Modern experimental techniques, including LIF lifetime and FTS branching fraction measurements, have increased the reliability of atomic transition probabilities in the UV and visible. However, this combination is problematic in the increasingly important IR region, resulting in a significant gap between the capabilities to record new astronomical spectra and the data needed to sufficiently analyze them. To aid in closing this gap, we are incorporating alternative techniques to measure sets of Fe-group oscillator strengths in the near-IR.

Changes in dry weight and 14C contents of categories of shoots that did and did not survive to produce ears were examined in winter wheat grown in micro-plots in 1982–4. The weight of a group of tillers when dead was similar to their maximum dry weight when living. By anthesis dead shoots exceeded living ones in number but contributed less than 10% of total shoot dry weight.

14CO2 was supplied, near the time that number of shoots was maximal, to tillers in axils of first (T1) and third (T3) main stem leaves; T1 usually survived and T3 usually died. The percentage of 14C in the plant retained in T1 was 78–94%. That retained in T3 ranged from 9 to 81%. Little 14C moved from dying shoots into the rest of the plant in two experiments. In another, perhaps 70% of the 14C in living tillers was transferred as they died but this represented only a small proportion of total plant weight. 14C not retained in tillers to which it had been given was found in all parts of the plant, including about 7% in grain.

Oligodendrocytes, derived from stem cell precursors which arise in subventricular zones of the developing central nervous system, have as their specialist role the synthesis and maintenance of myelin. Astrocytes contribute to the cellular architecture of the central nervous system and act as a source of growth factors and cytokines; microglia are bone-marrow derived macrophages which function as primary immunocompetent cells in the central nervous system. Myelination depends on the establishment of stable relationships between each differentiated oligodendrocyte and short segments of several neighbouring axons. There is growing evidence, especially from studies of glial cell implantation, that oligodendrocyte precursors persist in the adult nervous system and provide a limited capacity for the restoration of structure and function in myelinated pathways damaged by injury or disease.