Showing papers by "Aarhus University published in 1976"
TL;DR: The spin-density-functional (SDF) formalism has been used for the interpretation of approximate versions of the theory, in particular the local-spin-density (LSD) approximation, which is formally valid only in the limit of slow and weak spatial variation in the density as discussed by the authors.
Abstract: The aim of this paper is to advocate the usefulness of the spin-density-functional (SDF) formalism. The generalization of the Hohenberg-Kohn-Sham scheme to and SDF formalism is presented in its thermodynamic version. The ground-state formalism is extended to more general Hamiltonians and to the lowest excited state of each symmetry. A relation between the exchange-correlation functional and the pair correlation function is derived. It is used for the interpretation of approximate versions of the theory, in particular the local-spin-density (LSD) approximation, which is formally valid only in the limit of slow and weak spatial variation in the density. It is shown, however, to give good account for the exchange-correlation energy also in rather inhomogeneous situations, because only the spherical average of the exchange-correlation hole influences this energy, and because it fulfills the sum rule stating that this hole should contain only one charge unit. A further advantage of the LSD approximation is that it can be systematically improved. Calculations on the homogeneous spin-polarized electron liquid are reported on. These calculations provide data in the form of interpolation formulas for the exchange-correlation energy and potentials, to be used in the LSD approximation. The ground-state properties are obtained from the Galitskii-Migdal formula, which relates the total energy to the one-electron spectrum, obtained with a dynamical self-energy. The self-energy is calculated in an electron-plasmon model where the electron is assumed to couple to one single mode. The potential for excited states is obtained by identifying the quasiparticle peak in the spectrum. Correlation is found to significantly weaken the spin dependence of the potentials, compared with the result in the Hartree-Fock approximation. Charge and spin response functions are calculated in the long-wavelength limit. Correlation is found to be very important for properties which involve a change in the spinpolarization. For atoms, molecules, and solids the usefulness of the SDF formalism is discussed. In order to explore the range of applicability, a few applications of the LSD approximation are made on systems for which accurate solutions exist. The calculated ionization potentials, affinities, and excitation energies for atoms propose that the valence electrons are fairly well described, a typical error in the ionization energy being 1/2 eV. The exchange-correlation holes of two-electron ions are discussed. An application to the hydrogen molecule, using a minimum basis set, shows that the LSD approximation gives good results for the energy curve for all separations studied, in contrast to the spin-independent local approximation. In particular, the error in the binding energy is only 0.1 eV, and bond breaking is properly described. For solids, the SDF formalism provides a framework for band models of magnetism. An estimate of the splitting between spin-up and spin-down energy bands of a ferromagnetic transition metal shows that the LSD approximation gives a correction of the correct sign and order of magnitude to published $X\ensuremath{\alpha}$ results. To stimulate further use of the SDF formalism in the LSD approximation, the paper is self-contained and describes the necessary formulas and input data for the potentials.
2,763 citations
TL;DR: A recent study was able to demonstrate the occurrence of VIP, not only in endocrine-like cells, but also in a rich system of gastrointestinal nerves, some of which had a perivascular localization 12.
352 citations
TL;DR: Support is provided for the view that PP is a true pancreatic hormone by the use of specific antisera demonstrated PP immunoreactivity in the pancreas of a number of mammals.
Abstract: A peptide, referred to as pancreatic polypeptide (PP), has recently been isolated from the pancreas of chicken and of several mammals. PP is thought to be a pancreatic hormone. By the use of specific antisera we have demonstrated PP immunoreactivity in the pancreas of a number of mammals. The immunoreactivity was localized to a population of endocrine cells, distinct from the A, B and D cells. In most species the PP cells occurred in islets as well as in exocrine parenchyma; they often predominated in the pancreatic portion adjacent to the duodenum. In opossum and dog, PP cells were found also in the gastric mucosa. In opossum, the PP cells displayed formaldehyde-induced fluorescence typical of dopamine, whereas no formaldehyde-induced fluorescence was detected in the PP cells of mouse, rat and guinea-pig. Also in these latter species, however, PP cells appear to possess amine-handling properties, a feature common to many peptide hormone-producing cells. The ultrastructure of the PP cells was defined by combining immunohistochemistry of semi-thin plastic sections with electron microscopy of adjacent ultrathin sections. PP cells show the ultrastructural features of peptide hormone-secreting cells. The PP cells of cat and dog contain fairly large, rather electron-lucent granules, and are probably identical with the previously described F cells. The PP cells of rat, guinea-pig, chinchilla and man contain small, fairly electron-dense granules. In these latter species no F cells are found. By immunoperoxidase staining of ultrathin sections, the PP immunoreactivity was found to be localized to the cytoplasmic granules. These observations provide support for the view that PP is a true pancreatic hormone.
