Showing papers by "University of Bern published in 1984"
TL;DR: In this article, the low energy representation of several Green's functions and form factors and of the na scattering amplitude are calculated in terms of a few constants, which may be identified with the coupling constants of a unique effective low energy Lagrangian.
3,277 citations
TL;DR: In this paper, a light-induced conversion of the low-spin state (1A1g) to the high-spin (HS) state (5T2g) in the spin-crossover iron (II) complex [Fe(ptz)6] (BF4)2, where ptz = 1-propyltetrazole.
913 citations
TL;DR: In this paper, the authors examined the hypothesis that CO2 variations arose from changes in ocean circulation that affected the distribution of chemical properties and thus of P CO2 in the surface waters of the world ocean.
Abstract: Studies on air trapped in old polar ice1,2 have shown that during the last ice age, the atmospheric carbon dioxide concentration was probably significantly lower than during the Holocene—about 200 p.p.m. rather than 270 p.p.m. Also, Stauffer et al.3 recently showed by detailed analyses of Greenland ice cores, that during the ice age, between about 30,000 and 40,000 yr BP, the atmospheric CO2 level probably varied between 200 and 260 p.p.m. These variations occurred parallel to climatic variations as indicated by δ18O of the ice; astonishingly, the changes took place within rather short times, no more than a few centuries or even less. Here we examine the hypothesis4 that CO2 variations arose from changes in ocean circulation that affected the distribution of chemical properties and thus of P CO2 in the surface waters of the world ocean. Such changes can take place in a rather short time, in contrast to changes of whole ocean properties.
447 citations
TL;DR: The co-inheritance of extensive and poor hydroxylation of mephenytoin and nirvanol, respectively, represents a new drug hydroxymation polymorphism in man.
Abstract: Inherited deficiency in mephenytoin hydroxylation was observed in a family study. It is important that the propositus was of the extensive metabolizer phenotype for the genetically controlled hydroxylation of debrisoquine. Thus, a genetic polymorphism of drug hydroxylation was suspected for mephenytoin. A population study of mephenytoin hydroxylation, combined with identification of extensive and poor debrisoquine hydroxylation phenotypes, was carried out in 221 unrelated normal volunteers. Twelve of them (5%) exhibited defective aromatic hydroxylation of mephenytoin, and 23 (10%) could be identified as poor metabolizers of debrisoquine. Amongst these 35 subjects with a drug hydroxylation deficiency, 3 (or 0.5%; 1 female, 2 males) displayed both defects simultaneously. A panel study of 10 extensive and 10 poor metabolizers of mephenytoin showed that the ability to perform aromatic hydroxylation of the demethylated mephenytoin metabolite nirvanol (5-phenyl-5-ethylhydantoin) was co-inherited with the mephenytoin hydroxylation polymorphism. Family studies suggested that poor metabolizer phenotypes of nirvanol and mephenytoin were most likely to have the homozygous genotype for an autosomal recessive allele of deficient aromatic drug hydroxylation. Intra-subject comparison of the debrisoquine and mephenytoin hydroxylation phenotypes in these subjects indicated that deficiency in the two drug hydroxylations occurred independently. Consequently, the co-inheritance of extensive and poor hydroxylation of mephenytoin and nirvanol, respectively, represents a new drug hydroxylation polymorphism in man.
352 citations
TL;DR: In acute reversible myocardial ischemia extracellular potassium activity rises 4 to 5 fold within 10 to 15 min after interruption of coronary perfusion and a hypothesis is discussed which relates increased K+ efflux to the formation of weak acids in the cells during anaerobic metabolism.
215 citations
TL;DR: In this article, the mean age difference between ice and enclosed air, as well as the age distribution width for a given sample, were deduced from the bubble volume measured as a function of depth.
Abstract: Air entrapped in bubbles formed in cold ice has essentially the same composition as that of the atmosphere at the time of bubble formation. The analysis of dated ice samples therefore enables the history of atmospheric composition to be investigated.1–3 The age of the entrapped air is, however, not the same as that of the surrounding ice because air bubbles only become isolated from the atmosphere during the transition from firn to ice. Typically the age of the ice at this transition is between 100 and 3,000 yr, depending mainly on firn temperature and snow accumulation rate. The mean age difference between ice and enclosed air, as well as the age distribution width for a given sample, are especially important for the investigation of the anthropogenic increase of CO2 and trace gases in the atmosphere over the last centuries, and for the comparison of climatic parameters recorded in the ice with parameters recorded in the bubbles. For Siple Station (Antarctica), this age difference and age distribution width were deduced from the bubble volume measured as a function of depth. The values are 95 yr and 22 yr respectively.
