Sea level rise (SLR) threatens coastal communities, infrastructure, and ecosystems. Worldwide, stakeholders critically depend on SLR projections with the associated uncertainty for risk assessments, decision-making and coastal planning. Recent research suggests that the Antarctic ice sheet mass loss during the 21st century may contribute up to an additional one meter of global SLR by year 2100. While uncertainty still exists, this value would double the ‘likely’ (> 66% probability) range of global SLR (0.52-0.98 m) by the year 2100, as found by Chapter 13 on Sea Level Change in the Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Here, we present three studies that assess mechanisms relevant to 21st century local, regional, and global SLR. Appendix A examines the effect of large-scale oceanic and atmospheric circulation variability on extreme sea levels along the East Coast of North America. Appendices B and C analyze ocean warming on the Antarctic shelf and its implications for future ice shelf basal melt and Antarctic Ice Sheet mass loss. These studies will contribute to more accurate projections of local, regional, and global SLR. In Appendix A, we analyze long-term tide gauge records from the North American eastern seaboard and find an extreme SLR event during 2009-2010. Within this two-year period, coastal sea levels spiked between Montauk, New York and Southern Canada by up to 128 mm. This two-year spike is unprecedented in the tide gauge record and found to be a 1-in-850 year event. We show that a 30% reduction in strength of the Atlantic meridional overturning circulation (AMOC) and a strong negative North Atlantic Oscillation (NAO) index caused the extreme SLR event. Climate models project that the AMOC will weaken and NAO variability will remain high over the 21st century. Consequently, extreme SLR events on the Northeast Coast could become more frequent during the 21st century in response to climate change and SLR. In Appendix B, we use a fine-resolution global climate model (GFDL CM2.6) that resolves an eddying ocean. With this state-of-the-art coupled model, we quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized experiment of doubling of the atmospheric CO2 concentration. The results show that the CO2 forcing leads to the shelf region warming both in the upper 100 m ocean and at depths near the sea floor. These warming patterns are controlled by different mechanisms. In the upper 100 m, the heat anomalies are primarily controlled by increased heat transport into the shelf region associated with the warmer near-surface waters from lower latitudes. Below 100 m, the heat anomalies develop due to increased onshore intrusions of relatively warm Circumpolar Deep Water and reduced vertical mixing of heat in the water column. A complete heat budget analysis is performed for the Antarctic shelf region as well as for six subdomains and three depth ranges (0-100 m, 100-700 m, and 700-1000 m). The results show that certain regions of the Antarctic shelf are more susceptible to large CO2-forced warming. These findings have implications for future Antarctic Ice Sheet mass loss and SLR, and can provide more detailed and accurate ocean boundary conditions for dynamical ice sheet models. In Appendix C, we use CM2.6 to examine the connections among ocean freshening and the magnitude and location of ocean warming on the Antarctic shelf. We find that CO2 forcing freshens the Antarctic shelf seas via increases in local precipitation, sea ice loss, liquid runoff, and iceberg calving. The freshening induces three heat budget-relevant responses: (1) reduced vertical mixing; (2) strengthening of the Antarctic Slope Front (ASF); and (3) increased eddy kinetic energy (EKE) near the ASF. First, heat can accumulate at depth (100-1000 m) as freshening increases the vertical stratification on the shelf and reduces upward mixing of heat associated with diffusion and convective processes. Second, freshening near the shelf break strengthens the ASF by increasing the lateral density gradient and by steepening and deepening the associated isopycnals. This response limits cross-ASF onshore heat transport at many locations around Antarctica. Third, EKE increases near the ASF may contribute to shelf warming by increasing cross-ASF onshore eddy heat transport. These results demonstrate the importance of shelf freshening to the development of positive heat anomalies on the Antarctic shelf. The findings provide new insight to the location of future shelf warming and ice shelf basal melting as well as provide significant information for projecting regional and global SLR.

