Thymol synthesis by acid catalysed isopropylation of m-cresol

Includes bibliographical references.The initial motivation for this study was to identify a suitable window of operation for thymol synthesis from iso-propanol and m-cresol mediated by a commercially available H-MFI zeolite catalyst. A preliminary investigation uncovered seeming anomalies in the course of the synthesis process, in particular counterintuitive trends with respect to m-cresol conversion and thymol selectivity at low space velocity. Consequently, the study sought to establish the reaction pathway responsible for these observations in an attempt to gain an understnding for future thymol yield optimisation studies. Under the reaction conditions studied, complete dehydration of iso-propanol was observed. Further reaction of the propene to olefinic species with carbon numbers higher than 3 was also seen. Results showed that the cause of the so-called “volcano curve” in respect of m-cresol conversion was found in the system’s propensity for the formation of cresylic rings which were alkylated with side chains consisting of carbon atoms between 4-8, particularly under severe reaction conditions. This fraction was formed via the alkylation of the m-cresol with the said olefinic pool. The thymol synthesis system was also found to be thermodynamically limited at high reaction temperature and low space velocit

Is the Adams D-15 colour vision test a sensitive screening tool for ethambutol- and linezolid-induced optic neuropathy? A retrospective case series

Background: Ethambutol hydrochloride and linezolid are commonly used anti-tuberculous agents. Both agents can cause potentially blinding toxic optic neuropathy. Currently there is no low-cost, sensitive screening tool to detect early toxicity before permanent vision loss has occurred. Purpose: To evaluate the ability of the Adams D-15 colour vision test to detect early ethambutol- and linezolid-induced optic neuropathy. Methods: This was a retrospective case series of 15 patients who were screened for ethambutol- and linezolid-induced toxic optic neuropathy. At screening and follow-up visits, a detailed clinical history was taken, a standard of care examination performed and a battery of side-room investigations conducted, including: Farnsworth Munsell D15 (FM D15) and Adams D15 colour vision tests, retinal nerve fiber layer optical coherence tomography (RNFL-OCT) and a Humphrey visual field 24-2 (HVF 24-2). According to the results of these tests, the patients were classified into 3 groups: “No toxicity”, “Uncertain toxicity” or “Confirmed toxicity”. Results: Six patients were classified as “No toxicity”, 3 were “Uncertain toxicity” and 6 were classified as “Confirmed toxicity”. The Adams D15 showed a sensitivity of 100% for detecting a toxic optic neuropathy. Conclusion: The Adams D15 is a sensitive screening tool for the detection of early ethambutol- and linezolid-induced optic neuropathy

FlexRDZ: Autonomous Mobility Management for Radio Dynamic Zones

FlexRDZ is an online, autonomous manager for radio dynamic zones (RDZ) that seeks to enable the safe operation of RDZs through real-time control of deployed test transmitters. FlexRDZ leverages Hierarchical Task Networks and digital twin modeling to plan and resolve RDZ violations in near real-time. We prototype FlexRDZ with GTPyhop and the Terrain Integrated Rough Earth Model (TIREM). We deploy and evaluate FlexRDZ within a simulated version of the Salt Lake City POWDER testbed, a potential urban RDZ environment. Our simulations show that FlexRDZ enables up to a 20 dBm reduction in mobile interference and a significant reduction in the total power of leaked transmissions while preserving the overall communication capabilities and uptime of test transmitters. To our knowledge, FlexRDZ is the first autonomous system for RDZ management.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Objek-georiënteerde en rolgebaseerde verspreide inligtingsekerheid in 'n oop transaksieverwerking omgewing

M.Sc. (Computer Science)Information is a valuable resource in any organisation and more and more organisations are realising this and want efficient means to protect it against disclosure, modification or destruction. Although relatively efficient security methods have been available almost as long as information databases, they all provide additional cost. This cost does not only involve money but also cost in terms of system performance and management of information security. Any new information security model must also provide better management of information security. In this dissertation we present a model that provides information security and aims to lower the technical skills required to manage information security using this approach. In any business organisation we can describe each employee's duties. Put in other words, we can say that each employee has a specific business role in the organisation. In organisations with many employees there are typically many employees that have more or less the same duties in the organisation. This means that employees can be grouped according to their business roles. We use an employee's role as a description of his/her duties in a business organisation. ' Each role needs resources to perform its duties in the organisation. In terms of computer systems, each role needs computer resources such as printers. Most roles need access to data files in the organisation's database but it is not desirable to give all roles access to all data files. It is obvious that roles have specific privileges and restrictions in terms of information resources. Information security can be achieved by identifying the business roles in an organisation and giving these roles only the privileges needed to fulfill their business function and then assigning these roles to people (users of the organisation's computer system). This is called role-based security. People's business functions are related, for example clerks and clerk-managers are related in the sense that a clerk-manager is a manager of clerks. Business roles are related in the same way. For an information security manager to assign roles to users it is important to see this relationship between roles. In this dissertation we present this relationship using a lattice graph which we call a role lattice. The main advantage of this is that it is eases information security management..

