Stability of IRSL signals from sedimentary K-feldspar samples

Recent work has identified IR stimulated luminescence signals at elevated temperature from both potassium- and sodium-rich feldspars that have much lower anomalous fading rates than the conventional signal measured using IR stimulation at 50°C. This paper examines the stability of these signals for potassium-rich sedimentary feldspars. We show that the natural post-IR IRSL (pIRIR) signal from a 3.6 Ma old sample is in apparent saturation on a laboratory generated dose response curve, i.e. it does not show detectable fading in nature although a low fading rate is observed on laboratory time scales. We show that the pIRIR signal has a greater thermal stability than the IRSL signal and that the trend in increasing thermal stability is mirrored by a decreasing fading rate. We also investigate the effect of preheat temperature and IR stimulation power on the decay shape and conclude that the data can be explained in terms of either a single- or multiple-trap model. We present evidence that may suggest that at least part of pIRIR signal is derived from a high temperature trap (∼550°C thermoluminescence (TL) peak), although again the data can also be explained in terms of a single-trap model. Finally, we present dose response curves and characteristic curvature constants (D₀) values for various IRSL signals and conclude that the more stable signals saturate more quickly than the less stable signals and that the initial and final signals saturate at approximately the same level.     

ERNST CASSIRER,MARTIN HEIDEGGER,AND THE LEGACY OF DAVOS

In 1929 Ernst Cassirer and Martin Heidegger participated in a momentous debate in Davos, Switzerland, which is widely held to have marked an important division in twentieth‐century European thought. Peter E. Gordon's recent book, Continental Divide: Heidegger, Cassirer, Davos, centers on this debate between these two philosophical adversaries. In his book Gordon examines the background of the debate, the issues that distinguished the respective positions of Cassirer and Heidegger, and the legacy of the debate for later decades. Throughout the work, Gordon concisely portrays the source of disagreement between the two adversaries in terms of a difference between Cassirer's philosophy of spontaneity and Heidegger's philosophy of receptivity, or of “thrownness” (Geworfenheit), into a situation that finite human beings can never hope to master. Although it recognizes that this work provides an important contribution to our understanding of the Davos debate and to twentieth‐century European thought, this review essay subjects Gordon's manner of interpreting the distinction between Cassirer and Heidegger to critical scrutiny. Its purpose is to examine the possibility that important aspects of the debate, which do not conform to the grid imposed by Gordon's interpretation, might have been set aside in the context of his analysis.     

Demonstration Survey of Prehistoric Reef‐Net Sites with Sidescan Sonar,near Becher Bay,British Columbia,Canada

Sidescan sonar was deployed in challenging shallow‐water conditions to demonstrate the potential for recording anchor‐stones left on the sea‐bed from prehistoric fishing operations. In less than three hours the survey successfully mapped a reef‐net site originally recorded in 1985 by diving archaeologists over many hours. In addition, 8 km of coastline were surveyed, resulting in the discovery and recording of one new underwater reef‐net site. Our understanding of evolving subsistence practices of the Straits Salish, for whom reef‐net fishing was a critical activity, may be enhanced by this survey method which provides cost‐effective access to data not otherwise being recorded. © 2011 The Authors     

Learning through Upheaval: Strategies for Analyzing and Construing Emerging Sociopolitical Transformations in the Middle East

The irreducible complexity and singular unpredictability of the upheavals that have roiled the Middle East since December 2010 challenge analysts—from university students to policymakers—to grapple with irresolvable questions; this, rather than analysts' superimposing their own visions of what might constitute the upheavals' driving forces, and what will, or should be the outcomes of the regional turmoil. Drawing on strategies gleaned from teaching about the Arab uprisings, this article asserts that the uprisings may be collectively read as comprising a text that contains signs of indeterminacy pointing to many possible meanings and sources of meanings. Focus is placed on those signs that embody the differing discourses through which the Middle East upheavals are, have been, or can be represented and assessed; and the fluid, multidimensional forms of political identity that have contributed to the upheavals, and are being further reshaped, in their wake. By reading these signs with intellectual openness and humility, interpreters can achieve greater insight into the profoundly contingent and unforeseeable dynamics at work across the region.     

Pottery firing temperatures: a new method for determining the firing temperature of ceramics and burnt clay

A new method for determining the maximum firing temperature of ceramics and burnt clay is presented. The technique relies on measuring the magnetic susceptibility on a step-wise re-fired sample. The validity of the method has been tested by determining firing temperatures of two sets of clay samples fired at temperatures ranging from 400 to 1000 °C. Aliquots of the same samples have been studied petrographically by optical microscopy on thin sections and analyzed by powder X-ray diffraction in order to monitor structural and mineralogical changes as a function of temperature. The method is demonstrated on samples from four geographically widely different sites and it is applied to a larger set of ceramics of Late (ca. AD 900–AD 1450) and Inca (ca. AD 1480–AD 1532) periods from the Northwestern Argentine region, dating to a limited period of time prior to the fall of the Inca Empire. The method is shown to be a powerful tool in revealing archaeological information about the change in firing technologies in the pre-Hispanic societies in the Andean area through time.     

Oxygen Isotopes and Human Residential Mobility in Central Western Argentina

Stable oxygen isotopes (δ¹⁸O) from human bone apatite from central western Argentina (30º–37ºS latitude) were analysed to understand changes in human residential mobility during the Late Holocene. This region contains evidence for the use of domesticated plants over the last 2000 years (Zea mays, Cucurbita sp. and Phaseolus sp., among others), and previous models of prehistoric occupation have suggested a distinct change in mobility and population movement associated with their incorporation. The importance of these domesticates also seems to have varied geographically, being greater in the northern part of the region and declining as one moves south toward the limit with Patagonia. Expectations about patterns of residential mobility have varied accordingly. To better evaluate these models, we analysed carbonate δ¹⁸O from the bone apatite of 71 individuals with radiocarbon dates spanning the last 6000 years. Given the existing evidence, we expected to see temporal and geographic differences in their oxygen isotope values associated with changes in residential mobility and the incorporation of different sources of drinking water available within the region. These expectations were not met. Significant variations were seen across all samples compared, both temporal and geographic, with no discernible differences among them. The data suggest that populations throughout the area were all highly mobile, and that this did not change with the incorporation of domesticates. Copyright © 2011 John Wiley & Sons, Ltd.     

An Analysis of Makovsky's Border Proposal in Light of Palestinian Needs

The border proposal of David Makovsky, who, served as an advisor to Martin Indyk during the recent Israeli‐Palestinian peace talks, is analyzed from the standpoint of viable contiguity — the degree to which the border, particularly where there is Israeli annexation of settlement blocs, offers provision for access, living space, and transportation infrastructure for the Palestinian population in adjacent areas. While at some locales his proposed border improves contiguity for Palestinians compared with the current situation unilaterally imposed by Israel, more attention needs to be given to the ways it would adversely affect the quality of life of the Palestinian population in the cities and villages adjacent to those settlement blocs. This leads to the suggestion that a more comprehensive solution to border issues will feature the establishment of joint economic zones and binational administrative authorities, which can manage the entanglement of roads and populations in ways that will maximize the potential for economic development.