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  • Cell & Developmental Biology  (20)
  • Humans  (9)
  • Phrenic nerve  (9)
  • 42.10  (6)
  • 1
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The validity of 2-D coupled-wave theory is investigated for the case of Bragg diffraction of a Gaussian beam by a thick unslanted phase grating in transmission mode. Fourier plane wave decomposition theory, as presented in a companion article, is used to test 2-D coupled-wave theory under circumstances when its validity is in question, namely when the incident distribution is very narrow or fast-varying, or when the parameterv o, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large. Numerical evaluations of the field patterns at output from the grating, obtained using plane-wave decomposition, are used to explore the effect of the gradual violation of the conditions (from the previous article) under which 2-D coupled-wave theory is valid.
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  • 2
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    Electronic Resource
    Springer
    Applied physics 26 (1981), S. 37-42 
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82 ; 42.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Novel thick grating focussing and de-focussing devices are described which employ uniform phase gratings with special boundary shapes. The analysis used is based upon an eigenmodal approach to Kogelnik's coupled-wave equations, akin to the dynamical theory of x-ray diffraction. The relationship between the direction of phase progression of the coupled-waves at Bragg incidence, and the direction of the Poynting vector is carefully delineated. As a consequence, a new technique-Poynting Vector Optics — is suggested as potentially an important means of designing thick gratings to fulfil certain beam processing roles, especially in integrated optics applications. The two-dimensional coupled-wave equations are briefly employed to illustrate the effectiveness of a particular focussing device.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 26 (1981), S. 89-98 
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82 ; 42.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The two-dimensional analysis of a recently reported thick grating Bragg diffraction focussing device is carried out using Solymar's coupled-wave approach. It is shown that the device is capable of operating as a non-divergent lens with beam contraction ratios of better than 100:1, and conversion efficiencies of nearly 100%. It is also shown that it can operate as a novel kind of Fourier spectrum analyser, the focussed diffracted intensity being proportional (as a function of Bragg condition violation) to the modulus squared of the Fourier transform of the incident finite beam. The focussing properties are studied as functions of incident beam profile, width and position, grating strength and Bragg condition violation. Poynting vector optics is used successfully to predict (in conjunction with the dispersion surfaces of x-ray dynamical theory) the off-Bragg behaviour in the focal plane. It is likely that the device could be used as avariable ratio beam contractor in integrated optics, where the grating strength could be controlled (interdigital electrode system) electrooptically.
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  • 4
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    Electronic Resource
    Springer
    Applied physics 39 (1986), S. 231-246 
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The behavior of light in dielectric gratings is discussed in terms of the optical Floquet-Bloch waves (or modes). The emphasis is on the development of a good physical understanding of the nature of these waves, using the wavevector diagram to summarize their spatial dispersion and spectra. It is shown that Floquet-Bloch theory offers some advantages conceptually over the commonly used coupled-wave theory, because the rays of the Floquet-Bloch waves (given by their group velocities) play the same role in a periodic medium as do those of plane waves in isotropic or graded-index media. The effect on power conservation of truncating the Floquet expansions for the Floquet-Bloch waves is considered in detail. Using the greater intuitive power of Floquet-Bloch theory, it is shown (in contrast to recent claims to the contrary) how rigorous coupled-wave theory can be applied to symmetrical reflection gratings, and secondly how the light in these gratings can be viewed in terms of the multiple-beam interference of Floquet-Bloch waves, leading to behavior reminiscent of a low-finesse Fabry-Perot cavity.
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  • 5
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    Electronic Resource
    Springer
    Applied physics 22 (1980), S. 335-353 
    ISSN: 1432-0630
    Keywords: 42.30 ; 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this review, a surgey of the evidence for the appearance in volume holography of certain anomalous effects (akin to the Borrmann effect in x-ray crystallography) is conducted, with reference to both experimental observations and theoretical models. The main part of the paper is devoted to the application of a recently-developed two-dimensional coupled-wave theory (an extension of Kogelnik's one-dimensional theory) to the modelling of such anomalous phenomena. Extensive calculations based upon this theory, for the case of Gaussian wave incidence on a uniform mixed grating for various boundary conditions, are presented in a unified two-dimensional description of Borrmann-like effects in volume holography. In particular, certain qualitative predictions of the dynamical theory of x-ray diffraction are expressed quantitatively in the two-dimensional theory.
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  • 6
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two rival techniques used in the analysis of Bragg diffraction of two-dimensional light beams by thick unslanted phase gratings, namely Fourier plane wave decomposition and 2-D coupled-wave theory, are compared. The advantages and regions of applicability of each are discussed, and the conditions found under which they yield identical results. In particular, the results of plane-wave decomposition are used to provide quantitative conditions for validity of 2-D coupled-wave theory. These conditions are not easily derived using any other technique, and set quantitative limits to how narrow or fast-varying the incident distribution may be before 2-D coupled-wave theory fails. It is also shown that 2-D coupled-wave theory is inadequate when the parameterv 0, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large.
