An analysis of climate change in Nigeria has been carried out. The aim was to investigate the environmental impact of Green house gases. The three zones of the country namely the extreme North, the middle zone and the extreme South have all been separately examined with respect to changes in solar radiation, temperature, precipitation and evaporation. The agricultural productivity for each zone was compiled, and trend plots over time carried out. Correlation tests were done between productivity and climatic changes and it was found that each zonal area reacted differently to changes in climate. The emission of carbon dioxide, methane and the oxides of nitrogen in Nigeria were calculated and trends plotted. A correlation test was also carried out between carbon dioxide emission and temperature change for each zone. The relationship between temperature change and productivity was shown in a regression model. An economic appraisal for Nigeria involving the GDP, pollution and population was examined in terms of the productivity- pollution index. This was also extended to some of the Western countries

This thesis addresses the parameterisation of chemical and dynamical processes in the Antarctic stratosphere. Statistical models for the inter- and intra-annual variability in Antarctic stratospheric ozone depletion were developed based on theory and an understanding of the coupling of dynamics and chemistry in the atmosphere. It was confirmed that the primary driver of the long-term trend in the severity of the Antarctic ozone hole is halogen loading in the stratosphere. The year-to-year variability in ozone mass deficit, a measure of the severity of Antarctic ozone depletion, could be described by a linear combination of South Pole temperatures and midlatitude wave activity. A time lag of two weeks between wave activity effects and ozone depletion indicates the predictive capability of meteorological parameters for seasonal projections of the severity of the Antarctic ozone hole. The statistical model describing the inter-annual variability in ozone mass deficit was regressed against observations from 1979 to 2004. The resulting regression coefficients were applied to South Pole temperature and wave activity fields from 28 chemistry-climate models. This analysis indicates a slight increase in the year-to-year variability in the severity of Antarctic ozone depletion. As a prelude to analysing the seasonal evolution of Antarctic ozone depletion, an improved ozone mass deficit measure was derived by replacing the constant 220 DU threshold with a seasonal varying pre-ozone hole background which leads to better capturing the true extent of the depleted ozone. Furthermore, it was shown that the new measure represents the chemical ozone loss within the Antarctic vortex provided that no mixing occurs through the vortex boundary. This new measure has many advantages over previous stratospheric ozone depletion indices. The conventional ozone mass deficit omits large amounts of depleted mass of ozone, and the onset of ozone depletion does not coincide with the timing of when sunlight first reaches areas of polar stratospheric clouds as expected from theory. Chemical ozone loss derived with a tracer-tracer correlation technique depends on ozone and passive tracer profile measurements which are not as readily available as the total column ozone fields required for the new ozone mass deficit presented in this thesis. As such, the new ozone depletion measure combines the simplicity of the old ozone mass deficit index with higher accuracy of the actual amount of chemically depleted stratospheric ozone. Furthermore, when applying the new definition of ozone mass deficit to chemistry-climate model outputs, model intercomparisons should become easier to interpret because biases in the models can be avoided. Based on theory and understanding of the coupling of chemistry and dynamics in the Antarctic stratosphere, two semi-empirical models were developed to describe the intra-seasonal evolution of chlorine activation and ozone depletion. Regression of the models against chlorine monoxide and ozone mass deficit from observations results in coefficients that capture key sensitivities in the real atmosphere. The seasonal evolution of ozone mass deficit can be described with these coefficients and readily available meteorological fields (temperature and wind fields). The predictive capability of these models was demonstrated for 2005 and 2006. Given temperature and wind fields, which for example can be obtained from general circulation models, these models can predict the size and depth of the Antarctic ozone hole. Important applications of the semi-empirical models could be chemistry-climate model validation by comparing the sensitivities from observations and models which may provide new insights into potential sources of differences in chemistry-climate model projections of Antarctic ozone depletion. Furthermore, projection of the inter-annual and intra-seasonal evolution of the Antarctic ozone hole into the future can help to assess the potential recovery of the Antarctic ozone hole.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-03Bitstream added on 2014-06-13T20:37:40Z : No. of bitstreams: 1 silva_ap_me_guara.pdf: 3513689 bytes, checksum: 6088e29c7edf5f22abc24fa7d1c6a6ac (MD5) / O ataque químico seletivo para alteração da composição superficial de ligas de ouro, é um processo que permite retirar os elementos de liga, de uma camada superficial de uma peça confeccionada com liga de ouro, produzindo assim uma camada formada por uma liga mais resistente aos ataques químicos e de cor diferente da liga original. Reagentes e procedimentos para aplicação do processo, apresentando baixa toxidez e fácil aquisição, foram aplicados em corpos de prova confeccionados com a liga de ouro ternária 75 Au, 12,5 Cu, 12,5 Ag, obtendo-se camadas com composição alterada com espessuras de até 50 æm. Reagentes diferentes produziram camadas de composições diferentes. O reagente contendo Na Cl, K NO3 e Fe2 SO4, mostrou maior eficiência na remoção do cobre, não interferindo significativamente no porcentual de prata, produzindo uma camada com porcentual de cobre praticamente igual a zero e o porcentual de prata em torno dos valores originais da liga. O reagente contendo Na Cl, K NO3 e KAl (SO4)2, apresentou remoção total da prata e do cobre, produzindo uma camada com 50 æm de espessura, composta praticamente de 100% de ouro. / The selective chemical attack for alteration of the superficial layer of gold alloys is a process that allows the removal of base metals and silver from the surface layer, of one part made with gold alloy, thus producing a layer composed of a more resistant alloy to the chemical attacks and with different color from the original alloy. Reagents and procedures, composed of low toxicity and easy acquisition substances, had been applied in test specimens prepared with ternary gold alloy 75 Au, 12,5 Cu and 12,5 Ag, getting layers with composition modified with thicknesses up to 50 æm. Different reagents had produced layers of different compositions. The reagent contend Na Cl, K NO3 and Fe2 SO4 showed great efficiency removing copper and not intervening significantly with the silver percentage, producing a layer with practically no copper and the silver amount around the original values. The reagent contained, Na Cl, K NO3 and KAl (SO4)2 showed total removals of the silver and copper, producing a layer 50 æm thick, composed basically of gold.

