Showing papers by "Stockholm University published in 1975"
TL;DR: The theory of types as mentioned in this paper is a full-scale system for formalizing intuitionistic mathematics as developed, which allows proofs to appear as parts of propositions so that the propositions of the theory can express properties of proofs.
Abstract: Publisher Summary The theory of types is intended to be a full-scale system for formalizing intuitionistic mathematics as developed. The language of the theory is richer than the languages of traditional intuitionistic systems in permitting proofs to appear as parts of propositions so that the propositions of the theory can express properties of proofs. There are axioms for universes that link the generation of objects and types and play somewhat the same role for the present theory as does the replacement axiom for Zermelo–Fraenkel set theory. The present theory is based on a strongly impredicative axiom that there is a type of all types in symbols. This axiom has to be abandoned, however, after it has been shown to lead to a contraction. This chapter discusses Normalization theorem, which can be strengthened in two ways: it can be made to cover open terms and it can be proved that every reduction sequence starting from an arbitrary term leads to a unique normal term after a finite number of steps. The definition of the notion of convertibility and the proof that an arbitrary term is convertible can no longer be separated because the type symbols and the terms are generated simultaneously.
725 citations
TL;DR: Xanthan gum, the extracellular polysaccharide from Xanthomonas campestris, has been reinvestigated by methylation analysis, and by uronic acid degradation followed by oxidation and elimination of the oxidized residue.
724 citations
358 citations
337 citations
TL;DR: A theoretical model is developed for the co-evolutionary relationship between adult oviposition preferences and larval feeding preferences for species in which the host plant choice is exercised by the adults.
Abstract: In Papilio machaon host plant utilization is argued to be proximally guided by adult and larval preferences, both of which are genetically determined. To decide whether these preferences are controlled by one or two gene complexes, oviposition preferences and larval survival of a Scandinavian population were investigated with regard to all potential host plants in the region. The experiments revealed a substantial difference between the potential host plant ranges of the adults and the larvae, indicating that adult and larval host plant preferences are determined by separate gene complexes.Based on this inference, a theoretical model is developed for the co-evolutionary relationship between adult oviposition preferences and larval feeding preferences for species in which the host plant choice is exercised by the adults.
313 citations
TL;DR: In this article, the authors extended the single-determinant Hartree-Fock studies on the equilibrium structures and stabilities of H2 O, H3 O+ as well as of the monohydrated ionic systems Li+ · H2O, F− · H 2 O and the hydrogen bonded water dimer, H2 o · HOH, by large scale configuration interaction calculations including all the possible single and double excitations arising from the canonical set of Hartree Fock molecular orbitals.
Abstract: Previous single-determinant Hartree-Fock studies on the equilibrium structures and stabilities of H2 O, H3 O+ as well as of the monohydrated ionic systems Li+ · H2O, F− · H2O and the hydrogen bonded water dimer, H2 O · HOH, are extended by large scale configuration interaction calculations including all the possible single and double excitations arising from the canonical set of Hartree-Fock molecular orbitals. The correlation energy effects on the equilibrium geometrical parameters of the systems under consideration are found to be quite small. The contributions of the correlation energy to the total binding energies of the weakly interacting composed systems are obtained to be of the order of 1 kcal/mole, leading to a considerable increase of the hydrogen bond strength in F− · H2O and H2O · HOH and to a small decrease of the binding energy in Li+ · H2 O. The observed strengthening of the hydrogen bonding interaction due to correlation is shown to be partly compensated by the change in the vibrational zero-point energy of the composed systems compared to the non-interacting subsystems. Approximate force constants corresponding to the intersystem vibrations in Li+ · H2O, F− · H2 O, and H2O · HOH are deduced from the calculated potential curve data on the SCF and the CI level of accuracy.
265 citations
TL;DR: A new radioactive assay for benzpyrene monooxygenase has been developed, characterized, and compared to the fluorescent assay generally employed and can be scaled down so that it is at least as sensitive as theorescent assay.
241 citations
TL;DR: Results indicate that the wheat germ agglutinin binding site is complementary to a sequence of three beta-(1 leads to 4)-linked N-acetyl-D-glucosamine units (N,N'N"-triacetyl chitotriose).
