722 research outputs found

    Beam extrapolation and photosensor testing for the T2K experiment

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    Our understanding of the physics of neutrino oscillations has evolved rapidly over the past decade or so, with results from the SNO, Super-K, MINOS and CHOOZ experiments, among others, producing results favouring a three-neutrino mixing model, and significantly constraining the parameter space for this mixing. There are still several important questions to be answered however: we do not know whether Θ13 is non-zero, or whether (sin2 2Θ23) is maximal; also, we do not know the sign of the large mass splitting ΔM2, or whether CP-violation occurs in the lepton sector. The latter is possibly the most exciting of all - leptonic CP- violation is a requirement for leptogenesis, and could therefore indicate a solution to the matter-antimatter asymmetry problem in cosmology. The T2K long-baseline neutrino experiment is one of a new generation of neutrino projects, which will make more precise measurements of Θ13 and Θ23 than has been achieved by previous experiments. It uses the Super-K water Čerenkov detector at Kamioka as a far detector, and also has a suite of new near detectors. These are largely scintillator-based, but use a novel photosensor, the silicon photomultiplier (SiPM), for light readout. T2K has been leading the effort to understand and model these new sensors, and the present work will describe the current state-of-the-art in device characterisation, and also the effort to ensure the quality of the devices installed in the calorimeter of the ND280 near detector. An important part of a long-baseline analysis is the extrapolation of the neutrino flux measured at the near detector to predict that at the far detector. Methods to do this have been developed by previous experiments; however T2K uses an innovative configuration whereby the main detectors are displaced from the neutrino beam centre, removing much of the high-energy tail in the neutrino flux to reduce background from non-quasielastic events. This thesis evaluates the effectiveness of two extrapolation techniques, used by previous experiments, for the T2K configuration

    Editorial: Hazards and Disasters: Learning, Teaching, Communication and Knowledge Exchange

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    Geography’s ‘unique selling point’, alongside its concern for spatial relationships, is its ability to unite social and environmental perspectives. Amidst a large literature, Ravi Singh (2009, p. 2) suggests, “The general trends in the history of geographical thoughts do suggest our discipline’s guiding principle has been its integrated perspective under which human and physical (natural) domains are simultaneously considered interconnected and interrelated”. He also suggests that a key item ..

    Connective practices in sustainability education

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    Connective practices are affective educational activities and critical for sustainability education. They bridge the gap between knowledge of environmental problems and the will, personally, to do something about them. Three sources of pedagogic theory are tapped for this application to sustainability education. From Deep Ecology comes the pedagogic ladder leading to recognition of the Ecological Self, the deep intuitive appreciation of being a part of the living Earth. The Connective Practice concept comes from Social Sculpture and the provocative artistic and political work of Joseph Beuys, whose notion of participatory response-ability envisages actions that unleash the positive creative potential of every individual. For Beuys, everyone is an artist and everyone can become a world-maker. Finally, Invitational Education adds concern for the learner’s inner being. Learning invitations aim to remove the obstacles that hold learners back from positive creativity. It also fosters learner engagement by developing the positive aspects of the whole learning environment, building care trust, respect and optimism from the sum of people, places, processes, programs and policies. Two case studies illustrate the task of inviting learners to develop pro-sustainability values and affirm them by a personal creative response. In the Karma to Climate Change project, scriptural quotations and environmental information combine to invite learners to make a personal religious pledge to adopt a more pro-sustainability lifestyle. In the Restoration of Wychwood Forest project, learners join local community volunteers to plant trees and later reflect on the wider personal significance of their enacting sustainability values

    Short-term variability in satellite-derived cloud cover and galactic cosmic rays: an update

