Showing papers by "University of Iceland published in 1986"
TL;DR: In a survey within continental solfatara fields in Iceland, three new isolates of the Methanothermaceae could be obtained, all thriving within a temperature range between 55 and 97°C with an optimum around 88 °C.
154 citations
TL;DR: A detailed study of the ground deformation during and following the 1984 eruption of the Krafla volcano, northeast Iceland, revealed the existence of several reservoirs that feed magma towards the volcano.
130 citations
TL;DR: Examination of the trends of meningococcal infection in Norway, Iceland, Faroe Islands, Denmark, England and Wales, and the Netherlands, has shown that Neisseria meningitidis B:2b:P1.2 and/or B: 2a:P 1.2 phenotypes were associated with peaks of infection in the Netherlands in 1966, in Iceland 1976-77, and in England and Welsh in 1973-75 but their prevalence is now practically negligible.
120 citations
TL;DR: The temperature distribution through the Greenland ice sheet at the Dye 3 borehole is a record of the past climatic changes in the Arctic, and the numerical model of the temperature distribution now presented reproduces the observed temperature distribution within 0.03 K, and shows that the basal ice is still cooled 5 K by the cold ice age climate as mentioned in this paper.
Abstract: The temperature distribution through the Greenland ice sheet at the Dye 3 borehole is a record of the past climatic changes in the Arctic. The numerical model of the temperature distribution now presented reproduces the observed temperature distribution within 0.03 K, and shows that the basal ice is still cooled 5 K by the cold ice-age climate. The results suggest a mean ice-age temperature of −32 ± 2°C, which is 12 K colder than the present temperature, and a precipitation rate 50 ± 25% of the present rate. Calculations of a more detailed temperature history through the present inter-glacial period reveal evidence of the AD 1920–50 maximum, the little ice age, and the Atlantic period.
105 citations
96 citations
TL;DR: The proteolytic specificities of two zinc hemorrhagic toxins, isolated from Crotalus atrox venom, were investigated by using the oxidized B chain of bovine insulin and synthetic peptide substrates, suggesting that the toxins may indeed have extended substrate-binding sites, which may accommodate at least six amino acid residues.
Abstract: The proteolytic specificities of two zinc hemorrhagic toxins (Ht-c and Ht-d), isolated from Crotalus atrox venom, were investigated by using the oxidized B chain of bovine insulin and synthetic peptide substrates. The enzymes cleaved the Ala14-Leu15 bond of the insulin B chain most rapidly and the Tyr16-Leu17 slightly more slowly. The His5-Leu6, His10-Leu11, and Gly23-Phe24 bonds were also cleaved but at condiserably slower rates. In order to assess the substrate length preferences of the enzymes, peptide analogs of the B chain about the Ala14-Leu15 bond were synthesized ranging in length from four to seven residues. The heptapeptide NH2-Leu-Val-Glu-Ala-Leu-Tyr-Leu-COOH was the best peptide substrate tested with the other peptides having decreasing kcat/Km values with decreasing length. The tetrapeptide NH2-Ala-Leu-Tyr-Leu-COOH was not cleaved by the enzymes. Furthermore, this peptide was shown to serve as a competitive inhibitor of the toxins. The N-acetylated pentapeptides and hexapeptides, synthesized to probe the active site environment of the enzymes, were significantly better substrates than their unacetylated counterparts. The toxins had the highest kcat/Km values for the acetylated peptide Ac-Val-Ala-Leu-Leu-Ala-COOH. The data suggest that the toxins may indeed have extended substrate-binding sites, which may accomodate at least six amino acid residues. The best substrate examined thus far for the toxins is the fluorogenic peptide analog 2-aminobenzoyl-Ala-Gly-Leu-Ala-4-nitrobenzylamide, suggestive of similarities between the toxins and mammalian collagenases as well as thermolysin. Mechanisms for inhibition of the enzymes were investigated using amino acid hydroxamates, chloromethyl esters, phosphoramidon and the peptide NH2-Ala-Leu-Tyr-Leu-COOH. All of these inhibitors had Ki values in the 10−4 M range.
67 citations
TL;DR: Thermophilic, aerobic bacteria of the genus Thermus were isolated from submarine alkaline hot springs in Iceland and the pattern of growth of these isolates on single carbon sources was similar to that of terrestrial isolates.
