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Several taxonomic characters, including the number of trunk myomeres, proportional body measurements and patterns of external and internal pigmentation, have been investigated in populations of ammocoetes belonging to the three species of lampreys found in British rivers. Petromyzon marinus can be readily distinguished by the pigmentary pattern in the tail and on the oral hood, and by the much higher number of trunk myomeres. Although no character can be used to separate with certainty the larvae of Lampetra fluviatilis and Lampetra planeri, significant differences were found between the mean number of trunk myomeres in the two species. Moreover, the values for ammocoetes were virtually identical to those of the respective post-larval stages, at which phase in the life cycle the two Lampetra species are clearly distinguishable. The incidence of pigmentation on the tongue precursor was much higher in larval populations of L. fluviatilis than in those of L. planeri and there was also a difference in the rate of change in the relative length of the trunk and tail. Where comparisons can be made, the results in this paper are in agreement with those of most other European and North American workers. The data differ markedly, however, from that contained in the only other previous detailed systematic study on British larval lampreys, which was subsequently used as the basis for taxonomic keys.

Several taxonomic characters, including the number of trunk myomeres, proportional body measurements and patterns of external and internal pigmentation, have been investigated in populations of ammocoetes belonging to the three species of lampreys found in British rivers. Petromyzon marinus can be readily distinguished by the pigmentary pattern in the tail and on the oral hood, and by the much higher number of trunk myomeres. Although no character can be used to separate with certainty the larvae of Lampetra fluviatilis and Lampetra planeri, significant differences were found between the mean number of trunk myomeres in the two species. Moreover, the values for ammocoetes were virtually identical to those of the respective post-larval stages, at which phase in the life cycle the two Lampetra species are clearly distinguishable. The incidence of pigmentation on the tongue precursor was much higher in larval populations of L. fluviatilis than in those of L. planeri and there was also a difference in the rate of change in the relative length of the trunk and tail. Where comparisons can be made, the results in this paper are in agreement with those of most other European and North American workers. The data differ markedly, however, from that contained in the only other previous detailed systematic study on British larval lampreys, which was subsequently used as the basis for taxonomic keys.

This paper attempts to demonstrate an application of the techniques of systems analysis, which have been successful in solving a variety of problems, to the question of nuclear facility siting. Within the framework of an overall, regional land use plan, a methodology for establishing the acceptability of a combination of site and facility is discussed. The consequences, e.g., the energy produced, thermal and chemical discharges, radioactive releases, aesthetic values, etc., of the site-facility combination are identified and compared with formalized criteria in order to ensure what might be called legal acceptability. Failure of any consequences to satisfy standard requirements results in a feedback channel which works to effect design changes in the facility. When legal acceptability has been assured, the project enters the public sector for consideration. The responses of individuals and of various interested groups to the external attributes of the nuclear facility gradually emerge. The criteria by which interest groups judge technological advances reflect both rational assessment and unconscious motivations. This process operates on individual, group, societal and international levels and may result in two basic feedback loops: one which might act to change regulatory criteria; the other which might influence facility design or site selection. Such reactions and responses on these levels result in a continuing process of confrontation, collaborative interchange and possible resolution in the direction of an acceptable solution. Finally, a Paretian approach to optimizing the site-facility combination is presented for the case where there are several possible combinations of site and facility. A hypothetical example of the latter is given, based upon typical preference functions determined for four interest groups. The article summarizes the research efforts of the Project on Energy systems of the International Institute of Applied Systems Analysis, IIASA, in Laxe

