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When tetracycline antibiotics are administered either orally or by injection they bind at the forming mineral front of the dentine and become incorporated into teeth as a permanent label. In this study, oxytetracycline was used as a label in order to investigate the growth of root dentine in macaques. There are no good data available in the literature for daily rates of root dentine formation over a prolonged period of time in either humans or macaques. Records of ten doses of oxytetracycline administered orally at irregular intervals (but at the same time of day) over a period of 10 months to a young rhesus macaque monkey (Macaca mulatta) were used to calculate the rate of dentine formation in tooth roots. Rates of dentine formation in the first portion of third permanent molar root formation, and in the apical portion of permanent canine and premolar root formation, were consistently between 3 μm and 4 μm per day. There was no evidence in this study of a gradual decrease in daily dentine formation rate from the crown to the root, or along the length of a dentine tubule through the bulk of the dentine, as has been implied previously. With the exception of faster rates recorded in cusps or slower rates recorded at the very beginning or very end of primary dentine secretion in other studies, the results of the present study suggest a consistent rate of dentine formation in permanent macaque teeth. What data there are for human dentine formation rates suggests that it is likely this finding can be extended to human dentine as well.  相似文献   
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This study explores the changes in sinus and meningeal vessel patterns caused by various types of artificial cranial deformation. Endocranial casts were prepared from six crania exhibiting one of three types of deformation (lambdoid, parallelo-fronto-occipital and fronto-vertico-occipital), as well as from 15 undeformed crania. Vessel and sulcus patterns of each cranium were analysed and these patterns included depth of impressions, size and number of vessels, and directional pathways of vessels. Comparisons were made within and between the different deformation types. The results indicated that deformation has an effect upon the pattern, shape and depth of vessel impressions. Vessels tended to be flattened in the areas directly affected by cranial deformation, and there was often compensatory enlargement of other vessels. Further, three of the six artificially deformed crania exhibited enlarged occipital/marginal sinuses, suggesting that this trait is developmentally plastic and greatly influenced by environmental factors.  相似文献   
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This paper examines a key issue in the history of the climate in the pre-instrumental period, that is, how to use narrative sources which make frequent references to weather events, but which need contextualised interpretation. The paper follows an argument that climatological techniques for deriving temperature indices from chronicles, though they have become increasingly elaborate and refined, nevertheless leave out much that is of interest to the social historian. This paper explores the area of the what-is-left-behind when chronicle narratives are reduced to numerical indices. Investigating a broad range of Latin and Italian chronicles from fourteenth and fifteenth-century Italy, the paper draws three main conclusions: that sensitivity to weather events not only varied greatly among writers (as one might expect) but so too did their use of severe weather to serve the purposes of narrative (through sequencing, metaphor and analogy); that sensitivity to meteorological anomaly changed during the period, especially in the fifteenth century with the spread of prognosticating verses; and that the broadening of chroniclers' interests in weather, both ordinary and extraordinary, and in its effects on everyday, material life may allow a connection to and re-evaluation of the Burckhartian idea of the Renaissance ‘discovery of the world’.  相似文献   
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Rapid advances in geophysical techniques over the past decade have provided the maritime archaeological community with significant opportunities for re‐defining the procedures for wreck‐site mapping, evaluation and monitoring. The techniques which offer most potential for high‐resolution survey are acoustic‐based and include sidescan sonar, swath‐bathymetry sonar and multibeam sonar. These techniques were tested on an artificial test‐site in Plymouth Sound and over the wreck of the Stirling Castle. Results demonstrate that the techniques can provide the maritime archaeologist with the opportunity to rapidly and cost‐effectively map and monitor small, centimetric changes on sites, with the potential for long‐term monitoring and management. © 2009 The Authors  相似文献   
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The Canadian government recently launched initiatives to promote immigrant settlement outside of traditional gateway cities, in small towns and rural areas. These initiatives attempt to mitigate socio-economic impacts of population decline, and address barriers to successful integration in urban areas. Drawing on the geographies of hope, this paper examines how newcomers navigate hopes as they imagine rural resettlement in Ontario. Based on focus groups with immigrants (n = 50), the findings suggest that newcomers' imagined rural futures are a dynamic and mobile process, shaped by competing hopes for a stable life. Rural imaginaries can sometimes provide a generative space to realize hopes and develop new future aspirations, other times they can constrain hopes for intergenerational futures. We contend that newcomer hopes arise in moments of relocation uncertainty, shaped by competing visions, interests, and priorities at individual and collective scales. Newcomers' expectations of rural futures are always enlivened with a sense of optimism for what has not yet become, but are equally replete with angst and anxiety for the future. This article concludes that future geographic research on migration-hope-place interactions, particularly in the health subfield, should engage constructions, experiences, and enactments of hope that mediate relocations and the policies governing them.  相似文献   
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