Les Polluants Organiques Persistants (POPs), largement présents dans l'environnement via les stations d'épuration des eaux usées (STEP) et l'activité anthropique de l'Homme constituent une source de contamination du milieu aquatique. L'évaluation du risque environnemental de ces composés implique leur analyse chimique quantitative et spécifique et l'estimation de leur origine vis-à-vis des zones contaminées. Cette étude consiste en une analyse qualitative et quantitative, à l'échelle internationale, pour une trentaine de composés organiques représentatifs en termes d'utilisation et pertinents en termes d'impact environnemental. L'approche mise en œuvre intègre une étape de détection et une étape d'évaluation de la toxicité des composés ciblés afin d'estimer leur niveau de risque écotoxicologique. La détection de ces composés dans les matrices sédiments a nécessité la mise au point d'une méthode d'extraction Soxhlet et le développement d'une méthode de détection par GC-MS. La validation de cette méthode a permis de mener à bien une campagne d'échantillonnage de 54 stations répartis sur 4 bassins versants (l'Arc, l'Huveaune, la Durance, l'étang de Berre et le Oued Medjerda), afin d'évaluer le niveau de contamination par les POPs. Ce travail se propose d'effectuer un échantillonnage orienté (avant et après des ouvrages majeurs tels que STEP, Industries …) de sédiments des différents cours d'eaux de la zone Méditerranée et d'étudier à la fois les taux de contamination ainsi que l'origine des POPs. Sur le plan régional et international, ce sujet répond à une demande sociétale forte. / Persistent Organic Pollutants (POPs), largely present in the environment via sewage wastewater (WWTP) and anthropogenic activities are a source of contamination of the aquatic environment. The environmental risk assessment of these compounds involves their specific and quantitative chemical analysis and estimation of their origin next to the contaminated areas. This study was a qualitative and quantitative analysis, internationally, for about thirty organic compounds representative in terms of use and relevant in terms of environmental impact. The approach used incorporates a detection step and a step for evaluating the toxicity of the compounds targeted to estimate their level of ecological risk. The detection of these compounds in the sediment matrix required the development of a Soxhlet extraction method and the development of a method of detection by GC-MS. Validation of this method allowed to carry out a sampling campaign of 54 stations spread over four watersheds (Arc, Huveaune, the Durance, the Etang de Berre and Oued Medjerda), to assess the level of contamination by POPs. This work intends to carry out a guided sampling (before and after major works such as STEP, industries ...) sediments of different rivers in the Mediterranean area and study both infection rates and the origin of POPs. At the regional and international levels, the subject responds to a strong societal demand. Indeed, it is essential to characterize the quality of streams and to estimate their contamination. This work has allowed a consistent inventory level of contamination. The PAH analysis is done by gas chromatography-mass spectrometry (GC / MS).

Soil organic matter (SOM) plays an important role in the global carbon cycle. Therefore, it is important to understand the stability of SOM, which is related to several processes. Its intrinsic properties may be related to its stability, for example black carbon is considered to be relatively resistant to degradation. In most soils, the dark horizons coincide with the superficial layers or horizons due to the greater accumulation of organic matter, but in the southern states of Brazil, the presence of soils with dark subsurface horizons is frequently observed. The dark subsurface horizon of these soils are similar to a sombric horizon. Aspects about its origin, formation and preservation have not yet been fully elucidated. The objective of this work is to understand the formation of \'sombric\' horizons in soils of the region from Tijucas do Sul (Paraná, Brazil). Five soil profiles were described and collected, from which three originate from a toposequence and contained a \'sombric\' horizon (P1-P3), a reference soil that is representative of the area (P5) and an intermediate soil (P4) that showed morphology between the reference soil and the soils with a \'sombric\' horizon. To