基于新课标分析两道情境相似的高考题

本文基于新课标中核心素养的要求,对2021年高考全国乙卷理综第24题与2022年高考湖南物理卷第14题进行对比分析,讨论同样是篮球与地面碰撞的情境下两道高考题有何异同.

Understory plant diversity and phenolic allelochemicals across a range of Eucalyptus grandis plantation ages

Allelopathy is an important mechanism in Eucalyptus plantations that causes detrimental impacts on understory diversity.Phenolic compounds are the main allelochemicals suppressing understory plants.However,the dynamic changes in phenolic allelochemicals and their relationship with understory diversity with increasing age of Eucalyptus plantations remain largely unclear.In this study,the understory plant diversity was assessed and phenolic compounds identified from leaf litter,roots,and rhizosphere soil samples in a Eucalyptus grandis plantation at two-year intervals for ten years using ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The abundance and diversity of under story plant species were lowest in 4-year-old plantations and increased significantly with age.Seven phenolic acids and 10 flavonoids were identified from leaf litter,roots,and rhizosphere soils.Most of the potential phenolic allelochemicals,such as salicylic acid,gallic acid,4-hydroxybenzoic acid,and epicatechin,were more abundant in younger plantations,especially at4 years old.The concentrations of phenolic compounds in the rhizosphere zone were significantly lower than in litter and root samples and did not change significantly with an increase in age.Notably,phenolic compounds contributed more to the variation in the understory plants than soil factors.Hydroxyphenyllactic acid,ellagic acid,quercetin,salicylic acid,and 4-hydroxybenzoic acid were the main phenolic compounds explaining the variation in plant diversity with plantation age.These findings indicate that young E.grandis plantations,especially at four years of age,merit a greater focus because of their lower understory plant diversity and higher allelopathic potential.

协同共治:粤港澳大湾区建设中大学的角色定位及其实现路径

在国家战略背景下,粤港澳大湾区高等教育融合发展问题倍受社会关注。课题组在粤港澳大湾区、旧金山湾区、纽约湾区、波士顿湾区和东京湾区等国际湾区收集了丰富的访谈资料,在一手资料及协同治理理论基础上,采用扎根理论质性研究方法构建起大学在粤港澳大湾区建设中的角色及治理路径模型。研究结果表明,大学在大湾区建设中承载着特殊角色与常态化角色。特殊角色是湾区文化与价值引领;常态化角色包括英才培育、知识创造、成果转化、制度创业等。适应粤港澳大湾区具体情境,实现大学积极治理的主体角色,必须发挥多元主体协同共治的作用,湾区高等教育协同治理路径表现为大学与政府协同、大学与市场协同、大学与社会协同、大学与大学协同以及大学内部治理协同。

Research Progress of Quorum Sensing in Staphylococcus aureus

Quorum sensing refers to the phenomenon that bacteria sense signal molecules in the environment and regulate a series of genes.At present,the known quorum sensing systems in Staphylococcus aureus are the Agr system and the LuxS/AI-2 system.They will be activated when the bacterial concentration is equal to or greater than 107/ml,and by regulating the corresponding genes,bacteria can indirectly or directly regulate the production and degradation of biofilms,the secretion of bacterial toxins and the growth of bacteria.In this paper,we summarized the research progress of quorum sensing in S.aureus by consulting relevant literatures at home and abroad on quorum sensing in S.aureus,so as to find a new direction for the future research on S.aureus.

A Total Variation Based Method for Multivariate Time Series Segmentation

Multivariate time series segmentation is an important problem in data mining and it has arisen in more and more practical applications in recent years.The task of time series segmentation is to partition a time series into segments by detecting the abrupt changes or anomalies in the time series.Multivariate time series segmentation can provide meaningful information for further data analysis,prediction and policy decision.A time series can be considered as a piecewise continuous function,it is natural to take its total variation norm as a prior information of this time series.In this paper,by minimizing the negative log-likelihood function of a time series,we propose a total variation based model for multivariate time series segmentation.An iterative process is applied to solve the proposed model and a search combined the dynamic programming method is designed to determine the breakpoints.The experimental results show that the proposed method is efficient for multivariate time series segmentation and it is competitive to the existing methods for multivariate time series segmentation.

The Convex Relaxation Method on Deconvolution Model with Multiplicative Noise

In this paper,we consider variational approaches to handle the multiplicative noise removal and deblurring problem.Based on rather reasonable physical blurring-noisy assumptions,we derive a new variational model for this issue.After the study of the basic properties,we propose to approximate it by a convex relaxation model which is a balance between the previous non-convex model and a convex model.The relaxed model is solved by an alternating minimization approach.Numerical examples are presented to illustrate the effectiveness and efficiency of the proposed method.

Thermodynamics of general scalar-tensor theory with non-minimally derivative coupling

With the usual definitions for the entropy and the temperature associated with the apparent horizon, we discuss the first law of the thermodynamics on the apparent in the general scalar-tensor theory of gravity with the kinetic term of the scalar field nonminimally coupling to Einstein tensor. We show the equivalence between the first law of thermodynamics on the apparent horizon and Friedmann equation for the general models, by using a mass-like function which is equal to the Misner-Sharp mass on the apparent horizon. The results further support the universal relationship between the first law of thermodynamics and Friedmann equation.