Climate in the balance

This essay explores how our climate system works, how humans are changing the climate system, and how we might face the challenges of reducing our negative impact on the climate system in the future

Dermophis oaxacae

Number of Pages: 2Integrative BiologyGeological Science

Student performance standards and Queensland teacher education

This paper considers the implementation of Student Performance Standards (SPS) in Queensland, Australia, and their implications for teacher education. Student testing procedures in various Australian states and territories are described. A theoretical framework, grounded in Australian educational history, is elaborated for understanding the political ramifications of SPS. S. J. Ball's explication of market, management and, particularly, curriculum controls over public education is applied to show how explicit emphasis on student performance is linked to wider forces promoting an instrumentalist and managerialist view of schooling. The emergence of statewide testing is seen as: a quality control measure designed to ensure that schools are producing human resources tailored to the needs of a post-fordist economy; an attempt to shape the quality, character, and content of classroom practice; and a potential step toward monitoring the performance of teachers and schools, making comparisons among them, and linking these comparisons to performance-related pay awards. The paper concludes that SPS constitutes a not entirely desirable response to a series of complex educational and political changes within and outside Australia. SPS represents in microcosm what is a broader challenge to the celebration of diversity and the recognition of heterogeneity that ought to underpin any teacher education program. (Contains 16 references.

A comparison of bearing life in new and refurbished railway axle boxes

A simple linear dynamical model shows that at normal running speeds of freight wagons, forced oscillations due to periodic track compliance are transferred to the overlying unsprung mass and significantly amplified. Due to these oscillations, a small gap opens and closes between the collar of a journal bearing and the axle box many times every second. The forces between these components reach peaks of over 10 tonnes. This is an environment in which wear of the soft spherical graphite iron of the axle box will eventually take place. Due to repeated unloadings of the weight on the bearing during oscillations, the bearing collar may slowly slip against the axle box wall. Although our calculations show that abrasive wear due to this slippage is negligible, the calculation raises general principles that apply to other possible wear mechanisms. If lifetime is proportional to hardness, we can estimate relative lifetimes of refurbished and new boxes. Although the resleeve material is softer than the original, the cost to lifetime ratio would favour refurbishment under this assumption. Important unanswered questions are identified and a specific integrated program of field, laboratory, and theoretical study is suggested