189 research outputs found
Investigating the current and potential distribution of lightning on a building to determine adequate protective measures
No full textThesis-Master of Engineering in Electrical Engineering--Central University of Technology, 2022Lightning is one of the most powerful and spectacular natural phenomena that mankind has ever encountered. Approximately 3 billion lightning flashes occur around the world every year. In South Africa, lightning is responsible for millions of deaths, which is significantly more than the global average. In particular, Bloemfontein is classified as having a high susceptibility to direct lightning strikes, making it a focal point for imposing lightning education and protection measures, owing to the city's rapid population growth.
The challenge exists when people are not educated in lightning protection measures and is considered last when constructing new structures, thus leaving a blank space when it comes to budgeting. There is a widespread misconception that people are immune to the effects of lightning because they are protected by structures and believe that lightning will never come into direct contact with them or have any impact on their daily life. This research’s first objective is to identify appropriate buildings that would clearly distinguish the type of impact that lightning would have on a building, considering various structural and environmental factors. The second objective is to propose a lightning protection system (LPS) for each building based on the outcomes of the lightning risk analysis. The third objective is to conduct a lightning analysis on the pre-defined buildings to outline the types of buildings that are highly susceptible to lightning side effects. The fourth objective is to evaluate the proposed LPS in terms of mitigation to demonstrate the economic impact that lightning would have on a building and focus on the various ways it could interact with people, causing injuries and fatalities. To address each objective of the study, simulations were performed with appropriate computer-based software.
A lightning risk analysis was performed using the DEHNsupport Toolbox software to determine the occurrence of lightning strikes, the source of damage and identify the lightning-related risk components for buildings that will be occupied by people. This analysis was performed in accordance with the methods outlined in the lightning standard SANS 62305. The analysis focused on three specific buildings: Boet Troskie Hall, the Free State Provincial Government and Loch Logan Park. After establishing the lightning sources and risk components, a proposed LPS was implemented on the buildings using architectural software, SketchUp, which was the subject of the lightning simulation study. The lightning study was carried out with an earthing and lightning simulation software, XGSLab, focusing on the frequency and time domains and considering a first negative lightning impulse of 50 kA to visualise the engineering aspects of the current and potential distribution across the LPS.
It was concluded that each building considered for the analysis showed differing results. First, the ground potential rise (GPR) is highly dependent on the earthing resistance by altering the number of conductive materials buried in the soil surface and the magnitude of impulse injected into the LPS. Secondly, the quantity and length of a down-conductor had a significant impact on the current distribution and potential difference simulated at selective points over the LPS. The separation distance that needs to be maintained to prevent dangerous sparking of any metallic elements, resulting in unsafe conditions for people, electrical and electronic equipment, depends on the length of the down-conductors. Thirdly, the current distribution measured over each down-conductor in the LPS for each building did not exhibit any significant variation from the current injection point and the conductors further away. However, as demonstrated on three buildings, adjusting the length and quantity of the down-conductor produced varying results.
Communities should acknowledge the impact of lightning strikes and the extent of damage that could be inflicted on a structure and the consequences that can result from a lightning event. This implementation of an adequate, compliant LPS should be paid attention to by adhering to the appropriate standards. It is recommended not to be designed or implemented with a lack of knowledge, as the effects of lightning may outweigh the benefits, considering the expense of the system
Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.
