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Smith, David P. (David Paul) 1956. "Responses of Pristina leidyi Smith 1896 (Naididae: Oligochaeta) to Cadmium, Vanadium, and Some Environmental Factors." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc500695/.
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Concern over sediment toxicity has increased the need for toxicity test information with organisms that inhabit sediments. Oligochaetes are exposed to toxicants through feeding and direct body contact with aquatic sediments. Chronic testing with oligochaetes has historically focused on tubificids with test lengths of one year or more to encompass several generations. Most naidid oligochaetes have generation times of three to seven days and could provide chronic information in a matter of weeks. The cosmopolitan distributed naidid, Pristina leidyi, was evaluated for use as a toxicity test organism. Results of research conducted includes culture methods, effects of temperature on reproduction, growth rates in a reference sediment, acute toxicity tests, and chronic toxicity tests.
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DELLA, SCALA VALERIO. "Pristina, oltre l'aporia urbana. L'agency del progetto architettonico in un contesto di state-building postbellico." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2933758.
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Dahinden, Janine. "Prishtina - Schlieren : albanische Migrationsnetzwerke im transnationalen Raum /." Bern [etc.] : [s.n.], 2003. http://www.zb.unibe.ch/download/eldiss/03dahinden_j.pdf.
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MacNelly, Julia. "The City and The Stage: Ethics of Performance in Ex-Yugoslavia." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/scripps_theses/495.
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In this project, contemporary theater and performance art is examined in four cities in ex-Yugoslavia. War has pervaded all of the sites in some way, interrupting a sense of normalcy, altering the city physically as well as ideologically. For that reason, interaction with urban space becomes a central element in performances—whether it serves to preserve the city’s identity amidst destruction, to cleanse the city from the shame of official exploits, to break from the insular legacy of nationalism that flooded the streets, or to gather the city together in a process of collective healing.
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Duclos, Alexandre. "Des formes modernes de cosmopolitisme." Paris 1, 2008. http://www.theses.fr/2008PA010577.
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Ce doctorat a pour ambition de connaître et d'apprendre à connaître les formes modernes de cosmopolitisme, c 'est-a. -dire les visions du monde et de l'humain en genèse dans les sociétés modernes. Nous partons du postulat que ces sociétés entretiennent une relation problématique avec la définition du monde et de l'humain. Notre démarche consiste à élaborer un concept utile théoriquement et pratiquement pour identifier dans les sociétés modernes les visions du monde et de l 'humain qui se construisent et comprendre les modalités de telles constructions sociales (en l'occurrence, a. New York. Pristina et Alexandrie) Nous chercherons à comprendre comment ces manières de penser et de sentir déterminent le sens des actions sociales. Avant de penser une forme d'acosmisme inhérent aux sociétés modernes ou une éventuelle crise de la culture, il s'agit pour nous de comprendre comment les visions du monde et de l'humain se construisent à l'échelle de sociétés concrètes et cohérentes.
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Pap, A. E. (Andrea Edit). "Investigation of pristine and oxidized porous silicon." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514277759.
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While numerous publications deal with the properties and applications of porous silicon (PS), some of the related topics are not complete or could be investigated from different aspects. Therefore, the main objective of this thesis is to provide novel information associated with the optical and chemical properties of PS.
For the investigations, various PS samples are manufactured by electrochemical dark etching of boron-doped p+-type Si wafers. Amongst others, (i) the wavelength-dependent refractive indices of freestanding PS monolayers having different porosities were obtained from optical transmission and reflection spectra in the 700–1700 nm wavelength range, and compared to those calculated from Bruggeman's effective medium approximation (EMA). The refractive indices of the PS samples are shown to be described well with the EMA. In addition, optical scattering at the air-PS interface was demonstrated. (ii) Multilayer stacks are created by alternating the porosities of PS layers within the same sample to form Bragg filters. The Bragg conditions of the filters are calculated and compared to optical transmission measurements. (iii) The oxidation of PS membranes in dry air is investigated with emphases on the reaction kinetics and on the structural changes of the porous matter. As revealed, oxidation proceeds faster in PS than in Si bulk. The formed SiO2 is amorphous and causes stress in the lattice of the residual Si skeleton. (iv) The effect of oxidation extent of PS layers on the growth mechanism of multi-walled carbon nanotubes (CNTs) is investigated. The density of the CNT network is found proportional to the oxidation extent of the substrates. (v) Finally, the chemically-reductive nature of PS is studied and exploited via the immersion plating method to deposit palladium and silver nanoparticles in the nanopores and on the surface of PS samples.
The presented novel results have potential in silicon-based technologies, including integrated active and passive optical components (waveguides, filters, antireflection coatings, optical gas/liquid sensors), electronic devices (electrochemical gas/liquid sensors, diodes, field effect devices) and selective chemical catalysis (substrates, growth templates).
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Dudin, Petr V. "Electrochemistry at pristine single-walled carbon nanotubes." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/50288/.
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This thesis aims to develop an understanding of the fundamentals and applications of electrochermistry at pristine single-walled carbon nanotubes (SWNTs), synthesised by the chemical vapour deposition (CVD) method. The SWNTs grown by CVD on the insulating SiO2 substrates were chosen for the reason being clean, free of amorphous carbon and readiness of nanotube morphology control. 2D random SWNT networks and individual ultra-long flow-aligned SWNTs were employed in the electrochemical studies throughout. SWNT networks were studied either by the microcapillary electrochemical method (MCEM) or in the format of disk-shaped ultramicroelectrodes (UMEs). By challenging the SWNT UMEs with enhanced mass-transport rates in a thin-layer cell (TLC) reversible quasi-steady state cyclic voltammogramms (CVs) were acquired, which allowed the numerical simulations of the voltammetric response and derivation limits for the standard electron transfer (ET) rate constants. Individual SWNTs also generate very high intrinsic mass-transport rates and were studied by the MCEM method, coupled with finite element modelling, highlighting that SWNT sidewalls are active towards outer-sphere redox reactions. By using a sparse surface coverage (typically less than 1%) of pristine SWNTs on an insulating substrate, it has also been demonstrated that electrodeposition of nanoparticles (NPs) is highly directional. By varying electrodeposition driving force (potential) and time one can control the NP density and size. The findings suggest that nucleation of Au on SWNTs is essentially 'instantaneous', and that the nucleation density increases with increase of the deposition potential. This knowledge has enabled the synthesis of a range of different nanostructures, from isolated Au NPs to Au nanowires (NWs), which were used as expedient platforms for analytical and electrocatalytical purposes. While some common inner-sphere redox processes do not readily undergo electrochemical reactions on the carbon nanotubes, which was established in experiments employed SWNT UMEs and individual ultra-long SWNTs, the outer-sphere redox processes were shown to be reversible on the same nanotube electrodes. Novel scanning electrochemical cell microscopy (SECCM) studies allowed individual Pt NPs, electrically connected by the sub-centimeter long SWNT, to be electrochemically assessed. Significantly, this work highlights that individual NPs have their intrinsic electrochemical characteristics.
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Ambroso, Stefano. "Distribution patterns and abundance of Antarctic pristine benthic communities." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671472.
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Knowledge of the abundance, distribution patterns, and population ecology of antarctic benthic biodiversity have increased considerably during the last decades. Antarctic marine benthic biodiversity has been sampled primarily in areas close to research stations and mainly at shallow depths since more than 100 years using a range of sampling methods, including benthic sleds or trawls and grabs each of which targets a particular community or habitat. Recent technological advances and increased availability of remotely operated vehicles (ROVs), manned submersibles, and video equipped towed gears have significantly increased accessibility to mid and outer continental shelves, continental slopes, submarine canyons and seamounts, thus allowing the direct observation and quantitative study of megabenthic assemblages wthout any impact on the benthic community.
Due to the high cost and logistics of these benthic sampling, particularly in Antarctica, studies are often limited to only one biological sampling method. Results of biodiversity studies are used for a range of purposes, including taxonomy, trophic ecology, growth rates, reproductive ecology, environmental impact assessments, and predictive modelling, all of which underpin appropriate marine resource management. However, the generality of marine biodiversity patterns identified among different sampling methods is unknown.
This is one of the resons why more comparative studies are necessary to better understand the ecosystem patterns and processes in antactic regions in a context of climate change scenario.
Major regions of the Antarctic shelf appear to be undergoing rapid climate change, such as warming on the Antarctic Peninsula in the past few decades. Such climate change will affect benthic ecosystems through changes in benthic-pelagic coupling. For these porpouse this tesis pretend to generally understand the distribution and the eocological paper that benthic organisms have on the benthic ecosystem of the antarctic continental shelf. This thesis includes for chapters
In the first chapter we investigate ophiuroid assemblages in terms of the distribution and diversity patterns at three different environmental regimes and depths in the Antarctic Peninsula. In the second chapter we assessed the health status of Antarctic gorgonian assemblages in a pristine and remote area in the southernmost part of the Weddell Sea continental shelf. In the third chapter we compared the performance of two sampling gears by assessing quantitative data on the continental shelf of three oceanographically very distinct regions in Antarctic Peninsula. Finally in the fourth chapter we tried to understand the way in which a gorgonian population affects the diversity of the surrounding megafaunal species, by characterizing gorgonian assemblages dwelling on two very contrasting continental shelves.<br>El conocimiento de la abundancia, los patrones de distribución y la ecología de población de la biodiversidad bentónica antártica ha aumentado considerablemente durante las últimas décadas. La biodiversidad bentónica marina antártica se ha muestreado principalmente en áreas cercanas a las estaciones de investigación y principalmente a poca profundidad desde hace más de 100 años utilizando una variedad de métodos de muestreo, incluidos trineos o redes de arrastre bentónicos, cada uno de los cuales se dirige a una comunidad o hábitat en particular. Los recientes avances tecnológicos y una mayor disponibilidad de vehículos operados a distancia (ROV), sumergibles tripulados y aparatos de muestreo equipados con videocámara han aumentado significativamente la accesibilidad a las plataformas continentales, taludes continentales, cañones submarinos y montañas submarinas, lo que permite la observación directa y el estudio cuantitativo de comunidades megabentónicas sin ningún impacto en la comunidad misma. Debido al alto coste y la compleja logística de estos muestreos, particularmente en la Antártida, los estudios que se generan a menudo se limitan a un solo método de muestreo biológico. Los resultados de los estudios de biodiversidad se utilizan para una variedad de propósitos, que incluyen taxonomía, ecología trófica, tasas de crecimiento, ecología reproductiva, evaluaciones de impacto ambiental y modelos predictivos, todos los cuales sustentan la gestión adecuada de los recursos marinos. Sin embargo, se desconoce la generalidad de los patrones de biodiversidad marina que se pueden identificar entre los diferentes métodos de muestreo. Esta es una de las razones por las que se necesitan más estudios comparativos para comprender mejor los patrones y procesos de los ecosistemas en las regiones antárticas en un contexto de escenario de cambio climático. Las principales regiones de la plataforma antártica parecen estar experimentando un cambio climático rápido, como el calentamiento en la Península Antártica en las últimas décadas. Dicho cambio climático afectará a los ecosistemas bentónicos a través de cambios en el acoplamiento bento-pelágico. Para estos motivos esta tesis tiene como objetivo general comprender la distribución y el papel ecológico que tienen los organismos bentónicos sobre el ecosistema bentónico de la plataforma continental antártica. Esta tesis incluye cuatro capítulos En el primer capítulo se investigan las asociaciones de ofiuras en términos de patrones de distribución y diversidad en tres regímenes ambientales y profundidades diferentes en la Península Antártica. En el segundo capítulo se evalúa el estado de salud de las poplaciones de gorgonias antárticas en un área prístina y remota en la parte más meridional de la plataforma continental del mar de Weddell. En el tercer capítulo se compara el rendimiento de dos artes de muestreo mediante la evaluación de datos cuantitativos en la plataforma continental de tres regiones oceanográficamente muy distintas en la Península Antártica. Finalmente, en el cuarto capítulo se trata de entender la forma en que una población de gorgonias afecta la diversidad de las especies de megafauna asociadas, caracterizando conjuntamente dos poblaciones de gorgonias que habitan en dos plataformas continentales muy diferentes.
