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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Coastal dune dynamics and management at the Bushman's River mouth, Kenton-on-Sea

Fraser, Claire January 2005 (has links)
A study of the dynamics and functions of a coastal dunefield at the Bushman’s River Mouth in Kenton-on-Sea was conducted to provide essential information for the formulation of a management strategy based on an ecosystem approach. Bi-monthly tacheometric surveys were undertaken at the Westbourne Road Car Park dunefield to investigate the sedimentological processes. Changes in the topography, the amount and rate of sand accretion were monitored. Accretion and progradation were the dominant long-term sedimentological processes at the site. Long-term spatial variation in these processes corresponded to the temporal pattern of sedimentation in the river mouth while short-term variation resulted from dynamics inherent to the types of dunes present. Factors affecting aeolian accretion at the site are topography, river mouth configuration, dune types and the presence of vegetation as well as the seasonal wind regime. A vegetation study, recording species present, cover and abundance of the plants along the surveyed transects, was also conducted to examine the progressive establishment of vegetation. Five plant communities were discerned namely, saltmarsh, pioneer, enriched pioneer, open scrub, closed scrub and scrub-thicket communities. The spatial distribution of these communities coincided with the north-westerly development of the sandbank. A successional trend in community change occurred along a gradient of increasing diversity, complexity and age. Initially, autogenic changes wrought by pioneer species facilitated the recruitment and survival of other species and commenced succession at the study site. Multiple successional pathways were discussed in relation to subsequent species establishment that occurred after facilitation. The amalgamation of ecological data with a social study in the form of public perception surveys allowed for a greater understanding of the present interactions between the ecosystem and the demands placed on it. The area primarily functions as a recreational site that offered numerous beach and water-related activities. A lack of information regarding the ecology and management programmes influenced public perception of the environment and management issues in general. Different management perspectives and the use of the information presented in this study were also discussed.
122

Ecosystem health of the Nelson Mandela Bay sandy beaches

Yani, Vuyolwethu Veronica January 2009 (has links)
An investigation of ecosystem functioning of sandy beaches in the Nelson Mandela Bay Municipality (NMBM) was carried out with the aim of describing their type and pollution status. Water salinity, temperature, pH, beach slope, water inorganic nutrient concentrations, urea, and chlorophyll-a concentration as well as the composition of zooplankton, phytoplankton, meiofauna, benthic microalgae and bacteria were examined at thirteen beaches. The beaches were classified into three types: short beaches; long beaches with surf diatoms; and long beaches that import biomass (without surf diatoms). Of the thirteen beaches, five were non-polluted and eight polluted with polluting human activities in and around them. Most beaches were dominated by fine sand except for St. Georges Strand where the particles were medium to fine sand and Maitland’s River Beach, Bluewater Bay and Sardinia Bay that had coarse sand. Nutrient concentrations ranged from 1.98 ± 0.10 μM to 19.30 ± 3.02 μM nitrate; 4.88 ± 1.00 μM to 11.97 ± 1.00 μM ammonium; 0.67 ± 0.00 μM to 2.31 ±1.00 μM soluble reactive phosphorus; and 0.00 to 0.03 ± 0.00 μg l-1 urea-N. Chlorophyll-a concentrations ranged from 0.04 ± 0.02 to 1.57 ± 0.11 μg l-1. Chlorophyll-a concentrations were negatively correlated to ammonium for all beach types (short beaches: r = 0.94; long importing beaches: r = 0.95 and surf diatom beaches: 0.94) and to nitrate for short and long importing beaches (short: r = 0.97 and long importing: r = 0.85). By contrast, a positive correlation was found between observed between chlorophyll-a concentrations and urea for surf diatom beaches (r = 0.93) and for long importing beaches (r = 0.73). Chlorophyll-a concentrations were negatively correlated to short beaches (r = 0.99) and long importing beaches (r = 0.76). The E. coli and total coliforms in all the sampled beaches were within the recommended South African water quality guidelines for contact recreation as specified by DWAF (1995) except at New Brighton Beach (2 419 total coliforms/100 ml and 1 853 E. coli cells/100 ml) and St. Georges Strand (274 total coliforms/100 ml). Diatoms dominated the phytoplankton and benthic microflora; calanoid copepods dominated the zooplankton and deposit-feeding nematodes dominated the meiofauna in all the beaches with no changes found at polluted beaches.
123

Geomorfologia e geologia do quaternário da planície flúvio-eólica do Médio rio São francisco, NE do brasil /

