2,666 research outputs found

    Development of Advanced NDE Ultrasonic Equipment

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    Recent studies to determine the probability of detection of nondestructive examination methods by the Air Force indicate that these capabilities are severely limited. One of the factors contributing to the insufficiency of ultrasonic testing is related to a general lack of versatility and capability of commercial ultrasonic equipment. Inadequate instrument reliability, inconsistent components including transducers, and uncertain calibration standards further compromise the potential utility of this method. Battelle Pacific Northwest Laboratories, under the sponsorship of the manufacturing Technology Division of the Air Force Materials Laboratory, is developing an advanced ultrasonic nondestructive testing system directed at resolving these defficiencies. As a result, this program will establish a modular ultrasonic system specification that will prevent near term obsolescence by permitting the addition of new technology such as ARPA developments in the form of additional or replacement modules. This paper will describe the Phase I and II tasks and objectives which are planned to establish an equipment specification, demonstrate initial prototype systems, and provide a procurement specification and technical manuals. Progress to date will be summarized

    Observations on the ecology of arctic foxes Alopex lagopus in Eqalummiut Nunaat, West Greenland

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    Information on diet, home range and activity of arctic foxes Alopex lagopus was collected by radio-tracking and faecal analysis in Eqalummiut Nunaat, West Greenland during spring and summer 1984. The study aimed to investigate the feeding ecology of foxes in an area where »traditional« prey such as lemmings Dicrostonyx groenlandicus and coastal food sources are absent. Foxes were found to be heavily dependent on abundant caribou Rangifer tarandus carrion, and invertebrates found in the layer of soil above the permafrost. Scat analysis and behavioural observations showed that foxes were quick to modify their foraging to exploit seasonal changes in food availability, and preyed heavily on nesting birds, mainly passerines, when these became available. Mean home range size of two radio-tagged female foxes was 11.7 km2. It was thought that fox density was unusually high due to the abundance of caribou carrion as a result of the exceptionally long preceding winter. The incidence of food caches was investigated and it was found that most were unearthed in June, after the thaw and just before passerine prey became abundant. White-fronted goose eggs and caribou carrion were the items most frequently found at unearthed caches. Observations and radio-tracking revealed that foxes predominated in lowland areas, generally avoiding plateau areas above 500 m, where passerines and caribou carrion were scarce. Foxes were found 10 be 50% more numerous on the study area in 1984 than in 1979, and this was felt to be related to differences in the availability of caribou carrion. Foxes were found to be major predators of the eggs of Greenland White-fronted geese

    Managing the mutations: Academic misconduct Australia, New Zealand and the UK

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    Academic misconduct is a problem of growing concern across the tertiary education sector. While plagiarism has been the most common form of academic misconduct, the advent of software programs to detect plagiarism has seen the problem of misconduct simply mutate. As universities attempt to function in an increasingly complex environment, the factors that contribute to academic misconduct are unlikely to be easily mitigated. A multiple case study approach examined how academic misconduct is perceived in universities in in Australia, New Zealand and the United Kingdom via interviews with academics and administrators. The findings show that academic misconduct is a systemic problem that manifests in various ways and requires similarly diverse approaches to management. Greater consistency in policies and procedures, including a focus on preventative education for both staff and students, is key, to managing the mutations of academic misconduct that continue to plague the higher education sector globally

    The high-lying 6^6Li levels at excitation energy around 21 MeV

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    The 3^3H+3^3He cluster structure in 6^6Li was investigated by the 3^3H(α\alpha,3^3H 3^3He)n kinematically complete experiment at the incident energy EαE_\alpha = 67.2 MeV. We have observed two resonances at ExE_x^* = 21.30 and 21.90 MeV which are consistent with the 3^3He(3^3H, γ\gamma)6^6Li analysis in the Ajzenberg-Selove compilation. Our data are compared with the previous experimental data and the RGM and CSRGM calculations.Comment: 12 pages, 6 figures. Accepted for publication in J. Phys. Soc. Jp

    The development of a new measure of quality of life for children with congenital cardiac disease

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    The purpose of the study was to develop a questionnaire measuring health-related R1 quality of life for children and adolescents with congenital heart disease, the ConQol, that would have both clinical and research applications. We describe here the process of construction of a questionnaire, the piloting and the development of a weighted scoring system, and data on the psychometric performance of the measure in a sample of 640 children and young people recruited via 6 regional centres for paediatric cardiology from across the United Kingdom. The ConQol has two versions, one designed for children aged from 8 to 11 years, and the other for young people aged from 12 to 16 years. Initial findings suggest that it is a valid and reliable instrument, is acceptable to respondents, and is simple to administer in both a research and clinical context

    Low-loss criterion and effective area considerations for photonic crystal fibers

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    We study the class of endlessly single-mode all-silica photonic crystal fibers with a triangular air-hole cladding. We consider the sensibility to longitudinal nonuniformities and the consequences and limitations for realizing low-loss large-mode area photonic crystal fibers. We also discuss the dominating scattering mechanism and experimentally we confirm that both macro and micro-bending can be the limiting factor.Comment: Accepted for Journal of Optics A - Pure and Applied Optic

    The radical character of the acenes: A density matrix renormalization group study

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    We present a detailed investigation of the acene series using high-level wavefunction theory. Our ab-initio Density Matrix Renormalization Group algorithm has enabled us to carry out Complete Active Space calculations on the acenes from napthalene to dodecacene correlating the full pi-valence space. While we find that the ground-state is a singlet for all chain-lengths, examination of several measures of radical character, including the natural orbitals, effective number of unpaired electrons, and various correlation functions, suggests that the longer acene ground-states are polyradical in nature.Comment: 10 pages, 8 figures, supplementary material, to be published in J. Chem. Phys. 127, 200
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