Showing papers by "University of Antwerp published in 1979"
TL;DR: Pericardium, pleura and peritoneum form substantially high amounts of prostacyclin and HETE indicating that these tissues contain both cyclo-oxygenase and prostacyClin-synthetase, and they also show considerable lipoxygen enzyme activity.
108 citations
TL;DR: In this article, a study by means of electron microscopy at high resolution has enabled the analysis of the microstructure of hematite as produced by dehydration from goethite.
63 citations
TL;DR: In this article, the authors reanalyzes the problem of competitive bidding with asymmetric information and derive an equilibrium that is essentially zero for the party with incomplete information, which is different from Wilson's solution and yields a simple explanation for the case cited by Wilson.
Abstract: This note reanalyzes the following problem, formerly treated by Wilson Wilson, R. B. 1967. Competitive bidding with asymmetric information. Management Sci.13 July 816--820: two parties have to submit bids for an object One of them knows the value with certainty, the other does not. The equilibrium derived differs from Wilson's solution and yields a simple explanation for the case cited by Wilson: the value of the game is essentially zero for the party with incomplete information.
62 citations
TL;DR: The relative merits of eight procedures for preconcentrations of trace metal ions from natural water samples and synthetic solutions are evaluated in this paper, where the quantitative characteristics of these techniques and the influence of the water matrix effects are discussed, as well as the applicability for x-ray fluorescence analysis.
51 citations
TL;DR: In this article, it was shown that the satellites observed in the diffraction pattern of the dehydrated single crystal of the mineral goethite are better interpreted in terms of small angle scattering by a "texture" of the dehydration product hematite.
49 citations
TL;DR: The structures for umuravumbolide, 5,6-dihydro-6-(3-acetoxy-1-heptenyl)-2-pyrone, a new α pyrone from Iboza riparia (Labiatae) and its corresponding deacylated product have been established.
49 citations
34 citations
TL;DR: In this article, the authors compared linear and non-linear least square fitting procedures in their ability to resolve X-ray fluorescence spectra obtained with Si(Li) detectors.
Abstract: Linear and non-linear least-squares fitting procedures are compared in their ability to resolve X-ray fluorescence spectra obtained with Si(Li) detectors. It is shown, by repeated analysis of synthetic and real X-ray spectra, that non-linear least-squares fitting programs which take into account the relation between peak positions and widths on the one hand and X-ray energies on the other hand, and moreover impose limitations upon the fitting parameters, represent a definite advantage over the linear least-squares fitting method. Only for spectrometers having an extremely high stability with time and counting rate does the linear fitting procedure yield accurate results.
32 citations
TL;DR: Production of Hb III and lactic acid, being inversely proportional to the acclimation level, has to be considered as a long term or short term adaptation to hypoxic conditions.
32 citations
TL;DR: In this article, the analytical data obtained for the organic composition of airborne particulate matter collected with a high volume cascade impactor and a filtration sampler were compared and it was concluded that both sampling and analytical procedures give consistent results for organic compounds of low volatility.
32 citations
TL;DR: A new subclass of dgsm mappings is introduced, the so-called symmetric dgSm mappings, which it is proved that (unlike for arbitrary dg sm mappings) their fixed-point languages are regular but not effectively obtainable.
Abstract: This paper considers equality languages and fixed-point languages of homomorphisms and deterministic gsm mappings. It provides some basic properties of these classes of languages. We introduce a new subclass of dgsm mappings, the so-called symmetric dgsm mappings. We prove that (unlike for arbitrary dgsm mappings) their fixed-point languages are regular but not effectively obtainable. This result has various consequences. In particular we strengthen a result from Ehrenfeucht, A., and Rozenberg, G. [(1978), Theor. Comp. Sci. 7, 169–184] by pointing out a class of homomorphisms which includes elementary homomorphisms but still has regular equality languages. Also we show that the result from Herman, G. T., and Walker, A. [(1976), Theor. Comp. Sci. 2, 115–130] that fixed-point languages of DIL mappings are regular, is not effective.
TL;DR: In this paper, the effective sample weight is computed from the scatter peaks, a method that cancels out target heterogeneity problems, and results for 16 trace elements and preliminary interpretation are given for a series of pedologically important soil samples from Brasil.
TL;DR: It is suggested that the 27 000-Mr protein and Artemia elongation factor eEF-Ts might be related to each other on the basis of amino acid composition and immunological cross-reactivity.
