Showing papers by "University of Cologne published in 1983"
TL;DR: In this paper, a review on the diffusion, solubility and electrical activity of 3D transition metals in silicon is given, which can be divided into two groups according to the respective enthalpy of formation of the solid solution.
Abstract: A review is given on the diffusion, solubility and electrical activity of 3d transition metals in silicon. Transition elements (especially, Cr, Mn, Fe, Co, Ni, and Cu) diffuse interstitially and stay in the interstitial site in thermal equilibrium at the diffusion temperature. The parameters of the liquidus curves are identical for the Si:Ti — Si:Ni melts, indicating comparable silicon-metal interaction for all these elements. Only Cr, Mn, and Fe could be identified in undisturbed interstitial sites after quenching, the others precipitated or formed complexes. The 3d elements can be divided into two groups according to the respective enthalpy of formation of the solid solution. The distinction can arise from different charge states of these impurities at the diffusion temperature. For the interstitial 3d atoms remaining after quenching, reliable energy levels are established from the literature and compared with recent calculations.
987 citations
TL;DR: In this paper, a review of electron spin resonance (ESR)-based dating is presented, which is based on the direct measurement of the amount of radiation-induced paramagnetic electrons trapped in crystal defects.
168 citations
TL;DR: Chromenes (benzopyrans) and benzofurans are characteristic natural products of certain tribes of the Asteraceae and a review of recent findings can be found in this article.
158 citations
TL;DR: In this article, the ground states of droplets of $N$ atoms of $^{4}\mathrm{He}$ were calculated using variational Monte Carlo and Green's function Monte Carlo methods.
Abstract: Quantum mechanical calculations of the ground states of droplets of $N$ atoms of $^{4}\mathrm{He}$ are reported. The calculations have been made by the variational Monte Carlo method for $4l~Nl~728$ and by the Green's function Monte Carlo method for $3l~Nl~112$. The energies, rms radii, and density distributions are reported; liquid-drop fits to the energies and radii are discussed.
147 citations
TL;DR: In this article, age data for about 660 speleothems and about 140 spring-deposited travertines were collected, including many unpublished results, and plotted as histograms and also as error-weighted frequency curves on a 350,000-yr scale.
138 citations
TL;DR: Computational tests with quadratic assignment problems (QAP) showed that it finds very good suboptimal solutions in moderate time and behaves computationally stable.
137 citations
TL;DR: Viral DNA replication or transcription could not be detected by blotting and nucleic acid hybridization experiments using nick-translated, cloned viral probes, and there was no evidence for the persistence of viral DNA or of fragments of viralDNA in mass cultures of mammalian cells.
131 citations
TL;DR: In this paper, the behavior of chemisorbed CO on the hexagonal Co(0001) surface as a function of coverage, temperature, and CO partial pressure was studied.
Abstract: Angle-resolved photoemission with synchrotron radiation, low-energy electron diffraction, and x-ray photoelectron spectroscopy have been combined to study the behavior of chemisorbed CO on the hexagonal Co(0001) surface as a function of coverage, temperature, and CO partial pressure. The band structure was measured for the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$ (coverage $\ensuremath{\bigominus}=\frac{1}{3}$ monolayer) and the $(2\sqrt{3}\ifmmode\times\else\texttimes\fi{}2\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$ ($\ensuremath{\bigominus}=\frac{7}{12}$ monolayer) phases. The results are compared to tight-binding calculations and show that hybridization effects for the $5\ensuremath{\sigma}$ and $1\ensuremath{\pi}$ bands and orbital mixing are important. The photoemission cross sections (shape resonances) are found to be significantly different for the high- and low-temperature phases.
110 citations
TL;DR: The distribution of 5-mC in hamster cell DNA appears to be nonrandom in that different 5'-CpG-3'-containing restriction sites are methylated to different extents and thus can be used routinely for DNA hydrolysis.