this end SOM is studied for its molecular composition by the pyrolysis technique coupled to gas chromatography and mass spectrometry (pyrolysis-GC-MS). In addition, 13C isotopic composition (δ13C) and phytolytic composition were studied in order to understand paleoclimatic conditions. These results will be related to past environmental conditions using 14C dating techniques, and supported by classical soil analysis. The samples of the horizons were submitted to the SOM chemical fractionation, generating two fractions: extractable fraction with NaOH (EXT) and residue (RES). The morphology of the profiles showed an intense biological activity in A horizons and a wide distribution of microfragments of charcoals. The lateral continuity of \'sombric\' horizons in toposequence soils was also observed, which differentiated them (P1-P3) from buried A horizons. The distribution of SOM in the fractions studied was the same for the five profiles studied: EXT> RES. Products related to wildfires such as polyaromatics (PAHs; BC) were found in all profiles, but in greater relative abundance in the \'sombric\' horizons, indicating a higher incidence of fire during the formation of these horizons and these compounds can be related to the maintenance of dark color of the \'sombric\' horizons. In relation to the paleoclimatic conditions it was observed that the dark subsurface horizons were developed during the Mid-Holocene under vegetation composed mainly by C4 grasses with shrubs, evidencing a drier climate corresponding to a higher fire incidence. / A matéria orgânica do solo (MOS) desempenha um papel importante no ciclo global do carbono. Portanto, é importante entender a estabilidade da MOS, que está relacionada a vários processos. As suas propriedades intrínsecas podem estar relacionadas com a sua estabilidade, por exemplo, o \"black carbon\" é considerado relativamente resistente à degradação. Na maioria dos solos, os horizontes escuros coincidem com as camadas ou horizontes superficiais devido ao maior acúmulo de matéria orgânica, mas nos estados do sul do Brasil, a presença de solos com horizontes subsuperficiais escurecidos é frequentemente observada. O horizonte subsuperficial escurecido destes solos assemelha-se a um horizonte sômbrico. Aspectos sobre sua origem, formação e preservação ainda não foram totalmente elucidados. O objetivo deste trabalho é compreender a formação de horizontes \'sômbricos\' em solos da região de Tijucas do Sul (Paraná, Brasil). Foram descritos e coletados cinco perfis de solo, dos quais três estão localizados em uma topossequência e continham um horizonte similar ao sômbrico (P1-P3), um solo de referência representativo da área (P5) e um solo intermediário (P4) que apresentou uma morfologia entre o solo de referência e os solos com horizonte \'sômbrico\'. Para este fim, a MOS foi estudada pela sua composição molecular através da técnica de pirólise acoplada à cromatografia gasosa e espectrometria de massa (pirólise-GC-MS). Além disso, estudou-se a composição isotópica 13C (δ 13C) e a composição fitolítica, a fim de compreender as condições paleoclimáticas que foram relacionados com as condições ambientais passadas usando técnicas de datação com 14C, e suportados pelas análises clássicas de solo. As amostras dos horizontes foram submetidas ao fracionamento químico MOS, gerando duas frações: fração extraível com NaOH (EXT) e resíduo (RES). A morfologia dos perfis mostrou uma intensa atividade biológica nos horizontes A e uma ampla distribuição de microfragmentos de carvão. Observouse também a continuidade lateral de horizontes \'sômbricos\' em solos da topossequência (P1-P3), diferenciando-os dos horizontes A enterrados. A distribuição da MOS nas frações estudadas pela pirólise foi a mesma para os cinco perfis: EXT> RES. Os produtos relacionados a incêndios florestais como os poliaromáticos (PAHs, BC) foram encontrados em todos os perfis, mas em maior abundância relativa nos horizontes sômbricos, indicando uma maior incidência de incêndio durante a formação destes horizontes. Os PAHs podem estar relacionados com a manutenção da cor escura dos horizontes \'sômbricos\'. Em relação às condições paleoclimáticas observou-se que os horizontes subsuperficiais escurecidos foram desenvolvidos durante o Holoceno Médio sob vegetação composta principalmente por gramíneas C4 com arbustos, evidenciando um clima mais seco correspondente a maior incidência de incêndio.