224 citations
TL;DR: In this paper, a generalized phase diagram for the lanthanides is constructed empirically, by means of which different phase transitions, both for an individual rare-earth element and intra-rare-earth alloys, can be correlated to certain critical values of a pseudopotential parameter.
Abstract: A "generalized" phase diagram is constructed empirically for the lanthanides. This diagram makes it possible, not only in one picture, to assemble a lot of information but also to predict phase transitions not yet experimentally accessible. Further, it clearly illustrates the close relation between the members of the lanthanide group. To account for some of its features, the pseudopotential method is applied. The trend in crystal structure through the lanthanide series can thereby be qualitatively accounted for, as can the trend in crystal structure for an individual element, when compressed. A scaling procedure makes it possible to extend our treatment to elements neighboring the lanthanides in the Periodic Table. In total 25 elements are considered. An atomic parameter $f$ (relatable to the pseudopotential) is introduced, by means of which different phase transitions, both for an individual rare-earth element and intra-rare-earth alloys, can be correlated to certain critical values of this parameter. A nonmagnetic rare-earth series (Sc, Lu, Y, La, and Ac) is introduced and the occurrence of superconductivity is discussed with special emphasis on the pressure dependence of the transition temperature. This temperature can be correlated to the above-mentioned parameter $f$, both for intra-rare-earth alloys and pure elements at different pressures. The found correlation implies that actinium is a superconductor with a critical temperature which could be as high as (11-12) \ifmmode^\circ\else\textdegree\fi{}K. It is also argued that the actinide series can be viewed upon as a second delayed rare-earth series. From this, several analogies between the two series are pointed out, which might throw new light upon several problems concerning the rare-earth themselves, e.g., the nature of the $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\alpha}$ transition in cerium and the occurrence of the dhcp structure in the light lanthanides. Finally, valence transitions at high pressure for europium and ytterbium are discussed. Calculations give that these elements should become trivalent at a pressure of the order of 150 kbar.
207 citations
TL;DR: It was suggested that the ferryl ion (compound I) of cytochrome P-450 is the common “activated oxygen” species in these hydroxylations.
162 citations
TL;DR: In this article, the chemical methods for specific or selective degradation of polysaccharides and their applications for structural analysis are discussed, including the application of consecutive degradations, each of which should ideally be quantitative, should facilitate determination of complicated structures with moderate effort.
Abstract: Publisher Summary This chapter discusses the chemical methods for specific or selective degradation of polysaccharides and applications of polysaccharides for structural analysis. The degradation of polysaccharides by the action of acids, followed by the fractionation and identification of the oligosaccharides formed, is one of the methods used frequently in structural polysaccharide chemistry, and it gives information both on sequences and anomeric configurations. In principle, any reaction that can be performed at the monomer level should be applicable to polysaccharides and rapid development in this field will be seen. Application of consecutive degradations, each of which should ideally be quantitative, should facilitate determination of complicated structures with moderate effort. G.l.c. an established method for the separation of the low-molecular weight products formed. Mass spectrometry and nuclear magnetic resonance spectroscopy, especially when combined with pulse Fourier transformation (PFT-n.m.r.), are becoming increasingly important for the characterization of the degradation products.
TL;DR: In this article, the authors present a diagram expressing the relationship between the height of the transient snow line and the annual specific net mass balance, provided detailed mass-balance studies have been performed during a period of several years of different mass balance conditions (ideally comprising both years of negative and of positive net balances).
Abstract: Due to increased demand for electric energy, which in Norway is produced almost entirely by hydro-electric power plants, extensive glacierized basins are now considered for future power production, However, glacier behaviour has a great impact on the annual run-off from these basins, and information about expected annual deviations from a “normal” discharge must be obtained from mass-balance studies on representative glaciers within the basin. For this reason such studies are presently performed at eight selected Norwegian glaciers; the costs involved are in the order of 10 000 annually for each observed glacier. The transient snow line can be identified easily on conventional air photographs and its height determined by direct comparisons with reliable topographie maps (with contour lines on glaciers). The resolution in ERTS images is sufficiently good to use the satellite data for a similar height determination of the transient snow line on glaciers—at least on the larger valley glaciers and, of course, on ice caps. Due to an existing correlation between the height of the transient snow line (at the end of the melt season) and the annual specific net mass balance, it is possible to construct a diagram expressing this relationship, provided detailed mass-balance studies have been performed during a period of several years of different mass-balance conditions (ideally comprising both years of negative and of positive net balances). Determinations of the transient snow-line height based upon ERTS data, obtained at the end of the summer season, can then be used to determine the mass balance for those glaciers where the above-mentioned relationship is established. This would be a great advantage in cases where there is a request for information on the net balance only; no separate data on winter balance or summer balance will be obtained by this method. Experiments have been performed to delineate the transient snow line on glaciers directly from ERTS digital data (CCT magnetic tape). The results indicate that last winter’s snow is characterized by grey-levels 41-48 (of 63 possible grey-scale levels) on MSS-7, whereas exposed glacier ice is represented by levels 13—20 in the same multi-spectral band. Snow and ice can also be separated on MSS-4, but the difference in grey-scale levels between the two materials is much smaller.
