No description available.

No description available.

Coincident with human activity in recent decades, human-associated microorganisms have arrived to the Antarctic region, possibly linked to increasing presence of scientific bases and ship-borne tourists. In the Arctic, humans have been present for a very long time, and the few parts of the Arctic without human activities is decreasing with time. The studies in this thesis investigate the occurrence of different pathogens in Antarctic and Arctic wildlife, especially in birds. The first study shows the existence of Enteropatogenic Escherichia coli (EPEC) in Antarctic fur seals. The EPEC isolates were so called atypical EPECs, carrying the eae gene but lacking the bfp gene. This is the first record of a diarrheogenic E. coli in wild animals in the Antarctic. The second study displays that spreading of antibiotic resistance mechanisms appears to be much more efficient than previously was known. Enterococcus faecium isolated from Alaskan birds showed high resistance to vancomycin and teicoplanin, but also to ampicillin and ciprofloxacin. These isolates also carried vanA genes and the virulent esp gene, which places the isolates in the clinical clone CC17 and indicates the isolates had a human origin. Bacteria from birds that reside in the Bering Strait region in the third study, demonstrates that only six of 145 E. coli from 532 birds had reduced antibiotic susceptibility. Despite this, selective screen on E. coli showed only four ESBL-producing isolates. The four E. coli isolates carried CTX-M genes. One isolate belonged to the E. coli O25b - ST131 genotype, which is a successful clone with a global spread. In the fourth study, 123 seawater samples and 400 fresh penguin feces were analyzed. From these, 71 E. coli strains were isolated and only one E. coli from penguins was resistant to one antibiotic (cloramfenicol), whereas in E. coli from seawater, resistance against ampicillin, tetracycline, streptomycin and trim-sulfa were detected. E. coli carrying ESBL type CTX -M genes were also detected and Multilocus Sequencing Typing (MLST) showed six different sequence types (ST) previously reported in humans: ST131, ST227, ST401, ST410, ST685 and ST937. In the short time interval between the second study (2005) and the third study (2010) in relation to the fifth study (2012) we found a dramatic increase in antibiotic-resistant genes in the Arctic region. Enterococci, E. coli, and Kl. pneumoniae carried antibiotic resistance genes to an extent and variety not previously reported. E. coli from Arctic birds showed resistant to 1, 2, 3, 4, and 5 different antibiotics. Resistant gene type vanA was confirmed in enterococci and ESBL genes type TEM, SHV and CTX-M in E. coli and Kl. pneumoniae was detected. Multilocus Sequencing typing (MLST), indicating that both E. coli and Kl. pneumoniae carrying ESBL markers that connects them to the humans. In summary, the combined studies strengthen that bacteria that cause infections in humans could spread to relatively pristine environments. We concluded that human and associated antibiotic-resistant bacteria has reached a global level, then we showed that ESBL- carrying bacteria circulating nowadays also in the last ESBL-free continent, Antarctica.

Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, Discipline of Physics, 2005. / Includes author's previously published papers. Includes bibliographical references. Also available in a print form.

Inaug.-Diss.--Uppsala. / Sonderabdruck aus: 'Wissenschaftliche ergebnisse der Schwedischen südpolarexpedition" 1901-1902.' bd. v. "Litteraturverzeichnis" : p. 113-115.