The use of enzymes as catalysts in organic synthesis constitutes an attractive alternative to conventional chemical catalysis. Enzymes are non-toxic and biodegradable and they can operate under mild reaction conditions. Furthermore, they often display high chemo-, regio- and stereoselectivity, enabling specific reactions with single product outcome. By the use of protein engineering, enzymes can be altered for the specific needs of the researcher. The major part of this thesis describes engineering of lipase A from Candida antarctica (CalA), for improved enantioselectivity in organic synthetic transformations. The first part of the thesis describes a highly combinatorial method for the introduction of mutation sites in an enzyme library. By the simultaneous introduction of nine mutations, we found an enzyme variant with five out of the nine possible mutations. This quintuple variant had an enlarged active site pocket and was enantioselective and active for our model substrate, an ibuprofen ester. This is a bulky substrate for which the wild-type enzyme shows no enantioselectivity and very poor activity. In the second part of the thesis, we continued our approach of combinatorial, focused enzyme libraries. This time we aimed at decreasing the alcohol pocket of CalA, in order to increase the enantioselectivity for small and medium-sized secondary alcohols. The enzyme library was bound on microtiter plates and screened by a transacylation reaction in organic solvent. This library yielded an enzyme variant with high enantioselectivity for the model substrate 1-phenyl ethanol, and high to excellent selectivity for other alcohols tested. Screening in organic solvent is advantageous since a potential hit is more synthetically useful. In the third part of the thesis, we used manipulated beads of controlled porosity glass (EziG™) for enzyme immobilization, and demonstrated the generality of this carrier for several enzyme classes. EziG™ allowed fast enzyme immobilization with simultaneous purification and yielded active biocatalysts in all cases. The last project describes the function of the proposed active site flap in CalA. In our study, we removed this motif. The engineered variant was compared to the wild-type enzyme by testing the amount of interfacial activation and the selectivity for certain alcohols. We showed that the motif is indeed controlling the entrance to the active site and that the flap is not part of the enantioselectivity determining machinery. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

Abstract This thesis examines the Mid-Pliocene climatic extreme ca. three million years ago (Ma) which was the latest longtime warm period. It is an important topic because the climate back then was warmer compared with the present. The bipolar regions are studied because they represent the largest areas that control the global climate. This study is based on clay mineral research that may significantly improve our knowledge of the Mid-Pliocene climate when combined with other palaeoenvironmental data. The paleoclimatological objectives of this study were: 1) to investigate how clay minerals reflect the Mid-Pliocene Global Warmth event, 2) to study ice sheet development at high latitudes, especially in East-Antarctica, and the history of ice rafting and sea ice, especially in the Arctic Ocean. This thesis deals with the clay mineral distribution and compositional analysis of the Pliocene-aged marine sediment sequences provided by the Ocean Drilling Program (ODP). The first studied site, Site 1165, is located at the continental rise of Prydz Bay, East Antarctica, and the second studied site, Site 911, is located at the Yermak Plateau, north of Svalbard, in the Arctic Ocean. The Pliocene smectite clay minerals at Site 1165 were mainly derived from Antarctic continental sources and transported to the site primarly by bottom currents related to warm events during the last 5 Ma. The evidence obtained in this study shows that the East Antarctic ice sheet may have been a dynamic ice sheet during the past 5 Ma, especially during the Mid-Pliocene. The results from the Mid-Pliocene possibly suggest a general warming trend. Based on the composition of the heavy minerals and clay minerals, at Site 911, the Pliocene smectite clay minerals were mainly transported within sea ice by the Siberian branch of the Transpolar Drift. The results indicate a warming trend at approximately 3 Ma after which they indicate a shift back to glacial conditions. Based on this study, the Mid-Pliocene Global Warmth can be observed in both the Arctic and Antarctic regions.

>Magister Scientiae - MSc / A metagenomic gene library prepared from soil found beneath a mummified seal carcass in the Miers Valley, Antarctica, suggests an environment rich in uncharacterised biodiversity including enzymes with possible application to industrial processes. A sequence based gene mining investigation was performed on a clone, which archives a metagenomic sequence from this environment. The sequence was annotated using de novo bioinformatics and molecular biology techniques. A predicted NAD+-dependent DNA ligase, ligDB1 was selected for further characterisation. LigDB1 encodes a gene product that contains all the sequence features of a functional ligase. The protein was overexpressed in a heterologous E. coli host and purified to homogeneity. LigDB1 did not exhibit nick sealing activity, but was able to perform AMP-dependent DNA relaxation in the presence of high concentrations of enzyme. DNA modifying enzymes from cold environments perform optimally at low temperatures and may be of use as molecular tools in biotechnology. Complete characterisation of this enzyme is subject to further investigations

