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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.
211

Bioarchaeological assessment of diet and changes in femoral and humeral stable isotopic values among subadults at Medieval Alytus, Lithuania.

Page, Katherine 01 January 2014 (has links)
Establishing a chronology of variation in isotopic values can reveal frailty associated with biological and social age, as well as highlight individuals who vary from typical patterns. Although general dietary characteristics and infant feeding practices were previously unknown for subadults excavated from the cemetery at Alytus, Lithuania (14th-18th centuries), previous research concludes that Alytus' subadults experienced high rates of physiological, metabolic, non-specific stress, in addition to specific diseases like tuberculosis. To investigate nuanced relationships between diet and mortality, nitrogen and carbon stable isotopes from the femoral and humeral midshaft diaphyses of 70 subadults (32 weeks gestation to16 years) were analyzed. Dietary reconstruction reveals that on average, exclusive breastfeeding continued until around 2 years of age when enriched ?13C (-19.6‰) and ?15N values (12.7‰) begin to deplete suggesting introduction of C3 grain gruels and potential weaning-associated infirmity. Nitrogen values remained slightly elevated in children (3-5 years, 11.2‰) until the beginning of juvenility (5-8 years, 10.3‰) when ?15N more closely mirrored adult values (16 years, 10.2‰), consistent with predominant consumption of terrestrial animal protein, possibly with riverine influence. The difference between femoral to humeral ? F-H 13C (-0.05 ±0.25‰, 1?) and ? F-H 15N (- 0.01±0.45‰, 1?) was not significant, though humeral values were on average more enriched. Enrichments in humeral nitrogen and carbon coincided with estimated weaning age. Cohorts experiencing childhood and adolescent growth spurts experienced higher femoral ?13C and ?15N values. Examining dietary experience and physiological changes contributes a holistic understanding of subadult morbidity and mortality experiences in Medieval Lithuania.
212

Formation process of a compact Type A Ca-Al-rich inclusion from Northwest Africa 7865 reduced CV3 chondrite : the condensation process after the igneous process / NWA7865還元型CV3コンドライト中のコンパクトタイプAカルシウムとアルミニウムに富む包有物の形成プロセス:火成プロセス後の凝縮プロセス

Suzumura, Akimasa 25 September 2023 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第24870号 / 理博第4980号 / 新制||理||1711(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 伊藤 正一, 教授 野口 高明, 准教授 三宅 亮 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
213

A Study of the Astrophysically Important States of 31S via the 32S(d,t)31S Reaction

Irvine, Dan T. 04 1900 (has links)
<p>The astrophysical <sup>30</sup>P(<em>p</em>,<em>γ</em>)<sup>31</sup>S reaction rate is a key quantity used in both classical nova and type I X-ray burst models that predict isotopic abundances produced during nucleosynthesis in the outburst. Currently, uncertainties in <sup>31</sup>S structure parameters lead to a variation in the reaction rate by a factor of 20 at nova temperatures causing predicted isotopic abundance ratios in the Si-Ar mass region to vary by factors of up to 4. The <sup>30</sup>P(<em>p</em>,<em>γ</em>)<sup>31</sup>S reaction rate can be determined indirectly by measuring transfer reactions populating excited states in <sup>31</sup>S. Nuclear structure information for <sup>31</sup>S resonant states above the proton threshold of 6131 keV and within the Gamow window that contribute most significantly to the reaction rate can be used to re-evaluate the rate for nova and type I X-ray burst temperatures and reduce current uncertainties. We have performed an experiment in order to study the level structure of <sup>31</sup>S via the <sup>32</sup>S(<em>d</em>,<em>t</em>)<sup>31</sup>S single-nucleon transfer reaction using the MP tandem accelerator and Q3D magnetic spectrograph at MLL in Munich, Germany. Excited states of <sup>31</sup>S in the 6-7 MeV region were observed and spin-parity constraints have been suggested. In this work we describe the experimental setup, data analysis and results for both experiments and provide recommendations for further investigation of the <sup>30</sup>P(<em>p</em>,<em>γ</em>)<sup>31</sup>S astrophysical reaction rate.</p> / Master of Science (MSc)
214

