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Showing papers by "Technical University of Berlin published in 1977"


Journal ArticleDOI
TL;DR: In this article, the authors considered the C*-algebra generated by n≧2 isometries S 1S 1+1+snS * n = 1.
Abstract: We consider theC*-algebra\(\mathcal{O}_n \) generated byn≧2 isometriesS1,...,Sn on an infinite-dimensional Hilbert space, with the property thatS1S*1+...+SnS*n=1. It turns out that\(\mathcal{O}_n \) has the structure of a crossed product of a finite simpleC*-algebra ℱ by a single endomorphism scaling the trace of ℱ by 1/n. Thus,\(\mathcal{O}_n \) is a separableC*-algebra sharing many of the properties of a factor of typeIIIλ with λ=1/n. As a consequence we show that\(\mathcal{O}_n \) is simple and that its isomorphism type does not depend on the choice ofS1,...,Sn.

1,353 citations



Journal ArticleDOI
TL;DR: The energy-dependent release of bound [14C]nucleotides trom the chloroplast coupling factor CF1, has been used to monitor conformational changes in CF1 and these results may be explained tentatively by the following concept.

186 citations


Journal ArticleDOI
TL;DR: In this paper, the authors bestatigt sich die schon eingangs erwahnte Festellung, das in Eine klare Differenzierung der Gattung Senecio von den Nachbargruppen von der Seite der Inhaltsstoffe her, ist nach wie vor problematisch.

166 citations


Journal ArticleDOI
TL;DR: In this paper, the inversion recovery method for determining T 1 relaxation times is theoretically treated for an isolated nuclear spin without taking into account rf field inhomogeneities, and the accumulated signal intensity after n scans, S n ( τ ), is found to be equal to C + B ( τ )exp(− τ / T 2 ), where C is a constant, B( τ ) depends on the delay time τ, the frequency offset, the waiting period T, and the nominal flip angles.

137 citations


Journal ArticleDOI
TL;DR: The interference pattern of two laser beams induces periodical variations of the optical properties of matter (refractive index and absorption coefficient). Induced grating structures have been observed in absorbing liquids and solids, plasmas, laser materials, dye solutions and semiconductors as discussed by the authors.
Abstract: The interference pattern of two laser beams induces periodical variations of the optical properties of matter (refractive index and absorption coefficient). Induced grating structures have been observed in absorbing liquids and solids, plasmas, laser materials, dye solutions and semiconductors. These gratings have been applied to thermal diffusion measurements, excitation of high frequency normal and second sound waves, determination of electronic lifetimes, distributed feedback lasers and real-time holography. The literature on transient grating materials and applications is surveyed.

121 citations


Journal ArticleDOI
TL;DR: In this article, the results of an investigation of six Mexican species of the old genus Eupatorium which are now placed in the genera Ageratina, Critonia and Fleischmannia, yields two new sesquiterpenic acids (12 and 16), a cadinane derivative (40) and three sesiquiterpene lactones (41, 57 and 58).
Abstract: Die Untersuchung von sechs mexikanischen Arten der alten Gattung Eupatorium, die jetzt in die Gattungen Ageratina, Critonia und Fleischmannia eingeordnet werden, ergibt zwei neue Sesquiterpensauren (12 und 16), ein Cadinan-Derivat (40) und drei Sesquiterpenlactone (41, 57 und 58). Auserdem werden neben bereits bekannten Verbindungen elf neue Thymolderivate (3–10 und 46–48), vier p-Hydroxyacetophenon-Derivate (21, 26, 30 und 45), drei Benzoesaurebenzylester (35–37), ein Flavanon (54) und ein Lignan (60) isoliert. Die Konstitutionen werden durch spektroskopische Daten sowie durch einige chemische Reaktionen geklart. Die chemotaxonomischen Aspekte werden diskutiert. Naturally Occurring Terpene Derivatives, 76. On Constituents of the Eupatorium Group The investigation of six Mexican species of the old genus Eupatorium which are now placed in the genera Ageratina, Critonia and Fleischmannia, yields two new sesquiterpenic acids (12 and 16), a cadinane derivative (40) and three sesquiterpene lactones (41, 57 and 58). In addition besides already known compounds eleven new thymol derivatives (3–10 and 46–48), four p-hydroxy-acetophenone derivatives (21, 26, 30 and 45), three benzyl benzoates (35–37), a flavanone (54) and a lignan (60) are isolated. The structures are established by spectroscopic data as well as by some chemical reactions. The chemotaxonomical aspects are discussed.

