Regression discontinuity design and its applications to Science of Science:A survey

Purpose:With the availability of large-scale scholarly datasets,scientists from various domains hope to understand the underlying mechanisms behind science,forming a vibrant area of inquiry in the emerging“science of science”field.As the results from the science of science often has strong policy implications,understanding the causal relationships between variables becomes prominent.However,the most credible quasi-experimental method among all causal inference methods,and a highly valuable tool in the empirical toolkit,Regression Discontinuity Design(RDD)has not been fully exploited in the field of science of science.In this paper,we provide a systematic survey of the RDD method,and its practical applications in the science of science.Design/methodology/approach:First,we introduce the basic assumptions,mathematical notations,and two types of RDD,i.e.,sharp and fuzzy RDD.Second,we use the Web of Science and the Microsoft Academic Graph datasets to study the evolution and citation patterns of RDD papers.Moreover,we provide a systematic survey of the applications of RDD methodologies in various scientific domains,as well as in the science of science.Finally,we demonstrate a case study to estimate the effect of Head Start Funding Proposals on child mortality.Findings:RDD was almost neglected for 30 years after it was first introduced in 1960.Afterward,scientists used mathematical and economic tools to develop the RDD methodology.After 2010,RDD methods showed strong applications in various domains,including medicine,psychology,political science and environmental science.However,we also notice that the RDD method has not been well developed in science of science research.Research Limitations:This work uses a keyword search to obtain RDD papers,which may neglect some related work.Additionally,our work does not aim to develop rigorous mathematical and technical details of RDD but rather focuses on its intuitions and applications.Practical implications:This work proposes how to use the RDD method in science of science research.Originality/value:This work systematically introduces the RDD,and calls for the awareness of using such a method in the field of science of science.

Effects of Different Seasons on Cutting Propagation of Five Citrus Rootstocks

[Objectives]To explore the cutting propagation mode of citrus rootstock,improve the survival rooting rate of citrus rootstock,and provide theoretical guidance and technical reference for the rooting research of difficult-to-root plants such as citrus.[Methods]Five citrus rootstocks Citrus tangerina Tanaka‘Hongju’,Citrus haniana Hort‘Suanju’,Citrus limonia Osbeck‘Hongningmeng’,Citrus sinensis×Poncirus trifoliata‘Zhicheng’and Poncirus trifoliate(L)Raf.‘Zhike’were used as experimental materials to select the suitable cutting substrate for citrus rootstocks by measuring the physical properties of the substrate.Cutting was carried out in spring,summer,autumn and winter respectively.After cutting,the morphological changes of cuttings were observed regularly,and the callus rate,germination rate and rooting rate of cuttings were recorded.[Results]The best substrate for citrus rootstock cutting was peat soil,vermiculite and fine river sand(2:1:1).The callus of citrus rootstock in different cutting seasons began to appear in 10-22 d,and the callus rate reached 55%-100%.In terms of budding,the budding time was the earliest in summer and autumn,and slightly later in spring and winter;the germination rate of C.limonia Osbeck‘Hongningmeng’was the highest,and the germination rate of C.sinensis×P.trifoliata‘Zhicheng’and P.trifoliate(L)Raf.‘Zhike’was lower;in terms of rooting,C.limonia Osbeck‘Hongningmeng’had the earliest rooting time and the highest rooting rate and could reach 100%in all seasons;the rooting rate of C.tangerina Tanaka‘Hongju’was 50%-80%;the rooting rate of C.haniana Hort‘Suanju’was 60%-80%;C.sinensis×P.trifoliata‘Zhicheng’and P.trifoliate(L)Raf.‘Zhike’showed the earliest rooting time and the highest rooting rate in summer,and the latest rooting time and the lowest rooting rate in winter,which were only 14.5%.Therefore,different citrus rootstock varieties should choose the appropriate cutting time according to their own characteristics.[Conclusions]The results of this study can provide a scientific basis for a large number of cutting propagation of different citrus rootstocks,and have practical guiding significance for large-scale planting.