Sr Isotopic Composition of Saline Waters and Host Rock in the Eye-Dashwa Lakes Pluton, Atikokan, Ontario

Franklyn, Michael T. 12 1900 (has links)
<p> Groundwater samples from seven boreholes at the Atikokan research area, northwestern Ontario, have been analysed to determine their Sr content and isotopic composition. Whole rock and mineral separates have also been analysed. The groundwaters can be broadly divided into two groups. The 'shallow' waters have low Sr content and high and variable isotopic ratios (.705 - .728) while the 'deep' Sr-rich saline groundwaters have low and constant 87Sr/86Sr ratios (.706 - .707). The saline waters are in isotopic equilibrium with plagioclase and the role of other major rock forming minerals in controlling the isotopic and chemical composition of these waters is negligible. Gypsum is in isotopic equilibrium with the saline waters and appears to be 'young'.</p> <p> The degree of water-plagioclase interaction appears to have been extensive implying low water/rock ratios (ie., 'closed' system. The chemistry of the Atikokan groundwaters is similar to several Shield mine waters. If seawater was a precursor of these waters, there is no evidence for it today. Some degree of mixing with surface waters is indicated in all samples. </p> <p> The granites of the Eye-Dashwa lakes pluton are very Sr-rich. This is reflected in the low isotopic ratios of plagioclase and other minerals and in turn in the low ratios for the saline groundwaters, which are some of the lowest values yet reported.</p> / Thesis / Master of Science (MSc)
215

Limits and possibilities in the geolocation of humans using multiple isotope ratios (H, O, N, C) of hair from east coast cities of the USA

Reynard, L.M., Burt, N., Koon, Hannah E.C., Tuross, N. 30 January 2020 (has links)
No / We examined multiple natural abundance isotope ratios of human hair to assess biological variability within and between geographic locations and, further, to determine how well these isotope values predict location of origin. Sampling locations feature differing seasonality and mobile populations as a robust test of the method. Serially-sampled hair from Cambridge, MA, USA, shows lower δ2 H and δ18 O variability over a one-year time course than model-predicted precipitation isotope ratios, but exhibits considerable differences between individuals. Along a ∼13° northsouth transect in the eastern USA (Brookline, MA, 42.3 ° N, College Park, MD, 39.0 ° N, and Gainesville, FL, 29.7 ° N) δ18 O in human hair shows relatively greater differences and tracks changes in drinking water isotope ratios more sensitively than δ2 H. Determining the domicile of humans using isotope ratios of hair can be confounded by differing variability in hair δ18 O and δ2 H between locations, differential incorporation of H and O into this protein and, in some cases, by tap water δ18 O and δ2 H that differ significantly from predicted precipitation values. With these caveats, randomly chosen people in Florida are separated from those in the two more northerly sites on the basis of the natural abundance isotopes of carbon, nitrogen, hydrogen, and oxygen. / This work was partially supported by the National Geospatial Agency under grant [HM1582-08-0024]. / Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria
216

