33,405 research outputs found

    A Monte Carlo Template based analysis for Air-Cherenkov Arrays

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    We present a high-performance event reconstruction algorithm: an Image Pixel-wise fit for Atmospheric Cherenkov Telescopes (ImPACT). The reconstruction algorithm is based around the likelihood fitting of camera pixel amplitudes to an expected image template. A maximum likelihood fit is performed to find the best-fit shower parameters. A related reconstruction algorithm has already been shown to provide significant improvements over traditional reconstruction for both the CAT and H.E.S.S. experiments. We demonstrate a significant improvement to the template generation step of the procedure, by the use of a full Monte Carlo air shower simulation in combination with a ray-tracing optics simulation to more accurately model the expected camera images. This reconstruction step is combined with an MVA-based background rejection. Examples are shown of the performance of the ImPACT analysis on both simulated and measured (from a strong VHE source) gamma-ray data from the H.E.S.S. array, demonstrating an improvement in sensitivity of more than a factor two in observation time over traditional image moments-fitting methods, with comparable performance to previous likelihood fitting analyses. ImPACT is a particularly promising approach for future large arrays such as the Cherenkov Telescope Array (CTA) due to its improved high-energy performance and suitability for arrays of mixed telescope types.Comment: 13 pages, 10 figure

    Hypotheses in Marketing Science: Literature Review and Publication Audit

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    We examined three approaches to research in marketing: exploratory hypotheses, dominant hypothesis, and competing hypotheses. Our review of empirical studies on scientific methodology suggests that the use of a single dominant hypothesis lacks objectivity relative to the use of exploratory and competing hypotheses approaches. We then conducted a publication audit of over 1,700 empirical papers in six leading marketing journals during 1984-1999. Of these, 74% used the dominant hypothesis approach, while 13 % used multiple competing hypotheses, and 13% were exploratory. Competing hypotheses were more commonly used for studying methods (25%) than models (17%) and phenomena (7%). Changes in the approach to hypotheses since 1984 have been modest; there was a slight decrease in the percentage of competing hypotheses to 11%, which is plained primarily by an increasing proportion of papers on phenomena. Of the studies based on hypothesis testing, only 11 % described the conditions under which the hypotheses would apply, and dominant hypotheses were below competing hypotheses in this regard. Marketing scientists differed substantially in their opinions about what types of studies should be published and what was published. On average, they did not think dominant hypotheses should be used as often as they were, and they underestimated their use

    Impact of European Water Framework Directive Article 7 on Drinking Water Directive compliance for pesticides: challenges of a prevention-led approach

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    Article 7 of the European Water Framework Directive (WFD) promotes a prevention-led approach to European Drinking Water Directive (DWD) compliance for those parameters that derive from anthropogenic influences on raw water quality. However, the efficacy of pollution prevention interventions is currently uncertain and likely to be variable, which makes absolute compliance with the drinking water standard a significant challenge. Member State governments, the WFD competent authority, the DWD competent authority, water suppliers and agriculture are all affected by and have a different perspective on the nature of this challenge. This paper presents a discussion of these perspectives applicable to stakeholders in all European Member States; the analysis is supported with examples from England and Wales. Improved understanding of the challenges faced by each group is needed if these groups are to achieve the shared goals of WFD Article 7 compliance and DWD compliance without a disproportionately negative impact on agricultural productivity. In addition, the European Commission needs to be aware of and address a potential incompatibility between WFD Article 7 and the DWD. With this in mind, targeted recommendations for action are presented for each stakeholder group

    WaND Briefing Note 28 Revised Options for UK Domestic Water Reduction - A Review

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    Demand pressure on UK water supplies is expected to increase in the next 20 years driven by increasing population, new housing development and reducing household size. Regionally and at town level migration will also affect demand particularly in the South-East which is forecast to have a larger than average growth in population and house building. The water demand moderating trends that are considered to have the greatest effect on UK consumption, in approximate order, are: 1. Metering 2. Low flush toilets 3. Normal showers 4. Efficient washing machines 5. Dishwashers 6. Cistern displacement devices (in existing homes with large cisterns) 7. Water efficient gardening measures can play an important role in reducing demand during critical drought period

    INCIDENTAL AND JOINT CONSUMPTION IN RECREATION DEMAND

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    A theory for analyzing incidental consumption in a single site recreation demand model is presented. We show that incidental consumption on a recreation trip, such as a visit to see friends or a visit to a second recreation site, can be treated as a complementary good and analyzed using conventional theory. We also show that the analysis applies whether the side trips are incidental or joint. In a simple application we find that failing to account for incidental consumption appears to create little bias in valuing recreation sites.Resource /Energy Economics and Policy,

    A simple screening method for determining knowledge of the appropriate levels of activity and risk behaviour in young people with congenital cardiac conditions

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    Objective: To assess a novel method for assessing risk and providing advice about activity to children and young people with congenital cardiac disease and their parents. Design and setting: Questionnaire survey in outpatient clinics at a tertiary centre dealing with congenital cardiac disease, and 6 peripheral clinics. Interventions: Children or their parents completed a brief questionnaire. If this indicated a desire for help, or a serious mismatch between advised and real level of activity, they were telephoned by a physiotherapist. Main measures of outcome: Knowledge about appropriate levels of activity, and identification of the number exercising at an unsafe level, the number seeking help, and the type of help required. Results: 253/258 (98.0%) questionnaires were returned, with 119/253 (47.0%) showing incorrect responses in their belief about their advised level of exercise; 17/253 (6.7%) had potentially dangerous overestimation of exercise. Asked if they wanted advice 93/253 (36.8%) said “yes”, 43/253 (17.0%) “maybe”, and 117/253 (46.2%) “no”. Of those contacted by phone to give advice, 72.7% (56/77) required a single contact and 14.3% (11/77) required an intervention that required more intensive contact lasting from 2 up to 12 weeks. Of the cohort, 3.9% (3/77) were taking part in activities that put them at significant risk. Conclusions: There is a significant lack of knowledge about appropriate levels of activity, and a desire for further advice, in children and young people with congenital cardiac disease. A few children may be at very significant risk. These needs can be identified, and clinical risk reduced, using a brief self-completed questionnaire combined with telephone follow-up from a suitably knowledgeable physiotherapist

    The Options for UK Domestic Water Reduction: A Review

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    Demand pressure on UK water supplies is expected to increase in the next 20 years driven by increasing population, new housing development and reducing household size. Regionally and locally migration will also afect demand particularly in the South-East. The water reduction trends that will have the greatest reduction effect on UK consumption are: 1. For new homes; metering and new efficiencies in design and construction (e.g. low flush toilets, heating and plumbing efficiences) 2. For established housing; metering and modern washing machines
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