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  • 7
    ISSN: 0886-1544
    Keywords: intermediate filaments ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin spermatozoa, eggs, and embryos were labeled with the universal antibody against the intermediate filament proteins (anti-IFA) described by Pruss et al. [Cell 27:419-428, 1981] and with anti-beta-tubulin. Localization of these antibodies was by indirect immunofluorescence microscopy. Cytoskeleton of unfertilized eggs, prepared according to a procedure adapted from Kane [Exp. Cell Res. 162:495-506, 1986] or as described by Dufresne et al. [Biochem. Cell Biol. 66:780-791, 1988], and reacted with the anti-IFA demonstrate a uniformly stained background except for the nuclear areas, which appear as dark rings. During the first cell cycle, the anti-IFA staining pattern coincides with that of spindle-associated tubulin but not with the cortical pattern of microtubules. Swimming embryos reacted with the anti-IFA show a labeling located on the cilia and within the cytoplasm of each individual cell of the larva. In spermatozoa, the labeling occurs all along the flagellae. Immunoblots of proteins from eggs and embryos reveal one major protein of 117 kDa and sometimes a component of 66 kDa, both of which cosediment with tubulin during the isolation procedure of microtubules described by Vallee and Bloom [Proc. Natl. Acad. Sci. USA 80:6259-6263, 1983]. These data show that proteins homologous to the intermediate filament proteins reported in vertebrate cells are present in both gametes of sea urchins. The specific localization ofthese proteins in the spindle, the flagella, and the cilia suggest that they may play a significant role in the organization and function of the microtubular lattice of the spermatozoa and of the embryo.
    Additional Material: 8 Ill.
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  • 8
    ISSN: 0886-1544
    Keywords: intermediate filaments ; phosphorylation ; sea urchin embryos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of 6-dimethylaminopurine (6-DMAP) on the length of the cell cycle and on the state of phosphorylation of a putative intermediate filament protein, p117, have been studied in sea urchin embryos. Embryos were transferred into sea water containing 600 μM 6-DMAP at 0.5, 2 or 5 min after insemination, and incubated for 30 or 90 min. The effects of 6-DMAP on cell cycle length were studied by determining the time required for completion of mitosis upon return of the embryos in normal sea water. In all instances, except for the embryos transferred 0.5 min after insemination (AI) and incubated for 30 min, the duration of the M phase was shortened compared to controls, being faster in the embryos incubated for 90 minutes compared to the 30 min incubation period. However, embryos transferred 0.5 min AI have a longer M-phase than those transferred 2 minutes or later after fertilization, suggesting that between 0.5 and 2 min after fertilization, critical phosphorylating events occur which affect the commitment of the cells to enter M-phase.To study the pattern of p117 phosphorylation during the cell cycle, the eggs were transferred 2 minutes after fertilization in presence of 600 μM 6-DMAP and with 200 μCi/ml of 32P-orthophosphate. Analyses of 32P-labelled proteins after exposure of SDS-PAGE gels and their corresponding blots suggested that phosphorylation of p117 greatly increases at the time of pronuclear fusion, and then declines slightly at prophase-metaphase. This decrease is markedly enhanced when the cells are treated with 6-DMAP during metaphase in order to induce a premature breakdown of the mitotic apparatus. A causal link is suggested between the level of phosphorylation of p117 and its state of assembly. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 1059-910X
    Keywords: Heparan sulfate proteoglycans ; Nephrogenesis ; Glomerular basement membranes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In vivo labeling of infant rat and mouse glomerular basement membranes (GBMs) with polyclonal anti-laminin IgGs results in binding across the full widths of GBMs at all stages of development. These stages include the pre-fusion, double basement membranes found beneath endothelial cells and podocytes in early glomeruli, and the subepithelial matrix outpockets where newly synthesized GBM is spliced into fused basement membrane during glomerular maturation. Identical binding results are obtained either with peroxidase or post-embedding immunogold techniques. Although injected cationized ferritin also binds abundantly to all developing GBMs, it quickly disappears and, 24 hours after injection, is generally absent from GBMs but remains within mesangial matrices. Injection of newborn mice with monoclonal anti-laminin IgGs results in dense labeling of pre-fusion GBMs but post-fusion GBMs and subepithelial outpockets are weak-negative. Although masking can not be excluded, these results indicate that laminin epitopes are removed during GBM fusion and splicing, either by isoform substitution or proteolytic processing. The loss of bound cationized ferritin is believed to occur mainly through rapid turnover of GBM proteoglycans. © 1994 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
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  • 10
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The arteries and veins of the heart of the beluga whale (Delphinapterus leucas) are described from the dissection of nine specimens. The arterial distribution is composed of the basic mammalian pattern of two major vessels, the left and right coronary arteries, which supply the cardiac tissue. The venous drainage is provided by three major systems which are the great, middle, and small cardiac veins. The vascular characteristics of the heart of the beluga whale are the marked sinuosity of both coronary arteries and their main branches, the numerous large interarterial anastomoses between major vessels, and the duplication of vessels in parallel branches. These characteristics are discussed in functional terms and correlated with the diving ability of the species.
    Additional Material: 5 Ill.
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