During the Late Pliocene, between 3.3 Ma and 2.6 Ma, tectonic events changed ocean basin interactions against a background of shifting orbital forcing mechanisms and a global cooling trend. A climate system that had been locked in a stable, warm state gradually transformed into one typified by the high-amplitude glacial–interglacial fluctuations characteristic of the later Quaternary. The onset of Northern Hemisphere glaciations in the Late Pliocene marks an important step in this transition, due to the role of feedback mechanisms including ice albedo. A crucial factor in this Northern Hemisphere ice sheet expansion is the North Atlantic surface ocean circulation. To evaluate how they are linked, a ca. 200-kyr time slab spanning 2782-2520 ka (Late Pliocene–Early Pleistocene) was analyzed at millennial scale resolution from eastern North Atlantic Deep Sea Drilling Project (DSDP) Site 610 and Integrated Ocean Drilling Program (IODP) Site U1313. The causes of the Plio-Pleistocene climatic turnover are compared to that of the well-documented Marine Isotope Stage (MIS) M2 occurring in the Late Pliocene (3.3 Ma). MIS M2, a severe glacial event seen as a precursor to later Quaternary-style glaciations, was investigated from western North Atlantic DSDP Site 603. Utilizing a same-sample methodology, two paleoceanographic proxies were used: (1) dinocyst assemblages, and (2) foraminiferal geochemistry (δ18O and Mg/Ca). Dinocysts are proven tracers of sea-surface temperature (SST), salinity, nutrient supply, and sea ice cover, and are analyzed here to characterize the overlying water masses at the studied sites. Strong dinocyst assemblage fluctuations attest to variations in the influence of the North Atlantic Current (NAC). Using Mg/Ca ratios for the planktonic foraminifer Globigerina bulloides to determine absolute SSTs allows salinity changes to be reconstructed when combined with stable oxygen isotopes. This study shows a persistent Gulf Stream–NAC in the western North Atlantic during MIS M2, favoring a southern shift of the NAC over a shutdown of the thermohaline circulation. At the newly established Plio-Pleistocene boundary, a profound turnover in dinoflagellate cyst assemblages reveals a shift in ocean mode during MIS 104 (2.6 Ma). Three distinct dinocyst ecozones demonstrate this fundamental reorganization of the North Atlantic circulation.

