Showing papers by "Université libre de Bruxelles published in 1984"
TL;DR: In this paper, a continuous reactor based on the fluidized bed technique was developed in order to study the kinetics and the mechanisms of the initial stages of weathering of albite.
423 citations
TL;DR: Using the theory of nonlinear dynamic systems, this work shows how certain key properties of climate can be determined solely from time series data.
Abstract: Much of our information on climatic evolution during the past million years comes from the time series describing the isotope record of deep-sea cores. A major task of climatology is to identify, from this apparently limited amount of information, the essential features of climate viewed as a dynamic system. Using the theory of nonlinear dynamic systems we show how certain key properties of climate can be determined solely from time series data.
294 citations
TL;DR: In this paper, the natural isotopic composition of suspended particulate organic nitrogen was determined in the Southern Bight of the North Sea and in the Scheldt estuary and these data show that δ 15 N constitutes a convenient tracer of the origin of the suspended matter.
235 citations
TL;DR: Postexercise proteinuria is a common phenomenon in humans that seems to be directly related to the intensity of exercise, rather than to its duration, and the degree of hydration appears to be important to reduce these abnormalities.
Abstract: Exercise induces profound changes in the renal haemodynamics and in electrolyte and protein excretion. Effective renal plasma flow is reduced during exercise. The reduction is related to the intensity of exercise and renal blood flow may fall to 25% of the resting value when strenuous work is performed. The combination of sympathetic nervous activity and the release of catecholamine substances is involved in this process. The reduction of renal blood flow during exercise produces a concomitant effect on the glomerular filtration rate, though the latter decreases relatively less than the former during exertion. However, the degree of hydration has an important influence on the glomerular filtration rate. An antidiuretic effect is observed during intense exercise. Changes in urine flow are dependent on the plasma antidiuretic hormone levels which are increased by intense exercise.
209 citations
TL;DR: Examination of the nitrogen balance during the spring bloom shows that microheterotrophic activity could play an important role in food-web dynamics by partly satisfying the nitrogen needs of phytoplankton, which represents about twice the mineral nitrogen stock initially present in the water column.
Abstract: Parallel measurements were made of particulate and dissolved products of primary production, utilization rate of amino acids, monosaccharides, and glycollate, thymidine incorporation into DNA, and exoproteolytic activity before and during the spring bloom at different stations in the southern bight of the North Sea and in the English Channel. High correlations were found between the three methods used for estimating the activities of heterotrophic bacteria. A reasonable quantitative agreement was found between the estimate of bacterial production based on thymidine incorporation into DNA and the estimate of total carbon utilization based on the sum of the utilization rates of amino acids, monosaccharides, and glycollate. A close coupling between microheterotrophic activity and primary production was demonstrated. Examination of the nitrogen balance during the spring bloom shows that microheterotrophic activity could play an important role in food-web dynamics by partly satisfying the nitrogen needs of phytoplankton, which represents about twice the mineral nitrogen stock initially present in the water column.
186 citations
TL;DR: In this article, the bifurcations of periodic orbits in a class of autonomous three-variable, nonlinear-differential-equation systems possessing a homoclinic orbit associated with a saddle focus with eigenvalues (ρ ±iω,λ), where ¦ρ/λ¦ < 1 (Sil'nikov's condition), are studied in a two-parameter space.
Abstract: The bifurcations of periodic orbits in a class of autonomous three-variable, nonlinear-differential-equation systems possessing a homoclinic orbit associated with a saddle focus with eigenvalues (ρ ±iω,λ), where ¦ρ/λ¦ < 1 (Sil'nikov's condition), are studied in a two-parameter space. The perturbed homoclinic systems undergo a countable set of tangent bifurcations followed by period-doubling bifurcations leading to periodic orbits which may be attractors if ¦ρ/λ¦ < 1/2. The accumulation rate of the critical parameter values at the homoclinic system is exp(-2π¦ρ/ω¦). A global mechanism for the onset of homoclinicity in strongly contractive flows is analyzed. Cusp bifurcations with bistability and hysteresis phenomena exist locally near the onset of homoclinicity. A countable set of these cusp bifurcations with scaling properties related to the eigenvaluesρ±iω of the stationary state are shown to occur in infinitely contractive flows. In the two-parameter space, the periodic orbit attractor domain exhibits a spiral structure globally, around the set of homoclinic systems, in which all the different periodic orbits are continuously connected.
185 citations
TL;DR: Experiments on progressive unidirectional freezing are COI1- ducted to determine the evolution in 00 and (51 BO) of successive water samples and ice layers during the course of freezing as discussed by the authors.