This paper attempts to demonstrate an application of the techniques of systems analysis, which have been successful in solving a variety of problems, to the question of nuclear facility siting. Within the framework of an overall, regional land use plan, a methodology for establishing the acceptability of a combination of site and facility is discussed. The consequences, e.g., the energy produced, thermal and chemical discharges, radioactive releases, aesthetic values, etc., of the site-facility combination are identified and compared with formalized criteria in order to ensure what might be called legal acceptability. Failure of any consequences to satisfy standard requirements results in a feedback channel which works to effect design changes in the facility. When legal acceptability has been assured, the project enters the public sector for consideration. The responses of individuals and of various interested groups to the external attributes of the nuclear facility gradually emerge. The criteria by which interest groups judge technological advances reflect both rational assessment and unconscious motivations. This process operates on individual, group, societal and international levels and may result in two basic feedback loops: one which might act to change regulatory criteria; the other which might influence facility design or site selection. Such reactions and responses on these levels result in a continuing process of confrontation, collaborative interchange and possible resolution in the direction of an acceptable solution. Finally, a Paretian approach to optimizing the site-facility combination is presented for the case where there are several possible combinations of site and facility. A hypothetical example of the latter is given, based upon typical preference functions determined for four interest groups. The article summarizes the research efforts of the Project on Energy systems of the International Institute of Applied Systems Analysis, IIASA, in Laxe

This paper describes an interactive computer program designed to facilitate the quantification of a decision maker's preferences for multiple objectives in terms of a multiattribute utility function. The program is intended to alleviate many of the operational difficulties with current procedures for assessing and using multiattribute utility functions. The package includes commands for structuring the utility function, assessing single attribute, component utility functions of the overall multiattribute utility function, identifying the preference tradeoffs between attributes, evaluating alternatives, and performing sensitivity analysis. Suggestions for using the program are included.

This paper describes an interactive computer program designed to facilitate the quantification of a decision maker's preferences for multiple objectives in terms of a multiattribute utility function. The program is intended to alleviate many of the operational difficulties with current procedures for assessing and using multiattribute utility functions. The package includes commands for structuring the utility function, assessing single attribute, component utility functions of the overall multiattribute utility function, identifying the preference tradeoffs between attributes, evaluating alternatives, and performing sensitivity analysis. Suggestions for using the program are included.

The 48th congress of the Australian and New Zealand Association for the advancement of science was held at Melbourne University from August 29th to September 2nd, and optometry again constituted its own section and presented a programme of free papers and symposia.

Contrast sensitivity for target I (3.24/diameter) of the 30 cm radius Goldmann perimeter was measured along the horizontal meridian to 50 degrees eccentricity in 5 subjects. Background luminance was 10.0 cd/m2 and stimulus duration was 130±4 ms. Using this data and the ophthalmic lens prismatic effects to be presented in another paper, the alteration in static perimetric sensitivity caused by spectacle lens prismatic effects was estimated. For spectacle lenses with powers between -6 D and + 10 D, the maximum sensitivity alteration was only 0.30 log units (+10 D, 25 degrees temporal) for a 14 mm vertex distance. As the experiment used conditions producing maximum visual field sensitivity gradients, and hence the maximum alteration in sensitivity caused by prismatic effects, prismatic effects of corrective ophthalmic lenses can be ignored within the central 30 degrees - 40 degrees visual field during static perimetry for lens powers less than ± 10 D.

This paper reviews development of visual field measurement (perimetry) from ancient times to the present. Since 1850 there has been a marked awareness of the importance of visual field measurement to neuro-ophthalmological diagnosis. This has resulted in a continuous increase in the number and complexity of perimetric methods.

This paper considers the dynamic linear programming model for multispecies live-stock farming with a feed production subsystem. The problem is to determine the optimal livestock mix with the projected growth rate and corresponding development of feed production in order to obtain the maximum profit for the given planning horizon. As examples, the planning model for a dairy farm and the control problem of age-size structure of a biological population are given.

This paper considers the dynamic linear programming model for multispecies live-stock farming with a feed production subsystem. The problem is to determine the optimal livestock mix with the projected growth rate and corresponding development of feed production in order to obtain the maximum profit for the given planning horizon. As examples, the planning model for a dairy farm and the control problem of age-size structure of a biological population are given.

