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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5128-5131 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The nonrelativistic anharmonic–asymmetrical–oscillator (AAO) is studied in full. The classical equation of motion is solved using Jacobi elliptic functions which have both real and imaginary periods. The imaginary period is connected with the imaginary part of the energy in quantum mechanics. The resonances (Siegert states) are calculated in the JWKB approximation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 2665-2668 
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: Analytic expressions for the transmission coefficient and the emission and the absorption rates for scalar particles with mass and a chargeless, nonrotating black hole are calculated by using Jacobian elliptic functions and integrals in the Jeffreys–Wentzel–Kramers–Brillouin (JWKB) approximation.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 689 (1993), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 35 (1992), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Lymphoid follicles are the main B-cell areas in peripheral lymphoid tissues. These structures commonly consist of germinal centre (GC) and mantle zone (MZ) regions. In the present work, human tonsillar B cells belonging to these two compartments were purified by a combination of density centrifugation and separation techniques involving the recognition by monoclonal antibodies of specific surface molecules followed by panning and magnetic bead selection. These purified populations were identified as GC and MZ cells by three different criteria: (1) GC cells showed the phenotype IgD- CD20+bright CD38+ CD44- and peanut agglutinin (PNA)+, and MZ cells were IgD+ CD20+dim CD38- CD44+ and PNA-; (2) morphologically, MZ cells appeared as small resting lymphocytes whereas GC cells consisted of large blastic cells of the germinal centre; (3) functionally, most GC, but not MZ, cells underwent apoptosis early in culture. The isolation of GC and MZ cells allowed the study of their proliferative response. As a result of these studies, GC cells were demonstrated to inhibit the proliferation of MZ cells in response to B-cell mitogens (Staphylococcus aureus Cowan I and anti-μ plus BCGF) in a concentration-dependent way; 50% inhibition was reached at a GC/MZ cell ratio of 1/2. This effect did not require GC-cell DNA synthesis since similar results were obtained with irradiated GC cells. Neither was it due to a non-specific toxic effect since GC cells did not alter the proliferative response of autologous T cells to mitogens (phytohaemagglutin and anti-CD3). The inhibition required cellular contact between GC and MZ cells, and was not restricted by histocompatibility barriers. These data suggest the possible existence of a new regulatory pathway within peripheral B-cell areas.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— A ductile medium strength steel has been modelled by means of the Gurson model, and been used to investigate the effect of crack tip constraint in several fracture mechanics specimens. Both numerical and experimental results have been obtained, in the course of the crack extension process, for single edge notch bending specimens with different crack length-to-width ratios. The geometries with the shorter cracks always exhibited higher J values at initiation and steeper J crack growth resistance curves, and these results have been explained in terms of the stress and strain fields and damage development in the region ahead of the crack tip.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10809-10817 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Field cycling nuclear magnetic resonance relaxometry was used to study the slow molecular dynamics in the nematics and isotropic phases and polyphasic region of the phase diagram in the thernary mixture: potassium laurate/1-decanol/water. The experiment has been performed over a broad range of Larmor frequencies (2×103−6.6×106 Hz). The first experimental evidence of director fluctuations in a micellar lyotropic nematic liquid crystal, studied by 1H spin-lattice relaxation rate, is reported. The results evidence that in the nematic mesophases, director fluctuations are responsible for the spin-lattice relaxation dispersion in the low Larmor frequency range ((approximately-less-than)105 Hz). By increasing the intermicellar water content, a crossover was found between a quasi-isotropic three-dimensional (3D) director fluctuation behavior and a two-dimensional (2D) pseudo-lamellar undulation fluctuation. In spite of the fact that no menatic phases of this micellar complex fluid are isotropic with respect to light scattering, they present spin-lattice relaxation profiles as driven by local director fluctuations. The polyphasic region, at lower temperatures, shows a quasinematic 3D director fluctuation behavior; meanwhile, the isotropic phase, at higher temperatures, presents 2D pseudo-lamellar undulation fluctuation modes. We conclude that the micelles, in the isotropic phase, preserve the pseudo-lamellar structure, already found in the nematic phases but forming nematic domains with the directors randomly oriented. In order to explain the higher frequency range ((approximately-greater-than)105 Hz), two relaxation mechanisms are assigned: (i) molecular reorientation by translational diffusion on the micellar surface and (ii) molecular exchange between the micelle and the bulk. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The inducible nitrogen oxygen synthase (iNOS) and nitric oxide (NO) system acting in concert with superoxide radicals is recognized as a powerful macrophage microbicidal mechanism. However, experimentation with iNOS knockout mice has rendered contradictory results on the protective role of iNOS/NO in the course of mycobacterial infections. On the other hand, NO also plays an immunoregulatory role. Knowing the nature of the mycobacterial constituents that induce iNOS gene expression would help to better understand the host–parasite relationship.Lipoarabinomannan (LAM) and a 19 KDa lipoprotein are the two known mycobacterial constituents that have shown to induce iNOS. By screening a set of methanol extracted lipids from Mycobacterium microti, here we provide evidence that multiple mycobacterial molecules of lipidic nature both of intermediate and of high polarity, with free amino groups or carbohydrates but no phosphate groups as part of their structure are capable of inducing iNOS gene expression in J774 cells, thus implying a complex relationship between mycobacteria and their host immune system in regard to iNOS gene expression.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 47 (1992), S. 0 
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 9
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The local synaptic connectivity in the superficial gray layer of the superior colliculus (SC) was assessed following retinal ganglion cell axonal regeneration through a peripheral nerve graft into the SC of Lister Hooded rats, using in vitro brain slice techniques. Repair was effected between the ipsilateral eye and SC, following bilateral lesion of optic nerves and ablation of ipsilateral occipital cortex. Deafferentation surgery alone resulted in a complete loss of synaptic potentials of extrinsic origin, once both retinal and cortical inputs were removed. Stimulation of graft insertion sites elicited synaptic responses comprising monosynaptic and network-mediated depolarising events. This activity, together with similar spontaneous bursts of depolarising events and action potential firing, was generated by the activation of non-N-methyl-d-aspartate glutamate receptors. This behaviour may reflect the development of a local recurrent synaptic connectivity following the repair surgery, as both evoked and spontaneous responses developed into large long-lasting bursts of excitatory activity when inhibition mediated by GABA receptors was blocked. These results suggest that the ultrastructural changes in the superficial layers of the SC resulting from deafferentation are reflected functionally at the synaptic level in the target structure even after repair. Such changes are likely to compromise the ability of the target structure to function normally during information processing. Therefore, although axons regenerating along peripheral nerve grafts can make functional synaptic connections, their efficacy in activating the target structure will probably be compromised by local changes in synaptic connectivity.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 25 (1994), S. 0 
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. Two experiments were carried out to study the effect of n-3 HUFA levels in rotifers on survival, growth, activity and fatty acid composition of gilthead bream, Sparus aurata (L.), larvae. From the third to the 15th day after hatching, gilthead bream larvae received one of the three kinds of rotifers containing different percentages of n–3 HUFA. Moisture, crude lipid, saponifiable matter and fatty acid composition of total lipids of rotifers and larvae were determined.A good correlation was found between larval growth and n–3 HUFA levels in rotifers. Larval survival was also significantly improved by the elevation of the n–3 HUFA levels in rotifers. A high occurrence of hydrops was registered in larvae fed with EFA-deficient rotifers. The n–3 HUFA levels in the larvae were increased by the elevation of n–3 HUFA contents in rotifers. However, n–9 fatty acids in the larvae remained almost constant, regardless of the different 18:1n–9 contents in rotifers. Therefore, the ratio of oleic acid to n–3 HUFA, known to be an indicator of the EFA deficiency in fish, was reduced by the elevation of the n–3 HUFA levels in rotifers.
    Materialart: Digitale Medien
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