A simulation of the hydrothermal response to the Chesapeake Bay bolide impact

Groundwater more saline than seawater has been discovered in the tsunami breccia of the Chesapeake Bay Impact Crater. One hypothesis for the origin of this brine is that it may be a liquid residual following steam separation in a hydrothermal system that evolved following the impact. Initial scoping calculations have demonstrated that it is feasible such a residual brine could have remained in the crater for the 35 million years since impact. Numerical simulations have been conducted using the code HYDROTHERM to test whether or not conditions were suitable in the millennia following the impact for the development of a steam phase in the hydrothermal system. Hydraulic and thermal parameters were estimated for the bedrock underlying the crater and the tsunami breccia that fills the crater. Simulations at three different breccia permeabilities suggest that the type of hydrothermal system that might have developed would have been very sensitive to the permeability. A relatively low breccia permeability (1 × 10^?16 m²) results in a system partitioned into a shallow water phase and a deeper superheated steam phase. A moderate breccia permeability (1 × 10^?15 m²) results in a system with regionally extensive multiphase conditions. A relatively high breccia permeability (1 × 10^?14 m²) results in a system dominated by warm‐water convection cells. The permeability of the crater breccia could have had any of these values at given depths and times during the hydrothermal system evolution as the sediments compacted. The simulations were not able to take into account transient permeability conditions, or equations of state that account for the salt content of seawater. Results suggest, however, that it is likely that steam conditions existed at some time in the system following impact, providing additional evidence that is consistent with a hydrothermal origin for the crater brine.     

基于集群理论的佛山禅城陶瓷产业转移时空演替机理研究

产业转移是一国或地区经济发展过程中的一种必然现象,随着我国珠江三角洲地区经济发展,产业结构升级已成为目前经济发展中重要课题。而产业转移是产业结构调整地域化的载体,是产业结构调整与升级的基本表现形式。普遍的观点认为产业集群使产业产生区域粘性,阻碍产业转移。然而本文从集群发展与升级的角度,认为中国最大的建筑陶瓷产业基地-佛山禅城的陶瓷集群在形成、发展与升级过程中存在着产业的空间转移,并发现佛山禅城陶瓷业转移在陶瓷产业集群发展与升级两个阶段表现出明显不同的特点:前者为"蔓延式扩散"、后者为"跳跃式转移"。并对两个时段的陶瓷产业转移的机理进行剖析,结果表明:市场才是驱动陶瓷产业转移的主要动力,而政府只是起了助推作用。     

西方国家大学技术转移研究的进展和启示

技术、制度、文化和关系、尺度、调节是经济地理学理论构建的重要中介,也是当今"新经济地理学"理论建构争论的核心所在。大学作为技术创新的集中地,也是国家创新体系的组成部分之一,其在整个国家和地区的技术创新和转移中具有举足轻重的地位。大学技术转移的研究是近年来国外管理学、经济学和经济地理学研究的热点问题。文章通过总结国外大学技术转移研究的现状和发展趋势,结合国内的研究特点,给出了未来我国学者,特别是经济地理学者在大学技术转移的研究方面应该注意的问题,以便使得大学技术转移能在我国建设自主创新型国家的过程中发挥应有的作用。     

Experimental insights into alternative strategies of lithic heat treatment

Conditions in which thermal fractures occur are explored experimentally, and the results are used to assess heat treatment strategies. We conclude that no single ‘critical temperature’ for thermal fracturing or heat treatment can be specified for any particular raw material, as has so often been attempted, because threshold temperatures exist in relationship to specimen sizes. Our experiments show that smaller specimens are resilient to greater ranges of temperature fluctuations than larger ones, and that by manufacturing/selecting specimens of smaller sizes there is more potential to heat them rapidly and to higher temperatures without producing thermal fractures. We hypothesize a continuum of heat treating strategies between a ‘slow and steady’ strategy, which has overwhelmingly dominated past experimental designs, and a ‘fast’ strategy, which has received much less attention. The paper discusses the economic and technological contexts to which different heat treating strategies might be suited.     

The international transfer of creative industries as a policy idea

This article examines the transfer of creative industries as a policy idea to Lithuania. Tracing the stages of the transfer and analysing its consequences in the local cultural policy field, this paper argues for the importance of studying cultural policy process. The findings reveal that the process of the international transfer of creative industries mattered, because it generated wider transformations in cultural policy field by having ambiguous effects on local power relations. The policy idea of creative industries opened the cultural policy field to new actors. As a result, competition for scarce state funding increased, but cultural organisations gained access to the European Union structural funds. In all, creative industries as a policy idea significantly transformed Lithuanian state cultural policy, in that it led to a reassessment of both the practices and identities of cultural organisations.     

A Post-Imperial Cold War Paradox: The Anglo-Nigerian Defence Agreement 1958–62

As the recent and current French military interventions in West Africa have illustrated, France succeeded in establishing long-lasting security relationships with its former colonies during the transfer of power. In Britain’s case, by contrast, decolonisation was largely followed by military withdrawal. This was not, however, for lack of trying. The episode of the Anglo-Nigerian Defence Agreement clearly illustrates that Britain, driven by its global cold war military strategy, wanted to secure its long-term interests in sub-Saharan Africa. The agreement was first welcomed by the Nigerian elite, which was not only anglophile and anti-communist, but also wanted British military assistance for the build-up of its armed forces. Yet, in Nigeria, the defence pact was faced with mounting opposition, and decried as a neo-colonial scheme. Whereas this first allowed the Nigerian leaders to extract strategic, material and financial concessions from Britain, it eventually led to the abrogation of the agreement. Paradoxically, Britain’s cold war grand strategy created not only the need for the agreement, but also to abrogate it. In the increasingly global East-West struggle, the agreement was strategically desirable, but politically counterproductive.     

