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Macroalgae removal is a proposed management option in the GBR to reverse declines in inshore coral reef health. Automated image analysis (AIA) is a valuable tool to assess benthic community assemblages. This study compared the accuracy of benthic community assemblages assessed through the AIA program CoralNet to manual image analysis. The ecological effect of macroalgae removal on benthic community composition was also investigated on established permanent quadrats (5x5 m) for reefs at Florence and Arthur Bay, Magnetic Island. Control and treatment quadrats (n=3 respectively) were photographed before and after macroalgae removal over 6 months. The results obtained by AIA and manual approaches were consistent, with macroalgae cover is approximately 77%-87% in all quadrats before macroalgal removal. Through the monitoring period, a small increase in coral cover in the macroalgal removal quadrats was observed in Florence and Arthur Bay (an increase of 1.8% and 0.1%, respectively). CoralNet was demonstrated to be robust for assessing reef benthic cover with no significant difference in recorded benthic categories when compared to the manual approach. CoralNet was accurate for identifying broad benthic categories, but less effective than manual image analyses for lower taxonomic categories (i.e., genus or species level).

We present THEMIS observations of a small‐scale secondary magnetic island within the Hall electromagnetic field region at the dayside magnetopause. The reconnecting magnetic fields are nearly symmetric and anti‐parallel, whereas the ion plasma density is ∼8 times higher in the magnetosheath than in the magnetosphere. In the event, the Hall magnetic and electric fields are asymmetric and stronger on the magnetospheric side of the magnetopause. The small‐scale magnetic island was immersed in the out‐of‐plane Hall magnetic field on the magnetosheath side. We derive a map of the cross section of the magnetic island by use of magnetohydrostatic Grad‐Shafranov reconstruction under the force‐free assumption. The reconstruction shows a right‐handed magnetic island with a length of ∼200 km and a width of ∼100 km.

Filamentary eruptions from the plasma edge in fusion devices pose a critical threat to their integrity. The identification of magnetic islands at the top of the edge explains how these eruptions are suppressed by resonant magnetic perturbations.

Magnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for the nonlinear MI evolution, but a lack of detailed experimental observations and analyses has prevented further understanding. Here, we provide comprehensive observations such as turbulence spreading into an MI and turbulence enhancement at the reconnection site, elucidating intricate effects of plasma turbulence on the nonlinear MI evolution. Magnetic reconnection and plasma turbulence occur in atmospheric and magnetized laboratory plasmas. Here the authors report evolution of magnetic islands and plasma turbulence in tokamak plasmas using high resolution 2D electron cyclotron emission diagnostics.

Significant evidence of late Holocene beach faces is presented in beach ridges along the North Queensland coast between Mackay and the Daintree region. The ages of these ridges has in some cases been dated giving confidence that the rearmost ridges are the result of a combination of cyclone activity and a late Holocene sea level high-stand. The height of this high-stand is the subject of debate, however the level may be confidently predicted through careful and extensive measurement of relict oyster beds in the region. Using pre-existing beach ridge research together with existing and new measurements of oyster beds on Magnetic Island, North Queensland a value for the late Holocene sea level high-stand is proposed which can be compared to the position of the coast on certain beaches during this period. These measurements are a good basis to test the applicability of the Bruun rules and some proposed modifications for the low energy beach systems of tropical North Queensland. This paper firstly examined the late Holocene sea level evidence stored in relict oyster beds and from that proposes a sea level to be used in the analysis. This sea level is then used to test the Bruun rule and variants and examine the differences between dated Holocene beach faces and the recession predicted by these models.

The modification of geometry and interactions in two-dimensional magnetic nanosystems has enabled a range of studies addressing the magnetic order1–6, collective low-energy dynamics7,8 and emergent magnetic properties5, 9,10 in, for example, artificial spin-ice structures. The common denominator of all these investigations is the use of Ising-like mesospins as building blocks, in the form of elongated magnetic islands. Here, we introduce a new approach: single interaction modifiers, using slave mesospins in the form of discs, within which the mesospin is free to rotate in the disc plane11. We show that by placing these on the vertices of square artificial spin-ice arrays and varying their diameter, it is possible to tailor the strength and the ratio of the interaction energies. We demonstrate the existence of degenerate ice-rule-obeying states in square artificial spin-ice structures, enabling the exploration of thermal dynamics in a spin-liquid manifold. Furthermore, we even observe the emergence of flux lattices on larger length scales, when the energy landscape of the vertices is reversed. The work highlights the potential of a design strategy for two-dimensional magnetic nano-architectures, through which mixed dimensionality of mesospins can be used to promote thermally emergent mesoscale magnetic states.

