The value of statistical life and cost–benefit evaluations of landmine clearance in Cambodia

Development agencies spend approximately US$400 million per year on landmine clearance. Yet many cost–benefit evaluations suggest that landmine clearance is socially wasteful because costs appear to far outweigh social benefits. This paper presents new estimates of the benefits of clearing landmines based on a contingent valuation survey in two provinces in rural Cambodia where we asked respondents questions that elicit their trade-offs between money and the risk of death from landmine accidents. The estimated Value of a Statistical Life (VSL) is US$ 0.4 million. In contrast, most previous studies of landmine clearance use foregone income or average GDP per capita, which has a lifetime value of only US$ 2,000 in Cambodia. Humanitarian landmine clearance emerges as a more attractive rural development policy when appropriate estimates of the VSL are used

The value of statistical life and cost-benefit evaluations of landmine clearance in Cambodia

Development agencies spend approximately US$400 million per year on landmine clearance. Yet many cost-benefit evaluations suggest that landmine clearance is socially wasteful because costs appear to far outweigh social benefits. This paper presents new estimates of the benefits of clearing landmines based on a contingent valuation survey in two provinces in rural Cambodia where we asked respondents questions that elicit their tradeoffs between money and the risk of death from landmine accidents. The estimated Value of a Statistical Life (VSL) is US$0.4 million. In contrast, most previous studies of landmine clearance use foregone income or average GDP per capita, which has a lifetime value of only US$2,000 in Cambodia. Humanitarian landmine clearance emerges as a more attractive rural development policy when appropriate estimates of the VSL are used

Porous silica spheres as indoor air pollutant scavengers

Porous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene-divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for volatile organic compounds evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment

Men’s health – the impact of stroke

Stroke is a leading cause of adult death and the most common cause of complex disability in the UK. This article discusses the incidence and impact of stroke, focusing on a range of issues from a male perspective, including stroke prevention, psychological needs, sexuality and return to work. There are some gender differences in modifiable risk factors for stroke, and women have better knowledge of stroke symptomatology. For men, the development of post-stroke depression is associated with greater physical disability. (c) Sherborne Gibbs Limite

Genetic programming and cellular automata for fast flood modelling on multi-core CPU and many-core GPU computers

Many complex systems in nature are governed by simple local interactions, although a number are also described by global interactions. For example, within the field of hydraulics the Navier-Stokes equations describe free-surface water flow, through means of the global preservation of water volume, momentum and energy. However, solving such partial differential equations (PDEs) is computationally expensive when applied to large 2D flow problems. An alternative which reduces the computational complexity, is to use a local derivative to approximate the PDEs, such as finite difference methods, or Cellular Automata (CA). The high speed processing of such simulations is important to modern scientific investigation especially within urban flood modelling, as urban expansion continues to increase the number of impervious areas that need to be modelled. Large numbers of model runs or large spatial or temporal resolution simulations are required in order to investigate, for example, climate change, early warning systems, and sewer design optimisation. The recent introduction of the Graphics Processor Unit (GPU) as a general purpose computing device (General Purpose Graphical Processor Unit, GPGPU) allows this hardware to be used for the accelerated processing of such locally driven simulations. A novel CA transformation for use with GPUs is proposed here to make maximum use of the GPU hardware. CA models are defined by the local state transition rules, which are used in every cell in parallel, and provide an excellent platform for a comparative study of possible alternative state transition rules. Writing local state transition rules for CA systems is a difficult task for humans due to the number and complexity of possible interactions, and is known as the ‘inverse problem’ for CA. Therefore, the use of Genetic Programming (GP) algorithms for the automatic development of state transition rules from example data is also investigated in this thesis. GP is investigated as it is capable of searching the intractably large areas of possible state transition rules, and producing near optimal solutions. However, such population-based optimisation algorithms are limited by the cost of many repeated evaluations of the fitness function, which in this case requires the comparison of a CA simulation to given target data. Therefore, the use of GPGPU hardware for the accelerated learning of local rules is also developed. Speed-up factors of up to 50 times over serial Central Processing Unit (CPU) processing are achieved on simple CA, up to 5-10 times speedup over the fully parallel CPU for the learning of urban flood modelling rules. Furthermore, it is shown GP can generate rules which perform competitively when compared with human formulated rules. This is achieved with generalisation to unseen terrains using similar input conditions and different spatial/temporal resolutions in this important application domain

Globular Cluster and Galaxy Formation: M31, the Milky Way and Implications for Globular Cluster Systems of Spiral Galaxies