The cementing of ties between South Africa and the Mercosur countries occurred at the time when the Cold War had just ended. Characteristic of the post-Cold War environment is the ascendance of socio-economic issues and the receding importance of military issues. Thus, South Africa’s security relations with Mercosur are rooted in the socio-economic sphere with limited military interaction which is designed to facilitate trade links and deal with potential trans-oceanic criminal activities such as drug-trafficking, arms-smuggling, poaching and sea piracy. This is in stark contrast with the pre-1994 relations between South Africa and the South American states. Given the fact that South Africa was regarded by the international community as a pariah state owing to her unacceptable political system, it was only prudent for South Africa to look for like-minded allies across the South Atlantic Ocean. From the mid-sixties to the early eighties, most South American states were under military rule, thus providing an ideal opportunity for possible allies for South Africa. At that stage, South Africa’s motive for cementing ties with South American states, especially those that eventually formed Mercosur, was not based on a genuine need for mutual protection and complementarity of defence capabilities, but a quest for some semblance of acceptability by the international community. Despite the decreasing importance of military matters in international relations, South Africa still maintains a significant exchange programme with the Mercosur military establishments. While most of the exchanges are for diplomatic purposes, military establishments on both sides of the South Atlantic Ocean conduct regular military exercises on both shores, in co-operation with extra-regional powers such as the US and the UK. These exercises serve the purpose of ensuring interoperability of military equipment (such as operational communication systems) and harmonising national policies and procedures, especially for search-and-rescue operations, but also for ensuring the smooth operation of maritime traffic on the South Atlantic Ocean. Furthermore, there is always a perennial fear that, despite the demise of the Cold War, the South Atlantic region may become a theatre of war in future. This is particularly based on the analysis of possible resource-endowment in Antarctica, which will fuel competition and intensify territorial claims. South Africa and some of the Mercosur countries also have significant interests in Antarctica. / Thesis (DPhil (International Politics))--University of Pretoria, 2005. / Political Sciences / unrestricted

My project examines the phenomenon of the hazy spaces on the periphery of the antebellum imagination that, while existing geographically at the very fringes of daily American life, are nonetheless active in the conceptualization, production, and representation of an idiosyncratic American sense of space: an anxiety of spatial fragmentation, formlessness, and modulation. In particular I am interested in Poe's “The Narrative of Arthur Gordon Pym” and Melville's “Benito Cereno,” both of which deal with American transoceanic travel to the proximity of Antarctica and its surrounding seas. These gothicized nautical fictions demonstrate an important dialectic playing out in these extreme spaces: the oscillating experience of external and closed space. What becomes detectable in antebellum literature in which spaces of enclosure interrupt expansiveness are far-reaching, deeply-rooted anxieties of an ever-transforming American space at risk of fragmenting and necessitating reorientation via the sort of imaginary travel texts being examined.

This study aims to quantify ground ice content and describe the cryostructures and sediment in 15 ice-bearing permafrost cores collected from nine sand-wedge polygons in University Valley. The objectives were reached through laboratory measurements and computed tomodensitometric (CT) scanned image analysis of the permafrost cores. The soils in the valley were predominantly medium-sand. Four types of cryostructures were present in the cores: structureless, suspended, crustal and porphyritic. Excess ice content ranged from 0 to 93%, gravimetric water content ranged from 13 to 1881% and volumetric ice content varied from 28 to 93%. Median excess ice, volumetric ice and gravimetric water contents significantly increased in the top 20 cm of the cores taken from the polygon shoulders with increasing distance from University Glacier. Ground ice was preferentially stored in the centre of the investigated polygons where the ground surface remains cryotic throughout the year. Conversely, higher ground ice contents were measured in the shoulders of the investigated polygon where the ground surface is seasonally non-cryotic. CT-scanned images were shown to reasonably assess the distribution and presence of excess ice in permafrost cores taken from a cold and hyper-arid environment. The results of this thesis provide the first cryostratigraphic study in the McMurdo Dry Valleys of Antarctica.

