Insights into Positionality and the Voicing of Indigeneity in Research : Towards a Critical Theory of Inbetweenness

Western empirical research holds to rules and guidelines informed by the natural sciences, positivism, deductive reasoning, objectivity and precise measures as gold standards of inquiry. Contrasting this worldview, the relational qualities and interconnections essential to Indigenous research are seen as problematic that must acquiesce to the norms of scientific observation. This paper draws upon the literature of key Indigenous researchers and the author’s insights from situated experiences and examine the ways in which the Indigenist paradigm challenges empirical standards in relation to positionality. That is, addressing the struggles of the ‘insider’ and ‘outsider’ standpoints, speaking to the dilemmas of identity, and negotiating the space in-between cultures (Kaomea, 2014). The question of insider and outsider even among Indigenous researchers can be regarded as a space of solvency and richness. The paper contends that with truth and reconciliation and the international recognition of Indigenous rights comes the need to strengthen and politicise Indigenous voices in all its forms. It is especially pressing in the area of knowledge development and dissemination. We share our stories of walking between worlds and reflect on our work experiences across nations. In the end, we hope to advance interest in the narratives affirming Indigenous research as relational, contextual, spiritual and situational.Peer reviewe

Financial reporting by New Zealand charities: finding a way forward

Purpose – Charities are becoming recognised as playing an important part in communities by furthering government’s social objectives through increasing support to disadvantaged members of society. As charities multiply in number, it becomes increasingly difficult for fund providers and contributors to determine which charity to support. In New Zealand there is a move towards providing public access to the financial accounts of charities to assist stakeholders in their decision making and to enhance transparency in charities. However, this assumes that these financial accounts are understandable by all stakeholders. This paper aims to identify four problems that limit the way forward for financial reporting by New Zealand charities. Design/methodology/approach – The first section of the paper comprises a review of the literature on charities’ financial accounts with a particular focus on the four problems identified above. The paper then reports the results of eight interviews with charitable organisations, auditors and academics that have expertise in charity financial reporting, with a particular emphasis on the four identified problems. Findings – There was agreement that unresolved, these four problems could limit the way forward in financial reporting by New Zealand charities. Some recommendations are proposed that suggest a way forward with regard to these problems, so that the users of the financial reports of charities may benefit. Research limitations/implications – Highlights a need for further research into these problems to identify the feasibility of the proposed recommendations. Originality/value – The enactment of the Charities Act 2005 in New Zealand and its requirement to include financial accounts on a publicly available register has raised the profile of the financial reports of charities. However, there has been limited research into the financial reporting by New Zealand charities, so this paper is a timely evaluation of four specific problems that could limit the way forward of financial reporting by New Zealand charities

Editor’s Note: Indigenous Communities and COVID-19: Impact and Implications

Editoral for the Special Issu

Finite-element modelling of no-insulation HTS coils using rotated anisotropic resistivity

The no-insulation (NI) winding method is an effective technique for winding coils from high-Tc superconductors (HTS). NI coils are electrically and thermally robust due to their ability to radially bypass current away from the fragile superconducting path when necessary. This avoids stored magnetic energy being entirely discharged on local defects in the HTS tape. However, the increased degrees of freedom for the current distribution makes finite-element modelling of these coils a complicated and multi-level problem. Here we present and validate a 2D axially symmetric model of an NI (or partially insulated) coil that captures all the inherent electromagnetic properties of these coils, including axial vs radial current flow and critical current suppression, and also reproduces the well-known charging and discharging characteristics. The model is validated against previously reported discharge measurements, and is shown to produce results consistent with the expected equivalent-circuit behaviour. Only by solving the NI coil problem with both axial and radial delity can the interplay of critical current anisotropy and turn-to-turn current be properly accounted for. The reported FE model will now enable coil designers to simulate key complex behaviours observed in NI coils, such as shielding currents, magnetic fi eld inhomogeneity and remnant fi eld effects

Mechanism of the High-Tc Superconducting Dynamo: Models and Experiment

High-Tc superconducting (HTS) dynamos are experimentally proven devices that can produce large, >kA, DC currents in superconducting circuits, without the thermal leak associated with copper current leads. However, these DC currents are theoretically controversial, as it is not immediately apparent why a device that is topologically identical to an AC alternator should give a DC output at all. Here, we present a finite-element model, and its comparison with experiment, which fully explains this effect. It is shown that the DC output arises naturally from Maxwell’s laws, when time-varying overcritical eddy currents are induced to circulate in an HTS sheet. We first show that our finite-element model replicates all of the the experimental electrical behavior reported so far for these devices, including the DC output characteristics, and transient electrical waveforms. Direct experimental evidence for the presence of circulating eddy currents is also obtained through measurements of the transient magnetic field profile across the HTS tape, using a linear Hall array. These results are also found to closely agree with predictions from the finite-element model. Following this experimental validation, calculated sheet current densities and the associated local electric fields are examined for a range of frequencies and net transport currents. We find that the electrical output from an HTS dynamo is governed by the competition between transport and eddy currents induced as the magnet transits across the HTS tape. These eddy currents are significantly higher (∼1.5X) than the local critical current density J_c, and hence experience a highly non-linear local resistivity. This non-linearity breaks the symmetry observed in a normal ohmic material, which usually requires the net transport current to vary linearly with the average electric field. The interplay between local current densities and non-linear resistivities (which both vary in time and space) is shown to systematically give rise to the key observed parameters for experimental HTS dynamo devices: the open-circuit voltage V_oc, the internal resistance R_int, and the short-circuit current I_sc. Finally, we identify that the spatial boundaries formed by each edge of the HTS stator tape play a vital role in determining the total DC output. This offers the potential to develop new designs for HTS dynamo devices, for which the internal resistance is greatly reduced and the short circuit current is substantially increased.New Zealand (NZ) MBIE Endeavour Grant No. RTVU1707 NZ Royal Society Marsden Grant No. MFP-VUW1806

