulses. With these diagnostics, linear-wave absorption and efficiencies of transmission through the quasi-optical transport system were studied. In addition, several radially resolved measurements of plasma density, temperature, and emission were made during FEL injection and were used in the analysis of microwave absorption data. A timing system, slaved to the FEL pulse arrival time, is capable of accuracy to a few nanoseconds in order to allow measurement of heating effects on the time scale of a single FEL pulse.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Recent studies performed in Seattle, USA have suggested that pretransplant assignment of high or low donor alloreactivity may predict acute graft-versus-host disease (aGvHD) after allogeneic HLA identical marrow transplantation for acute leukaemia. The effect of such pretrunsplant assignment was studied in a Scandinavian population of 114 consecutive transplantations for acute and chronic leukaemias in 1st remission (n= 74) or chronic phase (n= 40) performed between 1975 and 1989.The selected cut-off value for discriminating between donors of high and low responding capacity (DRC) was based on distribution plots of results from the pretransplant mixed lymphocyte culture (MLC) and chosen as the median value (80% normalized response). Then 57 donors were assigned with high DRC and 57 donors assigned with low DRC. Kaplan-Meier estimates of the probability of patients to develop Grade M or higher aGvHD in receipt of high or low responder donor transplants were compared by univariant analysis. The patients in first remission or chronic phase transplanted with bone marrow from donors assigned as high or low responders had a 36.1% and 10.6% risk for aGvHD, respectively, a difference found to be significant by log rank test (chi-squared = 10.1, d.f.= 1, P= 0.0015).Subsequent studies of the cellular and humoral requirements for this predictive response of donor cells, by blocking with cytokine specific antibodies, addition of excess of recombinant human cytokines and scanning of lymphocyte subsets during the response, showed that the response against pool cells mostly depended upon IL-2 responding cells with the phenotype CD3+, CD4+, CD8-, CD25+, CD16-.It is concluded that prospective studies of alloreactivity as a risk factor should be performed to confirm the above findings,
    Materialart: Digitale Medien
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  • 7
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Two monoclonal antibodies, anti-CD45RA and anti-CD29, reciprocally divide the CD4+ and CD8+ lymphocytes into CD4+ CD45RA+, CD4+ CD29+, CD8+ CD45RA+ and CD8+ CD29+ subsets. The CD4+ CD45RA+, CD4+ CD29+ and CD8+ CD45RA+ possess suppressor-inducer, helper-inducer and suppressor-effector functions respectively. Since the role of these subsets has not been established after allogeneic bone marrow transplantation we studied lymphocyte subpopulations in 12 patients 45- 227 days after the procedure.The fraction of CD4+ lymphocytes was significantly (P= 0.0005) decreased to 20±9% versus 43±3% in controls. Within the CD4+ compartment, we found an increase in the fraction of CD4+ cells that co-expressed CD29 (CD29+/CD4+) to 92±10% versus 48±15% (P=0.008) in controls and a concommittant decrease m CD45RA+/CD4+ to 16±12% versus 56±25% (P=0.008)Patients were also noted to have an increase in the percentage of CD8+ lymphocytes to 41±5% compared to 23±4% in controls (P=0.0004), Examination of the CD8+ subsets revealed a significant increase in the CD29+/CD8+ fraction to 97±3% versus 64±2% in controls (P= 0.008) and a decrease in the CD45RA+/CD8+ fraction to 36±11% versus 70±21% (P= 0.008).The number of cells co-expressing CD57 were also determined within the CD4+ and CD8+ subsets. In patients CD57+/CD4+ were increased to 29±7% versus 1±1% in controls (P=0.04), and CD57+/CD8+ to 49±12% versus 23±9% (P=0.02).Since CD29+ and CD57+ cells have a poor capability for IL-2 production and proliferation this shift in subset distribution may account for some of the defects in cellular immunity seen within the first year after allogeneic bone marrow transplantation.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 29 (1989), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: An effective method for specific depletion of mature T lymphocytes from human bone marrow mononuclear cells (BMMC) with preservation of prethymic T cells and natural killer (NK) cells is presented. The BMMC were incubated with F101.01, a monoclonal antibody recognizing an epitope of the T-cell receptor CD3 complex, and subsequently with immunomagnetic beads. Flow cytometric analysis demonstrated that mature T cells were efficiently depleted and that NK cells and prethymic T cells were preserved in the BMMC. Furthermore, T cell-mediated immune reaction as measured by thymidine incorporation after stimulation with phytohaemagglutinin was abolished, whereas NK activity as measured by 51Cr release using K562 as target cells was preserved. Recovery of colony-forming units of granulocyte macrophages was 60–70%.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 28 (2005), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Forty strains of Flavobacterium psychrophilum were tested for the production of siderophores using the universal Chrome Azurol S (CAS) assay. The majority of the strains (85%) were CAS positive (CAS+) and some (15%) were CAS negative (CAS−). The cryptic plasmid pCP1 was carried by all positive strains and was lacking from negative strains. While a weak catechol reaction was detectable in CAS+ culture supernatants, the CAS reaction was, to some extent, heat sensitive, questioning whether the positive reaction was caused only by siderophores. The ability to grow in vitro under iron-restricted conditions did not correlate with the CAS reactivity, as growth of both CAS+ and CAS− strains was similarly impaired under iron restriction induced by 2,2 dipyridyl. Suppressed growth under these conditions was restored by addition of FeCl3, haemoglobin and transferrin for both CAS+ and CAS− strains.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of fish diseases 28 (2005), S. 0 
    ISSN: 1365-2761
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The occurrence of Flavobacterium psychrophilum at four rainbow trout hatcheries was investigated to provide more knowledge about the reservoirs and transmission of this bacterium. Broodstock were sampled at stripping (including both unfertilized and fertilized eggs), and the offspring were then sampled at the eyed egg and fry stages. Water and surface samples (e.g. hatchery trays) were also sampled. Flavobacterium psychrophilum was found in ovarian fluid and milt, indicating that broodstock may serve as a reservoir and are latent carriers of the pathogen. Flavobacterium psychrophilum was not found on or inside eggs, but further egg studies will be necessary to elucidate the possibility of vertical transmission of the pathogen. Flavobacterium psychrophilum was isolated from water samples, but only from water that had been in close contact with farmed rainbow trout or eggs. Flavobacterium psychrophilum isolates were characterized and compared with well-characterized strains, using degradation of elastin, serotype and ribotype profiles. Different ribotypes of F. psychrophilum were found between hatcheries, but a common ribotype A was found at all four hatcheries. Different ribotypes were found in broodstock without clinical disease, whereas only a few ribotypes (mostly ribotype A) were found in diseased fry. The same ribotype A was found in broodstock, in water samples from hatchery trays and in fry, which suggests the possibility of transmission of F. psychrophilum between broodstock and offspring.
    Materialart: Digitale Medien
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