TL;DR: Two forms of glutathione S-aryltransferase were purified from rat liver and the only differences noted between the two forms were in the chromatographic and electrophoretic properties, which permitted the separation of the two species.
Abstract: Two forms of glutathione S-aryltransferase were purified from rat liver. The only differences noted between the two forms were in the chromatographic and electrophoretic properties, which permitted the separation of the two species. The molecular weights of the enzyme and its subunits were estimated as about 50000 and 23000 respectively. The steady-state kinetics did no follow Michaelis-Menten kinetics when one substrate concentration was kept constant while the second substrate concentration was varied. Several S-substituted GSH derivatives were tested as inhibitors of the enzymic reaction. The enzyme was inactivated by thiol-group reagents.
TL;DR: Results show that more approximate analyses for order parameters and correlation times can yield incorrect conclusions, and that decreasing rates of pseudoisotropic motion lead to incorrect estimates of rotational correlation times, which can result in the inference of an artifactual phase transition in the lipids.
TL;DR: The tentative conclusion is that the carbohydrate moiety of carcinoembryonic antigen does not contain the tumor-associated determinant(s).
Abstract: The carbohydrate moiety of carcinoembryonic antigen could be sequentially degraded by repeated cycles of periodate oxidation, reduction, and mild acid hydrolysis (Smith degradation). After three complete degradations, all fucose and sialic acid, 80% of the galactose, 65% of the mannose, and about 40% of the N-acetylglucosamine were eliminated without impairing the ability of degraded carcinoembryonic antigen to react with specific antisera against the antigen. Inhibition studies in a carcinoembryonic antigen/rabbit anti-carcinoembryonic antigen precipitating system with oligosaccharides covering previously known internal structures of glycoproteins and presumably corresponding to the internal carbohydrate region of the antigen, demonstrated that none of the compounds tested was inhibitory. Nor could any inhibitory effect on the binding of carcinoembryonic antigen to antibody against the antigen in a radioimmunoassay system be domonstrated for the carbohydrate moiety prepared by hydrazinolysis or the glyco peptide fraction isolated after papain degradation of the antigen. However, if carcinoembryonic antigen is completely reduced and alkylated, with three intrachain disulfide bonds cleaved per 10-5 g, the immunological activity is reduced to 3-5% of untreated antigen. Furthermore, treatment of the antigen with 0.5 NaOH at 20 degrees for 2 hr completely abolished its ability to react with antiserum, whereas its ability to precipitate with a series of lectins was unchanged. No release of low-molecular-weight carbohydrate orchange in sugar composition of alkali-treated antigen was observed. Our tentative conclusion is that the carbohydrate moiety of carcinoembryonic antigen does not contain the tumor-associated determinant(s).
TL;DR: In this article, the conversion relation conv is interpreted as definitional equality in the model, and definitional equivalence is a notion that is unmentionable within the classical set theoretic framework.
Abstract: Publisher Summary This chapter is devoted to the formulation of the most natural notion of model for intuitionistic theories that either are type theories by their very definition or may be viewed as such because of the correspondence between formulae and type symbols. The chapter analyzes the notion of definitional equality and its formal counterpart, convertibility, and advocates a change in the current definition of convertibility for systems in which explicit definitions are represented by means of lambda abstraction rather than the introduction of constants or the special constants called combinators. Because of the correspondence between lambda terms and natural deductions, this change is equally called for in Prawitz's definition of convertibility for natural deductions. The chapter also outlines that the transition to intuitionistic abstractions on the metalevel is essential and nontrivial; essential, because they are the most fruitful notion of model, the interpretation of the convertibility relation conv, is standard, that is, it is interpreted as definitional equality in the model, and definitional equality is a notion that is unmentionable within the classical set theoretic framework.