Made available in DSpace on 2015-03-26T13:50:13Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2950242 bytes, checksum: 87a3fed7b278be1081be57b42f6f0be6 (MD5) Previous issue date: 2013-07-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The Earth s climate system is influenced by the topography configuration, whose importance is based on the characterization of the dynamic and thermodynamic aspects of the atmosphere and ocean. In this sense, the study aims to investigate the oceanic and atmospheric processes associated with the western Antarctic ice sheet collapse, which occurred 1.080 million years (ka) ago. Thus, two simulations were performed with the coupled climate model SPEEDO: a) the control simulation (CTRL) under current conditions and, b) forced simulation (1080ka), inserting the topography of 1.080 ka ago. Both simulations are conducted in the 2 CO atmospheric concentration of 380 ppmV. In the ocean circulation, the 1080ka simulation results show variations of salinity and temperature in relation to CTRL, at all ocean levels. Forcing contributed to an increase of approximately 1.4 °C and 1.6 °C in the sea surface temperature of the Ross and eastern Antarctic seas, plus the intensification of oceanic heat flux in the South Atlantic Ocean. On the other hand, there was an increase of 20 TW heat flow towards the north Pacific Ocean. These oceanic variations lead to changes in atmospheric circulations. The air temperature in the 1080ka simulation was 6.5 °C higher than CTRL in the Ross Sea region, contrary to the eastern region of Antarctic, where there was a decrease of 4.5 °C. In the precipitation field, there were an increase of approximately 160 mm/year in the Antarctic Peninsula and a decrease near 80 mm/year in the South Atlantic Ocean. The wind, at low levels, intensified in the South Atlantic anticyclone, moving towards South America continent. At high levels, the westward fluxes were weakened by the lower thermal gradient in the extratropical region. Although an intermediate complexity climate model was used, it was able to represent the main mass conservation mechanisms of the atmosphere and oceans. / O sistema climático da Terra é influenciado pela configuração da topografia, cuja importância fundamenta-se na caracterização dos aspectos dinâmicos e termodinâmicos da atmosfera e do oceano. Neste sentido, o objetivo do estudo é investigar os processos oceânicos e atmosféricos associados ao colapso das geleiras continentais da região oeste da Antártica, referente ao período de 1,080 milhão de anos (ka) passados. Para tal fim, foram realizadas duas simulações com o modelo climático acoplado SPEEDO: a) simulação controle (CTRL), sob condições atuais e; b) simulação forçada (1080ka), inserindo a topografia de 1,080 ka passados. Ambas as simulações são conduzidas com a concentração atmosférica de 2 CO em 380 ppmV. Na circulação oceânica, os resultados da simulação 1080ka mostram variações de salinidade e temperatura em relação à CTRL, em todos os níveis oceânicos. A forçante contribuiu para um aumento de aproximadamente 1,4 °C e 1,6 °C na temperatura da superfície do mar dos mares de Ross e a leste da Antártica, somados a intensificação do fluxo de calor oceânico ao sul do oceano Atlântico. Por outro lado, houve um acréscimo de 20 TW no fluxo de calor em direção ao norte do oceano Pacífico. Estas variações oceânicas conduzem a mudanças na circulação atmosférica. A temperatura do ar na simulação 1080ka foi 6,5 °C maior a CTRL na região do mar de Ross, inversamente a região leste da Antártica, onde ocorreu um decréscimo de 4,5 °C. No campo de precipitação, houve um aumento de aproximadamente 160 mm/ano na Península Antártica e uma diminuição próxima a 80 mm/ano no sul do Oceano Atlântico. O vento, em baixos níveis, foi intensificado no Anticiclone do Atlântico Sul, deslocando-se em direção ao continente sul-americano. Em altos níveis, os fluxos de oeste foram enfraquecidos, devido ao menor gradiente térmico meridional na região extratropical. Embora se tenha utilizado um modelo climático de complexidade intermediária, o mesmo foi capaz de representar os principais mecanismos de conservação de massa da atmosfera e dos oceanos.

Beaked whales are comparatively unknown social mammals due to their deep-ocean distribution and elusive habits. The deep-ocean is the largest biome on Earth and the final frontier for human expansion. Since their first discovery, beaked whales have remained largely hidden from science. In this era of rapid technological advancement, genetic and genomic methods are key tools for population biologists and are particularly useful in describing rarely seen species. Using DNA-barcoding and nuclear markers, the publications in this thesis provide data on the distribution and external appearance of two species of beaked whale: the spade-toothed (Mesoplodon traversii) and Derinayagala’s whale (Mesoplodon hotaula). These whales were previously known from only a handful of tissue and bone specimens. Long-term efforts have facilitated the collection of samples of Gray’s beaked whale (Mesoplodon grayi) and we have used shot-gun sequencing to characterise the mitochondrial genome and isolate species-specific nuclear microsatellite loci. Using genetic species and sex identification, together with museum specimens and multivariate analyses, we provide clear evidence of sexual dimorphism in cranial dimensions and geographic variation in external morphology. No genetic differentiation was evident in Gray’s beaked whales across a large study area (~ 6,000 km). With a large female effective population size (Ne) and genetic homogeneity, we hypothesise that gene flow is facilitated by large-scale oceanographic features, such as the sub-tropical convergence. Genetic kinship analyses within Gray’s beaked whale groups suggest that the whales that strand together are not related. Both sexes disperse from their parents and these groups are not formed through the retention of kin. These results are consistent with a ‘fission-fusion’ social system that has been observed in some oceanic dolphin species. Taken together, these data provide the first insights into the population dynamics, dispersal and social organisation in Gray’s beaked whales. These publications highlight the value of using genetics alongside other techniques to describe inter- and intraspecific diversity. For beaked whales, the dead can tell us much about the living.

