The Lee-Carter method of mortality forecasting assumes an invariant age component and most applications have adopted a linear time component. The use of the method with Australian data is compromised by significant departures from linearity in the time component and changes over time in the age component. We modify the method to adjust the time component to reproduce the age distribution of deaths, rather than total deaths, and to determine the optimal fitting period in order to address non-linearity in the time component. In the Australian case the modification has the added advantage that the assumption of invariance is better met. For Australian data, the modifications result in higher forecast life expectancy than the original Lee-Carter method and official projections, and a 50 per cent reduction in forecast error. The model is also expanded to take account of age-time interactions by incorporating additional terms, but these are not readily incorporated into forecasts.
Background: Anthozoan cnidarians are amongst the simplest animals at the tissue level of organization, but are surprisingly complex and vertebrate-like in terms of gene repertoire. As major components of tropical reef ecosystems, the stony corals are anthozoans of particular ecological significance. To better understand the molecular bases of both cnidarian development in general and coral-specific processes such as skeletogenesis and symbiont acquisition, microarray analysis was carried out through the period of early development -when skeletogenesis is initiated, and symbionts are first acquired.
Electrical impedance measurements were used to characterize changes in intracellular and extracellular resistance as well as changes in the condition of membranes during ripening of nectarines (Prunus persica [L.] Batsch cv Fantasia). These measurements were related to changes in fruit texture assessed by flesh firmness and apparent juice content. An electrical model indicated that, during ripening (d 1-5) of freshly harvested fruit, the resistance of the cell wall and vacuole declined by 60 and 26%, respectively, and the capacitance of the membranes decreased by 9%. Accurate modeling of the impedance data required an additional resistance component. This resistance, which declined by 63% during ripening, was thought to be associated with either the cytoplasmic or membrane resistance. Changes in tissue resistance measured using low frequencies of alternating current were closely related to flesh firmness. After storage at O' C for 8 weeks, the nectarines developed a woolly (dry) texture during ripening at 2O' C. The main difference between these chilling-injured nectarines and fruit ripened immediately after harvest was the resistance of the cell wall, which was higher in woolly tissue (4435 D after 5 d at 20'C) than in nonwoolly tissue (2911 D after 5 d at 20°C). The results are discussed in relation to physiological changes that occur during the ripening and development of chilling injury in nectarine fruit.
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