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  • 11
    Electronic Resource
    Electronic Resource
    Culture of Regulatory T-Cell Lines from Bronchial Mucosa (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Scandinavian journal of immunology 59 (2004), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: T lymphocytes play a major role in many immune responses. In the last decade, special focus has been on the function of Th1 and Th2 effector cells. Now the importance of regulatory CD4+CD25+ T cells in maintenance of the immunological homeostasis emerges. Sarcoidosis is a multisystem granulomatous disorder often affecting the lungs. The typical sarcoid granulomas consists of epitheloid cells, macrophages and lymphocytes, mainly CD4+ T cells of Th1 phenotype. We have cultured T cells from bronchial biopsies of patients with sarcoidosis as well as from controls in high levels of interleukin 2 (IL-2) and IL-4 and demonstrate spontaneously arising CD4+ CD25+ populations and high concentrations of IL-10 in these cultures. The main difference between cultures of sarcoid origin compared to controls is a very much higher concentration of the inflammatory cytokines IL-6 and TNF-α in cultures of sarcoid origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0300-9475.2004.01423z.x
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  • 12
    Electronic Resource
    Electronic Resource
    Buchbesprechungen (1967)
    Springer
    Computing 2 (1967), S. 81-88 
    Details
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02235515
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  • 13
    Electronic Resource
    Electronic Resource
    On the density of localized levels in amorphous silicon (1979)
    Springer
    Applied physics 18 (1979), S. 427-429 
    Details
    ISSN: 1432-0630
    Keywords: 71.20 ; 71.55 ; 72.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The distribution of the localized levelsg(ε) in the forbidden gap of amorphous silicon is calculated from the dependence of the Fermi energy on the doping concentration of phosphorus donors and boron acceptors. The minimum ofg(ε) is verified by this method to be in the order of 1017 to 1018 cm−3eV−1, whereas the maxima ofg(ε), which have been reported in the literature, are not confirmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00899699
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  • 14
    Electronic Resource
    Electronic Resource
    Defect-level analysis of semiconductors by a new differential evaluation ofn(1/T)-characteristics (1979)
    Springer
    Applied physics 19 (1979), S. 307-312 
    Details
    ISSN: 1432-0630
    Keywords: 71.20 ; 71.55 ; 72.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A new method for the defect-level analysis of extrinsic semiconductors is described. Provided that the defect-level concentration is not too large and the temperature is not too low, the Fermi levelE F is shifted with increasing temperature from a position near the conduction (or valence) band towards the middle of the forbidden gap monotonously. Thus majority carriers are emitted into the conduction (or valence) band from the defect levels successively. If for a small increment of the temperature the Fermi levelE F is shifted by ΔE F and the concentration of free majority carriers is increased by Δn, then the ratio Δn/ΔE F is a measure of the defect-level concentration within ΔE F . Furthermore we discuss how this analysis is influenced by additional defect levels outside the range over which the Fermi energy can be shifted by variation of the temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00900474
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  • 15
    Electronic Resource
    Electronic Resource
    Photo-enhanced etching ofn-Si (1984)
    Springer
    Applied physics 33 (1984), S. 243-245 
    Details
    ISSN: 1432-0630
    Keywords: 73.40.Mr ; 82.30.Lp ; 85.30.De ; 85.30.Tv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The etch rate ofn-type Si in diluted HF solutions was investigated as a function of the bias voltage applied to the Si/electrolyte interface in the dark and under illumination. It was observed that the etch rate depends very sensitively on the minority carrier flow through this interface. For an illumination intensity of 5.3×1016 photons/cm2 s (γ=550nm) and the depleted Si/electrolyte interface biased slightly (less than 1 V) in reverse, the etch rate is increased by a factor of more than 1000 as compared to the etch rate under open-circuit condition. This effect can be used to create etch patterns during device processing without prior masking the semiconductors. Using the same effect it should be possible to trim the thickness of Si layers on (semi-) insulating substrates for the fabrication of enhancement-mode FETs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614665
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  • 16
    Electronic Resource
    Electronic Resource
    Determination of localized level energies by a statistics of the fermi-level (1977)
    Springer
    Applied physics 12 (1977), S. 379-381 
    Details
    ISSN: 1432-0630
    Keywords: 71.55 ; 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract For a very large number of samples of a semiconducting material, which is not intentionally doped, the Fermi-level coincides approximately with the respective energy levels of the accidential impurities and defects. Based on this fact, the energies of localized levels were determined from a statistic of the Fermi-level in CdSe platelets. These energies agree very well with most of the values obtained with different methods by other authors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00886040
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  • 17
    Electronic Resource
    Electronic Resource
    Differential evaluation of the Hall effect in silicon with oxygen-related donors (1984)
    Springer
    Applied physics 33 (1984), S. 47-50 
    Details
    ISSN: 1432-0630
