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- 2018
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:1
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Research review (peer-reviewed)
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- Joffrin, E., et al.
(author)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Research review (peer-reviewed)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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- Bracegirdle, Chloe, et al.
(author)
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Neither Friend nor Foe : Ethnic Segregation in School Social Networks
- 2023
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In: Socius. - 2378-0231. ; 9
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Journal article (peer-reviewed)abstract
- High levels of ethnic segregation have been widely observed in school friendship networks, whereas the degree to which school bullying networks are divided along ethnic lines remains uncertain. Using data from 981 students (53% girls, 47% boys; 11–14 years of age) in British schools, we sought to visualize, quantify, and compare the degree of ethnic segregation in friendship and bullying networks. Our findings contradict the common belief that ethnic segregation in friendship networks fosters interethnic conflict; instead, we identified similarly high levels of ethnic segregation in both friendship and bullying networks. Students may therefore simultaneously avoid positive and negative interethnic relationships. The findings indicate that positive and negative networks should both be considered to provide a comprehensive assessment of interethnic relations in the school environment.
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- Breen, Richard, et al.
(author)
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How much scope for a mobility paradox? The relationship between social and income mobility in Sweden
- 2016
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In: Sociological Science. - : Society for Sociological Science. - 2330-6696. ; 3, s. 39-60
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Journal article (peer-reviewed)abstract
- It is often pointed out that conclusions about intergenerational (parent–child) mobility can differ depending on whether we base them on studies of class or income. We analyze empirically the degree of overlap in income and social mobility; we demonstrate mathematically the nature of their relationship; and we show, using simulations, how intergenerational income correlations relate to relative social mobility rates. Analyzing Swedish longitudinal register data on the incomes and occupations of over 300,000 parent–child pairs, we find that social mobility accounts for up to 49 percent of the observed intergenerational income correlations. This figure is somewhat greater for a fine-graded micro-class classification than a five-class schema and somewhat greater for women than men. There is a positive relationship between intergenerational social fluidity and income correlations, but it is relatively weak. Our empirical results, and our simulations verify that the overlap between income mobility and social mobility leaves ample room for the two indicators to move in different directions over time or show diverse patterns across countries. We explain the circumstances in which income and social mobility will change together or co-vary positively and the circumstances in which they will diverge.
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- Dollmann, Jörg, et al.
(author)
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Ethnic gaps in Swedish upper secondary school completion : Is 'immigrant optimism' the problem?
- 2021
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Reports (other academic/artistic)abstract
- In many Western countries, researchers have documented ‘immigrant optimism’ in education, i.e., the tendency for immigrant-background students to choose academically more demanding routes than others at given levels of grade point averages (GPA). For some, this indicates structural integration, while others alert against an ‘immigrant optimism trap’ when ambition trumps ability, leading to high risks of non-completion. Using longitudinal Swedish population data (n≈90,000), we estimate the upper secondary ‘completion gap’ to 12% to the detriment of immigrant-background students. We then address the ‘trap hypothesis’ via two counterfactual analyses. The first shows that if immigrant-background youth made similar educational choices as other students at the same GPA, the completion gap would shrink by 3.4 percentage points. The second analysis suggests that restricting admission to programmes based on prior GPA, which would lead to a massive relocation of low- and mid-GPA students to vocational programmes, would reduce the completion gap by 2.2 percentage points. These changes must be considered marginal in view of the substantial restrictions of choice that either of these measures would entail. We conclude that completion gaps are not primarily a result of immigrant optimism, and optimistic choices are likely to be a net positive for structural integration.
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