An experimental study of nitrogen flux in llamas: is N preferentially excreted?

Nitrogen isotope analysis is now commonly used to investigate the diets, and to a lesser extent, the environments of ancient populations. These studies assume that mammals are predictably enriched in ¹⁵N over their food, and concomitantly, that ¹⁵N becomes increasingly concentrated as one moves up the food chain. The literature commonly states that this ¹⁵N-enrichment of mammalian tissues is due to preferential excretion of light nitrogen (¹⁴N), but there are few data to support this assertion. To address the gap, we conducted two nitrogen flux trials in which four llamas (Lama glama) were fed high- and low-protein diets. The ratios of fecal nitrogen loss to urinary nitrogen loss were 0.30 and 0.88 on the high- and low-protein diets respectively. Feces were enriched in ¹⁵N by approximately +3‰ on both diets, whereas urinary nitrogen was depleted in ¹⁵N (−2.1‰) on the low-protein diet, but not significantly different from intake δ¹⁵N on the high-protein diet. Most importantly, there was no statistically significant difference between dietary and total excreta δ¹⁵N on either diet. Given these data and theoretical considerations, we argue that the nitrogen influx and efflux of adult mammals at steady state should be isotopically commensurate. However, during growth, diet change, thermal or nutritional stress, animals may not be at steady state and fractionation between intake and excreta δ¹⁵N may occur.     

政府控制、权力制衡与旅游上市公司经营绩效的关系研究

政府控制是我国旅游上市公司中常见的现象。在2011）年沪深两市共26家旅游上市公司中,仅有新都酒店、ST东海、大连圣亚、世纪游轮四家公司的实际控制人为自然人或民营企业法人,政府直接或间接控制的上市公司数量占比高达85％。根据终极产权理论和相关的经验研究结果,不同的终极控制人的性质对企业经营绩效的影响存在很大差别。本文利用沪深两市2003～2010年间旅游上市公司的非平衡面板数据,对政府控制、权力制衡与旅游上市公司经营绩效之间的关系进行了实证研究。,研究结果表明,在当前的市场环境下,地方政府控制的旅游上市公司经营绩效高于非政府和中央政府控制的旅游上市公司,同时,适当减少地方政府控制权比例,建立科学的制衡机制将有助于提高;茂国旅游上市公司的经营绩效。     

铜绿山古铜矿遗址古坑木防腐保护

通过模拟试验和现场试验,对铜绿山古铜矿遗址古坑木的保护方法进行了研究,找到了一种较适合于古铜矿遗址使用的古坑木保护方法,取得了较好的效果。     

Fluid inclusion and isotopic constraints on the origin of ore‐forming fluid of the Jinman–Liancheng vein Cu deposit in the Lanping Basin,western Yunnan,China

Extensive quartz–carbonate–Cu sulfide veins occur in clastic rocks and are spatially related to Paleocene granites in the western border of the Lanping Basin, western Yunnan, China. Abundant aqueous‐carbonic fluid inclusions occur in these veins but their origin is debated. In the Jinman–Liancheng deposit, individual primary inclusion groups contain either exclusively liquid‐rich inclusions (Gl), or coexisting liquid‐rich and vapor‐rich inclusions (Glv). Microthermometry and estimate of CO₂ content indicate that type Gl inclusions either have homogenization temperatures (Th) 238–263°C and contain c. 3.9–5.5 mole % CO₂, or have Th 178–222°C and contain c. 1.6–3.2 mole % CO₂. Type Glv inclusions are thought to represent samples of fluid unmixing that occurred at 183–218°C. At that time, the liquid phase in the unmixing fluid may contain c. 2.0–3.3 mole % CO₂. As such, the correlation of CO₂ content with Th for type Gl inclusions is thought to be caused by fluid unmixing with decreasing temperature and subsequent CO₂ escape. δ¹⁸O and δD values of the parent water mainly fall in the field below that of primary magmatic water, indicative of fluid derivation from degassed (in open system) magmatic water, with no contributions from basinal or meteoric water. Initial Sr isotopic compositions of hydrothermal carbonates suggest that the fluid was magmatic, probably derived from the Paleogene granites. δ¹³C_PDB values (?4‰ to ?7‰) of the hydrothermal carbonates and δ³⁴S_V‐CDT values of sulfides (mainly ?11‰ to +5‰) indicate that the carbon and sulfur can be derived from (degassed) magma and/or nonmagmatic sources. The CO₂‐rich and magmatic‐water‐derived fluid at Jinman–Liancheng differs from the CO₂‐poor and basinally derived fluid in sediment‐hosted stratiform Cu (SSC) deposits, which suggests that there are no genetic linkages between the vein Cu and SSC deposits in the Lanping Basin.     

Metallurgical Characterization of A Coated Roman Iron Coin By Analytical Investigations

A coated Roman iron coin from Villa Loig in Salzburg, Austria was investigated. The coating is a copper alloy consisting of Cu, Pb, Sn, Zn and negligible amounts of Ag, a variant of gunmetal known as ‘leaded red brass’. The numismatic term for such a coin is subferratus (Latin). From an archaeometallurgical point of view, information about the chemical composition, the microstructure and the manufacturing technique are of interest. To achieve these objectives, different analytical techniques and metallographic examinations were applied. Droplet‐shaped iron inclusions were observed in the red brass coating, while at the grain boundaries, inside the iron core, copper and lead were detected (liquid metal embrittlement). The dendritic microstructure of the coating, the spheroidal‐shaped iron inclusions in the coating and the liquid metal embrittlement show that the iron coin was plated by immersing it in a molten copper alloy. The iron core is a low‐carbon steel with slag stringers, both of which are characteristic of a bloomery iron. Deformation twins (Neumann lines) were observed in the microstructure of the iron core and indicate that the coining was performed after the flan was cooled.     

