An environmental systems analysis of greenhouse horticulture in the Netherlands : the tomato case

Objective of the thesisThe greenhouse horticulture sector in the Netherlands covers about 10,000 hectares and produces vegetables, cut flowers and pot plants. This agricultural sector is of social and economic importance because of its annual production value, export earnings and the employment it provides. Cultivation in greenhouses, however, is characterised by high inputs of energy, fertilisers and chemical biocides, which contribute to several environmental problems. Through technical options, these environmental problems can be reduced.The general objective of this thesis is to identify technical options to reduce the environmental impact of greenhouse horticulture in the Netherlands and to evaluate their cost-effectiveness. The study focuses on tomato cultivation and on the environmental problems of global warming, acidification, eutrophication, dispersion of toxic biocides and the production of waste. The method of environmental systems analysis is used as a tool for the assessment of technical options for reducing the impact of the sector on multiple environmental problems. A side-objective is to discuss the usefulness of environmental systems analysis in such analyses. System boundaries and model componentsThe first step of the analysis is the definition of the system boundaries and the determination of the system components. To this end we carried out a limited environmental life cycle analysis (LCA) for tomato cultivation under glass and its contribution to global warming, acidification and eutrophication. We focused on these three environmental problems because of the interrelations between the underlying processes and the emissions. We quantified the emissions of first-order processes (these are activities such as the use of natural gas and fertilisers) and second-order processes (these are industrial activities such as the production of electricity and fertilisers). Results indicated that, in general, the emissions of first-order processes exceed the emissions of second-order processes. However, in some cases the off-farm emissions were relatively high. For example, the production of electricity and rock wool contribute almost 25% to total acidifying emissions. We concluded that a study of the environmental impact of tomato cultivation in the Netherlands needs to consider CO 2 emissions from the use of natural gas and the production of electricity, NO x emissions from the use of natural gas and fertilisers, and from the production of electricity and rock wool, and losses of nitrogen and phosphorus from the use of fertilisers. In addition, we considered biocide use and biocide emissions to the environment and the production of waste. We argue that a profound study of the definition of system boundaries is worthwhile and provides a better understanding of the system. Model buildingA model was developed that can be used to quantify the environmental impact of tomato cultivation in the Netherlands and that can be used to evaluate the cost-effectiveness of technical options for reducing the environmental impact. The model calculates the environmental impact as a function of the activities, emission factors and reduction options applied. The impact is quantified by using environmental pressure indicators mainly. The activities include the use of natural gas, fertilisers, biocides and rock wool, as well as the production of electricity and rock wool. The model calculates the environmental impacts through global warming (emission of carbon dioxide in kg CO 2 ), acidification (emission of nitrogen oxides in kg NO x ), eutrophication (emission of eutrophying compound in kg phosphate (PO 4 )-equivalents), dispersion of toxic compounds (indicated by the use of biocide in kg active ingredients and the emission of biocides quantified by the biocide-air-emission score) and the production of waste (kg waste). The model includes 22 groups of technical options that reduce the activity levels (e.g. the use of gas) and/or the emission factors (e.g. NO x emissions from gas use). The model accounts for important side effects of the reduction options on the tomato production and on the levels of the activities and other emissions. The reduction costs are calculated as annual costs per hectare and include the annualised investment costs, operational costs and variable costs of the technical options applied (e.g. saving in gas use and effects on the production level). The model selects the most cost-effective combinations from all possible combinations of options. Exploration of the modelWe explored the model for a hypothetical reference situation in which none of the technical reduction options were applied. The model calculations, for instance, showed that most of the profitable options are related to a reduction in the use of gas. The combi-condenser and heat buffer were selected by the model in all cost-effective combinations of options. The cost curves for the hypothetical reference situation illustrate the costs of combinations of options for different reductions in emissions. The cost curves indicated that considerable reduction of the environmental impact could be achieved at net zero costs, but that increasing reduction of the environmental impact resulted in rapidly increasing costs.The model calculations show that reducing the emissions for one compound may also affect the emissions of other pollutants (the above-mentioned side effects). This is especially the case for the reduction of emissions of CO 2 and NO x . Furthermore, the options for reducing emissions of eutrophying compounds may affect the emissions of CO 2 and biocides into the atmosphere and vice versa.To further explore the model we carried out a sensitivity analysis. The model results were found to be sensitive to changes in the values of the emissions factors for biocides into the atmosphere. These emission factors are relatively uncertain. We point out that more research is needed on the quantification of the emission of biocides from greenhouse horticulture. The model results are also sensitive to the inclusion or exclusion of NO x as an eutrophying compound, and to changes in prices, in particular to changes in the price of natural gas. The higher the gas price the higher the savings in costs for each m 3reduction in gas use; consequently, the more expensive reduction options are selected by the model in cost-effective combinations of options.We applied five different methods for multi-criteria analysis (MCA) in order to evaluate the cost-effectiveness of the reduction options in reducing several environmental problems simultaneously. The results of these MCA methods differed considerably. They resulted in different numbers of cost-effective combinations of