Showing papers by "Utrecht University published in 1971"
TL;DR: Renormalizable models are constructed in which local gauge invariance is broken spontaneously and can be found by means of a path integral method, and they can be checked by algebra as discussed by the authors, which can serve as a renormalizable theory for ϱ-mesons and photons.
842 citations
TL;DR: The problem of renormalization of non-gauge invariant regulator fields is studied in this paper, where it is shown that in the limit of high regulator mass gauge invariance can be restored by means of a finite number of counterterms in the Lagrangian.
823 citations
TL;DR: The fact that rats treated with pitressin retain the avoidance response for a considerable time after treatment suggests that this preparation contains peptides which interfere with long term memory storage, but that peptides with a configuration like that of ACTH participate in short term memory processes3.
Abstract: RATS subjected to posterior lobectomy are unable to maintain a shuttle-box avoidance response without reinforcement1, but normal behaviour can be restored to that of sham-operated controls by treatment with pitressin tannate in oil, a relatively crude extract of posterior and intermediate pituitary lobes. Long acting preparations of ACTH and α-MSH can also restore the normal rate of extinction of an avoidance response in posterior lobectomized rats2. Pitressin as well as ACTH analogues, including α-MSH, delay the extinction of an avoidance response also in intact rats3,4. Treatment with pitressin tannate in oil, however, preserves a conditioned avoidance response whether the treatment is given during acquisition or extinction, while ACTH or ACTH analogues inhibit extinction most markedly during the treatment period3. These observations suggest that the mechanisms by which pitressin and analogues of ACTH affect conditioned avoidance behaviour are basically different. The fact that rats treated with pitressin retain the avoidance response for a considerable time after treatment suggests that this preparation contains peptides which interfere with long term memory storage, but that peptides with a configuration like that of ACTH participate in short term (trial to trial) memory processes3.
441 citations
01 May 1971
TL;DR: In this article, the effect of hydrodynamic interaction on the coagulation rate of colloidal particles has been investigated and it has been shown that it can reduce the rate by a factor of about 0.4 to 0.6, depending on the Hamaker constant.
Abstract: The hydrodynamic interaction which occurs when particles are close to each other diminishes the coagulation rate of colloidal particles. We have evaluated this effect, improving a previous treatment by Derjaguin and Muller (7). The absolute rate of rapid coagulation has been computed numerically, with the help of the complete Hamaker equation for the van der Waals force. We have found that hydrodynamic interaction diminishes this rate by a factor of about 0.4 to 0.6, depending on the Hamaker constant. This result agrees completely with that of Spielman (8). The ratio W of the rates of rapid and slow coagulation has been calculated analytically with a simplified Hamaker equation and an approximate expression for the double-layer interaction, following, with modifications, the procedure of Reerink and Overbeek (21). The factor W has also been computed by numerical integration with the complete Hamaker equation. In either calculation the effect of hydrodynamic interaction on d(ln W ) /d (ln c e ) (where c e is the concentration of indifferent electrolyte) is found to be small. We conclude, in agreement with Derjaguin and Muller, that the existing discrepancy between theory and experiment with regard to d(ln W )/d (ln c e ) cannot be explained by this hydrodynamic effect.
382 citations
TL;DR: It is proposed that the 13-peroxyoctadeca-cis-9-trans-11-dienoic acidradical formed through hydrogen radical abstraction by the linoleic acid radical is the key intermediate for these reactions.
Abstract: In an anaerobic system soya-bean lipoxygenase together with linoleic acid induces a structural rearrangement of 13-hydroperoxyoctadeca-cis-9-trans-11-dienoic acid leading to the formation of 13-oxotrideca-cis(trans)-9-trans-11-dienoic acid and n-pentane as well as 13-oxo-octadeca-9,11-dienoic acid. It is proposed that the 13-peroxyoctadeca-cis-9-trans-11-dienoic acid radical formed through hydrogen radical abstraction by the linoleic acid radical is the key intermediate for these reactions.
193 citations
TL;DR: For many years New Mathematics has meant new subject matter, and this is what it still means in many cases as mentioned in this paper. But where people tried to teach it, it became meaning new teaching techniques.
Abstract: For many years New Mathematics has meant new subject matter, and this is what it still means in many cases. Where people tried to teach it, it became meaning new teaching techniques. There are few people to which it means a conscious philosophy.
186 citations
TL;DR: Treatment of human red cell ghosts with pureospholipase C resulted in a nearly complete degradation of the main phospholipid classes (except for sphingomyelin) up to 70% of total phosphorus.
183 citations
TL;DR: A strain of Streptococcus mutans was treated with a mutagenic agent, which resulted in isolation of a mutant which, compared to the original strain, had lost the ability to form sticky deposits on hard surfaces in sucrose medium.
160 citations
TL;DR: A pertinent discrimination in permeability of K+ with respect to Na+ and H+ in the very unsaturated membranes is indicated, indicating a significant increase in K+ permeability with increasing unsaturation.
153 citations
TL;DR: Weinberg's theory of purely leptonic weak interactions can be tested in neutrino-electron scattering experiments as mentioned in this paper, where cross-sections must be measured as a function of the energy of the recoil electron.
143 citations
TL;DR: The composition of lecithins from lung and brain showed many similarities irrespective of animal species, which may indicate a certain degree of tissue specificity.
TL;DR: Results were obtained with liposomes derived from human erythrocytes, indicating that the degree of hydrolysis depends only upon the chemical nature of the phospholipids involved, and changes in membrane architecture occurring during membrane isolation or as induced by nonlytic concentrations of detergents lead to exposure of membrane phosphoglycerides to phospholIPases A and C.
