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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

Diatoms as Recorders of Sea Ice in the Bering and Chukchi Seas: Proxy Development and Application

Caisse, Beth A. 01 May 2012 (has links)
The recent, rapid decline in Arctic summer sea ice extent has prompted questions as to the rates and magnitude of previous sea ice decline and the affect of this physical change on icerelated ecosystems. However, satellite data of sea ice only extends back to 1978, and mapped observations of sea ice prior to the 1970s are sparse at best. Inventories of boreal ecosystems are likewise hampered by a paucity of investigations spanning more than the past few decades. Paleoclimate records of sea ice and related primary productivity are thus integral to understanding how sea ice responds to a changing climate. Here I examine modern sedimentation, decadal-scale climate change in the recent past, and centennial- to millennial-scale changes of the past 400 ka using both qualitative and quantitative diatom data in concert with sedimentology and organic geochemistry. Diatom taxonomy and corresponding ecological affinities are compiled in this study and updated for the Bering Sea region and then used as recorders of past climate changes. In recent decades, the Pacific Decadal Oscillation and the strength of the Aleutian Low are reflected by subtle changes in sediment diatom assemblages at the Bering Sea shelf-slope break. Farther back in time, the super-interglacial, marine isotope stage (MIS) 11 (428-390ka), began in Beringia with extreme productivity due to flooding of the Bering Land Bridge. A moisture-driven advance of Beringian glaciers occurred while eustatic sea level was high, and insolation and seasonality both decreased at the global peak of MIS 11. Atlantic/Pacific teleconnections during MIS 11 include a reversal in Bering Strait throughflow at 410 ka and a relationship between North Atlantic Deep Water Formation and Bering Sea productivity. Finally, concentrations of the biomarker-based sea ice proxy, IP25, are compared to sea ice concentration across the Bering and Chukchi seas. Changes in the concentration of IP25 in the sediments may be driven by the length of time that the epontic diatom bloom lasts. When combined with a sediment-based proxy for sea surface temperatures, IP25 can be used to reconstruct spring ice concentration.
12

Last Deglacial Arctic to Pacific Transgressions via the Bering Strait: Implications for Climate, Meltwater Source, Ecosystems and Southern Ocean Wind Strength

Nwaodua, Emmanuel C. 09 December 2013 (has links)
No description available.
13

Fundo público e capital portador de juros: os dilemas do financiamento da seguridade social no Brasil

Santo, Marcos Henrique do Espirito 07 March 2017 (has links)
Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-03-17T11:54:40Z No. of bitstreams: 1 Marcos Henrique do Espirito Santo.pdf: 1256088 bytes, checksum: 68067cffb23c5a46839f73e747877817 (MD5) / Made available in DSpace on 2017-03-17T11:54:40Z (GMT). No. of bitstreams: 1 Marcos Henrique do Espirito Santo.pdf: 1256088 bytes, checksum: 68067cffb23c5a46839f73e747877817 (MD5) Previous issue date: 2017-03-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this research is to understand the relationship between the public fund and the interest-bearing capital in Brazil, with a particular analysis on the effects produced by this relationship within the Social Security Budget. Social security, constantly threatened by globalized finance, finds its most evident expression in Brazil. To do so, the understanding of interest-bearing capital from Marx will be rescued, as well as the constitution of the public fund in the post-World War II period in order to contextualize the relationship between the two elements. It is, however, from the structural creation of capital and the advance of financial deregulation that the public fund constituted for social protection suffers a severe attack / O objetivo desta pesquisa é compreender a relação entre o fundo público e o capital portador de juros no Brasil, com uma particular análise sobre os efeitos provocados por essa relação no Orçamento da Seguridade Social. A seguridade social, constantemente ameaçada pela finança globalizada, encontra no Brasil sua expressão mais evidente. Para tanto, será resgatada a compreensão do capital portador de juros a partir de Marx, além da constituição do fundo público no pós-II Guerra Mundial com objetivo de contextualizar a relação entre os dois elementos em destaque. É, contudo, a partir da crise estrutural do capital e do avanço da desregulamentação financeira que o fundo público, constituído para proteção social, sofre duro ataque
14

