The archaeology of radiocarbon accelerator dating

Accelerator mass spectrometry (AMS) allows radiocarbon dating to be carried out by direct counting of¹⁴C atoms, rather than the conventional counting of radioactive disintegrations. The result is that samples up to 1000 times smaller can be handled. The approach was tested in principle by 1977 and for archaeological operation by 1983. More than 2000 samples per year are now being dated worldwide. The machines can now operate to about ± 80 years or better. Dates older than 40,000 years have not yet been achieved, but the ability to use small samples has already had considerable impact on dating the period 10,000–30,000 years ago. Bone is an ideal material for the new technique, since amino acids can normally be isolated and purified from gram-size samples. Studies of the origins of domestication are aided by the dating of individual grains and seeds. Because small samples can be mobile in the soil, careful sample selection strategies and procedures are required. The full impact of the technique can be assessed only through the rapid and comprehensive publication of archaeological results.     

Topic Modeling and Text Analysis for Qualitative Policy Research

This paper contributes to a critical methodological discussion that has direct ramifications for policy studies: how computational methods can be concretely incorporated into existing processes of textual analysis and interpretation without compromising scientific integrity. We focus on the computational method of topic modeling and investigate how it interacts with two larger families of qualitative methods: content and classification methods characterized by interest in words as communication units and discourse and representation methods characterized by interest in the meaning of communicative acts. Based on analysis of recent academic publications that have used topic modeling for textual analysis, our findings show that different mixed‐method research designs are appropriate when combining topic modeling with the two groups of methods. Our main concluding argument is that topic modeling enables scholars to apply policy theories and concepts to much larger sets of data. That said, the use of computational methods requires genuine understanding of these techniques to obtain substantially meaningful results. We encourage policy scholars to reflect carefully on methodological issues, and offer a simple heuristic to help identify and address critical points when designing a study using topic modeling.     

汉代漆器的剖析

通过制备并分析一系列模拟漆膜样品。建立了有助于鉴定汉代漆器成分的剖析方法。经裂解气相色谱、差热分析、色谱一红外联用等现代分析技术对出土的汉代漆器残片样品的综合分析,证实在西汉漆器制造中已使用桐油或其它的添加剂,并依据剖析的结果,对某些汉代漆器的原材料差异作了初步探讨。     

Radiocarbon Chronology of the Siberian Paleolithic

We have compiled 462 C-14 determinations for 120 Paleolithic and Mesolithic sites from Siberia and the Russian Far East. The Mousterian sites are dated to ca. 46,000–28,500 BP. The Middle–Upper Paleolithic transition dates to ca. 43,300–28,500 BP. Although there are a few earlier sites, most of the Upper Paleolithic sites are dated to the time interval between ca. 34,000 BP and 10,000 BP. The earlier Upper Paleolithic stage is characterized by macroblade technology and is radiocarbon-dated to ca. 34,000–20,000 BP. The earliest microblade technology occurs in the late stage of the Upper Paleolithic, dated to ca. 23,000–20,000 BP, but the majority of microblade sites is dated to ca. 20,000–11,000 BP. The Final Paleolithic (Mesolithic) sites date to ca. 12,000–6000 BP. At ca. 13,000–11,000 BP, the earliest Neolithic appeared in both the Russian Far East (Amur River basin) and the Transbaikal. The Paleolithic–Neolithic transition occurred ca. 13,000–6000 BP.     

The Unitary Association Method of Relative Dating and Its Application to Archaeological Data

The primary objective of relative dating techniques is to determine a reliable sequence of archaeological deposits. This task becomes more difficult whenever our research steps beyond individual sites to the study of intercommunity relationships because we need to develop some means of associating unconnected deposits in time. Radiocarbon dating, as a stand-alone method, cannot always be used to draw reliable correlations between sites. The relevance of archaeological dates, including absolute dates, relies ultimately on the determination of artifact or sample associations and their respective superpositional relationships. The Unitary Association Method of Relative Dating is an alternative to seriation methods that is less susceptible to spatial variation and offers analytical strengths needed for regional chronological analyses.     

高颐阙残损阙檐的修复技术

高颐阙是东汉晚期的红色砂岩的建筑物。位于四川省雅安市。阙檐东面残缺.导致日晒雨淋加剧,苔藓丛生,从而引起严重风化。为此,对残损阙檐进行了修复。根据高颐阙的结构.雅安市的气候特征及阙石的化学组成和物理性质.讨论了薄片检查和 X 衍射分析的结果、修复残缺阙檐的理论基础以及计算、修复的程序和效果。