We analyse the influence of an inhomogenous microwave field on the coherence of atom ensembles. Two methods are proposed to suppress the dephasing generated by the inhomogenous Rabi frequency. One of them is realized ...We analyse the influence of an inhomogenous microwave field on the coherence of atom ensembles. Two methods are proposed to suppress the dephasing generated by the inhomogenous Rabi frequency. One of them is realized by using a spin echo, and the other one is based on the identical spin rotation effect. The calculation results show that the contrast of a signal acquired in experiment can be improved by using the two methods. Their advantages and drawbacks are discussed. We hope they can be used to improve the contrast of experimental signals in situations where microwave fields are very inhomogenous. Finally, we discuss the case of a continuous working microwave field and show that the dipole force raised with the inhomogeneitv can be eased by slain flip.展开更多
Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific t...Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific tree species,a close relationship is expected between this and foliar fungal pathogen infestation.Testing for such a relationship in the German tree diversity experiment BIOTREE(Bechstedt),we hypothesized that pathogen richness and pathogen load decline with increasing functional diversity of tree communities.Using macro-and microscopic analyses,we assessed pathogen richness and load on 16 tree species in plots that,although differing in functional diversity,had the same tree species richness.We found no effects of functional diversity on pathogen richness or load.However,we encountered strong species identity effects in plot species composition,as susceptible tree species contributed positively to each community’s pathogen richness and load.Furthermore,testing for effects of particular leaf traits and geographical range size of host species revealed a significant effect of total leaf phenolics,which was unexpected as pathogen richness increased with increasing content in polyphenolics.Our study showed that at the community level,host species’identity was more important for foliar fungal pathogen richness and load than the functional diversity of host trees.The positive relationship between pathogen richness and phenolics in leaves,along with the finding that pathogen richness is very much conserved in tree species,point to an evolutionary arms race between hosts and fungi resulting from fungi increasing their capacity to infect tree leaves and trees boosting their defences.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB921504)the National Natural Science Foundation of China (Grant No. 10974210)
文摘We analyse the influence of an inhomogenous microwave field on the coherence of atom ensembles. Two methods are proposed to suppress the dephasing generated by the inhomogenous Rabi frequency. One of them is realized by using a spin echo, and the other one is based on the identical spin rotation effect. The calculation results show that the contrast of a signal acquired in experiment can be improved by using the two methods. Their advantages and drawbacks are discussed. We hope they can be used to improve the contrast of experimental signals in situations where microwave fields are very inhomogenous. Finally, we discuss the case of a continuous working microwave field and show that the dipole force raised with the inhomogeneitv can be eased by slain flip.
基金The research leading to these results also attracted funding from the European Union’s Seventh Framework Programme(FP7/2007-2013)under grant agreement no265171,project FunDivEUROPE as well as of the BACCARA project,which received funding from the European Commission’s Seventh Framework Programme(FP7/2007-2013),under grant agreement no226299.O.P.and H.B.also acknowledge the support of the German Centre for Integrative Biodiversity Research(iDiv)HalleJena-Leipzig,funded by the German Science Foundation(FZT 118).
文摘Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific tree species,a close relationship is expected between this and foliar fungal pathogen infestation.Testing for such a relationship in the German tree diversity experiment BIOTREE(Bechstedt),we hypothesized that pathogen richness and pathogen load decline with increasing functional diversity of tree communities.Using macro-and microscopic analyses,we assessed pathogen richness and load on 16 tree species in plots that,although differing in functional diversity,had the same tree species richness.We found no effects of functional diversity on pathogen richness or load.However,we encountered strong species identity effects in plot species composition,as susceptible tree species contributed positively to each community’s pathogen richness and load.Furthermore,testing for effects of particular leaf traits and geographical range size of host species revealed a significant effect of total leaf phenolics,which was unexpected as pathogen richness increased with increasing content in polyphenolics.Our study showed that at the community level,host species’identity was more important for foliar fungal pathogen richness and load than the functional diversity of host trees.The positive relationship between pathogen richness and phenolics in leaves,along with the finding that pathogen richness is very much conserved in tree species,point to an evolutionary arms race between hosts and fungi resulting from fungi increasing their capacity to infect tree leaves and trees boosting their defences.