Abstract: Thermophilic, aerobic bacteria of the genus Thermus were isolated from submarine alkaline hot springs in Iceland. Five submarine hot springs were sampled, and all had viable counts of Thermus spp. of about 10 CFU/ml. All submarine strains grew in the presence of NaCl at 3% or higher, but no strains from terrestrial hot springs would grow at concentrations higher than 1% NaCl. The growth rate of submarine Thermus strains was not stimulated by NaCl and was reduced at NaCl concentrations higher than 1%. The pattern of growth of these isolates on single carbon sources was similar to that of terrestrial isolates.
62 citations
TL;DR: If secretion plays a similar protective role in the host-parasite interactions that lead to establishment or prevention of these infections, it is predicted an increased incidence of nonsecretors among children with haemophilus infections.
54 citations
46 citations
TL;DR: A window trap is described which has been found useful in the study of the fight periodicity of chironomids and simuliids, and variation in trap catches of .S.
Abstract: SUMMARY. 1. A window trap is described which has been found useful in the study of the fight periodicity of chironomids and simuliids. the trap is simple to construct and can be operated in high winds.
2. Window traps were operated in 1977 and 1478 at Lake Myvatn. Iceland, when thirty-nine chironomid species and two simuliid species were caught. Most of the chironomids had two peaks in flight activity per year. e.g. Eukiefferietla minor, Cricotftpus tibialis. Pogonocladius consohrinus, Tanytaraus gracilentus and Micropsectra airofasciata. Chironomus islandicus and Heterotrissocladius grimshawi had one peak in activity in all traps. The flight activity of Prodadius istandicus, Orthocladius oblidens and Micropsectra Undrothi varied greatly between traps and years. Simulium vittatum had two peaks in flight activity, corresponding to the two generations developing per year. Variation in trap catches of .S. vittatum reflected populalion changes measured independently in a study of larval population dynamic
45 citations
TL;DR: It is concluded, that simply jugular vein blood provides reliable information on the acid/base status of goats, but that the feeding schedule has to be considered in all experiments where small ruminants are used to investigate the integrated control of acid/ base and sodium homeostasis.
Abstract: Effects of 30 min intense hay-feeding on acid/base and sodium homeostasis were studied in semi-starved goats during hyper- and euhydration. Parallel analyses of carotid and jugular blood samples revealed that feeding induced metabolic acidosis, which to some extent was subjected to respiratory compensation. The acidosis was accompanied by renal sodium retention and urinary acidification persisting for 2-3 h. The sodium retention was succeeded by an increase in renal Na excretion above the initial level. This natriuresis was most accentuated during hyperhydration. Blood samples taken for hormone assays during euhydration revealed a 15% increase in haematocrit and a significant rise in plasma aldosterone at termination of feeding. Inhibition of the water diuresis in hyperhydrated animals, and moderate increases in renal arginine vasopressin (AVP) excretion and plasma AVP were inconsistent effects of feeding. It is concluded, that simply jugular vein blood provides reliable information on the acid/base status of goats, but that the feeding schedule has to be considered in all experiments where small ruminants are used to investigate the integrated control of acid/base and sodium homeostasis.
TL;DR: In this article, a detailed map of the glacier surface elevation and sub-ice bedrock has been compiled from ground-based, radio echo-sounding and the maps of HofsjokuIl cover 923 km2, the sounding lines were 1350 km long; 42 000 points were used for determining ice thickness and 30 000 for surface elevation.
Abstract: Since 1977, large areas on western Vatnajokull have been surveyed by ground-based, radio echo-sounding and the whole ice cap, HofsjokuIl, was surveyed in 1983. Detailed maps of the glacier-surface elevation and the sub-ice bedrock have been compiled. The instrumentation includes a 2–5 MHz, mono-pulse echo-sounder, for continuous profiling, a satellite geoceiver and Loran-C equipment, for navigation, and a precision pressure altimeter. The maps of western Vatnajokull cover about 1500 km2 and are compiled from 1500 km-long sounding lines, which yielded about 50 000 data points for ice thickness and 20 000 points for ice-surface elevation. The maps of HofsjokuIl cover 923 km2, the sounding lines were 1350 km long; 42 000 points were used for determining ice thickness and 30 000 for surface elevation. The maps obtained from these data are the first ones of the ice caps with surface elevation of known accuracy. The bedrock map of western Vatnajokull shows details of volcanic ridges and subglacial valleys, running north-east to south-west, as well as the central, volcanic complexes, Hamarinn, Bardarbunga, and Grimsvton and the related fissure swarms. The map of Hofsjokull reveals a large volcanic complex, with a 650 m deep caldera. The landforms in southern Hofsjokull are predominantly aligned from north to south, but those in the northern ice cap run north by 25° east.
