Dans le modèle de formation hiérarchique des structures, les amas de galaxies se forment et grandissent par l'accrétion de groupes plus petits ou de galaxies isolées. Dans ce scenario, comprendre comment les galaxies accrétées interagissent avec cet environnement très dense est une étape importante pour comprendre le schéma global de l'évolution des galaxies et de la formation des structures. En effet, pendant leur chute au coeur de l'amas, les galaxies sont sujettes à diverses interactions avec l'amas hôte, au niveau de leur composante baryonique aussi bien que matière noire, et ces interactions vont modifier les propriétés de la galaxie. Au niveau de la matière noire, les simulations numériques suggèrent que la friction dynamique fait plonger les galaxies vers le centre de l'amas, et que les forces de marée exercées par l'hôte peuvent arracher une partie de la matière de la galaxie, et même détruire celle-ci. Ce processus, au cours duquel une partie de la matière noire de la galaxie est arrachée, est appelé stripping. La détection du stripping de matière noire contient d'importantes informations sur l'évolution des groupes et des amas. Le travail principal de cette thèse se concentre sur l'étude des galaxies dans les amas, et en particulier sur l'étude du stripping des galaxies par les forces de marées des amas. Les profils de densité des halos sont mesurés à l’aide de l’effet de lentille gravitationnelle faible, en utilisant les catalogues de formes de galaxies des relevés CFHTLenS, CFHT Stripe 82 et DES-SV, alliés au catalogue d’amas redMaPPer. / Galaxy clusters are large structures in the Universe, composed of tens or hundreds of galaxies bound by gravity. In the hierarchical formation model, they are formed and grow by accretion of smaller groups or isolated galaxies. In this scenario, understanding how these accreted galaxies interact with the very dense cluster environnement is an important step towards explaining the global picture of galaxy evolution and structure formation. Indeed, during infall, galaxies are subject to numerous interactions with the host cluster, both at the level of the baryonic and dark matter component, and these interactions influence the properties of the infalling galaxy. At the level of dark matter, numerical simulations suggest that dynamical friction sinks galaxies towards the center of clusters, and tidal forces of the host can strip part of the satellite's matter away, and even disrupt it. The detection of this stripping contains important informations on the evolution of groups and clusters: what quantity of dark matter is associated to the cluster galaxies as a function of the distance to the centre of the cluster ? How does this depend on the redshift and dynamical state of the cluster ? Does stripping depend on the morphological type of cluster galaxies ? The main work of this thesis is focused on studying galaxies in clusters, in particular tidal stripping of their dark matter haloes. The dark matter halo profiles are measured with weak gravitational lensing, using galaxy shape catalogues from the CFHTLenS, CFHT Stripe 82 and DES-SV surveys, combined with the redMaPPer cluster catalogue.

No description available.

The aim of this diploma thesis is to design a stripping column according to given requirements. At the beginning, the contaminant is described, in this case ammonia. Next section is putting emphasis on stripping columns, the principle, possible construction options etc. The main part of this thesis is focused on the design itself, including calculation of various parameters as well as simplified construction possibility. Drawing documentation is included in the attachment.

No description available.

No description available.

