Showing papers by "University of Fribourg published in 1984"
TL;DR: In this paper, a remarkable exposure of Miocene marine molasse in western Switzerland records the evolution of a tidal sandwave over a period of approximately 2 1/2 months.
Abstract: A remarkable exposure of Miocene marine molasse in western Switzerland records the evolution of a tidal sandwave over a period of approximately 2 1/2 months. The sandwave is composed of tidal ‘bundles’ in which a sandwave reactivation stage and full vortex stage can be recognized for the dominant flow (ebb tide) and a rippled flood apron overlain by high water drape for the reversed flow. Bundle thicknesses vary systematically through neap–spring cycles, with a periodicity of 27 demonstrating the semi-diurnal lunar control of sedimentation. Waves were an additional component, especially when superimposed on flood tides, producing near-symmetrical combined-flow ripple marks in the flood apron.
Tidal current velocities are estimated using critical shear velocities for entrainment, the ripple-dune transition and the dune-plane bed transition. Using appropriate estimates of roughness lengths and a logarithmic velocity law, maximum tidal speeds at 1 m above the bed were approximately 0·6 m sec−1 for ebbs and up to 0·5 m sec−1 for floods. The enhancement by waves of bed shear stress (τwc/τ of approximately 2 for 1 m high waves) under flood currents implies flood tidal velocities closer to 0·2–0·3 m sec−1.
Peak instantaneous bedload sediment transport rates using a modified Bagnold equation are nearly 5 times greater under ebb tides than floods. The average net sediment transport rate at springs (0·04 kg m−1 sec−1) is over 10 times greater than at neaps (0·002 kg m−1 sec−1). Comparison with transport rates in modern tidal environments suggests that the marine molasse of Switzerland was deposited under spatially confined and relatively swift tidal flows not dissimilar to those of the present Dutch tidal estuaries.
180 citations
TL;DR: The local application of cobalt reversibly blocks the calcium channel conductance and therefore synaptic transmission, which is a useful tool to discriminate between the origins of a response recorded with extracellular metal electrodes from central nervous system substructures.
117 citations
TL;DR: The presence in the brain of vasoppressin-containing pathways and of various types of receptors to vasopressin, as well as the existence of cardiovascular effects elicited by central administration of antidiuretic hormone, suggests a role for cerebral vasopressesin in the control of autonomic function.
Abstract: Vasopressin has been shown to elicit vasoconstriction in unanaesthetized animals at plasma concentrations similar to those associated with its renal antidiuretic effect. The vasconstrictor effects of vasopressin do not normally translate into pressor responses until relatively high plasma concentrations are reached. This appears to be related to very effective buffering by the baroreceptor reflex. In the absence of afferent signals from the baroreceptors (surgical denervation, but more importantly, low arterial pressure), the vasoconstriction elicited by vasopressin represents a significant part of the mechanisms that determine blood pressure. Vasopressin is clearly involved in the short-term control of blood pressure in situations such as haemorrhage, other volume-depleted states and dehydration. However, it is only one of several short-acting mechanisms which complement each other in the defence against hypotensive stresses. Under different conditions, the cardiovascular effects of vasopressin seem to have a component related to the central nervous system control of the circulation. Whether or not circulating vasopressin interacts with the newly described network of extrahypothalamic projections from the paraventricular nucleus is yet conjectural. However, the presence in the brain of vasopressin-containing pathways and of various types of receptors to vasopressin, as well as the existence of cardiovascular effects elicited by central administration of antidiuretic hormone, suggests a role for cerebral vasopressin in the control of autonomic function. Slightly elevated levels of vasopressin have been found in various forms of hypertension. Yet, the role of vasopressin, when present, may be more related to its antidiuretic than to its vasoconstrictor properties.(ABSTRACT TRUNCATED AT 250 WORDS)
80 citations
TL;DR: Electrophysiological studies in Parkinsonian patients demonstrate increased reaction times and a reduced build-up of movement-related muscular activity underlying hypokinesia and provide circumstantial evidence for a central origin of tremor and rigidity, corroborate experimentally the concept that Parkinsonian hypokineia is due to a failure of basic behavioral activating mechanisms.
41 citations
TL;DR: In the substantia nigra of anesthetized and awake monkeys, presumptive dopamine cells of the pars compacta were electrophysiologically discriminated against non-dopaminergic cells ofThe pars reticulata by their lower discharge rate, and their exclusive depression following systemic injection of the dopamine agonist apomorphine.
34 citations
34 citations
TL;DR: In this article, the photoelectron spectrum of cyclobutanol was determined and the second π-state of 1+ was estimated at 13.6-14.1 eV above the ground state of 1.52 eV.
Abstract: Vinyl alcohol 1 was prepared by thermolysis of cyclobutanol and its photoelectron spectrum was determined. I = 9.18 eV and I = 9.52 eV were found, the vibrations progression (ṽ = 1400 cm−1) for this lowest energy transition 1(X)1+(X) indicating significant skeletal changes in the ion. The question of the relative stability of the syn (1)- vs. anti-ions (1) is discussed in the light of theoretical calculations. The energy of the second π-state of 1+ is estimated at 13.6–14.1 eV above the ground state of 1.
26 citations
TL;DR: In this article, the wavelength of the 2 p 3 2 - ls 1 2 transition in muonic 12C was measured with a crystal spectrometer as 16.473765 (88) pm.