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The key objective of this study was to examine whether leucocyte depletion generated or removed platelet-derived microvesicles in platelet concentrates for transfusion. Three in-process leucocyte removal filters for pooled buffy coat derived platelet concentrates, i. e. negative charged polyester, positively charged polyester, and non-charged polyurethane, were compared. The effects of three major leucocyte depletion technologies currently in use in the UK, i. e. Cobe LRS and Haemonetics MCS+ LD apheresis, and filtration of pooled buffy coat derive platelets, on platelet microvesiculation were also examined. Furthermore, the effects of various leucocyte filters and leucocyte depletion technologies on platelet activation and the activation of coagulation/complement systems were investigated. The procoagulant and anticoagulant properties of microvesicles isolated from platelet concentrates were explored. Leucocyte filtration of pooled bully coat derived platelet concentrates by all three filters did not have a net effect on the level of microvesicles. All three leucocyte depletion technologies gave similar values of microvesicles on day 1, but on day 5 MCS+ LD apheresis showed the lowest value, whilst Cobe LRS apheresis and buffy coat methods were equivalent. Among the three filters, the negatively charged filter activated the coagulation system as measured by kallikrein-like and thrombin-like activities, but removed some activated complement C3a, whereas the positively charged filter generated C3a. Among the three leucocyte depletion technologies, platelets prepared by Cobe LRS showed the lowest degree of activation of the coagulation system. However, both Cobe LRS and MCS apheresis showed higher levels of C3a than filtered buffy coat derived platelets. The microvesicles isolated from day 1 platelet concentrates could act as a catalytic surface for both the coagulant and anticoagulant reactions as measured by the formation of prothrombinase complex and the inactivation of FVa by activated protein C. The microvesicles isolated from day 5 platelets showed an increased procoagulant activity, whereas the anticoagulant activity substantially diminished.

For a variety of reasons Whites often expect negative interracial interactions. Previous research suggests that negative expectations for interracial interactions often lead to negative interaction experiences. Specifically, interracial interactions are experienced as cognitively depleting, engendering of negative affect, and devoid of behavioral mimicry"u2014a nonconscious behavior that engenders liking, and smooth, harmonious interactions. Because individuals do not expect mimicry in interracial interactions, when mimicry is present individuals experience cognitive depletion. While the majority of research has focused on how White individuals"' expectations for interracial interactions lead to self-regulatory efforts that ultimately are cognitively depleting, the present research proposes that the behaviors of one"'s interaction partner must also be considered. It was predicted that Whites who expect positive interracial interactions would not experience cognitive depletion when mimicked by a Black person, but would experience depletion when they are not mimicked. Conversely, Whites expecting a negative interracial interaction were predicted to experience cognitive depletion when mimicked by a Black person, but would not experience depletion when not mimicked. Findings revealed that the interaction between mimicry and interaction expectations on cognitive depletion was not significant. Counter to predictions, those with positive interaction expectations experienced the most cognitive depletion following an interracial interaction. Consistent with predictions, significant interactions between mimicry and interaction expectations revealed that, for those with positive expectations, not being mimicked was associated with decreased positive affect and increased negative affect. These findings suggest that mimicry in interracial interactions may not be counternormative for those who expect positive interactions, and its absence (rather than its presence) may lead to negative emotional outcomes. / 1 / Tara Van Bommel