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Abrupt variations of auroral electrojets can induce geomagnetically induced currents, and the ability to model and forecast them is a pressing goal of space weather research. We report an auroral electrojet spike event that is extreme in magnitude, explosive in nature, and global in spatial extent that occurred on 24 April 2023. The event serves as a fundamental test of our understanding of the response of the geospace system to solar wind dynamics. Our results illustrate new and important characteristics that are drastically different from existing knowledge. Most important findings include (a) the event was only of ∼5‐min duration and was limited to a narrow (2°–3°) band of diffuse aurora; (b) the longitudinal span covered the entire nightside sector, possibly extending to the dayside; (c) the trigger seems to be a transient solar wind dynamic pressure pulse. In comparison, substorms usually last 1–2 hr and span almost the entire latitudinal width of the auroral oval. Magnetic perturbation events (MPEs) span hundreds km in radius. Both substorms and MPEs are mainly driven by disturbances in the magnetotail. A possible explanation is that the pressure pulse compresses the magnetosphere and enhances diffuse precipitation of electrons and protons from the inner plasma sheet, which elevates the ionospheric conductivity and intensifies the auroral electrojet. Therefore, the event exhibits a potentially new type of geomagnetic disturbance and highlights a solar wind driver that is enormously influential in driving extreme space weather events. Plain Language Summary Auroral electrojets are horizontal electric currents that flow in the auroral ionosphere, and extreme auroral electrojet activities can induce geomagnetically induced currents that damage high‐voltage power transformers and increase steel corrosion of pipeline networks. Understanding what drives the extreme events is therefore a pressing goal of space weather research. We report an auroral electrojet spike event that is extreme in magnitude, explosive in nature, and global in spatial extent that occurred on 24 April 2023. The event serves as a fundamental test of our understanding of the response of the geospace system to solar wind dynamics. Most important findings include (a) the event was only of ∼5‐min duration and was limited to a narrow band of diffuse aurora; (b) the longitudinal span covered the entire nightside sector; (c) the trigger seems to be a transient solar wind dynamic pressure pulse. These features differ drastically from other widely known geomagnetic disturbances such as substorms or magnetic perturbation events, and signify a potentially new type of disturbance. A possible explanation is that the solar wind pressure pulse compresses the magnetosphere, enhances diffuse precipitation of particles into the ionosphere, and elevates the ionospheric conductivity. Key Points An abrupt and intense auroral electrojet enhancement occurred during the storm of 24 April 2023 This extreme event differs from typical geomagnetic disturbances in terms of magnitude, spatiotemporal extent, and physical driver The event was triggered by a solar wind pressure pulse, which enhanced diffuse auroral precipitation and ionospheric conductivity

Ultralight dark matter, such as kinetically mixed dark-photon dark matter (DPDM) or axionlike-particle dark matter (axion DM), can source an oscillating magnetic-field signal at Earth's surface. Previous work searched for this signal in a publicly available dataset of global magnetometer measurements maintained by the SuperMAG collaboration. This ``low-fidelity\" dataset reported measurements with a 1-minute time resolution, allowing the search to set leading direct constraints on DPDM and axion DM with Compton frequencies \\(f_DM1/(1\\,min)\\) [corresponding to masses \\(m_DM710^-17\\,eV\\)]. More recently, a dedicated experiment undertaken by the SNIPE Hunt collaboration has also searched for this same signal at higher frequencies \\(f_DM0.5\\,Hz\\) (or \\(m_DM210^-15\\,eV\\)). In this work, we search for this signal of ultralight DM in the SuperMAG ``high-fidelity\" dataset, which features a 1-second time resolution, allowing us to probe the gap in parameter space between the low-fidelity dataset and the SNIPE Hunt experiment. The high-fidelity dataset exhibits lower geomagnetic noise than the low-fidelity dataset and features more data than the SNIPE Hunt experiment, making it a powerful probe of ultralight DM. Our search finds no robust DPDM or axion DM candidates. We set constraints on DPDM and axion DM parameter space for \\(10^-3\\,Hz f_DM0.98\\,Hz\\) (or \\(410^-18\\,eV m_DM410^-15\\,eV\\)). Our results are the leading direct constraints on both DPDM and axion DM in this mass range, and our DPDM constraint surpasses the leading astrophysical constraint in a narrow range around \\(m_A'210^-15\\,eV\\).

