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  • 1
    Digitale Medien
    Digitale Medien
    Motion of ions in an electron cyclotron resonance plasma (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2890-2892 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The motion of ions emerging from an electron-cyclotron-resonance plasma source has been investigated. Trajectories have been calculated by solving the ion equations of motion in a divergent magnetic field and an electrostatic longitudinal accelerating field which has to be evaluated self-consistently. The trajectory calculations have been combined with a Monte Carlo procedure for choosing the initial ion phase space variables in order to study the propagation of the ion distribution function. It is shown that outside the chamber the spatial profile of this distribution is increasingly broadened with distance from the second magnet due to the diverging magnetic field lines, while at the same time the ions gain energy from the electrostatic field. For an argon plasma a mean ion beam energy of about 16 eV with respect to the plasma source potential results at the target plane in a distance of 60 cm from the source.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.110316
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  • 2
    Digitale Medien
    Digitale Medien
    A holographic grating study on a crystal-to-crystal photodimerization and thermal backreaction (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10474-10480 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The thermally reversible single-crystal-to-single-crystal [2+2] photodimerization of a styrylpyrylium salt, (E)-2,6-Di-tert-butyl-4-[2-(4-methoxyphenyl)-ethenyl]pyrylium- trifluormethansulfonate, has been investigated by means of a laser-induced holographic grating technique. By irradiation far into the long wavelength absorption tail, the single crystalline character of the sample can be retained both during the photodimerization and the thermal backreaction. Without irradiation the holographic gratings are stable at room temperature, but decay at elevated temperatures. From the temperature dependence of the holographic growth and decay curves an upper limit for the activation energy for the photodimerization is obtained to 15.2 kJ/mol. For the thermal cyclobutane cleavage an activation energy of 99 kJ/mol and an attempt frequency of 1.2×1012 s−1 are found. © 1994 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.467865
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  • 3
    Digitale Medien
    Digitale Medien
    Thermodiffusion in polymer solutions as observed by forced Rayleigh scattering (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 660-668 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Thermodiffusion, the cross coupling between temperature and concentration, is studied in dilute polymer solutions by forced Rayleigh light scattering. First a spatial temperature grating is created within the solution by absorption of an optical interference grating and subsequently a concentration grating builds up. The time-dependent diffraction efficiency of both gratings is described by a phenomenological model from which the thermal diffusivity, the ordinary diffusion coefficient, and the thermodiffusion coefficient are obtained without the need for absolute intensity measurements or calibration with a known standard. No labeling of the polymer chains with photochromic dyes is required. Experimental details and potential pitfalls are discussed. Measurements are carried out on polystyrene in ethyl acetate and the obtained values compare well with data taken from the literature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.464610
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  • 4
    Digitale Medien
    Digitale Medien
    Polyangiitis overlap syndrome with features of Wegener's granulomatosis and Panarteriitis nodosa (1991)
    Springer
    Journal of molecular medicine 69 (1991), S. 374-374 
    Details
    ISSN: 1432-1440
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02115788
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  • 5
    Digitale Medien
    Digitale Medien
    A K-12 faculty salary-growth model: State and local norms (1992)
    Springer
    Journal of personnel evaluation in education 5 (1992), S. 369-399 
    Details
    ISSN: 1573-0425
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Pädagogik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00126829
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  • 6
    Digitale Medien
    Digitale Medien
    Druckverlust in glatten und innenberippten Verdampferrohren (1991)
    Springer
    Heat and mass transfer 26 (1991), S. 323-330 
    Details
    ISSN: 1432-1181
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Für den Parameterbereich konventioneller Dampferzeuger wurde an einer Hochdruckversuchsanlage der Druckverlust in glatten und innenberippten Verdampferrohren gemessen. Basierend auf diesen Experimenten und Meßwerten aus der Literatur wurden Verfahren entwickelt, mit denen der Reibungsdruckverlust in diesen Rohren mit guter Genauigkeit berechnet werden kann. Um die diesen Verfahren zugrundeliegenden Modellvorstellungen zu überprüfen, wurde die Staudruckverteilung bei einund zweiphasiger Durchströmung in glatten und innenberippten Rohren bestimmt. Durch Vergleichsmessungen, die bei horizontaler und vertikaler Rohrlage durchgeführt wurden, konnte außerdem die sogenannte Gravitationsdichte, der der geodätische Druckabfall proportional ist, für innenberippte Rohre ermittelt werden.