94 citations
TL;DR: The structure of the Shrunken (Sh) locus in a strain containing an unstable recessive mutation, sh-m5933, caused by the transposable controlling element Dissociation (Ds), is analyzed and nine spontaneous Sh revertant alleles are analyzed.
TL;DR: In this paper, an approximation of the one particle spectrum of the Anderson model with time ordered perturbation is presented. The approximation includes all processes without crossing band electron lines and does not make use of the Brillouin-Wigner scheme.
Abstract: An investigation of the one particle spectrum of the (impurity-) Anderson model within the time ordered perturbation approach is presented. The approximation used includes all processes without crossing band electron lines and does not make use of the Brillouin-Wigner scheme. Foregoing treatments are thus generalized in essential points. Local self energies are determined by two coupled integral equations which are solved numerically. Numerical procedures and the validity of the approximation are thoroughly tested for the resonant level model, which deals with only one spin component and is exactly solvable. Calculated spectra for the Anderson model in all regimes of temperature and of local level position are discussed. A remarkable improvement over earlier attempts is found. Connection to the resonant level model is made by analytical continuation in the number of spin components. The approximation is placed into a general context of a conserved skeleton diagram expansion. It is pointed out how it can systematically be improved, and some exact formulas are derived.
TL;DR: In this paper, the Fourier transform spectra and the diode laser spectra of the ν2 band of 14NH3 have been measured with 0.005 and 0.002 cm−1 resolution, respectively.
TL;DR: In contrast to some earlier studies, good agreement has been found between the asymptotic random-walk exponent for particles restricted to the occupied sites of a simplecubic lattice, and the dynamical scaling prediction of Gefen, Aharony, and Alexander as mentioned in this paper.
Abstract: In contrast to some earlier studies, good agreement has been found between the asymptotic random-walk exponent for particles restricted to the occupied sites of a simplecubic lattice, and the dynamical scaling prediction of Gefen, Aharony, and Alexander. For the first time, up to ${10}^{7}$ steps were used in the Monte Carlo study, which moreover employed larger lattices (${180}^{3}$) than earlier studies.
TL;DR: This analysis revealed that the protraction of middle and rear legs is guided by the ipsilateral front and middle legs respectively, and inter- and intrasegmental control functions are revealed.
Abstract: Continuous measurements of anterior-posterior leg position recorded from stick insects walking on a wheel were tested for relationships among spatial and temporal parameters of leg coordination. This analysis revealed that the protraction of middle and rear legs is guided by the ipsilateral front and middle legs respectively. Protraction endpoint for each rear leg shows a significant positive correlation with the simultaneous position of the ipsilateral middle leg (Figs 1,2; Table 1). An analogous, but somewhat weaker, correlation exists between the protraction endpoint of each middle leg and the position of the ipsilateral front leg. This coordination of spatial parameters was tested experimentally by manipulating the position of the forward leg. When a middle leg is restrained in various positions, the ipsilateral rear leg adjusts its protraction endpoint accordingly (Fig. 3). However, its retraction endpoint does not undergo parallel shifts; consequently, step amplitude, protraction duration, and step frequency all change as a function of middle leg position. When a sinusoidal movement is imposed on either a middle or front leg, the adjacent, caudal leg continuously adjusts its protraction endpoint according to the momentary position of the forward leg (Fig. 4). This adjustment is again accompanied by changes in step amplitude and step period, changes which may affect all five unrestrained legs. The anterior-posterior leg position measured in our experiments primarily reflects the angle of the coxo-thoracic joint; this angle is monitored by hair rows and hairplates located on the coxa (Wendler, 1964; Baessler, 1965). Modifying these external proprioceptive inputs revealed both inter- and intrasegmental control functions. The caudally situated hair rows are important for measuring the small variations in the position of the target leg which occur during normal walking. Immobilization of these hairs on a middle leg causes the mean protraction endpoint of the ipsilateral rear leg to shift forward (Fig. 5: o1 versus C) and reduces or eliminates the step by step correlation of this protraction endpoint with middle leg position (Table 1). The additional immobilization of the cranially situated hairplates usually leads to a caudal shift in the protraction endpoint of the ipsilateral rear leg (Fig. 5: o2 versus o1) and reduces any residual correlation (Table 1). The actual position of the protraction endpoint reflects an integration of intersegmental signals representing the position of the target leg and intrasegmental signals from the sensory hairs on the protracting leg. Both operations may affect the duration of protraction in both the operated target leg and the adjacent, caudal leg.
