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Showing papers by "Université catholique de Louvain published in 1988"


Book
01 Jan 1988
TL;DR: This chapter discusses the Scope of Integer and Combinatorial Optimization, as well as applications of Special-Purpose Algorithms and Matching.
Abstract: FOUNDATIONS. The Scope of Integer and Combinatorial Optimization. Linear Programming. Graphs and Networks. Polyhedral Theory. Computational Complexity. Polynomial-Time Algorithms for Linear Programming. Integer Lattices. GENERAL INTEGER PROGRAMMING. The Theory of Valid Inequalities. Strong Valid Inequalities and Facets for Structured Integer Programs. Duality and Relaxation. General Algorithms. Special-Purpose Algorithms. Applications of Special- Purpose Algorithms. COMBINATORIAL OPTIMIZATION. Integral Polyhedra. Matching. Matroid and Submodular Function Optimization. References. Indexes.

6,287 citations



Journal ArticleDOI
TL;DR: There is a significant correlation between serum IL-6 activity and serum levels of C-reactive protein, alpha 1-acid glycoprotein,alpha 1-antitrypsin, fibrinogen, and haptoglobin, which indicates that IL- 6 is related to disease activity in patients with RA.
Abstract: Interleukin-6 (IL-6), also called 26-kd protein, hybridoma plasmacytoma growth factor, beta 2-interferon, or B cell stimulatory factor 2, is a recently described human cytokine with multiple growth and differentiation activities. Using a very sensitive bioassay based on the growth factor activity of this protein for B cell hybridomas, we found that IL-6 activity was significantly elevated in synovial fluid from patients with rheumatoid arthritis (RA) or other inflammatory arthritides, as compared with that in a group of patients with osteoarthritis. Moreover, IL-6 was detected in about one-third of the serum samples from patients with RA. In the latter group, we found a significant correlation between serum IL-6 activity and serum levels of C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antitrypsin, fibrinogen, and haptoglobin, which indicates that IL-6 is related to disease activity in patients with RA.

885 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used a latent variables model to model the movements in profits of firms over time. But their model is based on the assumption that entry and imitation do not actually have to occur to have an effect on profits.
Abstract: This paper is concerned with modeling the movements in profits of firms over time At the heart of the emp irical model is a latent variables problem which arises from the fact that entry and imitation do not actually have to occur to have an ef fect on profits A solution to this problem is explored, and then emp irical results are presented comparing a sample of firms from the Uni ted Kingdom, France, and West Germany Copyright 1988 by Royal Economic Society

340 citations


Journal Article
TL;DR: The levels of 26K are considerably increased during the early stages of acute infections of the central nervous system, and this elevation in 26K titres was not observed in either chronic infections or in non-infectious diseases.
Abstract: We reported recently that a human protein, previously described as IL-1 inducible 26K factor (26K) or interferon-beta 2, was a potent growth factor for B cell hybridomas in vitro. Subsequently, it appeared that this protein was also identical with the lymphokine B cell stimulatory factor 2. Here we report that the levels of 26K are considerably increased during the early stages of acute infections of the central nervous system. This elevation in 26K titres was not observed in either chronic infections or in non-infectious diseases.

232 citations


Journal ArticleDOI
TL;DR: In this article, a general model of turbulent dissipation in one-dimensional oceanic mixed layer models is reviewed, focusing on the long-term response of these models, and a general parameterized form is proposed that provides a useful guideline to devise new parameterizations and to compare existing ones.
Abstract: The parameterization of the turbulence used in one-dimensional oceanic mixed layer models is briefly reviewed, focusing on the long-term response of these models. Particular attention is directed towards the parameterization of turbulent dissipation. A general parameterized form is proposed that provides a useful guideline to devise new parameterizations and to compare existing ones. Different models of the classical Niiler–Kraus type are first tested by simulating four years (1969–72) of the upper ocean evolution at Ocean Station Papa. In the results, distinction is made between the errors inherent in the model and those due to changes in the upper ocean heat content not explained by the surface heat fluxes. It appears that, after a needed empirical calibration, all models systematically overestimate the sea surface temperature (SST) in summer and underestimate it during fall. In absolute value, the maximum error on the monthly-mean predicted SST reaches about 1 K. In an attempt to reduce this e...

