Showing papers by "University of Hamburg published in 1982"
TL;DR: A new sawing-grinding method is described for the histological evaluation of jaw bones with teeth or bones containing implants (ceramic or metallic).
Abstract: A new sawing-grinding method is described for the histological evaluation of jaw bones with teeth or bones containing implants (ceramic or metallic). The undecalcified bone is embedded in acrylic resin and sawed at 100 to 150 micrometers. The slices are ground automatically by a special machine to a thickness of 5-10 micrometers. The usually employed staining procedures for hard plastic embedded-tissues may be used. Plaque, fillings, crowns, bridges, implants and soft tissues are preserved in situ. Macroscopic and microscopic detail of good quality is preserved for histological and morphometrical evaluation.
1,657 citations
TL;DR: Retrovirus genomes introduced into mouse zygotes by microinjection of cloned DNA, or into morula stage pre-implantation mouse embryos by infection with Moloney murine leukaemia virus, became de novo methylated and were blocked in expression.
Abstract: Retrovirus genomes introduced into mouse zygotes by microinjection of cloned DNA, or into morula stage pre-implantation mouse embryos by infection with Moloney murine leukaemia virus (M-MuLV), became de novo methylated and were blocked in expression. No restriction of virus expression and no de novo methylation were observed when post-implantation mouse embryos were infected with virus. Efficient de novo methylation activity may be an important characteristic of gene regulation in early mouse embryos.
555 citations
TL;DR: The sequence of a cDNA encoding the nonapeptide arginine vasopressin (A VP) and its carrier protein, neurophysin II (NpII) from bovine hypothalamus, proves that the 166-amino acid precursor molecule contains a signal peptide of 19 amino acids followed directly by A VP connected to NpII by a Gly-Lys-Arg sequence.
Abstract: The sequence of a cDNA encoding the nonapeptide arginine vasopressin (A VP) and its carrier protein, neurophysin II (NpII) from bovine hypothalamus, proves that the 166-amino acid precursor molecule contains a signal peptide of 19 amino acids followed directly by A VP connected to NpII by a Gly-Lys-Arg sequence. The carboxy-terminal region of the precursor contains a naturally occurring glycopolypeptide of 39 amino acids which is separated from NpII by a single arginine residue.
517 citations
TL;DR: In this paper, the authors derive localization properties of massive particle states which hold in all models of relativistic quantum theory, including gauge theories, starting from the principle of locality of observables.
Abstract: Starting from the principle of locality of observables we derive localization properties of massive particle states which hold in all models of relativistic quantum theory, including gauge theories. It turns out that particles may always be regarded as well localized distributions of matter, although their mathematical description might require the introduction of non-local (unobservable) fields, which are assigned to infinite string-like regions. In spite of the non-locality of these fields one can show that such particles obey Bose- or Fermi (para) statistics, that to each particle there exists an antiparticle and that collision states of particles exist. A selfcontained exposition of the underlying physical ideas is given in the Introduction, and some perspectives for the structure of field-theoretic models arising from our analysis are discussed in the Conclusions.
391 citations
TL;DR: In this article, the authors introduce low-molecular weight alkynyl complexes, including four-coordinate compounds, five-and sixcoordinate complexes, and polynuclear complexes of d-metal clusters.
332 citations
278 citations
TL;DR: In this article, a general formalism for multiple bremsstrahlung on the level of tree diagrams for gauge theories is presented, and extensive cancellations between Feynman diagrams are accomplished automatically.
275 citations
TL;DR: A polyhedral approximation for the volumetric description of a moving rigid object from a real-world scene is derived, based on measurements in monocular TV-frame sequences, and is compared to related ones reported in the recent literature.
218 citations
TL;DR: In this article, the helicity amplitudes for the QED processes e+e−→γγγ, μ+μ−γ, and e +e−γ were calculated in the limit of vanishing fermion masses.
193 citations
TL;DR: In this article, the authors studied the 3-dimensional pureU(1) lattice gauge theory with Villain action, which is related to the ℤ-ferromagnet by an exact duality transformation (and also to a Coulomb system).
Abstract: We study the 3-dimensional pureU(1) lattice gauge theory with Villain action which is related to the 3-dimensional ℤ-ferromagnet by an exact duality transformation (and also to a Coulomb system). We show that its string tension α is nonzero for all values of the coupling constantg2, and obeys a bound α≧const·mDβ−1 for smallag2, with β=4π2/g2 and\(m_D^2 = (2{\beta \mathord{\left/ {\vphantom {\beta a}} \right. \kern-
ulldelimiterspace} a}^3 )e^{ - \beta \upsilon _{Cb} {{(0)} \mathord{\left/ {\vphantom {{(0)} 2}} \right. \kern-
ulldelimiterspace} 2}} (a = lattice spacing)\). A continuum limita→0,mD fixed, exists and represents a scalar free field theory of massmD. The string tension αmD−2 in physical units tends to ∞ in this limit. Characteristic differences in the behaviour of the model for large and small coupling constantag2 are found. Renormalization group aspects are discussed.
