• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 641
  • 59
  • 50
  • 50
  • 50
  • 50
  • 50
  • 47
  • 46
  • 31
  • 30
  • 13
  • 10
  • 9
  • 8
  • Tagged with
  • 1070
  • 174
  • 148
  • 134
  • 118
  • 113
  • 103
  • 85
  • 71
  • 70
  • 67
  • 66
  • 59
  • 58
  • 58
  • 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.
261

Oceanography and underwater acoustics in Resolute Bay, Nunavut: 2012-2015

O'Neill, Caitlin 12 July 2016 (has links)
Resolute Bay, a remote Arctic bay opening into Parry Channel, in the Canadian Arctic Archipelago, hosts diverse populations of marine mammals and fish at various times each year. These animals migrate through the bay following patterns linked to food availability and oceanographic conditions; however, these patterns are not well understood. The focus of this study was to measure the oceanographic properties of the waters in and around Resolute Bay and to record underwater sounds to obtain marine mammal temporal patterns and ambient sound levels. Results showed the water properties in Resolute Bay differed from the waters outside of the bay. Dissolved oxygen saturation levels in Resolute Bay decreased during ice-covered times, with lowest levels between May and July. Dissolved oxygen was replenished after the ice left the bay. Sudden changes in salinity, temperature, and dissolved oxygen were observed in Resolute Bay when outside waters entered. Mean third-octave band sound pressure levels were 85.3 dB re 1 μPa during high ice concentration, and 95.6 dB re 1 μPa during ice-free and freeze-up periods, and reached a maximum of 145.3 dB re 1 μPa when vessels were present. Belugas (Delphinapterus leucas) and narwhals (Monodon monocero) were only present in periods of low ice concentration, while bearded seals (Erignathus barbatus) and ringed seals (Pusa hispida) remained throughout the entire year. / Graduate / 2018-07-01
262

Problematika Arktidy a související výzvy pro mezinárodní vztahy / Challenges for International Relations in the Arctic

Štěpánek, Zdeněk January 2015 (has links)
This thesis deals with identification, analysis and critical assessment of challenges for international relations arising in the Arctic in connection with global climate change, which results mainly into decrease of the sea ice. Copenhagen School forms the primary theoretical bedrock of the thesis. The thesis maps the approach of different theoretical paradigms to the Arctic region throughout the history and on this basis it justifies the relevance of application of the concept of security sectors defined by Copenhagen School on the region. The thesis also maps the current governance mechanisms of the Arctic region as far as international law and institutional arrangements are concerned. The analysis of concrete challenges for international relations is structured according to the sectors of security defined by Copenhagen School. Thus, challenges in the environmental, societal, economic, political and military sectors are examined.
263

Tectonic evolution of northern Ellesmere Island: insights from the Pearya Terrane, Ellesmerian Clastic Wedge And Sverdrup Basin

Malone, Shawn Joseph 01 December 2012 (has links)
The tectonic evolution of northern Ellesmere Island is dominated by the accretion of the Pearya Terrane and the progressive reworking of materials from the Pearya Terrane and the northern Caledonides. Geochronology from a suite of seven Succession I orthogneiss samples defines a range of earliest Neoproterozoic ages from 962 ± 6 Ma to 974 ± 8 Ma. Geochemistry of both zircon and whole rock samples reveal a complex magmatic history tapping multiple sources. The rocks include both I and S type granitoids, with silica contents ranging from 62% to 73%. Trace element geochemistry reveals LILE enrichment decoupled from low to depleted HFSE values, suggestive of an origin above a subduction zone. Isotope geochemistry supports input from juvenile and evolved materials, with εNd(i) values between -1 and -4.6, and a similar range for εHf from zircon. The northern elements of the Caledonian Orogen preserve a record of magmatism in the c. 985 Ma to 920 Ma range. These ages are also observed in orthogneiss units of the south central Brooks Range and Farewell terrane, Alaska. The Pearya Terrane orthogneiss units and those currently dispersed in Alaska are interpreted to have originated near or on the eastern margin of Greenland and record post-Rodinia assembly subduction outboard of the supercontinent. Succession II (Trettin, 1987) of the Pearya Terrane represents variably metamorphosed metasedimentary rocks of Proterozoic to early Paleozoic age. These units are structurally juxtaposed with Succession I orthogneiss and Paleozoic sedimentary units of the Pearya Terrane. Detrital zircon age spectra from seven samples of Neoproterozoic meta-sedimentary rocks reveal three groups defined by observed dominant age peaks and youngest observed age populations. Group I includes three quartzite samples and contains numerous c. 1100 Ma to 1800 Ma peaks, with the youngest population at c. 1050 Ma. Two samples of immature meta-sandstone form Group II, defined by a dominant c. 970 Ma age peak. Two samples from the diamictite unit below the Deutchers Glacier thrusts form Group III, with a similar pattern of c. 1000 Ma to 1800 Ma age peaks to Group I; however, this group includes a small population of c. 600 Ma to 700 Ma grains as well. The ubiquitous Mesoproterozoic ages reflect a Grenvillian-Sveconorwegian provenance. These data are consistent with detrital zircon datasets from other North Atlantic-Arctic Caledonide terranes, reinforcing stratigraphic links between the Pearya Terrane and the northern Caledonides. The utility of the Pearya Terrane dataset is multiplied by probable links to Circum-Arctic and Cordilleran terranes, many of which contain similar populations of Mesoproterozic-aged detrital zircon. U/Pb ages and Hf isotopic data from detrital zircon suites sampled from Ordovician to Carboniferous sedimentary rock of the Pearya Terrane and northern Ellesmere Island record define the background for terranes translating along the northeastern Laurentian margin in the Paleozoic. Ordovician to Silurian clastic sediments deposited on the Pearya Terrane record pre terrane accretion provenance dominated by recycling of the metaigneous and metasedimentary Proterozoic basement as well as an Ordovician arc source. The provenance of Late Devonian sediments deposited during the Ellesmerian Orogen is dominated by similar recycled materials, with new sources derived from Paleoproterozoic domains of the Canadian-Greenland shield and documented late Devonian granitoids emplaced the Canadian Arctic Islands and Arctic Alaska. The basal Sverdrup Basin records increasing proportions of Paleoprtoerozoic and Archean aged grains relative to Mesoproterozoic ages, suggestive of increased contributions from the Laurentian craton and no little detritus exotic to Laurentia. Detrital zircon age spectra from Devonian to Carboniferous sediments in the northern Cordilleran clastic wedge and western Canadian Arctic Islands contain abundant exotic zircon likely derived from the Caledonian and Timanian Orogens. This variance of sediment provenance indicates that the eastern Canadian Arctic Island were isolated from non-Laurentian or Caledonian detritus, and that sources of the exotic Timanian zircon reconstruct farther west along the margin.
264

