Simban Acs - Academia.edu (original) (raw)

Papers by Simban Acs

Hungary's imminent entrance into the EU calls for a farm-level financial support system aimi... more Hungary's imminent entrance into the EU calls for a farm-level financial support system aiming at combining agricultural production with nature conservation targets. Within the Hungarian National Agri-environmental Programme (NAEP) for the Environmentally Sensitive Areas, a payment system was developed. For each individual region the amount of support for every environmentally friendly farming prescription package (tier) was established using the support calculation methodology of the EU. The purpose of this paper is to analyse the impact of the packages on the income of an individual mixed farm. In contrast to many other studies, in the current study the analysis was carried out with the context of the whole farm, taking into consideration the entire production structure. The amount of support which the farmer needs to sign up for a contract turned out to be quite different from the actual payments done by the Hungarian government.

Biological Agriculture & Horticulture, 2007

Publikationsansicht. 23240977. Comparison of conventional and organic arable farming systems in t... more Publikationsansicht. 23240977. Comparison of conventional and organic arable farming systems in the Netherlands by means of bio-economic modelling (2007). ...

Hill farming in UK is experiencing very difficult economic circumstances and many farmers rely on... more Hill farming in UK is experiencing very difficult economic circumstances and many farmers rely on subsidies provided by the government for a large fraction of their income. The Peak District National Park is used as a case study to examine how farmers might respond to current policy changes – in particular, the move from area- and headage-based payments to the

Recent decades have witnessed substantial losses in biodiversity in Europe, principally driven by... more Recent decades have witnessed substantial losses in biodiversity in Europe, principally driven by the ecological changes associated with intensification of agricultural production. These changes especially affected the biodiversity in the marginal areas, such as the uplands in UK, since the habitat change was greater than in lowland zones. Livestock farming is the main land use in these areas, and economic viability of these farmers substantially relies on income coming from agricultural subsidies and different agri-environmental payments. The production decisions are influenced by these incentives and those have a subsequent effect on biodiversity. In order to address the problem of economic viability of farmers together with its impact on biodiversity conservation, we developed ecological-economic models for four typical farm types in the Peak District National Park in UK. We analyse the effect of policies on upland avian densities, focusing on decoupling and agri-environment schemes. The results show that the impact of these policies individually, which sometimes opposite, differs from their aggregated effect. It also shows that the effect differs across farm types. This means that from a biodiversity point of view whatever future policy options are chosen will result in winners and losers.

Recent decades have witnessed substantial losses in biodiversity in Europe, partly driven by the ... more Recent decades have witnessed substantial losses in biodiversity in Europe, partly driven by the ecological changes associated with intensification of agricultural production. These changes have particularly affected biodiversity in marginal areas, such as the uplands in UK, since habitat change has been greater than in lowland zones. Livestock farming is the main land use in these areas, and economic viability of farmers substantially relies on income coming from agricultural subsidies and agrienvironmental payments. The production decisions have an effect on biodiversity, although the precise links are subject of much debate. To assess the effects of policy changes on farm incomes and biodiversity, we developed ecological-economic models for three typical farm types in the Peak District National Park in UK. We analyse the effect of decoupling and agri-environment schemes on birds. The results show that the impact of these policies varies across farm types and across biodiversity indicator. This means that from a biodiversity point of view whatever future policy options are chosen will result in winners and losers.

Scientific workflows are common in biomedical research, particularly for molecular docking simula... more Scientific workflows are common in biomedical research, particularly for molecular docking simulations such as those used in drug discovery. Such workflows typically involve data distribution between computationally demanding stages which are usually mapped onto large scale compute resources. Volunteer or Desktop Grid (DG) computing can provide such infrastructure but has limitations resulting from the heterogeneous nature of the compute nodes.

Recent decades have witnessed substantial losses of biodiversity in Europe, partly driven by the ... more Recent decades have witnessed substantial losses of biodiversity in Europe, partly driven by the ecological changes associated with intensification of agricultural production. These changes have particularly affected avian (bird) diversity in marginal areas such as the uplands of the UK. Future trends for upland birds will likely be impacted by changes in agricultural support regimes, such as those currently envisaged in ongoing reforms of the Common Agricultural Policy. We developed integrated ecological-economic models, using seven different indicators of biodiversity based on avian species richness and individual bird densities. The models represent six different types of farms which are typical for the UK uplands, and were used to assess the outcomes of different agricultural futures. Our results show that the impacts of these future agricultural scenarios on farm incomes, land use and biodiversity are very diverse across policy scenarios and farm types. Moreover, each policy scenario produces unequal distributions of farm income changes and gains and losses in alternative biodiversity indicators. This shows that generalisations of the effects of policy and pricing changes on farm incomes, land uses and biodiversity can be misleading. Our results also suggest that a focus on umbrella species or biodiversity indicators (such as total species richness) can miss important compositional effects.