    Notizen: Abstract The pressure drop in smooth and rifled evaporator tubes was measured on a high pressure test facility for the range of parameters of a conventional steam generator. Based on these experiments and results from literature, methods were developed by which the frictional pressure loss in these tubes may be calculated with a good degree of accuracy. To verify the assumptions on which these models are based, the stagnation pressure distribution in single-phase and two-phase flow in smooth and rifled tubes was determined. By comparing measurements taken on tubes in horizontal and vertical orientation, the so called liquid hold-up, which is a measure for the hydrostatic pressure drop, could be determined for rifled tubes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01591665
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  • 7
    Digitale Medien
    Digitale Medien
    Visual and vestibular signals in the lateral mesencephalic tegmental region of the cat (1991)
    Springer
    Experimental brain research 85 (1991), S. 641-649 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Lateral mesencephalic tegmental region ; Brain stem ; Visual responses ; Vestibular responses ; Auditory responses ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Single unit recordings from two alert cats were used in an attempt to further elucidate the function of the lateral mesencephalic tegmental region (LTR), a part of the mesencephalon forming a link between the superior colliculus and the lower brain stem. A total of 155 units recorded from the LTR were tested with visual, vestibular and acoustic stimuli. Of these, 54 cells (36%) were characterized as either visually (n=33) or vestibularly (n=21) responsive and an additional 13 cells were driven by complex acoustic stimuli. Visually responsive cells typically were directionally selective with large, mainly contralateral receptive fields. Vestibularly responsive cells were modulated by stimulation of either the horizontal canals (yaw stimulation; n = 16) or of both pairs of vertical canals (pitch stimulation; n=5). About half of the cells with activity modulated by rotation about the yaw axis increased discharge during ipsiversive (Type I), the other half during contraversive rotation (Type II). Of the 5 cells with activity modulated by pitch stimulation, 4 preferred the nose-down and only 1 the nose-up direction. Although the discharge of units responsive to yaw stimulation was roughly in phase with head velocity (mean phase lag with respect to head velocity: 10.6 deg), none of the vestibular cells had activity correlated with eye position, eye velocity or movement of visual stimuli. Our observations suggest that the LTR might introduce visual and vestibular signals into the tecto-facial pathway which may be used to adjust the size of pinna movements with respect to the size of ongoing head- or body movements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00231750
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  • 8
    Digitale Medien
    Digitale Medien
    Identification of rape seed cultivars (Brassica napus) by starch gel electrophoresis of enzymes (1990)
    Springer
    Euphytica 45 (1990), S. 179-187 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; rape seed cultivars ; isozyme variation ; variety identification ; partial outcrossing species
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Isozyme patterns were used to characterize ten commercial rape seed (Brassica napus) cultivars. Extracts of cotyledons were made 4–7 days after germination and separated by electrophoresis on starch gels. A sample of more than 100 plants of each variety was analysed and stained for 4 polymorphic enzyme loci (Lap, Gpi, Acon, and Sdh). Therewith, it was possible to distinguish all ten rape varieties qualitatively by at least one typical enzyme pattern. Further, it could be demonstrated that all pairs of varieties showed clear qualitative differences in isozyme patterns, when only tow loci were screened (Acon, Sdh). Using χ2 test of homogeneity all pairs of varieties differ significantly in their frequencies of isozyme patterns for Acon and in all but one for Sdh.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00033284
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  • 9
    Digitale Medien
    Digitale Medien
    A fast membrane osmometer based on a porous glass membrane: first results (1993)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 44 (1993), S. 238-242 
    Details
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The prototype of a fast and versatile membrane osmometer based on a capillary shaped porous glass membrane has been developed and successfully tested with solutions of polystyrene in toluene. The coaxial design of the cell is ideally suited both for batch and continuous flow operation. Time constants on the order of several seconds are observed with membranes of 10 nm and 20 nm nominal pore size. Important design criteria are discussed and first results for the cut-off molar mass are reported.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/actp.1993.010440505
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