Abstract: The cytoplasm of the cryptobiotic Artemia salina gastrula contains a large quantity of a unique 19-S complex. This particle is a specific aggregated form of a 27000-Mr protein, having a molecular weight of 106 and an apparent buoyant density of 1.25–1.26 g/cm3 in sucrose and 1.31 g cm3 in CsCI. The relative quantity of this 19-S complex decreases significantly with respect to 80-S monoribosomes during the postgastrula development. Biochemical and immunological studies indicate that the 27000-Mr protein is one of the RNA-binding proteins [Ovchinnikov et al., FEBS Lett. 88, 21–26 (1978)] but is absent in the protein components associated with poly(A)-containing ribonucleoprotein complexes. The possibility is also suggested that the 27000-Mr protein and Artemia elongation factor eEF-Ts might be related to each other on the basis of amino acid composition and immunological cross-reactivity.
TL;DR: It is concluded that the acquisition of impermeability in the developing gastrula embryo plays an essential role in the normal embryonic development in Artemia salina.
TL;DR: The resulting algorithm is suitable for solving (n+1)-th order recursions (n≥1) for which there existn independent solutions that are dominated by each solution that does not belong to the space spanned by thesen solutions.
Abstract: In one of his papers [5] Gautschi presents an algorithm for determining the minimal solution of a second-order homogeneous difference equation. The method is based on the connection between the existence of a minimal solution of such a difference equation and the convergence of a certain continued fraction. In the present paper, these results are generalized. For this purpose we use the concept of generalized continued fraction. The resulting algorithm is suitable for solving (n+1)-th order recursions (n≥1) for which there existn independent solutions that are dominated by each solution that does not belong to the space spanned by thesen solutions.
TL;DR: In this paper, a study has been made of possible interferences upon the determination of selenium by hydride generation atomic absorption spectrometry (HGAAS), due to the presence of other hydrides forming elements such as As, Ge, Bi, Te, Sn and Sb, and to a volatile element such as Hg.
Abstract: A study has been made of possible interferences upon the determination of selenium by hydride generation atomic absorption spectrometry (HGAAS), due to the presence of other hydride forming elements such as As, Ge, Bi, Te, Sn and Sb, and to a volatile element such as Hg The interfering effects of these cations were determined at several concentration levels using sodium borohydride as the reductant and a commercially available semi-automatic system for the generation and the flameless combustion of the hydrides It has been demonstrated that the determination of selenium by HGAAS is relatively free from interferences with regard to other elements that form volatile hydrides, except for tin and bismuth that strongly interfere
TL;DR: The authors confirm that anal pressure measurements record only the tonus of the sphincter apparatus and are not influenced by the volume of the hemorrhoidal masses themselves.
Abstract: In this study, the authors recorded pre- and postoperative anal resting pressures in 28 patients with hemorrhoidal disease and in 32 controls. No significant difference was found between these two groups preoperatively. In the patient population anal pressure was significantly lowered following Lord's anal dilation treatment. No such pressure reduction was recorded after a standard St. Mark's hemorrhoidectomy. Finally, the authors confirm that anal pressure measurements record only the tonus of the sphincter apparatus and are not influenced by the volume of the hemorrhoidal masses themselves.
TL;DR: It is concluded that no major morphological differences between Sanfilippo disease types A and C can be observed.
Abstract: Anatomopathological studies of one case of Sanfilippo disease types A and C, respectively, are presented. The storage phenomenon is very severe in the central as well as in the peripheral nervous system of both patients. Light microscopy does not show significant differences between the two cases. Electron microscopy of the nervous system reveals in both cases the presence of variable amounts of zebra bodies and of membrano-granulo-vacuolar inclusions. The presence of larger amounts of zebra bodies in the type A case and of larger quantities of membrano-granulo-vacuolar inclusions in the type C case constitute probably a non-distinctive feature between the two types. Light and electron microscopic studies of visceral organs do not disclose significant differences either. It is concluded that no major morphological differences between Sanfilippo disease types A and C can be observed.
TL;DR: This paper found that the rounded member of the pairs /i-y/ and /e-o/ was centralized and the rounded vowel bears a different relationship to its unrounded counterpart.
Abstract: Traditional articulatory descriptions of front rounded and unrounded vowel pairs have assumed that tongue height is the same for the members of the pairs /i-y/, /e-o/, and /e-œ/. The electromyographic, articulatory synthetic, and acoustic investigations carried out in this study indicate that, in Dutch, the rounded member of the pairs /i-y/ and /e-o/ was centralized. In the /e-œ/ pair, however, the rounded vowel bears a different relationship to its unrounded counterpart.
TL;DR: In this paper, a method for simultaneous determination of inorganic and organic lead compounds in air is described, together with some results from its application at different sampling sites, where a cellulose filter is subjected to low-temperature ashing, after which the lead content in the residue is measured by electrothermal atomic absorption spectrometry.
