Showing papers by "Katholieke Universiteit Leuven published in 1975"
TL;DR: Special subclasses of inequalities for which all faces can be generated are demonstrated, including the “matroidal” and “graphic” inequalities, where a count on the number of such inequalities is obtained, and inequalities where all Faces can be derived from lower dimensional faces.
Abstract: Given a linear inequality in 0–1 variables we attempt to obtain the faces of the integer hull of 0–1 feasible solutions. For the given inequality we specify how faces of a variety of lower-dimensional inequalities can be raised to give full-dimensional faces. In terms of a set, called a ldquostrong coverrdquo, we obtain necessary and sufficient conditions for any inequality with 0–1 coefficients to be a face, and characterize different forms that the integer hull must take. In general the suggested procedures fail to produce the complete integer hull. Special subclasses of inequalities for which all faces can be generated are demonstrated. These include the ldquomatroidalrdquo and ldquographicrdquo inequalities, where a count on the number of such inequalities is obtained, and inequalities where all faces can be derived from lower dimensional faces.
327 citations
TL;DR: Acute atherosis of the myometrial segments of the uteroplacental arteries from pre-eclamptic pregnancies was studied by electron microscopy.
195 citations
TL;DR: In this paper, the authors derived an expression of the drain current I D versus the drain voltage V D for devices with a channel length not smaller than 20 µm, and demonstrated that the surface potential fluctuations do not affect the slope of the I D -V D curve, whereas the density N ss of surface states strongly influences the slope for small drain voltages.
Abstract: The drain current I D versus gate voltage V G of an MOST operating in weak inversion, and the influence of surface potential fluctuations on this characteristic have been studied before [1], [2]. The purpose of this paper is to derive an expression of the drain current I D versus the drain voltage V D for devices with a channel length not smaller than 20 µm. It is demonstrated that the surface potential fluctuations do not affect the slope of the I D -V D curve, whereas the density N ss of surface states strongly influences the slope for small drain voltages. This yields a simple and useful technique to determine N ss on MOS transistors.
165 citations
TL;DR: Five patients, four women and one man, age 32-8- yr, all whites, had refractory anemia with the same abnormal bone marrow karyotype, i.e., a partial deletion of the long arm of the No. 5 chromosome, which constitutes another example of the association between a specific abnormal chromosome and a distinct hematologic disorder.
138 citations
TL;DR: The occurrence of vitamin D deficiency in patients treated with anticonvulsant drugs resulting in hypocalcemia and secondary hyperparathyroidism is confirmed, and an oral vitamin D3 supplement is recommended.
Abstract: In 20 female patients treated for 2 to 37 years (mean :12) with anticonvulsant drugs, low serum levels of 25-hydroxy-vitamin D (25-OH-D; 6.4 +/- 3.2 ng/ml M +/- SD), relative hypocalcemia (9.2 +/- 0.4 mg/100 ml) and high levels of parathyroid hormone (PTH 277 +/- 165 pg/ml) were found compared to an age-matched control group (respectively 8.6 +/- 3.2 ng/ml, 9.6 +/- 0.3 mg/100 ml and 183 +/- 95 pg/ml) living in the same psychiatric clinic. A significant negative correlation was found between total duration of treatment and either serum 25-OH-D or serum calcium. After treatment with an oral vitamin D3 supplement (2000 IU/day) for 3 weeks, the serum 25-OH-D levels, although increased, remained lower than normal in the epileptic group and neither hypocalcemia nor their secondary hyperparathyroidism were corrected. These data confirm the occurrence of vitamin D deficiency in patients treated with anticonvulsant drugs resulting in hypocalcemia and secondary hyperparathyroidism.
125 citations
TL;DR: An algorithm for fitting a smoothing spline function to a set of experimental or tabulated data is presented and the obtained spline approximation can be used for differentiation and integration of the given discrete function.
114 citations
TL;DR: Plasma levels of unconjugated estrogens (estrone, estradiol and estriol) and of HCS were measured serially from the 5th to the 40th week of pregnancy in a group of 22 normal women to demonstrate different patterns of changes in the plasma levels.
