Propagating waves in polar coronal holes as seen by SUMER and EIS

To study the dynamics of coronal holes and the role of waves in the acceleration of the solar wind, spectral observations were performed over polar coronal hole regions with the SUMER spectrometer on SoHO and the EIS spectrometer on Hinode. Using these observations, we aim to detect the presence of propagating waves in the corona and to study their properties. The observations analysed here consist of SUMER spectra of the Ne VIII 770 A line (T = 0.6 MK) and EIS slot images in the Fe XII 195 A line (T = 1.3 MK). Using the wavelet technique, we study line radiance oscillations at different heights from the limb in the polar coronal hole regions. We detect the presence of long period oscillations with periods of 10 to 30 min in polar coronal holes. The oscillations have an amplitude of a few percent in radiance and are not detectable in line-of-sight velocity. From the time distance maps we find evidence for propagating velocities from 75 km/s (Ne VIII) to 125 km/s (Fe XII). These velocities are subsonic and roughly in the same ratio as the respective sound speeds. We interpret the observed propagating oscillations in terms of slow magneto-acoustic waves. These waves can be important for the acceleration of the fast solar wind.Comment: 5 pages, 7 figures Accepted as Astronomy and Astrophysics Lette

Exploring transmission Kikuchi diffraction using a Timepix detector

Electron backscatter diffraction (EBSD) is a well-established scanning electron microscope (SEM)-based technique [1]. It allows the non-destructive mapping of the crystal structure, texture, crystal phase and strain with a spatial resolution of tens of nanometers. Conventionally this is performed by placing an electron sensitive screen, typically consisting of a phosphor screen combined with a charge coupled device (CCD) camera, in front of a specimen, usually tilted 70° to the normal of the exciting electron beam. Recently, a number of authors have shown that a significant increase in spatial resolution is achievable when Kikuchi diffraction patterns are acquired in transmission geometry; that is when diffraction patterns are generated by electrons transmitted through an electron-transparent, usually thinned, specimen. The resolution of this technique, called transmission Kikuchi diffraction (TKD), has been demonstrated to be better than 10 nm [2,3]. We have recently demonstrated the advantages of a direct electron detector, Timepix [4,5], for the acquisition of standard EBSD patterns [5]. In this article we will discuss the advantages of Timepix to perform TKD and for acquiring spot diffraction patterns and more generally for acquiring scanning transmission electron microscopy micrographs in the SEM. Particularly relevant for TKD, is its very compact size, which allows much more flexibility in the positioning of the detector in the SEM chamber. We will furthermore show recent results using Timepix as a virtual forward scatter detector, and will illustrate the information derivable on producing images through processing of data acquired from different areas of the detector. We will show results from samples ranging from gold nanoparticles to nitride semiconductor nanorods

A cost minimisation analysis of NOACs compared to warfarin to attain therapeutic anticoagulation amongst AF patients, pre- and post-cardioversion

Atrial fibrillation can be managed with anticoagulation and restoration of normal sinus rhythm using direct current cardioversion (DCCV). To reduce the risk of thromboembolism anticoagulation pre-and-post DCCV is recommended. This study investigates the cost effectiveness of using NOACs compared to warfarin to attain therapeutic anticoagulation amongst AF patients pre-and-post DCCV. Propensity score matching revealed no statistically significant difference in outcomes from using NOACs and Warfarin. A cost minimisation study was performed; demonstrating a cost differential of €209 between those administered NOACs and warfarin pre and post DCCV. This study demonstrates how using NOACs compared to warfarin to attain therapeutic anticoagulation amongst AF patients preand-post DCCV is cost effective

Structure and stereochemistry of the base excision repair glycosylase MutY reveal a mechanism similar to retaining glycosidases.

MutY adenine glycosylases prevent DNA mutations by excising adenine from promutagenic 8-oxo-7,8-dihydroguanine (OG):A mismatches. Here, we describe structural features of the MutY active site bound to an azaribose transition state analog which indicate a catalytic role for Tyr126 and approach of the water nucleophile on the same side as the departing adenine base. The idea that Tyr126 participates in catalysis, recently predicted by modeling calculations, is strongly supported by mutagenesis and by seeing close contact between the hydroxyl group of this residue and the azaribose moiety of the transition state analog. NMR analysis of MutY methanolysis products corroborates a mechanism for adenine removal with retention of stereochemistry. Based on these results, we propose a revised mechanism for MutY that involves two nucleophilic displacement steps akin to the mechanisms accepted for 'retaining' O-glycosidases. This new-for-MutY yet familiar mechanism may also be operative in related base excision repair glycosylases and provides a critical framework for analysis of human MutY (MUTYH) variants associated with inherited colorectal cancer

An exploration of occupation in nursing home residents with dementia

Objectives: This study evaluated the sitting room environment of two nursing homes in Ireland, using interactive occupation and social engagement as outcome measures and defining these rooms as occupational spaces. Method: Snapshot observational recordings were made in the main sitting rooms during the periods of time when the rooms were in most active use. Narrative information was also recorded. Results: Residents were more likely to occupy their time in the main sitting room passively, rather than in interactive occupation and social engagement. The nursing home residents with dementia spent approximately 70% of their daily time in the main sitting room areas in states of occupational disengagement. Discussion: Additional insight is provided through pragmatic narrative descriptions of the functioning of the main sitting room environment in terms of interactive occupation and social engagement. Relevance: The research study demonstrates a methodology for evaluating the sitting room areas of a care environment, using interactive occupation and social engagement as outcome measures,which can be used for descriptive and comparative insights into the performance of care environments

Aspects of Graduateness in Computing Students’ Narratives

In this paper, we explore graduates’ characterisations of their learning experiences at university and beyond. Using a narrative methodology, we elicited life stories from graduates of the School of Computing at the University of Kent. We initially review and situate our approach within the wide variety of existing narrative approaches. Then, we turn to an aspect of the student experience that struck us as particularly significant: the “year in industry”. We discuss the accounts of ten participants who completed a year in industry and highlight their perspectives of the effect it had on them. Finally, we propose a narrative construction of the concept of graduateness – of what it means to complete a university degree

Descendants of the first stars: the distinct chemical signature of second generation stars

Extremely metal-poor (EMP) stars in the Milky Way (MW) allow us to infer the properties of their progenitors by comparing their chemical composition to the metal yields of the first supernovae. This method is most powerful when applied to mono-enriched stars, i.e. stars that formed from gas that was enriched by only one previous supernova. We present a novel diagnostic to identify this subclass of EMP stars. We model the first generations of star formation semi-analytically, based on dark matter halo merger trees that yield MW-like halos at the present day. Radiative and chemical feedback are included self-consistently and we trace all elements up to zinc. Mono-enriched stars account for only $\sim 1\%$ of second generation stars in our fiducial model and we provide an analytical formula for this probability. We also present a novel analytical diagnostic to identify mono-enriched stars, based on the metal yields of the first supernovae. This new diagnostic allows us to derive our main results independently from the specific assumptions made regarding Pop III star formation, and we apply it to a set of observed EMP stars to demonstrate its strengths and limitations. Our results may provide selection criteria for current and future surveys and therefore contribute to a deeper understanding of EMP stars and their progenitors.Comment: 18 pages, 20 figures, published in MNRA