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Burkholder, Derek A. "Top Down Control in a Relatively Pristine Seagrass Ecosystem." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/799.
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The loss of large-bodied herbivores and/or top predators has been associated with large-scale changes in terrestrial, freshwater, and marine ecosystems around the world. Understanding the consequences of these declines has been hampered by a lack of studies in relatively pristine systems. To fill this gap, I investigated the dynamics of the relatively pristine seagrass ecosystem of Shark Bay, Australia. I began by examining the seagrass species distributions, stoichiometry, and patterns of nutrient limitation across the whole of Shark Bay. Large areas were N-limited, P-limited, or limited by factors other than nutrients. Phosphorus-limitation was centered in areas of restricted water exchange with the ocean. Nutrient content of seagrasses varied seasonally, but the strength of seasonal responses were species-specific. Using a cafeteria-style experiment, I found that fast-growing seagrass species, which had higher nutrient content experienced higher rates of herbivory than slow-growing species that are dominant in the bay but have low nutrient content. Although removal rates correlated well with nutrient content at a broad scale, within fast-growing species removal rates were not closely tied to N or P content. Using a combination of stable isotope analysis and animal borne video, I found that green turtles (Chelonia mydas) – one of the most abundant large-bodied herbivores in Shark Bay – appear to assimilate little energy from seagrasses at the population level. There was, however, evidence of individual specialization in turtle diets with some individuals foraging largely on seagrasses and others feeding primarily on macroalgae and gelatinous macroplankton. Finally, I used exclusion cages, to examine whether predation-sensitive habitat shifts by megagrazers (green turtles, dugongs) transmitted a behavior-mediated trophic cascade (BMTC) between sharks and seagrasses. In general, data were consistent with predictions of a behavior-mediated trophic cascade. Megaherbivore impacts on seagrasses were large only in the microhabitat where megaherbivores congregate to reduce predation risk. My study highlights the importance of large herbivores in structuring seagrass communities and, more generally, suggests that roving top predators likely are important in structuring communities - and possibly ecosystems - through non-consumptive pathways.
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Van, Zandt Nicholas L. "Aqueous Fabrication of Pristine and Oxide Coated ZnSe Nanoparticles." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1623356039586297.
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Marija, Unterberger. "Razvoj modela pristupa poštanskoj mreži." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=101282&source=NDLTD&language=en.
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Istraživanje koje je sprovedeno u doktorskoj diserrtaciji usmereno je na definisanje modela pristupa poštanskoj mreži i faktora koji utiču na kreiranje modela. Osnovni cilj istraživanja jeste kreiranje dinamičkog modela pristupa poštanskoj mreži koji će obezbediti veću tražnju za uslugom pristupa i veću efikasnost poštanskih operatora univerzalne usluge. Pored kreiranja dinamičkog modela pristupa, u radu je istraženo i tržište poštanskih usluga i ukupne poštanske infrastrukture u Republici Srbiji, a zatim je izvršena analiza i prognoza tražnje za uslugom pristupa poštanskoj mreži. Predložena je originalna metodologija pod nazivom “Post - DSS” (Delfi-Serquval-Scenario), čiji je osnovni cilj bio da se analiziraju zahtevi za pristupom poštanskoj mreži i da se istraže faktori koji utiču na pristup. Na osnovu ostvarenih rezultata istraživanja izgrađen je model pristupa poštanskoj mreži i testiran na području Republike Srbije.<br>The study which was conducted in this doctoral dissertation focused on defining the model of access to the postal network and the factors that influence the creation of the model. The main objective of the research is to create a dynamic model of access to the postal network that will provide greater demand for service access and greater efficiency of the postal operators of the universal service. In addition to creating a dynamic model of access, the paper explored the postal market and overall postal infrastructure in the Republic of Serbia, and then made forecast of the demand for service access to the postal network. The proposed methodology is an original one called "Post-DSS" (Delfi-Servqual-Scenario), whose main objective was to analize requests for access to the postal network and to investigate the factors affecting the access. Based on the results of research, a model of access to the postal network has been built and tested in the Republic of Serbia.
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Hajdari, Arben. "Ulpiana et la romanisation de la Dardanie." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENH036.
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Ce thème de doctorat a été réalisé en cadre d'une convention de cotutelle réalisé entre l'Université Pierre Mendès Franca, Grenoble 2 et l'Université de Prishtina. L'habitat d'Ulpiana un oppidum quasi inconnu dans la Dardanie préromaine, après son invasion de la part des romains, devient un centre important politique, économique et culturel pour toute la Dardanie. Cette étude traitera l'historique du développement de la ville depuis sa fondation et jusqu'à son abandon, et montre une réflexion générale sur la base de données de nos jours qu'offrent les sources littéraires, épigraphiques, numismatiques et les résultats des rapports de fouilles archéologiques. Après son élévation au rang de municipium durant le règne de l'empereur Trajan, Ulpiana connait un agrandissement et un grand développement grâce à sa position géostratégique favorable qu'elle possédait en se situant dans un carrefour de routes importantes qui liait l'est avec l'ouest et surtout grâce aux richesses et aux nombreuses réserves minérales qu'elle possédait lesquelles étaient si importantes durant cette époque pour la stabilité économique de l'empire romain. Elle est devenue très vite l'un des centres gravitationnels le plus importants de toute la province de Moesie, en devenant un centre autant important de la propagation de la nouvelle mode de vie chez la population indigène. Ulpiana, mais aussi les autres centres urbains comme Scupi, Naissus ect, ont joués un rôle important dans le processus de la romanisation qui comprenait toute la population autochtone après l'invasion des romains. Dans ce travail de doctorat fut faite une synthèse générale du processus de la romanisation en Dardanie en soulignant les questions comme ; les enjeux de pouvoir, l'urbanisation, les aspects socio-économiques, les aspects culturels, les portées de la romanisation, la romanisation comme acculturation acceptée par les indignes et la résistance à la romanisation. Cette étude montre un traitement monographique global de l'histoire du développement de l'un des habitats le plus important de Kosova<br>This dissertation has been written based on an agreement (cotutelle) between Université Pierre Mendès Franca, Grenoble 2 and University of Prishtina. The Ulpiana settlement, an oppidum almost unknown in the pre-Roman Dardania, turns into a significant political, economic and cultural centre, after the Roman invasion. This study deals with the history of the development of the city, covering its establishment until its abandonment. Also, the study provides a general overview based on data from literary, epigraphic, numismatic sources as well as archaeological excavations. Upon its rise to the rank of municip, under the rule of Emperor Trajan, Ulpiana faces a swift growth thanks to its favourable geostrategic position on the very important crossroads linking the east and the west, but also because of its wealthy mineral reserves, which in turn were very necessary in ensuring the economic stability of the Empire. Ulpiana will soon turn into one of the most important provinces of Moesia, and in the process it also became a significant centre from where the new way of life diffused to the rest of the native population. Together with the rest of the urban centres like Scupi and Naissus, Ulpiana played an important role in the process of Romanization of the native population, after the Roman invasion. In this dissertation we have presented a comprehensive synthesis of the Romanization process in Dardania by highlighting issues such as: certain policy aspects, urbanization, socio-economic and cultural situation, extension of the process of Romanization as well as the reception of such a process by the natives and the resistance. This study presents a monographic discussion of the overall history of one of the most important dwellings in Kosovo
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Aikebaier, Faluke. "Effects of electron-electron interaction in pristine and doped graphene." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-37467.
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The goal of this master thesis is to investigate the eect of electron-electron interaction on electronic properties of graphene that can be measured experimentally. A tight-binding model, which includes up to next-nearest-neighbor hopping, with parameters tted to density functional theory calculations, has been used to describe the electronic structure of graphene. The electron-electron interaction is described by the Hubbard model using a mean- eld approximation. Based on the analysis of dierent tight-binding models available in the literature, we conclude that a next-nearest-neighbor tight-binding model is in better agreement with density functional theory calculations, especially for the linear dispersion around the Dirac point. The Fermi velocity in this case is very close to the experimental value, which was measured by using a variety of techniques. Interaction-induced modi cations of the linear dispersion around the Dirac point have been obtained. Unlike the non-local Hartree-Fock calculations, which take into account the long-range electron-electron interaction and yield logarithmic corrections, in agreement with experiment, we found only linear modi cations of the Fermi velocity. The reasons why one cannot obtain logarithmic corrections using the mean- eld Hubbard model have been discussed in detail. The remaining part of the thesis is focused on calculations of the local density of states around a single substitutional impurity in graphene. This quantity can be directly compared to the results of the scanning tunneling microscopy in doped graphene. We compare explicitly non-interacting and interacting cases. In the latter case, we performed self-consistent calculations, and found that electron-electron interaction has a signi cant eect on the local density of states. Furthermore, the band gap at high-symmetry points of the Brillouin zone of a supercell, triggered by the impurity, is modi ed by interactions. We use a perturbative model to explain this eect and quantitative agreement with numerical results. In conclusion, it is expected that the long-range electron-electron nteraction is extremely strong and important in graphene. However, as this thesis has shown, interactions at the level of the Hubbard model and mean- eld approximation also introduce corrections to the electronic properties of graphene.
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Saup, Casey Morrisroe. "Biogeochemical Cycling in Pristine and Mining-Impacted Upland Fluvial Sediments." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593664378874682.
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Mejergren, Henrik. "Multipoint Measurements of Magnetic Holes in the Pristine Solar Wind." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290371.
