Showing papers by "University of Cologne published in 1985"
TL;DR: Comparison of the deep-level transient spectroscopy (DLTS) and EPR results allowed tentative identification of the different DLTS lines with particular EPR spectra, and thus conclusions about the microscopic models for different defects were reached.
Abstract: Energy levels of defect states introduced by plastic deformation of n-type silicon have been studied by capacitance transient spectroscopy. From the observed properties of the defects, it is concluded that two different types of defects are produced. The first type is interpreted as point defects located in the vicinity of, or inside, dislocations. These deep-level defects have been analyzed in a model involving level broadening due to strain fields and/or defect interaction. The analysis gives information on thermal emission rates, capture cross sections, ionization energies, and deep-level broadenings. In addition, this analysis allows for the determination of accurate defect concentrations. From the improved concentration measurements it has been possible to determine the dependence of the repulsive potential (responsible for the unusual capture mechanism) on the filling times during the capture process. The second type of defects seems to be directly related to dislocations, but their physical properties could not be determined unambiguously. Comparison of the deep-level transient spectroscopy (DLTS) and EPR results allowed tentative identification of the different DLTS lines with particular EPR spectra, and thus conclusions about the microscopic models for different defects. The quantitative comparison of defect concentrations measured by DLTS and EPR also suggests that in strongly deformed silicon, part of the EPR lines might be broadened due to imperfections in the lattice surrounding the paramagnetic center.
266 citations
203 citations
TL;DR: In this article, an extensive region of nuclei near A = 130 resembling the O(6) symmetry of the IBA is presented, and other similarities between these two regions are found, in particular, a common relation of the energy scales of the O (6) and O(5) groups.
201 citations
TL;DR: The International Satellite Cloud Climatology Project (ISCCP) project as discussed by the authors conducted a pilot study initiated in late 1981 to evaluate currently available cloud analysis algorithms, which focused on the most fundamental step of any cloud algorithm, namely cloud detection.
Abstract: Research related to the International Satellite Cloud Climatology Project (ISCCP) began with a pilot study initiated in late 1981 to evaluate currently available cloud analysis algorithms. Other objectives of this study are related to a test of the effects of data volume compression schemes and the design of the operational algorithms for ISCCP. The present paper summarizes the pilot study by focusing on the most fundamental step of any cloud algorithm, that of cloud detection. An outline is provided of the objectives and limitations of the pilot study, and a description is given of the criteria used to design the operational analysis algorithm. Attention is given to the pilot study data set, a cloud detection intercomparison, a cloud analysis, and ISCCP cloud algorithm design.
196 citations
TL;DR: Some of the migrant species found there have probably terminated their migration whereas other species do only stopover for fattening and do in fact continue their migration if they have restored sufficient fat for a further flight.
Abstract: 1. Data on body weight, fat score and length of stopover of Palaearctic passerine migrants trapped at two sites in the central Algerian Sahara in autumn 1983 are presented. 2. Birds found grounded in oases were in good condition. They were not critically short of fat reserves. 3. Some of the migrant species found there have probably terminated their migration whereas other species do only stopover for fattening and do in fact continue their migration if they have restored sufficient fat for a further flight. 4. The daily activity pattern of caged migrants depended on their fat reserves. 5. The available food supplies were high enough for fattening.
183 citations
01 Apr 1985
TL;DR: The pattern of cell proliferation and cell movements in Drosophila embryogenesis has been analyzed with the aim of constructing a blastoderm fate map as mentioned in this paper, and three mitotic waves affect the embryonic cells according to a constant spatio-temporal pattern.
Abstract: The pattern of cell proliferation and cell movements inDrosophila embryogenesis has been analysed with the aim of constructing a blastoderm fate map. Post-blastoderm cell proliferation starts at gastrulation and ends around the stage of germ band shortening. Three mitotic waves affect the embryonic cells according to a constant spatio-temporal pattern. For any of these waves mitotic activity starts at well-defined loci, which have been called mitotic centres. During the first and second mitotic waves all cells undergo mitosis, except for those of the amnioserosa, which do not proliferate at all. The third wave spares most of the ectodermal cells. Neuroblasts, progenitors of epidermal sensilla and germ line cells show their own, different pattern of proliferation.
182 citations
TL;DR: Eight monoclonal antibodies from the primary response of C57BLJ6 mice against the hapten (4‐hydroxy‐3‐nitrophenyl)acetyl (NP) were isolated and Sequence analysis at the level of mRNA reveals that all antibodies express the VH gene 186.2 and all but one the DF116.1 gene segment.
