敦煌刺绣《灵鹫山说法图》的年代及相关问题

本文对敦煌刺绣作品《灵鹫山说法图》的制作年代根据相关的资料作出判断,指出当在7世纪末的武周圣历年间;同时结合中国刺绣的历史,就敦煌古代刺绣作品研究的价值意义提出自己的看法。     

长沙风篷岭汉代漆器制作工艺中淀粉胶黏剂的分析

为研究汉代髹漆工艺中是否含有淀粉粘结剂,利用淀粉粒分析方法提取了长沙风篷岭汉墓出土的漆器残片中的残留物.实验结果显示:在偏光显微镜下观察到具有十字消光特性的淀粉颗粒,粒度大小在13至25μm,且有加热糊化的现象,加热温度在60至80℃,加热时间大约在30min以内.本实验证实在汉代漆器制作过程中使用了淀粉作为粘结剂,为研究汉代漆器的制作工艺提供了新的科学方法.     

Stochastic Efficiency of Bayesian Markov Chain Monte Carlo in Spatial Econometric Models: An Empirical Comparison of Exact Sampling Methods

Spatial econometric specifications pose unique computational challenges to Bayesian analysis, making it difficult to estimate models efficiently. In the literature, the main focus has been on extending Bayesian analysis to increasingly complex spatial models. The stochastic efficiency of commonly used Markov Chain Monte Carlo (MCMC) samplers has received less attention by comparison. Specifically, Bayesian methods to analyze effective sample size and samplers that provide large effective size have not been thoroughly considered in the literature. Thus, we compare three MCMC techniques: the familiar Metropolis‐within‐Gibbs sampling, Slice‐within‐Gibbs sampling, and Hamiltonian Monte Carlo. The latter two methods, while common in other domains, are not as widely encountered in Bayesian spatial econometrics. We assess these methods across four different scenarios in which we estimate the spatial autoregressive parameter in a mixed regressive, spatial autoregressive specification (or, spatial lag model). We find that off‐the‐shelf implementations of the newer high‐yield simulation techniques require significant adaptation to be viable. We further find that the effective sizes are often significantly smaller than nominal sizes. In addition, we find that stopping simulation early may understate posterior credible interval widths when effective sample size is small. More broadly, we suggest that sample information and stopping rules deserve more attention in both applied and basic Bayesian spatial econometric research.     

Reinforcement of the 18th Century Buttresses of Maniace Castle: Design and Execution

ABSTRACT

Maniace Castle, built on Ortygia island in Siracusa (Italy) in the first half of the 13th century and hosting a magnificent hypostyle hall (the Salone), a square area covered by 25 cross vaults supported by columns, was severely damaged by the 1693 earthquake and the explosion of the ammunition dump in 1704. The buttresses, built immediately afterward to counteract the thrust of the 10 surviving vaults, did not guarantee adequate seismic safety so that a metal scaffolding was installed in 2001 to prevent an overturning mechanism. This article discusses the design and execution of an external pre-stressing steel system to increase existing buttress strength and the seismic capacity of the Salone, starting with historical and constructional analyses and dealing with both analytical and technical aspects. The monitoring system installed to detect structural response during and after the working execution is shown, along with some of the data acquired so far.     

Reassessment of the Lower Paleolithic (Acheulean) presence in the western Tien Shan

Kulbulak (Uzbekistan) is among the most important Paleolithic sites in Central Asia. Based on excavations from the 1960s to the 1980s, a stratigraphic sequence yielding 46 archeological horizons of the Lower, Middle and Upper Paleolithic has been described. The lowermost 22 layers were at that time defined as Acheulean, both in cultural and chronological aspects. Based on these previous works, Kulbulak has thus often been cited as one of the rarest occurrences of Lower Paleolithic and Acheulean in the region. However, this attribution was debatable. New excavations at Kulbulak in 2007–2010 provided new material and the first reliable dates that permitted us to tackle this issue. Moreover, a reappraisal of the lithic collections and documents from previous excavations was also conducted. These new data clearly indicate the absence of Acheulean or even Lower Paleolithic at Kulbulak. On the contrary, the lithic assemblages from this site only correspond to Middle and Upper Paleolithic periods. The lowermost layers are particularly interesting due to the presence of an early industry with blade and bladelet technology.     

Socio‐cultural innovations of the Final Umm an‐Nar period (c.2100–2000 BCE) in the Oman peninsula: new insights from Ra's al‐Jinz RJ‐2

The Early Bronze Age site of RJ‐2, located close to the coastal village of Ra's al‐Jinz on the eastern Omani coast (Niyabat Ra's al‐Hadd), was the focus of archaeological investigations for over two decades. The latest campaigns of excavation unearthed an architectural complex (Building XII) dated to the very end of the Umm an‐Nar period (Final UaN, c.2100–2000 BCE), previously attested on site by poorly preserved remains. This paper presents the remains explored during the most recent fieldwork, focusing on the stratigraphic‐structural sequence and the spatial layout. It also considers the transformations affecting structural evidence and material culture during this period, at both local and regional level, highlighting their significance for a comprehensive assessment of the last occupations related to the Early Bronze Age in south‐eastern Arabia. The paper concludes by showing how the Final Umm an‐Nar phase represents an age of substantial socio‐cultural innovations, which most likely shaped the transition towards the following Wadi Suq period.