Showing papers by "University of Lorraine published in 2001"

A combination of friedel-crafts and lawesson reactions to 5-substituted-2,2´-bithiophenes

Abstract: Fundacao para a Ci~Encia e Tecnologia. ICCTI/French Embassy - Technical and Scientific~Cooperation Programme.

Decline of Dreissena polymorpha in the River Moselle: biotic and abiotic key factors involved in dynamics of invasive species

Abstract: Macroinvertebrate communities sampled in 1994, 1995 and 1996 showed that three invasive exotic species (Dreissena polymorpha, Corophium curvispinum and Corbicula fluminalis) were well established and coexisted in the River Moselle. Results highlighted a decline of the zebra mussel population, the oldest invader considered, between 1994 and 1996. Benthic densities decreased. The recruitment of juveniles was unsuccessful and population was clearly ageing over the considered period. These results were confirmed by a decline of the veliger density (reproduction capacity) between 1994 and 1998. Biotic and abiotic factors which have probably influenced the zebra mussel population dynamics are discussed. The recent establishment of C. curvispinum in the same mesohabitat type and the massive development of Corbiculidae suggested a possible competition for habitat and/or food between these invasive species. A first abiotic factor was the hydrological regime of 1994 and 1995, which was particularly high for the 1992-1998 period. It may have removed the substratum and then favoured the settlement of an opportunistic species like C. curvispinum with a high reproductive output and a reproduction period early in the year. A second abiotic factor was the physicochemical water quality of the River Moselle. In 1993 and 1994 the high chlorophyll-a concentration probably favoured the incubation of C. curvispinum, and in 1994 the pH did not reach an optimal value for the survival of D. polymorpha veligers, Our results describe key factors for understanding the population dynamics of invasive species in regard to environmental changes and processes involved in future ecosystem invasions.

Hyperventilation and loss of hemolymph Na+ and Cl- in the freshwater amphipod Gammarus fossarum exposed to acid stress: a preliminary study.

Abstract: The effect of acidification on the acid-sensitive species Gammarus fossarum was investigated in the laboratory. The results showed that as mortality increased, mean hemolymph chloride and sodium concentrations decreased rapidly. Concomitantly, organisms hyperventilated during the first 24 h and then started to hypoventilate. These results demonstrated that exposure to acid stress in the acid-sensitive species G. fossarum led to ion-regulatory and respiratory failure as previously reported in fish and crayfish exposed to acid stress.

Comparison between integral equation method and molecular dynamics simulation for three-body forces: Application to supercritical argon

Abstract: The prediction of the structural and thermodynamic properties of supercritical argon has been carried out by two independent routes: semianalytical calculations and numerical simulations. The first one is based on the hybridized mean spherical approximation (HMSA) conjugated with an effective pair potential that incorporates multipole dispersion interactions. The second one uses a very recent numerical simulation technique, inspired by the Car–Parrinello method [van der Hoef et al., J. Chem. Phys. 111, 1520 (1999)], which contains an effective quantum-mechanical representation of the underlying electronic structure. The latter approach allows us to treat the contribution of the three-body effects as well, and to validate the use of an effective pair potential for them in the framework of the self-consistent integral equation method. For all the supercritical argon states studied, the results obtained with the semianalytical approach are in good agreement with the predictions of the numerical simulation. Here it is shown that HMSA remains competitive with molecular dynamics simulation when the triple-dipole and the dipole–dipole–quadrupole three-body terms are taken into account

Distention of venous structures in muscles as a controller of respiration.

Abstract: The search for a Coe flow-related control mechanism of ventilation (VE) that could account for PaCO2 homeostasis1– remains rather disappointing. Indeed, although activation of chemoreceptors or mechanoreceptors located in specific sites of the cardiovascular system, i.e. the right heart6,7,8, the pulmonary circulation9,10, the carotid bifurcation or the ascending aorta11 can trigger ventilatory reflexes, their role in adjusting ventilation to the rate of incoming blood flow, when metabolism varies, is far from being established3,12. It remains therefore unclear what afferent information reaching the central nervous system could adjust the level of ventilation to the rate of CO2 removed from the tissues and reaching the lungs, to maintain constant arterial PCO2. The possible role of the peripheral circulation, mainly in the muscles, as a possible controller of respiration has been more recently proposed13–16, since a large proportion of the mechanosensitive group III and IV muscle afferent fibers, which have long been shown to stimulate ventilation17–18, are located in the adventitia of the venules. Based on human19–24 and animal13,14 studies in which the peripheral circulation was either impeded or increased, it was argued that during a peripheral vasodilatation, the change in volume of the post-capillary and/or venous network could be a source of VE stimulation15. Such a mechanism places therefore the circulation in the tissues as a possible site of mediation between peripheral gas exchange and ventilatory control.

