Experimental assessment of plan-view and profile-view gross-edge curvature on stone flake slicing efficiency

Separating two or more aspects of an object via cutting was likely an important factor in the origin and evolution of flaked stone technology. In recent years experiments have demonstrated that several stone tool attributes can influence different kinds of cutting behaviour: slicing, cleaving, scraping, sawing, drilling, piercing and abrading. Here we experimentally assessed the role of stone flake plan- and profile-view gross-edge curvature in a controlled slicing task. We also assessed the role of edge length. A total of 21 participants, using 252 stone flakes with distinct gross-edge curvatures and edge lengths, were asked to cut through a standardized substrate, and their efficiency in the task was measured over time. Flakes with longer edge lengths increased the efficiency of the cutting task, but increasing either plan- or profile-view edge curvature decreased the efficiency of the cutting task. These results have implications for the emergence of particular tool forms or reduction sequences throughout the Pleistocene, and may in part explain why certain forms were favoured by Paleolithic people, leading to their convergent evolution or widespread transmission.     

Was Civil War surgery effective?

During the U.S. Civil War surgeons performed a vast number of surgeries. Whether surgery increased wounded soldiers’ chances of survival has been debated ever since. I analyze a unique observational data set gathered by Dr. Edmund Andrews, a surgeon with the 1st Illinois Light Artillery. I use Dr. Andrews’s data, model selection tools, and doubly robust estimation methods to estimate treatment effects from surgery. I find that surgery increased wounded soldiers’ chances of survival by 0.09–0.16, depending on the specific model of surgical procedure.     

铜-铁复合兵器铁刃的分析

对上海博物馆馆藏新品王件春秋早期的铜一铁复合兵器中铁的类型、制成方法、机械性能和材料组织进行了分析,以判明铁刃的原料来源和制作工艺。结果表明：铁刃基体成分为较纯的铁,没有发现镍元素,铁刃组织呈层状分布,结构疏松,合较多夹杂物和孔洞,夹杂物由硅酸盐类复相组成,证实了三件铜一铁复合兵器的铁刃是由人工冶铁锻制而麻     

The relationship between neighborhood design and social capital as measured by carpooling

This paper examines whether social capital in a neighborhood is influenced by its design, taking the cul‐de‐sac as a special case. It offers two contributions: using carpooling to school as a proxy for social capital and a precise definition of the neighborhood using geo‐coded survey data from California. Living in a cul‐de‐sac neighborhood is found to increase the probability of carpooling, but the effect loses statistical significance when residential self‐selection is accounted for. The analysis reveals competing insights about the self‐selection behavior that must be resolved before neighborhood design can be considered an effective policy tool for enhancing social capital.     

Firm networks,borders, and regional economic integration

Borders reduce interprovincial trade relative to intraprovincial trade. Using trade and firm ownership microdata over a 9-year period (2004–2012), we show firm ownership networks, like trade flows, diminish with distance and borders and that the estimated effect of provincial borders on trade may fall by almost 75% after accounting for firm networks. This suggests the weaker presence of firm networks across borders has a significant, although statistically imprecise, effect on interprovincial trade. These findings reinforce the view that understanding border effects require not only the identification of barriers to trade but also barriers to investment across borders.     

How relationships can influence an organic firm’s network identity

ABSTRACT

A main challenge when organic food actors cooperate with conventional food actors is to maintain their identity in the relationship. In this paper, we analyse such a relationship through the use of the industrial marketing and purchasing perspective (IMP). The aim is to increase knowledge about changes in relationships that occur through growth processes and about how new relationships influence the identity of a quality-oriented firm. We use a case-study method when examining the relationship between the organic Røros Dairy and the retail chain Coop, and its effects on relationships within the dairy network. Results show that the focal relationship influences, and in turn is influenced by, the dairy’s network. Because of the dairy’s strong identity that preceded its formal cooperation with Coop, as well as its reputation for quality production and continuous product development, the dairy has strengthened its position in the network. We conclude that the IMP perspective contributes a valuable framework in this study of an organic food network. For business managers, our results highlight the importance of considering possible effects of relationships on the identity one would want to convey.     

罗马对外扩张的历史影响

罗马的对外扩张是世界古代史中的重大历史事件之一。它对罗马乃至地中海世界历史的影响是深远的。对外扩张导致了帝国的形成 ,帝国的形成却为罗马历史的前进平添了沉重的历史包袱 ,但对罗马文化的形成与发展起了推动作用     

区域一体化的人口增长与集散效应——以长三角地区为例

城市群一体化深化过程中,如何引导人口布局优化,是推动经济社会高质量发展的重要举措之一。本文基于长三角1990—2017年城市尺度数据,采用双重差分模型,多角度检验一体化的城市人口增长效应,并初步探讨相关驱动机制。结果表明：(1)一体化能够显著促进城市人口更快增长,且城市就业人口规模越大、人口集聚效应越显著。(2)总体效应的显著性,并不能掩盖一体化过程中人口集聚效应的异质性,一方面随着加入协调会时间的推进,不同阶段效应由正转负,另一方面存在不同批次间效应先增长后下降的差异。(3)一体化过程中要素集聚带来的经济发展水平提升,是城市人口更快增长的关键动力,中介效应与调节效应模型验证了这一假设。     

沙漠边缘区兵团职工活动行为的空间特征——以新疆生产建设兵团某团三连为例

本文通过对地处沙漠边缘区、具有单线式等级逐级递增商业网点的新疆生产建设兵团某团三连全体土地承包户2009年全年外出活动的调查发现,使用频率高或质量较重不便运输的生产资料集中于近距离购买;质量及售后保障敏感度较高的商品购买空间分布零散;中高档生活用品的购买行为空间,呈现"远近匀称式"的空间形态;耐用性商品购买多在"非近即远"的空间距离进行;农产品销售呈现"中短距离匀称式"空间分布形态;2009年全连职工外出活动频率呈"中间距离凹陷式"空间现象。     

Effect of heating on the stable carbon and nitrogen isotope ratios of bone collagen

The effects of heat on the stable carbon and nitrogen isotopic ratios of collagen in bone were studied. Boiling or roasting did not change the δ¹³C and δ¹³N values by more than 1‰. More extreme heating, such as might occur if bones were burned or a body cremated, shifted δ¹³C and δ¹⁵N values by as much as 5 and 4‰ respectively. These large shifts were accompanied by changes in the atomic carbon-to-nitrogen ratios of the collagen. These results indicate that collagen samples extracted from prehistoric bones which display anomalous atomic carbon-to-nitrogen ratios may have been subjected to heating extreme enough to have altered their ${}^{13}\text{C}{}^{12}\text{C}$ and/or ${}^{15}\text{N}{}^{14}\text{N}$ ratios and therefore should not be used for dietary reconstruction.