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Satellite data from the Cluster satellites have been used to find and evaluate structures in the pristine solar wind, referred to as magnetic holes. By using multipoint measurements, size and orientation-estimates are established. Other characteristics of interest are also examined, such as velocity, temperature, density, and pressure. The results show that the magnetic holes vary in both shape and size, but with a median difference between the minor and major axis by a factor of five. Most of the events also show increases in both density and ion temperature compared to background values. Comparisons have been made with studies of similar structures downstream of the bow shock referred to as plasmoids which show an even more flattened shape in the direction of the plasma velocity. This study did however not find any such correlations when looking at projections in the GSE-coordinate system. This could suggest that these structures are being compressed in the direction of the velocity as they travel past the bow shock, most likely due to the drastic decrease in velocity. Furthermore, no distinct correlation is found between the size of the MH and the drop of magnetic field strength.<br>Satellitdata från Cluster-satelliterna har använts för att hitta och utvärdera strukturer i den orörda solvinden, kallade magnetiska hål. Genom att använda flerpunktsmätningar fastställs storlek och orienteringsuppskattningar av dessa. Även andra egenskaper av intresse undersöks, såsom hastighet, temperatur, densitet, och tryck. Resultaten visar att de magnetiska hålen varierar både i storlek och form, med en storaxel som är cirka fem gånger större än lillaxeln om man tittar på medianvärdet. De flesta magnetiska hål visar ökningar i både densitet och jontemperatur jämfört med bakgrundsvärden. Jämförelser har gjorts med studier av liknande strukturer, nedströms bågchocken som kallas plasmoider. Dessa visar en ännu mer tillplattad form, i plasmahastighetens riktning. Denna studie hittade dock inga sådana korrelationer när man tittade på formen i GSE-koordinater. Detta kan tyda på att dessa strukturer komprimeras i hastighetens riktning när de färdas förbi bågchocken, troligtvis på grund av den drastiska minskningen av hastigheten. Studien visar inte heller någon tydlig korrelation mellan storleken på hålen och dess minskning av magnetfältstyrkan.
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Ghoraishian, Seyed Mahmood. "Autoimmune reactions in pristane-induced arthritis." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385940.
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Bessey, Cindy. "The Role of Teleost Grazers in a Relatively Pristine Seagrass Ecosystem." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/911.
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Trophic downgrading of ecosystems necessitates a functional understanding of trophic cascades. Identifying the presence of cascades, and the mechanisms through which they occur, is particularly important for seagrass meadows, which are among the most threatened ecosystems on Earth. Shark Bay, Western Australia provides a model system to investigate the potential importance of top-down effects in a relatively pristine seagrass ecosystem. The role of megagrazers in the Shark Bay system has been previously investigated, but the role of macrograzers (i.e., teleosts), and their importance relative to megagrazers, remains unknown. The objective of my dissertation was to elucidate the importance of teleost macrograzers in transmitting top-down effects in seagrass ecosystems. Seagrasses and macroalgae were the main food of the abundant teleost Pelates octolineatus, but stable isotopic values suggested that algae may contribute a larger portion of assimilated food than suggested by gut contents. Pelates octolineatus is at risk from numerous predators, with pied cormorants (Phalacrocorax varius) taking the majority of tethered P. octolineatus. Using a combination of fish trapping and unbaited underwater video surveillance, I found that the relative abundance of P. octolineatus was greater in interior areas of seagrass banks during the cold season, and that the mean length of P. octolineatus was greater in these areas compared to along edges of banks. Finally, I used seagrass transplants and exclosure experiments to determine the relative effect of megagrazers and macrograzers on the establishment and persistence of three species of seagrasses in interior microhabitats. Teleost grazing had the largest impact on seagrass species with the highest nutrient content, and these impacts were primarily observed during the warm season. My findings are consistent with predictions of a behaviorally-mediated trophic cascade initiated by tiger sharks (Galeocerdo cuvier) and transmitted through herbivorous fishes and their predators.
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Marshall, Lynn P. "Conservation of biological diversity in Canada, pristine wilderness or mythical camelot?" Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24880.pdf.
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Kumar, Abhishek. "Black Phosphorus: Pristine and doped surface investigations using Scanning Tunneling Microscopy." Doctoral thesis, Scuola Normale Superiore, 2019. http://hdl.handle.net/11384/85910.
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Black Phosphorus (bP) is the most stable allotrope of phosphorus, first synthesized in
1914 by Bridgman. It was investigated along with other layered materials like GaS, GaSe,
GaTe, graphite, boron nitride and transition metal dichalcogenides for nearly a century.
One important characteristic of these layered materials is that they are composed of twodimensional (2D) sheets of covalently bonded atoms that are kept together by van der
Waals forces. Therefore, they were perceived as interesting materials with an ambition
to achieve thinner and thinner materials, up to a single monolayer, called 2D materials.
In 2004, Andre Geim and Konstantin Novoselov demonstrated the first successful preparation of one-atomic-thin carbon films, called graphene. They used the technique of
scotch tape exfoliation and studied the marvelous properties of graphene, which got
them the Nobel Prize in physics in 2010. With the discovery of interesting properties of
graphene, a search for other 2D materials started. A range of such materials have been
realized since then, like hexagonal boron nitride (h-BN), silicene, germanene, stanene,
and transition metal dichalcogenides (TMDCs). Black Phosphorus (bP) is an important
part of this class of 2D materials, from which phosphorene is exfoliated.
Phosphorene, first exfoliated in 2014, has emerged as an important material. With its
band gap tunable with thickness (from 2.0 eV for the single layer to 0.3 eV for the
bulk), it occupies a special position between zero band gap graphene and high band
gap TMDCs. Anisotropy is another important aspect discovered in its properties like
effective mass, mobility, thermal conductivity, and plasmon resonance. This opens a
gate for potential applications in electronics, photonics, thermoelectrics, and for gas
sensing devices.
Surface studies of bP are quite limited so far. There have been some works reported
showing bP atomic resolution and tunneling spectra on bP surfaces. However, most of
them have been performed on cleaved bulk bP crystals. From a 2D application point of
view, however, it is important to study thin exfoliated bP flakes. The majority of work
reported until now on thin bP flakes concerns electrical transport or optical experiments,
performed on flakes encapsulated in a protective layer. The reason for this is to protect
the material from oxidation upon exposure to air, since bP is known to be highly reactive.
One STM study on a few nanometer-thin bP flake shows surface atomic resolution, but
mainly focuses on the spectroscopic properties of bP. Since surface plays an important
role in nanomaterials due to the high surface-to-volume ratio, it is very important to
understand the surface behavior of such materials.
Here, we have prepared samples on which surface studies on exfoliated bP flakes could be
done. We have prepared samples by exfoliating bP in a glove bag continuously flushed with nitrogen, which provides an inert atmosphere and protects the reactive bP surface
from oxidation. We have used graphene on silicon carbide (SiC) as a substrate, which
provides large atomically flat terraces of SiC and a conducting graphene sheet on top
– fulfilling major requirements for scanning tunneling microscopy (STM) experiments.
We mount the sample inside the glove bag and transfer it under inert atmosphere, which
helps in preserving the highly reactive bP surface from oxidation. This is confirmed by
flat, clean, and oxide-free bP surfaces as seen in STM.
We initially started with the investigation of surface behavior with temperature. We
found that 200 ◦C to 300 ◦C is a proper temperature range for cleaning the surface. We
saw defects on the clean bP surface, reported earlier to be the reason for the intrinsic
p-type doping of bP. At 375 ◦C to 400 ◦C, eye-shaped craters started to develop on the
surface due to phosphorus desorption. Meanwhile, we solved an existing debate in the
literature regarding the orientation of the long axis of these elongated craters: along
the crystallographic armchair direction due to an atomic phosphorus desorption mechanism, or along the crystallographic zigzag direction due to a molecular P2 desorption
mechanism, both investigated by electron microscopy and diffraction studies. Armed
with the power of atomic resolution imaging enabled by the STM technique, we were
able to resolve smaller craters, which are the seeds of the larger craters reported in
previous studies. With a statistical analysis, we confirmed the specific directionality of
the orientation of these anisotropic craters. Furthermore, with the help of atomic resolution provided by STM, we could directly compare the crater alignment with respect
to atomic arrangement, and found that the long axis of the craters is aligned with the
zigzag direction – thus solving the existing debate in the literature.
bP is intrinsically p-doped. Some works were performed to obtain an n-type behavior
by doping, as it would allow p-type and n-type behavior in the same material, very
useful for basic diode applications. In one paper focusing on devices, copper adatom
doping has been shown to yield n-type behavior, using transport measurements. Here,
we study copper growth morphology on bP. We observed the preference of copper atoms
to occupy atomic vacancies of the bP surface. We also observed an alignment of copper
islands along the crystallographic armchair direction of bP, and a step decoration of
copper islands at bP step edges. With scanning tunneling spectroscopy, we studied the
transfer doping of bP by copper at the local atomic level and found a shift of the Fermi
level in bP from p-type behavior to n-type behavior. We also observed an increase in
the band gap value measured on doped bP, consistent with DFT calculations.
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Sharma, Manju. "Magnetic and spectroscopic investigations of pristine and cation-substituted barium hexaferrites." Thesis, IIT Delhi, 2019. http://eprint.iitd.ac.in:80//handle/2074/8041.
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Lewis, C. A. "Studies of pristane isomerisation under laboratory conditions." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373739.
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Daniela, Rosić. "Model kontrole pristupa u Smart Grid sistemima." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2017. https://www.cris.uns.ac.rs/record.jsf?recordId=104820&source=NDLTD&language=en.
Full textAbstract:
U tezi je analiziran problem kontrole pristupa u Smart Grid sistemima. Formalno je specificiran model kontrole pristupa za Smart Grid koji je zasnovan na unapređenju i proširenju RBAC modela i koji je usklađen sa aktuelnim zahtevima u elektroenergetskoj industriji. Postavljena je softverska arhitektura predloženog modela kontrole pristupa, čija je prototipska implementacija zatim integrisana u simuliranom Smart Grid okruženju.<br>This thesis discusses the challenges related to access control in SmartGrid systems. A formal model for access control in the Smart Grid isspecified, extending the role-based access control (RBAC) model to bein accordance with the existing security requirement in the power industry.Based on the proposed access control model, software architecture wasdeveloped and its prototype implementation is integrated in a Smart Gridsimulated environment.
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Corrêa, Mara Adriana. "Participação do gene Slc11a1 na modulação da resposta imune na artrite induzida por pristane em camundongos selecionados para resposta inflamatória aguda." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/42/42133/tde-10062015-093513/.
