The Algorithmic Complexity of Bondage and Reinforcement Problems in bipartite graphs

Let $G=(V,E)$ be a graph. A subset $D\subseteq V$ is a dominating set if every vertex not in $D$ is adjacent to a vertex in $D$. The domination number of $G$, denoted by $\gamma(G)$, is the smallest cardinality of a dominating set of $G$. The bondage number of a nonempty graph $G$ is the smallest number of edges whose removal from $G$ results in a graph with domination number larger than $\gamma(G)$. The reinforcement number of $G$ is the smallest number of edges whose addition to $G$ results in a graph with smaller domination number than $\gamma(G)$. In 2012, Hu and Xu proved that the decision problems for the bondage, the total bondage, the reinforcement and the total reinforcement numbers are all NP-hard in general graphs. In this paper, we improve these results to bipartite graphs.Comment: 13 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:1109.1657; and text overlap with arXiv:1204.4010 by other author

GPU acceleration of many-body perturbation theory methods in MOLGW with OpenACC

Quasiparticle self-consistent many-body perturbation theory (MBPT) methods that update both eigenvalues and eigenvectors can calculate the excited-state properties of molecular systems without depending on the choice of starting points. However, those methods are computationally intensive even on modern multi-core central processing units (CPUs) and thus typically limited to small systems. Many-core accelerators such as graphics processing units (GPUs) may be able to boost the performance of those methods without losing accuracy, making starting-point-independent MBPT methods applicable to large systems. Here, we GPU accelerate MOLGW, a Gaussian-based MBPT code for molecules, with open accelerators (OpenACC) and achieve speedups of up to 9.7x over 32 open multi-processing (OpenMP) CPU threads

The Effect Of Flood Reduction And Water Conservation Of Decentralized Rainwater Management System

Climate change and increase of surface runoff by urbanization caused the urban flooding. Therefore, a sustainable new paradigm is required to recover sound water circulation and overcome the limitations of the existing water management system vulnerable to flooding. Recently Rainwater management is widely known and its legal obligation is strengthened to improve the control capacity for flooding reduction and water conservation in urban areas. Multipurpose DRMS(Decentralized Rainwater Management System) is a new paradigm proposed and recommended by NEMA(National Emergency Management Agency) for both flood control and water conservation. In this study, a flood prone area in Suwon of South Korea is selected and analysis of DRMS has been made using XP-SWMM for different scenarios of RT installation with same total rainwater tank volume and location. In addition, the effects of water resources secure were analyzed in accordance with using stored rainwater in tank. Also according to a strong will of local governments for DRMS application in developing area, the additional guidelines were first given for DRMS design method and modeling realization using XP-SWMM, know-how for data collection and transformation. As a result, installing one rainwater tank of 3,000㎥ can reduce the peak flow rate by 15.5%. Installing six rainwater tanks of 500㎥ volume in the area can reduce the peak flow rate by 28%. Three tanks concentrated in the middle region can reduce peak rate more than evenly distributed tanks. In case of the same tank volume, the more the number of rainwater storage tanks installed, the more the better water quality was guaranteed. The method and results found from this study can be used for the design and performance prediction of DRMS at a flood prone area by supplementing the existing system, which contribute to design rainwater management system at small scale development area of P city in reality

The Responses of Small Open Economies to Foreign Interest Rate Shocks: Considering Structural Break, Net External Credit, and Financial Integration

