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21.
The strategic advantages of being the first entrant into a market have been discussed extensively. This paper presents examples of markets in which there is no first entry advantage. Rather, the later entrant always has an advantage even when both deploy equal resources. The necessary conditions for the occurrence of this first entry paradox are presented.  相似文献   
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Despite the importance of the Clovis–Folsom transition for understanding the history of western North America, its spatiotemporal dynamics remains unclear. Here we report a three-part study in which we investigated the transition using radiocarbon dates from Clovis and Folsom sites. In the first part of the study, we used dates from Folsom site-phases to determine when and where Folsom originated. In the second part of the study, we employed Clovis and Folsom dates in analyses designed to determine whether Folsom spread via demic diffusion or cultural diffusion. In the third part of the study we investigated the velocity of the Clovis–Folsom transition. The analyses suggest that Folsom first appeared around 12,800 calBP in the northern High Plains and spread north and south from there. They also suggest that the spread of Folsom was, at least in part, the result of population expansion. In addition, the analyses indicate that the spread of Folsom was relatively fast for a prehistoric diffusion but well below the maximum velocity that has been estimated for such events. These findings, in turn, have implications for the hypotheses that have been put forward to explain the Clovis–Folsom transition. They refute the idea that the Clovis–Folsom transition resulted from an extraterrestrial impact over northern North America at 12,900 ± 100 calBP but are consistent with the alternative proposal that the transition was a response to climate-driven environmental change.  相似文献   
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Rock art researchers throughout the world have explicitly or implicitly invoked ritual as an activity associated with the production of rock art but the articulation between the structure and composition of rock art assemblages and ritual behaviour remains poorly understood. Anthropologist, Roy Rappaport (1999) argued that all ritual, whatever the content or focus, has a universal structure. We review this proposition in the context of ritual studies and propose a method aimed at assessing the potential for identifying ritual structure in rock art assemblages. We discuss an archaeological analysis undertaken on the rock art assemblages in arid Central Australia, which aimed at distinguishing such a ritual structure among engraved assemblages, likely to have a Pleistocene origin, as well as more recent painted, stencilled and drawn assemblages. This analysis, despite its limitations, provides the foundation for developing a model, which will enhance the understanding of the relationship between the production of rock art and ritual.  相似文献   
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Researchers use a variety of target materials, and sometimes combinations of materials, in their archaeological experiments to examine thrust-spear or projectile penetration, impact angle, durability, and other issues involving prehistoric hunting weaponry. This variety of target materials is beneficial to archaeological science in several ways, but it may also hinder the comparison of results because many of these target materials do not necessarily share similar physical properties. Here, we assess the penetration properties of four different target materials—store-bought meat, clay, and two types of gelatin—via static penetration tests of a modern broadhead-tipped arrow and a stone-tipped projectile attached to an Instron Universal Materials Tester. Our analyses of load-deflection curves, peak load, and work energy demonstrate how the four target materials are similar in some ways but different in others, which suggests that researchers may strategically employ one or several depending on the question asked or hypothesis tested.  相似文献   
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We show that Steele’s (2010) criticisms of Hamilton and Buchanan (2007) and Buchanan et al. (2008) do not hold water and demonstrate that his re-analyses of Hamilton and Buchanan’s (2007) and Buchanan et al'.s (2008) datasets are flawed. In the process, we highlight some important issues for researchers interested in using radiocarbon dates to reconstruct population movements and demography. Most notably, we explain why OLS regression is preferable to RMA regression when estimating diffusion velocity, and demonstrate that the summed probability distributions yielded by CalPal are more reliable as guides to past demographic change than those produced by Calib and OxCal.  相似文献   
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The initial colonization of North America remains a controversial topic. There is widespread agreement that Clovis and related cultures of the Early Paleoindian period (∼11,500–10,500 BP) represent the first well-documented indications of human occupation, but considerable differences of opinion exist regarding the origins of these cultures. Here, we report the results of a study in which data from a continent-wide sample of Early Paleoindian projectile points were analyzed with cladistic methods in order to assess competing models of colonization as well as several alternative explanations for the variation among the points, including adaptation to local environmental circumstances, cultural diffusion, and site type effects. The analyses suggest that a rapidly migrating population produced the Early Paleoindian projectile point assemblages. They also suggest that the population in question is unlikely to have entered North America from either the Isthmus of Panama or the Midatlantic region. According to the analyses, the Early Paleoindians are more likely to have entered North America via either the ice-free corridor between the Laurentide and Cordilleran ice sheets that is hypothesized to have opened around 12,000 BP, or the Northwest Coast.  相似文献   
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The 1951 Festival of Britain has long been seen as both a key turning point in the country’s post-war history and an event which was delivered, by Clement Attlee’s Labour Government, in the face of formidable political (and media) opposition. This article considers the Festival’s status as a pivotal moment in modern British history but focuses primarily on the Conservative Party’s approach to the project. In doing so, its draws on previously neglected evidence to suggest that successive works on the subject have greatly exaggerated the extent to which the festivities were the subject of partisan campaigning and political contention.  相似文献   
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