Accommodating intraocular lenses:a review of design concepts, usage and assessment methods

The correction of presbyopia and restoration of true accommodative function to the ageing eye is the focus of much ongoing research and clinical work. A range of accommodating intraocular lenses (AIOLs) implanted during cataract surgery has been developed and they are designed to change either their position or shape in response to ciliary muscle contraction to generate an increase in dioptric power. Two main design concepts exist. First, axial shift concepts rely on anterior axial movement of one or two optics creating accommodative ability. Second, curvature change designs are designed to provide significant amplitudes of accommodation with little physical displacement. Single-optic devices have been used most widely, although the true accommodative ability provided by forward shift of the optic appears limited and recent findings indicate that alternative factors such as flexing of the optic to alter ocular aberrations may be responsible for the enhanced near vision reported in published studies. Techniques for analysing the performance of AIOLs have not been standardised and clinical studies have reported findings using a wide range of both subjective and objective methods, making it difficult to gauge the success of these implants. There is a need for longitudinal studies using objective methods to assess long-term performance of AIOLs and to determine if true accommodation is restored by the designs available. While dual-optic and curvature change IOLs are designed to provide greater amplitudes of accommodation than is possible with single-optic devices, several of these implants are in the early stages of development and require significant further work before human use is possible. A number of challenges remain and must be addressed before the ultimate goal of restoring youthful levels of accommodation to the presbyopic eye can be achieved.

Sustainable rural micro-enterprises through co- and tri-generation:review of concepts

Biomass production, conversion and utilization can be done locally with value addition to small farmers. However, new technical inputs are needed for profitable exploitation of biomass within the constraints related to land, water and skill availability and to provide higher quality of energy needed for rural industries. Trigeneration, which is generating energy simultaneously in three forms (electric power, heat for processing and refrigeration), helps in fully utilizing the stored energy in biomass and would be most appropriate for micro enterprises. This paper presents concepts in terms of trigeneration systems feasible for rural areas.

The use of data analysis methods: basic concepts for optometrists

This article explains first, the reasons why a knowledge of statistics is necessary and describes the role that statistics plays in an experimental investigation. Second, the normal distribution is introduced which describes the natural variability shown by many measurements in optometry and vision sciences. Third, the application of the normal distribution to some common statistical problems including how to determine whether an individual observation is a typical member of a population and how to determine the confidence interval for a sample mean is described.

Genetics of ocular disease Part 1: Basic concepts: cells, chromosomes and inheritance

This series of articles describes the basic elements of genetics necessary to understand the new advances and the impact these advances will have on the study and treatment of ocular disease. The first article describes the patterns of inheritance of human characteristics, how they are transmitted between the generations and the structure of chromosomes.

Genetics of ocular disease Part 2: Basic concepts: DNA, proteins and genes

This article on the basic concepts of genetics concentrates on doeoxyribose nucleic acid (DNA), the chemical constituent of the genes. First, it will cover how DNA was discovered to be the substance of the genes. Second, the structure of DNA is revealed together with how DNA molecules can make copies of themselves. Third, the nature of the genetic code contained in DNA and how this code directs the manufacture of proteins is described. Finally, the effects of mutation of the genes and how the activities of genes are regulated will be discussed together with the relevance of these concepts to ocular disease.

Cost and performance analysis of new wood-fuelled power plant concepts

The objective of the thesis was to analyse several process configurations for the production of electricity from biomass. Process simulation models using AspenPlus aimed at calculating the industrial performance of power plant concepts were built, tested, and used for analysis. The criteria used in analysis were performance and cost. All of the advanced systems appear to have higher efficiencies than the commercial reference, the Rankine cycle. However, advanced systems typically have a higher cost of electricity (COE) than the Rankine power plant. High efficiencies do not reduce fuel costs enough to compensate for the high capital costs of advanced concepts. The successful reduction of capital costs would appear to be the key to the introduction of the new systems. Capital costs account for a considerable, often dominant, part of the cost of electricity in these concepts. All of the systems have higher specific investment costs than the conventional industrial alternative, i.e. the Rankine power plant; Combined beat and power production (CUP) is currently the only industrial area of application in which bio-power costs can be considerably reduced to make them competitive. Based on the results of this work, AsperiPlus is an appropriate simulation platform. How-ever, the usefulness of the models could be improved if a number of unit operations were modelled in greater detail. The dryer, gasifier, fast pyrolysis, gas engine and gas turbine models could be improved.