206 citations


Journal ArticleDOI
TL;DR: The regulatory mechanism controlling Sm-C/IGF-I production and growth might be different from those that regulate GH receptor concentrations, but continuous exposure to GH being required for up-regulation of liver GH receptors is suggested.
Abstract: To determine if the pattern of GH delivery is important for the regulation of serum somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) and liver somatogenic receptors, we have measured serum Sm-C/IGF-I concentrations and free (H2O-treated homogenates) and total (MgCl2-treated homogenates) liver GH-binding sites in hypophysectomized rats treated for 7 days with rat GH (rGH), given either continuously by osmotic minipumps (50 and 250 micrograms/day) or intermittently (four sc injections of 12.5 micrograms/day). At a daily dose of 50 micrograms, intermittent rGH produced greater weight gain [+29.7 +/- 0.8 g (mean +/- SE)] than continuous GH infusion (23.3 +/- 2.0 g; P less than 0.01). Likewise, the serum Sm-C/IGF-I concentration rose more with intermittent (0.33 +/- 0.1 U/ml) than with continuous delivery (0.17 +/- 0.01 U/ml; P less than 0.01). The serum Sm-C/IGF-I level achieved with repeated GH injections was even greater than that after continuous delivery of a 5-fold higher GH dose (250 micrograms/day; 0.27 +/- 0.02 U/ml; P less than 0.05). Continuous infusions of 50 and 250 micrograms rGH/day increased the number of liver total GH receptors by 2.5-fold over that of controls. In contrast, frequent GH injections did not affect GH binding, and the serum Sm-C/IGF-I concentration did not correlate with liver GH-binding sites in the GH-injected rats (r = 0.189; P = NS). Induction of hepatic PRL receptors was 10-fold higher when GH was given continuously than when it was given intermittently. The close correlation observed between GH- and PRL-binding sites in all GH-treated rats (r = 0.955; P less than 0.001) suggests that their regulation may be linked. These data suggest that the regulatory mechanism controlling Sm-C/IGF-I production and growth might be different from those that regulate GH receptor concentrations, with GH pulses being crucial for the maximal stimulation of Sm-C/IGF and growth, but continuous exposure to GH being required for up-regulation of liver GH receptors.

190 citations


Journal ArticleDOI
TL;DR: The results show that [3H]paroxetine is a ligand of choice to label the 5-HT uptake molecular complex in human brain.

177 citations


Journal ArticleDOI
TL;DR: The slender bloodstream form of Trypanosoma brucei shows receptor-mediated endocytosis of low density lipoprotein (LDL) particles of its hosts, and the LDL receptor of this species is purified nearly to homogeneity and monospecific polyclonal antibodies against it are obtained.
Abstract: The slender bloodstream form of Trypanosoma brucei shows receptor-mediated endocytosis of low density lipoprotein (LDL) particles of its hosts. We have purified the LDL receptor of this species nearly to homogeneity (about 1000-fold purification) and obtained monospecific polyclonal antibodies against it. As analyzed by NaDodSO4/polyacrylamide gel electrophoresis, the purified receptor consists of a single subunit, with an apparent molecular mass of 86 kDa. Its isoelectric point is 5.9. On the average, each cell exposes 52,000 copies of low-affinity receptors (Kd of 250 nM) and 1800 copies of high-affinity receptors (Kd of 5.7 nM). According to indirect en bloc immunolabeling of fixed parasites, the receptor appears to be localized to the flagellar pocket membrane and the flagellar membrane and to be completely absent from the rest of the pericellular membrane. LDL is required for optimal growth of the trypanosome in vitro: cell growth can be inhibited either by removal of LDL from the culture medium or by antibodies against the purified LDL receptors. In both cases, growth is restored by the addition of excess LDL.

170 citations


Journal ArticleDOI
TL;DR: A study of the intracellular distribution of iron has shown that the vacuoles are involved in the storage of iron in the yeast cell, and it seems that this vacuolar iron can be further utilised by the cells for iron‐requiring processes such as mitochondriogenesis.

