Leisure Behavior Pattern Stability During the Transition from Adolescence to Young Adulthood

Leisure is an important context in which human development occurs. Changes in leisure behavior patterns may indicate changing developmental needs or reflect contextual changes that impact leisure behavior. The transition from adolescence to young adulthood provides an excellent opportunity for the study of the stability of leisure behavior as individuals' contexts are changed with the adoption of adult roles and the potential for disruption of leisure patterns exists. Previous studies investigating leisure and the transition from adolescence to young adulthood have tended to be cross-sectional and focus on specific leisure behaviors rather than identifying patterns of leisure behavior. The present study involved a longitudinal investigation of leisure behavior patterns over a three-year period during the transition from adolescence to young adulthood, and determined the nature of leisure pattern stability and instability during this period. In general, leisure pattern stability was the most common pathway into young adulthood. The patterns of leisure behavior and the nature of the changes that occurred with the transition from adolescence to young adulthood differed to some degree for males and females, although similarities in patterns and transitions were also found.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45285/1/10964_2004_Article_411255.pd

Kriech- und Ermüdungsrisswachstum der Werkstoffe X10NiCrAlTi3220 und NiCr22Co12Mo im Hochtemperaturbereich

As part of several HTGR-development programs, experiments on creep crack growth and fatigue crack growth have been performed at the companies ABB, Interatom, KFA and PSI. The materials under investigation were XlONiCrAlTi32 20 (Alloy 800) and NiCr22CoI2Mo (Inconel 617). Several production lots and semifinished materials as well as welded materials have been tested. Testing techniquesmore or less differ at the different labs. This concerns heating, crack length measurement, COD-measurement and specimen geometry. In order to eliminate the influence of individual testing techniques, material of some production lots was tested at different labs. Creep crack growth: Alloy 800 was tested between 550°C and 900°C, Inconel 617 between 800°C and 1000°C. The evaluation was done on the base of the fracture mechanics parameters K$_{I}$ and C*. Fatigue crack growth: The materials were tested between RT and 1050°C. The influence of temperature, R-ratio, frequency and hold time was investigated. Beside the experiments in air, some standard specimens were also tested in vacuum and in HTGR-helium. A few experiments have been performed with components (tubes). In order to get informations on the influence of long time heat treatment on the crack propagation, creep and fatigue tests also have been performed with serviced material