Showing papers by "University of Amsterdam published in 1976"

Design and Implementation of an Efficient Priority Queue

Abstract: We present a data structure, based upon a hierarchically decomposed tree, which enables us to manipulate on-line a priority queue whose priorities are selected from the interval 1,⋯,n with a worst case processing time of $$\mathcal{O}$$ (log logn) per instruction. The structure can be used to obtain a mergeable heap whose time requirements are about as good. Full details are explained based upon an implementation of the structure in a PASCAL program contained in the paper.

Scaling Theory and Finite Systems

Abstract: A renormalization group transformation is introduced with the help of which critical properties of infinite systems can be related to finite systems. As a numerical example the method is applied to the two-dimensional Ising model. The critical point and critical point exponent are computed in addition to the amplitude of the logarithmic singularity in the specific heat.

Value and limitations of thallium-201 scintigraphy in the acute phase of myocardial infarction

Abstract: We examined the diagnostic usefulness of thallium-201 scintigraphy in 200 patients with acute myocardial infarction. The scintiscans showed a defect, suggesting infarction in 165. In all 44 patients studies within six hours after onset of symptoms the scintiscans indicated a defect. Frequency of positive scans was significantly higher (90 of 96) in patients studies within 24 h after onset than in those (75 of 104) studied later (P < 0.01).

Mothers' speech in three social classes

Abstract: Functional and linguistic aspects of the speech of Dutch-speaking mothers from three social classes to their 2-year-old children were studied. Mothers' speech in Dutch showed the same characteristics of simplicity and redundancy found in other languages. In a free play situation, both academic and lower middle class mothers produced more expansions and used fewer imperatives, more substantive deixis, and fewer modal verbs than working-class mothers. These differences were not present while mothers were reading books with their children. In general, the mothers' speech was more complex in the book reading situation than during free play.

Bioenergetic aspects of aerobic growth of Klebsiella aerogenes NCTC 418 in carbon-limited and carbon-sufficient chemostat culture.

Abstract: Carbon-limited chemostat cultures of Klebsiella aerogenes NCTC 418 consumed more oxygen per unit of cell synthesis when growing on mannitol or glycerol than when growing on glucose; and since the "maintenance" requirements were similar, this suggested that the extra reducing equivalents present in these compounds were oxidized wastefully. By comparison with carbon-limited cultures, carbon-sufficient cultures that were ammonia-, sulphate- or phosphate-limited generally consumed considerably more oxygen per unit of cell synthesis, particularly at low growth rates. Thus, according to the theory of Pirt, these carbon-sufficient cultures had a greatly increased "maintenance energy" requirement but nevertheless used the remaining energy with a much increased efficiency compared with carbon-limited cultures. This, we suggest, is a false conclusion which stems from the basic assumption that the maintenance requirement does not change with growth rate.

Benign myopathy, with autosomal dominant inheritance. A report on three pedigrees.

Abstract: Three pedigrees are described in which 28 living siblings suffered from a benign myopathy. The first symptoms were observed around the fifth year of life. The proximal muscles were more involved than the distal muscles, the extensors more than the flexors. Due to a marked paresis of the extensor digitorum communis muscles 22 patients showed a flexion contracture of the interphalangeal joints of the last four fingers. In addition 20 patients showed a flexion contracture of the elbows and 12 patients had a plantar flexion contracture of the ankles. A high incidence of congenital torticollis was found. The histopathological features were non-specific and remarkably uniform and consisted of a marked variation in muslce fibre diameter and a very marked increase of fatty tissue. Light-microscopy and electronmicroscopy did not show any specific structural changes. There was normal distribution of type I and type II fibres, without type-grouping or preferential atrophy of one of the fibre types. Lobulated type I fibres were found in 6 out of 12 biopsies. Post-mortem study of one case did not show any convincing features of a neurogenic disorder. As no relationship could be found between the siblings of the 3 pedigrees as far back as the beginning of the eighteenth century, this myopathy seemed to be a new nosological entity.

On the heat of mixing of liquid alloyS—II

Abstract: In a previous paper, the authors demonstrated that the alloying behaviour of liquid metals can be described, in a qualitative way, by a simple cellular model. In the present paper, a quantitative analysis of heats of mixing and solution is given for liquid alloys; all parameters used in the calculations are tabulated. The values calculated from the model generally agree with available experimental data. Discrepancies between model and experiment mainly occur for systems with large negative heats of mixing and can be attributed to ordering effects in the liquid alloy. A complete list of calculated values of heats of solution of metals in liquid iron, uranium, and tin is presented. A comparison is made between the present model and existing models.

Palynology of the middle part (30–78 metres) of the 120 m deep section in northern greece (macedonia)

Abstract: SUMMARY In this paper the results of a palynological investigation of the 30–78 m interval from a deep bore hole in the Tenagi Philippon are presented. The pollen diagram reflects alternating steppe phases and phases of oak forest, some of them with an evergreen character. Taking the 14C dated last interglacial-glacial cycle (resp. forest and steppe) as a model, the oak phases are interpreted as interglacials or warm interstadials and the steppe phases mostly as glacials. The presence of pollen from evergreen oaks indicates warmer periods that might be called interglacials whereas the presence of only pollen from (semi) deciduous oak species indicates periods that might be called interstadials.

