The work described in this thesis is the result of aresearch program started in 1981 to find better ways ofprogramming Telecom applications. These applications are largeprograms which despite careful testing will probably containmany errors when the program is put into service. We assumethat such programs do contain errors, and investigate methodsfor building reliable systems despite such errors. The research has resulted in the development of a newprogramming language (called Erlang), together with a designmethodology, and set of libraries for building robust systems(called OTP). At the time of writing the technology describedhere is used in a number of major Ericsson, and Nortelproducts. A number of small companies have also been formedwhich exploit the technology. The central problem addressed by this thesis is the problemof constructing reliablesystems from programs which maythemselves contain errors. Constructing such systems imposes anumber of requirements on any programming language that is tobe used for the construction. I discuss these languagerequirements, and show how they are satisfied by Erlang. Problems can be solved in a programming language, or in thestandard libraries which accompany the language. I argue howcertain of the requirements necessary to build a fault-tolerantsystem are solved in the language, and others are solved in thestandard libraries. Together these form a basis for buildingfault-tolerant software systems. No theory is complete without proof that the ideas work inpractice. To demonstrate that these ideas work in practice Ipresent a number of case studies of large commerciallysuccessful products which use this technology. At the time ofwriting the largest of these projects is a major Ericssonproduct, having over a million lines of Erlang code. Thisproduct (the AXD301) is thought to be one of the most reliableproducts ever made by Ericsson. Finally, I ask if the goal of finding better ways to programTelecom applications was fulfilled --- I also point to areaswhere I think the system could be improved.

<p>The work described in this thesis is the result of aresearch program started in 1981 to find better ways ofprogramming Telecom applications. These applications are largeprograms which despite careful testing will probably containmany errors when the program is put into service. We assumethat such programs do contain errors, and investigate methodsfor building reliable systems despite such errors.</p><p>The research has resulted in the development of a newprogramming language (called Erlang), together with a designmethodology, and set of libraries for building robust systems(called OTP). At the time of writing the technology describedhere is used in a number of major Ericsson, and Nortelproducts. A number of small companies have also been formedwhich exploit the technology.</p><p>The central problem addressed by this thesis is the problemof constructing reliablesystems from programs which maythemselves contain errors. Constructing such systems imposes anumber of requirements on any programming language that is tobe used for the construction. I discuss these languagerequirements, and show how they are satisfied by Erlang.</p><p>Problems can be solved in a programming language, or in thestandard libraries which accompany the language. I argue howcertain of the requirements necessary to build a fault-tolerantsystem are solved in the language, and others are solved in thestandard libraries. Together these form a basis for buildingfault-tolerant software systems.</p><p>No theory is complete without proof that the ideas work inpractice. To demonstrate that these ideas work in practice Ipresent a number of case studies of large commerciallysuccessful products which use this technology. At the time ofwriting the largest of these projects is a major Ericssonproduct, having over a million lines of Erlang code. Thisproduct (the AXD301) is thought to be one of the most reliableproducts ever made by Ericsson.</p><p>Finally, I ask if the goal of finding better ways to programTelecom applications was fulfilled --- I also point to areaswhere I think the system could be improved.</p>

Errors in health care are one of the leading causes of death and injury in this country, requiring new methods for evaluating and promoting quality in health care services. Concern for patient safety, the foundation for quality services, has prompted national initiatives to examine the most basic premise for health care providers: Do no harm to the patient. Few of these initiatives have examined errors from the perspective of those who have been sanctioned for their errors. This descriptive, exploratory study utilized a survey methodology to examine the perceptions of 62 registered nurses (RNs) who had been sanctioned by a board of nursing to ascertain categories of practice errors and identify individual, health care team, patient, and system threats that contributed to an error and/or patient harm. The Threat and Error Management Model (TEMM) was utilized as a framework for examining the phenomena that promote or hinder patient safety. Using a modified version of the Taxonomy of Error Root Cause Analysis of Practice-Responsibilities (TERCAP) instrument, sanctioned RNs selected types of errors associated with a breakdown in their nursing practice. In addition, they identified factors that contributed to their errors, including individual, health care team, patient, and system threats. Associations between the levels of patient harm and types of error were examined. Two open-ended questions provided an opportunity for the participants to describe changes in their practice since the error event. System and health care team factors were the most common items selected as contributing to the error events, while individual factors were the least often selected items. Two types of errors, clinical evaluation and attentiveness/surveillance, were significantly related to the level of harm to patients. Given the opportunity to discuss individual factors through open-ended questions, responses were comprehensive and many were related to issues with trust. Recommendations for nursing theory, policy, practice, education, and research are reviewed.