187 citations
TL;DR: In this paper, the euclidean formulation of the thermodynamics for quantum spin systems was reviewed and the corresponding formalism for SU(N) gauge fields on the lattice.
TL;DR: In this paper, the authors derived a criterion which characterizes the state space of quantum electrodynamics and provided a basis for a general analysis of the infrared problem, and established the existence of asymptotic electromagnetic fields in all charge-sectors.
Abstract: Starting from the fact that electrically charged particles are massive, we derive a criterion which characterizes the state space of quantum electrodynamics This criterion clarifies the special role of the electric charge amongst the uncountably many superselection rules in quantum electrodynamics and provides a basis for a general analysis of the infrared problem Within this framework we establish the existence of asymptotic electromagnetic fields in all charge-sectors, find a general characterization of infra-particles and introduce a notion of asymptotic completeness
TL;DR: Twelve methods for analysing FCM‐histograms were compared using the same set of data and DNA histograms were measured for L‐929 cells at various times after mitotic selection.
Abstract: . Twelve methods for analysing FCM-histograms were compared using the same set of data. Some of the histograms that were analysed were simulated by computer and some were taken from experiments. Simulated data were generated assuming asynchronously growing cell populations and (i) measurement coefficients of variation (CV) from 2 to 16%; (ii) constant measurement CV or CV's increasing from G1 to G2 phase, and (iii) varying fractions of cells in each phase. Simulated data were also generated assuming synchronous cell populations in which a block in early S phase was applied and released. DNA histograms were measured for L-929 cells at various times after mitotic selection. Labelling indices were also measured for these cells at the same time.
The fractions of cells in the G1, S, and (G2+ M) phases were calculated by each analytical method and compared with the actual fractions used for simulation, or in case of experimental data, with autoradiographic results. Generally, all methods yielded reasonably accurate fractions of cells in each phase with relative errors in the range of 10–20%. However, most methods tended to overestimate G1 fractions and underestimate S fractions. In addition, variations in the shape of the S phase distribution often caused considerable errors. Phase fractions were also calculated for histograms of kinetically perturbed populations, simulated as well as experimental The errors were only slightly larger than for histograms from asynchronously growing cell populations.
TL;DR: In the presence of silver carbonate-silver perchlorate and dichloromethane-toluene as solvent, 3,4,6-tri-O -acetyl-2-azido-2,deoxy-β-d -galactopyranosyl chloride, and derivatives of l -serine and - l -threonine, gave, with high stereoselectivity, the benzyl esters of N -(benzyloxycarbonyl)-3, O -(3, 4, 6-tri)-O
TL;DR: In this article, a method for estimating the expected value of IBNR-c1aims is derived by transforming the classical multiplicative model into a two-way model of Analysis of Variance, in which easy tractable results of Mathematical Statistics can be applied.
Abstract: A method for estimating the expected value of IBNR-c1aims is derived by transforming the classical multiplicative model into a two-way model of Analysis of Variance, in which easy tractable results of Mathematical Statistics can be applied. The resulting method is shown to be strongly connected to the classical chain ladder method.
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TL;DR: The syntactic structure of sets of ancestors and sets of descendants is considered, as well as that of unions of congruence classes, taken over (infinite) context-free languages or regular sets.
TL;DR: Nitrosococcus oceanus, a strongly halophilic bacterium, had a very low tolerance to organic matter compared with other organisms tested, and nitrite formation by both Nitrosovibrio tenuis strains tested was similar.
Abstract: The effect of various organic compounds on the growth of ammonia-oxidizing bacteria was examined.Nitrosococcus oceanus, a strongly halophilic bacterium, had a very low tolerance to organic matter compared with other organisms tested. Organic compounds scarcely affected the growth of theNitrosomonas strains whereas nitrite formation by bothNitrosococcus mobilis strains was inhibited by nearly all of the substances tested. The growth ofNitrosospira strain Nsp1 was enhanced more than 30% by acetate and formate, but not growth was detectable in the presence of pyruvate. On the contrary,Nitrosospira strain Nsp5 was stimulated only by pyruvate. Nitrite formation by the twoNitrosovibrio tenuis strains tested was similar. The growth of both strains was enhanced considerably by formate and glucose; acetate and, to a greater extent, pyruvate inhibited these bacteria. In batch culture, the energy efficiency of autotrophically grown ammonia-oxidizing bacteria varied from strain to strain. The cell yield of mixotrophically grown cultures, per unit of ammonia oxidized, was increased in comparison with autotrophic ones. No heterotrophic growth was detected.