Computer models of the world system produce very different results, ranging from economic collapse and massive starvation in the 21st century to universal prosperity for double or triple the present world population. The strikingly different conclusions that arise make it urgent to compare them effectively with one another, and see what it is about them that produces such diverse policies. Insofar as the policies are similar, one would like to know more about how they arise from the models. This paper suggests a line of analysis that permits comparison of properties among such models. It takes up two ways of seeing what is in a model in addition to examining its documentation: first, making alternative transparent models that check the partial results of the complex model; and, second, black-box experiments leading to a truncated linear form of the complex model. These two methods of assessment are designed to replace most of the documentation, and to allow the user to understand more effectively what assumptions one commits oneself to in using the model.

Computer models of the world system produce very different results, ranging from economic collapse and massive starvation in the 21st century to universal prosperity for double or triple the present world population. The strikingly different conclusions that arise make it urgent to compare them effectively with one another, and see what it is about them that produces such diverse policies. Insofar as the policies are similar, one would like to know more about how they arise from the models. This paper suggests a line of analysis that permits comparison of properties among such models. It takes up two ways of seeing what is in a model in addition to examining its documentation: first, making alternative transparent models that check the partial results of the complex model; and, second, black-box experiments leading to a truncated linear form of the complex model. These two methods of assessment are designed to replace most of the documentation, and to allow the user to understand more effectively what assumptions one commits oneself to in using the model.

Contact lens practitioners often rely on specifications supplied by manufacturers for information on new lens materials and new lens designs. Comparison of different contact lenses on the basis of this information is made difficult by the use of non-standard test procedures and a lack of consistency in the presentation of data. In this paper commonly used parameters are explained and their relative importance is discussed. It is suggested that independent reports provide the best method of comparison.

This paper presents a mathematical model for all matter-energy processing subsystems at the level of he society, specifically India. It explores India's choices in the food and energy sectors over the coming decades. Alternative land intnsive, irrigation energy intensive, and fertilizer intensive techniques of food production are identified using a nonlinear programming mdel. The land saved is devoted to growing firewood. The optimum combination of railway (steam, diesel, and electric traction) and road automobiles, diesel trucks, and diesel and gasoline buses) transport is determined. For the oil sector, two alternative sources of suply of crude oil and petroleum products are included, namely, domestic production and imports. The optimum choice is determined through a linear programming model. While the model is basically a satic one, designed to determine the optimal choice for the target year of 2000-2001, certain intertemporal detail is incorporated forelectricity generation. The model minimizes the costs of meeting the needs for food, transport in terms of passenger kilometers and goos per ton per kilometer, energy needs for domestic cooking and lighting, and the energy needs of the rest of the economy.

This paper presents a mathematical model for all matter-energy processing subsystems at the level of he society, specifically India. It explores India's choices in the food and energy sectors over the coming decades. Alternative land intnsive, irrigation energy intensive, and fertilizer intensive techniques of food production are identified using a nonlinear programming mdel. The land saved is devoted to growing firewood. The optimum combination of railway (steam, diesel, and electric traction) and road automobiles, diesel trucks, and diesel and gasoline buses) transport is determined. For the oil sector, two alternative sources of suply of crude oil and petroleum products are included, namely, domestic production and imports. The optimum choice is determined through a linear programming model. While the model is basically a satic one, designed to determine the optimal choice for the target year of 2000-2001, certain intertemporal detail is incorporated forelectricity generation. The model minimizes the costs of meeting the needs for food, transport in terms of passenger kilometers and goos per ton per kilometer, energy needs for domestic cooking and lighting, and the energy needs of the rest of the economy.

This paper presents an analysis of the role of public phenomena like knowledge and research and development in the economic growth process of a spatially extended economy. It deals with the organizational level of living systems (regions) and the societal level, and with monetary information flows, chiefly in the decider and channel and net subsystems. Accessibility to knowledge pools is used as a way of connecting regions with each other. It is shown with analytical methods as well as with simulation that improving information networks will generally lead to a higher rate of growth in all regions if the economies behave according to the neoclassical paradigm. Superimposing an accessibility function with spatial frictions in the information flows on a technology with economies of scale leads to uneven but realistic dynamics. In this case there is an increasing inequality of income per capita between regions with different centrality up to a point of maximum inequality with a subsequent convergence thereafter. The analysis demonstrates that increasing research and development activities can, under certain probable technologies, lead to increasing inequalities between rich and poor regions.