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A artrite induzida por pristane (PIA) em camundongos AIRmax homozigotos para o alelo R e S do gene Slc11a1 foi usada para avaliar a influência do polimorfismo deste gene na resposta imune, mais especificamente na ativação de macrófagos peritoneais durante a PIA. Estudos anteriores mostraram que a presença do alelo S do gene Slc11a1 aumentou a incidência e a severidade da PIA em AIRmaxSS, sugerindo que este gene ou outro próximo esteja interagindo com o loci da inflamação para modular a PIA. O tratamento com pristane nos animais AIRmaxSS induziu infiltrado intenso composto por linfócitos, monócitos/macrófagos e neutrófilos. Macrófagos AIRmaxSS apresentaram perfis de expressão gênica e celular exacerbados durante a PIA, com expressão/produção elevada de H2O2, NO, IL-1b, IL-6, TNF-a e várias quimiocinas. Entretanto, o alelo R do gene Slc11a1 foi capaz de regular a intensidade de ativação do macrófago de forma mais eficiente que o alelo S e controlar desenvolvimento da artrite. Houve acometimento do rim, pulmão e timo durante a PIA. Nossos dados sugerem que o gene Slc11a1 modula a ativação dos macrófagos envolvidos na suscetibilidade a PIA e estas linhagens representam um modelo murino alternativo para o estudo da artrite reumatoide.<br>Pristane-induced arthritis (PIA) in AIRmax mice homozygous for Slc11a1 R and S allele was used in this study to characterize the role of Slc11a1 polymorphisms on immune response, more specifically in the activation of peritoneal macrophages during PIA. Previous reports showed the presence of S allele of Slc11a1 increased the incidence and severity PIA in AIRmaxSS, suggesting that this gene or another closed-linked gene interacts with inflammatory loci to modulate PIA. Pristane treatment induced intense infiltration of lymphocytes, monocytes/macrophages and neutrophils in AIRmaxSS animals. AIRmaxSS macrophages demonstrated exacerbated cellular and gene expression profiles during PIA, with higher expression/production of H2O2, NO, IL-1b, IL-6, TNF-a and chemokines. However, Slc11a1 R allele could be regulating macrophage activation intensity more efficiently than the S allele and control the development of arthritis. There was involvement of kidney, lung and thymus during PIA. Our data suggest that the Slc11a1 gene modulates macrophage activation involved in PIA susceptibility and these lines represent an alternative murine model of rheumatoid arthritis.
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Soderberg, Gregory. "Ancient discipline and pristine doctrine appeals to antiquity in the developing reformation /." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-07192007-090407/.
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Madden, Deborah. "Pristine purity : primitivism and practical piety in John Wesley's art of physic." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397341.
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Okere, Uchechukwu Victor. "Biodegradation of polycyclic aromatic hydrocarbons in "pristine " soils from different environmental systems." Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.656326.
Full textAbstract:
Global soils have the capacity to act as a sink for polycyclic aromatic hydrocarbons (PAHs) and subsequently as a secondary source making soil/PAH interactions important to environmental PAH levels. A number of physical, chemical and biological processes determine P AH fate in soil but microbial degradation is the most important. Biodegradation depends on bioavailability, soil organic matter, water and nutrient content, temperature and previous exposure to PAHs. Globally, environments differ and soils from different geographic regions differ in their properties and PAH concentrations. While the importance of diffuse P AH contamination of soils is widely acknowledged in literature, most studies on P AH biodegradation in soils have been conducted on soils contaminated from a P AH point source. The aims of this project were to investigate the indigenous biodegradation of PAHs in pristine soils from different geographic locations as well as what environmental factors are most significant in the development of PAH biodegradation potential in pristine soils. Pristine soils used include soils from Antarctica, Norway, UK and Tibet. Levels of PAHs in all the soils were low and properties like soil organic matter, nutrients and water content were different. P AH degrading bacteria were present in all the soils studied irrespective of low PAH concentrations. Temperature was found to affect both the rates and extents of P AH degradation in the Antarctic soils. Results also suggest that the effect of temperature on adaptation of indigenous microbes to PAH degradation might be more important than that of lack of exposure. Further works suggested include the identification of individual P AH -degrading bacteria in these background soils and investigating the effect of increasing soil P AH-contact time in low organic matter background Antarctic soils.
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Taylor, J. P. "Abiotic and biotic influences on acetochlor fate in pristine soils and subsoils." Thesis, University of Kent, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270820.
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Tran, Huy Nam. "Raman scattering and optical spectroscopies of individual pristine and functionalized carbon nanotubes." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS150/document.
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Ce travail, qui concerne l’étude des nanotubes de carbone mono- et double parois, comporte deux volets distincts: (i) une compréhension des propriétés optiques et phononiques intrinsèques des nanotubes de carbone individuels, (ii) une approche expérimentale originale des propriétés des nanotubes de carbone double-parois fonctionnalisés de manières covalente et non-covalente. Concernant l’étude des propriétés intrinsèques des nanotubes de carbone individuels, des informations originales ont été obtenues en couplant des résultats de spectroscopie Raman, incluant la mesure des profils d’excitation des différents modes, avec des données d’absorption optique et de diffraction électronique. De manière générale, l’approche que nous avons développée a mis en avant la complémentarité de la spectroscopie Raman et de la diffraction électronique pour l’identification « la plus probable » de la structure de chaque tube. Parmi les résultats obtenus sur les tubes mono-paroi (SWNTs) individuels, on peut souligner la confirmation originale du caractère excitonique des transitions optiques obtenue en combinant des données d’absorption et de profils d’excitation Raman, ainsi que la mise en évidence d’un comportement inattendu des rapports d’intensité des composantes LO et TO des modes G. L’étude des nanotubes de carbone double-parois (DWNTs) individuels de structures clairement identifiées a permis de comprendre le rôle de la distance inter-tubes dans les déplacements en fréquence des modes Raman (modes de respiration (RBLM) et modes G), en associant à une distance inter-tube donnée une pression interne négative (positive) quand cette distance est supérieure (inférieure) à 0.34 nm. D’autre part, le rôle des effets d’interférences quantiques dans l’évolution avec l’énergie d’excitation des intensités des composantes LO et TO des modes G a été clairement identifié. Enfin, une attribution de l’origine des transitions optiques, mesurées par spectroscopie d’absorption, de différents DWNTs a été proposée.L’étude des propriétés de DWNTs fonctionnalisés a été réalisée en couplant des expériences de spectroscopie Raman, d’absorption UV-visible-NIR et de photoluminescence (PL), incluant les cartes d’excitation de la photoluminescence (PLE), sur des suspensions de DWNTs avant et après fonctionnalisation, (i) covalente via un groupement diazonium, (ii) covalente et non-covalente (pi-stacking) par un colorant. Ce travail présente une contribution au débat sur une question essentielle pour l’utilisation des DWNTs dans des dispositifs opto-électroniques, à savoir : « les DWNTs luminescent-ils ? Et si oui, quelle est l’origine de la luminescence ? ». La présence de photoluminescence dans nos échantillons de DWNTs est établie, et l’étude de son évolution avec différents types et degrés de fonctionnalisation démontre qu’elle ne peut provenir que des tubes internes des DWNTs (PL intrinsèque aux DWNTs), ou de SWNTs générés par l’extrusion des tubes internes de DWNTs durant la préparation des suspensions. D’autre part, on peut souligner la mise en évidence d’un transfert d’énergie du colorant vers le tube interne quand le colorant est greffé de manière covalente sur la tube externe<br>This work concerns the study of mono- and double-walled carbon nanotubes. It contains two distinct parts: (i) the first part is devoted to the understanding of the intrinsic optical and phonon properties of individual carbon nanotubes; (ii) the second part reports an experimental investigation of the properties of covalently and non-covalently functionalized double-walled carbon nanotubes. Concerning the study of the intrinsic properties of the individual carbon nanotubes, new information was obtained by coupling Raman spectroscopy data, including the measurement of the excitation profiles of different Raman-active modes, with optical absorption and electronic diffraction data. From a general point of view, our approach put in evidence the complementarity of the Raman spectroscopy and electronic diffraction for “the most probable” assignment of the structure of the nanotubes.Among the results obtained on individual single-walled carbon nanotubes (SWNTs), one can underline the confirmation of the excitonic character of the optical transitions by combining optical absorption and Raman excitation profiles on the same nanotubes, and the evidence of an unexpected behavior of the relative intensities of the LO and TO components of the G-modes. The study of the index-identified individual double-walled carbon nanotubes has permitted to understand the role of the inter-walls distance in the frequency shifts of the radial breathing-like modes (RBLM) and G-modes, by associating a given inter-walls distance to a negative (positive) internal pressure when this distance is larger (smaller) than 0.34 nm. On the other hand, the role of quantum interferences in the evolution with the excitation energy of the intensities of the LO and TO components of the G-modes was clearly identified. Finally, the assignment of the optical transitions, measured by absorption spectroscopy, of index-identified DWNTs was proposed.The study of the properties of functionalized DWNTs was performed by combining Raman spectroscopy, UV-visible-NIR absorption and photoluminescence (PL), including maps of photoluminescence excitation (PLE), on suspensions of DWNTs before and after functionalization: (i) covalently by using diazonium, (ii) covalently and non-covalently (pi-stacking) by using dye molecules. This work is a contribution to the debate on an essential question for the use of the DWNTs in opto-electronic devices, namely: “Do the DWNTs they luminesce? And if yes, what is the origin of the luminescence?". The presence of photoluminescence in our samples of DWNTs was established, and the study of its evolution with various kinds and degrees of functionalization states that PL can only result from inner tubes (intrinsic PL of DWNTs), or from SWNTs generated by the extrusion of the internal tubes of DWNTs during the preparation of the suspensions. On the other hand, one must emphasize the evidence of an energy transfer from the dye molecules towards the internal tube when such molecules are covalently grafted on the outer tube
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Bueno, Paula Franciely Grutka. "Um rio de unidade de conservação, como ambiente pristine para ictiofauna neotropical." Universidade Estadual do Oeste do Parana, 2012. http://tede.unioeste.br:8080/tede/handle/tede/726.
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Previous issue date: 2012-09-24<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Lotic environments are influenced by outer regions, but also influence adjacent terrestrial
environments. Studies carried in conservation areas are still scarce, especially when they
refer to aquatic ecosystems, which are only preserved if inserted to a Conservation Unit.
