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51.
52.
Discovery of the uses and later the invention of fire-making are fundamental to humanity. Following reports over the last decade of traces of fire found on Lower Pleistocene archaeological sites in eastern Africa, the dating of the control of fire by hominids has become a controversial issue. In this paper we critically review the contexts and, in the light of a battery of archaeometric techniques, the nature of reported instances of fire from Koobi Fora and Chesowanja in Kenya, and from Gadeb and the Middle Awash in Ethiopia. We conclude with a discussion of the roles fire may have played in the lifeways of early Pleistocene savanna-living hominids.
Résumé La découverte des usages du feu et ensuite de sa préparation est fondamentale pour l'humanité. Suite à des rapports au cours de la dernière décennie signalant des traces de feu relevées dans des sites archéologiques du Pléistocène inférieur dans l'est de l'Afrique, la datation du contrôle du feu par les hominiens est devenu une source de controverse. Dans cet article, nous révisons d'un oeil critique les contextes et la nature des cas de feu signalés à Koobi Fora et à Chesowanja au Kenya, et à Gadeb et dans l'Awash moyen en Éthiopie, à la lumière d'une suite de techniques archéometriques. Suit en conclusion une discussion sur les rôles qu'aurait pu jouer le feu dans les modes de vie des hominiens vivant dans les savannes du Pléistocène inférieur.相似文献
53.
Nearshore water circulation and bar patterns at Coledale, New South Wales, were surveyed daily over thirty-six consecutive days, from 3 November to 8 December 1978, to identify sequences of changes that might occur in response to spring-to-spring tide cycles of fourteen days, changing barometric and wind conditions associated with the passage of anticyclonic weather systems across the coast, and day to day variation in the nearshore wave regime. During the survey the bar patterns tended to vary from transverse bars, through a composite arrangement incorporating longshore and transverse bars, to a longshore bar pattern as the tide changed from its spring to neap tide phase. However, this sequence was too brief to unequivocally establish variations in nearshore bar pattern that might be attributed to the fourteen day, spring-to-spring tide cycle. Nevertheless, morphologic changes occurring in response to wave regime fluctuation at Coledale were broadly in accord with studies from elsewhere by Dolan et al. (1979, 1982), and Clarke and Eliot (1982, 1983) in that bars and rips were systematically distributed along the beach. At Coledale, bars tended to relocate approximately 0.4 and 0.75 of the distance along the beach from its southern end. The preferred bar spacing closely matches hypothetical standing waves trapped between the headlands of the Coledale embayment. Temporally, the nearshore morphology is highly responsive to wave regime changes such that, as primary breaker heights decrease and remain below Hmax=1.0m, the bar pattern changes from longshore through mixed to transverse bar patterns within three to five days. On one occasion the bar pattern switched from a longshore to a transverse bar pattern within twenty-four hours. 相似文献
54.
The Multiregional Variable Input-Output (MRVIO) model is introduced to measure the development impact of a transportation system. The MRVIO model is a theoretically flexible, computationally simple, and cost-responsive model. Under the MRVIO model, regional input-output coefficients, trade coefficients, and trade flows become cost responsive and easy to compute. The MRVIO model is employed to measure the development impact of the Arkansas waterway during the period of 1974 to 1978. In the study, the U.S. economy is disaggregated into 3 regions and 35 industrial sectors. The MRVIO model estimates the economic conditions of these 3 regions with and without the waterway in terms of industrial output, income, employment, and trade flows. 相似文献
55.
Using data describing the historical distribution of county seats in the United States, we (1) replicate the traditional ratio-variable test of the size-density law, (2) test a new multivariate, nonratio form of the law, and (3) introduce an alternative method of testing, one which avoids three possible problems in traditional analyses: ratio-variables, multicollinearity, and logarithmic transformation. 相似文献
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57.
