Values in design

Focusing on socio-technical design with values as a critical component in the design process

Validity of the N\'{e}el-Arrhenius model for highly anisotropic Co_xFe_{3-x}O_4 nanoparticles

We report a systematic study on the structural and magnetic properties of Co_{x}Fe_{3-x}O_{4} magnetic nanoparticles with sizes between $5$ to $25$ nm, prepared by thermal decomposition of Fe(acac)_{3} and Co(acac)_{2}. The large magneto-crystalline anisotropy of the synthesized particles resulted in high blocking temperatures ($42$ K \leqq $T_B$ $\leqq 345$ K for $5 \leqq$ d $\leqq 13$ nm ) and large coercive fields ($H_C \approxeq 1600$ kA/m for $T = 5$ K). The smallest particles ($=5$ nm) revealed the existence of a magnetically hard, spin-disordered surface. The thermal dependence of static and dynamic magnetic properties of the whole series of samples could be explained within the N\'{e}el-Arrhenius relaxation framework without the need of ad-hoc corrections, by including the thermal dependence of the magnetocrystalline anisotropy constant $K_1(T)$ through the empirical Br\"{u}khatov-Kirensky relation. This approach provided $K_1(0)$ values very similar to the bulk material from either static or dynamic magnetic measurements, as well as realistic values for the response times ($\tau_0 \simeq 10^{-10}$ s). Deviations from the bulk anisotropy values found for the smallest particles could be qualitatively explained based on Zener\'{}s relation between $K_1(T)$ and M(T)

The Conservation Status of Eagles in South African Law

This contribution is an introductory survey and preliminary evaluation of the conservation status of eagles in South African law. The methodology is primarily an interdisciplinary literature study of legal texts and texts from the natural sciences. Eagles are some of the largest and most powerful avian predators, and the human response to their presence is dualistic and polarised. At the one extreme, many people admire eagles, while at the other extreme they are perceived as a threat to economic and other interests, and may even be actively persecuted in a conviction that they are vermin. This duality in the human perception of eagles is also prevalent in South Africa and complicates their conservation. The mobility of eagles and other birds of prey means that they cannot be restrained by fencing national parks and other protected areas, and this heightens the likelihood of their entering into conflict with human interests. The conservation problems faced by eagles in South Africa can broadly be divided into direct and indirect threats. Direct threats include the intentional killing of eagles, and trade in eagles and their eggs. Indirect threats include non-targeted poisoning (where poisoned bait is used to control other predators, but eagles find the bait, feed on it, and succumb); habitat loss; mortality induced by dangerous structures; and disturbance.   The legal status of eagles is influenced by a large body of legislative provisions, ranging from international and regional legal instruments, through national legislation, to provincial legislative measures. An overview of these provisions is given, with concise explanations of how they apply to the legal status of eagles and other birds of prey in South Africa. The conservation status of eagles in South African law is subsequently evaluated by considering the contribution of the applicable laws to three main types of conservation interventions. In respect of the first, habitat preservation, the relevant legal provisions contribute to an impressive array of conserved habitats in national parks and other protected areas. However, the mobility of eagles, and the fact that some species occur mainly outside protected areas, make it imperative for eagles also to be afforded legal protection outside of protected areas. In respect of the second type of intervention, namely management activities to conserve the species in their habitats, an inquiry is made into how the law addresses the threats of the intentional killing of eagles; trade in eagles and their eggs; non-targeted poisoning; mortality induced by dangerous structures; and disturbance. The protection is found to be sound in principle. In respect of the third and most intensive intervention, captive breeding, a regulatory framework is in place, but no such intervention on eagle species is known to be operative in South Africa.   In conclusion a number of recommendations are made. The existing laws can be improved by aligning the legal status of species with their Red List status; listing all bird of prey species that are not Critically Endangered, Endangered, or Vulnerable, as Protected for the purpose of national environmental legislation; and, in the medium rather than the short term, considering the imposition of legal obligations on electricity suppliers to implement measures that will mitigate mortalities on electricity structures. Better application of the existing laws could be achieved by improving compliance and enforcement, and by facilitating the optimal use of Biodiversity Management Plans, environmental research, and environmental education.  &nbsp

The Bald and Golden Eagle Protection Act, Species-Based Legal Protection and the Danger of Misidentification