This dissertation enhances our understanding of the effect of foreign interest rate shocks on small open economies. This dissertation investigates related issues such as the result of structural break unit root tests, the role of net external credit (or debt) and financial integration, and the difference in the response of a small open economy based on its categorization. In chapter 2, this study compares various endogenous structural break unit root tests such as the ZA test, the LM test and the KP test. This study points out important drawbacks of the LM test that have been ignored, and also demonstrates practical problems of the KP test. The empirical result implies that the Asian financial crisis seems to be the most significant structural break in most macroeconomic variables of South Korea for the last 20 years. Meanwhile, it turns out that some macroeconomic variables of South Korea still remain nonstationary even after the consideration of a structural break. In chapter 3, this study shows that the Korean economy after the Asian financial crisis demonstrates that, when a small open economy has sizable net external credit, foreign interest rate hikes may cause real expansion due to a positive wealth effect. In addition, the empirical result implies that enhanced financial integration of a small open economy enables foreign interest rate shocks to explain a higher proportion of fluctuations in financial variables of the small open economy. Considering the co-movement of the foreign interest rate with the domestic interest rate of South Korea after the Asian financial crisis, enhanced financial integration seems to make the interest rate channel more important. In chapter 4, this study suggests a new method to categorize small open countries based on net external credit (or debt) and financial integration level. This study shows how responses of developing countries to foreign interest rate shocks differ depending on their categorization. The empirical result based on the Panel VAR methodology shows that overall responses seem to be consistent with the theoretical model that is based on 3 transmission channels

Influence of Flooding, Soil Ph, Copper, and Zinc on Growth and Chemical Composition of Rice Plants.

Investigations were conducted in the greenhouse, field, and laboratory to evaluate eight different chemical methods for estimating the availability of Cu in air-dried and flooded soils, and to determine the influence of flooding, soil pH, and applications of Cu and Zn on the growth and chemical composition of rice (Oryza sativa L. cultivar Saturn) plants grown on selected soils in Louisiana. DTPA-TEA extractant generally removed smaller amounts of Cu and Zn and larger amounts of Mn and Fe from flooded soils than from air-dried soils. In general, levels of soil Ca, Mg, and K were significantly correlated with extractable Cu. No significant relationships were found between extractable Cu and soil pH or soil organic matter content. The DTPA-TEA, pH 7.3, 0.1N HCl, and 1N NH(,4)OAc, pH 4.8 extractable Cu were significantly related to the concentration of Cu in rice tissue. A significant negative correlation was found between Cu concentration in rice tissue and soil organic matter content. Multiple regressions consisting of extractable Cu and soil organic matter accounted for over 53% of the variations in predicted concentration of Cu in rice tissue. In general, Cu uptake by rice plants was significantly correlated with extractable Cu. Flooding the Lafitte muck significantly increased the production of dry matter, total leaf chlorophyll content, and the concentrations of Cu, Fe, and P, and significantly decreased the concentrations of Zn, Mn, Ca, and K in rice tissue. The dry matter production and nutrient concentration and uptake by rice plants were greatly reduced when soil pH was adjusted to over 5.9 by application of CaCO(,3). The concentrations of Cu, Zn, Mn, and Fe in rice tissue were significantly higher at pH 4.8 than at pH 4.2. The application of 5ppm of Cu significantly increased the production of dry matter, total leaf chlorophyll content, and concentrations of Cu, Fe, and Ca, and significantly decreased the concentrations of P and K in rice tissue. The concentration of Cu in the tissue of rice plants grown on Lafitte muck without applied Cu tended to be lower under flooded conditions than under nonflooded conditions. When Cu was applied, it was significantly higher under flooded conditions. The soil pH levels did not significantly influence the concentration of Cu in plants grown on the soil that did not received Cu. Application of Cu resulted in a significantly higher Cu concentration in rice tissue at pH 4.8, 5.4, and 5.9. The concentration of Zn in rice tissue was significantly increased at pH (LESSTHEQ) 5.4, and decreased at pH (GREATERTHEQ) 5.9 by application of Cu. Cu and Zn applied to Crowley silt loam under field conditions did not significantly influence the grain yields, although consistently higher yields were obtained on plots that received Cu and Zn in each of the two years. The application of Cu significantly increased the leaf concentrations of Cu and Zn. Applied Zn significantly increased the concentration of Zn, but did not significantly influence the concentration of Cu in rice leaves at first joint. The data obtained from laboratory, greenhouse, and field investigations indicate that there is not a critical need for supplemental Cu fertilization of rice on the mineral soils. The data suggest that Cu may be beneficial to rice plants growing on soils that contain more than approximately 4% of organic matter and less than 0.2 ppm of DTPA-TEA extractable Cu