5,802 research outputs found

    The removal of thermally aged films of triacylglycerides by surfactant solutions

    Get PDF
    Thermal ageing of triacylglycerides (TAG) at high temperatures produces films which resist removal using aqueous surfactant solutions. We used a mass loss method to investigate the removal of thermally aged TAG films from hard surfaces using aqueous solutions of surfactants of different charge types. It was found that cationic surfactants are most effective at high pH, whereas anionics are most effective at low pH and a non-ionic surfactant is most effective at intermediate pH. We showed that the TAG film removal process occurs in several stages. In the first ‘‘lag phase’’ no TAG removal occurs; the surfactant first partitions into the thermally aged film. In the second stage, the TAG film containing surfactant was removed by solubilisation into micelles in the aqueous solution. The effects of pH and surfactant charge on the TAG removal process correlate with the effects of these variables on the extent of surfactant partitioning to the TAG film and on the maximum extent of TAG solubilisation within the micelles. Additionally, we showed how the TAG removal is enhanced by the addition of amphiphilic additives such as alcohols which act as co-surfactants. The study demonstrates that aqueous surfactant solutions provide a viable and more benign alternative to current methods for the removal of thermally aged TAG films

    V<sub>H</sub> replacement in rearranged immunoglobulin genes

    Get PDF
    Examples suggesting that all or part of the V&lt;sub&gt;H&lt;/sub&gt; segment of a rearranged V&lt;sub&gt;H&lt;/sub&gt;DJ&lt;sub&gt;H&lt;/sub&gt; may be replaced by all or part of another V&lt;sub&gt;H&lt;/sub&gt; have been appearing since the 1980s. Evidence has been presented of two rather different types of replacement. One of these has gained acceptance and has now been clearly demonstrated to occur. The other, proposed more recently, has not yet gained general acceptance because the same effect can be produced by polymerase chain reaction artefact. We review both types of replacement including a critical examination of evidence for the latter. The first type involves RAG proteins and recombination signal sequences (RSS) and occurs in immature B cells. The second was also thought to be brought about by RAG proteins and RSS. However, it has been reported in hypermutating cells which are not thought to express RAG proteins but in which activation-induced cytidine deaminase (AID) has recently been shown to initiate homologous recombination. Re-examination of the published sequences reveals AID target sites in V&lt;sub&gt;H&lt;/sub&gt;-V&lt;sub&gt;H&lt;/sub&gt; junction regions and examples that resemble gene conversion

    Assessing the impact of regulations on the use and trade of wildlife: an operational framework, with a case study on manta rays

    Get PDF
    Overexploitation represents a significant threat to wildlife, with the severest impacts felt by slow growing, economically valuable species. Governments often seek to address this through regulating utilisation and trade of species, which is commonly catalysed by multi-lateral environmental agreements (MEAs) such as the Convention on the International Trade of Endangered Species (CITES). However, it is often unclear to what degree CITES and associated regulations lead to tangible conservation outcomes. Robust impact assessments are needed to understand whether regulations are effective for achieving biodiversity conservation goals, and to learn lessons for future policy interventions. Yet such assessments are hindered by data paucity, bias, complexity and uncertainty. Here we discuss key challenges for assessing the impact of regulations on the use and trade of wildlife, and offer a practical approach to overcome them. Our approach combines an integrated framework for collating and analysing disparate and methodologically inconsistent data with a robust process to establish causal inference (and hence assess impact). This framework and process can be applied to any regulation, species or country context. To demonstrate its utility we apply this approach to the case of manta ray utilisation and trade (Mobula alfredi and M. Birostris) in Indonesia. This case study is particularly important due to the recent increase in the number of commercially important elasmobranchs listed in CITES appendices, with Parties adopting various national-level regulations to implement their CITES commitments. However, it is unclear to what degree these listings lead to meaningful regulatory reform, and much-needed reductions in fishing mortality, utilisation and onward trade. Indonesia is also a priority country for effective regulatory reform, due to its role as a major source country for international elasmobranch trade. Overall, we highlight challenges and opportunities for assessing the impact of wildlife trade regulations, which are generalisable across species and contexts, and provide the first attempt to assess the impact of such regulatory change on manta ray mortality in a source country. We also offer recommendation for future implementation and evaluation, emphasising the importance of mixed-methods, multiple datasets, and explicit acknowledgement of bias and complexity

