Physical properties of vortex and applicability of different vortex identification methods

For correct identification of vortices,this paper first analyzes the properties of the rigid vortex core and its induced flow field given by the Rankine vortex model,and it is concluded that the concentrated vortex structure should consist of the vortex core and the induced flow field(the potential flow region with a weak shear layer).Then the vortex structure is analyzed by using the Oseen vortex model.Compared with the Rankine vortex,the Oseen vortex is a concentrated vortex with a deformed vortex core.The vortex structure consists of the vortex core region,the transition region and the shear layer region(or the potential flow region).The transition region reflects the properties of the resultant vorticity of the same magnitude and the resultant deformation rate of the shear layer,and the transition region also determines the boundary of the vortex core.Finally,the evolution of leading-edge vortices of the double-delta wing is numerically simulated.And with different vortex identification methods,the shape and the properties of the leading-edge vortices identified by each method are analyzed and compared.It is found that in the vorticity concentration region,the vortices obtained by using ω,λ2,Ω criteria and Q criteria are basically identical when appropriate threshold values are adopted.However,in the region where the vorticity is dispersed,due to the influence of the flow viscous effect and the adverse pressure gradient,the results obtained by different vortex identification methods can be quite different,as well as the related physical properties,which need to be further studied.

Techniques of cell type-specific transcriptome analysis and applications in researches of sexual plant reproduction

In higher plants, specific cell differentiation and fate decision are controlled by differential gene expression.Cell type-specific transcriptome analysis has become an important tool for investigating cell regulatory mechanisms. Inrecent years, many different techniques have been developed for the isolation of specific cells and the subsequenttranscriptome analysis, and considerable data are available regarding the transcriptional profiles of some specific cells.These cell type-specific transcriptome analyses hold significant promise for elucidating the gene expression linked tocellular identities and functions, and are extraordinarily important for research in functional genomics and systemsbiology aimed toward basic understanding of molecular networks and pathway interactions. Moreover, to reveal thecritical mechanisms about sexual plant reproduction, the gamete and embryo cells have long been treated as goodsubjects for cell-specific transcriptome analysis, and there has been important progress in recent decades. In this review,we summarize current technologies in cell type-specific transcriptome analysis and review the applications of thesetechnologies in research into the mechanisms of sexual reproduction in higher plants.