自润滑聚合物材料研究进展

润滑失效是导致摩擦运动零部件性能退化的主要原因,自润滑聚合物材料为解决这一问题提供了有效途径。文中综述了自润滑聚合物材料研究进展,对固体纳米粒子填充型自润滑材料、多孔自润滑聚合物材料、微胶囊型自润滑材料3种自润滑聚合物复合材料进行了介绍,重点对微胶囊型自润滑聚合物材料近年来的研究进展进行分析和总结。从自润滑机理、自润滑微胶囊化方法、芯材润滑剂及壁材的种类、自润滑聚合物材料的摩擦磨损性能、减摩耐磨机理等方面进行详细阐述,最后对自润滑聚合物材料的前景进行了展望。

CHRT:Clustering-Based Hybrid Re-Routing System for Traffic Congestion Avoidance

Re-routing system has become an important technology to improve traffic efficiency.The traditional re-routing schemes do not consider the dynamic characteristics of urban traffic,making the planned routes unable to cope with the changing traf-fic conditions.Based on real-time traffic information,it is challenging to dynamically re-route connected vehicles to alleviate traffic congestion.Moreover,how to obtain global traffic information while reducing communication costs and improving travel efficiency poses a challenge to the re-routing system.To deal with these challenges,this paper proposes CHRT,a clustering-based hybrid re-routing system for traffic congestion avoidance.CHRT develops a multi-layer hybrid architecture.The central server accesses the global view of traffic,and the distributed part is composed of vehicles divided into clusters to reduce latency and communication overhead.Then,a clustering-based priority mechanism is proposed,which sets priorities for clusters based on realtime traffic information to avoid secondary congestion.Furthermore,to plan the optimal routes for vehicles while alleviating global traffic congestion,this paper presents a multi-metric re-routing algorithm.Through extensive simulations based on the SUMO traffic simulator,CHRT reduces vehicle traveling time,fuel consumption,and CO2 emissions compared to other systems.In addition,CHRT globally alleviates traffic congestion and improves traffic efficiency.

教师惩戒的失落与回归

教师惩戒是当下我国基础教育改革中备受关注的热点。近年来我国教师惩戒却逐渐步入不敢管、不愿管与不会管、不当管的双重困境中。造成教师惩戒失落的原因是多方面的,包括立法层面的缺失、社会层面的非理性认识、家长理解的偏差、教师自我定位不准等多重因素,而要突破这一困境,也需要多维助力:加强立法工作、社会和家长观念转变、提高教师自身修养等回归机制。

Follicles were reconstituted from dissociated mouse fetal ovarian cells in vitro

Early folliculogenesis involved in the interaction of germ cells and somatic cells is a complicated physiological event. Female germ cells are committed to differentiate into oocytes and finish complete development in the functional units of follicles. Thus there will be great significance in basal research and practices to evaluate the possibility of ovarian cells to reconstitute into follicles in vitro. In the present research, 12-16 dpc (days post coitum) mouse fetal ovarian cells were respectively isolated using collagenase digestion and cultured in droplets in vitro. The results revealed that the fetal ovarian cells of 12-16 dpc appeared to form multiple cell aggregates and tissue-like pieces in vitro. However, 12-13 dpc ovarian cells failed to form the follicles. 14-15 dpc ovarian cells were competent to form a few follicle-like complexes. Furthermore many small typical follicles were reconstituted from 16 dpc ovarian cells in vitro. The results showed for the first time that mouse embryonic

