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  • 1
    Electronic Resource
    Electronic Resource
    Uptake of exogenous protein by supraependymal cells of the feline area postrema (1979)
    Springer
    Cellular and molecular life sciences 35 (1979), S. 539-541 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Supraependymal cells occurring on the surface of the feline area postrema were examined for phagocytic ability. It was shown that they could ingest exogenous horseradish peroxidase that was experimentally introduced into the brain ventricular system. The cells thus bear functional as well as ultrastructural attributes of macrophages, similar to those found in the third ventricle and subarachnoid space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01922757
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution of calmodulin protein and mRNA in growing pollen tubes (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 131-139 
    Details
    ISSN: 1432-2145
    Keywords: Key words Calmodulin ; mRNA ; Calcium ; Pollen tube ; Agapanthus umbellatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Pollen tube growth is a vital process for angiosperm fertilisation and is dependent on the presence of a tip-focused gradient of cytosolic free calcium ([Ca2+]c). In order to clarify some of the target molecules which convey the Ca2+ signal information, we investigated calmodulin distribution during tube growth. Fluorescently labelled calmodulin was pressure microinjected into pollen tubes and its distribution monitored by confocal microscopy. Calmodulin distributes evenly throughout the cell, but some of its binding sites form a V-shaped collar behind the apical region. This specific association dissipates upon growth arrest, and suggests an interaction of calmodulin with cytoskeletal-bound target proteins. The distribution of calmodulin mRNA was also analysed by microinjection of fluorescently labelled mRNA. No specific pattern was observed, with an even localisation in the body of tube and a lower concentration in the cell apex. Studies with localised application of inhibitors/activators indicate that calmodulin plays a crucial role in tip elongation but does not direct tube orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050130
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  • 3
    Electronic Resource
    Electronic Resource
    A numerical technique for solving the scalar wave equation for Gaussian and smoothed-out profiles (1981)
    Springer
    Optical and quantum electronics 13 (1981), S. 217-224 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A numerical technique, based on transforming the scalar wave equation to a finite interval before discretization is applied, is proposed for the solution of the scalar wave equation defining the modal fields and propagation constants of optical fibres. It is used to compute the propagation constants and modal fields of weakly guiding fibres of circular cross-section when the refractive index profile has a Gaussian or smoothed-out form. The smoothed-out profiles are studied because they vary continuously from the Gaussian to the step profile. Results are compared with and shown to be accurately approximated by simply explicit functions, dependent only on the fibre parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00620324
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  • 4
    Electronic Resource
    Electronic Resource
    Second-mode cutoff in rectangular-core couplers using the Fourier decomposition method (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 987-994 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract By transforming the infinitex-y plane onto the unit square and using two-dimensional Fourier series expansions, the modal fields and propagation constants of dielectric waveguides can be accurately determined within the scalar (weak-guidance) regime. In particular, the method gives cutoffV-values directly. By applying the technique to symmetric and asymmetric rectangular-core couplers, the second-mode cutoffV-value is determined numerically as a function of both the centre-to-centre core separation and the core aspect ratios. Approximate analytical expressions are derived from the exact numerical data which give the cutoff values to within 2.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558490
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis and design of highly broad-band, planar evanescent couplers (1996)
    Springer
    Optical and quantum electronics 28 (1996), S. 71-81 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract It is shown that by taking advantage of the maximum in the spectral dependence of the coupling coefficient, very broad-band symmetric and asymmetric single-mode planar couplers can be designed. The symmetric coupler allows at least 95.6% coupling between the two cores over the wavelength range 1.3–1.58 μm, while the asymmetric coupler can act as a 3 dB splitter with only ±1.6% variation in the splitting ratio over the wavelength range 1.3–1.67 μm. In both cases, the design includes the curved input-output arms, and the estimated bend loss is approximately 0.1 dB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00578552
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  • 6
    Electronic Resource
    Electronic Resource
    Multimode planar devices (1999)
    Springer
    Optical and quantum electronics 31 (1999), S. 307-326 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We derive simple analytical expressions, using geometric optics, to describe the power output characteristics of various multimode devices, including acute angle X-junctions, symmetric Y-junctions and multimode interference couplers. The ray-tracing results compare well with results obtained using a finite difference beam propagation method solution of the governing scalar wave equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006971108806
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  • 7
    Electronic Resource
    Electronic Resource
    Limitations in the perturbation analysis of bent finite-clad fibres and waveguides (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 15-33 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The transverse shift in the field distribution and the correction to the propagation constant of the fundamental and symmetric cladding modes on bent finite-clad single-mode fibres and slab waveguides are evaluated from perturbation theory for effective index values extending below the cladding index. Analytical results are derived in both geometries for the step-profile that are valid within the overall limitations of the theory. However, it is found that, for the fibre geometry only, the method breaks down at certain discrete wavelengths because of degeneracies that occur between the HE12 (LP02) and TE01 (LP11) mode propagation constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431030
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  • 8
    Electronic Resource
    Electronic Resource
    Asymmetric multimode Y-junction splitters (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 379-392 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The wavelength-independent, non-reciprocal splitting properties of the asymmetric, multimode Y-junction make it an ideal device for use as a low-loss, low-power tap in a concatenated linear bus. The properties of a two-dimensional slab model of the junction are investigated and the results of ray-tracing, modal and numerical beam propagation method (BPM) techniques are compared. Minimization of splicing loss between the ports of a square-core, three-dimensional buried channel waveguide version of the device and a multimode fibre is also addressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018582912154
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  • 9
    Electronic Resource
    Electronic Resource
    Efficient coupling of a laser to a waveguide using a taper designed by conformal mapping (2000)
    Springer
    Optical and quantum electronics 32 (2000), S. 197-208 
    Details
    ISSN: 1572-817X
    Keywords: lasers ; pigtailing ; waveguides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Maximising the optical power collected in a waveguide from the diffracting field of a semiconductor laser is desirable in optical fibre communication systems. However, the spot size and phase front curvature of the laser field usually makes a poor overlap with the mode of the receiving waveguide. Various proposals have been made to improve this coupling. This paper presents the design of a tapered waveguide section, having the correct geometry and refractive index profile, to efficiently capture and transform the rapidly diffracting light from a semiconductor laser to a planar wavefront in a straight waveguide. Experimentally, such an approach requires the refining of available techniques (UV exposure, ion implantation or diffusion) to obtain the required grading of the refractive index profile within the tapered input section of the receiving waveguide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007080925215
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  • 10
    Electronic Resource
    Electronic Resource
    Report on The International Workshop on Optical Waveguide Theory, 21–23 September, 1976, Lannion, France (1977)
    Springer
    Optical and quantum electronics 9 (1977), S. 84-86 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619889
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