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Showing papers by "Technical University of Berlin published in 1987"


Journal ArticleDOI
01 May 1987-Fuel
TL;DR: In this article, maturation levels and kerogen types (which can be used to estimate the hydrocarbon generating potential of source rocks and oil shales) were defined by infrared spectroscopy.

250 citations


Proceedings ArticleDOI
01 Oct 1987
TL;DR: This work considers the problem of computing geometric transformations (rotation, translation, reflexion) that map a point setA exactly or approximately into a pointSetB.
Abstract: We consider the problem of computing geometric transformations (rotation, translation, reflexion) that map a point setA exactly or approximately into a point setB. We derive efficient algorithms for various cases (Euclidean or maximum metric, translation or rotation, or general congruence).

236 citations


Journal ArticleDOI
TL;DR: In this article, a causal modeling approach is applied to secondary data measuring retail supply in rural and urban areas, and an explicit test of validity proposes a four-dimensional measurement model of retail satisfaction.

221 citations


Journal ArticleDOI
TL;DR: In this paper, an adiabatic evolution that approximates the physical dynamics and describes a natural parallel transport in spectral subspaces was studied, and it was shown that the eventual tunneling out of such spectral sub-spaces is smaller than any inverse power of the time scale if the Hamiltonian varies infinitly smoothly over a finite interval.
Abstract: We study an adiabatic evolution that approximates the physical dynamics and describes a natural parallel transport in spectral subspaces. Using this we prove two folk theorems about the adiabatic limit of quantum mechanics: 1. For slow time variation of the Hamiltonian, the time evolution reduces to spectral subspaces bordered by gaps. 2. The eventual tunneling out of such spectral subspaces is smaller than any inverse power of the time scale if the Hamiltonian varies infinitly smoothly over a finite interval. Except for the existence of gaps, no assumptions are made on the nature of the spectrum. We apply these results to charge transport in quantum Hall Hamiltonians and prove that the flux averaged charge transport is an integer in the adiabatic limit.

188 citations


Journal ArticleDOI
TL;DR: In this article, a modified neutron spin echo (NSE) spectrometer using high frequency spin flippers to replace the static spin flipper and the long magnetic precession field in each arm of the classical NSE setup was proposed.

170 citations


Journal ArticleDOI
TL;DR: A photosystem I (PS I) reaction center complex was isolated and purified from the cyanobacterium Synechococcus sp.

163 citations



Journal ArticleDOI
TL;DR: A reaction scheme is proposed relating the redox reaction, the activation and the catalytic reaction of the chloroplast ATP synthase, which can occur in different redox and activation states.

150 citations



Journal ArticleDOI
TL;DR: In this paper, the spectral p-n junction model is rigorously applied based on the accepted standard spectra and a quantitative expression for the increase in efficiency under concentration is derived. But the model can be quantitatively applied to all tandem solar-cell systems, and the special form and use of reverse saturation current density is discussed in detail.
Abstract: Tandem solar cells can have significantly higher efficiencies than single-junction solar cells because they convert a larger fraction of the incident solar spectrum to electricity. For the design of tandem solar cells the spectral p-n junction model is proposed. It is based on tabulated standard spectra, on the fit of experimentally achieved open-circuit voltages, and assumes a quantum efficiency of unity. By consistent treatment of the energy gap in the diode equation, the model can be quantitatively applied to all tandem solar-cell systems. The special form and use of the reverse saturation current density is discussed in detail. The spectral p-n junction model is rigorously applied based on accepted standard spectra. The tandem solar-cell performance limits based on the model are calculated. A quantitative expression for the increase in efficiency under concentration is derived. Choosing materials with optimum bandgaps, a two-solar-cell two-terminal tandem system can achieve a theoretical maximum efficiency of 38.2-percent (AM1.5 global). A two-solar-cell four-terminal tandem system can have a maximum efficiency of 39.1 percent at the same spectrum. This four-terminal system allows more freedom in choosing the most efficient bandgap combinations. Assuming realistic losses, a configuration consisting of a Si solar cell on the bottom and a solar cell with a bandgap, E g = 1.85 eV on the top, a maximum efficiency of 32.1 percent (AM1.5 global) can be predicted. Increased efficiency can be obtained from a three-solar-cell six-terminal tandem system. With an optimum bandgap combination the theoretical maximum efficiency is 44.5 percent (AM1.5 global) for the three-solar-cell system. The limits predicted by the model are discussed for tabulated standard spectra. The highest achievable efficiency is 57.3 percent (AM1.5 global) without concentration of the incident light. The increase in efficiency under concentration is evaluated, and it is found that the relative change of the efficiency at any concentration X is linear with In (X).