Modelling silver transport in spherical HTR fuel

For direct cycle gas cooled high temperature reactor designs, operating conditions may be limited as a result of excessive maintenance dose rates caused by the 110mAg source term on the turbine. The accurate prediction of silver fission and activation products’ release during normal operation is required to ensure regulatory compliance and economic viability of planned power plants. Fuel qualification programs should provide satisfactory results to ensure correct analyses, but will however not be available for many years. In the meantime data from the German fuel development program may be utilized. Traditionally diffusion models were used to derive transport parameters from limited irradiation testing of fuel materials and components. Best estimates for all applicable German fuel irradiation tests with defendable uncertainty ranges were never derived. However, diffusion theory and current parameters cannot account for all irradiation and heat-up test results, and for some tests, it appears unacceptably conservative. Other transport mechanisms have been suggested and alternative calculation models are being considered. In this thesis the relevant German material and irradiation tests were evaluated with the current PBMR metallic fission product release calculation model. Transport through all the fuel materials and components and from the sphere to the coolant gas was considered and best possible models and parameters were suggested. For the transport of silver through the SiC layer an alternative suggested model called the Molecular Vapour Transport Release (MVR) Model was evaluated against the traditional diffusion model. From this evaluation it was shown that classical diffusion modelling was still a viable model to predict silver transport in SiC. The MVR model was found to be a feasible model as well. However, due to the much larger verification and validation effort required, it was decided to use the diffusion model until such time that experimental results become available that might elucidate the exact physical transport model. The evaluation also showed that the diffusion model used must be quantified in a detailed evaluation of all applicable irradiation tests. A study of all German irradiation tests was previously performed and the applicable irradiation tests were identified. A detailed evaluation of these irradiation tests were performed with an updated diffusion model. New transport and material parameters were derived in this detailed evaluation and compared with existing values. An evaluation of some heat-up tests of irradiated fuel spheres was performed to assess the range for which the newly derived transport parameters are valid. The different models with their old and newly derived parameters were used to analyse sample PBMR cores. Recommendations were made to the suitability of the different models and parameters for future PBMR silver fission and activation product analyses.Thesis (DPhil)--University of Pretoria, 2009.Physicsunrestricte

An analysis of the relationship between security risk management and business continuity management : a case study of the United Nations Funds and Programmes