114 citations


Journal ArticleDOI
TL;DR: In this article, a numerical calculation procedure for the radiated far-field, which is based on Lighthill's wave equation approach with a linearized pressure source function, strongly weighted by axial and radial interference functions, is presented.
Abstract: Experimental results of pressure cross-spectra in model jets indicate that large-scale coherent structures do persist at higher Mach numbers up to 0.8 in the relevant range of Strouhat numbers between 0.1 and 2.0. If the pressure field is Fourier-analy zed circumferentially, the lower-order components are seen to dominate. This, along with the high acoustic efficiency of these components, suggests a numerical calculation procedure for the radiated far-field, which is based on Lighthill's wave equation approach with a linearized pressure source function, strongly weighted by axial and radial interference functions.

104 citations


Journal ArticleDOI
TL;DR: Preliminary results on the spectral dependence of the absorption of light in tissue are presented and discussed with respect to medical laser application.
Abstract: Preliminary results on the spectral dependence of the absorption of light in tissue are presented and discussed with respect to medical laser application.

104 citations


Journal ArticleDOI
TL;DR: In this paper, a thermodynamic analogue of the thermostatic temperature can be developed by generalized empirems which govern the thermal interaction between non-equilibrium and thermally homogeneous systems.
Abstract: On the basis of well known empirems of classical thermodynamics, such as the First and Zeroth Laws, which lead to the definition of calorimeter systems by which heat exchanges can be measured, thermal interaction between thermally homogeneous systems is investigated by methods of set theory. In connexion with Carnap's axiom for a classical measuring quantity a thermodynamic analogue of the thermostatic temperature can be developed by generalized empirems which govern the thermal interaction between non-equilibrium and thermally homogeneous systems. An empirical identification of the contact temperature and its field formulation are given.

90 citations


Journal ArticleDOI
TL;DR: The investigation of twelve further species of the Eupatorium complex affords four new germacrolides and seven guaianolides together with new thymol and p-hydroxyacetophenone derivatives as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, a series of solid solutions of composition La2−xSrxNiO4 (0 ⩽ x⩽ 1) in which the oxidation state of nickel varies from +2 at 0 to +3 at 0.5 has been prepared.

Journal ArticleDOI
TL;DR: In this article, weitgehende Zuordnung der Signale erfolgte mit Hilfe der geminalen und vicinalen 13C-1H-Kopplungen und den Substituenteneffekten.

Journal ArticleDOI
TL;DR: Ru3(CO)12 as mentioned in this paper reacts with tri-t-butylphosphine and butyric acid to form di-μ-(n-butyrato)bis[dicarbonyl(tri-t)-phosphinesine)ruthenium(I)](RuRu).

Journal ArticleDOI
TL;DR: In this paper, the Hamilton's principle was used to formulating the equations of motion and the associated boundary conditions of short unsymmetric sandwich beams. But, the results of the analysis of the frequency and loss factors of typical short sandwich beams are inaccurate by as much as 45 percent.

Journal ArticleDOI
TL;DR: The light-induced reaction kinetics of electron carriers between the two light reactions were studied in spinach chloroplasts and gave evidence for a function of cytochrome f between plastoquinone and chlorophyll a1 in parallel to plastocyanin.

Journal ArticleDOI
TL;DR: An investigation of nine representative species of the tribe Mutisieae yielded some new results of chemotaxonomic interest, including some new sesquiterpenes and coumarins characterised by spectroscopic methods.

Journal ArticleDOI
TL;DR: In this paper, two species of the genus Flourensia have been investigated and their structures have been elucidated by spectroscopic methods, besides the already known characteristic 4-hydroxyacetophenone derivatives.
Abstract: Die Untersuchung von zwei Arten der Gattung Flourensia zeigt, das hier neben bereits bekannten, fur die Tribus charakteristischen Acetylenverbindungen vor allem 4-Hydroxyacetophenon-Derivate vorkommen. 14 Verbindungen (2–4, 8, 11, 13, 14, 18–23 und 25) sind bisher noch nicht isoliert worden. Ihre Konstitutionen werden durch spektroskopische Methoden geklart. On Constituents of the Genus Flourensia The investigation of two species of the genus Flourensia yields, besides the already known characteristic acetylenic compounds of the tribe, mainly 4-hydroxyacetophenone derivatives. 14 compounds (2–4, 8, 11, 13, 14, 18–23, and 25) have not been isolated before. Their structures have been elucidated by spectroscopic methods.