167 citations


Journal ArticleDOI
01 Sep 1988-Gut
TL;DR: There was a good correlation (48 of 58) between the diagnosis of the so-called varioliform gastritis and the histological evidence of lymphocytic gastritis, and the correlation was even better when nodules, erosions, and enlarged folds were considered.
Abstract: Lymphocytic gastritis is a histopathological entity characterised by the accumulation of small lymphocytes in the surface and foveolar epithelium. In order to investigate the correlation between endoscopy and histology in this condition, 192 observations selected on the basis of a presumed diagnosis of erosive or varioliform gastritis were reviewed. Ninety two instances corresponded to lymphocytic gastritis, while 100 did not show any particular microscopic feature and were labelled non-specific gastritis. There was a good correlation (48 of 58) between the diagnosis of the so-called varioliform gastritis and the histological evidence of lymphocytic gastritis. The correlation was even better when nodules, erosions, and enlarged folds were considered. Lymphocytic gastritis has a typical endoscopical appearance consisting of nodules, erosions, and large folds predominating in the gastric body. This contrasts with non-specific gastritis, which affects the antrum and produces erosions on a flat mucosa.

Journal ArticleDOI
TL;DR: Observations indicate that viral infections can actively influence the switch of Igs and selectively stimulate the production of the IgG2a subclass.
Abstract: The isotypic distribution of murine IgG was examined after infection with several viruses. The results indicate that when a hypergammaglobulinemia was induced by the infection, it was restricted to the IgG2a and, to a lesser extent, to the IgG2b subclasses. In addition, when mice were infected with some viruses concomitantly with the immunization with a soluble protein antigen, a modification in the isotypic distribution of antiprotein antibodies was observed, with a preferential production of IgG2a. These observations indicate that viral infections can actively influence the switch of Igs and selectively stimulate the production of the IgG2a subclass.

Journal ArticleDOI
TL;DR: The study of the combined effects of Asi, GSH and other thiols in vitro and the results of previous in-vivo studies in humans and rats are consistent with a pathway involving the formation of a monomethylated metabolite which is either rapidly further methylated into a dimethylated derivative or is spontaneously oxidized into monometrichylarsonic acid (MMA).

Journal ArticleDOI
TL;DR: An implicit description of the convex hull of solutions is given, and it is shown how the problem of finding a violated cutting plane can be solved as a linear program.
Abstract: We examine mixed integer programming reformulations of the uncapacitated lot-sizing problem with backlogging. First we consider the effect of using a standard reformulation technique for fixed charge network flow problems which involves the introduction of new variables, leading to a known plant location reformulation and a shortest path reformulation. Each of these reformulations is strong in the sense that its linear programming relaxation solves the lot-sizing problem. Secondly we attempt to treat the problem in the space of the original variables. We give an implicit description of the convex hull of solutions, and show how the problem of finding a violated cutting plane can be solved as a linear program. We also describe a family of strong valid inequalities which can be generated rapidly by a heuristic and which have proved effective in a cut generation algorithm. The efficiency of both the shortest path formulation and the cutting plane algorithm have been tested on a series of multi-item capacitated lot-sizing problems with backlogging. Near optimal solutions have been found to problems with 8 periods and up to 100 times.

Journal ArticleDOI
TL;DR: A combination of these two cytokines induced strong proliferations, indicating that IL 1 and IL 6 play a synergistic role in the interactions between accessory cells and T lymphocytes.
Abstract: Purified human interleukin 6 (IL 6) was found to stimulate the proliferation of human tonsillar and peripheral rosetting T cells subliminally activated with phytohemagglutinin (PHA). This response seemed independent of IL 2 but highly dependent on the presence of accessory cells. Indeed, when accessory cell-depleted tonsillar T cells were activated with PHA and exposed to IL 6, only minimal proliferations were observed. A similar result was obtained with IL 1. However, a combination of these two cytokines induced strong proliferations, indicating that IL 1 and IL 6 plays a synergistic role in the interactions between accessory cells and T lymphocytes.

