11,671 research outputs found

    An Estimate of Changes in the Sun's Total Irradiance Caused by UV Irradiance Variations from 1874 to 1988

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    Enhanced emission from bright solar faculae is a source of significant variation in the sun's total irradiance. Relative to the emission from the quiet sun, facular emission is known to be considerably greater at UV wavelengths than at visible wavelengths. Determining the spectral dependence of facular emission is of interest for the physical insight this may provide to the origin of the sun's irradiance variations. It is also of interest because solar radiation at lambda less than 300 nm is almost totally absorbed in the Earth's atmosphere. Depending on the magnitude of the UV irradiance variations, changes in the sun's irradiance that penetrates to the Earth's surface may not be equivalent to total irradiance variations measured above the Earth's atmosphere. Using an empirical model of total irradiance variations which accounts separately for changes caused by bright faculae from those associated with dark sunspots, the contribution of UV irradiance variations to changes in the sun's total irradiance is estimated during solar cycles 12 to 21

    VLED and formula LED in the management of type 2 diabetes: defining the clinical need and research requirements

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    It has been known for many years that substantial weight loss, achieved by bariatric surgery or non-surgical means can mean normalise glucose tolerance. Recent RCT evidence indicates that >15 kg weight loss is necessary, to this and it may lead to near normalisation (doubling) of life expectancy. Less than 5% of patients achieve this through even the best, evidence-based medical weight management programme (Counterweight www.counterweight.org ). A weight loss of >15 kg is easily achievable by 8 weeks VLED/LELD in compliant patients, with little difference between 400-800 kcal/day, but weight maintenance after VLED has until recently been so poor that VLEDs are not, at present, recommended in clinical guidelines. However, mean weight loss close to >15 kg can be maintained 18-24 months using a variety of maintenance strategies. These include a structured reintroduction of foods linked to an education programme with behavioural strategies, intermittent VLED use and prescribable anti-obesity drugs (dexfenfluramine, orlistat, sibutramine). Most of these studies have been in non-diabetic subjects. A new “curative” paradigm in T2DM management, aiming to normalise glucose tolerance and health risks by achieving and maintaining >15 kg loss, as soon as possible after diagnosis, should be highly acceptable to patients, generating many additional QALYs. It is likely to be highly cost-effective by avoiding the current recommended, mainly palliative, model, using polypharmacy which provides an overall risk reduction of only 5-10%.. Clinical trials are on-going to establish the feasibility of delivering formula (LELD) and a maintenance programme to large numbers of patients within routine primary care. There is urgent need, to run similar studies in diabetic patients. New approaches to long-term (lifelong) maintenance of weight loss and a non-diabetic state may include anti-obesity drugs

    Dirac groupoids and Dirac bialgebroids

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    We describe infinitesimally Dirac groupoids via geometric objects that we call Dirac bialgebroids. In the two well-understood special cases of Poisson and presymplectic groupoids, the Dirac bialgebroids are equivalent to the Lie bialgebroids and IM-22-forms, respectively. In the case of multiplicative involutive distributions on Lie groupoids, we find new properties of infinitesimal ideal systems.Comment: New expanded version; the construction of the Manin pair associated to an LA-Dirac structure has moved from arXiv:1209.6077 to here. Added background on double vector bundles, VB-algebroids and 2-term representations up to homotop

