Showing papers by "Katholieke Universiteit Leuven published in 1979"
TL;DR: In this paper, the evolution of the concept is traced back and a generalized definition is accepted, and various experimental methods are considered with which meaningful measurements of thixotropy can be performed.
Abstract: The time-dependent behaviour associated with thixotropy rather than with viscoelasticity is discussed. The evolution of the concept is traced back and a generalized definition is accepted. Subsequently, the various experimental methods are considered with which meaningful measurements of thixotropy can be performed. The specific experimental difficulties encountered with the systems under consideration are treated separately. It is impossible to enumerate all materials that show thixotropy or anti-thixotropy. Instead, they are classified in groups according to their origin or application. The resulting table is used to deduce the characteristics which accompany thixotropic phenomena. This leads to a discussion of the time effects in terms of the molecular or microscopic structure. An attempt is made to provide a systematic outline of the published models and possible constitutive equations for thixotropic materials. Both inelastic and viscoelastic descriptions are included.
481 citations
TL;DR: In this article, the class of subexponential distribution functions with Levy measure v was studied and the following assertions were proved: 1) For F infinitely divisible on [0, ∞] with Levy measures v, the following results on ∞ are established.
Abstract: Let ℒ denote the class of subexponential distribution functions. For F infinitely divisible on [0, ∞) with Levy measure v, the following assertions are proved to be equivalent:
In the proof of this theorem, some new results on ∞ are established.
330 citations
TL;DR: In this article, the lysine-binding sites in the plasmin A-chain were found to be responsible for the interaction with α 2 -antiplasmin.
279 citations
TL;DR: The interdigestive phase in man is characterized by periodic activity complexes comprising both motor and secretory components, which may have important implications for the interpretation of currently used functional tests of gastrointestinal secretion.
Abstract: Intraduodenal pH, bicarbonate and amylase secretion, and gastric acid and pepsin output were studied in relation to the migrating motor complex in man. The occurrence of a motor complex in the duodenum was preceded by an increase in gastric acid and pepsin output and followed by a peak in bicarbonate and amylase secretion. It is concluded that the interdigestive phase in man is characterized by periodic activity complexes comprising both motor and secretory components. These observations may have important implications for the interpretation of currently used functional tests of gastrointestinal secretion.
241 citations
TL;DR: The frequent occurrence of intermediate types of motility disorders and the transition from diffuse spasm to achalasia suggest that achalAsia and diffuse esophageal spasm are part of a spectrum of related motor disorders.
240 citations
186 citations
TL;DR: In this paper, the first two terms of the power series expansion for Fro(r) are computed for surfaces in RS and the coefficients of r n+~ for/r even can be expressed in terms of curvature.
Abstract: (Here o~-~the volume of the unit ball in R\". The simplest expression for eo is w = (1]( 89 \"/~ where ({rn)! ---F( 89 + 1).) First we make several remarks. 1. Our method for attacking the conjecture (I) will be to use the power series expansion for Vm(r). This expansion will be considered in detail in section 3; however, the general facts about it are the following: (a) the first term in the series is corn; (b) the coefficient of r n+~ vanishes provided k is odd; (c) the coefficients of r n+~ for/r even can be expressed in terms of curvature. Unfortunately the nonzero coefficients depend on curvature in a rather complicated way, and this is what makes the resolution of the conjecture (I) an interesting problem. 2. To our knowledge the power series expansion for Vm(r) was first considered in 1848 by Bertrand-Diguet-Puiseux [6]. See also [14, p. 209]. In these papers the first two terms of the expansion for Fro(r) are computed for surfaces in RS:
157 citations
TL;DR: It is reported here that the density of the conducting pores decreases with increasing Na+ activity, and it has been suggested that in this case saturation occurs through a [Na]o-dependent decrease in channel density.
