Most farmers in South Africa use standard insurance to protect their crops against natural disasters such as hail or strong winds. However, no South African insurance contracts exist to compensate for too much or too little rain (although floods are covered), or which will pay out if temperatures were too high or too low for a certain period of time for the relevant crop. Weather derivatives - which farmers may employ to ensure crops against adverse temperatures - do exist, but these are mostly available in foreign markets in the form of Heating Degree Days contracts and Cooling Degree Day contracts and are used chiefly by energy companies. Some South African over-the-counter weather derivatives are available, but trading in these is rare and seldom used. The goal of this dissertation is to establish a pricing equation for weather derivatives specifically for use in the South African market. This equation will be derived using a similar methodology to that employed for credit default swaps. The premium derived will be designed to compensate grape farmers from losses arising from two different climatic outcomes - in this case temperature and precipitation. These derivatives will be region and crop specific and the formulation will be sufficiently flexible as to allow for further climatic possibilities (which may be added at a later stage). These weather derivative premiums will then be compared to standard crop insurance to establish economic viability of the products and recommendations will be made regarding their usage. The possibility of the simultaneous use of these derivatives and standard crop insurance for optimal crop coverage will also be explored and discussed. / Thesis (M.Com. (Risk management))--North-West University, Potchefstroom Campus, 2011.

Orientador: Victor Ciro Solano Reynoso / Banca: Keizo Yukimitu / Banca: Raul Fernando Cuevas Rojas / Resumo: O presente trabalho visou a produção e o estudo das propriedades físicas de amostras de resina epóxi transparente dopadas com diferentes concentrações de nanocristais de sulfeto de cádmio (CdS). As técnicas de difração de raios-X, espectroscopia no infravermelho, espectroscopia Raman e calorimetria diferencial de varredura (DSC) foram utilizadas para estudar as propriedades estruturais. Espectroscopias de refletância e de transmitância foram utilizadas para obter a dispersão do índice de refração e do coeficiente de extinção na região do UV-Vis para amostras dopadas com diferentes concentrações de CdS. A técnica do ângulo de Brewster foi também utilizada para determinar o índice de refração das diferentes amostras. Os valores dos índices de refração obtidos através das medidas de refletância e de transmitância na região do UV-Vis e da técnica do ângulo de Brewster foram comparados e os resultados mostraram que a técnica do ângulo de Brewster além de apresentar valores que conferem com a literatura apresentou valores com alta precisão. Foram realizadas medidas de birrefringência opticamente. Foram obtidos resultados da birrefringência fotoinduzida por um fóton para diferentes concentrações de CdS por amostra e para diferentes intensidades da luz de excitação. Os resultados foram quantificados utilizando alguns dos principais modelos teóricos, onde foi observado que a resina epóxi pura apresenta birrefringência fotoinduzida e a adição do CdS contribui para o aumento da birrefringência. / Abstract: The present work sought production and study of the physical properties of samples of transparent epoxy resin doped with different concentrations of structures of cadmium sulfide (CdS) nanocrystals. X-ray diffraction, infrared spectroscopy, Raman spectroscopy e differential scanning calorimetry techniques were used to study their structural properties. Reflectance and transmittance spectroscopy were used to obtain of the refraction index and of the extinction coefficients dispersion in the UVVis region for doped samples with different concentrations of CdS. The Brewster angle technique also was used to determine the refraction index of the different samples. The refraction index values obtained using the reflectance and transmittance measurement in the UV-Vis region and Brewster angle technique were compared and the results showed that the Brewster angle technique besides presents values that check with the literature, presented values with high precision. Measurements of optically induced birefringence were accomplished. Were obtained results of the photo induced birefringence by a photon for different concentrations of CdS for sample and for different intensities of the excitement light. The results were quantified using some of the principal theoretical models, where was observed that the pure epoxy resin presents photo induced birefringence and the addition of the CdS contributes to the increase of the birefringence. / Mestre

