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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.
11

How do African ElephantsUtilize the Landscape DuringWet Season? : A Habitat Connectivity Analysis for Sioma Ngwezi Landscape in Zambia

Chibeya, Doubt January 2019 (has links)
How environmental factors influence distribution and persistence of African elephants(Loxodonta africana) is pertinent to policy makers and managers to formulate balanced plansfor different landuse types (i.e. wildlife management, forestry). The study focuses on movementof elephants and how they utilize foraging areas in Sioma Ngwezi landscape in Zambia. Theanalysis was based on telemetry data (global position system radio collars) acquired from 8elephants (5 matriarchs and 3 bulls) between February and July in 2018. The followingenvironmental variables were analysed; land cover, topographic wetness index, normalizeddifference vegetation index, proximity to roads and proximity to settlements. MaximumEntropy (MaxEnt) and linkage mapper were the novel tools used to predict habitat suitability,movement corridors and barriers in the landscape during the wet season. Landscapepermeability and habitat suitability were explored by using resistance raster. The studyidentified elevation, land cover and Normalized Difference Vegetation Index (NDVI) as themost important environmental predictors that modifies the dispersal of elephants in thelandscape during the wet season. Additionally, a total of 36 potential wet season corridors wereidentified connecting 15 core areas mainly used for foraging and protection from poachers inthe landscape. Of these, 24 corridors were highly utilized and are suggested as priority corridorsfor elephant movement in the landscape. The identified wet season habitats and functionalcorridors may help to combat elephant poaching by patrolling areas with high relativeprobability of elephant presence. The findings may also help abate human elephant conflictsuch as crop raiding by managing identified corridors that run into agriculture zones in the gamemanagement area. Finally, management of these corridors has massive potential to increasemovement of elephants in the region especially since Sioma landscape is strategically locatedin the Kavango-Zambezi Trans-frontier Conservation Area (KAZA TFCA) connecting thesource (Hwange, Chobe and Bwabwata national parks) and the sink (the Greater Kafue andLuangwa ecosystems) linking elephants from Zambia, Zimbabwe, Angola, Namibia and Botswana.
12

The Search for Life on Mars - Preparation for Sample Return

Hode, Tomas January 2005 (has links)
<p>The purpose of the thesis work has been to develop methods and concepts to aid in the search, detection and assessment of ancient microfossils here on Earth as a guide to the search for ancient life on Mars. The intention has been to identify and characterize environments on Earth that may be considered analogous to Martian environments and in which fossil preservation is expected to be good, and to develop and apply methods to characterize the isotopic and chemical composition of possible traces of life in order to assess their biogenicity and biological affinities.</p><p>An investigation of the Siljan impact structure, Sweden, demonstrated that niches for thermophilic organisms were created in the associated hydrothermal system. The temperature regimes were favorable for thermophilic life in the outer parts of the structure during the early and main stages of the hydrothermal system, but that these niches moved toward the center of the crater during the final cooling stages. It was demonstrated that the hydrothermal system contains traces of a thermophilic microbial community, represented by fossilized extracellular polymeric substances (EPS). Given the presence of water on Mars, similar impact-induced hydrothermal systems were probably generated on Mars as well. These regions, like those at Siljan, may have supported hyperthermophilic microbial communities on the red planet, emphasizing the relevance of searching for impact-induced hydrothermal deposits for evidence of microbial life on Mars.</p><p>A method for the determination of stable carbon isotopes with high lateral resolution of TEM (transmission electron microscopy) samples has been developed. The method is based on alpha-particle Rutherford backscattering (RBS), it is non-destructive, and therefore suitable for analysis of extraterrestrial and other rare or irreplaceable material. Also, a novel concept to extract fluid inclusions without ablating the sample has been proposed, and a proof-of-concept has been demonstrated. The purpose is to analyze organic biomarkers trapped in fluid inclusions without risking contamination, and also to extract and analyze single fluid inclusions. The minimized contamination risk and the potential to extract single fluid inclusions could make the method a useful tool in the search for organic biomarkers in early-Earth material, and eventually, in samples returned from Mars.</p>
13