343 citations
TL;DR: The Barkas effect is the difference in stopping of swift, positive and negative particles as mentioned in this paper, and it concerns the theory of higher Z1-corrections to the Bethe formula.
261 citations
206 citations
TL;DR: If gastrin-like peptides occur in the pancreatic A1 cells they must be devoid of the bioactive, C-terminal sequence, and it is concluded that radioimmunoassayable pancreatic gastrin occurs at levels far below those expected if the A2 cells stored gastrin.
Abstract: IT has been suggested1,2 that pancreatic gastrin is stored in islet A1 (or D) cells. There are, however, conspicuous histological and histochemical differences between antral gastrin cells and A1 cells, indicating the storage of different peptide molecules in these two types of cell3,4. Furthermore, pancreatic tumours producing gastrin are composed of cells that have no features in common with A1 cells but often resemble antral gastrin cells5,6. We have now tested a large number of gastrin antisera, most of which were specific for the C-terminal, bioactive, sequence of gastrin-17, on both unfixed and formaldehyde-fixed tissue, and found that all antisera reacted with antral gastrin cells but not with A1 cells. Also, radioimmunoassayable pancreatic gastrin occurs at levels far below those expected if the A1 cells stored gastrin7. We conclude that if gastrin-like peptides occur in the pancreatic A1 cells they must be devoid of the bioactive, C-terminal sequence. While studying the ontogeny of the rat gastrin cell we have, however, found, at a certain stage of development, true gastrin cells in the pancreas.
190 citations
181 citations
TL;DR: A questionnaire follow‐up of the physical and mental development of lithium children who were not malformed at birth does not reveal any increased frequency of physical or mental anomalies among the lithium children.
Abstract: The Lithium Baby Register was founded in 1968 to determine the frequency of abnormalities among children born to mothers who were given lithium during the first trimester of pregnancy. Previous studies have revealed an increased frequency of congenital malformations, possibly due to teratogenic action of lithium. The present report is a questionnaire follow-up of the physical and mental development of lithium children who were not malformed at birth. Sixty lithium children were examined; their siblings, who had not been exposed to lithium during fetal life, served as a control group. The data obtained do not reveal any increased frequency of physical or mental anomalies among the lithium children.
167 citations
TL;DR: Studies of this vertebrate smooth muscle actomyosin show that the regulation of the actin-myosin interaction is effected, as in molluscan muscles, by the myosin molecule itself and not by an act in-linked regulatory system, as found in vertebrate skeletal muscle.
150 citations
TL;DR: In fifteen patients with hyperkalaemic familial periodic paralysis, inhalation of salbutamol alleviated hyperkaleamia and paralysis precipitated by exercise or oral administration of potassium chloride.
147 citations
TL;DR: The effects of pH, temperature and salts on the oxygenation properties of the (isolated) haemoglobins are reported and discussed in relation to the varying environmetal conditions encountered by eels, and compared with data on American and Japanese eels.
Abstract: Unlike the whole body oxygen affinity, which adapts readily to environmental oxygen tensions, haemoglobins, prepared from normoxic- and hypoxic-accimated eels (Anguilla anguilla) show no adaptive changes in oxygenation properties or in multiplicity. Hypoxic acclimation is, howeveer, accompanied by a strong decrease in red cell nucleoside triphosphates, particularly guanosine triphospphate (GTP), which depresses oxygen affinity of the composite and component haemoglobins more strongly than does the concurring ATP. The effects of pH, temperature and salts on the oxygenation properties of the (isolated) haemoglobins are reported, discussed in relation to the varying environmetal conditions encountered by eels, and compared with data on American and Japanese eels (A. rostrata and A. juponica, respectively.
01 Jan 1976
TL;DR: It was found that extraverted subjects showed less responsiveness to moderate intensity stimuli, whereas high neuroticism or anxiety prone subjects showed more spontaneous fluctuations and better electrodermal conditioning when conditioned responses were scored relative to unconditioned responses.
