Temperature minimum heating in solar flares by resistive dissipation of Alfven waves

The possibility that the strong heating produced at temperature-minimum levels during solar flares is due to resistive dissipation of Alfven waves generated by the primary energy release process in the corona is studied. It is shown how, for suitable parameters, these waves can carry their energy essentially undamped into the temperature-minimum layers and can then produce a degree of heating consistent with observations

Analysis of Gamma Radiation from a Radon Source: Indications of a Solar Influence

This article presents an analysis of about 29,000 measurements of gamma radiation associated with the decay of radon in a sealed container at the Geological Survey of Israel (GSI) Laboratory in Jerusalem between 28 January 2007 and 10 May 2010. These measurements exhibit strong variations in time of year and time of day, which may be due in part to environmental influences. However, time-series analysis reveals a number of periodicities, including two at approximately 11.2 year$^{-1}$ and 12.5 year$^{-1}$. We have previously found these oscillations in nuclear-decay data acquired at the Brookhaven National Laboratory (BNL) and at the Physikalisch-Technische Bundesanstalt (PTB), and we have suggested that these oscillations are attributable to some form of solar radiation that has its origin in the deep solar interior. A curious property of the GSI data is that the annual oscillation is much stronger in daytime data than in nighttime data, but the opposite is true for all other oscillations. This may be a systematic effect but, if it is not, this property should help narrow the theoretical options for the mechanism responsible for decay-rate variability.Comment: 9 pages, 21 figure

Doctors who pilot the GMC's Tests of Competence: who volunteers and why?

Background: Doctors who are investigated by the General Medical Council (GMC) for performance concerns may be required to take a Test of Competence (ToC). The tests are piloted on volunteer doctors before they are used in Fitness to Practise (FtP) investigations. Objectives: To find out who volunteers to take a pilot ToC and why. Methods: This was a retrospective cohort study. Between February 2011 and October 2012 we asked doctors who volunteered for a test to complete a questionnaire about their reasons for volunteering and recruitment. We analysed the data using descriptive statistics and Pearson’s chi-square test. Results: 301 doctors completed the questionnaire. Doctors who took a ToC voluntarily were mostly women, of white ethnicity, of junior grades, working in general practice and who held a Primary Medical Qualification from the UK. This was a different population to doctors under investigation and all registered doctors in the UK. Most volunteers heard about the GMC’s pilot events through email from a colleague and used the experience to gain exam practice for forthcoming postgraduate exams. Conclusions: The reference group of volunteers are not representative of doctors under FtP investigation. Our findings will be used to inform future recruitment strategies with the aim to encourage better matching of groups who voluntarily pilot a ToC with those under FtP investigation

Longitude distribution of solar flares

Longitude distribution of solar flare

Twelve tips for conducting a virtual OSCE

Recently many medical schools have faced the challenge of redesigning their existing assessments to run in a virtual format. We ran a virtual Objective Structured Clinical Examination (OSCE) for a group of final year students assessing clinical communication skills, written communication, practical skills, examination skills and professionalism. OSCEs provide the opportunity to test skills that written papers cannot, so it was important to include such a clinical exam in the portfolio of assessments for graduating students. The virtual OSCE ran smoothly and was successful at discriminating between candidates. In this article, we share twelve practical tips from our experience and the small body of literature on how to successfully design and deliver a virtual OSCE. This format provides an opportunity to run similar assessments in the future if remote assessments or assessments of telemedicine skills are required

Cosmic ray diffusion fronts in the Virgo cluster

The pair of large radio lobes in the Virgo cluster, each about 23 kpc in radius, have curiously sharp outer edges where the radio-synchrotron continuum flux declines abruptly. However, just adjacent to this sharp transition, the radio flux increases. This radio limb-brightening is observed over at least half of the perimeter of both lobes. We describe slowly propagating steady state diffusion fronts that explain these counterintuitive features. Because of the natural buoyancy of radio lobes, the magnetic field is largely tangent to the lobe boundary, an alignment that polarizes the radio emission and dramatically reduces the diffusion coefficient of relativistic electrons. As cosmic ray electrons diffuse slowly into the cluster gas, the local magnetic field and gas density are reduced as gas flows back toward the radio lobe. Radio emission peaks can occur because the synchrotron emissivity increases with magnetic field and then decreases with the density of non-thermal electrons. A detailed comparison of steady diffusion fronts with quantitative radio observations may reveal information about the spatial variation of magnetic fields and the diffusion coefficient of relativistic electrons. On larger scales, some reduction of the gas density inside the Virgo lobes due to cosmic ray pressure must occur and may be measurable. Such X-ray observations could reveal important information about the presence of otherwise unobservable non-thermal components such as relativistic electrons of low energy or proton cosmic rays.Comment: 11 pages, 5 figures, Accepted by Ap