Abstract: Many transport processes in biological membranes show a saturation of transport rate when the concentration of the transported ions or molecules is sufficiently increased. Saturation will result when at high concentrations a translocation step which does not directly depend on bulk concentration becomes rate limiting, and it is expected for all multi-step translocation mechanisms. However, a possible alternative explanation for saturation is a regulatory process which decreases the number of translocating channels in response to an increase in bulk concentration of the transported species. In the frog epidermis, Na+ uptake from the extracellular space into the epithelial cytosol occurs through Na+-selective, passively conducting channels located in the apical membrane of the cells directly below the cornified outer cell layer. Saturation of transport occurs with increasing outer Na+ activity ([Na]o): the net Na+ current1,2, membrane conductance2,3 and unidirectional Na+ influx4 increase only subproportionally with [Na]0. The apical Na+ current can transiently be larger than the saturation value, suggesting that a fixed upper single channel transport rate is not responsible for the saturation, and it has, therefore been suggested that in this case saturation occurs through a [Na]o-dependent decrease in channel density2. The Na+-translocation process can be investigated by a statistical evaluation of spontaneous transport fluctuations. The reversible transport blocker amiloride can be used to induce random fluctuations of the Na+ current at the apical membrane. The power density spectrum of these fluctuations is of the lorentzian type and permits an estimation of the Na+ current which passes through individual translocators in the time intervals between blocks5. We have recorded the current fluctuations at different [Na]o values and different amiloride concentrations in the [Na]o range in which saturation of total Na+ current is observed. We report here that the density of the conducting pores decreases with increasing [Na]o.
150 citations
TL;DR: Two female sibs are reported with a possibly new lethal malformation pattern, the major anomalies of which are coarse face with small eyes and cloudy corneae, cleft soft palate, hypoplasia and absence of lobulation of both lungs, diaphragmatic defects, digitalisation of thumbs and distal limb deformities.
Abstract: Two female sibs are reported with a possibly new lethal malformation pattern, the major anomalies of which are: coarse face with small eyes and cloudy corneae, cleft soft palate, hypoplasia and absence of lobulation of both lungs, diaphragmatic defects, digitalisation of thumbs and distal limb deformities.
149 citations
TL;DR: The plasmin-streptokinase-plasmin complex binds to Sepharose-lysine and SepHarose-fibrin monomer in the same fashion as free plasmine, showing that the lysine binding sites are fully exposed in the complex.
Abstract: Streptokinase reacts very rapidly with human plasmin (rate constant 5.4 × 107 M−1 s−1) forming a 1:1 stoichiometric complex which has a dissociation constant of 5 × 10−11 M. This plasmin-streptokinase complex is 105 times less reactive towards α2-antiplasmin than plasmin, the inhibition rate constant being 1.4 × 102 M−1 s−1. The loss of reactivity of the streptokinase-plasmin complex towards α2-antiplasmin is independent of the lysine binding sites in plasmin since low-Mr plasmin, which lacks these sites, and plasmin in which the sites have been blocked by 6-amino-hexanoic acid, are both equally unreactive towards α2-antiplasmin on reaction with streptokinase. The plasmin-streptokinase complex binds to Sepharose-lysine and Sepharose-fibrin monomer in the same fashion as free plasmin, showing that the lysine binding sites are fully exposed in the complex.
Bovine plasmin is rapidly inhibited by human α2-antiplasmin (k1= 1.6 × 106 M−1 s−1) and similarly loses reactivity towards the inhibitor on complex formation with streptokinase (50% binding at 0.4 μM streptokinase).
115 citations
TL;DR: Human antiplasmin, the fast-acting plasmin inhibitor in plasma, was purified to homogeneity and labeled with 125I and its turnover measured in control subjects and in patients undergoing thrombolytic therapy.
TL;DR: It is proposed that the previously described antithrombotic properties of Bay g 6575 in animals are due to stimulation of prostacyclin release from the vessel wall, and that this effect is also demonstrable in man.
TL;DR: It appears that in certain human hemopathies, e.g., chronic myelocytic leukemia and BL, the deletion of a specific chromosome, nos. 22 and 8, respectively, may be the key karyotypic event associated with the disease, rather than the site of translocation of the deleted segments.
TL;DR: These cases confirm that the distal end of chromosome 14q may function as a “receptor site,” according to the hypothesis of Kaiser‐McCaw et al.12 and tend to indicate that chromosome #14 may not be unique in showing so‐called “donor” and ‘receptor sites,’ and that other chromosomes, in casu chromosome #11, may behave similarly.
Abstract: A new characteristic chromosome anomaly t(11;14)(q14;q32?) in lymphoproliferative disorders (LPD) is described in 4 cases. The extra material was found on a "14 chromosome (14q+) and belonged to the long arm of one "11 chromosome in 3 cases and to the long arm of a "14 in the other case. These cases confirm that the distal end of chromosome 14q may function as a "receptor site," according to the hypothesis of Kaiser-McCaw et al. and also tend to indicate that chromosome "14 may not be unique in showing so-called "donor" and "receptor sites," and that other chromosomes, in casu chromosome "11, may behave similarly.
TL;DR: It is proposed that the hepatic receptors responsible for the glycogenolytic activity of vasopressin share characteristics with and appear therefore related to those responsible for pressor activity in vivo.