194 citations
TL;DR: The caffeine breath test may be considered as a quantitative measure of hepatic microsomal activity; based on a surprisingly close, hyperbolic relationship between Cl and fasting caffeine plasma concentrations, the latter might serve as a simple guide to severity of liver disease.
179 citations
TL;DR: It is suggested that Col 1–3 serum levels reliably reflect the activity and degree of liver fibrosis and are useful along with liver biopsy in follow‐up of patients with chronic liver disease.
175 citations
TL;DR: The associated production of a heavy Higgs boson (mH > 100 GeV) with top quarks at Juratron energies is studied in this paper, where it is assumed that the mass value of the top-quarks is in the interval mt ≈ 30-80 GeV.
171 citations
TL;DR: In this paper, a computer program was used to identify modes in the zircon fission track age distribution within two Lower Cretaceous sandstone samples from the Weald of southern England.
Abstract: Modes in the frequency of distribution of fission track ages obtained from detrital zircon grains may prove characteristic of individual sandstone bodies, supporting the identification of the sources from which a particular flow of sedimentary detritus was derived and thus allowing new inferences to be made concerning palaeogeography. A computer program has been written and used to identify modes in the zircon fission track age distribution within two Lower Cretaceous sandstone samples from the Weald of southern England. Pronounced modes appear in one rock around 119 Ma, 160 Ma, 243 Ma and 309 Ma and in the other around 141 Ma, 175 Ma, 257 to 277 Ma and 394 to 453 Ma. The geological implications of these quite dissimilar zircon age spectra are discussed. It is concluded that they support the palaeogeographical models of Allen (1981) and indicate that the provenance of the first sample, from the Top Ashdown Sandstone member at Dallington in East Sussex, was almost entirely southerly, while that of the second, from the Netherside Sand member at Northchapel in West Sussex, was more varied, but predominantly westerly and northerly.
154 citations
TL;DR: The pO2 in untreated periodontal pockets was low, however, it does not represent a completely anaerobic environment, and deep pockets contained less oxygen than moderately deep sites.
Abstract: The purpose of this study was to assess the oxygen tension in untreated human periodontal pockets and test the hypothesis that the subgingival environment is anaerobic in nature. Twenty-six patients with advanced chronic inflammatory periodontal disease participated. A total of 111 untreated pockets, 5 to 10 mm in depth, were selected for the pO2 measurements. Pocket depths, Plaque-Index and Gingival-Index were recorded. The pO2 at the base of the 111 pockets ranged from 5 to 27 mm Hg, with an average of 13.3 mm Hg (1.8% 02). Mean pocket depth was 6.9 mm. Moderately deep pockets (5–6 mm) had a mean p02 of 15.0 mm Hg, whereas deep pockets (7–10 mm) showed a significantly lower pO2 of 11.6 mm Hg. No correlation was found between the pO2 and the Plaque-Index. Higher Gingival-Index scores tended to be associated with higher pO2 values. The pO2 in untreated periodontal pockets was low. However, it does not represent a completely anaerobic environment. Deep pockets contained less oxygen than moderately deep sites.
TL;DR: The adjustable, individually shaped, mandibular condylar prosthesis permits precise restoration of articular guidance on the reconstructed side while preventing incorrect loading of the opposite joint.
TL;DR: In this article, a generalization of Friedmann-Robertson-Walker cosmology to 4 + K dimensions is considered, where the space-time manifold R1 × S3 × SK is characterized by two time-dependent scales, R(t) and a(t).
TL;DR: In this paper, a 10Be profile across the manganese crust VA 13-2 from the Central Pacific, using a tandem van de Gr£ a ff accelerator, yields growth rates of 2.7 and 4.8 mm Myr−1 for the layers accumulated between Recent and 6 Myr BP and between 6 and 11 Myr, respectively.
Abstract: One of the most promising applications of the new 10Be detection technique using accelerator mass spectrometry is the determination of growth rates of Mn-nodules and crusts1–5. Because the half life of cosmogenic 10Be (1.5 Myr) is of the same order as the time needed for a few millimetres of nodule material to grow, 10Be is a useful tool for unravelling such evolution during the late Tertiary, when most nodules are assumed to have started their growth6. Mass spectrometric measurement of a 10Be profile across the manganese crust VA 13-2 from the Central Pacific, using a tandem van de Gr£ a ff accelerator, yields growth rates of 2.7 and 4.8 mm Myr−1 for the layers of the crust accumulated between Recent and 6 Myr BP and between 6 and 11 Myr, respectively. Using these measurements as well as 230Th dating, we have been able to distinguish boundaries between zones in the crust with different structures and chemical compositions and to assign ages to them. These ages are 0.12, 2.9–3.4, 5.7–6.7, 7–9, 10–12 and 13–16 Myr BP. All of these boundaries apparently coincide with the times reported for Quaternary and late Tertiary palaeoclimatic events, suggesting that the crust growth has been strongly influenced by palaeoclimate.
