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  • 1
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    German Medical Science; Düsseldorf, Köln
    In:  57. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie; 20060511-20060514; Essen; DOCSA.09.08 /20060508/
    Publication Date: 2006-07-31
    Keywords: olfactory groove meningioma ; surgical approach ; skull base ; Olkatoriusrinnenmeningeom ; chirurgischer Zugang ; Schädelbasis ; ddc: 610
    Language: English
    Type: conferenceObject
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  • 2
    ISSN: 1573-5117
    Keywords: fish ; assemblage ; artificial reefs ; substrate ; colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Migjorn artificial reef (MAR) was deployed in the summer of 1990 and is made by 48 concrete blocks set 30 m deep on a sea bed of sand with a small proportion of Posidonia oceanica (L.) Delile meadow. Visual censuses of blocks on both substrata were carried out during the months of February, May and September in 1992 and 1993. The MAR fish assemblages were influenced by the surronding substrate. Thus, a group of ubiquitous species, frequent on both substrata and typical of natural rocky habitats (mostly Sparidae) and a group associated with the samples recorded on the Posidonia meadow (mostly Labridae) could be distinguished. Season had only a secondary and slight effect on fish assemblages. The MAR was colonized by 74% of the species in the first two years after deployment. Positive and lineal relationships between species richness, diversity, abundance of necto-benthic species and time since deployment on sandy substrata were found. On Posidonia oceanica deployment time has only increased very sedentary and cryptic species. Although some ways in which the MAR would have a productive function are not rejected, the most obvious MAR working pattern is that of fish aggregation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5117
    Keywords: fish ; assemblage ; artificial reefs ; substrate ; colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Migjorn artificial reef (MAR) was deployed in the summer of 1990 and is made by 48 concrete blocks set 30 m deep on a sea bed of sand with a small proportion of Posidonia oceanica (L.) Delile meadow. Visual censuses of blocks on both substrata were carried out during the months of February, May and September in 1992 and 1993. The MAR fish assemblages were influenced by the surronding substrate. Thus, a group of ubiquitous species, frequent on both substrata and typical of natural rocky habitats (mostly Sparidae) and a group associated with the samples recorded on the Posidonia meadow (mostly Labridae) could be distinguished. Season had only a secondary and slight effect on fish assemblages. The MAR was colonized by 74% of the species in the first two years after deployment. Positive and lineal relationships between species richness, diversity, abundance of necto-benthic species and time since deployment on sandy substrata were found. On Posidonia oceanica deployment time has only increased very sedentary and cryptic species. Although some ways in which the MAR would have a productive function are not rejected, the most obvious MAR working pattern is that of fish aggregation.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photophysical parameters and lasing properties of Coumarin 540A dye molecules are studied in solutions of increasing viscosity, from liquid solutions in 1,4-dioxane to solid solutions in poly(methyl methacrylate). The fluorescence quantum yield and lasing efficiencies decrease as the viscosity of the solution increases, reflecting the strong influence of the rigidity of the medium on the radiative processes. The photodegradation mechanisms acting on the fluorophores are analyzed by following the dependence of laser induced fluorescence and laser output on the number of pump laser pulses. The fluorescence redistribution after pattern photobleaching technique is used, and Fick's second law is applied to study the diffusion of dye molecules in the highly viscous polymer solutions. The diffusion coefficients of the dye molecules as a function of the increased viscosity of the medium are determined. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Modified rhodamine 6G molecules with polymerizable double bonds have been copolymerized with methacrylic monomers and the resulting polymers have been pumped at 337 nm with a N2 laser in a transversal configuration. The preparation of these new materials is described in detail and their lasing properties are evaluated. Important increases in photostability, with lasing efficiencies similar to those found for the parent dye rhodamine 6G in ethanol solution, have been obtained for some of these materials. Lifetimes (measured as an 80% efficiency drop) in excess of 20 000 shots at repetition rates of 2 Hz have been demonstrated. Strong dependence on pump repetition rate was observed. Possible mechanisms and processes responsible for the behavior of these materials are discussed. By using a rotating system where the sample is scanned in a continuous way, the laser output remained stable, with no sign of degradation, after 500 000 shots. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 452-454 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the laser action of pyrromethene 567 incorporated into polymeric matrices and pumped longitudinally with the green line of a copper-vapor laser. When the dye was dissolved in a copolymer of methyl methacrylate and pentaerythritol triacrylate, 290 mW average power at 1 kHz (37% lasing efficiency) was obtained. The laser output decreased to 150 mW after 30 min irradiation time (1.8×106 shots) and to 32 mW after 70 min of operation (4.2×106 shots). Output power of up to 1 W at 6.2 kHz was obtained for short periods of time. Polymeric matrices incorporating rhodamine 6G were also studied. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the lasing action of modified rhodamine 6G dyes copolymerized with methacrylic monomers. The laser samples were transversely pumped with a N2 laser at 337 nm. Lasing efficiencies similar to those found for rhodamine 6G in ethanol solution have been achieved. Important increases in photostability, with lifetimes in excess of 20 000 shots at 2 Hz, have been obtained. By using a rotating mechanism, a stable output with no sign of degradation after half a million shots has been demonstrated. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Having in mind the high complexity of the sky radiance distribution, the Commission of the European Communities, in the frame of the Solar Energy R&D in the European Community Programme, developed among other related fields of research a clear sky radiance model. This model, the so-called EC-Model, was intended for the estimation of the diffuse irradiance falling on an inclined surface by integration of the sky radiance field. It represents a progress development over its predecessor, the Berlin model, and takes into account all the scientific knowledge about this topic, lying heavily on the principles of the Liebelt formulation and the work of Steven and Unsworth on the observed relative radiance distribution. The European Solar Radiation Atlas was in part prepared by the adoption of the EC-Model and could not take into account Valko’s new results about sky radiance distributions, because of time coincidence and that only previous results were ready at the time it was published. In this work, we focus on the EC-Model behaviour, against experimental sky radiance data from Toronto, Canada. The SKYSCAN’834 Data Set is a well-known database, which we have used in order to investigate the EC-Model behaviour both under its original formulation (the one that has been used in the development of the Atlas) and under the modified version suggested by Valko’s results. Even though we are considering data from outside Europe, the results of this test let us establish the model limitations and the modifications that should be done to it.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Steady-state photolysis at 365 nm has been employed to carry out a structure - reactivity investigation of the 2,6-dihalogen derivatives of p-nitroaniline (pNA). Detailed studies of the spectroscopy of these molecules were accomplished. Photoreduction behavior of the 2,6-dihalogen derivatives of p-nitroaniline in the presence of N,N-dimethylaniline (DMA) has been analyzed. The efficiency of these compounds as photoinitiators was studied by following the polymerization kinetics of the lauryl acrylate (LA) monomer by differential scanning photo-calorimetry (Photo-DSC) under aerobic and anaerobic conditions. Using size exclusion chromatography (SEC) analysis of the polymers their number-average molecular weights, the number-average degree of polymerization, and the length of the kinetic chain were determined and information on the nature of the end-chain groups and the chain-transfer behavior of these photoinitiators systems were obtained. The polymerization activity of the 2,6-dihalogen derivatives of pNA proved to be higher than those obtained with conventional aromatic ketone photoinitiators.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Narrow-linewidth multiple-prism grating solid-state dye laser oscillators are analysed using ray transfer matrices. Attention is given to beam divergence measurements and the effect on them of thermal lensing, at the solid-state gain medium. It is found that although thermal lensing leads to an increment of beam divergence, it induces oscillation in the unstable resonator regime, thus contributing to the attainment of TEM00 beam profiles. In addition, narrow-linewidth emission in dispersive oscillators, incorporating rhodamine 6 G doped HEMA:MMA gain media, is reported for the first time. Laser efficiency is 4–5% at a laser linewidth ≤1.8 GHz for double-longitudinal-mode emission. Beam divergence is measured in the 2–2.3 mrad range, in good agreement with theory.
    Type of Medium: Electronic Resource
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