Abstract: .— Recording skin resistance in 34 young women it was found that extraverted subjects showed less responsiveness to moderate intensity stimuli, whereas high neuroticism or anxiety prone subjects showed more spontaneous fluctuations and better electrodermal conditioning when conditioned responses were scored relative to unconditioned responses. Further, the subjects were rated for ‘schizophrenism’ according to an inventory devised by the authors. The high schizophrenism subjects behaved electrodermally very much like the pre-schizophrenic sample in Mednick and Schulsinger's prospective study of schizophrenia; they exhibited faster recovery, greater response amplitude to aversive stimuli and faster initial habituation to these stimuli.
TL;DR: In this article, a prescription for exchange and correlation in the density-functional formalism with a nonlocal density dependence is given, which is exact in the almost homogeneous limit, charge-conserving, and always finite.
TL;DR: The present study was undertaken in an at tempt to further delineate the localization and nature of the metals in question and to show that application of chelating drugs, which abolish Timm stainability, has pronounced behavioural effects.
TL;DR: The striking increase in O2-Hb affinity during estivation is regarded as an adaptation to a reduced alveolar O2 availability associated with estivation.
TL;DR: In this paper, a selfconsistent calculation for hydrogen chemisorption is reported, where the surface is described both by the jellium model and by a model that includes ion pseudopotentials to lowest order.
Abstract: A self-consistent calculation for hydrogen chemisorption is reported, where the surface is described both by the jellium model and by a model that includes ion pseudopotentials to lowest order. It predicts that for H on Al(100) a bridge configuration is the most favorable (binding energy 1.9 eV), and that the activation energy for surface diffusion is 0.1-0.2 eV.
TL;DR: Chronic renal failure treatment in chronic renal failure does not affect the progressive loss of calcium from bone despite normalisation of plasma-calcium, and 1α-H.C.C., a double-blind placebo-controlled trial, concludes.
TL;DR: The high O2 affinity of Heterocephalus blood is viewed as a possible adaptation to its burrowing habits and not dependent upon cofactor influence or the temperature sensitivity of the O2-Hb binding.
TL;DR: In this article, an x-ray standing-wave-field apparatus has been constructed that demonstrates an impurity atomic position resolution of 0.02 \ensuremath{\sim} 0.2 \AA{}.
Abstract: An x-ray standing-wave-field apparatus has been constructed that demonstrates an impurity atomic position resolution of \ensuremath{\sim}0.02 \AA{}. The method is applied to the measurement of ion-implantation-induced lattice relaxation. It is pointed out that the method is also suited to determine surface impurity locations perpendicular to crystal surfaces.
TL;DR: These findings argue against a simple, virally determined repressor model and emphasize the role of cellular controls in restricting the EBV cycle in virus‐carrying B‐lymphocyte lines of human origin.
Abstract: Two EBV-negative lymphoma lines of human B-cell origin, BJAB and Ramos, were compared with altogether six of their in vitro EBV-converted, EBNA- and EBV-DNA-carrying sublines (four of Ramos and two of BJAB derivation). All converted lines closely resembled the parental line with regard to karyotype and HL-A and B antigen typing. Induction of EBV antigens (EA and VCA) by P3HR-1 virus superinfection was either similar in the converted and the negative lines, or somewhat increased in certain converted lines. These findings argue against a simple, virally determined repressor model and emphasize the role of cellular controls in restricting the EBV cycle in virus-carrying B-lymphocyte lines of human origin. IUdR inducibility varied in the different converted lines. There was a possible relationship between average number of EBV-genome equivalents per cell and inducibility. Converted sublines did not differ from the original negative lines with regard to surface immunoglobulin and Fc receptors. There was a dramatic increase in complementconsuming ability, however, following EBV conversion. Among the EBV-positive lines, there was a linear relationship between complement-consuming and EBV-receptor activity, the latter measured by a quantitative absorption test.
