A crescente demanda por energia e a necessidade de promover o desenvolvimento sustentável colocam em foco os combustíveis renováveis. Dentro de biocombustíveis, os 2G ou segunda geração, têm como objetivo a utilização da energia contida na biomassa vegetal. Muitos microorganismos são capazes de excretar enzimas que quebram a lignocelulose, o principal componente das paredes celulares da planta, em açúcares fermentáveis. Os objetivos deste trabalho foram selecionar fungos filamentosos que produzem enzimas que degradam a biomassa e otimizar suas condições de cultivo. Quatro isolados e duas linhagems padrão foram testadas para a produção de celulases e identificadas pelo sequencimaneto da região ITS (Internal Transcribed Spacer). Após a caracterização inicial, três linhagens foram selecionadas e testadas em diferentes fontes de nitrogênio e carbono, e agentes tamponantes, visando o cultivo ótimo para cada delas. As condições ideais foram escolhidas com base em critérios de atividade enzimática, proteínas totais liberadas e pH. Após o estabelecimento das condições ótimas, os sobrenadantes das culturas foram liofilizados e o teor de proteínas determinado. O mesmo extrato foi testado quanto à FPA (Filter Paper Activity), atividades de β-glicosidase e xilanases, e quanto sua capacidade hidrolitica na biomassa pré-tratada. As linhagens selecionadas foram identificadas como Phanerochaete chrysosporium (F88), Aspergillus brasiliensis (F811) e a linhagem padrão Trichoderma reesei QM9414. A melhor combinação de fontes de nitrogênio foi a razão 4:3:3; 5:3:2 e 6:3:1 (sulfato de amónio, ureia e extrato de levedura) para F88, F811 e T. reesei, respectivamente. O ácido cítrico foi selecionado como agente tamponante para F88 e T. reesei, e PIPES para F811. Bagaço pré-tratado por explosão a vapor (BPT), como fonte de carbono, foi o melhor para induzir a produção de celulases e xilanases por F88 e F811, enquanto, Solka-Floc® foi a melhor para T. reesei. As atividades de β-glicosidase e xilanase foram maiores em F811 do que para T. reesei. No entanto, para FPA, T. reesei apresentou o melhor rendimento. Nos ensaios de hidrólise, as conversões de glicana e xilana foram semelhantes para ambas as linhagens, mesmo havendo acúmulo de celobiose no ensaio de T. reesei. Comparando os dados obtidos para ambas linhagens, uma selvagem e outra que é considerada referência industrial, F811 se mostrou promissor para a produção de enzimas hidrolíticas e como consequência, a habilidade em transformar a biomassa em açúcares fermentáveis. / The increasing demand for energy and the necessity to promote sustainable development has focused on renewable fuels. Within the available biofuels, 2G or second generation, has the aim of releasing the energy contained in plant biomass. Many microorganisms are able to secret enzymes capable of breaking down lignocellulose, the main component of plant cell walls, into fermentable sugars. The objectives of this project was to select filamentous fungi that produce enzymes that degrade biomass and optimize the growth conditions for them. Four isolates and two standards strains were tested for the production of cellulases and identified by ITS (Internal Transcribed Spacer) sequencing. After initial characterization, three strains were selected and tested in different sources of nitrogen and carbon, and buffering agents for optimal growth. The ideal conditions were chosen based on the criteria of enzymatic activity, total proteins released and pH. After the ideal condition for each strain were established, cell free extracts from each culture were lyophilized and the total protein content determined. This extract was tested for FPA (Filter Paper Activity), β- glucosidase and xylanase activity and the hydrolysis assays were carried out using pretreated biomass. The selected strains were identified as Phanerochaete chrysosporium (F88), Aspergillus brasiliensis (F811) and the standard strain Trichoderma reesei QM9414. The best combination of nitrogen sources was the ratio 4:3:3; 5:3:2 and 6:3:1 (ammonium sulfate, urea and yeast extract) for F88, F811 and T. reesei, respectively. Citric acid was selected as buffering agent for F88 and T. reesei, and PIPES for F811. Steam exploded bagasse, as a carbon source, was the best to induce the cellulase and xylanase production for F88 e F811, while, Solka-floc® was better for T. reesei. The activities of β-glucosidase and xylanase were higher for F811 than for T. reesei. However, for FPA, T. reesei showed the best yield. In the hydrolysis assays, conversions of glucan and xylan were similar for both strains, even though there was an accumulation of celobiose in the T. reesei\'s assay. Comparing the data obteined for both strains, a wild type and an industrial reference, F811 showed as a promising strain to produce hydrolytic enzymes and as consequence, break down biomass into fermentable sugars.