Journal ArticleDOI
TL;DR: In this article, the theoretical basis of fine root turnover estimation in forest soils is discussed, in relation to appropriate experimental techniques of measurement, and the correct expression is the sum of significant positive increments of live and dead roots of various diameter categories, to which the transfer of dead roots to organic matter derived from roots, OMDR, has to be added.
Abstract: The theoretical basis of fine root turnover estimation in forest soils is discussed, in relation to appropriate experimental techniques of measurement. After sequential coring, the correct expression is the sum of significant positive increments of live and dead roots of the various diameter categories, to which the transfer of dead roots to organic matter derived from roots, OMDR, has to be added. This should not be confounded with dead root mineralization. The transfer rates should first be estimated in root dimensions and not in weight of dry matter.

Journal ArticleDOI
TL;DR: In this article, the paleoclimatic variability at frequencies ranging from 10−4 cycle per year (cpy) to 10−3 cpy was investigated using a set of three deep-sea cores from the Indian Ocean.
Abstract: The paleoclimatic variability at frequencies ranging from 10−4 cycle per year (cpy) to 10−3 cpy is investigated using a set of three deep-sea cores from the Indian Ocean Three frequency bands of high paleoclimatic variability are first defined using upper and lower limits of the significant spectral power concentrations: the bands are centered around the spectral maxima located at 103, 47, and 25 kyr The localisation of spectral lines is then refined by high-resolution spectral analysis

Journal ArticleDOI
TL;DR: Using T cell‐derived interleukin‐HP1 (HP1), purified to homogeneity, as the prototype of this family of cytokines, the effects of these molecules in conventional polyclonal B cell activation assays with anti‐immunoglobulin antibodies or dextran sulfate as co‐stimulators are examined.
Abstract: It was recently shown that T cells, macrophages and fibroblasts produce growth factors for B cell hybridomas and plasmacytomas. These factors were subsequently identified as members of a new family of cytokines on the basis of NH2-terminal amino acid sequence analyses. Using T cell-derived interleukin-HP1 (HP1), purified to homogeneity, as the prototype of this family, we examined the effects of these molecules in conventional polyclonal B cell activation assays with anti-immunoglobulin antibodies or dextran sulfate as co-stimulators. In the absence of other cytokines, the only significant effect of HP1 was to stimulate moderately the proliferation of anti-immunoglobulin-activated B cells. By contrast, in conjunction with interleukin 1, HP1 became a major growth and differentiation factor not only for B cells activated with anti-immunoglobulin antibodies but also for dextran sulfate-stimulated and even for unstimulated B cells. In fact, with respect to cell proliferation or IgM synthesis, the IL1-HP1 combination proved to be equivalent to B cell stimulatory factors like IL4 or IL5. This B cell stimulatory activity was not due to the presence of a contaminant in the HP1 preparation because it was also observed with purified plasmacytoma growth factors derived from macrophages and fibroblasts, and could be inhibited by a monoclonal anti-HP1 antibody.

Journal ArticleDOI
TL;DR: The elemental surface composition of eleven microorganisms was determined by X-ray photoelectron spectroscopy: bacteria could be distinguished from yeasts by higher nitrogen and phosphate concentrations, and a positive correlation is found between hydrophobicity and the N/P ratio, pointing at the role of proteins in determining the hydrophobia.

