Showing papers by "University of Iceland published in 1990"

Economic behavior and institutions: Principles of Neoinstitutional Economics

Abstract: An important research programme has developed in economics that extends neo-classical economic theory in order to examine the effects of institutions on economic behaviour. The body of work emerging from this line of inquiry includes contributions from various branches of economic theory, such as the economics of property rights, the theory of the firm, cliometrics and law and economics. This book is a comprehensive survey of this research programme which the author terms 'neoinstitutional economics'. The author proposes a unified approach to this research, integrating the work of various contributors and emphasising the common principles of inquiry that tie the work together. The theoretical discussion is accompanied by empirical studies dealing with a range of institutions and economic systems. This book will serve as the primary resource for economists and students who want to learn about this important branch of economic theory.

Azithromycin in the treatment of sexually transmitted disease

Abstract: One hundred and eighty-two patients were enrolled in a randomized third-party blinded study to assess the efficacy and safety of azithromycin in the treatment of sexually transmitted diseases. Three regimens of azithromycin, including a single oral dose, were compared with a standard treatment with doxycycline. The patients were followed for four weeks. Efficacy was evaluated in 168 patients (113 azithromycin, 55 doxycycline). Fourteen patients had negative cultures or did not come for all follow-up visits. Of the 168, 138 were infected with Chlamydia trachomatis, 43 with Neisseria gonorrhoeae, and 45 with Ureaplasma urealyticum. Ninety-six per cent of patients with chlamydial infections and 92% of those with gonorrhoea were cured with azithromycin. Two patients infected with N. gonorrhoeae, four with C. trachomatis and six with U. urealyticum had positive cultures on follow-up visits after receiving azithromycin. Of these 11 patients with positive cultures on follow-up visits, seven (five with U. urealyticum and two with C. trachomatis) violated the protocol by having intercourse with infected individuals during the study. Azithromycin was very well tolerated; one patient complained of mild abdominal pain shortly after receiving the drug, seven patients complained of mild nausea and two patients had mild diarrhoea.

fervidobacterium islandicum sp. nov., a new extremely thermophilic eubacterium belonging to the thermotogales

Abstract: An extremely thermophilic anaerobic fermentative eubacterium growing at temperatures between 50 and 80°C (opt.: 65°C) was isolated from an Icelandic hot spring. The cells were Gram-negative motile rods, about 1.8 μm in length, and 0.6 μm in width occurring singly and in pairs. About 50% of the cells formed large spheroids at one end similar to Fervidobacterium nodosum. The new isolate H 21 differed from Fervidobacterium nodosum by a 6 mol % higher GC-content of its DNA (41 mol %), its ability to grow on cellulose, and insignificant DNA homology. The lipids of isolate H 21 were similar to that of members of “Thermotogales”. 16S rRNA sequencing of isolate H 21 and Fervidobacterium nodosum indicated (a) that isolate H 21 represents a new species of the genus Fervidobacterium which we name Fervidobacterium islandicum and (b) that the genus Fervidobacterium belongs to the “Thermotogales” branch.

Catalytic properties and chemical composition of pepsins from Atlantic cod (Gadus morhua).

Abstract: 1. Three pepsins were purified from the gastric mucosa of Atlantic cod (Gadus morhua). 2. The enzymes, called Pepsin I and Pepsin IIa and b, had isoelectric points 6.9, 4.0 and 4.1, respectively, and digested hemoglobin at a maximal rate at a pH of approximately 3. 3. They resembled bovine cathepsin D in being unable to digest the mammalian pepsin substrate N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine. 4. Specificity constants (kcat/Km) for the cod pepsins were lower than for porcine pepsin, and they expressed higher substrate affinity and physiological efficiency at pH 3.5 than at pH 2. 5. The cod pepsins are glycoproteins, and their amino acid composition resembles that of porcine cathepsin D more than that of porcine pepsin. 6. The N-terminal sequence of Atlantic cod pepsins is substantially different from that of porcine pepsin. This indicates a significant evolutionary gap between fish and mammalian pepsins.

Systems of Production and Social Discourse: The Skipper Effect Revisited

Abstract: We have argued that differences in success in Icelandic fishing are statistically explained more by technical and ecological factors than by personal qualities of skippers, the “skipper effect.” Research by other scholars has reopened the discussion of the skipper effect. We assess some of the statistical arguments, pointing out that while there may be a strong skipper effect in some societies, in other societies it is weak or negligible. We suggest that it is important to distinguish between the statistical reality of the skipper effect and its sociology and that the concept of skipper effect is of limited utility in comparative studies, since different researchers using it have not always been talking about the same phenomena and fishing success is conceived differently in different societies. The discussion of the skipper effect echoes debates on resource management and the authenticity of folk models, as well as larger debates in social theory on the relationship between the symbolic and the real and the role of history and agency. Folk theories of production, we argue, are best regarded as cultural accounts constructed in social discourse, in the context of production systems.