Another factor that hinders the preservation of lotic environments is the study techniques
used, which are still based on terrestrial and marine environments. The objective of the
present study was to analyze limnological parameters of a preserved river, the Floriano
River, evaluating the quality of its waters through the comparison between two sampling
points. The study was conducted between February and December 2010 in two parts of the
river called stretch 1 and stretch 2, where bimonthly the following variables were sampled:
air and water temperature, dissolved oxygen and oxygen saturation, pH, conductivity,
turbidity and transparency. Seasonal differences were observed during the evaluation
period of the study. The average air temperatures fluctuated from 15.6° C to 27.0° C, while
the average water temperatures were between 17.9° C to 26.6° C. The minimum and
maximum values observed for oxygen saturation were 83.6% and 111.3%, consistent with
the standards of a preserved river. Transparency average values stayed between 0.3 and 0.9
m, showing a good water quality. Dissolved oxygen, pH and turbidity presented values
within the standards established by the CONAMA Resolution 357/05. Considering the
rivers belonging to the Iguaçu National Park, the Floriano River is the most preserved one,
since its basin is fully inserted in this Conservation Unit, presenting no changes in its
natural habitat. Thus, this area represents a good site for studies of abiotic variables and for
setting standards to be used in the evaluation of anthropogenic environments<br>Os ambientes lóticos sofrem influência das regiões externas, mas também influenciam no
ambiente terrestre. Os estudos em áreas preservadas ainda são escassos principalmente
quando se considera os ecossistemas aquáticos, que somente são preservados quando
fazem parte de uma Unidade de Conservação. Outro fator que dificulta a preservação de
ambientes lóticos são as técnicas de estudos utilizadas, que ainda estão baseadas nos
ambientes terrestres e marinhos. O objetivo deste trabalho foi analisar parâmetros
limnológicos de um rio preservado, o rio Floriano, avaliando a qualidade de suas águas,
por meio da comparação entre dois pontos de coleta. O estudo foi realizado entre fevereiro
e dezembro de 2010, onde foram amostradas bimensalmente as variáveis temperatura do
ar, temperatura da água, oxigênio dissolvido, saturação de oxigênio, pH, condutividade
elétrica, turbidez e transparência, em dois pontos denominados ponto 1 e ponto 2. Foram
observadas diferenças sazonais durante a avaliação da pesquisa. No período de estudo
foram verificadas temperaturas médias do ar de 15,6oC a 27,0oC, enquanto que para a
temperatura da água foram observadas médias de 17,9oC a 26,6oC. Os valores mínimos e
máximos para saturação de oxigênio foram de 83,6% e 111,3%, condizentes com os
padrões de um rio preservado. Para transparência foram conferidas médias de 0,3 a 0,9m,
que demonstram a boa qualidade da água As variáveis oxigênio dissolvido, pH e turbidez
apresentaram valores dentro dos padrões estabelecidos pela resolução no 357/05 do
CONAMA. Considerando os rios pertencentes ao Parque Nacional do Iguaçu, o rio
Floriano é o rio mais preservado, por sua bacia estar totalmente inserida nessa Unidade de
Conservação, portanto por não possuir modificações em seu habitat natural, torna-se
importante sítio para estudos de variáveis abióticas estabelecendo padrões de comparação
com outros ambientes antropizados
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Beech, Jonathan Thomas. "The role of cytokines in pristane induced arthritis." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389033.
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Goran, Sladić. "Model kontekstno zavisne kontrole pristupa u poslovnim sistemima." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2011. http://dx.doi.org/10.2298/NS2011SLADICGORAN.
Full textAbstract:
Kontrola pristupa odnosno autorizacija, u širem smislu, razmatra na koji način korisnici mogu pristupiti resursima računarskog sistema i na koji način ih koristiti. Ova disertacija se bavi problemima kontrole pristupa u poslovnim sistemima. Tema disertacije je formalna specifkacija modela kontekstno zavisne kontrole pristupa u poslovnim sistemima koji je baziran na RBAC modelu kontrole pristupa. Uvođenjem kontekstno zavisne kontrole pristupa omogućeno je defnisanje složenijih prava pristupa koje u postojećim modelima kontrole pristupa za poslovne sisteme nije bilo moguće realizovati ili bi njihova realizacija bila komplikovana. Dati model primenljiv je u različitim poslovnim sistemima, a podržava defnisanje prava pristupa kako za jednostavne tako i za slo·zene poslovne tokove. Sistem je verifkovan na dva realna poslovna procesa pomoću razvijenog prototipa. Prikazana prototipska implementacija koja ispunjava ciljeve u pogledu funkcionalnosti postavljene pred sistem predstavlja potvrdu praktične vrednosti predloženog modela.<br>Access control is concerned with the way in which users can access to resources in the computer system. This dissertation focuses on problems of access control for business processes. The subject of the dissertation is a formal specification of the RBAC-based context sensitive access control model for business processes. By using a context-sensitive access control it is possible to define more complex access control policies whose implementation in existing access control models for business processes is not possible or is very complicated. The given model is applicable in diferent business systems, and supports the definition of access control policies for both simple and complex business processes. The model's prototype is verified by two case studies on real business processes. The presented prototype implementation represents a proof of the proposed model's practical value.
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Moser, Muriel. "Senatvi avctoritatem pristinam reddidisti : the Roman senatorial aristocracy under Constantine and Constantius II." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/265599.
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Under the Constantinian dynasty, the Roman senatorial aristocracy was subject to two major social and political transformations. Firstly, emperors gradually modified the rules for senatorial office-holding, moving away from a hereditary model towards a more flexible system in which rank could be gained through merit (service to the emperor). The number of senatorial posts in the administration was increased, which resulted in the expansion of the senatorial order from outside the hereditary aristocracy. Secondly, Constantine founded Constantinople, where a second senate emerged, prompting the formation of a new eastern senatorial order. Roman senatorial nobles were among the most powerful individuals of the empire. The expansion of their order, the transformation of senatorial office-holding and the foundation of Constantinople did not lead to the reduction of their influence in government. Constantine actively encouraged the involvement of Roman grandees in government as a means of supporting imperial rule, especially in the East. Constantine's son, Constantius II, emperor of the East, continued these policies until 350, when the military and dynastic context forcefully disrupted his relationship with the Roman senate. In this situation, Constantius moved to found a second senate in Constantinople to legitimise his position in the East. Modelled on Rome, the new senate quickly assembled the top echelons of the traditional eastern elite. However, the emergence of this order did not impinge on the authority of the Roman senate, restored to its traditional authority by Constantine. Constantius made it clear that the support of the Roman nobility remained a vital source of political stability and (above all) a necessary means of risk-reduction in the continuing context of the fragility of imperial power.
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Wang, Yushan. "First-principles investigations of electronic structures of pristine and doped anatase titanium dioxide." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 182 p, 2007. http://proquest.umi.com/pqdweb?did=1354136771&sid=25&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ferrera, Rodriguez Ofelia. "Rhizosphere microbial communities of Puccinella angustata thriving in pristine diesel-contaminated Arctic soils." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104604.
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Petroleum hydrocarbon contamination has reached Arctic soils, Puccinellia angustata thrives in such habitats. Hydrocarbon removal during phytoremediation treatments strongly depends on the catabolic activities of root associated microorganisms. This research compared the rhizospheric microorganisms from P. angustata established at Arctic soils under different degrees of contamination with petroleum hydrocarbons to determine if this plant species has phytoremediation potential. The abundance, diversity, and activity of soil bacterial communities were investigated by means of plate and microscopic counts, strains isolation, 16S rRNA gene DGGE fingerprinting, functional gene PCR detection, microcosm hydrocarbon mineralization assays, and TPH quantification. This study was divided in three experimental stages. In the first stage a comparison of samples vegetated by five different plant species as well as four bulk samples, showed that P. angustata had greater enrichment of hydrocarbon-degrading bacteria than samples vegetated by other plant species. In the second stage, a comparison between the rhizosphere of P. angustata and bulk samples collected at pristine (Pr), hydrocarbon-contaminated but non-bioremediated (NBr) and hydrocarbon-contaminated and bioremediated (Br) Arctic soils, revealed that the presence of P. angustata enhanced the abundance and the activity of hydrocarbon-degrading microorganisms in two soils (Pr and NBr) but not at Br since this soil was subjected to fertilizations as bioremediation process. In the third stage, via growth chamber experiments, in which high Arctic summer conditions were simulated, P. angustata (with and without nitrogen fertilization) was assessed for phytoremediation of a soil artificially contaminated with diesel (10,000 mg Kg-1). Puccinellia showed tolerance to fresh diesel contamination and enhanced hydrocarbon-degrading bacteria that significantly increased the TPH removal. Also, the rhizosphere of P. angusatata had high bacterial diversity, encompassing members from Actinobacteria, Bacteroidetes, Firmicutes, Gemmatimonadetes and Proteobacteria phyla. These findings indicate that P. angustata stimulates soil microflora responsible for biodegradation of hydrocarbons therefore it has potential for phytoremediating contaminated Arctic soils.Abbreviation: PCR (polymerase chain reaction), DGGE (Denaturing Gradient Gel Electrophoresis), TPH (Total Petroleum Hydrocarbons).<br>La contamination par hydrocarbures pétroliers a touché les sols arctiques ; Puccinellia angustata se développe dans ces habitats. L'élimination de l'hydrocarbure pendant les traitements de phytoremédiation dépend fortement des activités cataboliques des microorganismes associés à la racine. Cette recherche a comparé les microorganismes rhizosphériques de P. angustata établis dans les sols arctiques à différents niveaux de contamination par hydrocarbures pétroliers pour déterminer si cette espèce de plante a du potentiel pour la phytoremédiation. L'abondance, la diversité, et l'activité des communautés bactériennes du sol ont été examinées au moyen de comptages sur plaque et microscopiques, isolement de souches, empreinte digitale par DGGE du gène 16S rRNA, détection fonctionnelle du gène par PCR, essais de minéralisation des hydrocarbures en microcosme et quantification de TPH. Cette étude a été divisée en trois étapes expérimentales. Dans la première étape, une comparaison d'échantillons globales et d'échantillons plantés de cinq espèces végétales différentes a montré que P. angustata avait une plus grande accumulation de bactéries de dégradation de l'hydrocarbure que les échantillons plantés avec d'autres espèces végétales. Dans la deuxième étape, une comparaison entre la rhizosphère de P. angustata et des échantillons globales pris des sols arctiques pures (Pr), des sols arctiques contaminés par hydrocarbures et non-bio-réhabilités (NBr) et des sols arctiques contaminés par hydrocarbures et bio-réhabilités (Br), a révélé que la présence de P. angustata a augmenté l'abondance et l'activité des microorganismes de dégradation d'hydrocarbures dans deux sols (Pr et NBr), mais pas dans le Br, parce que ce sol avait reçu des fertilisations comme processus de bioremédiation. Dans la troisième étape, au moyen d‘essais en chambres de croissance où les conditions d'été du Haut-Arctique étaient simulées, P. angustata (avec et sans fertilisation par hydrogène) a été évaluée pour la phytoremédiation d'un sol contaminé artificiellement avec du diesel (10,000 mg Kg-1). Puccinellia a montré tolérance à la contamination par diesel et a augmenté les bactéries de dégradation d'hydrocarbures, en améliorant ainsi beaucoup l'élimination des TPH. Aussi, la rhizosphère de P. angustata avait une haute diversité bactérienne, contenant des membres de phylums Actinobacteria, Bacteroidetes, Firmicutes, Gemmatimonadetes et Proteobacteria. Ces conclusions indiquent que P. angustata stimule la microflore du sol qui est responsable de la biodégradation des hydrocarbures et, pourtant, pourrait aider la phytoremédiation des sols arctiques contaminés.Abréviations : PCR (Réactions en chaîne par polymérase), DGGE (Électrophorèse sur gel à gradient dénaturant),TPH (hydrocarbures pétroliers totaux)
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Juhel, Jean-Baptiste. "Base de référence, impacts anthropiques et mesure s de protection pour les requins récifaux de Nouvelle - Calédonie." Thesis, Nouvelle Calédonie, 2016. http://www.theses.fr/2016NCAL0002/document.
