基于腾讯迁徙大数据的长三角城市群春运人口流动时空特征

开展城市群人口流动研究对促进区域人口有序流动和城市群协同发展具有重要的理论和实践指导意义。本文基于腾讯迁徙大数据，运用GIS空间统计和K-shell分解等方法，从人口流动总量、位序、时序和网络层级等方面，对我国长三角城市群2018年春运期间的人口流动特征进行系统研究。结果表明：①长三角城市群春运期间大规模的“返乡流”和“返城流”呈现明显的对称性，并分别于除夕和第一个工作日达到最高峰。②经济发展水平相对较高的上海、苏州、杭州等为劳动力输入型城市，而经济发展水平相对较低的盐城、安庆和滁州等为劳动力输出型城市。③长三角城市群内部人口流动网络具有明显的层级特征，其中上海和杭州是人口辐射核心城市，上海-合肥、上海-南京、上海-杭州等是人口流动的主体路径；空间上东部-西部横向人口流动最为频繁，大体呈现“Z”字形。     

Geochemical characterization of ochre from central coastal British Columbia,Canada

The use of ochre and its presence in archaeological contexts is well documented archaeologically, ethnographically and historically. Elemental analysis of ochre is becoming increasingly common as a method for identifying ancient quarrying and mining practices, and for identifying patterns of resource use, trade and exchange. As this type of work has become more common it has become apparent that two critical issues need to be considered: (1) the need for systematic identification of trends and patterns in ochre geochemistry using appropriate statistical analyses, and, (2) consideration of geographic and geologic scale in relation to ochre chemistry. Because ochre is a heterogeneous material relative to other raw material types, it is necessary to apply multivariate and discriminant statistics to differentiate geochemical groups within a sample set. However, caution must be taken when interpreting statistical results at face value. Local geologic and geomorphologic conditions play a significant role in ochre chemistry and need to be taken into account when interpreting analytical results. The purpose of this project was to determine if geochemically distinct groups of ochre could be distinguished through neutron activation analysis (NAA) of archaeological and geological ochres from the central coast of British Columbia, Canada. The results show that it is possible to satisfy the provenance postulate and to differentiate chemical groups through elemental characterization and using multivariate statistical methods.