Neste trabalho prepararam-se ésteres de ácidos graxos por esterificação do ácido oléico e transesterificação do óleo de soja e do triéster oléico via catálise enzimática. Determinou-se a composição dos produtos obtidos por RMN 1H e CG-FID. Os padrões dos ésteres do ácido oléico via esterificação ácida foram preparados empregando ácido sulfúrico, os padrões dos ésteres do óleo de soja por transesterificação básica com hidróxido de sódio e o padrão do triéster oléico foi sintetizado utilizando ácido p-tolueno sulfônico como catalisador. A melhor enzima para essas reações foi determinada através de reações de esterificação do ácido oléico e transesterificação do óleo de soja com etanol na ausência de co-solventes, sendo que foi selecionada a lipase de Candida antarctica. A mesma enzima foi empregada nas esterificações enzimáticas do ácido oléico com diversos alcoóis (metanol, etanol, n-propanol e n-butanol), na transesterificação enzimática do óleo de soja e do triéster oléico com etanol. Em ambos os estudos, foram avaliados os fatores que influenciam as reações: quantidade de enzima; tempo de reação; água adicionada ao álcool e reuso do biocatalisador. Na esterificação enzimática do ácido oléico, o uso do etanol forneceu o melhor rendimento (96,5%) com 5,0% (m/m) de enzima em 24 horas de reação. Quando uma quantidade de 4,0% de água foi adicionada ao álcool, a reação utilizando metanol mostrou maior eficiência (98,5%) e os rendimentos com os outros alcoóis não foram alterados significativamente (acima de 90%). Também foi possível utilizar a enzima por até 10 ciclos sem perda de rendimento, com exceção do metanol, onde ocorreu um decréscimo acentuado de rendimentos nos ciclos seguintes. Na transesterificação enzimática do óleo de soja, os mesmos fatores foram avaliados e com 5,0% de enzima, após 24 horas, foi obtido um rendimento de 84,1% e com a adição de água o rendimento não foi significativamente alterado (83%). Na transesterificação, os métodos de quantificação por RMN 1H e CG-FID foram comparados sendo que uma maior diferença foi observada para as reações com baixos rendimentos por RMN 1H, porém em altos rendimentos a diferença entre os dois métodos não foi significativa. Monoglicerídeos e diglicerídeos foram quantificados por CG-FID e por RMN 1H onde foi possível calcular a razão dos produtos formados através de uma equação desenvolvida, sendo que a diferença entre esses tipos de análises foi pequena, de apenas 1,4%. A transesterificação enzimática do triéster oléico foi obtida em bom rendimento (90,4%) e uma pequena quantidade de mono- e diglicerídeos foi produzida. Em todas as reações de transesterificação, o glicerol não foi detectado após a lavagem dos produtos. A metodologia empregando a lipase de Candida antarctica mostrou-se eficiente para a produção de biodiesel a partir do óleo de soja e do ácido oléico com diferentes tipos de alcoóis. / In this work, it was prepared esters of the fatty acid by esterification of the oleic acid and transesterification of the soy oil through enzymatic catalysis. It was determined the composition of the products obtained by 1H NMR and GC-FID. The standards of esters of the oleic acid by acid esterification was prepared employing sulfuric acid, the standards of esters of the soy oil by alkaline transesterification with sodium hydroxide and the standard of the oleic triester was synthesized employing p-toluene sulfonic acid as catalyst. The best enzyme for those reactions was determined through reactions of esterification of the oleic acid and transesterification of the soy oil with ethanol and free co-solvents, and lipase from Candida antarctica was selected. The same enzyme was employed in the enzymatic esterifications of the oleic acid with various alcohols (methanol, ethanol, propanol and butanol), in the enzymatic transesterification of soy oil and the oleic triester with ethanol. In both studies, was assessed the factors that influence the reactions: amount of catalyst, reaction time, water added in the alcohol and the turnover of biocatalyst. In the enzymatic esterification of the oleic acid, the ethanol showed the better yield (96,5%) with 5,0% (m/m) of enzyme at 24 hours of reaction. When 4,0% of water was added to the alcohol, the methanol showed the high efficiency (98,5%) and the yield with another alcohols were not affected. It was also possible to use the enzyme for 10 cycles without lose yield, except for the methanol. In the enzymatic transesterification of the soy oil, the same factors were assessed using 5,0% of enzyme, after 24 hours, a yield of 84,1% was obtained and with the water addition the yield was not modified (83%). On the transesterification, 1H NMR and GC-FID were compared and a great difference was observed for low yields, but on high yields, the difference between methods was small. Monoglycerides and diglycerides were quantified by GC-FID and detected by 1H NMR, it was possible to calculate the ratio between them on the products formed through an equation developed and the difference for this type of analysis was small, only 1.4% . The enzymatic transesterification of the oleic triester was obtained with good yield (90,4%) and a small amount of the monoglycerides and diglycerides was produced. In all the transesterifications reactions, glycerol was not detected after washing mixture of products. The methodology employing Candida antarctica lipase was efficient for biodiesel production by soybean oil and oleic acid with different alcohols.

