A social cost-benefit analysis of two One Health interventions to prevent toxoplasmosis

In the Netherlands, toxoplasmosis ranks second in disease burden among foodborne pathogens with an estimated health loss of 1,900 Disability Adjusted Life Years and a cost-of-illness estimated at €45 million annually. Therefore, effective and preferably cost-effective preventive interventions are warranted. Freezing meat intended for raw or undercooked consumption and improving biosecurity in pig farms are promising interventions to prevent Toxoplasma gondii infections in humans. Putting these interventions into practice would expectedly reduce the number of infections; however, the net benefits for society are unknown. Stakeholders bearing the costs for these interventions will not necessary coincide with the ones having the benefits. We performed a Social Cost-Benefit Analysis to evaluate the net value of two potential interventions for the Dutch society. We assessed the costs and benefits of the two interventions and compared them with the current practice of education, especially during pregnancy. A ‘minimum scenario’ and a ‘maximum scenario’ was assumed, using input parameters with least benefits to society and input parameters with most benefits to society, respectively. For both interventions, we performed different scenario analyses. The freezing meat intervention was far more effective than the biosecurity intervention. Despite high freezing costs, freezing two meat products: steak tartare and mutton leg yielded net social benefits in both the minimum and maximum scenario, ranging from €10.6 million to €31 million for steak tartare and €0.6 million to €1.5 million for mutton leg. The biosecurity intervention would result in net costs in all scenarios ranging from €1 million to €2.5 million, due to high intervention costs and limited benefits. From a public health perspective (i.e. reducing the burden of toxoplasmosis) and the societal perspective (i.e. a net benefit for the Dutch society) freezing steak tartare and leg of mutton is to be considered

Advances in magnetic recording materials

Magnetic recording is mainly carried out on thin layers that consist of a dispersion of magnetic particles in an organic binder system. These particles are single domains of either γ-Fe2O3 or CrO2, the magnetic anisotropy of which is due to their acicular shape. The recording performance of γ-Fe2O3 coatings have been enhanced considerably in the past five years by improving the particle morphology. Attempts to make the recording quality of iron oxides equal to that of CrO2 by increasing their magnetocrystalline anisotropy by Co-doping failed because of the resultant insufficient physical stability. Taking into account the good morphology of the present CrO2 a further significant increase of recording performance by the architecturing of oxidic materials is not to be expected. Considerable progress, ∼ 6 dB with respect to CrO2, is possible, however, by using well-shaped metallic iron or iron-alloy particles, owing to their much higher saturation magnetization.L'enregistrement magnétique est principalement effectué sur des couches minces constituées de particules magnétiques disposées dans un liant organique. Ces particules sont des monodomaines, soit de γ-Fe2O3, soit de CrO 2 présentant une anisotropie magnétique provoquée par leur forme aciculaire. Les performances des couches à base de γ-Fe2O3 ont été considérablement améliorées ces cinq dernières années. Le résultat a pu être obtenu grâce à un perfectionnement de la morphologie des particules. Les efforts déployés pour atteindre avec les oxydes de fer les mêmes performances à l'enregistrement qu'avec CrO 2, et ce par augmentation de leur anisotropie magnétocristalline, par dopage à l'aide de cobalt, ont échoué jusqu'à présent du fait de leur stabilité physique insuffisante. La morphologie de CrO 2 est bonne à l'heure actuelle, en conséquence il est peu probable qu'une meilleure mise en forme des oxydes permette d'atteindre des améliorations de performances. Un progrés considérable — 6 dB comparé au CrO2 — est pourtant possible, en utilisant des particules bien formées de fer métallique, grâce à leur saturation magnétique plus élevée

De bereiding van butadien

Document(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Incorporating three-dimensional mechanisms into two-dimensional dislocation dynamics

Constitutive rules are developed to include three-dimensional dislocation mechanisms, such as line tension and dynamic junction formation, within a two-dimensional dislocation dynamics formulation. Some of the junctions that form dynamically can operate as Frank-Read sources. Boundary value problems are solved by using superposition to represent the solution in terms of the infinite medium fields for discrete dislocations and non-singular complementary fields that enforce the boundary conditions. This framework is used to analyse the plane strain tension of a single crystal. Calculations are carried out to strains of 3-8%, and the transition from stage I to 11 hardening is exhibited. The dependence of this transition and of the stage II hardening on constitutive parameters is explored. A variety of stress-strain responses are obtained and compared with available experimental results. The emergence of dislocation cells is seen and the structure of the cells is described

The stored energy of cold work: Predictions from discrete dislocation plasticity

The stored energy of cold work is calculated for planar single crystals under tensile loading with plastic deformation occurring through dislocation glide. Superposition is used to represent the solution of boundary value problems in terms of the singular fields for discrete dislocations and image fields that enforce boundary conditions. Constitutive rules are used which account for the effects of line tension and three-dimensional dislocation interactions including dynamic junction formation. The stored energy is calculated both under load and after load removal and methods are devised to estimate the local plastic dissipation and to separate out the contribution of long-range stresses to the energy stored. Calculations are carried out up to imposed strains of 0.05–0.1 and the effects of strain level, dislocation structure and crystal orientation on the evolution of the stored energy are investigated. Although the flow stress and work hardening rate depend mainly on the dislocation density, the stored energy of cold work depends on details of the dislocation structure that forms, with any long-range dislocation stress field playing a significant role. The calculations exhibit a connection between the stored energy of cold work and the Bauschinger effect. It is also found that local energy storage values can differ substantially from the average value.

Smaller is Softer: An Inverse Size Effect in a Cast Aluminum Alloy

The stress–strain curves of A356 cast aluminum alloys exhibit an unusual size effect on flow properties: the finer the microstructure, the lower the tensile flow strength. Tensile tests were carried out on specimens made of an A356 alloy with 7% Si as the main alloying element. The specimens were cast at two cooling rates. For both processing conditions the microstructure within each grain consists of pro-eutectic aluminum dendrites separated by a boundary eutectic region of segregated silicon particles of ≈2–3 µm diameter. The fast cooling rate gives rise to a secondary dendrite arm spacing of approximately 20–30 µm, while the secondary dendrite arm spacing obtained with the slow cooling rate is about 80–100 µm. Discrete dislocation plasticity is used to model the inverse size effect in this alloy. The dislocations are represented as line defects in an elastic solid and dislocation nucleation, annihilation and drag are incorporated through a set of constitutive rules. Obstacles to dislocation motion are randomly distributed in the dendrite and the eutectic regions, but with different densities and strengths. The thickness of the eutectic region is found to be a key parameter in determining the inverse size effect. In addition, the size effect is found to depend on the extent to which dislocation nucleation takes place in the eutectic region.