Low Density Parity Check (LDPC) codes are the parity check codes of long block length, whose parity check matrices have relatively few non-zero entries. To improve the performance at relatively short block lengths, LDPC codes are constructed by either pseudo-random or quasi-cyclic methods instead of random construction methods. In this thesis, pseudo-random code construction methods, the effects of closed loops and the graph connectivity on the performance of pseudo-random LDPC codes are investigated. Moreover, quasi-cyclic LDPC codes, which have encoding and storage advantages over pseudo-random LDPC codes, their construction methods and performances are reviewed. Finally, performance comparison between pseudo-random and quasi-cyclic LDPC codes is given for both regular and irregular cases.

Traditional solutions to information security in communication systems act in the application layer and are oblivious to the effects in the physical layer. Physical-layer security methods, of which information-theoretic security is a special case, try to extract security from the random effects in the physical layer. In information-theoretic security, there are two asymptotic notions of secrecy---weak and strong secrecy This dissertation investigates the problem of information-theoretic strong secrecy on the binary erasure wiretap channel (BEWC) with a specific focus on designing practical codes. The codes designed in this work are based on analysis and techniques from error-correcting codes. In particular, the dual codes of certain low-density parity-check (LDPC) codes are shown to achieve strong secrecy in a coset coding scheme. First, we analyze the asymptotic block-error rate of short-cycle-free LDPC codes when they are transmitted over a binary erasure channel (BEC) and decoded using the belief propagation (BP) decoder. Under certain conditions, we show that the asymptotic block-error rate falls according to an inverse square law in block length, which is shown to be a sufficient condition for the dual codes to achieve strong secrecy. Next, we construct large-girth LDPC codes using algorithms from graph theory and show that the asymptotic bit-error rate of these codes follow a sub-exponential decay as the block length increases, which is a sufficient condition for strong secrecy. The secrecy rates achieved by the duals of large-girth LDPC codes are shown to be an improvement over that of the duals of short-cycle-free LDPC codes.

台灣地區生育率逐年下降，從1985年起總生育率即低於替代水準2.1；近幾年更快速下降，2005年降至空前的1.12，僅有1960年的1/6。為瞭解台灣地區生育率的未來趨勢，本文研究婦女生育年齡、勞動參與率、教育程度及胎次生育率，與世界各國比較，以分析生育率的變化。我們發現近年台灣、日本及法國各年齡組對生育率的貢獻幾乎相同，但法國的總生育率卻有2的水準。比較台灣地區大專以上及高中以下教育程度的婦女，兩者的生育情況在早期是有所差別的，但近年兩者的生育行為非常接近；大學以上及高中以下的婦女生育率均同時降低，生育率的下降似乎和婦女教育程度關係不大。除了以年齡別的角度進行分析，本文也在胎次別生育率的研究上探討及驗證過去的模型與理論，提出模型以修正Feeney的胎次進級模型，從台灣地區資料的計算結果來比較，兩者相差不大，建議在資料允許的情況下可以使用我們提出的計算方法。 / The fertility rates in Taiwan decline rapidly. The total fertility rate has been lower than the replacement level 2.1 since 1985 and it reached to 1.12, the historical low in 2005, only 1/6 of which in 1960. In order to explore the fertility trend in Taiwan, several variables were used to compare with countries in the world, including women fertility rate by age groups, female labor force participation rate, fertility of women with different educational attainments and fertility rate by birth order. We found that Taiwan, Japan and France share a similar fertility pattern, unlike in the U.S., while the young female groups still have significant contribution on fertility. For the variable of highest education attained, the group of senior high school and below have higher fertility before 1970’s comparing to that of education with college and higher. However, the gap narrowed down in recent years. Also, for the fertility rates by birth order, we proposed a new model estimation for the parity progression model. We found that the results of proposed method are almost identical to those of the original method, but the computation is much easier.