Majorana zero modes are fractional quantum excitations appearing in pairs, each pair being a building block for quantum computation. Some signatures of Majorana zero modes have been reported at endpoints of one-dimensional systems, which are however required to be extremely clean. An alternative are two-dimensional topological superconductors, such as the Pb/Co/Si(111) system shown recently to be immune to local disorder. Here, we use scanning tunneling spectroscopy to characterize a disordered superconducting monolayer of Pb coupled to underlying Co-Si magnetic islands. We show that pairs of zero modes are stabilized: one zero mode positioned in the middle of the magnetic domain and its partner extended all around the domain. The zero mode pair is remarkably robust, isolated within a hard superconducting gap. Our theoretical scenario supports the protected Majorana nature of this zero mode pair, highlighting the role of magnetic or spin-orbit coupling textures. It is predicted that Majorana zero modes can appear locally around topological defects in a two-dimensional system. Here, the authors observe pairs of zero modes stabilized in the middle and around the magnetic domains in a disordered superconducting Pb monolayer.

Turbulent magnetic reconnection is believed to occur in astrophysical plasmas, and it has been suggested to be a trigger of solar flares. It often occurs in long stretched and fragmented current sheets. Recent observations by the Parker Solar Probe, the Solar Dynamics Observatory and in situ satellite missions agree with signatures expected from turbulent reconnection. However, the underlying mechanisms, including how magnetic energy stored in the Sun’s magnetic field is dissipated, remain unclear. Here we demonstrate turbulent magnetic reconnection in laser-generated plasmas created when irradiating solid targets. Turbulence is generated by strongly driven magnetic reconnection, which fragments the current sheet, and we also observe the formation of multiple magnetic islands and flux-tubes. Our findings reproduce key features of solar flare observations. Supported by kinetic simulations, we reveal the mechanism underlying the electron acceleration in turbulent magnetic reconnection, which is dominated by the parallel electric field, whereas the betatron mechanism plays a cooling role and Fermi acceleration is negligible. As the conditions in our laboratory experiments are scalable to those of astrophysical plasmas, our results are applicable to the study of solar flares.Laboratory experiments reveal the underlying mechanism of turbulent reconnection, including electron acceleration. These findings are directly relevant for studies of flares in the solar corona.

In tokamaks, a leading platform for fusion energy, periodic filamentary plasma eruptions known as edge-localized modes occur in plasmas with high-energy confinement and steep pressure profiles at the plasma edge. These edge-localized modes could damage the tokamak wall but can be suppressed using small three-dimensional magnetic perturbations. Here we demonstrate that these magnetic perturbations can change the magnetic topology just inside the steep gradient region of the plasma edge. We identify signatures of a magnetic island, and their observation is linked to the suppression of edge-localized modes. We compare high-resolution measurements of perturbed magnetic surfaces with predictions from ideal magnetohydrodynamic theory where the magnetic topology is preserved. Although ideal magnetohydrodynamics adequately describes the measurements in plasmas exhibiting edge-localized modes, it proves insufficient for plasmas where these modes are suppressed. Nonlinear resistive magnetohydrodynamic modelling supports this observation. Our study experimentally confirms the predicted role of magnetic islands in inhibiting the occurrence of edge-localized modes. This will be beneficial for physics-based predictions in future fusion devices to control these modes. The suppression of edge-localized modes in tokamak plasmas is crucial to prevent them from damaging the walls of the chamber. Now experiments confirm the role that magnetic islands play in suppressing these detrimental modes.

Recent accumulation of a critical mass of observational material from different spacecraft complete with the enhanced abilities of numerical methods have led to a boom of studies revealing the high complexity of processes occurring in the heliosphere. Views on the solar wind filling the interplanetary medium have dramatically developed from the beginning of the space era. A 2-D picture of the freely expanding solar corona and non-interacting solar wind structures described as planar or spherically-symmetric objects has dominated for decades. Meanwhile, the scientific community gradually moved to a modern understanding of the importance of the 3-D nature of heliospheric processes and their studies via MHD/kinetic simulations, as well as observations of large-scale flows and streams both in situ and remotely, in white light and/or via interplanetary scintillations. The new 3-D approach has provided an opportunity to understand the dynamics of heliospheric structures and processes that could not even be imagined before within the 2-D paradigm. In this review, we highlight a piece of the puzzle, showing the evolution of views on processes related to current sheets, plasmoids, blobs and flux ropes of various scales and origins in the heliosphere. The first part of the review focuses on introducing these plasma structures, discussing their key properties, and paying special attention to their observations in different space plasmas.