1,443 research outputs found

    Feasibility study of resistance welding of aluminum alloys, stainless steel, and titanium in a hard vacuum Final report, Jun. 27, 1967 - Feb. 29, 1968

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    Tensile strength and X ray analysis of resistance spot welded aluminum and stainless steel alloy

    Fiat Money and the Distribution of Incomes and Wealth

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    Under a fiat money system, the money supply is subject to the human will. It therefore tends to grow faster than under a commodity money system. We analyse the implications of this fact for the distribution of incomes, and especially for the distribution of wealth. We argue that fiat money systems tend to increase the gap between incomes and wealth and also tend to leverage income differences into even greater differences of wealth.

    Climate change impact, adaptation, and mitigation in temperate grazing systems: a review

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    Managed temperate grasslands occupy 25% of the world, which is 70% of global agricultural land. These lands are an important source of food for the global population. This review paper examines the impacts of climate change on managed temperate grasslands and grassland-based livestock and effectiveness of adaptation and mitigation options and their interactions. The paper clarifies that moderately elevated atmospheric CO2 (eCO2) enhances photosynthesis, however it may be restiricted by variations in rainfall and temperature, shifts in plant’s growing seasons, and nutrient availability. Different responses of plant functional types and their photosynthetic pathways to the combined effects of climatic change may result in compositional changes in plant communities, while more research is required to clarify the specific responses. We have also considered how other interacting factors, such as a progressive nitrogen limitation (PNL) of soils under eCO2, may affect interactions of the animal and the environment and the associated production. In addition to observed and modelled declines in grasslands productivity, changes in forage quality are expected. The health and productivity of grassland-based livestock are expected to decline through direct and indirect effects from climate change. Livestock enterprises are also significant cause of increased global greenhouse gas (GHG) emissions (about 14.5%), so climate risk-management is partly to develop and apply effective mitigation measures. Overall, our finding indicates complex impact that will vary by region, with more negative than positive impacts. This means that both wins and losses for grassland managers can be expected in different circumstances, thus the analysis of climate change impact required with potential adaptations and mitigation strategies to be developed at local and regional levels

    Symbolic Manipulators Affect Mathematical Mindsets

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    Symbolic calculators like Mathematica are becoming more commonplace among upper level physics students. The presence of such a powerful calculator can couple strongly to the type of mathematical reasoning students employ. It does not merely offer a convenient way to perform the computations students would have otherwise wanted to do by hand. This paper presents examples from the work of upper level physics majors where Mathematica plays an active role in focusing and sustaining their thought around calculation. These students still engage in powerful mathematical reasoning while they calculate but struggle because of the narrowed breadth of their thinking. Their reasoning is drawn into local attractors where they look to calculation schemes to resolve questions instead of, for example, mapping the mathematics to the physical system at hand. We model the influence of Mathematica as an integral part of the constant feedback that occurs in how students frame, and hence focus, their work

    General practitioners' knowledge, attitudes and views of providing preconception care: a qualitative investigation

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    Background: Preconception health and care aims to reduce parental risk factors before pregnancy through health promotion and intervention. Little is known about the preconception interventions that general practitioners (GPs) provide. The aim of this study was to examine GPs’ knowledge, attitudes, and views towards preconception health and care in the general practice setting. Methods: As part of a large mixed-methods study to explore preconception care in England, we surveyed 1,173 women attending maternity units and GP services in London and interviewed women and health professionals. Seven GPs were interviewed, and the framework analysis method was used to analyse the data. Findings: Seven themes emerged from the data: Knowledge of preconception guidelines; Content of preconception advice; Who should deliver preconception care?; Targeting provision of preconception care; Preconception health for men; Barriers to providing preconception care; and Ways of improving preconception care. A lack of knowledge and demand for preconception care was found, and although reaching women before they are pregnant was seen as important it was not a responsibility that could be adequately met by GPs. Specialist preconception services were not provided within GP surgeries, and care was mainly targeted at women with medical conditions. GPs described diverse patient groups with very different health needs. Conclusion: Implementation of preconception policy and guidelines is required to engage women and men and to develop proactive delivery of care with the potential to improve pregnancy and neonatal outcomes. The role of education and of nurses in improving preconception health was acknowledged but remains under-developed

    How do women prepare for pregnancy? Preconception experiences of women attending antenatal services and views of health professionals

