Stability of a FBTCS Scheme Applied to the Propagation of Shallow-Water Inertia-Gravity Waves on Various Space Grids

in Journal of Computational Physics (1993), 108(1), 94-104

The equations governing the propagation of inertia-gravity waves in geophysical fluid flows are discretized on the A, B, C, and D grids according to the classical forward-backward on time and centered on ... [more ▼]

The equations governing the propagation of inertia-gravity waves in geophysical fluid flows are discretized on the A, B, C, and D grids according to the classical forward-backward on time and centered on space (FBTCS) numerical scheme. The von Neumann stability analysis is performed and it is shown that the stability condition of the inertia-gravity waves scheme is more restrictive, at least by a factor of , than that concerning pure gravity waves, whatever the magnitude of the Coriolis parameter. Finally, the general necessary and sufficient stability condition is derived for the A, B and C grids, while, on the D grid, the stability condition has been obtained only in particular cases. [less ▲]

Comment rendre LOTOS apte à spécifier des systèmes temps réel ?

in Dssouli, Rachida; Bochmann, Gregor (Eds.) Ingénierie des Protocoles (1993, September)

We explain and justify by examples our proposed timed extension of LOTOS. The examples cover protocol functions and service facilities that are frequently encountered in practice or are inspired by ... [more ▼]

We explain and justify by examples our proposed timed extension of LOTOS. The examples cover protocol functions and service facilities that are frequently encountered in practice or are inspired by existing ones, such as timers, watchdogs, delays, isochronism, multimedia, rate control, ... The semantics of the language is presented after, and its properties discussed more formally. We think that the systematic application of formal temporal techniques to this kind of examples is unavoidable to convince of the pertinence of the design choices. The practical effectiveness of a formalism is as important as the associated mathematical properties. [less ▲]

In vitro antagonism of two potential biopesticides Bacillus subtilis and Pseudomonas fluorescens : biochemical aspects.

in Proceedings "Biological control of fruit and foliar diseases" (1993, September)

No Increase in Plasma Histamine During Paf-Induced Airway Obstruction in Allergic Asthmatics

in CHEST (1993), 104(3), 806-10

To investigate the possible role of mast cell or basophil histamine release in mediating platelet-activating factor (PAF) airway obstruction, we studied the effect of inhaled PAF (30 micrograms, single ... [more ▼]

To investigate the possible role of mast cell or basophil histamine release in mediating platelet-activating factor (PAF) airway obstruction, we studied the effect of inhaled PAF (30 micrograms, single dose) on plasma histamine, bronchial caliber, and leukocyte and platelet counts in six patients with mild or moderate allergic asthma (mean age, 27 +/- 1.3 years; mean FEV1, 95 +/- 5 percent of predicted; mean PC20 methacholine, 1.46 +/- 0.36 mg/ml). Specific conductance (SGaw) FEV1, FEF25-75 percent, differential leukocyte and platelet counts, and plasma histamine (radioimmunoassay) were measured before and 5, 10, 15, and 20 min after PAF inhalation. Mean basal plasma histamine level was 0.28 +/- 0.04 ng/ml. Inhalation of PAF caused a fall in SGaw peaking at 5 min (43 +/- 9 percent) and a fall in FEV1 and FEF25-75 peaking at 10 min (19 +/- 10 percent and 30 +/- 13 percent, respectively). There was also a rapid and transient fall in circulating neutrophils at 5 min (from 3,096 +/- 204/mm3 to 2,551 +/- 158/mm3, p < 0.05) followed by a rebound neutrophilia. In contrast, plasma histamine level did not change significantly at any time measured. Conversely in the same asthmatics, a rapid rise in plasma histamine level (from 0.29 +/- 0.03 ng/ml at baseline to 0.53 +/- 0.06 ng/ml at 5 min; p < 0.01) was observed after an allergenic challenge (Dermatophagoides pteronyssinus) causing a fall in FEV1 peaking at 10 min (22 +/- 4 percent). Thus, inhaled PAF may induce airway obstruction and neutropenia in asthmatics without any significant change of plasma histamine level. These results indicate that it is unlikely that lung mast cells or basophils degranulate during PAF-induced bronchoconstriction. [less ▲]

Sous le swing de la croix

in Soul Bag (1993), (132), 12-16

Des Hymnes aux Negro Spirituals et aux Gospel Songs

La nature des représentations visuelles en tant que fonction de la profondeur d’encodage

Master's dissertation (1993)

Analysis of emergency voltage situations

in Proc. 11th Power System Computation Conference (1993, September)

Terpenoids production by normal and transformed cultures of Artemisia annua L.

Poster (1993, August 31)

Macromolecular engineering of polylactones and polylactides. 12. Study of the depolymerizatin reactions of poly(ε-caprolactone with functional aluminum alkoxide end groups

in Macromolecules (1993), 26(17), 4407-4412

Ring-opening polymerization of epsilon-caprolactone has been initiated with functional aluminum alkoxides in toluene at 25-degrees-C. Degradation of ''living'' polyester chains by transesterification ... [more ▼]

Ring-opening polymerization of epsilon-caprolactone has been initiated with functional aluminum alkoxides in toluene at 25-degrees-C. Degradation of ''living'' polyester chains by transesterification reactions has been studied in relation to temperature, solvent polarity, average molecular weight, and structure of the initiator, i.e., the nature of the functional group and the number of alkoxides per Al atom. Degradation products, particularly cyclic oligomers, have been isolated by supercritical fluid extraction (SFE) and characterized by GC-MS. The effect of Lewis bases on transesterification reactions has been investigated and discussed in reference to the ''coordination-insertion'' mechanism. [less ▲]

Interactions between Active-Site-Serine Beta-Lactamases and Compounds Bearing a Methoxy Side Chain on the Alpha-Face of the Beta-Lactam Ring: Kinetic and Molecular Modelling Studies

in Biochemical Journal (1993), 293((Pt 3)), 607-611

The interactions between three class A beta-lactamases and compounds bearing a methoxy side chain on the alpha-face of the beta-lactam ring (cefoxitin, moxalactam and temocillin) have been studied. When ... [more ▼]

The interactions between three class A beta-lactamases and compounds bearing a methoxy side chain on the alpha-face of the beta-lactam ring (cefoxitin, moxalactam and temocillin) have been studied. When compared with the situation prevailing with good substrates, both acylation and deacylation steps appeared to be severely impaired. Molecular modelling studies of the structures of the Henri-Michaelis complexes and of the acyl-enzymes indicate a major displacement of the crystallographically observed water molecule which connects the glutamate-166 and serine-70 side chains and underline the role of this water molecule in both reaction steps. [less ▲]