Automatic Evaluation of Python and C Programs with codecheck

This project enhances the codecheck autograder by implementing automatic evaluation of C and Python programs. Two security approaches are implemented and analyzed in order to complete this goal. The first approach involves isolation by using virtualization and the second approach involves hardening of the host operating system. I describe both implementations and measure their performance levels to see which approach is more efficient

Comparative and Competitive Advantage of the Shrimp Industry in Mekong River Delta, Vietnam

Given the growing prominence of Vietnam's fishery products in the world market, this study examines data on shrimp aquaculture in the country, as practiced through intensive and semi-intensive methods, in two provinces in the Mekong River Delta region. The study estimates the comparative and competitive advantage of the shrimp industry using various approaches, namely: 1) the RCA or revealed comparative advantage; 2) the Policy Analysis Method (PAM) method to calculate the resource cost ratio (RCR) and RCR* indices; and 3) the Net Social Profitability (NSP) and Net Private Profitability (NPP). To identify the effects of changes in key factors affecting competitive and comparative advantage, a sensitivity analysis is conducted. The results show that Vietnam's shrimp products maintain a strong competitive position in the world market, as evidenced by an RCA greater than 1. The RCR and RCR* estimates bordering on zero also indicate the strong comparative and competitive advantage of the shrimp industry. These findings are bolstered as well by the resulting NSP and NPP estimates. Furthermore, in terms of farming methods, the lower RCR and RCR* estimates for the intensive farms confirm their higher comparative and competitive advantage, compared to the semi-intensive model. Finally, the sensitivity analysis shows that the comparative and competitive advantage of shrimp is strongly sensitive to the price of feed, exchange rate, shrimp yield, and export price. The wage rate also exhibits a slight effect on the industry's standing in the world market. Improving the productivity and quality of shrimp is shown to be vital to the MRD shrimp industry because this would translate into a higher export price and higher yield of shrimp, which will further enhance the industry's comparative and competitive advantage.

Potential energy surface for highly energetic species: fuels for thoughts

The research in this thesis involves the development and application of electronic structure theory to obtain an understanding of the molecular electronic structure, bonding, and reaction mechanisms of main group organic and organometallic chemistry, with the emphasis on highly energetic species. Areas of research include: (1) systematic investigations of the molecular electronic structures and bonding of Group IVB (1.1.1) propellanes, and Group IVB 2,4,5-trioxa (1.1.1) propellanes and Group IVB 2,4,5-trithia (1.1.1) propellanes; (2) predicting the structures, stabilities, and dissociation barriers of metastable molecules for possible high energy density material (HEDM) applications; (3) analysis of the mechanism and potential energy surface of the Si[superscript]+ + CH[subscript]3-SiH[subscript]3 reaction; (4) evaluation the [beta] effect of carbon, silicon, germanium, or tin on the carbenium ions in H[subscript]2R[superscript]\u27 MCH[subscript]2CHR[superscript]+ (R[superscript]\u27 = H; R = H, CH[subscript]3; M = C, Si, Ge, Sn); (5) developing parameters for scaling electron correlation energy; (6) study the effect of hydration and dimerization of the formamidine (1,3) sigmatropic rearrangement

Efficiency Analysis and Experimental Study of Cooperative Behaviour of Shrimp Farmers Facing Wastewater Pollution in the Mekong River Delta

Shrimp farming is important to the Vietnamese economy in terms of national income, job creation and poverty alleviation. However, shrimp farming is generally technically inefficient and probably generates too much pollution. To encourage the sustainable development of the Vietnamese shrimp industry, there is a need to improve the productivity of shrimp farms and at the same time to reduce the wastewater pollution generated by shrimp farming. The thesis has two aims: (1) to estimate the efficiency of shrimp farms in the Mekong Delta of Vietnam, with a particular focus on the productivity effects of pollution, and (2) to use experimental economics to investigate policies that could be used to mitigate the wastewater pollution impacting shrimp farms. Overall farmers are found to be inefficient, suggesting farmers are using more inputs than necessary to produce a given output level. Surprisingly, the average extensive (i.e., less capital-intensive) farm is found to be more efficient than the average intensive and semi- intensive (i.e., more capital-intensive) farms. Furthermore, downstream farms are found to be less efficient than upstream farms, suggesting that wastewater pollution influences shrimp farming productivity and results in a negative externality. Evidence from lab-based experiments suggests that the incentives provided by a monitoring and certification agency are not sufficient to promote the full cooperation of shrimp farmers to solve the wastewater pollution problem. However, full cooperation was achieved by providing farmers with an opportunity to communicate. In both cases, self-governance of shrimp farmers was found to be highly effective. The results suggest that community-based management is worthy of further investigation as a possible solution to sustainable development of the shrimp industry in Vietnam. "What we have ignored is what citizens can do and the importance of real involvement of the people involved – versus just having somebody in Washington ... make a rule." Elinor Ostrom (1933-2012