A crescente demanda por energia e a necessidade de promover o desenvolvimento sustentável colocam em foco os combustíveis renováveis. Dentro de biocombustíveis, os 2G ou segunda geração, têm como objetivo a utilização da energia contida na biomassa vegetal. Muitos microorganismos são capazes de excretar enzimas que quebram a lignocelulose, o principal componente das paredes celulares da planta, em açúcares fermentáveis. Os objetivos deste trabalho foram selecionar fungos filamentosos que produzem enzimas que degradam a biomassa e otimizar suas condições de cultivo. Quatro isolados e duas linhagems padrão foram testadas para a produção de celulases e identificadas pelo sequencimaneto da região ITS (Internal Transcribed Spacer). Após a caracterização inicial, três linhagens foram selecionadas e testadas em diferentes fontes de nitrogênio e carbono, e agentes tamponantes, visando o cultivo ótimo para cada delas. As condições ideais foram escolhidas com base em critérios de atividade enzimática, proteínas totais liberadas e pH. Após o estabelecimento das condições ótimas, os sobrenadantes das culturas foram liofilizados e o teor de proteínas determinado. O mesmo extrato foi testado quanto à FPA (Filter Paper Activity), atividades de β-glicosidase e xilanases, e quanto sua capacidade hidrolitica na biomassa pré-tratada. As linhagens selecionadas foram identificadas como Phanerochaete chrysosporium (F88), Aspergillus brasiliensis (F811) e a linhagem padrão Trichoderma reesei QM9414. A melhor combinação de fontes de nitrogênio foi a razão 4:3:3; 5:3:2 e 6:3:1 (sulfato de amónio, ureia e extrato de levedura) para F88, F811 e T. reesei, respectivamente. O ácido cítrico foi selecionado como agente tamponante para F88 e T. reesei, e PIPES para F811. Bagaço pré-tratado por explosão a vapor (BPT), como fonte de carbono, foi o melhor para induzir a produção de celulases e xilanases por F88 e F811, enquanto, Solka-Floc® foi a melhor para T. reesei. As atividades de β-glicosidase e xilanase foram maiores em F811 do que para T. reesei. No entanto, para FPA, T. reesei apresentou o melhor rendimento. Nos ensaios de hidrólise, as conversões de glicana e xilana foram semelhantes para ambas as linhagens, mesmo havendo acúmulo de celobiose no ensaio de T. reesei. Comparando os dados obtidos para ambas linhagens, uma selvagem e outra que é considerada referência industrial, F811 se mostrou promissor para a produção de enzimas hidrolíticas e como consequência, a habilidade em transformar a biomassa em açúcares fermentáveis. / The increasing demand for energy and the necessity to promote sustainable development has focused on renewable fuels. Within the available biofuels, 2G or second generation, has the aim of releasing the energy contained in plant biomass. Many microorganisms are able to secret enzymes capable of breaking down lignocellulose, the main component of plant cell walls, into fermentable sugars. The objectives of this project was to select filamentous fungi that produce enzymes that degrade biomass and optimize the growth conditions for them. Four isolates and two standards strains were tested for the production of cellulases and identified by ITS (Internal Transcribed Spacer) sequencing. After initial characterization, three strains were selected and tested in different sources of nitrogen and carbon, and buffering agents for optimal growth. The ideal conditions were chosen based on the criteria of enzymatic activity, total proteins released and pH. After the ideal condition for each strain were established, cell free extracts from each culture were lyophilized and the total protein content determined. This extract was tested for FPA (Filter Paper Activity), β- glucosidase and xylanase activity and the hydrolysis assays were carried out using pretreated biomass. The selected strains were identified as Phanerochaete chrysosporium (F88), Aspergillus brasiliensis (F811) and the standard strain Trichoderma reesei QM9414. The best combination of nitrogen sources was the ratio 4:3:3; 5:3:2 and 6:3:1 (ammonium sulfate, urea and yeast extract) for F88, F811 and T. reesei, respectively. Citric acid was selected as buffering agent for F88 and T. reesei, and PIPES for F811. Steam exploded bagasse, as a carbon source, was the best to induce the cellulase and xylanase production for F88 e F811, while, Solka-floc® was better for T. reesei. The activities of β-glucosidase and xylanase were higher for F811 than for T. reesei. However, for FPA, T. reesei showed the best yield. In the hydrolysis assays, conversions of glucan and xylan were similar for both strains, even though there was an accumulation of celobiose in the T. reesei\'s assay. Comparing the data obteined for both strains, a wild type and an industrial reference, F811 showed as a promising strain to produce hydrolytic enzymes and as consequence, break down biomass into fermentable sugars.

