177 research outputs found

    CoopeTárcoles, Costa Rica. Equator Initiative Case Study Series

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    The artisanal fishers of the community of Tárcoles, located in the Gulf of Nicoya on the Pacific coast of North America (Central America)-Costa Rica; faced declining fish stocks due to a combination of overharvesting by commercial shrimp boats and unsustainable local fishing practices. At the same time, development of the tourism sector along the coast threatened to restrict access to the shore and to marginalize their work. The local fishing cooperative Coope Tárcoles R.L. was founded in 1985 to confront these twin threats. At the forefront of these efforts has been the development of fishing bylaws that stress sustainable practices, enshrined in the community's 'Code of Responsible Fishing'. In partnership with CoopeSolidar R.L., the initiative launched a sustainable and community-based ecotourism venture in 2007 to provide an alternative source of income for local residents. In 2009, meanwhile, the group was successful in gaining approval of a community-managed marine area

    Formal Verification of the AAMP-FV Microcode

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    This report describes the experiences of Collins Avionics & Communications and SRI International in formally specifying and verifying the microcode in a Rockwell proprietary microprocessor, the AAMP-FV, using the PVS verification system. This project built extensively on earlier experiences using PVS to verify the microcode in the AAMP5, a complex, pipelined microprocessor designed for use in avionics displays and global positioning systems. While the AAMP5 experiment demonstrated the technical feasibility of formal verification of microcode, the steep learning curve encountered left unanswered the question of whether it could be performed at reasonable cost. The AAMP-FV project was conducted to determine whether the experience gained on the AAMP5 project could be used to make formal verification of microcode cost effective for safety-critical and high volume devices

    Efficient execution in an automated reasoning environment

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    We describe a method that permits the user of a mechanized mathematical logic to write elegant logical definitions while allowing sound and efficient execution. In particular, the features supporting this method allow the user to install, in a logically sound way, alternative executable counterparts for logically defined functions. These alternatives are often much more efficient than the logically equivalent terms they replace. These features have been implemented in the ACL2 theorem prover, and we discuss several applications of the features in ACL2.Ministerio de Educación y Ciencia TIN2004–0388

    Reverse engineering: transaminase biocatalystdevelopment using ancestral sequencereconstruction

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    The development of new biocatalysts using ancestral sequence reconstruction is reported. When applied to an ω-transaminase, the ancestral proteins demonstrated novel and superior activities with eighty percent of the forty compounds tested compared to the modern day protein, and improvements in activity of up to twenty fold. These included a range of compounds pertinent as feedstocks in polyamide manufacture.MW and SK were supported by CSIRO Research Office Postdoctoral Fellowships

    MAS-NMR Studies of Carbonate Retention in a Very Wide Range of Na2O-SiO2 Glasses

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    Glasses that contain carbon are of geological interest, and the form of that carbon can be probed by Magic-Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy. Previous studies of the Na2O-SiO2 glass system could only reach 56 mol% Na2O. Here we reproduce and extend those studies to cover a very wide compositional range, from 20 to 70 mol% Na2O, by using a combination of conventional melt-quench and twin roller quenching technologies on natural and 99% 13C-enriched sodium silicate glasses. 13C MAS-NMR reveals that measurable levels of carbon retention occur above at least 40 mol% Na2O,and takes the form of CO32- ions incorporated in the glass structure. These CO32- anions are surrounded by Na+ cations, forming nanoscale domains in a sodium silicate glass network. 23Na MAS-NMR showed a linear decrease in mean Na—O bond length with increasing Na2O content, up to 60 mol% Na2O, above which the mean Na—O bond length increased. Elemental analysis detected significant (>5%) carbonate by mass in the 65 and 70 mol% Na2O glasses. For the 70 mol% Na2O glass, 13C and 23Na MAS-NMR detected ordered nanoscale domains composed of only Na2O and CO2. These results have shown the quantity and nature of carbon retention in the archetypal sodium silicate glass system, which will better inform structural models and carbonate solubility limits

    High-Pressure Transformation of SiO2 Glass from a Tetrahedral to an Octahedral Network:A Joint Approach Using Neutron Diffraction and Molecular Dynamics