This thesis is focused on the credit derivatives market. The aim is to identify and quantify the causal dependence of the development of credit derivatives market in relation to the dynamics of macroeconomic indicators and on this basis the possible prediction. At first, it shows with the help of literature review of their present and history and gives a better look to the different types of credit derivatives. The following section deals with the use of these underlying instruments in practice, their possible trading, insurance, or speculation, whether on the OTC markets or organized exchanges. The following describes the events in the capital and commercial markets during the financial crisis that is between the years 2005-2010, from which are taken the data for the empirical part. The empirical part is based on correlation analysis (multiple regression model) of a few selected and described macroeconomic indicators enriched with Granger causality test. In the conclusion may be find the discussion of the results and possible recommendations for potential investors.

O clássico Equilíbrio Econômico nunca foi realidade, especialmente após as primeiras crises dos mercados financeiros. Hoje se sabe que as economias estão longe da situação de equilíbrio, sendo vistas mais como um processo em construção do que um estado estático propriamente dito. Se assemelham a um sistema estocástico, e não determinístico como um dia se pensou. O Brasil é um país jovem, e seus sistemas econômico e político ainda estão em formação. Tendo em vista todas as mudanças e crises que o país tem sofrido em sua história recente, este estudo busca uma forma alternativa para que tais eventos possam ser detectados e, principalmente, de certa forma antecipados, para que as providências cabíveis possam ser tomadas a tempo de se evitar grandes perdas financeiras. Para tal, as medidas de Complexidade de SDL e LMC são aplicadas às séries do câmbio dolar-real, Ibovespa e CDS Brasil e avaliadas durante eventos de crises. Detectados os principais eventos de cada série, \"volta-se no tempo\", ao início da crise, e avalia-se, dada a informação disponível naquele momento, a possibilidade de se detectar a crise em seus primeiros estágios. Ao fim, conclui-se que as Medidas de Complexidade LMC e SDL são robustas na detecção de aumentos de volatilidade nos dados de séries financeiras. Assim sendo, apresentam grande potencial como indicadores precoces de crises financeiras. Para tal, não são necessários cálculos extensivos, nem grandes históricos de dados; e também não são necessárias hipóteses sobre a distribuição de probabilidades destes dados. Acredita-se que este seja o primeiro passo em direção à construção de um monitor de crises em tempo real. / The classical Economic Equilibrium has never been a reality, especially after the first financial markets crisis events. It is known nowadays that economies are far from their Equilibrium, they are seen more as a process under construction, not a static state; a stochastic instead of deterministic process, as it was thought before. Brazil is a young country, hence its economic and political systems are still maturing. In light of all the changes and crises it has been suffering in the recent history, this research seeks for an alternative mechanism to detect and anticipate these crisis events, in order to avoid massive financial losses. To this end, the LMC and SDL Complexity Measures are applied to the Dollar-Real exchange rates, Ibovespa and Brazilian CDS time series during crisis events. After detecting the main events, the idea is to \"turn back in time\", to the events\' inception, and analyse if, given the limited amount of information on that time, the crises could be detected on their early stages. Finally, this research concludes that both LMC and SDL Complexity Measures are robust in detecting volatility increases on the financial series, revealing good potential as crises early warning. However, no extensive calculus, large samples, or strong assumptions about the data probability distributions are needed to this aim. Therefore, these results represent the very first step towards a crises real time monitor.