Abstract: Experiments on progressive unidirectional freezing are COI1- ducted to determine rhe evol ution in 00 and (51 BO of successive water samples and ice layers ta ken during the course of freezing R es ults indicate t hal lhi s evoluti on takes pl ace, in a bD- bIBO diagram, a long a strai ght line wi th a characteri sti c slope This slope, different from that due to the precip itation effec t, gives a finger-print of the occurrence of a freezing or of a melt ing- refreez ing process in the stud ied reservoir Residual water was sampled at the beginning of the experiment, after 40%, 80%, 85%, 90% and 95% of the material had frozen When the freezing process was complete, the ice core was recovered and sectioned The samples covered the freezing ranges from 0 to 10%, 10 to 20%, 20 to 50%, 50 to 60%, 60 to 70% , 70 to 80%,
170 citations
167 citations
TL;DR: Short-term oral zinc supplementation probably improved hepatic encephalopathy by correcting the zinc deficiency that compromises conversion of ammonia to urea and the duration of this improvement requires further investigation.
159 citations
TL;DR: In this article, a systematic study of the dependence of static nuclear properties on the parameters of the effective interaction used in the Hartree-Fock (HF) and extended Thomas-Fermi (ETF) models is presented.
153 citations
TL;DR: In this paper, a stochastic formulation of the stability of nonequilibrium states is discussed, including the effect of both the macroscopic evolution and of the fluctuations, and an entropy balance equation is derived.
Abstract: A stochastic formulation of the stability of, nonequilibrium states is discussed. An entropy balance equation, including the effect of both the macroscopic evolution and of the fluctuations is derived. In the linear region of thermodynamics Prigogine's minimum entropy production, theorem is extended to include the effect of fluctuations. The latter are shown to reinforce the return of the system to its steady state distribution.
TL;DR: Comparison of the BLV and HTLV sequences within the post-envelope region revealed a very limited but possibly significant similarity.
TL;DR: In this paper, the spectrum of eleven-dimensional supergravity compactified on the seven-sphere is obtained, and the spectrum agrees with OSp(4|8) supersymmetry despite the appearance of 294 massless scalars which are not members of the N=8 massless supermultiplet.
TL;DR: In this paper, the mathematical foundations of multidimensional scaling, generalizing Guttman scaling, are discussed, in which the structure of the embedding space relies only on ordinal concepts.
TL;DR: A collection of Erwinia strains screened for temperate phages turned out to be a generalized transducing phage, phiEC2, which was found to be 62 kb long, terminally redundant, and circularly permuted.
TL;DR: In this article, it was shown that the problem of cost allocation in a cooperative game with transferable utilities is identical to the problem in a game with cooperative utilities, and four new accounting methods that originate from game theory were proposed.
Abstract: The allocation of operating costs among the lines of an insurance company is one'of the toughest problems of accounting; it is first shown that most of the methods used by the accountants fail to satisfy some natural requirements. Next it is proved that a cost allocation problem is identical to the determination of the value of a cooperative game with transferable utilities, and 4 new accounting methods that originate from game theory are proposed. One of those methods, the proportional nucleus, is recommended, due to its properties. Several practical examples are discussed throughout the paper.
TL;DR: Isolation of helodermin was the first demonstration of the existence of a secretin/VIP‐related peptide in an animal that is neither mammal nor bird.
TL;DR: A Homo-like obstetrical mechanism for Australopithecus, characterized by the rotation and the flexion of the Neonate, with fetal skull size similar to the one of the neonate chimpanzee, in the pelvic cavity is suggested.
TL;DR: It is tested the hypothesis that subjects with a good tolerance to shift work maintain the circadian period τ of their temperature rhythm equal to 24 h, while τ may differ from 24 h when subjects exhibit one or several clinical signs of intolerance.
Abstract: The present study tested the hypothesis that subjects with a good tolerance to shift work maintain the circadian period tau of their temperature rhythm equal to 24 h, while tau may differ from 24 h when subjects exhibit one or several clinical signs of intolerance. These latter are mainly: persisting sleep disturbance, persisting fatigue, changes in mood and behaviour, and digestive troubles, from gastritis to overt peptic ulcer. These symptoms were used here to classify the subjects studied. Medications, including all types of sleeping pills, are ineffective. As was the case in the present study, some subjects may tolerate shift work for 35 yr, reaching 57 yr of age without complaint, while others, after several months or many years, quite rapidly (within 6 months) develop symptoms of intolerance.
TL;DR: Enrichment cultures on either alpha- and beta-glucoside result in increasing activity of the corresponding glucosidase, both in absolute terms and with respect to the other glucOSidase.
