Showing papers by "University of Copenhagen published in 1968"
TL;DR: In this article, the shell correction method was used to calculate the effect of nucleon shells in deformed and spherical nuclei, and the results were presented in such a way as to illustrate more clearly the effects of shell shells on nucleon nuclei.
802 citations
TL;DR: The microwave spectra of four ring-substituted fluorobenzenes have been measured and the molecular structure of fluorobenzene has been determined by the substitution method as mentioned in this paper.
196 citations
TL;DR: This chapter discusses the electron microscopic morphology of oogenesis, which is concerned with the partial or complete perforation of the envelope, possibly facilitating the passage of nuclear material to the cytoplasm.
Abstract: Publisher Summary This chapter discusses the electron microscopic morphology of oogenesis. The nucleus plays a very important role in regulation of cell life processes. In accordance with the theory that the nucleolus controls the synthesis of cytoplasmic RNA, it is noted in studies of oocyte nuclei that the nucleolus often shows signs of emitting granules into the nucleoplasm. In vitro nucleolar emission is observed in oocytes of the roach and this finding was correlated with a reticulate rim of the nucleolus as seen in the electron microscope. Two processes visibly affect the nuclear envelope during oogenesis. One is concerned with the partial or complete perforation of the envelope, possibly facilitating the passage of nuclear material to the cytoplasm; the other is the enlargement of the nuclear membrane area as well as its area relative to nuclear volume. 2. The literature on oogenesis makes little mention of smooth endoplasmic reticulum. It is generally accepted that this type of cytomembrane plays only a limited role in oocytes. The controversy in interpretation of Golgi structure and function may be equally applied to oogenetical studies. Electron microscopy has so far been the most reliable means for studying Golgi material.
188 citations
TL;DR: The Danish twin register as discussed by the authors is based on the total twin population born in Denmark in the years 1870-1910 with a more recent addition of all same-sexed pairs from the period 1911-1920.
Abstract: A description is given of the Danish Twin Register which is based on the total twin population born in Denmark in the years 1870-1910 with a more recent addition of all same-sexed pairs from the period 1911-1920. Twins belonging to pairs where one or both partners are found to have died before attaining the age of six years are disregarded in the more intensive studies whereas the remaining part of the twin population is being followed by periodical inquiries. The methods used in the collection of the material, in the establishment of the zygosity diagnosis and in specific investigations of selected diseases and abnormalities are described and discussed. A survey is given of the more important results of the research based on the Register. In the group of somatic diseases, greatest attention has so far been paid to malignant growths, diabetes mellitus and peptic ulcer. A number of psychiatric disorders and deviations are at present being studied with schizophrenia and criminality as the first subjects for intensive research. Some of the main results obtained are given as illustrations of the potentialities and scope of this approach to the application of twin studies in a broad variety of research areas.
178 citations
TL;DR: Kety, Wender and Wender as discussed by the authors presented a series of reports on the Adopttees Study, which they called the Extended Family Study and the one that Dr. Wender presented as the Adoptee Study.
157 citations
149 citations
TL;DR: In this article, the authors performed a clinical and EEG study on two hundred consecutive children with their first convulsion with fever of extracerebral origin and were followed at 3 months, 6 months, 1 year and at yearly intervals thereafter.
132 citations
TL;DR: By electron microscopy, the ultrastructure of the M line was investigated in fibers from frog nonglycerinated semitendinosus muscles at body length and at different degrees of shortening and stretch, and a model is suggested for the Mline.
Abstract: By electron microscopy, the ultrastructure of the M line was investigated in fibers from frog nonglycerinated semitendinosus muscles at body length and at different degrees of shortening and stretch. The M line appeared as a line of high electron opacity in the middle of the A band. Its framework consists of: (i) three (four or five) arrays of transverse M bridges, 200 A apart, connecting each A filament with its six neighbors; (ii) M filaments, parallel to the A filaments, passing through the M line and linking each set of M bridges together. In the shortened fiber the M line remained distinct. At high degrees of stretch, the M line became fainter or indiscernible. This appearance reflects a misalignment of the M components caused by a staggering of the A filaments. The M line reappeared after release of fibers stretched 70-80% above equilibrium length. On the basis of the structural analysis, the possible function of the M line is compared with that of the Z line, and a model is suggested for the M line.