options and in different options selected in the cost-effective combinations. On the other hand, the use of multi-criteria analysis appeared to be useful for tracing robust reduction options. These robust reduction options are options that were always selected in the cost-effective combinations of options, independent of the multi-criteria method used. Robust reduction options for tomato cultivation include the combi-condenser, heat buffer (both improving energy efficiency), high pressure cleaner (reducing the biocide use) and regional schemes for composting organic waste (reducing the amount of waste disposed). Many different MCA methods are available and the choice of the methodology is subjective. For this reason, and because of the observed differences in the results of the five MCA methods, it may be recommended to use more than one method for MCA in (environmental) research to gain insight into the effect of the choice of MCA method used and to trace robust reduction options. Model application and optimisation analysisWe analysed cost-optimal strategies to meet national environmental targets for tomato cultivation in the Netherlands. We accounted for some of the heterogeneity of Dutch tomato cultivation (1220 hectare) by defining three farm types: Innovators (245 hectare), In-Betweens (730 hectare) and Low-Costs (245 hectare). The main differences between these farm types are the size of the greenhouse, the production volume, the intensity of the production (and therefore the activity levels) and the application of emission reduction options. Innovators produce tomatoes in relatively large new greenhouses and apply several technical reduction options. Low-Costs farmers produce tomatoes in relatively small old greenhouses and apply few options. The In-Betweens occupy the middle ground between the two other farm types. Data were based on the 1995 situation.Two types of optimisation analysis were performed. The first type aimed at minimising the costs to achieve selected environmental targets for the tomato cultivation sector as a whole. The environmental targets for tomato cultivation are based on current policy for Dutch greenhouse horticulture. In the second type of optimisation analysis we analysed the extent to which the environmental impact could be reduced under different cost constraints. In both types of optimisation analysis we calculated the areas on which cost-effective combinations of options are applied on the different farm types to achieve the optimal situation.The results of the optimisation analysis indicate that current policy targets for the tomato sector for global warming (24% reduction in CO 2 emission) and eutrophication (45% reduction in the emissions of eutrophying compounds) can be achieved at net negative costs. The targets for biocide emissions to the atmosphere (a reduction of 38% from 1995 levels) and energy efficiency improvement (65% over 1980 levels) can be achieved at relatively high costs. The target for the reduction in biocide use in 2010 cannot be achieved by the technical reduction options analysed. When model results indicate that the costs of achieving a certain target are negative at the national level, this may not be necessarily the case for all individual firms. Model results indicate that the most cost-effective solutions are often achieved at the national levels by applying relatively expensive options to part of the tomato cultivation area and relatively cheap options to other parts of the area. In these solutions, the costs fall mainly on the farm types Low-Costs and In-Betweens.We also calculated cost-optimal ways to achieve the above mentioned policy targets for tomato cultivation sector simultaneously. The model results indicate that the net costs of achieving all targets simultaneously are negative. We observed that the model selects other combinations of reduction options in the multiple target optimisation than for the optimisation of the individual targets. Most noticeable in this respect are the selection of a fixed screen and double glass in the roof in combination with the no-windows options, in addition to the more generally applied options such as the combi-condenser, heat buffer, Econaut, strips around window panes and regional composting.The results of the second type of the optimisation analysis were used to develop cost curves. These curves illustrate the costs of different levels of national emission reduction for tomato cultivation and were developed for all individual environmental problems analysed as well as for the integrated environmental impact using the five multi-criteria methods. The cost curves illustrate that, for the 1995 situation, for each environmental problem considered about 20% of the impact from tomato cultivation in the Netherlands can be reduced at net zero costs. Extrapolating the results to total greenhouse horticultureExtrapolating the results of the tomato case to the whole greenhouse sector is not easy because of crop specific characteristics. Most importantly, tomato cultivation uses relatively more natural gas, fertilisers and rock wool than the greenhouse horticulture sector as a whole, but less electricity. Furthermore, tomatoes are relatively sensitive to a reduction in radiation (light) that may result from the application of some reduction options, such as screens. These differences may have an important effect on the cost-effectiveness of the options. Despite these differences we discussed the possibilities of achieving the environmental targets for greenhouse horticulture in 2010, based on the tomato case. We argue that most of the environmental targets probably can be achieved, but that targets for the emission of eutrophying compounds and biocides to the atmosphere will probably be difficult to achieve. A more thorough analysis is needed to draw more definite conclusions on the reduction of the environmental impact of greenhouse horticulture as a whole. Environmental systems analysisThis thesis shows that environmental systems analysis can be useful for analysing complex problems concerning economic and environmental aspects. The environmental systems analysis procedure involves six steps: 1. definition of the system boundaries and the system components, 2. description of the objectives, 3. model building, 4. systems analysis, 5. selection of the optimal system, and 6. conclusions and documentation. It is our experience that these steps are performed interactively rather than in a strict sequence. Iteration and feedback occur to help refine the objectives, improve the model and adapt the constraints. In the analysis we applied a combination of tools, including environmental life cycle analysis, environmental indicators, cost-effectivety analysis and optimisation analysis, multi-criteria analysis and sensitivity analysis.</p