Service-oriented computing is a popular technology that facilitates the development of large-scale distributed systems. However, the modular composition and flexible coordination of such applications still remains challenging for the following reasons: 1) the services are provided as loosely coupled black boxes that only expose their interfaces to the environment; 2) interacting services are not usually known in advance: web services are dynamically chosen to fulfil certain roles and are often replaced by services with a similar functionality; 3) the nature of the service-based application is decentralised. Loose coupling of web services is often lost when it comes to the construction of an application from services. The reason is that the object-oriented paradigm, which is widely used in the implementation of web services, does not provide a mechanism for service interface self-tuning. As a result, it negatively impacts upon the interoperability of web services. In this dissertation we present a formal method for automatic service configuration in the presence of subtyping, polymorphism, and flow inheritance. This is a challenging problem. On the one hand, the interface description language must be flexible enough to maintain service compatibility in various contexts without any modification to the service itself. On the other hand, the composition of interfaces in a distributed environment must be provably consistent. Our method is based on constraint satisfaction and Boolean satisfiability. First, we define a language for specifying service interfaces in a generic form, which is compatible with a variety of contexts. The language provides support for parametric polymorphism, Boolean variables, which are used to control dependencies between any elements of interface collections, and flow inheritance using extensible records and variants. We implemented the method as a constraint satisfaction solver. In addition to this, we present a protocol for interface configuration. It specifies a sequence of steps that leads to the generation of context-specific service libraries from generic services. Furthermore, we developed a toolchain that performs a complete interface configuration for services written in C++. We integrated support for flexible interface objects (i.e. objects that can be transferred in the application along with their structural description). Although the protocol relies solely on interfaces and does not take behaviour concerns into account, it is capable of finding discrepancies between input and output interfaces for simple stateful services, which only perform message synchronisation. Two running examples (a three buyers use-case and an image processing application) are used along the way to illustrate our approach. Our results seem to be useful for service providers that run their services in the cloud. The reason is twofold. Firstly, interfaces and the code behind them can be generic as long as they are sufficiently configurable. No communication between service designers is necessary in order to ensure consistency in the design. Instead, the interface correspondence in the application is ensured by the constraint satisfaction algorithm, which we have already designed. Secondly, the configuration and compilation of every service are separated from the rest of the application. This prevents source code leaks in proprietary software which is running in the cloud.

Advances in wireless technology and the growing popularity of multimedia applications have brought about a need for energy efficient and cost effective portable supercomputers capable of delivering performance beyond the capabilities of current microprocessors and DSP chips. The SIMPil architecture currently being developed at Georgia Institute of Technology is a promising candidate for this task. In order to develop applications for SIMPil, a high level language and an optimizing compiler for the language are essential. However, with the recent trend of interconnect latency becoming a major bottleneck on computer systems, optimizations focusing on reducing latency are becoming more important, especially with SIMPil, as it is highly scalable. The compiler tracks the path of data through the network and buffers data in each processor to eliminate redundant communication. With a buffer size of 5, the compiler was able to eliminate 96 percent of the redundant communication for a 9x9 convolution and 8x8 DCT algorithms. With 5x5 convolution, only 89 percent elimination was observed. In terms of performance, 106 percent speedup was observed with 9x9 convolution at buffer size of 5 while 5x5 convolution and 8x8 DCT which have a much lower number of communication showed only 101 percent speedup.