The influence by point sources on carbon, nitrogen and metals in two sedimentary environments

Bohlin, Hanna January 2005 (has links)
<p>Sediments in two aquatic environments have been investigated. Both are anthropogenically affected and polluted. The focus has been on stable carbon and nitrogen isotopes, C/N ratios, and heavy metals. </p><p>The first site is Höggarnsfjärden Bay in the inner parts of the Stockholm Archipelago, Sweden, where a garbage dump releases treated leach water. The effect on carbon and nitrogen in the sediment close to the discharge is large, but 1200 m downstream the effect is diluted by the background discharge of the town of Stockholm and the Lake Mälaren, which drains into the archipelago. The main source of the studied metals is not the garbage dump itself. The sediment close to the discharge shows high enrichment factors due to high sedimentation rate and adsorption, and low decomposition of organic matter. The metal enrichment factors of downstream sites are not higher than the upstream sites. </p><p>The second site is Lake Verkasjön close to the north part of Lake Vättern, in the county of Örebro, Sweden. River Salaån flows through Lake Verkasjön on the way through a former mining area to Lake Vättern. Upstream of Lake Verkasjön an ore dressing plant site was used in 1877-1881 for extraction of zinc. During that period the sediment of Lake Verkasjön received high loadings of sulphidic tailings. Normal sedimentation after the event has lead to that the polluted sediment is found as a distinct layer at 18-22 cm. The layer is characterized by elevated metal concentrations, decreased organic matter content and increased stable carbon composition. The sediment that has accumulated above 18 cm works as a physicochemical barrier that seals the waste from the overlying sediment. At the time of the event the signal of aquatic production in the sediment changed; the sediment above the layer has an increased proportion of aquatically produced material, implying changed land use in the catchment area.</p>
14

Environmental and climatic changes in the Baltic Sea and the eastern Mediterranean Sea : as recorded by pigments and isotopes in sediments

Borgendahl, Johanna January 2006 (has links)
<p>This thesis is a study of Holocene sapropels from two semi-enclosed seas; the Baltic Sea and the Mediterranean Sea. Sapropels are sedimentary layers with organic C > 2%. The Baltic Sea and the Mediterranean Sea have a limited water exchange, and despite differences in water depth and salinity, mechanisms for fluxes and preservation of C<sub>org</sub> are principally the same. Primary focus is on biomarkers for increased primary productivity and anoxic/euxinic bottom water. Pigments (primarily from cyanobacteria), δ<sup>15</sup>N, δ<sup>13</sup>C, N and C<sub>org</sub> have been used for studying increased primary productivity. Presence of the pigment isorenieratene from green sulphur bacteria indicates photic zone anoxia. Zn, Mn and δ<sup>34</sup>S have also been used to identify different scenarios during sapropel formation.</p><p>Pigments start to appear at the beginning of both the Baltic Sea sapropel and S1, the Holocene sapropel in the Mediterranean Sea. Cyanobacterial pigments generally increase early in the sapropel, due to fast adaptation to more P-rich conditions. Cyanobacteria are favored by low N/P-ratios and P was probably in excess during the formation of S1 and the Baltic Sea sapropel sediments. Lowering of δ<sup>15</sup>N and concurrent increase in N in both the Baltic Sea and S1 sapropels is probably caused by cyanobacterial N<sub>2</sub>-fixation. This most likely increased the N/P-ratio and enhanced overall primary productivity. Both increased primary productivity and enhanced preservation of organic carbon are important mechanisms for sapropel formation. The appearance of isorenieratene in the protosapropel is most likely the result of an environment where even moderate increases in primary productivity could create anoxic conditions. This favours an estuarine water circulation scenario with anoxic bottom waters. δ<sup>34</sup>S of sulphate and sulphide confirm this scenario, which can be explained by the coexistence of sulphate reducing and sulphur disproportionating bacteria together with phototrophic purple and green sulphur bacteria.</p>
15