Abstract: Plasma levels of unconjugated estrogens (estrone, estradiol and estriol) and of HCS were measured serially from the 5th to the 40th week of pregnancy in a group of 22 normal women. The levels of all four hormones increased regularly till the end of pregnancy. The sequential rise in plasma was estradiol and estrone followed by HCS and finally estriol at the 10th week of pregnancy. The different patterns of changes in the plasma levels were evidenced by the hormonal ratios, leading to the following observations: 1. Estrone to estradiol ratio was not constant throughout pregnancy, but showed a preferential accumulation of the reduced form by the end of pregnancy. 2. After the 8th week of pregnancy, estradiol, which was already elevated, increased less than placental HCS appearing in the circulation. 3. Estriol increased steeply after the 10th week of pregnancy. After the 12th week, this increase was steeper than those of estradiol and of HCS. 4. From the 18th to the 30th week, the levels of all 3 estrogens a...
112 citations
TL;DR: In this paper, the versatility of vinyl azides in organic reactions is demonstrated, showing that the reactive azide function is susceptible to thermolysis, photolysis, cycloadditions, and attack by nucleophiles and electrophiles.
Abstract: This review is designed to demonstrate the versatility of vinyl azides in organic reactions. The reactive azide function is susceptible to thermolysis, photolysis, cycloadditions, and attack by nucleophiles and electrophiles. The neighboring double bond accentuates the reactivity of the azide function and provides additional intramolecular pathways for reaction. Last but not least, the presence of an appreciable electron density at the β-vinyl carbon makes this class of compounds comparable with enamines in their reactions with electrophiles and 1,3-dipoles.
95 citations
89 citations
TL;DR: The glycogenolytic effect of vasopressin is due to the activation of glycogen phosphorylase, the rate limiting enzyme in glycogen degradation, which is apparently not mediated by cyclic AMP.
79 citations
TL;DR: In this article, the spectral analysis of pseudodifferential operators in the framework of perturbation theory is studied and a closed extension (the closure, or the Friedrichs extension) of the perturbed operator is constructed.
TL;DR: Investigation of the conditions, necessary to achieve this high fusion frequency, showed that supplementing the PEG solution with Ca++ and adjustment to high pH gave the best results.
Abstract: Solutions containing polyethylene glycol MW 6000 (PEG) induced fusion of protoplasts of Penicillium chrysogenum. Balanced heterokaryons were formed by fusion of nutritionally complementing protoplasts. Heterokaryotic fusion products were obtained up to a frequency of 4% of the number of protoplasts, surviving the fusion treatment. Investigation of the conditions, necessary to achieve this high fusion frequency, showed that supplementing the PEG solution with Ca++ and adjustment to high pH gave the best results. Mechanisms of fusion of fungal protoplasts by PEG, calcium and alkaline pH are discussed in view of the obtained results.
TL;DR: The study of the relation between the inwardly directed Na gradient and the cellular Ca content has revealed that this Na gradient exerts no effect during prolonged exposure to K-free solution and a very limited effect during exposure to Na-deficient solutions.
Abstract: The exchange of Ca between the extracellular fluid and the cellular compartment has been investigated in smooth muscle cells of taenia coli. It was found that during the initial phase of metabolic depletion by DNP+IAA, the net inwards flux of Ca amounts to 0.02 pmol cm−2·sec−1. This increase might be proportional to the physiological calcium leak. The study of the relation between the inwardly directed Na gradient and the cellular Ca content has revealed that this Na gradient exerts no effect during prolonged exposure to K-free solution and a very limited effect during exposure to Na-deficient solutions. The cellular45Ca release induced by metabolic inhibition is not affected by substituting Li or choline for Na. The supplementary calcium which enters the cells during exposure to a solution at low temperature is extruded on returning to a solution at 35°C, even if the Na gradient is reversed. This finding and the effects of metabolic inhibition indicate that Ca extrusion in smooth muscle cells is a process which depends on metabolism and which is not affected by the inwardly directed Na gradient.
TL;DR: It has been demonstrated that this receptor protein binds 17 beta - hydroxy-5alpha-androstan-3-one (DHT) and testosterone in both tissues and is identical with the previously described 8-10 S androgen receptor.
TL;DR: In this paper, a Ubersicht uber die vielfaltigen Anwendungsmoglichkeiten von Vinylaziden bei organisch-chemischen Reaktionen gegeben werden.