TL;DR: Obvious sequence specificities at the sites of insertion have so far not been found in the adenovirus, SV40, or polyoma virus system.
Abstract: The integration of adenovirus DNA into host cell DNA was studied in considerable detail in abortively and productively infected cells, as well as in transformed and tumor cells induced by human adenoviruses (for a review see Doerfler 1982). More than 70 different adenovirus-transformed cell lines and tumor cell lines from adenovirus-induced tumors exhibited non-indentical patterns of viral DNA insertion into the host genome. In this context harmster, mouse, and rat systems were investigated From these studies, there was no evidence for highly specific sites of viral DNA inserion into the cellular genome as judged by the results of Southern blotting analyses. Of course, intergratiom patterns in established transformed or tumor cell lines could have been modified by postintergrational alterations, such as rearrangements, amplifications, or partial deletions, and thus possible specificities could have been obscured. On the other hand, in several in stances it could be demonstrated that the cellular nucleotide sequences at the sites of junction were not altered (Gahlmann et al. 1982; Stabel and Doerfler 1982; Gahlmann and Doerfler? 1983). Obvious sequence specificities at the sites of insertion have so far not been found in the adenovirus, SV40, or polyoma virus system.
TL;DR: Research in quantitative international politics and peace science is dominated by two puzzles and their corresponding research designs as discussed by the authors : Why some nations fight wars more often than others, and why some nations choose to commit war more frequently than others.
Abstract: Research in quantitative international politics and peace science is dominated by two puzzles and their corresponding research designs. (1) Why do some nations fight wars more often than others? (2...
TL;DR: The main result of the study appears to be that the in vitro model predicted a greater effectiveness of the disinfectant than was observed in vivo both in the "hand' test and the "finger' test, although some differences were noted between these tests.
TL;DR: In this article, a simple model of U redistribution processes in geologic systems based on 238U-series disequilibria is developed and applied to the samples investigated, and some implications for γ-radiometric field methods are discussed.
TL;DR: The population of HLA-A2-positive individuals, currently considered serologically homogeneous, can be divided into three subtypes on the basis of antigen recognition by various HLA's specific cytotoxic T lymphocytes, which are found to be distinct.
Abstract: The population of HLA-A2-positive individuals, currently considered serologically homogeneous, can be divided into three subtypes on the basis of antigen recognition by various HLA-A2-specific cytotoxic T lymphocytes (CTLs). When these three types of HLA-A2 antigens were analyzed biochemically, they were found to be distinct. Isoelectric focusing (IEF) of HLA antigens digested with neuraminidase (NANAse) suggested that the difference(s) reside in the polypeptide backbone of the HLA-A2 heavy chain. Biochemical analysis distinguishes three distinct categories of HLA-A2 antigens: (1) a major subtype, designated HLA-A2.I, (2) a minor subtype, designated HLA-A2.II, possessing a more basic isoelectric point (IEP) and (3) a minor HLA-A2 subtype more acidic in its IEP than HLA-A2.I, designated HLA-A2.III. A fourth HLA-A2 subtype could be defined by discordance between cell-mediated lympholysis (CML) typing and biochemical analysis. The latter HLA-A2 antigen was defined as a variant by CTL, but was biochemically indistinguishable from the major subtype HLA-A2.I.
TL;DR: It is demonstrated that the sugar-binding domains of the Lac and Gal repressors are homologous with the Sugar- binding domains of three periplasmic proteins.