Orientador: Telma Teixeira Franco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T15:01:29Z (GMT). No. of bitstreams: 1 Tsukamoto_Junko_D.pdf: 1866337 bytes, checksum: 5cac22304ad7fddc116a61d4e57a941f (MD5) Previous issue date: 2006 / Resumo: Reações enzimáticas em meio orgânico têm despertado grande interesse industrial devido às vantagens de obtenção de produtos puros pela maior especificidade das enzimas, pela redução de gastos energéticos e pela possibilidade de desenvolvimento de condições menos agressivas de processo. O uso de enzimas em síntese é uma alternativa viável à síntese orgânica e pode ser compreendida como processo relacionado ao novo conceito de ¿biotecnologia industrial¿ (white biotechnology), devido às preocupações ambientais e da sustentabilidade dos processos químicos. Processos biotecnológicos permitem a exploração racional de materiais renováveis (açúcares) para obtenção de produtos industriais, diminuindo a degradação ambiental. Uma rota enzimática é aqui proposta para obtenção de acrilatos de açúcares, monômero para confecção de polímeros biodegradáveis. O uso de enzimas em síntese orgânica oferece vantagens devido a especificidades na formação de produto, onde os custos de separação, purificação e tratamento de resíduos são minimizados. As lipases são responsáveis por 20% das biotransformações realizadas atualmente. Ésteres derivados de carboidratos e de ácidos graxos vêm sendo produzidos para a indústria alimentícia e farmacêutica, entretanto, mas não se encontram ainda ésteres tais como acrilatos de carboidratos no mercado. Esse projeto visou um estudo da produção de acrilatos de carboidratos pela reação direta via enzimática pela lipase comercial CalB. A esterificação de três monossacarídeos (D-glicose, D-frutose e D-xilose) e dois dissacarídeos (sacarose e maltose) com ácido acrílico pela CalB no solvente terc-butanol foi estudada. O efeito dos três seguintes parâmetros foi avaliado: temperatura, razão molar entre os reagentes (açúcar: ácido acrílico) e quantidade de enzima sobre a conversão a ésteres foi avaliada. A conversão da reação foi acompanhada por cromatografia líquida (CLAE-IR) e por MALDI TOF MS / Abstract: Industrial interest in enzymatic reactions in organic media is due to the possibility of obtain pure compounds with the use of highly specific enzyme, the decrease in energy costs and the possibility of using mild process conditions. The development of new enzymatic processes for chemical synthesis as a viable alternative to the organic synthesis is related to the new concept of "industrial biotechnology" (white biotechnology), with higher concerns with the environment and the sustainability of chemical processes. Biotechnological processes that make a more rational use of renewed resources such as sugars to produce chemicals decrease, in most cases, the environmental impact. In this work an enzymatic route is proposed for the production of sugar acrylates, a biodegradable monomer. The use of enzymes in organic media has the advantage of high specificity to the desired product, lower separation and purification costs, and minimization of residue formation. Currently, lipases are responsible for 20% of all biotransformations. Esters derived from fatty acid and carbohydrates are produced for the food and pharmaceutical industries. However, acrylate esters of carbohydrate are still not found in the market. This aim of this work was to study the production of acrylates of carbohydrates by the direct enzymatic reaction of sugars with acrylic acid on the commercial lipase CalB. The esterification of three monosaccharide (D-glucose, D-fructose and xylose) and two disaccharides (sucrose and maltose) with acrylic acid on CalB in tert-butanol was studied. The effects of temperature, molar ratio of the reactants (sugar to acrylic acid) and amount of enzyme on the conversion to esters were studied. The esterification reaction was monitored by HPLC and MALDI TOF MS / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