Doctor Pharmaceuticae - Dpharm / The brain laterality of pharmacists may influence where the pharmacists are best suited to work. Brain laterality refers to the asymmetry of the hemispheres of the brain with regard to specific cognitive functions, such as objectivity and emotion. The left hemisphere functions objectively and rationally, whereas the right hemisphere is subjective and nonrational. Animal behaviour in the literature demonstrated an influence of brain laterality, thus selecting an ideal work environment may also be driven by brain laterality bias. Further support for the research included: amblyopia; hemiplegia; the WADA test. The research question investigated the matching of the brain laterality groups of pharmacists to their ideal work environments. The aims investigated: ear, eye, hand and foot dominance in determining brain laterality; influence of brain laterality and reductionistic variables on job choice; location of emotion generation and job choice. Five objectives investigated these aims: influence of brain laterality alone; influence of brain laterality and reductionistic variables; influence of a new brain laterality determining continuum; Propinquity Principle in achieving data; correctness of the Right Hemisphere Theory (RHT) or the Valence Theory (VT). The RHT suggests that the right hemisphere is dominant in processing all emotion. The VT argues that the left hemisphere is specialised in processing the positive emotions while the right hemisphere is specialised in processing the negative emotions. The resulting Null Hypothesis posits that there is no statistical difference between the different brain laterality groups enabling pharmacists to work competently in any placement. The Alternative Hypothesis was that there is a statistical difference between the brain laterality groups, thus brain laterality can be used to best place pharmacists into ideal placements. Global warming questions in the questionnaire determined positive and negative emotion as well as enthusiasm for global warming problems. In South Africa, probability cluster sampling was applied utilising postal and email methods. In the UK, non-probability purposive sampling was applied utilising four methods: snowballing, email, postal, and convenience sampling. Both countries produced similar results for the same sample size.

L'ozone joue un rôle primordial sur l'équilibre photochimique de l'atmosphère et participe au processus d'équilibrage radiatif entre les deux hémisphères (Mecke, 1931). Dans la troposphère, l'ozone détermine la capacité oxydante de la majorité des gaz et absorbe continuellement dans la stratosphère les radiations ultraviolettes nocives (McMicheal et al., 2003). D'où l'intérêt de surveiller la variation de la couche d'ozone de façon régulière. Il a été constaté au début des années 80, une diminution inquiétante et progressive de la colonne totale de l'ozone dûe aux émissions anthropiques des substances riches en chlore, brome et fluor. Ce constat a conduit au Protocole de Montréal en 1987 dont l'objectif est de mettre en place une politique internationale visant à réduire les émissions des substances appauvrissant l'ozone. Dix ans après la signature du dit Protocole, la concentration de ces substances commence à diminuer dans l'atmosphère et la prospection d'un recouvrement progressif de la couche d'ozone demeure aujourd'hui un sujet d'actualité (UNEP/PNUE, 2009 ; OMM, 2010 et 2014). Les besoins d'aujourd'hui sont de réaliser des mesures continues et fiables de l'ozone dont leurs exploitation dans des méthodes et/ ou des modèles bien adaptés à la problématique aideront la communauté à suivre l'évolution de l'ozone et d'estimer les tendances à long terme. Dans ce travail, une variété de produits d'ozone issue de différents instruments a été combinée pour construire des bases des données fiables et homogènes afin d'étudier sa variabilité et d'estimer la tendance de l'ozone dans les régions tropicale et subtropicale sud. L'application de ces bases de données sur les ondelettes a permis d'identifier les principaux forçages qui contrôlent la variabilité de l'ozone et la période de retour associée à chaque forçage. Il s'agit des variations saisonnières du climat, les oscillations quasi-biennales, les oscillations australes El-Niño et l'activité solaire dont le cycle moyen est évalué à 11ans. Le comportement et l'influence de chacun de ces paramètres sur la viabilité de l'ozone sont étudiés. Cette étude est faite en s'appuyant sur des méthodes statistiques et sur le modèle Trend-Run. Avec ce modèle, la part de contribution et la réponse de chaque paramètre sur la variabilité de l'ozone sont quantifiées. Les résultats sur les tendances montrent une augmentation de la couche d'ozone avec un taux variant entre 0 et 2.78% par décade (selon la région et le site) sur la période 1998-2012. Cette amélioration est bien observée au-dessus de 22km, surtout aux subtropiques par rapport à la région équatoriale. / Ozone plays an important role on photochemical equilibrium of atmosphere and participate on radiative balance process between hemispheres (Mecke, 1931). In the troposphere, ozone determines the oxidizing capacity of major species and absorbs continuously in the stratosphere the harmful ultraviolet radiation (McMichael et al, 2003). Based on the above facts, it is important to monitor ozone continuously with consistency and accuracy. Global total column ozone (TCO) has depleted gradually since 1980 with an increase of chlorofluorocarbon concentrations in the stratosphere due to anthropogenic activities. In 1987, the Montreal protocol was formulated in order to regulate the emissions of substances that deplete ozone. Concentrations of these substances are observed to decrease ten years after the Montreal protocol. Thus we have been expecting an increase in ozone by now (UNEP/PNUE, 2009; WMO, 2010 and 2014). The current needs are to achieve consistent and reliable measurements in which their exploitation on adapted methods/models can help scientists to follow the ozone evolution and to estimate long term ozone trend. In this work, a variety of ozone products from different instruments was combined in order to create reliable and homogenous dataset to study the ozone variability and trend over the southern tropics and subtropics. The dataset application on wavelets method allowed to identify the dynamic parameters that control ozone variability and their periodicities. These include seasonal variations of climate, the quasi-biennial oscillations, the El-Niño Southern Oscillation and the 11-years solar cycle. The behavior of each parameter and its influence on ozone variability were analysed based on statistical method and the Trend-Run model. The contribution and response of each variable on ozone variability were quantified from the model. The obtained trends results exhibit an increase of total ozone from 1998 to 2012 with a rate varying between 0 and 2.78% par decade (depending of the site and region). The ozone increase was observed mainly above 22 km and it is more important over the subtropical region with respect to equatorial zone.

