This thesis describes the evaluation of four operating systems for microcomputers. The emphasis of the study is on the suitability of the operating systems for use in real-time applications, such as process control. The evaluation was performed in two sections. The first section was a quantitative assessment of the performance of the real-time features of the operating system. This was performed using benchmarks. The criteria for the benchmarks and their design are discussed. The second section was a qualitative assessment of the suitability of the operating systems for the development and implementation of real-time systems. This was assessed through the implementation of a small simulation of a manufacturing process and its associated control system. The simulation was designed using the Ward and Mellor real-time design method which was extended to handle the special case of a real-time simulation. The operating systems which were selected for the study covered a spectrum from general purpose operating systems to small, specialised real-time operating systems. From the quantitative assessment it emerged that QNX (from Quantum Software Systems) had the best overall performance. Qualitatively, UNIX was found to offer the best system development environment, but it does not have the performance and the characteristics required for real-time applications. This suggests that versions of UNIX that are adapted for real-time applications are worth careful consideration for use both as development systems and implementation systems.

Continuing advances in hardware and in software applications are pushing traditional operating systems beyond their limits. This is largely due to the fact that these advances, and their associated requirements, were not foreseen at operating system design time. This becomes particularly apparent with multimedia applications, whose demands for guaranteed quality of service differ considerably from those of most traditional applications. To ensure that many future requirements will be met, along with many existing demands, one solution is to allow applications to customize their operating system throughout its life-time. However, opening up an operating system to application-initiated changes can compromise the integrity of the system, suggesting the need for a security model. Like any other aspect of a customizable system, such a security model should be securely customizable, too. Therefore, this dissertation introduces MetaOS, a securely- and dynamically-customizable operating system which has a securely- and dynamically-customizable security model. MetaOS employs four types of building blocks: meta-levels, meta-spaces, meta-objects, and meta-interfaces. Meta-levels localize customizable system services. Meta-spaces act as firewalls which prevent custom alterations from affecting unrelated meta-spaces and their applications. Meta-objects help to modularize meta-spaces into smaller, easier-to-maintain components. Finally, meta-interfaces provide the heart of the secure customizing model. MetaOS meta-interfaces are strictly divided into declarative and imperative interfaces, providing a basis on which to distinguish between calls which only affect the invoking application (i.e., local-effect calls), and calls which could affect other applications as well (i.e., meta-space-wide-effect calls). By giving free access to the former, but limiting access to the latter, a basic balance between flexibility and security can be struck. Additional flexibility is achieved by allowing new local and meta-space-wide-effect calls to be added dynamically, by permitting untrusted applications to negotiate changes with trusted meta-space managers, and by allowing untrusted applications to migrate to cloned meta-spaces and alter them as necessary. / Graduate

Fine needle aspiration (FNA) in the operating room is a convenient optional diagnostic approach. Our objective of this study was to evaluate the accuracy and study the potential benefits of fine needle aspiration in the operating room. Retrospective review of all intraoperative FNA that were requested and performed by pathologists over 20-month period was carried out. Immediate smears were interpreted by the cytopathology team after staining with Diff Quik stain. All cases were reviewed and correlation with subsequent tissue diagnosis was done. Accuracy was calculated and potential benefits were discussed. The number of aspirates was 32. Adequate material for immediate and final interpretation was achieved in 31 cases (sensitivity 97%). In 20 cases (63%), malignancy was diagnosed while a benign diagnosis was rendered in 12 (37%). All cases had a follow up tissue diagnosis. No false-positive cases were identified (specificity 100%). The information gained from this approach was considered helpful to the surgeons. We concluded that FNA of head and neck masses in the operating room is an accurate and sensitive diagnostic approach. The service provides helpful information to surgeons and is an additional optional diagnostic approach.

A Dissertation submitted to the Faculty of Health Science, University of the Witwatersrand, in fulfillment of the requirements of the degree of Master of Science in Nursing Education Johannesburg, June 2017 / Multi-resistant organisms, the involvement of numerous stakeholders in the OR as well as the complex procedural and technical advancements, especially in the private healthcare environment, justifies an evidence based infection prevention quality audit tool for an OR that is comprehensive. The purpose of the study was to develop a comprehensive infection prevention quality audit tool for operating room within a private healthcare environment. A three phased, multi-method study was conducted whereby phase one included the identification of statements in existing audit tools, policies and published articles. This was used to compile concourse statements that were used during phase 2 in the Q-sort data collection method, which allowed stakeholders (scrub- and anaesthetic nurses, CSD Managers, IPC- and OHS Coordinators and surgeons) to indicate what they want to be included in the IPC Audit Tool for operating room. A statement verification was conducted to expand the concepts that enabled the researcher to compile an audit tool. Subject experts and the researcher tested the degree of validity of the audit tool in phase three of the study. A descriptive analysis revealed that the results of the Q-sort event was inconclusive. The subject experts were unable to determine the degree of validity of the audit tool, which forced the researcher to test the audit tool in an OR. A Comprehensive IPC Control Quality Audit Tool was developed. The utilisation of the audit tool in an OR should be a well-planned event. Specific education and training of the multidisciplinary team regarding IPC in the OR should be considered. / MT2017

No description available.

