Magister Scientiae - MSc (Dept. of Chemistry) / Fly ash and AMD samples were characterised by standard analytical methods for selection of the test materials. Active treatment by means of mixing fly ash with AMD in beakers and a large tank at pre-determined ratios have shown that fly ash is capable of neutralising AMD and increasing the pH beyond neutral values, which optimises the removal of heavy metals and ions. The trend was: the more fly ash added the quicker was the reaction time and higher the pH values achieved. Iron was reduced by as much 99 % in beaker scale experiments via Fe(OH)3 precipitation at pH values >4.0. A 99 % decrease in aluminium concentration was observed which was attributed to the precipitation of primarily gibbsite and various other mineral phases at pH values >5.5. As the pH increases, sulphate is adsorbed via Fe(OH)3 and gypsum precipitation at elevated pH. Sulphate attenuation with fly ash was excellent, achieving 98 % attenuation with beaker scale experiments and 1:1 fly ash:AMD ratio. Sulphate attenuation with fly ash was comparable to membrane and ion exchange systems and exceeded the performance of limestone treatment. Except for the larger volumes of fly ash needed to neutralise the AMD, fly ash proved to be a feasible and cost efficient alternative to limestone treatment. Fly ash produced competing results to limestone concerning acidity removal and sulphate attenuation. The comparison highlighted the advantages of utilising fly ash in comparison to limestone and demonstrated its cost effectiveness. The results of this study have shown that fly ash could be successfully applied for the neutralisation of acid mine drainage (AMD) and effectively attenuate the sulphate load in the treated water. The critical parameters to this technology are the variations of chemical composition and mineralogy of fly ash, which could influence the pH, contact time of the neutralisation reaction, and the same is true if the AMD quality varies. / South Africa

Neste trabalho estudaremos a existência de soluções fracas, semi-clássicas e clássicas, conceitos introduzidos no texto para uma classe de sistemas integro-diferenciais do tipo neutro com retardamento não limitado modelados na forma d/dt D(t, xt) = AD(t, xt) + ∫t0 B(t - s)D(s, xs)ds + g(t, xt), t ∈ (0, a), x0 = φ ∈ B, d/dt (x(t) + F(t, xt)) = Ax(t) + ∫t0 B(t - s)x(s)ds + G(t, xt), t ∈ (0, a), x0 = φ ∈ B, onde A é um operador linear fechado densamente definido em um espaço de Banach X, cada B(t) : D(B(t)) ⊂ X → X, t ≥ 0 é um operador linear fechado, a história xt : (-∞, 0] → X, xt(θ) = x(t + θ), pertence a um espaço de fase abstrato B definido axiomaticamente e D, F, g, G : [0, a] × B → X são funções apropriadas. Para obter alguns de nossos resultados, estudamos a existência e propriedades qualitativas de uma família resolvente de operadores lineares limitados (R(t))t≥0, para o sistema integro-diferencial d/dt (x(t) + ∫t0 N(t - s)x(s)ds) = Ax(t) + ∫t0 B(t - s)x(s) ds, t ∈ (0, a), x(0) = x0, onde (N(t)) t≥0 é uma família de operadores lineares limitados em X. Mencionamos que este tipo de sistemas aparece no estudo da condução de calor em materiais com memória amortecida. / In this work we study the existence of mild, semi-classical and classical solution, concepts introduced be later for a class of abstract neutral functional integrodifferential systems with unbounded delay in the form d/dt D(t, xt) = AD(t, xt) + ∫t0 B(t - s)D(s, xs)ds + g(t, xt), t ∈ (0, a), x0 = φ ∈ B, d/dt (x(t) + F(t, xt)) = Ax(t) + ∫t0 B(t - s)x(s)ds + G(t, xt), t ∈ (0, a), x0 = φ ∈ B, where A : D(A) ⊂ X → X is a closed linear densely defined operator in a Banach space X, each B(t) : D(B(t)) ⊂ X → X, is a closed linear operator, the history xt : (-∞, 0] → X, xt(θ) = x(t + θ), belongs to some abstract phase space B defined axiomatically and D, F, g :[0, a] × B → X are appropriate functions. To establish some of our results, we studied the existence and qualitative properties of a resolvent of bounded linear operators (R(t))t≥0, for a system in the form d/dt (x(t) + ∫t0 N(t - s)x(s)ds) = Ax(t) + ∫t0 B(t - s)x(s) ds, t ∈ (0, a), x(0) = x0, where (N(t)) t≥0 is a family of bounded linear operators on X. We mention that this class of system arise in the study of heat conduction in material with fading memory.