Abstract: In diesem Aufsatz soll eine Ubersicht uber die vielfaltigen Anwendungsmoglichkeiten von Vinylaziden bei organisch-chemischen Reaktionen gegeben werden. Die reaktive Azidgruppe kann der Thermolyse, Photolyse und Cycloaddition sowie dem Angriff nucleophiler und elektrophiler Verbindungen unterworfen werden. Die benachbarte Doppelbindung verstarkt die Reaktionsfahigkeit der Azidgruppe und ermoglicht intramolekulare Reaktionen. In ihren Umsetzungen mit elektrophilen und 1,3-dipolaren Verbindungen konnen die Vinylazide schlieslich wegen ihrer bemerkenswerten Elektronendichte am β-Vinylkohlenstoffatom mit Enaminen verglichen werden.
TL;DR: Bilirubin isomer determination on native bile and isolated bile pigments, and dipyrrole-exchange assays with [14C8]bilirubs indicated that the conjugates pre-exist in bile, and that no significant dipyr Role exchange occurs during isolation of the pigments.
Abstract: 1. A system for separation of bile pigments by t.l.c. and for their structure elucidation is presented. Separated bile pigments are characterized by t.l.c. of derived dipyrrolic azopigments. 2. At the tetrapyrrolic stage hydrolysis in strongly alkaline medium followed by t.l.c. demonstrates the presence of bilirubin-IIIalpha, -IXalpha and -XIIIalpha and allows assessment of their relative amounts. 3. Most structural information is derived from analysis of dipyrrolic azopigments. Such derivatives, obtained by treatment of separated bile pigments with diazotized ethyl anthranilate, were separated and purified by t.l.c. Micro methods showed (a) the nature of the dipyrrolic aglycone, (b) the nature of the bonds connecting aglycone to a conjugating group, (c) the ratio of vinyl/isovinyl isomers present in the aglycone and, (d) the nature of the conjugating groups (by suitable derivative formation and t.l.c. with reference to known compounds). 4. In bile of normal dogs at least 20 tetrapyrrolic, diazo-positive bile pigments could be recognized. Except for two pigments the tetrapyrrolic nucleus corresponded predominantly to bilirubin-IXalpha. All conjugated pigments had their conjugating groups connected in ester linkage to the tetrapyrrolic aglycone, Apart from bilirubin-IXalpha, monoconjugates and homogeneous and mixed diconjugates of bilirubin were demonstrated; conjugating groups of major importance were xylose, glucose and glucuronic acid. 5. Bilirubin isomer determination on native bile and isolated bile pigments, and dipyrrole-exchange assays with [14C8]bilirubin indicated (a) that the conjugates pre-exist in bile, and (b) that no significant dipyrrole exchange occurs during isolation of the pigments.
TL;DR: The characteristics of the extracellular and cellular calcium exchange in taenia coli have been studied by efflux experiments under different experimental conditions and it is observed that K depolarization can only cause a Ca release if external Ca can enter the cells.
Abstract: The characteristics of the extracellular and cellular calcium exchange in taenia coli have been studied by efflux experiments under different experimental conditions. The exchange of extracellularly bound calcium is accelerated by the presence of calcium in the external solution. If a Ca-free solution is used as washing solution, the slowly exchanging extracellular calcium also contributes appreciably to the later phase of the Ca efflux and obscures the changes of the cellular calcium exchange. There is no evidence for a Ca−Ca exchange diffusion.
TL;DR: The distribution in the environment of Naegleria fowleri, the causal agent of primary amoebic meningoencephalitis has been investigated and strains isolated were not virulent for mice, although they showed all the characteristics of the pathogenic strains.
Abstract: The distribution in the environment of Naegleria fowleri, the causal agent of primary amoebic meningoencephalitis has been investigated in this study. N. fowleri was isolated only from a thermally polluted canal. These amoebaflagellates were not isolated from another thermally polluted canal in the neighbourhood indicating that, apart from high temperature, other factors are involved in the selective proliferation of N. fowleri. This species was absent in all other samples originating from two canals, a stream, two lakes, several reservoirs and slow sandfilters of a water supply service and also a water distribution network. Many other amoebae able to grow at 42 degrees C. were found in different places. Most of the N. fowleri strains isolated were not virulent for mice, although they showed all the characteristics of the pathogenic strains.