Isotopic effects in H[subscript]2+ dynamics in an intense laser field

Hua, Jianjun January 1900 (has links)
Master of Science / Department of Physics / Brett D. Esry / The two-state field-aligned (1-D) model has been employed to investigate the dissociation dynamics of a hydrogen molecular ion and its isotopes under the Born-Oppenheimer approximation without rotation. The emphasis of this work was on the role of mass during the dynamical dissociation processes and on the laser-induced branching ratios between different photon pathways. Firstly, we have found that scaling the pulse duration of the laser pulse, applied to H[subscript]2+ and D[subscript]2+ , by the square root of the mass ratio of these isotopes will produce similar structure in the nuclear kinetic energy release (KER) spectra. In fact, the similarity of the spectra is enhanced by including some averaging that is necessary for comparison with experiment. For this to occur, the same broad initial vibrational distribution and a short pulse are preferred. Using this scaling idea, it is possible to produce effectively shorter laser pulses by studying heavier isotopes, like D[subscript]2+. Secondly, we have demonstrated analytically and numerically that there is a carrier-envelope phase effect in the total dissociation probability (TDP) of H[subscript]2+, and this effect grows with nuclear mass. We further show that under the same laser conditions, the CEP effect in the asymmetry between breakup channels decreases with mass. Our analytic expressions enhance the idea that CEP effects can be understood as an interference between different n-photon processes. Thirdly, the trends in the dissociation dynamics of H[subscript]2+ and D[subscript]2+ in a 800nm ultra short intense laser field were demonstrated by studying the dissociation branching ratios of multiphoton processes as a function of the laser peak intensity (from 8[times]10[superscript]9 to 10[superscript]14 W/cm[superscript]2) or pulse length (5fs-7.5fs). Based on the two-state approximation, an energy-analysis method (EAM) was employed to separate multiphoton processes. The results show that the one-photon dissociation process dominates over all other photon processes under all the laser conditions applied in the calculations and that the zero-photon process contributes to a surprisingly large fraction of the total dissociation. Two- and three- photon dissociation are weaker processes, but become more and more important as the laser peak intensity and pulse length increases. A two-state Floquet method was used to check the accuracy of the EAM, and good agreement between the two methods was found, demonstrating the reliability of the EAM. In comparison with H[subscript]2+, D[subscript]2+ displays stronger two and three photon branching ratios (above-threshold dissociation - ATD), which can be attributed to the late arrival of D[subscript]2+ to the critical distance for ATD to occur due to its heavier mass. Therefore, this "mass" effect can be used to steer the molecular dissociation pathways.
217

Formation des chondres : précurseurs et chronologie / Formation of chondrules : precursors and chronology

Villeneuve, Johan 01 July 2010 (has links)
Les chondres, sphérules infra-millimétriques composées de minéraux silicatés de haute température, sont les constituants majeurs des météorites primitives. Ils présentent d'importantes variabilités texturales et chimiques révélatrices d'une histoire complexe. Cette thèse s'est intéressée à la chronologie de formation des chondres et de leurs précurseurs à deux échelles de temps distinctes aux moyens de deux approches complémentaires : la géochimie isotopique via le chronomètre isotopique à courte période ²⁶lAl-²⁶Mg et la pétrologie expérimentale. Le développement au cours de cette thèse d'un protocole analytique innovant de mesure in situ de haute précision par sonde ionique des compositions isotopiques du Mg et Al, a permis de démontrer l'homogénéité de la distribution de l'²⁶Al dans le disque d'accrétion, ce qui présente d'importantes implications sur la chronologie relative et les processus de formation des chondres, mais aussi sur l'origine de l'²⁶Al dans le Système Solaire. L'application de ce protocole analytique aux olivines reliques des chondres permet de préciser leur origine, ainsi que leur chronologie et leur processus de formation. Les expérimentations permettent de montrer qu'il est aisé de former des analogues de chondres de type II PO à partir de chondres de type I PO. Un tel processus de formation des chondres implique l'application de régimes thermiques isothermes suivis d'une trempe rapide, incompatibles avec les mécanismes classiques d'ondes de choc. D'autre part, nous montrons que les compositions chimiques en éléments majeurs et traces des différents types de chondres porphyriques peuvent être reproduites par le mélange de trois phases réfractaires solides héritées des précurseurs des chondres (olivine réfractaire, liquide réfractaire et métal) et d'une phase gazeuse riche en éléments volatils et modérément volatils. Ces résultats nous ont conduit à proposer un modèle de filiation entre les chondres / Chondrules are the major constituent of primitive meteorites. The large variability of textures and chemical compositions within chondrules is indicative of a complex history. This work is focused on the chronology of formation of chondrules and of their precursors by using two complementary tools: the short-lived radio-isotopes ²⁶Al-²⁶Mg and the experimental petrology.The development of a high precision analytical methodology for in situ measurements of the Mg and Al isotopic compositions by ion probe allows to demonstrate that the distribution of ²⁶Al was homogeneous within the accretion disk. This result has important implications for the chronology and process of chondrule formation and also for the origin of ²⁶Al in the Solar System. By using the same methodology with relict olivines in chondrules, we were able to constrain their origin and their formation process.From experimental petrology studies, we show that it was easy to form type II PO chondrules analogues from type I PO analogues. Such a process for chondrules formation implies an isothermal heating followed by a quick quench which is incompatible with the classical shock-waves model. Moreover, we show that the chemical compositions for major and trace elements of the different types of porphyritic chondrules can be easily reproduced by a mixing model composed of three refractory phases inherited from chondrules precursors (refractory olivine, refractory liquid and iron metal) and a gas phase enriched in volatile and moderately volatile elements. Finally, we propose a model of genetic linkage between the different types of porphyritic chondrules
218

