9 research outputs found
Geo-spatial analysis of built-environment exposure to flooding: Iowa case study
No full textAbstract Flooding is the most frequent type of natural disaster, inducing devastating damage at large and small spatial scales. Flood exposure analysis is a critical part of flood risk assessment. While most studies analyze the exposure elements separately, it is crucial to perform a multi-parameter exposure analysis and consider different types of flood zones to gain a comprehensive understanding of the impact and make informed mitigation decisions. This research analyzes the population, properties, and road networks potentially exposed to the 100, 200, and 500-year flood events at the county level in the State of Iowa using geospatial analytics. We also propose a flood exposure index at the county level using fuzzy overlay analysis to help find the most impacted county. During flooding, results indicate that the county-level percentage of displaced population, impacted properties, and road length can reach up to 46%, 41%, and 40%, respectively. We found that the most exposed buildings and roads are laid in residential areas. Also, 25% of the counties are designated as very high-exposure areas. This study can help many stakeholders identify vulnerable areas and ensure equitable distribution of investments and resources toward flood mitigation projects
Flood Exposure Assessment of Railway Infrastructure: A Case Study for Iowa
No full textFloods pose a substantial risk to human well-being. These risks encompass economic losses, infrastructural damage, disruption of daily life, and potential loss of life. This study presents a state-wide and county-level spatial exposure assessment of the Iowa railway network, emphasizing the resilience and reliability of essential services during such disasters. In the United States, the railway network is vital for the distribution of goods and services. This research specifically targets the railway network in Iowa, a state where the impact of flooding on railways has not been extensively studied. We employ comprehensive GIS analysis to assess the vulnerability of the railway network, bridges, rail crossings, and facilities under 100- and 500-year flood scenarios at the state level. Additionally, we conducted a detailed investigation into the most flood-affected counties, focusing on the susceptibility of railway bridges. Our state-wide analysis reveals that, in a 100-year flood scenario, up to 9% of railroads, 8% of rail crossings, 58% of bridges, and 6% of facilities are impacted. In a 500-year flood scenario, these figures increase to 16%, 14%, 61%, and 13%, respectively. Furthermore, our secondary analysis using flood depth maps indicates that approximately half of the railway bridges in the flood zones of the studied counties could become non-functional in both flood scenarios. These findings are crucial for developing effective disaster risk management plans and strategies, ensuring adequate preparedness for the impacts of flooding on railway infrastructure
Comprehensive Assessment of Flood Risk and Vulnerability for Essential Facilities: Iowa Case Study
No full textIn this study, nine different types of essential facilities in the state of Iowa (such as hospitals, fire stations, schools, etc.) were analyzed on a county level in terms of flood depth, functionality and restoration time after flooding, and damage sustained during flooding. These essential facilities were also analyzed on the state level in terms of their location relative to the 100 y and 500 y flood zones. Results show that the number of essential facilities within the flood extent reached up to 39%, and during the 100 y flood scenario all but one of the six chosen counties lost functionality of 100% of their facilities. Most essential facilities were found to have a flood depth of 1 to 4 ft deep and a restoration time of 480 days. The purpose of this study is to bring awareness to decisionmakers regarding the risk that flooding events pose to essential facilities and to highlight the increasing dangers of flooding on a broader scale. This study will be beneficial to improve mitigation strategies, emergency response plans, and ensuring that emergency services and facilities are available in the event of future floods for the affected areas
Essays on the performance, disclosure, and corporate governance of Islamic banks
No full textIn this study, I empirically investigate relative efficiency, accounting conservatism, and corporate governance in Islamic banking. It is crucial for Islamic banks to be efficient in order to withstand competitive pressures and financial crisis. Academic evidence, however, from Islamic banking studies is inconclusive on the question of whether Islamic banks are more or less efficient than their conventional counterparts. There is also doubt on the relevance of conservatism concept to financial reporting practices of Islamic banking because of Zakah (Islamic tax). Moreover, the institution of Shariah supervisory board (SSB) as an additional layer of governance in Islamic banks plays an important role in affecting bank risk-taking. The first essay empirically examines the relative efficiency of Islamic banks compared to conventional banks using a sample of Islamic and conventional