A helping hand for the Arctic : EU in search for a role in the North

Pettersson, Jessica January 2020 (has links)
Climate change is opening opportunities for further extraction of natural resources and business in the Arctic, which is why the region is more desirable to a variety of actors, including the European Union (EU). Even though the EU is not a permanent observer in the Arctic Council, the EU Member States, Sweden and Finland, are. Henceforth, this thesis is an explorative comparative case study with the aim to investigate the EU's role in Arctic affairs, and if the EU's interests overlap and/or challenge the interest of the two EU Member States. It explains this through the theoretical approaches of liberalism (cooperation) and realism (confrontation). The material under investigation is the Arctic policies of the EU, Sweden, and Finland. The Arctic policies are analyzed based on the three priorities of the EU's Arctic policy: (1) International cooperation on Arctic Issues, (2) Climate change and safeguarding the Arctic Environment, and (3) Sustainable development in and around the Arctic by conducting a frame analysis. The findings of the study show that the EU frames itself as a ‘helping hand’ in the Arctic, meanwhile Sweden and Finland do not fully agree with this picture. Concluding that the EU does not show any attempt to challenge its Member States' interests in the Arctic. It also shows all three actors on one side have a very liberal frame for international cooperation, but on the other side have visible elements of a more realistic frame in terms of sustainable development.
265

Growth, proximate composition and physiology of Arctic charr exposed to toxaphene and Diphyllobothrium dendriticum

Blanar, Christopher A. January 2001 (has links)
No description available.
266

Acute effects of petroleum hydrocarbons on the arctic littoral mysid, mysis oculata (Fabricius)

Riebel, Philippe N. January 1988 (has links)
No description available.
267

The Geopolitical Tensions in the Arctic Region : A Comparative Study of Russia’s and Finland’s Arctic Policies

Nord, Astrid January 2023 (has links)
This thesis presents an analysis of Russia’s and Finland’s Arctic polities, and what effects their policies have for the future geopolitical situation. The argument of this thesis that the implication of Russia’s and Finland’s policies on the geopolitical situation in the Arctic will likely get increasingly tense in the future. Neoclassical realism was the chosen theoretical framework since the topic is concerned with a combination of domestic and systemic factors. The methodological approach was a comparative case study analyzing Russia and Finland with a most-different system design. This approach made it possible to compare three units that shaped these states Arctic policies. Conclusively, the results find that Russia’s economic decline and perception of the Arctic as an economic opportunity conflict with Finland who are in favor of policies to strengthen the regional organizational framework by broadening Arctic Council’s agenda to have a greater cooperation with Arctic and non-Arctic states on security politics.
268

Comparison of temperature variability and trends in Svalbard and Franz Joseph Land

Renberg, Johanna January 2022 (has links)
Arctic warming is assumed to be four times the global warming. A published study by Ivanov et al. (2019) shows that the annual average temperature of Franz Joseph Land (the world’s northernmost island region, a Russian territory) has increased by 5.2 °C from 2000-2017. This result supported the idea of determining whether Svalbard (Norwegian territory) is experiencing similar warming. Svalbard has historically been an attractive research center for examining climate change in the Arctic. Due to easier accessibility, the vast majority of weather stations have been located on the western part of the main island, Spitsbergen, which does not provide a representative picture of the entire archipelago. Therefore, this project has focused on eastern Spitsbergen. Data from six stations have been processed to analyze the temperature changes based on linear regression (the same method as at Franz Joseph Land). As eastern Spitsbergen has never been a priority, only short datasets are available, with the longest one dating from 2009. Because of this, no statistically significant result could be elucidated. Instead, data from Longyearbyen, which is located southwest were implemented, allowing analysis over the same period as Franz Joseph Land (2000-2017). This result suggested a temperature increase of 5.6 °C for the same period, with a statistical significance of P = 0.13, as well as that the winters are extra vulnerable to warming. The stations from eastern Spitsbergen’s local variability were also examined, which showed that the local climate varies although the stations are relatively close. Among others, Pyramiden seemed to be most affected by the lapse rate feedback, meaning a significant strong warming at the surface.
269

A Synoptic Climatological Assessment of the Relationship between Arctic Sea Ice Variability and Climate Anomalies over North America

Ballinger, Thomas J. 09 April 2015 (has links)
No description available.
270

Meridional advection of moisture in the Arctic.

Boyes, G. A. January 1963 (has links)
No description available.

Page generated in 0.0598 seconds