The Strait Defense: A Case Study Comparison of Global Straits

Endicott, Travis Wayne January 2016 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The global climate is creating more ice-free waters in the Arctic. These new navigation possibilities around the Arctic lead to increased global trade, tourism, and oil and gas exploration. With the foreseeable increased nautical transportation through the Northwest Passage, the United States needs to revisit its security posture in and around the Bering Strait. At least five different grand strategies are potentially relevant in addressing this question. By comparing the suggestions of these leading grand strategy approaches to what has actually been implemented by the United States in the Strait of Hormuz, the Strait of Malacca, and the Panama Canal, similarities emerge that can help the United States shape their strategy for the defending of its national interests in the Bering Strait. By testing the different grand strategies against three reasonably similar cases, I find that a forward military presence and supporting a liberal institutionalist approach are the two key aspects that the United States should employ in the Bering Strait. Increasing and improving the military presence that the United States has in the region should be a top priority. In addition, supporting the Arctic Council would provide an increased level of security to the United States and other nations in the region. This strategy is not without its challenges and it will require artful statecraft in order to be successful.
15

The Geopolitical Significance of the Bering Strait Region in the 21st Century / The Geopolitical Significance of the Bering Strait Region in the 21st Century

Raková, Alena January 2015 (has links)
As Arctic warms twice as fast as the rest of the world and the polar ice-cap melts, the strategic importance and geopolitical significance of the Bering Strait as the only maritime gateway between the world's fastest-developing and dynamic regions, the Asia Pacific and the Arctic region, will steadily grow. The climate change triggered the reduction of the Arctic ice-cap, which results in increased maritime traffic activity as new shipping routes are becoming more viable and mineral resources more accessible. This has a tremendous impact on the region as it opens it to economic development but at the same time it puts strain on its fragile environment. The goal of the paper is to affirm that the geopolitical significance of the Bering Strait is increasing and will increase in the near future. The work examines the causes of the Bering Strait region's rise, its characteristics, challenges and opportunities together with the assessment of major regional actors' interests and approaches towards the region. Next, paper focuses The emphasis is put especially on the role of the United States and on their attitude toward the Bering Strait region. It therefore pays attention namely on the US policy and goals in the region, and on the implications the Strait's growing global importance has for the United...
16

Mercury Methylation in Oxic Sub-Polar Marine Regions Linked with Nitrification

Despins, Marissa Collins 05 August 2022 (has links)
No description available.
17

Jízdárna / Hippodrome

Václavíková, Veronika January 2013 (has links)
The theme of this Master´s thesis is to design and assess the load Bering steel structure of the hippodrome in Napajedla. The hippodrome is solved as a hall object in two alternatives. Both alternatives are elliptical in shape with dimensions of 40 and 80 m. Load bearing structure of the chosen alternative is formed by transversely oriented column binding with the axial spacing of 6,0 m. Transversely oriented binding is formed from spatial lattice truss supported by fixed solid columns. The spatial rigidity of the structure is ensured by fixing columns in the transverse direction and by using transverse braces in the longitudinal direction. The longitudinal braces help to ensure the spatial rigidity. The work consists of the design and assessment of the main load bearing components, the solution of chosen details of joints and columns´ anchoring, solution of construction component and the elaboration of statement of material and drawings´ documentation.
18

Dřevěná nosná konstrukce víceúčelové haly / Multipurpose load-bearing timber hall structure

Matuška, Martin January 2013 (has links)
This Master’s thesis is focused on the design and structural analysis of load-bearing structure of a multipurpose hall that is strained by the permanent load, working load and climatic load. The hall has the shape of an elliptical dome. Maximum margin of the structure is 60,0m and maximum height is 18,0m. Main carrier elements of the structure are radially arranged curved beams made of glued laminated timber, class SA(GL24).
19