Santos, Landerlei Almeida. January 2020 (has links)
Orientador: Edgardo Manuel Latrubesse / Resumo: Compreender a evolução paleoclimática do Quaternário na região Nordeste do Brasil (NEB) é parte fundamental para entender como tem funcionado a circulação atmosférica na faixa tropical da América do Sul. Nesse contexto, o campo de dunas eólicas estabilizadas do Médio Rio São Francisco é um “geoproxy” de grande potencial principalmente por fornecer informações sobre o comportamento dos paleoventos durante os estágios de formação e desenvolvimento das dunas eólicas presentes nesta região. A magnitude e tipo das dunas arenosas presentes neste campo eólico são características particulares desta área em relação a outros registros eólicos da América do Sul tropical. Assim, o principal objetivo deste trabalho é propor um modelo de organização espacial dos padrões eólicos predominantes, inferir mecanismos de desencadeamento e expansão do campo de dunas, e contribuir com o entendimento paleoclimático do NEB a partir de resultados de datações por luminescência optica dos principais padrões de dunas eólicas integrados com outros dados proxies da região. Baseado na combinação de métodos de sensoriamento remoto, morfoestratigrafia e datação por luminescência óptica, definimos as unidades morfosedimentares do campo eólico e, secundariamente, da planície aluvial do Rio São Francisco. Devido a pouca informação de subsuperfície, analisamos dados prévios da planície flúvio-eólica com objetivo de entender a estruturação do arcabouço no qual ocorreu a expansão do campo eólico. Usamos mapa prévio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The paleoclimatic knowledge of the Quaternary period of Northeastern Brazil (NEB) is key to understanding how atmospheric circulation has worked in the tropical zone of South America. In this context, the inactive dune field in the Middle São Francisco River is a “geoproxy” of great potential mainly because it provides information on the behavior of paleowinds during the formation and development stages of the aeolian dunes present in this region. The magnitude and type of sandy dunes present in this dune field are particular characteristics of this area in relation to other wind records in tropical South America. Thus, the main objective of this work is to propose a model of spatial organization of the prevailing aeolian patterns, to infer mechanisms of triggering and expansion of the dune field, and to contribute to the paleoclimatic understanding of NEB from results of dating by optical luminescence of the main patterns aeolian dunes integrated with other proxies data from the region. Based on the combination of remote sensing, morphostratigraphy and optical luminescence dating, were define the morphosedimentary units of the dunefield, and secondarily of the alluvial plain of the São Francisco River. Due to scarcity of subsurface information, we analyzed previous data from the fluvial-aeolian plain in order to understand the structure of the framework in which the expansion of the dunefield occurred. Were used a previous map derived from magnetic anomaly data, sedimentary ... (Complete abstract click electronic access below) / Doutor
124

Dunes and dune movement in the Walvis Bay area of Namibia, and implications for future land-use planning and development

Soboil, Jeremy Hirsch January 1996 (has links)
Bibliography: pages 144-155. / Dunes are an integral part of the Walvis Bay environment. Their dynamics significantly influence the functioning of the coastal system and have major implications for both the ecological and socio-economic environments. In light of residential, commercial and industrial requirements for the Walvis Bay area, dune encroachment needs to be seriously considered in the future planning of land-use and resource utilisation. The overall objective of this report, therefore, is to provide a better understanding of the dominant role dunes and sand drift play in the study area and in so doing promote the more judicious future planning and management of the region. In order to achieve this aim, several specific objectives were addressed, these being: to identify and clarify all dune types occurring in the study area, and discuss the geomorphological and ecological characteristics of each; to provide an analysis of the long-term stability of dunes in the Walvis Bay area by means of aerial photograph interpretation; to highlight all factors that contribute to dune encroachment and to assess the ramifications of this movement upon the ecological and socio-economic environments; * to emphasise elements that need to be considered with any future planning of land-use and development; * to review dune management practices in the Walvis Bay area and provide recommendations for the more effective management of the system in the future.
125

På tröskeln mellan världar : Fiktiv paratext i Frank Herberts Dune och Ursula K. Le Guins Four Ways to Forgiveness / On the Threshold Between Worlds : Fictional Paratext in Frank Herbert's Dune and Ursula K. Le Guin's Four Ways to Forgiveness

Rovio, Andreas January 2023 (has links)
No description available.
126

Populationsgröße, Trichterdichte und Habitatpräferenz der Dünen-Ameisenjungfer Myrmeleon bore (Tjeder, 1941) im Gebiet der Dresdner Heide (Neuroptera)

