Gamow-Teller Strength in the Region of 100^{100}Sn

New calculations are presented for Gamow-Teller beta decay of nuclei near $^{100}$Sn. Essentially all of the $^{100}$Sn Gamow-Teller decay strength is predicted to go to a single state at an excitation energy of 1.8 MeV in $^{100}$In. The first calculations are presented for the decays of neighboring odd-even and odd-odd nuclei which show, in contrast to $^{100}$Sn, surprisingly complex and broad Gamow-Teller strength distributions. The results are compared to existing experimental data and the resulting hindrance factors are discussed.Comment: 12 pages (latex) and 2 figures available on reques

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation

Background: Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime. The present study investigates the effect of body size and lifestyle on trabecular structure in Sciuromorpha. Methods: Based upon high-resolution computed tomography scans, the femoral head 3D inner microstructure of 69 sciuromorph species was analyzed. Species were assigned to one of the following lifestyle categories: arboreal, aerial, fossorial and semifossorial. A cubic volume of interest was selected in the center of each femoral head and analyzed by extraction of various parameters that characterize trabecular architecture (degree of anisotropy, bone volume fraction, connectivity density, trabecular thickness, trabecular separation, bone surface density and main trabecular orientation). Our analysis included evaluation of the allometric signals and lifestyle-related adaptation in the trabecular parameters. Results: We show that bone surface density, bone volume fraction, and connectivity density are subject to positive allometry, and degree of anisotropy, trabecular thickness, and trabecular separation to negative allometry. The parameters connectivity density, bone surface density, trabecular thickness, and trabecular separation show functional signals which are related to locomotor behavior. Aerial species are distinguished from fossorial ones by a higher trabecular thickness, lower connectivity density and lower bone surface density. Arboreal species are distinguished from semifossorial ones by a higher trabecular separation. Conclusion: This study on sciuromorph trabeculae supplements the few non-primate studies on lifestyle-related functional adaptation of trabecular bone. We show that the architecture of the femoral head trabeculae in Sciuromorpha correlates with body mass and locomotor habits. Our findings provide a new basis for experimental research focused on functional significance of bone inner microstructure

Beta-delayed particle emission from neutron-deficient isotopes in the Z approximately 50 region

Experimental studies of beta-delayed proton and alpha-particle emission from precursors in the region close to the double shell closure at N=Z=50 are described. The results range from identification of new precursors like /sup 96/Ag and /sup 103,105/Sn, to determination of branching ratios, feeding of excited levels after particle emission and the energy available for proton emission. Comparison of the results with statistical-model calculations points to a resonance in the beta-strength function in the decay of /sup 110,112/I, /sup 113/Xe, /sup 114,116/Cs and /sup 117/Ba. (39 refs)