Grabbing Land for Equitable Development? Reengineering Land Dispossession through Securitising Land Development Rights in Chongqing

This article examines the securitisation of land development rights under the dipiao scheme in Chongqing, China. It argues that this instrument is based on the dispossession and exploitation of rural households but these unequal relations have been concealed and naturalised through the complex geographies and temporalities of dispossessory arrangements, financing mechanisms and discursive tactics. By overcoming political barriers to land commodification and dispossession in this way, the Chongqing government has expanded the frontier of commodifiable land and sustained a land‐based, urban‐centric and debt‐financed accumulation. Instead of narrowing the urban–rural divide, this instrument reproduces and solidifies it. On this basis, the article argues that conceptual and political innovations for inclusive and equitable development needs to shift the attention from land to people.     

New Light on the Medieval Gough Map of Britain

Remarkably little is known about the earliest surviving separate-sheet medieval map of Britain that takes its name from its former owner, Richard Gough (1735–1809), and that has been variously dated to between 1300 and 1400, and later. It presents a sophisticated cartographical image at a time when detailed maps of individual regions were almost unknown in Europe, yet nothing is agreed about its possible origins, context (ecclesiastical or secular), or why and how it was compiled. In the belief that historical interpretation has to stem from an intimate knowledge of the map as artefact—the state of the parchment, nature of the inks, palaeography—as well as image, an informal study group of historians and scientists (the Gough Map Panel) was convened in 2012 to examine the map through high resolution digital reproduction, hyperspectral analysis, three-dimensional analysis and Raman pigment analysis. Although the study is still ongoing, much that is new has been discovered, notably about the way features were marked on the map, Gough’s application to the map of a damaging reagent to render place-names readable, and the extent to which the original map (now dated to c.1400), although never completed, was nonetheless reworked on two different occasions in the fifteenth century, effectively creating two further maps. These and other findings are summarized here to encourage the further study of the map’s features that is needed before it can be fully understood.     

Episodic fluid flow within continental rift basins: some insights from field data and mathematical models of the Rhinegraben

Vitrinite reflectance data from a petroleum exploration well in the northern Upper Rhinegraben show an unusual vertical maturity trend. Above and below a 500 m thick marl layer the vitrinite reflectance levels are consistent with modern, conductive, geothermal gradients. Between about 1000 and 1500 m depth, however, vitrinite reflectance levels are significantly elevated (about 0.6%Ro). This anomaly cannot be explained with one‐dimensional conductive or conductive–convective heat transfer models, and thermal effects of sedimentation or igneous intrusion seem implausible for this geological setting. The thermal anomaly that formed this maturation anomaly must have been hydrothermal in origin, two‐dimensional in nature, and persisted long enough to elevate the vitrinite reflectance values within this marl unit, yet it must have dissipated before the thermal perturbation would have altered the organic matter below and above the unit. In this study, we propose that the vitrinite reflectance anomalies were caused by a transient thermal inversion induced by episodic, lateral flow of hot (130–160°C) groundwater along conductive fractures and bedding planes. Heat flow constraints suggest that fluids must have moved rapidly up a vertical feeder fault from a depth of at least 3.6 km before migrating laterally. To test this hypothesis, we present a suite of simple, idealized mathematical models of groundwater flow, heat transfer, thermal degradation of kerogen and vitrinite systematics to explore the episodic flow that could have produced the observed thermal anomaly. In these simulations, a single, horizontal aquifer is sandwiched between two less permeable units: the total dimensions of the vertical section model are 4 km thick by 10 km long. The top of the aquifer coincides with the position of the observed thermal maturity anomaly in the Rhinegraben. Boundary conditions along the left edge of this aquifer were varied through time to allow for the migration of hot fluids out into the basin. Inflow temperature, horizontal velocity, duration and frequency of flow and thickness of the aquifer were varied. We found that a thermal maturity anomaly could only be produced by a rather restrictive set of hydrothermal conditions. It was possible to produce the observed vitrinite reflectance anomaly by a single hydrothermal flow event of 130°C fluid migrating laterally into the aquifer at a rate of 1 m a^?1 for about 10 000 years. The anomaly is spatially confined to near the left edge of the basin, near the feeder fault. If the flow event lasted longer than 100 000 years, then the maturation anomaly disappeared as the lower confining unit approached steady‐state thermal conditions. It is possible that such an event occurred about 5 million years ago in response to increases in fault permeability associated with far field Alpine tectonism.     

Goats Mingling With Sheep? Professionalisation,Personalities, and Partnerships Between British Civil and Military Engineers,c.1837–1939

This article explores the entangled history of civil and military engineering from 1837 to 1939. Typically characterised in the historiography as a relationship marked by neglect and intransigence, it reveals a longstanding kinship between the two professions, built on the firm foundations of mutual interest and respect. Charting the formal and informal links between civil and military engineering in terms of knowledge, recruitment, and education, this article argues that the relationship, while often characterised by tensions and disagreements, represented a process of re-negotiation and renewal to meet new challenges and altered contexts.