TL;DR: It is found that para-substituted phenyl-terpyridine ligands can easily be isolated as hydrobromides from acetic acid and purification turned out to be easy.
Abstract: Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H3C-, H2BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.
01 Jan 1984
TL;DR: During the past ten years parvoviruses have attracted considerable interest due to their unique molecular organization as well as to the fact that they provide an excellent experimental tool to study the replication of a small, single-stranded viral DNA genome and to probe into the synthesis of eucaryotic cell DNA.
Abstract: During the past ten years parvoviruses have attracted considerable interest. This is in part due to their unique molecular organization as well as to the fact that they provide an excellent experimental tool to study the replication of a small, single-stranded viral DNA genome and to probe into the synthesis of eucaryotic cell DNA. On the other hand, parvoviruses were shown to be associated with various economically important diseases of animals. At lease since the very recent world-wide epidemic of canine parvovirus enteritis they are no longer regarded as constituting a mere laboratory problem.
TL;DR: In this article, a distinction is made between local and global scanpaths, reflecting consistent patterns of successive fixations, and the distribution of fixations over a larger time scale irrespective of their immediate succession.
Abstract: The scanpath hypothesis as proposed by Noton and Stark is briefly reviewed and some of the difficulties in its theory and empirical investigation are mentioned. A distinction is proposed between “local scanpaths” in the sense of Stark et al. reflecting consistent patterns of successive fixations, and “global scanpaths” reflecting the distribution of fixations over a larger time scale irrespective of their immediate succession. It is assumed that local scanpaths are regulated by the momentary fixation and its peripheral information in a moment-to-moment control mode, and global scanpathsare regulated by the hypothesis or search plan of the subject and are assumed to operate in a top-down fashion. The data of a facial' inspection and recognition experiment are analysed and empirical evidence for both local and global scanpaths is found. Finally, the type of scanning behavior is set into relation with several performance measures.
TL;DR: In this article, the SU(2) gauge theory was studied in an L × L ×L × L periodic box and the crossover from small-volume to large-volume behavior is likely to take place at z ≅ 2.
TL;DR: In this article, the authors measured the CO2 concentration of ice samples from the deep ice core recently drilled at Dye 3 (south Greenland), which represents ice from about 40 to 30 ka BP.
Abstract: Analyses of atmospheric air extracted from air bubbles in polar glacier ice provide a measure of past CO2 concentrations and their temporal variations. Earlier measurements have shown that the atmospheric CO2 concentration was significantly lower during the late Wisconsin stage and that the change from low to high CO2 concentration occurred in a relatively short time period. We measured the CO2 concentration of ice samples from the deep ice core recently drilled at Dye 3 (south Greenland). The core section investigated represents ice from about 40 to 30 ka BP. The air extracted from the ice samples shows large variations of CO2 concentration which are correlated with δ18O values of the ice samples. A probable explanation of the results is that corresponding changes of the atmospheric CO2 concentration occurred during that glacial period. These changes could have had a significant influence on the climate. Possible reasons for the variations of the atmospheric CO2 concentration are discussed.
TL;DR: In this paper, the backscatter data used in this work are based on four seasons of scatterometer-measurements made on the alpine test site Weissfluhjoch, Davos, and on a comparison with additional scatterometer data from groups in Europe and the U.S.
Abstract: Hydrological interest in mapping snow concentrates on the phase of snow depletion when at least part of the snow cover is wet. In this situation, snow has a very low backscatter coefficient, smaller than almost any land surface at X-band. Together with the independence of cloud cover and time, this unique signature of snow enables frequent and regular mapping of snow even in rugged terrain. First results from a synthetic aperture radar experiment made during the melting season—even under unfavourable conditions—clearly indicate this potential. The backscatter data used in this work are based on four seasons of scatterometer-measurements made on the alpine test site Weissfluhjoch, Davos, and on a comparison with additional backscatter data from groups in Europe and the U.S.A
TL;DR: In this article, the authors show that relatively hot lithospheric slabs are expected to deform in a superplastic flow regime below a depth of ∼300 km if olivine reacts to fine-grained spinel.
