Robust asset allocation under model ambiguity

A decision maker, when facing a decision problem, often considers several models to represent the outcomes of the decision variable considered. More often than not, the decision maker does not trust fully any of those models and hence displays ambiguity or model uncertainty aversion. In this PhD thesis, focus is given to the specific case of asset allocation problem under ambiguity faced by financial investors. The aim is not to find an optimal solution for the investor, but rather come up with a general methodology that can be applied in particular to the asset allocation problem and allows the investor to find a tractable, easy to compute solution for this problem, taking into account ambiguity. This PhD thesis is structured as follows: First, some classical and widely used models to represent asset returns are presented. It is shown that the performance of the asset portfolios built using those single models is very volatile. No model performs better than the others consistently over the period considered, which gives empirical evidence that: no model can be fully trusted over the long run and that several models are needed to achieve the best asset allocation possible. Therefore, the classical portfolio theory must be adapted to take into account ambiguity or model uncertainty. Many authors have in an early stage attempted to include ambiguity aversion in the asset allocation problem. A review of the literature is studied to outline the main models proposed. However, those models often lack flexibility and tractability. The search for an optimal solution to the asset allocation problem when considering ambiguity aversion is often difficult to apply in practice on large dimension problems, as the ones faced by modern financial investors. This constitutes the motivation to put forward a novel methodology easily applicable, robust, flexible and tractable. The Ambiguity Robust Adjustment (ARA) methodology is theoretically presented and then tested on a large empirical data set. Several forms of the ARA are considered and tested. Empirical evidence demonstrates that the ARA methodology improves portfolio performances greatly. Through the specific illustration of the asset allocation problem in finance, this PhD thesis proposes a new general methodology that will hopefully help decision makers to solve numerous different problems under ambiguity

Mechanism-based strategies for the management of autoimmunity and immune dysregulation in primary immunodeficiencies

A broad spectrum of autoimmunity is now well described in patients with primary immunodeficiencies (PIDs). Management of autoimmune disease in the background of PID is particularly challenging given the seemingly discordant goals of immune support and immune suppression. Our growing ability to define the molecular underpinnings of immune dysregulation has facilitated novel targeted therapeutics. This review focuses on mechanism-based treatment strategies for the most common autoimmune and inflammatory complications of PID including autoimmune cytopenias, rheumatologic disease, and gastrointestinal disease. We aim to provide guidance regarding the rational use of these agents in the complex PID patient population

Measuring de facto versus de iure political institutions in the long-run: a multivariate statistical approach

In this paper we use the components of the PolityIV project’s polity2 and Vanhanen’s Index of Democracy indicators to analyse the relationship between de iure and de facto political institutions from 1820 until 2000 with a canonical correlation method, and a correction for the sample selection bias, caused by the change in the number of available countries. We find considerably fluctuation in the relationship between the two measures and that much of the observed correlation is due to the sample selection bias. The relationship becomes strong and positive only in the second half of the 20th century

Synthetic studies on the C(1)-C(9) unit of TA toxin using nucleophilic opening of chiral epoxides

TA and TB toxins are host-specific phytotoxins produced by the fungus Altemaria altemata f. sp. Iycopersici, the causative agent of stem canker disease in tomato. The two toxins are similar in structure: TB lacks the C(5) hydroxy group present in TA toxin. Both compounds are isolated as an equilibrium mixture of the two esters formed by either the C(13) or C(14) hydroxy groups of the (2S,4R,5R,11R,13S,14R,15R)-1-amino-11,15¬dimethylhepta-decane-2,4,5, 13, 14-pentol backbone with the Re prochiral carboxy group of tricarballylic acid. The synthesis for these toxins is necessary in order to study their structure-activity relationships. The aim of the synthetic study outlined in this dissertation is the development and implementation of methodology for the synthesis of the C(1)-C(9) unit of the C17 aminopentol backbone of TA toxin with the appropriate stereochemistry. Retrosynthetic analysis of the C17 aminopentol backbone of TA toxin identifies (2R,4S,-5R,6R)-2,6-dimethyloctane-1.4,5-triol, synthon B, and (2S,4R,5R)-1-amino¬nonane-2,4,5,9-tetrol, synthon A as key intermediates for the proposed synthesis. Further analysis of synthon A identifies the C9 synthon (2S,4R,5R)-nonane-1,2,4,5,9-pentol, as the target molecule which can be derived from the C7 synthon (2S,3R)-1,2-epoxyheptane-3,7¬diol. The work presented in this dissertation shows that the protected intermediate corresponding to the abovementioned C7 synthon, can be prepared from 1,5-pentanediol by a number of functional group trans-formations using appropriate protecting group strategy (O-TBS, O-TBDPS and O-benzyl groups) and introduction of the two stereogenic centres by using Sharpless epoxidation/kinetic resolution methodology. Nucleophilic opening of the terminal epoxide using cyanide was successful but using chiral sulfoxide methodology for the introduction of the third stereogenic centre and the concomitant one¬-carbon chain extension, failed: in the case of both an acetonide and a dibenzyl protected C8 intermediate a rearrangement occurred. Alternative methods for nucleophilic opening of the terminal epoxide ring and concomitant or subsequent chain extension were investigated and as a result a different synthetic route is proposed.Dissertation (MSc (Chemistry))--University of Pretoria, 2006.Chemistryunrestricte

