Thesis (M.Sc. (Med.))--University of the Witwatersrand, Faculty of Health Sciences, 1998. / The issue of Malagasy ancestry has been controversial, and has still not been completely resolved. The historical, linguistic, archaeological and some genetic evidence points to the fact that modern Malagasy are the descendants of immigrants who arrived on the island over the past 2000 years, from South and Southeast Asia, Africa and the Near East. In more recent centuries, mainly in the twentieth century, there have been significant numbers of Indian, Chinese and French immigrants. In addition, archaeological and historical studies of specific regional populations of Malagasy suggest a complex pattern of internal migration within the island, extending back in time to the first European contacts with the island in the sixteenth century. The 22 Malagasy ethnic groups may be classified as "highland" or "lowland" depending on their geographic distribution on the island. Within the ethnic groups, the founding populations have made different genetic contributions: the highland groups are said to have a greater Indonesian contribution to their ancestry, while the lowlanders have a greater African contribution to their ancestry. Genetic studies on the Malagasy have been limited by small sample sizes, deficiencies in sampling procedures and in the limited number of polymorphisms studied. In light of the paucity of written records, the Department of Human Genetics, SAIMR, has undertaken a large study in Madagascar to reconstruct the biological history of its people, using genetic variation. This thesis forms a part of this study. Variation in the a- and p-globin cluster has been extensively studied in many parts of the world, and has been shown to be population specific, with specific variants having distinct geographical distributions. Thus haemoglobin and its related disorders have been the subject of extensive studies for determining the origin(s) of particular populations. In this study, some of the a- and p-globin variation present in the Malagasy was characterised. Seven RFLPs/HVRs in the a-globin gene cluster and seven RFLPs in the p-globin gene cluster were analysed. The common a- and p-globin gene cluster haplotypes differ between African and Asian populations. Frequencies also vary between populations in a specific geographical regions. The aim of this study was to characterise the haplotypes present in the Malagasy, to provide information on the relative genetic contributions of different populations to the peoples of Madagascar. DNA samples from randomly selected, haematologically normal individuals were analysed. Individuals were chosen from six Malagasy ethnic groups: two “highland” populations (Merina and Betsileo), two “lowland" populations (Antasaka and Tsimiheti) and two populations from the south-west of the island (Mahafaly and Vezo). The groups chosen cover a broad range of Madagascar and thus provide some representation of the Malagasy population as a whole. The number of individuals studied in each ethnic group are as follows: Merina: 88; Betsileo: 78; Antasaka: 67; Tsimiheti: 67; Mahafaly: 26; Vezo: 25. The frequencies of the a- and (B-globin RFLP sites and a-globin HVRs in the Malagasy vere calculated. 5' and 3’ p-globin haplotypes were constructed on the basis of homozygosity. A maximum-likelihood algorithm was used to obtain frequencies of 5’ P-globin haplotypes that could not be assigned on the basis of homozygosity. These data were then subject to statistical analysis. The frequencies of the 5’ p-globin haplotypes (consisting of the five sites Hindi 5' to e, Hindi 11 within Gy and Ay, Hindi within \|/P and 3' to it) were the most informative data set for comparing the Malagasy ethnic groups to each other and to other world populations. Unfortunately, the maximum-likelihood estimates of 5‘ p-globin haplotypes could not be used for comparative analyses due to the lack of similar data in other populations. However the strong correlation between the maximum-likelihood frequencies and the observed frequencies illustrated the ability of the algorithm to determine hapiotype frequencies from otherwise uninformative individuals. 5’ p-globin haplotypes were assigned unambiguously for 248 Malagasy chromosomes. Ten haplotypes were found; of these, nine have been reported previously in other world populations and one has not been reported and hns thus been called “rare” in this study. The frequencies of unambiguous 5’ p-globin haplotypes in the Malagasy and the proposed parental populations were initially analysed with x2 tests. For a more accurate comparison between these populations, genetic distances were calculated and used for the construction of phylogenetic trees, principle component analysis was carried out, and a study of heterozygosity versus distance from the centroid was performed. Admixture estimates of two African populations and one Indonesian population to Malagasy ancestry were calculated. Certain general trends were noted in all the analyses. The results are in agreement with the historical data which provides evidence for both African and Asian contributions to Malagasy ancestry. The highlanders were more closely affiliated to the Indonesian/Polynesian populations, while the south-west groups showed the strongest associations with the African populations. The lowlanders were consistently intermediate in position between the highlanders and the south-west groups, with the Antasaka being slightly more closely related to the African populations than the Tsimiheti. The Malagasy were shown to have high heterozygosities, similar to those of African populations, and this high degree of diversity is probably a reflection of the many sources of ancestry of the Malagasy. The south-west groups were the furthest outliers in the model of heterozygosity versus distance from the centroid, suggesting that these groups are the most genetically admixed of all the Malagasy groups that were studied. Estimates of ancestral population admixture confirmed these trends, with the highlanders having the highest proportional contribution by Indonesians (53%), but the lowest total African contribution (47%), while the south-west groups have the highest Bantu contribution (65%). The Indonesian and African contributions to the lowlanders are intermediate between those to highlanders and south-west groups. Overall the Malagasy subjects included in this study showed a 61% African admixture contribution and a 39% Indonesian admixture contribution. It is hoped that the results obtained in this study will contribute to the larger project concerning the origins of the Malagasy, and that they may be used to shed further light on the much debated issue of Malagasy ancestry.

