Flaring and self-shadowed disks around Herbig Ae stars: simulations for 10 micron interferometers

We present simulations of the interferometric visibilities of Herbig Ae star disks. We investigate whether interferometric measurements in the 10 micrometer atmospheric window are sensitive to the presence of an increased scale height at the inner disk edge, predicted by recent models. Furthermore, we investigate whether such measurements can discriminate between disks with a ``flaring'' geometry and disks with a ``flat'' geometry. We show that both these questions can be addressed, using measurements at a small number of appropriately chosen baselines. The classification of Herbig Ae stars in two groups, based on the appearance of the spectral energy distribution (SED), has been attributed to a difference in disk geometry. Sources with a group I SED would have a flaring outer disk geometry, whereas the disk of group II sources is proposed to be flat (or ``self-shadowed''). We show that this hypothesis can be tested using long-baseline interferometric measurements in the micrometer atmospheric window.Comment: 10 pages, 7 figures, accepted for publiction in Astronomy and Astrophysic

Governance for quality management in smallholder-based tropical food chains

Abstract The paper provides a framework that focuses on the linkages between several key dimensions of supply chain organization and performance of perishable tropical food products. The focus is on the relationship between governance regime and quality management. However, two other but related variables are taken into account because they impact on the relationship between governance and quality management. These variables are channel choice and value added distribution in the supply chain. Governance regime is reflecting how to enhance coordination and trust amongst supply chain partners and how to reduce transaction costs. Quality management is dealing with how to manage food technology processes such that required quality levels can be improved and variability in quality of natural products can be exploited. Governance regimes in relation to quality management practices are discussed to the extent that supply chain partners are able, or are enabled, to invest in required quality improve-ments. Reduction of transaction costs, creation of trust-based networks and proper trade-offs between direct and future gains may offer substantial contributions to effective quality management and enforcement. This framework has been applied to nine case studies on smallholder-based food supply chains originating from developing countries (Ruben et al., 2007). Three of these case studies are discussed in this paper to illustrate what challenges can be derived from the case studies. The selected case studies concern fish originating from Kenya, mango originating from Costa Rica and vegetables produced in China

Bayesian networks to explain the effect of label information on product perception

Interdisciplinary approaches in food research require new methods in data analysis that are able to deal with complexity and facilitate the communication among model users. Four parallel full factorial within-subject designs were performed to examine the relative contribution to consumer product evaluation of intrinsic product properties and information given on packaging. Detailed experimental designs and results obtained from analyses of variance were published [1]. The data was analyzed again with the machine learning modelling technique Bayesian networks. The objective of the current paper is to explain basic features of this technique and its advantages over the standard statistical approach regarding handling of complexity and communication of results. With analysis of variance, visualization and interpretation of main effects and interactions effects becomes difficult in complex systems. The Bayesian network model offers the possibility to formally incorporate (domain) experts knowledge. By combining empirical data with the pre-defined network structure, new relationships can be learned, thus generating an update of current knowledge. Probabilistic inference in Bayesian networks allows instant and global use of the model; its graphical representation makes it easy to visualize and communicate the results. Making use of the most of data from one single experiment, as well as combining data of independent experiments makes Bayesian networks for analysing these and similarly complex and rich data set

Governance for quality management in smallholder-based tropical food chains

The paper provides a framework that focuses on the linkages between several key dimensions of supply chain organization and performance of perishable tropical food products. The focus is on the relationship between governance regime and quality management. However, two other but related variables are taken into account because they impact on the relationship between governance and quality management. These variables are channel choice and value added distribution in the supply chain. Governance regime is reflecting how to enhance coordination and trust amongst supply chain partners and how to reduce transaction costs. Quality management is dealing with how to manage food technology processes such that required quality levels can be improved and variability in quality of natural products can be exploited. Governance regimes in relation to quality management practices are discussed to the extent that supply chain partners are able, or are enabled, to invest in required quality improve¬ments. Reduction of transaction costs, creation of trust-based networks and proper trade-offs between direct and future gains may offer substantial contributions to effective quality management and enforcement. This framework has been applied to nine case studies on smallholder-based food supply chains originating from developing countries (Ruben et al., 2007). Three of these case studies are discussed in this paper to illustrate what challenges can be derived from the case studies. The selected case studies concern fish originating from Kenya, mango originating from Costa Rica and vegetables produced in China.Agribusiness, Agricultural and Food Policy,