The Bald and Golden Eagle Protection Act of 1940 bestows legal protection on two North American eagle species in the United States of America. The Act was originally aimed at the legal protection of only one species: the Bald Eagle Haliaeetus leucocephalus, the national symbol of the USA. Later the Act was amended to extend protection also to the Golden Eagle Aquila chrysaetos. The Bald Eagle was an Endangered Species, but the Golden Eagle was not formally listed as Endangered nationwide in the USA. One of the reasons for extending legal protection to the Golden Eagle under the Act was to strengthen the legal protection of the Bald Eagle, because immature Bald Eagles were being misidentified as Golden Eagles and shot. Additional factors relating to Golden Eagle mortality also made legal protection of the Golden Eagle desirable. The danger that a rare and legally protected species can be misidentified and mistaken for a more common and unprotected species can therefore serve as a reason for bestowing legal protection on the more common species as well. Other factors may also indicate that legal protection of the more common species is desirable, making the case more compelling. If this line of reasoning is applied in respect of South African birds of prey, a strong case can be made in favour of extending legal protection under the national biodiversity legislation to more species than the small number of species currently enjoying such protection. Species that are listed as Vulnerable under South African national biodiversity legislation may be misidentified as species that are not subject to such protection. Additional factors are also present that make such an extension of legal protection desirable.  &nbsp

The Legal Status of the Spanish Imperial Eagle in Spain and Thoughts on Environmental Law and Policy as Contributing Factors in the Conservation of Species

This contribution reflects on the contributory role of environmental law and policy in the successful conservation interventions on behalf of the rare Spanish Imperial Eagle (Aquila Adalberti), with the aim of gaining insights that may be more universally applicable, including in jurisdictions such as South Africa. An overview of applicable international, European and Spanish laws and policies is given, and the role played by these instruments is considered together with successes attained with diverse conservation goals in respect of the Spanish Imperial Eagle. The exceptionally comprehensive character of the legal protection of the Spanish Imperial Eagle is highlighted, in conjunction with some extra-legal factors that have contributed to successful outcomes. While quantification of the role of the law in the conservation of a species remains elusive, it is probably safe to conclude that environmental law and policy have played a vital and central role in the improvement of the conservation status of the Spanish Imperial Eagle. It is submitted that the conservation interventions on behalf of the Spanish Imperial Eagle show that concerted legal and other conservation interventions can effectively halt and reverse the decline of an endangered species. However, such interventions are onerous and expensive and ideally, effective conservation measures should be in place before populations have declined to a critical level. Birds of prey face similar threats in South Africa and Spain, and a number of South African raptor species will soon be classified as endangered. While South African biodiversity laws and policy are similar to the European and Spanish laws in general import and methodology, the South African laws and policy are more restricted in scope, less detailed and less prescriptive. When comparing the use of Spanish and South African legislation in the conservation of birds of prey, sight must not be lost of the varying conservation needs of different species and the unequal resources available to different jurisdictions.   

Modelling and optimisation of the operation of a radiant warmer

This paper presents numerical calculations of the temperature field obtained for the case of a neonate placed under a radiant warmer. The results of the simulations show a very non-uniform temperature distribution on the skin of the neonate, which may cause increased evaporation leading to severe dehydration. For this reason, we propose some modifications on the geometry and operation of the radiant warmer, in order to make the temperature distribution more uniform and prevent the high temperature gradients observed on the surface of the neonate. It is concluded that placing a high conductivity blanket over the neonate and introducing additional screens along the side of the mattress, thus recovering the radiation heat escaping through the side boundaries, helped providing more uniform temperature fields.The European Union for the Marie Curie Fellowship grant awarded to the Centre for CFD, University of Leeds

Pinning Fields In Amorphous Materials

The stress and field dependence of the pinning field Hp of ribbons of the composition Fe73.5Cu1Nb3Si 13.5B9 and Co73.5Cu1Nb 3Si13.5B9 is compared with that of the coercivity HC. The similar character of HC(σ) and Hp(σ) indicates a strong correlation between these two properties. At higher external stresses HC(σ) and H p(σ) depend on a premagnetizing procedure. This can be explained assuming a different domain structure.731057275729New University of Lisbon,UNINOVA,Universiteit van Amsterda