15 Fakultätsübergreifend / Sonstige Einrichtung
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Item Open Access Opto-electronic pattern recognition system(1970) Tiziani, Hans J.; Beyeler, Bernhard H.; Witz, WernerAn opto-electronic technique for the classification of grains of photographic emulsions by shape is described. Fortunately, the shapes to be distinguished differ only in their two-dimensional rotational symmetry group. A special optical filtering procedure has been developed to take account of the implied positional and rotational invariance. The transfer from the optical to the electrical signal is obtained in a simple manner. The method works satisfactorily even for a rather complicated cluster. Some results are discussed.Item Open Access Speckling in diffraction patterns and optical images formed with the laser(1970) Hopkins, Harold H.; Tiziani, Hans J.It has been shown that the known characteristics of speckling in both diffraction patterns and optical images can be explained on the basis of a simple physical model. This explains not only the occurence of a predominant size but also the high contrast in speckle patterns.Item Open Access Wavelength dependent triplet state populating mechanisms of naphthalene in heavy atom hosts(1973) Schweitzer, Dieter; Zuclich, Joseph A.; Maki, August H.We have made zero-field optically-detected magnetic resonance measurements on the triplet state of naphthalene-d8 incorporated in the heavy-atom host crystals p-dichlorobenzene, p-dibromobenzene, and s-tetrachlorobenzene. The dependence of the relative triplet sublevel populating rates on the exciting wavelength is interpreted in terms of the electronic excitation transfer mechanisms. We find that upon excitation of the host S1 ← S0 transition in p-dichlorobenzene, energy transfer to the guest T1 takes place via the guest S1, whereas in the other host crystals the intermediate is mainly the host T1 band. Upon host T1 ← S0 excitaton, trapping takes place from a spin-aligned excitor band in s-tetrachlorobenzene, whereas the initial alignment is lost prior to trapping in the dihalobenzene hosts.Item Open Access Bürgerinitiativen im lokalpolitischen Entscheidungsprozeß : Entstehungsbedingungen und Aktionsmuster(1978) Gabriel, Oscar W.Im Erstarken der Initiativbewegung äußert sich zwar Kritik an Fehlleistungen von Politik und Verwaltung, die im kommunalen Bereich besonders drastisch dokumentiert sind. Ebenso bedeutsam sind jedoch die eingetretenen Veränderungen im politischen Bewußtsein der bundesdeutschen Mittelschicht, die diese Form politischer Partizipation erst möglich machten. Bürgerinitiativen stellen somit keine spezifische Erscheinung des lokalpolitischen Systems dar. Vielmehr führte das Vorliegen entsprechender Randbedingungen dazu, daß sich die kommunale Ebene als besonders geeignetes Feld für die Formulierung von Partizipationsforderungen erwies.Item Open Access Effects of abscisic acid on photosynthesis of protoplasts from Petunia hybrida(1974) Hoffmann, Franz; Kull, UlrichProtoplasts from plants are suitable experimental objects for investigations in which substances are taken up by cells, since chemicals can reach the cell surface directly. Therefore, it is convenient to use them for experiments concerned with effects of phytohormones on metabolism. So far, some work on the application of auxins 1-3 has been described, and recently we have made some investigations on the influence of zeatin on photosynthesis and respiration of isolated mesophyll protoplasts from Petunia.Item Open Access Osmotische Verhältnisse und Zuckergehalte im Jahresgang bei Bäumen Ost-Afghanistans. 