banks from the Bankscope database. I define efficiency as the level of capital buffer banks would maintain for any given level of asset risk. Due to profit and loss sharing (PLS) scheme that dominates the deposit side of Islamic banks, majority of the depositors are equity-like holders whose returns depend on bank performance (Archer and Karim, 2009). Therefore, I hypothesize that Islamic banks would maintain lower capital reserves, for any given level of asset risk, compared to their conventional counterparts. However, I find that Islamic banks hold more capital and reserves, for a given level of asset risk, which suggest that Islamic banks are less efficient than their conventional counterparts. I find that Islamic banks that engage more in Islamic mode of finance and are highly funded by PLS contracts are less efficient than Islamic banks that engage less in such contracts. In further cross-sectional tests, I find that smaller Islamic banks are significantly less efficient than larger Islamic banks due to the absence of risk diversification tools in small banks, and that Islamic banks tend to be less efficient before and after the financial crisis of 2007-2008. The second essay explores the nature of Islamic banks’ financial reporting incentives created by Shariah with respect to accounting conservatism. Adherence to Shariah rules, Islamic bank, as a separate entity, is obligated to pay Islamic tax or Zakah in order to maintain social justice and alleviate poverty. This indicates that the financial reporting of Islamic banks would be influenced by such obligation. Many Islamic accounting scholars cast doubt on the relevance of conservatism concept. Some scholars claim that the conservatism concept is not relevant for Islamic accounting reporting because it leads to understating assets that could be subject to Zakah (Adnan et. al. 1997). Others argue, however, that what is meant in Islamic accounting by conservatism concept is the selection of the accounting techniques that has the most favorable impact on society not the owner. For instance, it is better to overestimate funds “anti-conservative” for Zakah purposes (Haniffa and Hudaib, 2001). I posit that Islamic banks apply an anti-conservatism practices in financial reporting to be consistent with Shariah rules. Using Basu (1997) and Ball and Shivakumar (2005) models, I find that Islamic banks recognize earnings decrease on timely bases while recognize earnings increase with delay. This would suggest that Islamic banks take the same accounting conservatism approach as conventional banks and Shariah does not play significant roles in term of financial reporting. In addition, I find that Islamic banks report more conservatively than conventional banks due to additional obligation of Zakah payment and higher litigation risk exposed to the Islamic banks. Prior literature argues that board’ characteristics paly an important roles in influencing bank risk-taking (Jensen, 1993; Yermack, 1996; Pathan, 2009). In third essay, I examine whether the board structure of Islamic bank, in particular Shariah supervisory board (SSB), influence risk-taking behaviors. Under Shariah rules, Islamic banks are expected to engage in less risk-taking investments. Focusing on board’s characteristics that mostly examined in the literature, I find that large SSB is positively associated with bank risk-taking. The result is consistent with Pathan (2009) that larger number of directors in the board is less effective in monitoring bank activities due to coordination and free-riding problems. Consistent with Shivdasani and Yermack (1999), Christy et al (2009), and Falato et al. (2014), I also find that scholars with multiple memberships, or busy members, in SSB are positively associated with bank risk. Scholars with multiple seats are too busy to mind the business and unable to provide meaningful managerial monitoring. Moreover, the results show that foreign scholars are more effective in monitoring banks’ Shariah compliance as they provide expertise and independent monitoring over management, which in turn enhance firm value (Oxelheim, and Randoy, 2003; Chi, Sul, and Min, 2012). Further analysis provides some evidence that most of the findings on the association between SSB structure and bank risk are derived from countries in the Gulf Corporation Council (GCC) where Shariah governance is ruled internally at bank level, and such associations are more pronounced after the global financial crisis. This study sheds light on current practices of Islamic governance and emphasizes the need for well-functioning Shariah board that works with board of directors and management to better realize the goals of Islamic banks in practice.Ph.D.Includes bibliographical referencesby Amal AlAbba
The dissemination of multidrug-resistant and hypervirulent <em>Klebsiella pneumoniae</em> clones across the Kingdom of Saudi Arabia