Address space layout randomization (ASLR) is a technique employed to prevent exploitation of memory corruption vulnerabilities in user-space programs. While this technique is widely studied, its kernel space counterpart known as kernel address space layout randomization (KASLR) has received less attention in the research community. KASLR, as it is implemented today is limited in entropy of randomization. Specifically, the kernel image and its modules can only be randomized within a narrow 1GB range. Moreover, KASLR does not protect against memory disclosure vulnerabilities, the presence of which reduces or completely eliminates the benefits of KASLR. In this thesis, we make two major contributions. First, we add support for position-independent kernel modules to Linux so that the modules can be placed anywhere in the 64-bit virtual address space and at any distance apart from each other. Second, we enable continuous KASLR re-randomization for Linux kernel modules by leveraging the position-independent model. Both contributions increase the entropy and reduce the chance of successful ROP attacks. Since prior art tackles only user-space programs, we also solve a number of challenges unique to the kernel code. Our experimental evaluation shows that the overhead of position-independent code is very low. Likewise, the cost of re-randomization is also small even at very high re-randomization frequencies. / Master of Science / Address space layout randomization (ASLR) is a computer security technique used to prevent attacks that exploit memory disclosure and corruption vulnerabilities. ASLR works by randomly arranging the locations of key areas of a process such as the stack, heap, shared libraries and base address of the executable in the address space. This prevents an attacker from jumping to vulnerable code in memory and thus making it hard to launch control flow hijacking and code reuse attacks. ASLR makes it impossible for the attacker to leverage return-oriented programming (ROP) by pre-computing the location of code gadgets. Unfortunately, ASLR can be defeated by using memory disclosure vulnerabilities to unravel static randomization in an attack known as Just-In-Time ROP (JIT-ROP) attack. There exist techniques that extend the idea of ASLR by continually re-randomizing the program at run-time. With re-randomization, any leaked memory location is quickly obsoleted by rapidly and continuously rearranging memory. If the period of re-randomization is kept shorter than the time it takes for an attacker to create and launch their attack, then JIT-ROP attacks can be prevented. Unfortunately, there exists no continuous re-randomization implementation for the Linux kernel. To make matters worse, the ASLR implementation for the Linux kernel (KASLR) is limited. Specifically, for x86-64 CPUs, due to architectural restrictions, the Linux kernel is loaded in a narrow 1GB region of the memory. Likewise, all the kernel modules are loaded within the 1GB range of the kernel image. Due to this relatively low entropy, the Linux kernel is vulnerable to brute-force ROP attacks. In this thesis, we make two major contributions. First, we add support for position-independent kernel modules to Linux so that the modules can be placed anywhere in the 64-bit virtual address space and at any distance apart from each other. Second, we enable continuous KASLR re-randomization for Linux kernel modules by leveraging the position-independent model. Both contributions increase the entropy and reduce the chance of successful ROP attacks. Since prior art tackles only user-space programs, we also solve a number of challenges unique to the kernel code. We demonstrate the mechanism and the generality of our proposed re-randomization technique using several different, widely used device drivers, compiled as re-randomizable modules. Our experimental evaluation shows that the overhead of position-independent code is very low. Likewise, the cost of re-randomization is also small even at very high re-randomization frequencies.

Thesis (M.H.A.)--University of Michigan, 1974.

Thesis (M.H.A.)--University of Michigan, 1974.

Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2008.

Sharps injuries can transmit fatal blood-borne infections to injured health care workers. These blood-borne infections have serious consequences, including long-term illness, disability and death. The operating room is a fast-paced, hazardous working environment, where personnel are constantly exposed to sharps injuries. The psychological aspects of these injuries have received little attention. The emotional impact of a sharps injury can be severe and long lasting, even when a serious infection is not transmitted. Furthermore, according to literature, the mean rates of underreporting sharps injuries vary between twenty two and seventy five percent. The research objectives of this qualitative, explorative and descriptive study were to explore and describe the experiences of operating room personnel in the southern district of the North-West province in South Africa after sharps injuries, to explore and describe the reasons why they do not always report these incidents, to explore and describe what could be done to increase reporting of sharps incidents in operating rooms by personnel and to propose guidelines to support operating room personnel after a sharps injury. In order to achieve these objectives, the researcher gathered data by conducting semi-structured interviews with operating room personnel who had experienced sharps injuries in hospitals of the southern districts of the North-West in South Africa. Ethical considerations were adhered to by the researcher. Permission to conduct research was negotiated by the researcher with management of the hospitals in the target area. Voluntary, informed consent in writing was obtained from all participants before interviews were conducted. Data saturation was reached after 17 interviews were conducted with participants. Data were analysed with the help of an experienced co-coder. The researcher and co-coder reached consensus during a meeting organised for the purpose. Then the data were related to relevant literature. Seven categories emerged from the data analysis: Mechanisms of sharps injuries in the operating room, practical measures taken after a sharps injury, reasons for not reporting all sharps injuries, emotions experienced after a sharps injury, impact of sharps injuries on relationships, the support received by participants after a sharps injury and their coping mechanisms after a sharps injury. Several conclusions were drawn by the researcher from the data. Although all hospitals in this study had a reporting system in place, operating room personnel participating in this study did not report all their sharps injuries. They received no or insufficient support from hospital management after a sharps injury. No or insufficient communication existed between hospital management and participants in this study after these incidents. From these findings the researcher proposed guidelines for support to operating room personnel after sharps injuries and to increase the reporting of these incidents. The researcher also compiled recommendations for nursing practice, nursing education and nursing research in the operating room. / Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2008.