TL;DR: A statistical analysis of data on fishing locations is developed in order to be able to describe the behavior, but not the cognition, of Icelandic fishing skippers.
Abstract: We discuss the literature on decision making in fishing and describe several objective factors related to Icelandic fishing skippers' behavior regarding times and destinations of their fishing trips. We argue that the information available to them and the knowledge and theories they have developed often can lead them to several different conclusions. They therefore follow hunches and other processes of decision making. We develop a statistical analysis of data on fishing locations in order to be able to describe the behavior, but not the cognition, of these skippers. [fishing, decision making, Iceland, skipper effect, statistics]
TL;DR: In this article, the authors apply game theory to the determination of government spending and wages within a simple macroeconomic framework where these variables are ordinarily treated as exogenous in the short run.
TL;DR: In this article, simultaneous observations using two-channel meridian scanning photometers were carried out at geomagnetically conjugate-pair stations, Syowa Station in Antarctica and Husafell in Iceland (L=6.1), during August-September 1984.
Abstract: Simultaneous observations using two-channel meridian scanning photometers were carried out at geomagnetically conjugate-pair stations, Syowa Station in Antarctica and Husafell in Iceland (L=6.1), during August-September 1984. The photometers were equipped with interference filters for OI 5577A and Hs 4861A emissions. During the conjugate campaign, the data obtained on September 26, 1984 was of the highest quality with a clear sky and no moon. The initial results on the conjugacy of Hs proton auroras and their relations to 5577A electron auroras are as follows; i) During the pre-breakup phase the Hs auroras observed at Syowa were mostly located at a lower latitude than the simultaneous conjugate auroras observed at Husafell. Such Hs auroras showed high intensities at Syowa relatively to those at Husafell, ii) During the auroral breakup phase, enhancement of Hs emissions occurred almost simultaneously in the both hemispheres. However, the intensities of Hs auroras were higher at Husafell than at Syowa, iii) During the pre-breakup phase, Hs auroras observed continuously in the equator boundary were associated with weak diffuse 5577A auroras in the conjugate regions, (iv) In the regions and time intervals where 5577A auroras showed poor conjugacy, the Hs auroras also showed poor conjugacy.
TL;DR: An eruption started on Jan Mayen on 6 January 1985 and lasted only 35-40 hours and discharged about 7 million m3 of magma, with individual quakes reaching magnitude 5.5 as discussed by the authors.
TL;DR: In this paper, a study of media deprivation was conducted based on data collected during a Swedish television strike in 1980, and the sample consisted of 215 adolescents aged 17 from Vaxjo, a city in southern Sweden.
Abstract: Conducted within the frame of the Media Panel Research Program at the University of Lund, Sweden, this study of media deprivation was based on data collected during a Swedish television strike in 1980. The sample consisted of 215 adolescents aged 17 from Vaxjo, a city in southern Sweden. Key concepts within the uses and gratifications approach are discussed. Of special interest to the study are the notions of dependency/affinity with the medium, functional alternatives to media consumption, and motives for using television.
TL;DR: Three patients with acute Allman type-III acromioclavicular dislocations were treated with open reduction and coracoacromial ligament transfer and two had unsatisfactory results at follow-up.
Abstract: Forty-seven patients with acute Allman type-III acromioclavicular dislocations were treated with open reduction and coracoacromial ligament transfer. At follow-up 1.6–10 years (mean 6) postoperatively 44 patients (94%) had excellent or good functional results. Two of the three patients with unsatisfactory results had degenerative joint changes. No late dislocation was found but there were three subluxations (3–5 mm). Two of the three patients with subluxation in the acromioclavicular joint at follow-up had unsatisfactory results. Complications were infrequent and cosmetic results satisfactory.
TL;DR: In this article, a systematic study of the reactions of Xe(3 P 1, 3 P 2) with HCl, HBr and HI using both spectroscopic and molecular beam techniques is presented.