Ultralight dark matter, such as kinetically mixed dark-photon dark matter (DPDM) or axionlike-particle dark matter (axion DM), can source an oscillating magnetic-field signal at Earth's surface. Previous work searched for this signal in a publicly available dataset of global magnetometer measurements maintained by the SuperMAG collaboration. This \"low-fidelity\" dataset reported measurements with a 1-minute time resolution, allowing the search to set leading direct constraints on DPDM and axion DM with Compton frequencies \\(f_DM1/(1\\,min)\\) [corresponding to masses \\(m_DM710^-17\\,eV\\)]. More recently, a dedicated experiment undertaken by the SNIPE Hunt collaboration has also searched for this same signal at higher frequencies \\(f_DM0.5\\,Hz\\) (or \\(m_DM210^-15\\,eV\\)). In this work, we search for this signal of ultralight DM in the SuperMAG \"high-fidelity\" dataset, which features a 1-second time resolution, allowing us to probe the gap in parameter space between the low-fidelity dataset and the SNIPE Hunt experiment. The high-fidelity dataset exhibits lower geomagnetic noise than the low-fidelity dataset and features more data than the SNIPE Hunt experiment, making it a powerful probe of ultralight DM. Our search finds no robust DPDM or axion DM candidates. We set constraints on DPDM and axion DM parameter space for \\(10^-3\\,Hz f_DM0.98\\,Hz\\) (or \\(410^-18\\,eV m_DM410^-15\\,eV\\)). Our results are the leading direct constraints on both DPDM and axion DM in this mass range, and our DPDM constraint surpasses the leading astrophysical constraint in a narrow range around \\(m_A'210^-15\\,eV\\).

Background: Despite growing evidence on the social determinants of health and health equity, political action has not been commensurate. Little is known about how political will operates to enact pro-equity policies or not. This paper examines how political will for pro-health equity policies is created through analysis of public policy in multiple sectors. Methods: Eight case studies were undertaken of Australian policies where action was either taken or proposed on health equity or where the policy seemed contrary to such action. Telephone or face-to-face interviews were conducted with 192 state and non-state participants. Analysis of the cases was done through thematic analysis and triangulated with document analysis. Results: Our case studies covered: trade agreements, primary healthcare (PHC), work conditions, digital access, urban planning, social welfare and Indigenous health. The extent of political will for pro-equity policies depended on the strength of path dependency, electoral concerns, political philosophy, the strength of economic and biomedical framings, whether elite interests were threatened and the success or otherwise of civil society lobbying. Conclusion: Public health policy actors may create political will through: determining how path dependency that exacerbates health inequities can be broken, working with sympathetic political forces committed to fairness; framing policy options in a way that makes them more likely to be adopted, outlining factors to consider in challenging the interests of elites, and considering the extent to which civil society will work in favour of equitable policies. A shift in norms is required to stress equity and the right to health.

Background The practices of transnational corporations affect population health through production methods, shaping social determinants of health, or influencing the regulatory structures governing their activities. There has been limited research on community exposures to TNC policies and practices. Our pilot research used McDonald’s Australia to test methods for assessing the health impacts of one TNC within Australia. Methods We adapted existing Health Impact Assessment methods to assess McDonald’s activities. Data identifying potential impacts were sourced through document analysis, including McDonald’s corporate literature; media analysis and semi-structured interviews. We commissioned a spatial and socioeconomic analysis of McDonald’s restaurants in Australia through Geographic Information System technology. The data was mapped against a corporate health impact assessment framework which included McDonald’s Australia’s political and business practices; products and marketing; workforce, social, environmental and economic conditions; and consumers’ health related behaviours. Results We identified both positive and detrimental aspects of McDonald’s Australian operations across the scope of the CHIA framework. We found that McDonald’s outlets were slightly more likely to be located in areas of lower socioeconomic status. McDonald’s workplace conditions were found to be more favourable than those in many other countries which reflects compliance with Australian employment regulations. The breadth of findings revealed the need for governments to strengthen regulatory mechanisms that are conducive to health; the opportunity for McDonald’s to augment their corporate social responsibility initiatives and bolster reputational endorsement; and civil society actors to inform their advocacy towards health and equity outcomes from TNC operations. Conclusion Our study indicates that undertaking a corporate health impact assessment is possible, with the different methods revealing sufficient information to realise that strong regulatory frameworks are need to help to avoid or to mediate negative health impacts.

