Ban on castration of boars in the Netherlands: modeling economic consequences of options

As a result of social criticism on castration, the Netherlands intend to start fattening boars. The great obstacle to a ban on castration is the expected negative effect on international trade because of the fear of boar taint. Consumers’ perception of boar taint is investigated, and a summary is presented of the knowledge gained up to the present to reduce boar taint. Advantaged and drawbacks of several alternatives are assessed. An economic chain- and import/export model has been developed to estimate economic consequences. The total added value of the pig farmers' chain will significantly reduce, but there is much uncertainty of the estimation of market acceptance and prices. A further elaboration of the model is proposed, with an assessment of the optimal mix of alternative

Moving towards boar taint-free meat: an overview of alternatives to surgical castration from a chain perspective

The objective of this study is to review important issues in boar taint prevention without surgical castration, namely alternatives to surgical castration, factors influencing boar taint development and economic considerations associated with the presently feasible alternatives to surgical castration. The paper looks at these issues from the pig production chain perspective and suggests a framework for the analysis of boar taint prevention without surgical castration within the whole-chain contex

From polemic to exegesis: The ancient philosophical commentary

Commentary was an important vehicle for philosophical debate in late antiquity. Its antecedents lie in the rise of rational argumentation, polemical rivalry, literacy, and the canonization of texts. This essay aims to give a historical and typological outline of philosophical exegesis in antiquity, from the earliest allegorizing readings of Homer to the full-blown “running commentary” in the Platonic tradition (fourth to sixth centuries CE). Running commentaries are mostly on authoritative thinkers such as Plato and Aristotle. Yet they are never mere scholarly enterprises but, rather, springboards for syncretistic clarification, elaboration, and creative interpretation. Two case studies (Galen 129–219 CE, Simplicius ca. 530 CE) will illustrate the range of exegetical tools available at the end of a long tradition in medical science and in reading Aristotle through Neoplatonic eyes, respectively

Did Aristotle have a concept of 'intuition'? Some thoughts on translating 'nous'.

In this paper Baltussen proposes to review existing translations of 'nous' in Aristotle in order to show that translating it as 'intuition' is problematic. A proposal to find a new direction for interpreting the term is given, based on a richer understanding of the modern notion of intuition in cognitive psychology. The paper ends by adding some passages to the usual set which deserve further investigation

Resource efficiency and economic implications of alternatives to surgical castration without anaesthesia

This paper presents an analysis of the economic implications of alternative methods to surgical castration without anaesthesia. Detailed research results on the economic implications of four different alternatives are reported. castration with local anaesthesia, castration with general anaesthesia, immunocastration and raising entire males. The first three alternatives have been assessed for their impact on pig production costs in the most important pig-producing Member States of the EU. The findings on castration with anaesthesia show that cost differences among farms increase if the anaesthesia cannot be administered by farmers and when the veterinarian has to be called to perform it. The cost of veterinarian service largely affects the total average costs, making this solution economically less feasible in small-scale pig farms. In all other farms, the impact on production costs of local anaesthesia is however limited and does not exceed 1 (sic)ct per kg. General anaesthesia administered by inhalation or injection of Ketamin in combination with a sedative (Azaperone, Midazolan) is more expensive. These costs depend heavily on farm size, as the inhalation equipment has to be depreciated on the largest number of pigs possible. The overall costs of immunocastration - including the cost of the work load for the farmer - has to be evaluated against the potential benefits derived from higher daily weight gain and feed efficiency in comparison with surgical castrates. The economic feasibility of this practice will finally depend on the price of the vaccine and on consumer acceptance of immunocastration, The improvement in feed efficiency may compensate almost entirely for the cost of vaccination. The main advantages linked to raising entire males are due to the higher efficiency of feed conversion, to the better growth rate and to the higher leanness of carcass. A higher risk of boar taint on the slaughter line has to be accounted for Raising entire males should not generate more than 2.5% of boar taint among slaughter pigs, in order to maintain the considerable economic benefits of better feed efficiency of entire males with respect to castrates

