Magnetization of Ancient Ceramics

The saturation magnetization σ of soft baked pottery appears to be determined during the firing process by transitions between the iron oxides magnetite, maghemite, hematite and perhaps goethite. The finding of large variations in σ motivated the design and construction of a ‘magnetization–gravitation’, or ‘MG’, balance for rapid non‐destructive magnetization measurements. The first results with this MG balance are presented: iso‐σ contours, typical histograms and correlations with colour features. Practical MG applications are summarized.     

Sarah and Her Sisters: Letters,Emotions, and Colonial Identities in the Early Modern Atlantic World

This article uses letters by indigenous converts to explore how early modern Moravian missions in the Atlantic imagined themselves as emotional communities. Moravian missions were the most successful Protestant mission enterprise in the Atlantic and established numerous missions across several empires and vastly different indigenous cultures. By comparing the letters from indigenous converts across the Atlantic rim (North America, Caribbean and Greenland) I argue that indigenous people used the medium of the written letter to participate in an imagined emotional community of Moravians while at the same time they negotiated inescapable social and gendered differences in very specific colonial contexts.     

Open Concepts as Crystallization Points and Enablers of Discursive Configurations: The Case of the Innovation Campus in the Netherlands

In this paper, we reflect on the role of concepts in spatial planning as reproductive devices of discursive configurations. In contrast to instrumentalist interpretations of spatial concepts, we start from the idea that spatial planning concepts are inherently political. Building on post-structuralist strands of thought, we discuss the theoretical concepts of “empty signifier” and “master signifier” and instead, after analysis, put forward “open concepts”, in order to grasp the richness of meanings and functions of seemingly vague concepts. This manoeuvre allows us to analyse the trajectory and performance of the spatial concept of the “innovation campus” in the Netherlands. This, in turn, opens the door to an analysis of planning concepts as crystallization points and enablers of discursive configurations. The Dutch innovation campus is shown to be a result of a confluence of various national and international discourses, an open concept, flexible enough to enable the continuation of the planning game within the familiar set of coordinates. Because of the particular set of expectations associated with the innovation campus, promising structural change, it is bound to produce disappointment.     

European Corridors as Carriers of Dynamic Agglomeration Externalities?

Transport corridors are viewed as a promising way forward in European Union (EU) transport policy, assumed to contribute positively to regional economic development. However, the validity of this assumption is not evident. The aim of this paper is to empirically test whether agglomeration economies in European transport corridor regions are positively related to indicators of regional economic development compared to regions outside the scope of corridors. The results build on the notion that the type of agglomeration economy in combination with the structure of the economy matters for prospects of structural economic growth in different regions. In this way, the analysis not only contributes to enhancing the empirical scrutiny of the corridor concept in EU transport policy, but also provides new insights into how corridors contribute to regional economic growth. We find only limited evidence for a corridor effect across European regions on productivity and employment growth externalities. Instead, we find a large degree of spatial heterogeneity interacting with corridors—a heterogeneity that has been little recognized in EU policies. We suggest that recent attention to place-based development strategies may accord well with the kinds of agglomeration effects related to corridor development observed in this study.     

Decreasing CO2 partial pressure triggered Mg–Fe–Ca carbonate formation in ancient Martian crust preserved in the ALH84001 Meteorite

We retrace hydrogeochemical processes leading to the formation of Mg–Fe–Ca carbonate concretions (first distinct carbonate population, FDCP) in Martian meteorite ALH84001 by generic hydrogeochemical equilibrium and mass transfer modeling. Our simple conceptual models assume isochemical equilibration of orthopyroxenite minerals with pure water at varying water‐to‐rock ratios, temperatures and CO₂ partial pressures. Modeled scenarios include CO₂ partial pressures ranging from 10.1325 to 0.0001 MPa at water‐to‐rock ratios between 4380 and 43.8 mol mol^?1 and different temperatures (278, 303 and 348 K) and enable the precipitation of Mg–Fe–Ca solid solution carbonate. Modeled range and trend of carbonate compositional variation from magnesio‐siderite (core) to magnesite (rim), and the precipitation of amorphous SiO₂ and magnetite coupled to magnesite‐rich carbonate are similar to measured compositional variation. The results of this study suggest that the early Martian subsurface had been exposed to a dynamic gas pressure regime with decreasing CO₂ partial pressure at low temperatures (approximately 1.0133 to 0.0001 MPa at 278 K or 6 to 0.0001 MPa at 303 K). Moderate water‐to‐rock ratios of ca. 438 mol mol^?1 and isochemical weathering of orthopyroxenite are additional key prerequisites for the formation of secondary phase assemblages similar to ALH84001’s ‘FDCP’. Outbursts of water and CO_2(g) from confined ground water in fractured orthopyroxenite rocks below an unstable CO₂ hydrate‐containing cryosphere provide adequate environments on the early Martian surface.     

Exploit or Protect Airport Regions from Urbanization? Assessment of Land-use Restrictions in Amsterdam-Schiphol

Airports are no longer only places for take-off and landing, but increasingly became economic nodes in the urban development of metropolitan areas. Though it is debatable to what extent aviation growth is a cause or effect of economic growth, the reciprocal relationship cannot be denied. Most past developments near airports have been spontaneous and haphazard, but recently regional planners have increasingly included an airport focus. Airport planning aims to find a balance between exploitation of the economic potential and protecting the airport area from congestion and urbanization. This article examines the effects of land-use restriction policies near Amsterdam Airport Schiphol. Within the Schiphol area, only airport-related companies are allowed to establish their business near the airport. These policies have been implemented since 1987, but their success or failure was never evaluated in depth. For the first time empirical results show that land-use restriction policies could ban most of the undesired businesses near the airport. However, despite varieties of implementation and interpretation of the testing, few differences in effects are found. This study shows that airport-relatedness testing is a typically Dutch planning instrument, but can also be useful for other international airports.     

Ancient Boats, Boat Timbers, and Locked Mortise-and-Tenon Joints from Bronze/Iron-Age Northern Vietnam

This paper describes two nautical discoveries buried c .2000 years ago in the Red River alluvial plain, northern Vietnam. One is part of a logboat with a series of empty mortise and locking-peg holes for plank attachment using loose rectangular tenons. The other, from an infant mortuary house, is a series of re-used 4-m-long timbers with exactly the same locked mortise-and-tenon technology. Both finds are interpreted as having belonged to river-boats like those shown on the sides of Heger 1 (Dong Son) bronze drums. Potentially-related technologies from the Mediterranean and China are also discussed.
© 2006 The Authors     

The Search for the 1871 Whaling Fleet of the Western Arctic: writing the final chapter

During 2015, the NOAA Office of National Marine Sanctuaries led a systematic seabed mapping survey along the Arctic coast of Alaska in search of whaling ships abandoned in 1871. The purpose of the expedition was to determine if wreckage from these abandoned ships was still present in the survey area, and, if so, to assess and document its location, status and condition. The project mapped approximately 50 km² of seabed using sidescan sonar and magnetometry and identified six sites that contained wreckage from at least two whaling ships. Magnetometry data also suggested that additional wreckage may be buried in the seabed.