Increasing profits and reducing risks in crop production using participatory systems simulation approaches

The development of cropping systems simulation capabilities world-wide combined with easy access to powerful computing has resulted in a plethora of agricultural models and consequently, model applications. Nonetheless, the scientific credibility of such applications and their relevance to farming practice is still being questioned. Our objective in this paper is to highlight some of the model applications from which benefits for farmers were or could be obtained via changed agricultural practice or policy. Changed on-farm practice due to the direct contribution of modelling, while keenly sought after, may in some cases be less achievable than a contribution via agricultural policies. This paper is intended to give some guidance for future model applications. It is not a comprehensive review of model applications, nor is it intended to discuss modelling in the context of social science or extension policy. Rather, we take snapshots around the globe to 'take stock' and to demonstrate that well-defined financial and environmental benefits can be obtained on-farm from the use of models. We highlight the importance of 'relevance' and hence the importance of true partnerships between all stakeholders (farmer, scientists, advisers) for the successful development and adoption of simulation approaches. Specifically, we address some key points that are essential for successful model applications such as: (1) issues to be addressed must be neither trivial nor obvious; (2) a modelling approach must reduce complexity rather than proliferate choices in order to aid the decision-making process (3) the cropping systems must be sufficiently flexible to allow management interventions based on insights gained from models. The pro and cons of normative approaches (e.g. decision support software that can reach a wide audience quickly but are often poorly contextualized for any individual client) versus model applications within the context of an individual client's situation will also be discussed. We suggest that a tandem approach is necessary whereby the latter is used in the early stages of model application for confidence building amongst client groups. This paper focuses on five specific regions that differ fundamentally in terms of environment and socio-economic structure and hence in their requirements for successful model applications. Specifically, we will give examples from Australia and South America (high climatic variability, large areas, low input, technologically advanced); Africa (high climatic variability, small areas, low input, subsistence agriculture); India (high climatic variability, small areas, medium level inputs, technologically progressing; and Europe (relatively low climatic variability, small areas, high input, technologically advanced). The contrast between Australia and Europe will further demonstrate how successful model applications are strongly influenced by the policy framework within which producers operate. We suggest that this might eventually lead to better adoption of fully integrated systems approaches and result in the development of resilient farming systems that are in tune with current climatic conditions and are adaptable to biophysical and socioeconomic variability and change. (C) 2001 Elsevier Science Ltd. All rights reserved.

A decision support system for selecting sanitation systems in developing countries

Due to the socio-economic inhomogeneity of communities in developing countries, the selection of sanitation systems is a complex task. To assist planners and communities in assessing the suitability of alternatives, the decision support system SANEX™ was developed. SANEX™ evaluates alternatives in two steps. First, Conjunctive Elimination, based on 20 mainly technical criteria, is used to screen feasible alternatives. Subsequently, a model derived from Multiattribute Utility Technique (MAUT) uses technical, socio-cultural and institutional criteria to compare the remaining alternatives with regard to their implementability and sustainability. This paper presents the SANEX™ algorithm, examples of its application in practice, and results obtained from field testing.

Benchmarking nitrogen removal suspended-carrier biofilm systems using dynamic simulation

We are witnessing an enormous growth in biological nitrogen removal from wastewater. It presents specific challenges beyond traditional COD (carbon) removal. A possibility for optimised process design is the use of biomass-supporting media. In this paper, attached growth processes (AGP) are evaluated using dynamic simulations. The advantages of these systems that were qualitatively described elsewhere, are validated quantitatively based on a simulation benchmark for activated sludge treatment systems. This simulation benchmark is extended with a biofilm model that allows for fast and accurate simulation of the conversion of different substrates in a biofilm. The economic feasibility of this system is evaluated using the data generated with the benchmark simulations. Capital savings due to volume reduction and reduced sludge production are weighed out against increased aeration costs. In this evaluation, effluent quality is integrated as well.

An overview of APSIM, a model designed for farming systems simulation

The Agricultural Production Systems Simulator (APSIM) is a modular modelling framework that has been developed by the Agricultural Production Systems Research Unit in Australia. APSIM was developed to simulate biophysical process in farming systems, in particular where there is interest in the economic and ecological outcomes of management practice in the face of climatic risk. The paper outlines APSIM's structure and provides details of the concepts behind the different plant, soil and management modules. These modules include a diverse range of crops, pastures and trees, soil processes including water balance, N and P transformations, soil pH, erosion and a full range of management controls. Reports of APSIM testing in a diverse range of systems and environments are summarised. An example of model performance in a long-term cropping systems trial is provided. APSIM has been used in a broad range of applications, including support for on-farm decision making, farming systems design for production or resource management objectives, assessment of the value of seasonal climate forecasting, analysis of supply chain issues in agribusiness activities, development of waste management guidelines, risk assessment for government policy making and as a guide to research and education activity. An extensive citation list for these model testing and application studies is provided. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.