Journal ArticleDOI
TL;DR: The resorption of fetal bone explants proceeds along with an accumulation of procollagenase, primarily within their nonmineralized matrix, and the results suggest that collagenase is likely to participate in the degradation of the nonminerized collagen of the boneExplants.
Abstract: The participation of collagenase in bone resorption has been investigated by assaying the procollagenase extracted from fetal mouse calvaria cultured under a variety of conditions, and by evaluating its ability to degrade bone collagen. Procollagenase was found in two separate pools, one requiring demineralization for its extraction, the other not. Culturing the bones with PTH, 1,25-dihydroxyvitamin D3, prostaglandin E2, interleukin-1, tumor necrosis factor-alpha, catabolin, retinoic acid, or endotoxin (but not with heparin) induced resorption, enhanced lysosomal enzyme release, and markedly increased the procollagenase content of the second pool. The PTH-induced increase in procollagenase was dose dependent and paralleled the extent of calcium loss and lysosomal enzyme release. The increase in procollagenase was found in bone, periosteum, and sutures, where its distribution was similar to that of nonmineralized collagen. The increase in procollagenase was abolished by cycloheximide, but not by indomethacin, hydroxyurea, glucocorticoids, acetazolamide, bisphosphonates, or calcitonin. Calcitonin and bisphosphonates almost completely inhibited the PTH-induced Ca loss and lysosomal enzyme release, but only partially inhibited the PTH-induced loss of collagen. The latter was, however, completely prevented by the collagenase inhibitor, CI-1. CI-1 also partially inhibited the PTH-induced Ca loss. Moreover, collagen degradation occurred in PTH-precultured calvaria (but not in noncultured controls) when incubated in a buffer under nonviable and nondemineralizing conditions. This degradation was inhibited by collagenase inhibitors, either CI-1 or the natural tissue inhibitor of metalloproteinases. This work thus indicates that the resorption of fetal bone explants proceeds along with an accumulation of procollagenase, primarily within their nonmineralized matrix. Moreover the results suggest that collagenase is likely to participate in the degradation of the nonmineralized collagen of the bone explants. Whether it also participates in the degradation of the collagen of the mineralized matrix remains to be elucidated.

Journal ArticleDOI
TL;DR: In this paper, a simple algorithm for the numerical calculation of finite-time ruin probabilities in a general discrete-time risk process model was developed, which can be used for the calculation of approximations for the finite time ruin probabilities for the classical actuarial risk model.
Abstract: We develop a simple algorithm for the numerical calculation of finite-time ruin probabilities in a general discrete-time risk process model These probabilities can be used for the calculation of approximations for the finite-time ruin probabilities in the classical actuarial risk model

Journal ArticleDOI
TL;DR: A second transport ATPase gene from Saccharomyces cerevisiae has been identified by hybridization to a PMA1 probe and sequenced, and it is supported by the observation that in pma1 mutants with reduced plasma membrane ATPase activity, disruption of the PMA2 gene confers the ability to grow under alkaline pH conditions.

Journal ArticleDOI
TL;DR: In this paper, the authors consider a general equilibrium model of an economy with increasing returns to scale or more general types of nonconvexity in production, where the firms are instructed to set their prices according to general pricing rules which are supposed to have bounded losses.

Journal ArticleDOI
TL;DR: In this article, the Selten concept of subgame perfect Nash equilibrium is used to model the price-location equilibrium in a two-stage game, and it is shown that the equilibrium discriminatory price system is the one initially identified by Hoover.

Journal ArticleDOI
TL;DR: The addition of glucose to a suspension of yeast initiated glycogen synthesis and ethanol formation and caused a detectable rise in cyclic AMP concentration and a series of cyclic-AMP-dependent effects such as an activation of phosphofructokinase 2 and of trehalase and an increase in the concentration of fructose 2,6-bisphosphate and in the rate of glycolysis.
Abstract: The addition of glucose to a suspension of yeast initiated glycogen synthesis and ethanol formation. Other effects of the glucose addition were a transient rise in the concentration of cyclic AMP and a more prolonged increase in the concentration of hexose 6-monophosphate and of fructose 2,6-bisphosphate. The activity of glycogen synthase increased about 4-fold and that of glycogen phosphorylase decreased 3-5-fold. These changes could be reversed by the removal of glucose from the medium and induced again by a new addition of the sugar. These effects of glucose were also obtained with glucose derivatives known to form the corresponding 6-phosphoester. Similar changes in glycogen synthase and glycogen phosphorylase activity were induced by glucose in a thermosensitive mutant deficient in adenylate cyclase (cdc35) when incubated at the permissive temperature of 26 degrees C, but were much more pronounced at the nonpermissive temperature of 35 degrees C. Under the latter condition, glycogen synthase was nearly fully activated and glycogen phosphorylase fully inactivated. Such large effects of glucose were, however, not seen in another adenylate-cyclase-deficient mutant (cyr1), able to incorporate exogenous cyclic AMP. When a nitrogen source or uncouplers were added to the incubation medium after glucose, they had effects on glycogen metabolism and on the activity of glycogen synthase and glycogen phosphorylase which were directly opposite to those of glucose. By contrast, like glucose, these agents also caused, under most experimental conditions, a detectable rise in cyclic AMP concentration and a series of cyclic-AMP-dependent effects such as an activation of phosphofructokinase 2 and of trehalase and an increase in the concentration of fructose 2,6-bisphosphate and in the rate of glycolysis. Under all experimental conditions, the rate of glycolysis was proportional to the concentration of fructose 2,6-bisphosphate. Uncouplers, but not a nitrogen source, also induced an activation of glycogen phosphorylase and an inactivation of glycogen synthase when added to the cdc35 mutant incubated at the restrictive temperature of 35 degrees C without affecting cyclic AMP concentration.