The low molecular weight (L.M.W.) thiol redox couple formed by γ-L-glutamyl-L-cysteinyl glycine, also called glutathione (reduced and oxidized), is present in most eukaryotes and a few species of bacteria. Glutathione plays a role in numerous cellular processes by providing a means of shuttling electrons to different enzymatic systems. As a result, thiol-dependent redox metabolic processes are highly coupled. Due to tight coupling of redox reactions, it is difficult to understand how changes in the concentration of glutathione would affect a specific glutathione-dependent process. Interestingly, only a small subset of bacteria encode the canonical enzyme for the biosynthesis of glutathione, namely γ-glutamyl cysteine synthetase (gshA gene product). The mechanisms by which glutathione-dependent processes are carried out in bacteria which do not have the genes for biosynthesis of glutathione or other L.M.W. thiols is not well understood. A genetic selection to restore a glutathione-dependent phenotype in E. coli, lacking the gene involved in first step of glutathione biosynthesis (gshA), was used to address how bacteria lacking gshA might substitute for glutathione. Genetic and biochemical analyses of the E. coli mutants isolated in the selection revealed a de novo pathway for biosynthesis of γ-glutamyl cysteine, the product formed normally by GshA. Additionally we found that the unnatural analogue of glutathione, γ-glutamyl homocysteine could also be formed by this pathway. Bioinformatic analysis suggested that bacteria lacking gshA may use these de novo pathways for biosynthesis of γ-glutamyl cysteine or γ-glutamyl homocysteine, which could serve as potential substitutes for glutathione. The engineering of de novo biosynthetic pathways for γ-glutamyl cysteine and γ-glutamyl homocysteine provided us a strategy for engineering a pathway for biosynthesis of another unnatural analogue of glutathione, β-aspartyl cysteine. Both γ-glutamyl homocysteine and β-aspartyl cysteine could potentially be used as orthologus redox couples in E. coli operating in parallel to glutathione to shuttle electrons to specific pathways which may thus be decoupled from glutathione availability. Glutathione-dependent enzymes that can use orthologous redox couples instead are biochemically isolated from network of other redox reactions in the cell and could be used to direct metabolic fluxes to specific pathways with high efficiencies. Towards this end, we show that glutathione transferase, a glutathione-dependent enzyme, can be engineered to use analogous thiols like γ-glutamyl cysteine as cofactors. / text

What drives species diversity across landscapes is one of the most fundamental questions in ecology. Further, understanding the mechanisms underlying species diversity patterns is important not only for forming and challenging ecological theories but also essential for appropriate landscape management and effective nature conservation. This thesis focuses on patterns of vascular plant, moss and liverwort species richness and composition in relation to water flow in boreal-forest catchments, focusing mostly on riparian zones (RZs), that is terrestrial areas bordering streams and rivers. I addressed some of the most essential questions related to the ecology of riparian vegetation including the role of stream network position, groundwater (GW) flow paths, substrate availability, upland perturbations, and stream restoration. I also investigated how riparian soil processes and habitat properties relate to these factors in order to provide a holistic understanding of riparian dynamics. The results showed that the species richness and composition of riparian vascular plants, mosses and liverworts are strongly influenced by position along the stream network, GW discharge, presence of variable substrates in RZs, and by stream restoration. Generally, more species were found downstream in the network, at sites with inputs of upland GW, sites with high diversity of substrates (e.g., open mineral soil, rocks, stones, wood and bark), and along streams restored after channelization. This thesis also describes how riparian habitat properties responded to position in the landscape and human impacts, thus providing mechanistic links between plant species diversity and riparian processes across spatial scales. These ecological insights are further implemented into numerous recommendations for freshwater and upland management in boreal Sweden. Given that streams and rivers connect landscape elements both longitudinally and laterally I argue that management plans should be designed for entire catchments instead of individual river segments. Ignoring the connectivity of streams as well as the high connectivity of riparian areas to uplands via GW flows may result in failure of restoration, mitigation and/or protection actions. Further, during forestry operations more emphasis should be placed on GW discharge areas along streams and rivers, because they represent important ecological and biogeochemical hotspots in the landscape. The riparian buffers left along streams in boreal catchments affected by forestry are presently insufficiently wide and often uniform in width. This threatens the assemblages of species in GW discharge hotspots and the ecosystem services they provide. Overall, this thesis describes a holistic picture of riparian diversity patterns and riparian processes in boreal landscapes, acknowledges and elaborates on current ecological theories, presenting new patterns in biodiversity, and offers management guidelines.