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    Copyright: © 2014 Stephenson et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Main objective - To determine the extent to which women plan and prepare for pregnancy. Methods - Cross-sectional questionnaire survey of pregnant women attending three maternity services in London about knowledge and uptake of preconception care; including a robust measure of pregnancy planning, and phone interviews with a range of health care professionals. Main results - We recruited 1173/1288 (90%) women, median age of 32 years. 73% had clearly planned their pregnancy, 24% were ambivalent and only 3% of pregnancies were unplanned. 51% of all women and 63% of those with a planned pregnancy took folic acid before pregnancy. 21% of all women reported smoking and 61% reported drinking alcohol in the 3 months before pregnancy; 48% of smokers and 41% of drinkers reduced or stopped before pregnancy. The 51% of all women who reported advice from a health professional before becoming pregnant were more likely to adopt healthier behaviours before pregnancy [adjusted odds ratios for greatest health professional input compared with none were 2.34 (95% confidence interval 1.54–3.54) for taking folic acid and 2.18 (95% CI 1.42–3.36) for adopting a healthier diet before pregnancy]. Interviews with 20 health professionals indicated low awareness of preconception health issues, missed opportunities and confusion about responsibility for delivery of preconception care. Significance of the findings - Despite a high level of pregnancy planning, awareness of preconception health among women and health professionals is low, and responsibility for providing preconception care is unclear. However, many women are motivated to adopt healthier behaviours in the preconception period, as indicated by halving of reported smoking rates in this study. The link between health professional input and healthy behaviour change before pregnancy is a new finding that should invigorate strategies to improve awareness and uptake of pre-pregnancy health care, and bring wider benefits for public health.Department of Healt

    Mapping interactions between the sustainable development goals: lessons learned and ways forward

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    Pursuing integrated research and decision-making to advance action on the sustainable development goals (SDGs) fundamentally depends on understanding interactions between the SDGs, both negative ones (“trade-offs”) and positive ones (“co-benefits”). This quest, triggered by the 2030 Agenda, has however pointed to a gap in current research and policy analysis regarding how to think systematically about interactions across the SDGs. This paper synthesizes experiences and insights from the application of a new conceptual framework for mapping and assessing SDG interactions using a defined typology and characterization approach. Drawing on results from a major international research study applied to the SDGs on health, energy and the ocean, it analyses how interactions depend on key factors such as geographical context, resource endowments, time horizon and governance. The paper discusses the future potential, barriers and opportunities for applying the approach in scientific research, in policy making and in bridging the two through a global SDG Interactions Knowledge Platform as a key mechanism for assembling, systematizing and aggregating knowledge on interactions

    Fourier transform for quantum DD-modules via the punctured torus mapping class group

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    We construct a certain cross product of two copies of the braided dual H~\tilde H of a quasitriangular Hopf algebra HH, which we call the elliptic double EHE_H, and which we use to construct representations of the punctured elliptic braid group extending the well-known representations of the planar braid group attached to HH. We show that the elliptic double is the universal source of such representations. We recover the representations of the punctured torus braid group obtained in arXiv:0805.2766, and hence construct a homomorphism to the Heisenberg double DHD_H, which is an isomorphism if HH is factorizable. The universal property of EHE_H endows it with an action by algebra automorphisms of the mapping class group SL2(Z)~\widetilde{SL_2(\mathbb{Z})} of the punctured torus. One such automorphism we call the quantum Fourier transform; we show that when H=Uq(g)H=U_q(\mathfrak{g}), the quantum Fourier transform degenerates to the classical Fourier transform on D(g)D(\mathfrak{g}) as q1q\to 1.Comment: 12 pages, 1 figure. Final version, to appear in Quantum Topolog

    Jet Streaks in the Gulf Stream

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    Mesoscale alongstream speed changes of the Gulf Stream are diagnosed from an array of current meters at depths 400, 700, and 1000 m, near 68°W, during the development of steep [ratio of “amplitude” to “wavelength” O(1)] meanders. Speed maxima (jet streaks) are generally found between trough and crest axes in steep meanders with local speed minima near the trough and crest axes. Speed changes along streamlines can be quite dramatic. Speed changes along the jet axis, between jet streaks and local minima in excess of 0.60, 0.40, and 0.35 m s−1, are observed at depth 400, 700, and 1000 m, respectively. This is in comparison with peak speeds in a frontal coordinates system mean of 1.22, 0.67, and 0.28 m s−1, at depth 400, 700, and 1000 m, respectively, from a previous study. The presence of the jet streaks can be explained kinematically as a superposition of the Gulf Stream and barotropic vortices. The development of these jet streaks in relation to the developing steep meanders differs from the canonical picture of jet streak/baroclinic wave development in the atmospheric jet stream in that the jet streaks in the Gulf Stream are predominantly fixed in place with respect to meanders as they steepen
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