No full textThe QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD
Halogen-containing species at Comet 67P/Churyumov-Gerasimenko: Full mission results
No full textInternational audienceDhooghe et al. (2017) studied halogen-bearing compounds in the coma of 67P/C-G with the Double Focusing Mass Spectrometer (DFMS) of Rosetta's ROSINA instrument during a few time periods from first encounter up to perihelion (August 2014-August 2015). The main halogen-bearing compounds identified in the comet atmosphere were the hydrogen halides HF (hydrogen fluoride), HCl (hydrogen chloride) and HBr (hydrogen bromide). The halogen to oxygen ratios were found to vary between ~10-4 (Cl/O and F/O) to ~10-6 (Br/O), which shows these compounds have a very low abundance. In a follow-up article, De Keyser et al. (2017) observed an increase in the halogen-to-oxygen ratio as a function of distance, which suggests a distributed source for HF and HCl, probably through progressive release of these compounds from grains. Fayolle et al. 2017 and recent work by Altwegg et al. 2020 show that also CH3Cl and NH4Cl, respectively are present in the coma. To further our knowledge on halogen containing species, we have applied recent improvements in DFMS data analysis techniques (De Keyser et al. 2019) to obtain a high quality time series for the complete mission duration. These data analysis techniques improve the retrieval of the abundances for overlapping mass peaks (18OH+ for F+, H218O+ for HF+, H34S+ for 35Cl+, and 36Ar+ and H234S+ for H35Cl+). The contribution of CS2++ to the signal of H37Cl+ has been determined from data for CS2+. Based on the full mission data, and focusing on chlorine, we determine the 37Cl/35Cl isotopic ratio. An interesting finding is that the 35Cl+/H35Cl+ and 37Cl+/H37Cl+ ratios in the DFMS mass spectrometer do not match the NIST ones for the H35Cl and H37Cl parents. This indicates that at least one additional chlorine source must be present. The variability of halogen-containing species as a function of time is discussed, as well as the possible role of distributed sources
Hungary's bankruptcy experience, 1992-93
No full textHungary adopted a tough new bankruptcy law in late 1991 that took effect on January 1, 1992. It required managers of firms with arrears over 90 days to any creditor to file for either reorganization or liquidation within eight days (the so-called"automatic trigger") and provided a rather sympathetic framework in which to do so. The result: since January 1992, more than 25,000 cases have been filed - far beyond lawmakers'expectations. Both positive and negative views about the law have been expressed, but details about how the process has actually worked have been scarce. The authors help fill this information gap by providing detailed data on a randomly selected stratified sample of actual cases filed in 1992-93, supplemented by information gained through interviews with judges, liquidations, and firms involved in bankruptcy. Their conclusions are as follows. First, the bankruptcy process appears to have had some degree of economic logic in 1992 and 1993. Better firms were more likely to enter and emerge"successfully"from reorganization, while worse firms were more likely either to fail in reorganization or to file directly for liquidation. Second, judicial reorganization need not be slow and costly. The first wave of reorganizations was handled surprisingly quickly, especially considering the sheer number of cases, the novelty of the process, and the shortage of trained judges. This quickness was possible largely because of the decentralized design of the process. Once the court approved a case, the court had little role. (Amendments added in 1993 may have made the process more bureaucratic and expensive). Third, in this sample, major delays occurred not in reorganization but in liquidation. Creditors will do almost anything to avoid filing for liquidation, and once firms enter liquidation they are still likely to be kept alive indefinitely. In the end, this lack of a viable creditor-led"exit"and debt collection mechanism harms firms by increasing the cost and reducing the flow of credit. Fourth, although the bankruptcy process displays some degree of economic logic, one should not assume that it operates as a similar law would in a market economy. In particular, a likely source of private gain in Hungary appears to be asset or other value diversion (or"value-stripping) before bankruptcy. Fifth, the main need is to strengthen the incentives of creditors to monitor the process closely and to improve their ability to do so.Banks&Banking Reform,International Terrorism&Counterterrorism,Strategic Debt Management,Small Scale Enterprise,Small and Medium Size Enterprises,Banks&Banking Reform,Strategic Debt Management,Legal Products,International Terrorism&Counterterrorism,Economic Theory&Research
Small and medium-size enterprises in economic development : possiblities for research and policy