TL;DR: The view that both the lipid bilayers and the biological membranes are penetrated by single fully dehydrated molecules are supported by the finding that a series of different diols did demonstrate practically identical activation energies.
TL;DR: The authors found that participants who anticipated working together showed a more favorable attitude toward their group and its members than subjects who did not, and actual social interaction increased in-group attractiveness, while low influence persons felt comparatively more positive about their group even before they actually had the opportunity to work together.
Abstract: Seventy-two male subjects from lower technical schools were divided into groups of three and assigned to three conditions in which they expected to work together in competition with another group, to work together but independently of the other group, or did not anticipate to work together at all.
Subjects who anticipated working together showed a more favorable attitude toward their group and its members than subjects who did not. Moreover, actual social interaction increased in-group attractiveness.
Intergroup competition led to a more differentiated leadership structure and a greater consensus about the distribution of influence in the group.
Contrary to our predictions, intergroup competition produced no greater in-group solidarity, nor any over-evaluation of the group's product.
Low influence persons felt comparatively more positive about their group even before they actually had the opportunity to work together. An attempt was made to relate this finding to the ordinal position of the low status figure, his affiliative tendencies under stress, and his greater social dependence.
TL;DR: Comparison of the monolayer and bulk methods showed that both techniques are complementary, and the pH dependence and calcium requirements of the enzymatic reaction are similar under monolayers and bulk conditions.
TL;DR: Rat liver plasma membranes were isolated by rate-isopycnic zonal centrifugation and electron micrographs showed a predominantly vesicular appearance with few junctional complexes as mentioned in this paper.
TL;DR: Application of 118 mg of the 3 PCB's (5 times per wk, for 38 days) on the back skin of rabbits also resulted in differences in toxicity, and PCB-induced skin lesions were hyperplasia and hyperkeratosis of the epidermal and follicular epithelium.
TL;DR: HCB residues in birds of prey found in a certain area are higher than residues found in Japanese quail fed 1 ppm HCB, and significantly higher brain residues were found in male compared to female birds.
TL;DR: In this paper, oriented cores from the tholeiitic Rajmahal traps basalts (northeast India), which are of a Late Mesozoic age, were used for a detailed palaeomagnetic investigation.
TL;DR: In this article, the average deviation between theory and experiment with three effective single-particle matrix elements for M1 transitions and effective charges for E2 transitions is about 30 %, only slightly larger than the average experimental error.
TL;DR: Transference number measurements showed that lecithin-cholesterol bilayers, when treated with the polyenes mentioned, become cation-selective, particularly affecting the transference numbers of Ca 2+ .
TL;DR: It was demonstrated that the 3- to 6-fold difference between the specific activities of outer and inner membrane phospholipids was partially eliminated and it was concluded that phospholips exchange between inner and outer membrane inside the mitochondrion was concluded.
TL;DR: A partial characterization of this lysophospholipase indicated that 1-[14 C] palmitoyl- sn -glycero-3-phosphoryl-1′-glycerol is a much better substrate than either 1-[ 14 C].
TL;DR: The doubling of mitochondrial protein, the increase of ALA synthetase activity, the liver enlargement, and the pyroninophilic staining of the hepatic nucleoli suggest an increased protein synthesis, which is considered to be responsible for the increased porphyria.
TL;DR: The mass spectra of 18 trimethylsilyl disaccharides containing only aldohexoses, connected via all possible linkages (1 → 1) to (1→ 6), were compared as mentioned in this paper.
TL;DR: In this article, the high resolving capacity of isoelectric focusing in thin layers of polyacrylamide gel was utilized for the separation of lens crystallins from eye lens tissue.
TL;DR: In this paper, it was proved that the two-dimensional Ising model in the absence of a magnetic field is equivalent to the ground state of the linear XY-model in the presence of magnetic field, under appropriate relations among coupling parameters.
TL;DR: This paper shows that the systems with two-sided and one-sided input are both as strong as Turing machines, and certain systems without cell-death (henceforth called propagating) are asStrong as context-sensitive grammars.
Abstract: Introduction. In his paper A. Lindenmayer [7] put forward a mathematical model for the growth process of linear arrays of cells. To simplify matter we conceive cells as spatial objects together with their states (so change of state of a \"cell\" is actually a change of cell). Lindenmayer considered the cases where each cell may be influenced by: (i) both neighbor cells, (ii) the left neighbor cell only, (iii) no other cell. This means that cells may produce output signals; in case (i) there are two output signals, in case (ii) there is only an output signal to the right, and in case (iii) there is no output signal at all. Now at each tick of the clock each cell transforms into a string of cells under the influence of the incoming signal(s). The set of signals is assumed to be identical with the set of cells and the output of each cell is the cell itself. This does seem to be a rather arbitrary restriction, but, mathematically speaking, the resulting systems are already as strong as anybody could wish. The problem of how to choose the signal set and to define the proper action of signals on cells belongs mainly to the domain of biology and until more experience is acquired the present systems may do very well. In this paper we show that the systems with two-sided and one-sided input are both as strong as Turing machines, t A refinement in measuring the strength of the systems under consideration is obtained by taking into account the possibility of cell-death, i.e., the erasing of a cell or the replacement of a cell by the empty string. It turns out that certain systems without cell-death (henceforth called propagating) are as strong as context-sensitive grammars. To conform to the tradition in automata theory we will use the word \"state\" instead of \"cell\" in the sequel. The author wishes to express his gratitude to Professor Lindenmayer for posing problems and conjectures on L-systems and for many illuminating discussions.
TL;DR: In this paper, the apparent K, for dCTP in dCDP-diglyceride synthesis by intact mitochondria was 4.10-5 M; the vmex was 1.1.10-z nmoles/min per mg protein.