Contextual planning for NASA - A second handbook of alternative future environments for mission analysis. Volume 2 - Appendix - An outline of a national profile

Basic national attitudes and implications for planning NASA program

Contextual planning for NASA - A second workbook of alternative future environments for mission analysis, volume 1 Interim report

Contextural planning for selecting alternate NASA program

Pollen dispersal and gene flow within and into a population of the alpine monocarpic plant Campanula thyrsoides

Background and Aims Gene flow by seed and pollen largely shapes the genetic structure within and among plant populations. Seed dispersal is often strongly spatially restricted, making gene flow primarily dependent on pollen dispersal within and into populations. To understand distance-dependent pollination success, pollen dispersal and gene flow were studied within and into a population of the alpine monocarpic perennial Campanula thyrsoides. Methods A paternity analysis was performed on sampled seed families using microsatellites, genotyping 22 flowering adults and 331 germinated offspring to estimate gene flow, and pollen analogues were used to estimate pollen dispersal. The focal population was situated among 23 genetically differentiated populations on a subalpine mountain plateau (<10 km2) in central Switzerland. Key Results Paternity analysis assigned 110 offspring (33·2 %) to a specific pollen donor (i.e. ‘father') in the focal population. Mean pollination distance was 17·4 m for these offspring, and the pollen dispersal curve based on positive LOD scores of all 331 offspring was strongly decreasing with distance. The paternal contribution from 20-35 offspring (6·0-10·5 %) originated outside the population, probably from nearby populations on the plateau. Multiple potential fathers were assigned to each of 186 offspring (56·2 %). The pollination distance to ‘mother' plants was negatively affected by the mothers' degree of spatial isolation in the population. Variability in male mating success was not related to the degree of isolation of father plants. Conclusions Pollen dispersal patterns within the C. thyrsoides population are affected by spatial positioning of flowering individuals and pollen dispersal may therefore contribute to the course of evolution of populations of this species. Pollen dispersal into the population was high but apparently not strong enough to prevent the previously described substantial among-population differentiation on the plateau, which may be due to the monocarpic perenniality of this specie

Résolution en temps d'un circuit de coïncidences particule gamma

Des détecteurs à barrière de surface ont été utilisés dans un circuit de coïncidences rapides particule-gamma en vue de mesurer des vies moyennes de noyaux dans des états excités. L'influence sur la résolution en temps de différents facteurs (résistivité, tension de polarisation, etc.) a été étudiée

Fission-Residues Produced in the Spallation Reaction 238U+p at 1 A GeV

Fission fragments from 1 A GeV 238U projectiles irradiating a hydrogen target were investigated by using the fragment separator FRS for magnetic selection of reaction products including ray-tracing and DE-ToF techniques. The momentum spectra of 733 identified fragments were analysed to provide isotopic production cross sections, fission-fragment velocities and recoil momenta of the fissioning parent nuclei. Besides their general relevance, these quantities are also demanded for applications. Calculations and simulations with codes commonly used and recently developed or improved are compared to the data.Comment: 60 pages, 21 figures, 4 tables, 2 appendices (15 pages