Phenomenological turbulence and innovation in knowledge systems

Most considerations of knowledge management focus on corporations and, until recently, considered knowledge to be objective, stable, and asocial. In this paper we wish to move the focus away from corporations, and examine knowledge and national innovation systems. We argue that the knowledge systems in which innovation takes place are phenomenologically turbulent, a state not made explicit in the change, innovation and socio-economic studies of knowledge literature, and that this omission poses a serious limitation to the successful analysis of innovation and knowledge systems. To address this lack we suggest that three evolutionary processes must be considered: self-referencing, self-transformation and self-organisation. These processes, acting simultaneously, enable system cohesion, radical innovation and adaptation. More specifically, we argue that in knowledge-based economies the high levels of phenomenological turbulence drives these processes. Finally, we spell out important policy principles that derive from these processes.

Clinical and economic impact of exercise electrocardiography and exercise echocardiography in clinical practice

Background Patients with known or suspected coronary disease are often investigated to facilitate risk assessment. We sought to examine the cost-effectiveness of strategies based on exercise echocardiography and exercise electrocardiography. Methods and results We studied 7656 patients undergoing exercise testing; of whom half underwent exercise echocardiography. Risk was defined with the Duke treadmill score for those undergoing exercise electrocardiography alone, and by the extent of ischaemia by exercise echocardiography. Cox proportional hazards models, risk adjusted for pretest likelihood of coronary artery disease, were used to estimate time to cardiac death or myocardial infarction. Costs (including diagnostic and revascularisation procedures, hospitalisations, and events) were calculated, inflation-corrected to year 2000 using Medicare trust fund rates and discounted at a rate of 5%. A decision model was employed to assess the marginal cost effectiveness (cost/life year saved) of exercise echo compared with exercise electrocardiography. Exercise echocardiography identified more patients as low-risk (51% vs 24%, p<0.001), and fewer as intermediate- (27% vs 51%, p<0.001) and high-risk (22% vs 4%); survival was greater in low- and intermediate- risk and less in high-risk patients. Although initial procedural costs and revascularisation costs (in intermediate- high risk patients) were greater, exercise echocardiography was associated with a greater incremental life expectancy (0.2 years) and a lower use of additional diagnostic procedures when compared with exercise electrocardiography (especially in lower risk patients). Using decision analysis, exercise echocardiography (Euro 2615/life year saved) was more cost effective than exercise electrocardiography. Conclusion Exercise echocardiography may enhance cost-effectiveness for the detection and management of at risk patients with known or suspected coronary disease. (C) 2003 Published by Elsevier Science Ltd on behalf of The European Society of Cardiology.

Applying ontologies to business and systems modelling techniques and perspectives: Lessons learned

For many years in the area of business systems analysis and design, practitioners and researchers alike have been searching for some comprehensive basis on which to evaluate, compare, and engineer techniques that are promoted for use in the modelling of systems' requirements. To date, while many frameworks, factors, and facets have been forthcoming, none appear to be based on a sound theory. In light of this dilemma, over the last 10 years, attention has been devoted by researchers to the use of ontology to provide some theoretical basis for the advancement of the business systems modelling discipline. This paper outlines how we have used a particular ontology for this purpose over the last five years. In particular we have learned that the understandability and the applicability of the selected ontology must be clear for IS professionals, the results of any ontological evaluation must be tempered by economic efficiency considerations of the stakeholders involved, and ontologies may have to be focused for the business purpose and type of user involved in the modelling situation.