126 citations
TL;DR: In this paper, ifJ π = 0 − states of the eight nuclei 16 O, 40 Ca, 48 Ca, 56 Ni, 90 Zr, 114 Sn, 140 Ce and 208 Pb are computed in the framework of the particle-hole model with the Tamm-Dancoff and random phase approximations.
123 citations
TL;DR: A marked, reversible swelling of the outermost layer of the stratum granulosum was observed during short circuiting of the skin compared to the homogeneous appearance of the epithelium under open circuit conditions.
Abstract: A method was experimentally tested which allows simultaneous morphological and bioelectrical studies of a tissue that performs active sodium transport, i.e., the isolated, surviving frog skin. In a four cell lucite chamber with four separate electric potential and current circuits, skin specimens for morphological observation (light and electron microscopy) were fixed in situ in well-defined functional states. The rate of active sodium transport through the epithelium of Rana temporaria skin was modified by changing the strength of the electric current passed through the specimens. A marked, reversible swelling of the outermost layer of the stratum granulosum was observed during short circuiting of the skin compared to the homogeneous appearance of the epithelium under open circuit conditions. Doubling the ingoing current led to an additional small increase of the swelling or the appearance of islets of cell necrosis in the same layer. There were signs of a slight shrinkage of the underlying cell layers. The observations are discussed in the light of previous bioelectrical and morphological observations.
107 citations
TL;DR: It is suggested that the increased arterial accumulation of lipids is caused by an increased endothelial permeability, as the vascular changes and their sequellae were far more pronounced in the hypoxic group.
TL;DR: No HCN could be detected in seeds of one cultivar of Manihot utilissima Pohl whereas seeds of two other cultivars contained 5·2–8·5 μg HCN/g fresh weight, however, 10–14-day-old seedlings of all three cultivars contain 156–260 μg HCNs, indicating a rapid biosynthesis of cyanogenic material occurred during germination.
TL;DR: Genetic and statistical analyses indicate that the HL-A system contains two intimately related chromosome regions containing at least seven and eight alleles, respectively.
Abstract: Genetic and statistical analyses indicate that the HL-A system contains two intimately related chromosome regions containing at least seven and eight alleles, respectively. The complex antibodies which these regions give rise to consist of a mixture of smaller components.
TL;DR: The nucleoside triphosphate pools of two cytidine auxotrophic mutants of Salmonella typhimurium LT-2 were studied under different conditions of pyrimidine starvation, and it was concluded that only cytidine nucleotides participate in the feedback regulation of de novo synthesis of UTP.
Abstract: The nucleoside triphosphate pools of two cytidine auxotrophic mutants of Salmonella typhimurium LT-2 were studied under different conditions of pyrimidine starvation. Both mutants, DP-45 and DP-55, are defective in cytidine deaminase and cytidine triphosphate (CTP) synthase. In addition, DP-55 has a requirement for uracil (uridine). Cytidine starvation of the mutants results in accumulation of high concentrations of uridine triphosphate (UTP) in the cells, while the pools of CTP and deoxy-CTP drop to undetectable levels within a few minutes. Addition of deoxycytidine to such cells does not restore the dCTP pool, indicating that S. typhimurium has no deoxycytidine kinase. From the kinetics of UTP accumulation during cytidine starvation, it is concluded that only cytidine nucleotides participate in the feedback regulation of de novo synthesis of UTP; both uridine and cytidine nucleotides participate in the regulation of UTP synthesis from exogenously supplied uracil or uridine. Uracil starvation of DP-55 in presence of cytidine results in extensive accumulation of CTP, suggesting that CTP does not regulate its own synthesis from exogenous cytidine. Analysis of the thymidine triphosphate (dTTP) pool of DP-55 labeled for several generations with 32P-orthophosphate and 3H-uracil in presence of 12C-cytidine shows that only 20% of the dTTP pool is derived from uracil (via the methylation of deoxyuridine monophosphate); 80% is apparently synthesized from a cytidine nucleotide.