War Schelling ein politischer Denker? Und wenn ja, wie lässt sich seine politische Denkweise einordnen? Die Antworten auf beide Fragen gehen in der Forschung weit auseinander. Die vorliegende Dissertation schlägt daher eine neue Lesart vor, in dem sie Schelling als Antipolitiker deutet. Hierdurch gelingt es, der Ambivalenz und Breite Schellings Politikauffassung Rechnung zu tragen und die bisherige Forschung aus der Perspektive herauszuführen, die den Autor entweder als „unpolitischen Denker“ oder „politisch-reaktionären Denker“ verstanden wissen will. Die Arbeit begreift Antipolitik dabei als ein Unternehmen, welche das „Überinklusive“ und „Unausweichliche“ am Politik-Begriff zurückweist und im Gegenzug den Raum des Privatbürgerlichen, ja der Gesellschaft verteidigt. Die Praktikabilität des Begriffs wird in der Arbeit sowohl in Bezug auf Schelling als auch in Bezug auf spätere Fallbeispiele wie Heinrich von Treitschke, Constantin Franz oder Friedrich Nietzsche demonstriert. Außerdem plädiert die Untersuchung dafür, Antipolitik auch als ein aktuelles Phänomen zu begreifen, das sich in Gesellschaft immer dann formiert, wenn die Privatsphäre, der nichtpolitische Bereich, durch „staatliche Übergriffe“ oder „politisches Fehlversagen“ tangiert wird. / Was Schelling a political thinker? And if he was, what kind of political idea did Schelling prefer? These questions have been differently discussed in literature during the last decades. The following thesis argues for a new interpretation of Schelling as an antipolitician. The term antipolitics copes with Schelling’s ambivalent political thinking and avoids the recent perspective in research classifying him as a nonpolitical philosopher or reactionist. Antipolitics is described as an ambition that rejects the „unavoidable“ and „Überinklusive“ of politics in order to strengthen the area of privacy and society. The paper demonstrates the practicability of the term using the example of Schelling and also later authors like Heinrich von Treitschke, Constantin Franz or Friedrich Nietzsche. Moreover, the thesis argues that antipolitics can also be seen as a modern phenomenon, which usually takes place when privacy or the non-political space is restricted by political power.

In der vorliegenden Arbeit wird aufgrund der kommentierten Quellen die Tatsache erhellt, dass der Kantsche Anspruch auf Legitimität des Erkenntnisverfahrens, wie er in seiner Transzendentalphilosophie zum Ausdruck gebracht wurde, von drei Momenten des Gedankenprozesses in der Philosophie der Deutschen Aufklärung vorangekündigt wird: a) der Verschiebung der Problematik der deutschen Philosophie vom „Harmonie“-Gedanken der so genannten Leibniz-Wolff-Schule und ihrer Gegner hin zur Fragestellung nach der „Realisierung der Begriffe“ bei Tetens, in der sich der Mensch als sinnstiftendes Wesen dartut, b) dem bereits bei Thomasius in Sprachparallelen zu Kant auftretenden „empiriorationalistischen“ Moment, das die gesamte Periode des Kampfes um die Wolffsche Lehre begleitet und bei Lambert eine neue Form (a priori durch Erfahrung) bekommt, c) dem Verständnis der Denkbarkeit bzw. Begreifbarkeit als Mitteilbarkeit, das schon in der Frühaufklärung (von Thomasius implizit, von Tschirnhaus explizit) anzutreffen ist und von den Zeitgenossen Kants rehabilitiert und von Tetens als Frage nach der Intersubjektivität (das „Objectivische“ als das „unveränderlich Subjectivische“) betont wird. Mit den Werken von Lambert und Tetens, in denen Gott fast keine Rolle mehr spielt, emanzipiert sich das philosophische Denken endgültig von der religiösen