La miniaturisation de circuits intégrés, les hautes fréquences de fonctionnement, la baisse des potentiels d'alimentation, les fortes densités d'intégration rendent les signaux numériques propagés sur les interconnexions très susceptibles à la dégradation voire à la corruption. En vue d’évaluer la compatibilité électromagnétique et l’intégrité du signal il est nécessaire de disposer dès les premières phases de développement de modèles précis de ces interconnexions pour les insérer dans les simulateurs temporels. Nos travaux s'inscrivent dans ce contexte et concernent plus particulièrement la modélisation comportementale des buffers et drivers de ligne de transmission. Ils ont abouti à une approche originale de modélisation notamment basée sur les séries de Volterra-Laguerre. Les modèles boites noires développés disposent d’une implémentation SPICE assez simple autorisant ainsi une très bonne portabilité. Ils sont faciles à identifier et disposent d’une complexité paramétrique permettant un gain important de temps de simulation vis-à-vis des modèles transistors des drivers. En outre les méthodes développées permettent une modélisation dynamique non linéaire plus précise du port de sortie, et une gestion plus générale des entrées autorisant notamment une très bonne prise en compte du régime de sur-cadencement ce que par exemple ne fait pas le standard IBIS. / Integrated circuits miniaturization, high operating frequencies, lower supply voltages, high-density integration make digital signals propagating on interconnects highly vulnerable to degradation. Assessing EMC and signal integrity in the early stages of the design flow requires accurate interconnect models allowing for efficient time-domain simulations. In this context, our work addressed the issue of behavioral modeling of transmission line buffers, and particularly that of drivers. The main result is an original modeling approach partially based on Volterra-Laguerre series. The black box models we developed have a fairly simple implementation in SPICE thus allowing a very good portability. They are easy to identify and have a parametric complexity allowing a large gain in simulation time with respect to transistor driver models. In addition, the developed methods allow a more accurate output port nonlinear dynamics modeling, and a more general management of inputs. A very good reproduction of driver behaviour in overclocking conditions provides a significant advantage over standard IBIS models.

Os solos ácidos recobrem, cerca de 40% da área terrestre, constituindo-se em um dos principais fatores limitantes à população à produção vegetal do planeta. No Brasil, os solos ácidos abrangem cerca de dois terços do território nacional. De um modo geral, a acidez do subsolo reduz a profundidade do sistema radicular, aumentando a susceptibilidade à seca e diminuindo o uso de nutrientes pelas plantas. Além da alta atividade de íon hidrogênio (H+), os solos ácidos geralmente apresentam níveis tóxicos de alumínio, sendo que a toxicidade por AI tem sido intensivamente investigada nos últimos anos. No entanto, a toxicidade por AI ocorre apenas a pH baixo e em condições onde a toxicidade por prótons geralmente também se manifesta. Apesar disto, trabalhos envolvendo a toxicidade por prótons são escassos. A sensibilidade de células a pH baixo depende da fase de crescimento e desenvolvimento em que estas se encontram. Em raízes, as células mais sensíveis são as da região de alongamento e em suspensões celulares as células na fase log de crescimento são mais sensíveis do que as células na fase estacionária. Este trabalho faz parte de uma linha de pesquisa que procura explorar as diferenças que existem entre células quanto à sensibilidade a pH baixo para melhor entender a toxicidade e tolerância a prótons. Foram utilizadas células da cultura de tabaco cv. BY-2, um sistema modelo que apresenta diversas vantagens sobre o uso de raízes para a realização deste trabalho. Os objetivos deste estudo foram de a) determinar condições apropriadas para a exposição destas células a acidez; b) caracterizar a resposta destas células a pH baixo, sob influência de diferentes fatores ambientais, quando se encontram em estados distintos de sensibilidade ao pH baixo; e c) verificar se mudanças na sensibilidade das células a pH baixo podem ser decorrentes de alterações na composição da membrana plasmática ou na atividade das ATPases. Vários testes iniciais foram realizados com o intuito de se definir algumas condições experimentais - o tempo de exposição, a composição do meio e o tampão a ser empregado. Optou-se por lavar as células e depois incubá-las por 1h em meio simples com pH desejado e contendo apenas Ca \'Cl