    The Geometrisation of N\mathbb N-manifolds of degree 2

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    This paper describes an equivalence of the canonical category of N\mathbb N-manifolds of degree 22 with a category of involutive double vector bundles. More precisely, we show how involutive double vector bundles are in duality with double vector bundles endowed with a linear metric. We describe then how special sections of the metric double vector bundle that is dual to a given involutive double vector bundle are the generators of a graded manifold of degree 22 over the double base. We discuss how split Poisson N\mathbb N-manifolds of degree 22 are equivalent to \emph{self-dual representations up to homotopy} and so, following Gracia-Saz and Mehta, to linear splittings of a certain class of VB-algebroids. In other words, the equivalence of categories above induces an equivalence between so called \emph{Poisson involutive double vector bundles}, which are the dual objects to metric VB-algebroids, and Poisson N\mathbb N-manifolds of degree 22.Comment: This is the improved and completed first part of the paper arXiv:1504.00880 (N-manifolds of degree 2 and metric double vector bundles). The improved second and third parts will be uploaded here in due time. v2: inconsistencies fixed in Example 3.18, as well as some typos. v3: Section 3.4.2 had a faulty formula that is now fixe

    Flight techniques for the measurement of stability derivatives and aircraft response

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    A method of obtaining aircraft frequency-response from transient response data by Fourier analysis is currently being investigated. This report describes progress that has been made between the commencement of the contract (1st December, 1964) and the time of writing (October, 1965). The dynamic response characteristics of a Hawker Siddeley Dore' aircraft are being determined from flight measurements using the Fourier method of analysis. At present attention is centred on the longitudinal response as the short-period mode of the aircraft is well damped and should be defined by a simple transfer function. The aircraft transient responses to various pilot-applied control inputs are recorded and the Fourier analysis of these transients is being carried out on a Ferranti Pegasus digital computer. Three development flights have been completed to date, and some preliminary results have been obtained, although the detailed analysis of the flight data is awaiting the incorporation of the instrumentation calibration into the computer programme. This last procedure will speed up the analysis of future data

    Ecological Hierarchy and Biodiversity

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    Solar Cycle Modulation of Total Irradiance: an Empirical Model from 1874 to 1988

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    Evidence acquired during the past decade indicates that over time scales of the solar cycle, enhanced emission from bright solar faculae cause significant variations in the sun's total irradiance even though, on shorter time scales, the most pronounced variations are those resulting from the passage of dark sunspots across the solar disc. An empirical model which accounts for the competing effects of dark sunspots and bright faculae has been developed from the available radiometry in cycle 21, and extended back to the beginning of solar cycle 12. According to this model, the largest 11-year modulation of total irradiance during the C20th occurred in the most recent cycle 21

    Estimate solar contribution to the global surface warming using the ACRIM TSI satellite composite

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    We study, by using a wavelet decomposition methodology, the solar signature on global surface temperature data using the ACRIM total solar irradiance satellite composite by Willson and Mordvinov. These data present a +0.047%/decade trend between minima during solar cycles 21-23 (1980-2002). We estimate that the ACRIM upward trend might have minimally contributed \sim10-30% of the global surface temperature warming over the period 1980-2002

    Contemporary challenges to iodine status and nutrition: the role of foods, dietary recommendations, fortification and supplementation

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    Iodine deficiency (ID) in women of childbearing age remains a global public health concern, mainly through its impact on fetal and infant neurodevelopment. While iodine status is improving globally, ID is still prevalent in pregnancy, when requirements increase. More than 120 countries have implemented salt iodisation and food fortification, strategies that have been partially successful. Supplementation during pregnancy is recommended in some countries and supported by the WHO when mandatory salt iodisation is not present. The UK is listed as one of the ten countries with the lowest iodine status globally, with approximately 60 % of pregnant women not meeting the WHO recommended intake. Without mandatory iodine fortification or recommendation for supplementation in pregnancy, the UK population depends on dietary sources of iodine. Both women and healthcare professionals have low knowledge and awareness of iodine, its sources or its role for health. Dairy and seafood products are the richest sources of iodine and their consumption is essential to support adequate iodine status. Increasing iodine through the diet might be possible if iodine-rich foods get repositioned in the diet, as they now contribute towards only about 13 % of the average energy intake of adult women. This review examines the use of iodine-rich foods in parallel with other public health strategies, to increase iodine intake and highlights the rare opportunity in the UK for randomised trials, due to the lack of mandatory fortification programmes
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