Ultracold neutral plasmas (UNP) are laboratory plasmas formed by the photoionization of a magneto-optically trapped and cooled gas. Because of their unusually low temperatures, UNPs are an example of a strongly coupled plasma, meaning that the potential energy of Coulomb interactions between particles is comparable to or greater than their thermal kinetic energy. In the field of strongly coupled plasmas, which also includes dense plasmas found in astrophysics and inertial confinement fusion experiments, there is a pressing need to better understand the collisional transport of matter, momentum, and energy between electrons and ions. The main result of this thesis is to demonstrate the existence of a new physical effect that significantly influences the electron-ion collision rates of strongly coupled plasmas. The essence of the effect is that the electron-ion collision rate depends explicitly on the sign of the colliding charges. This runs counter to both traditional plasma kinetic theory and modern extensions to strong coupling, all of which predict collision rates that do not depend on the sign of the electron-ion interaction. The effect is similar to a phenomenon observed charged-particle stopping known as the Barkas effect. The existence of the Barkas effect in the electron-ion collision rate of strongly coupled plasmas is first demonstrated using molecular dynamics (MD) simulations. A non-equilibrium simulation methodology is developed to extract the electron-ion collision frequency from the relaxation of an induced electron drift velocity. The simulations are carefully designed to ensure that the relaxation process can be modeled with a constant relaxation rate, which facilitates comparison with theoretical predictions developed later in the thesis. The Barkas effect becomes apparent when these simulations are repeated with positrons in place of electrons. It is seen that the positron-ion collision rate is always lower than the equivalent electron-ion one, and that this charge-sign asymmetry widens rapidly with increasing electron (or positron) coupling strength. It is hypothesized that the observed Barkas effect can be explained by accounting for plasma screening in the kinematics of binary electron-ion collisions. This is the main tenet of Effective Potential Theory (EPT), which assumes transport occurs through binary collisions governed by the potential of mean force. In order to apply EPT to electron-ion transport in UNPs, several new theoretical developments are made. First, it is demonstrated that EPT is able to accurately predict near-equilibrium transport in ionic mixtures as compared with equilibrium MD simulations. Next, a previously proposed model for the potentials of mean force in two-temperature positron-ion plasma is validated using a new two-thermostat MD methodology. Finally, EPT is applied to electron-ion transport in UNPs using a semi-analytic mapping between a two-component plasma and a screened one-component plasma system, which alleviates numerical difficulties in the theory associated with attractive interactions. The EPT predictions for the electron-ion and positron-ion relaxation rates are in excellent agreement with the MD simulations over the range of coupling strengths attained in present-day UNP experiments. EPT is thus shown to be the first transport theory for strongly coupled plasmas that accounts for the close-interaction physics that give rise to the Barkas effect in electron-ion transport.

Thesis (M.Sc. (Biochemistry)) -- University of Limpopo, 2011 / Soybean is one of the most cultivated legume plants in developing countries. Nodule senescence is a major limitation in producing high yields of soybean as it coincides with the pod filling stage. Delaying nodule senescence could be a way of increasing the yield of soybean therefore determination of the role of cysteine protease in soybean is of vital importance. In this study, soybean plants were grown under controlled temperature and light conditions. Leaves and root crown nodules were collected at 4, 6, 10, 12 and 16 weeks of age. In a comparative 1-dimensional SDS-PAGE analysis of soybean nodule proteomes as the plant matured, it showed differences in proteins expressed as shown by different banding patterns with less variation between the younger soybean nodule extracts (4, 6 and 10 weeks old) as compared to the older ones (12 and 16 weeks old). As determined by azocasein assay and protease zymography, the protease activity of the nodule extracts generally decreased with an increase in the age of the nodules whereas that of the leaves increased as the plants grew older. Cysteine proteases in the soybean nodule extracts readily cleaved the Z-Arg-Arg-AMC substrate with the highest activity shown in the younger nodules as compared to the older ones. In the leaf extracts, cysteine protease activity increased with age of the leaves. DCG-04, a biotinylated irreversible inhibitor, proved to be an effective label in profiling of activity of cysteine proteases in 1-dimensional and 2-dimensional systems. The labelling was inhibited specifically by cysteine protease inhibitor, E-64. In root nodules, the DCG-04 probing demonstrated that the expression of cysteine proteases is higher in early stages of development of the soybean nodules as compared to the later stages whereas in the leaves, there is higher expression of cysteine proteases in the old leaves (16 weeks). Using 2-dimensional polyacrylamide gel electrophoresis, five cysteine protease isoforms were visualised with the size ranging from approximately 25 to 30 kDa and a pI range of 4-6. In older nodules (12 and 16 weeks old) the higher pI isoforms are down-regulated with the 26 kDa and pI 4.5 protease being the predominant isoform. Affinity precipitation of the cysteine proteases yielded a strong band with the size of about 26 kDa. All assays used show that while in leaves, the expected trend of high expression of cysteine proteases in senescing leaves is observed, in soybean nodules the expression of cysteine proteases decreases with senescence. There is, therefore, no correlation between senescence and cysteine proteases in nodules. The highly expressed cysteine protease in young nodules could play a developmental or regulatory role during the early stages of development.

