Showing papers by "University of Iceland published in 1981"

The Application of Tephrochronology in Iceland

Abstract: The situation in Iceland for establishing a tephrochronological time scale is very good. This is due to the great number of volcanic eruptions in post glacial time, a great range of variation in chemistry between tephra layers, a rapid thickening of the soil, separating layers with small age difference, and the existence of detailed accounts of many historical eruptions.

Tephrochronology by Microprobe Glass Analysis

Abstract: Basaltic tephra layers form a considerable part of the postglacial tephra deposits in Iceland. They can be related to the volcanic systems that produced them by characteristics based on major and minor element chemistry. Microprobe analysis of volcanic glass shards have made it possible to relate even very thin (1–2 mm) basaltic tephra layers in distal areas outside the volcanic zones to their source.

Tephra Studies and Tephrochronology: A Historical Review with special reference to Iceland

Abstract: In the fourteenth century Icelandic chroniclers already discerned between three types of tephra: pumice, sand and ash. From 1625 onwards, detailed accounts of the tephra fall in all major Icelandic eruptions were written. The earliest description of tephra layers in soil sections is from 1638 and somewhat more comprehensive studies of tephra layers in soil were carried out in the middle eighteenth century.

Radio-Echo Sounding Maps of Storglaciären, Isfallsglaciären and Rabots Glaciär, Northern Sweden

Abstract: Maps are presented for the subglacial topography of Storglaciaren, Isfallsglaciaren and Rabots glaciar in northern Sweden. The maps are results of radio-echo soundings. Isfallsglaciaren consists of...

Torus mandibularis among Icelanders

Abstract: Nine hundred and seventy-six Icelandic schoolchildren (489 male and 487 female) were surveyed for occurrence of torus mandibularis. No sexual dimorphism was observed but there was a statistically significant difference between areas. A highly significant positive association between age and frequency of occurrence and size was also observed. Single tori were more prevalent than multiple ones and also appeared earlier. Symmetrical occurrence predominated, but when unilateral, tori were more often found on the right side. Secular changes in the incidence of torus mandibularis among Icelanders suggest the strong influence of environmental factors.

A Simulation Model of the Capelin Fishing in Iceland

Abstract: In the last decade, or since the herring disappeared from the Icelandic fishing waters in 1967–68, the capelin has been by far the most important industrial fish for the production of meal and oil in Iceland.

Translationally invariant states and the spectrum ideal in the algebra of test functions for quantum fields

Abstract: A class of states on Borchers' tensor algebra is constructed. These states are invariant under the translation group and fulfill the spectrum condition. This leads to a characterization of the linear span of all such states in terms of a simple continuity property.

A new pyroxene fractionation trend from a layered basic intrusion

Abstract: Pyroxene fractionation trends in igneous rocks depend on the magma composition and the conditions of crystallization. Four main types of pyroxene crystallization trend have been recognized in terrestrial igneous rocks (Fig. 1). These are the clinopyroxene trend of mildly alkaline basic magmas1,2; the clinopyroxene trend of strongly alkaline basic magmas3; the two-pyroxene trend typical of tholeiitic magmas4–6; and the two-pyroxene trend typical of calc-alkaline intrusions7–9. The calc-alkaline pyroxene trends show restricted iron-enrichment as high causes the crystallization of calcic amphibole (and biotite) in place of pyroxenes at a fairly early stage of fractionation. Ca-rich and Ca-poor pyroxenes from the Fongen–Hyllingen complex which coexist with hydrous mafic phases and initially have compositions very similar to those from calc-alkaline complexes, show extreme iron-enrichment in the late differentiates. This is the first recorded example of such extreme pyroxene fractionation in elevated conditions and this fractionation trend, accompanied by other distinct mineralogical features, warrants designation as a new type: the Fongen–Hyllingen trend.

A diachronic look at the syllable: the case of Icelandic

Abstract: i. Like so many linguistic terms, the term syllable has been used in many different senses, and theoretical distinctions have been made, aimed at avoiding confusion. There is hardly any need to remind the reader of Pike's distinction between PHONETIC and PHONEMIC syllables: 'the phonetic syllables must be analyzed into the structural phonemic syllables' (Pike, 1947: 90). Although obviously beneficial, this division still leaves considerable room for confusion, both on the phonetic and on the phonological side. On the phonological side the syllable can be thought of as a unit of organization of smaller phonological units (cf. e.g. Bell (I977), Bell & Hooper (1978)) or as a unit defining the scope or environment for phonological processes, or as accounting for regularities of quantity and tonality (cf. e.g. Pike (1947: 90), and Hooper (I972)). On the phonetic side there are at least two approaches to the syllable. It has been looked on as defining units in speech production (cf. Stetson (I951), Catford (1977: 89-90)) or as a means of describing sonority variation in the phonetic signal (cf. e.g. Jespersen (I949/1934: I I8-12I)). This latter aspect relates to the perception of the linguistic signal by speakers and to the acoustic buildup of the phonetic medium. Finally, there are those who deny the usefulness of the concept altogether. I would like to make here a few points related to length and stress in Icelandic that seem to be relevant to the question of the status of the syllable. In particular, I would like to draw attention to the diachronic aspect of these phenonema and its relevance for the syllable as a potential unit in the synchronic analysis of language. 2. Modern Icelandic has been described as having only heavy 'stressed syllables' (cf. Arnason (I977, I980) Swedish and Norwegian have a similar 'structure', cf. Arnason (1977, I980), Eliasson & La Pelle (I973), Eliasson (I979), and Linell (I979)). According to the traditional accounts, vowels are short before two or more consonants, but long otherwise. Thus the types that occur are: COVC2. . ., such as vors [vors] 'spring' (gen.), hestur [hcstYr] 'horse'

Stability of universal unfoldings: a correction

Abstract: The author is grateful to Les Lander for pointing out an error in the stability section of (1). In fact Theorems 5 and 7 are incorrect. Recently Arkeryd proved a stability theorem for the infinite-dimensional case in the context of the imperfect bifurcation theory of Golubitsky and Schaeffer(3). In his result finitely many derivatives are controlled, the number depending on the codimension of the singularity unfolded. In this note we shall present a stability theorem involving the determinacy of the singularity. The context is the parameter-free potential case, that is, catastrophe theory. The proof is without recourse to the finite-dimensional results, and the theorem concludes an account of a part of singularity theory in Banach spaces, in which the author has tried to use as little as possible of the finite-dimensional theory (1, 2).

Merons at finite temperature

Abstract: We prove the existence of solutions to the SU(2) Yang—Mills equations on IR4, periodic in time, with meron singularities along the time-axis.