Showing papers by "University of Antwerp published in 1974"
TL;DR: The effects of substitution of Sr for Ca thus resemble those of caffeine on mammalian heart muscle and a close relationship between the time course of the force-velocity-length relationship and the degree of activation is suggested.
Abstract: The time course of the relationship between force, shortening velocity, and length during shortening was examined in mammalian heart muscle in calcium (Ca)-containing solutions and solutions with strontium (Sr) substituted for Ca by imposing load clamps of various amplitudes at various times during external shortening. The onset of this force-velocity-length relationship was measured by abruptly unloading the muscle at different times to nearly zero external load--by zero load clamping the muscle--under conditions of optimal damping; the subsequent unloaded active muscle shortening velocity was then analyzed with respect to time and length. In Ca- containing solution, the unloaded velocity in the length range around 90% of L max rose within 16% of the time required to reach peak isometric force to a maximum level appropriate to a given contractile state. Subsequently, the force-velocity-length relationship was independent of time at any load over a well-determined portion of external shortening. In Sr-containing solution, unloaded active velocity rose much slower to reach a steady state after 30-35% of the time to peak force, and the time independence of the force-velocity-length relationship was delayed until after this time. In Na-free Sr-containing solution, maximum unloaded shortening velocity and the time-independent portion of the force-velocity-length relationship were achieved again within 20% of the time to peak force. The effects of substitution of Sr for Ca thus resemble those of caffeine on mammalian heart muscle. These findings suggest a close relationship between the time course of the force-velocity-length relationship and the degree of activation.
91 citations
TL;DR: A detailed comparison of the vegetative and reproductive structures in Laurus nobilis and L. azorica is presented, finding that most of the characters used by authors to differentiate the two species show a marked degree of overlap.
39 citations
TL;DR: In this paper, the dispersion of the collective excitations of a polaron-gas is calculated, and it is shown that the interaction between the L.O. phonons and the plasmons induces a relatively strong wave vector dependence in the ω+ ω- modes.
25 citations
TL;DR: The essential differences between normal and hypertrophic bovine thyroid tissue are higher water content and lower triglyceride and sphingomyelin values for hypertrophic tissue.
Abstract: The phospholipid content of bovine thyroid tissue amounts to 70% of total lipid. Triglycerides and cholesterol are the main neutral lipids. Only trace amounts of free fatty acid and esterified cholesterol are found, while two not yet identified components also are present. The distribution of lipid phosphorus in the different phospholipid classes is as follows: phosphatidyl choline, 43.0%; phosphatidyl ethanolamine, 25.2%; phosphatidyl serine, 5.6%; phosphatidyl inositol, 6.5%; sphingomyelin, 14.0%; cardiolipin, 2.8%; lysophosphatidyl choline, <1%; and phosphatidic acid, <1%. The phosphatidyl ethanolamines are rich in plasmalogens. The fatty acid patterns in the different lipid classes are reported. The essential differences between normal and hypertrophic bovine thyroid tissue are higher water content and lower triglyceride and sphingomyelin values for hypertrophic tissue.
18 citations
TL;DR: Caffeine shortens the duration of contraction in this preparation and abolishes the time-independent portion of the FVL relationship, so demonstrating that this is not an invariable feature of heart muscle twitch contractions.
Abstract: It has been demonstrated previously that the force-velocity-length (FVL) relationship in twitch contractions of mammalian heart muscle is independent of time during a major portion of the shortening phase of the contractions. These findings were confirmed under all conditions studied. The reason for the phenomenon is not established. In the present study the time course of the FVL relationship has been examined in twitch contractions of amphibian heart muscle. Caffeine shortens the duration of contraction in this preparation and abolishes the time-independent portion of the FVL relationship, so demonstrating that this is not an invariable feature of heart muscle twitch contractions.