Anselmi, A. C. M., Gallon, S. C. E., Müller, P., Reinhardt, K. 04 November 2022 (has links)
Nach dem Erstnachweis von Myrmeleon-Bohrungen (Tjeder, 1941) in der Dresdner Heide im Jahr 2019 (KURTH 2020, Sächs. Entomol. Z. 10: 71-80) wurde die Populationsgröße und Dichte der Art bestimmt. M. bore wurde hauptsächlich in offenen, spärlich bewachsenen, sandigen Gebieten mit direkter Sonneneinstrahlung gefunden. Die flächengewichtete Dichte des gesamten Untersuchungsgebietes (4,05 Hektar) betrug 0,177 Larven/m2. Schätzungen der Populationsgröße basierend auf zufälligen Quadratzahlen führen zu einer Zahl von 4000-7000 Individuen - die größte bekannte Population dieser Art. Die für diese Art aus Laborversuchen bekannte positive Korrelation zwischen Larvengröße und Grubendurchmesser wurde an unserem Studienstandort bestätigt. Diese Korrelation könnte es Forschern ermöglichen, die Altersstruktur von Wildpopulationen abzuschätzen. Angesichts der besonderen Verantwortung Deutschlands für den Schutz dieser Art und der Größe der Population fordern wir den Schutz des Gebietes und eine Priorisierung gegenüber anderen geschützten Arten in diesem Gebiet. / Following the first record of Myrmeleon bore (Tjeder, 1941) in the Dresden Heath area in 2019 (KURTH 2020, Sächs. Entomol. Z. 10: 71-80), the population size and density of the species was determined. M. bore mainly was found in open, sparsely vegetated, sandy areas with direct sunlight exposure. The area-weighted density of the entire study site (4.05 hectares) was 0.177 larvae/m2. Population size estimates based on random quadrat counts lead to a figure of 4000-7000 individuals - the largest known population of this species. The positive correlation between larval size and pit diameter known for this species from laboratory trials was confirmed at our study site. This correlation may allow researchers to estimate the age structure of wild populations. Given the special responsibility of Germany for the protection of this species and the size of the population, we urge the protection of the site and a prioritisation over other protected species found in the area.
127

Women of the future : gender, technology, and cyborgs in Frank Herbert's dune

Evans, Carrie Lynn 24 April 2018 (has links)
Cette thèse défend les mérites d’une lecture cyborgienne de l’oeuvre de science-fiction de Frank Herbert, Dune, où la vision particulière des sciences et technologies nous permet d’interpréter plusieurs personnages en tant que réitération Nouvelle Vague du cyborg. Publié en 1965, Dune introduit des personnages féminins atypiques pour cette époque compte tenu de leurs attributs tels qu’une capacité intellectuelle accrue, une imposante puissance de combat et une immunité manifeste contre la faiblesse émotionnelle. Cependant, le roman reste ambivalent en ce qui concerne ces femmes : en dépit de leurs qualités admirables, elles sont d’autre part caractérisées par des stéréotypes régressifs, exposants une sexualité instinctive, qui les confinent tout au mieux aux rôles de mère, maitresse ou épouse. Finalement, dans le roman, elles finissent par jouer le rôle du méchant. Cette caractérisation se rapproche beaucoup de celle du cyborg femelle qui est d’usage courant dans les productions de science fiction pour le grand public des décennies plus récentes. Par conséquent, cette thèse défend qu’une lecture cyborgienne de Dune complète et accroisse une analyse sexospécifique, car cette approche comporte une théorisation essentielle des réactions à l’égard de la technologie qui, selon Evans, sont entretissées dans la réaction patriarcale de ce roman à l’égard des femmes. Bien que ces créatures fictives ne soient pas encore communes à l’époque de la rédaction de Dune, Jessica et certains autres personnages du roman peuvent néanmoins être considérés comme exemples primitifs des cyborgs, parce qu’ils incarnent la science et la technologie de leur culture et qu’ils possèdent d’autres éléments typiques du cyborg. L’hypothèse propose que la représentation des femmes dans Dune ne découle pas seulement de l’attrait pour le chauvinisme ou la misogynie, mais qu’elle est en fait grandement influencée par la peur de la technologie qui est transposée sur la femme comme c’est couramment le cas dans la littérature cyborg subséquente. Ainsi, ce roman annonce le futur sous-genre cyborg de la science-fiction. / Evans argues for the merits of a cyborgian reading of Frank Herbert’s seminal science fiction novel, Dune, on the basis that the novel’s particular conception of science and technology allows many of the characters to be understood as New Wave iterations of the cyborg. First published in 1965, Dune includes female characters uncharacteristic for the genre during this period due to the degree of their intelligence, formidable fighting powers, and seeming freedom from emotional weakness. However, the novel is ambivalent about its super-women: despite their admirable qualities, they are otherwise depicted in retrogressive stereotypes, representing the instinctual sex, naturally best limited to roles of mothers, lovers, and wives; by the novel’s conclusion they are cast as villains. This particular characterization of women shares many qualities with the trope of the female cyborg that becomes common in mass media science fiction of later decades. Therefore, this thesis argues that a cyborgian reading of Dune complements and augments a gender analysis of the novel because this approach incorporates an essential theorization of the reactions to technology that, according to Evans, are interwoven into the novel’s patriarchal response to women. Although these fictional creatures were not yet common at the time of Dune’s writing, Jessica and other characters in the novel can be read nonetheless as early examples of cyborgs because they physically embody their culture’s science and technology, and are consistent with other important hallmarks of the figure. The argument is that Herbert’s depiction of women in Dune does not just arise from an appeal to male chauvinism and misogyny, but is, in fact, strongly influenced by a fear of technology that is projected onto women, as is commonly seen in later cyborg literature. According to such a reading, the novel foreshadows the later cyborg sub-genre of science fiction.
128

