聚醋酸乙烯酯乳液的表征、性能及其在彩绘类文物保护中的应用

聚醋酸乙烯酯(PVAc)乳液是常见的彩绘类文物保护材料。采用激光粒度仪、热重/差热分析、红外光谱、X-射线衍射、扫描电镜、透射电镜等表征了PVAc乳液的粒径以及胶膜的热稳定性、结构和形貌;采用粘度计、表面张力仪、pH计、电导率仪等研究了乳液浓度与其粘度、表面张力、pH、电导率的关系;通过冻融、室温-高温放置、离心分离研究了乳液的稳定性;同时用PVAc乳液对模拟起甲和酥碱的壁画进行了修复。结果表明,PVAc乳液粒径呈双峰分布,小粒子的平均粒径为380 nm,大粒子的平均粒径为5.85μm;乳液胶膜为非结晶物质,胶膜热重的最终质量残留为1.54%,335℃出现放热峰。PVAc乳液的电导率随浓度的增大而增大,pH随浓度的增大而下降;相同温度下表面张力随浓度的增大而基本呈现低浓度下降,高浓度上升的趋势。相同浓度下,表面张力随温度升高而无显著变化,表明PVAc乳液的表面张力受温度变化影响不大。相同温度下,乳液粘度随浓度的增大而增大;相同浓度下,乳液的粘度随温度的升高而降低。冻融、离心分离和不同温度下静置发现,该乳液出现分层。用该乳液对模拟起甲和酥碱壁画修复后,再分别老化20个循环和12个循环,发现颜料层再次空鼓、起甲。综合分析,说明实验中所使用的该种PVAc稳定性和抗老化能力较弱,在修复彩绘类文物中应慎重选择PVAc的种类,综合考虑PVAc的使用浓度、环境因素对其性能的影响,以达到最佳使用效果。     

慈利白公城遗址出土木材种属的鉴定研究

慈利白公城遗址历史悠久,具有重要的考古价值。该遗址出土了大量木质井壁及少量其他木质文物,为了解这些木材的特点,以及为木材保护提供相关的参考,通过徒手切片,并利用光学显微镜对该遗址出土的10件木质样品进行鉴定。结果表明其中1件为无患子(Sapindus. mukorossi Gaertn.),1件为冷杉(Abies fabri(Mast.)Craib),2件为湖南杨桐(Adinandra. acutifolia Hand.-Mazz.),2件为香椿(Toona sinensis A. Juss.),4件为润楠(Machilus pingii Cheng ex Yang)。通过实验结果,初步推测井壁的制作在当时是比较重要的工作,此时已经在选择性地使用木质井壁原料。从树种适宜生长的环境上看,同时期该遗址附近可能是以阔叶材为主的针阔叶混交林,气候温暖湿润。     

Self‐determination and a shattered star: Statehood and national identity in the Somali Horn of Africa

This article explores the articulation—in different forms, at different periods, and by different actors—of ‘national self‐determination’ in Somalia and across the Somali‐speaking regions of the Horn of Africa. It explores how this concept can be understood in the context of protracted political fragmentation in Somalia—considering unresolved debates over the ideological foundations of state reconstruction, disagreements about the suitability of federalism, aspirations for the recognition of an independent Republic of Somaliland, and the distinctive trajectory of the Somali Regional State in Ethiopia. Taking a comparative, cross‐border and wide‐angled historical approach, the article argues that ideas of an ethno‐linguistically, culturally and religiously defined Somali ‘nation’ continue to coexist (and be reproduced, updated and used) within an environment of extreme political fragmentation and across multiple ‘state’ boundaries. This argument is made through comparative analysis of contemporary examples of the performance of Somali state and nationalist identities within and beyond the region and the distinctive transnational Somali‐language media environment within which these ideas circulate and compete.     

Nitrogen cycling in western India as revealed by nitrogen isotopes,and the historic production of saltpetre

Saltpetre (KNO₃) manufacture was a principal monopoly industry in early Modern India when the United Kingdom governed the social and economic systems. The process represented microbial transformation of excrementitious livestock and human wastes deposited around habitats, resulting in formation of salt efflorescence at an economic scale. Low caste people collected these wastes for extraction and production of rough saltpetre under the administrative control of British India. Stable isotope composition (δ¹⁵N and δ¹⁸O) was used to trace details of the microbial transformation processes, often involving the isotopic fractionation of nitrogen and oxygen. Marked elevation in δ¹⁵N and δ¹⁸O values for nitrates in soils and deposits, relative to those of primary organic nitrogen in diets and water sources, characterizes the unique processes of historic saltpetre manufacture in British India.     