本研究主要探討中國如何介入中東地區，並且檢視其多重戰略操作現況，其中包括了安全議題、能源議題、以及經貿議題。透過中國藉由上述議題介入中東事務的發展，本研究期望能呈現中國的中東外交政策及其未來發展趨勢。本研究以中國與美國兩強是否會在中東地區發生權力轉移的可能作為研究問題，有鑑於此，本研究以AFK Organski的權力轉移理論作為全文的概念化基礎，並且重新檢視權力轉移理論在近年來的發展與實踐。就此，本研究將回應下列幾個問題:中國的中東外交政策之主要戰略目的為何?此一政策在中國全方位外交政策中的權重與定位為何?中國與中東國家的交往及雙邊關係中，所具備的優勢與劣勢為何?從結構層次來說，中國與美國在中東是否將達到權力平衡的局面?最後，中國是否滿意現階段自身在中東的地位以及中東地緣政治本身的現況?又或者中國傾向改變中東現狀，並且有意取代美國。本研究透過對上述問題的重新檢視，發現如果中國在中東所介入的勢力與議題越廣泛，並且以挑戰美國霸權為前提全力推進中國的中東介入政策，這意味著中東的現狀與規則將會被調整與改變，進而產生權力轉移的情況。不過，中國現階段並未有意、有能力挑戰美國在中東的戰略地位，因為這將使得中國與美國的結構性矛盾導向衝突。 / This study aims at examining the different aspects of China’s involvement in the Middle East: security, energy and economy, in the context of its evolving foreign policy and changing international status. The main question of the research is whether a power transition between the US and China is possible in the region of the Middle East. Hence. The power transition theory developed by AFK Organski in the 1950s is the basis of this research. The main question is answered by several secondary questions: What is China's foreign policy in the Middle East, and how does it combine into its overall foreign policy; What are the strong points as opposed to the weak points of China's relations with Middle Eastern countries; Is China on the course of achieving parity with the US in the region of Middle East? And the last one, is China satisfied with its current role in the Middle East and the regional existing order, or it would like to alter it in order for it to be able to replace the US as the hegemonic power in the area. If China is indeed becoming more powerful in the area and is challenging the American hegemony, the transformation of the current order and accepted rules of the games in the region could be changed to accommodate China’s needs, and this might lead to tension between China and the US or even conflicts.

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This dissertation interrogates the representation of SiSwati programming (a minority language) on SABC 1 It critically analyses the statutory provisions in place for language parity and utilises hegemony as the theoretical framework for understanding the concept of language parity in the South African broadcasting landscape. To the researcher’s knowledge, there is limited information pertaining to this particular research topic however, most of the previous literature refers to all eleven official languages and not SiSwati specifically. Hegemony, a strand of critical theory as developed by Antonio Gramsci, will serve as the theoretical base of this study. This study falls within the framework of qualitative research. An extensive literature study of various sources and a content analysis of the relevant legislative documents form the basis of the research. SABC TV is positioned in a highly competitive, multi-channel market environment with powerful social, political and economic forces to contend with, this makes it difficult for SABC TV to fulfil its mandate of treating all eleven official languages equitably, hence languages such as SiSwati are underrepresented on national television. This study is seminal and relevant insofar as it offers a much needed insight into the plight of a marginalised language by the country’s public broadcaster. / MA (Communication Studies), North-West University, Potchefstroom Campus, 2014

In this dissertation, I focus on the development and application of nonparametric methods in econometrics. First, a constrained nonparametric regression method is developed to estimate a function and its derivatives subject to shape restrictions implied by economic theory. The constrained estimators can be viewed as a set of empirical likelihood-based reweighted local polynomial estimators. They are shown to be weakly consistent and have the same first order asymptotic distribution as the unconstrained estimators. When the shape restrictions are correctly specified, the constrained estimators can achieve a large degree of finite sample bias reduction and thus outperform the unconstrained estimators. The constrained nonparametric regression method is applied on the estimation of daily option pricing function and state-price density function. Second, a modified Cumulative Sum of Squares (CUSQ) test is proposed to test structural changes in the unconditional volatility in a time-varying coefficient model. The proposed test is based on nonparametric residuals from local linear estimation of the time-varying coefficients. Asymptotic theory is provided to show that the new CUSQ test has standard null distribution and diverges at standard rate under the alternatives. Compared with a test based on least squares residuals, the new test enjoys correct size and good power properties. This is because, by estimating the model nonparametrically, one can circumvent the size distortion from potential structural changes in the mean. Empirical results from both simulation experiments and real data applications are presented to demonstrate the test's size and power properties. Third, an empirical study of testing the Purchasing Power Parity (PPP) hypothesis is conducted in a functional-coefficient cointegration model, which is consistent with equilibrium models of exchange rate determination with the presence of trans- actions costs in international trade. Supporting evidence of PPP is found in the recent float exchange rate era. The cointegration relation of nominal exchange rate and price levels varies conditioning on the real exchange rate volatility. The cointegration coefficients are more stable and numerically near the value implied by PPP theory when the real exchange rate volatility is relatively lower.

