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Understanding voluntary program performance : Introducing the diffusion network perspective
No full textVoluntary programs have rapidly become a means for the public, private, and third sectors to regulate and govern complex societal problems. Following the rapid and widespread emergence of these programs, scholars have been active in mapping, exploring, and interrogating their design and performance. Considerable advances have been made in describing program design and context conditions, and the actors involved in the voluntary program that relate to program performance. Less is known, however, about how these conditions affect program performance. Starting with one of the dominant theories on voluntary programs, the club theory perspective, this article seeks to understand how different program design conditions interact to affect the performance of 26 voluntary programs for low carbon building and city development in Australia, the Netherlands, and the United States. Applying qualitative comparative analysis, the study finds that the club theory perspective has limited explanatory power for this specific set of cases. Iterative rounds of analysis indicate that a diffusion network perspective is the best complementary perspective for explaining the performance of this set of programs. The article concludes that, in situations of a non-homogeneous market of voluntary program participants, a focus on the programs’ diffusion networks helps to explain their performance. This has implications for the design and implementation of such programs.</p
Twenty years of forest management certification in the tropics : Major trends through time and among continents
No full textFor over 20 years, forest management certification—particularly that of the Forest Stewardship Council (FSC)—has been promoted as a way to manage tropical natural forests responsibly. To shed light on the current and historical trends of this market-driven, forest governance intervention, we obtained information from the public summaries of evaluation reports belonging to 543 forest management units (FMUs) located in the tropics and covering 20 years of certification, from 1995 until 2016. Additionally, we analyzed 4621 corrective action requests (CARs) issued by third-party auditors during the initial certification attempts of companies and groups managing tropical natural forests to increase our understanding of the nature of problematic management issues and their evolution across different regions. By the end of 2016, most of the certified forest area was located in Africa, followed by the Americas and Asia. The tropics experienced a period of stagnation regarding certified area growth during the last decade, partly as a consequence of a pantropical wave of certificate terminations that started in 2008, having a severe impact in the Americas and a moderate one in Asia and Africa. Our results suggest that FMUs that remain certified for relatively more extended periods are more resilient against external economic pressures. One implication is that managers and policymakers should develop mechanisms to encourage long-term certification, particularly among small-holders as the amount of certified area managed by groups (i.e., communities and groups of small companies) has decreased throughout the last decade. We highlight the importance of looking into the temporal and regional dynamics to get a broader perspective of FSC certification at the tropical level.</p
A system approach towards prediction of food safety hazards : Impact of climate and agrichemical use on the occurrence of food safety hazards
No full textIn this study, we aimed to demonstrate the aptness of a system approach to predict the level of contamination in a given agricultural product. As a showcase, the impact of climate and agrichemical use on the occurrence of food safety hazards in feed of dairy cows in the Netherlands was used. Data on chemical hazards in dairy cows' feed in the Netherlands for the years 2000 to 2013 were retrieved from the Dutch monitoring program KAP (Quality Program for Agricultural Products). Climate data (17 variables) and agrichemical usage figs. (6 variables) for the Netherlands were obtained from the NOAA's National Centers for Environmental Information, the European Commission Joint Research Center's Agri4Cast database, and FAO's FAOSTAT. A Bayesian Network (BN) was constructed with this data and optimized for the prediction of the contamination level. The overall accuracy of prediction of the level of contamination in feed was 90.3%. Sensitivity analysis demonstrated that many climate and agrichemical variables contributed to the prediction; however, their individual contribution was generally small. The applicability of the BN was demonstrated in more detail for grass and maize as feed components. The observed trends in contamination of these crops were accounted for by climate and agrichemical variables, with the impact varying amongst the specific variables and commodities. The variables with the highest impact were “days of precipitations in a month with ≥ 2.5 mm” and “annual use of herbicides". The results demonstrate that data-driven BNs can capture complex interactions, thereby enabling high-accuracy predictions. Whilst the applicability of this approach to the safety of dairy cows' feed in the Netherlands has thus been demonstrated, it can also be applied to other areas of food safety when a systems approach is needed. Such models can support risk assessors and risk managers in their understanding of the impacts of a given factor on food and feed safety, and inform the latter's decisions to mitigate potential risks.</p