TL;DR: Thymocytes isolated from recently adrenalectomized rats and incubated in a medium with low concentrations of [1,2-3H2]corticosterone were found to accumulate the hormone at 4, 17 and 37°, suggesting that the steroid receptor complex itself is involved in the next step of events, eventually causing the known hormonal effects.
TL;DR: In this article, rain samples from three stations in the Alps (altitude difference 1680 m) show that the evaporation from falling drops causes an isotopic altitude effect of?0.2‰ per 100 m.
Abstract: 1 Simultaneously collected rain samples from 3 stations in the Alps (altitude difference 1680 m) show that the evaporation from falling drops causes an isotopic altitude effect of ?0.2‰ per 100 m. 2 Despite the lack of altitude effect in Alpine snow fall, the summer melting and the wind erosion cause distinct isotopic variations in the net-accumulated material on Kesselwandferner. 3 These variations are reflected in the ice in the ablation zone, and they may be used for studying glacier flow patterns. DOI: 10.1111/j.2153-3490.1968.tb00402.x
TL;DR: The semi-empirical and semi-quantitative methods used in molecular orbital calculations on transition metal complexes have been discussed in this paper, with the conclusion that the only completely consistent method uses the CNDO (complete neglect of differential overlap) approximation.
Abstract: Publisher Summary This chapter discusses the semi-empirical and semi-quantitative methods, which have been used in molecular orbital calculations on transition metal complexes. It is contended that the extended Wolfsberg-Helmholz method forms a rational basis for semi-empirical calculations, but like semi-empirical methods in other fields, it should be used with care, and only the gross features of the results should be considered to be meaningful. An analysis of semi-quantitative methods led to the conclusion that the only completely consistent method uses the CNDO (complete neglect of differential overlap) approximation. The CNDO method is applied to the permanganate ion, through which conclusions are drawn concerning the bonding and the electronic spectrum for the ion, without introducing semi-empirical factors that are abundant in calculations on transition metal complexes.
TL;DR: It is shown that seawater teleosts maintain their water balance by drinking water and eliminating the divalent ions really and the monovalent ions extra-renally, but no quantitative evaluation of the drinking rate was attempted.
Abstract: SMITH1 has shown that seawater teleosts maintain their water balance by drinking water and eliminating the divalent ions really and the monovalent ions extra-renally. Keys2 demonstrated that the extra-renal route of excretion is most probably the gills. On the other hand, Smith3 and Krogh4 say that “the freshwater teleost apparently does not drink water but absorbs it through the oral membranes or perhaps through the gills”. This statement has been challenged by several authors5,6, but no quantitative evaluation of the drinking rate was attempted.
TL;DR: In this paper, a normalization was obtained which allowed the extraction of reduced transition probabilities from the yields of inelastically scattered deuterons, and the cross sections from the 2+ and 3− states were compared to the corresponding reduced transition probability determined by Coulomb excitation with 15 or 16 MeV α-particles.
TL;DR: Labeling of linolenic acid was found to be highest in the monogalactosyl diglyceride fraction at all stages of greening, and differences in the amount of label found in the various phospho- and galacto-lipids were found.
TL;DR: The “face immersion bradycardia” in humans is suggested to be part of a conditioned reflex, developed from an unconditioned apneic inhibitory reflex, built up in people during actual swimming and during exercise on a bicycle-ergometer.
Abstract: The “face immersion reflex” (bradycardia on immersion of the face in water) was studied in normal young subjects, males and females, swimmers and non-swimmers, during actual swimming and during exercise on a bicycle-ergometer. During swimming in a steady state the heart rate was lower when the face was immersed while the subject breathed through a “snorkel” than when the face was out of the water at corresponding oxygen uptakes. During bicycle riding, apnea, with or without face immersion, caused bradycardia. Face immersion alone, without apnea, caused only a short-lasting, slight bradycardia that disappeared on repeated face immersions. Varying the water temperatures between 15° and 35° C had very little effect on the response to face immersion. The “face immersion bradycardia” in humans is suggested to be part of a conditioned reflex, developed from an unconditioned apneic inhibitory reflex.