No description available.

No description available.

Age, sex, race, heredity, environment and nutrition have been found to influence ametropia. In this study, the distribution of refractive errors has been investigated in relation to age, sex, race, education and near work, and lighting conditions. Visual awareness and vision screening in pre-school and schoolchildren were also investigated. Data were collected using the Nikon auto-refractor, retinoscope, Snellen V.A chart, and subjective techniques. 777 people were refracted, whose ages ranged between four and eighty years. Measurements were made in different sections of Umlazi township, therefore people of different socio-economic sectors were refracted. Four year-old children were found to be hyperopic. Hyperopia decreased and refraction shifted towards emmetropia. Myopia started to appear at the age of ten. Myopia increased until the age of twenty, and thereafter decreased slowly until the age of thirty three, where the average refraction was emmetropia. From age forty onwards, hyperopia was predominant. The incidence of high astigmatism, high hyperopia and high myopia is low in this community. Most people fall in the spherical refractive error region of between -1.000 and +1.000. The curve is leptokurtotic with highest peak around +0.250. The cylindrical error is between -0.500 and -1.000. No significant difference between sexes was found except at the fourth age group (40-51), where females are more hyperopic than males. The other sex difference is at ages ten to twelve, where females develop myopia earlier than males. Illumination plays no important role in the development of refractive errors in this community. Education and near work seem to account very little to the development of myopia. The influence of heredity on the development of ametropia was not investigated in depth. However, there is no evidence of heredity influencing the development of ametropia. There is a lack of vision screening and visual awareness. / Thesis (M.Optom.)-University of Durban-Westville, 1988.

We consider the task of computing reliable numerical approximations of the solutions of elliptic equations and systems where the coefficients vary discontinuously, rapidly, and by large orders of magnitude. Such problems, which occur in diffusion and in linear elastic deformation of composite materials, have solutions with low regularity with the result that reliable numerical approximations can be found only in approximating spaces, invariably with high dimension, that can accurately represent the large and rapid changes occurring in the solution. The use of the Galerkin approach with such high dimensional approximating spaces often leads to very large scale discrete problems which at best can only be solved using efficient solvers. However, even then, their scale is sometimes so large that the Galerkin approach becomes impractical and alternative methods of approximation must be sought. In this thesis we adopt two approaches. We propose a new asymptotic method of approximation for problems of diffusion in materials with periodic structure. This approach uses Fourier series expansions and enables one to perform all computations on a periodic cell; this overcomes the difficulty caused by the rapid variation of the coefficients. In the one dimensional case we have constructed problems with discontinuous coefficients and computed the analytical expressions for their solutions and the proposed asymptotic approximations. The rates at which the given asymptotic approximations converge, as the period of the material decreases, are obtained through extensive computational tests which show that these rates are fundamentally dependent on the level of regularity of the right hand sides of the equations. In the two dimensional case we show how one can use the Galerkin method to approximate the solutions of the problems associated with the periodic cell. We construct problems with discontinuous coefficients and perform extensive computational tests which show that the asymptotic properties of the approximations are identical to those observed in the one dimensional case. However, the computational results show that the application of the Galerkin method of approximation introduces a discretization error which can obscure the precise asymptotic rate of convergence for low regularity right hand sides. For problems of two dimensional linear elasticity we are forced to consider an alternative approach. We use domain decomposition techniques that interface the subdomains with conjugate gradient methods and obtain algorithms which can be efficiently implemented on computers with parallel architectures. We construct the balancing preconditioner, M,, and show that it has the optimal conditioning property k(Mh(^-1)Sh) =< C(1 + log(H/h))^2 where Sh is the discretized Steklov—Poincaré operator, C> 0 is a constant which is independent of the magnitude of the material discontinuities, H is the maximum subdomain diameter, and h is the maximum finite element diameter. These properties of the preconditioning operator Mh allow one to use the computational power of a parallel computer to overcome the difficulties caused by the changing form of the solution of the problem. We have implemented this approach for a variety of problems of planar linear elasticity and, using different domain decompositions, approximating spaces, and materials, find that the algorithm is robust and scales with the dimension of the approximating space and the number of subdomains according to the condition number bound above and is unaffected by material discontinuities. In this we have proposed and implemented new inner product expressions which we use to modify the bilinear forms associated with problems over subdomains that have pure traction boundary conditions.

No description available.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 122-123). Also available on the World Wide Web.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.