TL;DR: In this article, the analytic calculation of the Sterman-Weinberg type 3-jet cross section to order αs was presented, and the fit to recent PLUTO data gave αs which corresponds to Λ=0.24 GeV in the 1-loop approximation.
Abstract: We present in detail the analytic calculation of the Sterman-Weinberg type 3-jet cross section to order αs2 The fit to recent PLUTO data gives in the\({MS}\) scheme αs which corresponds to Λ=0.24 GeV in the 1-loop approximation.
TL;DR: Water samples collected during a spring plankton bloom in the northern North Sea were investigated for dissolved organic carbon (DOC), total dissolved sugars (TDS) and dissolved amino acids (TDAA).
TL;DR: In this paper, the data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases and neither lead nor copper seem to be remobilized to any significant extent.
Abstract: Data from mechanical concentrates of recent sediments indicate that clay minerals, clay-rich aggregates and heavy minerals are the major carriers of heavy metals in detrital sediment fractions. Hydrous Fe/Mn oxides and carbonates and sulfides, in their specific environments, are the predominant accumulative phases for heavy metals in autochthonous fractions. Sequential chemical extraction techniques permit the estimation of characteristic heavy metal bonding forms: exchangeable metal cations, easily reducible, moderately reducible, organic and residual metal fractions, whereby both diagenetic processes and the potential availability of toxic compounds can be studied. The data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases. In contrast at pH 4.4, neither lead nor copper seem to be remobilized to any significant extent. Immobilization by carbonate precipitation seems to provide an effective mechanism for the reduction of dissolved inputs qf metals such as zinc and cadmium in pH-buffered, hard water systems.
TL;DR: This chapter discusses the membrane flow via the Golgi apparatus (GA) of higher plant cells, as a large part of the intracellular transport of macromolecules takes place via dictyosomes.
Abstract: Publisher Summary This chapter discusses the membrane flow via the Golgi apparatus (GA) of higher plant cells. GA plays a significant role in membrane flow processes, as a large part of the intracellular transport of macromolecules takes place via dictyosomes. Therefore, the membranes of the GA are considered as packing material and transportation vehicles for the transfer of polysaccharides and proteins from their sites of synthesis to the plasma membrane (PM). The transfer processes constitute a membrane flow beginning at the GA or, when starting at the endoplasmic reticulum (ER), via the GA. Membrane transfer from the ER to the PM via the GA can be divided into three different phases. Those three phases are, (1) beginning at the ER and ending at the forming faces of the dictyosomes; (2) comprising the flow through the cisternal stack of the dictyosomes, and (3) extention from the maturing faces of the dictyosomes to the PM. The velocity of granulocrine secretion involves measurements based on the use of content markers; measurements based on membrane markers; and calculations derived from a morphometric analysis of thin sections. The recycling of membrane from the PM is a necessary consequence of granulocrine secretion.
TL;DR: The state of stress of an intact femur was analysed using a three-dimensional finite element model and a pair of femora was used for determination of data for the 3-D model.
TL;DR: In this article, room-temperature cw lasing at 1.061 μm has been obtained in Cr,Nd: GdScGa-garnet and threshold powers as low as 7 mW and slope efficiencies up to 41% have been measured.
Abstract: Room-temperature cw lasing at 1.061 μm has been obtained in Cr,Nd: GdScGa-garnet. Threshold powers as low as 7 mW and slope efficiencies up to 41% have been measured. Cross pumping of Nd3+ via Cr3+ is nearly as efficient as direct pumping. Time-resolved measurements of the transfer rate yield a transfer efficiency of 0.86 and an average transfer time of 17 μs. An improvement in pulsed broad band pumping can also be expected.
TL;DR: In this paper, the authors analyzed the composition of acid-hydrolyzable carbohydrates in particulate matter collected during a plankton bloom in the northern North Sea and found that the variations observed were caused by variations in the production of carbohydrates by phytoplankton and significant loss of produced carbohydrates into the dissolved fraction.
Abstract: Monosaccharide composition of acid-hydrolyzable carbohydrates was analyzed in particulate matter collected during a plankton bloom in the northern North Sea. Concentrations of total particulate carbohydrates varied from 50 nmol·liter−1 to >600, with maximum concentrations in the upper layers above 1% light depth. The monosaccharide spectra, considered in conjunction with those of dissolved carbohydrates from the same samples, suggest that the variations observed were caused by variations in the production of carbohydrates by phytoplankton and significant loss of produced carbohydrates into the dissolved fraction. Two loss phases could be discerned: first, labile glucose polymers, followed by the relatively stable structural polysaccharides.