TL;DR: The ultrastructure of the mast-cell granule was studied in skin specimens of urticaria pigmentosa mast cells and the lamellar structures were found characteristic of human mast- cell granules.
TL;DR: In this paper, the forward particle scatterance was found to be virtually independent of wavelength, whereas the backward scatterance is dependent on the wavelength, and the ratio of scatterance at 45° to total scatterance over all angles was found within narrow limits for different oceanic areas.
TL;DR: The isolated gastrocnemius muscle of the cat was used to study the relation between the desaturation of 133xenon measured by external monitoring, and blood flow measured directly by a dropcounter, and the identity of the results obtained implies that there is, at least initially, diffusion equilibrium between tissue and blood in both.
Abstract: The isolated gastrocnemius muscle of the cat was used to study the relation between the desaturation of 133xenon measured by external monitoring, and blood flow measured directly by a dropcounter.
The metered blood flow agreed with that calculated from the initial slope of the desaturation curve from tissue equilibrated by prolonged intra-arterial infusion and also by atraumatic gas labelling of a local area of the muscle (approximately 0.15% of the muscle weight). In this sense the concept of uniform distribution of blood flow in skeletal muscle has received substantial support. The identity of the results obtained by local gas labelling and by intra-arterial equilibration of the whole muscle with gas implies that there is, at least initially, diffusion equilibrium between tissue and blood in both.
However, the clearance curves could in no instance be fitted by a single exponential function. This indicates that the diffusion equilibrium is not maintained after the initial phase. It is suggested that this is not due to the presence of anatomical arteriovenous shunts or other types of uneven perfusion, but to counter current exchange of inert gas through the walls of vessels, i.e. shunting by diffusion explains the shape of the desaturation curves.
TL;DR: In this article, the cross sections for inelastic scattering of 12 MeV deuterons from all the even Er isotopes have been measured at 90° and 125° by means of a magnetic spectrograph.
TL;DR: In this paper, the elastic and inelastic scattering of deuterons from 1 f 7 2 nuclei (40,42,44Ca, 45Sc, 46,48Ti, 50,51V and 50,52Cr and 54Fe) has been measured at 7.50 MeV bombarding energy.
TL;DR: In this paper, the energy levels of dysprosium nuclei were investigated by inelastic scattering of 12 MeV deutrons, and a magnetic spectrograph was used to record the deutron spectra with an over-all energy resolution of ≈ 8 KeV.
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TL;DR: A new method of quantitative determination of taste is described, in a special experimental situation S compares taste and pure tones, until S finds the pitch which characterizes the sample.
Abstract: This paper describes a new method of quantitative determination of taste. In a special experimental situation S compares taste and pure tones. The latter are varied in pitch until S finds the pitch which characterizes the sample. The method is illustrated by results for two samples, Carlsberg Lager and Carlsberg Elephant Beer. New problems are involved within the psychology of perception.
TL;DR: Using the kidneys from white rats a method for the localization of a prostaglandin-dehydrogenase activity is presented, which demonstrated showed NAD dependence and displayed a high substrate specificity.
Abstract: Using the kidneys from white rats a method for the localization of a prostaglandin-dehydrogenase activity is presented. The activity demonstrated showed NAD dependence and displayed a high substrate specificity. The most pronounced activity was observed in the thick ascending limb of the loop of Henle and in the distale tubule. Lesser activity was found in the collecting tubules of the inner medulla, in the interstitial cells of the medulla, in the epithelial cells of the pelvis, in the tunica media of the cortical arteries and arterioles and in the visceral epithelium of the renal corpuscles. The pitfalls of the cytochemistry of the co-enzyme linked dehydrogenases are discussed and correlated to the present study. Similarly the observations noticed is discussed in relation to the metabolism and biological activity of the prostaglandins.