Discrepancies in surface temperature between NCEP reanalysis data and station observations over China and their implications

Previous studies show that temporal irreversibility(TI),as an important indicator of the nonlinearity of time series,is almost uniformly overestimated in the daily air temperature anomaly series over China in NCEP reanalysis data,as compared with station observations.Apart from this highly overestimated TI in the NCEP reanalysis,some other important atmospheric metrics,such as predictability and extreme events,might also be overestimated since there are close relations between nonlinearity and predictability/extreme events.In this study,these issues are fully addressed,i.e.,intrinsic predictability,prediction skill,and the number of extreme events.The results show that intrinsic predictability,prediction skill,and the occurrence number of extreme events are also almost uniformly overestimated in the NCEP reanalysis daily minimum and maximum air temperature anomaly series over China.Furthermore,these overestimations of intrinsic predictability,prediction skill,and the number of extreme events are only weakly correlated with the overestimated TI,which indicates that the quality of the NCEP reanalysis should be carefully considered when conclusions on both predictability and extreme events are derived.

Animal models of tendon calcification:Past,present,and future

Tendon calcification is a common clinical condition that frequently occurs as a complication after tendon injury and surgery,or as an expression of fibrodysplasia ossificans progressiva.This condition can be referred to by various names in clinical practice and literature,including tendon ossification,tendon mineralization,heterotopic ossification,and calcific tendonitis.The exact pathogenesis of tendon calcification remains uncertain,but current mainstream research suggests that calcification is mostly cell mediated.To further elucidate the pathogenesis of tendon calcification and to better simulate the overall process,selecting appropriate experimental animal models is important.Numerous animal models have been utilized in various clinical studies,each with its own set of advantages and limitations.In this review,we have discussed the advancements made in research on animal models of tendon calcification,with a focus on the selection of experimental animals,the sites of injury in these models,and the methods employed for modeling.

多维协同效应诱导的高压电性及可靠性的KNN压电陶瓷应用于高频超声换能器

高频超声换能器已成为现代医学诊断和治疗的有力工具.目前,大多数超声换能器使用压电陶瓷进行机电耦合,在高频(>20 MHz)下会发生周期性的电声转换,因此对材料可靠性要求较高.本文提出了一种结构调控策略,以提高铌酸钾钠(KNN)基无铅陶瓷的压电性与可靠性,并用于高频超声成像.该KNN基陶瓷具有增强的压电性(d33~550±20 pC N^(-1))及抗疲劳特性,同时针对其良好性能,我们从涉及宏观到微观的多项共存、完好微观结构与灵活畴翻转的多维度协同效应阐述其机理.该多维度协同效应抑制了疲劳过程中性能恶化裂纹的出现及空间电荷的聚集,从而减少了畴壁的钉扎,增强了抗疲劳性.此外,基于该高性能压电陶瓷制备的超声换能器具有高可靠性及温度稳定性(从室温到80℃,频带宽度几乎不变).我们利用该超声换能器扫描罗非鱼眼球结构测试了器件成像效果.相信通过结构策略实现性能提升的新方法可以促进KNN基超声器件在生物医学方面的应用.