IND. 2\' 2mM, KCl 10mM. E o tampão MES ou biftalato (10 mM). O biftalato foi testado porque o tampão MES, usado normalmente no meio de cultura completo, não é eficiente na faixa de pH abaixo de 5,0. O biftalato (pKa = 4,1) praticamente não afetou a viabilidade celular avaliada pela permeabilidade a trypan blue, mas inibiu o crescimento celular no meio de cultura completo. Mesmo assim, os dois tampões foram utilizados em paralelo em diversos experimentos e verificou-se que os resultados foram semelhantes. A viabilidade das células na fase log (2 dias) foi reduzida quando se abaixou o pH de 5,6 a 3,8, sendo que caiu mais acentuadamente até o pH de 4,8. As células da fase estacionaria (7d) foram insensíveis ao baixo pH. A um pH fixo de 4,2 aumentando-se a concentração de Ca \'Cl IND. 2\' para cerca de 8 a 16 mM praticamente aboliu o efeito deletério do pH baixo. Para se ter o mesmo efeito com a adição de KCl, foi necessário adicionar entre 80 e 160 mM. A adição de sacarose também amenizou os efeitos do pH\'sendo praticamente revertido a uma concentração de 100 Mm. Os resultados indicam a importância da força iônica e da osmolaridade da solução, mas o efeito de Ca não parece depender apenas destas duas propriedades. A inibição de ATPases, pelo uso de DCCD, não pareceu ter qualquer relação com a sensibilidade a pH baixo. Tanto células de tabaco na fase log quanto estacionárias foram sensíveis à aplicação de ortovanadato de sódio. Em células da fase estacionária, este efeito mais acentuado a pH 4,2, sugerindo que nestas células, as H+ ATPases do tipo P da membrana plasmática podem ter algum papel na tolerância destas células ao baixo pH. Encontrou-se diferenças no perfil protéico de frações enriquecidas em membrana plasmática entre células da fase log e estacionárias e entre células tratadas ou não a pH baixo. Estas diferenças precisam ser melhor estudadas. / Acid soils account for about 40 % of the surface area of the world and are one of the major factors limiting plant productivity. In Brazil, these soils comprise roughly two-thirds of its total territory. In general, soil acidity is detrimental because it limits the depth of the root system, increasing susceptibility to drought and decreasing the use of nutrients. In addition to the high levels of hydrogen ion activity, acid soils usually have Al toxicity hazards, a topic which has been intensely studied in the past years. However, Al toxicity only occurs at low pH, under conditions in which proton toxicity is also a problem. Despite this, studies of proton toxicity are lacking. The sensitivity of cells to low pH depends on their growth and developmental status. In roots, the most sensitive cells are those of the elongation zone and in cell cultures, cells in the log phase are more sensitive than those of the stationary phase. This study is part of a larger attempt to explore the differences that exist between cells with respect to their sensitivity to low pH to further understand toxicity and tolerance to protons. Cells of tobacco BY-2, a plant cell model system which has several advantages over the use of roots, was used in this study. The objectives were a) to determine the appropriate conditions to expose these cells to low pH; b) characterize the response of these cells to low pH, when different environmental factors are varied and at different stages of cellular sensitivity to acidity; and c) examine if changes in the sensitivity of cells to low pH are due to changes in the composition of plasma membranes or in the activity of ATPases. Several preliminary tests were performed to define the experimental conditions to be used ? the duration of exposure to low pH, the composition of the medium and the buffer to be used. A simple solution containing only CaCl2 2mM, KCl 10 mM and MES or phthalate buffer (10 mM) was chosen to wash and incubate the cells at the pH of interest. Phthalate was tested because MES, the buffer normally used in the culture medium, is not effective at pH values below 5.0. Phthalate (pKa = 4,1) had very little effects on cell viability as evaluated by membrane permeability to trypan blue, but it severely inhibited the growth of the cell culture in complete medium. Nevertheless, both buffers were used in several subsequent experiments, the results of which were found to be similar between both buffers. The viability of log-phase cells (2 day-old) was reduced when the pH was lowered from pH 5,6 to 3.8, but this was sharper down to pH 4,8. Cells in stationary phase (7 day-old) were insensitive to low pH. At a fixed pH of 4,2, increases in the concentration of CaCl2 up to 8 or 16 mM abolished most of the deleterious effects of low pH. To generate the same effect, KCl