A study of parametric versus non-parametric methods for predicting paleohabitat from Southeast Asian Bovid astragali

Studies of the African members of the family Bovidae have demonstrated the feasibility of using linear discriminant analysis to predict paleoenvironment based on measurements from postcranial skeletal elements. The use of discriminant analysis depends upon adherence to certain assumptions about the data set. In certain cases, these assumptions are violated, thus reducing the confidence of the results. The research presented here introduces the use of the non-parametric recursive partitioning method as a test of the linear discriminant method for predicting habitat from a collection of modern Bovid astragali from Southeast Asia. This study also provides a critique of the previous African studies. The results indicate that a combination of the parametric and non-parametric methods provides the highest prediction accuracy for Southeast Asian Bovids, though the independent methods do test favorably; thus providing an additional tool for archaeologists and paleoanthropologists in this region.     

铜及其合金的表面着色机理

根据表面着色的化学动力学原理论证了铜及铜合金表面人工仿古着色处理的某些必要过程。如为何要进行着色前的表面预处理;表面预处理的主要内容及着色反应的化学机理。并对目前众多的人工表面着色配方进行了归纳。     

黄铜器表面着色方法的研究

在总结古代铜器表面处理的文献基础上一通过化学成膜探讨含锌32％－36％的黄铜试样表面着色的方法,通过调整和控制试液的浓度、温度、酸度及浸泡时间的实验,确定黄铜表面栗色膜形成的最佳条件。对表面形成的粟色膜用多种实验手段进行了测定,结果表明栗色股厚度约为8μm主要组成为Cu2O。并对化学过程中形色栗色膜的机理作了初步探体     

Evaluating effects of chemical weathering and surface contamination on the in situ provenance analysis of building stones in the Cuzco region of Peru with portable XRF

As the only type of instrument capable of determining artifact geochemistry in a wide variety of settings, portable X-Ray Fluorescence (PXRF) may be frequently utilized as probably the best option for collecting data when removal of objects in part or in whole is unfeasible. However, using PXRF in circumstances where sample selection and preparation diverge from standards developed for lab-based instrumentation requires assessing the impact of new and potentially limiting factors to establish the validity of the method in these new contexts. Here we examine the effects of surface contamination and chemical weathering on the ability to assess provenance of igneous building stones used in the Cuzco region of Peru. Surface contamination was assessed through comparing low-impact cleaning methods on diorite and andesite blocks, and weathering was examined by comparing weathered vs. fresh surfaces of samples from two andesite quarries. In general, the lightest elements were most impacted by contamination and weathering while measurements of many of the heavier elements commonly used in provenance studies were relatively unaffected. Concentrations of Pb and Zn were problematic in the urban context of Cuzco because of pollution. Ability to determine provenance of building stones within those limitations (i.e., the validity of this application of PXRF) was demonstrated in a preliminary study by comparing measurements from uncleaned, exposed building stones in the region to fresh quarry samples.     

PS表面防风化工艺研究

为研究大型露天遗址的防风化问题,经总结二十多年来PS大规模应用于土遗址保护的经验,逐步形成了一套行之有效的表面防风化工艺。该工艺包括表面喷洒渗透和常压滴渗,两者可单独使用也可联合使用。表面喷洒渗透采用直接向墙体喷洒PS溶液的方式加固,适用于风化层较薄、自身强度较高的墙体;常压滴渗需要在墙面上开孔,将PS溶液通过细胶管或小号针头缓慢滴入土体,以起到更好的加固效果,主要适用于风化层较厚、强度较低的墙体。PS加固以后土遗址颜色稍有变化,采用作旧的方式保持土遗址原来的观感。大量工程实例和后期检测都证明该工艺具有良好的加固效果,可以推广应用。     

Marine shell dates and surface lithic assemblages on the west coast of South Africa

Archaeological surface finds are difficult to date. There are several useful methods, but each requires special circumstances and has one drawback or another. On the west coast of South Africa marine shell are abundant on surface sites but they are rarely dated because they are perceived to be in disturbed context and in questionable association with artefacts. This paper attempts to rectify this misconception and shows that, although far from perfect, a large suite of surface dates can shed as much light as excavated data. On the Vredenburg Peninsula they help refute the hypothesis that two economically and culturally distinct populations shared this pre-colonial landscape since 2000 BP.     

甘肃拉卜楞寺壁画表面涂层材质分析

西藏壁画表面大多刷有保护涂层。据记载,其材质主要是桐油、牛胶或清漆等。但目前,对该涂层材质科学的研究却较少,不利于后期保护修复。为配合拉卜楞寺壁画保护修复项目,本研究以衰减全反射红外光谱法(ATR-FTIR)、核磁共振氢谱法(~1H-NMR)、热裂解-气相色谱-质谱联用(Py-GC-MS)技术等分析手段,对甘肃夏河拉卜楞寺弥勒佛殿、时轮学院主殿壁画的涂层进行了分析。结果表明,两处佛殿壁画涂层可确定是一种干性油,种类与桐油较接近。但由于西藏壁画在材料和工艺上的独特性,材料老化等因素,拉卜楞寺壁画涂层在组成和结构上,与现代桐油有一定差别,表现出一定的丰富性和复杂性。后期修复,可采用性质与西藏传统涂层材料接近的干性油,例如桐油,作为新的壁画表面涂层材料。