TL;DR: The elucidation of the molecular mechanism of photosensitized hemolysis of red blood cells may give important clues to the primary events underlying the phototoxic reactions observed in pathological conditions such as porphyria and induced by photosensitizing drugs.
Abstract: — The elucidation of the molecular mechanism of photosensitized hemolysis of red blood cells may give important clues to the primary events underlying the phototoxic reactions observed in pathological conditions such as porphyria and induced by photosensitizing drugs. Sensitizers effective in photo-hemolysis are porphyrins, the tryptophan metabolite kynurenic acid, and phototoxic drugs such as chlor-promazine and demethylchlortetracycline. Utilizing the singlet oxygen quenchers. jS-carotene and histi-dine and the large deuterium effect on the lifetime of singlet oxygen previously described by us, good evidence of the participation of this excited molecular species in the photohemolysis in the presence of kynurenic acid was obtained. Chlorpromazine and demethylchlortetracycline clearly act by a non-singlet oxygen pathway. The situation observed with haematoporphyrin is less clear and may represent a mixed Type I-Type II mechanism.
TL;DR: Children, 9–10 years old, solved all additions with the sum of two positive addends smaller than 14 to constitute an important starting point and frame of reference for the analysis and understanding of the cognitive process activated when children solve arithmetic problems.
TL;DR: In this paper, the basic transfer equation interrelating sources and sinks for atmospheric pollutants through the turbulent processes in the atmosphere is reformulated in a statistical manner, which assumes in some regards a statistical independence of the physical and chemical processes being considered.
Abstract: The basic transfer equation interrelating sources and sinks for atmospheric pollutants through the turbulent processes in the atmosphere is reformulated in a statistical manner, which assumes in some regards a statistical independence of the physical and chemical processes being considered. Since on the regional scale the synoptic disturbances are the essential turbulent elements, their statistics is considered in some detail using geostrophic trajectory computations. The various scales of atmospheric turbulence are analyzed with regard to their importance for vertical transfer. The sink mechanisms of rain-out and wash-out (interior sinks) and direct deposition at the lower boundary (boundary transfer) are also described statistically. The sceleton of a regional dispersion model is developed and its advantages and limitations are discussed. As an example a simplified study of the emission, dispersion and removal of atmospheric sulfur is presented. DOI: 10.1111/j.2153-3490.1975.tb01679.x
TL;DR: Evidence is presented that these two classes of anticoagulants, although both acting as competitive inhibitors with respect to NAD(P)H, bind to different sites of the enzyme in a synergistic fashion, interpreted as indicative of a cooperativity between different substrate-binding sites ofThe enzyme.
TL;DR: The formation of mature tetrads almost certainly occurred independently in Camissonia and may have done so in Ludwigia and the Epilobieae, and Morphological diagnoses of monad units indicated that individual taxa could be readily distinguished.
Abstract: In Onagraceae, pollen is shed in mature tetrads in most Epilobieae, many species of Ludwigia (Jussiaeeae), and two closely related species of the large genus Camissonia (Onagreae). Mature tetrads of Camissonia cardiophylla and representative species of Epilobium and Ludwigia were examined with light, scanning, and transmission electron microscopes. Morphological diagnoses of monad units indicated that individual taxa could be readily distinguished. Statistical analyses of tetrads which remained after acetolysis treatment revealed significant differences in the strength of the binding mechanisms. Mechanisms of tetrad cohesion were found to consist of two principal types. Common to all taxa is cohesion of pollen wall surfaces at the aperture margins; this mechanism is well known in many angiosperm groups. With the exception of Camissonia, the remaining taxa also display binding by means of short exine fragments between adjacent pollen units. These fragments, termed bridges and reported here for the first time, are located in the area extending from the aperture margins to near the center of the proximal exine faces. Thin sections reveal that layers of the bridges are identical with those of the exine. Comparisons were made between bridges and viscin threads, both of which occur on the proximal faces of the grains. Viscin threads are present on all pollen grains in Onagraceae and exhibit distinctive morphologies, and bridges were viewed morphogenetically as related to viscin threads but including an endexine layer and occupying a position near the apertures where cohesion of wall surfaces also occurs. In an evolutionary sense, the formation of mature tetrads almost certainly occurred independently in Camissonia and may have done so in Ludwigia and the Epilobieae.
