We study a bootstrap method which is based on the method of sieves. A linear process is approximated by a sequence of autoregressive processes of order p = pn, where pn ! 1 ; p n = on as the sample size n ! 1. F or given data, we t h e n estimate such a n A R pn model and generate a bootstrap sample by resampling from the residuals. This sieve bootstrap enjoys a nice nonparametric property. We ...

Because sieve elements are generally regarded as the specialized conducting cells in the phloem tissue, their structure in relation to function has been the subject of many studies and discussions. ' Both the protoplast and the walls of sieve elements have distinctive characteristics, some of which are difficult to relate to the rapid flow of materials-at the rate of up to 100 cm. per hour-reco...

It has been shown by various investigators that the substances in the sieve tubes are qualitatively the same throughout the plant. This, together with a number of physiological observations, seems to suggest that substances move through the sieve tubes without their being metabolized (2, 8, 23). There is good evidence, however, that the movement over the short distance from the leaf parenchyma ...

Petiolar application of potassium cyanide inhibited (14)C-assimilate translocation without affecting source leaf photosynthesis or phloem loading of sucrose in Phaseolus vulgaris. The inhibition of transport was correlated with disruption of the structural integrity of the sieve tubes (sieve pore blockage) rather than impairment of a metabolic process in the translocation path driving transloca...