Giant current-driven domain wall mobility in (Ga,Mn)As

We study theoretically hole current-driven domain wall dynamics in (Ga,Mn)As. We show that the spin-orbit coupling causes significant hole reflection at the domain wall, even in the adiabatic limit when the wall is much thicker than the Fermi wavelength, resulting in spin accumulation and mistracking between current-carrying spins and the domain wall magnetization. This increases the out-of-plane non-adiabatic spin transfer torque and consequently the current-driven domain wall mobility by three to four orders of magnitude. Trends and magnitude of the calculated domain wall current mobilities agree with experimental findings.Comment: Final version accepted by Physical Review Letter

Mesures du périmètre crânien dans les troubles envahissants du développement : une étude comparative entre adultes

Un nombre significatif d’enfants autistes ont une macrocéphalie. Malgré plusieurs études du périmètre crânien en autisme, peu d’études ont été faites sur des adultes. Aussi, les références actuelles en périmètre crânien (PC) adulte datent d’environ 20 ans. Les objectifs de cette étude étaient de construire une échelle de référence du PC adulte, et de comparer les taux de macrocéphalie entre un groupe d’adultes autistes et un groupe d’adultes neurotypiques. Dans cette étude, 221 sujets masculins adultes étaient recrutés de différents milieux afin de déterminer le meilleur modèle prédictif du PC et de construire l’échelle de référence. La hauteur et le poids étaient mesurés pour chaque participant afin de déterminer leur influence sur les dimensions crâniennes. Pour la partie comparative, 30 autistes et 36 sujets neurotypiques, tous adultes, étaient recrutés à partir de la base de données du laboratoire de recherche. Pour l’échelle de référence, les résultats démontraient des corrélations positives entre le PC avec la hauteur et le poids. Après analyse, la corrélation conjointe de la hauteur et du poids sur le PC a été déterminée comme étant le modèle qui offre les résultats les plus significatifs dans la prédiction du PC. Pour la partie comparative, les taux de macrocéphalie atteignaient 10,00% chez les autistes contre 2,56% chez les neurotypiques selon la formule de régression linéaire obtenue du modèle. Cependant le test d’exactitude de Fisher n’a révélé aucune différence significative entre les 2 groupes. Mes résultats suggèrent qu’il est nécessaire de considérer la hauteur et le poids en construisant une référence du PC et que, même en utilisant la nouvelle référence, les taux de macrocéphalie demeurent plus élevés chez les autistes adultes que chez les adultes neurotypiques en dépit de l’absence de différences significatives.A significant proportion of autistic children have macrocephaly. Despite numerous head circumference studies in autism, few studies in adults exist. Also, current adult head circumference (HC) references are around 20 years old. The purposes of this study were to construct an adult head measurement reference chart, and to compare macrocephaly rates between a group of autistic adults and a group of typically developing adults. In this study, 221 male adults were recruited from various settings in order to determine the best predictive model for HC and to construct the reference chart. Height and weight were measured for each participant in order to evaluate their influence on head dimensions. For the comparison part, 30 autistic and 36 typically developing adult subjects were recruited from within the research lab’s database. For the reference chart, results showed positive correlations between HC, and both height and weight. After analysis, the combined influence of both height and weight on HC size has was determined to be the model showing most significant results in predicting HC. For the comparison part, macrocephaly rates reached 10.00% in the autistic group against 2.56% in the control group according to the linear regression formula obtained from the model. However, the Fisher’s exact test revealed no significant difference in macrocephaly rates between both groups. My results suggest the necessity of considering both height and weight when constructing a head circumference reference chart and that, even using a new reference, macrocephaly rates remain higher than normal in autistic adults although not significantly different enough from the typically developing adults

Anomalous scaling dimensions and critical points in type-II superconductors

The existence of a {\it stable critical point}, separate from the Gaussian and XY critical points, of the Ginzburg-Landau theory for superconductors, is demonstrated by direct extraction via Monte-Carlo simulations, of a negative anomalous dimension $\eta_{\phi}$ of a complex scalar field $\phi$ forming a dual description of a neutral superfluid. The dual of the neutral superfluid is isomorphic to a charged superfluid coupled to a massless gauge-field. The anomalous scaling dimension of the superfluid order-field is positive, while we find that the anomalous dimension of the dual field is negative. The dual gauge-field does not decouple from the dual complex matter-field at the critical point. {\it These two critical theories represent separate fixed points.} The physical meaning of a negative $\eta_{\phi}$ is that the vortex-loop tangle of the superfluid at the critical point fills space {\it more} efficiently than random walkers, {\it without collapsing}. This is due to the presence of the massless dual gauge-field, and the resulting long-ranged {\it vectorial} Biot-Savart interaction between vortex-loop segments, which is a relevant perturbation to the steric $|\psi|^4$ repulsion term. Hence, the critical dual theory is not in the universality class of the $|\psi|^4$-theory.Comment: 2 pages, 1 figur

Intrinsic Domain Wall Resistance in Ferromagnetic Semiconductors

Transport through zincblende magnetic semiconductors with magnetic domain walls is studied theoretically. We show that these magnetic domain walls have an intrinsic resistance due to the spin-orbit interaction. The intrinsic resistance is independent of the domain wall shape and width when the latter is larger than the Fermi wavelength. For typical parameters, the intrinsic domain wall resistance is comparable to the Sharvin resistance and should be experimentally measurable.Comment: Final versio