2,860 research outputs found
An Estimate of Changes in the Sun's Total Irradiance Caused by UV Irradiance Variations from 1874 to 1988
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
Solar Cycle Modulation of Total Irradiance: an Empirical Model from 1874 to 1988
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
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
10-30% of the global surface temperature warming over the period
1980-2002
Fasciculochloris, a new Chlorosphaeracean alga from a Connecticut soil
Chlorosphaeracean algae from Connecticut soi
An analog computer study of the effectiveness of interceptor commands derived from a prediction equation of second order
Analog computer study of effectiveness of interceptor commands derived from prediction equation of second orde
Enhancing the Impact of Online Simulations through Blended Learning: a Critical Incident Approach
Version of record is available at the Emerald publishing platform: http://dx.doi.org/10.1108/ET-01-2013-0007 publicationstatus: publishedPurpose – The purpose of this paper is to describe an approach for utilising a critical incident method within the context of an online business simulation game in order to provide an effective framework for reflective learning. Design/methodology/approach – The paper presents a review of pertinent literature to place the critical incident technique within the novel context of simulation gaming. Through presenting a case study of practice, it goes on to describe a blended learning approach that combines online simulation with post-simulation reflection based on the critical incident method. An action research approach is adopted as a framework for reflection on practice. Findings – From a conceptual perspective, there are a number of potential benefits to employing a critical incident approach combined with simulation gaming. The ability of educators to compress time frames and manage the introduction of critical incidents allows students to learn in a way that would not be possible in the real world. Furthermore, carefully designed post-simulation debriefing, structured around a critical incident framework, has the potential to enhance the learning impact of online simulation. Research limitations/implications – The research is limited in that a single case study context is described. Further evaluation research is required to fully assess the benefits of the approach adopted. Originality/value – The study explores the use of the critical incident approach within the novel context of online simulation gaming. It provides educators with a blended learning method that can be employed to enhance the impact of e-learning through structured reflection
The Role of Organisational Culture in the Merger of English Local Authorities into a Single Unitary Authority
This is an Accepted Manuscript of an article published by Taylor & Francis in Local Government Studies on 18/07/2013, available online: http://wwww.tandfonline.com/10.1080/03003930.2013.787413 publicationstatus: publishedCornwall Council is a new ‘unitary’ local authority which was created following the merger of six district councils and one county council on 1 April 2009. A questionnaire survey based on specific ‘dimensions’ of organisational culture was circulated to staff prior to the merger date. Overall, the results indicated a generally congruent culture characterised by a strong team spirit and commitment to the workplace. A number of differences were observed between the cultural orientations of the seven councils, but there was only weak evidence of differences between tiers of management or professional groupings. The study suggests that the new organisation will have to find ways of ‘unfreezing’ staff from their established ways of thinking and working before changes can be properly embedded. It is recommended that the organisational change process shifts from a top-down ‘planned’ approach to a more ‘emergent’ approach to facilitate learning and organisational development
Low-level seaweed supplementation improves iodine status in iodine-insufficient women
Iodine insufficiency is now a prominent issue in the UK and other European countries due to low intakes of dairy products and seafood (especially where iodine fortification is not in place). In the present study, we tested a commercially available encapsulated edible seaweed (Napiers Hebridean Seagreens® Ascophyllum nodosumspecies) for its acceptability to consumers and iodine bioavailability and investigated the impact of a 2-week daily seaweed supplementation on iodine concentrations and thyroid function. Healthy non-pregnant women of childbearing age, self-reporting low dairy product and seafood consumption, with no history of thyroid or gastrointestinal disease were recruited. Seaweed iodine (712 μg, in 1 g seaweed) was modestly bioavailable at 33 (interquartile range (IQR) 28–46) % of the ingested iodine dose compared with 59 (IQR 46–74) % of iodine from the KI supplement (n 22). After supplement ingestion (2 weeks, 0•5 g seaweed daily, <i>n</i> 42), urinary iodine excretion increased from 78 (IQR 39–114) to 140 (IQR 103–195) μg/l (<i>P</i>< 0•001). The concentrations of thyroid-stimulating hormone increased from 1•5 (IQR 1•2–2•2) to 2•1 (IQR 1•3–2•9) mIU/l (<i>P</i>< 0•001), with two participants having concentrations exceeding the normal range after supplement ingestion (but normal free thyroxine concentrations). There was no change in the concentrations of other thyroid hormones after supplement ingestion. The seaweed was palatable and acceptable to consumers as a whole food or as a food ingredient and effective as a source of iodine in an iodine-insufficient population. In conclusion, seaweed inclusion in staple foods would serve as an alternative to fortification of salt or other foods with KI
Attention and regional gray matter development in very preterm children at age 12 years
Objectives: This study examines the selective, sustained, and executive attention abilities of very preterm (VPT) born children in relation to concurrent structural magnetic resonance imaging (MRI) measures of regional gray matter development at age 12 years. Methods: A regional cohort of 110 VPT (≤32 weeks gestation) and 113 full term (FT) born children were assessed at corrected age 12 years on the Test of Everyday Attention-Children. They also had a structural MRI scan that was subsequently analyzed using voxel-based morphometry to quantify regional between-group differences in cerebral gray matter development, which were then related to attention measures using multivariate methods. Results: VPT children obtained similar selective (p=.85), but poorer sustained (p=.02) and executive attention (p=.01) scores than FT children. VPT children were also characterized by reduced gray matter in the bilateral parietal, temporal, prefrontal and posterior cingulate cortices, bilateral thalami, and left hippocampus; and increased gray matter in the occipital and anterior cingulate cortices (family-wise error-corrected
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