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L'impact anthropique sur les écosystèmes coralliens est aujourd'hui largement documenté, que ce soit sur la biodiversité qu'ils hébergent, leur diversité fonctionnelle, les services écosystémiques qu'ils procurent ou leur capacité de résilience. Parmi les groupes trophiques, les prédateurs apicaux en général et les requins en particulier, sont particulièrement sensibles aux perturbations d’origine humaine du fait de leurs traits d'histoire de vie conservateurs (e.g. croissance lente, maturité sexuelle tardive, faible fécondité). D'après certaines estimations, les populations de requins ont décliné de plus de 90% à l'échelle globale. Afin d'assurer le maintien de leurs populations et de leur rôle fonctionnel dans la communauté, il est nécessaire de mettre en place des mesures de gestion adaptées. Les objectifs de cette thèse sont de 1) faire le bilan des populations de requins de Nouvelle-Calédonie ; 2) déterminer l'efficacité des vidéos stéréoscopiques appâtées (S-BRUVS) pour recenser les requins en les comparant aux comptages en plongées (UVC) et évaluer leur possible amélioration ; 3) évaluer l'impact de la proximité humaine sur la diversité, l'abondance et le comportement des requins récifaux et 4) déterminer l'efficacité des mesures de gestion en place pour protéger ces espèces emblématiques. Les résultats des deux méthodes de recensement montrent un important déclin d'environ 90% des abondances de requins récifaux le long d'un gradient anthropique complet en Nouvelle-Calédonie alors que la pêche des requins est historiquement absente dans cet archipel. Une importante altération comportementale du requin gris de récif (Carcharhinus amblyrhynchos) face à la nouveauté d'un appât a été mise en évidence. Les individus se tiennent plus éloigné du dispositif, interagissent moins avec l'appât et mettent plus de temps pour le mordre avec l'augmentation de la proximité humaine. Cette dernière est le principal moteur de ce déclin d’abondance (46 à 71%) et de l'altération comportementale vers des individus plus craintifs (50 à 80%). Globalement, les aires marines protégées de Nouvelle-Calédonie ne sont pas efficaces pour la protection des requins. Néanmoins, la réserve intégrale Merlet héberge des populations de requins proche du niveau de récifs isolés de l’archipel et protège une partie du comportement. Les résultats de ce travail révèlent 1) l'importance et le caractère unique des récifs coralliens isolés ; 2) qu'en absence de pêche la proximité humaine conditionne l'abondance et le comportement des requins de récifs avec des conséquences écologiques potentielles sur l'ensemble du réseau trophique ; 3) que l'efficacité des AMPs réside dans leur capacité à exclure la présence humaine sur une surface suffisamment grande<br>Anthropogenic impacts on coral reefs are largely documented through changes in functional diversity, ecosystem services or resilience. Among trophic groups, apex predators in general and sharks in particular are the most sensitive to disturbance due to conservative life history traits (e.g. slow growth, late sexual maturity, low fecundity). By some estimates, shark populations have declined by >90% worldwide. To ensure the sustainability of their populations and their functional role in the reef community, appropriate management measures must be implemented. The aims of this thesis are 1) to assess reef shark populations in New Caledonia; 2) to evaluate the efficiency of stereo baited remote underwater video systems (S-BRUVS) in surveying shark distribution comparing them to underwater visual censuses (UVC) and to evaluate their potential improvements ; 3) to evaluate the impact of human proximity on diversity, abundance and behaviour of reef sharks and 4) to determine the efficiency of management measures currently in place in New Caledonia to protect reef shark populations. The results of S-BRUVS and UVC were congruent and revealed a dramatic decline of shark abundance of ~90% along the anthropogenic gradient in a country where shark fishing is historically absent. An important behavioural alteration of the grey reef shark (Carcharhinus amblyrhynchos) towards bait was highlighted. Individuals remained farther from the device, exhibited more cautious approaches, interacted less with the bait and took longer to bite it as human proximity increased. Human proximity was the main driver of the abundance decline (46 to 71%) and the behavioural alteration towards shier individuals (50 to 80%). Globally, MPAs in New Caledonia are not effective in protecting reef sharks. However, the oldest and most restrictive MPA (Merlet) hosts shark abundance close to that of some remote reefs of the archipelago and partially protect the behaviour of individuals. These results 1) emphasize the unique role of remote coral reefs as the last refuges for sharks ; 2) reveal that in absence of shark fishing, human proximity condition shark abundance and behaviour with potential ecological consequences and 3) indicate that the MPAs efficiency to ensure the protection of reef sharks is effected by their ability to exclude human presence over a sufficiently large area
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Grönlund, Erik. "The Recovery of Two Polluted Subarctic Lakes—Towards Nutrient Management or a Pristine State?" Mittuniversitetet, Institutionen för teknik och hållbar utveckling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-17200.
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Two small subarctic lakes were eutrophicated due to wastewater discharge from 1964. In 1975, a wastewater treatment plant was built and a recovery process started. This paper will: (1) compile the 1972–1974, 1978–1980 and 1985–1988 investigation data regarding phosphorous and microalgae for one of the lakes; (2) complement with unpublished data from 1985 and 2003; and (3) introduce a discussion regarding three alternatives for future development of the lakes in their last phase of recovery. In the latest investigation, 2003, the lakes were assessed as almost recovered. They had returned to an oligotrophic state, but not fully to a pre-sewage situation. In the upper lake, more heavily polluted, the total phosphorous levels had decreased from an average of 168 µg P/L in 1972–1974 to an average of 12 µg P/L in 2003. The phytoplankton biomass had decreased twentyfold during the same period, from 11.2 mg/L to 0.6 mg/L. The Secchi depth had increased from 1.3 m to 2.8 m. The low oxygen level in late winter was still not recovered, thereby profoundly affecting residential organisms in the lakes. The low winter oxygen is assumed to remain so for a long time due to phosphorus release from sediments in the lakes.
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Phillips, Nicole. "Conservation genetics of Pristis sawfishes in Australian waters." Thesis, Phillips, Nicole (2012) Conservation genetics of Pristis sawfishes in Australian waters. PhD thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/10513/.
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Northern Australia is believed to contain the last ‘viable’ populations of the critically endangered Freshwater Sawfish, Pristis microdon, Dwarf Sawfish, Pristis clavata, and Green Sawfish, Pristis zijsron, making these populations of global significance. Mitochondrial and microsatellite markers were used to investigate the population structure, levels of genetic diversity, and evolutionary history of each of these species in northern Australian waters. Pristis microdon, which utilizes freshwater rivers as juveniles and marine waters as adults, has high levels of mtDNA heterogeneity and no nDNA heterogeneity; indicating that this species has female philopatry coupled with male-biased dispersal in northern Australian waters. The conservation plans for this species should, therefore, place a high priority on the protection of females, pupping grounds, and nursery areas to minimize the risk of extirpation. Conservation plans also need to consider the likelihood that a decline in the abundance of this species in one location could have an effect on its abundance and genetic ‘health’ in other locations via male gene flow. In contrast, P. clavata and P. zijsron, which spend their entire lives in marine and/or estuarine waters, each have heterogeneity in the mtDNA and nDNA markers, suggesting that gene flow in both males and females is restricted at large spatial scales in northern Australian waters. Consequently, the risk of extirpation for each of these species is relatively high since a decline in abundance is unlikely to be replenished by immigration from other locations. Therefore, conservation plans for P. clavata and P. zijsron should place a high priority on the protection of males and females, as well as pupping grounds and nursery areas. Most of the assemblages of each of the Pristis species contained moderate and high levels of diversity in mtDNA and nDNA markers, respectively. This suggests that the prognosis for the short and medium-term survival of each of these species in Australian waters is relatively good, providing that measures are put in place to curb any further declines in abundance. However, the levels of mtDNA diversity in the assemblage of each of P. clavata and P. zijsron in the Gulf of Carpentaria were reduced and, therefore, these assemblages may warrant special conservation status. Finally, the evolutionary histories of the Pristis species in Australian waters have most likely played an important role in shaping the observed patterns of population structure and levels of genetic diversity, however, the relative influence of contemporary versus historic factors on the amount and distribution of genetic variation in each of these species remains somewhat unresolved.
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Francis, James Nicholas. "Immunomodulation of autoimmune disease using peptides derived from heat shock proteins." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302098.
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D'agata, Stéphanie. "Vulnérabilité des communautés de poissons coralliens aux pressions humaines et importance des sites références pour l'évaluation des outils de conservation." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS067.
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Au-delà de la perte de richesse spécifique, les activités humaines entraînent probablement la diminution de la diversité phylogénétique et fonctionnelle portée par les espèces dans les communautés. Comprendre les effets des activités humaines sur l'ensemble des facettes de la biodiversité liées au fonctionnement des écosystèmes et évaluer les outils de conservation de ces facettes restent des enjeux majeurs de l'écologie notamment en milieu marin. Les objectifs de la thèse sont donc i) d'évaluer les impacts humains sur la diversité des lignées phylogénétiques et des fonctions au sein des communautés de poissons coralliens indépendamment des facteurs environnementaux naturels, ii) d'évaluer la capacité des aires marines protégées à conserver efficacement ces facettes et à produire des valeurs de références pour la gestion des écosystèmes et iii) de mesurer la vulnérabilité fonctionnelle intrinsèque, sans pression humaine, des communautés de poissons. Pour cela nous avons dû échantillonner des sites très isolés des populations humaines à travers l'Indo-pacifique et nous avons utilisé des modèles permettant de prendre en compte les effets de seuil et les interactions pour extraire les effets ‘purs' liés à l'homme. Dans un premier temps, nous montrons, à l'échelle du Pacifique sud-ouest, que le nombre d'espèces des poissons perroquets diminue linéairement mais uniquement de 12% le long d'un gradient d'impact humain alors que les diversités phylogénétiques et fonctionnelles diminuent de 36% et de 47%, respectivement, avec de forts effets de seuil. Dans un deuxième temps, en considérant un gradient d'impact humain et une large gamme d'aires marines protégées (AMPs) en Nouvelle-Calédonie, nous démontrons que les sites très isolés des activités humaines (>20 heures de temps de trajet depuis Nouméa la capitale régionale) possèdent des communautés de poissons avec une plus forte diversité fonctionnelle et biomasses de prédateurs apicaux que la plus grande et plus ancienne AMP intégrale. Finalement, en considérant quatre sites isolés des activités humaines à travers l'Indo-Pacifique, nous avons révélé que la diversité des fonctions portées par les poissons est très vulnérable, 60% n'étant portées que par une espèce, même sans impact humain. Nos travaux montrent la très forte vulnérabilité aux activités humaines des facettes fonctionnelles et phylogénétiques de la biodiversité, avec un manque de capacité des AMPs à restaurer l'ensemble des rôles fonctionnels des poissons et une redondance très limitée pour ces fonctions même dans les sites les plus isolés<br>Beyond species loss, human activity may cause the decrease of phylogenetic and functional diversity carried by species. One of the major issue, particularly in marine ecology, is to understand the effects of human activities on all aspects biodiversity related to ecosystem functioning and assess conservation tools.The objectives of the thesis are i) to assess human impacts on the diversity of phylogenetic lineages and functions within the coral reef fish communities regardless of natural environmental factors, ii) to evaluate the ability of marine protected areas to conserve these facets efficiently and produce baselines values for ecosystem management and iii) to measure the intrinsic functional vulnerability, without human pressure, of fish communities. For this we had sampled very remote sites across the Indo-Pacific and we used statistical tools that take into account thresholds effects and interactions to extract the marginal effect of human activities.First, we show that across the South West Pacific, parrotfish species richness decreases linearly but only of 12% along a gradient of human impact while the phylogenetic and functional diversity decrease of 36% and 47%, respectively, with strong threshold effects. Secondly, considering the human impact gradient and a wide range of marine protected areas (MPAs) in New Caledonia, we demonstrate that very remote sites from human activities (> 20 hours of travel time from Noumea, the regional capital) have greater fish functional diversity and biomass of apex predators than the largest and oldest MPA.Finally, considering four remote sites across the Indo-Pacific, we have found that the diversity of functions carried by fish communities is very vulnerable, showing that 60% of functions were only worn by one species, even without human impact. Our work shows that the functional and phylogenetic aspects of biodiversity are highly vulnerable to human activities, with a lack of ability of MPAs to restore all of the functional roles of fish and a very limited redundancy for these functions even in the most isolated locations
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Pöhlker, Mira [Verfasser]. "Investigation of atmospheric aerosols and cloud condensation nuclei under pristine and polluted conditions / Mira Pöhlker." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/1152029460/34.