No full textThe World Bank's most important long-term advantage in promoting development, says the author, may lie in opportunities to address related obstacles simultaneously. It could mount concurrent efforts to address the problems of small and medium-size enterprises in a particular sector, region, or economy, for example. It could address the conditions of founding new firms, providing finance or technical assistance, developing mutual support institutions, resolving disputes, and perhaps reducing counterproductive government interventions. Were the Bank to follow such a coordinated approach, programs could be designed to generate data to illuminate the impacts and interactions of various elements of policy. These data could be exploited, then, in research designs, or even the design of management information systems, shaped by program evaluation. The author proposes four general issues for research (plus a series of topics for each issue). (1) Can Bank initiatives involving small and medium-size enterprises in developing countries facilitate the entry of these enterprises into similar learning relationships with other firms - foreign firms, larger firms in their own countries, or each other? (2) The economic significance of high"turbulence"(entry and exit rates) in small-firm populations is poorly understood. The fact of high turbulence is well-documented in industrial countries; it is not for developing countries, but available data suggest a broadly similar pattern. Are high failure rates for small businesses symptomatic of an important shortcoming in the system of economic organization itself? Or should the unit of analysis be the enterprise, the entrepreneur, or the entrepreneur's family? (3) Is the apparent trend favoring a larger economic role for smaller production units autonomous rather than induced by other changes? Does it depend on general operating factors such as the declining costs of communication and computation? (4) The rate of learning by a small firm may depend on the nature of its transacting partner. Certain multinational enterprises make good teachers, for example, but certain local labor markets or markets for consumer goods and services may not be well-positioned for relevant learning. They may learn well how to adjust to local circumstances but not to the international diffusion of technology and ways of organizing (the main source of hope for developing countries). Perhaps Bank policy should be more concerned with transaction patterns.General Technology,Environmental Economics&Policies,Decentralization,ICT Policy and Strategies,Small and Medium Size Enterprises,Environmental Economics&Policies,General Technology,Small and Medium Size Enterprises,ICT Policy and Strategies,Small Scale Enterprise
The optics of homiletics : preaching as reframing of perspective
No full textInaugural lecture delivered on 21 February 2012.Johan Cilliers was born in Luanshya, Zambia (1954); matriculated in De Aar (1972),
and received his theological training at the Faculty of Theology, Stellenbosch
University, as well as the Karl Rupprecht University in Heidelberg, Germany. He
has obtained the following degrees: DTh Theology, Stellenbosch University (SU)
1982; Licentiate in Theology, SU 1979 (cum laude); MTh Theology, SU 1979 (cum
laude); BTh Theology, SU 1978 (cum laude), and BA Philosophy and Greek, SU 1975
(cum laude). After having served as minister in two Dutch Reformed congregations
(in Durban and Stellenbosch), he was appointed as senior lecturer at the Faculty
of Theology, Stellenbosch University, and is currently professor of Homiletics and
Liturgy at this institution.
He is head of the Department of Practical Theology and Missiology at the Faculty; president
of the Society for Practical Theology in South Africa, as well as vice-president of the Societas
Homiletica (the international society for Homiletics). He has delivered guest lectures at the
University of Umea, Sweden, as well as the Humboldt University, Germany, and has written nine
academic books, inter alia on preaching, liturgy and aesthetics. He has co-authored two books
with international scholars, respectively on the foolishness of preaching (with American author
Charles Campbell) and worshipping in the so-called ‘Network Society’ (with Dutch author Marcel
Barnard). He has published more than 60 academic articles in accredited journals, and authored
23 popular religious books, for which he has received numerous awards from the Christian
Booksellers Association of Southern Africa (CBSA).
He has received the Rector’s Award for Excellence in Teaching (2003), the Best Lecturer Award
from the Golden Key International Society and SU’s Academic Affairs Council (2008), as well as the
Rector’s Award for Excellence in Research (2010). As researcher, he holds a National Research
Foundation (NRF) rating and has received grants from the Harry Oppenheimer Memorial Trust as
well as the SU Research Committee. He is fond of languages (speaks German and studies French
among others) and enjoys dabbling in art.1 He is married to Elna, and is the (very proud) father of
twins, Jacques and Karen
Reforming nationhood : England in the literature of the Tudor imperial age, 1509-1553
No full textThe thesis explores the relationship between empire and nationhood in the literature of the Royal Supremacy. In so doing, it contests the assumptions of the social historians Michel Foucault, Benedict Anderson, Jürgen Habermas, and Ernest Gellner - all of whom have dated the dawn of the nation-event on our Western political horizons from the end of the eighteenth century. The thesis invites important outcomes for our perception of early Tudor political culture, and for our wider appreciation of the origins of English national identity. It differentiates the Habsburg imperial idea from the Tudor ideology of empire inherited by Henry VIII upon his accession in 1509. It then distinguishes both these imperial ideologies from Henry's pretensions, as enshrined in the 1533 Appeals Act, to