Modern farmed landscapes have witnessed substantial losses in biodiversity principally driven by ... more Modern farmed landscapes have witnessed substantial losses in biodiversity principally driven by the ecological changes associated with agricultural intensification. The causes of declines are often well described, but current management practices seem unlikely to deliver the EU-wide policy objective of halting biodiversity losses. 2. Available evidence suggests that property-scale factors can be influential in shaping patterns of biodiversity; however, they are rarely included in studies. Using 44 upland farms in the Peak District, northern England, we investigate the roles of ecological, agricultural and socioeconomic factors in determining avian species richness, for the first time incorporating information from all three influences. 3. Although we might expect that habitat quality would be the main factor affecting species richness, these variables had little influence. The landscape context of each property was unimportant in explaining any of the three measures of species richness (Total , Upland and Conservation Concern) used here. Within-property habitat quality did explain 42% of the variation in richness of upland specialist species, but had no influence on Total or Conservation Concern Richness. 4. Socioeconomic circumstances of farms alone accounted for 24% of the variation in Total Richness, with land tenure and labour inputs important predictors of avian diversity. However, net income, rental value and the level of Agri-Environment Scheme (AES) payments did not play a role in predicting species richness. 5. Farm management variables, including many of the main prescriptions outlined in AES, accounted for 23% of the variation in the richness of species of Conservation Concern, but less than 10% for Total Richness. However, no farm management variable alone was shown to offer better predictive power of avian species richness than random. 6. Synthesis and applications. The agricultural landscape is managed by a mosaic of landowners, all of whom can influence biodiversity conservation. We demonstrate that variation at the propertyscale in habitat, management and socio-economics can feed into determining patterns of biodiversity. Currently, farmland conservation policy largely assumes that socioeconomic barriers and financial costs of implementing conservation measures are constant. Incorporating a consideration of the varying circumstances of individual properties into policy design is likely to result in substantial biodiversity gains.

1. The 20th century has witnessed substantial increases in the intensity of agricultural land man... more 1. The 20th century has witnessed substantial increases in the intensity of agricultural land management, much of which has been driven by policies to enhance food security and production. The knock-on effects in agriculturally dominated landscapes include habitat degradation and biodiversity loss. We examine long-term patterns of agricultural and habitat change at a regional scale, using the Peak District of northern England as a case study. As stakeholders are central to the implementation of successful land-use policy, we also assess their perceptions of historical changes. 2. In the period 1900 to 2000, there was a fivefold rise in sheep density, along with higher cattle density. We found a reduction in the number of farms, evidence of a shift in land ownership patterns, and increased agricultural specialization, including the virtual disappearance of upland arable production. 3. Despite previous studies showing a substantial loss in heather cover, we found that there had been no overall change in the proportion of land covered by dwarf shrub moor. Nonetheless, turnover rates were high, with only 55% of sampled sites maintaining dwarf shrub moor coverage between 1913 and 2000. 4. Stakeholders identified many of the changes revealed by the historical data, such as increased sheep numbers, fewer farms and greater specialization. However, other land-use changes were not properly described. For instance, although there had been no overall change in the proportion of dwarf shrub moor and the size of the rural labour force had not fallen, stakeholders reported a decline in both. Spatial heterogeneity of the changes, shifting baselines and problems with historical data sources might account for some of these discrepancies. 5. Synthesis and applications. A marked increase in sheep numbers, combined with general agricultural intensification, have been the dominant land-use processes in the Peak District during the 20th century. Stakeholders only correctly perceived some land-use changes. Policy and management objectives should therefore be based primarily on actual historical evidence. However, understanding stakeholder perceptions and how they differ from, or agree with, the available evidence will contribute to the successful uptake of land management policies and partly determine the costs of policy implementation.