Deposition of noble metal and semiconductor nanocrystalline thin films has received much attention. CdS and CdSe are important semiconductors used in optical devices. A wet chemical route which uses the interface of two immiscible liquids to control the growth and deposition of nanocrystalline thin films forms the basis of the current study. In this method, a metal precursor dissolved in toluene or decane is held in contact with a water layer containing a reducing or sulphiding agent. The reaction proceeds at the interface of the liquids and results in deposits adhering to the interfacial region. The products of such reactions typically consist of nanocrystals forming a thin film. Stable sols of Au, Ag were found to metathesize on contact with alkylamine in oil to form monolayer films that spread across large areas at the water/oil interface. The nature and properties of interfacial thin films depend on the alkylamine. Nanocrystalline thin films consisting of CdS adhering to the interface starting with a polydispersed aqueous sol of crystallites and alkylamine were obtained. The optical band gaps of the films formed are dependent on the alkylamine chain length, with the shortest chain yielding the largest gap. A systematic increase in particle diameters following adsorption is responsible for changes in the electronic structure of films. The formation of nanocrystalline films of CdS adhering at the interface using a toluene solution of cadmium diethyldithiocarbamate and aqueous Na2S solution, in the presence of tetraoctylammonium bromide (TOAB) in the aqueous phase, was investigated under various reaction parameters, while CdSe was obtained using Na2SeSO3 solution and the influences of deposition temperature and solution concentration were studied. A ternary water/decane/2-butoxyethanol /salt system was used to grow deposits of CdSe and CdS. Nanostructured thin films were obtained at the upper interface of the ternary system, between the emulsive middle layer and oil rich top phase. The influence of deposition conditions such as precursor concentrations and temperature, as well as the nature of the medium on the properties of the deposits was studied. Deposits grown using the ternary system were compared with those obtained using water/decane and water/toluene systems. Reaction parameters such as temperature, solution concentration and the size of CdS and CdSe were controlled. A thin film of CdS and CdSe nanocrystals was formed at the interface. The grain size was found to be dependent on reaction temperature and solution concentration, with higher temperatures and solution concentration resulting in larger grains. The nature of thin films obtained at the interface of two immiscible liquids and of a water/decane/2-butoxyethanol/salt ternary system were studied using Scanning and Transmission electron microscopy, X-ray diffraction and UV-visible spectroscopy.

In dieser Arbeit wurde das laserinduzierte Fluoreszenzlicht von mikrometergroßen Partikeln untersucht, die in einer elektrodynamischen Vierpolfalle gespeichert waren. Untersuchungsobjekte dabei waren ligandenstabilisierte Cadmiumsulfid-Cluster, Farbstoffpartikel und Diamanten mit N-V-Zentren. Auf die Herstellung und Charakterisierung der CdS-Proben wird genauer eingegangen. Zum Probentransfer in den Speicher wurde die Verwendung eines kommerziellen Tröpfchengenerators eingeführt und diskutiert.

Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with alternative heterojunction partner such as ZnS. With varying ratio of Zn/ (Zn+Cd) in ZnxCd1-xS a range of bandgap energies can be obtained and thus an optimum band offset can be engineered. For reducing interface dominated recombination better lattice match between absorber and heterojunction partners is desirable. Although CdS has better lattice match with CuIn1-xGaxS2 absorber layer, same is not true for CuIn1-xGaxS2 absorber layers. Utilizing ZnxCd1-xS as heterojunction partner provides a range of lattice constant (between aZnS= ~5.4 Ǻ and aCdS= ~5.7 Ǻ) depending on Zn/(Zn+Cd). Therefore better lattice match can be obtained between heterojunction partner and absorber layer. Better lattice match will lead to lower interface dominated recombination, hence higher open circuit voltages. In the present study chemical bath deposition parameters are near optimized for high efficiency CIGS2 Solar cells. Effect of various chemical bath deposition parameters on device performance was studied and attempts were made to optimize the deposition parameters in order to improve the device performance.In/(In+Ga) ratio in absorber layer is varied to obtain good lattice match and optimum band alignment. Solar cells with conversion efficiencies comparable to conventional CdS/CIGS2 has been obtained with ZnxCd1-xS /CIGS2. High short current as well as higher open circuit voltages were obtained with ZnxCd1-xS as alternative heterojunction partner for CIGS2 solar cells as compared to SLG/Mo/CIGS2/ CdS / i-ZnO/ZnO:Al.

