North Carolina State University

About: North Carolina State University is a education organization based out in Raleigh, North Carolina, United States. It is known for research contribution in the topics: Population & Thin film. The organization has 44161 authors who have published 101744 publications receiving 3456774 citations. The organization is also known as: NCSU & North Carolina State University at Raleigh.

Oxygen Stress and Superoxide Dismutases

Abstract: The accumulation of dioxygen in Earth's atmosphere allowed for the evolution of aerobic organisms that use O2 as the terminal electron acceptor, thus providing a higher yield of energy compared with fermentation and anaerobic respiration. For example, in aerobic metabolism, the complete breakdown of one molecule of glucose yields a total of 38 molecules of ATP, whereas the anaerobic breakdown of this same glucose molecule to ethanol and CO, yields only 8 ATPs. In its ground state, molecular O2 (dioxygen) is relatively unreactive, yet it is capable of giving rise to lethal reactive ,excited states as free radicals and derivatives. Utilization of O2 proceeds most readily via a complete stepwise, fourelectron reduction to water during which partially reduced reactive intermediates are generated (Fig. 1). The reactive species of reduced dioxygen include the superoxide radical (. 02-), hydrogen peroxide (H202), and the hydroxyl radical (. OH). These and the physiologically energized form of dioxygen, singlet oxygen ('O2), are the biologically most important O2 species. An activation energy of approximately 22 kcal/mol is required to raise molecular O2 from its ground state to its first singlet state. In higher plants, this energy is readily obtained from light quanta via such transfer molecules as Chl (Foote, 1976). A11 of these activated oxygen species are extremely reactive and cytotoxic in a11 organisms. These highly reactive species can react with unsaturated fatty acids to cause peroxidation of essential membrane lipids in the plasmalemma or intracellular organelles. Peroxidation damage of the plasmalemma leads to leakage of cellular contents, rapid desiccation, and cell death. Intracellular membrane damage can affect respiratory activity in mitochondria, cause pigment breakdown, and cause loss of carbon-fixing ability in chloroplasts. Severa1 Calvin-cycle enzymes within chloroplasts are extremely sensitive to H202, and high levels of H202 (the product of superoxide dismutation) directly inhibit C02 fixation (Kaiser, 1979). H202 has also been shown to be active with mixed function oxidases in marking severa1 types of enzymes for proteolytic degradation (Fucci et al., 1983). Superoxide and H202 can react in a \"Haber-Weiss\" reaction to generate the hydroxyl radical ( + OH), which is the most potent oxidant known. The hydroxyl radical indiscriminately and rapidly attacks virtually a11 macromolecules, leading to seri-

False data injection attacks against state estimation in electric power grids

Abstract: A power grid is a complex system connecting electric power generators to consumers through power transmission and distribution networks across a large geographical area. System monitoring is necessary to ensure the reliable operation of power grids, and state estimation is used in system monitoring to best estimate the power grid state through analysis of meter measurements and power system models. Various techniques have been developed to detect and identify bad measurements, including the interacting bad measurements introduced by arbitrary, non-random causes. At first glance, it seems that these techniques can also defeat malicious measurements injected by attackers.In this paper, we present a new class of attacks, called false data injection attacks, against state estimation in electric power grids. We show that an attacker can exploit the configuration of a power system to launch such attacks to successfully introduce arbitrary errors into certain state variables while bypassing existing techniques for bad measurement detection. Moreover, we look at two realistic attack scenarios, in which the attacker is either constrained to some specific meters (due to the physical protection of the meters), or limited in the resources required to compromise meters. We show that the attacker can systematically and efficiently construct attack vectors in both scenarios, which can not only change the results of state estimation, but also modify the results in arbitrary ways. We demonstrate the success of these attacks through simulation using IEEE test systems. Our results indicate that security protection of the electric power grid must be revisited when there are potentially malicious attacks.

Updated national birth prevalence estimates for selected birth defects in the United States, 2004–2006†

Abstract: BACKGROUND: The National Birth Defects Prevention Network collects state-specific birth defects surveillance data for annual publication of prevalence estimates and collaborative research projects. In 2006, data for 21 birth defects from 1999 through 2001 were presented as national birth prevalence estimates. The purpose of this report was to update these estimates using data from 2004 through 2006. METHODS: Population-based data from 11 active case-finding programs, 6 passive case-finding programs with case confirmation, and 7 passive programs without case confirmation were used in this analysis. Pooled birth prevalence estimates for 21 birth defects, stratified by case ascertainment approach, were calculated. National prevalence estimates, adjusted for maternal race/ethnicity and maternal age (trisomy 13, trisomy 18, and Down syndrome only) were determined using data from 14 programs. The impact of pregnancy outcomes on prevalence estimates was also assessed for five specific defects. RESULTS: National birth defects prevalence estimates ranged from 0.72 per 10,000 live births for common truncus to 14.47 per 10,000 live births for Down syndrome. Stratification by type of surveillance system showed that active programs had a higher prevalence of anencephaly, anophthalmia/microphthalmia, cleft lip with or without cleft palate, reduction defect of upper limbs, and trisomy 18. The birth prevalence of anencephaly, trisomy 13, and trisomy 18 also varied substantially with inclusion of elective terminations. CONCLUSION: Accurate and timely national estimates of the prevalence of birth defects are needed for monitoring trends, assessing prevention efforts, determining service planning, and understanding the burden of disease due to birth defects in the United States. Birth Defects Research (Part A) 88:1008–1016, 2010. 2010 Wiley-Liss, Inc.

Understanding Student Differences

Abstract: Students have different levels of motivation, different attitudes about teaching and learning, and different responses to specific classroom environments and instructional practices. The more thoroughly instructors understand the differences, the better chance they have of meeting the diverse learning needs of all of their students. Three categories of diversity that have been shown to have important implications for teaching and learning are differences in students' learning styles (characteristic ways of taking in and processing information), approaches to learning (surface, deep, and strategic), and intellectual development levels (attitudes about the nature of knowledge and how it should be acquired and evaluated). This article reviews models that have been developed for each of these categories, outlines their pedagogical implications, and suggests areas for further study.