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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An experimental approach to the generation of phenylcarbyne anion

Schell, Philip L January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
2

Exploring palaeoaridity using stable oxygen and carbon isotopes in small mammal teeth : a case study from two Late Pleistocene archaeological cave sites in Morocco, North Africa

Jeffrey, Amy January 2016 (has links)
Revised chronologies from Moroccan cave sites have raised questions concerning the timing of changes in human cultural behaviour in relation to past climate shifts. However, many of the inferences about past moisture regimes are based on external records. Therefore, this thesis aimed to develop a palaeoclimate record using oxygen and carbon isotope values (d18O and d13C) in Gerbillinae (gerbil) teeth from two Late Pleistocene cave sites, El Harhoura 2 and Taforalt, in Morocco. Since small mammals are not commonly used to construct proxy climate records, a modern isotope study was undertaken in northwestern Africa to understand the influences on the stable isotope composition of small mammal tissues in semi-arid and arid settings. The results from the modern study show that d18O composition of gerbil teeth is strongly correlated with mean annual precipitation (MAP), and therefore in arid settings reflects moisture availability. Predictably, the d13C values of the gerbil teeth reflected C3 and C4 dietary inputs, but arid and mesic sites could not be distinguished because of the high variability displayed in d13C. The d18O isotope-based MAP reconstructions suggest that the Mediterranean coastal region of North Africa did not experience hyper-arid conditions during the Late Pleistocene. The d13C values of the gerbil teeth show that C3 vegetation dominated in the Late Pleistocene, but there was a small amount C4 vegetation present at Taforalt. This indicates that small mammals are extremely sensitive to discreet shifts in past vegetation cover. Both the modern and archaeological studies demonstrated that the isotope values of molars and incisors differed. The results indicate that tooth choice is an important consideration for applications as proxy Quaternary records, but also highlights a new potential means to distinguish seasonal contexts. Comparisons of proxy climate records and cultural sequences at Taforalt and El Harhoura 2 show that Middle Stone Age occupations of both sites occurred during relatively humid and arid climate phases. The transition to the Later Stone Age appears to have taken place during a period of increased aridity, hinting that this cultural transition may be related to changing environmental conditions.
3

Development of new analytical techniques for amino acid isotope analysis and their application to palaeodietary reconstruction

McCullagh, James Stephen Oswin January 2007 (has links)
No description available.
4

Weaning at Anglo-Saxon Raunds: Implications for changing breastfeeding practice in Britain over two millennia

Haydock, H., Clarke, L., Craig-Atkins, E., Howcroft, R., Buckberry, J. January 2013 (has links)
This study investigated stable-isotope ratio evidence of weaning for the late Anglo-Saxon population of Raunds Furnells, Northamptonshire, UK. delta(15)N and delta(13)C values in rib collagen were obtained for individuals of different ages to assess the weaning age of infants within the population. A peak in delta(15) N values at about 2-year-old, followed by a decline in delta(15) N values until age three, indicates a change in diet at that age. This change in nitrogen isotope ratios corresponds with the mortality profile from the site, as well as with archaeological and documentary evidence on attitudes towards juveniles in the Anglo-Saxon period. The pattern of delta(13) C values was less clear. Comparison of the predicted age of weaning to published data from sites dating from the Iron Age to the 19th century in Britain reveals a pattern of changing weaning practices over time, with increasingly earlier commencement and shorter periods of complementary feeding in more recent periods. Such a change has implications for the interpretation of socioeconomic changes during this period of British history, since earlier weaning is associated with decreased birth spacing, and could thus have contributed to population growth.
5

Olive oil or lard?: distinguishing plant oils from animal fats in the archeological record of the eastern Mediterranean using gas chromatography/combustion/isotope ratio mass spectrometry

Steele, V. J., Stern, B., Stott, A. W. January 2010 (has links)
Distinguishing animal fats from plant oils in archaeological residues is not straightforward. Characteristic plant sterols, such as beta-sitosterol, are often missing in archaeological samples and specific biomarkers do not exist for most plant fats. Identification is usually based on a range of characteristics such as fatty acid ratios, all of which indicate that a plant oil may be present, none of which uniquely distinguish plant oils from other fats. Degradation and dissolution during burial alter fatty acid ratios and remove short-chain fatty acids, resulting in degraded plant oils with similar fatty acid profiles to other degraded fats. Compound-specific stable isotope analysis of delta(13)C(18:0) and delta(13)C(16:0), carried out by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), has provided a means of distinguishing fish oils, dairy fats, ruminant and non-ruminant adipose fats, but plant oils are rarely included in these analyses. For modern plant oils where C(18:1) is abundant, delta(13)C(18:1) and delta(13)C(16:0) are usually measured. These results cannot be compared with archaeological data or data from other modern reference fats where delta(13)C(18:0) and delta(13)C(16:0) are measured, as C(18:0) and C(18:1) are formed by different processes resulting in different isotopic values. Eight samples of six modern plant oils were saponified, releasing sufficient C(18:0) to measure the isotopic values, which were plotted against delta(13)C(16:0). The isotopic values for these oils, with one exception, formed a tight cluster between ruminant and non-ruminant animal fats. This result complicates the interpretation of mixed fatty residues in geographical areas where both animal fats and plant oils were in use.
6

