549 research outputs found
Identifying the magnetotail lobes with Cluster magnetometer data
No full textWe describe a novel method for identifying times when a spacecraft is in Earth’s magnetotail lobes solely using magnetometer data. We propose that lobe intervals can be well identified as times when the magnetic field is strong and relatively invariant, defined using thresholds in the magnitude of BX and the standard deviation σ of the magnetic field magnitude. Using data from the Cluster spacecraft at downtail distances greater than 8 RE during 2001–2009, we find that thresholds of 30 nT and 3.5 nT, respectively, optimize agreement with a previous, independently derived lobe identification method that used both magnetic and plasma data over the same interval. Specifically, our method has a moderately high accuracy (66%) and a low probability of false detection (11%) in comparison to the other method. Furthermore, our method identifies the lobe on many other occasions when the previous method was unable to make any identification and yields longer continuous intervals in the lobe than the previous method, with intervals at the 90th percentile being triple the length. Our method also allows for analyses of the lobes outside the time span of the previous method
'Giving honour to the Spirit' : a critical analysis and evaluation of the doctrine of pneumatological union in the Trinitarian theology of Jonathan Edwards in dialogue with Karl Barth
No full textThe extent to which the 'honour' of the Spirit influenced the theology of
Jonathan Edwards is a hitherto underdeveloped theme. Against a backdrop of
Patristic thought and in dialogue with the theology of Karl Barth, evaluation is
made of pneumatological union in Edwards' Trinitarian theology as this centres
on the nature and inter-relatedness of the 'three unions' that characterize his
theology: the union of the three Persons of the Trinity, the union of the saints
with God, and the union of the divine and human natures of Christ.
Edwards' seeks to honour the Spirit as the mutual love of the Father for the Son
within his Augustinian, Lockean model of the immanent Trinity, and as 'Person'
in the economy. The challenges of doing so within the limits of this
psychological model of the Trinity are evaluated in dialogue with the
Cappadocian Fathers and Barth.
In a manner patterned after union in the Trinity, Edwards gave prominence to the
concept of the pneumatological union of the saints with God in Christ, in
fulfilment of the self-glorifying purpose of God in creation and redemption.
Edwards' experiential theology of conversion, and his elevation of subjective
sanctification by the Spirit over objective justification in Christ, for assurance, is
contrasted with Barth's greater emphases on the Christological union of God
with humanity and objective justification in Christ. Barth's more contemplative
approach is contrasted with the overly introspective spirituality of Edwards.
Edwards' view of the role of the Spirit in the hypostatic union of God with
humanity in Christ, which is reflective of the other unions, is also evaluated in
light of Patristic, Reformed-Puritan and Barthian thought on the nature of the
humanity Christ assumed, and the doctrine of the vicarious humanity of Christ. A
more emphatic incarnational emphasis may have saved Edwards' Spirit-
honouring spirituality from an anthropocentricity which is ironical given that the
glory of God is his ontic doxological concern
Birkeland currents during substorms: Statistical evidence for intensification of Regions 1 and 2 currents after onset and a localized signature of auroral dimming
No full textWe conduct a superposed epoch analysis of Birkeland current densities from AMPERE (Active Magnetosphere and Planetary Electrodynamics Response Experiment) using isolated substorm expansion phase onsets identified by an independently derived data set. In order to evaluate whether R1 and R2 currents contribute to the substorm current wedge, we rotate global maps of Birkeland currents into a common coordinate system centered on the magnetic local time of substorm onset. When the latitude of substorm is taken into account, it is clear that both R1 and R2 current systems play a role in substorm onset, contrary to previous studies which found that R2 current did not contribute. The latitude of substorm onset is colocated with the interface between R1 and R2 currents, allowing us to infer that R1 current closes just tailward and R2 current closes just earthward of the associated current disruption in the tail. AMPERE is the first data set to give near-instantaneous measurements of Birkeland current across the whole polar cap, and this study addresses apparent discrepancies in previous studies which have used AMPERE to examine the morphology of the substorm current wedge. Finally, we present evidence for an extremely localized reduction in current density immediately prior to substorm onset, and we interpret this as the first statistical signature of auroral dimming in Birkeland current
THEMIS Magnetopause Crossing Database V2