13 citations
TL;DR: A highly purified preparation of bovine hypertrophie thyroid nuclei was isolated by means of an adapted method of Widnell, C. C. and Tata, J. R. (1964), followed by a centrifugation step in a zonal rotor.
8 citations
7 citations
29 Jul 1974
TL;DR: Given a rewriting system G, the most natural set of strings associated with G is the set of all strings one can “derive in G” starting with ω and using productions from P.
Abstract: Given a rewriting system G consisting of an alphabet V, the set of productions P and the axiom ω, the most natural set of strings associated with G is the set of all strings one can “derive in G” starting with ω and using productions from P. Now, one can define “the language of G” in at least two different ways.
5 citations
Journal Article•
3 citations
TL;DR: Bovine thyroids obtained fresh from the slaughterhouse and transported chilled in crushed ice were sliced, washed repeatedly in 0.32 M sucrose solution, homogenized in a Ten Broeck homogenizer and filtered through two layers of cheese cloth.
Abstract: METHODS Isolation of nuclei. - For this purpose an adapted method of WIDNELL & TATA (1964) was used. Bovine thyroids were obtained fresh from the slaughterhouse and transported chilled in crushed ice (DIERICK & HILDERSON, 1967). After removal of adhering adipose and connective tissue the glands were sliced, washed repeatedly in 0.32 M sucrose solution (3 mM with respect to MgCl,, adjusted to pH 7.4 with NaHCO,) and homogenized in a Ten Broeck homogenizer. The homogenate was filtered through two layers of cheese cloth. Per 25 ml filtered homogenate 15 ml of
3 citations
TL;DR: The selectivity for ammonium and some of its alkyl derivatives has been experimentally determined for a liquid-membrane ammonium electrode.
TL;DR: Electrical stimulation by means of an electrode inserted through the infundibulum produces important changes in the plasma levels of adrenaline and noradrenaline, which could be explained by the ganglion blocking effect of high plasma adrenaline levels resulting in an interruption of the central orthosympathic excitation pathway and producing a fall in plasma noradRenaline.
Abstract: Electrical stimulation by means of an electrode inserted through the infundibulum produces important changes in the plasma levels of adrenaline and noradrenaline. Increase of adrenaline in plasma is a constant feature. Noradrenaline is also enhanced at first but can subsequently disappear completely from the plasma especially when the plasma adrenaline levels are rising very high. The differing adrenaline and noradrenaline response could be explained by the ganglion blocking effect of high plasma adrenaline levels resulting in an interruption of the central orthosympathic excitation pathway and producing a fall in plasma noradrenaline.
TL;DR: This case illustrates also how in colder and humid climates, mummification-in its natural aspect—is made possible under certain favourable conditions—ismade possible undercertain favourable conditions.
Abstract: The hanged and completely mummified body of a 31-year-old man was found in one of his house cellars—a fully occupied 3-family house—14 months (433 days) after he had vanished from home. The investigation carried out locally, the questioning of the house tenants and the post-mortem examination itself brought light to this unusual affair. In every case, suicide was then considered. This case illustrates also how in colder and humid climates, mummification-in its natural aspect—is made possible under certain favourable conditions.
TL;DR: In this article, various adducts of the formula (4-substituted pyridine) 2 MgBr 2 have been synthesized by treatment of a 4-substantituted Pyridine with organomagnesium bromides.
TL;DR: In this article, it is shown through an analysis of the electron-paramagnetic-resonance spectra that [001] uniaxial stress changes the geometry of the center at low temperatures.
