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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 37 (1989), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A new approximate method to calculate the space-time acoustic wave motion generated by an impulsive point source in a horizontally layered configuration is presented. The configuration consists of a stack of fluid layers between two acoustic half-spaces where the source and the receiver are located in the upper half-space. A distorted-wave Born approximation is introduced; the important feature of the method is the assumption of a background medium with vertical varying root-mean-square acoustic wave speed. A closed-form expression for the scattered field in space and time as a function of the contrast parameters is deduced. The result agrees closely with rigorously calculated synthetic seismograms. In the inverse scheme the wave speed and mass density can be reconstructed within a single trace. Results of the inversion scheme applied to synthetic data are shown.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 10633-10639 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The holographic properties of the photorefractive polymer composite PSX:DMNPAA:TNF are determined as a function of the grating spacing by use of two-beam coupling and degenerate four-wave mixing measurements. The phase shift was quantified with the grating translation technique. In particular, an almost constant mean drift length of the charge carriers of about 0.5 μm was obtained. The resulting discrepancies between the standard theory of crystals, which is generally used as an approximation for amorphous organic materials, and the experimental data are discussed and attributed to the different mechanisms of charge transport in amorphous organic materials. To verify our conclusions we performed time-of-flight and degenerate four-wave mixing measurements on the two photorefractive organic glasses DRDCTA:DOP:C60 and DRDCTA:EHMPA:C60, which differ in the degree of dispersivity of charge carrier transport and, hence, the involved trap energy distributions. Comparing the behavior of the two materials under investigation, we obtained a qualitative relationship between dispersivity and a theoretically unexpected drop in the diffraction efficiency: The larger the dispersivity the earlier the drop in the efficiency. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Influences of microbial pathogens are crucial for the maturation of the immune system. Caspase-recruitment domain containing protein 15 (CARD15) is a cytosolic receptor involved in bacterial recognition by antigen-presenting cells. CARD15 polymorphisms have been associated with Crohn's disease. Recently, associations with atopic phenotypes have been reported in children.Objective Within a large population of German adults (n=1875), we evaluated eight CARD15 polymorphisms for associations with atopic phenotypes.Methods Subjects were phenotyped by standardized questionnaires and interviews as well as total and allergen-specific IgE measurements. Genotyping was performed using matrix-assisted laser desorption ionization – time of flight mass spectrometry. Haplotypes were estimated using the SAS/Genetics module.Results Subjects with a T allele at rs1077861 had a decreased risk of developing asthma (odds ratio OR=0.648, P=0.013), whereas the presence of an A allele at rs3135500 was significantly associated with an increased risk (OR=1.374, P=0.023). In addition, a CARD15 haplotype revealed to be protective against the development of asthma (OR=0.326, P=0.003). Subjects with an A allele at position rs5743266 or a T allele at rs2066842 had a significantly decreased risk of developing allergic rhinoconjunctivitis with ORs of 0.820 (P=0.049) and 0.801 (P=0.025). Polymorphism rs2066845 showed a significant association with increased total serum IgE (OR=2.155, P=0.006).Conclusion Genetic variants of CARD15 that might result in inappropriate immunomodulation are not only associated with autoimmune diseases but also with atopic disorders.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Atopic disorders are the result of complex interactions between genetic and environmental factors. Associations analyses between the promoter polymorphism rs1800875 in the mast cell chymase gene (CMA1) and atopy-related phenotypes have yielded inconsistent results.Methods:  We sequenced the CMA1 locus in 24 unrelated healthy individuals with serum IgE levels 〈50% percentile and 24 individuals with atopic eczema and serum IgE levels 〉90% percentile. Seven CMA1 single nucleotide polymorphisms (SNPs) were evaluated for evidence of associations with atopic phenotypes within a large population of German adults (n = 1875). Subjects were phenotyped by standardized questionnaires and interviews, skin prick testing and serum IgE measurements. Genotyping was performed using MALDI-TOF MS (Matrix-Assisted Laser Desorption Ionization–Time of Flight mass spectrometry).Results:  Promoter polymorphism rs1800875 was significantly associated with atopic eczema. No associations between any other single SNP and atopic phenotypes could be detected. Haplotype reconstruction revealed four of 128 possible haplotypes reaching estimated frequencies of 3% or more. Two of these haplotypes showed a borderline-significant association with atopic eczema, which did not remain significant after correction for multiple testing.Conclusions:  Results confirm previous observations of a significant association between the CMA1 promoter polymorphism rs1800875 and atopic eczema, but not with serum IgE levels, and support the hypothesis that CMA1 serves as candidate gene for atopic eczema.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 132 (1995), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It has been suggested that in atopic eczema (AE) a reduced lymphocyte response to T-cell mitogens in vitro is secondary to altered production of cytokines or inflammatory mediators. We investigated, in parallel, the mitogen-induced T-cell proliferation, monocyte interleukin-1ß (IL-1ß) production, and prostaglandin E2 (PGE2) production of monocytes and of peripheral blood mononuclear cells (PBMC) in AE patients and non-atopic controls. After stimulation with concanavalin A (Con A) PBMC of AE patients showed a significantly reduced proliferative response compared with the controls. The monocyte production of IL-1ß after stimulation with lipopolysaccharide (LPS) was significantly decreased in AE. No differences between AE patients and controls were observed with regard to the PGE2 production of PBMC after stimulation with Con A or the monocyte release of PGE2 after LPS stimulation. Because IL-1 plays a central role in the activation of T-cell proliferation, the decreased monocyte IL-1ß production may provide a plausible explanation for the reduced mitogen response of T cells in AE.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 283 (1991), S. 5-6 
    ISSN: 1432-069X
    Keywords: Eosinophil cationic protein ; Atopic eczema ; IgE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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