Two million years of environmental change : a case study from Wonderwerk Cave, Northern Cape, South Africa

Ecker, Michaela Sarah January 2015 (has links)
The arid interior of South Africa lacks long, continuous and well-dated climate and environmental proxy records that can be compared with cultural sequences and with broader global climate records. This thesis develops the first substantial terrestrial environmental sequence for the interior of southern Africa at the site of Wonderwerk Cave, spanning two million years of prehistory. Changes in vegetation and humidity over time were investigated by means of carbon and oxygen stable isotope analysis on fossil herbivore enamel and ostrich eggshell, creating two independent proxy datasets. The Holocene record was used as a baseline for comparing the Pleistocene sequence, but required chronological tightening. Therefore, nine new radiocarbon dates were obtained, and calibrated and modelled with existing dates to provide a firmer chronology. The ostrich eggshell isotope record suggests arid but variable conditions, with distinct phases of increased humidity in the Early Pleistocene and mid-Holocene. Enamel stable isotope results show clear differences in local resource availability between the Early and Mid-Pleistocene, and then between the Pleistocene and Holocene, with an overall trend of increasing aridity. In particular, the onset of dietary specialisation in grazers at 0.8Ma is linked to expanding C4 grasslands. Aridity was not the driver behind the increase in C4 grasses, but changing pCO2 levels at the Mid Pleistocene transition were identified as a possible key factor. The presence of C3 and C4 grasses in the Early Pleistocene, when compared to the domination of C4 grasses today, was fostered by reduced rainfall seasonality. Regional independent developments have to be considered, as other regions in South and East Africa show C4 dominated diets in herbivores at earlier times than at Wonderwerk Cave. In the Holocene, higher temporal resolution indicates phases of environmental change coinciding with changes in the cultural record.
7

Neolithic Anatolia and Central Europe : disentangling enviromental impacts from diet isotope studies

Budd, Chelsea January 2015 (has links)
The aim of this thesis was to reconstruct dietary choices for Neolithic populations in Anatolia and Poland using stable isotope analysis, and to examine the extent to which local environmental factors in these regions affected the isotope values recorded from skeletal collagen. In total 278 new δ13C and δ15N values were obtained from human and animal bone collagen for this project (161 from the site of Oslonki 1, 59 from Barçin Höyük, and 58 from the site of Aktopraklik). From an environmental perspective, the multi-level statistical modelling highlighted a clear relationship with δ13C and δ15N and moisture availability, which was most evident through the proxy of mean annual precipitation (MAP). The modelling highlighted a 0.4‰ decrease in d13C for every 100mm decrease of MAP, and a 0.5‰ decrease in d15N for every 100mm decrease between sites. The δ13C and δ15N values for the North-West Anatolian sites are the first dietary isotopic studies for the Neolithic period in the region. The values are largely commensurate with the dietary isotope studies from Neolithic sites located on the Central Anatolian plateau, with the caveat that the North-West sites perhaps had a greater reliance on herbivore protein (instead of plant protein) than their plateau counterparts. The dietary reconstruction of Oslonki 1 uncovered a rather unexpected outcome - namely that status exerted a degree of control over human diet. If this is indeed true it will be the earliest evidence in Europe of a distinct relationship between the socioeconomic status and diet of an individual.
8

Isotopes in the landscape : carbon and nitrogen isotopes of domestic animals and their application to the archaeology of the Upper and Middle Thames Valley in the Neolithic to Roman periods