Abstract: Eight monoclonal antibodies from the primary response of C57BL/6 mice against the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) were isolated. The antibodies carry lambda 1 light chains and have similar affinities for the immunizing hapten. Sequence analysis at the level of mRNA reveals that all antibodies express the VH gene 186.2 and all but one the DFl 16.1 gene segment. The J segment of the heavy chain is JH2 in six cases and JH4 in two. Somatic point mutations are scarcely detectable in the antibodies, but there is extensive sequence variability at the boundaries of the D gene segment, mainly at its 5' end. However, seven of eight antibodies express tyrosine in position 99 of the heavy chain, encoded either by the 5' codon of DFl 16.1 or by presumed N sequences. In the former case, the tyrosine is the first of a stretch of three (positions 99-101). In the latter, a similar stretch (positions 99, 101, 102) is interrupted by aspartic acid, asparagine or cysteine in position 100. These variations profoundly affect idiotypic specificity. Six of the eight monoclonal antibodies came from mice neonatally suppressed by an anti-idiotope antibody whose target idiotope is regularly expressed in primary anti-NP responses and depends upon a non-germ-line-encoded aspartic acid in position 100 of the heavy chain. The sequence data show that the mice circumvent suppression by expressing antibodies which lack this aspartic acid but are otherwise structurally very similar to anti-NP antibodies from normal animals. Since suppression in the animals is partly controlled by regulatory T cells, we conclude that these T cells are highly restricted in their specificity in that they preferentially see a determinant which also depends upon the aspartic acid in position 100. The data suggest that the VH to D boundary serves as a target of idiotypic selection.
181 citations
TL;DR: The stability of the exterior Kerr-Newman spacetime to high-frequency perturbations is investigated and modes indicate that the external Kerr- newman geometry is stable in the eikonal approximation.
Abstract: The stability of the exterior Kerr-Newman spacetime to high-frequency perturbations is investigated. The complex frequencies associated with the oscillations of a charged rotating black hole are determined for the perturbation angular momentum parameters j = Vertical BarmVertical Bar>>1. The results are extended to j> or =Vertical BarmVertical Bar>>1 for slowly rotating black holes. These modes indicate that the exterior Kerr-Newman geometry is stable in the eikonal approximation.
173 citations
TL;DR: Evolutionarily stable sets are introduced, i.e. sets of equilibrium strategies (EQS) which have much of the properties of an ESS, primarily used with evolutionary game models that allow a continuum of EQSs, but also include common ESSs as a special case.
Abstract: As an extension of the concept of an evolutionarily stable strategy (ESS) evolutionarily stable sets are introduced, i.e. sets of equilibrium strategies (EQS) which have much of the properties of an ESS. They are primarily used with evolutionary game models that allow a continuum of EQSs, none of which can be an ESS, but also include common ESSs as a special case. For a large class even of nonlinear models it can be shown that the standard dynamics converge towards some equilibrium point in an ES set if started within a neighbourhood of the set. Important applications of ES sets include e.g. mixed-strategist models and evolutionary game models in sexual populations.
164 citations
TL;DR: In this article, the authors studied the systematics of the nuclear phase transitional regions near A = 100, 130, 150 and 190 from the standpoint of the valence nucleon product N p N n.
156 citations
TL;DR: The results support the concept of size-dependent radial distribution of particles in flow of mixed suspensions and serve to explain WBC margination in microvessels in terms of a hydrodynamic phenomenon resulting from red cell/white cell interaction.
TL;DR: The results establish that gene 4 from the T‐region of octopine and nopaline Ti plasmids codes for an enzyme of cytokinin biosynthesis, and no comparable enzyme activity or immunoreactive protein was detected in cytokininsautotrophic, T‐DNA free tobacco cells.
Abstract: Gene 4 from the T-region of Ti plasmids is responsible for cytokinin effects in crown gall cells; we investigated whether it codes for an enzyme of hormone biosynthesis. In a first set of experiments, gene 4 from octopine plasmid pTiAch5 and nopaline plasmid pTiC58 was expressed in Escherichia coli, and the gene products were identified by reaction with antiserum raised against a decapeptide derived from the DNA sequence of the gene. Extracts from cells expressing the gene contained high isopentenyl-transferase activity catalyzing the formation of N6-(2-isopentenyl)adenosine from 5'-AMP and 2-isopentenylpyrophosphate. The cytokinin was identified by sequential h.p.l.c. chromatography and mass spectrometry. In a second set of experiments it was shown that crown gall cells contained isopentenyltransferase activity and a protein of mol. wt. 27 000 which was identified as the product of gene 4 by reaction with the antiserum. Isopentenyltransferase activity was specifically inhibited by the antiserum. No comparable enzyme activity or immunoreactive protein was detected in cytokinin-autotrophic, T-DNA free tobacco cells. The results establish that gene 4 from the T-region of octopine and nopaline Ti plasmids codes for an enzyme of cytokinin biosynthesis.