TL;DR: Three children with neurological, dysmorphic and cholestatic symptoms of variable degree and with elevated amounts of coprostanic acids and a C29 dicarboxylic bile acid in their serum are described.
Abstract: Three children with neurological, dysmorphic and cholestatic symptoms of variable degree and with elevated amounts of coprostanic acids and a C29 dicarboxylic bile acid in their serum are described. One of the patients had all the symptoms of the Zellweger syndrome.
Trihydroxycoprostanic acid (3α,7α,12α-trihydroxy-5β-cholestan-26-oic acid) was a major component of the bile acids in bile (21.3%–37.0%), serum (17.3%–21.5%), urine (14.4%–29.5%) and feces (15.0%–75.3%). Considerable amounts of dihydroxycoprostanic acid (3α,7α-dihydroxy-5β-cholestan-26-oic acid) were found in bile (6.0%–8.6%), serum (8.2%–26.6%), urine (3.9%) and feces (7.5%–15.7%). Small amounts of 3α-hydroxy-5β-cholestan-26-oic acid (in serum), 3β-hydroxy-5-cholesten-26-oic acid (in serum and bile) and varanic acid (in bile) were identified. Minor quantities of other C27 bile acids and bile alcohols were only tentatively characterized. The common C24 bile acids, cholic acid and chenodeoxycholic acid, were strongly decreased in duodenal fluid, but elevated amounts were found in serum.
Serum of these patients also contained important amounts of a C29 bile acid (27.6%–41.3%). The mass spectrum of this bile acid suggested that it was a 3α,7α,12α-trihydroxy-5β-C29 dicarboxylic bile acid. The compound contains a normal trihydroxy bile acid nucleus, the two additional carbon atoms and the two carboxyl groups being located in the side chain. Although the C29 dicarboxylic bile acid was a predominating component of the bile acids in serum, only small amounts were detected in bile or urine.
TL;DR: The t(15;17)(q26;q22) structural anomaly is highly characteristic of APL, is found in APL of children and adults, but it is apparently not associated with a clinically different form ofAPL.
Abstract: Sixteen patients, 15 adults and one child, with APL have been studied cytogenetically; 14 of these had an abnormal karyotype (87%). Eleven of these consistently showed a t(15;17)(q26;q22) structural anomaly, one patient showed a 47,+8 karyotype, one a rearrangement of chromosomes #15 and #17, apparently different from that in the other patients, and one a #17 deletion without a demonstrable translocation. As an additional chromosome change trisomy #8 was found in 5 cases and monosomy #7 in two. The t(15;17)(q26;q22) structural anomaly is highly characteristic of APL, is found in APL of children and adults, but it is apparently not associated with a clinically different form of APL. Cancer 43:558–562, 1979.
TL;DR: Experimental evidence of cation exchange between anionic micelles is presented in this article, revealed by a kinetic study of fluorescence quenching of solubilized aromatic molecules.
TL;DR: The (Na+ + K+)-stimulated ATPase activity decreases with increasing pressure and a plot of the logarithm of the activity versus pressure shows a change in slope at a defined breakpoint pressure (Pb), which is in very good agreement with the pressure shift for melting transitions in phospholipids and aliphatic chains.
TL;DR: Human fibroblast interferon (F-interferon) purified by adsorption on controlled-pore glass was given intramuscularly to patients at daily dosages of up to 20 × 106 units and evoked febrile reactions, delayed skin reactivity, and transitory lymphopenia in humans.
Abstract: Human fibroblast interferon (F-interferon) purified by adsorption on controlled-pore glass was given intramuscularly to patients at daily dosages of up to 20 × 10 6 units. Serum levels of antiviral activity were low or undetectable. In contrast, reasonably high serum titers were found in patients receiving interferon prepared from leukocytes (L-interferon). Similarly, in rabbits lower serum titers were seen with F-interferon than with L-interferon. These results are at variance with those obtained earlier (V. G. Edy, A. Billiau, and P. De Somer, J. Infect. Dis. 133: A18–A21, 1976). Possible explanations for this discrepancy are discussed. The F-interferon evoked febrile reactions, delayed skin reactivity, and transitory lymphopenia in humans. Some patients developed an allergic state of the reaginic type as evidenced by a weal and flare reaction after intradermal challenge. However, these patients did not show allergic symptoms after intramuscular injections. None of the side effects was severe enough to prohibit continuation of the treatment; most of them seemed to be due to contaminants not removed by the purification method. The possibility is considered that some of the side effects, e.g., delayed skin reactivity, are sufficiently specific to justify identification of the active principals. Images
TL;DR: In this paper, an aperture model is developed for calculating the radiation field of microstrip antennas, and antenna characteristics, like patterns and radiation resistance, are computed and compared with experimental results.