Abstract: Many proteins consist of several independent folding units or domains, each specifying a different function. Repressor proteins such as Lac or lambda cI carry small N-terminal domains which recognize DNA sequences and larger C-terminal domains which are required for effector recognition and/or oligomerization. The native periplasmic metabolite-binding proteins consist of short membrane-recognizing signal sequences and larger C-terminal metabolite-binding domains which also recognize membrane-bound proteins involved in transport and chemotaxis. The DNA-recognizing domains of many repressors are homologous, as are the sugar-recognizing periplasmic proteins. Here I demonstrate that the sugar-binding domains of the Lac and Gal repressors are homologous with the sugar-binding domains of three periplasmic proteins.
01 Dec 1983-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: High speed film analysis to investigate the head nodding movement during tethered flight inLocusta shows that the position of the wind-sensitive head hairs with respect to the flight direction is altered by 5.5° in the rhythm of the wing beat.
Abstract: 1.
Using high speed film analysis (500 frames/s) to investigate the head nodding movement during tethered flight inLocusta shows that the position of the wind-sensitive head hairs with respect to the flight direction is altered by 5.5° in the rhythm of the wing beat (Fig. 2).
2.
Wind measurements in the region of the hair fields demonstrate that the wind reaching the hairs during flight is modulated by the animal's own wing beat. The modulation has a peak-to-peak value of 0.6–1.0 m/s (Fig. 3).
3.
An airstream with its speed modulated by these values was used to stimulate the wind-sensitive hairs to analyse the steady-state response during tethered flight in animals with the antennae removed (Fig. 1). In these entrainment experiments absolute coordination (a relation of locked phase) between the wind modulation and the flight oscillator is found in a range of about 3 Hz around the intrinsic flight frequency. At frequencies both above and below this range, relative coordination (a relation of preferred phase) is obtained (Figs. 4–7).
4.
The dynamic response to step changes in the modulation frequency was tested. There is an immediate reaction, but it takes several wing beats to reach the new steady-state (Fig. 8).
5.
When flight was elicited while a modulated wind stream was already blowing, the first wing beat occurred in a preferred phase with respect to the stimulus modulation (Figs. 10 and 11).
6.
To understand the generation of the flight pattern, the whole flight oscillator must be considered as a cooperative system of central neuronal, sensory (proprioceptive) and mechanical components (Fig. 12).
TL;DR: The NCI‐proposed New Working Formulation for Clinical Usage is recommended as practical and unprejudicing classification scheme for general application; however, its usefulness as tool for translating one classification scheme into another appears limited.
Abstract: Two hundred thirty cases of malignant non-Hodgkin's lymphomas were reclassified in a retrospective study according to the New Working Formulation for Clinical Usage of the NCI as compared to the Rappaport and Kiel classifications. The reproducibility for the individual schemes this study was 81% (Rappaport), 79% (Kiel), and 85% (New Working Formulation). In keeping with the results of the NCI international study, all lymphomas were subdivided into 3 prognostic groups: (1) low-grade malignancy (6.0 years median survival); (2) intermediate-grade malignancy (3.5 years median survival); and (3) high-grade malignancy (1.4 years median survival). The NCI-proposed New Working Formulation for Clinical Usage is thus recommended as practical and unprejudicing classification scheme for general application; however, its usefulness as tool for translating one classification scheme into another appears limited.
TL;DR: In this paper, the Brillouin-Wigner scheme is critically investigated and a more general method developed for summation methods for diagrams in infinite order, and a new set of integral equations is derived.
Abstract: Systems with two kinds of electrons, one localized and strongly correlated, the other in extended band states, require unconventional perturbational concepts. The application of time ordered perturbation expansions with respect to hybridization is studied. The Brillouin-Wigner scheme is critically investigated and a more general method developed. Particular care is devoted to a discussion of summation methods for diagrams in infinite order, and a new set of integral equations is derived. These avoid explicit regularization procedures and lend themselves naturally to investigations of the Kondo-and Intermediate Valence-regimes. Some general expressions for partition fuction and local Green's function of the impurity problem are studied and related to theT-matrix of compounds. Two exactly solvable cases, the resonant level model and the limit of zero bandwidth, serve as examples and guides for approximations.