This paper presents an analysis of the role of public phenomena like knowledge and research and development in the economic growth process of a spatially extended economy. It deals with the organizational level of living systems (regions) and the societal level, and with monetary information flows, chiefly in the decider and channel and net subsystems. Accessibility to knowledge pools is used as a way of connecting regions with each other. It is shown with analytical methods as well as with simulation that improving information networks will generally lead to a higher rate of growth in all regions if the economies behave according to the neoclassical paradigm. Superimposing an accessibility function with spatial frictions in the information flows on a technology with economies of scale leads to uneven but realistic dynamics. In this case there is an increasing inequality of income per capita between regions with different centrality up to a point of maximum inequality with a subsequent convergence thereafter. The analysis demonstrates that increasing research and development activities can, under certain probable technologies, lead to increasing inequalities between rich and poor regions.

This paper provides the first detailed qualitative and quantitative description of metamorphosis in the lamprey Geotria australis, which is the sole representative of the exclusively Southern Hemisphere family Geotriidae. Using a description which separates metamorphosis into seven sequential stages, emphasis has been placed on the pattern of development of ihe unique adult characters found in this family. Such characters include the spatulate shape of the teeth, the markedly tridentate anterior lingual lamina, the prominent longitudinal dorso-lateral blue-green stripes, the pair of enlarged oral disc papillae, and the gap between the second dorsal and caudal fins. Moreover, body proportion data demonstrate that compared with other genera, Geotria has an unusually small eye and oral disc and a relatively long trunk. While during metamorphosis the length remained relatively constant, due to compensatory increases in the actual length of some parts of the body against losses in other regions, both the mean weight and the condition factor declined. The latter reductions are clearly related to the fact that the animal does not feed during the six months between the onset of metamorphosis in late January and early February and the time when the animal embarks on its movement towards the sea in late July and early August. The length and weight data suggest that G. australis enters metamorphosis at a smaller size than any other parasitic species of lamprey. The sex ratio in the 218 individuals whose gonad was examined, indicated that the populations in south-western Australia were characterised by a slight excess of males (1♀: M8♂). The mortality encountered when downstream migrants were transferred to 100% sea water was 36% after direct transfer and 10–12% after prior acclimation to reduced salinities.

This paper provides the first detailed qualitative and quantitative description of metamorphosis in the lamprey Geotria australis, which is the sole representative of the exclusively Southern Hemisphere family Geotriidae. Using a description which separates metamorphosis into seven sequential stages, emphasis has been placed on the pattern of development of ihe unique adult characters found in this family. Such characters include the spatulate shape of the teeth, the markedly tridentate anterior lingual lamina, the prominent longitudinal dorso-lateral blue-green stripes, the pair of enlarged oral disc papillae, and the gap between the second dorsal and caudal fins. Moreover, body proportion data demonstrate that compared with other genera, Geotria has an unusually small eye and oral disc and a relatively long trunk. While during metamorphosis the length remained relatively constant, due to compensatory increases in the actual length of some parts of the body against losses in other regions, both the mean weight and the condition factor declined. The latter reductions are clearly related to the fact that the animal does not feed during the six months between the onset of metamorphosis in late January and early February and the time when the animal embarks on its movement towards the sea in late July and early August. The length and weight data suggest that G. australis enters metamorphosis at a smaller size than any other parasitic species of lamprey. The sex ratio in the 218 individuals whose gonad was examined, indicated that the populations in south-western Australia were characterised by a slight excess of males (1♀: M8♂). The mortality encountered when downstream migrants were transferred to 100% sea water was 36% after direct transfer and 10–12% after prior acclimation to reduced salinities.

