区域创新网络在促进路径创造中的作用分析

路径依赖不仅表现在组织层次上,在网络层次、区域层次表现得也很明显。一个区域的持续发展在于不断地创新,其本质在于不断突破原有路径依赖的束缚、创造新的路径。通过阐述区域创新网络的构成、目标与任务,揭示出区域创新网络实现路径创造的两种基本途径,说明区域创新网络的构建与区域的路径创造是一个相辅相成的关系。     

城市形象传播:观念角色路径

现代传媒对城市形象的传播作用不可替代,它自身具备的强大功能影响着城市的形象。本文对城市形象传播中传媒的角色定位进行分析,研究促进城市形象塑造的传播路径。认为媒体应发掘城市精神,建构城市主体文化,既成为沟通政权、资本和智慧的桥梁,同时对内扶助城市人群形成特有的文化归属意识,对外形成良好声誉。     

Two decades of suspect evidence for adaptive molecular evolution—negative selection confounding positive-selection signals

There has been a large literature in the last two decades affirming adaptive DNA sequence evolution between species. The main lines of evidence are from (i) the McDonald-Kreitman (MK) test, which compares divergence and polymorphism data, and (ii) the phylogenetic analysis by maximum likelihood (PAML) test, which analyzes multispecies divergence data. Here, we apply these two tests concurrently to genomic data of Drosophila and Arabidopsis. To our surprise, the >100 genes identified by the two tests do not overlap beyond random expectation. Because the non-concordance could be due to low powers leading to high false negatives, we merge every 20–30 genes into a ‘supergene’. At the supergene level, the power of detection is large but the calls still do not overlap. We rule out methodological reasons for the non-concordance. In particular, extensive simulations fail to find scenarios whereby positive selection can only be detected by either MK or PAML, but not both. Since molecular evolution is governed by positive and negative selection concurrently, a fundamental assumption for estimating one of these (say, positive selection) is that the other is constant. However, in a broad survey of primates, birds, Drosophila and Arabidopsis, we found that negative selection rarely stays constant for long in evolution. As a consequence, the variation in negative selection is often misconstrued as a signal of positive selection. In conclusion, MK, PAML and any method that examines genomic sequence evolution has to explicitly address the variation in negative selection before estimating positive selection. In a companion study, we propose a possible path forward in two stages—first, by mapping out the changes in negative selection and then using this map to estimate positive selection. For now, the large literature on positive selection between species has to await reassessment.     

师生信任的模式、困境与突围——基于现代性的视角

长久以来,教育活动的顺利展开是以师生信任作为基础的,其主要模式为发轫于中国的伦理型师生信任与发轫于西方的契约型师生信任。现代社会的深刻变化导致师生信任模式从伦理型向契约型转变,其不可避免遭遇到“现代性的后果”,体现为信任基础的薄弱、信任对象的割裂、信任情感驱力的缺失以及信任文化的失落。摆脱师生信任的现代性困境,需要从三个方面着手:一是摆脱“非此即彼”的思维窠臼,实现伦理信任和契约信任的融通;二是彰显教师的道德身份,奠定师生信任的情感根基;三是构筑师生信任的长效机制,形成师生信任的文化共识。     

工程网络关键线路在施工中的应用

在工程施工中,运用网络技术来编制进度计划,能反映出各工序间的逻辑关系,通过时间参数的计算,找出网络关键线路,实施动态管理,能有效地控制工程进度,节约人力物力,提高经济效益。     

解读近现代中国体育制度文化(一)——20世纪中国学校体育组织制度演变及其启示

学校体育组织制度是一个规定学校体育管理,规范学校体育行为的系统。通过文献资料法与历史学的研究,分析了中国学校体育组织制度演变并寻找演变过程中的特点,最后指出中国学校体育在20世纪的发展方向。     

解读近现代中国体育制度文化(二)——20世纪中国学校体育课程制度演变摭谈

学校体育课程是根据青少年的身心发展规律和要求,以发展学生体能、增进学生身心健康为目的而制订的,以体育运动为载体的学科知识体系。运用文献资料法,分析了20世纪中国学校体育课程制度的演变过程及其特点,指出:1、学校体育的发展必须与一定社会的政治、经济发展相一致;2、从全球化的视角指导体育文化的交融,以实现体育文化融合的中国化的过程;3、将政府和政党推动学校体育发展的外力转为广大人民群众的内在自觉行为,这才是推动学校体育不断发展的原动力。     

医学伦理教育的问题审视与路径探析

医学伦理教育存在的问题通过教学层面得以直接反映和集中体现。这些问题主要包括教学内容知识化、课程设置模块化、教学过程阶段化、教学方式单一化。政府、高校和学科是医学伦理教育供给侧的核心要素。政府是政策制定方,高校是实施执行方,学科是理论输出方,高校的实施执行结果受制于政府和学科这两个要素。政策内涵模糊导致医学伦理教育目标错置,学科地位迷失导致理论供给缺位,从而从根本上制约了医学伦理教育的发展。破解医学伦理教育的困境和危机,政府层面应加强顶层设计,完善政策供给;院校层面应优化教学模式,完善教学供给;学科层面应加强学术研究,完善理论供给。     

Exploring ancestral phenotypes and evolutionary development of the mammalian middle ear based on Early Cretaceous Jehol mammals

We report a new Cretaceous multituberculate mammal with 3D auditory bones preserved. Along with other fossil and extant mammals, the unequivocal auditory bones display features potentially representing ancestral phenotypes of the mammalian middle ear. These phenotypes show that the ectotympanic and the malleus-incus complex changed notably during their retreating from the dentary at various evolutionary stages and suggest convergent evolution of some features to extant mammals. In contrast, the incudomalleolar joint was conservative in having a braced hinge configuration, which narrows the morphological gap between the quadroarticular jaw joint of non-mammalian cynodonts and the incudomalleolar articulations of extant mammals. The saddle-shaped and abutting malleus-incus complexes in therians and monotremes, respectively, could have evolved from the braced hinge joint independently. The evolutionary changes recorded in the Mesozoic mammals are largely consistent with the middle ear morphogenesis during the ontogeny of extant mammals, supporting the relation between evolution and development.     

中国冰雪运动企业空间格局演化特征及影响因素研究

冰雪运动企业是冰雪运动产业蓬勃发展的重要载体,探究冰雪运动企业空间格局演化特征及影响因素,对于提升冰雪运动普及程度,促进区域冰雪运动产业集聚发展具有重要意义。以中国冰雪运动企业为研究对象,运用最近邻指数、标准差椭圆和核密度分析法,探索2000年、2005年、2010年、2015年和2020年中国冰雪运动企业的空间格局特征及演化趋势,并借助OLS模型解析影响冰雪运动企业空间布局的核心要素。结果表明:中国冰雪运动企业整体空间布局呈现集聚分布,向外扩散趋势不断减弱而集聚态势日益增强;中国冰雪运动企业分布的热点集聚区主要沿着“西南-东北”方向集中在东北地区、京津冀、长三角及珠三角地区,不同时间节点冰雪运动企业呈现不同分布密度;中国冰雪运动企业空间布局的形成是人口规模、经济实力、产业结构、政策支持、固定资产投资、消费需求、交通条件、雪场数量等多种要素综合作用的结果,且不同区位主导因素有所差异。最后,根据实证研究结论,提出相应对策性建议:借势北京冬奥会东风,冰雪运动产业聚焦空间布局、人才培养、政策扶持、产业融合、数字技术,推动产业高质量可持续发展。