had to be added at concentrations between 80 and 160 mM. The addition of sucrose also alleviated the effects of low pH. The results suggest the importance of solution ionic strength and osmolarity on sensitivity to low pH, but the effects of Ca do not appear to depend only on these two properties. The inhibition of ATPases, by DCCD, did not appear to bear any relation to cellular sensitivity to low pH. Both log-phase and stationary-phase cells were affected by the addition of sodium orthophosphate. In stationary-phase cells, this effect was more pronounced at pH 4,2, suggesting that in these cells, P-type H+-ATPases of the plasma membrane may play a role in the tolerance of these cells to lo pH. Differences were found in the protein profile of enriched plasma membrane fractions both between log-phase and stationary-phase cells and between cells treated or not with low pH. These differences, however, need to be better examined.

Apart from the personal and socioeconomic burdens of dementia, the immense, intangible emotional and psychological suffering endured by dementia patients, their carers and families are difficult to quantify. Alzheimer’s dementia (AD) accounts for over 50% of all dementias and is responsible for a large percentage of morbidity and mortality in older adults. It is also recognised as a disease qualitatively distinct from the normal ageing process. Identified almost 95 years ago by Alois Alzheimer, it poses a seminal problem, which in the twenty-first century is compounded by the predicted extension in human longevity. Caregivers thus bear a considerable financial, social and emotional burden due to the progressive debilitating nature of the disease. It is hypothesised that social support buffers the individual from the negative emotional effects of stressful circumstances associated with the caregiving process; and although the inevitable course of the disease cannot be stopped, improving support to caregivers may decrease feelings of isolation and improve psychological health. Caregivers of AD patients often report experiencing a lack of social support due to the nature and progression of this disease. This study thus aims to investigate the relationship between real and/or perceived social support and psychological health (depression, loneliness, and perceived burden of care) amongst a cohort of Alzheimer’s caregivers. The following standardised measuring instruments were used to elicit data: the Zarit Burden Interview (ZBI), the Beck Depression Inventory (BDI-II), UCLA Loneliness Scale, Personal Resource Questionnaire (PRQ85) and a biographical questionnaire. Data were analysed using correlation and regression statistical techniques. The main findings of this study were that there is a significant positive correlation between loneliness and depression; loneliness and personal strain (burden) as well as both role and personal strain (burden) with depression. A significant negative correlation was also found between perceived social support and loneliness. Additional findings were that participants with higher educational qualifications experienced more personal strain and role strain (burden); caregivers with patients in the two younger age groups scored higher on the BDI-II; and the cognitive status of the patient correlated with the burden experienced by the caregiver. A significant negative correlation between summaries of reactions (burden) and duration of caregiving was also reported. / Dissertation (MA)--University of Pretoria, 2008. / Psychology / unrestricted

This diploma thesis deals with countercyclical measures of Basel III which will come into force in future. Thesis outlines the issue of cyclical effects which appeared in connection with application of Basel II and provides basic information about new treatment of this issue in Basel III. Further the thesis discusses preparedness of the czech banking sector for the introduction of countercyclical buffers and possibility of Tier I capital formation which should be the main part of the new bank capital adequacy including the capital buffers in future. Subsequently this thesis informs about conditions of using the countercyclical buffers and examines possible appropriate timing for their application. In the other parts of the thesis three selected foreign banking sectors and czech banking sector are examinated with the main focus on their weak spots and their possible development in the case of application of Basel III before the beginning of the world economic crisis in 2007 . In the end the stability of the czech banking sector is examined in detail by using the crisis scenarios and also the impact of application of Basel III before 2007 is discussed.