The aim of the present study was to investigate the potential allelopathic effects of different concentrations of Zygophyllum album （donor species） aqueous extract （2.5, 5, 7.5 and 10%） on germination percentage, ...The aim of the present study was to investigate the potential allelopathic effects of different concentrations of Zygophyllum album （donor species） aqueous extract （2.5, 5, 7.5 and 10%） on germination percentage, plumule and radicle length ofBromus tectorum （weed） and Triticum aestivum （crop species） under laboratory conditions to have the greatest inhibitory allelopathic effect on the recipient species in mixed culture compared to that pure culture. The germination percentage, plumule and radicle length ofB. tectorum in mixed culture was completely inhibited at the highest concentration of aqueous extracts of the donor species level the exerted weak measures as affected by the highest concentration level of donor in pure culture. This inhibition was markedly in obvious B. tectorum that is more sensitive to tested donor. The domineering effect of aqueous extract of the donor was more prominent on weeds than crop species. The variant response to the allelopathic substance could be related to the species specific growth regulatory effect of allelochemicals and concentration dependent. There is possibility of using these allelochemicals directly or as structural leads for the discovery and development of environment friendly herbicides to control weeds.展开更多
We study preconditioning techniques used in conjunction with the conjugate gradient method for solving multi-length-scale symmetric positive definite linear systems originating from the quantum Monte Carlo simulation ...We study preconditioning techniques used in conjunction with the conjugate gradient method for solving multi-length-scale symmetric positive definite linear systems originating from the quantum Monte Carlo simulation of electron interaction of correlated materials. Existing preconditioning techniques are not designed to be adaptive to varying numerical properties of the multi-length-scale systems. In this paper, we propose a hybrid incomplete Cholesky （HIC） preconditioner and demonstrate its adaptivity to the multi-length-scale systems. In addition, we propose an extension of the compressed sparse column with row access （CSCR） sparse matrix storage format to efficiently accommodate the data access pattem to compute the HIC preconditioner. We show that for moderately correlated materials, the HIC preconditioner achieves the optimal linear scaling of the simulation. The development of a linear-scaling preconditioner for strongly correlated materials remains an open topic.展开更多
文摘The aim of the present study was to investigate the potential allelopathic effects of different concentrations of Zygophyllum album （donor species） aqueous extract （2.5, 5, 7.5 and 10%） on germination percentage, plumule and radicle length ofBromus tectorum （weed） and Triticum aestivum （crop species） under laboratory conditions to have the greatest inhibitory allelopathic effect on the recipient species in mixed culture compared to that pure culture. The germination percentage, plumule and radicle length ofB. tectorum in mixed culture was completely inhibited at the highest concentration of aqueous extracts of the donor species level the exerted weak measures as affected by the highest concentration level of donor in pure culture. This inhibition was markedly in obvious B. tectorum that is more sensitive to tested donor. The domineering effect of aqueous extract of the donor was more prominent on weeds than crop species. The variant response to the allelopathic substance could be related to the species specific growth regulatory effect of allelochemicals and concentration dependent. There is possibility of using these allelochemicals directly or as structural leads for the discovery and development of environment friendly herbicides to control weeds.
基金supported in part by the US National Science Foundation grant 0611548in part by the US Department of Energy grant DE-FC02-06ER25793
文摘We study preconditioning techniques used in conjunction with the conjugate gradient method for solving multi-length-scale symmetric positive definite linear systems originating from the quantum Monte Carlo simulation of electron interaction of correlated materials. Existing preconditioning techniques are not designed to be adaptive to varying numerical properties of the multi-length-scale systems. In this paper, we propose a hybrid incomplete Cholesky （HIC） preconditioner and demonstrate its adaptivity to the multi-length-scale systems. In addition, we propose an extension of the compressed sparse column with row access （CSCR） sparse matrix storage format to efficiently accommodate the data access pattem to compute the HIC preconditioner. We show that for moderately correlated materials, the HIC preconditioner achieves the optimal linear scaling of the simulation. The development of a linear-scaling preconditioner for strongly correlated materials remains an open topic.