Variation in human bone bioerosion during the Late Eneolithic/Bronze Age in Moravia (Czech Republic): A novel approach to BSE-SEM image quality and quantity assessment

Human bones from Late Eneolithic graves and Bronze Age settlement pits in Moravia (Czech Republic) were studied to reconstruct their post-mortem histories based on the distribution of their microbial destruction. Backscattered electrons in a scanning electron microscope (BSE-SEM) were used for visual assessment of bioerosion. Visual data from the histological analysis were transformed into quantitative data using the Waikato Environment for Knowledge Analysis (WEKA) toolkit. The results show that the presence of bioerosion is different between the two groups of samples. The bones from settlement pits display extensive bioerosion whereas the bones from graves display no or arrested bioerosion. The absence of bioerosion in graves is most probably linked with tomb burials of Corded Ware Culture. Given the tombs are frequently not preserved archaeologically, the state of bone bioerosion may serve as an indicator of their existence.     

Inca builders at Machu Picchu National Archaeological Park

Knowledge about the Inca measurement system is based on information from the colonial chronicles and modern studies of the 16th-century Quechua dictionaries. Based on those texts, we can presume that the Incas used an anthropometric system of measurement adopted from the proportions of the human body. Using cosine quantogram analysis and statistical verification, it is possible to verify the existence of the measurement system used by the Inca architects. For this purpose, a measurement series of architectural and water infrastructure elements were collected from 3D point cloud of the Chachabamba and Machu Picchu settlements in Machupicchu National Archaeological Park.     

Exploring the context and elements of local environmental stewardship: An embedded case study of the Niagara Region,Canada

Environmental stewardship—a concept that describes the relationships between humans and the environment—is gaining increased attention as an approach that can address planetary sustainability issues. In-depth empirical investigations of local environmental stewardship are needed to understand how social-ecological context influences stewardship, as well as the arrangement of conceptual elements in applied settings. This study addresses these needs by conducting an in-depth exploration of environmental stewardship in the Niagara Region of Canada. A single embedded case study design is employed, with environmental stewardship initiatives constituting the individual units of analysis with the case. Analysis of the spatial arrangement of a total of 89 initiatives indicated that initiatives tended to cluster closer to the Niagara River and in more populous municipalities. The significance of collaboration, tensions between the environment and economic development, and concerns about political impacts emerged as themes across contextual factors. The configuration of stewardship elements reveals interesting discrepancies between initiatives and previous stewardship research focused on larger scales, individuals, and organizations. Further analysis is encouraged to illuminate environmental stewardship in other settings as well as advance relational understanding of conceptual elements.     

MORE THAN MEETS THE FACT: THE UNIVERSALITY OF HISTORY AND THE COLONIAL MEDIATION

This article examines how mediation is not just limited to the format that's selected to convey the findings of previously conducted research that supposedly followed the conventional protocols of the historical discipline. Rather, it considers mediation as a fundamental part of building historical knowledge, for it assumes that every part of the historiographical operation can be defined as “mediation.” Specifically, it deals with colonial historical mediation, a concept that refers to the combination of an overt or concealed agenda, intentional or unnoticed bias, commonsense assumptions, inherited academic and political traditions, conceptual constellations, and more or less informed theoretical beliefs that configure the subtext upon which historical explanation is built, particularly in Latin America.     

HISTORY MAKING AND ETHICS—AN INTEGRAL RELATIONSHIP?

In this review essay, I examine the arguments made by Marnie Hughes-Warrington, with Anne Martin, in Big and Little Histories: Sizing Up Ethics in Historiography. While I find much to praise in this history, I also ask critical questions about the impact of non-Western ethics on historical writing, the role of ethics in historical writing generally, the need to further investigate the everyday lifeworlds of history makers in order to fully understand their ethical dispositions, and the relationship between the ethics of history making and engaged forms of historical writing. I conclude this review essay by offering some reflections on the interrelationship between history and memory and the ethics involved in both.     

Evidence on economies of scale in local public service provision: A meta-analysis

The standard theory of optimal jurisdictional size hinges on the existence of economies of scale in the provision of local public goods and services. However, despite its relevance for forced local amalgamation programs and related policies, the empirical evidence on the existence of such economies of scale remains elusive. The main goal of this paper is to produce an updated and comprehensive quantitative review of the existence of economies of scale in the provision of local public goods using a meta-analysis approach to systematize the wide range of empirical approaches and modeling frameworks found in the previous literature. Our analysis confirms the presence of moderately increasing to constant returns to scale in the provision of local services with no reduction in the average costs of production in the delivery of most local public services beyond a certain, modest jurisdictional size, which many studies have estimated at 10,000 residents. Also, the potential for economies of scale differs at least across three traditional services: education, water and sanitation, and garbage collection, being highest for education and lowest for garbage collection. Our analysis also offers guidelines for future empirical research in this area. Physical output and production cost data should be used, together with translog specifications for the modeling of cost functions. Last, we find evidence that the determinants of output cost elasticity include bidirectional publication bias and population density but do not include the presence or absence of modern “lean” production technologies or the (perceived) capital intensity of the sector, contrary to conventional wisdom. These findings have significant policy implications for countries considering jurisdictional consolidation programs.