Text in EnglishThe goal of this research was to investigate the relationship between security risk management and business continuity management and to determine how these two methodologies are applied within United Nations Funds and Programmes. These United Nations (UN) agencies have been established to deliver humanitarian aid, economic and social development and reconstruction activities. The locations where these services are required are typically where security risks are also most prevalent. The staff of the UN, the International Red Cross and other humanitarian and development organisations have traditionally been treated as neutral parties and have not been targeted by belligerent groups. This study revealed that there has been an annual increase in security incidents against aid workers and employees of UN organisations. The changing security landscape worldwide and the increasing demand for aid and development services in especially fragile and post-conflict environments, require organisations working in these areas to maintain a high level of resilience. Their resilience can be strengthened by applying robust security risk and business continuity management methodologies. The study included an examination of the global risk environment as it pertains to UN agencies, as well as key risk management concepts such as risk management, operational risk management, security risk management, business continuity management and organisational resilience. For the purposes of this study, security risk management is defined as the systematic approach to assessing and acting on security risks, while ensuring the safety and security of the organisation's personnel and facilities and ensuring that organisational objectives are achieved. Business continuity is a management process that identifies potential threats to an organisation, it assesses the impact to business operations − should the threats materialise − and it furthermore assists in the development of strategies to continue operations in the event of a disruption. In addition to looking at these concepts individually, the relationship between security risk management and business continuity management was also reviewed. The specific objectives set out to achieve the goal of the study were the following: Explore the perceptions of UN agencies about the link between security risk management and business continuity management. Analyse the extent of integration between security risk management and business continuity management processes and oversight. Make recommendations as to how security risk management and business continuity management can operate in an integrated manner with the goal of increasing the overall resilience of UN agencies. To answer the research questions a qualitative research approach was adopted. This enabled the researcher to collect data through interviewing participants and analysing their feedback. The research focused on UN Funds and Programmes as a sub-set of agencies within the UN family of organisations. Each one of these agencies has a specific mandate, such as providing assistance to refugees, promoting food security, poverty reduction, improving reproductive health and family planning services. They also operate in fragile states as well as in emergency and humanitarian crises situations where the security risks are often higher than in normal developing countries. Eight out of 12 UN Funds and Programmes agreed to participate in the study, including: United Nations Children's Fund; United Nations Relief and Works Agency for Palestine Refugees in the Near East; Office of the United Nations High Commissioner for Refugees; World Food Programme; United Nations Development Programme; United Nations Office on Drugs and Crime; United Nations Human Settlements Programme; and UN Women. Data were collected through conducting semi-structured telephone interviews with the security manager and/or business continuity manager serving in the headquarters of each participating organisation. Findings from the study indicated that security risk management within the UN system has evolved and that security has matured from a purely protective and defensive posture to following a risk management approach. The strength of the UN Security Management System lies in its Security Risk Management Model, which enables a thorough assessment of security risks and the implementation of commensurate mitigating security measures. In contrast to security risk management, the study revealed that business continuity as a management process is a fairly new initiative and has not yet been comprehensively adopted by all UN agencies. When combined, security risk management and business continuity management ensure the safety of staff, maximise the defence of the agencies’ reputation, minimise the impact of events on the agencies as well as their beneficiaries, protect the organisation’s assets, and very importantly, demonstrate effective governance. This can only be done through establishing an organisational risk management model by positioning security risk management and business continuity management within the UN agency’s organisational structure so that they can effectively work together and at the same time allow access to senior management. Good practices and apparent gaps were identified in how these two methodologies are implemented and five specific recommendations were made. The research confirmed the need for both security risk management and business continuity management and the role each function plays to enhance an organisation’s resilience. It also highlighted that while they are two separate management functions, both need to be implemented within a larger risk management framework and need to be closely aligned in order to be effective. The five recommendations are: Incorporate security risk management and business continuity management functions and responsibilities into the larger agency-wide risk management governance framework. Expand the scope of business continuity in those UN agencies where it currently sits in the domain of information technology or has not yet been comprehensively implemented across the organisation. Establish a comprehensive crisis management framework spanning across the whole organisation from their headquarters to country offices. Develop the capacity to gather risk data across their agency and aggregate the data to view the full spectrum of risks, including security risks and business continuity risks in a holistic manner. Integrate security risk management and business continuity management processes to enhance their effectiveness. This study contributes to the existing body of knowledge in the field of risk management by gathering relevant information from participating UN Funds and Programmes, comparing the information with other academic sources and drawing conclusions to answer the research questions. While it is expected that each organisation will have its own view on how to implement security risk management and business continuity management, the findings and recommendations as a result of the study present a series of practical recommendations on how the two functions can operate in an integrated manner in order to increase the overall resilience of these UN agencies. Other non-UN organisations working in similar high risk environments could also benefit from the outcomes of the study, as it would allow them to compare their own approaches to security risk management and business continuity management with the information presented in this study.Security Risk ManagementM. Tech. (Security Management

Pentateuchtradisies in die prediking van Deuterojesaja

Our investigation of the background of the different allusions to the Pentateuchatlr aditions in Is. 40-55 and their bearing on the teaching of Deutero-Isaiah rendered as result that Deutero-Isaiah used these traditions in absolute freedom. .... Zie: Conclusio

The relationship between barchan size and barchan morphology : a case study from Northern Namibia

Landform allometry has been a topic of inquiry since at least the 1970s. In this study, the presence of allometry is investigated for a barchan dunefield in northern Namibia. Using a combination of traditional morphometric parameters and techniques borrowed from geometric morphometrics it is shown that barchan allometry is present. This allometry is a combination of positive and negative allometry. Barchans show a definite change in mean shape as the size of the dune increases becoming more asymmetric. Differences in horn length, along with dune width, show positive allometry indicating that it changes faster than the shape changes. Barchan bilateral asymmetry and stoss length show negative allometry indicating that changes in these variables lag behind changes in size. Together, these results hint at the possible presence of threshold size differences beyond which distinct shape changes can be observed.http://www.tandfonline.com/loi/rsag20hj2022Geography, Geoinformatics and Meteorolog