Abstract: Starting from the equivalence principle, an aperture model is developed for calculating the radiation field of microstrip antennas. In this communication the model is applied to the rectangular microstrip resonator antenna. Antenna characteristics, like patterns and radiation resistance, are computed and compared with experimental results. The model and the calculations include the higher order modes as well as the fundamental mode of the resonator antenna.
TL;DR: The class of completely positive (CP) quasi-free maps on the CCR-algebra is studied in this article, where the authors characterize the pure maps, study invariant states under semigroups, construct a particular dilation and consider the problem of implementation.
TL;DR: It is shown that the definition without limiting procedure by a formal series expansion has the same ambiguities as the definition through discretization, these last ones being related to ordering problems.
Abstract: We study functional integrals in phase space and show that the definition without limiting procedure by a formal series expansion has the same ambiguities as the definition through discretization, these last ones being related to ordering problems. We exhibit the way to obtain the prescription that makes the series expansion unambiguous and study the mechanism that makes the expansion independent of the chosen discretization.
TL;DR: In this article, the authors proposed a method for cooling the capillary during the injection, down to the injection point in the oven, to discriminate the less volatile parts of the sample which remain in the needle.
Abstract: On-column injection into a hot gas chromatograph oven involves the danger that the bottom part of the needle is warmed up above the boiling point of the solvent in the sample. Consequently parts of the sample are evaporated out of the needle instead of being introduced as a liquid into the capillary column. This causes losses and hence discrimination of the less volatile parts of the sample which remain in the needle.
A technical solution is proposed using a system for cooling the capillary during the injection, down to the injection point in the oven.
TL;DR: In this article, the prescription dependence in Langevin-type equations is studied in the context of perturbation theory and it is proved that the prescription is responsible for an additional term which has given rise to difficulties of interpretation in the Onsager-Machlup path probability density.
Abstract: We study a method proposed recently that gives a unified view of the properties of stochastic fields determined by Langevin-type equations. The functional integrals involved are shown to need an additional prescription to be defined, this prescription being related to the relative order of noncommuting operators in the corresponding operator formalism which we characterize in detail. It is proved that the prescription is responsible for an additional term which has given rise to difficulties of interpretation in the Onsager-Machlup path probability density. We prove that all results are independent of this term. In particular in perturbation theory the cancellation mechanism of the prescription dependence is studied in detail.
TL;DR: In this paper, the environmental and the soil mechanical conditions for the massive planar slides which ravaged the area of Caraguatatuba, Serra do Mar, in 1967 were discussed.
Abstract: This paper discusses the environmental and the soil mechanical conditions for the massive planar slides which ravaged the area of Caraguatatuba, Serra do Mar, in 1967. Special attention is given to the hydrology of slopes on weathered gneiss during days of heavy rainfall. It is proposed that, under these circumstances, the forest vegetation indirectly triggers landslides. Both the plasticity index I p and the sci-fraction (silt + clay + iron oxides) seem to be negatively correlated to the shear strengths of the regoliths. These indices, therefore, may have a value in prediction.
TL;DR: Two brothers developed a neurological condition characterized by homochrony and homotypy: the first symptoms in both were generalized epileptic seizures, occurring at about the same age, followed by a cerebellar syndrome with myoclonic jerks and some extrapyramidal symptoms.
Abstract: Two brothers developed a neurological condition characterized by homochrony and homotypy: the first symptoms in both were generalized epileptic seizures, occurring at about the same age (30 years in the elder, 32 years in the younger), followed by a cerebellar syndrome with myoclonic jerks and some extrapyramidal symptoms. The elder of the two boys died at the age of 33 years. Histology showed extensive storage of ceroid-lipofuscin in the central nervous system (curvilinear bodies), in hepatocytes, in heart muscle and in the retina. In the younger boy, still living, a muscle biopsy (peroneal muscle) revealed accumulation of membrane-bound osmiophilic inclusions with curvilinear profiles. Retinal storage in Kufs' disease has never been documented. Muscle biopsy as a diagnostic tool for Kufs' disease has not been reported.
TL;DR: It is described here that this phosphorylase phosphatase activity results from the interaction of at least two different thermolabile fractions which can be separated by DEAEeel&lose ~~omatography.