Showing papers by "Humboldt University of Berlin published in 1986"

Renormalization of Path Ordered Phase Factors and Related Hadron Operators in Gauge Field Theories

Abstract: We give a review of the renormalization and short distance properties of path ordered phase factors in nonabelian gauge field theories. It includes nonlocal gauge invariant meson, baryon and gluonium operators constructed with the help of such phase factors. Furthermore, the renormalization properties of functional derivatives of phase factors as they are needed in dynamical equations are considered. The discussion is based on an one dimensional auxiliary field formalism which enables the application of the usual language of local Green's functions.

Quantification of ATP-producing and consuming processes of Ehrlich ascites tumour cells.

Abstract: ATP production of Ehrlich ascites tumour cells was estimated on the basis of their coupled respiration and lactate formation. ATP-consuming processes were assessed from the effects of selective inhibitors of RNA synthesis, protein synthesis and proteolysis, Na+/K+-ATPase on respiration. The extent of protein synthesis and proteolysis were also determined directly. From these values and those of the inhibition of respiration by selective inhibitors, a P/O ratio of 2.2 was calculated. About 75% of the total ATP consumption could be assigned to specific processes. The major ATP-consuming processes of tumour cells in an amino-acid-enriched medium, in which they are in an approximate steady state, are protein synthesis with about 30% of total ATP consumption, and Na+/K+-ATPase with about 20%, while RNA synthesis, ATP-dependent proteolysis and Ca2+-ATPase contribute about 10% each. In an amino-acid-free glucose medium, protein synthesis is reduced to a third, with a corresponding decrease of respiration, whereas the rate of the other ATP-consuming processes is unchanged.

Influence of Noise on Duffing‐Van der Pol Oscillators

Abstract: The stochastic motions of Duffing-Van der Pol oscillators driven by white noise are investigated by using several theoretical methods: analytical and numerical calculations of the stationary probability distribution, analysis of the Hopf bifurcation, computer simulations and study of Lyapunov exponents. One observes a break of the radial symmetry and noise induced oscillations. Die stochastischen Bewegungen von Duffing-Van der Pol-Oszillatoren, die durch weises Rauschen angetrieben werden, werden mit Hilfe verschiedener theoretischer Methoden untersucht: Analytische und numerische Berechnungen der stationaren Wahrscheinlichkeitsverteilung, Untersuchung der Hopf-Bifurkation, Computer-Simulationen sowie das Studium der Lyapunov-Exponenten. Man beobachtet einen Bruch der radialen Symmetrie und rauschinduzierte Oszillationen.

Transluminal closure of patent ductus arteriosus: long-term results of 208 cases treated without thoracotomy.

Abstract: Patent ductus arteriosus was the first inborn cardiac defect ever eliminated by percutaneous transvascular therapy. The method, results, and complications of Ivalon plugging of the ductus in 208 patients between 5 and 62 years old and treated between 1967 and 1985 are described. Permanent closure was accomplished in 197 patients (94.7%). The following particular benefits are obtainable from the method: no need for thoracotomy; local anesthesia applicable to 65% of all cases; 30 mm average time of intevention; only moderate invasiveness to the patients; only 7 days of hospitalization; good cost-benefit ratio.

On stability and stationary points in nonlinear optimization

Abstract: This paper presents three theorems concerning stability and stationary points of the constrained minimization problem:In summary, we prove that, given the Mangasarian-Fromovitz constraint qualification (MFCQ), the feasible set M[H, G] is a topological manifold with boundary, with specified dimension; (ℬ) a compact feasible set M[ H, G] is stable (perturbations of H and G produce homeomorphic feasible sets) if and only if MFCQ holds; under a stability condition, two lower level sets of f with a Kuhn-Tucker point between them are homotopically related by attachment of a k-cell (k being the stationary index in the sense of Kojima).

Plastome mutants

Abstract: Since the first reports seventy-five years ago on the non-Mendelian inheritance of variegation in plants, chloroplast gene mutations have been useful for genetical and physiological investigations. The mutations have been shown to affect the chloroplast translational apparatus, photosystem I, photosystem II, the cytochrome f/b6 complex, carbon fixation, or the ATP synthase. They arose spontaneously or were induced by mutagens or by the action of nuclear mutator genes. Alterations of chloroplast DNA include point mutations, deletions, duplications, and inversions.

The influence of phagocytic stimuli on the expression of HLA-DR antigens; role of reactive oxygen intermediates.

Abstract: Human peripheral blood mononuclear cells show after one day of culture with opsonized zymosan a decreased expression of HLA-DR (but not HLA-A, B, C) antigens, which can be prevented by the scavenger of reactive oxygen intermediates beta-carotene, or superoxide dismutase or indomethacin. Mononuclear cells of a patient with a heterozygous form of chronic granulomatous disease show no alterations in HLA-DR antigen expression after culture with opsonized zymosan. Possible roles of reactive oxygen intermediates or prostaglandins in the modulation of HLA-DR antigens are discussed.