The purpose of this study is to show that instructional methods designed for right-brained students will make a significant difference in the reading achievement scores of the students when compared with the scores of right-brained sixth grade students not receiving these instructional methods.The subjects were sixth grade students who use the right hemisphere of the brain to a greater degree than the left hemisphere. The subjects' cerebral preference was determined by a test known as the Cerebral Preference Index (CPI). Ten students each were chosen from two sixth grade classes. The study consisted of a Control Group and Experimental Group. During the study the Control Group received eight weeks of the regular school's program while the Experimental Group received eight weeks of instructional strategies that take hemispheric specialization into consideration. The results indicated that there was no significant difference in the reading achievement scores of those students who received the instructional methods designed for right brained students. The analysis of data did suggest that those scoring high on the pre-test scored high on the post test. The results indicated the same outcome for low scorers.

No description available.

MENVSC (Climatology) / Department of Geography and Geo-Information Sciences / Subtropical anticyclones locate and modulate weather and climate over subtropical belts for both the Northern and Southern Hemispheres. This study investigates the spatio-temporal variability of the Mascarene High over the South Indian Ocean on (anomalous) weather and climate over southern Africa at intraseasonal, seasonal, interannual, multidecadal and event time-scales. The Mascarene High is located 25-35°S, 40-110°E, playing a vital role in day-to-day weather and climate patterns conditions over southern Africa. Spatio-temporal characteristics of the Mascarene High investigated in this study span the period 1985-2014 and 2071-2100, using NCEP-NCAR reanalysis datasets for present-day climate observations and the Conformal-Cubic Atmospheric Model (CCAM) for future projections. The Mascarene High is analysed using mean sea level pressure (MSLP) extracted from ECMWF ERA-interim monthly reanalysis data. The Mascarene High is also subjected to Principal Components Analysis, depicting eastern displacements of the weather system to be dominant for weather and climate fluctuations over southern Africa. The Mascarene High migrates south (north) during austral summer (winter) and is centred over the eastern Indian Ocean in summer in connection with the Indian Ocean Subtropical Dipole. Event scale analysis is also employed for investigating Mascarene High blocking and induced anomalous weather. Mascarene High blocking leads to anomalous rainfall events over southern Africa associated with tropical cyclones, cut-off lows and cloud bands. There is also a vital geographical variability of the Mascarene High development, distribution and movement in the South Indian Ocean at the different time-scales. Projections of the Mascarene High indicate a shift in mean location as a result of future expansion and intensification. This projected expansion and intensification is expected to shift tropical cyclone trajectories equatorward, with the baroclinic structure of cold fronts expected to shift poleward affecting changes in the weather and climate of southern Africa. This finding is important as it projects changes in weather and climate conditions over southern Africa in a changing climate due to increased greenhouse gas emissions.