Abstract: We report a systematic study of the reactions of Xe(3 P 1, 3 P 2) with HCl, HBr and HI using both spectroscopic and molecular beam techniques. No reaction is observed at room temperatures for Xe(3 P 2) with HCl; analysis of the Xe(3 P 1)/HCl data yields an estimate of the endoergicity of the 3 P 2 reaction which agrees within experimental error with the threshold obtained from deconvolution of the excitation function measured in the molecular beam experiments, thus indicating little or no barrier in the entrance channel. Surprisal analysis of the vibrational population distributions obtained by inversion of the rare gas halide spectra yields estimates for the fraction of the available energy disposal into vibration . The results are in broad agreement with earlier estimates and are roughly independent of the spin orbit component for a given reaction. Deviations from the purely kinematic limit in the product rotational alignment ( ) increase across the series HCl, HBr, HI while ...
TL;DR: One animal in this population of fin whales showed alterations in serum chemistry which were consistent with renal failure, and was similar to that of domesticated animals.
Abstract: Serum electrolytes, urea nitrogen, creatinine, albumin and globulin were studied in fin whales (Balaenoptera physalus) caught by commercial whalers in the North Atlantic (Denmark Strait area). Blood samples were obtained by catchment or cardiac puncture within 5-15 min of death and analyzed using automated spectrophotometric methods and flame photometry. Osmolality was determined for two serum samples by a vapor pressure method. Linear regressions determined for each measured serum variable vs. chase time suggested that pursuit of the whales prior to capture had no substantive effect on measured serum chemistry. As in other cetaceans, serum sodium, chloride, urea nitrogen and osmolality were distinctly higher in the fin whale than in terrestrial mammals. The total concentration of serum proteins, however, was 1.4-1.8 g/dl lower, on average, than reported in small toothed whales, and was similar to that of domesticated animals. One animal in this population showed alterations in serum chemistry which were consistent with renal failure.
TL;DR: Thermophilic obligately autotrophic H2‐oxidizing bacteria from Icelandic hot springs were tested for growth on thiosulfate and they would not grow on agar medium under H2 but grew on Agar medium containing thiosolfate.
Abstract: Thermophilic obligately autotrophic H2-oxidizing bacteria from Icelandic hot springs were tested for growth on thiosulfate. Ten strains were tested and all grew on thiosulfate but not on sulfite or sulfur. The product of thiosulfate oxidation was sulfate. The growth rate on thiosulfate was slower (μ=0.12 h-1) than on H2 (μ=0.34 h-1). Washed cells which had been grown on thiosulfate could oxidize thiosulfate rapidly but H2-grown cells oxidized thiosulfate much more slowly and with about a 3 h lag time. The bacteria would not grow on agar medium under H2 but grew on agar medium containing thiosulfate.
TL;DR: In this paper, the authors propose that differences in eruption frequency of volcanoes within the same volcanic region may be due to different aspect ratios of the magma chambers that feed the volcanoes.
Abstract: The eruption frequency of volcanoes, even within the same region, is highly variable. In volcanic regions associated with stress fields that are essentially uniform (but anisotropic), as at plate boundaries, the explanation for the range in eruption frequency must lie within the volcanic systems themselves. I propose that differences in eruption frequency of volcanoes within the same volcanic region may be due to different aspect ratios of the magma chambers that feed the volcanoes. For a magma chamber of elliptical cross section with half-height h and half-width w , the higher the h/w ratio the more frequent will be the eruptions.
TL;DR: Two cases of socket wall addition in patients with a recurrent dislocation of a revised total hip prosthesis with a good result seven and thirteen months after the operation are described.
Abstract: Two cases of socket wall addition in patients with a recurrent dislocation of a revised total hip prosthesis are described. Both patients have a good result seven and thirteen months after the operation.
TL;DR: The paper describes the postpartum reproductive performance of 252 dairy cows in 2 areas in Iceland, in the north (Eyjafjörður) and in the south (Skeið), during a 12 months period, which showed increase in number of conceptions to first pp ai and decrease in numbers of services per conception with increased mean number of days from calving to first ai.
Abstract: The paper describes the postpartum (pp) reproductive performance of 252 dairy cows in 2 areas in Iceland, in the north (Eyjafjorður) and in the south (Skeið), during a 12 months period. First pp ovulation occurred significantly earlier in primiparous cows, in cows in Skeið and in cows that calved in September—November. The average time of first pp artificial insemination (ai) was 72 days in both areas. Conception rate to first ai in these cows was 58 % in Eyjafjorður and 53 % in Skeið and the number of ai per conception was 1.6 and 1.8, respectively. In Eyjafjorður, 23 % of the cows were inseminated at the time of first pp ovulation. Sixtytwo percent of these cows conceived. In Skeið, 20 cows were inseminated at the time of first pp ovulation, and 9 or 45 % of these cows conceived. The interval from calving to conception was, on the average, 92 days in Eyjafjorður and 100 days in Skeið. Comparison of results from individual farms showed increase in number of conceptions to first pp ai (35–72 %) and decrease in number of services per conception (2.0–1.3) with increased mean number of days from calving to first ai (62–82 days).