25 citations
TL;DR: In this paper, the most recent results obtained during the Alfven wave heating experiments being carried out on the TCA Tokamak were presented, along with some of the problems encountered.
Abstract: In this paper, we present the most recent results obtained during the Alfven wave Heating experiments being carried out on the TCA Tokamak. We have obtained both significant electron heating and some ion heating using rf powers up to 230 kW, greater than the value of the ohmic heating power in the target plasma. Firstly, we shall describe the AWH method as applied to TCA and then briefly cover some of the low power experiments carried out during the last year. The higher power experiments will then be discussed, along with some of the problems we have encountered.
22 citations
01 May 1984
21 citations
TL;DR: In this article, the luminescence behavior of Ru(bpy) 2 (pq) 2+, Ru(phen) 2 pq 2, Ruphen 2 (DMCH) 2 +, Rupton 2 (i -biq 2 2 + ) 2, and Rupton 3 (i −biq ) 2 + has been carefully studied.
TL;DR: Vinylamine 1 was prepared by thermolysis of cyclobutylamine and its photoelectron spectrum was measured I = 820 eV and I = 865 eV were found, the dominant vibrational progression (ṽ = 725 cm−1) indicating that in the course of 1(X)1+(X) flattening around the N-atom occurs as mentioned in this paper.
Abstract: Vinylamine 1 was prepared by thermolysis of cyclobutylamine and its photoelectron spectrum was measured I = 820 eV and I = 865 eV were found, the dominant vibrational progression (ṽ = 725 cm−1) indicating that in the course of 1(X)1+(X) flattening around the N-atom occurs The Franck-Condon profile of this band, however, suggests that a skeletal mode of ṽ ≈ 1400 cm−1 (observed also in the iso-π-electronic systems vinyl-alcohol-cation and allyl radical) may also be excited Comparison with the data for the isomer acetaldehyde-imine 2 and its cation s+ shows that the isomer couple 1/2 constitutes a further notable example for a relative thermochemical stability inversion on going from the neutrals to the cations
TL;DR: The results suggest that the decreased sensitivity of the LES strain to fluoride may relate to its relatively greater volume of bone in which most absorbed fluoride is deposited, which is similar to that of the HES strain.
TL;DR: In this article, a method for calculating molecular electrostatic potentials from multiple scattering Xα wavefunctions is presented, and applied to water and formamide molecules leads to iso-energy contour maps in good agreement with ab initio SCF results.
TL;DR: In this paper, the concept of dielectric enrichment was extended from the liquid to the solid state if it is assumed that the solvent shell which stabilizes the ground state is frozen in the polymer and cannot be changed during the lifetime of excited states.
TL;DR: The rate constants of electronic energy transfer from the lowest excited state of Ru(bpy) 2 (L) 2+ or 10 Ru(L) 3 2+ (b).
TL;DR: Because its DLO2/MO2 ratio is lower than that of dog, sheep appears to be more adequate than dog as a model for human alveolar-arterial gas exchange.
Journal Article•
TL;DR: In this paper, the most recent results obtained during the Alfven wave heating experiments being carried out on the TCA Tokamak were presented, along with some of the problems encountered.
Abstract: In this paper, we present the most recent results obtained during the Alfven wave Heating experiments being carried out on the TCA Tokamak. We have obtained both significant electron heating and some ion heating using rf powers up to 230 kW, greater than the value of the ohmic heating power in the target plasma. Firstly, we shall describe the AWH method as applied to TCA and then briefly cover some of the low power experiments carried out during the last year. The higher power experiments will then be discussed, along with some of the problems we have encountered.
TL;DR: It is concluded that the motor cortex is not essential for the execution of this overtrained simple movement.
TL;DR: In this paper, it was shown that the sum of all time orderings (iterative plus noniterative) can be reasonably well approximated by twice the isoscalar piece of the iterative ones.
Abstract: The fourth-order noniterative diagrams of $\ensuremath{\pi}\ensuremath{\rho}$ exchange involving nucleon-isobar intermediate states are evaluated in momentum space in the framework of noncovariant perturbation theory. It is shown that the sum of all time orderings (iterative plus noniterative) can be reasonably well approximated by twice the isoscalar piece of the iterative ones (which are much simpler to evaluate). The same approximation is used in order to describe the sum of all time orderings for the corresponding diagrams involving double-isobar intermediate states. The role of these contributions is studied in NN scattering. Especially, it is investigated whether such contributions can quantitatively replace part of the $\ensuremath{\omega}$-exchange contribution used in one-boson-exchange models.
TL;DR: Human subjects performed plantar flexions of the foot in visual reaction time (RT) situations and the intersensory facilitation in the choice RT task provided support for the preparation enhancement model since the subjects could not react to the electrical stimulus alone.
TL;DR: In this paper, auteurs ont etudie la distribution and the structure of la chromatine dans les differents types cellulaires se trouvant dans un epanchement pleural humain d'origine tumorale (adenocarcinome mammaire).
01 Jan 1984
Journal Article•
TL;DR: Das Photoelektronenspektrum (Abbildung) von Vinylalkohol (II), zuganglich durch Pyrolyse von Cyclobutanol (I), wird untersucht as mentioned in this paper.
Abstract: Das Photoelektronenspektrum (Abbildung) von Vinylalkohol (II), zuganglich durch Pyrolyse von Cyclobutanol (I), wird untersucht.