872 research outputs found

    Drivers of vegetation change in grasslands of the Sheffield region, northern England, between 1965 and 2012/13

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    Questions: How has vegetation species diversity and species composition changed between 1965 and 2012/13 in acidic and calcareous grasslands? What has driven this change in vegetation? Location: A 2400-km2 area around Sheffield, northern England. Methods: In 1965 a survey was conducted to describe grassland vegetation of the Sheffield region. We repeated this survey in 2012/13, revisiting acidic and calcareous grassland sites (455 quadrats). Climate, N and sulphur deposition, cattle and sheep stocking rates, soil pH, altitude, aspect and slope were considered to be potential drivers of variation in vegetation. We analysed temporal changes in vegetation and examined relationships with spatial and temporal variation in driver variables. Results: Both acidic and calcareous grasslands showed clear changes in species composition between the two time periods. In acidic grasslands there was no significant change in richness but there were declines in diversity. There were significant increases in Ellenberg N. Nitrogen deposition and grazing were identified as potential drivers of spatial and temporal patterns but it was not possible to discriminate the respective impacts of potential drivers. In calcareous grasslands there were declines in species richness, diversity and appropriate diversity indices. Climate and soil pH were identified as potential drivers of spatial and temporal patterns. Conclusions: Despite only small site losses compared to other surveys in the UK, especially within the national park, both calcareous and acidic grasslands showed very clear changes in species composition. In acidic grasslands, high abundance of Pteridium aquilinum was a particular problem and had increased considerably between the two survey periods. Atmospheric N deposition and grazing were identified as drivers of species diversity. A number of calcareous grasslands showed signs of reduced management intensity leading to scrub invasion

    Electrophysiological and behavioral responses of female African rice gall midge, Orseolia oryzivora Harris and Gagné, to host plant volatiles

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    African rice gall midge, Orseolia oryzivora Harris and Gagné, is a major pest of rice in Africa. Depsite its economic importance, its chemical ecology is not well understood. Here, we assessed behavioral and electrophysiological responses of O. oryzivora to host plant volatiles. In olfactometer bioassays, mated female O. oryzivora were attracted to volatiles emitted from intact rice plants but were repelled by volatiles collected from plants infested by conspecifics. In a choice test, there was a preference for volatiles from uninfested plants over those from infested plants. Coupled gas chromatography-electroantennography analyses of panicle volatiles isolated four electrophysiologically active components: (S)-linalool, 4,8-dimethyl-1,3,7-nonatriene, (E)-caryophyllene, and (R/S)-(E)-nerolidol. A synthetic blend of volatiles at the same concentration and ratio as that from an intact plant was attractive to mated females, whereas a blend based on the ratio of volatiles from an infested plant was repellent. This suggests that O. oryzivora uses olfaction for host plant recognition. The identification of blends of volatiles emitted by plants that can both attract and repel O. oryzivora may aid the development of sustainable control measures

    Development of shipping in Guyana

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    The landscape ecological impact of afforestation on the British uplands and some initiatives to restore native woodland cover

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    The majority of forest cover in the British Uplands had been lost by the beginning of the Nineteenth Century, because of felling followed by overgrazing by sheep and deer. The situation remained unchanged until a government policy of afforestation, mainly by exotic conifers, after the First World War up to the present day. This paper analyses the distribution of these predominantly coniferous plantations, and shows how they occupy specific parts of upland landscapes in different zones throughout Britain. Whilst some landscapes are dominated by these new forests, elsewhere the blocks of trees are more localised. Although these forests virtually eliminate native ground vegetation, except in rides and unplanted land, the major negative impacts are at the landscape level. For example, drainage systems are altered and ancient cultural landscape patterns are destroyed. These impacts are summarised and possible ways of amelioration are discussed. By contrast, in recent years, a series of projects have been set up to restore native forest cover, as opposed to the extensive plantations of exotic species. Accordingly, the paper then provides three examples of such initiatives designed to restore native forests to otherwise bare landscapes, as well as setting them into a policy context. Whilst such projects cover a limited proportion of the British Uplands they nevertheless restore forest to landscapes at a local level

    Live-Cell Imaging of Cellular Proteins by a Strain-Promoted Azide–Alkyne Cycloaddition

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    Live and let dye: Three coumarin-cyclooctyne conjugates have been used to label proteins tagged with azidohomoalanine in Rat-1 fibroblasts. All three fluorophores labeled intracellular proteins with fluorescence enhancements ranging from eight- to 20-fold. These conjugates are powerful tools for visualizing biomolecule dynamics in living cells

    The meaning of life in a developing universe

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    The evolution of life on Earth has produced an organism that is beginning to model and understand its own evolution and the possible future evolution of life in the universe. These models and associated evidence show that evolution on Earth has a trajectory. The scale over which living processes are organized cooperatively has increased progressively, as has its evolvability. Recent theoretical advances raise the possibility that this trajectory is itself part of a wider developmental process. According to these theories, the developmental process has been shaped by a larger evolutionary process that involves the reproduction of universes. This evolutionary process has tuned the key parameters of the universe to increase the likelihood that life will emerge and develop to produce outcomes that are successful in the larger process (e.g. a key outcome may be to produce life and intelligence that intentionally reproduces the universe and tunes the parameters of ‘offspring’ universes). Theory suggests that when life emerges on a planet, it moves along this trajectory of its own accord. However, at a particular point evolution will continue to advance only if organisms emerge that decide to advance the evolutionary process intentionally. The organisms must be prepared to make this commitment even though the ultimate nature and destination of the process is uncertain, and may forever remain unknown. Organisms that complete this transition to intentional evolution will drive the further development of life and intelligence in the universe. Humanity’s increasing understanding of the evolution of life in the universe is rapidly bringing it to the threshold of this major evolutionary transition

    Captive reptile mortality rates in the home and implications for the wildlife trade

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    The trade in wildlife and keeping of exotic pets is subject to varying levels of national and international regulation and is a topic often attracting controversy. Reptiles are popular exotic pets and comprise a substantial component of the live animal trade. High mortality of traded animals raises welfare concerns, and also has implications for conservation if collection from the wild is required to meet demand. Mortality of reptiles can occur at any stage of the trade chain from collector to consumer. However, there is limited information on mortality rates of reptiles across trade chains, particularly amongst final consumers in the home. We investigated mortality rates of reptiles amongst consumers using a specialised technique for asking sensitive questions, additive Randomised Response Technique (aRRT), as well as direct questioning (DQ). Overall, 3.6% of snakes, chelonians and lizards died within one year of acquisition. Boas and pythons had the lowest reported mortality rates of 1.9% and chameleons had the highest at 28.2%. More than 97% of snakes, 87% of lizards and 69% of chelonians acquired by respondents over five years were reported to be captive bred and results suggest that mortality rates may be lowest for captive bred individuals. Estimates of mortality from aRRT and DQ did not differ significantly which is in line with our findings that respondents did not find questions about reptile mortality to be sensitive. This research suggests that captive reptile mortality in the home is rather low, and identifies those taxa where further effort could be made to reduce mortality rate

    The reaction of benzyne with acridine

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    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
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