Equilibre et régulation du marché de la justice. Délais versus prix

Abstract: Equilibre et regulation du marche de la justice Delais versus prix ; ; En France, offre et demande de justice s'equilibrent grâce a des variations du temps qui s'ecoule entre la mise en delibere et le jugement Ce rationnement de la demande de justice par le temps apparait inefficace puisque le delai d'obtention d'un jugement s'allonge Cet article se propose donc d'etudier d'autres politiques de regulation des flux de contentieux et d'en mesurer les effets Les politiques de reduction du delai imparti au debat contradictoire, d'augmentation de l'offre de justice, d'accroissement du cout d'acces a la justice et de re-allocation des couts de proces entre les parties sont ainsi envisagees successivement

Two-centre partial-wave calculations for the multiply differential cross section of the simple ionization of diatomic lithium Li2 by fast electron impact

Abstract: The (e, 2e) ionization of diatomic lithium Li2 by fast electrons is studied by applying, for the slow ejected electron, an asymptotically exact partial-wave description, which takes into account the diatomic nature of the problem. The ionization is considered as a vertical transition from the lowest vibrational and rotational level of the fundamental electronic state 1 � + g of Li2 to the fundamental 2 � + g state of Li + . After verification of the procedure on the (e, 2e) ionization of diatomic hydrogen H2 for which experimental and theoretical results exist we present the particularities and favourable directions for Li2 targets.

Conception et surete de fonctionnement : deux activites indissociables

Abstract: RESUME : L’introduction massive de l’electronique dans le secteur automobile a permis, d’une part une amelioration consequente des services rendus par le vehicule, et d’autre part une reduction des couts, qui s’explique par le caractere moins onereux de l’electronique par rapport a la mecanique. Neanmoins, de nombreux systemes controles et commandes par l’electronique, tels que le freinage, doivent repondre a de severes criteres de fiabilite et requierent donc, lors de leur conception, une attention particuliere en terme de surete de fonctionnement. Cet article presente une methodologie dont l’objectif majeur est la prise en compte de la surete de fonctionnement lors de la conception de systemes de controle commande numeriques.

Flow of non-Newtonian #uids around bubbles: PIV measurements andbirefringence visualisation

Abstract: The bubble motion in non-Newtonian #uids plays a major role in many industrial processes. However, the knowledge in this domain is still very de"cient. The present study provides new insights into the #ow of non-Newtonian#uids around bubbles, by means of both a modern technique * particle image velocimetry (PIV) anda classical method * birefringence visualisation. The complete #ow "eldaroundbubbles rising in polyacrylamide (PAAm) solutions shows for the "rst time the coexistence of three distinct zones: a central downward #ow behindthe bubble (negative wake), a conical upward #ow surrounding the negative wake zone, and an upward #ow zone in front of the bubble. This #ow con"guration is totally di!erent from that in a Newtonian #uid. The birefringence visualisation reveals a butter#y-like spatial distribution of shear stresses between the conical upward #ow andthe negative wake. These stresses display a temporarily reduced local #uidviscosity which is responsible for the interactions andcoalescence between bubbles rising in such media. 2001 Elsevier Science Ltd. All rights reserved.

Localisation techniques for division in douglas algebras

Abstract: In this paper we use uniform algebra techniques and recent results on separation properties to prove several division theorems for closed subalgebras ofL 1 containing H 1 . We also study ideals having the local approximation property and we show that not every ideal in such algebras is local.

Contraintes syntaxiques et discursives des emplois de quant à et en ce qui concerne en français parlé

Abstract: L’article propose une analyse de quant a et en ce qui concerne a partir d’un corpus de francais parle. L’auteur presente tout d’abord une analyse macro-syntaxique unique pour les deux marqueurs qui ne peuvent etre assimiles a des faits de dislocation a gauche. L’etude presente ensuite une analyse comparative des fonctionnements discursifs des marqueurs a la lumiere des travaux menees sur l’ecrit. L’hypothese, qui s’appuie sur la notion de genre de texte, est qu’une des differences decoule du fait que les emplois de quant a dans des textes planifies obeissent a des regles de rhetorique qui ne touchent pas les emplois de en ce qui concerne.

Periodic method for characterization of glass by use of an analytical model

Abstract: This paper presents an analytical method based on the quadrupole formulation (transfer matrix) that allows one dimensional calculation of the coupled heat transfer that occurs by both radiation and conduction transport phenomena in glasses or ceramics at high temperatures. This model is used to investigate a well known experimental technique (periodic method) that is classically used for opaque materials in order to determine their thermal diffusivity thanks to the measurement of the phase lag evolution versus frequency. The underlying idea is to see whether such an experiment applied to semi-transparent materials (STM) is able as it is the case for the flash method – to evaluate the phononic or lattice thermal conductivity and possibly an average extinction coefficient. Some preliminary responses are given here through a stochastic analysis of the main parameters.

On the Equilibrium Position of a Square on an Elastic Wire

Abstract: The goal of this note is to study the equilibrium position of a heavy square able to move freely on an elastic wire.

A Combination of Friedel—Crafts and Lawesson Reactions to 5-Substituted 2,2′-Bithiophenes.

Abstract: Fundacao para a Ci~Encia e Tecnologia. ICCTI/French Embassy - Technical and Scientific~Cooperation Programme.