After discussing the current reporting on two mature IIASA research activities, those on global energy and interregional migration, this introduction describes the four main themes foreseen as motivating IIASA's future work: global transition, national interdependence, regional integration, and the craft of systems analysis. After mentioning the backgrounds of the papers in this issue, some items of general interest are listed.

After discussing the current reporting on two mature IIASA research activities, those on global energy and interregional migration, this introduction describes the four main themes foreseen as motivating IIASA's future work: global transition, national interdependence, regional integration, and the craft of systems analysis. After mentioning the backgrounds of the papers in this issue, some items of general interest are listed.

This paper has two aims. The first is to exposit the various forms of the LM statistic and to collect together some of the relevant research reported in the mathematical statistics literature. The second is to illustrate the construction of LM tests by considering a number of particular econometric specifications as examples. It will be found that in many instances the LM statistic can be computed by a regression using the residuals of the fitted model which, because of its simplicity, is itself estimated by OLS. The paper contains five sections. In Section 2, the LM statistic is outlined and some alternative versions of it are discussed. Section 3 gives the derivation of the statistic for several econometric specifications. Applications in this section are the testing for a liquidity trap, autocorrelation, the error components model, diagonality of a covariance matrix in seemingly unrelated equation systems and choice between models generated by separate families of distributions. Section 4 considers the construction of a pseudo-LM statistic when estimation is difficult even under the null hypothesis and discusses the derivation of the exact distribution of the statistic. A concluding summary is given as Section

This paper has two aims. The first is to exposit the various forms of the LM statistic and to collect together some of the relevant research reported in the mathematical statistics literature. The second is to illustrate the construction of LM tests by considering a number of particular econometric specifications as examples. It will be found that in many instances the LM statistic can be computed by a regression using the residuals of the fitted model which, because of its simplicity, is itself estimated by OLS. The paper contains five sections. In Section 2, the LM statistic is outlined and some alternative versions of it are discussed. Section 3 gives the derivation of the statistic for several econometric specifications. Applications in this section are the testing for a liquidity trap, autocorrelation, the error components model, diagonality of a covariance matrix in seemingly unrelated equation systems and choice between models generated by separate families of distributions. Section 4 considers the construction of a pseudo-LM statistic when estimation is difficult even under the null hypothesis and discusses the derivation of the exact distribution of the statistic. A concluding summary is given as Section

This paper describes the Humphrey Vision Analyser (HVA) which is a subjective refracting instrument incorporating the unique principles of 'remote refraction' and continuously variable topics. Increased versatility can be obtained by connecting the HVA to the Humphrey Lens Analyser, forming an over-refraction system. A brief evaluation is presented.

This paper deals with the socioeconomic dimension of creativity in technology organization and economy. Creativity is decisive for the development of social systems, but one finds evidence that creativity is a wasted resource. Obstacles to creativity have been identified over the following stages: formation of creative personalities, creation period, and realization period; and on four levels: growth of productive forces, economic relations and interests, institutions, and mental or ideological factors. World, society, organizations, groups, and individuals and their interaction are the objects of social creativity research. Measurement of creativity in the stages research, development, and introduction and improvement uses four dimensions: results, process, personal characteristics, and level of participation. Creativity is closely connected with its counterpart: routine experience. In an organization the innovation potential plays an important role, together with such determinants as strategic orientation, capacity for current production operations, and level of cooperation and coordination.

This paper deals with the socioeconomic dimension of creativity in technology organization and economy. Creativity is decisive for the development of social systems, but one finds evidence that creativity is a wasted resource. Obstacles to creativity have been identified over the following stages: formation of creative personalities, creation period, and realization period; and on four levels: growth of productive forces, economic relations and interests, institutions, and mental or ideological factors. World, society, organizations, groups, and individuals and their interaction are the objects of social creativity research. Measurement of creativity in the stages research, development, and introduction and improvement uses four dimensions: results, process, personal characteristics, and level of participation. Creativity is closely connected with its counterpart: routine experience. In an organization the innovation potential plays an important role, together with such determinants as strategic orientation, capacity for current production operations, and level of cooperation and coordination.

