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991.
ABSTRACT We study how the city system is affected by the possibility for the members of the same cultural diaspora to interact across different cities. In so doing, we propose a simple two‐city model with two mobile cultural groups. A localized externality fosters the productivity of individuals when groups interact in a city. At the same time, such interaction dilutes cultural identities and reduces the consumption of culture‐specific goods and services. We show that the two groups segregate in different cities when diaspora members find it hard to communicate at distance whereas they integrate in multicultural cities when communication is easy. The model generates situations in which segregation is an equilibrium but is Pareto dominated by integration. 相似文献
992.
M.A. Pabst I. Letofsky-Papst E. Bock M. Moser L. Dorfer E. Egarter-Vigl F. Hofer 《Journal of archaeological science》2009,36(10):2335-2341
The Tyrolean iceman, a 5300-year-old mummy, presents tattoos on different parts of his body. Skin samples of several line tattoos and a cross tattoo were investigated by optical microscopy and various electron microscopy techniques (TEM, EFETEM, EELS, EDXS, electron diffraction). The epidermis of the investigated skin areas was mostly lacking. The tattooing particles are distributed in the connective tissue and could be identified as soot. In some areas between the soot particles, different silicate crystals are present such as almandine and quartz, along with some not exactly definable crystals. The crystals possibly derived from stones of the fireplace from which the soot was taken for tattooing. Additionally, in the medial part of the right leg, putative ash particles were seen in the tattooed area. Furthermore, in non-tattooed skin areas, a vivianite crystal and small grains of CaPO4 and nearby Fe, P and O could be detected, these having formed most probably after the death of the Tyrolean Iceman during his long period in the mountains. On the surface of two leg specimens, a small layer with brown granules was visible by means of optical microscopy, and these were identified as melanin granules in the stratum basale of the epidermis. 相似文献
993.
C. Papageorgopoulou N.I. Xirotiris P.X. Iten M.R. Baumgartner M. Schmid F. Rühli 《Journal of archaeological science》2009
The partially mummified remains of a high-status female (ca. 1700 BP, Thessaloniki, Greece) were found inside a Roman-type marble sarcophagus containing a lead coffin. The individual was positioned on a wooden pallet, wrapped in bandages, and covered with a gold-embroidered purple silk cloth. Besides the clothes, remnants of soft tissue as well as the individual's original hair style and eyebrows were exceptionally well preserved. In addition to the macroscopic examination, microscopic and biochemical analyses were undertaken. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and gas chromatography/mass spectrometry (GC/MS) were applied to examine the tissue preservation and probable mechanisms of mummification. The presence of chemical components, such as sesquiterpenes, triterpenoids, and diterpenoids, originating from coniferous and pistacia resins, myrrh, and other spices, verify ancient information on preparation methods of the dead in Greek and Roman times. These chemical components are thought to have played a prominent role in the mummification mechanism in this particular case. The potential effect of the lead coffin in the mummification process was also examined. Energy-dispersive X-ray analysis failed to detect lead penetration into the tissues, suggesting that the coffin played a limited role in the preservation of soft tissue. 相似文献
994.
Sediments of the Karoo Basin in southern Africa represent one of the world's finest laboratories for investigating sandstone weathering. The natural breakdown of these sandstones, most notably in the Clarens Formation, is destroying much of the indigenous rock art heritage that exists there. In an attempt to elucidate the operative weathering processes, a range of micro-climatic, rock temperature, rock moisture, rock chemistry, and rock property data have been monitored over a 15 year period at two sites in the KwaZulu-Natal Drakensberg. Results suggest that rock moisture regimes and to a lesser extent, rock thermal regimes exert the most damaging influence on San paintings. It is argued that granular disintegration and the enlargement of existing sandstone pores and bedding planes close to the rock surface, facilitate an increasingly dynamic moisture regime, which leads to an accelerating rate of weathering. Recent technological advances in data collection suggest that a re-evaluation of environmental controls may be necessary before weathering, at a scale appropriate to the deterioration of rock art, can be fully understood. The continued existence of indigenous rock art in southern Africa depends on investigations aimed at the development of techniques for its preservation. 相似文献
995.
Charlotte L. Pearson Darren S. Dale Peter W. Brewer Peter I. Kuniholm Jeffrey Lipton Sturt W. Manning 《Journal of archaeological science》2009
The most marked tree-ring growth anomaly in the Aegean dendrochronological record over the last 9000 years occurs in the mid 17th century BC, and has been speculatively correlated with the impact of the Late Bronze Age eruption of Thera (Santorini). If such a connection could be proved it would be of major interdisciplinary significance. It would open up the possibility of a precise date for a key archaeological, geological and environmental marker horizon, and offer a direct tie between tree-ring and ice-core records some 3600 years ago. A volcanic explanation for the anomaly is highly plausible, yet, in the absence of a scientifically proven causal connection, the value of the proposed correlation is limited. In order to test the hypothesis, dendrochemical analysis via Synchrotron Radiation Scanning X-ray Fluorescence Microscopy (SXFM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) was carried out on growth-ring series from four trees displaying the anomaly. Increases of sulfur, calcium, and rare earth elements following the onset of altered growth, plus concentration spikes of zinc and hafnium in the first affected growth-ring provide promising new evidence in support of a volcanic causal factor. Although a volcanic association is implied, the new data are not sufficient to prove a link to the exact eruption source. 相似文献
996.