How do financial variables, such as firms’ cash flow and banks’ capital, affect macroeconomic variables, such as investment and GDP growth? What are the macroeconomic effects of exchange rate depreciation in countries where firms and households have extensive foreign-currency liabilities? The doctoral thesis Empirical Essays on Macro-Financial Linkages consists of four separate papers in the field of empirical macroeconomics. The first three papers investigate the macroeconomic implications of financial-market imperfections. Imperfect information between borrowers and lenders makes it more costly for firms to finance investments with external funds than with internal funds. The external finance risk premium depends on the strength of firm balance sheets, which hence affects firm investment. The first paper, The Effect of Cash Flow on Investment: An Empirical Test of the Balance Sheet Channel, examines the importance of financial constraints for investment using a large Swedish firm-level data set which includes many smaller firms (where balance sheet effects are likely to be especially important). I find a positive effect of cash flow on investment, controlling for fundamental determinants of investment and any information in cash flow about investment opportunities. As predicted by the balance sheet channel, the estimated effect of cash flow on investment is especially large for firms which, a priori, are more likely to be financially constrained (low-dividend, small and non-group firms). Moreover, the investment-cash flow sensitivity is significantly larger and more persistent during the first half of the sample period, which includes a severe banking crisis and recession. The second paper, Credit Matters: Empirical Evidence on U.S. Macro-Financial Linkages, written jointly with Tamim Bayoumi, estimates the impact of an adverse shock to bank capital on credit availability and spending in the United States, allowing for feedback from spending and income through the balance sheets of banks, firms and households. We find that an exogenous fall in the bank capital/asset ratio by one percentage point reduces real GDP by some 1 ½ percent through its effects on credit availability, while an exogenous fall in demand of 1 percent of GDP is gradually magnified to around 2 percent through financial feedback effects. The third paper, The Effects of Real Exchange Rate Shocks in an Economy with Extreme Liability Dollarization, studies the effects of real exchange rate depreciation in Bolivia, where over 95 percent of bank credit is denominated in dollars. Currency depreciation increases the domestic-currency value of foreign-currency liabilities and the debt service burden, thus adversely affecting firm balance sheets. A key issue for policymakers in countries with widespread foreign-currency borrowing is whether depreciation would have the standard, expansionary effect on output, or if an adverse balance sheet would dominate. I find that real exchange depreciation has negligible effects on output, since a contractionary balance-sheet effect on investment is counteracted by the standard expansionary effect on net exports. The fourth paper, Uncovered Interest Parity in a Partially Dollarized Developing Country: Does UIP Hold in Bolivia? (And If Not, Why Not?), studies another aspect of macro-financial linkages. The so-called uncovered interest parity (UIP) condition states that interest rate differentials compensate for expected exchange rate changes, equalizing the expected returns from holding assets which only differ in terms of currency denomination. Because of data availability problems, there is a lack of empirical tests of UIP for developing countries. The paper studies the case of Bolivia, where there are bank accounts which only differ in terms of currency denomination (bolivianos or U.S. dollars). I find that UIP does not hold in Bolivia, but that the deviations are smaller than in most other studies of developed and emerging economies. / Diss. Stockholm : Handelshögskolan, 2009 Sammanfattning jämte 4 uppsatser

Thesis (Master of Military Studies)-Marine Corps Command and Staff College, 2008. / Title from title page of PDF document (viewed on: Dec 29, 2009). Includes bibliographical references.

