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| Registros recuperados: 501 | |
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| Mumford, J.. |
| To allocate biosecurity resources efficiently and effectively it is necessary to be able to systematically estimate and describe risks from a wide range of threats and mitigation measures. A common framework for conducting risk assessments is an essential tool for setting national priorities and for making decisions that will justify actions to international trading partners. Two systems, one quantitative and one that combines qualitative and quantitative elements, are presented as examples of such a systematic approach |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1288 |
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| Skirvin, D.J.. |
| Canopy structure has an important role to play in determining the searching patterns of predators of insect pests in crops. The connections between plants within the canopy are crucial in determining the ability of predators to move around the canopy. Virtual plant models provide an ideal method for providing a realistic background for modelling the movement of insects in plant canopies. Experimental simulations of the movement of the predatory mite Phytoseiulus persimilis have shown that the time taken for the predator to locate the prey decreases as plants become more connected. However, the time to prey location is increased as the internal structure of the individual plants in increased. These two factors therefore have to trade off against each other... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1388 |
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| Relf, P.D.. |
| The need to document the efficacy of nature-based therapeutic modalities is of concern to all who support and encourage this field of endeavour. While a relatively large body of information is available very few of the articles are published in clinical and medical journals that provide the underlying basis for academic, programmatic and policy decisions, and little of it is based on the high level of rigorous research needed to gain respect as a contributing part of health-care science. In addition, the difficulties in forming a coherent profession go beyond the lack of adequate and appropriate research to the core problem of uniform terminology in the field and coherent theoretical framework to guide the research and implementation of treatment. With... |
| Tipo: Conference proceedings |
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| Ano: 2005 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1254 |
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| Takken, W.; Costantini, C.; Dolo, G.; Hassanali, A.; Sagnon, N.; Osir, E.. |
| Mating is one aspect of behaviour that has been much ignored in mosquito biology. Yet, the success of a transgenic release strategy depends on normal, competitive mating between introduced and wild individuals. An overview is presented of current knowledge of mating behaviour in Culicidae, including timing of mating, means of sperm transfer, refractory behaviour and multiple mating. Most lacunae were found in mate finding: it is known that some species use swarming while other mate on or near the vertebrate host. At short range males locate females by acoustic signals, but there is no knowledge how the sexes locate each other from a distance. It is argued that mass rearing of mosquitoes for sterile-insect release or transgenic release should include steps... |
| Tipo: Conference proceedings |
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| Ano: 2005 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1197 |
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| Lewis, J.L.. |
| Forest managers and academics seeking to forge an interdisciplinary blend of natural and social scientific research confront a formidable challenge. In addition to the daunting array of conceptual and methodological frameworks, there are fundamental questions and methodological issues regarding the respective roles of biology, social context and culture as influential factors in environmental perception. The purpose of this chapter is to present a conceptual roadmap for land managers and researchers attempting to achieve some form of disciplinary integration. I critically evaluate the theoretical postulates used in current landscape-perception research, examine the role of aesthetics and culture in landscape perception, and speculate on the potential... |
| Tipo: Conference proceedings |
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| Ano: 2005 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1104 |
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| Kaufman, J.L.. |
| To improve local food systems in the U.S. it is important to understand what is happening in the dominant mainstream food system, because that system poses formidable constraints to how much success local food systems can achieve. Major changes occurred in the food-system-centred part of the American landscape. The principal trends in the changes of the food system are that farmers get less of the food dollar, their numbers decrease and large farms are dominating the farming community. Accompanying changes are high pesticide use, less biodiversity in crops, more use of genetically modified organisms and booming factory farms. These trends change the rural communities and make farmland disappear from urban fringes. The consumer part is changing by the... |
| Tipo: Conference proceedings |
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| Ano: 2004 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1002 |
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| Karley, A.; Marshall, B.. |
| Sustainable farming systems that maintain the diversity of arable plant communities and associated invertebrates are a key objective for European agriculture. Plant structure–function analysis and modelling are potentially important tools for studying these arable communities, and for understanding the impact of crop–weed interactions on crop productivity and on diversity in arable food webs. To understand the role of plant structure in trophic interactions and community composition, we need knowledge of the ‘rules’ governing plant structure, and how variation in structure affects the way that plants compete for and acquire resources, both above- and belowground. As a first step to a structural-modelling approach, we have used a sonic digitizer to capture... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1386 |