Vattenkvarnar - en studie om Hjul- och skvaltkvarnar och deras förekomst i Fulltofta socken

Bengtsson, Mikael January 2005 (has links)
<p>This rapport handles the presence of two kinds of watermills in the Swedish landscape. The first is a small type with a horizontal shovel blade and the other a bigger kind with a vertical standing shovel scoop. The rapport seeks for information of their capacity and how long they existed as flour producing units. A important issue is how small can a brook be and still run a mill. Finally the reasons for their disappearance in one selected parish is shown.</p>
16

Från ett nödvändigt ont, till en naturtyp värd att bevara - en studie av ljungheden i Sandsjöbacka och Grönabur/From a necessary evil to a nature type worth protect - a studie of the Calluna heath of Sandsjöbacka & Grönabur

Barrhök, Johan January 2005 (has links)
<p>In the middle of the 19th century was Calluna heath the major nature type in Halland, but the remaining parts today is only 1 500 hectares which is a 99 % decrease of the Calluna heath mainly due to an increase in forest plantations and arable fields. I have made a quantitative study how the Calluna heath of Grönabur & Sandsjöbacka has changed between 1841 and 2005 and why it didn’t disappear in the same manner, as it did in other parts of Halland. </p><p>The studying of original sources as historical maps, literature and by doing field visits has been significant for the final result. The main reason for the different development of the Calluna heath in the investigation area (69 % decrease), compare to elsewhere in Halland, is the establishment and management of a nature reserve.</p>
17

Landsbygdens återkomst - mångsysslare i ny produktion : Löderup och Valleberga socknar om 10 till 15 år

Håkansson, Annika, Ingvarsson, Eva, Persson, Kamilla January 2005 (has links)
<p>The essay on ”The revival of the countryside – a multitalent in landproduction.” focuses on local and regional development within agriculture, foodprocessing and tourism.</p><p>Due to great changes in society, the inhabitants in rural areas are forced to find alternative occupations. Using history as a tool to build up the future is a main factor in rural development. Apart from this it involves cooperation, resources, cultural heritage and values, entrepreneurship and innovation, economic vitality, and an understanding of markets and marketing. They all contribute to a region`s ability to benefit from rural development.</p>
18

Cata - a former homeland village affected by Betterment, Eastern Cape, South Africa

Andersson, Josefina, Axelsson, Lina January 2005 (has links)
<p>This study focus on the house ruins and land use in Nyokana, a former village section in Cata, by looking at their location, number and the people who lived there and their living before the Betterment plan was carried through. This is done by studying an old map and documents of Cata, field studies with GPS-using and by interviewing mostly old inhabitants. The result is a basis for the development of the planned tourism track within the heritage project, wich runs by BRC and University of Fort Hare.</p>
19

Fiskarebönder och landskapet i Karlshamns skärgård förr och nu

Granqvist, Ingela, Hassgård, Jörgen January 2005 (has links)
<p>Hällaryd archipelago, consisiting of approx. 50 islands, islets and skerries, is situated east of Karlshamn city in Blekinge province. The archipelago has been shaped into a rift valley by volcanic activity, the inland ice and maritime climate.</p><p>The archipelago is divided into seven main islands: Bockö, Västra Bokö, Ekö, Hallö, Joggesö, Mjöö and Tärnö. </p><p>This essay will connect population changes with land use. </p>
20

Förslag till placering av anläggningar för att förbättra vattenkvalitén i Tidan

Wilsson, Anneli January 2006 (has links)
<p>Considering water quality, landuse and reducion of wetland area in the watershed of Tidan, areas witch are in need of constructions to improve the water quality are identified. Constructions are suggested to be located within the smaller streams in the watershed, so that the water is treated before it reaches the stream Tidan.</p>

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