Special Issue Foreword

JISD Foreword for Special Issue on Love

Cooper pair trajectories in superconducting slab at self-field conditions

Dissipative-free electric current flow is one of the most fascinating and practically important properties of superconductors. Theoretical consideration of the charge carriers flow in infinitely long rectangular slab of superconductor in the absence of external magnetic field (so called, self-field) is based on an assumption that the charge carriers have rectilinear trajectories in the direction of the current flow whereas the current density and magnetic flux density are decaying towards superconducting slab with London penetration depth as characteristic length. Here, we calculate charge particle trajectories (as single electron/hole, as Cooper pair) at self-field conditions and find that charge carriers do not follow intuitive rectilinear trajectories along the slab surface, but instead ones have meander shape trajectories cross the whole thickness of the slab. Moreover, if the particle velocity is below some value, the charge moves in opposite direction to nominal current flow. This disturbance of the canonical magnetic flux density distribution and backward movement of Cooper pairs can be entire mechanism for power dissipation in superconductors. © 2021 World Scientific Publishing Company.EFT thanks financial support provided by the state assignment of Minobrnauki of Russia (theme “Pressure” No. AAAA-A18-118020190104-3) and by Act 211 Government of the Russian Federation, contract No. 02.A03.21.0006

Classifying superconductivity in ThH-ThD superhydrides/superdeuterides

Satterthwaite and Toepke (1970 Phys. Rev. Lett. 25 741) discovered that Th4H15-Th4D15 superhydrides are superconducting but exhibit no isotope effect. As the isotope effect is a fundamental prediction of electron-phonon mediated superconductivity described by Bardeen, Cooper, and Schrieffer (BCS) its absence alludes to some other mechanism. Soon after this work, Stritzker and Buckel (1972 Zeitschrift für Physik A Hadrons and nuclei 257 1-8) reported that superconductors in the PdHx-PdDx system exhibit the reverse isotope effect. Yussouff et al (1995 Solid State Communications 94 549) extended this finding in PdHx-PdDx-PdTx systems. Renewed interest in hydrogen- and deuterium-rich superconductors is driven by the discovery of near-room-temperature superconductivity in highly-compressed H3S (Drozdov et al 2015 Nature 525 73) and LaH10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001). Here we attempt to reaffirm or disprove our primary idea that the mechanism for near-room-temperature superconductivity in hydrogen-rich superconductors is not BCS electron-phonon mediated. To that end, we analyse the upper critical field data, B c2(T), in Th4H15-Th4D15 (Satterthwaite and Toepke 1970 Phys. Rev. Lett. 25 741) as well as two recently discovered high-pressure hydrogen-rich phases of ThH9 and ThH10 (Semenok et al 2019 Materials Today, DOI: 10.1016/j.mattod.2019.10.005). We conclude that all known thorium super-hydrides/deuterides, to date, are unconventional superconductors - along with the heavy fermions, fullerenes, pnictides, cuprates - where we find they have T c/T F ratios within a range of 0.008 < T c/T F < 0.120, where T c is the superconducting transition temperature and T F is the Fermi temperature. © 2020 The Author(s). Published by IOP Publishing Ltd

A new benchmark problem for electromagnetic modelling of superconductors: the high-Tc_{c} superconducting dynamo

The high-T$_{c}$ superconducting (HTS) dynamo is a promising device that can inject large DC supercurrents into a closed superconducting circuit. This is particularly attractive to energise HTS coils in NMR/MRI magnets and superconducting rotating machines without the need for connection to a power supply via current leads. It is only very recently that quantitatively accurate, predictive models have been developed which are capable of analysing HTS dynamos and explain their underlying physical mechanism. In this work, we propose to use the HTS dynamo as a new benchmark problem for the HTS modelling community. The benchmark geometry consists of a permanent magnet rotating past a stationary HTS coated-conductor wire in the open-circuit configuration, assuming for simplicity the 2D (infinitely long) case. Despite this geometric simplicity the solution is complex, comprising time-varying spatially-inhomogeneous currents and fields throughout the superconducting volume. In this work, this benchmark problem has been implemented using several different methods, including H-formulation-based methods, coupled H-A and T-A formulations, the Minimum Electromagnetic Entropy Production method, and integral equation and volume integral equation-based equivalent circuit methods. Each of these approaches show excellent qualitative and quantitative agreement for the open-circuit equivalent instantaneous voltage and the cumulative time-averaged equivalent voltage, as well as the current density and electric field distributions within the HTS wire at key positions during the magnet transit. Finally, a critical analysis and comparison of each of the modelling frameworks is presented, based on the following key metrics: number of mesh elements in the HTS wire, total number of mesh elements in the model, number of degrees of freedom, tolerance settings and the approximate time taken per cycle for each model. This benchmark and the results contained herein provide researchers with a suitable framework to validate, compare and optimise their own methods for modelling the HTS dynamo