WETTING CHARACTERISTICS OF SOME TROPICAL TREE SPECIES

Interception is a physical process, which represents a definite loss of rain-water,since most plants can absorb water only through their roots. 771e quantity lostdepends on how the canopy is wetted by the falling rain, and the amount of waterstored on the vegetation after the rain stops. Information on these points is needed inmodelling studies aimed at estimating the interception loss under varying climaticconditions. This study compared the welling characterisitics of Acacia decurren,Artocarpus heterophyllus, Eucalyptus microcorys, Hcdyotis confertiflora, Pinuscaribaca, Rhododendron zeylanicuni, Syzygiun! rotundifoliunt, and Tectono gram/is./1 rainfall simulator was used 10 generate three drop sizes. Maximum interceptionand interception loss for each species and for each drop size were measured on abranch representing a projected canopy area of one square metre. The resultsshowed that the interception loss depends on the species and not on the raindrop sizeand that it is inversely proportional to leafsize. Front the point ofview ofmaximizingthe catchment water yield, the species with larger leaves, such asjak and teak, whichgive the least interception losses, are more suitable Jhr planting in drier areas, whilespecies with smaller leaves are more suitablefor wetter areas

Photon stimulated desorption and effect of cracking of condensed molecules in a cryogenic vacuum system.

The design of the Large Hadron Collider (LHC) vacuum system requires a complete understanding of all processes which may affect the residual gas density in the cold bore of the 1.9 K cryomagnets. A wealth of data has been obtained which may be used to predict the residual gas density inside a cold vacuum system exposed to synchrotron radiation. In this study, the effect of cracking of cryosorbed molecules by synchrotron radiation photons has been included. Cracking of the molecular species CO/sub 2/ and CH/sub 4/ has been observed in recent studies and these findings have been incorporated in a more detailed dynamic gas density model for the LHC. In this paper, we describe the relevant physical processes and the parameters required for a full evaluation. It is shown that the dominant gas species in the LHC vacuum system with its beam screen are H/sub 2/ and CO. The important result of this study is that, while the surface coverage of cryosorbed CH/sub 4/ and CO/sub 2/ molecules is limited due to cracking, the coverage of H/sub 2/ and CO molecules may increase steadily during the long-term operation of the machine. (7 refs)

Models for Type Ia supernovae and related astrophysical transients

We give an overview of recent efforts to model Type Ia supernovae and related astrophysical transients resulting from thermonuclear explosions in white dwarfs. In particular we point out the challenges resulting from the multi-physics multi-scale nature of the problem and discuss possible numerical approaches to meet them in hydrodynamical explosion simulations and radiative transfer modeling. We give examples of how these methods are applied to several explosion scenarios that have been proposed to explain distinct subsets or, in some cases, the majority of the observed events. In case we comment on some of the successes and shortcoming of these scenarios and highlight important outstanding issues.Comment: 20 pages, 2 figures, review published in Space Science Reviews as part of the topical collection on supernovae, replacement corrects typos in the conclusions sectio