The paper is a critique of Moore's conception of common sense – a conception based on two central propositions. The critique is specific and textual in character but turns generally upon the difficulties inherent in Moore's attempt to articulate definite propositional grounds for common sense knowledge. By contrast, the discourse of the critique favours a praxiological conception of common sense and so proceeds to show how Moore's propositional conception itself emerges from certain textual and discursive techniques.

The paper is a critique of Moore's conception of common sense – a conception based on two central propositions. The critique is specific and textual in character but turns generally upon the difficulties inherent in Moore's attempt to articulate definite propositional grounds for common sense knowledge. By contrast, the discourse of the critique favours a praxiological conception of common sense and so proceeds to show how Moore's propositional conception itself emerges from certain textual and discursive techniques.

Simulation models constructed to estimate the physical and economic performance of alternative river basin development configurations have been widely used since the start of the Harvard Water Program in the early 1960's. These models have proved useful in choosing from among several potential river basin configurations, since they can rapidly evaluate each configuration's expected performance. However, when dealing with large scale river basin development projects, in which over 50 or 100 alternative reservoirs, irrigation areas, and other components must be considered, it is sometimes quite difficult to effectiely use a simulation model to rapidly identify those combinations of projects which best satisfy the development objectives. The purpose of this paper is to describe how a simulation model was used in the analysis of a complex river basin development project in Eastern Eurpe, and how the problems of scale were confronted and solved. The author's experience on this projet is used to derive a set of general guidelines which may be helpful in other simulation studies.

Simulation models constructed to estimate the physical and economic performance of alternative river basin development configurations have been widely used since the start of the Harvard Water Program in the early 1960's. These models have proved useful in choosing from among several potential river basin configurations, since they can rapidly evaluate each configuration's expected performance. However, when dealing with large scale river basin development projects, in which over 50 or 100 alternative reservoirs, irrigation areas, and other components must be considered, it is sometimes quite difficult to effectiely use a simulation model to rapidly identify those combinations of projects which best satisfy the development objectives. The purpose of this paper is to describe how a simulation model was used in the analysis of a complex river basin development project in Eastern Eurpe, and how the problems of scale were confronted and solved. The author's experience on this projet is used to derive a set of general guidelines which may be helpful in other simulation studies.

A measure of the Swedish money stock is identified in this paper using an empirical approach. Correlation coefficients between quarterly changos in a number of monetary assets and economic activity are calculated for leading, concurrent and lagging observations. Coins and notes exhibit close simultaneous covariation with economic activity. Commercial bank, savings bank and Post Office Bank deposits lead changes in economic activity by 6-8 quarters. This countercycUcal pattern is best regarded as the outcome of Eikabank policy. The empirical results suggest a defmition of the Swedish money stock as the sum of the volume of notea andcommercial bank deposits held by the public.

After a brief review of the nature of strategic planning, and the problems of defining health service objectives, the paper concentrates on the question of decision making and "strategic control," in the context of a regional health authority, a system at the level of the organization. The purpose of monitoring is defined in detail. A critical review of concepts of control in various disciplines considers their suitability to the health authority context. An integration of feedforward and feedback control loops is developed in order to meet the specific characteristics of a system in which "environment" can be viewed as the "input," and to provide the adaptive, learning capability which is required by the situation of insufficient data, ignorance of underlying mechanisms, and continuing change.

After a brief review of the nature of strategic planning, and the problems of defining health service objectives, the paper concentrates on the question of decision making and "strategic control," in the context of a regional health authority, a system at the level of the organization. The purpose of monitoring is defined in detail. A critical review of concepts of control in various disciplines considers their suitability to the health authority context. An integration of feedforward and feedback control loops is developed in order to meet the specific characteristics of a system in which "environment" can be viewed as the "input," and to provide the adaptive, learning capability which is required by the situation of insufficient data, ignorance of underlying mechanisms, and continuing change.