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    Previous work by Todd and Kniveton (2001) (TK2001) has indicated a statistically significant association (at the daily timescale) between short-term reductions in galactic cosmic rays, specifically Forbush decrease (FD) events, and reduced cloud cover, mainly over Antarctica (as recorded in International Satellite Cloud Climatology Project (ISCCP) D1 data). This study presents an extension of the previous work using an extended dataset of FD events and ISCCP cloud data over the period 1983-2000, to establish how stable the observed cloud anomalies are. Composite analysis of ISCCP data based on a sample of 32 FD events (excluding those coincident with solar proton events) indicates cloud anomalies with a very similar space/time structure to that previously reported, although of smaller magnitude. Substantial reductions in high level cloud (up to 12% for zonal mean, compared to 18% reported by TK2001) are observed over the high geomagnetic latitudes, especially of the southern hemisphere immediately following FD event onset. Largest anomalies are centred on the Antarctic plateau region during austral winter. However, the largest cloud anomalies occur where the accuracy of the ISCCP cloud retrievals is likely to be lowest, such that the results must be treated with extreme caution. Moreover, significant positive composite mean surface and tropospheric temperature anomalies centred over the same region are also observed for the FD sample from the National Center for Environmental Prediction (NCEP) reanalysis data. Such increased temperatures are inconsistent with the radiative effect of a reduction in high-level cloud during local winter. Overall, the results do not provide strong evidence of a direct galactic cosmic ray/cloud association at short timescales. The results highlight (a) the potential problems of data quality in the high latitude regions (b) the problems inherent in inferring cause and effect relationships from observational data alone (c) the need for further research to test competing hypotheses

    Changes in Management Can Improve Returns from Cambodian Upland Crops

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    Farming systems research for wet-season non-rice upland crops in Cambodia is being conducted with the overall aim of poverty reduction and food security for farmers in the Provinces of Battambang and Kampong Cham. Some of these cash crops exhibit low and variable incomes, especially when grown in the early wet season. Cambodian farmers may borrow money to buy crop inputs and often sell their produce to companies and traders from neighbouring countries, hence they are price takers. Some new crop technologies are evaluated which relate to soil and crop fertility management interacting with climatic factors. The DSSAT crop simulation model is used to predict outcomes from alternative management strategies. Bio-economic analyses are conducted to assess the likely appeal of these technologies to Cambodian farmers in a return-on-investment context. The results show that management to adjust the nitrogen fertility available to corn, the use of rhizobium in soybean, and a delay in planting early-wet-season corn may all show substantial financial benefits. Further research and an associated farmer demonstration program involving local extension officers are recommended.Upland crops, Cambodia, technology, economics, simulation, risk, Crop Production/Industries,

    Atmospheric temperature responses to solar irradiance and geomagnetic activity

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    The relative effects of solar irradiance and geomagnetic activity on the atmospheric temperature anomalies (Ta) are examined from the monthly to interdecadal timescales. Geomagnetic Ap (Ap) signals are found primarily in the stratosphere, while the solar F10.7-cm radio flux (Fs) signals are found in both the stratosphere and troposphere. In the troposphere, 0.1–0.4 K increases in Ta are associated with Fs. Enhanced Fs signals are found when the stratospheric quasi-biennial oscillation (QBO) is westerly. In the extrapolar region of the stratosphere, 0.1–0.6 and 0.1–0.7 K increases in Ta are associated with solar irradiance and with geomagnetic activity, respectively. In this region, Fs signals are strengthened when either the QBO is easterly, or geomagnetic activity is high, while Ap signals are strengthened when either the QBO is westerly, or solar irradiance is high. High solar irradiance and geomagnetic activity tend to enhance each other's signatures either making the signals stronger and symmetric about the equator or extending the signals to broader areas, or both. Positive Ap signals dominate the middle Arctic stratosphere and are two to five times larger than those of Fs. When solar irradiance is low, the signature of Ap in Ta is asymmetric about the equator, with positive signals in the Arctic stratosphere and negative signals at midlatitudes of the NH stratosphere. Weaker stratospheric QBO signals are associated with high Ap and Fs, suggesting possible disturbances on the QBO. The signals of Ap and Fs are distinct from the positive temperature anomalies resulting from volcanic eruptions

    A participatory approach to variety trials for organic systems

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    A participatory research methodology was used to compare the performance of UK wheat varieties under organic conditions. Plots of three breadmaking winter wheat varieties (Hereward, Solstice and Xi19) and a mixture (1:1:1) of the varieties were grown at 19 UK farms in two seasons (2003/04 and 2004/05). Meas-urements were taken of growth habit, yield and grain quality. Grain yields in both seasons showed significant site by variety interactions, although the variation among sites was greater than among varieties in both instances. Wheat grown at Western sites was significantly shorter and higher-yielding than that grown at Eastern sites in 2003/04 but significantly taller in 2004/05. As with grain yield, greater variation among site than variety was found in the Hagberg Falling Number and protein concentra-tion results in both seasons. The results from the two years of trials illustrate the variability of organic systems and the difficulty in selecting a single variety suitable for organic farms
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