A dissertação analisa as experiências de anticoncepção de mulheres pobres multíparas, considerando os fatores que condicionam a sua autonomia no campo da anticoncepção. A pesquisa foi de cunho qualitativo, do tipo descritivo-exploratório. A coleta das informações foi desenvolvida através da realização de grupos focais com multíparas que freqüentam uma Unidade Básica de Saúde da região metropolitana de Porto Alegre. As informações foram analisadas através de análise de conteúdo proposta por Minayo. A análise sugere que, para as participantes da pesquisa, o número elevado de filhos se justifica em função da sua autonomia contraceptiva reduzida gerada por fatores sociais e individuais. A análise indicou os seguintes fatores como implicados na produção de multiparidade – (1) sociais: dificuldades financeiras, problemas de acesso aos serviços de saúde e aos métodos anticoncepcionais e desigualdades de poder de gênero e (2) individuais: efeitos colaterais dos métodos anticoncepcionais e a auto-responsabilização pelo controle da fertilidade do casal. A multiparidade traz repercussões negativas para a vida dessas mulheres e, apesar de as participantes da pesquisa, em alguma medida, terem consciência dos fatores que limitam o seu potencial de autonomia para escolherem quando e quantos filhos ter, elas parecem não ter poder para modificar essa situação. No entanto, como o poder circula nas relações, suas falas sugerem que existe sempre a possibilidade de que elas ocupem posições de poder e consigam minimizar as dificuldades que enfrentam para controlar sua fertilidade. A pesquisa permite concluir que a retórica produzida no campo do planejamento familiar e sua ênfase na defesa dos direitos reprodutivos contradizem as experiências vividas pelas mulheres pobres que participaram desta pesquisa, no sentido de que essas mulheres não estão exercendo o direito de controlar sua fertilidade. O estudo traz contribuições para o trabalho dos profissionais de saúde no sentido de indicar não só as circunstâncias e os fatores implicados com a produção do fenômeno da multiparidade em comunidades pobres, como também de mostrar os limites das ações e dos serviços que atuam no campo do planejamento familiar. / This dissertation analyzes experiences of contraception among low-income multiparae women, considering factors that condition their autonomy in the field of contraception. The research is characterized as qualitative, descriptive-exploratory. Data collection was carried out through focus groups of multiparae women who attended a Basic Health Unit in Porto Alegre. Information was analyzed through the content analysis proposed by Minayo. The analysis has suggested that, for the participants of this research, the high number of children is justified by their reduced contraceptive autonomy, which is generated both by social and individual factors. The analysis has pointed out the following factors as being implied in the production of multiparity. (1) Social: financial problems, difficult access to health services and contraceptive methods, and inequality of gender power; (2) Individual: side effects of the contraceptive methods, and self-responsibility for the couple’s fertility control. Multiparity causes negative effects in those women’s lives and, although the participants of this research, to a certain extent, were aware of the factors that limit their autonomy potential to choose when and how many children to have, they seemed not to have power to change this situation. However, as power circulates in the relationships, their speech suggests that there is always the possibility to occupy power positions and be able to minimize difficulties they face to control their fertility. The research allows for the conclusion that the rhetoric produced in the field of family planning and its emphasis on the advocacy of reproduction rights contradicts the experiences that poor women have had, in the sense that those women are not exercising their right to control their fertility. The study has brought contributions to work of health professionals, not only indicating the circumstances and factors implied in the production of the multiparity phenomenon in low-income communities, but also showing the limits of actions and services that are present in the field of family planning. / La disertación analiza las experiencias de anticoncepción de mujeres pobres multíparas, considerando los factores que condicionan su autonomía en el campo de la anticoncepción. La investigación fue de cuño cualitativo, del tipo descriptivoexploratorio. La colecta de las informaciones fue desarrollada a través de la realización de grupos focales con multíparas que frecuentan una Unidad Básica de Salud de la región metropolitana de Porto Alegre. Las informaciones fueron analizadas a través del análisis de contenido propuesto por Minayo. El análisis sugiere que, para las participantes del estudio, el número elevado de hijos se justifica en función de su autonomía contraceptiva reducida generada por factores sociales e individuales. El análisis indicó los siguientes factores involucrados en la producción de multipariedad – (1) sociales: dificultades financieras, problemas de acceso a los servicios de salud y a los métodos anticoncepcionales y desigualdades de poder de género y (2) individuales: efectos colaterales de los métodos anticoncepcionales y la auto-responsabilidad por el control de la fertilidad de la pareja. La multipariedad trae repercusiones negativas para la vida de esas mujeres y, a pesar de que las participantes de la investigación, en cierta medida, tengan conciencia de los factores que limitan su potencial de autonomía para escoger cuándo e cuántos hijos tener, ellas parecen no tener poder para modificar esa situación. Sin embargo, como el poder circula en las relaciones, sus discursos sugieren que siempre existe la posibilidad de que ellas ocupen posiciones de poder y consigan minimizar las dificultades que enfrentan para controlar su fertilidad. El estudio permite concluir que la retórica producida en el campo de la planificación familiar y su énfasis en la defensa de los derechos reproductivos contradicen las experiencias vividas por las mujeres pobres que participaron de esta investigación, en el sentido de que esas mujeres no están ejerciendo el derecho de controlar su fertilidad. Este estudio también trae contribuciones para el trabajo de los profesionales de la salud en relación a la posibilidad de indicar no solo las circunstancias y los factores implicados en la producción del fenómeno de lamultipariedad en comunidades pobres, como también de mostrar los límites de las acciones y de los servicios que actúan en el campo de la planificación familiar.