The International Character of a Trimmer: Interest,Reason of State,and Balance of Power in Halifax's Political Thought

This article argues that George Savile's thought casts light on international relations in the seventeenth century. Halifax's life and works concern not only England's domestic politics, but also its foreign affairs. Indeed, he develops a clear vision of international politics. This article analyses Halifax's international thought, in particular three concepts that are closely related to one another: ‘interest’, ‘reason of state’, and ‘balance of power’. Through the study of these ideas, this article will try to point out both the novelty of Halifax's thought compared with that of his contemporaries, and to reverse the stereotypical understanding of his intellectual legacy and political behaviour. The ‘trimmer’ contrasts with Louis XIV's attempt to establish a universal monarchy across Europe, outlining a doctrine of moderation that seeks to ensure liberty, security, and restraint in international relations.     

The later prehistory of mainland Southeast Asia

Until the recent expansion of research into the prehistory of mainland Southeast Asia, the development of civilizations employing Indian religious and political concepts had been seen as a major fulcrum in the area's history. The prehistoric sequence in the area is reviewed, with particular attention being paid to evidence for ritual, display, exchange, and ranking behavior within lowland sedentary communities. These date to the two or three millennia preceding Indian contact. It is argued that already by the end of the prehistoric period, there were complex centralized societies with a long tradition of recognizing status differentials among individuals, affiliated groups, and communities. The sequence incorporates the exploitation of rice, and bronze and iron working. The chronology of these innovations is compared with that in China. It is not possible at present to argue for single or multiple origins, but the area of southern China is suggested as a crucial one in further research to resolve these issues.     

Lead isotopic analyses of copper ores in the Early Bronze Age central Hexi Corridor,north-west China

This paper explores the possible provenance of ores employed for metallurgical production during the Early Bronze Age in the central Hexi Corridor of north-west China. In total, 78 pieces of copper (Cu) ore samples were collected from five Early Bronze Age sites and one Cu deposit site (the Beishantang Cu deposit) in the Heihe River region of the central corridor. These sites were dated to the late Machang (4100–4000 bp ), Xichengyi (4000–3700 bp ), Qijia (4000–3600 bp ) and Siba (3700–3400 bp ) cultures. After comparing with published lead (Pb) isotopic data from other possible Cu deposits in north-west China, the results show that the Cu ores collected from the Early Bronze Age sites were most likely derived from the adjacent Beishan Cu deposit. More intriguingly, for the first time in Hexi Corridor, a dozen Cu ores were discovered containing highly radiogenic Pb. Though fundamentally different from those in the Central Plains, they illustrate a possible new type of Cu used in Bronze Age western China, and the first-hand materials are significant for further understanding the provenance of raw metals for metallurgical production in the prehistoric Hexi Corridor.     

微区位研究的新思维

论文从区位尺度观、空间关联、行为观、空间竞争、平衡最优理论等五个方面探讨微观区位研究的新视角、新思维。指出微区位研究与传统的区位研究的区位选择主体、空间范围、影响因素都有很大不同。区位选择对象与周边环境的空间关联制约微观环境下的区位空间类型。经营者与消费者的行为、文化心理对微区位选择构成重要影响。市场的空间竞争关系到布局对象的生存与发展。微区位追求的目标应当是经营者的最大利润与消费者的最大剩余效用之间的平衡,最大限度利用空间外部效果对微区位选择具有重要意义。     

甘肃出土糟朽木器的形态与结构分析

甘肃出土木器依据形态与结构划分,属于典型的糟朽木器类型,材质外观特征与特性明显。制作材质鉴定表明,基本类型有①松科云杉;②松科冷杉;③柏科圆柏。通过对糟朽木器形态类型、结构属性、影响因素及发生改变原因剖析,指出了糟朽木器材质在经历了第一阶段的转折性根本改变后（含水率远低于纤维饱和点）,即将面临第二阶段的转折性根本变化（含水率略高或接近于平衡含水率）,而这一阶段的改变结果对器物将是毁灭性的;为了避免出土器物在短期内形态发生剧变,运用生物切片、扫描电镜分析技术对木质纤维显微结构进行了观察和研究,研究结果与结构病害腐变结果相吻合。选取与糟朽器物同期考古出土的糟朽棺板木作为分析对象,分别对其化学成分、容积重、含水率以及力学性能进行了实验测试,测得糟朽木器降解损失超过50%,含水率约为10.5%,力学强度指标与正常材质相比,均有明显的下降,且相对差异较大,最大约为正常木材强度的60%。对比分析结果,得出了结论：①糟朽木器的形态与结构状况与实验生物切片分析、电镜显微结构观察和研究结果相吻合,同时材质成分、容积重与力学性能测定结果为上述分析结果提供了有力的数据支撑;②致使糟朽木器形态和结构发生改变的主要因素是胎木含水率,其值是非恒定的并随外部环境而改变,因此含水率可用于反映糟朽木器的材质特性;③纤维饱和点与平衡含水率是影响、衡量和评估糟朽木器形态与结构的两个重要的物理参数;④鉴于糟朽木器的材质特性,后期保存应尽量避免与水分的直接接触,需要严格控制其胎木的含水率,且维持恒定、稳定的保存环境,这点对后期糟朽木器的保存是非常重要的