Faculty of Science School of Animal Plant and Enviromental Sciences 0404336v lmcnamara@gpf.co.za / Pine saw timber plantation forestry on the Eastern Escarpment of South Africa contributes significantly to the economy of the country. Losses to plantation value through fire, insects and disease, and particularly over the last decade, losses due to baboon damage are of serious concern. Anecdotal evidence indicated that baboons damage pine trees shortly following pruning operations and at certain times of the year. A perception existed that damage has increased dramatically, yet no documented evidence to this effect is available. As a result two physiological studies were undertaken to investigate whether changes in nutrient concentration of inner bark tissues of pine trees on the Eastern Escarpment of South Africa, act as triggers for baboon damage. A literature review was also undertaken to document the extent of baboon damage, tree volume and associated economic costs. A comparison was made with Zimbabwe, where baboon damage is quoted to be a severe threat to the continued viability of plantation forestry. The first study investigated changes in nutrient concentration of the soft, inner bark tissue of Pinus patula, in response to pruning measured in five year old plantations in the Mpumalanga Province, South Africa. Samples of tissues were collected from pruned and unpruned trees at 2, 7, 14 and 28 days after 26% of the live crown had been removed in the pruning treatment. Results indicated that live pruning of Pinus patula did not influence nutrient concentration of inner bark tissues at set intervals post pruning. Treatment differences of aggregate data for sample interval showed that potassium concentration increased by 0.03% whereas magnesium concentration decreased by 0.02% following pruning. Aggregate data for treatment showed that phosphorus, carbohydrates (fructose, glucose, sucrose and starch), boron and nitrogen concentration, and moisture content of inner bark tissues varied during the short time period of the study. Variations are attributed to iv the commencement of growth, translocation of nutrients from needles and branches and possibly moisture stress. Results from the study do not support anecdotal evidence that baboon damage to pine plantations which increases shortly after pruning operations is as a direct physiological response to the pruning event. In this study it is much more likely that changes in nutrient concentrations coincided with a remobilization of resources in response to seasonal triggers. In the second study, nutrient concentrations of the inner bark of Pinus patula and Pinus taeda growing on the Eastern Escarpment of South Africa were studied over a seasonal cycle in order to investigate the allegations that baboon damage in the plantations was related to the degree of nutrient remobilization. Significant differences were found in phosphorus concentration and moisture content across seasons and between baboon damaged and undamaged trees. Undamaged Pinus taeda trees recorded the highest phosphorus levels in April 2003 (0.13%). Moisture content was lowest in damaged Pinus patula trees in August 2003 (57%). Anecdotal evidence that baboon damage to pine trees on the Eastern Escarpment of Mpumalanga increases prior to the growing season is supported by the significant changes in inner bark tissue concentration. Nutrient translocation prior to needle fall alters inner bark nutrient concentration, as does moisture stress and demand for nutrients prior to cambial activity. Pine bark is easier to peel during periods of peak cambial activity. These factors are discussed as they may trigger baboon damage. Significantly higher inner bark tissue concentrations of sucrose (4.25 versus 2.61%), starch (4.75 versus 2.84%) and nitrogen (0.61 versus 0.49%) in Pinus taeda compared with Pinus patula, supports anecdotal evidence that Pinus taeda is preferentially damaged by baboons. Baboon damaged trees contained higher concentrations of zinc (30.4 versus 22.3 ppm) and calcium (0.26 versus 0.20%), and lower concentrations of sucrose (2.95 versus 3.91%) and starch (3.21 versus v 4.39%) than undamaged trees, which was attributed to resource allocation to wound response and not that baboons selected trees with higher concentrations of zinc or calcium. The variability of inner bark tissue concentration due to a number of factors highlights that baboon damage in pine plantations is not readily answered, and remains a complex problem. A literature review was undertaken of reported baboon damage occurrence and intensity of damage, following statements that baboon damage to pine plantations is rapidly escalating in the Mpumalanga Province, South Africa. The extent and intensity of baboon damage from the first reported damage (1960’s) until current levels are documented. A comparison is made between Zimbabwe and South Africa where the baboon damage is viewed as a serious problem. The extent of baboon damage in Zimbabwe, expressed as the total percentage of area damaged by baboons as a function of the total area planted to pine for the period 2000-2004 has escalated from 10.8 to 13.3% despite harvesting activities removing damaged trees (Fergusson, 2004). The total area with reported baboon damage in Zimbabwe amounted to 5 317 hectares in 2004 (Fergusson, 2004). In South Africa baboon damage has increased markedly from the first reports of 300 hectares in 1980 (Bigalke, 1980) to 7 641 hectares in 2004. The average percentage of trees damaged in affected compartments is 20.4% with the percentage increasing from 17.2 to 23.6% from 2002-2004. Pinus taeda appears to be the most severely affected species with Pinus elliottii showing increasing levels of damage in many compartments in 2004. Quantifying the value lost by baboon damage to the industry requires reliable assessment methods that are cost effective to implement. Assessment methods need to take into account the position of the damage on the stem, and resultant saw log value that is lost. Assessment methods implemented in South Africa and Zimbabwe are described, and results given by method applied. A standard assessment method is required for comparisons to be made between areas vi with baboon damage. An investigation in Zimbabwe highlighted significant differences between standing tree volume estimations (4.98 – 7.59 m3/ha, with various methods), and actual volume losses (50.45 m3/ha) (Ngorima et. al., 2002). The associated Rand value loss determined by the South African assessment method in 2004 was in excess of 20 million Rand. This estimated loss in revenue does not include losses of incremental growth due to the damage, re-establishment costs, loss of thinning and clearfelling product revenue due to timber wastage, or losses experienced in down line processing at the saw mill. The extent of the baboon damage problem warrants proactive management, continued monitoring and investment into research in order to gain a better understanding of the problem. The increase in the extent of baboon damage from early documented figures is most alarming, showing that the baboon damage problem continues to grow.