Sutton and Lawless review a selection of the prolific literature on the Maghreb's human geography published from the late 1970s onward. The pedigree of the discipline in Maghreb was established by several notable geographers who lived, researched, and wrote there. Augustin Bernard's writings on rural settlement, his atlas, and study of Algeria are still cited. Jean Despois's regional study with Raynal and his work on Tunisia, together with the detailed rural research of Jean Poncet, provides a particularly rich coverage for that country. Jean Dresch's early work on Morocco exemplified an early critique of the contemporaneous uncritical colonial human geography. The Sahara's fascination also inspired pioneering studies by Robert Capot-Rey. The work of these notables and others provided a solid background of geographical literature on the Maghreb to be supplemented, criticized, and challenged by more recent researchers, sometimes pupils of the above individuals, and increasingly North African by birth. The tradition of general texts on the Maghreb has continued, though increasingly with systematic approaches replacing regional appraisals. The geography of the decolonization of the Maghreb by Isnard has been replaced by a study summarizing recent collaborative work by a team of French geographers. The Saharan extensions of the Maghreb states have often been linked in general works, sometimes being juxtaposed against the Maghreb as in the essays offered to Jean Despois. Lawless and Findlay's collaborative study juxtaposes geographical studies of each country's economic development with political scientists' evaluations of their sociopolitical development. This review limits itself largely to geographers and geographical journals, only occasionally including significant works from other subject areas, and to 1977-1978 publications, with a few notable exceptions. The spatial juxtaposition of contrasting approaches to economic development, liberal market economy approaches by Tunisia and Morocco arguably leading to dependency, and centrally-planned strategies by Algeria and Libya resulting in bureaucratic constraints serves to offer the Maghreb as a pertinent case-study region for the applied geographer of developing countries. 相似文献
58.
The determinants of county growth 总被引:3,自引:0,他引:3
The determinants of population and employment growth were explored from a broader interregional (as opposed to intraregional) perspective. Data for the 1970s, at the county level of disaggregation, were used to analyze the effects of economic, demographic, and climatic variables on population and employment growth in a simultaneous equation framework. The use of data from the more than 3000 US counties provides a considerably larger testing ground than those used in previous research. The point of departure was a conventional, general equilibrium model in which both households and producers are geographically mobile. The study's dependent variables refer to population, total, and manufacturing employment densities. Family income had a powerful effect in stimulating both population and employment density. A 10% increase in family income led to a 7.9% increase in total and a 9.2% increase in manufacturing employment densities. High family income must stand for high demand, and thus, firms are drawn to an area. High family income also drew households to an area. A 10% increase in family income led to a 5.5% increase in population density. High family income must represent "good" neighborhoods for households. High family income was positively correlated with population and employment density, but in other recent studies either a negative and significant relationship or an insignificant relationship were reported. Local taxes consist of the receipts of county government and those of municipalities, townships, school districts, and special districts within the county. The elasticities reported in Table 4 suggest that a 10% increase in such taxes resulted in about a 0.072% reduction in county population density during the decade. The Industrial Revenue Bonds (IRBs) and the percent of the labor force that is unionized are 2 potential policy instruments at the state level. The study results suggest that IRBs have not stimulated either manufacturing or total employment, and the coefficients were statistically insignificant in the structural equations. The elasticities imply that a 10% increase in percent union reduces total employment by 0.42% and manufacturing employment by 0.18%. The effect on population was tiny. Further, while not intended, the interstate highway program may have been a significant redistributor of population and employment but has not caused immigration of people and jobs from central cities. 相似文献
59.
ABSTRACT This paper develops a model of regional financial markets which can encompass different degrees of spatial financial integration. The behavior of the system is analyzed under alternative assumptions about the time frame of analysis and the extent of the flexibility of interest rates. It is argued that links may exist between regional real and financial sectors even in the short run and that such links must, through the regional balance of payments, exist in the long run, even where there is perfect financial spatial integration. It is observed that these relationships have generally been ignored by regional economic model builders. 相似文献
60.