Possible isotopic fractionation of argon in source obsidians and archeological artifacts from Kulkuletti, Ethiopia

Despite uniform geochemistry ⁴⁰Ar/³⁹Ar ages of 0.6, 1.25, and 1.3 Ma on obsidians from a source flow (Worja) and from archeological artifacts at the sites of Kulkuletti (near Gademotta, Ethiopia) have been interpreted to suggest that they derive from different source flows of different ages. A further suggestion is that the magmatic source of the obsidian flows was chemically homogeneous between 1.3 Ma and 0.6 Ma. Chemical analysis of these obsidians indeed suggests that they derive from a single flow. Reexamination of the argon isotopic data reveals that argon isotopes may have been fractionated within the flow, so that the assumption of an atmospheric ⁴⁰Ar/³⁶Ar ratio of 295.5 is inappropriate to use for computing ages. Three groups of data are apparent, and internally all yield ages near 1.3 Ma if the intercept value for ⁴⁰Ar/³⁶Ar from an isotope correlation plot is used for computation instead of using the atmospheric ratio. The Soret thermal diffusion effect provides a possible mechanism of fractionation of argon within the obsidian flow that is of approximately the right magnitude to explain the observations by in-diffusion of already fractionated atmospheric argon.     

Labour Migration, Neoliberalism and Ethno-politics in the New Europe: The Latvian Case

Abstract:  The accession of the new European Union (EU) member states of Eastern Europe has highlighted ambivalence towards migration within the older member states. That same ambivalence has been less frequently discussed in the new. The former Soviet republic of Latvia serves as a case study of a new member state facing intensified pressure to accept inward migration to meet labour shortages, in part, a consequence of EU accession. Confounding appropriate political and policy responses is the sensitive issue of "ethnic balance", a troubled "legacy" of Latvian history. This has been characterised as comprising a "regime of discrimination" against the Russian-speaking minority. In the context of changes in the global migratory landscape, the potential for a renewed of regime of discrimination is emerging, based on an ethno-politics that has wider European resonance.     

The significance of the Carolingian advocate

This article argues that ninth-century advocates in the Frankish world deserve more attention than they have received. Exploring some of the wealth of relevant evidence, it reviews and critiques both current historiographical approaches to the issue. Instead of considering Carolingian advocates as largely a by-product of the ecclesiastical immunity, or viewing advocacy as a Trojan horse for a subsequent establishment of lordship over monasteries, the article proposes a reading of ninth-century advocacy as intimately linked with wider Carolingian reform, particularly an interest in promoting formal judicial procedure.     

Phylogeographic analysis of barley DNA as evidence for the spread of Neolithic agriculture through Europe

Results of analyses of the photoperiod response gene (PPD-H1) and simple sequence repeats (SSRs) in modern landraces of cultivated barley were used as evidence for the mechanism of agricultural spread in Neolithic Europe. In particular, we explored the usefulness of considering adaptive genes as indicators of past selective pressures acting on crops, during their spread through Europe. In some areas, such as the Alpine region, Britain and Scandinavia, we have evidence to suggest that the adaptation of crops to certain climatic conditions may have contributed to the timing of agricultural spread. At the northern fringes of Europe, and in higher altitude locations in central Europe, the introduction of more suitably adapted cereals may have facilitated successful agriculture to trigger agricultural expansion. This research opens up the possibility of investigating other genetic adaptations to climate, which would permit a fuller evaluation of the relative contributions of climate/crop and forager/farmer interactions in the process of agricultural spread.     

INTRODUCTION: PROCESSES OF CHANGE IN URBAN SYSTEMS*

ABSTRACT The twenty‐first century will be one of intensified urbanization, on a scale never before experienced. How do urban systems and individual cities change and develop? The social sciences have many different approaches to analyzing the economic, social, and spatial dimensions of urban change. We inventory some of these approaches and their implications for public policy toward cities, urban change, and economic development.