2D continuous spectrum of shear Alfven waves in the presence of a magnetic island

The radial structure of the continuous spectrum of shear Alfven modes is calculated in the presence of a magnetic island in tokamak plasmas. Modes with the same helicity of the magnetic island are considered in a slab model approximation. In this framework, with an appropriate rotation of the coordinates the problem reduces to 2 dimensions. Geometrical effects due to the shape of the flux surface's cross section are retained to all orders. On the other hand, we keep only curvature effects responsible of the beta induced gap in the low-frequency part of the continuous spectrum. New continuum accumulation points are found at the O-point of the magnetic island. The beta-induced Alfven Eigenmodes (BAE) continuum accumulation point is found to be positioned at the separatrix flux surface. The most remarkable result is the nonlinear modification of the BAE continuum accumulation point frequency

Use of NHS Digital datasets as trial data in the UK: a position paper

Background: Clinical trial teams increasingly want to make use of data from healthcare systems (“healthcare data”), particularly to enhance recruitment and follow-up of participants, to reduce time and cost, and to stop the duplication of effort. However, there is continued uncertainty of how regulators regard healthcare data used for trial purposes, in terms of provenance, quality and reliability. Objectives: There were two key objectives: First, to demonstrate the data integrity of two datasets held by NHS Digital (NHSD) that are most requested by trial teams; and second, to set out an approach by which any other healthcare systems datasets can be similarly evaluated. Method: The data lifecycles of the datasets were carefully documented, mapping the flow of data from the originating healthcare provider’s databases to NHSD warehouses and onwards to clinical trials teams. These were assessed for evidence of whether the datasets are accurate, reliable, complete, contemporaneous, and well-governed. Result: The assessment method was applied to (a) the Hospital Episode Statistics Admitted Patient Care (HES APC) dataset and (b) the Civil Registration of Deaths (CRD) dataset. This paper clearly demonstrates that their collection and management through NHSD systems ensure their integrity and reliability. The datasets are accurate representations of the data held by the originating providers (acute NHS trusts and local registrars). Conclusion: Based on these findings, the HES APC and CRD datasets satisfy the assessment criteria that demonstrate they are reliable transcribed copies of the original source data. Implications: First, these datasets can be used directly for clinical trial data, with trial teams focusing on the accuracy of algorithms and processes to identify particular outcomes rather than on the integrity of the data flow. Second, this assessment approach should be used to assess whether other healthcare systems datasets are ready to be used as transcribed copies of source data, and for data providers to take appropriate steps to redress this matter if they are not

Diasporic Dreams, Middle Class Moralities and Migrant Domestic Workers among Muslim Filipinos in Saudi Arabia

This paper is about middle-class Muslim Filipinos in Saudi Arabia and their discourses about and relationships with migrant domestic workers. Saudi Arabia is not simply a temporary stopping point to a better future elsewhere, but is also a place where the middle-class aspirations of Muslim Filipinos may be realised and where their religious affiliations as Muslims may be seen as enhancing rather than detracting from those dreams and imaginings. As part of a large and diverse diasporic community, middle-class Filipinos routinely interact and socialise with working-class Filipinos. They often provide succour and support for their compatriots who labour under difficult and legally unprotected conditions. Some employ migrant domestic workers in their homes, many of whom are irregular or takas (escapees). At the same time, they reproduce and reinforce many of the gendered stereotypes of domestic workers that often suggest moral failings of one sort or another. The simultaneous embracing of and distancing from domestic workers reflects the anxieties of those, particularly women, whose tenuous hold of middle-class status is accomplished through, but also put at risk by, the precariousness of their sojourns abroad in the Kingdom

Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario

The linear stability of Alfvén eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach based on CASTOR-K (Borba and Kerner 1999 J. Comput. Phys. 153 101; Nabais et al 2015 Plasma Sci. Technol. 17 89) is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfvén eigenmodes. The largest growth-rates occur in the scenario variant with higher core temperatures, which has the highest alpha-particle density and density gradient, for eigenmodes with toroidal mode numbers . Although these eigenmodes suffer significant radiative damping, which is also evaluated, their growth rates remain larger than those of the most unstable eigenmodes found in the variant of the ITER baseline scenario with lower core temperatures, which have and are not affected by radiative damping

Sensitivity of alpha-particle-driven Alfvén eigenmodes to q-profile variation in ITER scenarios

A perturbative hybrid ideal-MHD/drift-kinetic approach to assess the stability of alpha-particle-driven Alfv�n eigenmodes in burning plasmas is used to show that certain foreseen ITER scenarios, namely the MA baseline scenario with very low and broad core magnetic shear, are sensitive to small changes in the background magnetic equilibrium. Slight variations (of the order of ) of the safety-factor value on axis are seen to cause large changes in the growth rate, toroidal mode number, and radial location of the most unstable eigenmodes found. The observed sensitivity is shown to proceed from the very low magnetic shear values attained throughout the plasma core, raising issues about reliable predictions of alpha-particle transport in burning plasmas