Korter diertransport helpt varkens weinig

Beperking van het maximaal aantal uren dat levende dieren op transport mogen, zal weinig veranderen aan de dierstromen binnen Europa en weinig gevolgen hebben voor de veehouderij. Dat blijkt uit een eerste verkenning van het LEI

Transport and mixing by artificial cilia

Microfluidic analysis devices are becoming more common as a tool for clinical analysis. In these devices fluid transport and mixing of multiple components are common tasks. A possible way of achieving these tasks can be found in nature, where small hairs, named cilia, are found on micro-organisms and surfaces. These hairs move the surrounding fluid, or move the micro-organism through the fluid. As in micro-fluidics, the generated flows are inertialess in general. By mimicking natural cilia, several successful microfluidic actuators for pumping and mixing have been developed recently [1–8]. In order to understand the working principles of these devices and improve their design, a numerical model is presented in this thesis. With this model, we studied the fluid-structure interaction of the cilium with the surrounding fluid. Since cilia are very thin beams which show large deformations, a model which can cope with large deformations is required. We therefore chose to model the fluid on a fixed Eulerian grid and the solid on a moving Lagrangian grid. Initially we used a fictitious domain/Lagrange multiplier technique to couple both domains. Simulations showed however, that this technique is inaccurate near the moving interface of the fluid and the cilium. This inaccuracy stems from two causes, namely the fictitious fluid domain and the discretization of the Lagrange multiplier. The first cause is eliminated by removing the fictitious domain with the eXtended Finite Element Method (xfem). The second cause is removed by applying coupling in a weak manner, without the need of a Lagrange multiplier. This method gave accurate results for Newtonian, generalized Newtonian and viscoelastic fluids in combination with an elastic solid. The major advantages of this method are its accuracy, optimal convergence rates, without including problem dependent parameters. In Chapter 4, the new numerical model is used to study the influence of the actuation frequency on the transport and mixing efficiency of one or two artificial cilia. It is shown that there exists a frequency for which the flow rate is maximum. The reason for this maximum is the fact that a fluid-structure interaction problem has an intrinsic time-scale, which makes the system frequency dependent, even when fluid and solid inertia are absent. At the optimal flow rate, the amount of displaced fluid per cycle is not optimal. So using the latter as an objective may not lead to the largest flow rate possible in the system. For the mixing analysis two cilia were modeled, each having a different intrinsic time-scale. Both were actuated by the same actuation force, thus showing different motion. This led to a phase difference between the two cilia, which has been shown to enhance mixing [9]. The mixing performance was measured by tracking a blob in time, which was initially placed in between the cilia. The stretch of this blob is a measure for the local mixing efficiency, and an exponential increase indicates chaotic mixing. A length stretch increase was observed in all cases. Changing the cilium thickness of one of the cilia has a clear beneficial effect on mixing. For mixing the amount of fluid moved by the cilia is also important, as the mixing performance at low actuation frequency is much better than at high actuation frequency, where the movement of the cilia, and hence the induced flow, is less. In order to perform simulations of artificial cilia in a non-Newtonian fluid, the numerical model proposed in Chapter 4 has been extended in Chapter 6. In addition a local mesh refinement scheme was developed in order to make accurate simulations within a shorter time-frame feasible. Both the mesh refinement scheme and the viscoelastic fluid-structure interaction scheme were tested, and shown to be stable and accurate. The numerical model of this chapter is used in Chapter 7 for the simulation of generalized Newtonian and viscoelastic fluid flow by artificial cilia. It is shown that by making use of the typical time-scale of the cilia system and the time-scale of the generalized Newtonian fluid, the net fluid flow of a generalized Newtonian fluid had a higher dependence on the actuation force than for a Newtonian fluid. In the final chapter conclusions and recommendations for future work are given