Journal ArticleDOI
TL;DR: In this paper, a new mixed algorithm for calculating viscoelastic flow is proposed, where the coupling between velocity and stress components is solved by means of multiple bilinear stress sub-elements embedded in the Lagrangian element for the velocity field while streamline upwinding is used for solving the advection dominated constitutive equations.
Abstract: In a recent paper, Marchal and Crochet have proposed a new mixed algorithm for calculating viscoelastic flow. The coupling between velocity and stress components is solved by means of multiple bilinear stress sub-elements embedded in the Lagrangian element for the velocity field while streamline upwinding is used for solving the advection dominated constitutive equations. The paper reviews the motivation and the contents of the new method and explores in detail the flow of Oldroyd-B, Phan Thien-Tanner and Giesekus-Leonov fluids through a circular abrupt contraction. No limitation based on the value of the Weissenberg number has been found for the calculation of such flows. The sensitivity of the macroscopic flow features upon a variation of the material parameters is also investigated.

Journal ArticleDOI
TL;DR: In this paper, the effects of extensional viscosity and first normal stress difference in axisymmetric flows were studied and it was shown that a high Trouton's ratio leads to vortex enhancement in an abrupt 4:1 circular contraction and to drag increase for the flow round a sphere moving along the axis of a circular tube.
Abstract: By including the dependence of the viscosity function upon the third as well as the second invariant in the flow equation governing generalized Newtonian and viscoelastic fluids, it is possible to isolate the effects of extensional viscosity and first normal stress difference in axisymmetric flows. It is shown that a high Trouton's ratio leads to vortex enhancement in an abrupt 4:1 circular contraction and to drag increase for the flow round a sphere moving along the axis of a circular tube. For low values of elasticity, it is shown that the first normal stress difference has the opposite effect.

Journal ArticleDOI
TL;DR: [3H]GBR 12935 binding was decreased in the putamen and caudate nucleus of subjects with Parkinson's disease and progressive supranuclear palsy and it is very unlikely that the remaining binding sites in both diseases correspond to piperazine acceptor sites that are not involved in dopamine uptake.

Journal ArticleDOI
TL;DR: In this paper, a family of valid inequalities for the capacitated economic lotsizing problem is given, and a heuristic for the separation problem, based on these inequalities, is defined for use in a cutting plane algorithm.

Journal ArticleDOI
TL;DR: A new, standardized, ready‐to‐apply patch test, the TRUE Test™, has been evaluated on 698 consecutive patients with suspected contact dermatitis, and there were positive test reactions to all 12 allergens lusted in the patient group.
Abstract: A new, standardized, ready-to-apply patch test, the TRUE Test™, has been evaluated on 698 consecutive patients with suspected contact dermatitis. The patients were tested with 12 different allergens. Simultaneously, the same 12 allergens in pet. (Trolab®) were applied symmetrically to the opposite side of the upper back using the conventional Finn Chamber® technique. There were positive test reactions to all 12 allergens lusted in the patient group. The concordance of positive reactions between the TRUE Test™ and the Finn Chamber® test was 67%; 13% of all positive reactions were recorded only for the TRUE Test™ and 20% only for the Finn Chamber® method. The frequency of questionable and irritant reactions was of the same low order of magnitude for both tests methods; such reactions were recorded an around 2% of all test patches.