Reproductibilité de la mesure des débits de glucose plasmatique après un repas riche en glucides

Bourdon, Éloïse January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
219

Évolution des pratiques alimentaires en cours de vie : une étude isotopique multi-matérielle de la population du cimetière Saint-Matthew (Québec, 1771-1860)

Toupin, Rémi 05 1900 (has links)
En tant que population majoritairement immigrante, les protestants inhumés au cimetière Saint-Matthew, ville de Québec (1771-1860) ont dû s'adapter à un nouvel environnement à leur arrivée au Québec, et donc à de nouvelles ressources. Parallèlement, les 18e et 19e siècles sont marqués par un contexte socio-économique en pleine mutation avec l'arrivée graduelle de la période industrielle, et la ville de Québec, avec son contexte portuaire, a ainsi été au coeur de ces changements. L'objectif de ce mémoire est d'évaluer si la géochimie des isotopes stables appliquée à plusieurs matériaux du squelette humain (collagène et apatite de l'os, collagène de la dentine, et carbonate de l'émail) permet de mieux comprendre comment les comportements alimentaires des individus analysés provenant de ce cimetière cosmopolite (n=40) ont évolué en cours de vie. L'alimentation étant influencée par des conditions socio-économiques, culturelles et environnementales, cela peut nous informer indirectement sur les processus d'adaptation et l'identité d'un individu. C'est dans cette perspective d'écologie culturelle que nous avons interprété les données recueillies lors de ce projet, en complément aux analyses effectuées précédemment par Morland (2009) et Caron (2013). Nos résultats corroborent les tendances déjà observées, soit des pratiques alimentaires semblables à celles que l'on retrouve en Europe, et des immigrants provenant majoritairement des Îles Britanniques. Ils démontrent également une légère augmentation de la consommation de ressources C4, comme le maïs et la canne à sucre, à l'âge adulte pour 90% des individus analysés, de même qu'une baisse du niveau de protéines. Par ailleurs, les individus étudiés ont généralement eu tendance à conserver le même niveau alimentaire les uns par rapport aux autres tout au cours de leur vie, même si les pratiques étaient moins diversifiés à l'âge adulte. Finalement, on constate des similarités de comportements avec les populations irlandaises et britanniques plus pauvres durant l'enfance, alors qu'ils ressemblent davantage à ceux visibles dans la vallée laurentienne en fin de vie, notamment en ce qui concerne l'apport en protéines. Nos résultats suggèrent donc des changements alimentaires significatifs, fort possiblement liés aux processus de migration et à une adaptation constante à un nouvel environnement de la part des individus étudiés. / As a population consisting mainly of immigrants, the Protestants buried in Saint-Matthew’s cemetery, Quebec City (1771-1860) during the 19th century had to adapt to a new environment, and therefore new resources, when they first settled in Quebec. On the other hand, the 18th and 19th centuries saw important socio-economic changes with the coming of the Industrial Revolution, and Quebec City, with its important port, was at the heart of those changes. The objective of this study is to evaluate if the stable isotope geochemistry of several materials of the human skeleton (bone collagen, bone apatite, dentinal collagen and enamel carbonate) can help us understand how dietary behaviours have evolved throughout the life of some individuals (n=40) buried in this cemetery. As diet is closely related to socio-economic, cultural and environmental conditions, it can inform us about individual adaptation and identity through a person’s lifespan. It is in this cultural ecology perspective that we approached this research and the data previously obtained by Morland (2009) and Caron (2013). Our data corroborate those acquired previously on bone collagen by showing that these individuals maintained a European-style diet, and originated mainly from the British Isles. They also show a significant increase in C4 plant (maize, sugarcane, etc.) consumption through adulthood amongst 36 of the 40 individuals that we analyzed, as well as a decrease of protein intake. Our results also indicate a generalized tendency to keep the same dietary profile in the population through life, even if practices became less variable during adulthood. Finally, dietary behaviors show similarites with Irish and poor British populations of the same period for childhood, where as they look more like populations from the St. Lawrence Valley later in life, particularly for protein intake. Therefore, our results suggest important dietary shifts for the individuals we studied, possibly strongly related to their migration process and adaptative response to a new environment.
220

