8,573 research outputs found

    Addressing the Multi-Channel Inverse Problem at High Energy Colliders: A Model Independent Approach to the Search for New Physics with Trileptons

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    We describe a method for interpreting trilepton searches at high energy colliders in a model-independent fashion and apply it to the recent searches at the Tevatron. The key step is to recognize that the trilepton signature is comprised of four experimentally very different channels defined by the number of tau-leptons in the trilepton state. Contributions from these multiple channels to the overall experimental sensitivity (cross section times branching ratio) are model-independent and can be parametrized in terms of relevant new particle masses. Given the trileptonic branching ratios of a specific model, these experimentally obtained multichannel sensitivities can be combined to obtain a cross section measurement that can be used to confront the model with data. Our model-independent results are more widely applicable than the current Tevatron trilepton results which are stated exclusively in terms of mSUGRA parameters of supersymmetry. The technique presented here can be expanded beyond trilepton searches to the more general "inverse problem" of experimentally discriminating between competing models that seek to explain new physics discovered in multiple channels.Comment: 17 pages, 7 figures Changed content cosmetic changes for submission to JHE

    Development of a low cost screen to identify hearing loss in young children and appropriate services for deaf children in Binga, Zimbabwe

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    There is a high prevalence of hearing loss estimated between 8 and 16% in young children in rural areas in Zimbabwe. Deaf children are usually identified late and do not benefit from early interventions. This study was conducted to evaluate a questionnaire screen in identifying permanent hearing loss in excess of 50dBHL of the better ear, compared with the pure-tone audiometric screen, in children aged 36-72 months living in Binga district, Zimbabwe. Subjects were recruited into the study by using two questions which identified 417 at-risk children who were registered as "Failing" children. In addition, 417 children were recruited as controls who were matched by age and sex and were registered as "Following" children (n=834). The "Questionnaire" screen used for this study had two parts; "Part I" had 8 general questions for every child, while "Part 2" had 3 age specific sections (A, B and C) with a set of 10 questions in each section and took between 20-25 minutes to administer for each child. The screen was administered on 747 (90%) children of the original sample (n=834) by four trained Tonga fluent interviewers, 87 children (10%) having dropped out. An experienced audiologist administered the gold standard pure-tone audiometry screen on the same 747 (90%) children who were "Questionnaire" screened. There were four test sound frequencies used: 0.5k, lk, 2k and 4k set at a flat cut-off point of 50dBHL generated by a calibrated Kamplex screening audiometer. The pure-tone screen administration required 10 - 15 minutes per child. Pass or fail results were plotted on the audiogram. For reliability testing of both the "Questionnaire" and the pure-tone screens, repeats were administered on 131 and 110 children respectively who were randomly selected from 747 children. Children with marked physical malforination, neurological problems and those for whom Tonga was not their first language were excluded from the study. The results revealed that the "Questionnaire" screen had a sensitivity of 79% and specificity of 96%. It was inter-and intra-user reliable (r---0.89) in identifying permanent hearing loss in children aged 36-72 months (p>0.05). The "Questionnaire" was easy to use and found to be a low-cost screen that can be appropriately adapted and used in service delivery or research programmes in different cultural settings in developing countries

    On the Temperature Distribution of a Viscous In-Compressible Fluid in a Circular Pipe Under Unsteady Rate of Heat Addition

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    A Note on the Linear Flow of a Viscous Incompressible Conducting Fluid Past an Infinite Flat Plate with Constant Suction in the Presence of a Transverse Magnetic Field

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    Analytical solution has been obtained for the momentum Equations of the linear flow of a viscous in compressible electrically conducting fluid past an infinite porous flat plate in the presence of a transverse magnetic field when the suction velocity normal to the plate is constant. It is observed that the velocity in the boundary layer increases with the increase of the intensity of the magnetic field

    Iterated Stieltjes transform of generalized functions

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    The generalized S2-transform of a member of f of a certain space of generalized functions is defined as F(x)=〈f(t),k(x,t;ρ)〉, wherek(x,t;ρ)=∫0∞1(x+y)ρ(y+t)ρ  dy,  ρ>12,0<x<∞  and  0<t<∞. An inversion theorem for the transform is established interpreting the oonvergene in the weak distributional sense

    Comment on: `Pipe Network Model for Scaling of Dynamic Interfaces in Porous Media'

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    We argue that a proposed exponent identity [Phys. Rev. Lett 85, 1238 (2000)] for interface roughening in spontaneous imbibition is wrong. It rests on the assumption that the fluctuations are controlled by a single time scale, but liquid conservation imposes two distinct time scales.Comment: 1 page, to appear in Phys. Rev. Let

    Consumers’ views and use of labels on food items sold in Bulawayo urban province, Zimbabwe

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    Food labels are a medium by which consumers acquire knowledge about packaged foods they are considering to purchase. The label makes the first impression about a product and has a great effect on the purchasing decision for consumers. In recent years, literate consumers have become interested in nutritional issues. Lifestyle, age, dietary and safety concerns have been the contributing factors to nutritional awareness by consumers. Nutritional labels can generally have a positive impact on food consumption and may save health-care costs for those consumers with health concerns. On the other hand, for those consumers who are illiterate, price may be more important in making purchase decisions. This study intended to investigate how consumers in Bulawayo Urban Province (Zimbabwe) view and use labels on packaged food items. Seventy-five randomly selected consumers were questioned about their perceptions, attitudes and use of label information using open ended structured questionnaires. The consumers were selected on the basis of being present at the supermarkets at the time of sampling. The respondents were interviewed at different times of the day to cater for employed and unemployed people. The results obtained indicate that the extent to which food labels are used depends on factors such as price of food products, individual health needs and gender. For consumers who use food labels to make their purchase decisions, not all the information on the label is considered. Items on the labels to which the consumers responded were brand, nutritional profile and mass of product in relation to the price. The label elements which were extensively used by consumers in this study are date mark (81.3%), weight of food (89.3%) and price (77.3%). The least used element is the nutritional panel (50.7%). About 44% of the consumers were not sure about the trustworthiness of the information given on food labels. Food labels are important to a greater extent for people with special dietary requirements, while the remainder of the studied population are influenced by price in their purchase decisions. Consumers seem not to understand some of the information on the food labels because of the difficulties in interpreting what is written.Keywords: Consumer, packaged food, labels, nutrition, nutritional panel, perceptions, purchase, behaviou

    Analysis of design strategies for mitigating the consequences of lithium fire within containment of controlled thermonuclear reactors

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    Originally presented as the first author's thesis, (M.S.)--in the M.I.T. Dept. of Nuclear Engineering, 1978Includes bibliographical references (pages 117-121)Report issued under U.S. Dept. of Energy EY-76-02-243