Quinidine-induced ventricular flutter and fibrillation without digitalis therapy

Abstract: Three cases are described with documented ventricular flutter and fibrillation during quinidine medication without concomitant digitalis therapy. In all three patients the arrhythmia developed while they were receiving moderate doses of quinidine. Although no changes in QRS width were observed after administration of quinidine, there was marked prolongation of the Q-T interval. The mechanism of development of ventricular flutter and fibrillation in patients taking quinidine may be similar to that in patients with the Q-T prolongation syndrome.

The role of energy-spilling reactions in the growth of Klebsiella aerogenes NCTC 418 in aerobic chemostat culture.

Abstract: When cell-saturating amounts of glucose and phosphate were added to steady state cultures ofKlebsiella aerogenes that were, respectively, glucose-and phosphate-limited, the organisms responded immediately with an increased oxygen consumption rate. This suggested that in neither case was glucose transport the rate-limiting process, and also that organisms must posses effective mechanisms for spilling the excess energy initially generated when a growth-limitation is temporarily relieved. Steady state cultures of mannitol- or glucose-limited organisms also seemingly generated energy at a greater rate than was required for cell synthesis since gluconate-limited cultures consumed oxygen at a lower rate, at each corresponding growth rate, than did mannitol- or glucose-limited cultures, and there-fore expressed a higherY o value. Thus, mannitol- and glucose-limitations must be essentially carbon (and not energy) limitations. The excess energy generated by glucose metabolism is one component of “maintenance” and could be used at lower growth rates to maintain an increased solute gradient across the cell membrane, imposed by the addition of 2%, w/v, NaCl to the growth environment. The maintenance rates of oxygen consumption ofK. aerogenes also could be caused to increase by adding glucose discontinuously (drop-wise) to a glucose-limited chemostat culture, or by exchanging nitrate for ammonia as the sole utilizable nitrogen source. The significance of these findings to an assessment of the physiological factors circumscribing energy-spilling reactions in aerobic cultures ofK. aerogenes is discussed.

The ostrogorski paradox: a peculiarity of compound majority decision *

Abstract: In the article it is shown that if during an election each voter picks the party with which he agrees on a majority of issues, it is nevertheless possible that a majority of voters disagrees with the winning majority party on every issue. This ‘inverted majority decision’, here called the Ostrogorski-paradox, resembles the structure underlying the Condorcet paradox and Simpson's paradox. Each concerns a relation of pairwise decision or observation functioning in an n-wise world. Our object here is to point out a possible paradox of parliamentary democracy, and to sketch some of its relationships to other paradoxes.

Uptake of Chloro- and Bromobiphenyls, Hexachloro- and Hexabromobenzene by Fish

Abstract: No major differences between the accumulation of di- and tetra-, bromo- and chlorobiphenyls by fish are apparent. In contrast to hexachlorobenzene, hexabromobenzene is not accumulated either from water or from food. The concentration of both chloro- and bromo-substituted compounds in water was of the same order of magnitude, and in both cases fish accumulated higher concentrations from water than from food. In both groups of compounds, the accumulation coefficients generally decreased with increasing degree of substitution during the uptake from water, and increased with increasing degree of substitution when taken up from food. Of the dihalobiphenyls, the 3,4-isomer accumulated from water much less than 2,6- and 2,4-dihalobiphenyl, and did not accumulate from food. Partially debrominated compounds were not detectable in fish exposed either from water or from food, but a dibromobiphenylol was tentatively detected in the former. Mortality after exposure to chlorine occurred among fish fed the mixture of brominated hydrocarbons and their toxicity should be further studied.

Reflection in the systemic arterial system: effects of aortic and carotid occlusion

Abstract: Experiments were performed in seven closed-chest anaesthetized male dogs to determine the role of pulse wave reflection in the pattern of flow and pressure in the ascending aorta. Ten days after implantation of an electromagnetic flow transducer around the ascending aorta a balloon catheter was placed in the descending aorta via the femoral arteries. At the same time a tip manometer was introduced into the ascending aorta. Aortic occlusions at three different sites caused pressure pulses with secondary systolic rises and flow pulses with biphasic deceleration. Secondary rises occurred 45 ± 9.0 ms after the initial pressure rise for high aortic occlusion; this time was 75±8.5ms for occlusion at the level of the diaphragm and 114± 16.5 ms for occlusion near the level of the renal arteries. These times approximate the times in which the pulse travels from the tip manometer to the inflated balloons and back. Forward and reflected pressure and flow waves were calculated from reflection coefficients. Aortic occlusion caused larger reflected waves and the recorded wave forms were caused by the summation of forward and backward waves, the latter contributing the secondary pressure rise and the increased flow deceleration. Occlusion of both carotid arteries showed no specific reflection site but reflected waves were larger. This increased reflection can probably be explained as the result of greater total reflection from distributed sites under increased peripheral resistance.

Pharmacokinetics of trichloroethylene in volunteers, influence of workload and exposure concentration

Abstract: Four male volunteers inhaled for 4 h 70 and 140 ppm trichloroethylene (TRI) at rest and also at rest combined with exercise. To estimate the amount retained in the body (dose), minute volume and concentration in exhaled air were determined. Concentrations of TRI, trichloroethanol (TCE) and trichloroacetic acid (TCA) were determined in blood. Exhaled air was analysed for TRI and TCE; urine for TCE and TCA.