Agricultural Systems, 2007

Several studies show that organic farming is more profitable than conventional farming. However, ... more Several studies show that organic farming is more profitable than conventional farming. However, in reality not many farmers convert to organic farming. Policy makers and farmers do not have clear insight into factors which hamper or stimulate the conversion to organic farming. The objective of this paper is to develop a dynamic linear programming model to analyse the effects of different limiting factors on the conversion process of farms over time. The model is developed for a typical arable farm in The Netherlands central clay region, and is based on two static liner programming models (conventional and organic). The objective of the model is to maximise the net present value over a 10-year planning horizon. The results of the analysis of a basic scenario show that conversion to organic farming is more profitable than staying conventional. In order to arrive at the actual profitable phase of organic farming, the farmer has to pass through the economically difficult 2-year conversion period. Sensitivity analysis shows that if depreciation is 25% higher than conventional fixed costs due to machinery made superfluous by conversion, conversion is less profitable than staying conventional. Also the availability of hired labour, which can be constrained in peak periods, has a strong effect on the cropping plan and the amount of area converted. Further analysis shows that a slight drop (2%) in organic prices lowers the labour income of the farmer and makes conversion less profitable than conventional farming. For farmers, a minimum labour income can be required to 'survive'. The analysis shows that constraint on minimum labour income makes stepwise conversion the best way for farmers to overcome economic difficulties during conversion.

Cloud computing represents a promising computing paradigm where computing resources have to be al... more Cloud computing represents a promising computing paradigm where computing resources have to be allocated to software for their execution. Self-manageable Cloud infrastructures are required to achieve that level of flexibility on one hand, and to comply to users' requirements specified by means of Service Level Agreements (SLAs) on the other. Such infrastructures should automatically respond to changing component, workload, and environmental conditions minimizing user interactions with the system and preventing violations of agreed SLAs. However, identification of sources responsible for the possible SLA violation and the decision about the reactive actions necessary to prevent SLA violation is far from trivial. First, in this paper we present a novel approach for mapping low-level resource metrics to SLA parameters necessary for the identification of failure sources. Second, we devise a layered Cloud architecture for the bottom-up propagation of failures to the layer, which can react to sensed SLA violation threats. Moreover, we present a communication model for the propagation of SLA violation threats to the appropriate layer of the Cloud infrastructure, which includes negotiators, brokers, and automatic service deployer.

Njas-wageningen Journal of Life Sciences, 2005

Literature shows a significant development of organic farming in Europe but with considerable dif... more Literature shows a significant development of organic farming in Europe but with considerable differences between countries. These depend on general agricultural policy (the set of regulations and laws), specific policy incentives, and also on differences in consumer behaviour. This paper reviews scientific literature on the evaluation of the technical, economic and environmental aspects of conversion from conventional towards organic production.

Hungary's imminent entrance into the EU calls for a farm-level financial support system aimi... more Hungary's imminent entrance into the EU calls for a farm-level financial support system aiming at combining agricultural production with nature conservation targets. Within the Hungarian National Agri-environmental Programme (NAEP) for the Environmentally Sensitive Areas, a payment system was developed. For each individual region the amount of support for every environmentally friendly farming prescription package (tier) was established using the support calculation methodology of the EU. The purpose of this paper is to analyse the impact of the packages on the income of an individual mixed farm. In contrast to many other studies, in the current study the analysis was carried out with the context of the whole farm, taking into consideration the entire production structure. The amount of support which the farmer needs to sign up for a contract turned out to be quite different from the actual payments done by the Hungarian government.

Biological Agriculture & Horticulture, 2007

Publikationsansicht. 23240977. Comparison of conventional and organic arable farming systems in t... more Publikationsansicht. 23240977. Comparison of conventional and organic arable farming systems in the Netherlands by means of bio-economic modelling (2007). ...

Hill farming in UK is experiencing very difficult economic circumstances and many farmers rely on... more Hill farming in UK is experiencing very difficult economic circumstances and many farmers rely on subsidies provided by the government for a large fraction of their income. The Peak District National Park is used as a case study to examine how farmers might respond to current policy changes – in particular, the move from area- and headage-based payments to the

Recent decades have witnessed substantial losses in biodiversity in Europe, principally driven by... more Recent decades have witnessed substantial losses in biodiversity in Europe, principally driven by the ecological changes associated with intensification of agricultural production. These changes especially affected the biodiversity in the marginal areas, such as the uplands in UK, since the habitat change was greater than in lowland zones. Livestock farming is the main land use in these areas, and economic viability of these farmers substantially relies on income coming from agricultural subsidies and different agri-environmental payments. The production decisions are influenced by these incentives and those have a subsequent effect on biodiversity. In order to address the problem of economic viability of farmers together with its impact on biodiversity conservation, we developed ecological-economic models for four typical farm types in the Peak District National Park in UK. We analyse the effect of policies on upland avian densities, focusing on decoupling and agri-environment schemes. The results show that the impact of these policies individually, which sometimes opposite, differs from their aggregated effect. It also shows that the effect differs across farm types. This means that from a biodiversity point of view whatever future policy options are chosen will result in winners and losers.