Les processus de transfert d’eau et de dioxyde de carbone dans l’épikarst : aide à la conservation des grottes ornées par le développement de nouvelles méthodologies pour l'étude de l'environnement des cavités

Lopez, Benjamin 25 May 2009 (has links)
Il est communément admis que la recharge des aquifères carbonatés est contrôlée par la zone non saturée, siège d’une mise à l’équilibre des phases liquides, solides et gazeuses. L’épikarst, zone superficielle de ces aquifères, recueille les pluies efficaces et les transfère en profondeur via une double porosité de fissure et de fracture. Des épandages détritiques sablo-argileux fossilisent souvent les paléo-reliefs, changeant ainsi les caractéristiques des zones d’infiltration. Toutefois, les données sur ces dépôts superficiels sont rares, et leur impact sur les modalités de recharge en contexte karstique est aujourd’hui mal connu et peu décrit.La célèbre grotte préhistorique ornée de Lascaux offre une fenêtre d’observation à l’intérieur de l’épikarst et constitue ainsi un site privilégié pour le suivi des processus de transferts. La grotte fait partie d’un réseau karstique fossile partiellement comblé par du matériel détritique sablo-argileux. Les parties basses de la cavité montrent des fortes teneurs en CO2 dans l’air, supérieures à 8% (80 000 ppmv) lors de certaines périodes estivales. Cette thèse propose une étude des caractéristiques de l’infiltration en milieu karstique grâce au suivi des variations chimiques et isotopiques d’une émergence épikarstique au plafond de l’entrée de la grotte. Les principaux objectifs sont la compréhension de la dynamique des fluides en transit dans l’épikarst, la recherche de la source des fortes teneurs en CO2 ainsi que la détermination du rôle des épandages détritiques dans les modalités de recharge de l’aquifère karstique.Après avoir mener une étude approfondie de l’environnement géologique et géomorphologique du site, l’analyse hydroclimatique, combinée au suivi bimensuel de la chimie et des variations isotopiques des eaux épikarstiques, a permis d’investiguer le fonctionnement de la zone d’infiltration du karst d’un point de vue des transferts de masse.Les premières observations montrent que l’émergence épikarstique n’est pas pérenne avec un tarissement qui débute au début de l’été. Le système nécessite environ 250 mm de recharge automnale pour se réactiver. Le signal 18O à l’émergence est fortement amorti comparé au signal 18O dans les pluies ce qui démontre la création d’une réserve épikarstique qui conduit à l’homogénéisation chimique des eaux. Ainsi, les transferts de masse sont lents dans ce système caractérisé par un comportement de type fissuré et non karstique. Les données de 13C collectées à l’émergence permettent de retracer les conditions physico-chimiques qu’ont rencontrées les eaux au cours de leur transit. Elles montrent différentes origines possible de l’infiltration et révèlent des phénomènes de dégazage – précipitation lors des périodes de fortes pluies.De plus, les eaux épikarstiques sont fortement sursaturées vis-à-vis de la calcite et leur forte minéralisation résulte de la mise à l’équilibre avec une pCO2 importante (5% en moyenne). De telles valeurs ne correspondent pas à la production de CO2 du sol. L’autre origine supposée est les épandages détritiques sablo-argileux où des teneurs importantes en CO2 ont été mesurées (pCO2air de 4 à 8%). De plus, la présence d’eau dans ces niveaux suggère que le système est en partie alimenté par ces formations. Ainsi, le transit des eaux au travers de milieux aux conditions physico-chimiques très contrastés pourrait être à l’origine de la sursaturation des eaux qui entrent dans la cavité.Enfin, l’étude montre que les épandages détritiques tiennent deux rôles majeurs dans les