44 research outputs found

    Systematic behaviour of the in-plane penetration depth in d-wave cuprates

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    We report the temperature T and oxygen concentration dependences of the penetration depth of grain-aligned YBa_2Cu_3O_{7-\delta} with \delta= 0.0, 0.3 and 0.43. The values of the in-plane \lambda_{ab}(0) and out-of-plane \lambda_{c}(0) penetration depths, the low temperature linear term in \lambda_{ab}(T), and the ratio \lambda_{c}(0) /\lambda_{ab}(T) were found to increase with increasing δ\delta. The systematic changes of the linear term in \lambda_{ab}(T) with T_c found here and in recent work on HgBa_2Ca_{n-1} Cu_nO_{2n+2+\delta} (n = 1 and 3) are discussed.Comment: 4 pages, 4 figure

    Decoupled CuO_2 and RuO_2 layers in superconducting and magnetically ordered RuSr_2GdCu_2O_8

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    Comprehensive measurements of dc and ac susceptibility, dc resistance, magnetoresistance, Hall resistivity, and microwave absorption and dispersion in fields up to 8 T have been carried out on RuSr_2GdCu_2O_8 with the aim to establish the properties of RuO_2 and CuO_2 planes. At ~130 K, where the magnetic order develops in the RuO_2 planes, one observes a change in the slope of dc resistance, change in the sign of magnetoresistance, and the appearance of an extraordinary Hall effect. These features indicate that the RuO_2 planes are conducting. A detailed analysis of the ac susceptibility and microwave data on both, ceramic and powder samples show that the penetration depth remains frequency dependent and larger than the London penetration depth even at low temperatures. We conclude that the conductivity in the RuO_2 planes remains normal even when superconducting order is developed in the CuO_2 planes below \~45 K. Thus, experimental evidence is provided in support of theoretical models which base the coexistence of superconductivity and magnetic order on decoupled CuO_2 and RuO_2 planes.Comment: 11 pages, 11 figures, submitted to PR

    Metabolic and endocrinologic complications in beta-thalassemia major: a multicenter study in Tehran

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    BACKGROUND: The combination of transfusion and chelation therapy has dramatically extended the life expectancy of thalassemic patients. The main objective of this study is to determine the prevalence of prominent thalassemia complications. METHODS: Two hundred twenty patients entered the study. Physicians collected demographic and anthropometric data and the history of therapies as well as menstrual histories. Patients have been examined to determine their pubertal status. Serum levels of 25(OH) D, calcium, phosphate, iPTH were measured. Thyroid function was assessed by T3, T4 and TSH. Zinc and copper in serum were determined by flame atomic absorption spectrophotometry. Bone mineral density (BMD) measurements at lumbar and femoral regions have been done using dual x-ray absorptiometry. The dietary calcium, zinc and copper intakes were estimated by food-frequency questionnaires. RESULTS: Short stature was seen in 39.3% of our patients. Hypogonadism was seen in 22.9% of boys and 12.2% of girls. Hypoparathyroidism and primary hypothyroidism was present in 7.6% and 7.7% of the patients. About 13 % of patients had more than one endocrine complication with mean serum ferritin of 1678 ± 955 micrograms/lit. Prevalence of lumbar osteoporosis and osteopenia were 50.7% and 39.4%. Femoral osteoporosis and osteopenia were present in 10.8% and 36.9% of the patients. Lumbar BMD abnormalities were associated with duration of chelation therapy. Low serum zinc and copper was observed in 79.6% and 68% of the study population respectively. Serum zinc showed significant association with lumbar but not femoral BMD. In 37.2% of patients serum levels of 25(OH) D below 23 nmol/l were detected. CONCLUSION: High prevalence of complications among our thalassemics signifies the importance of more detailed studies along with therapeutic interventions

    Effect of cation substitution on the physical properties of the high temperature superconductor YBa_2Cu_3O_7_-_#delta#

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    SIGLEAvailable from British Library Document Supply Centre-DSC:D195596 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Scoring methods for prioritizing and selecting innovation projects

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    An approach for designing multi-factor scoring systems for evaluating and selecting early stage innovation projects is presented. A project is a piece of work of finite duration with finite resources, aimed at a defined outcome. Innovation projects have the extra complication that all of these aspects will be somewhat uncertain and knowledge of them is liable to change as the project proceeds. Clearly different assessment factors are required for different organizations, and for different types and stages of project. There is little guidance in the literature on how to choose the factors and how best to structure the scoring process. The approach is presented in the form of managerial guidelines, targeted at those who have to implement innovation project selection systems. Design aspects are discussed, including structure of the tool, choosing the factors, scaling statements, weightings, risk, uncertainty and confidence. Management aspects are considered, including preparation, scoring, decisions and outputs. The method is positioned in terms of theory and practice, with reference to both literature and industrial case studies. The paper concludes with a discussion of practical and theoretical contributions, and highlights areas that would benefit from further research

    SME Innovation – practice and needs, lessons from the PrISMS programme

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    Innovation management is widely recognised as an integral part of strategic thinking in firms, and has become an area of rapidly growing interest within academia and industry. However, amid calls for practical approaches to support implementation of innovation in smaller manufacturing firms, there is a lack of practice-based knowledge about innovation management in such companies and how it is related to and influenced by their operational strengths and constraints. This paper reviews the innovation practices and needs of seven manufacturing SMEs by drawing on data from outputs of the PrISMS project, a European-funded manufacturing development programme, in the context of the SME innovation literature. Using data from the PrISMS programme we explore how this small group of SMEs approach innovation drawing upon their operational context, looking at their current practices and where they require further support to grow their businesses sustainably

    Mapping experience in organizations: A learning process for strategic technology planning

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    Today's fast-paced, dynamic environments mean that for organizations to keep “ahead of the game”, engineering managers need to maximize current opportunities and avoid repeating past mistakes. This article describes the development study of a collaborative strategic management tool – the Experience Scan – to capture past experience and apply learning from this to present and future situations. Experience Scan workshops were held in a number of different technology organizations, developing and refining the tool until its format stabilized. From participants' feedback, the workshop-based tool was judged to be a useful and efficient mechanism for communication and knowledge management, contributing to organizational learning. © 2013 by the American Society for Engineering Management
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