• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigating the Magnetic Susceptibility of Cornish Loess as a Tool for Understanding the Palaeoclimate of SW England / Undersökning av den magnetiska susceptibiliteten i loess från Cornwall som ett verktyg till att förstå paleoklimatet i sydvästra England

Tingdal, Love January 2020 (has links)
Loess is a silty material produced via glacial grinding and its deposition is usually associated with colder periods when there is a considerable increase in atmospheric dust transport. The magnetic susceptibility of loess-palaeosol sequences has been the subject of extensive research within palaeoclimatology as it has proven to be reliable climate proxy. Most research on magnetic susceptibility has been focused on thick deposits found in Europe and Asia, in particular the Chinese Loess Plateau where it is possible to discern more than 2.5 million years of climate variation in deposits several hundred meters thick. The climate development throughout the Quaternary has been characterized by glacials where there has been a significant ice growth, and interglacials where ice sheets have retreated. The Last Glacial Maximum was the most recent time of ice sheets reaching their maximum extent, occurring at some point between 26.5 and 18 ka BP. Aeolian reworking of material produced in conjunction with the Irish Sea Ice Stream (ISIS) occurred approximately 5000 years after the LGM. The ISIS limit were located just north of the Lizard Peninsula, and impinged on the Isles of Scilly. Loess deposits in SW England has largely been ignored in previous research in favour of the previously mentioned Chinese loess, but may be important climate archives in understanding the climate development of the North Atlantic. As such, the scope of this thesis is investigating the magnetic susceptibility of loess deposits in Cornwall and the Isles of Scilly in the far SW England. This is done by analyzing 36 samples from Lowland Point and 24 samples from Chynhalls Point, both located at the Lizard Peninsula in Cornwall, as well as 20 samples from Porthcressa and 14 samples from Gimble Porth, both located at the Isles of Scilly. The instruments used for analysis are the Bartington MS2B and the Agico MFK-1 FA Kappabridge, where all 96 samples were analyzed on the former while the 36 Lowland Points samples and the 20 Porthcressa samples were also analyzed on the latter. The Bartington MS2B operates at two frequencies, 465 Hz and 4650 Hz, while the Agico MFK-1 FA Kappabridge operates at three frequencies, 976 hz, 3904 Hz, and 15616 Hz. The results from this study suggest that the Lizard Peninsula sample sites exhibit signs of magnetic enhancement through pedogenic processes while the sample sites at the Isles of Scilly consist of mainly unaltered material, likely due to an overlying sollifluction unit inhibiting magnetic enhancement. As a consequence of the different frequencies, the results were lognormalized to permit a direct comparison between the instruments. While the variability in magnetic susceptibility was strikingly similar, the results of the Kappabridge were shifted to ~20% higher values than those of the Bartington which may be attributed to the Kappabridges higher precision when analyzing weakly magnetic material. A similar shift is not evident when measuring the calibration samples of each instrument. In determining the mean annual precipitation after deposition, the Lizard Peninsula samples sites suggest an exposure to an annual precipitation between 300-400 mm/yr, compared to modern rainfall between 900-1000 mm/yr. The data from the Isles of Scilly were insufficient for calculating the mean annual precipitation due to the lack of evidence for magnetic enhancement. / Loess är benämningen för material i siltstorlek som produceras då glacial aktivitet maler ned den underliggande berggrunden. Detta material är tillräckligt litet för att fångas upp av vindar och därefter transporteras i atmosfären, för att därefter avsättas då vindhastigheten minskar. Under kalla perioder i jordens historia ökar denna transport då vindhastigheten ofta varit högre än under varma perioder. Under de varmare perioderna och med tiden så utsätts loess för jordmånsbildande processer och bildar palaeosoler. Den magnetiska susceptibiliteten hos loess-palaeosol-sekvenser har under flera årtionden varit ämnet för utbredd forskning då detta har visat sig vara en tillförlitlig klimatproxy för att förstå klimatutvecklingen under jordens gångna historia. I synnerhet har loess-palaeosol-sekvenser i Kina varit av intresse då det går att utröna mer än 2,5 miljoner år av klimatutveckling i avlagringar som på sina platser är flera hundra meter tjocka. Under den senaste istidens maximala utbredning mellan 26500 och 18000 år sedan passerade en isström över den Irländska sjön (Irish Sea Ice Stream, sammankopplad med inlandsisen), förbi Cornwalls norra kust och stötte samman med Scillyöarna. Det tog sedan ungefär 5000 år tills vindtransport av avsatt material påbörjades. Loessavlagringar i sydvästra England har känts till under årtionden men har till stor del ignorerats till fördel för de tidigare nämnda avlagringarna i Kina, men de kan agera som viktiga klimatarkiv för tiden efter den senaste istiden och därmed klimatutvecklingen i Nordatlanten. Denna rapport undersöker således den magnetiska susceptibiliteten i loess från två platser på Lizard-halvön i Cornwall, och två platser på Scillyöarna. Totalt analyserades 96 prover, 36 av dem från Lowland Point, 24 av dem från Chynhalls Point, båda belägna på Lizard-halvön, samt 20 prover från Porthcressa och 14 prover från Gimble Porth, båda belägna på Scillyöarna. Resultaten från denna studie påvisar att provplatserna på Lizard-halvön visar tecken på magnetisk förstärkning på grund av jordmånsbildande processer, medan provplatserna på Scillyöarna huvudsakligen består av oförändrat material, troligen på grund av att dessa täckts av annat material under isens tillbakadragning, vilket förhindrat jordmånsbildning. Resultaten från Lizard-halvön möjliggör beräkning av årsmedelnederbörden sedan materialet först avsattes, vilket beräknades till mellan 300-400 mm/år jämfört med modern årsmedelnederbörd mellan 900-1000 mm/år. Dessvärre möjliggjorde inte resultaten från provplatserna på Scillyöarna en liknande beräkning.
2

Localism and the design of political systems

Harmes, Riccardo Lucian Paul January 2017 (has links)
Localism places a special value on the local, and is increasingly prominent as a political doctrine. The literature suggests localism operates in three ways: bottom-up, top down and mutualistic. To assess its impact, localism needs to be seen within the broader context of multi-level governance. Here localism is examined in relation to three major themes: place, public value (PV), and institutional design. Regarding place, a key distinction is drawn between old and new localism. Old localism is about established local government, while new localism highlights the increasing room for manoeuvre that localities have in contemporary politics. This enables them to influence wider power structures, for example through trans-local organizing. With regard to public value, localist thinking makes a key contribution to core PV domains such as sustainability, wellbeing and democracy, as well as to others like territorial cohesion and intergovernmental mutuality. As for institutional design, the study is particularly concerned with ‘sub-continental’ political systems. A set of principles for the overall design of such systems is proposed, together with a framework of desirable policy outcomes at the local level. This can be used to evaluate how effective political systems are at creating public value in local settings. The thesis presents a comparative study of localism in two significant, sub-continental clusters: India/Kerala/Kollam and the EU/UK/England/Cornwall. Both can be seen as contrasting ‘exemplars’ of localism in action. In India, localism was a major factor in the nationwide local self-government reforms of 1993 and their subsequent enactment in the state of Kerala. In the EU, localism has been pursued through an economic federalism based on regions and sub-regions. This is at odds with the top-down tradition in British politics. The tension between the two approaches is being played out currently in the peripheral sub-region of Cornwall/Isles of Scilly. Cornwall’s dilemma has been sharpened by Britain’s recent decision to leave the EU. The thesis considers the wider implications of the case studies, and presents some proposals for policymakers and legislators to consider, together with suggestions for further research.

Page generated in 0.0403 seconds