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  • 1
    ISSN: 1432-0533
    Keywords: Experimental allergic encephalomyelitis ; Demyelination ; Cyclosporin A ; Lewis rat ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Chronic relapsing experimental allergic encephalomyelitis was induced in Lewis rats by inoculation with guinea-pig spinal cord and complete Freund's adjuvant followed by treatment with low-dose cyclosporin A. In most animals, tail and limb weakness developed in a relapsing remitting pattern but in some these signs were persistent or progressive from onset. Histological studies during the early stages of clinically active disease (〈 25 days after inoculation) revealed inflammation and primary demyelination in the central nervous system (CNS), particularly the spinal cord, and in the peripheral nervous system (PNS), specifically the ventral and dorsal roots and dorsal root ganglia. Animals studied in the later stages of clinically active disease (〉 28 days after inoculation) had extensive spinal cord demyelination but minimal PNS demyelination. In these animals, large plaques of demyelination with gliosis and prominent plasma cells occurred particularly in the thoracic spinal cord, and lesions of different ages were present within the spinal cord. CNS and PNS remyelination by oligodendrocytes and Schwann cells, respectively, was present in all animals studied later than 18 days after inoculation (the time of the first remission, if it occurred). In both early and late clinically active disease electron microscopy revealed macrophages invading and destroying CNS myelin sheaths. Active demyelination was sometimes found in regions of CNS remyelination, suggesting that remyelinated fibres were being attacked. Axonal degeneration occurred in the spinal cord. During clinical remission there was CNS and PNS remyelination and much less inflammation; however, active demyelination still occurred to a limited degree.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0888-7543
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0888-7543
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    The @Journal of Supercritical Fluids 4 (1991), S. 40-46 
    ISSN: 0896-8446
    Keywords: carbon dioxide ; extraction ; supercritical fluid ; vanilla ; vanillin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In gyro-devices, a nonlinear output taper is often employed as the transition from the near cutoff radius of the interaction circuit to a much larger output waveguide. The tapers are usually designed to avoid passive mode conversion, and thus do not consider the effect of a bunched beam. However, recent simulations with the self-consistent MAGY code [Botton et al., IEEE Trans. Plasma Sci. 26, 882 (1998)] indicate that higher order mode interactions with the bunched electron beam can substantially compromise the mode purity of the rf output. The interaction in the taper region is traveling wave in nature, and is strongly dependent on the residual beam bunching characteristics resulting from the upstream operating mode interaction. An experiment has been performed to quantify the rf output mode content from a Ka-band gyroklystron. The agreement between salient theoretical and measured rf output characteristics confirms the existence of higher order mode excitation in output tapers as predicted by theory. © 2001 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)
    Physics of Plasmas 6 (1999), S. 4405-4409 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The experimental demonstration of a high average power W-band (75–110 GHz) gyroklystron amplifier is reported. The gyroklystron has produced 118 AW peak output power and 29.5% electronic efficiency in the TE011 mode using a 66.7 kV, 6 A electron beam at 0.2% rf duty factor. At this operating point, the instantaneous full width at half-maximum (FWHM) bandwidth is 600 MHz. At 11% rf duty factor, the gyroklystron has produced up to 10.1 kW average power at 33% electronic efficiency with a 66 kV, 4.15 A electron beam. This represents world record performance for an amplifier at this frequency. At the 10.1 kW average power operating point, the FWHM bandwidth is 420 MHz. At higher magnetic fields and lower beam voltages, larger bandwidths can be achieved at the expense of peak and average output power. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 26 (1996), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background The very low concentrations of IgE antibodies in serum tnake investigations of the affinity of allergen-specific antibodies extremely difficult. In the absence of such studies, the fact that low IgE concentrations are capable of inducing powerful effector function has encouraged the view that IgE antibodies are typically high affinity antibodies. Yet the phenomenon of allergic cross-reactivity suggests that lower affinity IgE antibodies may sometitnes be of clinical significance.Objectives To investigate the effect of antibody affinity upon mast cell sensitivity in an in vitro model.Methods Rat basophil leukaemia (RBL) cells were sensitized with one of three monoclonal IgE antibodies which bind to trinitrophenyiated proteins with varying affinity. Serotonin release was measured after challenge of sensitized cells with trinitrophenyiated human serum albumin (TNP-HSA).Results Low valency TNP3-HSA failed to stimulate degranulation of RBL cells sensitized with SPE-7 anti-DNP IgE, which binds TNP with low affinity. However, upon challenge with high concentrations (1250 ng/mL) of TNP8-HSA, or as little as 10 ng/mL of highly substituted TNP23-HSA, low levels of degranulation were seen. A similar relationship between antigen valency and cell sensitivity was seen with cells sensitized with the H-le-DNP anti-DNP IgE. which binds with moderate affinity to TNP proteins.Conclusion High valency antigen is capable of activating RBL cells sensitized with low affinity antibody. This has important implications for our understanding of allergic sensitization. It also suggests that the long-rccognized relationship between antigen valency and RBL cell sensitivity may partly reflect the high functional affinity of cell-bound IgE when directed against multivalent antigen.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2224-2232 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe methods for automating the control and tracking of states within or near a chaotic attractor. The methods are applied in a simulation using a recently developed model of thermal pulse combustion as the dynamical system. The controlled state is automatically tracked while a parameter is slowly changed well beyond the usual flame-out point where the chaotic attractor ceases to exist because of boundary crisis. A learning strategy based on simple neural networks is applied to map-based proportional feedback control algorithms both with and without a recursive term. Adaptive recursive proportional feedback is found to track farther beyond the crisis (flame-out) boundary than does the adaptive non-recursive map-based control. We also found that a continuous-time feedback proportional to the derivative of a system variable will stabilize and track an unstable fixed point near the chaotic attractor. The positive results suggest that a pulse combustor, and other nonlinear systems, may be suitably controlled to reduce undesirable cyclic variability and extend their useful operating range. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3244-3249 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experiment demonstrating the production of a "radius-tailored beam,'' which has a larger head and smaller tail for more stable propagation through gas, using a fast rise-time focusing coil is described. The results and their analyses for the radius-tailored case, the untailored case, and the "reverse-tailored'' case are presented. A two-dimensional particle simulation of the experiment was performed for each case using the parameters of the experiment for the inputs and it produces results consistent with the experiment.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of high power, high efficiency Ka-band and W-band gyroklystron experiments has been conducted recently at the Naval Research Laboratory (NRL). Stagger tuning of the cavities for bandwidth enhancement is commonly used in the conventional multicavity klystrons. The desired stagger tuning is usually achieved via mechanical tuning of the individual cavities. However, in the millimeter wave regime, particularly, in the case of the high average power operation, it is desirable to be able to achieve the required stagger tuning by design. The NRL gyroklystron experiments explored the tradeoffs between power, bandwidth, efficiency, and gain to study the effects of large stagger tuning in millimeter wave without resorting to mechanical tuning of the cavities. Both, Ka-band and W-band, experiments demonstrated a record power-bandwidth product. The success of the experiments was due in large part to a battery of improved large-signal, stability, and cold test codes employed in the modeling and design stage. Theoretical models that provide the basis for these design simulation tools and the design methodology will be presented. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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