01 Sep 1979
TL;DR: A different presentation of the Generator Coordinate Method is used to explain why, in spite of their being bad approximations to the Hill-Wheeler integral, discretisation techniques are so successful in GCM.
Abstract: A different presentation of the Generator Coordinate Method is used to explain why, in spite of their being bad approximations to the Hill-Wheeler integral, discretisation techniques are so successful in GCM. A particular technique, which then appears appropriate, is discussed in detail.
TL;DR: Ca2+ is an essential cofactor for the trypanocidal activity of normal human serum, in which α2 macroglobulin (α2) might function as a Ca2+-carrier, and it is shown that D-glucose, D-fructose and D-mannose can suppress the try panocidal action of normalhuman serum, whereas glycerol has the opposite effect.
Abstract: Normal human serum has been known to exert a cytotoxic effect on Trypanosoma brucei subspecies for nearly 80 yr1. But in spite of many attempts, no trypanocidal factor was found in human or baboon serum2–6, until Rifkin demonstrated a high density lipoprotein (HDL) in normal human serum with trypanocidal activity7. The conclusion that this was the trypanocidal factor was supported by the report that serum from patients with Tangier disease, characterised by a severe deficiency of HDL, lacked trypanocidal activity7. We report here that Ca2+ is an essential cofactor for the trypanocidal activity of normal human serum, in which α2 macroglobulin (α2) might function as a Ca2+-carrier. We further show that D-glucose, D-fructose and D-mannose can suppress the trypanocidal action of normal human serum, whereas glycerol has the opposite effect.
TL;DR: A reformulation of an algorithm developed by F.W.J. Olver for the numerical solution of second-order difference equations is presented in this paper, which requires less computations and needs no adaptations in case certain coefficients vanish.
Abstract: A reformulation of an algorithm developed by F.W.J. Olver for the numerical solution of second-order difference equations is presented. It requires less computations and needs no adaptations in case certain coefficients vanish. It has also the advantage of avoiding overflow in some special cases.
TL;DR: In this article, a discussion is given concerning the transformation of curite into meta-torbernite in an acid environment and the surface conductivity is calculated from the measured zeta-potential.
Abstract: A discussion is given concerning the transformation of curite into meta-torbernite in an acid environment. Crystallographic data together with differential thermal analysis show that the end-product obtained by this method is identical with meta-torbernite. Measurements of the zeta-potential on these meta-torbernite specimens result in negative values, which are strongly influenced by pH and NaCl concentrations. The surface conductivity is calculated from the measured zeta-potential.
TL;DR: Net photosynthetic and dark respiration rate, stomatal and internal resistances to carbon dioxide, and chlorophyll concentrations were lowest at LPI lower than 10 although an increase in two steps was found, when leaf age increases up to maturity.
Abstract: Net photosynthetic (PN) and dark respiration (RD) rate, stomatal (rs′) and internal (ri′) resistances to carbon dioxide were measured by gas exchange methods on leaves of different ages, expressed in leaf plastochron index units (LPI) for a fast growing poplar cultivar Unal 2. Although the optimal leaf age differs slightly for the different gas exchange parameters, leaf ontogeny is reflected in the same way in these different parameters. MaximalPN and minimalrs′ and ri′ values were found at LPI between 6 and 10. Chlorophyll concentrations were lowest at LPI lower than 10 although an increase in two steps was found, when leaf age increases up to maturity.
TL;DR: Flash and pattern VER might be even more pathognomonic in MS than oligoclonal gammaglobulin fractionation on agar, positive in 75% of cases and it is suggested that subclinical MS cases should be submitted to full electro-ophthalmographic investigation.
Abstract: Until a few years ago, the diagnosis of a demyelinating disease as multiple sclerosis (MS) was finally decided only according to the clinical symptomatology and classified in probable, possible, and established cases [13].
TL;DR: In this paper, the low-field polaron mobility at weak and intermediate coupling has been studied in the framework of a self-consistent equation-of-motion approach developed earlier by the present authors.
Abstract: The low-field polaron mobility at weak and intermediate coupling has been studied in the framework of a self-consistent equation-of-motion approach developed earlier by the present authors. It is shown that the possibility of internal excitations of polarons leads to a decrease of the mobility at relatively strong coupling. The theoretical results are compared with previous theoretical work and with experimental results in the case of AgBr, AgCl, KBr, and KCl in the temperature range where electron-LO-phonon scattering is predominant.
TL;DR: A possible role of prostaglandins and their precursors in autoregulation of mesenteric blood flow in the pig is suggested, after previous blockade of the PG synthetase and lipoxygenase pathways with indomethacin and ETA.