TL;DR: It is suggested that elevated plasma Ca2+ concentration in vivo may cause increased excitability due to membrane depolarization and resistance increase, thus leading to enhancedCa2+ influx and hormone secretion, and the action potentials of the human MTC cells have both a Na+ and a Ca2+, respectively.
Abstract: Primary cultures of human medullary thyroid carcinoma tissue were prepared from lymph node metastases in two patients. The parenchymal, cultured cells displayed positive immunocytochemical staining for CT, and the cells also released the hormone into the culture medium. The membrane potential and resistance of the CT-producing cells were 50.1 +/- 8.9 mV and 634 +/- 154 M omega (mean +/- SD, n = 46). TTX sensitive action potentials with maximum rate of rise up to 51 V s-1 were evoked by current injection in Na+-containing solution, whereas TTX insensitive action potentials with maximum rate of rise up to 9 V s-1 were generated in Na+-free solution. These action potentials were reversibly blocked by D-600. We conclude that the action potentials of the human MTC cells have both a Na+ and a Ca2+ component. Ejection of CA2+-free solution close to the cells caused membrane hyperpolarization associated with decreased membrane resistance. The reversal potential of this response was -66.2 +/- 10.9 mV (n = 10), indicating that a permeability increase to Cl- and/or K+ may be involved. We suggest that elevated plasma Ca2+ concentration in vivo may cause increased excitability due to membrane depolarization and resistance increase, thus leading to enhanced Ca2+ influx and hormone secretion.
TL;DR: In this article, a model of planar random surfaces in the lattice z d with an action that depends on the angle that neighbouring plaquettes make with each other is considered, and the critical exponents take their mean field value if the susceptibilities of the model and a coarse grained version of it both diverge.
TL;DR: A trend toward more severe inflammatory changes of the tubes was found in women with positive cultures compared with those with negative cultures, and microbiologic investigation of both partners is necessary in order to prevent reinfection of the woman.
TL;DR: In this paper, the scaling limit of the planar random surface (PRS) model has been shown to be a free field with Ornstein-Zernike decay for all noncritical values of the temperature.
Abstract: We prove that the two-loop function in the planar random surface (PRS) model has Ornstein-Zernike decay for all noncritical values of the temperature. A notion of breathing is introduced and it is shown that surfaces do not breathe at noncritical temperatures. With the aid of a simple assumption, supported by mean field theory and numerical calculations, we prove that the scaling limit of the PRS-model exists and equals that of a free field.
TL;DR: In a case of renal adenocarcinoma the presenting features were sudden appearance of an abdominal mass and hypovolemia due to spontaneous retroperitoneal hemorrhage.
Abstract: In a case of renal adenocarcinoma the presenting features were sudden appearance of an abdominal mass and hypovolemia due to spontaneous retroperitoneal hemorrhage. The diagnosis was established following emergency nephrectomy
01 Jan 1986
TL;DR: Estimation of γ-trace in the CSF is presently the only test available for supporting diagnosis of the disorder and differentiating it from other types of cerebral hemorrhage, and will significantly improve genetic counseling and make search for genetic linkage possible.
Abstract: Hereditary central nervous system amyloid angiopathy occurring in Icelanders is the first human disease known to be caused by selective deposition of fragments of the alkaline microprotein γ-trace forming amyloid fibrils in the walls of the brain and spinal cord arteries. This causes single or multiple strokes ending fatally in most cases. A regulation of cysteine proteinase activity has been suggested as the function of γ -trace. Studies of 128 affected members in eight families from the same geographical area, indicate transmission of an autosomal dominant gene over two centuries. About 90% of those who died of this disorder were less than 50 years. The studies indicate, that in few members the carrier state is compatible with reaching old age. This CNS angiopathy is characterized by an abnormally low value of γ-trace in the CSF or one third of the mean value found in comparable normal adults. Estimation of γ-trace in the CSF is presently the only test available for supporting diagnosis of the disorder and differentiating it from other types of cerebral hemorrhage. This test will significantly improve genetic counseling and make search for genetic linkage possible.