TL;DR: Interactions of the loci N, Dl and E(spl) among each other and with another locus (H), by means of increasing and decreasing the number of wild-type copies of one of these genes in the presence of mutations in another one, reveal functional community which exists among these neurogenic loci.
Abstract: A number of genetic loci, called neurogenic, have been found to be involved in directing the segregation of neural and epidermal lineages within the ectodermal germ layer of Drosophila melanogaster. With the aim of understanding the regulation of this developmental function we have studied interactions of the loci N, Dl and E(spl) among each other and with another locus (H), by means of increasing and decreasing the number of wild-type copies of one of these genes in the presence of mutations in another one. The results reveal functional community which exists among these neurogenic loci. E(spl) overlaps functionally with both N and Dl because genotypes involving only one copy of E(spl)+ and either an N or Dl mutation are lethal. Furthermore the normal H+ allele behaves as if it represses the activity of the 3 neurogenic loci; and, whereas E(spl) seems to be a close target of H repressing action, the influence of H upon the other two seems to be indirect.
TL;DR: In this article, the exclusive validity of the statistical interpretation of the uncertainty relations is questioned and an individualistic interpretation, formulated by means of the concept of unsharp observables, is justified through a model of a joint measurement of position and momentum.
Abstract: This paper concerns derivations and interpretations of the uncertainty relations. The exclusive validity of the statistical interpretation is called into question. An individualistic interpretation, formulated by means of the concept of unsharp observables, is justified through a model of a joint measurement of position and momentum.
TL;DR: VH‐gene expression in hybridomas derived from lipopolysaccharide‐activated B cells was analyzed and it appears that the latter essentially represent the Vn‐ gene cluster of the mouse.
Abstract: VH-gene expression in hybridomas derived from lipopolysaccharide-activated B cells was analyzed. Isolated cytoplasmic RNA was hybridized to probes representing the 9 known VH-gene groups or subjected to mRNA sequencing. In the collection of hybridomas VH genes of all 9 groups are expressed at frequencies which in most correlate reasonably well with the relative complexities of the groups. In 51 out of 54 RNA samples VH-gene transcripts could be identified and corresponded to one of the known VH-gene groups. It therefore appears that the latter essentially represent the VH-gene cluster of the mouse.
TL;DR: The analysis of mutations in these genes has led to hypotheses about the commitment of the neurogenic ectoderm and of the neural progenitors in Drosophila.
TL;DR: In this paper, a shell-model interpretation of both the occurrence of low-lying intruder states in certain mass regions and the onset of stable deformation in the ground state in others, is obtained.
TL;DR: In this article, the leading terms of an effective Hamiltonian for a linear molecule in a given vibrational state are presented up to κ 10 T v order of magnitude, whereby higher-order l-dependent terms such as H 12.0, H 8.2, and H 7.2 have been neglected because in spectroscopic application they are of minor importance.
TL;DR: During premigratory fattening, both in “autumn” and “spring”, food intake and utilization were significantly higher than during the low body weight prefattening periods of the garden warbler.
Abstract: 1
Intake of food, fat, protein and carbohydrates and their fecal output were recorded during the annual body weight cycle of the garden warbler, and old-world longdistance migratory bird species, and the efficiencies of food and nutrient utilization, defined as the ratio (intake-fecal output)/intake, were calculated.
2.
Gross food intake and food and nutrient utilization differed significantly between different phases of the birds' body weight cycle.
3.
During premigratory fattening, both in “autumn” and “spring”, food intake and utilization of fat, protein and carbohydrates were significantly higher than during the low body weight prefattening periods.
4.
The increase in efficiency of nutrient utilization accounted for about 1/3 and the increase in gross food intake about 2/3 of all surplus energy for hyperlipogenesis in the premigratory periods of the garden warbler.
5.
The seasonal changes in efficiency of food and nutrient utilization seem to be driven by a circannual timing mechanism.
TL;DR: In this article, a deconvolution technique for valence determination from mixed-valent L III -spectra is described, and it is shown that from L III-spectra valence numbers can be read separately from hybridization and non-linear volume effects.
TL;DR: In this paper, it was shown that the empirical deviations from the O(6) limit of the IBA in the Pt and Xe, Ba regions are nearly identical and that both can be interpreted very simply by introducing explicitly triaxial degrees of freedom via an additional cubic interaction in the hamiltonian, which simultaneously improves the energy staggering in the γ-band, the energy of the first excited 0 + state, and the spacings among high ρ-states.
TL;DR: The copper-catalyzed oxidation of peptides and proteins by phosphomolybdic/phosphotungstic acid (Folin phenol reagent) was studied with respect to redox stoichiometry of color formation and nature of the oxidation products.
TL;DR: In this paper, a detailed hybrid model analysis was performed using the recent code ALICE LIVERMORE 82, which in contrast to earlier formulations of the model takes into account experimental mass data, multiple preequilibrium nucleon emission and non-integer initial excitation numbers.