Increasing Absorption Bistability of CdS at Room Temperature

Abstract: Visible-wavelength increasing absorption bistability at room temperature is shown due to lattice heating of CdS in a fully cw-regime. Cross talk of two beams and the switching behaviour of the bistable system are investigated. For the first time critical slowing down is demonstrated for this type of optical bistability. Quantitative theoretical investigations based on the heat flow equations yield an excellent agreement with the experimental data. Optische Bistabilitat infolge wachsender Absorption im sichtbaren Wellenlangenbereich bei Raumtemperatur durch eine Gittererwarmung von CdS in einem vollig stationaren Regime wird gezeigt. Das Ubersprechen zwischen zwei Lichtstrahlen und das Schaltverhalten des bistabilen Systems werden untersucht. Erstmalig wird „critical slowing down” fur diesen Typ optischer Bistabilitat demonstriert. Quantitative theoretische Untersuchungen, die von der Warmeleitungsgleichung ausgehen, ergeben eine ausgezeichnete Ubereinstimmung mit den experimentellen Ergebnissen.

Electrorotation of lymphocytes—The influence of membrane events and nucleus

Abstract: Electrorotation--the spin of cells in rotating high frequency electric fields--has been used to investigate properties of human peripheral blood lymphocytes. The rotation spectra of lymphocytes deviate from those of single shell spheres. The deviations are caused by the electrical properties of the nucleus in the cell interior. Electrorotation allows the distinction between successfully stimulated lymphocytes and unstimulated cells after application of concanavalin A. Notwithstanding the fact that only a proportion of the cells will be mitogenically stimulated we detected an enhanced cell membrane conductivity for the whole cell population immediately after the addition of mitogen.

Nitrogen extractability and buffer capacity of defatted linseed (Linum usitatissimum L.) flour

Abstract: Defatted linseed flour was prepared from cold-pressed seed meal via hexane extraction of the residual oil, followed by removal of the major portion of the hulls through grinding and sieving (sieve size 0.25 mm). The resulting flour had 50% protein on a dry basis compared with 40% contained by the whole seed on an oil-free dry basis. Nitrogen extractability of the defatted flour in water was not influenced by the length of the extraction period but an increased extraction was observed at higher solid:liquid ratios up to the studied limit of 1:40. The smallest amount of nitrogen (20%) was extracted in the pH range 4.0–4.6 and the greatest (80%) at pH 12.0. Addition of NaCl (0.1–1.0 M) broadened the pH range of minimum nitrogen extractability and shifted it towards lower pH region. At higher concentrations (0.6 and 1.0 M) NaCl markedly increased nitrogen extractability in the pH range of 4.0 to 8.0. Precipitation of protein from an extract at pH 10.0 was maximum (77%) at pH 4.1. A higher buffer capacity of the flour was observed in the acidic medium (0.204 mmol HCl g−1 flour) than in the alkaline medium (0.096 mmol NaOH g−1 flour).

Can a solar pulsation event be characterized by a low-dimensional chaotic attractor?

Abstract: Using the theory of nonlinear dynamical systems a time-series analysis of a pulsation event in solar radio emission suggests that there exists a low-dimensional attractor. The power spectrum cannot be interpreted as a superposition of periodic components. Estimates of the maximum Lyapunov exponent and the Kolmogorov entropy give some hints to deterministic chaos. Consequences for the physical modelling of the event are discussed.

A model for the asymmetric lipid distribution in the human erythrocyte membrane

Abstract: The asymmetric transverse distribution of phospholipids in the human erythrocyte membrane can be explained by differences between the rate constants of flip and flop motion of the lipids. A selective interaction between aminophospholipids and spectrin does not need to be assumed for creating and maintaining the asymmetric localization of these lipids. Shape transformation of red cells could be caused by alterations of the flip-flop rate constants leading to a change of the lipid distribution and, consequently, to a differential area expansion of the outer and inner membrane leaflet.

A qualitative analysis of emotional effector patterns and their feedback.

Abstract: This paper is devoted to the study of the relationship between the subjective component (feelings) and the behavioral aspect of emotions. The following emotions were studied: fear-anxiety, anger-aggression, joy-laughter, love-eroticism, love-tenderness, and sadness-tears. The observations were performed with three different groups of people: patients with anxiety neurosis, students under hypnosis, and drama students. Each emotion was characterized by a specific set of reactions in the respiratory pattern, heart activity, muscular activity, and facial expression. The feelings were correlated with the behavioral patterns and each time the behavioral patterns were interfered with a concomitant modification of the subjectivity component was observed. The direct performance of the behavioral emotional patterns in the absence of the emotogenic stimulus produced the feeling corresponding to the mimicked emotion. If the subjects were stimulated with an emotogenic stimulus during the direct performance of the behavioral patterns of another emotion, they confessed to have the feeling corresponding to the mimicked emotion, and not to the emotion belonging to the emotogenic stimulus. The role played by the feedback from the effector organs in the determination of the subjective emotional states is discussed.