Development of an instrument to analyze organizational characteristics in multidisciplinary care pathways:the case of colorectal cancer

Background: To analyze the organization of multidisciplinary care pathways such as colorectal cancer care, an instrument was developed based on a recently published framework that was earlier used in analyzing (monodisciplinary) specialist cataract care from a lean perspective. Methods: The instrument was constructed using semi-structured interviews and direct observation of the colorectal care process based on a Rapid Plant Assessment. Six lean aspects that were earlier established that highly impact process design, were investigated: operational focus, autonomous work cell, physical lay-out of resources, multi-skilled team, pull planning and non-value adding activities. To test reliability, clarity and face validity of the instrument, a pilot study was performed in eight Dutch hospitals.ResultsIn the pilot it proved feasible to apply the instrument and generate the intended information. The instrument consisted of 83 quantitative and 24 qualitative items. Examples of results show differences in operational focus, number of patient visits needed for diagnosis, numbers of staff involved with treatment, the implementation of protocols and utilization of one-stop-shops. Identification of waste and non-value adding activities may need further attention. Based on feedback from involved clinicians the face validity was acceptable and the results provided useful feedback- and benchmark data. The instrument proved to be reliable and valid for broader implementation in Dutch health care. The limited number of cases made statistical analysis not possible and further validation studies may shed better light on variation. Conclusions: This paper demonstrates the use of an instrument to analyze organizational characteristics in colorectal cancer care from a lean perspective. Wider use might help to identify best organizational practices for colorectal surgery. In larger series the instrument might be used for in-depth research into the relation between organization and patient outcomes.Although we found no reason to adapt the underlying framework, recommendations were made for further development to enable use in different tumor- and treatment modalities and in larger (international) samples that allow for more advanced statistical analysis. Waste from defective care or from wasted human potential will need further elaboration of the instrumen

The Role of PIVKA-II as a Predictor of Early Hepatocellular Carcinoma Recurrence-Free Survival after Liver Transplantation in a Low Alpha-Fetoprotein Population

Introduction: AFP and the RETREAT score are currently used to predict HCC recurrence after LT. However, superior discriminating models are needed for low AFP populations. The aim of this study is to investigate the predictive value of PIVKA-II on recurrence-free survival after LT in a low AFP population and microvascular invasion on explant. Methods: A retrospective cohort study including all consecutive patients transplanted for HCC between 1989 and 2019 in the Erasmus MC University Medical Center in Rotterdam, the Netherlands, was used. AFP and PIVKA-II levels were determined in serum samples collected at the time of transplantation. Data on tumor load and microvascular invasion were retrieved from patients’ records. Results: The study cohort consisted of 121 patients, with HCC recurrence in 15 patients (12.4%). The median AFP was 7.7 ng/mL (4.4–20.2), and the median PIVKA-II was 72.0 mAU/mL (41.0–213.5). Patients with low AFP (≤8 ng/mL) and PIVKA-II (≤90 mAU/mL) had a 5-year recurrence-free survival of 100% compared to 85.7% in patients with low AFP and high PIVKA-II (p = 0.026). Regardless of the AFP level, patients within the Milan criteria (based on explant pathology) with a low PIVKA-II level had a 5-year recurrence-free survival of 100% compared to patients with a high PIVKA-II level of 81.1% (p = 0.002). In patients with microvascular invasion, the AUC for PIVKA-II was slightly better than the AUC for AFP (0.775 vs. 0.687). Conclusions: The dual model of PIVKA-II ≤ 90 mAU/mL with either AFP ≤ 8 ng/mL or with patients within the Milan criteria identifies patient groups which can be exempted from HCC surveillance after LT in a low AFP population. PIVKA-II may be a better predictor for explant microvascular invasion than AFP and could play a role in future models identifying LT candidates with the highest risk for HCC recurrence.</p