Furcht und dem „metaphysischen Schauder“, die während der Barockzeit durch den Triumph der wissenschaftlichen Revolution hervorgebracht worden waren. In der Philosophie der beiden Zeitgenossen Kants versteht sich der Mensch nicht mehr als „intellectus ectypus“, sondern zum ersten Mal als potentieller Gesetzgeber der Natur. Folglich macht diese Tatsache klar, dass Kant auf bereits gestellte Fragen zu antworten hatte. / The current dissertation, which is based on documented sources, elucidates the fact that the Kantian claim of the legitimacy of the cognitive process, as this claim is expressed in the Kantian “Transcendental Philosophy”, had its precursor in three major elements of the philosophical evolution in the German Enlightenment: a)The shifting of the philosophical problematic in the German Enlightenmentfrom the “harmony”-thinking of the Wolffians and their detractors, to Tetens’ posit of the “realization” of concepts, according to which a human being is proven as a meaning-establishing entity; b) The “empiriorationalistic” element in Thomasius, which finds parallels in Kantian formulations, remains active during the whole controversy surrounding the Wolffian teaching, and then acquires a new form in Lambert (a priori through experience); c) The understanding of “conceivability” as “communicability”, which is already present in the early German Enlightenment, implicitly in Thomasius and explicitly in Tschirnhaus, does not come under discussion in the era of Wolff. However, this element comes under the spotlight by Kant’s contemporaries, especially highlighted in Tetens’ question of intersubjectivity (the objective as the “unchangeably subjective”). The representatives of German Enlightenment Philosophy after 1760 freed from the metaphysical shudder caused by the “scientific revolution”, are the very first to comprehend the human intellect, not as “intellectus ectypus”, but as the legislator of nature. In this way, German philosophical thought is to abandon once and for all the baroque world-view. The systems of Lambert and Tetens show clearly that Kant elaborated on questions that they had already posed in an elementary form.

Die Krise der Philosophie, die Nietzsche diagnostiziert hat, ist eine Krise der Abstraktheit der Philosophie, einer Philosophie, die nicht mehr als existenziale Luft des Lebens und als existenziale Atmung des Menschen funktioniert. Für Nietzsche ist die Konkretheit als Begriff im Verhältnis mit der wirklichen Lebenswelt des Menschen nicht bloß die Diagnose der Krise des Lebens, sondern eine Philosophie der Heilung, die der Handlung eines Arztes entspricht. In Nietzsches Philosophie als Gesundheitsphilosophie wird die Krankheit als eine Chance bestimmt, wieder gesund werden zu können. Das heißt, die Krankheit ist ein wichtiger Grund für die Hoffnung auf Gesundheit und die Gesundheit ist eine wichtige Antwort auf den Sinn der Krankheit. / The Crisis of Philosophy that Nietzsche has diagnosed, is a Crisis of the Abstractness of Philosophy, a Philosophy that no longer functions as the existential air of Life and existential Breath of Humans. For Nietzsche the Concreteness as understood as a Conceptual unit is in Proportion with the real Life and World of Humans not only the diagnosis of the Crisis of Life, but a Philosophy of Healing, which corresponds to the Cure of a Doctor. In Nietzsche''s Philosophy as a Philosophy of Health the disease is determined as a chance to be Healthy once more. Disease is an important reason for the Hope of Health and Health is an important Response to the sense of the disease.