Metaphor in (Arabic-into-English) translation with specific reference to metaphorical concepts and expressions in political discourse

Cognitive linguistics scholars argue that metaphor is fundamentally a conceptual process of mapping one domain of experience onto another domain. The study of metaphor in the context of Translation Studies has not, unfortunately, kept pace with the discoveries about the nature and role of metaphor in the cognitive sciences. This study aims primarily to fill part of this gap of knowledge. Specifically, the thesis is an attempt to explore some implications of the conceptual theory of metaphor for translation. Because the study of metaphor in translation is also based on views about the nature of translation, the thesis first presents a general overview of the discipline of Translation Studies, describing the major models of translation. The study (in Chapter Two) then discusses the major traditional theories of metaphor (comparison, substitution and interaction theories) and shows how the ideas of those theories were adopted in specific translation studies of metaphor. After that, the study presents a detailed account of the conceptual theory of metaphor and some hypothetical implications for the study of metaphor in translation from the perspective of cognitive linguistics. The data and methodology are presented in Chapter Four. A novel classification of conceptual metaphor is presented which distinguishes between different source domains of conceptual metaphors: physical, human-life and intertextual. It is suggested that each source domain places different demands on translators. The major sources of the data for this study are (1) the translations done by the Foreign Broadcasting Information Service (FBIS), which is a translation service of the Central Intelligence Agency (CIA) in the United Sates of America, of a number of speeches by the Iraqi president Saddam Hussein during the Gulf Crisis (1990-1991) and (2) official (governmental) Omani translations of National Day speeches of Sultan Qaboos bin Said of Oman.

Concepts and methods of quantitative assessment of risk to groundwater resources

This work presents a two-dimensional approach of risk assessment method based on the quantification of the probability of the occurrence of contaminant source terms, as well as the assessment of the resultant impacts. The risk is calculated using Monte Carlo simulation methods whereby synthetic contaminant source terms were generated to the same distribution as historically occurring pollution events or a priori potential probability distribution. The spatial and temporal distributions of the generated contaminant concentrations at pre-defined monitoring points within the aquifer were then simulated from repeated realisations using integrated mathematical models. The number of times when user defined ranges of concentration magnitudes were exceeded is quantified as risk. The utilities of the method were demonstrated using hypothetical scenarios, and the risk of pollution from a number of sources all occurring by chance together was evaluated. The results are presented in the form of charts and spatial maps. The generated risk maps show the risk of pollution at each observation borehole, as well as the trends within the study area. This capability to generate synthetic pollution events from numerous potential sources of pollution based on historical frequency of their occurrence proved to be a great asset to the method, and a large benefit over the contemporary methods.

Analysis of constructivist, network-based discourses:concepts, prospects, and illustrations

The authors propose a new approach to discourse analysis which is based on meta data from social networking behavior of learners who are submerged in a socially constructivist e-learning environment. It is shown that traditional data modeling techniques can be combined with social network analysis - an approach that promises to yield new insights into the largely uncharted domain of network-based discourse analysis. The chapter is treated as a non-technical introduction and is illustrated with real examples, visual representations, and empirical findings. Within the setting of a constructivist statistics course, the chapter provides an illustration of what network-based discourse analysis is about (mainly from a methodological point of view), how it is implemented in practice, and why it is relevant for researchers and educators.

Overlapping of legal concepts:classifying the law of trusts

The purpose of this piece is to explain how the trust concept fits the overlapping analysis, presenting an example of why discrete categorisation is often unhelpful in understanding the operation of legal concepts.

Boundary spanning elements and the marketing function in organizations:concepts and empirical studies

This book presents current research on boundary spanning elements. The editors bring together extant knowledge in the field and present a uniform narrative. Previous studies have often been disseminated across several academic disciplines like services marketing, personal selling and sales management etc. and this monograph aggregates studies dealing with boundary spanning elements or has boundary spanning elements related to the marketing function as the main empirical platform under a uniform theoretical perspective. Each chapter in the book deals with an important research theme and synthesizes studies in relation to boundary spanning elements.