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Sensitivity analysis of the Swarm-observed magnetospheric magnetic field to Earth's large-scale mantle electrical conductivity inhomogeneities
Get PDFArthurian references in medieval Welsh poetry, c. 1100-c. 1540
Get PDFA survey of references to characters and events with a connection to Arthur and the Arthurian story-world within the works of medieval Welsh poets. The specifically `Arthurian' poems are excluded as they are dealt with by another contributor in the volume. Instead, the poems examined here are praise poetry, love poetry, satire, prophecy and religious verse. The chapter explores the changing aspects of the Arthurian story-world to which medieval Welsh poets make reference. In the twelfth century, references indicate that the poets accessed a predominantly native Arthurian tradition, but were already being exposed to French Arthurian literature. French influence increased steadily over the centuries to become quite predominant, but some memory was retained of divergent and sometimes conflicting Welsh traditions of Arthur
Brief rules for reading Irish found in printed books, 1571-1863
Get PDFThis paper surveys short guides to reading Irish that appeared with Irish-language texts in printed books between 1571 and 1863. These brief rules are situated within the history of writing on Irish grammar and attention is drawn to the information on Irish phonology to be gleaned from them
Transmission, metre and language: some observations on the poetry of Giolla Brighde Mac Con Midhe
Get PDFThis chapter seeks to establish the true corpus of extant poems by the famous thirteenth-century poet Giolla Brighde Mac Con Midhe; addresses some textual issues in the published edition; and studies linguistic and metrical variation in Mac Con Midhe's work as a contribution to understanding his superb artistry
Upper limits on very-high-energy gamma-ray emission from core-collapse supernovae observed with H.E.S.S.
Get PDFYoung core-collapse supernovae with dense-wind progenitors may be able to accelerate cosmic-ray hadrons beyond the knee of the cosmic-ray spectrum, and this may result in measurable gamma-ray emission. We searched for gamma-ray emission from ten supernovae observed with the High Energy Stereoscopic System (H.E.S.S.) within a year of the supernova event. Nine supernovae were observed serendipitously in the H.E.S.S. data collected between December 2003 and December 2014, with exposure times ranging from 1.4 to 53 h. In addition we observed SN 2016adj as a target of opportunity in February 2016 for 13 h. No significant gamma-ray emission has been detected for any of the objects, and upper limits on the >1 TeV gamma-ray flux of the order of 10^-13 cm-2s-1 are established, corresponding to upper limits on the luminosities in the range 2 x 10^39 to 1 x 10^42 erg s-1. These values are used to place model-dependent constraints on the mass-loss rates of the progenitor stars, implying upper limits between 2 x 10^-5 and 2 x 10^-3 Msun yr-1 under reasonable assumptions on the particle acceleration parameters
Seismic Discrimination between Earthquakes and Quarry Blasts In Ireland
Get PDFThe Irish National Seismic Network (INSN) is operated by the Dublin Institute for Advanced Studies (DIAS) and consists of six broadband permanent seismic stations in Ireland that stream data in real-time. Temporary, offline seismic networks operated by DIAS since 2010 include the Ireland Array (IA), SIMCRUST, and ISLE networks, and the WAVEOBS network, operated jointly by University College Dublin (UCD) and DIAS. The British Geological Survey (BGS) has been operating a station in Northern Ireland since 2012. As a result, seismic event detection in Ireland has increased since 2010, with several hundred events detected per year. However, the vast majority of events (~99%) are believed to be quarry blasts. To avoid contamination of earthquake catalogs by man-made events, a robust discriminant, or set of discriminants is necessary. We examine if earthquakes and quarry blasts can be separated at local distances (less than 200km) by using two waveform-based discriminants. We find that traditional P/S amplitude ratios show very little separation, whereas an S-wave spectral ratio achieves much greater separation between these two types of events
Review: Immo Warntjes and Dáibhí Ó Cróinín, eds, Late Antique Calendrical Thought and its Reception in the Early Middle Ages: Proceedings of the 3rd International Conference on the Science of Computus in Ireland and Europe, Galway, 16–18 July, 2010 (Turnhout 2017).
Get PDFThis book review includes discussion of the following:
-the progress of research on ancient and medieval computus as a whole
-the significance of computus in philosophical and theological history
-the need for a non-teleological approach to the history of science
-generally unexamined historiographical assumptions in the field of Early Irish
-the need for a verifiable approach to the symbolic significance of numbers in Hiberno-Latin literatu
Modelling of electromagnetic signatures of global ocean circulation: physical approximations and numerical issues
No full textThe interactions of flowing electrically conductive seawater with Earth’s magnetic field generate electric currents within the oceans, as well as secondary electric currents induced in the resistive solid Earth. The ocean-induced magnetic field (OIMF) is an observable signature of these currents. Ignoring tidally forced ocean flows, the global ocean circulation system is driven by wind forcing on the ocean surface and by the temperature- and salinity-dependent buoyancy force. Ocean circulation’s magnetic signals contribute to the total magnetic field observed at the Earth’s surface or by low-orbit satellite missions. In this paper, we concentrate on accurate numerical modelling of the OIMF employing various approaches. Using a series of numerical test cases in different scenarios of increasing complexity, we evaluate the applicability of the unimodal thin-sheet approximation, the importance of galvanic coupling between the oceans and the underlying mantle (i.e. the bimodal solution), the effects of vertical stratification of ocean flow as well as the effects of vertical stratification of both oceanic and underlying electrical conductivity, and the influence of electromagnetic self-induction. We find that the inclusion of galvanic ocean-mantle coupling has the largest effect on the predicted OIMF. Self-induction is important only on the largest spatial scales, influencing the lowest spherical harmonic coefficients of the OIMF spectrum. We find this conclusion important in light of the recent Swarm satellite mission which has the potential to observe the large-scale OIMF and its seasonal variations. The implementation of fully three-dimensional ocean flow and conductivity heterogeneity due to bathymetry, which substantially increases the computational demands of the calculations, can play some role for regional studies, or when a more accurate OIMF prediction is needed within the oceans, e.g. for comparison with seafloor observations. However, the large-scale signals at the sea surface or at satellite altitude are less affected
Review of Ulidia 4: Proceedings of the Fourth International Conference on the Ulster Cycle of Tales, Queen’s University, Belfast, 27–9 June 2013.
Get PDFA combinatorial identity
Get PDFWe give an elementary proof of an interesting combinatorial identity which is of particular interest in graph theory and its applications