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Barker, Amanda J. "Speciation, transport and mobility of metals in pristine watersheds and contaminated soil systems in Alaska." Thesis, University of Alaska Fairbanks, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10240128.
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<p> The fate of metal(loid)s in the environment depends on a variety of physical and geochemical factors. Assessing metal(loid) transport in soil solution and surface water requires detailed knowledge of the speciation, which can often control mobility, toxicity and bioavailability of a given element. The present study details the geochemical analyses of two end member types of systems: a ‘pristine’ Arctic watershed and a military shooting range with an overall focus on understanding lead (Pb) and antimony (Sb) mobility in shooting range soils. The project uses bulk speciation analyses coupled with micro-scale methods to quantify variations in metal(loid) concentration as a function of environmental conditions and characterize metal(loid) speciation and distribution in relation to parent source material in order to understand the impact that metal(loid) retention versus mobilization has on a given system. </p><p> In the Arctic, stream water concentrations of Al, Ba, Fe, and Mn in Imnavait Creek were highest in the late fall (September and October). This pattern appears to correlate with the depth of the active layer throughout the watershed. Increased water infiltration at the permafrost-active layer boundary could significantly impact stream water trace metal(loid) signatures due to mineral weathering of unfrozen soil. In the central Alaskan shooting range, there were significant contributions of Pb and Sb to both the soil and soil solution as a result of the weathering of fragmented bullets. Aqueous concentrations of Sb were higher than Pb in all soil types, indicating Sb is more mobile, despite the fact that bullets introduce approximately two orders of magnitude more Pb than Sb. We observed an association of both Pb and Sb with Fe in soils, which impacts remediation scenarios for ranges as Fe treatments have potential to be effective for system-wide immobilization of major contaminants. Overall, the results from this study highlight the complexity of metal(loid) speciation, transport and mobility as a function of seasonality, soil type and environmental conditions.</p>
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Josefsson, Torbjörn. "Pristine forest landscapes as ecological references human land use and ecosystem change in boreal Fennoscandia /." Umeå : Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200977.pdf.
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Gkotsinas, Anastasios. "On the pristine nature of cometary nuclei : coupled modeling of their thermal and dynamical evolution." Electronic Thesis or Diss., Lyon 1, 2023. http://www.theses.fr/2023LYO10144.
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Les comètes sont une population de petits corps du Système Solaire souvent décrits comme les objets les plus primitifs de notre Système Solaire, détenant des informations précieuses sur sa formation et son évolution. Formées tôt, au même temps que les planètes géantes, dans les parties externes du disque protoplanétaire et dispersées vers l'extérieur peu après leur formation pour être stockées dans des réservoirs lointains et froids, elles sont considérées comme ayant largement conservé leurs propriétés et composition primordiales. Cependant, le niveau de leur nature primitive a commencé à être revu, car un nombre croissant d'observables et d'études théoriques suggèrent la possibilité d'altérations thermiques avant leur retour dans les parties internes du Système Solaire où elles sont généralement étudiées et observées. Dans ce contexte, ce travail vise à examiner le niveau de cette nature primitive pour les différentes familles cométaires de notre Système Solaire. Dans ce but, nous avons développé un modèle d'évolution thermique dédié, conçu pour un couplage efficace aux simulations N-corps qui suivent l'évolution orbitale à long terme des planétésimaux, provenant des parties externes du disque protoplanétaire et évoluant vers des orbites dans la région planétaire, après un séjour prolongé dans les réservoirs extérieurs du système solaire. Nos résultats révèlent la possibilité d'altérations thermiques, affectant principalement le contenu condensé primordial d'hyper-volatiles et dans un second lieu le contenu primordial modérément volatile et la glace d'eau amorphe, au cours des premières phases de la vie des comètes. Une étude comparative indique que les comètes à longue période devraient être la population la moins altérée. Une activité intense, mais sporadique, est également enregistrée dans la région des planètes géantes, alors que les comètes reviennent dans le Système Solaire interne, compatible avec les observables actuelles concernant la population de Centaures. Ces résultats indiquent que l'évolution thermique des noyaux cométaires est inextricablement liée à leur évolution orbitale. Ils indiquent également que l'activité cométaire observée dans les parties internes du Système Solaire provient très probablement de couches déjà altérées, soulignant la nécessité de prendre en compte l'histoire dynamique des comètes lors de l'interprétation des observations actuelles<br>Comets are a population of small Solar System bodies, often described as the most primitive population in our Solar System, holding valuable information on its formation and evolution. Formed early, at the same time as the giant planets, in the outer parts of the protoplanetary disk and scattered outwards shortly after their formation towards distant and cold reservoirs, they are considered to have preserved their primordial composition and properties to a great extent. However, the level of this primitive nature has started to be reevaluated recently, as a growing body of observational evidence and an important number of theoretical studies are suggesting the possibility of thermally-induced alterations before their return to the inner parts of the Solar System, where they are usually studied and observed. In this context, our work aims to examine the level of the primitive nature of different cometary families in our Solar System. To do so, we developed a dedicated thermal evolution model, designed for an efficient coupling to N-body simulations, tracking the long-term orbital evolution of planetesimals, originating in the outer parts of the protoplanetary disk and evolving into planetary-crossing orbits after a prolonged stay in outer Solar System reservoirs. Our results reveal the possibility of thermal processing, affecting mainly the primordial condensed hyper-volatile content and on a lesser extent the primordial moderately-volatile and amorphous water ice content, during the early phases of a comet's lifetime. A comparative study is indicating that long-period comets are expected to be the least altered population. Intense, yet sporadic, activity is also recorded in the planetary region, as comets return in the inner Solar System, compatible with the current observables on the Centaur population. These results indicate that the thermal evolution of cometary nuclei is inextricably related to their orbital evolution. They are also indicating that the cometary activity observed in the inner parts of the Solar System is very likely triggered from thermally processed subsurface layers, highlighting the necessity of considering the past evolutionary history of comets when interpreting the current observations in a broader context
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Gordeev, Georgy [Verfasser]. "Elementary exciton mediated Raman scattering mechanisms in pristine and functionalized single walled carbon nanotubes / Georgy Gordeev." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1189138255/34.
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Fontanesi, Claudio. "An ab-initio theoretical description of vibrational and electronic states in pristine and doped organic semiconductors." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760888.
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This PhD thesis deals with research activity in organic electronics, an extremely exciting field offundamental science, which is complemented by relevant applications in every-day life: optoelectronics,solar energy conversion (photovoltaics), sensing and information technology, just to mentiona few. In this area, charge transfer/energy transfer processes, as well as light matter interaction,play a major role. Within this topic, this work focus on the theoretical study of the electronic structureand related charge transfer/spectroscopic properties of various molecular systems: Coronenecrystals, F4TCNQ/perylene co-crystals, polythiophenes, PCPDT/PCPDT-BT homo- and copolymerbased on thiophene, chemisorbed ferrocene on Si(111) substrate. Particular attention wasdevoted to the calculation of infrared (IR) and electronic spectra associated with the so-called “polaronsignature” in doped organic semiconductors. To assess the reliability and physical meaning of electronic quantities involved in the calculations(like the HOMO/LUMO gap, theoretical spectroscopic intensity and vibrational modes, pursuingthe comparison between neutral and charged systems) a number of different levels of the theoryhave been systematically varied from HF (Hartree-Fock) to “pure” DFT (Density Functional Theory),as well as hybrid B3LYP (Becke 3-Parameter (Exchange), Lee, Yang and Parr 1,2) and longrange corrected Coulomb-Attenuating Method (CAM-B3LYP) functionals. In the attempt to untanglethe physics underlying the polaron formation in charged molecular systems (as evidenced by theoccurrence of giant intensity bands found in IR spectra), the mapping of the vibrational mode betweenneutral and charged systems has been calculated. A major achievement in this work is thatthe vibrational (giant) mode associated with the “polaron” emerges as a new mode (peculiar of thecharged state) not related to any mode existing in the neutral system.
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Samson, Heidi E. (Heidi Estrelita). "Psychrotolerant mucoralean fungi present in pristine mountain fynbos soil and vineyard soil from the Stellenbosch region." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52423.
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Thesis (MSc)--University of Stellenbosch, 2001.<br>ENGLISH ABSTRACT: Mucoralean fungi are mostly saprotrophs that are frequently encountered in soil
habitats. Using an isolation temperature of circa 25°C, other workers obtained
these fungi from a wide diversity of geographical areas in southern Africa.
However, it is known that psychrotolerant mucoralean fungi, able to grow at
25°C as well as at 5°C, occur in pristine Alti Mountain Grassland. Nothing is
known about the diversity of these psychrotolerant soil fungi in other vegetation
types of South Africa.
Consequently, in this study, the psychrotolerant fungal taxa and numbers in soil
from a vineyard and from pristine Mountain Fynbos were determined using an
incubation temperature of 4°C and a complex isolation medium. The latter
contained agar, malt extract, peptone, yeast extract, penicillin and streptomycin
sulphate. Soil samples were analysed in late summer, autumn and mid-winter.
It was found that, for the samples taken in late summer and autumn, the
diversity of mucoralean species in the soil differed between fynbos and
vineyard. In winter however, no significant difference was detected between the
Shannon's diversity indices of mucoralean species in the soil samples taken
from the two habitats. It was found that in both soil types, the percentage
mucoralean fungi on the plates increased from summer to winter. In addition,
the numbers of detectable Morlierella subgenus Morlierella on the plates were
higher in winter than in late summer. The diversity of mucoralean species
obtained during winter in fynbos and vineyard soil was significantly less than the
diversity of these species in Alti Mountain Grassland soil.