Recent decades have witnessed substantial losses in biodiversity in Europe, partly driven by the ... more Recent decades have witnessed substantial losses in biodiversity in Europe, partly driven by the ecological changes associated with intensification of agricultural production. These changes have particularly affected biodiversity in marginal areas, such as the uplands in UK, since habitat change has been greater than in lowland zones. Livestock farming is the main land use in these areas, and economic viability of farmers substantially relies on income coming from agricultural subsidies and agrienvironmental payments. The production decisions have an effect on biodiversity, although the precise links are subject of much debate. To assess the effects of policy changes on farm incomes and biodiversity, we developed ecological-economic models for three typical farm types in the Peak District National Park in UK. We analyse the effect of decoupling and agri-environment schemes on birds. The results show that the impact of these policies varies across farm types and across biodiversity indicator. This means that from a biodiversity point of view whatever future policy options are chosen will result in winners and losers.

Scientific workflows are common in biomedical research, particularly for molecular docking simula... more Scientific workflows are common in biomedical research, particularly for molecular docking simulations such as those used in drug discovery. Such workflows typically involve data distribution between computationally demanding stages which are usually mapped onto large scale compute resources. Volunteer or Desktop Grid (DG) computing can provide such infrastructure but has limitations resulting from the heterogeneous nature of the compute nodes.

Recent decades have witnessed substantial losses of biodiversity in Europe, partly driven by the ... more Recent decades have witnessed substantial losses of biodiversity in Europe, partly driven by the ecological changes associated with intensification of agricultural production. These changes have particularly affected avian (bird) diversity in marginal areas such as the uplands of the UK. Future trends for upland birds will likely be impacted by changes in agricultural support regimes, such as those currently envisaged in ongoing reforms of the Common Agricultural Policy. We developed integrated ecological-economic models, using seven different indicators of biodiversity based on avian species richness and individual bird densities. The models represent six different types of farms which are typical for the UK uplands, and were used to assess the outcomes of different agricultural futures. Our results show that the impacts of these future agricultural scenarios on farm incomes, land use and biodiversity are very diverse across policy scenarios and farm types. Moreover, each policy scenario produces unequal distributions of farm income changes and gains and losses in alternative biodiversity indicators. This shows that generalisations of the effects of policy and pricing changes on farm incomes, land uses and biodiversity can be misleading. Our results also suggest that a focus on umbrella species or biodiversity indicators (such as total species richness) can miss important compositional effects.

Modern farmed landscapes have witnessed substantial losses in biodiversity principally driven by ... more Modern farmed landscapes have witnessed substantial losses in biodiversity principally driven by the ecological changes associated with agricultural intensification. The causes of declines are often well described, but current management practices seem unlikely to deliver the EU-wide policy objective of halting biodiversity losses. 2. Available evidence suggests that property-scale factors can be influential in shaping patterns of biodiversity; however, they are rarely included in studies. Using 44 upland farms in the Peak District, northern England, we investigate the roles of ecological, agricultural and socioeconomic factors in determining avian species richness, for the first time incorporating information from all three influences. 3. Although we might expect that habitat quality would be the main factor affecting species richness, these variables had little influence. The landscape context of each property was unimportant in explaining any of the three measures of species richness (Total , Upland and Conservation Concern) used here. Within-property habitat quality did explain 42% of the variation in richness of upland specialist species, but had no influence on Total or Conservation Concern Richness. 4. Socioeconomic circumstances of farms alone accounted for 24% of the variation in Total Richness, with land tenure and labour inputs important predictors of avian diversity. However, net income, rental value and the level of Agri-Environment Scheme (AES) payments did not play a role in predicting species richness. 5. Farm management variables, including many of the main prescriptions outlined in AES, accounted for 23% of the variation in the richness of species of Conservation Concern, but less than 10% for Total Richness. However, no farm management variable alone was shown to offer better predictive power of avian species richness than random. 6. Synthesis and applications. The agricultural landscape is managed by a mosaic of landowners, all of whom can influence biodiversity conservation. We demonstrate that variation at the propertyscale in habitat, management and socio-economics can feed into determining patterns of biodiversity. Currently, farmland conservation policy largely assumes that socioeconomic barriers and financial costs of implementing conservation measures are constant. Incorporating a consideration of the varying circumstances of individual properties into policy design is likely to result in substantial biodiversity gains.