Effect of dimethyl disulfide on the sulfur formation and microbial community composition during the biological H<sub>2</sub>S removal from sour gas streams
No full textRemoval of organic and inorganic sulfur compounds from sour gases is required because of their toxicity and atmospheric pollution. The most common are hydrogen sulfide (H2S) and methanethiol (MT). Under oxygen-limiting conditions about 92 mol% of sulfide is oxidized to sulfur by haloalkaliphilic sulfur-oxidizing bacteria (SOB), whilst the remainder is oxidized either biologically to sulfate or chemically to thiosulfate. MT is spontaneously oxidized to dimethyl disulfide (DMDS), which was found to inhibit the oxidation of sulfide to sulfate. Hence, we assessed the effect of DMDS on product formation in a lab-scale biodesulfurization setup. DMDS was quantified using a newly, in-house developed analytical method. Subsequently, a chemical reaction mechanism was proposed for the formation of methanethiol and dimethyl trisulfide from the reaction between sulfide and DMDS. Addition of DMDS resulted in significant inhibition of sulfate formation, leading to 96 mol% of sulfur formation. In addition, a reduction in the dominating haloalkaliphilic SOB species, Thioalkalivibrio sulfidiphilus, was observed in favor of Thioalkaibacter halophilus as a more DMDS-tolerant with the 50 % inhibition coefficient at 2.37 mM DMDS.</p
All sparse PCA models are wrong, but some are useful. Part I: Computation of scores, residuals and explained variance
No full textSparse Principal Component Analysis (sPCA) is a popular matrix factorization approach based on Principal Component Analysis (PCA) that combines variance maximization and sparsity with the ultimate goal of improving data interpretation. When moving from PCA to sPCA, there are a number of implications that the practitioner needs to be aware of. A relevant one is that scores and loadings in sPCA may not be orthogonal. For this reason, the traditional way of computing scores, residuals and variance explained that is used in the classical PCA can lead to unexpected properties and therefore incorrect interpretations in sPCA. This also affects how sPCA components should be visualized. In this paper we illustrate this problem both theoretically and numerically using simulations for several state-of-the-art sPCA algorithms, and provide proper computation of the different elements mentioned. We show that sPCA approaches present disparate and limited performance when modeling noise-free, sparse data. In a follow-up paper, we discuss the theoretical properties that lead to this undesired behavior. We title this series of papers after the famous phrase of George Box “All models are wrong, but some are useful” with the same original meaning: sPCA models are only approximations of reality and have structural limitations that should be taken into account by the practitioner, but properly applied they can be useful tools to understand data.</p
How a Strategic Scoping Canvas Can Facilitate Collaboration between Partners in Sustainability Transitions
No full textThe loosely applied concepts of transformations and transitions often result in unarticulated different visions and expectations among stakeholders regarding the orientation and ambition of a particular initiative related to system transitions/transformations. In this paper, a strategic scoping canvas and an associated facilitation process are presented as a way of enhancing sharedunderstanding among stakeholders. Illustrations are provided of initial application in three cases related to food system transitions in Peru, Ethiopia, and Bangladesh, exploring the connectivity with approaches commonly used in the context of system transformations, including the Multi-LevelPerspective on sustainability transitions, the Leverage Points approach, Capability Approach, and the theory of Large System Change. We conclude that the canvas and associated facilitation approach has proved useful in dierent contexts, oering opportunities for complementing existing methodologies,and potentially enhancing their ecacy in facilitated multi-stakeholder processes
Berekening grondstofefficiëntie geeft nuchtere kijk op plant factory : Ontbreken van 'gratis' zonlicht is zwakke punt vertical farm
No full textEight grand challenges in socio-environmental systems modeling