Abstract: With no applied external uniaxial stress the ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ axis of the ${H}_{A}({\mathrm{Li}}^{+})$ center in KCl:${\mathrm{Li}}^{+}$ makes a 26\ifmmode^\circ\else\textdegree\fi{} angle with [100] in the (110) plane. It is shown through an analysis of the electron-paramagnetic-resonance spectra that [001] uniaxial stress changes the geometry of the ${H}_{A}({\mathrm{Li}}^{+})$ center at low temperatures. The ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ axis moves out of the (110) plane and with increasing stress describes an octant of a cone around [100] having a 2\ifmmode\times\else\texttimes\fi{}26\ifmmode^\circ\else\textdegree\fi{} = 52\ifmmode^\circ\else\textdegree\fi{} apex angle. At high uniaxial stresses (\ensuremath{\sim} 5\ifmmode\times\else\texttimes\fi{}${10}^{8}$ dyn/${\mathrm{cm}}^{2}$) and at 4.2 K the ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ axis is within a few degrees of the (001) plane. Raising the temperature above 4.2 K counteracts the effect of the uniaxial stress while lowering the temperature aids it. Above \ensuremath{\sim}50 K the [100] uniaxial stress is no longer effective in changing the ${H}_{A}({\mathrm{Li}}^{+})$ center geometry. The stressed ${H}_{A}({\mathrm{Li}}^{+})$ center possesses a restricted interstitial motion (RIM) which, similar to the RIM of the unstressed ${H}_{A}({\mathrm{Li}}^{+})$ center, may be tunneling a low temperatures.
TL;DR: In this paper, all researchers on the staff of the State University Centre of Antwerp (RUCA) were asked to indicate from the periodicals collection all journal titles whose contents they or the department wanted to scan In exchange they would be provided by the library with a copy of the table of contents of all incoming issues of these so-called SDI-journals.
Abstract: All researchers on the staff of the State University Centre of Antwerp (RUCA) were asked to indicate from the periodicals collection all journal titles whose contents they or the department wanted to scan In exchange they would be provided by the library with a copy of the table of contents of all incoming issues of these so-called SDI-journals By the time this library service became effective it covered 80% of all departments, each participant making 94 requests on the average The experiment revealed that, in the subject fields studied, 57% of the journals currently taken by the library at RUCA are requested for SDIIf the service is continued over longer periods of time, lists of SDI-periodicals need to be systematically reviewed biannually or individually upon request
TL;DR: In this article, the complexes of γ-picoline with MgBr 2 and MgI 2 have been prepared, the infrared and Raman spectra have been measured in the region 4000 cm − 1 -200 cm −1 and are compared with the spectra of the ligand.
01 Jan 1974
TL;DR: In this paper, a ground state theorem valid for the self-field of a particle is discussed; the theorem relies on the long wave-length behavior of the current-current correlation function.
Abstract: A ground state theorem [1] valid for the self-field of a particle is discussed; the theorem relies on the long wave-length behavior of the current-current correlation function. Using the scale properties of the polaron system, the ground state energy-is related to the kinetic energy by a differential equation with an appropriate initial condition and it was possible to show exact relations between the ground state energy and the number of virtual phonons in the polaron-cloud and the interaction energy [2] which are an extension of the Pekar relations.
01 Jan 1974
TL;DR: In this article, the authors give a survey of thermal hydrodynamic excitations in dielectrics and in magnets, and the advances in experimental methods such as light scattering, neutron scattering and heat pulse techniques have stimulated the interest in this subject.
Abstract: The purpose of this seminar is to give a survey of some thermal hydrodynamic excitations in dielectrics and in magnets. The advances in experimental methods as light scattering, neutron scattering and heat pulse techniques have stimulated the interest in this subject.
TL;DR: The polarisability and the equivalent ionic conductance of the short-chain alkylammonium ions were determined by refractometric and conductometric measurements in aqueous solutions as discussed by the authors.
Abstract: The polarisability and the equivalent ionic conductance of the short-chain alkylammonium ions were determined by refractometric and conductometric measurements in aqueous solutions.
TL;DR: In this paper, a closed expression for the spectral energy transfer function in the inertial range is derived from the original fluid equations, which is closely related to the one postulated by Heisenberg.
TL;DR: In this article, a consistent dynamical equation for the energy spectrum function has been derived which describes a strong turbulent state of a model system, which is similar to the one described in this paper.