94 research outputs found
Impact of wind farms on electro-magnetic transients on 132kV network, with particular reference to fault detection
Impact of wind farms on electro-magnetic transients on 132kV network, with particular reference to fault detection
High frequency fault location technique for transmission lines based on artificial neural networks and genetic algorithms using current signals only
High frequency fault location technique for transmission lines based on artificial neural networks and genetic algorithms using current signals only
Modeling and analysis of superconducting fault current limiters applied in VSC-HVDC systems
Direct current transmission based on Voltage Source Converters (VSC-HVDC) has a number of advantages compared with traditional HVDC systems. However, VSC-HVDC systems are subjected to high short circuit currents due to faults in the DC line, which may contribute negatively to the dissemination and advances of this technology. In this context, this paper analyzes the impact of superconducting fault current limiters on the system response due to faults in the DC line. An effective model for fault limiters is proposed, aiming at limiting the fault current to values below the short circuit withstand capability of DC breakers. The results show the effectiveness of the method and the advantages of using superconducting materials to minimize the impact of faults on VSC-HVDC lines
Individual correlates of podoconiosis in areas of varying endemicity: a case-control study
BACKGROUND
Podoconiosis is a non-filarial form of elephantiasis resulting in lymphedema of the lower legs. Previous studies have suggested that podoconiosis arises from the interplay of individual and environmental factors. Here, our aim was to understand the individual-level correlates of podoconiosis by comparing 460 podoconiosis-affected individuals and 707 unaffected controls.
METHODS/PRINCIPAL FINDINGS
This was a case-control study carried out in six kebeles (the lowest governmental administrative unit) in northern Ethiopia. Each kebele was classified into one of three endemicity levels: 'low' (prevalence 5%). A total of 142 (30.7%) households had two or more cases of podoconiosis. Compared to controls, the majority of the cases, especially women, were less educated (OR = 1.7, 95% CI = 1.3 to 2.2), were unmarried (OR = 3.4, 95% CI = 2.6-4.6) and had lower income (t = -4.4, p<0.0001). On average, cases started wearing shoes ten years later than controls. Among cases, age of first wearing shoes was positively correlated with age of onset of podoconiosis (r = 0.6, t = 12.5, p<0.0001). Among all study participants average duration of shoe wearing was less than 30 years. Between both cases and controls, people in 'high' and 'medium' endemicity kebeles were less likely than people in 'low' endemicity areas to 'ever' have owned shoes (OR = 0.5, 95% CI = 0.4-0.7).
CONCLUSIONS
Late use of shoes, usually after the onset of podoconiosis, and inequalities in education, income and marriage were found among cases, particularly among females. There were clustering of cases within households, thus interventions against podoconiosis will benefit from household-targeted case tracing. Most importantly, we identified a secular increase in shoe-wearing over recent years, which may give opportunities to promote shoe-wearing without increasing stigma among those at high risk of podoconiosis
Cell fusions in mammals
Cell fusions are important to fertilization, placentation, development of skeletal muscle and bone, calcium homeostasis and the immune defense system. Additionally, cell fusions participate in tissue repair and may be important to cancer development and progression. A large number of factors appear to regulate cell fusions, including receptors and ligands, membrane domain organizing proteins, proteases, signaling molecules and fusogenic proteins forming alpha-helical bundles that bring membranes close together. The syncytin family of proteins represent true fusogens and the founding member, syncytin-1, has been documented to be involved in fusions between placental trophoblasts, between cancer cells and between cancer cells and host cells. We review the literature with emphasis on the syncytin family and propose that syncytins may represent universal fusogens in primates and rodents, which work together with a number of other proteins to regulate the cell fusion machinery
Rationale, description and baseline findings of a community-based prospective cohort study of kidney function amongst the young rural population of Northwest Nicaragua
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