Construction of exponential Liouville field operators for closed string models

Abstract: Operators for arbitrary exponentials exp(λφ) of a periodic Liouville field φ(τ,σ) are represented iteratively by an infinite power series in terms of a periodic scalar free field. Necessary quantum corrections of the Liouville operators with respect to their classical expressions are fixed by conformal covariance and locality. Canonical commutation relations for the Liouville field quantities are valid when the canonical quantization of the scalar free field is imposed. A quantum correction of the energy momentum tensor can be avoided thus preserving the conformal invariance of the Liouville theory.

Energy transfer processes between Ten centres in ZnS:Te and CdS:Te

Abstract: ZnS:Te, CdS:Te, and (Zn, Cd)S:Te crystals are studied by photoluminescence emission and excitation spectroscopy and by thermal and optical quenching measurements. In ZnS:Te besides the well-known uv and blue emission bands caused by Te1 and Te2 centres, respectively, a new lower-energy emission band is found at higher Te concentrations which has to be ascribed to the radiative annihilation of excitons bound to Te3 clusters consisting of three Te impurities on nearestneighbour anion sites. The exciton binding energies and Franck-Condon relaxation energies of the various Ten centres are discussed. The energy transfer between the Ten centres in ZnS:Te and CdS:Te is studied and quantitatively analyzed in the framework of a kinetic model. In the lowtemperature region a radiationless resonant energy transfer dominates whereas at higher temperatures a thermal release of the bound excitons followed by an exciton-recapturing by other Ten centres occurs. The observed optically induced energy transfer from Te2 to Te1 centres in ZnS is discussed on the basis of a configuration-coordinate model. ZnS:Te-, CdS:Te- und (Zn, Cd) S:Te-Kristalle werden durch Photolumineszenz-Emissions- und Anregungsspektroskopie und durch thermische und optische Tilgungsmessungen untersucht. In ZnS:Te wird neben der bekannten UV- und der blauen Emissionsbande, die durch Te1 bzw. Te2-Zentren verursacht werden, bei hoheren Te-Konzentrationen eine neue niederenergetische Emissionsbande beobachtet, die der strahlenden Annihilation von Exzitonen zugeschrieben werden mus, die an Te3-Cluster gebunden sind, welche aus drei Te-Storstellen auf nachst-benachbarten Anion-Platzen bestehen. Die Exzitonen-Bindungsenergien und Franck-Condon-Relaxationsenergien der verschiedenen Ten-Zentren werden diskutiert. Der Energietransfer zwischen den Ten-Zentren in ZnS:Te und CdS:Te wird untersucht und quantitativ analysiert im Rahmeneines kinetischen Modells. Im Tieftemperaturbereich dominiert ein strahlungsloser Resonanz-Energietransfer, wahrend bei hoheren Temperaturen eine thermische Befreiung der gebundenen Exzitonen und ein anschliesender Exziton-Wiedereinfang durch andere Ten-Zentren stattfindet. Der beobachtete optisch induzierte Energietransfer von Te2- zu Te1-Zentren in ZnS wird auf der Grundlage eines Konfigurationskoordinaten-Modells diskutiert.

Correlation between the phenotype and the functional capacity of activated T cells in patients with active systemic lupus erythematosus.

Abstract: Activated T cells in the peripheral blood of patients with systemic lupus erythematosus (SLE) were determined using monoclonal antibodies against activation antigens. Elevated percentages of HLA-DR+ T cells were found in association with active disease. In contrast, we observed an increase in IL-2, receptor-bearing T cells in only six out of 16 patients with active disease. In vitro assays, like spontaneous proliferation, response to IL-2, production of IL-2, and immunoglobulin synthesis have shown that the different patterns of activation antigens are related to different functional stages of T-cell activation. The possible therapeutic consequences are discussed.

Histophotometric Evaluation of Glutamate Dehydrogenase Activity of the Rat Hippocampal Formation During Postnatal Development, with Special Reference to the Glutamate Transmitter Metabolism

Abstract: 1. Transmitter glutamate/aspartate synthesis is known to proceed along different metabolic pathways. In this light, the functional relevance of glutamate dehydrogenase in postnatally maturing glutamatergic/aspartatergic structures was studied by means of quantitative enzyme histochemistry. 2. The basic requirements concerning the kinetics and calibration of the histochemical glutamate dehydrogenase reaction used were proved to be met in order to obtain valid quantitative data. 3. The histochemically demonstrable activity of glutamate dehydrogenase (EC 1.4.1.3) in the hippocampal formation of the rat increased markedly during postnatal development. On day 30, the distribution pattern observed was similar to that in adult animals. 4. While the enzyme activity rose within cell body layers from day 0 to day 30 by 240–285%, the increase in neuropil layers was found to be up to 830%. Maximum values were seen in the stratum lacunosum-moleculare of CA1 and CA3 and the stratum moleculare of the dentate fascia on day 30. 5. Since the hippocampal neuropil is supposed to be copiously provided with glutamatergic (and aspartatergic?) structures which become functional in rats during the first weeks of postnatal life, the increase in enzyme activity is discussed to be primarily a consequence of maturing synaptic systems using glutamate and/or aspartate as transmitters.