To determine if the Morlierella subgenus Morlierella isolates from the fynbos
and vineyard soil, and those obtained from Alti Mountain Grassland, differ in the
ability to grow at low temperatures, the radial growth rate on malt extract agar at
4°C and BOC was determined for each isolate. The results indicate that not only
did seasonal changes occur in the taxa within Morlierella subgenus Morlierella,
but that the isolates dominating the soil in different seasons also differed in the
ability to grow at low temperatures. The percentage of isolates that had
reached greater colony diameters after B days of incubation at 4°C, was higher for the isolates obtained in the cold wet month of July than for those obtained in
the warmer dryer month of February. Similar results were obtained with the
radial growth experiments conducted at BOC. The Morlierella subgenus
Morlierella isolates obtained in winter from fynbos and vineyard soil showed
less variation in low temperature growth rate than the isolates of this taxon
obtained in winter from Alti Mountain Grassland soil during a previous study.
This variation corresponds to the greater number (20) of Morlierella subgenus
Morlierella species found in the grassland soil. Altogether only seven species
of this subgenus was detected during the present study in the fynbos and
vineyard soil samples. It was speculated that this difference in diversity
between the fynbos and vineyard isolates, and the grassland isolates obtained
in a previous study, might have been as a result of differences in the habitat or
the enumeration methods used.
The phylogenetic relationship between different psychrotolerant isolates of
Morlierella subgenus Morlierella originating from the soil of the fynbos, vineyard
and Alti Mountain Grassland, was subsequently determine through comparison
of ITS regions, within ribosomal RNA repeats. Consequently, 45
psychrotolerant Morlierella subgenus Morlierella isolates originating from the
three soil habitats was compared on the basis ITS 1 nucleotide sequence
composition and radial growth rate at 4°C. Phylogenetic analyses showed that
the isolates could be grouped into two clusters correlating with the ability to
grow at low temperatures. Each cluster was further subdivided into two
subgroups. It was found that except for one subgroup and the reference strain
occurring in another subgroup, all the subgroups contain isolates originating
from a single soil habitat. Therefore, the ITS 1 sequence of these fungi seems
to indicate the original habitat and ability to grow at low temperatures. This
correlation of the ITS sequence with the ecological habitat of a fungus has also
been observed by other workers for other fungal groups.<br>AFRIKAANSE OPSOMMING: Mucoraliese fungi is meestal saprotrofe wat dikwels in grondhabitatte aangetref
word. Deur gebruik te maak van 'n isolasietemperatuur van circa 25°C, het
ander werkers dié fungi van 'n wye verskeidenheid geografiese gebiede in
suidelike Afrika verkry. Dit is egter bekend dat die psigrotolerante mucoraliese
fungi, wat in staat is om by 2SoC en ook by SaC te groei, in ongeskonde Alti
Berg-Grasland voorkom. Niks is egter bekend oor die diversiteit van dié
psigrotolerante grondfungi in ander veldtipes van suidelike Afrika nie.
Die psigrotolerante fungustaksa en -getalle in grond van 'n wingerd en van
ongeskonde Berg Fynbos is gevolglik in dié studie bepaal deur gebruik te maak
van 'n inkubasietemperatuur van 4"C en 'n komplekse isolasiemedium.
Laasgenoemde het agar, moutekstrak, peptoon, gisekstrak, penisillien en
streptomisiensulfaat bevat. Grondmonsters is in die laatsomer, herfs en
midwinter geanaliseer. Daar is 'n verskil gevind tussen die diversiteit van die
mucoraliese spesies in die grond van fynbos en dié van wingerd in die monsters
wat in die laatsomer en midwinter geneem is. In die winter is daar egter geen
beduidende verskil gevind tussen die Shannon diversiteitsindekse van
mucoraliese spesies in die grondmonsters wat uit die twee habitatte getrek is
nie. In albei grondtipes is daar gevind dat die persentasie mucoraliese fungi op
die plate toegeneem het van somer tot winter. Daarby was die aantal
waarneembare Morlierella subgenus Morlierella op die plate meer in die winter
as in die laatsomer. Die diversiteit van mucoraliese spesies wat in die winter uit
fynbos- en wingerdgrond verkry is, was beduidend minder as die diversiteit van
dié spesies in Alti Berg-Grasland grond.
Om te bepaal of die Morlierella subgenus Morlierella isolate van die fynbos- en
wingerdgrond en dié van Alti Berg-Grasland van mekaar verskil ten opsigte van
hul vermoë om by lae temperature te groei, is die radiale groeitempo op
moutekstrak by 4"C en aoc vir elke isolaat bepaal. Die resultate dui aan dat
daar nie alleen seisoenale veranderinge in die taksa binne Morlierella subgenus
Morlierella voorkom nie, maar dat die isolate wat tydens verskillende seisoene
uit die grond verkry is, ook ten opsigte van hul groeivermoë by lae temperature van mekaar verskil. Die persentasie isolate wat groter kolonie diameters bereik
het ná B dae inkubasie by 4°C, was hoër vir die isolate van die koue, nat
Juliemaand as vir dié wat in die warmer en droër Februariemaand verkry is.
Soortgelyke resultate is verkry met radiale groei-eksperimente wat by BOC
gedoen is. Die MortierelIa subgenus MortierelIa isolate wat in die winter uit
fynbos- en wingerdgrond verkry is, het In kleiner variasie in hul groeitempo by
lae temperature getoon as die isolate in dié takson wat tydens 'n vorige studie
in die winter uit Alti Berg-Grasland grond verkry is. Dié variasie stem ooreen
met die groter aantal (20) MortierelIa subgenus MortierelIa spesies wat in die
graslandgrond gevind is. Slegs sewe spesies van dié subgenus is gedurende
die huidige studie in die fynbos- en wingerdgrondmonsters waargeneem. Daar
is gespekuleer dat dié verskil in diversiteit tussen die fynbos- en wingerdisolate
en die graslandisolate van die vorige studie die gevolg mag wees van verskille
tussen die habitat of die enumerasiemetodes wat gebruik is.
Die filogenetiese verwantskap tussen verskillende psigrotolerante isolate van
MortierelIa subgenus MortierelIa uit die grond van die fynbos, wingerd en Alti
Berg-Grasland, is vervolgens bepaal deur 'n vergelyking van interne
getranskribeerde spasieerder (ITS) areas, binne ribosomale RNS herhalings.
Daar is gevolglik 45 psigrotolerante MortierelIa subgenus MortierelIa isolate uit
die drie grondhabitatte met mekaar vergelyk op grond van die basis ITS 1
nukleotied opeenvolgingsamestelling en radiale groeitempo by 4°C.
Filogenetiese analises het die isolate in twee groepe verdeel op grond van hul
vermoë om by lae temperature te groei. Elke groep is verder in twee subgroepe
verdeel. Daar is gevind dat behalwe vir een subgroep en die verwysingstam
wat in 'n ander subgroep voorgekom het, elkeen van die subgroepe bestaan het
uit isolate wat van 'n enkele grond habitat verkry is. Dit wil dus voorkom of die
ITS 1 opeenvolging van dié fungi 'n aanduiding gee van die oorspronklike
habitat en die vermoë om by lae temperature te groei. Dié korrelasie tussen die
ITS opeenvolging en die ekologiese habitat van 'n fungus is ook deur ander
werkers vir ander fungusgroepe waargeneem.
47
Smit, A. K. "Geochemistry of a pristine fynbos ecosystem in the Harold Porter National Botanical Gardens and Kogelberg Biosphere Reserve." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/4221.
Full textAbstract:
Bibliography: leaves 79-83.<br>Water, soil and rock samples were taken from the Harold Porter National Botanical Gardens and the Kogelberg Biosphere Reserve in order to investigate interactions between the various nutrient pools in a pristine fynbos ecosystem. Physical variables (pH, EC, temperature, DO, alkalinity) were measured in the field, and water samples were collected and analysed for chemical composition. Chemical composition and mineralogy of soil and rock samples from the Peninsula, Cedarberg and Goudini formations were determined to assess the influence of parent geology on soil chemistry. The surface water chemistry in the study area was remarkably homogeneous, with only major ions Na, CI, Mg, Ca, Si and S04 exceeding concentrations of 1 ppm at any of the sample sites. Concentrations of other major ions AI, K, NH4, N03 and Fe ranged between 0.1 and 0.7 ppm. The minor and trace elements B, Sb, Sr, Zn and Mn were present in concentrations greater than 1 ppb. Compared to the seawater chloride ratio, Na, Mg, K and S04 were depleted in the streams relative to CI, showing that these elements are preferentially accumulated and are conserved within the fynbos ecosystem. In contrast, CalCI ratio is elevated in streams, indicating an external source of Ca other than the seawater. This source may be windblown dust. The Fe content of soils appears to be lower than that of the parent bedrock, especially in the case of the iron-rich Goudini Formation. This indicates an as yet undetermined pathway for iron to leave the system, which may be through deeper anoxic groundwaters in the area. Only one site from the Oudebosch River headwaters showed significant deviation from other sites in several of the elemental trends, and also had no measurable DOC content, compared to the other sites which ranged from 10 to 16 mg/L DOC. These differences are probably the result of the different vegetation (afromontane forest as opposed to fynbos) and geological setting (clay rich, Cedarberg Formation soils). Soils contained higher concentrations of water-soluble ions than the streams, and organic carbon content ranges from 6 to 34 wt%. Organic 0 horizons and Melanic/Humic A horizons constituted the major soil types. Cation exchange capacities of the soil samples ranges between 31.3-93 mmolJkg, and about half of the soil samples were determined to be acid saturated and fairly leached of ions, probably due to the high rainfall. The soil composition and mineralogy correlate well with that of the underlying bedrock, and was dominated by quartz, with some clays, micas, feldspars and hematite. The study was similar to one in the Cedarberg, which has the same geological setting and equal fynbos species richness. This is the first integrated geochemical study to characterise the pristine fynbos biome of the Harold Porter National Botanical Gardens and the Leopards Gorge River Catchment, and will allow rapid assessment of any future changes.
48
Pfannerstill, Eva Yvonne [Verfasser]. "Total OH reactivity in pristine and polluted environments: Investigating atmospheric chemistry in the Anthropocene / Eva Yvonne Pfannerstill." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/1199367737/34.
Full text
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Santos-Caton, Ingrid R. Schneegurt Mark A. "Abundance of nifH genes in urban, agricultural, and pristine prairie streams exposed to different levels of nitrogen loading." Diss., A link to full text of this thesis in SOAR, 2007. http://soar.wichita.edu/dspace/handle/10057/1118.
Full textAbstract:
Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences.<br>"May 2007." Title from PDF title page (viewed on Dec. 4, 2007). Thesis adviser: Mark A. Schneegurt. Includes bibliographic references (leaves 63-72).
50
Schulz, Christiane [Verfasser]. "Secondary organic aerosol in the pristine Amazonian atmosphere: chemical properties, formation pathways, and interactions with clouds / Christiane Schulz." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/1185711856/34.
Full text