Hamilton, Julie January 2015 (has links)
This thesis deals with the development of farming landscapes in the Thames Valley from the Neolithic to the Roman period (4000 BCE - 410 CE). The focus is on the major domestic animal species, cattle, sheep and pig, and their roles in the agroecosystem, traced using carbon and nitrogen isotope ratios measured in collagen. The large dataset of faunal isotope values from a limited area, obtained from sites with extensive archaeological and environmental information, allowed a thorough characterisation of variability in isotope values, within and between species, sites, archaeological periods, and landscape regions. Isotope ratios in a flock of modern sheep showed less variability than archaeological assemblages. Linear mixed models were used to analyse variation in isotope values in 1490 archaeological samples from 23 sites. The pattern of change over time differed for cattle, sheep and pig, reflecting both wide-scale environmental change and changes in animal management. d13C values of cattle and pigs reflected the loss of primary closed-canopy woodland. Pig management changed from an emphasis on woodland resources to a closer association with settlement and consumption of anthropogenic waste. Herbivore d15N values probably reflect variations in the intensity of pasture use and association with arable farming. Climatic cooling since the post-glacial thermal maximum cannot explain these varied trajectories of change. Variation between sites in faunal isotope values was related to landscape regions. Faunal isotope values at individual sites were useful in site interpretation in the context of other evidence. The trend in pig and cattle δ13C values with time was widely found in the UK, as expected if it represents forest clearance. In the Neolithic, cattle management was similar to the UK at central and eastern European Neolithic sites, but pig management was different. Patterns of faunal isotope values and their changes over time, analysed in the context of archaeological and environmental information, can contribute to the interpretation of sites, and give a unique perspective on changes in farming practice and their effects on the landscape.
9

Fruits of the forest : human stable isotope ecology and rainforest adaptations in Late Pleistocene and Holocene Sri Lanka

Roberts, Patrick January 2016 (has links)
Despite ecological, anthropological, and archaeological debate surrounding their desirability as habitats for human occupation, tropical rainforests have received relatively little attention in discussions of Homo sapiens' Pleistocene dispersal. Sri Lanka has yielded some of the earliest dated fossil and material culture evidence (c. 38-35,000 cal. years BP) for our species in a modern rainforest context beyond Africa. Nevertheless, assertions in Sri Lanka, and elsewhere, regarding early human rainforest reliance have been largely based on coarse or 'off-site' palaeoenvironmental records, and the overall role of these environments in human subsistence strategies has remained uncertain. This study applies stable carbon and oxygen isotope analysis to Sri Lankan human fossil, and associated faunal, tooth enamel dated to between 36-29,000 and 3,000 cal. years BP, in order to directly test human rainforest resource reliance, reconstruct a stable isotope ecology, and develop 'on-site' palaeoenvironmental records for Late Pleistocene-Holocene Sri Lankan rainforest foragers. Stable carbon and oxygen isotope analysis of modern Sri Lankan primates, and stable carbon, oxygen, and nitrogen isotope analysis of modern plant samples from the Polonnaruwa Nature Sanctuary, are also performed to investigate the ecology of Sri Lankan primates on which Late Pleistocene-Holocene forager subsistence strategies were focused. The results demonstrate that Homo sapiens relied on rainforest resources in Sri Lanka from c. 36-29,000 cal. years BP until the Iron Age c. 3 cal. years BP, even when open environments, and their corresponding resources, were available. This remains the case through periods of evident environmental change at the Last Glacial Maximum and even upon the arrival of agriculture in the island's tropical forests. The primate stable isotope data prove difficult to interpret as ecological niche separation in the absence of observation data. Nonetheless, humans were evidently able to not only use but also rapidly specialise in the exploitation of South Asia's rainforests.
10

Olive oil or lard? Distinguishing plant oils from animal fats in the archaeological record of the eastern Mediterranean using gas chromatography/combustion/isotope ratio mass spectrometry

Steele, Valerie J., Stern, Ben, Stott, A.W. 15 December 2010 (has links)
Yes / Distinguishing animal fats from plant oils in archaeological residues is not straightforward. Characteristic plant sterols, such as ¿-sitosterol, are often missing in archaeological samples and specific biomarkers do not exist for most plant fats. Identification is usually based on a range of characteristics such as fatty acid ratios, all of which indicate that a plant oil may be present, none of which uniquely distinguish plant oils from other fats. Degradation and dissolution during burial alter fatty acid ratios and remove short chain fatty acids, resulting in degraded plant oils with similar fatty acid profiles to other degraded fats. Compound specific stable isotope analysis of ¿13C18:0 and ¿13C16:0, carried out by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), has provided a means of distinguishing fish oils, dairy fats, ruminant and non-ruminant adipose fats but plant oils are rarely included in these analyses. For modern plant oils where C18:1 is abundant, ¿13C18:1 and ¿13C16:0 are usually measured. These results cannot be compared with archaeological data or other modern reference fats where ¿13C18:0 and ¿13C16:0 are measured, as C18:0 and C18:1 are formed by different processes resulting in different isotopic values. Eight samples of six modern plant oils were saponified releasing sufficient C18:0 to measure the isotopic values, which were plotted against ¿13C16:0. The isotopic values for these oils, with one exception, formed a tight cluster between ruminant and non-ruminant animal fats. This result complicates the interpretation of mixed fatty residues in geographical areas where both animal fats and plant oils were in use. / AHRC

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