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971.
Francis Ivanhoe Philip W Chu James A Bennyhoff 《International Journal of Osteoarchaeology》1998,8(3):135-179
A quantitative bioenvironmental study of cranioskeletal size has been made of a latitude-ordered sequence of 14 series of adult skeleton sets (N=305): the archaeological remains of aboriginal maritime peoples inhabiting the west coast of North America between southern California and the Arctic. Of eight osteometric parameters of cranioskeletal size developed, the most important are partial skeleton volume (PSK) and cranial capacity (CC); and the principal bone-affecting environmental factors are the northerly climate (CLIM2c), the reconstructed diet deficient in calcium and overabundant in animal foods and vitamin D (DIET3c), and demographic stress (DSg). Prior research has demonstrated that cranioskeletal size increases with geographical latitude and decreases under dietary calcioprivation and unphysiologically high birth rates. Upon linear multifactorial statistical analysis our main finding, limited to the Amerindian subsequence (n=11 series) from the Santa Barbara Channel, the San Francisco Bay Region and the Northwest Coast, is that PSK and CC vary in direct proportion to CLIM2c, and inversely with DIET3c and DSg. Controlling for the latter two osteoantitrophic factors, coastal Amerindian female PSK rises by 9% between 34 and 54°N latitude, CC by 5%; and the male incremental rates are somewhat higher, 13 and 10%, respectively. This newly discovered climate-dependent race cline, an example of Bergmann's Rule, is interpreted as factual evidence of a mid-Wisconsin or earlier arrival date for the first Palaeoindians. Cranioskeletal size of the very small (n=3 series) Western Eskimo subsequence approximates the northernmost values of the coastal Amerindian distribution. © 1998 John Wiley & Sons, Ltd. 相似文献
972.
973.
Peter M. Atkinson Sally E. German David A. Sear Michael J. Clark 《Geographical analysis》2003,35(1):58-82
The relations between riverbank erosion and geomorphological variables that are thought to control or influence erosion are commonly modelled using regression. For a given river, a single regression model might befitted to data on erosion and its geomorphological controls obtained along the river's length. However, it is likely that the influence of some variables may vary with geographical location (i.e., distance upstream). For this reason, the spatially stationary regression model should be replaced with a non‐stationary equivalent. Geographically weighted regression (GWR) is a suitable choice. In this paper, GWR is extended to predict the binary presence or absence of erosion via the logistic model. This extended model was applied to data obtained from historical archives and a spatially intensive field survey of a length of 42 km of the Afon Dyfi in West Wales. The model parameters and the residual deviance of the model varied greatly with distance upstream. The practical implication of the result is that different management practices should be implemented at different locations along the river. Thus, the approach presented allowed inference of spatially varying management practice as a consequence of spatially varying geomorphological process. 相似文献
974.
A classification of census enumeration districts has recently been added to the 1991 British Census 2% Sample of Anonymised Records (SAR). Through the use of multilevel modeling techniques, the area classification information on the SAR is used to investigate geographical differences in unemployment. Previous research has indicated that where a person lives can affect their propensity to unemployment. However, the understanding of these relationships are confounded by the reciprocal nature of the relationship between unemployment, housing, and geographical location. This paper examines the relative importance of the individual, the type of neighborhood of residence, and the local labor market in which one lives in explaining variations in unemployment risk. It also examines the role of housing tenure at an individual and contextual level in mediating this relationship. Two competing hypotheses are evaluated. The first is that local concentrations of unemployment are the result of the process of neighborhood selection. The other suggests there are contextual affects on unemployment risk, which may include access to job opportunities and “concentration effects.” The paper concludes that most neighborhood level variation in unemployment is due to housing market effects, particularly neighborhood selection. As well as offering insights into the relationship between unemployment and geographical location, this paper aims to demonstrate methodological innovations in the analysis of census microdata. In particular it shows how area classifications can be used in conjunction with microdata in a multilevel modeling framework, to get a better understanding of the role of individual and contextual factors in social processes. 相似文献
975.
976.