none

Made available in DSpace on 2018-08-24T22:53:15Z (GMT). No. of bitstreams: 1 tese_5199_Dissertação definitiva Felipe.pdf: 3695373 bytes, checksum: 835da901132eebe5561ff320277b9841 (MD5) Previous issue date: 2011-09-15 / O lixiviado de aterro sanitário possui alto potencial poluidor, com elevadas concentrações de cloretos, matéria orgânica e nitrogênio amoniacal. Seu processo de tratamento é muito complexo e geralmente envolve diferentes tecnologias. Devido à sua eficácia, o stripping é um tratamento amplamente utilizado para a remoção de NH3 de lixiviado. Esta pesquisa focou no processo de air stripping para remoção de amônia do lixiviado produzido na Central de Tratamento de Resíduos Vila Velha, CTRVV. Para tanto, as influências da variação de pH e da vazão de ar sobre a resposta do processo foram consideradas. Além disso, abordou a relação entre as remoções de alcalinidade total e nitrogênio amoniacal, bem como a formação de espuma. Para realização da parte experimental, foram realizados ensaios com 1 L de lixiviado, usando torres de arraste de com 90 cm de altura e 10 cm de diâmetro interno, em temperatura ambiente e tempo de batelada de 4 h. O experimento foi dividido em duas etapas. A Etapa I teve por objetivo direcionar metodologicamente o procedimento experimental. A Etapa II foi planejada a partir dos conhecimentos obtidos na Etapa I. Os resultados apresentaram eficiências de remoção de amônia 56%, 72% e 83% para as taxas de vazões de ar 2 NL.L-1.min-1, 5 NL.L-1.min-1 e 10 NL.L-1.min-, respectivamente. Com as variações do pH natural da amostra, pH 10, pH 11, e pH 12, obteve-se uma diferença média de 6%, entre os ensaios, sendo que o maior eficiência média foi de 75% para pH 12. Concluiu-se que a taxa de vazão de 5 NL.L-1.min-1 foi a mais adequada para remoção de amônia em lixiviado e a aplicação do pH inicial igual a 10 apresentou ser a mais vantajosa, que para pH 11 e pH 12.

<p> The (t,p) reaction has been performed on targets of 151Sm, 176Yb and 178Hf. The experiment was performed with 15 MeV tritons. The outgoing protons were analyzed with the Enge split-pole spectrograph. Angular distributions were measured for all three nuclei with special emphasis being placed on L=0 transitions.</p> <p> The angular distributions for the 151Sm(t,p)153Sm reaction showed that the distribution of L=0 strength among the low-lying states is not consistent with expectations based on the detailed wavefunctions for 151Sm and 153Sm calculated by two independent groups; Katajanheimo and Hammaren (1978) and Rekstad et al. (1978). The distributions also showed that the total L=0 strength, summed over the four observed states in 153Sm, is much less than for neighbouring nuclei.</p> <p> Angular distributions of the (t,p) reaction on 176Yb and 178Hf targets showed strong L=0 transitions to levels at ~ 1.3 MeV excitation. It is believed that the N=108 energy gap in the Nilsson diagram is the cause of the large L=0 strength observed. At present no quanitative calculation has reproduced the observed phenomenon, however a calculation based on the Volkov model is presently being considered.</p> / Thesis / Master of Science (MSc)

No description available.