The globular cluster (GC) systems of the Milky Way and of our neighboring spiral galaxy, M31, comprise 2 distinct entities, differing in 3 respects. 1. M31 has young GCs, ages from ~100 Myr to 5 Gyr old, as well as old globular clusters. No such young GCs are known in the Milky Way. 2. We confirm that the oldest M31 GCs have much higher nitrogen abundances than do Galactic GCs at equivalent metallicities. 3. Morrison et al. found M31 has a subcomponent of GCs that follow closely the disk rotation curve of M31. Such a GC system in our own Galaxy has yet to be found. These data are interpreted in terms of the hierarchical-clustering-merging (HCM) paradigm for galaxy formation. We infer that M31 has absorbed more of its dwarf systems than has the Milky Way. This inference has 3 implications: 1. All spiral galaxies likely differ in their GC properties, depending on how many companions each galaxy has, and when the parent galaxy absorbs them. The the Milky Way ties down one end of this spectrum, as almost all of its GCs were absorbed 10-12 Gyr ago. 2. It suggests that young GCs are preferentially formed in the dwarf companions of parent galaxies, and then absorbed by the parent galaxy during mergers. 3. Young GCs seen in tidally-interacting galaxies might come from dwarf companions of these galaxies, rather than be made a-new in the tidal interaction. There is no ready explanation for the marked difference in nitrogen abundance for old M31 GCs relative to the oldest Galactic GCs. The predictions made by Li & Burstein regarding the origin of nitrogen abundance in globular clusters are consistent with what is found for the old M31 GCs compared to that for the two 5 Gyr-old M31 GCs.Comment: to be published in ApJ, Oct 2004; 13 pages of text, 2 tables, 7 postscript figure

Recombination and its impact on the genome of the haplodiploid parasitoid wasp Nasonia

Homologous meiotic recombination occurs in most sexually reproducing organisms, yet its evolutionary advantages are elusive. Previous research explored recombination in the honeybee, a eusocial hymenopteran with an exceptionally high genome-wide recombination rate. A comparable study in a non-social member of the Hymenoptera that would disentangle the impact of sociality from Hymenoptera-specific features such as haplodiploidy on the evolution of the high genome-wide recombination rate in social Hymenoptera is missing. Utilizing single-nucleotide polymorphisms (SNPs) between two Nasonia parasitoid wasp genomes, we developed a SNP genotyping microarray to infer a high-density linkage map for Nasonia. The map comprises 1,255 markers with an average distance of 0.3 cM. The mapped markers enabled us to arrange 265 scaffolds of the Nasonia genome assembly 1.0 on the linkage map, representing 63.6% of the assembled N. vitripennis genome. We estimated a genome-wide recombination rate of 1.4-1.5 cM/Mb for Nasonia, which is less than one tenth of the rate reported for the honeybee. The local recombination rate in Nasonia is positively correlated with the distance to the center of the linkage groups, GC content, and the proportion of simple repeats. In contrast to the honeybee genome, gene density in the parasitoid wasp genome is positively associated with the recombination rate; regions of low recombination are characterized by fewer genes with larger introns and by a greater distance between genes. Finally, we found that genes in regions of the genome with a low recombination frequency tend to have a higher ratio of non-synonymous to synonymous substitutions, likely due to the accumulation of slightly deleterious non-synonymous substitutions. These findings are consistent with the hypothesis that recombination reduces interference between linked sites and thereby facilitates adaptive evolution and the purging of deleterious mutations. Our results imply that the genomes of haplodiploid and of diploid higher eukaryotes do not differ systematically in their recombination rates and associated parameters.Publisher PDFPeer reviewe

Investigation of Driving Force Variation During Swage Autofrettage, Using Finite Element Analysis

Swaging is one method of autofrettage, a means of prestressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed along and through the bore of the tube. A finite element (FE) model of the swaging process, developed previously by the author in ANSYS, was configured for comparison with an earlier model; this allowed the accuracy of further properties of the ANSYS model to be investigated. Driving force was the main property of interest, specifically how it varied with mandrel slopes and parallel midsection, to allow direct comparison with the earlier model. The variation of driving force with respect to coefficient of friction was investigated; driving force increased in near proportion, but a subtle trend indicated a further study of stress component be made. This was followed by a two-pass swage process. Close agreement was found with empirical data and the discrepancies observed between the two models are explained by the relatively coarse mesh used by the earlier model. This further verifies the sensitivity of the model described here

Technical Debt is an Ethical Issue

We introduce the problem of technical debt, with particular focus on critical infrastructure, and put forward our view that this is a digital ethics issue. We propose that the software engineering process must adapt its current notion of technical debt – focusing on technical costs – to include the potential cost to society if the technical debt is not addressed, and the cost of analysing, modelling and understanding this ethical debt. Finally, we provide an overview of the development of educational material – based on a collection of technical debt case studies - in order to teach about technical debt and its ethical implication