Diatoms from the late Holocene of the western Chukchi Sea, Arctic Ocean: environmental signals and palaeoceanography / Diatoméer från sen holocen i västra Tjukjerhavet, Arktiska oceanen: miljösignaler och paleoceanografi

Browaldh, Erik January 2022 (has links)
The sediment Core SWERUS-L2-2-PC1 (2PC) retrieved from the Chukchi Sea, Arctic Ocean sits in an oceanographically dynamic location at the Arctic-Pacific Ocean gateway. The 8.3 m-long core was retrieved in Herald Canyon at the marginal ice zone at 57 m depth. Core 2PC is well-positioned to record variability in inflow of Bering Sea Water (BSW) and Pacific Water (PW) in Herald Canyon. With the 2PC high sedimentation rate (200 cm/kyr), two independent age models (radiocarbon and palaeomagnetism) based on tephra age markers, and a richness in well-preserved siliceous sediment, validate 2PC as an outstanding sequence for applying diatom assemblage analysis as a proxy for ocean-climate change back to 4250 years BP, including the past few hundred years where global warming and sea ice decline is recorded by instrumental records. These characteristics make Core-2PC a useful record for investigating the role of PW on sea ice variability in the Chukchi Sea, both in the past and predicting the future. To investigate the impact of PW on ocean and sea ice conditions in the Chukchi Sea, diatom assemblage analysis was performed on 49 samples through the Late Holocene. The over-arching goal was to test the hypothesis, suggested by existing research on 2PC using benthic foraminifera Mg/Ca palaeothermometry, that the strength of PW inflow into the Chukchi Sea via Herald Canyon has varied on a time scales of ~500-1000 years in the past 4000 years. PW is slightly warmer than resident Arctic surface waters and is known to be an important control on Arctic sea-ice. The diatom assemblage approach assumes that there are recognizable differences between end-member diatom assemblages that are characteristic of PW versus Arctic Ocean type environments associated with extensive sea-ice conditions. The mapping of species in the Herald Canyon was used to test the idea of variability of sea-ice extent and the role of the Pacific Ocean forcings into the western Chukchi Sea. The results reveal diverse diatom assemblages throughout the past 4000 years in Herald Canyon, showing this core to be very useful for diatom palaeoclimate reconstructions. A total of 126 species with abundance >1% are recognized. Several generalist species typically dominate assemblages especially Chaetoceros, ice-algae, marine-neritic and near ice or cold-water planktic centric diatoms. Distinct changes in stratigraphy are illustrated by changes in identified diatom assemblage zones. The 2PC diatom assemblages were contrasted with records from Chukchi-, Laptev-, East Siberian- and Bering Sea and North Pacific Ocean. At 2PC, sympagic (sea-ice related), planktic and neritic species abundance varies on time scales of ~500-1000 years. Importantly, there is a clear similarity between the timing of diatom assemblage changes and the 2PC benthic foraminifera Mg/Ca bottom water temperature (BWT) reconstruction. In particular, abundance changes in the warm water species Thalassionema nitzschioides, Shionodiscus oestrupii and Thalassionema simonsenii, tychoplanktic Paralia sulcata, Ice algae- and sympagic assemblages and cold-water indicators correspond best to BWT fluctuations shown by the Mg/Ca reconstruction. These oscillations are suggestive of changes in warmer PW inflow. Other aspects of the diatom data appear to correlate with colder and warmer climate events and suggest that changes in PW inflow amplified the effects of these events in the Chukchi Sea region through the Late Holocene in the Northern Hemisphere. It can thus, be concluded that diatoms from 2PC, support the palaeoceanographic reconstruction suggested by the benthic foraminifera Mg/Ca palaeothermometry and that variations in PW inflow through Herald Canyon is an important driver of sea ice variability on thousand-year time scales.

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