Journal ArticleDOI
TL;DR: In this paper, a thermodynamic analogue of the thermostatic temperature is defined by the vanishing heat exchange between a non-equilibrium system and a heat reservoir, called contact temperature.

Journal ArticleDOI
TL;DR: In this article, the effect of spatial source coherence on jet noise has been investigated theoretically for a normalized cross-spectral density of the source quantity based on a convected Gaussian form and for different special source intensity distributions, Lighthill's approach being used.

Journal ArticleDOI
TL;DR: Evidence is given for such a "triplet valve" to be established also in bacteria, especially the routes leading to the dissipation of excess excitation energy within the photosynthetic unit.

Journal ArticleDOI
TL;DR: In this article, a special chlorophyll-a was found to be charged up sequentially by ChlaiI via univalent electron transfer reactions, until after the accumulation of four redox equivalents of sufficient oxidizing power.


Journal ArticleDOI
TL;DR: Proton release due to water oxidation under these conditions is the subject of this communication and follows a characteristic kinetic pattern.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated three South American Wedelia species, which affords besides known acetylenes several new kaurenic acid derivatives, which have been isolated as their methyl esters.

Journal ArticleDOI
TL;DR: In this article, a new type of a pyrrolizidine derivative (25) is isolated from Senecio pterophorus and the structures are elucidated by spectroscopic methods as well as some chemical reactions.
Abstract: Aus Vertretern der Sektion Rigidi werden neben bereits bekannten Verbindungen vier neue Benzofurane (3, 5, 6 und 10) sowie sechs neue Furanoeremophilane (13, 15, 19–21 und 23) isoliert. Aus Senecio pterophorus wird ein neuer Typ eines Pyrrolizidin-Derivats (25) isoliert. Ahnliche Verbindungen (34–37) enthalt Senecio cissampelinus. Die Konstitutionen werden durch spektroskopische Methoden sowie durch einige chemische Reaktionen geklart. Die chemotaxonomischen Aspekte werden diskutiert. Naturally Occurring Terpene Derivatives, 78 Further Constituents of South African Senecio Species From representatives of the section Rigidi besides already known compounds four new benzofurans (3, 5, 6, and 10) as well as six new furanoeremophilanes (13, 15, 19–21, and 23) are isolated. From Senecio pterophorus a new type of a pyrrolizidine derivative (25) is isolated. Senecio cissampelinus contains similar compounds (34–37). The structures are elucidated by spectroscopic methods as well as by some chemical reactions. The chemotaxonomical aspects are discussed.

Journal ArticleDOI
TL;DR: In this article, the wavelength-modulated reflectivity spectra of ZnSe and ZnS are presented in the energy range from 2.5 to 8 eV.
Abstract: Wavelength-modulated reflectivity spectra of ZnSe and ZnS are presented in the energy range from 2.5 to 8 eV. Around the fundamental transition Eo qualitative evidence for the occurrence of excitonic polariton and exciton-phonon quasi-bound complex is given. The structure at higher energies is compared to calculated derivative reflectivity curves of Walter et al. The agreement between theory and experiment is good. Die wellenlangen-modulierte Reflektivitat von ZnSe und ZnS im Energiebereich von 2,5 bis 8 eV wird dargestellt. Im Bereich des fundamentalen Ubergangs E0 wird der Anteil des exzitoni-schen Polaritons und des quasigebundenen Exziton-Phonon-Komplexes an den Spektren quali-tativ diskutiert. Die hoherenergetische Struktur wird mit entsprechenden Berechnungen der theoretischen modulierten Reflektionsspektren von Walter et al. verglichen. Die ubereinstimmung zwischen Theorie und Experiment ist gut.

Journal ArticleDOI
TL;DR: In this paper, a new method to achieve charge separation in light-driven redox reactions is presented based on the principle of electrostatic interactions of the radical ions produced by the light with the local environment present in aqueous solutions of surfactant aggregates.


Journal ArticleDOI
TL;DR: The close interrelationship between ΔA 0 (chlorophyll- a II ) and delayed fluorescence intensity in the μs range is shown to be interpretable mainly by kinetical rather than by energetical effects.