This paper investigates the vulnerability of South Africa to the shocks that originate from its major trading partners over time using a structural vector autoregressive framework. We examine the impact of shocks emanating from the EU, the US, China, Japan, India and Brazil on South Africa’s output growth through both direct and indirect trade linkages, by considering the changing trade patterns from 1996 to 2017. The results suggest that the South African economy has become more integrated with emerging economies. Furthermore, China has increased its impact on the output growth of the other sample economies through trade linkages, which implies that developments in China are of increasing importance to other economies. The US and the EU are still dominated in propagating shocks despite their declining impact on the output growth of other economies in this sample.

京都大学 / 0048 / 新制・課程博士 / 博士(経済学) / 甲第19392号 / 経博第527号 / 新制||経||276(附属図書館) / 32417 / 京都大学大学院経済学研究科経済学専攻 / (主査)准教授 敦賀 貴之, 教授 照山 博司, 教授 有賀 健 / 学位規則第4条第1項該当 / Doctor of Economics / Kyoto University / DGAM

This dissertation consists of three chapters which as a whole address development issues in Nigeria. These chapters relate to issues on conflicts, rural labor, education, weather shocks, health, and aid. Chapter 1 studied the effects of conflicts on the labor adjustment patterns of rural households in Northern part of Nigeria. I relied on variation in the conflict incidence and employed the use of instrumental variable technique in order to identify the effect of conflict on several household labor variables. The result reveals that conflict within 20km radius of household has led to adjustment of labor away from agriculture to nonagricultural sectors. Also, it has led to substitution of household agricultural labor with hired labor. The demand pressure on hired labor was also found to have increased the wage rates of agricultural hired labor. Chapter 2 investigates the effects of conflicts, depending on the nature, on educational attainment of individuals in Nigeria. Specifically, I looked at how two forms of conflicts with different nature and perpetrators - Boko Haram insurgence and Farmers and Herders conflict – affects educational attainments in Nigeria. I employed the Difference-in-Difference (DiD) technique and found that both forms of conflict hurts completed years of education of individuals that are exposed to them. However, the magnitude of the effects of farmers and herders conflict tends to be larger than that of boko haram insurgence. Chapter 3 studies the effectiveness of World Bank aid projects in reducing the adverse effects of weather shocks on children’s health in Nigeria. The study revealed that children’s’ exposure to weather shocks in their month of birth and in utero have adverse effects on their Weight-to-age- z-score (WAZ) and height-to-age z-score (HAZ). However, the availability of aid projects within 20km radius of these children helps to reduce such negative effects of such weather shocks.

No description available.