It has been difficult to infer behaviours related to anterior tooth use in fossil hominids owing to a lack of broad‐based comparative studies of the relationships between front tooth use and craniodental features in modern humans. In this study, we seek to establish such a neontological baseline by exploring aspects of craniodental form among populations of recent humans that are inferred to have differed in habitual levels of ingestive and paramasticatory processing using the incisors. Morphometric data are compared among samples from three human populations: Aleutian Islanders (n=25); Arikara from the Mobridge Site, SD (n=19); and a late Woodland Bluff group from Jersey County, IL (n=24). Data for various biomechanically relevant dimensions were collected using standard callipers, while three‐dimensional (3D) coordinate data for 28 cranial landmarks were recorded using a video‐based image analysis system. These data indicate that several aspects of cranial form thought to influence the efficiency of force production on the incisors differ among the examined groups, including the positions and size of the primary masticatory muscles and the position of the dentition. For most dimensions, the Aleut sample exhibits the most mechanically advantageous configuration, the Illinois Bluff group the least advantageous configuration, while the Arikara are intermediate in form. This pattern corresponds to differences in the intensity of incisor loading among these groups, as inferred from both ethnographic reports and incisor microwear data. These results, therefore, suggest that cranial form in humans varies with subsistence‐related differences in masticatory force production and that quantitative studies of masticatory system configuration may provide useful information for studies of hominid palaeobiology. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
977.
The simulation of Sea-ice in a coarse resolution ocean general circulation model is examined in Hudson Bay and surrounding waters. Sea-ice distribution and duration compared well to climatological values, although ice thickness is undersimulated as it is in other modelling work. In Hudson Bay ice thickness variation was dominated by the atmospheric forcing as shown by the symmetric response of ice thickness to warming and cooling scenarios. Below ice heat fluxes play a more significant role in Foxe Basin and Baffin Bay where they mitigate air-ice heat loss by as much as 40 percent, thus limiting ice thickness and duration. Below ice heat flux reduces by 23 percent for the region of study (Hudson Bay, Foxe Basin, Baffin Bay, and Labrador Sea) for a global 3°C cooling and increases by 9 percent for a 3°C global warming. This asymmetric response is attributed to the ocean's asymmetric response to warming and cooling scenarios. In so much as Hudson Bay is dominated by atmospheric forcing rather than under ice heat as these results indicate, coarse resolution models may be useful in assessing the impact of change. However the necessary reconfiguration of the model grid render results from Foxe Basin and Hudson Strait less credible. On étudie la simulation de glace marine dans un modèle de circulation océanique générale à faible résolution dans la baie d'Hudson et dans les eaux avoisinantes. La distribution et la durée de la glace marine correspondent bien aux valeurs climatologiques, bien que l'épaisseur de la glace soit sous-simulée comme c'est le cas dans d'autres travaux de modélisation. Dans la baie d'Hudson, la variation de l'epaisseur de la glace est dominée par le forçage atmosphérique, comme on peut le voir d'après la réponse symétrique de l'épaisseur de la glace suivant les scénarios de réchauffement et de refroidissement. Les flux de chaleur sous la glace jouent un rôle plus important dans le bassin de Foxe et la baie Baffin, où ils permettent une réduction des pertes de chaleur air-glace allant jusqu'à 40 pour cent, limitant ainsi l'épaisseur de la glace et la durée. Le flux de chaleur sous la glace diminue de 23 pour cent dans la région étudiée (baie d'Hudson, bassin de Foxe, baie Baffin et mer du Labrador) pour un refroidissement global de 3C et augmente de 9 pour cent pour un réchauffement global de 3C. On attribue cette réponse asymétrique à la réponse asymétrique de l'océan aux scénarios de refroidissement et de réchauffement. Dans la mesure où, comme l'indiquent ces résultats, la baie d'Hudson est dominée par le forçage atmosphérique plutôt que par la chaleur sous la glace, des modèles à faible résolution peuvent être utiles pour évaluer l'impact des changements. Cependant, la reconfiguration nécessaire de la grille du modèle atténue la crédibilité des résultats obtenus dans le Bassin de Foxe et le détroit d'Hudson. 相似文献
978.
Peter P.J. Driessen Anton A.J. De Gier 《Tijdschrift voor economische en sociale geografie = Journal of economic and social geography = Revue de géographie économique et humaine = Zeitschrift für ?konomische und soziale Geographie = Revista de geografía económica y social》1999,90(3):336-342
In early 1995 the Netherlands was faced with extremely high water levels on some of its major rivers. An emergency situation arose due to the threat of dikes being breached. As a result, during 1995 and 1996 the dikes along major rivers have been subjected to large-scale reinforcement. So that this could be achieved, a special Act was brought into force to make possible a fast realisation of the operation. In spite of expeditious implementation, factors other than safety concerns were taken into account, such as the interests of ecology and the landscape. The approach adopted towards dike reinforcement in the Netherlands proves that fast decision-making in complex policy situations, does not per se have to be detrimental to precision, regarding procedures and the balancing of different interests. 相似文献
979.
980.