Le mercure (Hg) est un métal émis dans l’atmosphère par des sources naturelles et anthropiques. Il est préoccupant à l’échelle mondiale de par sa propagation atmosphérique sur de longues distances, loin des sources d’émissions, sa persistance dans l’environnement, son potentiel de bioaccumulation dans les chaînes alimentaires aquatiques et ses effets néfastes sur la santé humaine. Les modèles atmosphériques, utilisés pour retracer son cheminement depuis les sources d’émissions jusqu’aux dépôts au sein des écosystèmes, sont entachés de fortes incertitudes en raison notamment de notre compréhension partielle des processus atmosphériques (réactions d’oxydo-réduction, dépôts, réémissions) et du manque de données d’observations à l’échelle planétaire. L’objectif de ces travaux de thèse est d’améliorer notre compréhension du cycle atmosphérique du Hg en trois sites reculés de l’Hémisphère Sud : l’île d’Amsterdam (AMS) en plein océan Indien, Concordia (DC) sur la calotte glaciaire antarctique et Dumont d’Urville (DDU) sur la côte Est du continent. Les données acquises à AMS démontrent une réactivité atmosphérique limitée du Hg dans cette région du globe. L’île étant faiblement et rarement influencée par des masses d’air continentales polluées, il s’agit d’un site clé pour la surveillance, sur le long terme, du bruit de fond atmosphérique aux moyennes latitudes de l’Hémisphère Sud. Les données acquises en Antarctique démontrent l’existence de processus inédits en termes de réactivité dans l’atmosphère et à l’interface air-neige. Les processus observés sur la calotte glaciaire influent par ailleurs sur le cycle du Hg à l’échelle continentale du fait des forts vents catabatiques. Ces avancées scientifiques permettront, à terme, de contraindre et d’améliorer les modèles atmosphériques globaux. / Mercury (Hg) is a metal emitted by both natural and anthropogenic sources. It is of global concern owing to its long-range atmospheric transport, its persistence in the environment, its ability to bioaccumulate in ecosystems, and its negative effects on human health. Large uncertainties associated with atmospheric models – that trace the link from emissions to deposition of Hg onto environmental surfaces – arise as a result of our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission) and of the scarcity of monitoring data at a global scale. The aim of this PhD work is to improve our understanding of the atmospheric Hg cycling at three remote sites of the Southern Hemisphere: Amsterdam Island (AMS) in the Indian Ocean, Concordia (DC) on the East Antarctic ice sheet, and Dumont d’Urville (DDU) on the East Antarctic coast. Data acquired at AMS suggest a limited atmospheric reactivity of Hg in this part of the globe. The advection of polluted continental air masses being scarce, AMS is a key site for the long-term monitoring of the atmospheric background in the Southern Hemisphere mid-latitudes. Data acquired in Antarctica highlight the occurrence of unprecedented processes in the atmosphere and at the air-snow interface. Due to katabatic winds flowing out from the East Antarctic ice sheet down the steep vertical drops along the coast, processes observed at DC influence the cycle of atmospheric Hg on a continental scale. These scientific breakthroughs will ultimately lead to improved global transport and deposition models.

No description available.