empire in the English Church. Despite these differences between the Habsburg and Tudor ideologies of empire, each received identical expression in propaganda that identified both England and the Holy Roman Empire with Virgil's Golden Age. The first two chapters explore the Golden Age motif in pageantry produced for the joint London Entry of Henry
VIII and Charles V (1522), and for the Entry of Anne Boleyn in 1533. Chapter Two concludes that the function of the 1533 Entry as propaganda for the Royal Supremacy was
undermined by the similarities between its stagecraft and that of the 1522 Entry
Hydrogen halides at Comet 67P/Churyumov-Gerasimenko: a whole mission overview
No full textInternational audienceIn Dhooghe et al. (2017) and De Keyser et al. (2017) we have studied the halogen-bearing compounds in the coma of 67P/C-G with Rosetta-ROSINA/DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer) from first encounter up to perihelion (August 2014-August 2015) and concluded the main halogen-bearing compounds in the comet atmosphere were the hydrogen halides HF (hydrogen fluoride), HCl (hydrogen chloride) and HBr (hydrogen bromide). An increase in the halogen-to-oxygen ratio as a function of distance was observed which suggests a distributed source for HF and HCl, probably through progressive release of these compounds from grains. We present an update of the results. First, there have been important updates on the calibration parameters for DFMS as well as updates on how these parameters changed over the course of the mission. Second, we now report on all HF and HCl data collected during the mission covering the period from the 7th of August 2014 up to the 6th of September 2016, thus greatly expanding the hydrogen halides database. We discuss our new results in view of the expanded database and the updated DFMS calibration parameters. Dhooghe, F. et al.: Halogens as tracers of protosolar nebula material in comet 67P/Churyumov-Gerasimenko, MNRAS, 472, Issue 2, 1336, doi 10.1093/mnras/stx1911, 2017. De Keyser, J. et al.: Evidence for distributed gas sources of hydrogen halides in the coma of comet 67P/Churyumov-Gerasimenko, MNRAS, 469, Issue Suppl_2, S695, doi 10.1093/mnras/stx2725, 2017
Hydrogen halides at Comet 67P/Churyumov-Gerasimenko: a whole mission overview
No full textInternational audienceIn Dhooghe et al. (2017) and De Keyser et al. (2017) we have studied the halogen-bearing compounds in the coma of 67P/C-G with Rosetta-ROSINA/DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer) from first encounter up to perihelion (August 2014-August 2015) and concluded the main halogen-bearing compounds in the comet atmosphere were the hydrogen halides HF (hydrogen fluoride), HCl (hydrogen chloride) and HBr (hydrogen bromide). An increase in the halogen-to-oxygen ratio as a function of distance was observed which suggests a distributed source for HF and HCl, probably through progressive release of these compounds from grains. We present an update of the results. First, there have been important updates on the calibration parameters for DFMS as well as updates on how these parameters changed over the course of the mission. Second, we now report on all HF and HCl data collected during the mission covering the period from the 7th of August 2014 up to the 6th of September 2016, thus greatly expanding the hydrogen halides database. We discuss our new results in view of the expanded database and the updated DFMS calibration parameters. Dhooghe, F. et al.: Halogens as tracers of protosolar nebula material in comet 67P/Churyumov-Gerasimenko, MNRAS, 472, Issue 2, 1336, doi 10.1093/mnras/stx1911, 2017. De Keyser, J. et al.: Evidence for distributed gas sources of hydrogen halides in the coma of comet 67P/Churyumov-Gerasimenko, MNRAS, 469, Issue Suppl_2, S695, doi 10.1093/mnras/stx2725, 2017
Hydrogen halides at Comet 67P/Churyumov-Gerasimenko: a whole mission overview
No full textInternational audienceIn Dhooghe et al. (2017) and De Keyser et al. (2017) we have studied the halogen-bearing compounds in the coma of 67P/C-G with Rosetta-ROSINA/DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer) from first encounter up to perihelion (August 2014-August 2015) and concluded the main halogen-bearing compounds in the comet atmosphere were the hydrogen halides HF (hydrogen fluoride), HCl (hydrogen chloride) and HBr (hydrogen bromide). An increase in the halogen-to-oxygen ratio as a function of distance was observed which suggests a distributed source for HF and HCl, probably through progressive release of these compounds from grains. We present an update of the results. First, there have been important updates on the calibration parameters for DFMS as well as updates on how these parameters changed over the course of the mission. Second, we now report on all HF and HCl data collected during the mission covering the period from the 7th of August 2014 up to the 6th of September 2016, thus greatly expanding the hydrogen halides database. We discuss our new results in view of the expanded database and the updated DFMS calibration parameters. Dhooghe, F. et al.: Halogens as tracers of protosolar nebula material in comet 67P/Churyumov-Gerasimenko, MNRAS, 472, Issue 2, 1336, doi 10.1093/mnras/stx1911, 2017. De Keyser, J. et al.: Evidence for distributed gas sources of hydrogen halides in the coma of comet 67P/Churyumov-Gerasimenko, MNRAS, 469, Issue Suppl_2, S695, doi 10.1093/mnras/stx2725, 2017
- …