Chemical bath deposition (CBD) is the analog in liquid phase of the well-known chemical vapor deposition technique in the vapor phase. In CBD, deposition of thin films takes place from aqueous solutions at low temperatures by a chemical reaction between dissolved precursors, with the help of a complexing agent. Among all techniques used to grow Group II-VI semiconductors, CBD has the advantage of being a simple, low temperature, and inexpensive large-area deposition technique. So far, its contribution in thin film solar cells industry has been mainly limited to growing n-type CdS and/or ZnS window layers for CdTe-based and CIGS-based solar cells. In this work we first optimize the CBD process of CdS using nitrilotriacetic acid and hydrazine as complexing agents as an alternative to ammonia. We then study the effect of the cadmium precursor on the optical/electrical properties, as well as crystal structure, morphology, and composition of CBD-CdS films. A better understanding of the CBD process of CdS as a whole has been achieved and high quality CBD-CdS films have been obtained. Next, we investigate in-situ doping of CBD-CdS with group III elements, such as B, Al, In, and Ga. The objective is to show that CBD is capable of not only growing CdS but also of doping it to reduce its resistivity and, as a result, facilitate its use in solar cells as well as other optoelectronic device fabrication. A four orders of magnitude drop of film resistivity has been achieved without a significant change in film bandgap, structure, or morphology. Finally, we test the possibility of using CBD to grow transparent conducting oxide (TCO) films, such as Al-doped ZnO films and cadmium stannate films. First, we study CBD of ZnO and later in-situ doping of ZnO using Al. High quality ZnO thin films have been grown using CBD with the help of four different complexing agents. Post heat treatment in argon ambient helped reduce resistivity of CBD-ZnO undoped films to ~ 10-1 Ω-cm. In-situ doping of such films using Al shows promising results. Such films could be an alternative to indium tin oxide (ITO) layers that are commonly used as TCO layers for solar cells. Another approach is to use CBD to grow CdO and SnO2 thin films, with the goal of obtaining Cd2SnO4 by later annealing of these two layers. Cadmium stannate is another TCO candidate that could replace ITO in the near future. We have succeeded in growing CBD-CdO thin films using three different complexing agents. Undoped CBD-CdO films with a resistivity as low as 1.01 x10-2 Ω-cm and a carrier density as high as 2.59 x 1020 cm-3 have been obtained. SnO2 films have been successfully grown using CBD. Fabrication of Cadmium stannate thin films using CBD is investigated. In summary, our objective to expand the use of CBD beyond just growing CdS and ZnS, and to test the possibility of using it for in-situ doping of group II-VI semiconductors as well as TCO layers fabrication proved to be successful. We believe that this may have a significant impact on solar cells as well as other optoelectronic devices fabrication industry, due to the simplicity and the cost-effectiveness of CBD.

No description available.

歐式信用違約交換選擇權通常都以短天期較富流動信，造成這樣情形的原因很可能是因為長天期的信用違約交換選擇權必須承擔標的公司的倒閉風險。美式信用違約交換選擇權讓持有者可以在選擇權到期以前履約，這使得持有者可以只注意信用違約交換溢酬的變動，而不必擔心標的公司的倒閉風險。在這篇論文當中，我們結合最小平方法以及單期信用違約溢酬模型評價美式信用違約交換選擇權，其中單期信用違約溢酬模型是由布瑞格在2004年所發表的模型。本篇論文評價方法的最大優點在於此方法類似於利率理論的市場模型，因此我們可以利用類似的想法評價任何與信用違約交換合約相關的信用衍生性商品。 / The most liquid European CDS options are usually of short maturities. This may result from that options with longer maturity have to bear more default risk of the reference company. American CDS options allow the holders to exercise options before option matures so that they can focus on spread movements without worrying about default risk. In this paper, we price American CDS options with one-period CDS spread model presented by Brigo (2004). The primary advantage of this model is that it is similar to LIBOR market model in interest rate theory. Therefore, path-dependent CDS-related products can be easily priced with familiar ideas.