132 citations



Journal ArticleDOI
TL;DR: Two different, highly active O2‐evolving Photosystem II complexes were purified from the cyanobacterium Synechococcus sp.

Journal ArticleDOI
TL;DR: The Amalgamation Theorem states that graph derivations which respect the given associations can be amalgamated to a single derivation via the “amalgamated” production.


Journal ArticleDOI
TL;DR: The anatomy of the unusually long transit sequence is discussed with regard to current concepts of protein import into and protein routein within the organelle.
Abstract: Several cDNA clones encoding the “33 kDa” protein associated with the photosynthetic water oxidation activity of spinach were sequenced. A 1208 bp insert of one of the clones encodes the entire 331 amino acid residues of the precursor protein including 84 amino acids (8.5 kDa) of the amino-terminal transit peptide, 49 bp of the 5′ and 111 bp of the 3′ untranslated segment of the mRNA. The 3′ poly(A) tail starts 19 bp downstream from a putative polyadenylation signal, TATAAA. The hydrophilic mature protein consists of 247 amino acid residues corresponding to an Mr of 26.5 kDa, which is 6.5 kDa smaller than the value determined by SDS-polyacrylamide gel electrophoresis (33–34 kDa), and shows a certain degree of conservation with the putative Mn-complexing active sites of bacterial Mn-dependent superoxide dismutases. The anatomy of the unusually long transit sequence is discussed with regard to current concepts of protein import into and protein routein within the organelle.

Journal ArticleDOI
TL;DR: In this article, the electroclinic effect in the smectic A phase of 4-(3-methyl-2-chlorobutanoyloxy)-4'-heptyloxybiphenyl has been investigated.
Abstract: The electroclinic effect in the smectic A phase of 4-(3-methyl-2-chlorobutanoyloxy)-4'-heptyloxybiphenyl has been investigated. Values up to 10° are obtained for the induced tilt angle, which is proportional to the applied d.c. field. The amplitude of the tilt angle modulation shows exactly the same dependence on temperature and frequency as the dielectric constant which indicates a linear coupling between the tilt angle and the polarization. The relaxation frequency increases linearly with temperature from 0.4 MHz at the SA—S∗C transition to 3.5 MHz near the SA-I clearing point. Optical switching times below 0.5 μs were established.

Journal ArticleDOI
TL;DR: In SDS gels of purified, highly active ATP-synthase from chloroplasts, CF0F1 a protein band was detected at an apparent molecular weight of 100 kDa, which implies that this supramolecular complex represents a stable native substructure of CF 0F1.
Abstract: In SDS gels of purified, highly active ATP-synthase from chloroplasts, CF0F1 a protein band was detected at an apparent molecular weight of 100 kDa. This protein was isolated on a preparative SDS gel. The 100 kDa protein can be dissociated at increased temperature or increased incubation time into an 8 kDa protein, which is identical with the subunit III of CF0 (DCCD- binding protein or proteolipid). This implies that the 100 kDa band is a stable supramolccular complex containing at least 12 copies of subunit III. Electron micrographs reveal a diameter of 6.3 nm and a membrane spanning length of 6.1 nm. We assume that this supramolecular complex represents a stable native substructure of CF0F1.

Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of S-state transition kinetics was measured by spectroscopy in the ultraviolet region with O 2 -evolving Photosystem II particles from a thermophilic cyanobacterium.

Journal ArticleDOI
01 Nov 1987
TL;DR: The non-ponential fluorescence decay behavior of triphenylmethane (TPM)-dyes can be understood as barrierless relaxation, i.e. intramolecular rotational relaxation of dialkylanilino groups under the influence of a driving force as discussed by the authors.
Abstract: The nonexponential fluorescence decay behaviour of triphenylmethane-(TPM)-dyes can be understood as barrierless relaxation, i.e. intramolecular rotational relaxation of dialkylanilino groups under the influence of a driving force. The observed viscosity dependent rotational relaxation rates of TPM-dyes with large and small, rigid and flexible rotor groups do not obey the Debye-Stokes-Einstein relationship but can be fitted within the microviscosity theory of Gierer and Wirtz and show that free volume effects are important. The relative size of free volume effects in n-alcohols, diols and glycerol can be determined by comparing the rates of different TPM-dyes.

Journal ArticleDOI
TL;DR: In this article, the existence of shape resonances exponentially close to the real axis as ℏ↘0.0 was shown for a class of Schrodinger operators with potentials having minima embedded in the spectrum and non-trapping tails.
Abstract: For a class of Schrodinger operatorsH:=−(ℏ2/2m)Δ+V onL 2(ℝ n ), with potentials having minima embedded in the continuum of the spectrum and non-trapping tails, we show the existence of shape resonances exponentially close to the real axis as ℏ↘0. The resonant energies are given by a convergent perturbation expansion in powers of a parameter exhibiting the expected exponentially small behaviour for tunneling.