TL;DR: Data fail to confirm the long-term involution of secondary hyperparathyroidism using high-calcium dialysis and Vitamin D treatment, however, results in a much more pronounced decrease in serum PTH concentrations, but sustained therapy is necessary.
TL;DR: In this article, the differential cross sections for elastic graviton-scalar, gravitonphoton, and graviton scattering are calculated in lowest order, and it is found that they have a maximal growth with energy allowed on dimensional grounds, i.e., like E2.
TL;DR: The three isomeric cholic acid-monosulfates were synthetized and characterized and the Rf values were low on TLC in n-butanol-acetic acid-water (10:1:1, v/v).
TL;DR: In this paper, a comparison of the ion exchange behavior towards the cobalt ion, of five sodium montmorillonite clays was made, in terms of a higher selectivity of the bivalent ions for the broken bonds located at the edges of the clay crystals.
Abstract: Abstraet--A comparison is made of the ion exchange behavior, towards the cobalt ion, of five sodium montmorillonite clays. The selectivity for the bivalent ion at low cobalt loading is correlated with the average dimensions of the particles in the various clays, as characterized by several methods. The data are interpreted in terms of a higher selectivity of the bivalent ions for the broken bonds located at the edges of the clay crystals. Using a model comprising two areas of different charge densities, the experimental differences in behavior can be predicted reasonably well.
TL;DR: Colonoscopy proved superior to radiography in defining mucosal abnormalities such as ulcerations and nodular or polypoid lesions and for recognizing the segmental distribution of disease.
TL;DR: The prosthesis should be inserted in varus position with regard to the axis of the intramedullary canal, and the prostheses should be made of an alloy with appreciably higher yield stress and fatigue strength than the alloys of the investigated broken Charnley and Charnleys-Müller type prostheses.
Abstract: A survey is given of the mechanical failures of the femoral component of Charnley and Charnley-Muller type total hip prostheses. Fractographic analysis reveals that all the prostheses have broken by metal fatigue. A review of the clinical data has been combined with a metallurgical and a mechanical study in order to assess the reasons of the mechanical failures. The following conclusions have been reached. The prosthesis should be inserted in varus position with regard to the axis of the intramedullary canal, and the prosthesis should be made of an alloy with appreciably higher yield stress and fatigue strength than the alloys of the investigated broken Charnley and Charnley-Muller type prostheses.
TL;DR: In this article, a nonadaptive automatic integration scheme using Clenshaw-Curtis quadrature is presented, and extensions are made to calculate Cauchy principal values and integrals having algebraic and logarithmic end point singularities.
TL;DR: In this article, the response, relaxation and correlation functions are defined for any vector state e of a von Neumann algebra, acting on a Hilbert space ℋ, satisfying the KMS-condition.
Abstract: The response, relaxation and correlation functions are defined for any vector state e of a von Neumann algebra\(\mathfrak{M}\), acting on a Hilbert space ℋ, satisfying the KMS-condition. An operator representation of these functions is given on a particular Hilbert space
.
TL;DR: In this article, the authors describe limited and relatively slow movements of coarse material induced by runoff, a process that is called runoff creep, and demonstrate that both upslope and downslope creep can occur as was illustrated by experiments on fine sands.
Abstract: Summary The present papers describes limited and relatively slow movements of coarse material induced by runoff, a process that is called runoff creep. Micromovements of pebbles were analyzed partly in the field but mainly in the laboratory on sands, loess, loamy sands, clay, granite gruss and “grezes litees” material. It was made clear that erosion and downslope transport of coarse debris by runoff is not an evident phenomenon. Paradoxically both upslope and downslope creep can occur as was illustrated by experiments on fine sands. Runoff can be rather incompetent, even when the unit discharge amounts to several hundred/dm/h, for: 1) drag and stream-power of sheet-wash are not capable of starting movement on an adhesive clayey-loamy subsoil; 2) moderate to heavy sheet- and rill-wash (q above about 15 liter/dm/h) on loose sands, or even on gravels, provokes an upslope creep of pebbles as the result of vortex erosion at the upslope side of the debris. Downslope runoff creep was observed: 1) on sandy material and on granite gruss when gentle sheetwash was active with a maximum q-value of several tens of liter/dm/h; 2) on cohesive loams and loamy sands in so far as rills develop by a regressive erosion of small overhanging scarps. These conclusions may be of some interest for the genetic interpretation of active and fossilized stonelines.