Thesis (Ph.D.) - University of Queensland, 2002.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-05-03T16:06:14Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2016_Lins_Lins_Dissertation.pdf: 7915359 bytes, checksum: e74bf25e8b94ceb1f1b77ccb258a0276 (MD5) / Made available in DSpace on 2017-05-03T16:06:14Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2016_Lins_Lins_Dissertation.pdf: 7915359 bytes, checksum: e74bf25e8b94ceb1f1b77ccb258a0276 (MD5) Previous issue date: 2016-02-22 / capes / This thesis aimed to unravel processes driving meiofaunal community patterns in the deep sea. Benthic-pelagic coupling and various physical parameters, such as surface primary productivity, organic matter flux, sediment composition, chlorophyll and other pigments, fatty acids, and carbon and nitrogen, were measured as well as connectivity between studied areas. The study areas comprised four stations located at the abyssal plain of the Southern Ocean (SO) and ten stations situated at the lower continental shelf and mid-slope of the Western Iberian Margin (WIM). Benthicpelagic coupling was investigated by testing how surface primary productivity and export fluxes, as well as other environmental factors, relate to differences in meiofaunal diversity, density, and standing stocks, but also meiofauna distribution over local and regional scales. Moreover, spatial turnover and connectivity between bathymetrically different stations were analysed. In order to test our hypotheses, surface and benthic environmental parameters were calculated. At the SO, surface primary productivity values and particulate organic carbon fluxes were estimated. For both study areas, benthic environmental variables analysed included chlorophyll a and its derivatives, sediment composition, and total carbon and nitrogen. In addition, in the SO, sediment and nematode fatty acid concentrations were measured. Meiofauna and nematode community aspects included standing stock (biomass only for the SO), density and diversity for both areas, as well as nematode respiration for the SO. The potential role of connectivity was studied at the WIM through the use of 18S rDNA. Results showed that net surface primary productivity at the SO was positively associated with the diversity, abundance, and total fatty acid content of meiofauna and nematodes. This shows that primary production represents the fundamental energy source for the meiobenthos. The export of organic matter to the benthos is depth dependent though. This could be shown by a decrease with depth in organic matter arriving at the sea bottom exhibited at the WIM. These differences accounted for disparity of density and diversity of nematodes associated with a decrease in patchiness with increasing depth. Besides organic matter content, other factors, such as hydrodynamics, inferred through variation in sediment composition, shaped alpha and beta diversity in both studied environments by increasing habitat heterogeneity. Hydrodynamics were also identified as potential promoter of dispersal of selected nematodes. The lack of genetic differentiation between bathymetrically and geographically different areas indicated connectivity between the study areas. / Esta tese teve como objetivo estudar os principais fatores responsáveis por padrões ecológicos, em diferentes escalas, da meiofauna e, em especial, dos nematódeos de mar profundo. Neste estudo foi investigado o acoplamento bento-pelágico, sendo medidas variáveis ambientais (produtividade primária, fluxo de matéria orgânica, granulometria, clorofila, pigmentos, ácidos graxos, concentração de carbono e nitrogênio), além de fatores responsáveis por dispersão e conectividade genética em mar profundo. As áreas estudadas compreendem quatro estações localizadas na planície abissal do Oceano Austral e dez estações situadas na plataforma continental e talude da Margem Ibérica. O acoplamento bento-pelágico foi investigado através de como a produtividade primária na superfície e o fluxo de exportação de matéria orgânica, assim como outros fatores ambientais, são responsáveis por diferenças em diversidade, densidade, abundância e biomassa de meiofauna em pequena e grande escala. Além disso, a variação espacial e a conectividade entre as áreas de estudo com diferentes profundidades foram analisadas. Nas estações localizadas no Oceano Austral, a produtividade primária e o fluxo de matéria orgânica foram estimados. Para as duas áreas de estudo, as variáveis ambientais do sedimento analisadas incluíram clorofila a e seus derivados, granulometria, e carbono e nitrogênio totais. Adicionalmente, no Oceano Austral, ácidos graxos do sedimento e dos nematódeos foram medidos. Aspectos da comunidade de meiofauna e dos nematódeos estudados incluíram abundância, densidade e diversidade destes grupos para as duas áreas estudadas, assim como taxas de respiração e biomassa para o Oceano Austral. Além disso, aspectos de conectividade na Margem Ibérica foram analisados através do uso de técnicas moleculares usando 18S rDNA. Os resultados mostraram que a produtividade primária na superfície do Oceano Austral possuiu uma correlação positiva com diversidade, abundância e ácidos graxos totais da meiofauna e dos nematódeos. Estes resultados sugerem que a produtividade primária representa a principal fonte de energia para a meiofauna. Por outro lado, a concentração de matéria orgânica proveniente da superfície que chega ao fundo mostrou ser dependente da profundidade. Isto foi mostrado através da diminuição de matéria orgânica com o aumento da profundidade na Margem Ibérica. Estas diferenças mostraram variações em densidade e diversidade dos nematódeos associados com a diminuição em agregamento de matéria orgânica em relação ao aumento da profundidade. Além da quantidade de matéria orgânica, outros fatores, como hidrodinamismo, inferido através da variação na composição do sedimento, regularam diversidade beta nas duas áreas estudadas através do aumento da heterogeneidade de hábitat. Desta forma, o hidrodinamismo foi identificado como um fator potencialmente promovedor de dispersão em algumas espécies de nematódeos. A ausência de diferenças genéticas entre áreas com diferentes batimetrias e também geograficamente distintas indicou ausência de endemismo para os grupos abordados entre as áreas estudadas. Portanto, podemos concluir neste estudo que as comunidades de nematódeos para as áreas estudadas se mostraram principalmente dependentes da matéria orgânica proveniente da superfície, seja ela em forma lábil ou não, e da heterogeneidade de hábitat criada por fatores ambientais que afetam a distribuição do sedimento.

Orientador: Roy E. Bruns / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T00:57:18Z (GMT). No. of bitstreams: 1 Guadagnini_PauloHenrique_D.pdf: 1175328 bytes, checksum: 1d90b1cecc2001bf1f665148300c3852 (MD5) Previous issue date: 2000 / Doutorado

The discrete Fourier transform in Cartesian coordinates has proved to be invaluable in many disciplines. However, less theory has been developed for functions that are best described in polar coordinates. In this thesis, a new discrete 2D-Fourier transform in polar coordinates is proposed and tested by numerical simulations. Guidelines for choosing sample size are developed. Furthermore, to be as useful as its Cartesian counterpart, improvements are made to reduce the computing time.

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