TL;DR: The association of the alcyonarian Heteroxenia fuscescens (Ehrb.) with its cytosymbiotic algae shows structural and physiological adaptations optimizing the living together of the two partners as one functional unit.
Abstract: The association of the alcyonarian Heteroxenia fuscescens (Ehrb.) with its cytosymbiotic algae shows structural and physiological adaptations optimizing the living together of the two partners as one functional unit. To enhance the energetic contribution of the autotrophic partner, the organization of the heterotrophic partner bears typical plant-like imprints. Up to 20% of the inorganic C photosynthetically fixed was translocated to the host (=2 mg C mg d.w.-1 d-1). This net C gain by the host is used for anabolic purposes including the deposition of storage material. Especially the wax-esters and triglycerides of the host-in contrast to those of the symbionts-were intensively labelled. The in-vivo14C-fixation of zooxanthellae is more than double the in-vitro fixation. In both symbionts and host, the lipids show the highest relative 14C-incorporation. In particular the polyol component was strongly labelled. After 120 min of continuous incubation, approximately 40 labelled intracellular metabolites were detectable in the ethanol/water soluble fractions of zooxanthellae. Glycerol is the main low-molecular weight carbohydrate being transferred. This is corroborated by the deacylation of lipids of the host.
01 Jan 1983
TL;DR: In this article, the authors describe the formation of the extremely LIL-element-enriched phonolite magmas by fractionation of olivine, clinopyroxene, phlogopite and, in more differentiated magmas, sphene, amphibole, apatite, magnetite, joined by feldspar and feldspathoids.
Abstract: The Quaternary (ca. 0.7 Ma) volcanic fields in the western central part of the Rhenish Massif (West Eifel and East Eifel) have formed roughly synchronously with the main Quaternary phase of uplift The fields are 50 and 30 km long, elongated in NW-SE direction, contain ca. 240 and 90 volcanoes and are dominantly made of K-rich nephelinitic-leucititic-basanitic scoria cones. The larger West Eifel differs from the East Eifel field by more mafic and silica-undersaturated magmas, greater abundance and larger size of peridotite xenoliths and near absence of highly differentiated magmas contrasted with the occurrence of four highly differentiated phonolite volcanoes in the smaller East Eifel field. Two major groups of primitive magmas generated in different mantle reservoirs were erupted in both fields, basanites and nephelinites-leucitites. Differentiation was accomplished dominantly by fractionation of olivine, clinopyroxene, phlogopite and, in more differentiated magmas, sphene, amphibole, apatite, magnetite, joined by feldspar and feldspathoids in highly derivative magmas. Diffusion-controlled processes may have led to the formation of the extremely LIL-element-enriched phonolite magmas.
TL;DR: A D-galactose-specific lectin I was extracted from the sponge Geodia cydonium and purified by affinity chromatography and showed that it is a trimer composed of three different subunits, two of the three subunits are linked by one disulfide bond.
Abstract: A d-galactose-specific lectin I was extracted from the sponge Geodia cydonium and purified by affinity chromatography. The molecular weight of lectin I as determined by high-pressure liquid gel chromatography, was found to be 36500 ± 1300. Disc gel electrophoresis in the presence and in the absence of sodium dodecyl sulfate showed that lectin I is a trimer composed of three different subunits (Mr: 13800, 13000 and 12200); two of the three subunits are linked by one disulfide bond. Isoelectric focusing gave a pI of 5.6 for the native molecule and a pI of 4.4 and of 7.4 for the subunits. The three subunits carry carbohydrate side chains, composed of d-galactose (94%) and of arabinose (5%). Based on experiments with lectins, the terminal d-galactose residues are bound by β16 and/or β14 glycosidic linkages. The Geodia lectin I contains, besides two carbohydrate recognition sites, at least one receptor site for a second lectin I molecule.