Cost of an emerging epidemic: an economic analysis of atrial fibrillation in the UK

Objective: To evaluate the cost of atrial fibrillation (AF) to health and social services in the UK in 1995 and, based on epidemiological trends, to project this estimate to 2000. Design, setting, and main outcome measures: Contemporary estimates of health care activity related to AF were applied to the whole population of the UK on an age and sex specific basis for the year 1995. The activities considered ( and costs calculated) were hospital admissions, outpatient consultations, general practice consultations, and drug treatment ( including the cost of monitoring anticoagulant treatment). By adjusting for the progressive aging of the British population and related increases in hospital admissions, the cost of AF was also projected to the year 2000. Results: There were 534 000 people with AF in the UK during 1995. The direct'' cost of health care for these patients was pound 244 million (similar toE350 million) or 0.62% of total National Health Service ( NHS) expenditure. Hospitalisations and drug prescriptions accounted for 50% and 20% of this expenditure, respectively. Long term nursing home care after hospital admission cost an additional pound46.4 million (similar toE66 million). The direct cost of AF rose to pound459 million (similar toE655 million) in 2000, equivalent to 0.97% of total NHS expenditure based on 1995 figures. Nursing home costs rose to pound111 million (similar toE160 million). Conclusions: AF is an extremely costly public health problem.

Genetic and economic analysis of a targeted marker-assisted wheat breeding strategy

The advent of molecular markers as a tool to aid selection has provided plant breeders with the opportunity to rapidly deliver superior genetic solutions to problems in agricultural production systems. However, a major constraint to the implementation of marker-assisted selection (MAS) in pragmatic breeding programs in the past has been the perceived high relative cost of MAS compared to conventional phenotypic selection. In this paper, computer simulation was used to design a genetically effective and economically efficient marker-assisted breeding strategy aimed at a specific outcome. Under investigation was a strategy involving the integration of both restricted backcrossing and doubled haploid (DH) technology. The point at which molecular markers are applied in a selection strategy can be critical to the effectiveness and cost efficiency of that strategy. The application of molecular markers was considered at three phases in the strategy: allele enrichment in the BC1F1 population, gene selection at the haploid stage and the selection for recurrent parent background of DHs prior to field testing. Overall, incorporating MAS at all three stages was the most effective, in terms of delivering a high frequency of desired outcomes and at combining the selected favourable rust resistance, end use quality and grain yield alleles. However, when costs were included in the model the combination of MAS at the BC1F1 and haploid stage was identified as the optimal strategy. A detailed economic analysis showed that incorporation of marker selection at these two stages not only increased genetic gain over the phenotypic alternative but actually reduced the over all cost by 40%.

Does pharmacogenomics provide an ethical challenge to the utilisation of cost-effectiveness analysis by public health systems?

Pharmacogenomics promotes an understanding of the genetic basis for differences in efficacy or toxicity of drugs in different individuals. Implementation of the outcomes of pharmacogenomic research into clinical practice presents a number of difficulties for healthcare. This paper aims to highlight one of the Unique ethical challenges which pharmacogenomics presents for the utilisation of cost-effectiveness analysis by public health systems. This paper contends that pharmacogenomics provides a challenge to fundamental principles which underlie most systems for deciding which drugs should be publicly subsidised. Pharmacogenomics brings into focus the conflict between equality and utility in the context of using cost-effectiveness analysis to aid distribution of a limited national drug budget.

Carvedilol reduces the costs of medical care in severe heart failure: An economic analysis of the COPERNICUS study applied to the United Kingdom

Background: The aim of this study was to determine the effects of carvedilol on the costs related to the treatment of severe chronic heart failure (CHF). Methods: Costs for the treatment for heart failure within the National Health Service (NHS) in the United Kingdom (UK) were applied to resource utilisation data prospectively collected in all patients randomized into the Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) Study. Unit-specific, per them (hospital bed day) costs were used to calculate expenditures due to hospitalizations. We also included costs of carvedilol treatment, general practitioner surgery/office visits, hospital out-patient clinic visits and nursing home care based on estimates derived from validated patterns of clinical practice in the UK. Results: The estimated cost of carvedilol therapy and related ambulatory care for the 1156 patients assigned to active treatment was 530,771 pound (44.89 pound per patient/month of follow-up). However, patients assigned to carvedilol were hospitalised less often and accumulated fewer and less expensive days of admission. Consequently, the total estimated cost of hospital care was 3.49 pound million in the carvedilol group compared with 4.24 pound million for the 1133 patients in the placebo arm. The cost of post-discharge care was also less in the carvedilol than in the placebo group (479,200 pound vs. 548,300) pound. Overall, the cost per patient treated in the carvedilol group was 3948 pound compared to 4279 pound in the placebo group. This equated to a cost of 385.98 pound vs. 434.18 pound, respectively, per patient/month of follow-up: an 11.1% reduction in health care costs in favour of carvedilol. Conclusions: These findings suggest that not only can carvedilol treatment increase survival and reduce hospital admissions in patients with severe CHF but that it can also cut costs in the process.