1. The 20th century has witnessed substantial increases in the intensity of agricultural land man... more 1. The 20th century has witnessed substantial increases in the intensity of agricultural land management, much of which has been driven by policies to enhance food security and production. The knock-on effects in agriculturally dominated landscapes include habitat degradation and biodiversity loss. We examine long-term patterns of agricultural and habitat change at a regional scale, using the Peak District of northern England as a case study. As stakeholders are central to the implementation of successful land-use policy, we also assess their perceptions of historical changes. 2. In the period 1900 to 2000, there was a fivefold rise in sheep density, along with higher cattle density. We found a reduction in the number of farms, evidence of a shift in land ownership patterns, and increased agricultural specialization, including the virtual disappearance of upland arable production. 3. Despite previous studies showing a substantial loss in heather cover, we found that there had been no overall change in the proportion of land covered by dwarf shrub moor. Nonetheless, turnover rates were high, with only 55% of sampled sites maintaining dwarf shrub moor coverage between 1913 and 2000. 4. Stakeholders identified many of the changes revealed by the historical data, such as increased sheep numbers, fewer farms and greater specialization. However, other land-use changes were not properly described. For instance, although there had been no overall change in the proportion of dwarf shrub moor and the size of the rural labour force had not fallen, stakeholders reported a decline in both. Spatial heterogeneity of the changes, shifting baselines and problems with historical data sources might account for some of these discrepancies. 5. Synthesis and applications. A marked increase in sheep numbers, combined with general agricultural intensification, have been the dominant land-use processes in the Peak District during the 20th century. Stakeholders only correctly perceived some land-use changes. Policy and management objectives should therefore be based primarily on actual historical evidence. However, understanding stakeholder perceptions and how they differ from, or agree with, the available evidence will contribute to the successful uptake of land management policies and partly determine the costs of policy implementation.

Agricultural Systems, 2007

Several studies show that organic farming is more profitable than conventional farming. However, ... more Several studies show that organic farming is more profitable than conventional farming. However, in reality not many farmers convert to organic farming. Policy makers and farmers do not have clear insight into factors which hamper or stimulate the conversion to organic farming. The objective of this paper is to develop a dynamic linear programming model to analyse the effects of different limiting factors on the conversion process of farms over time. The model is developed for a typical arable farm in The Netherlands central clay region, and is based on two static liner programming models (conventional and organic). The objective of the model is to maximise the net present value over a 10-year planning horizon. The results of the analysis of a basic scenario show that conversion to organic farming is more profitable than staying conventional. In order to arrive at the actual profitable phase of organic farming, the farmer has to pass through the economically difficult 2-year conversion period. Sensitivity analysis shows that if depreciation is 25% higher than conventional fixed costs due to machinery made superfluous by conversion, conversion is less profitable than staying conventional. Also the availability of hired labour, which can be constrained in peak periods, has a strong effect on the cropping plan and the amount of area converted. Further analysis shows that a slight drop (2%) in organic prices lowers the labour income of the farmer and makes conversion less profitable than conventional farming. For farmers, a minimum labour income can be required to 'survive'. The analysis shows that constraint on minimum labour income makes stepwise conversion the best way for farmers to overcome economic difficulties during conversion.

Cloud computing represents a promising computing paradigm where computing resources have to be al... more Cloud computing represents a promising computing paradigm where computing resources have to be allocated to software for their execution. Self-manageable Cloud infrastructures are required to achieve that level of flexibility on one hand, and to comply to users' requirements specified by means of Service Level Agreements (SLAs) on the other. Such infrastructures should automatically respond to changing component, workload, and environmental conditions minimizing user interactions with the system and preventing violations of agreed SLAs. However, identification of sources responsible for the possible SLA violation and the decision about the reactive actions necessary to prevent SLA violation is far from trivial. First, in this paper we present a novel approach for mapping low-level resource metrics to SLA parameters necessary for the identification of failure sources. Second, we devise a layered Cloud architecture for the bottom-up propagation of failures to the layer, which can react to sensed SLA violation threats. Moreover, we present a communication model for the propagation of SLA violation threats to the appropriate layer of the Cloud infrastructure, which includes negotiators, brokers, and automatic service deployer.

Njas-wageningen Journal of Life Sciences, 2005

Literature shows a significant development of organic farming in Europe but with considerable dif... more Literature shows a significant development of organic farming in Europe but with considerable differences between countries. These depend on general agricultural policy (the set of regulations and laws), specific policy incentives, and also on differences in consumer behaviour. This paper reviews scientific literature on the evaluation of the technical, economic and environmental aspects of conversion from conventional towards organic production.