Pandemic preparedness systems and diverging COVID-19 responses within similar public health regimes: a comparative study of expert perceptions of pandemic response in Denmark, Norway, and Sweden.

BACKGROUND: National responses to the COVID-19 pandemic depend on national preparedness systems that must be understood as components of global public health emergency preparedness systems, governed and coordinated through the World Health Organization's 2005 International Health Regulations. The pandemic has raised the question of why countries belonging to similar public health regimes, coordinated through the same global system, responded differently to the same threat. Comparing the responses of Denmark, Sweden and Norway, countries with similar public health regimes, the paper investigates to what degree national differences in COVID-19 policy response reflect significant differences in the policy preferences of national expert groups. RESULTS: We employ a structured case comparison of Denmark, Norway, and Sweden to analyze their' politico-administrative pandemic preparedness systems and policy responses during the first wave of the COVID-19 pandemic. We use the results of an interdisciplinary expert survey completed in 2020 to analyze expert perceptions in two ways. First, we analyze expert perceptions of COVID-19 responses while controlling for national COVID-19 trajectories and experts' characteristics. Second, we analyze the distribution and effect of dominant global expert-held ideas across countries, showing the importance of dominant ideas for experts' perceptions and preferences for COVID-19 response. CONCLUSION: The study finds no evidence indicating that COVID-19 policy variation between the most similar cases of Denmark, Norway, and Sweden are the result of differences in the policy preferences of national expert groups. Instead, our study highlights the importance of other factors than cross-national expert dissensus for explaining variation in pandemic response such as the politico-administrative organization of pandemic preparedness systems. Further, we find that expert support for dominant ideas such as a 'focused protection strategy' is associated with consistent policy preferences across locational, disciplinary, and geographic affiliations. Recognition of the latter should be a part of future discussions about how global ideas of pandemic preparedness are diffused transnationally and embedded in national politico-administrative systems.

Fast core rotation in red-giant stars as revealed by gravity-dominated mixed modes.

When the core hydrogen is exhausted during stellar evolution, the central region of a star contracts and the outer envelope expands and cools, giving rise to a red giant. Convection takes place over much of the star's radius. Conservation of angular momentum requires that the cores of these stars rotate faster than their envelopes; indirect evidence supports this. Information about the angular-momentum distribution is inaccessible to direct observations, but it can be extracted from the effect of rotation on oscillation modes that probe the stellar interior. Here we report an increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants, obtained using the rotational frequency splitting of recently detected 'mixed modes'. By comparison with theoretical stellar models, we conclude that the core must rotate at least ten times faster than the surface. This observational result confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior.

Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars.

Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies. Here we report observations of gravity-mode period spacings in red giants that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly ∼ 50 seconds) and those that are also burning helium (period spacing ∼ 100 to 300 seconds).