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    International audienceA combination of in situ high-pressure neutron diffraction at pressures up to 17.5(5) GPa and moleculardynamics simulations employing a many-body interatomic potential model is used to investigate thestructure of cold-compressed silica glass. The simulations give a good account of the neutron diffractionresults and of existing x-ray diffraction results at pressures up to ∼60 GPa. On the basis of the moleculardynamics results, an atomistic model for densification is proposed in which rings are “zipped” by a pairingof five- and/or sixfold coordinated Si sites. The model gives an accurate description for the dependence ofthe mean primitive ring size hni on the mean Si-O coordination number, thereby linking a parameter that issensitive to ordering on multiple length scales to a readily measurable parameter that describes the localcoordination environment

    Health for Wealth : Building a Healthier Northern Powerhouse for UK Productivity

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    There is a well-known productivity gap between the Northern Powerhouse and the rest of England of £4 perperson-per-hour. There is also a substantial health gap between the Northern Powerhouse and the rest of England, with average life expectancy 2 years lower in the North. Given that both health and productivity are lower in the Northern Powerhouse, the NHSA commissioned this report from six of its eight university members (Newcastle, Manchester, Lancaster, Liverpool, Sheeld and York) to understand the impact of poor health on productivity and to explore the opportunities for improving UK productivity by unlocking inclusive, green, regional growth through health improvement. Our report shows the importance of health and the NHS for productivity in the Northern Powerhouse. So, as it develops its post-Brexit industrial strategy, central government should pay particular attention to the importance of improving health in the Northern Powerhouse as a route to increased wealth

    Density-driven structural transformations in B2O3 glass

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    The method of in situ high-pressure neutron diffraction is used to investigate the structure of B2O3 glass on compression in the range from ambient to 17.5(5) GPa. The experimental results are supplemented by molecular dynamics simulations made using a newly developed aspherical ion model. The results tie together those obtained from other experimental techniques to reveal three densification regimes. In the first, BO3 triangles are the predominant structural motifs as the pressure is increased from ambient to 6.3(5) GPa, but there is an alteration to the intermediate range order which is associated with the dissolution of boroxol rings. In the second, BO4 motifs replace BO3 triangles at pressures beyond 6.3 GPa and the dissolution of boroxol rings continues until it is completed at 11–14 GPa. In the third, the B-O coordination number continues to increase with pressure to give a predominantly tetrahedral glass, a process that is completed at a pressure in excess of 22.5 GPa. On recovery of the glass to ambient from a pressure of 8.2 GPa, triangular BO3 motifs are recovered but, relative to the uncompressed material, there is a change to the intermediate range order. The comparison between experiment and simulation shows that the aspherical ion model is able to provide results of unprecedented accuracy at pressures up to at least 10 GPa

    Genomic Islands of Speciation in Anopheles gambiae

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    The African malaria mosquito, Anopheles gambiae sensu stricto (A. gambiae), provides a unique opportunity to study the evolution of reproductive isolation because it is divided into two sympatric, partially isolated subtaxa known as M form and S form. With the annotated genome of this species now available, high-throughput techniques can be applied to locate and characterize the genomic regions contributing to reproductive isolation. In order to quantify patterns of differentiation within A. gambiae, we hybridized population samples of genomic DNA from each form to Affymetrix GeneChip microarrays. We found that three regions, together encompassing less than 2.8 Mb, are the only locations where the M and S forms are significantly differentiated. Two of these regions are adjacent to centromeres, on Chromosomes 2L and X, and contain 50 and 12 predicted genes, respectively. Sequenced loci in these regions contain fixed differences between forms and no shared polymorphisms, while no fixed differences were found at nearby control loci. The third region, on Chromosome 2R, contains only five predicted genes; fixed differences in this region were also verified by direct sequencing. These “speciation islands” remain differentiated despite considerable gene flow, and are therefore expected to contain the genes responsible for reproductive isolation. Much effort has recently been applied to locating the genes and genetic changes responsible for reproductive isolation between species. Though much can be inferred about speciation by studying taxa that have diverged for millions of years, studying differentiation between taxa that are in the early stages of isolation will lead to a clearer view of the number and size of regions involved in the genetics of speciation. Despite appreciable levels of gene flow between the M and S forms of A. gambiae, we were able to isolate three small regions of differentiation where genes responsible for ecological and behavioral isolation are likely to be located. We expect reproductive isolation to be due to changes at a small number of loci, as these regions together contain only 67 predicted genes. Concentrating future mapping experiments on these regions should reveal the genes responsible for reproductive isolation between forms
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