Made available in DSpace on 2017-07-24T19:37:57Z (GMT). No. of bitstreams: 1 JULIANE MARIA BER.pdf: 4116262 bytes, checksum: 58a85b36bbcbe8e5b731b5c3d9014a71 (MD5) Previous issue date: 2007-12-14 / The aim of the present work was to carry out an ethnopharmacological survey of the vegetal species used by the inhabitants of the municipality of Céu Azul (located in the extreme west of the State of Paraná, Brazil). A specific questionnaire was used to get the referring data to the uses and ways of preparation of the species used as medicinal. During the interviews, the plant material (exsiccate) was collected in duplicate with the aid of the informers for posterior identification and deposit in the Museu Botânico Municipal de Curitiba. The uses of 47 species pertaining to 12 botanical families were surveyed in this field research. One of the main objectives of the present work was to evaluate the possible use of forest medicinal species in Céu Azul, especially because an extensive area of the municipality belongs to the National Park of the Iguaçu. However, th 47 plants cited by the population can be divided in a group with 42 exotic species and another one with only 6 Brazilian plants, and none of which is being removed from the reserve. The data base of The International Plant Names Index was used to prevent inappropriate botanical names and to verify the current use of synonyms. A survey of the scientific information on the chemical composition and bioactivity was carried out for each cited species. The main source of scientific information for this work was the data base of the Institute of Scientific Information and the Chemical Abstracts on-line. In general, the Céu Azul population makes use of medicinal plants sufficiently known in the scientific sense, but there is also the use of little studied species. For four of the cited species (Alternanthera bettzickiana, Alternanthera dentata, Plectranthus neochilus, Tradescantia pallida), we could not find any scientific reference on its bioactivity. The results of this survey have been concomitantly interpreted as indicative for the election of one of these species, sufficiently known for the Céu Azul population, for deepening of study in the chemistry area. The chemical composition of the essential oil of Plectranthus neochilus was determined using gas chromatography techniques coupled to mass spectrometry. The main components were the monoterpenes α-pinene (9.7), thujene (9.0), terpin-4-ol (4.8) and sabinene (4.7); the sesquiterpenes caryophyllene (19.9) and caryophyllene oxide (15.5); and the diterpene methyl communate (4.4). The presence of pinene and caryophyllene as principal components of the essential oil could be related to the traditional use of Plectranthus against stomach ache. Keywords: medicinal plants, Céu Azul, ethnopharmacology, Plectranthus neochilus, essential oil, GC-MS. / O presente trabalho teve por objetivo realizar um levantamento etnofarmacológico de espécies vegetais utilizadas pelos moradores do município de Céu Azul (localizado no extremo oeste do Paraná). Utilizou-se um questionário específico para obter os dados referentes aos usos e modos de preparo das espécies utilizadas como medicinais. Durante as entrevistas, o material vegetal (exsicata) foi coletado em duplicata com o auxílio dos informantes para posterior identificação e depósito no Museu Botânico Municipal de Curitiba. Na pesquisa de campo foi constatada a utilização de 47 espécies pertencentes a 12 famílias botânicas. Um dos principais propósitos do presente levantamento foi avaliar o possível uso de espécies medicinais florestais no município de Céu Azul, especialmente porque uma extensa área do município pertence ao Parque Nacional do Iguaçu. No entanto, as 47 plantas citadas pela população ceuazulense podem ser divididas em um grupo com 42 espécies exóticas e outro com apenas 6 plantas brasileiras, nenhuma das quais é retirada da reserva. Utilizou-se o banco de dados do The International Plant Names Index para evitar incorreções nos binômios botânicos e verificar o uso atual de sinônimos. Para cada espécie citada, foi realizado um levantamento das informações científicas sobre a composição química e a bioatividade. As principais fontes de informações científicas foram o banco de dados do Institute for Scientific Information e o Chemical Abstracts on-line. Em geral, a população de Céu Azul faz uso de plantas medicinais bastante conhecidas no meio científico, mas há também a utilização de espécies pouco estudadas. Para quatro das espécies utilizadas (Alternanthera bettzickiana, Alternanthera dentata, Plectranthus neochilus, Tradescantia pallida), não foram encontradas referências científicas sobre suas bioatividades. Desta forma, os resultados deste levantamento foram concomitantemente interpretados como indicativos para a seleção de uma destas espécies, bastante conhecida e utilizada pela população de Céu Azul, para aprofundamento de estudo, Plectranthus neochilus. Determinou-se a composição química do óleo essencial das folhas desta espécie vegetal por técnicas de cromatografia gasosa acoplada à espectrometria de massas. Os principais componentes encontrados foram os monoterpenos pineno (9,7), tujeno (9,0), terpinen-4-ol (4,8) e sabineno (4,7); os sesquiterpenos cariofileno (19,9) e óxido de cariofileno (15,5); e o diterpeno comunato de metila (4,4). A ocorrência de pineno e cariofileno como principais componentes do óleo essencial pode estar relacionada ao uso tradicional desta espécie vegetal contra dores estomacais.