Learning plays an important role in adopting new technology. While the role of learning in the decision to adopt is widely investigated in the literature, its role in knowing how to best use technology and the speed of learning is not. For instance, when farmers adopt groundwater extraction technology, they need to learn their private marginal cost and marginal benefit of extracting water. Comparing the extraction behavior of the owners of new wells with old wells, we explore the role of experience in shaping farmers' decisions. We use three identification strategies to test the hypothesis that owners of new wells extract more water than owners of old wells. Employing panel data at the district level in a fixed-effects model, we find that groundwater extraction rises as the growth rate in new wells increases. Our second strategy uses the exogenous variation in precipitation shocks in a double-difference approach. Employing census data at the well level, we show that more water is extracted from new wells than older wells and that the difference in extraction increases in areas that experience negative precipitation shocks. The third strategy is the nearest-neighbor matching method which confirms the above findings and indicates that old wells are more efficient in maintaining their inter-temporal extraction. We also provide evidence regarding the speed of learning about using technology. Our findings have important implications for discussions of common pool regulation. Firms are often considered entities with complete private information about their true abatement costs. Our findings imply that quantity instruments for regulating groundwater extraction fail to guarantee productive efficiency when farmers face uncertainty about their marginal abatement cost. This paper also provides new insights for optimizing climate change scenarios, in light of the importance of the learning lag in using new technologies. In chapter two, we discuss the effects of precipitation shocks on the rural labor market and migration. The welfare of both agrarian and non-agrarian workers in rural areas is highly affected by agricultural output volatility, caused in part by weather shocks. This paper examines the impact of precipitation shocks on labor supply and out-migration in rural Iran. We use individual-level panel data combined with station-based precipitation data at the rural-agglomeration level to study the intensive and extensive margins of employment. Our results indicate different types of responses to positive and negative shocks. Using a fixed-effects panel data model, we find that workers in agriculture and industry sectors increase their hours of work in response to positive shocks. At the extensive margin, we find that negative shocks reduce the labor market participation of women. We observed heterogeneity in responses based on the sector of employment, gender, and the roles of individuals in the household. We also show that positive shocks affect the division of labor at the household level. Our estimates for the probability of migration indicate that negative shocks raise the probability of migration for young men. We show that the labor-migration of the same group is also affected by negative shocks, but the impact could be explained by the local unemployment rate, implying the labor market is a channel through which precipitation shocks affect migratory decisions. In the final chapter, we investigate parents' investment in the quality of their children. While school enrollment at the primary level has been rising in developing countries to almost complete national coverage, international measures of education quality, especially in basic knowledge of reading and math, do not exhibit a parallel improvement. Since parents' expenditure is an important determinant of children's school performance, we investigate parents' investments in the quality of their children's education, measured by their spending on books and other school materials. We develop an overlapping generations model, in which we consider families' expenditure as an input to their children's human capital. Moreover, in our model, parents use the current status of their children's human capital as a screening measure for adjusting their investment, instead of the standard tradition of simply balancing the trade-off between future income and the current stream of direct and indirect school costs. From our theoretical analysis, our main hypothesis is that families consider better school performance to be a reliable predictor of future return, and this incentivizes them to invest more in children who are academically promising, considering other determinants of children's schooling output, such as school quality. Empirically, we use an instrumental variables approach to test our main hypothesis, and it is accepted using data for Ghanaian primary school students in rural areas. / Doctor of Philosophy / Adopting new technology need learning, either in the form of knowledge or by working with the adopted technology. While the role of learning in the decision to adopt is widely investigated in the literature, its role in knowing how to best use technology and the speed of learning is not. In the first chapter, we investigate the adoption of the use of groundwater technology. When farmers adopt groundwater extraction technology, they need to learn about how to best use the technology to maximize their profit in the short and long run. We use five sets of data from Iran to show the existence of learning in the use of groundwater technology. Our findings improve the discussion on the regulation of firms in using common resources. This paper also provides new insights for optimizing climate change scenarios, in light of the importance of the learning lag in using new technologies. In chapter two, we discuss the effects of precipitation shocks on the rural labor market and migration. Weather shocks affect the welfare of workers in rural areas. This paper examines the impact of precipitation shocks on labor supply and out-migration in rural Iran. We use individual-level and station-based precipitation data at the rural-agglomeration level to study the effects of precipitation shocks on employment. Our results indicate different types of responses to positive and negative shocks. We find that workers in agriculture and industry sectors increase their hours of work in response to positive shocks and negative shocks reduce the labor market participation of women. We also show that the labor market is a channel through which precipitation shocks affect migratory decisions. In the final chapter, we investigate parents' investment in the quality of their children. While school enrollment at the primary level has been rising in developing countries, international measures of education quality, especially in basic knowledge of reading and math, do not exhibit a parallel improvement. Since parents' expenditure is an important determinant of children's school performance, we investigate parents' investments in the quality of their children's education, measured by their spending on books and other school materials. We develop a model, in which we consider families' expenditure as an input to their children's human capital. We hypothesize that families consider better school performance to be a reliable predictor of future return. Empirically, we test our hypothesis, and it is accepted using data for Ghanaian primary school students in rural areas.

Typically, computational fluid dynamic (CFD) solutions produce large amounts of data that can be used for analysis. The enormous amount of data produces new challenges for effective exploration. The prototype system EVITA, based on ranked access of application-specific regions of interest, provides an effective tool for this purpose. Automated feature detection techniques are needed to identify the features in the dataset. Automated techniques for detecting shocks, expansion regions, vortices, separation lines, and attachment lines have already been developed. A new approach for identifying the regions of flow separation is proposed. This technique assumes that each pair of separation and attachment lines has a vortex core associated with it. It is based on the velocity field in the plane perpendicular to the vortex core. The present work describes these methods along with the results obtained.

No description available.

No description available.

No description available.

Gradient-driven mass diffusion, or species separation, is a transport process which can occur in plasma shocks. Experimental observations of this phenomena are difficult to make, but are of interest to ongoing Inertial Confinement Fusion efforts. This body of work describes the results of two major experimental campaigns conducted at Virginia Tech's Experimental Plasma and Propulsion Laboratory to identify species separation in multi-component plasma shocks. A linear plasma-armature railgun forms and accelerates low temperature, high density, supersonic plasma jets, with the collision between two of these jets shown to induce a collisional plasma shock in the first campaign. The second campaign leverages this experimental setup while employing spatially resolved emission spectroscopy alongside collisional radiative modeling to identify species separation within multi-ion-species plasma shocks consisting of argon, aluminum, and nitrogen. These results are some of the first to be performed in a plasma shock with more than two ion species, and can be used for verification and validation of physics models of fusion plasmas. This body of work was supported by the National Science Foundation under Grant No. PHY-1903442. / Doctor of Philosophy / Plasmas represent the fourth state of matter, where enough energy has been imparted onto a gas for ionization to occur, resulting in a quasi-neutral collection of charged and neutral particles that are subject to both hydrodynamic and electrodynamic effects. Shocks can occur in plasmas, which presents as a transition layer where plasma parameters drastically change over a small region of space. Plasmas hold the key to nuclear fusion, with the topic of gradient-driven mass diffusion, or species separation, in plasma shocks being of great interest to large-scale fusion experiments. This body of work performs experimental measurements using a railgun-based plasma source to create plasma shocks with multiple ion species in the laboratory, and ultimately observe this effect of species separation through the use of spatially resolved spectroscopy. To the author's best knowledge, these measurements represent some of the first to be done in a plasma shock with more than two ion species, and can be used to benchmark physics models of plasmas in fusion experiments.