Showing papers by "University of Iceland published in 1976"

Emergence of permanent teeth and onset of dental stages in the population of Iceland.

Abstract: The purpose of this investigation was to determine the mean ages at emergence of the permanent teeth of Icelandic children, as well as the mean ages at onset of the dental stages (DS). The material consisted of 1,941 randomly selected children, corresponding to 9.5% of the total primary and secondary school population of Reykjavik. The mean ages at emergence of the permanent teeth, along with the ages at commencement of DS 2, DS3, DS4 and DS M2, are given. Owing to the age distribution of the material, it was not possible to give mean ages at emergence of the first and third molars, or of the mandibular central incisors. A comparison of the emergence-ages in Icelandic children with those of Danish and Norwegian children showed close agreement.

An epidemiologic study of occlusal anomalies in relation to development of the dentition in Icelandic children

Abstract: — The purpose of the investigation was to determine the prevalence of occlusal anomalies in relation to dental stages (DS) in Icelandic schoolchildren, and to compare it with results from other Scandinavian countries and Ireland found on the basis of the same method. The material consisted of 1,641 randomly selected children, 791 boys and 850 girls, corresponding to 9.5 % of the total primary and secondary school population of Reykjavik. A significant sex difference was only recorded in the frequencies of two of the single morphologic traits of occlusal anomalies, the boys showing higher frequencies in deep bite and in scissors-bite. Significant differences in the occurrence of occlusal anomalies in Iceland and Denmark were only found in two out of 108 pairs of frequencies.

Lithium treatment of a patient with periodic catatonia

Abstract: This case report describes successful lithium treatment in a patient with long-standing periodic catatonia. Various medical treatments had been tried with meager results. Since 1955, a number of phenothiazines had been tried, also with little improvement. The institution of lithium treatment in 1964 caused a dramatic improvement in the patient's condition. For 9 years the patient remained totally asymptomatic. Lithium treatment was terminated in 1975 because of lithium intoxication with a diabetes insipiduslike syndrome. The patient then became psychotic again and has since experienced periodic phases similar to the previous illness. The diagnostic validity of the case is discussed, and some possible explanations of the favourable response to lithium are mentioned briefly.

A marine magnetic survey off southern Iceland

Abstract: Total-intensity magnetic anomalies observed in a 1973 survey reflect contrasts in the structure of the southern Iceland shelf respectively west and east of 20°W. The western part, which is wider and more evenly sloping than the eastern part, has subdued magnetic relief indicating basement (basalt) depth of at least 400 m. On the eastern part of the shelf there occur pronounced edge anomalies, apparently due to a basement step of at least 1 km mean thickness and of mean width 3–4 km. The distance from the upper edge of this basement step to the bathymetric shelf edge increases from 5–8 km at 19°W to 12–14 km at 14°30′W. The basement has alternating magnetic polarities. Linear magnetic anomalies are indistinct or absent in the surveyed region. It is speculated that the sharp basement step represents the trace of the maximum southerly extent of the eastern volcanic zone of Iceland.

Central volcanoes on the Western Icelandic shelf

Abstract: Magnetic surveys of the shelf off Western Iceland have been interpreted to show the presence of a large number of central volcanoes, as known to occur on shore. This is confirmed by gravity evidence. The concentration of these volcanoes is greater off the Snaefellsnes-Breidafjordur area than off the Northwest peninsula; by comparison with previous work in Iceland and to the southeast, these results may define the mantle plume trace west of Iceland.

Mycoplasma ovipneumoniae demonstrated in Icelandic sheep.

Abstract: For at least thirty years chronic pneumonia of suckling lambs has occurred in many sheep flocks in the north-eastern part of Iceland, Thingeyjarsýsla. Owing to the retarded growth rate of affected lambs, the farmers named it “kregda” which means “the poor eater”. A similar syndrome has also been observed in some areas of South Iceland (Gislason 1963).

Deletions of ribosomal protein genes inEscherichia coli merodiploids heterozygous for resistance to streptomycin and spectinomycin

Abstract: In a merodiploid strain ofEscherichia coli heterozygous for the ribosomal protein genesspc andstr, deletions were observed preventing the expression of either gene but permitting the expression of the other. This suggests that thespc andstr genes are in separate transcriptional units.

Notes on the classical and the nonrelativistic limits in quantum mechanics

Abstract: A method is presented which can be used to discuss both the classical and also the nonrelativistic limit of quantum mechanics. A one-to-one correspondence may be established between the asymptotic convergence of the resolvent and that of the timedependent solution. In so far as the question of dynamics is concerned we investigate the relation between families of nonrelativistic Hamiltonians and the corresponding Dirac-Hamiltonians when c→±∞ or when c→±0. The nonrelativistic ‘free’ theory formally shows the same pattern when ħ→±0 (the classical limit) or when ħ→±∞. The investigation finally shows how the asymptotic convergence of the relativistic theory can take place under some fairly general conditions of the radiation field.