This thesis is concerned with weakly bound neutral and ionic clusters. Spectra of the region near the S1fS0 electronic origin of four neutral van der Waals molecules - aniline-argon, phenol-argon, chlorobenzene-argon and fluorobenzene-argon - were obtained using resonance enhanced multiphoton ionization (REMPI). These spectra indicate that Fermi resonances between van der Waals stretching and bending motions are important in these molecules. Effective Hamiltonians are constructed that describe well the low frequency vibrations. In order to better discuss the low frequency van der Waals motions of aromatics bound to one and two rare gas atoms a simple model for the vibrations is developed. The model enables expression of van der Waals frequencies in terms of fundamental molecular properties and enables facile comparison of effective force constants in a variety of van der Waals molecules. The model is successfully employed to explain van der Waals vibrational structure associated with the origin region of aniline-(argon)2 using van der Waals potential parameters derived from the aniline-(argon)1 spectrum. REMPI and emission spectra of larger clusters of aniline and argon are also reported and discussed. Using atom-atom potentials, equilibrium structures for aniline-(argon)n (n=l, 2, 3) are calculated. The calculations prove useful in the analysis of the spectra.The BfX transitions of the cation complexes fluorobenzene+-argon and chlorobenzene+-argon have been investigated. The cations were prepared by resonance enhanced multiphoton ionization of the neutral van der Waals molecules. A time delayed tunable dye laser was then used to dissociate the cations, loss of an argon atom being the dominant process. When the second laser was tuned to a cation resonance the dissociation cross section increased markedly, allowing characterization of BfX transition. The resulting spectra are presented and discussed.

<p>This essay focuses on men’s construction of feminism and gender and views on equality between the sexes. The purpose of the essay is met through interviews with eight men on their thoughts and constructions of these issues. The answers from the interviewed men were analysed with a radical feminist and gender perspective approach. The sources used in the analysis of the material, in the aspect of gender, were from the work of Judith Butler, Robert W. Connell and Yvonne Hirdman. The conclusion that can be drawn from this essay is that men view feminism as something positive but feminists as negative which is in line with results from previously published studies. Regarding gender the interviewed men were unfamiliar with the term and they discussed gender in terms of masculinity as something they felt did not apply to them. Equality between the sexes is by the interviewed men only pointed out and discussed as inequality in the labour market. This combined with a radical feminist analysis is interpreted as a denial of a feminist analysis that regards women as oppressed in all aspects of society not just in the labour market.</p>

<p>This study investigates interaction in eight sibling pairs aged 1-5 years with the purpose of examining the prevalence of certain variables constituting the interaction. The siblings were observed with video camera while playing with a toy brought along by the author. In order to validate and expand upon the information obtained from the observations, the parent(s) were asked to respond to a number of questions from a Questionnaire. The variables investigated were reciprocal and complementary interaction, asymmetrical roles, imitation, conflict, joint and parallel play and communication. The results obtained indicate that, in these eight sibling pairs, reciprocal interaction, that is interaction taking place on an equal level, is signified by joint play. Complementary interaction, that is interaction taking place on different levels, is signified by parallel play. High activity level for boys versus low activity level for girls in three sibling pairs were observed to correspond to gender-specific play activities in everyday life.</p>

