THE EFFECTS OF ZONING IN SPATIAL COMPETITION

ABSTRACT This paper considers a location model to illustrate the effect of zoning on competition. A planner is in charge of designing a city in a circular space where firms and consumers are located on different sides. With this type of market configuration, equilibrium in location under concave transport costs is proved. Then, a welfare function with different weights attached to consumer and firm surpluses is introduced to highlight zoning regulation as an influential competition policy tool. Depending on the regulator's political profiles and the demand, it is shown that zoning can lead to strong, weak, or moderate competition.     

Three-dimensional cranial shape analyses and gene flow in North Africa during the Middle to Late Holocene

Archaeological evidence shows that populations used to transverse the Sahara Desert throughout the Holocene despite the extreme temperatures and the rough physical terrain. The current paper examines whether the desert inhibited extended gene flow among populations by means of cranial morphology as captured by geometric morphometrics. The examined populations include the Garamantes, a group centered in Southwest Libya and largely controlling trans-Saharan trade, and various Egyptian, Tunisian and Sudanese groups dating to the Middle and Late Holocene. The results showed that most inter-population comparisons were statistically significant and therefore all populations appear more or less distant to each other. The Mahalanobis biodistance measure identified four clusters. The first consists of the Garamantes alone, the second includes the populations from Kerma and Gizeh, the third includes the Badari and Naqada, while the fourth consists of the samples from Algeria, Carthago, Soleb and Alexandria. Moreover, the distance of the Garamantes to their neighbors was significantly high and the population appeared to be an outlier. This is attributed to the location of the Garamantes at the core of the desert, indicating that, despite the archaeological evidence, the Sahara Desert posed important limitations to gene flow between the Garamantes and other North African populations.     

Husbandry practices and livestock dung at the Numidian site of Althiburos (el Médéina,Kef Governorate,northern Tunisia): the phytolith and spherulite evidence

Recent excavations at Althiburos, northern Tunisia, have shown the existence of permanent pre-roman occupations in the central area of the urban settlement. Significantly, the site has been found to contain one of the most complete Numidian sequences, spanning from the Early Numidian (at least from the 10th–9th century BC) to its final stage. Research at the site addresses questions related to the identification of settlement patterns at this time.The combined study of phytoliths and spherulites recovered from well defined archeological contexts at the site have provided new data for identifying husbandry activities carried out by the ancient Numidian populations. The results show that there is abundant evidence for both cooking and processing cereals, primarily from common or bread wheat (Triticum aestivum). Also significantly, was the abundance of faecal spherulites in certain areas of the site, indicative of dung accumulation. The correlation between large amounts of spherulites and rich phytolith sediments in specific contexts, suggested that grasses were brought to the site or consumed offsite and deposited onsite as livestock dung or dung-products. The identification of dung accumulations in the site raises questions about the diversity of economic practices developed by Protohistoric communities in northern Africa. Future research questions regarding such dung rich layers will also be examined.     

Chemical analyses of the earliest pigment residues from the uttermost part of the planet (Beagle Channel region,Tierra del Fuego,Southern South America)

This paper presents the results of chemical analyses of the organic and inorganic fractions of pigment residues found in three archaeological sites located in the Beagle Channel region, Tierra del Fuego, Southern South America. Twenty-one archaeological samples have been analysed through XRD, SEM–EDX, FT-IR and GC–MS in order to characterise their inorganic colouring components and to search for the presence of organic substances used as binders. Lipids found in some samples are considered as potential binders. These organic components are compared to those found in archaeological sediment samples from the same layers where the pigments have been found, in order to search for potential taphonomic contaminations of the latter by the former. Results show that such contaminations are unlikely, hence the lipid contents are deemed of anthropic origin. The pigment sample results are also compared to data from analyses of natural sediment samples collected in several localities of the Beagle Channel in order to search for potential natural pigment sources. Results show that organic and inorganic components of these sediments are not the same than those present in the archaeological pigment samples, hence the pigment raw material sources have not been yet located. All these data provide for the first time evidence of the existence of ancient activities of pigment sourcing and paint preparation with organic binders which range from 6000 BP to 1900 BP in the southernmost region of the planet.     

Raw stone material supply for Upper Pleistocene settlements in Sierra de Atapuerca (Burgos,Spain): flint characterization using petrographic and geochemical techniques

Microscopy, mass spectrometry and X-ray diffraction methods were used to analyse 415 samples of natural and archaeological flint from Sierra de Atapuerca (Burgos, Spain) in order to define the different types from Neogene and Cretaceous formations in the study area, infer their genetic context and ascertain the supply sources used by hunter-gatherers who exploited this area in the Upper Pleistocene. A statistical classification model was also designed using linear discriminatory analysis and support vector machines which permitted the differentiation of the flint on an age basis.     

A metric study of three types of artificial cranial modification from north‐central Peru

Artificial cranial modification (ACM) involves the alteration of cranial vault shape by cultural means, and is performed during infancy while the cranial bones remain soft and malleable. The direction of normal cranial growth is altered through the application of external forces. In this study, three types of ACM from north‐central Peru (posterior flattening, bilobed and circumferential) were analysed using standard craniometric techniques. The aim was to determine the effects of these forms of ACM on craniofacial morphology, and the extent to which different types of ACM could be distinguished from one another and unmodified crania on the basis of these measurements. Significant differences between artificially modified and unmodified crania, and between different types of ACM, were demonstrated in cranial vault shape for all types. Significant differences in facial morphology were found only in the bilobed group compared with the unmodified crania. Canonical variates analysis (discriminant analysis) confirmed that major differences between modification types and unmodified crania were in measurements and angles of the cranial vault. While the results show some similarities to previous studies, they add to the variability in the patterns and extent of differences documented to date. It is suggested, based on these results and visual observations, that interpopulation variation in ACM within major modification categories may explain some of the variability in results between studies, an explanation which has previously received insufficient recognition but which remains to be tested since varied methodology between studies may also be a contributory factor. While previous studies have often sought to generalise about the effects of ACM, the examination of the differences between populations even within major ACM categories may offer new insight into cultural variation in modification techniques between populations and the nature of craniofacial development. Copyright © 2009 John Wiley & Sons, Ltd.     

Interpretative scenarios emerging from plant micro- and macroremains in the Iron Age site of Salut,Sultanate of Oman

The archaeobotanical research carried out in the Iron Age site of Salut (north Oman) gives insights on various interpretative scenarios: the ancient vegetation surrounding the site, oasis farming, and possible ritual practices. The landscape was dominated by dry shrublands with, among others, acacia, jujube and tamarisk that were exploited for obtaining timber and firewood. Agricultural practices mainly consisted of date palm, cereal and sesame cultivation. By comparing the datasets it was possible to assess that the date palm had various uses in this site: one hypothesis involves its offering in ceremonial practices. This third scenario suggests a new way of interpreting some of the plant remains in an archaeological site as Salut, a multipurpose site including a possibly cultic function.