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Showing papers by "University of Antwerp published in 1972"


Journal ArticleDOI
TL;DR: The experiments on dogs show that an increased cellular metabolism due to noradrenaline and to adrenaline, is an essential factor in the haemodynamic reactions in subarachnoid haemorrhage.

72 citations


Journal ArticleDOI
TL;DR: Fine structural details are described in developing coronary collateral vessels after occlusion of the circumflex branch of the left coronary artery, which had developed into a small artery by increasing diameter and wall thickness.
Abstract: Fine structural details are described in developing coronary collateral vessels after occlusion of the circumflex branch of the left coronary artery Vessels examined 3 weeks after the onset of constriction showed thinning of the endothelial lining, fragmentation or absence of the internal elastic membrane, necrosis of medial smooth muscle cells and infiltration of blood-borne cells into the vessel wall These findings have been interpreted as acute vascular damage After 8 weeks the prominent feature was a subintimal thickening which contained smooth muscle cells, modified smooth muscle cells and fibroblast-like cells combined with an accumulation of collagen, elastic material and ground substance After 1 year the subendothelial thickening had regressed, and only a small rim of subintimal smooth muscle cells and extracellular material was observed In the course of 1 year an arteriolar vessel had developed into a small artery by increasing diameter and wall thickness

63 citations


Journal ArticleDOI
TL;DR: In this paper, it was suggested that transitions to these states might lead to prominent resonances in the optical absorption at energies approximately twice the bandgap energy. And the predicted shift towards higher energies of the corresponding resonances was calculated in the energy loss function.

47 citations


Journal ArticleDOI
TL;DR: In this paper, a new technique, velocity clamping, was used to study the effects of a constant total velocity of shortening on the interrelation between force, velocity, length, and time in cat papillary muscle.
Abstract: A new technique-velocity clamping-was used to study the effects of a constant total velocity of shortening on the interrelation between force, velocity, length, and time in cat papillary muscle. With decreasing values of clamped total velocity, the duration of the contraction increased but never exceeded the duration of an isometric contraction. Hence these findings confirm that the mode of contraction-isometric or isotonic-has a marked effect on the duration of the contraction. The active state can be prolonged when less shortening occurs and more tension is developed. This phenomenon seems mainly due to the amount of shortening rather than to the velocity of shortening of the muscle. The data were also plotted on a threedimensional graph and compared with velocity-length tracings of afterloaded contractions. The force-length trajectories of the muscle during velocity clamping did not fall on the surface described by the force-velocity-length relations as derived from afterloaded isotonic contractions. This finding could be ascribed to the masking effect of the series elastic component due to the continuous adjusting of the load.

24 citations


Journal ArticleDOI
L Wuytack1
TL;DR: A new algorithm is derived for computing continued fractions whose convergents form the elements of the table of interpolating rational functions with theqd-algorithm as a special case.
Abstract: The problem of the construction of a table of interpolating rational functions is considered. A description of the methods of Larkin and Stoer for solving this problem is given. A new algorithm is derived for computing continued fractions whose convergents form the elements of the table. This algorithm has theqd-algorithm as a special case.

18 citations


Journal ArticleDOI
TL;DR: In this paper, perturbation theory is directly applied to the system of Howie and Whelan, and general recurrence relations are presented for the calculation of the corrections on eigenvalues and eigenvectors.
Abstract: Instead of using the usual Schrodinger equation, perturbation theory is directly applied to the system of Howie and Whelan. According to the nature of the perturbing dynamical matrix generally three different types of perturbation are distinguished. The perturbing matrix may be a) constant and Hermitian b) constant but not Hermitian c) not constant but depth dependent. The first case has been discussed previously, now case b) is considered. In full matrix notation both generate and degenerate perturbation theory is presented. Special attention is given to the usual treatment of absorption effects. General recurrence relations are presented for the calculation of the corrections on eigenvalues and eigenvectors. The influence of these corrections on the amplitudes and the intensities of the constituent beams is discussed. Anstatt der normalen Schrodingergleichung wird die Storungstheorie direkt auf das System von Howie und Whelan angewendet. In Ubereinstimmung mit der Natur der dynamischen Stormatrix werden im allgemeinen drei verschiedene Arten der Storung unterschieden. Die Stormatrix kann a) konstant und hermitesch, b) konstant, jedoch nicht-hermitesch und c) nicht konstant, sondern tiefenabhangig sein. Nach der fruheren Diskussion des ersten Falles wird nun der Fall b) betrachtet. In vollstandiger Matrixschreibweise werden sowohl entartete als auch nichtentartete Storungstheorie angegeben. Spezielle Beachtung findet die normale Behandlung der Absorptionseffekte. Allgemeine Rekursionsbeziehungen werden fur die Berechnung der Korrekturen zu den Eigenwerten und Eigenvektoren angegeben. Der Einflus dieser Korrekturen auf die Amplituden nnd Intensitaten der Teilstrahlen wird diskutiert.

11 citations



Journal ArticleDOI
M. Czank1, J. Van Landuyt2, H. Schulz1, F. Laves1, S. Amelinckx2 
TL;DR: In this article, the authors describe a mode that leads to a cons i s t en t exp l ana t i on for all t h e p rev ious and more recen t obse rva t ions in t r an s miss ion electron microscopy.
Abstract: I n p rev ious pape r s [1, 2] two a p p a r e n t l y d i f fe rent models were p roposed in order to i n t e rp r e t t he obse rva t ions on t he t e m p e r a t u r e dependence of t he c type ref lect ions (h + k + l = odd) on t he one h a n d [1] and t he e lect ron microscopic obs e rva t i on of d o m a i n s t r uc t u r e s on t he o the r h a n d [2]. Here we shal l describe a mode l t h a t leads to a cons i s t en t exp l ana t i on for all t h e p rev ious and more recen t obse rva t ions in t r an s miss ion electron microscopy. Fig. I a shows a d a r k field e lec t ron microscope i mage of t h e coarse d o m a i n s t r u c t u r e observed a t low t e m p e r a t u r e us ing a c type ref lect ion for imag ing . T he d o m a i n walls are revealed as s f r inges [3]: we therefore conclude t h a t t hese in ter faces are an t i phase boundar ies . On h e a t i n g above a cri t ical t e m p e r a t u r e (230 ~ t he fr inge p a t t e r n g r adua l l y becomes f iner and d isappears , whereas s i m u l t a n e o u s l y t he c-reflect ions become more diffuse and ve ry weak. At th i s s t age t h e da rk field image in c-reflect ions revea ls Mack a n d whi%e pa tches , in ter faces are no longer resolved. A h e a t i n g sequence shows t h e t r an s i t i on f rom t he low t e m p e r a t u r e d o m a i n s t r uc tu r e

9 citations


Journal ArticleDOI
TL;DR: In this article, the crystallography and geometry of domains in V2−xCrxO3 have been studied by transmission electron microscopy and the interface between these two phases is visible as a wavy fringe pattern imaging directly the progression of the Mott-transition.

8 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the lifetime of one of the first internal relaxed excited states of polarons is increased by the application of a magnetic field, which is known as magnetic magnetic resonance.

2 citations