The siting of facilities for large-scale, novel technologies presents a formidable challenge to politcal risk management. This paper develops a model for describing the decision process for this type of problem at the level of societal systems. It explicitly considers the role of the relevant interested parties, each of whom brings to the siting debate its own set of objetives and attributes. We have labeled the approach a multiattribute multiparty model (MAMP to distinguish it from prescriptive techniques such as multiattribute utility analysis or decision analysis). The MAMP model is a natural extension of the burgeoning literature on the key role that limited time, attention, and information processing capabilities play in political decision making when there are uncertain outcomes and likely conflicts among interested parties. The model also highlights the importance of decentralized and sequential decision making and indicates the role that formal risk assessments have played at each stage of the process. We illustrate its application in the context of the decision proess associated with a proposed liquiefied natural gas terminal in California. The concluding portion of this paper suggests future rsearch needs for improving the credibility of analysis and facilitating collective action with respect to facility siting problems.

The siting of facilities for large-scale, novel technologies presents a formidable challenge to politcal risk management. This paper develops a model for describing the decision process for this type of problem at the level of societal systems. It explicitly considers the role of the relevant interested parties, each of whom brings to the siting debate its own set of objetives and attributes. We have labeled the approach a multiattribute multiparty model (MAMP to distinguish it from prescriptive techniques such as multiattribute utility analysis or decision analysis). The MAMP model is a natural extension of the burgeoning literature on the key role that limited time, attention, and information processing capabilities play in political decision making when there are uncertain outcomes and likely conflicts among interested parties. The model also highlights the importance of decentralized and sequential decision making and indicates the role that formal risk assessments have played at each stage of the process. We illustrate its application in the context of the decision proess associated with a proposed liquiefied natural gas terminal in California. The concluding portion of this paper suggests future rsearch needs for improving the credibility of analysis and facilitating collective action with respect to facility siting problems.

Major theoretical advances in understanding the operating forces of society have not led to corresponding improvement in techniques of forecasting. Ranging across the major socioeconomic theories bearing on demographic trends - from demographic transition theory to human capital theory - this paper asks whether there are scientific results neglected by forecasters that would help population forecasting and, if not, what it is in the nature of scholarship that makes it unusable for this purpose. The static and conditional nature of most theory, the presence of confounding factors that swamp the postulated effect, and uncertainty of timing are among the major limitations in application of theoretical insights to forecasting. Pending discovery of a truly behavioral way of estimating the future, extrapolation of the observed regularities of the past remains the best that can be expected.

Major theoretical advances in understanding the operating forces of society have not led to corresponding improvement in techniques of forecasting. Ranging across the major socioeconomic theories bearing on demographic trends - from demographic transition theory to human capital theory - this paper asks whether there are scientific results neglected by forecasters that would help population forecasting and, if not, what it is in the nature of scholarship that makes it unusable for this purpose. The static and conditional nature of most theory, the presence of confounding factors that swamp the postulated effect, and uncertainty of timing are among the major limitations in application of theoretical insights to forecasting. Pending discovery of a truly behavioral way of estimating the future, extrapolation of the observed regularities of the past remains the best that can be expected.

It is a well established fact that older persons require higher levels of illumination to meet their visual needs, than do younger people. However, most interior lighting standards pay little attention to the needs of older persons. These standards give few recommendations for domestic lighting and rarely does illumination in homes meet the recommended levels. This paper discusses the role of the optometrist in the assessment of the response of older patients to illuminance levels and presents information which can help the optometrist better advise older persons on their domestic lighting requirements.

This paper describe two cases of papilloedema due to raised intra-cranial pressure; one caused by a brain tumor and other by psudo-tumor cerebri, (benign intra-cranial hypertension).