The Role of PIVKA-II as a Predictor of Early Hepatocellular Carcinoma Recurrence-Free Survival after Liver Transplantation in a Low Alpha-Fetoprotein Population

Introduction: AFP and the RETREAT score are currently used to predict HCC recurrence after LT. However, superior discriminating models are needed for low AFP populations. The aim of this study is to investigate the predictive value of PIVKA-II on recurrence-free survival after LT in a low AFP population and microvascular invasion on explant. Methods: A retrospective cohort study including all consecutive patients transplanted for HCC between 1989 and 2019 in the Erasmus MC University Medical Center in Rotterdam, the Netherlands, was used. AFP and PIVKA-II levels were determined in serum samples collected at the time of transplantation. Data on tumor load and microvascular invasion were retrieved from patients’ records. Results: The study cohort consisted of 121 patients, with HCC recurrence in 15 patients (12.4%). The median AFP was 7.7 ng/mL (4.4–20.2), and the median PIVKA-II was 72.0 mAU/mL (41.0–213.5). Patients with low AFP (≤8 ng/mL) and PIVKA-II (≤90 mAU/mL) had a 5-year recurrence-free survival of 100% compared to 85.7% in patients with low AFP and high PIVKA-II (p = 0.026). Regardless of the AFP level, patients within the Milan criteria (based on explant pathology) with a low PIVKA-II level had a 5-year recurrence-free survival of 100% compared to patients with a high PIVKA-II level of 81.1% (p = 0.002). In patients with microvascular invasion, the AUC for PIVKA-II was slightly better than the AUC for AFP (0.775 vs. 0.687). Conclusions: The dual model of PIVKA-II ≤ 90 mAU/mL with either AFP ≤ 8 ng/mL or with patients within the Milan criteria identifies patient groups which can be exempted from HCC surveillance after LT in a low AFP population. PIVKA-II may be a better predictor for explant microvascular invasion than AFP and could play a role in future models identifying LT candidates with the highest risk for HCC recurrence.</p

Transmission Heterogeneity and Control Strategies for Infectious Disease Emergence

The control of emergence and spread of infectious diseases depends critically on the details of the genetic makeup of pathogens and hosts, their immunological, behavioral and ecological traits, and the pattern of temporal and spatial contacts among the age/stage-classes of susceptible and infectious host individuals.We show that failing to acknowledge the existence of heterogeneities in the transmission rate among age/stage-classes can make traditional eradication and control strategies ineffective, and in some cases, policies aimed at controlling pathogen emergence can even increase disease incidence in the host. When control strategies target for reduction in numbers those subsets of the population that effectively limit the production of new susceptible individuals, then control can produce a flush of new susceptibles entering the population. The availability of a new cohort of susceptibles may actually increase disease incidence. We illustrate these general points using Classical Swine Fever as a reference disease.Negative effects of culling are robust to alternative formulations of epidemiological processes and underline the importance of better assessing transmission structure in the design of wildlife disease control strategies

Expression of Foot-and-Mouth Disease Virus Capsid Proteins in Silkworm-Baculovirus Expression System and Its Utilization as a Subunit Vaccine

Background: Foot-and-mouth disease (FMD) is a highly contagious disease of livestock that causes severe economic loss in susceptible cloven-hoofed animals. Although the traditional inactivated vaccine has been proved effective, it may lead to a new outbreak of FMD because of either incomplete inactivation of FMDV or the escape of live virus from vaccine production workshop. Thus, it is urgent to develop a novel FMDV vaccine that is safer, more effective and more economical than traditional vaccines. Methodology and Principal Findings: A recombinant silkworm baculovirus Bm-P12A3C which contained the intact P1-2A and 3C protease coding regions of FMDV Asia 1/HNK/CHA/05 was developed. Indirect immunofluorescence test and sandwich-ELISA were used to verify that Bm-P12A3C could express the target cassette. Expression products from silkworm were diluted to 30 folds and used as antigen to immunize cattle. Specific antibody was induced in all vaccinated animals. After challenge with virulent homologous virus, four of the five animals were completely protected, and clinical symptoms were alleviated and delayed in the remaining one. Furthermore, a PD50 (50 % bovine protective dose) test was performed to assess the bovine potency of the subunit vaccine. The result showed the subunit vaccine could achieve 6.34 PD50 per dose