Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence

Quartz has been the main mineral used for optically stimulated luminescence (OSL) dating of sediments over the last decade. The quartz OSL signal, however, has been shown to saturate at relatively low doses of ～200–400 Gy, making it difficult to be used for dating beyond about 200 thou-sand years (ka), unless the environmental dose rate is low. The infrared stimulated luminescence (IRSL) from feldspars has been shown to continue to grow to higher dose levels than quartz OSL. The application of IRSL dating of feldspars, however, has long been hampered by the anomalous fading effect. Recent progress in understanding anomalous fading of the infrared stimulated luminescence (IRSL) signals in potassium-feldspar has led to the development of post-IR IRSL (pIRIR) protocols and also a multiple elevated temperature (MET) stimulation (MET-pIRIR) protocol. These procedures have raised the prospect of isolating a non-fading IRSL component for dating Quaternary deposits containing feldspars. In this study, we review the recent progress made on (1) overcoming anomalous fading of feldspar, and (2) the development of pIRIR dating techniques for feldspar. The potential and problems associated with these methods are discussed.     

Leonardo Bruni and humanist historiography

Leonardo Bruni: History of the Florentine People. Edited by James Hankins, Volume 1 (Cambridge, MA: Harvard University Press, 2001 and 2004), v–xxiv?+?520 pp. $29.95/£19.95/€27.70 cloth.

Leonardo Bruni: History of the Florentine People. Edited by James Hankins, Volume 2 (Cambridge, MA: Harvard University Press, 2004), xiii?+?584 pp. $29.95/£19.95/€27.70 cloth.     

A Family of Location Models for Multiple-Type Discrete Dispersion

One of the defining objectives in location science is to maximize dispersion. Facilities can be dispersed for a wide variety of purposes, including attempts to optimize competitive market advantage, disperse negative impacts, and optimize security. With one exception, all of the extant dispersion models consider only one type of facility, and ignore problems where multiple types of facilities must be located. We provide examples where multiple-type dispersion is appropriate and based on this develop a general class of facility location problems that optimize multiple-type dispersion. This family of models expands on the previously formulated definitions of dispersion for single types of facilities, by allowing the interactions among different types of facilities to determine the extent to which they will be spatially dispersed. We provide a set of integer-linear programming formulations for the principal models of this class and suggest a methodology for intelligent constraint elimination. We also present results of solving a range of multiple-type dispersion problems optimally and demonstrate that only the smallest versions of such problems can be solved in a reasonable amount of computer time using general-purpose optimization software. We conclude that the family of multiple-type dispersion models provides a more comprehensive, flexible, and realistic framework for locating facilities where weighted distances should be maximized, when compared with the special case of locating only a single type of facility.     

Recovering social and cultural dynamics from plaster floors: chemical analyses at ancient Chunchucmil,Yucatan, Mexico

Phosphate analysis and trace metals analysis were used to determine activities that took place on plaster floors in domestic contexts at the ancient Maya site of Chunchucmil, Yucatan. Research on activities and the use of space contributes to an understanding of social relations within household groups as well as unforeseen patterns that structure refuse discard. The floors analyzed in this paper pertain to three structures in two neighboring houselots dating to the Early Classic (300–600 A.D.) period. Data from the chemical analyses were utilized in conjunction with associated architectural features and artifacts found on the floors. These three lines of information were interpreted with the help of models developed from ethnographic and ethnoarchaeological research. The results demonstrated functional differentiation of rooms within elaborate residences and suggested that front rooms were used to host visitors. The results also suggested that different types of debris were managed differently. Finally, chemical analyses suggest that non-elite Maya occasionally enacted rituals often restricted to elites.