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Thermal lens oscillations, and associated hot-wire experiments, pertain to a class of instabilities produced when the free surface of a liquid is locally heated from below, generalizing to some extent the classical Bénard-Marangoni instabilities [1--8]. They provided a host of original observations, including what is seemingly the first evidence of a type-II intermittency in hydrodynamical experiments or the discovery of a new kind of propagating waves exhibiting a significant 1D-character. After two decades of study, this class of instabilities now receives a rather classical aspect [9] and deserves a review, which is presented in this paper. Beside the presentation of what is known and understood nowadays, the opportunity is taken to stress unsolved issues, therefore opening the way to future studies. This review completes and up-to-dates a previous one published one decade ago [10]. [ABSTRACT FROM AUTHOR]

BACKGROUND/AIMS: The fact that raised interleukin 1 beta (IL 1 beta) concentrations have been found in the colonic mucosa of rats with experimentally induced colitis and of patients with inflammatory bowel disease indicates that this cytokine may participate in the disturbed intestinal motility seen during inflammatory bowel disease. This study investigated whether IL 1 beta could change the contractility of (a) a longitudinal muscle-myenteric plexus preparation from rat jejunum, ileum, and colon and (b) isolated jejunal smooth muscle cells. METHODS: Isometric mechanical activity of intestinal segments was recorded using a force transducer. Moreover, smooth muscle cell length was measured by image analysis. RESULTS: Although IL 1 beta did not affect jejunal, ileal, and colonic basal contractility, it significantly reduced contractile response to acetylcholine (ACh). This significant inhibition was seen only after 90 or 150 minutes of incubation with IL 1 beta. Pretreatment with cycloheximide blocked IL 1 beta induced inhibition of ACh stimulated jejunal contraction, suggesting that a newly synthesised protein was involved in the effect. NW-nitro-L-arginine (a nitric oxide synthase inhibitor) did not prevent the inhibition induced by IL 1 beta. Blocking neural transmission with tetrodotoxin abolished the IL 1 beta effect on jejunal contractile activity, whereas IL 1 beta had no effect on isolated and dispersed smooth muscle cells. CONCLUSIONS: IL 1 beta inhibits ACh induced intestinal contraction and this inhibitory effect involves protein synthesis but is independent of nitric oxide synthesis. This effect does not involve a myogenic mechanism but is mediated through the myenteric plexus. [ABSTRACT FROM PUBLISHER]

A program for the simulation of light propagation in multiple scattering media is applied to the evaluation of visibility distances. Knowing the three-dimensional geometric and photometrical characteristics of sources and detectors and the albedo, extinction coefficient and phase function of the scattering medium, the program computes light propagation and detection. The program is applied to visibility distances of targets for a driver on a road in foggy night atmospheres. In the first of two studies, two lighting installations are compared: classic street lamps and experimental sheetlighting. In the second, the influence of the height and spacing of lamps is been simulated, together with the respective roles of two kinds of targets: the lateral limits of the road and obstacles ahead. [ABSTRACT FROM PUBLISHER]