The Raya port (eighth to 12th centuries) on the Sinai Peninsula, Egypt, was one of the important port cities for the Red Sea trade. We performed on-site analyses of Islamic glass vessels (used in eighth to 11th centuries) mainly from this site in Egypt using a portable XRF spectrometer. The aim of this paper is to contribute to our understanding of the chemical compositions of early Islamic glass vessels by comparing their archaeological date and typology. In the early Islamic period, glass objects were mainly produced from natron as the soda source. Among the natron glass analyzed in this study, glass vessels with low titanium and iron and high strontium contents, which were probably produced in the Syria–Palestine region, were excavated in the eighth century layer. From the ninth century layer, a large number of samples with high levels of calcium, titanium and iron, probably produced in Egypt, were found. It should be noted that a large number of glass vessels with this chemical composition were found at the Raya site, because this type of glass was rarely reported from other Islamic sites. We finally concluded that this type of glass seems to be produced under a fixed recipe, although some samples contain a colorant or decolorized materials. 相似文献
997.
Ancient copper and lead pollution records from a raised bog complex in Central Wales,UK 总被引:1,自引:0,他引:1
This paper presents records of metal deposition as preserved by a peatland which has accumulated in the lowland coastal zone at Borth, near Aberystwyth, Ceredigion, mid-Wales, U.K. The research objective was to explore the origins and history of metal mining and (or) metallurgy by reconstructing a geochemical record of copper, lead and zinc pollution for the last four millennia. Two cores were extracted from Borth Bog, one from the raised ombrotrophic part of the bog and another from a minerotrophic part of Borth Bog close to the ancient copper workings at Llancynfelin. Although peat stratigraphy and nutrient status have influenced the geochemical record, the results suggest that an early phase of copper and lead pollution occurred at Llancynfelin whilst lead enrichment occurred in the peat core taken close to the centre of Borth Bog during the Bronze Age and the Roman occupation. Therefore the origins of copper and lead mining and metallurgy possibly extend back to the Bronze Age in central Wales. No record of historical pollution exists at either site. The results of this study also provide further evidence that lead and copper are immobile in ombrotrophic peat and that pollution records can be elucidated from minerotrophic peat. Zinc, however, may have suffered from post-depositional mobility. 相似文献
998.
Lacking the salt-water beaches, accessible mineral springs, and rugged mountains that attracted the first tourists to the northeastern United States, the Vermont–Quebec borderland did boast a number of clear and picturesque bodies of water, the largest of which was Lake Memphremagog. Once this lake became accessible by rail, American and Canadian promotional literature and graphic illustrations emphasized the romantic nature of its paddle-wheel excursions, scenic landscape, and resort hotels. This type of tourism was depicted as essentially a passive, civilizing experience in which participants affirmed their aesthetic sensibility and social status by admiring the view of lake and mountains from boat decks and hotel verandahs. But the exclusive nature of this romantic sensibility was undermined to some extent by the fact that local newspapers and railway companies encouraged groups of people from the surrounding communities to join the sight seeing tours. Local entrepreneurs were also quick to take advantage of the market for scenery and, in contrast to other tourist zones, there was no apparent conflict with the industrial development that was taking place at both ends of the lake. 相似文献
999.
1000.
In a geochemical and petrological analysis of overprinting episodes of fluid–rock interaction in a well‐studied metabasaltic sill in the SW Scottish Highlands, we show that syn‐deformational access of metamorphic fluids and consequent fluid–rock interaction is at least in part controlled by preexisting mineralogical variations. Lithological and structural channelling of metamorphic fluids along the axis of the Ardrishaig Anticline, SW Scottish Highlands, caused carbonation of metabasaltic sills hosted by metasedimentary rocks of the Argyll Group in the Dalradian Supergroup. Analysis of chemical and mineralogical variability across a metabasaltic sill at Port Cill Maluaig shows that carbonation at greenschist to epidote–amphibolites facies conditions caused by infiltration of H2O‐CO2 fluids was controlled by mineralogical variations, which were present before carbonation occurred. This variability probably reflects chemical and mineralogical changes imparted on the sill during premetamorphic spilitization. Calculation of precarbonation mineral modes reveals heterogeneous spatial distributions of epidote, amphibole, chlorite and epidote. This reflects both premetamorphic spilitization and prograde greenschist facies metamorphism prior to fluid flow. Spilitization caused albitization of primary plagioclase and spatially heterogeneous growth of epidote ± calcic amphibole ± chlorite ± quartz ± calcite. Greenschist facies metamorphism caused breakdown of primary pyroxene and continued, but spatially more homogeneous, growth of amphibole + chlorite ± quartz. These processes formed diffuse epidote‐rich patches or semi‐continuous layers. These might represent precursors of epidote segregations, which are better developed elsewhere in the SW Scottish Highlands. Chemical and field analyses of epidote reveal the evidence of local volume fluctuations associated with these concentrations of epidote. Transient permeability enhancement associated with these changes may have permitted higher fluid fluxes and therefore more extensive carbonation. This deflected metamorphic fluid such that its flow direction became more layer parallel, limiting propagation of the reaction front into the sill interior. 相似文献