No full textArchived data for the manuscript “Do statistical models capture the dynamics of the magnetopause during sudden magnetospheric compressions?” by Staples et al., 2020, Journal of Geophysical Research: Space Physics (Accepted, DOI pending). This file contains the THEMIS magnetopause crossing data, including time and location of each THEMIS probe magnetopause crossing classified between 2007 and 2016 (inclusive). For detailed description of the method used to classify these magnetopause crossings, see section 3.1 in the manuscript. The THEMIS data used for the classification is publicly available via http://cdaweb.gsfc.nasa.gov . VERSION 2: In version 2 of this dataset, we have removed duplicate records of magnetopause crossings which were present in veersion 1.Frances A Staples, Ashley R. A. Smith, Colin Forsyth, & I. Jonathan Rae. (2024). THEMIS Magnetopause Crossing Database V2 [Data set]. Zenodo. https://doi.org/10.5281/zenodo.1065531
Tailward propagation of magnetic energy density variations With respect to substorm onset times
No full textDuring geomagnetic substorms, around 1015 J of energy is extracted from the solar wind and processed by the Earth's magnetosphere. Prior to the onset of substorm expansion phases, this energy is thought to be largely stored as an increase in the magnetic field in the magnetotail lobes. However, how, when, and where this energy is stored and released within the magnetotail is unclear. Using data from the Cluster spacecraft and substorm onsets from Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE), we examine the variation in the lobe magnetic energy density with respect to substorm onset for 541 isolated onsets. Based on a cross‐correlation analysis and a simple model, we deduce the following: On average, the magnetic energy density increases approximately linearly in the hour preceding onset and decreases at a similar rate after onset. The timing and magnitude of these changes varies with downtail distance, with observations from the mid‐tail ( urn:x-wiley:jgra:media:jgra54303:jgra54303-math-0001) showing larger changes in the magnetic energy density that occur ∼20 min after changes in the near‐tail ( urn:x-wiley:jgra:media:jgra54303:jgra54303-math-0002). The decrease in energy density in the near‐tail region is observed before the ground onset identified by SOPHIE, implying that the substorm is driven from the magnetotail and propagates into the ionosphere. The implication of these results is that energy in the near‐tail region is released first during the substorm expansion phase, with energy conversion propagating away from the Earth with time
THEMIS Magnetopause Crossing Database
No full textArchived data for the manuscript “Do statistical models capture the dynamics of the magnetopause during sudden magnetospheric compressions?” by Staples et al., 2020, Journal of Geophysical Research: Space Physics (Accepted, DOI pending). This file contains the THEMIS magnetopause crossing data, including time and location of each THEMIS probe magnetopause crossing classified between 2007 and 2016 (inclusive). For detailed description of the method used to classify these magnetopause crossings, see section 3.1 in the manuscript. The THEMIS data used for the classification is publicly available via http://cdaweb.gsfc.nasa.gov . Since uploading this file, we noted some duplicate records of crossings in this data file. We recommend that users remove these crossings. Python code to do this can be found here.Frances A Staples, Ashley R. A. Smith, Colin Forsyth, & I. Jonathan Rae. (2020). THEMIS Magnetopause Crossing Database (Version 1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.370050
Journal rankings and the ABS Journal Quality Guide
No full textThe purpose of this paper is to provide an outline of the arguments for and against different
types of journal ranking lists, and, against this background, an account of the development of the
Association of Business Schools' (ABS) Journal Quality Guide. The paper identifies recent trends in academic journal publication that have increased the need for mechanisms to assess the overall quality of academic journals. Six approaches to ranking are outlined and evaluated including the hybrid approach adopted in producing the ABS Journal Quality Guide. The ABS Journal Quality Guide provides wide journal coverage; has high levels of internal and external reliability; is sensitive to small variations in the ratings of journals, and is generally accepted as a fair means of ranking journals within its user community. This paper focuses on developments in the UK, and while the findings of this study may be of interest to researchers in other countries, the implications for policy and practice will be felt most keenly in British business schools. This paper describes a hybrid, iterative and consensual approach to developing and validating a journal quality guide that is likely to be of value to researchers, academic managers, subject librarians and research auditors
Objectifying Power : A Study of Visual Representations of Politicians in I Am Greta (2020)
No full textIn this study I will explore the representations of politicians in the documentary film I Am Greta (2020). Drawing from Stuart Halls work on representation and Martha Nussbaums and Rae Langtons theories on objectification, I will conduct a multimodal semiotic analysis in which the representations of people and persons are studied. The findings point towards the representation of politicians through stereotyping practices and signifying difference. I also conclude that individuals identified as politicians are objectified through representation. Contextualised within populist climate discourse, these representations of politicians might aid in the discursive construction referred to as the establishment.