No full text\ua9 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd.Klebsiella pneumoniae is a Gram-negative bacterium associated with a wide range of community- and hospital-acquired infections. The emergence of clonal hypervirulent strains resistant to last-resort antimicrobial agents has become a global concern. The Kingdom of Saudi Arabia (KSA), with its diverse population and high tourism traffic, serves as a platform where the spread of multidrug-resistant (MDR) strains are facilitated. However, the knowledge of epidemiology and population diversity of MDR K. pneumoniae in KSA is scarce. We conducted a comprehensive genomic survey on 352 MDR K. pneumoniae isolates systematically collected from bloodstream and urinary tract infections in 34 hospitals across 15 major cities in KSA during 2022 and 2023. Whole-genome sequencing on the isolates was performed, followed by genomic epidemiology and phylodynamic analysis. Our study revealed a dynamic population characterized by the rapid expansion of several dominant clones, including, ST2096, ST147, and ST231, which were estimated to have emerged within the past decade. These clones exhibited widespread dissemination across hospitals and were genetically linked to global strains, particularly from the Middle East and South Asia. All major clones harboured plasmid-borne ESBLs and carbapenemase genes, with plasmidome analysis identifying multiple IncH, IncA/C and IncL plasmids underlying the MDR-hypervirulent phenotype. These plasmids were shared between major clones and became acquired on the same time scales as the expansion of the dominant clones. Our results report ST2096 as an emerging MDR-hypervirulent clone, emphasizing the need for monitoring of the circulating clones and their plasmid content in the KSA and broader West Asia
An experimental and chemical kinetic modeling study of 1,3-butadiene combustion: Ignition delay time and laminar flame speed measurements
No full textIgnition delay times for 1,3-butadiene oxidation were measured in five different shock tubes and in a rapid compression machine (RCM) at thermodynamic conditions relevant to practical combustors. The ignition delay times were measured at equivalence ratios of 0.5, 1.0, and 2.0 in ‘air’ at pressures of 10, 20 and 40 atm in both the shock tubes and in the RCM. Additional measurements were made at equivalence ratios of 0.3, 0.5, 1.0 and 2.0 in argon, at pressures of 1, 2 and 4 atm in a number of different shock tubes. Laminar flame speeds were measured at unburnt temperatures of 295 K, 359 K and 399 K at atmospheric pressure in the equivalence ratio range of 0.6–1.7, and at a pressure of 5 atm at equivalence ratios in the range 0.6–1.4. These experimental data were then used as validation targets for a newly developed detailed chemical kinetic mechanism for 1,3-butadiene oxidation.
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\nA detailed chemical kinetic mechanism (AramcoMech 3.0) has been developed to describe the combustion of 1,3-butadiene and is validated by a comparison of simulation results to the new experimental measurements. Important reaction classes highlighted via sensitivity analyses at different temperatures include: (a) ȮH radical addition to the double bonds on 1,3-butadiene and their subsequent reactions. The branching ratio for addition to the terminal and central double bonds is important in determining the reactivity at low-temperatures. The alcohol-alkene radical adducts that are subsequently formed can either react with HȮ2 radicals in the case of the resonantly stabilized radicals or O2 for other radicals. (b) HȮ2 radical addition to the double bonds in 1,3-butadiene and their subsequent reactions. This reaction class is very important in determining the fuel reactivity at low and intermediate temperatures (600–900 K). Four possible addition reactions have been considered. (c) 3Ö atom addition to the double bonds in 1,3-butadiene is very important in determining fuel reactivity at intermediate to high temperatures (> 800 K). In this reaction class, the formation of two stable molecules, namely CH2O + allene, inhibits reactivity whereas the formation of two radicals, namely Ċ2H3 and ĊH2CHO, promotes reactivity. (d) Ḣ atom addition to the double bonds in 1,3-butadiene is very important in the prediction of laminar flame speeds. The formation of ethylene and a vinyl radical promotes reactivity and it is competitive with H-atom abstraction by Ḣ atoms from 1,3-butadiene to form the resonantly stabilized Ċ4H5-i radical and H2 which inhibits reactivity. Ab initio chemical kinetics calculations were carried out to determine the thermochemistry properties and rate constants for some of the important species and reactions involved in the model development. The present model is a decent first model that captures most of the high-temperature IDTs and flame speeds quite well, but there is room for considerable improvement especially for the lower temperature chemistry before a robust model is developed.The work at NUI Galway was supported by Saudi Aramco under the FUELCOM program. Chong-Wen Zhou also thanks the support from Beihang University, China. Computational resources were provided by the Irish Centre for High-End Computing, ICHEC. Ultan Burke sincerely thanks Science Foundation Ireland, (SFI) under Grant number [08/IN1./I2055] for funding this project. The work at TAMU was funded in part by the Texas A&M Engineering Experiment Station, the Texas A&M University at Qatar, and the Mary Kay O'Connor Process Safety Center. Research at KAUST was supported by funding from Saudi Aramco under the FUELCOM program. The work at XJTU was supported by the National Natural Science Foundation of China (No. 91541115). Research at UCF was based upon work supported partially by the National Science Foundation Graduate Research Fellowship Program under Grant no. 1144246, Donors of the American Chemical Society Petroleum Research Fund, and the Defense Threat Reduction Agency (grant number: HDTRA1-16-1-0009). J. L. acknowledges funding provided by the National Aeronautics and Space Administration Florida Space Grant Consortium. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the United States Government