Abstract: The α- and β-glucosidase activity in natural samples can be readily measured during short incubation times (20 min) by using the artificial substrates 4-methylumbelliferyl-α-d-glucoside and 4-methylumbelliferyl-β-d-glucoside. The apparent Km of both α- and β-glucosidase for these respective substrates is 0.01 μM. The homologous disaccharides maltose and cellobiose competitively inhibit α- and β-glucosidase, respectively. Absolute substrate specificity of the α- and β-glucosidase is observed with respect to the configuration of carbon atoms 1 and 4. Enrichment cultures on either α- and β-glucoside result in increasing activity of the corresponding glucosidase, both in absolute terms and with respect to the other glucosidase.
01 Jan 1984
TL;DR: In this article, a discussion of the processes of their utilization and mineralization can bring insights either into specific aspects of the nitrogen cycle or into general mechanisms of organic matter metabolism in the sea.
Abstract: Because organic nitrogen compounds represent both a nitrogen and an energy source for heterotrophic microorganisms in the sea, a discussion of the processes of their utilization and mineralization can bring insights either into specific aspects of the nitrogen cycle or into general mechanisms of organic matter metabolism in the sea. This paper will be mainly devoted to the latter aspect. There are indeed some technical advantages in focusing on nitrogen instead of on carbon for studying organic matter utilization in the sea, owing to the greater sensitivity of analytical methods for organic nitrogen than for organic carbon. However, parallelism or lack of parallelism between nitrogen and carbon utilization processes will be underlined.
TL;DR: The volatile irritants produced by the larvae are well suited to repel small arthropods, whereas poisons associated with aposematic coloration in the adults could be directed against small vertebrates, such as birds.
TL;DR: In this paper, the stability of the zero-intensity solution of the semiclassical laser equations when the pump parameter increases linearly in time was studied. But the authors focused on the stabilization of the trivial fixed point of the Lorenz equations.
Abstract: We study the stability of the zero-intensity solution of the semiclassical laser equations when the pump parameter increases linearly in time. Equivalently, we study the stability of the trivial fixed point of the Lorenz equations when the Rayleigh number is increased linearly in time. When the time-dependent parameter varies slowly, the stability domain is greatly increased with respect to the stability domain derived under stationary conditions. This corresponds to a dynamical stabilization of an unstable stationary solution.
TL;DR: Early somatosensory evoked potentials to median or ulnar nerve stimulation were recorded with non-cephalic reference from neck, oesophagus and scalp in normal young adults, finding a new montage of posterior-to-anterior neck can enhance this component without introducing extraneous potentials.
TL;DR: The binding of 6 aminoglycosides in current clinical use to phosphatidylinositol has been studied by gel filtration technique and by conformational analysis and is largely, but not entirely dependent upon electrostatic interactions.
TL;DR: Dyslexia (15 boys, 12 girls, 6 to 9 yr.) were not poorer than normal readers in segmenting tone sequences but much poorer in segmented speech.
Abstract: Dyslexics (15 boys, 12 girls, 6 to 9 yr.) were not poorer than normal readers (13 boys, 11 girls, 6 to 9 yr.) in segmenting tone sequences but much poorer in segmenting speech.
TL;DR: Using an explicit expression for the Laplace transform of the Brownian excursion area generating function, a numerical analysis gives moments, density, and distribution function for small argument.
Abstract: Using an explicit expression for the Laplace transform of the Brownian excursion area generating function, a numerical analysis gives moments, density, and distribution function. An asymptotic formula is given for small argument.
01 Jan 1984
TL;DR: The concentration of neurophysin I ( hNPI) and II (hNPII), the hypothalamo-pituitary carriers of vasopressin and oxytocin, in CSF of depressed and schizophrenic patients and age matched controls was studied.
Abstract: We studied the concentration of neurophysin I ( hNPI) and II (hNPII), the hypothalamo-pituitary carriers of vasopressin and oxytocin, in CSF of depressed and schizophrenic patients and age matched controls. Mean hNPI values were lower and mean hNPII values greater in schizophrenics than in controls. Lower hNPI values were observed in unipolar patients than in controls. In bipolar patients however, higher hNPI values were present. Significantly higher hNPII values were observed in bipolar patients than in controls; no difference was present between unipolars and controls. A positive correlation was observed with age in controls and bipolars for hNPII. These data emphasize the interest of studying the neurohypophysal function in affective illness and in schizophrenia.
TL;DR: In this paper, it was shown that if a locally compact group G acts simplicially on a tree in such a way that the stabilizers of the vertices are amenable, then G is K-amenable.
TL;DR: Autoradiograms of in vitro developed embryos pulsed for 2 h with [3H]uridine confirm that the central fibrillar core of the nucleoli of 6-to 8-cell embryos is never labelled, and the fibrillsar constituent of this core is not homologous to the fibillar component of theucleoli of later stage embryos, which is the site of active rDNA transcription.