TL;DR: Isolated cells of Saccharomyces cerevisiae were mated by micromanipulation and the reproductive capacity of the resulting zygotes was determined: the mating frequency was dependent on the age of the parents: conjugations between young cells and cells which had completed more than two thirds of their life-span were very rare events.
Abstract: Isolated cells of Saccharomyces cerevisiae were mated by micromanipulation and the reproductive capacity of the resulting zygotes was determined. The mating frequency was dependent on the age of the parents: conjugations between young cells and cells which had completed more than two thirds of their life-span were very rare events. The life-span of a zygote was very similar to the life-span of its shorter-lived parent. If one of the parent cells had budded several times prior to fusion, the life-span of the zygote was reduced correspondingly, i.e. there was no 'rescue by hybridization.' In four crosses the distribution of buds on both of the parent cells was recorded. In three of these four crosses the buds were evenly distributed, and in one the alpha-parent had three times as many buds as the a-parent.
TL;DR: Rat and mouse complementary DNA and genomic clones encoding the thy-1 molecule have been isolated and sequenced and revealed the existence of a sequence which would encode an extra segment (31 amino acids) at the carboxyl terminus of the thy -1 molecule.
Abstract: The mode of integration of the glycoprotein thy-1 within the cell membrane has been controversial due to an apparent lack of a transmembrane hydrophobic segment Rat and mouse complementary DNA and genomic clones encoding the thy-1 molecule have been isolated and sequenced These studies have enabled us to determine the intron-exon organization of the thy-1 gene Furthermore, they have revealed the existence of a sequence which would encode an extra segment (31 amino acids) at the carboxyl terminus of the thy-1 molecule These extra amino acids include a 20-amino acid hydrophobic segment which may be responsible for integration of thy-1 within the plasma membrane
TL;DR: Two major pathways of eicosanoid production have been demonstrated in endothelial cells, yielding significant amounts of prostacyclin (PGI2), PGE2, PGF2α, thromboxane A2, leukotrienes and a number of hydroxy fatty acids.
Abstract: Endothelial cells are an important source of eicosanoid formation in the cardiovascular systems. All major pathways of eicosanoid production have been demonstrated in endothelial cells, yielding significant amounts of prostacyclin (PGI2), PGE2, PGF2α, thromboxane A2, leukotrienes and a number of hydroxy fatty acids. The regulation of eicosanoid formation by endothelial cells is poorly understood. There is evidence that precursors, such as arachidonic acid or prostaglandin endoperoxides, may also be provided by other cell types. Endothelial cell-derived eicosanoids are involved in the regulation of local vessel tone, intravascular platelet activation, cell locomotion and, eventually, cell proliferation. Most of the available information considers PGI2. This compound is the quantitatively dominating eicosanoid in endothelial cells. Major actions of PGI2 include inhibition of platelet activation and aggregation, relaxation of arterial vessels and inhibition of growth-factor release. There is probably a tight interaction with other biologically active mediators which needs further evaluation. This also applies to the clinical significance of eicosanoid-related pathways for the mechanism of action of cardiovascular drugs, such as organic nitrates or acetylsalicylic acid. The unique property of the cicosanoid system to become activated only in response to stimulation, the local nature of this reaction, the multiplicity of products formed and the short half-time of most of them are currently the most significant obstacles to define the role of endothelial cell-derived eicosanoids in clinical practice.
TL;DR: In this article, the authors derived analytical results on the dynamics of the degenerate Anderson model at zero-temperature and showed the existence of an inelastic peak in the dynamical susceptibility and that of the asymmetry in the density of states of local electrons.
TL;DR: A bioluminescent method for measuring the number of bacteria attached to synthetic polymers was developed with strains of S. epidermidis and S. aureus and was optimized with respect to extraction of bacterial ATP and time of incubation of synthetic polymer with bacterial strains.
TL;DR: An antibody mutant is described that has fully retained antigen-binding specificity but has lost or drastically changed all V-region antigenic determinants (idiotopes) of the wild type as defined by monoclonal anti-idiotope antibodies.
Abstract: In proliferating B lymphocytes, somatic mutation of rearranged antibody variable (V)-region genes occurs at high frequency and may have a key role in the selection of these cells. It is of interest in this context to learn in which way single mutations can affect antigen binding and/or idiotypic specificity of an antibody. Previous investigations have analysed spontaneous mutants of myeloma and hybridoma cells in which the mutation affected the antigen-binding specificity of the antibody. Here we describe an antibody mutant that has fully retained antigen-binding specificity but has lost or drastically changed all V-region antigenic determinants (idiotopes) of the wild type as defined by monoclonal anti-idiotope antibodies. The mutant phenotype is generated by a glycine to arginine exchange in the middle of the diversity (D) element, at position 103 of the heavy chain.