Dependence of normal contact stress on the surface morphology of solid surfaces

Contact problems between two solids are essential to interpret the loading-unloading behaviour in indentation tests. Using linear elastic theory, a general relationship between the normal stress and the surface deformation for elastic contact of two solids was derived, in which the normal stress is a function of the mean curvature of the undeformed surface.     

Do knee concentric and eccentric strength and sagittal-plane knee joint biomechanics differ between jumpers and non-jumpers in landing?

The purpose of this study was to investigate the differences of knee concentric and eccentric strength and impact related knee biomechanics between jumpers and non-jumpers during step-off landing tasks. Ten male college swimming athletes (non-jumpers) and 10 track and volleyball athletes (jumpers) were recruited to participate in two test sessions: a muscle strength testing session of concentric and eccentric extension for dominant knee joint at 60 °/s and 180 °/s and a landing testing session. The participants performed five trials of step-off landing in each of four conditions: soft and stiff landing from 0.4 m and 0.6 m landing heights. The three-dimensional kinematics and ground reaction force were recorded simultaneously during step-off landing conditions. The results showed that the jumpers had significantly greater peak knee eccentric extension and concentric flexion torques compared to the non-jumpers. No significant group effects were found for peak vertical ground reaction force and knee range of motion during landing. The jumpers had significantly greater knee contact flexion angle, maximum knee flexion angle and initial knee extension moment compared to the non-jumpers. These results suggest that these athletes adopted a favorable impact attenuation strategy that is related to the greater knee eccentric muscle strength and training.     

A longitudinal examination of the relationship between teacher burnout and depression

This study investigates the longitudinal relationships between burnout and depression among teachers. Middle and high school teachers participated in a 3‐wave survey. The results of the latent growth modeling analysis revealed that there was a significant relationship between the initial status of burnout and the initial status of depression. Results also indicated a significant relationship between the change rate of burnout and the change rate of depression. Moreover, the autoregressive cross‐lagged modeling revealed a causal relationship such that teacher's burnout leads to subsequent depression symptoms, not vice versa.     

Too exhausted to remember: Ego depletion undermines subsequent event‐based prospective memory

Past research has consistently found that people are likely to do worse on high‐level cognitive tasks after exerting self‐control on previous actions. However, little has been unraveled about to what extent ego depletion affects subsequent prospective memory. Drawing upon the self‐control strength model and the relationship between self‐control resources and executive control, this study proposes that the initial actions of self‐control may undermine subsequent event‐based prospective memory (EBPM). Ego depletion was manipulated through watching a video requiring visual attention (Experiment 1) or completing an incongruent Stroop task (Experiment 2). Participants were then tested on EBPM embedded in an ongoing task. As predicted, the results showed that after ruling out possible intervening variables (e.g. mood, focal and nonfocal cues, and characteristics of ongoing task and ego depletion task), participants in the high‐depletion condition performed significantly worse on EBPM than those in the low‐depletion condition. The results suggested that the effect of ego depletion on EBPM was mainly due to an impaired prospective component rather than to a retrospective component.     

Learning without consciously knowing: Evidence from event-related potentials in sequence learning

This paper investigated how implicit and explicit knowledge is reflected in event-related potentials (ERPs) in sequence learning. ERPs were recorded during a serial reaction time task. The results showed that there were greater RT benefits for standard compared with deviant stimuli later than early on, indicating sequence learning. After training, more standard triplets were generated under inclusion than exclusion tests and more standard triplets under exclusion than chance level, indicating that participants acquired both explicit and implicit knowledge. However, deviant targets elicited enhanced N2 and P3 components for targets with explicit knowledge but a larger N2 effect for targets with implicit knowledge, revealing that implicit knowledge expresses itself in relatively early components (N2) and explicit knowledge in additional P3 components. The results help resolve current debate about the neural substrates supporting implicit and explicit learning.     

指动脉背侧支皮瓣在手指末节皮肤缺损治疗中的临床应用

分析指背动脉背侧支与其血管网联合供血滋养皮瓣在指末端皮肤缺损的修复中的应用效果。取中节手指固有动脉的背侧支为蒂血管,逆行切取指背皮瓣31例共35指,移植修补位于远端指间关节或其远端的皮肤缺损。若同时伴有骨、关节、肌腱等的损伤,则予以同期修复。本研究中最大切取皮瓣1.5cm×3.5cm,平均随访6±0.5个月(3至9个月),皮瓣成活率100%,皮瓣两点辨别觉9±0.2mm,95%的患者具有良好的指间关节活动能力。因此,指动脉背侧支皮瓣手术操作简单,术后成功率高且患者恢复效果好。     

“正名”视野下的《白马论》

本文根据公孙龙的正名理论解读《白马论》,认为"白马非马"的真正含义是"白马之名全异于马之名",也即"白马之实全异于马之实";并表明无须修改通行《道藏》本的论证顺序,文意原本通畅。     

断指再植术后肝素抗凝治疗的风险评估

为了研究断指再植术后用肝素抗凝对再植成活率的影响,将112例因完全离断行断指再植术的患者随机分成两组,对照组术后连续应用肝素10天,试验组仅术后应用48小时,对比两组再植术后血管危象的发生率、成活率及活化部分凝血活酶时间(APTT).结果显示试验组血管危象发生率10.7％、成活率94.6％,对照组血管危象发生率8.9％(P＞0.05)、成活率92.9％(P＞0.05).术后第10天试验组和对照组的APTT之间有差异(P＜0.05).所以术后长时间的应用肝素并不能降低血管危象的发生率,也不能提高再植的成活率,相反却会导致APTT延长.     

真实火灾和模拟火灾情境下小鼠的逃生决策比较*

探讨并比较真实火灾和模拟火灾情境下小鼠是否采用直觉性逃生决策。研究包括一个预备训练和两个主实验。预备训练的目的：首先训练小鼠获得有关迷宫路线及出口的经验,然后再经过遗忘处理使它们遗忘相关经验。两个主实验均采用3(情境：真实火灾,模拟火灾,普通情境)×2(记忆：遗忘前和遗忘后)混合实验设计,因变量均为逃生决策。实验组被试为72只经过训练的小鼠,控制组为24只未经过训练的小鼠。通过考察小鼠在不同情境和不同记忆条件下的逃生时间和对逃生出口的选择探测并比较真实火灾和模拟火灾情境下小鼠的逃生决策差异。主要结果：(1)实验组在真实火灾情境下的逃生时间无论遗忘前后都明显比模拟火灾情境下短;(2)实验组在真实火灾和模拟火灾情境下的逃生时间都明显比控制组短;(3)当熟悉和陌生出口均开启同时熟悉出口处有烟雾条件下,真实火灾组在遗忘前后均倾向于选择熟悉出口逃生,其他两组则倾向于选择陌生出口离开。结论：真实火灾和模拟火灾情境下小鼠的逃生决策存在明显差异：真实火灾情境下受过训练的小鼠倾向于直觉性逃生决策;模拟火灾情境下受过训练的小鼠不倾向于直觉性逃生决策。