高等教育溢价变动:就业结构效应还是技能价格效应?

中国高等教育溢价在刘易斯转折前后从上升转为下降,从需求的角度提出,数字信息技术应用过程中对就业机会的改变和岗位工资结构的影响是高等教育溢价变动的重要原因。对此,利用2010-2018年中国家庭追踪调查(CFPS)数据,对大学生劳动力的就业结构变动、岗位技能工资结构变动及其对高等教育溢价变动的贡献率进行了研究。研究发现:大学生劳动力在就业结构变动过程中,出现了从高技能岗位向低技能岗位转移的现象,特别是2012年以后就业降级的规模超过了就业升级的规模,这是高等教育溢价趋势转变的一个原因。另外,数字信息技术应用过程中,技能工资结构收窄,大学生劳动力就业密集的认知型岗位工资增长放缓,而高中及以下劳动力就业密集的非常规操作型岗位工资增长加快,从而认知技能相对价格下降,成为高等教育溢价趋势转变的另一个原因。RIF分解表明,高等教育溢价变动的30%~35%来自就业结构调整,65%~70%来自岗位技能工资结构变动。

Effects of controlled-release urea application on the growth, yield and nitrogen recovery efficiency of cotton

Field experiments were conducted to study the effects of the controlled release urea (CRU) application on growth yield and nitrogen recovery efficiency of cotton in the main cotton zone of the Yangtze River basin in 2010. Different nitrogen levels were set in order to determine the suitable dosage of CRU on cotton. The special purpose was to provide evidence for the CRU application in cotton fields. The results show that the application of CRU promotes the growth of cotton significantly and enhances the nitrogen supply in the whole period. Compared to the treatment with total N as base fertilizer (UB), the bod, flower, little bolls and total bolls are increased significantly. There are no significant differences in the yield between the CRU treatment and the treatment of controlled release urea and urea combined application (60%CRU + 40%U), but an increase by 12.38%-22.67% compared to the UB treatment, and an increase by 4.49%-7.23% compared to the treatments of total N split application (UD). The nitrogen uptake of CRU treatment was significantly increased by 13.01%-48.32% and 30.27%-13.01% than UB treatment and UD treatment, respectively. The nutrient recovery efficiency of CRU treatment is increased by 16.42-20.59, 5.92-11.29 and 4.22-12.59 percentage points compared to the UB treatment, UD treatment and 60%CRU + 40%U treatment, respectively. In this study, there was a good linearity relationship between the cotton yield and amount of CRU in Wuxue site. The yield of cotton response to amount of CRU could be described by the model of linear plus plateau in Jingzhou site.

Cloning and Functional Characterization of Chalcone Isomerase Genes Involved in Anthocyanin Biosynthesis in Clivia miniata

Chalcone isomerase(CHI),catalyzing isomerization of chalcones,is a crucial enzyme in flavonoid biosynthesis.Three CHI genes were isolated from Clivia miniata and designated as CmCHI1,CmCHI2 and CmCHI3,respectively.Multiple sequence alignments and phylogenetic analysis showed that CmCHI1 and CmCHI2 were members of type I CHI proteins,whereas CmCHI3 belonged to type IV CHI proteins.Subcellular localization analysis found that all three CmCHIs had diffused distribution in the cytoplasm similar to green fluorescent protein(GFP).Anthocyanin biosynthesis and gene expression analysis demonstrated that CmCHIs were highly expressed in anthocyanin accumulated tissues.To further functionally characterize the role of CmCHIs,an in vitro enzymatic activity assay was carried out using the purified recombinant proteins.Results showed that CmCHI1 and CmCHI2 could completely convert the substrate naringenin chalcone(NC)into the product naringenin(NA),whereas CmCHI3 seemed nonfunctional as no increment of NA was detected.Further genetic transformation of Arabidopsis tt5-1 mutant validated that CmCHI1 and CmCHI2 rather than CmCHI3 could complement the chi deficient phenotypes.In summary,CmCHI1 and CmCHI2 are the real active CHI genes in Clivia miniata.The results not only broaden our knowledge on flavonoid biosynthesis in C.miniata but also lay a new foundation for further flavonoid modification in C.miniata.