Epidemiological evidence on the social determinants of health inequity is well-advanced, but considerably less attention has been given to evaluating the impact of public policies addressing those social determinants. Methodological challenges to produce evidence on policy outcomes present a significant barrier to mobilising policy actions for health equities. This review aims to examine methodological approaches to policy evaluation of health equity outcomes and identify promising approaches for future research. We conducted a systematic narrative review of literature critically evaluating policy impact on health equity, synthesizing information on the methodological approaches used. We searched and screened records from five electronic databases, using pre-defined protocols resulting in a total of 50 studies included for review. We coded the studies according to (1) type of policy analysed; (2) research design; (3) analytical techniques; (4) health outcomes; and (5) equity dimensions evaluated. We found a growing number of a wide range of policies being evaluated for health equity outcomes using a variety of research designs. The majority of studies employed an observational research design, most of which were cross-sectional, however, other approaches included experimental designs, simulation modelling, and meta-analysis. Regression techniques dominated the analytical approaches, although a number of novel techniques were used which may offer advantages over traditional regression analysis for the study of distributional impacts of policy. Few studies made intra-national or cross-national comparisons or collected primary data. Despite longstanding challenges of attribution in policy outcome evaluation, the majority of the studies attributed change in physical or mental health outcomes to the policy being evaluated. Our review provides an overview of methodological approaches to health equity policy outcome evaluation, demonstrating what is most commonplace and opportunities from novel approaches. We found the number of studies evaluating the impacts of public policies on health equity are on the rise, but this area of policy evaluation still requires more attention given growing inequities.

Background The adverse health and equity impacts of transnational corporations’ (TNCs) practices have become central public health concerns as TNCs increasingly dominate global trade and investment and shape national economies. Despite this, methodologies have been lacking with which to study the health equity impacts of individual corporations and thus to inform actions to mitigate or reverse negative and increase positive impacts. Methods This paper reports on a framework designed to conduct corporate health impact assessment (CHIA), developed at a meeting held at the Rockefeller Foundation Bellagio Center in May 2015. Results On the basis of the deliberations at the meeting it was recommended that the CHIA should be based on ex post assessment and follow the standard HIA steps of screening, scoping, identification, assessment, decision-making and recommendations. A framework to conduct the CHIA was developed and designed to be applied to a TNC’s practices internationally, and within countries to enable comparison of practices and health impacts in different settings. The meeting participants proposed that impacts should be assessed according to the TNC’s global and national operating context; its organisational structure, political and business practices (including the type, distribution and marketing of its products); and workforce and working conditions, social factors, the environment, consumption patterns, and economic conditions within countries. Conclusion We anticipate that the results of the CHIA will be used by civil society for capacity building and advocacy purposes, by governments to inform regulatory decision-making, and by TNCs to lessen their negative health impacts on health and fulfil commitments made to corporate social responsibility.

Background:Insufficient progress has been made towards reducing health inequities, due in part to a lack of action on the root causes of health inequities. At present, there is a limited evidence base to guide policy decision making in this space. Key points for discussion:This paper proposes new principles for researchers to conduct health equity policy evaluation. Four key principles are presented: (1) where to evaluate - shifting from familiar to unfamiliar terrain; (2) who to evaluate - shifting from structures of vulnerability to structures of privilege; (3) what to evaluate - shifting from simple figures to complex constructs; and (4) how to evaluate - shifting from 'gold standard' to more appropriate 'fit-for-purpose' designs. These four principles translate to modifying the policy domains investigated, the populations targeted, the indicators selected, and the methods employed during health equity policy evaluation. The development and implementation of these principles over a five-year programme of work is demonstrated through case studies which reflect the principles in practice. Conclusions and implications:The principles are shared to encourage other researchers to develop evaluation designs of sufficient complexity that they can advance the contribution of health equity policy evaluation to structural policy reforms. As a result, policies and actions on the social determinants of health might be better oriented to achieve the redistribution of power and resources needed to address the root causes of health inequities.

Microrheology, the study of fluids on micron length-scales, promises to reveal insights into cellular biology, including mechanical biomarkers of disease and the interplay between biomechanics and cellular function. Here a minimally-invasive passive microrheology technique is applied to individual living cells by chemically binding a bead to the surface of a cell, and observing the mean squared displacement of the bead at timescales ranging from milliseconds to 100s of seconds. Measurements are repeated over the course of hours, and presented alongside novel analysis to quantify changes in the cells' low-frequency elastic modulus and the cell's dynamics over the time window from around 0.01s to 10s. An analogy to optical trapping allows verification of the invariant viscosity of HeLa S3 cells under control conditions and after cytoskeletal disruption. Stiffening of the cell is observed during cytoskeletal rearrangement in the control case, and cell softening when the actin cytoskeleton is disrupted by Latrunculin B. These data correlate with conventional understanding that integrin binding and recruitment triggers cytoskeletal rearrangement. This is, to our knowledge, the first time that cell stiffening has been measured during focal adhesion maturation, and the longest time over which such stiffening has been quantified by any means.