Interaction of Liposomal Drug Delivery Systems with Cells and Tissues: Microscopic Studies

Liposomes , as drug carriers, can be administered into the body by several routes e.g. intravenously, intraperitoneally, intramuscularly, intratracheally and topically among others. Radiolabelled markers are suitable to monitor the distribution and elimination of liposomes, but the tissue deposition of intact liposomes, the mode and sites of drug release from the liposomes and liposome-cell interactions cannot be investigated morphologically. Microscopic techniques could provide information regarding the intact state of liposomes and possibly the dynamics of liposomes in tissues provided that they can be identified with certainty in vivo. This is a formidable problem and in spite of several attempts, there is still a lot of work and new ideas needed to overcome this problem. This paper gives a detailed review of liposome markers used in light and electron microscopy. The use of markers or the technique involved in the identification of liposomes in cells or t issues is discussed. The feasibility of using colloidal iron, a new electron dense marker, as a marker for intravenously injected liposomes was investigated in mice. Intact multilamellar vesicles containing colloidal iron were identified in the liver, spleen and lung of mice injected with liposomes. The liver and the spleen are organs for the storage of iron containing proteins (ferritin, hemosiderin), therefore studying the disposition of colloidal iron from the liposomes was not possible. However, in organs not containing iron, e.g. lung, the presence of colloidal iron can easily be recognized. The colloidal iron marker may be suitable to label liposomes targeted to the brain , heart or certain tumors

Carbon nanotubes for stabilization of nanostructured lipid particles

Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2–5 μm size. Single-walled (pristine) as well as –OH and –COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs

Леся Українка та Олена Пчілка в контексті західно- української мемуаристики першої половини ХХ ст.

Розглядаються жанрові особливості та поетика деяких мемуарів західних теренів України (зокрема Галичини та Буковини), у яких постають образи Лесі Українки та Олени Пчілки.Рассматриваются жанровые особенности и поэтика некоторых мемуаров западного региона Украины (в особенности Галиции и Буковины), в которых постают образы Леси Украинки и Олены Пчилки.The article tells about genre peculiarities and poetics of memoirs of the Western Ukraine (in particular, Halychyna and Bukovyna), in which characters of Lesya Ukrainka and Olena Pchilka appear

Human capital in Qing China: economic determinism or a history of failed opportunities?

The traditional education system in Qing China has been widely debated over the past decades. Some have argued it was efficient and furthered economic growth, while others have stressed its inefficient nature, which led to the introduction of the modern education system in the closing decades of the 19th century, followed by its total collapse in 1905. In this paper we make a first try to quantify above debate. Starting from the observation that below the well-known civil examination system there existed a whole system of popular and vocational education, we find that years of education in the population were still lower than in many European countries. More interestingly, whereas in European countries years of education increased strongly in the 19th century, our estimates of average years of education and the ABCC indices show that the level of education remained stable well into the 1920s when it accelerated. However, the main rise only occurred during the late 20th century. This finding leads to an interesting question since per capita income only started to grow significantly since the 1950s. This means that the rise of education since the mid-1920s was not as such driven by per capita income. Apparently this was the same for both the traditional and modern education since the latter had already started to transform Chinese education from the 1890s onwards. Hence, we have to look at the question why persons decided to follow education, i.e. was it individually profitable to follow education (positive private returns)? However, testing for this latter hypothesis shows that, after correction for foregone earnings, life expectancy, and probability of passing the exams, only the below shengyuan level students actually had positive returns. For an ordinary person it was therefore uneconomical to join in the civil examination system. Apparently this did not change, not even after the introduction of the modern education system, until the 1950s

Human capital in Qing China: economic determinism or a history of failed opportunities?

The traditional education system in Qing China has been widely debated over the past decades. Some have argued it was efficient and furthered economic growth, while others have stressed its inefficient nature, which led to the introduction of the modern education system in the closing decades of the 19th century, followed by its total collapse in 1905. In this paper we make a first try to quantify above debate. Starting from the observation that below the well-known civil examination system there existed a whole system of popular and vocational education, we find that years of education in the population were still lower than in many European countries. More interestingly, whereas in European countries years of education increased strongly in the 19th century, our estimates of average years of education and the ABCC indices show that the level of education remained stable well into the 1920s when it accelerated. However, the main rise only occurred during the late 20th century. This finding leads to an interesting question since per capita income only started to grow significantly since the 1950s. This means that the rise of education since the mid-1920s was not as such driven by per capita income. Apparently this was the same for both the traditional and modern education since the latter had already started to transform Chinese education from the 1890s onwards. Hence, we have to look at the question why persons decided to follow education, i.e. was it individually profitable to follow education (positive private returns)? However, testing for this latter hypothesis shows that, after correction for foregone earnings, life expectancy, and probability of passing the exams, only the below shengyuan level students actually had positive returns. For an ordinary person it was therefore uneconomical to join in the civil examination system. Apparently this did not change, not even after the introduction of the modern education system, until the 1950s

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Contains a report on a research project