22,666 research outputs found

    The Policy and Regulatory Environment for Organic Farming in Europe

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    Organic Farming is one of the key issues in reshaping European agricultural policy. This book clarifies the policy and regulatory environment within which organic farming currently operates in all EU-15 member states and in three non-EU countries (Norway, Switzerland and the Czech Republic). European and national regulations and their implementation are reviewed. Focus is led on agri-environmental and mainstream agricultural support measures, marketing and regional development programmes, certification systems and organic farming support in the form of advice, training and research. The book aims at policy makers, the private sector, researchers and students in the field of economics and politics of organic farming

    Network growth models and genetic regulatory networks

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    We study a class of growth algorithms for directed graphs that are candidate models for the evolution of genetic regulatory networks. The algorithms involve partial duplication of nodes and their links, together with innovation of new links, allowing for the possibility that input and output links from a newly created node may have different probabilities of survival. We find some counterintuitive trends as parameters are varied, including the broadening of indegree distribution when the probability for retaining input links is decreased. We also find that both the scaling of transcription factors with genome size and the measured degree distributions for genes in yeast can be reproduced by the growth algorithm if and only if a special seed is used to initiate the process.Comment: 8 pages with 7 eps figures; uses revtex4. Added references, cleaner figure

    Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

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    Abstract On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (\u3e2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased \u3e90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Key Points Substorm dynamics are important for highly relativistic electron energization Cold plasma preconditioning is significant for rapid relativistic energization Relativistic / highly relativistic electron energization can occur in \u3c 5 hrs

    Systematic derivation of a surface polarization model for planar perovskite solar cells

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    Increasing evidence suggests that the presence of mobile ions in perovskite solar cells can cause a current-voltage curve hysteresis. Steady state and transient current-voltage characteristics of a planar metal halide CH3_3NH3_3PbI3_3 perovskite solar cell are analysed with a drift-diffusion model that accounts for both charge transport and ion vacancy motion. The high ion vacancy density within the perovskite layer gives rise to narrow Debye layers (typical width ∼\sim2nm), adjacent to the interfaces with the transport layers, over which large drops in the electric potential occur and in which significant charge is stored. Large disparities between (I) the width of the Debye layers and that of the perovskite layer (∼\sim600nm) and (II) the ion vacancy density and the charge carrier densities motivate an asymptotic approach to solving the model, while the stiffness of the equations renders standard solution methods unreliable. We derive a simplified surface polarisation model in which the slow ion dynamic are replaced by interfacial (nonlinear) capacitances at the perovskite interfaces. Favourable comparison is made between the results of the asymptotic approach and numerical solutions for a realistic cell over a wide range of operating conditions of practical interest.Comment: 32 pages, 7 figure

    The Policy and Regulatory Environment for Organic Farming in Europe: Country Reports

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    This Volume (2) documents in detail the policies and regulations to organic farming for all 15 EU member states and for three non-EU countries (Norway, Switzerland and the Czech Republic). European and national regulations and their implementation are reviewed covering agri-environmental and mainstream agricultural support measures, marketing and regional development programmes, certification system and oranic farming support in the form of advice, training and research. Volume (1) provides a comparative analysis of the policy and regulatory environment within which organic farming currently operates in these countries. The book aims at policy makers, the private sector, researchers and students in the field of economics and politics of organic farming

    Development of food photographs for use with children aged 18 months to 16 years:comparison against weighed food diaries – The Young Person’s Food Atlas (UK)

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    Traditional dietary assessment methods, used in the UK, such as weighed food diaries impose a large participant burden, often resulting in difficulty recruiting representative samples and underreporting of energy intakes. One approach to reducing the burden placed on the participant is to use portion size assessment tools to obtain an estimate of the amount of food consumed, removing the need to weigh all foods. An age range specific food atlas was developed for use in assessing children’s dietary intakes. The foods selected and portion sizes depicted were derived from intakes recorded during the UK National Diet and Nutrition Surveys of children aged 1.5 to 16 years. Estimates of food portion sizes using the food atlas were compared against 4-day weighed intakes along with in-school / nursery observations, by the research team. Interviews were conducted with parents the day after completion of the diary, and for children aged 4 to 16 years, also with the child. Mean estimates of portion size consumed were within 7% of the weight of food recorded in the weighed food diary. The limits of agreement were wide indicating high variability of estimates at the individual level but the precision increased with increasing age. For children 11 years and over, agreement with weighed food diaries, was as good as that of their parents in terms of total weight of food consumed and of intake of energy and key nutrients. The age appropriate food photographs offer an alternative to weighed intakes for dietary assessment with children

    Drugs for neglected diseases: a failure of the market and a public health failure?

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    Infectious diseases cause the suffering of hundreds of millions of people, especially in tropical and subtropical areas. Effective, affordable and easy-to-use medicines to fight these diseases are nearly absent. Although science and technology are sufficiently advanced to provide the necessary medicines, very few new drugs are being developed. However, drug discovery is not the major bottleneck. Today's R&D-based pharmaceutical industry is reluctant to invest in the development of drugs to treat the major diseases of the poor, because return on investment cannot be guaranteed. With national and international politics supporting a free market-based world order, financial opportunities rather than global health needs guide the direction of new drug development. Can we accept that the dearth of effective drugs for diseases that mainly affect the poor is simply the sad but inevitable consequence of a global market economy? Or is it a massive public health failure, and a failure to direct economic development for the benefit of society? An urgent reorientation of priorities in drug development and health policy is needed. The pharmaceutical industry must contribute to this effort, but national and international policies need to direct the global economy to address the true health needs of society. This requires political will, a strong commitment to prioritize health considerations over economic interests, and the enforcement of regulations and other mechanisms to stimulate essential drug development. New and creative strategies involving both the public and the private sector are needed to ensure that affordable medicines for today's neglected diseases are developed. Priority action areas include advocating an essential medicines R&D agenda, capacity-building in and technology transfer to developing countries, elaborating an adapted legal and regulatory framework, prioritizing funding for essential drug development and securing availability, accessibility, distribution and rational use of these drugs

    X-Ray Imaging for the Observation of Mode I Fracture in Fibre Reinforced Concrete

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    In this study X-ray imaging is used to investigate the mechanisms of fracture in fibre reinforced concrete. The investigation looks at the performance of discrete end-hooked fibres crossing a cracking plane at various angles and loaded normal to the plane. The angle of a fibre crossing a crack is found to be an important parameter in determining the mode of failure and bending of the fibres were observed up to approximately 5 mm into the matrix from the fibre exit point. The tests show a probability that some fibres pullout from longer embedded side under Mode I fracture. In the non-destructive observation procedure presented here, the internal actions of the fibres at the various stages of loading can be determined. X-Ray imaging is shown to be a valuable tool in understanding steel fibre-concrete behaviour
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