processus d’infiltration des eaux : (i) ils participent à leur homogénéisation en les stockant proche du sol et (ii) ils fournissent un fort potentiel de karstification au système. / It is widely recognized that the recharge of deep carbonated aquifers is controlled by a non saturated zone in which liquids, solids and gases are exchanged to attain equilibrium. The epikarstic zone, which represents the bottom of these aquifers, collects the efficient rain waters and transfers them deeper through a dual fractured and fissured porosity. Sandy-clayey detritic coatings are often observed to fossilize the paleo-relief changing the features of the infiltration zones. However, field data on these superficial deposits are sparse and their impact on the recharge modalities in karstic context is not yet well known and described.The famous prehistoric painted cave of Lascaux (France) provides a window into the epikarstic system and offers a privileged environment for the monitoring of transfer processes. The Lascaux cave is part of a fossil karstic network partly filled with detritic material and it is known to have high CO2 concentrations, greater than 8% (80,000 ppmv) in some summer periods, when measured in the air of the lower parts of the cave. Here, we study the epikarstic seepage traits monitoring the chemical and isotopic variations in waters which seep from the entrance roof of the cave. The aims of this work are to understand the dynamics of the fluids in the epikarstic system, to find the source of the high CO2 concentrations measured into the cave and to understand how the detritic coatings impact on the recharge modalities. After carried out an in-depth geological and geomorphological study of the site, the use of hydroclimatic analysis combined with the semi-monthly hydrochemical and isotopic monitoring of the epikarstic waters allowed us to investigate the karstic infiltration zone functioning in term of matter transfer. First, we observed that the epikarstic emergence is non perennial and dries up at the beginning of summer. The system needs an approximately 250 mm recharge in autumn before seeing flows at the emergence. The 18O signal at the emergence is highly amortized compared to the rain 18O signal which reveals the creation of an epikarstic water table that chemically homogenises waters. Thus, the mass transfers are slow in this system characterized by a fissured and nonkarstic behaviour type. The 13C data obtained at the epikarstic emergence seem to characterize the physicochemical conditions of the environments in which waters circulate during their transit in the system. They confirm the possible various origins of waters and reveal degassing – precipitation phenomena during rising periods.Moreover, épikarstic waters are always supersaturated with respect to the calcite and the the high bicarbonates and calcium concentrations result from water equilibrate with an important pCO2 at saturated state (5% on average). Such values of pCO2 do not correspond to the soil CO2 production. The other supposed origin is the sandy clayey detritic formations where we measured important pCO2 (data range from 4 to 8% in the atmosphere of the coatings). Furthermore, the presence of water in the sandy levels of the coatings suggests that the system can be partly fed by these formations. The transit of water through two physicochemicaly highly contrasted environments would be at the origin of the general flows supersaturation state in the cave.Finally, the study shows that the detritic coatings are involved in two aspects of the epikarstic waters run-off conditions: (i) they homogenize them while retaining near to the soil and (ii) give to them a very high karstification potential.

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