<p>Den här uppsatsen syftar till att undersöka hur asylhandläggare på Migrationsverket uppfattar sin roll och sitt handlingsutrymme. Därtill hör även att utifrån den teoretiska ansatsen problematisera uppfattningarna för att undersöka om handläggarna kan förstås som neutrala verkställare enligt ett Weberianskt idealbyråkratiskt perspektiv eller snarare som närbyråkrater med stort handlingsutrymme enligt Michael Lipskys teori. Därutöver utgör en viktig del av syftet att problematisera utfallet av handläggarnas roll och handlingsutrymme för att belysa detta utifrån demokrati-, legitimitets- och rättssäkerhetsaspekter.</p><p>Uppsatsen kan förstås som en fallstudie där metoden för undersökningen utgjorts av samtalsintervjuer. Det empiriska materialet utgörs således av intervjuer med sex asylhandläggare från två olika asylenheter i landet. Samtliga respondenter har erfarenhet av att handlägga ärenden med humanitära grunder.</p><p>I uppsatsen har jag kommit fram till att sättet på vilket asylhandläggarna själva uppfattar sin roll och sitt handlingsutrymme främst kan relateras till en neutral verkställarroll enligt en Weberiansk modell. Den här uppfattningen är dock inte helt entydig, vilket exempelvis framkommer då vissa respondenter uppfattar att det faktiskt finns ett visst handlingsutrymme i utredningsarbetet. Det innebär att uppfattningen om rollen som neutral verkställare kan ifrågasättas. Trots att ett visst handlingsutrymme förekommer i utredningsarbetet, finns det dock en mycket tydlig juridisk styrning och därtill ett flertal olika kontrollmekanismer som sammantaget innebär att jag inte anser att asylhandläggarna bör förstås som närbyråkrater med stort handlingsutrymme enligt Lipskys teori. Kontrollmekanismerna och den tydliga styrningen som föreligger innebär också en ökad tilltro till möjligheterna att upprätthålla rättssäkerhet i myndighetsutövandet. Samtidigt pågår också arbetet med att öka insynen i Migrationsverket exempelvis genom att förtydliga bestämmelsen om humanitära skäl, vilket kan bidra till en ökad legitimitet. Vikten av den egna rollen och dess betydelse i ett vidare perspektiv är också något som markerats av flera respondenter. Asylhandläggarna uppfattar därmed att den egna rollen inte enbart syftar till att utreda och ge förslag till beslut i asylärenden; det handlar också om en roll i vilken strävan efter att bidra till upprätthållandet av legitimitet, demokrati och rättssäkerhet har en stor betydelse.</p>

<p>The attention on environmental issues has never been as huge as today. The climate is changing and more and more evidence suggest that the cause behind climate changes is an increase of carbondioxide into the atmosphere. The increase in turn is considerd to be an act of human activity. Therefore some companies have decided to become climate neutral and implement information technology in their business in order to reduce their emissions. This thesis has three aimes: to calculate a small company´s carbondioxide emissions, study whether or not information technology could help to reduce these emissions and furthermore find out why some companies decided to become climate neutral and describe the concept climate neutral. The results show that if information technology is used properly and effectively there are great potential to reduce the emissions, especially emissions from transportation sector. Now that the environment issues has become number one in the news and in the political agenda many companies try to cut their emissions, which is why some companies decided to take one step further and become climate neutral. Most of the companies see this action as a necessity in order to survive in a high competitive market. By doing so, they get more PR and more credit from both their investers and custumers. That is also why GreenIT´s carbondioxide emissions where calculated here. GreenIT have intentions in becoming climate neutral and in order to becoming one they have to reduce their remaining emissions by investing in projects in developing countries. As GreenIT is a small company they don´t have large emissions to reduce. This action will not cost them much but will probably give them an advantage in the market and credit from other investors and customers.</p>

<p>Fly ash and AMD samples were characterised by standard analytical methods for selection of the test materials. Active treatment by means of mixing fly ash with AMD in beakers and a large tank at pre-determined ratios have shown that fly ash is capable of neutralising AMD and increasing the pH beyond neutral values, which optimises the removal of heavy metals and ions. The trend was: the more fly ash added the quicker was the reaction time and higher the pH values achieved. Iron was reduced by as much 99 % in beaker scale experiments via Fe(OH)3 precipitation at pH values &gt / 4.0. A 99 % decrease in aluminium concentration was observed which was attributed to the precipitation of primarily gibbsite and various other mineral phases at pH values &gt / 5.5. As the pH increases, sulphate is adsorbed via Fe(OH)3 and gypsum precipitation at elevated pH. Sulphate attenuation with fly ash was excellent, achieving 98 % attenuation with beaker scale experiments and 1:1 fly ash:AMD ratio. Sulphate attenuation with fly ash was comparable to membrane and ion exchange systems and exceeded the performance of limestone treatment. Except for the larger volumes of fly ash needed to neutralise the AMD, fly ash proved to be a feasible and cost efficient alternative to limestone treatment. Fly ash produced competing results to limestone concerning acidity removal and sulphate attenuation. The comparison highlighted the advantages of utilising fly ash in comparison to limestone and demonstrated its cost effectiveness. The results of this study have shown that fly ash could be successfully applied for the neutralisation of acid mine drainage (AMD) and effectively attenuate the sulphate load in the treated water. The critical parameters to this technology are the variations of chemical composition and mineralogy of fly ash, which could influence the pH, contact time of the neutralisation reaction, and the same is true if the AMD quality varies.</p>