2, Cercii griffithii und Pistacia cabulica(1972) Kull, Ulrich; Breckle, Siegmar-WalterIn der Kohe Daman-Ebene nördlich von Kabul gibt es einige weitbekannte Standorte von Cercis griffithii. Die Standorte, meist im Geröll oder auf Fels, scheinen in den meisten Fällen nicht grundwasserfern zu sein. Südwestlich von Kabul finden sich an trockenem Felsstandort alte Pistazien mit dicken Stämmen. Diese Relikte können sowohl als Zeiger eines früher wesentlich dichteren Vorkommens und weiterreichender Verbreitung angesehen werden. Die Jahresgänge der osmotischen Verhältnisse wie auch der Brechungsindices des Zellsaftes zeigen in den Blättern dieser beiden sommergrünen Arten Maxima im Spätsommer. Die Speicherkohlenhydrate zeigen in Rinden von Cercis vor allem Saccharose, Glucose und Stärke eine ausgeprägte Jahresperiodik, welche derjenigen von Quercus baloot und der mitteleuropäischer Arten ähnlich ist. Das winterliche Zuckermaximum ist mit einem Auftreten geringer Mengen von Raffinose verknüpft. In den Blättern von Cercis erfolgt mit zunehmendem Blattalter eine Abnahme der Zucker- und Stärkegehalte. Pistacia cabulica weist kein winterliches Maximum des Gesamtzuckergehaltes auf und führt weder Galaktoside noch Fructoside. Rinden und Blätter besitzen Maximalwerte des Zuckergehalts während der sommerlichen Trockenperiode. Die Berechnung des prozentualen Anteils des Gesamtzuckergehaltes am potentiellen osmotischen Druck läßt erkennen, daß die letztgenannte Größe vom Zuckerhaushalt je nach Art mehr oder weniger unabhängig ist.Item Open Access Electronic properties of the triplet state of fluorene, carbazole, dibenzofuran and dibenzothiophene(X-traps)(1979) Goldacker, Wilfried; Schweitzer, Dieter; Zimmermann, HerbertThe triplet state of X-traps in neat single crystals of fluorene, carbazole, dibenzofuran and dibenzothiophene was investigated bv the method of ODMR in zero field at 1.3 K. In addition to the intersystem crossing rates, steady state populations, decay rate constants and relative radiative rate constants of the sublevels, the spin-lattice relaxation (SLR)-rates were measured, which could not be neglected even at this low temperature. In the case of dibenzothiophene a strong intramolecular heavy-atom effect due to the sulphur atom was observed which allowed direct So → T1 excitation.Item Open Access Reaktionen der Silylphosphine : Bildung von Lithium-tris(diäthylphosphinyl)silicid(1967) Fritz, Gerhard; Becker, Gerd-Item Open Access Strøkøøp - a program on long-term investigation of cost optimum nuclear power systems : input description (status april 1971)(1971) Voß, AlfredFor the purpose of a long-term planning in energy politics one needs some information support in order to reach an optimum extension of the energy supply grid. Arising problems might todate be solved sufficiently precise by means of mathematical optimization processes. The program discussed here is appropriated to deliver such a support - a suitable employment provided. It was determined the cost-optimum capacity distribution of up to 10 different power plants in a national grid under consideration of the classified curve of annual load curve and of various restrictions, e.g. limitation of capacity increase of fast plutonium breeders by limited availability of plutonium. The optimization is carried out for each period of time. Here, nuclear power plants were exclusively selected according to economic view points. The description of this calculational model corresponds in essential to that of Ref. (2), and is made in the following chapter. Henceforth is given a description on the accomplishment of special calculations, in the end a detailed description of all necessary input data. Also, an illustration is given for input and output.Item Open Access Nervous-system-specific carcinogenesis by ethylnitrosourea in the rat: molecular and cellular aspects(1977) Rajewsky, Manfred F.; Augenlicht, Leonard H.; Biessmann, Harald; Goth, Regine; Hülser, Dieter F.; Laerum, Ole D.; Lomakina, L. Ya.A lead in the search for cellular determinants favoring neoplastic transformation may be provided by the pronounced tissue specificity of the oncogenic effect of certain carcinogens which do not require enzymatic metabolic activation, i.e., in cases where this specificity cannot be due to tissue differences in the activity of enzymes involved in the formation of the ultimate reactants. A carcinogen that fulfills this condition is the ethylating agent N-ethyl-N-nitrosourea (EtNU). Alkylation of nucleic acid constituents by N-nitroso compounds in relation to mutagenesis and carcinogenesis has received considerable attention recently.