Sediment-transport (wind) experiments in zero gravity

The carousel wind tunnel (CWT) can be a significant tool for the determination of the nature and magnitude of interparticlar forces at threshold of motion. By altering particle and drum surface electrical properties and/or by applying electric potential difference across the inner and outer drums, it should be possible to separate electrostatic effects from other forces of cohesion. Besides particle trajectory and bedform analyses, suggestions for research include particle aggregation in zero and sub-gravity environments, effect of suspension-saltation ratio on soil abrasion, and the effects of shear and shear free turbulence on particle aggregation as applied to evolution of solar nebula.

Origin, development and evolutionary model of shelf desertization environment in late stage of Upper Pleistocene

Based on the study of palaeo-environmental evolution in the shelves of the Eastern China Seas, the concept of ''shelf desertization'' in the late stage of Upper Pleistocene is defined; the environmental background and evolutionary process of shelf desertization are analysed. Study on the records of subbottom profiling and the data of core samples from shelf areas revealed that during low sea-level stages, the sedimentary environment in the exposed shelf plains was dominated by aeolian depositional process under cold and dry climatic conditions, i.e. under the action of strong winter-monsoon winds. Parts of the exposed marine strata were disintegrated, and aeolian sand dunes were formed on the disintegrated marine deposits, from which the finer sediment grains were blown away by wind and deposited in the downwind areas to form the derivative loess deposits. Thus a desertization environmental system was formed in the exposed shelf plains of the Eastern China Seas.

The sedimentology of unconsolidated deltaic and aeolian sediments east of Dunnville, Ontario /

Surficial sediments east of Dunnville, Ontario representing a limited deltaic/lacustrine/aeolian system are investigated with the aim of defining and interpreting their geological history by means of exarrrrning their sedimentology and interrelationships. The Folk and \oJard grain size statistics of samples fran the area were calculated. These sample parameters were e1en plotted on maps to detennine regional patterns. The strongest pattern observed was one of distinct fining to the east, away fran the sand source. Aeolian deposits were fourrl to be better sorted than the surrcunding sediments. The grain size parameter values were also plotted on bivariate graphs in an attempt to separate the samples according to depositional environment. This exercise met with little success, as rrost of the sediments sampled in the area have similar grain size parameters. This is believed to be because the sediment sources for the different environments (delta, distal delta, aeolian dune) are intimately related, to the point that nnst dunes appear to have been sourcErl fran immediately local sediments. It is FOstulated that in such a srrall sedimentological sub-system, sediments were not involved in active transport for a length of time sufficient for the rraterial to cane to equilibritnn with its transporting medium. Thus, fe..v distinctive patterns of parameters were developed that would enable one to differentiate between various environments of neposition. The i.rnTaturity of rrany dune forms and the i.Imaturity of mineralogical composition of all deposits support the above hyt:XJthesis of limited transport time. Another hypothesis proposen is that eadh geologically or geographically distinct area or "sub-system" rray have its o,.m "signature" of grain size relationships as plotted on bivariate graphs. Thus, the emphasis, concerning graphs of this type, should not be placErl on attempting to nifferentiate between various environnents of deposition, hut raB1er on investigating the interrelationships between sanples am environments within that "sub-system". Through the course of this investigation, the existence of nelta plain distributary Channels in the thesis area is SUG0ested, and the mscovery of significantly mfferent sub-units within the TUnnville dune sediments is documented. It is inferred by reference to other authors interpretations of the glacial history of the area, that the tirre of effective aeolian acti vi ty in the Dunnville area was between 12,300 to 12,100 years R.p.

Assessing the completeness of optical resetting of quartz OSL in the natural environment

Resetting of previously accumulated optically stimulated luminescence (OSL) signals during transport of sediment is a fundamental requirement for reliable optical dating. The completeness of optical resetting of 46 modern-age quartz samples from a variety of depositional environments was examined. All equivalent dose (De) estimates were View the MathML source, with the majority of aeolian samples View the MathML source, and fluvial samples View the MathML source. The OSL signal of quartz originates from several trap types with different rates of charge loss during illumination. As such, incomplete bleaching may be identifiable as an increase in De from easy-to-bleach through to hard-to-bleach components. For all modern fluvial samples with non-zero De values, SAR De(t) analysis and component-resolved linearly modulated OSL (LM OSL) De estimates showed this to be the case, implying incomplete resetting of previously accumulated charge. LM OSL measurements were also made to investigate the extent of bleaching of the slow components in the natural environment. In aeolian sediments examined, the natural LM OSL was effectively zero (i.e. all components were fully reset). The slow components of modern fluvial samples displayed measurable residual signals up to 15 Gy.

The extracurriculum in an input-poor environment

This paper reports on the experiences of an extracurricular program in English language learning (ELL) that was implemented in an institute of technology in the hinterland of the People's Republic of China (PRC). Following the guidelines set out in an impact study of the reform of curriculum change in Hong Kong (Adamson & Morris, 2000), this study takes account of the context of the particular socio-cultural and political environment in which the research program takes place. Three distinct phases emerged in the career of the extracurricular program - the establishment of the program; successful implementation; and the decline. The study identifies three key factors that shaped these phases: teacher motivation; student motivation and its various influences; and available resources (including collegial and administrative support). The findings suggest that of the key factors impacting on the ELL extracurriculum, student motivation was the most influential.