Skin deposits in hereditary cystatin C amyloidosis.

Abstract: Clinically normal skin from 47 individuals aged 9–70 years was investigated. Cystatin C amyloid deposits were found in various locations of the skin by light and/or electron microscopy, in all 12 patients with a clinical history of hereditary cystatin C amyloidosis (HCCA). Six asymptomatic individuals, who had the Alu 1 restriction fragment length polymorphism (RFLP) marker reported to cosegregate with the disease, also had cystatin C amyloid deposits in the skin. Three asymptomatic individuals (age 17–46) belonging to the HCCA families were without amyloid in the skin but had Alu 1 RFLP marker. Skin from 12 individuals who served as controls and skin from 14 close relatives of the patients was negative for amyloid. Punch biopsy of the skin is a simple procedure which is of value for the diagnosis of HCCA, even before the appearance of clinical symptoms. This method might also be of use in following progression of the disease.

Electrical stimulation of the gastrocnemius muscle in the spontaneously hypertensive rat increases the pain threshold: role of different serotonergic receptors

Abstract: In a previous study, prolonged low-frequency muscle stimulation in the hind leg of the fully conscious spontaneously hypertensive rat (SHR) was shown to induce a long-lasting reduction of blood pressure. It was also shown that opioid and serotonergic (5-HT) systems were involved. More recently, we have shown that the 5-HT1 receptors are involved in the post-stimulatory decrease in blood pressure. In the present study, the influence of this type of muscle stimulation on the pain threshold was investigated. Pain perception was measured as the squeak threshold to noxious electric pulses. After cessation of the stimulation, an analgesic response was elicited within 60 min and peak analgesia developed after 120 min, being 139 +/- 10% (P less than 0.01) of the prestimulatory control value. The increased pain threshold lasted for another 2 h. One group of SHR was pretreated with PCPA, a serotonin synthesis blocker, which completely abolished the post-stimulatory analgesia. To analyse further the involvement of different serotonin systems, drugs with selective affinity for 5-HT receptors were used. In one group a prestimulatory dose of metitepine maleate (a 5-HT1&2 receptor antagonist) abolished the post-stimulatory elevation of the pain threshold. The prolonged analgesic response was still present after prestimulatory treatment with ritanserin or ICS 205-930 (5-HT2 and 5-HT3 blocking agents respectively). In another group of experiments, the serotonin receptor antagonists were administered post-stimulation to animals with fully elicited analgesia. None of the antagonists used could reverse the elevation of pain threshold towards prestimulatory levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Left and right sided breast cancer.

Abstract: Many studies have shown that unilateral breast cancer is more frequent in the left breast than in the right. This has been investigated in the Icelandic Cancer Registry. Information on all but 18 female breast cancer cases diagnosed in the forty-year-period from 1948 to 1987, a total of 2139 cases, was used. Of these 2011 were unilateral, 1069 were in the left breast, an excess of 13%. Primary breast cancer in both breasts was diagnosed in 81 women, 35 in the left breast first, and 46 in the right breast first. The excess risk of developing cancer remains for the left breast also for women who have already lost one breast because of cancer. Information on whether their relatives had developed breast cancer existed for 1197 of these women. Patients with an affected first degree relative were of 2.54 fold risk of developing contralateral primary breast cancer, but women with no affected relative were at a reduced risk (not significant). Patients with right sided breast cancer are more likely to have a relative with breast cancer. The breast cancer status of the relatives did not influence the risk of death, so a better survival of familial cases could not be shown.

Positivity of Wightman functionals and the existence of local nets

Abstract: The paper is concerned with the existence of a local net of von Neumann algebras associated with a given Wightman field. For fields satisfying a generalizedH-bound the existence of such a net is shown to be equivalent to a certain positivity property of the Wightman distributions.

Weighted Matching in Chess Tournaments

Abstract: In many chess tournaments, e.g. when the Swiss system is used, the number of players is much larger than the number of rounds to be played. In such tournaments the pairing for a round depends on the results in earlier rounds, and the pairing process can be very complicated. In these pairing systems the main goals are to let players with equal scores play together, and that each player should alternately play white and black, with the restriction that no player may face the same opponent more than once. The paper describes how a weighted matching algorithm is used to find ‘the best pairing’ by converting the pairing rules into penalty points.

