Comparison of the conductivities of pure AgBr and AgBr doped with varying concentrations of CdBr2 in the intrinsic temperature range determines the concentration of defects and the mobilities of silver vacancies and interstitial ions. These quantities have been measured as a function of pressure up to 8000 kg/cm2 at three temperatures below 300°C. From the pressure variation of the defect concentration, the molar volume ΔV* of the imperfections is found to be 16 cc/mole below 300°C. An analysis of the pressure variation of the mobilities u0 and u□ of the Ag+ interstitial ions and of the silver vacancies, respectively, indicates that the free volumes associated with their motions are 2.7 cc/mole and 7.4 cc/mole. The value of ΔV*=16 cc/mole is consistent with the Frenkel disorder type. At temperatures above 300°C, however, the observed value of |∂ lnσ/∂p| is larger than expected from a simple Frenkel disorder type. An effort is made to interpret this behavior in terms of mixed Frenkel and Schottky defects.

Photoconductive (PC) and photoelectromagnetic (PEM) effects have been observed in p-type InSb single crystals of high purity at nOK (extrinsic range) and 301°K (intrinsic range). Because of the large electron mobilities in InSb, and because the variation of the PEM response with magnetic field was found to be strongly dependent on surface treatment, it was necessary to develop a new theoretical model to describe the PEM effect, permitting the evaluation of bulk lifetime and both electron and hole mobilities. In addition, the model affords an interpretation of Hall and magnetoresistance effects in intrinsic InSb. When the PEM effect is analyzed using impurity or thermal scattering, assuming Boltzmann statistics, the result does not fit the data so well as the simple model presented here.

Over the last several decades, scholars have reexamined the importance of spatiality to human life and argued that space produces and is produced by social relationships. This article adopts such a relational understanding of space to examine the production of eco-archaeological tourist attractions in the eastern Yucatan Peninsula of Mexico and beyond. Specifically, this article considers the common practice of declaring areas encompassing archaeological sites as nature parks or wildernesses. Because so many sites are currently located in areas that have been deemed natural, scholars cannot fully understand the contemporary production of archaeological space without examining the historic production of nature and wilderness. Using the Xcaret Eco-Archaeological Park and the Otoch Ma'ax Yetel Kooh, this article shows that although the creation of archaeological nature parks frequently harms indigenous peoples through processes of spatial colonization and spatial commodification, the production of such spaces can also enable and empower local, marginalized groups. [wilderness, political authority social inequality, community archaeology, the Maya] RESUMEN En lasúltimas décadas, investigadores han reexaminado la importancia de la espacialidad a la vida humana y argumentado que el espacio produce y es producido por las relaciones sociales. Este artículo adopta tal entendimiento relacional del espacio para examinar la producción de atracciones turísticas eco-arqueológicas en el oriente de la península de Yucatán de México y más allá. Específicamente, este artículo considera la práctica común de declararáreas que abarcan sitios arqueológicos como parques de naturaleza o selva. Debido a que muchos sitios están actualmente localizados enáreas que han sido consideradas naturales, investigadores no pueden entender completamente la producción contemporánea de espacio arqueológico sin examinar la producción histórica de la naturaleza y la selva. Usando el Xcaret Eco-Archaelogical Park y el Otoch Ma'ax Yetel Kooh, este artículo muestra que, aunque la creación de parques naturales arqueológicos afecta frecuentemente a los pueblos Indígenas a través de procesos de colonización espacial y comodificación espacial, la producción de tales espacios puede también posibilitar y empoderar a grupos marginados locales. [selva, autoridad política, desigualdad social, arqueología de comunidad, los maya]

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