The effects of dune stabilization on the spatiotemporal distribution of soil moisture resources, Northern Great Plains, Canada

Koenig, Daniel Edgar January 2012 (has links)
In dryland environments, the availability of soil moisture is the primary control on plant species’ distributions. In the sandhill regions of the northern Great Plains, vegetation establishment has transformed highly mobile, desert-like dune fields into stabilized landscapes covered by mixed-grassland prairie. This study examines how dune stabilization has modified the spatiotemporal distribution of soil moisture resources. An ergodic (space-for-time) approach was used, comparing soil moisture dynamics on active and vegetation-stabilized dunes in the Bigstick Sand Hills of southwestern Saskatchewan. Results indicate that while dune stabilization has enhanced near-surface soil moisture availability, deeper profile soil moisture recharge is reduced. Through better understanding how vegetation has modified soil moisture dynamics in stabilizing sandhill regions, better management practices may be implemented to maintain water resource availability and ecosystem health. / xii, 97 leaves : ill., maps ; 29 cm
129

Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa / Investigation of the relationship between morphology, patterns and processes in a headland bypass dunefield, in the Eastern Cape, South Africa

McConnachie, Lauren Bernyse January 2013 (has links)
Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed / Maiden name: Elkington, Lauren
130

Sedimentology of a Grain-Dominated Tidal Flat, Tidal Delta, and Eolianite System: Shroud Cay, Exumas, Bahamas

Petrie, Maaike 01 January 2010 (has links)
Sedimentary characteristics of grainy non-skeletal tidal flats along windward platform margins have not been described in modern environments and may be misidentified or misclassified in the rock record. This study describes the sedimentology of such an environment to aid in accurate identification and characterization in the ancient. At Shroud Cay, a grain-dominated tidal flat is sheltered from the high energy of the shelf by a ring of cemented Pleistocene and partly indurated Holocene eolianite islands separated by several narrow tidal passes. Depositional texture, environment of deposition and geobody mapping, extensive sediment sampling, and vibracoring have shown that, though the cemented island provide a barrier from the high energy of the shelf, a high degree of tidal energy still occurs behind this barrier as indicated by the overwhelmingly grainy nature of all of the tidal flat sub-environments. Intertidal flats comprise the majority of the tidal flat surface. These flats are characterized by patchy Scytonema mats overlying bioturbated peloid-ooid grainstones to packstones with cemented lithoclasts. Three main tidal channels dissect the tidal flat and allow diurnal flow, one of those tidal channels does not exit the tidal flat but dead-ends behind a cemented Holocene beach dune ridge along the eastern side of Shroud Cay. Peloid-ooid-skeletal grainstone tidal bars and peloid-ooid packstones fill much of the channels. Most of the channels are bordered by low-relief grain-rich packstone levees often capped by red mangroves and algal mats. The interior-most supratidal parts of the flat, often in the lee of the windward Holocene ridge, are covered by a thick (5-~25cm) Scytonema microbial mat underlain by grain-rich ooid-peloid packstones. Ancient grain-dominated carbonate tidal flats and eolianite deposits like Shroud Cay?s are the reservoir rocks in some of today?s largest hydrocarbon fields. We develop a model for the evolution of the grain-dominated tidal flat, document and compare differences between the grain-rich tidal flat and surrounding environments of deposition, and develop a set of criteria for recognition. These criteria can be used to more accurately characterize reservoirs such as the Jurassic Smackover fields, to avoid mis-classification of similar settings, and more effectively produce those reservoirs.

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