No full textModeling is essential to characterize and explore complex societal and environmental issues in systematic and collaborative ways. Socio-environmental systems (SES) modeling integrates knowledge and perspectives into conceptual and computational tools that explicitly recognize how human decisions affect the environment. Depending on the modeling purpose, many SES modelers also realize that involvement of stakeholders and experts is fundamental to support social learning and decision-making processes for achieving improved environmental and social outcomes. The contribution of this paper lies in identifying and formulating grand challenges that need to be overcome to accelerate the development and adaptation of SES modeling. Eight challenges are delineated: bridging epistemologies across disciplines; multi-dimensional uncertainty assessment and management; scales and scaling issues; combining qualitative and quantitative methods and data; furthering the adoption and impacts of SES modeling on policy; capturing structural changes; representing human dimensions in SES; and leveraging new data types and sources. These challenges limit our ability to effectively use SES modeling to provide the knowledge and information essential for supporting decision making. Whereas some of these challenges are not unique to SES modeling and may be pervasive in other scientific fields, they still act as barriers as well as research opportunities for the SES modeling community. For each challenge, we outline basic steps that can be taken to surmount the underpinning barriers. Thus, the paper identifies priority research areas in SES modeling, chiefly related to progressing modeling products, processes and practices.<br/
Behavioural factors of Dutch pig producers related to control of <i>Toxoplasma gondii </i>infections in pigs
No full textToxoplasma gondii (T. gondii) is a food safety hazard which causes a substantial human disease burden. Infected pig meat is a common risk source of toxoplasmosis. Therefore, it is important to control T. gondii infections in pigs. Improving farm management to control the introduction risk likely contributes to that aim. A pig producer only implements control measures when he or she is aware of the underlying problem, wants to solve it, and is able to solve it. If a pig producer is not implementing appropriate control measures, behavioural change interventions can be introduced to overcome constraining behavioural factors. To aid in designing behaviour change interventions, this study analysed behavioural factors of Dutch pig producers in terms of capability, opportunity and motivation to control T. gondii infections in pigs. Key risk sources analysed focused on the life cycle of T. gondii, with cats as primary host, rodents as intermediate host, and uncovered feed as an important risk source. A survey was conducted among Dutch pig producers. Responses were analysed using descriptive and cluster analysis. Results showed that around 80% of the 67 responding pig producers was aware of key risk sources of T. gondii infections in pigs. Respondents also rated risk sources that are not known to increase the risk of T. gondii infections in pigs as somewhat important. Many respondents did not know about potential consequences of a T. gondii infection in pigs on human health. Two third expected some impact on pig performance, which is incorrect because T. gondii generally does not make pigs ill. Most respondents indicated to have the motivation and opportunity to control the risk sources cats, rodents and uncovered feed. Three pig producer clusters were identified: one with higher capability to control rodents, one with lower motivation to control rodents and cats and to cover feed storages, and one with lower scores on the importance of rodent control for pigs, human health and farm profit. We conclude that, although many pig producers have knowledge about risk sources for and consequences of T. gondii infections in pigs, the public health impact and risks of T. gondii infections in pigs are not yet common knowledge among all Dutch pig producers. Furthermore, Dutch pig producers differ in opportunity and motivation to control T. gondii infections. Targeted interventions to address these specific constraining behavioural factors can help to improve the control of T. gondii infections in pigs
Invasion biology, ecology, and management of western flower thrips
No full textWestern flower thrips, Frankliniella occidentalis, first arose as an important invasive pest of many crops during the 1970s-1980s. The tremendous growth in international agricultural trade that developed then fostered the invasiveness of western flower thrips. We examine current knowledge regarding the biology of western flower thrips, with an emphasis on characteristics that contribute to its invasiveness and pest status. Efforts to control this pest and the tospoviruses that it vectors with intensive insecticide applications have been unsuccessful and have created significant problems because of the development of resistance to numerous insecticides and associated outbreaks of secondary pests. We synthesize information on effective integrated management approaches for western flower thrips that have developed through research on its biology, behavior, and ecology. We further highlight emerging topics regarding the species status of western flower thrips, as well as its genetics, biology, and ecology that facilitate its use as a model study organism and will guide development of appropriate management practices.</p