Neurophysiological evidence for and characterization of the post-ganglionic innervation of the adrenal gland in the rat.

Abstract: The aim of this study was to examine and characterize the post-ganglionic innervation of the adrenal gland, using a neurophysiological nerve recording technique. Adrenal multifibre nerve activity was recorded in chloralose-anaesthetized Wistar rats. To test for post-ganglionic nerve activity, trimethaphan, a ganglionic blocker, was given intravenously. About 60% of the adrenal nerve preparations tested responded with a marked decrease in nerve activity (to 52 +/- 11% of pre-trimethaphan activity, P less than 0.01), while other nerves responded with an increase in activity (to 152 +/- 29% of pre-trimethaphan activity, P less than 0.01). Based on these responses, the nerves were considered to contain predominantly post- or preganglionic fibres respectively, and the difference in response to an intravenous injection of trimethaphan between the two groups was significant (P less than 0.01). It was also demonstrated that the post-ganglionic adrenal nerve activity had a greater variability in firing pattern than preganglionic adrenal nerve activity. We also examined whether there was any cardiac rhythmicity in the investigated nerves. There was a weak cardiac rhythmicity in six out of 12 post-ganglionic adrenal nerves, but there was no cardiac rhythmicity in the remaining six post-ganglionic nerves, and we observed no cardiac rhythmicity in preganglionic nerves. In contrast, renal sympathetic nerves showed a profound cardiac rhythmicity. Our results might explain recent histological findings of a direct post-ganglionic innervation of the adrenal cortex. We speculate that this nerve population is involved in steroid synthesis indirectly via regulation of the cortical blood flow or directly via a direct innervation of parenchymal cells in the adrenal cortex.

Reproductive factors and breast cancer risk in Iceland. A second cohort study

Abstract: In a previous prospective study we showed elevated risks for breast cancer in nulliparous women compared to parous women, in those having their first pregnancy at a higher age, and those with few children. This was based on 216 women diagnosed with breast cancer during 1965 to 1975 among 34,525 women having attended the cervix cancer detection clinic in Iceland by the end of 1974, and born between 1906 and 1945. The present investigation on 848 cases, diagnosed among 6 1,040 women attending the cervix cancer detection clinic during 1964 to 1984 and born between 1901 and 1960, shows the same risk factors to be significant. The relative risks are, however, smaller. The reasons for the difference in relative risks are discussed, We find that the effect of age at first birth is significant for women up to the age of 65 and not for older women. In both cohorts, women older than 55 are underrepresented and more so in the earlier report. In addition, the small number of cases in the reference group with age at first birth below 20 appears to have made the figures of our earlier report unreliable.

Parallel symbolic factorization of sparse linear systems

Abstract: The Cholesky factorization of a sparse matrix A can introduce new nonzeros into the factor matrix. We present an efficient CRCW parallel algorithm to find this fill. Our algorithm takes O(log2n) time using m∗ processors, where m∗ is the number of nonzeros in the Cholesky factor of A. The algorithm has two stages. First it finds A's elimination tree, and then uses it to compute the fill. The part of the algorithm that finds the elimination tree runs in O(log2n) time using m processors, where m is the number of nonzeros in A.

Maedi - Visna. Pathology and Pathogenesis

Abstract: Infection of sheep with maedi-visna virus (MVV) causes a multi-organ disease, i.e. encephalitis, pneumonia, mastitis and arthritis. Both the spectrum of organ changes and the character of pathological lesions are similar to that observed in the related lentiviral infection of goats. The tissue tropism of infection with human immunodeficiency virus (HIV) is partly similar and the pathological lesions, especially of the lungs of pediatric patients with AIDS, resemble maedi in sheep. There is a difference in the susceptibility of different breeds of sheep and a variation in the biology of different strains of MVV, reflected in the incidence of different organ manifestations of the infection in various breeds. Thus arthritis has only been observed in American sheep infected with progressive pneumonia virus (PVV) and Icelandic sheep seem to be exceptionally susceptible to encephalitis. A viremia, which develops shortly after infection, apparently plays a major role in the spread of the infection. In American breeds of sheep the main targets of infection are macrophages and they seem to play a key role in development of lesions, whereas in Icelandic sheep a wide variety of cells are permissive for infection with the MW, among them lymphocytes and glial cells. Early lesions have been shown to be immune-mediated, the damaging immune response being directed against virus-induced antigens. A change in the pathogenetic mechanisms may, however, occur with time, as indicated by the appearance of plaques of primary demyelination many years after infection, resembling lesions characteristic of multiple sclerosis.