As condições ambientais e climáticas da Antártica repercutem no Brasil e América do Sul, constituindo-se em foco central de preocupação na medida que seu equilíbrio possa ser afetado. Para o País e a Região a defesa dos instrumentos legais de proteção ambiental tal qual o Protocolo ao Tratado da Antártica sobre Proteção ao Meio Ambiente-PEPAT são fundamentais. Para dinamizar-se a aplicação do PEPAT o seu §3º, artigo 9º e diversos outros dispositivos do seu Apêndice e Anexos possibilitam a aprovação e a entrada em vigor de “Medidas”, que estabeleçam alterações ao seu próprio Apêndice ou Anexos, em um ano ou noventa dias após o encerramento da respectiva ATCM em que tiverem sido adotadas, sem que se tenha que passar pelos respectivos processos internos de aprovação dos tratados internacionais dos países membros do TA, no caso do Brasil, pela aprovação do Congresso Nacional. Nestas condições estes dispositivos poderiam ensejar violação ao disposto no inciso I, artigo 49 e a segunda parte do inciso VIII, artigo 84, da Constituição Federal-CF. Não obstante, a presente dissertação propugna pela constitucionalidade dos dispositivos e das normas deles resultantes. Para fundamentar a assertiva pressupôs-se duas abordagens distintas, a primeira, sustenta a constitucionalidade partir de fundamentos tradicionais de Direito Internacional, de modo que se compreende os dispositivos acima elencados e as normas deles decorrentes no âmbito dos acordos em forma simplificada e segunda a partir de fundamentos de Direito Ambiental e Direito Ambiental Internacional, demonstrando-se a constitucionalidade dos dispositivos e das normas deles decorrentes a partir do que se chamou de fundamentos de base epistêmica, de base principiológica e de base jurídica. Ressalta-se esta construção metodológica combina-se, nos seus aspectos gerais, com o amparo do método dedutivo. / The environmental and climatic conditions of Antarctica have repercussions in Brazil and South America, constituting a central focus of concern to the extent that its equilibrium can be affected. For the Country and the Region the protection of the legal instruments of environmental protection, such as the Protocol to the Antarctic Treaty on Environmental Protection – PEPAT are fundamental. In order to speed up the application of PEPAT, its §3, Article 9 and several other provisions of its Appendix and Annexes allow the approval and entry into force of "Measures", which establish changes to its own Appendix or Annexes, in a year or ninety days after the closure of the respective ATCM in which they were adopted, without having to go through the respective internal processes of approval of the international treaties of the member countries of the TA, in the case of Brazil, by the approval of the National Congress. Under these conditions, these provisions could lead to violation of the provisions of item I, article 49 and the second part of item VIII, article 84, of the Federal Constitution-CF. Nevertheless, this dissertation advocates for the constitutionality of the devices and norms resulting from them. In order to justify the assertion, two different approaches it was assumed, the first one, supporting the constitutionality from traditional foundations of International Law, so that it includes the above mentioned devices and the norms derived from them under the Executive Agreements and second on the basis of Environmental Law and International Environmental Law, demonstrating the constitutionality of the devices and the norms derived from them, based on what have been termed epistemic fundamentals, based on principles and legal basis. This methodological construction is emphasized, in its general aspects, under the protection of the deductive method.

Na Antártica e no Ártico, a vida microbiana é presente e diversificada, tendo se adaptado a condições similares às encontradas em mundos que despertam interesse à astrobiologia. Este estudo investigou as alterações fisiológicas e fenotípicas do extremófilo psicrotrófico Exiguobacterium antarcticum B7 sob diferentes temperaturas. Foram utilizadas técnicas de eletroforese de proteínas em duas dimensões associada a espectrometria de massa, juntamente com técnicas de microscopia. E. antarcticum foi também submetida a condições físicas encontradas em Marte e no ambiente interplanetário. Seguindo evidências de que micro-organismos psicrotróficos podem também ser resistentes a períodos prolongados de dessecação, foi investigada a presença de linhagens microbianas resistentes a anidrobiose em solos da Antártica e permafrost do Ártico. Por fim, voltando-se à ecologia microbiana de solos polares permanentemente congelados, foi estudada a diversidade microbiana de três estratos de permafrost do ártico canadense com o uso de sequenciamento de DNA de nova geração. / In Antarctica and the Arctic, microbial life is present and diverse, having adapted to low temperature and low humidity conditions, similar to the worlds that arouse more interest to astrobiology. This study investigated the physiological changes of the psychrotrophic extremophile Exiguobacterium antarcticum B7 at different temperatures. Two dimensional protein electrophoresis techniques was used for proteome analysis in conjunction with mass spectrometry, as well as microscopy techniques. E. antarcticum was also subjected to physical parameters found on Mars and in the interplanetary environment. Following evidence that psychrotrophic microorganisms may also be resistant to prolonged periods of desiccation, it was investigated the presence of microbial strains resistant to anhydrobiosis on Antarctic soils and Arctic permafrost. At last, turning the attention to the microbial ecology of permanently frozen polar soils, it was studied the bacterial diversity of three Arctic permafrost strata with next-generation high throughput DNA sequencing.