Experts frequently differ on their estimates of risk associated with accidents that have a low probablity of occurrence. Those who stand to benefit from siting a new facility often perceive it as acceptably safe, using expert opinion to defend their argument. Potential losers find data to suggest that the new technology is too hazardous. This paper contrasts the role of risk assesments of low probability events in siting Liquified Natural Gas (LNG) terminals in the United States and the Federal Republic of Germany. In both cases the decision process was a rather lengthy one due to conflicts between interested stakeholders. The paper discussed the potential of compensation and insurance as policy tools for facilitating negotiation. Four criteria for improving the siting process in any country are also outlined.

Experts frequently differ on their estimates of risk associated with accidents that have a low probablity of occurrence. Those who stand to benefit from siting a new facility often perceive it as acceptably safe, using expert opinion to defend their argument. Potential losers find data to suggest that the new technology is too hazardous. This paper contrasts the role of risk assesments of low probability events in siting Liquified Natural Gas (LNG) terminals in the United States and the Federal Republic of Germany. In both cases the decision process was a rather lengthy one due to conflicts between interested stakeholders. The paper discussed the potential of compensation and insurance as policy tools for facilitating negotiation. Four criteria for improving the siting process in any country are also outlined.

Orthodox demand theory has received greater flexibility and adaptability to different choice situations from the broad family of Additive Random Utility Models. But this development leaves the major open issues in demand analysis till unresolved. In this contribution special attention is given to alternative theoretical frameworks for the interpretation of Random Utility Models. The analysis conducted opens the way for further developments and, in conclusion, a first outline of a stochastic model, where choice probabilities can be interpreted as function of some 'observed attractiveness' in the theoretical framework of bounded rationality, is presented.

Orthodox demand theory has received greater flexibility and adaptability to different choice situations from the broad family of Additive Random Utility Models. But this development leaves the major open issues in demand analysis till unresolved. In this contribution special attention is given to alternative theoretical frameworks for the interpretation of Random Utility Models. The analysis conducted opens the way for further developments and, in conclusion, a first outline of a stochastic model, where choice probabilities can be interpreted as function of some 'observed attractiveness' in the theoretical framework of bounded rationality, is presented.

This paper describes a simple, in-office procedure for measuring the oxygen transmissibility (DK/L) of hydrogel contact lenses. The procedure involves measuring lens thickness with an electrical micrometer and lens water content using a hand refractometer. A graph is provided so that the lens DK/L can be derived from these two parameters. A protocol for in-office DK/L measurement is presented and the application of this procedure to patient management is discussed.

Lenticular designs are useful for high negative spectacle prescriptions. This paper presents an accurate method for determining the power of the extra curve to be surfaced on the back surfaces of a negative lenticular spectacle lens in order to obtain the required edge thickness. Data required are the front surface power, back surface power, refractive index, centre thickness, full diameter and aperture diameter.

The term "aspheric" means non-spherical but this simple definition could include toric surfaces, which is not intended in this paper. Instead the term "aspheric" will cover only rotationally non-spherical surfaces. Aspheric surfaces occur frequently in ophthalmic optics. For example the four refracting surfaces of the eye are more accurately described by aspheric mathematical functions than by a simple spherical function. Throughout the ophthalmic literature a number of different methods for specifying aspheric surfaces have been in use, particularly in the case of ophthalmic lenses. The purpose of this paper is to review the nature of aspheric surfaces, their mathematical description and their occurrence and significance in ophthalmic optics. Their effect on aberrations is of particular significance and their effect on the oblique astigmatism in spectacle lenses will be discussed in depth.

The development of corneal oedema during hydrogel contact lens wear is well documented; however, the magnitude of lens-induced swelling cannot be completely explained in terms of a response to hypoxia. This paper examines whether there may, in addition to other factors, be an inflammatory component in the aetiology of contact lens induced corneal oedema. A hypothesis is advanced – that hypoxia induced by a contact lens stimulates the release of prostaglandins from the cornea, which interfere with endothelial control of corneal hydration, resulting in corneal oedema. This hypothesis was tested by studying the effects of the prostaglandin-inhibitor naproxen on contact lens induced corneal oedema. Naproxen was found to have no measurable effect. The clinical and physiological implications of this result are discussed.