TL;DR: In this paper, the adsorption of some polar volatile compounds on glass capillary columns has been investigated, and it was shown that a thin layer of non-extractable Carbowax 20M provides a well deactivated surface for further coating with polar or non-polar stationary phases.
TL;DR: The effect of several proteolytic and lipolytic enzymes on intact microsomal vesicles is demonstrated using vesicle permeable to macromolecules the inner surface was digested by these enzymes and the chemical constituents analyzed.
TL;DR: A comparison of the eyes, their location and retinal organization shows that among hagfishes an evolutionary trend towards reduction of the visual capability and a degeneration of the Eyes is evident.
TL;DR: The reduction of mixed disulphides of some proteins and GSH [Protein(-SSG)n] is accomplished with GSH as a reductant and a thioltransferase from rat liver as a catalyst, thus: See article.
Abstract: The reduction of mixed disulphides of some proteins and GSH [Protein(-SSG)n] is accomplished with GSH as a reductant and a thioltransferase from rat liver as a catalyst, thus: See article. The spontaneous reaction is negligible in comparison with the enzymic reaction in vivo, and any direct reduction with glutathione reductase is not detectable with the substrates used. The reduction is only indirectly dependent on NADPH, which is required for the regeneration of GSH from GSSG. Other protein disulphides apparently are reduced via analogous GSH-dependent reactions
TL;DR: In this article, an interpolation scheme for the binding energies of rare earth metals was proposed to give a good account for the cohesive energies of the rare-earth metals, starting with einsteinium.
Abstract: An interpolation scheme for the binding energies is shown to give a good account for the cohesive energies of the rare-earth metals. From this the divalent nature of europium and ytterbium can be concluded. The same method is applied to the actinide elements. The observed deviations from experiment are interpreted in terms of itinerant $5f$ states. Further, a divalent metallic character of the heavier actinide elements, starting with einsteinium, is predicted.
TL;DR: Kimberlitic zircons from 16 intrusions in Lesotho, the Republic of South Africa, and Tanzania have been investigated in this paper, and the following characteristics distinguish the kimberlite zircon from the zirons derived from most other sources: 1. Rounded to subrounded grains predominate; euhedral zircon are very rare.
Abstract: Kimberlitic zircons from 16 intrusions in Lesotho, the Republic of South Africa, and Tanzania have been investigated. The following characteristics distinguish the kimberlitic zircons from the zircons derived from most other sources: 1. Rounded to subrounded grains predominate; euhedral zircons are very rare. 2. Perfect parting in several directions, mainly (100) and (111). 3. Lattice distortions occur (decreasing molar volume). 4. High abundancy of fluid inclusions, occupying healed fractures. 5. Uranium contents less than 30 ppm U. Low contents of Th, Y, P, REE. 6. Whitish alteration rims composed of monoclinic and tetragonal zirconia in varying proportions are common. — The use of zircons in order to identify and trace kimberlite intrusives is discussed, as there may be a possible connection between some properties of the kimberlitic zircons and the diamond grade of their host rocks.
TL;DR: In this paper, the free radicals induced by γ-irradiation at 77 K in non-deuterated and fully deuterated oriented samples of moist algal DNA have been studied by electron paramagnetic resonance (e.p.r.).
Abstract: SummaryThe free radicals induced by γ-irradiation at 77 K in non-deuterated and fully deuterated oriented samples of moist algal DNA have been studied by electron paramagnetic resonance (e.p.r.). The e.p.r. spectra from the non-deuterated sample were found to be similar to those from calf-thymus DNA studied previously. Numerical spectra simulations were performed based on the previously proposed interpretation of the DNA spectra at 77 K in terms of a mixture of two spectral components arising from anionic and cationic base radicals (probably on thymine and guanine, respectively). The simulations were found to account satisfactorily for the main characteristics of the e.p.r. spectra from both the non-deuterated and the fully deuterated algal DNA sample.