Phenomena in the Solar Corona: characteristic structure and dynamic evolution

This thesis presents a study of multiple phenomena that exist within the solar corona. The structures explored in this work cover a range of sizes from a small-scale X-ray bright point (100 Mm). Observational data and numerical simulations were utilised in order to investigate the structure and evolution of each type of feature. A small-scale X-ray bright point (XBP) was investigated using complete Hinode observations in order to examine it over its entire lifetime (∼12 hours). The XBP was found to be formed directly above an area of cancelling magnetic flux on the photosphere. A good correlation between the rate of X-ray emission and decrease in total magnetic flux was found. The magnetic fragments of the XBP were found to vary on very short timescales (minutes), however the global quasi-bipolar structure remained throughout the lifetime of the XBP. Electron density measurements were obtained using a line ratio of Fe XII and the average density was found to be 5±1x109 cm−3 with the volumetric plasma filling factor calculated to have an average value of 0.04±15%. Emission measure loci plots were then used to infer a steady temperature of log Te [K] ∼ 6.1±0.1. The calculated Fe XII Doppler shifts show velocity changes in and around the bright point of ±15 kms−1 which are observed to change on a timescale of less than 30 minutes. The results indicate that higher cadence spectroscopic measurements are required if the velocity flows are to be related to corresponding changes in the magnetic field. The next feature investigated was a 100 Mm multistranded coronal loop that was simulated in order to investigate how changing the various model parameters would affect the resulting differential emission measure DEM distributions and intensity values. Once the model was fully understood, it was used to test a DEM solver and quantify the ‘goodness-of-fit’ that could be achieved. This allowed the imitations of the DEM method to be understood. As the model parameter space was altered, a number of changes in the resulting synthetic DEMs were observed. In most cases these changes were subtle and could be explained by the changing physics of the system. The cooling simulation showed the most unique changes where the total energy of the system could be identified by examining the evolution of the intensity values and DEM shape. The iterative solver solution XRT DEM iterative2 did an excellent job of reconstructing the original model intensity values and DEM distributions in the majority of cases. The only instance where the solver did not do well was when the synthetic DEM was very narrow i.e., only covering a few temperature bins. This highlights the under-constrained problem of using DEM solvers and shows that this particular solver works best when the original DEM being reconstructed is smoother and more multithermal. Finally, a large-scale prominence eruption was investigated using observations from two points of view. The structure and evolution of the prominence material and cavity were examined over the eruption process. Many possible initiation methods were investigated to see if the cause of the prominence eruption could be pinned down. It was found that the polar-crown cavity could be defined as a density depletion sitting above denser polar-crown filament plasma which has drained down from the cavity due to gravity. The eruption of the polar crown cavity as a solid body can be decomposed into two phases: a slow rise at a speed of 2 ±0.2 km s−1 , and an acceleration phase at a mean speed of 15–25 ±0.6 km s−1 . The initiation of the prominence was concluded to be caused by a combination of mass un-loading and a type of kink instability

The State of Sustainable Research Software: Results from the Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE5.1)

This article summarizes motivations, organization, and activities of the Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE5.1) held in Manchester, UK in September 2017. The WSSSPE series promotes sustainable research software by positively impacting principles and best practices, careers, learning, and credit. This article discusses the Code of Conduct, idea papers, position papers, experience papers, demos, and lightning talks presented during the workshop. The main part of the article discusses the speed-blogging groups that formed during the meeting, along with the outputs of those sessions

The diagnostic performance of routinely acquired and reported computed tomography imaging in patients presenting with suspected pleural malignancy

Objectives: Contrast-enhanced computed tomography (CT) provides essential cross-sectional imaging data in patients with suspected pleural malignancy (PM). The performance of CT in routine practice may be lower than in previously reported research. We assessed this relative to ‘real-life’ factors including use of early arterial-phase contrast enhancement (by CT pulmonary angiography (CTPA)) and non-specialist radiology reporting. Materials and methods: Routinely acquired and reported CT scans in patients recruited to the DIAPHRAGM study (a prospective, multi-centre observational study of mesothelioma biomarkers) between January 2014 and April 2016 were retrospectively reviewed. CT reports were classified as malignant if they included specific terms e.g. “suspicious of malignancy”, “stage M1a” and benign if others were used e.g. “indeterminate”, “no cause identified”. All patients followed a standard diagnostic algorithm. The diagnostic performance of CT (overall and based on the above factors) was assessed using 2 × 2 Contingency Tables. Results: 30/345 (9%) eligible patients were excluded (non-contrast (n = 13) or non-contiguous CT (n = 4), incomplete follow-up (n = 13)). 195/315 (62%) patients studied had PM; 90% were cyto-histologically confirmed. 172/315 (55%) presented as an acute admission, of whom 31/172 (18%) had CTPA. Overall, CT sensitivity was 58% (95% CI 51–65%); specificity was 80% (95% CI 72–87%). Sensitivity of CTPA (performed in 31/315 (10%)) was lower (27% (95% CI 9–53%)) than venous-phase CT (61% (95% CI 53–68%) p = 0.0056). Sensitivity of specialist thoracic radiologist reporting was higher (68% (95% CI 55–79%)) than non-specialist reporting (53% (95% CI 44–62%) p = 0.0488). Specificity was not significantly different. Conclusion: The diagnostic performance of CT in routine clinical practice is insufficient to exclude or confirm PM. A benign CT report should not dissuade pleural sampling where the presence of primary or secondary pleural malignancy would alter management. Sensitivity is lower with non-thoracic radiology reporting and particularly low using CTPA

Design of an Online Optimisation Tool for Smart Home Heating Control

The performance of model predictive smart home heating control (SHHC) heavily depends on the accuracy of the initial setup for individual building characteristics. Since owners or renters of residential buildings are predominantly not experts, users’ acceptance of SHHC requires ease of use in the setup and minimal user intervention (e.g. only declaration of preferences), but at the same time high reliability of the initial parameter settings and flexibility to handle different preferences. In contrast, the training time of self-learning SHHC (e.g. based on artificial neural networks) to reach a reliable control status could conflict with the users’ request for comfortable heating from the very beginning. Dealing with this trade-off, this paper follows the tradition of design science research and presents a prototype of an online optimisation tool (OOT) for SHHC. The OOT is multi objective (e.g. minimising lifecycle energy (cost) or carbon emissions) under constraints such as thermal comfort. While the OOT is based on a discrete dynamic model, its self-adaptation is accelerated by a database of physically simulated characteristic buildings, which allows parameter setting at the beginning by a similarity measurement. The OOT artefact provides a base for empirically testing advantages of different SHHC design alternatives

EU must stand up for jailed Iranian scholar Ahmadreza Djalali. Egmont Commentary 1 December 2020.

A Swedish citizen faces capital punishment without a fair trial. The EU cannot afford to stay silent. In a faraway prison, an Iranian-Swedish scientist awaits execution. Ahmadreza Djalali, a specialist in disaster medicine sentenced to death for allegedly collaborating with Israeli intelligence, was told last week that his execution is imminent. Faced with this grim development, Sweden and Belgium, as well as the NGO Amnesty International, have deployed all possible means to halt his execution. If the European Union is serious about defending the rule of law and the rights of its citizens, it needs to come out strongly in defense of Djalali too. It cannot allow Djalali, like other dual citizens before him, to be reduced to mere pawns in a game of geopolitical chess