    Keywords: 71.55.Fr ; 72.80.Cw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The free-electron concentration as a function of the temperature is analyzed differentially for silicon with oxygen-related donors formed by annealing at 430 °C. The analysis yields defect levels atE c−0.25 eV,E c−0.14eV, andE c−0.055 eV assuming the degeneracy factors to be unity. The corresponding defect level concentrations are approximately proportional to the annealing time. Their formation rates are between 1 and 3×1010cm−3s−1 at 430 °C annealing temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197085
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  • 18
    Electronic Resource
    Electronic Resource
    On the validity of an approximation for the deviation of a light beam. by a prism (2000)
    Springer
    Applied physics 70 (2000), S. 69-71 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 42.15.Gs; 42.79.Bh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. According to many textbooks on optics, the deviation angle of a prism with the apex angle (or prism angle), γ, and the refractive index, n, with respect to the surrounding medium can be approximated by δappr=(n-1)γ, if γ≪π/2 and the angle of incidence α1≪π/2. The validity of this approximation is investigated considering the relative error of the deviation. It is shown that this approximation can be extended to angles of incidence α1=nγ with very fair accuracy and even to larger prism angles γ〈π/4 in the range of angles of incidence near the minimum of deviation depending on the acceptable relative error.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050010
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  • 19
    Electronic Resource
    Electronic Resource
    Theory for the spectral transmittance of Christiansen filters made of glass beads (2000)
    Springer
    Applied physics 70 (2000), S. 853-861 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 78.35.+c; 42.25.Gy; 42.70.Ce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The spectral transmittance of Christiansen filters made of glass beads immersed in an index-matching fluid is described theoretically based on geometrical optics. The glass beads and the immersion fluid are considered to be homogeneous and free of absorption. The diameter is assumed to be the same for all of the beads. Fresnel reflection and prismatic deviation of the incident light are considered to be the dominant losses in transmission experiments. The parameters for these losses can be estimated a priori by a simple model. Losses by Rayleigh scattering and diffraction can be included by additional parameters to fit the experimental spectral extinction curves. For the range of wavelengths sufficiently far from the transmittance maximum the theoretical results of the model predict that the spectral extinction increases sublinearly with the thickness of the filters, the inverse of the diameter of the glass spheres, and the difference of the refractive indices between the glass and the immersion fluid. Due to the total reflection of the glass spheres, if their refractive index is smaller than that of the immersion fluid, an asymmetry of the spectral transmittance curves is observed. Furthermore, the halfwidth of the spectral transmission passband decreases with increasing thickness of the filters and with decreasing average diameter of the beads for given dispersion curves of the refractive indices. The simple theory to describe the spectral transmittance curves of Christiansen filters made of glass beads quantitatively seems to solve a 100-year-old problem in physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050019
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  • 20
    Electronic Resource
    Electronic Resource
    Regulation of plant genes specifically induced in nitrogen-fixing nodules: role of cis-acting elements and trans-acting factors in leghemoglobin gene expression (1989)
    Springer
    Plant molecular biology 13 (1989), S. 319-325 
    Details
    ISSN: 1573-5028
    Keywords: nodulins ; leghmoglobin ; gene regulation ; cis-acting elements ; trans-acting factors ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic alfalfa plants harboring a gene fusion between the soybean leghemoglobin (lbc3) promoter region and the chloramphenicol acetyl transferase (cat) gene were used to determine the influence of rhizobial mutants on lb gene expression in nodules. The promoter region of the Sesbania rostrata glb3 (Srglb3) leghemoglobin gene was examined for the presence of conserved motifs homologous to binding site 1 and 2 of the soybean lbc3 promoter region, found to interact with a trans-acting factor present in soybean nodule nuclear extracts (Jensen EO, Marcker KA, Schell J, de Bruijn FJ, EMBO J 7: 1265–1271, 1988). Subfragments of the S. rostrata glb3 (Srglb3) promoter region were examined for binding to trans-acting factors from nodule nuclear extracts. In addition to the binding sites previously identified (Metz BA, Welters P, Hoffmann HJ, Jensen EO, Schell J, de Bruijn FJ, Mol Gen Genet 214: 181–191), several other sites were found to interact with trans-acting factors. In most cases the same trans-acting factor(s) were shown to be involved. One fragment (202) was found to bind specifically to a different factor (protein) which was extremely heat-resistant (100°C). The appearance of this factor was shown to be developmentally regulated since the expected protein-DNA complexes were first observed around 12 days after infection, concomitant with the production of leghemoglobin proteins. Fragments of the Srglb3 5′ upstream region were fused to the β-glucuronidase reporter gene with its own CAAT and TATA box region or those of the cauliflower mosaic virus 35S and nopaline synthase (nos) promoters. These constructs were used to generate transgenic Lotus corniculatus plants and their expression was measured in different plant tissues. The Srglb3 CAAT and TATA box region was found to be required for nodule-specific expression and several upstream enhancer-type regions were identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025320
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