Abstract: During subduction, relatively hot lithospheric slabs are expected to deform in a superplastic flow regime below a depth of ∼300 km if olivine reacts to fine-grained spinel. This process reduces the flow strength of such slabs below the phase boundary so that they become aseismic at about this depth. In colder slabs temperatures are too low for superplastic deformation, and a high flow strength and seismic activity are maintained to a depth of 600–700 km.
01 Nov 1984-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the AMS 14C dating of shells handpicked from deep sea sediments is explored, and it is shown that while the age difference between planktonic and benthic shells must carry information regarding paleocirculation rates, this message is likely obscured by effects associated with the coupling between bioturbation and dissolution and between biotic abundance change.
Abstract: In this paper the potential of AMS 14C dating of shells handpicked from deep sea sediments is explored. We show that while the age difference between planktonic (surface dwelling) and benthic (bottom dwelling) shells must carry information regarding paleocirculation rates, this message is likely obscured by effects associated with the coupling between bioturbation and dissolution and between bioturbation and abundance change. It is also possible that the 14C/12C ratio in planktonic shells was initially not identical to that in surface water and that the 14C/12C ratio in benthic shells was initially not identical to that in bottom water. These and other biases will plague all attempts to extract the desired information regarding circulation rate changes over the last 20000 years. However in sorting them out, much will be learned about the origin and history of the calcite particles found in deep sea sediments.
TL;DR: In this paper, the authors report measurements of hydrogen peroxide in polar ice samples and show that H2O2 is a dominant trace compound present in clouds over remote and clean areas.
Abstract: Hydrogen peroxide, a powerful oxidant, is believed to be a key component in the oxidation of SO2 to H2SO4 in clouds1. The first quantitative H2O2 measurements in snow, rain, hoarfrost and fog were reported in 1874 (ref. 2), however, systematic investigations of H2O2 concentrations in precipitation and hydrometeors began only a few years ago3,4. We report here measurements of hydrogen peroxide in polar ice samples. To our knowledge, chemically-reactive species have not been previously analysed in ice core samples. Our measurements show that H2O2 is a dominant trace compound present in clouds over remote and clean areas.
TL;DR: The higher extractable activity of APSSTase with NH(4) (+) may be a regulatory mechanism involved in the formation of sufficient sulfur amino acids during a period of increased protein synthesis.
Abstract: The effect of nitrate and ammonium on the extractable activity of two enzymes of assimilatory sulfate reduction, ATP sulfurylase (EC 2.7.7.4) and adenosine 5′-phosphosulfate sulfotransferase (APSSTase), was examined in Lemna minor L. cultivated under steady state conditions. Nitrate reductase (EC 1.6.6.1) was measured for comparison. Low nitrate concentrations (0.2 and 0.04 millimolar) caused a decrease in the specific activity of all three enzymes measured. Twenty-four hours after transfer to medium without a nitrogen source, the specific activity of APSSTase and nitrate reductase was at less than 30% of the original level, whereas ATP sulfurylase was still at about 80%. NH4+ added to the nutrient solution caused a 50 to 100% increase in the specific activity of APSSTase within 24 hours, followed by a slow decrease. After 72 hours with NH4+, the specific activity was still 25% higher than originally. During the same period, the extractable protein increased by 30% on a fresh weight basis, and total protein by 55 to 60%. Nitrate reductase activity decreased to less than 5%. After omission of NH4+ from the nutrient solution extractable APSSTase activity rapidly decreased to the level of cultures with NO3− as a nitrogen source. Using [35S]SO42− as a sulfur source, an increased incorporation of label into the protein fraction could be detected when NH4+ was added to the nutrient solution. This indicated that more sulfate was assimilated and used for protein synthesis. The higher extractable activity of APSSTase with NH4+ may be a regulatory mechanism involved in the formation of sufficient sulfur amino acids during a period of increased protein synthesis.
TL;DR: In this paper, a study of the production characteristics of W and Z bosons produced at the CERN p p p Collider has been made, where W→ev decays and 39 Z→e + e − decays were identified by the UA2 detector.
TL;DR: It is suggested that microtubule-disrupting drugs induce motility via structural changes in the cytoskeleton which act as signals for the motor apparatus which could be reversed by an extracellular chemotactic gradient.
TL;DR: The neuronal number and nucleolar volume of the magnocellular population of the basal nucleus of Meynert in 6 patients with progressive supranuclear palsy and one associated with Alzheimer's disease were compared with those of 5 controls.