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| Yuen, J.; Mila, A.. |
| Bayesian methods are seldom seen in the context of plant pathology. However, they offer a number of possibilities in data analysis and decision theory. Most decision makers utilize a Bayes-like methodology to combine prior information with new information, and in this context the acceptance or failure of predictive systems can be itself dependent on prior information. In the context of complex systems, a Bayesian approach to data analysis using MCMC methods offers flexibility beyond that encountered in a frequentist approach. Frequency distributions of parameters become available, and the effect of the certainty of the prior distribution can also be determined |
| Tipo: Conference proceedings |
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| Ano: 2004 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/861 |
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| Goeschl, T.. |
| This paper examines the linkages between the system that society uses to incentivize R&D by private innovators in the area of crop improvement on the one hand and the environment on the other. This examination is an important addition to the technology-assessment exercise conducted in the context of transgenic crops since it focuses on the organization of the R&D process rather than on the outputs. The paper first demonstrates that design choices with respect to the system of rewards under which crop improvement is carried out determine important characteristics of R&D outputs. In particular, it shows that choosing a patent-style system of intellectual property rights (IPR) will impact on the rate, direction, pace and mode of technological... |
| Tipo: Conference proceedings |
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| Ano: 2005 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/926 |
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| Surkov, I.V.; Oude Lansink, A.G.J.M.; Van der Werf, W.; Van Kooten, O.. |
| Optimal allocation of available resources to minimize quarantine risks related to international trade is a problem facing plant protection agencies worldwide. In this paper a model of budget allocation to minimize quarantine risks is developed. Theoretical conditions that budget allocation should satisfy are derived. These conditions imply that optimal allocation of resources is achieved when the marginal pest risks are equalized across risky pathways. Furthermore, an empirical model of budget distribution is developed. In the empirical model, the protecting agency wants to minimize the expected number of infested ornamental plants imported in a given country. The model is parameterized using data on import of ornamental commodities, the associated... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1280 |
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| Malosetti, M.; Ribaut, J.M.; Vargas, M.; Crossa, J.; Boer, M.P.; Van Eeuwijk, F.A.. |
| Water shortage is a major cause of yield loss in maize. Thus, breeding for adaptation to waterstressed environments is an important task for breeders. The use of quantitative-trait loci (QTL) models in which the response of complex phenotypes under stressed environments is described in direct relation to molecular information can improve the understanding of the genetic causes underlying stress tolerance. Mixed QTL models are particularly useful for this type of modelling, especially when the data stem from multi-environment evaluations including stressed and non-stressed conditions. The study of complex phenotypic traits such as yield under water-limited conditions can benefit from the analysis of trait components (e.g., yield components) that can be... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1293 |
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| Van der Heijden, G.W.A.M.; De Visser, P.H.B.; Heuvelink, E.. |
| The aim of this chapter is to give an overview of the measurements needed for development and parameterization of a functional-structural crop model. Special emphasis will be given to measurements for structural/architectural processes. Size (area, length, width, thickness, volume) of the various organs (e.g., leaves, internodes, flowers, fruits and roots), as well as number of organs, 3D position and time of measurement need to be recorded. Existing methods for full 3D data capture and automatic feature extraction still present many problems. Therefore, human-operated sonic or magnetic trackers are at the moment more suitable to extract and store relevant information. Physiological processes like photosynthesis, transpiration and carbon allocation require... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1368 |
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| Dingkuhn, M.; Luquet, D.; Clément-Vidal, A.; Tambour, L.; Kim, H.K.; Song, Y.H.. |
| There is a new interest in plant morphogenesis and architecture because molecular genetics is providing new information on their genetic and physiological control. From a crop modeller’s point of view, this requires particular attention paid to the regulation of sinks associated with organ development, as well as their interactions with assimilate sources. Existing agronomic and architectural crop models are not capable of simulating such interactions. A conceptual framework is presented for the analysis and simulation of crop growth driven by either assimilate source or sink dynamics, building on the assumption that meristems are the main sites in the plant architecture where sinks are initiated and adjusted to resources. Among the numerous sink–source... |
| Tipo: Conference proceedings |
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| Ano: 2007 |
URL: http://library.wur.nl/ojs/index.php/frontis/article/view/1303 |
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| Registros recuperados: 501 | |
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