新疆塔什库尔干野生动物自然保护区马可波罗盘羊潜在生态廊道识别

识别野生动物的适宜生境并在适宜生境之间构建生态廊道能够提高生境连通性,有利于加强种群间基因交流并缓解生境破碎化带来的不利影响。本研究基于生境适宜性评价结果确定了塔什库尔干野生动物自然保护区内马可波罗盘羊(Ovis polii)的核心生境斑块,运用廊道设计模型Linkage Mapper识别最低成本廊道并确定其优先级。结果表明,马可波罗盘羊适宜生境主要分布在保护区西北部,核心生境斑块少且破碎化明显,夏冬两季核心生境斑块均为28个,潜在生态廊道分别为45和47条。采用成本加权距离与欧几里得距离之比(CWD:EucD)以及成本加权距离与最低成本路径长度之比(CWD:LCP)两种度量方法评估了生态廊道的质量与重要性。以CWD:EucD来衡量,夏季质量最高的4条廊道分别是皮斯岭至帕日帕克、同库至马尔洋、科克吐鲁克至帕日帕克,以及哈尔努孜至同库;冬季质量最高的3条廊道分别是其克尔克尔至亚希洛夫、萨提曼至依西代尔、其克尔克尔至科克吐鲁克。CWD:LCP分析表明,夏季质量最高的廊道分别是哈尔努孜至阔克加尔和阔克加尔至马尔洋;冬季质量最高的廊道分别是爱勒米希至塔萨拉、沙尔比列西南至依西代尔。利用流中心性评估各核心生境斑块和廊道的重要性表明,帕日帕克、塔萨拉和马尔洋这三个斑块在促进马可波罗盘羊迁移扩散方面的贡献值最高。夏季皮斯岭至帕日帕克、同库至马尔洋和马拉特至其克尔克尔这3条廊道的贡献值最高;冬季爱勒米希至塔萨拉、沙尔比列至沙尔比列西南和铁尔布尔列至沙尔比列这3条廊道的贡献值最高,上述核心生境斑块和生态廊道在维持保护区马可波罗盘羊种群迁徙扩散中发挥着关键作用。此外,赞坎、沙尔比列等斑块虽然面积小、贡献值低,但起到了维持景观中重要斑块连通的踏脚石作用,其重要性也不可忽略。研究结果可为塔什库尔干野生动物保护区马可波罗盘羊有效保护、保护区功能区划优化以及当地基础建设项目的规划选址提供科学指导。

Viral receptor profiles of masked palm civet revealed by single-cell transcriptomics

Civets are small mammals belonging to the family Viverridae.The masked palm civets(Paguma larvata)served as an intermediate host in the bat-to-human transmission of severe acute respiratory syndrome coronavirus(SARS-Co V)in 2003(Guan et al.,2003).Because of their unique role in the SARS outbreak,civets were suspected as a potential intermediate host of SARS-Co V-2.

Effects of thickness on the microstructure and energy-storage performance of PLZT antiferroelectric thick films

The typical antiferroelectric(AFE)thick films Pb_(0.94)La_(0.04)(Zr_(0.98)Ti_(0.02))O_(3)(PLZT 4/98/2)with different thicknesses of 2,4,6 and 10μm were successfully deposited on Pt(111)/TiO_(2)/SiO_(2)/Si(100)substrates from polyvinylpyrrolidone(PVP)-modified chemical solution.The effects of thickness on the crystalline structure,electrical properties and the energy-storage performance were investigated in detail.X-Ray diffraction analysis and scanning electron microscopy pictures indicated that AFE films with a thickness less than 4
m showed a(111)-preferred orientation with uniform surface microstructure.The electrical measurement results illustrated that,as the thickness increased,the saturation polarization,remnant polarization,dielectric constant and leakage current of AFE thick films were enhanced gradually,while the capacitive density and the critical breakdown fields were decreased.Moreover,all the PLZT 4/98/2 AFE films shared the same Curie temperature of about 224℃.As a result,the AFE thick films showed good energy-storage stability in a wide temperature range.The maximum energy-storage density of 47.4 J/cm^(3) was obtained in the 2-μm-thick PLZT 4/98/2 films measured at 3699 kV/cm.