TL;DR: In this paper, the authors demonstrate wavelength averaging of the power in either mode, permitting a simple measurement of power transfer to the cross-polarized mode as a function of fiber length, and confirm experimentally the theory of random mode coupling between the polarization modes.
Abstract: Perturbations in highly birefringent single-mode fibers couple the two polarization modes and degrade the polarization-holding ability. With a broadband source we demonstrate wavelength averaging of the power in either mode, permitting a simple measurement of the power transfer to the cross-polarized mode as a function of fiber length. Using this technique, we confirm experimentally the theory of random mode coupling between the polarization modes.
TL;DR: The relation between cell survival and the number of double-strand breaks measured 1 hour after irradiation could be described by the same function as for the three treatments applied.
Abstract: SummaryThe effect of hyperthermia on DNA strand break repair was studied in CHO cells. DNA strand breaks were analysed by the alkaline DNA-unwinding technique followed by chromatography on hydroxyapatite. Immediately after irradiation with doses ranging from 2 to 7 Gy, cells were exposed to 42 or 45°C. Heat alone was found to induce DNA strand breaks only at temperatures exceeding 45°C. In comparison to 37°C, the rate of single-strand break repair was increased by hyperthermia at 42°C, but decreased at 45°C. In contrast hyperthermia at either temperature resulted in a higher number of remaining double-strand breaks 1 hour after irradiation. For the three treatments applied, i.e. X-rays alone or combined with hyperthermia at 42 or 45°C, the relation between cell survival and the number of double-strand breaks measured 1 hour after irradiation could be described by the same function.
TL;DR: In this paper, the theory of Rayleigh functionals for non-linear eigenvalue problems T(λ) u = 0 is extended to cases where the functional is defined only on a proper subset.
Abstract: The theory of Rayleigh functionals for non-linear eigenvalue problems T(λ) u = 0 is extended to cases where the functional is defined only on a proper subset. The theory applies to problems which do not satisfy an overdamping condition and yields a minimax characterization of eigenvalues. Applications to damped free vibrations of an elastic body are discussed.
TL;DR: The three-dimensional architecture of the villous core of the chorionic villi has been studied in the human placenta throughout pregnancy by scanning electron microscopy, and compared with light microscopic and transmission electron microscopic findings.
TL;DR: In this article, experimental evidence is presented for radiative transitions of light holes accumulated in a limited area in momentum space to the heavy-hole band, and the possibility of far-infrared amplification is discussed.
Abstract: Experimental evidence is presented for radiative transitions of light holes accumulated in a limited area in momentum space to the heavy-hole band. Also reported is the observation of cyclotron resonance emission from the accumulated light holes. The possibility of far-infrared amplification is discussed.
TL;DR: There is a distinct accumulation of estrogens in the nuclei of stroma, E2 concentration being significantly higher than E1, and the hypothesis that E2 could play a preferential role in stimulating the growth of the BPH stroma is supported.
Abstract: In an earlier publication we found significantly more estrogen receptor-positive cases in the stroma if compared with the epithelium of human benign prostatic hyperplasia (BPH). We were therefore interested to find out whether this preferential assay of estrogen receptor in stroma is reflected by a higher estrogen content in this tissue fraction. Estradiol (E2) and estrone (E1) were measured by RIA in whole BPH tissue, stroma, and epithelium as well as in the nuclear fraction of stroma and epithelium. For comparison, E2 and E1 were measured in blood also. The main results are as follows: 1) In all BPH samples the E2 (26.0 +/- 3.5 (SEM) pg/g (n = 20)) and E1 (53.5 +/- 7.4 (14)) content was significantly higher than in the corresponding plasma (E2: 17.5 +/- 2.3 pg/ml (11); E1: 26.5 +/- 4.4(7)), the mean ratio of E2/E1 was 0.52 and 0.69 for BPH and plasma, respectively; 2) in stroma significantly more E2 (53.6 +/- 7.8 fmol/mg DNA (18)) and E1 (55.9 +/- 8.4 (12)) were measured than in epithelium (E2: 15.7 +/- 1.9 (16); E1: 20.7 +/- 3.2 (13)); 3) in nuclei of stroma significantly higher E2 (38.0 +/- 5.3 fmol/mg DNA (20)) and E1 (19.2 +/- 4.8 (14)) concentrations were present than in epithelium (E2: 6.8 +/- 3.1 (19); E1: 2.5 +/- 0.5 (13)), the mean ratio of E2/E1 for the nuclear fractions of stroma (2.3) and epithelium (2.7) increased dramatically if compared with the respective ratio in whole BPH tissue. In conclusion, there is a distinct accumulation of estrogens in the nuclei of stroma, E2 concentration being significantly higher than E1. These data support the hypothesis that E2 could play a preferential role in stimulating the growth of the BPH stroma.