Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

Steady state turnover time of carbon in the Australian terrestrial biosphere

Abstract: The turnover time of terrestrial carbon was estimated using a multiobjective parameterization method that combined data sets of plant production, biomass, litter and soil-C observations in the calibration of a C-cycle model for the Australian continent (VAST1.1; Vegetation and Soil carbon Transfer). The method employed a genetic algorithm to minimize model-data deviations and maximize consistency between estimated model parameters and all available data. Based on the parameterization, the turnover time of biosphere C for Australia was estimated to be 78 years which is longer than global C-turnover estimates (of 26–60 years) due entirely to slower turnover of C in the upper 20 cm of soil. Turnover times of litter and deeper soil-C were similar to global values. By splitting total C in the upper 20 cm between labile and nonlabile fractions (based on published data) the turnover time of the labile pool was at least 44 years which is still longer than global estimates (9–25 years). Longer C-turnover in Australian surface soils was attributed to (1) limited soil moisture slowing decomposition more than net primary production, (2) frequent fires leading to a large fraction of nonlabile charcoal C in soil, and (3) strong adsorbing capacity for organic-C in these highly weathered soils. It was found that >89% of the C flux to the atmosphere from decomposition of organic matter originated from fine litter, coarse woody debris and the upper 20 cm of soil in all biomes.

Microcystin‐LR and liver tumor promotion: effects on cytokinesis, ploidy, and apoptosis in cultured hepatocytes

Abstract: There is mounting evidence that the cyanobacterial toxins, the microcystins, can act as tumor promoters. However, due to their requirement for active uptake by the cell, there have been few in vitro studies of the mechanism by which this might occur. Most of our understanding of this process has been deduced from experiments using the cell permeant okadaic acid, despite differences in the effects of these toxins. A cell culture system was developed in which nonmitogenically stimulated proliferating primary mouse hepatocytes could be exposed to microcystin-LR and the effects on various cell cycle parameters could be determined. It was found that cytokinesis was stimulated and the rate of apoptosis reduced by picomolar concentrations of microcystin-LR, whereas at higher (nanomolar) concentrations, cytokinesis appeared to be inhibited and cell death was induced. Cell killing was selective at these higher concentrations, favoring retention of a proliferatively active cohort of cells. The differences in effect between okadaic acid and microcystin-LR found by other researchers were confirmed, although in this system the effective concentrations of the toxins were approximately 100-fold lower than those reported previously. The mechanistic implications of these findings with regard to tumor promotion are discussed. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 61–75, 1999

Higher order soliton pulse compression in dispersion-decreasing optical fibers

Abstract: Compression of higher order optical solitons in fibers with anomalous dispersion decreasing along their length is investigated. We demonstrate high-quality compression of pulses with initial soliton order 1