Journal ArticleDOI
TL;DR: The oxygen flash yield and the kinetics of Chl a+II (P-680+) reduction have been measured under repetitive excitation as a function of pH between pH 4.0 and pH 9.0 in oxygen-evolving PS II particles from Synechococcus sp.

Journal ArticleDOI
TL;DR: Alignteins of the sequence with sequences from Rieske FeS-proteins of respiratory electron transport chains shows little sequence homology, but remarkable similarity in secondary structure including a putative N-terminal transmembrane segment of about 25 residues and the peptides CTHLGCV and CPCHGS in the C-terminals that are involved in the binding of the Fe2S2-cluster.
Abstract: Summary Several cDNA clones encoding the entire Rieske FeS-precursor protein of the chloroplast cytochrome b 6 f-complex have been isolated by high density plaque immunoscreening of a phage lambda gt11 cDNA expression library, made from poly A+-RNA of spinach seedlings. The identity of the cDNAs has been confirmed by N-terminal amino acid sequencing of the purified protein. The nucleotide sequence indicates a protein of 247 amino acid residues including a putative transit sequence of 68 amino acids corresponding to molecular masses of 26.3 kDa (precursor) and 18.8 kDa (mature protein; 179 amino acid residues). Alignteins of the sequence with sequences from Rieske FeS-proteins of respiratory electron transport chains, two of bacterial and three of mitochondrial origin, shows little sequence homology, but remarkable similarity in secondary structure including a putative N-terminal transmembrane segment of about 25 residues and the peptides CTHLGCV and CPCHGS in the C-terminal region of the protein that are involved in the binding of the Fe2S2-cluster.

Journal ArticleDOI
TL;DR: The integral membrane protein complex of the photosystem I reaction center from the cyanobacterium Synechococcus sp. has been isolated and highly purified as discussed by the authors, and at extremely low protein complex concentrations (50 μg/ml), crystallization occurred.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the absorption changes coupled with the individual transitions S 0 -S 3 and redox reactions in the water-splitting enzyme system S of photosynthesis and showed that the ultraviolet spectrum of S 0 → S 1 transition is different from the spectra of S 1 → S 2 and S 2 → S 3 transition.


Journal ArticleDOI
TL;DR: In this article, a mathematical characterization of standard clocks (i.e., clocks measuring proper time) is presented, which yields an experimental method to test whether or not a given clock is a standard clock.
Abstract: A mathematical characterization of standard clocks (i.e., clocks measuring proper time) is presented, which yields an experimental method to test whether or not a given clock is a standard clock. The only tools needed are light rays and freely falling particles. For this reason our method fits very well in the framework of the axiomatic approach to space-time theory given by Ehlers, Pirani, and Schild [1], where just light rays and freely falling particles are used as primitive concepts. As the underlying space-time model we use a Weyl manifold (instead of a Lorentz manifold, which is the usual model of general relativity); this generalization is motivated by [1].

Journal ArticleDOI
TL;DR: An enzyme fraction isolated from crude extracts of the fungus Tolypocladium inflatum, strain 7939/F, is able to synthesize the undecapeptide cyclosporin A, confirmed by chromatographic comparison with the authentic compound and by amino acid analyses.

Journal ArticleDOI
TL;DR: In this paper, a pentamethylcyclopentadienyl complexes (C 5 Me 5 ) 2 Lu(OC 4 H 9 -t) 2 Li(THF) 2 (7 ) and (c 5 H 5 )2 Lu(SC 4 H 8 -t ) 2 Li (THF 2 (8 ) have been determined by X-ray diffraction.

Journal ArticleDOI
TL;DR: In this paper, a correction factor for the spontaneous emission rate, which is introduced by the longitudinal field distribution within the laser cavity, was proposed. But this correction factor was not considered for index-guided semiconductor laser diodes.
Abstract: To calculate the linewidth for an index-guided semiconductor laser, one usually neglects a correction factor for the spontaneous emission rate, which is introduced by the longitudinal field distribution within the laser cavity. For FabryPerot lasers with cleaved facets the correction factor is small. However, for DFB lasers this correction factor may become quite significant, yielding a linewidth enhancement for DFB laser diodes.

Journal ArticleDOI
TL;DR: In this paper, the Eriocephalus species were investigated by high-field NMR spectroscopy and a few chemical transformations and the structures were elucidated by high field NMR.