Corporate Governance (CG) nowadays is on the agenda of most developed and developing countries, including Jordan, and is receiving considerable attention in the business world as well as in the area of academic research, which is an indication of its importance for business development and society as a whole. The knowledge base about CG in developing countries appears to be limited, but it is growing in size and importance. This study therefore aims to investigate current CG practices and barriers to the development of good CG practices in firms. In order to accomplish the research objectives, a mixed research methodology was adopted. The findings of the study contribute to knowledge by providing empirical data to test and extend the theory of CG. The results suggest that most big and old firms are applying best practice of good CG. Regarding factors inhibiting the practice of effective CG, the results indicate that weakness of the legal environment for firms and lack of knowledge of BODs about CG principles are the most important factors. The empirical results find that constitution, compliance and conscience will affect firm’s performance positively. Separation between the position of CEO and Chairman, the existence of independent NEDs, the use of board subcommittees and a strong disclosure regime also help firms to improve performance. On the basis of the empirical results, the study recommends that the government needs to reform the relevant legislation. These suggestions may strengthen the internal governance of firms, thereby increasing performance and maximise shareholders’ wealth.

The central theme of this thesis is the design of optimal balanced black-box stopping criteria in iterative solvers of symmetric positive-definite, symmetric indefinite, and nonsymmetric linear systems arising from finite element approximation of stochastic (parametric) partial differential equations. For a given stochastic and spatial approximation, it is known that iteratively solving the corresponding linear(ized) system(s) of equations to too tight algebraic error tolerance results in a wastage of computational resources without decreasing the usually unknown approximation error. In order to stop optimally-by avoiding unnecessary computations and premature stopping-algebraic error and a posteriori approximation error estimate must be balanced at the optimal stopping iteration. Efficient and reliable a posteriori error estimators do exist for close estimation of the approximation error in a finite element setting. But the algebraic error is generally unknown since the exact algebraic solution is not usually available. Obtaining tractable upper and lower bounds on the algebraic error in terms of a readily computable and monotonically decreasing quantity (if any) of the chosen iterative solver is the distinctive feature of the designed optimal balanced stopping strategy. Moreover, this work states the exact constants, that is, there are no user-defined parameters in the optimal balanced stopping tests. Hence, an iterative solver incorporating the optimal balanced stopping methodology that is presented here will be a black-box iterative solver. Typically, employing such a stopping methodology would lead to huge computational savings and in any case would definitely rule out premature stopping. The constants in the devised optimal balanced black-box stopping tests in MINRES solver for solving symmetric positive-definite and symmetric indefinite linear systems can be estimated cheaply on-the- fly. The contribution of this thesis goes one step further for the nonsymmetric case in the sense that it not only provides an optimal balanced black-box stopping test in a memory-expensive Krylov solver like GMRES but it also presents an optimal balanced black-box stopping test in memory-inexpensive Krylov solvers such as BICGSTAB(L), TFQMR etc. Currently, little convergence theory exists for the memory-inexpensive Krylov solvers and hence devising stopping criteria for them is an active field of research. Also, an optimal balanced black-box stopping criterion is proposed for nonlinear (Picard or Newton) iterative method that is used for solving the finite dimensional Navier-Stokes equations. The optimal balanced black-box stopping methodology presented in this thesis can be generalized for any iterative solver of a linear(ized) system arising from numerical approximation of a partial differential equation. The only prerequisites for this purpose are the existence of a cheap and tight a posteriori error estimator for the approximation error along with cheap and tractable bounds on the algebraic error.