    Super-resolution far-field ghost imaging via compressive sampling

    Full text link
    Much more image details can be resolved by improving the system's imaging resolution and enhancing the resolution beyond the system's Rayleigh diffraction limit is generally called super-resolution. By combining the sparse prior property of images with the ghost imaging method, we demonstrated experimentally that super-resolution imaging can be nonlocally achieved in the far field even without looking at the object. Physical explanation of super-resolution ghost imaging via compressive sampling and its potential applications are also discussed.Comment: 4pages,4figure

    Parameterized vertex deletion problems for hereditary graph classes with a block property

    Get PDF
    For a class of graphs P, the Bounded P-Block Vertex Deletion problem asks, given a graph G on n vertices and positive integers k and d, whether there is a set S of at most k vertices such that each block of G − S has at most d vertices and is in P. We show that when P satisfies a natural hereditary property and is recognizable in polynomial time, Bounded P-Block Vertex Deletion can be solved in time 2O(k log d)nO(1), and this running time cannot be improved to 2o(k log d)nO(1), in general, unless the Exponential Time Hypothesis fails. On the other hand, if P consists of only complete graphs, or only K1,K2, and cycle graphs, then Bounded P-Block Vertex Deletion admits a cknO(1)-time algorithm for some constant c independent of d. We also show that Bounded P-Block Vertex Deletion admits a kernel with O(k2d7) vertices. © Springer-Verlag GmbH Germany 2016

    External sources of clean technology: evidence from the clean development mechanism

    Get PDF
    New technology is fundamental to sustainable development. However, inventors from industrialized countries often refuse technology transfer because they worry about reverse-engineering. When can clean technology transfer succeed? We develop a formal model of the political economy of North–South technology transfer. According to the model, technology transfer is possible if (1) the technology in focus has limited global commercial potential or (2) the host developing country does not have the capacity to absorb new technologies for commercial use. If both conditions fail, inventors from industrialized countries worry about the adverse competitiveness effects of reverse-engineering, so technology transfer fails. Data analysis of technology transfer in 4,894 projects implemented under the Kyoto Protocol’s Clean Development Mechanism during the 2004–2010 period provides evidence in support of the model

    Counterfactual reasoning and knowledge of possibilities

    Get PDF
    Williamson has argued against scepticism concerning our metaphysically modal knowledge, by arguing that standard patterns of suppositional reasoning to counterfactual conclusions provide reliable sources of correct ascriptions of possibility and necessity. The paper argues that, while Williamson’s claims relating to necessity may well be right, he has not provided adequate reasons for thinking that the familiar modes of counterfactual reasoning to which he points generalise to provide a decent route to ascriptions of possibility. The paper also explores another path to ascriptions of possibility that may be extracted from Williamson’s ideas, before briefly considering the general status of counterfactual reasoning in relation to our knowledge of possibilities

    Large changes in Great Britain’s vegetation and agricultural land-use predicted under unmitigated climate change

    Get PDF
    This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this recordData availability: The parameter values used for JULES is available from the suite u-ao645 and branch ‘full_UK’ on the Rosie repository: https://code.metoffice.gov.uk/trac/roses-u (registration required). The data that support the findings of this study are openly available at DOI.The impact of climate change on vegetation including agricultural production has been the focus of many studies. Climate change is expected to have heterogeneous effects across locations globally, and the diversity of land uses characterising Great Britain (GB) presents a unique opportunity to test methods for assessing climate change effects and impacts. GB is a relatively cool and damp country, hence, the warmer and generally drier growing season conditions projected for the future are expected to increase arable production. Here we use state-of-the-art, kilometre-scale climate change scenarios to drive a land surface model (JULES; Joint UK Land Environment Simulator) and an ECOnometric AGricultural land use model (ECO-AG). Under unmitigated climate change, by the end of the century, the growing season in GB is projected to get >5°C warmer and 140 mm drier on average. Rising levels of atmospheric CO2 are predicted to counteract the generally negative impacts of climate change on vegetation productivity in JULES. Given sufficient precipitation, warming favours higher value arable production over grassland agriculture, causing a predicted westward expansion of arable farming in ECO-AG. However, drying in the East and Southeast, without any CO2 fertilisation effect, is severe enough to cause a predicted reversion from arable to grassland farming. Irrigation, if implemented, could maintain this land in arable production. However, the predicted irrigation demand of ~200 mm (per growing season) in many locations is comparable to annual predicted runoff, potentially demanding large-scale redistribution of water between seasons and/or across the country. The strength of the CO2 fertilisation effect emerges as a crucial uncertainty in projecting the impact of climate change on GB vegetation, especially farming land-use decisions.Natural Environment Research Council (NERC)Joint UK BEIS/Defra Met Office Hadley Centre Climate Programm
    • …
    corecore