An experimental and chemical kinetic modeling study of 1,3-butadiene combustion: Ignition delay time and laminar flame speed measurements
No full textIgnition delay times for 1,3-butadiene oxidation were measured in five different shock tubes and in a rapid compression machine (RCM) at thermodynamic conditions relevant to practical combustors. The ignition delay times were measured at equivalence ratios of 0.5, 1.0, and 2.0 in \u27air\u27 at pressures of 10, 20 and 40 atm in both the shock tubes and in the RCM. Additional measurements were made at equivalence ratios of 0.3, 0.5, 1.0 and 2.0 in argon, at pressures of 1, 2 and 4 atm in a number of different shock tubes. Laminar flame speeds were measured at unburnt temperatures of 295 K, 359 K and 399 K at atmospheric pressure in the equivalence ratio range of 0.6-1.7, and at a pressure of 5 atm at equivalence ratios in the range 0.6-1.4. These experimental data were then used as validation targets for a newly developed detailed chemical kinetic mechanism for 1,3-butadiene oxidation.A detailed chemical kinetic mechanism (AramcoMech 3.0) has been developed to describe the combustion of 1,3-butadiene and is validated by a comparison of simulation results to the new experimental measurements. Important reaction classes highlighted via sensitivity analyses at different temperatures include: (a) (O) over dotH radical addition to the double bonds on 1,3-butadiene and their subsequent reactions. The branching ratio for addition to the terminal and central double bonds is important in determining the reactivity at low-temperatures. The alcohol-alkene radical adducts that are subsequently formed can either react with HO2 radicals in the case of the resonantly stabilized radicals or O-2 for other radicals. (b) H(O) over dot(2) radical addition to the double bonds in 1,3-butadiene and their subsequent reactions. This reaction class is very important in determining the fuel reactivity at low and intermediate temperatures (600-900 K). Four possible addition reactions have been considered. (c) O-3 atom addition to the double bonds in 1,3-butadiene is very important in determining fuel reactivity at intermediate to high temperatures (> 800 K). In this reaction class, the formation of two stable molecules, namely CH2O + allene, inhibits reactivity whereas the formation of two radicals, namely C2H3 and CH2CHO, promotes reactivity. (d) H atom addition to the double bonds in 1,3-butadiene is very important in the prediction of laminar flame speeds. The formation of ethylene and a vinyl radical promotes reactivity and it is competitive with H atom abstraction by H atoms from 1,3-butadiene to form the resonantly stabilized C4H5-i radical and H-2 which inhibits reactivity. Ab initio chemical kinetics calculations were carried out to determine the thermochemistry properties and rate constants for some of the important species and reactions involved in the model development. The present model is a decent first model that captures most of the high-temperature IDTs and flame speeds quite well, but there is room for considerable improvement especially for the lower temperature chemistry before a robust model is developed. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.The work at NUI Galway was supported by Saudi Aramco under the FUELCOM program. Chong-Wen Zhou also thanks the support from Beihang University, China. Computational resources were provided by the Irish Centre for High-End Computing, ICHEC. Ultan Burke sincerely thanks Science Foundation Ireland, (SFI) under Grant number [08/IN1./I2055] for funding this project. The work at TAMU was funded in part by the Texas A&M Engineering Experiment Station, the Texas A&M University at Qatar, and the Mary Kay O\u27Connor Process Safety Center. Research at KAUST was supported by funding from Saudi Aramco under the FUELCOM program. The work at XJTU was supported by the National Natural Science Foundation of China (No. 91541115). Research at UCF was based upon work supported partially by the National Science Foundation Graduate Research Fellowship Program under Grant no. 1144246, Donors of the American Chemical Society Petroleum Research Fund, and the Defense Threat Reduction Agency (grant number: HDTRA1-16-1-0009). J. L. acknowledges funding provided by the National Aeronautics and Space Administration Florida Space Grant Consortium. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the United States Government.2020-09-1
SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study
No full textBackground: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling.
Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty.
Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year.
Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population