by Kin-wai Lee. / Includes bibliographies / Thesis (M.Phil.)--Chinese University of Hong Kong, 1982

Syftet med den här magisteruppsatsen är att undersöka hur tillkännagivandet av företags-förvärv påverkar aktieavkastningen på ett uppköpande bolaget. Testet är begränsat till före-tag som enbart är listade på Stockholmsbörsen under perioden 1996 till 2005. För att testa onormal avkastning användes marknads modellen. Resultatet visade att tillkännagivandet av företagsförvärv har en signifikant effekt på avkastningen för aktien för det bolag som ska förvärva. Majoriteten av uppköpande bolag upplevde en negativ onormal avkastning under test perioden (100 dagar före tillkännagivandet och 100 dagar efter). / The purpose of this master’s thesis is to examine the effect a corporate takeover an-nouncement has on share prices for acquiring companies. The test will only involve com-panies listed on the Stockholm Stock Exchange during the period 1996 to 2005. To test the effect an announcement has, abnormal return for a period before and after the takeover announcement was calculated. The findings from the testing showed that takeover an-nouncements have a significantly impact on shareholder return. The majority of acquirers in the sample had negative average abnormal returns during the event period (100 days prior to the announcement and 100 day after).

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The purpose of this paper is to investigate the long-term share price effects for Swedish companies that employed repurchases programs during 2000 - 2012. This paper applies a trading strategy where the investor invests in stocks of compa-nies that engage in repurchase of their own equity. We test buy-and-hold abnormal returns versus two different proxies for the control firm, using small sample t-statistics. Abnormal returns for one to five years are insignificant under sta-tistic tests, using the supersector indices. In contrast, they are significant using a proxy for the market index as control firm. Factors hypothesized to contribute to this result are incon-clusive using our method of comparison. As a whole, we suggest that investing in companies that repurchase stock is a solid strategy: It is on par or better than index.

The relative economic efficiency of acquisitions as a means of restructuring financially distressed firms is investigated. Yearly accounting and daily stock price data are extracted for the period between 1979 and 1998 on firms entering financial distress The behaviour and performance of these firms were traced for a five year period following their entry into distress or until their shares were no longer trading. These collected data forms the basis for analyzing the returns acquired from investing in potential takeover targets. Survival analysis is used to analyze the hazard rate for both the acquisition and bankruptcy of distressed firms. The results of the analysis indicate that the ZSCORE, a predictor of the probability of failure, and SPCSRM, the rating by Standard and Poor's, can be used as financial indicators in the screening mechanisms for financially distressed firms. A multinomial-logit acquisition model is used to predict three outcomes of financially distressed firms: survival, acquisition and failure. This model is tested using two methods by simulating the probability of acquisition. The first uses to compare the predicted versus the actual corporate events to maximize the predicted acquisition event. The second uses to compute abnormal return to maximize portfolio return over a given time period, continual on the ZSCORE, probability of acquisition, and the length of holding period. The predictive model of the acquisition probability is applied as a stock entry rule in a buy-sell system. The success of the model will serve two purposes. One is to predict the economic value of acquisition. The other is to provide successful strategies for investing in stocks.

The relative economic efficiency of acquisitions as a means of restructuring financially distressed firms is investigated. Yearly accounting and daily stock price data are extracted for the period between 1979 and 1998 on firms entering financial distress The behaviour and performance of these firms were traced for a five year period following their entry into distress or until their shares were no longer trading. These collected data forms the basis for analyzing the returns acquired from investing in potential takeover targets. Survival analysis is used to analyze the hazard rate for both the acquisition and bankruptcy of distressed firms. The results of the analysis indicate that the ZSCORE, a predictor of the probability of failure, and SPCSRM, the rating by Standard and Poor's, can be used as financial indicators in the screening mechanisms for financially distressed firms. A multinomial-logit acquisition model is used to predict three outcomes of financially distressed firms: survival, acquisition and failure. This model is tested using two methods by simulating the probability of acquisition. The first uses to compare the predicted versus the actual corporate events to maximize the predicted acquisition event. The second uses to compute abnormal return to maximize portfolio return over a given time period, continual on the ZSCORE, probability of acquisition, and the length of holding period. The predictive model of the acquisition probability is applied as a stock entry rule in a buy-sell system. The success of the model will serve two purposes. One is to predict the economic value of acquisition. The other is to provide successful strategies for investing in stocks.

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In the past, most scholars emphasized the cause of the short-term and long-term abnormality, but often neglected the influence of measure method. As a result, seldom scholars explained the measure method completely. Most scholars think market factor can explain asset return completely, so they use CAPM to evaluate the short-run and long-run performance of IPOs. They find IPOs have initial abnormal return, but they are underperformance in the long run. But if market factors cannot explain IPOs performance completely, short-run and long-run performance does exist or just the model cannot explain? We think it is necessary to modify three-factor model to improve its explanatory power. We utilize Fama-French three- factor model and momentum factor to assemble into four-factor model to revaluate IPOs performance, explore the reasons which influence abnormal return of IPOs in Taiwan, and discuss market efficiency to understand the tendency and the variation of IPOs performance. We conclude that there is no underperformance in Taiwan and Taiwan¡¦s stock market is market efficient. In addition, the empirical result is the same with Loughran and Ritter¡]2000¡^that it will increase explanatory power to use purging benchmark.