Trinity, Economy, and Scripture: A Theologically-Motivated Recovery of Didymus the Blind
No full textIn this study I examine the question of the normativity of Didymus the Blind’s exegetical practices in light of his scriptural ontology. Given that Didymus understands the Scriptures primarily in relation to their function in the Triune economy of re-creation, I ask what this economy can tell us about how Scripture should be read. This involves the antecedent consideration of God’s being in its relationship to this economy and subsequent considerations of the human responses that are generated by participation in this economy.
In chapter two, I argue that the state of the question on De Trinitate favors its attribution to Didymus, encouraging an attempt at rapprochement between his dogmatic and exegetical corpus. In chapter three, I take up the question of how Didymus, in De Trinitate, links Trinitarian being and what is particular to the hypostaseis with the activities of the hypostaseis in the economy. Chapter four contains my summary of the broad lines of Didymus’ scriptural ontology. The speech of the prophets and the apostles is located firmly within the divine economy to which they bear witness. I argue that Didymus’ account of Scripture in De Trinitate supports readings that recognize the inherence of Triune activity within the Old Testament, the christological focus of Scripture, and the deeply participational (or baptismal) character of proper interpretation.
In chapter five, I turn to the Commentary on Zechariah to take up the question of the manner in and extent to which other people can be said to be conformed to the virtues of Christ, noting that Didymus believes such conformation to be possible in the present life with the help of God. In chapter six, I visit the issue of whether human knowledge of the Trinity progresses in the age to come in relation to the Son’s mediation of divine knowledge. I note two deficiencies of Didymus’ account of the economy in his denial of Christ’s material embodiedness in the eschaton and in his conviction that human knowledge of the Trinity must come to the point at which progress is no longer possible.
In chapter seven, I examine the consequences of the above determinations about the economy for the reading of Zechariah 3, engaging with questions about Didymus’ employment of the criterion of the literal sense’s usefulness, his understanding of the historical dimensions of the vision, and the resulting vision of Christ that emerges from his reading. While I argue that certain elements of his reading practice are recoverable – his theologically-informed reading of history and the baptismal and participational character of faithful reading – I argue that his account of the mystery of Christ is finally deficient because he construes the “literal sense” in such a way that it no longer possesses the power to illumine critical aspects of Christ’s mystery in the “spiritual sense.”
In the conclusion, I briefly draw together the various threads of the argument and bring them to bear on select conversations about the ongoing usefulness of patristic exegesis for the reading practices of the Church
Magnetospheric field‐line resonances: Ground‐based observations and modelingournal of Geophysical Research: Space Physics, 110(A10), [pp
No full textWe present theory and ground-based observations of field-line resonances (FLRs) excited in Earth's magnetosphere. Three FLR observations are reported, which correspond to large-scale standing shear Alfven wave (SAW) oscillations on nightside field lines extending from premidnight to close to dawn. The eigenfrequencies for these events are modeled using a nonorthogonal covariant-contravariant analysis of the ideal magnetohydrodynamic (MHD) equations. This allows us to use a general field-line topology, an example of which is computed using the Tsyganenko 1996 magnetic field model. We show that field-line stretching, along with assumptions regarding the distribution of density along field lines, is sufficient to explain the observed FLR frequencies. Then, we consider dispersive effects operating at the level of the electron inertial scale near the ionosphere or the ion-acoustic gyroradius in the vicinity of the equatorial plane. Specifically, we estimate the spatial saturation widths and phase mixing timescales based on a simple model of dispersive SAWs. By considering a new model for ionospheric Pedersen conductivity modification by field-aligned currents in SAWs and numerical ( finite element model) solutions to the reduced MHD equations, we model specific FLR observations in an approximate axisymmetric field topology. We discuss the interplay of linear and nonlinear phase mixing, along with gradients in dispersion and time-dependent losses due to Pedersen conductivity enhancements
- …