Soil organic matter (SOM) plays an important role in the global carbon cycle. Therefore, it is important to understand the stability of SOM, which is related to several processes. Its intrinsic properties may be related to its stability, for example black carbon is considered to be relatively resistant to degradation. In most soils, the dark horizons coincide with the superficial layers or horizons due to the greater accumulation of organic matter, but in the southern states of Brazil, the presence of soils with dark subsurface horizons is frequently observed. The dark subsurface horizon of these soils are similar to a sombric horizon. Aspects about its origin, formation and preservation have not yet been fully elucidated. The objective of this work is to understand the formation of \'sombric\' horizons in soils of the region from Tijucas do Sul (Paraná, Brazil). Five soil profiles were described and collected, from which three originate from a toposequence and contained a \'sombric\' horizon (P1-P3), a reference soil that is representative of the area (P5) and an intermediate soil (P4) that showed morphology between the reference soil and the soils with a \'sombric\' horizon. To this end SOM is studied for its molecular composition by the pyrolysis technique coupled to gas chromatography and mass spectrometry (pyrolysis-GC-MS). In addition, 13C isotopic composition (δ13C) and phytolytic composition were studied in order to understand paleoclimatic conditions. These results will be related to past environmental conditions using 14C dating techniques, and supported by classical soil analysis. The samples of the horizons were submitted to the SOM chemical fractionation, generating two fractions: extractable fraction with NaOH (EXT) and residue (RES). The morphology of the profiles showed an intense biological activity in A horizons and a wide distribution of microfragments of charcoals. The lateral continuity of \'sombric\' horizons in toposequence soils was also observed, which differentiated them (P1-P3) from buried A horizons. The distribution of SOM in the fractions studied was the same for the five profiles studied: EXT> RES. Products related to wildfires such as polyaromatics (PAHs; BC) were found in all profiles, but in greater relative abundance in the \'sombric\' horizons, indicating a higher incidence of fire during the formation of these horizons and these compounds can be related to the maintenance of dark color of the \'sombric\' horizons. In relation to the paleoclimatic conditions it was observed that the dark subsurface horizons were developed during the Mid-Holocene under vegetation composed mainly by C4 grasses with shrubs, evidencing a drier climate corresponding to a higher fire incidence. / A matéria orgânica do solo (MOS) desempenha um papel importante no ciclo global do carbono. Portanto, é importante entender a estabilidade da MOS, que está relacionada a vários processos. As suas propriedades intrínsecas podem estar relacionadas com a sua estabilidade, por exemplo, o \"black carbon\" é considerado relativamente resistente à degradação. Na maioria dos solos, os horizontes escuros coincidem com as camadas ou horizontes superficiais devido ao maior acúmulo de matéria orgânica, mas nos estados do sul do Brasil, a presença de solos com horizontes subsuperficiais escurecidos é frequentemente observada. O horizonte subsuperficial escurecido destes solos assemelha-se a um horizonte sômbrico. Aspectos sobre sua origem, formação e preservação ainda não foram totalmente elucidados. O objetivo deste trabalho é compreender a formação de horizontes \'sômbricos\' em solos da região de Tijucas do Sul (Paraná, Brasil). Foram descritos e coletados cinco perfis de solo, dos quais três estão localizados em uma topossequência e continham um horizonte similar ao sômbrico (P1-P3), um solo de referência representativo da área (P5) e um solo intermediário (P4) que apresentou uma morfologia entre o solo de referência e os solos com horizonte \'sômbrico\'. Para este fim, a MOS foi estudada pela sua composição molecular através da técnica de pirólise acoplada à cromatografia gasosa e espectrometria de massa (pirólise-GC-MS). Além disso, estudou-se a composição isotópica 13C (δ 13C) e a composição fitolítica, a fim de compreender as condições paleoclimáticas que foram relacionados com as condições ambientais passadas usando técnicas de datação com 14C, e suportados pelas análises clássicas de solo. As amostras dos horizontes foram submetidas ao fracionamento químico MOS, gerando duas frações: fração extraível com NaOH (EXT) e resíduo (RES). A morfologia dos perfis mostrou uma intensa atividade biológica nos horizontes A e uma ampla distribuição de microfragmentos de carvão. Observouse também a continuidade lateral de horizontes \'sômbricos\' em solos da topossequência (P1-P3), diferenciando-os dos horizontes A enterrados. A distribuição da MOS nas frações estudadas pela pirólise foi a mesma para os cinco perfis: EXT> RES. Os produtos relacionados a incêndios florestais como os poliaromáticos (PAHs, BC) foram encontrados em todos os perfis, mas em maior abundância relativa nos horizontes sômbricos, indicando uma maior incidência de incêndio durante a formação destes horizontes. Os PAHs podem estar relacionados com a manutenção da cor escura dos horizontes \'sômbricos\'. Em relação às condições paleoclimáticas observou-se que os horizontes subsuperficiais escurecidos foram desenvolvidos durante o Holoceno Médio sob vegetação composta principalmente por gramíneas C4 com arbustos, evidenciando um clima mais seco correspondente a maior incidência de incêndio.