Inductibilite Du Cycle Du Virus D'Epstein-Barr (EBV) Et Proprietes Des Marqueurs De La Surface Des Lignees De Lymphome EBV-Negatives Et De Leurs Sous-Lignees Transformees in vitro par L'EBV
Deux lignees de lymphome EBV-negatives provenant de cellules B humaines, BJAB et Ramos, ont ete comparees avec six de leurs sous-lignees transformees in vitro par l'EBV et portant l'EBNA et l'ADN de l'EBV (quatre sous-lignees Ramos et deux BJAB). Toutes les lignees transformees ressemblaient etroitement a la lignee parentale du point de vue du caryotype et du typage des antigenes B et HL-A. L'induction des antigenes de l'EBV (EA et VCA) par surinfection avec le virus P3HR-1 etait soit analogue dans les lignees transformees et les lignees negatives, soit legerement superieure dans certaines lignees transformees. Ces constatations ne concordent pas avec l'hypothese d'un modele de represseur simple, determine par le virus, et mettent en evidence le rǒle des contrǒles cellulaires dans la restriction du cycle de l'EBV dans les lignees de lymphocytes B d'origine humaine qui hebergent le virus. L'inductibilite sous l'effet de l'IUdR varie selon les lignees transformees. Il existe peut-ětre un rapport entre le nombre moyen d'equivalents du genome EBV par cellule et l'inductibilite. Les lignees transformees ne different pas des lignees negatives initiales du point de vue de l'immunoglobuline de la surface et des recepteurs Fc. On a toutefois constate une augmentation frappante de la capacite d'epuisement du complement apres la conversion par l'EBV. Dans les lignees EBV-positives, on a note un rapport lineaire entre l'epuisement du complement et l'activite des recepteurs de l'EBV, cette derniere ayant ete mesuree au moyen d'un test d'absorption quantitatif.
TL;DR: In this article, a survey points to the age-old European interest in the role of small states, almost ignored in the recent literature on small states and it is shown that the numerous attempts to define a small sta...
Abstract: The survey points to the age-old European interest in the role of small states, almost ignored in the recent literature on small states. It is shown that the numerous attempts to define a small sta...
TL;DR: G-strophanthin binding to (Na + + K + )- activated ATPase from ox brain was studied as a function of the P i concentration with the (Mg 2+ +P i )-facilitated pathway, resulting in curved lines.
TL;DR: Hydstatic and oncotic water conductance of the rabbit proximal tubule changes with postnatal development and ultrastructural tracer studies suggest that the change in conductance is due to alteration of the paracellular pathway.
TL;DR: The backputtering yield of gold bombarded with gold ions has been measured in the energy range from 60 keV to 20 MeV as discussed by the authors, where the targets were polycrystalline, self-supporting gold foils, 3000-6000 A thick, and the sputtering yield was determined by measuring the thickness decrease of the target by means of forward scattering of protons.
TL;DR: In this article, the impact-parameter dependence of inner-shell ionization was investigated by measuring the impact parameter dependence of Cu-K shell ionization by H, Be, C, and O, at energies corresponding to 2 MeV/amu.
TL;DR: In this article, it was shown that a strongly connected digraph with n vertices and minimum degree ⩾ n is pancyclic unless it is one of the graphs Kp,p.
TL;DR: The Santorini caldera walls of the ring-islands of the southern Aegean are built up of lavas and pyroclastics, among which pumice layers are particularly striking as mentioned in this paper.
Abstract: THE caldera walls of the ring-islands Thera and Therasia, belonging to the Santorini Group (Fig. 1) in the southern Aegean, are built up of lavas and pyroclastics, among which pumice layers are particularly striking (Fig. 2). The top layer (Bo, abbreviated from the German term “oberer Bimsstein”1) comprises air-fall pumice and ashes, overlain by thick pyroclastic flows2,3. It was produced by the catastrophic outburst of the Thera volcano in late-Minoan time, which culminated in the collapse of the Santorini caldera4. The decline of the Minoan civilisation around 1500 BC has been attributed to these volcanic events5. The Upper Pumice Series buried late-Minoan settlements on Thera and Therasia, and an important settlement near Akrotiri in the southern part of Thera is still being excavated6. The Upper Pumice Series rests on an old soil horizon (black layer in Fig. 2) in which remnants of late-Minoan houses were found in 1869 (ref. 7). Wood from such houses found at the base of the pumice quarries south of the town of Fira has provided radiocarbon dates of 3,370±100 yr b.p. (ref. 8). This age coincides exactly with archaeological data for the destruction of late-Minoan settlements on Santorini6.
TL;DR: The results show that protein uptake in proximal tubule cells, transport into lysosomes and the digestion of protein is a more rapid process than previously reported in ultrastructural studies.