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Every year in Australia over a thousand children who are born with congenital heart disease require surgical intervention. Vocal cord dysfunction (VCD) can be an unavoidable and potentially devastating complication of surgery for congenital heart disease. Structured, multidisciplinary care pathways help to guide clinical care and reduce mortality and morbidity. An implementation study was conducted to embed a novel, multidisciplinary management pathway into practice using the consolidated framework for implementation research (CFIR). The goal of the pathway was to prepare children with postoperative vocal cord dysfunction to safely commence and transition to oral feeding. Education sessions to support pathway rollout were completed with clinical stakeholders. Other implementation strategies used included adaptation of the pre-procedural pathway to obtain consent, improving the process of identifying patients on the VCD pathway, and nominating a small team who were responsible for the ongoing monitoring of patients following recruitment. Implementation success was evaluated according to compliance with pathway defined management. Our study found that while there were several barriers to pathway adoption, implementation of the pathway was feasible despite pathway adaptations that were required in response to COVID-19.
Stars lose mass and angular momentum during their lifetimes. Observations of H-alpha absorption of a number of low mass stars, show prominences transiting the stellar disc and being ejected into the extended stellar wind. Analytic modelling have shown these M-dwarf coronal structures growing to be orders of magnitude larger than their solar counterparts. This makes prominences responsible for mass and angular momentum loss comparable to that due to the stellar wind. We present results from a numerical study which used magnetohydrodynamic simulations to model the balance between gravity, magnetic confinement, and rotational acceleration. This allows us to study the time dependent nature of prominence formation. We demonstrate that a prominence, formed beyond the co-rotation radius, is ejected into the extended stellar wind in the slingshot prominence paradigm. Mass, angular momentum flux and ejection frequency have been calculated for a representative cool star, in the so-called Thermal Non-Equilibrium (TNE) regime.
Magnetic confinement of material is observed on both high and low mass stars. On low mass stars, this confinement can be seen as slingshot prominences, in which condensations are supported several stellar radii above the surface by strong magnetic fields. We present a model for generating cooled field lines in equilibrium with the background corona, which we use to populate a model corona. We find prominence masses on the order of observationally derived values. We find two types of solutions: footpoint heavy “solar-like prominences” and summit heavy “slingshot prominences” which are centrifugally supported. These can form within the open field region i.e. embedded in the wind. We generate Hα spectra from different field structures and show that all display behaviour that is consistent with observations. This implies that the features seen in observations could be supported by a range of conditions, suggesting they would be common across rapidly rotating stars.
Wild birds have been the focus of a great deal of research investigating the epidemiology of zoonotic bacteria and antimicrobial resistance in the environment. While enteric pathogens (e.g. Campylobacter, Salmonella, and E. coli O157:H7) and antimicrobial resistant bacteria of public health importance have been isolated from a wide variety of wild bird species, there is a considerable variation in the measured prevalence of a given microorganism from different studies. This variation may often reflect differences in certain ecological and biological factors such as feeding habits and immune status. Variation in prevalence estimates may also reflect differences in sample collection and processing methods, along with a host of epidemiological inputs related to overall study design. Because the generalizability and comparability of prevalence estimates in the wild bird literature are constrained by their methodological and epidemiological underpinnings, understanding them is crucial to the accurate interpretation of prevalence estimates. The main purpose of this review is to examine methodological and epidemiological inputs to prevalence estimates in the wild bird literature that have a major bearing on their generalizability and comparability. The inputs examined here include sample type, microbiological methods, study design, bias, sample size, definitions of prevalence outcomes and parameters, and control of clustering. The issues raised in this review suggest, among other things, that future prevalence studies of wild birds should avoid opportunistic sampling when possible, as this places significant limitations on the generalizability of prevalence data.
The hot Jupiter HD189733b is expected to be a source of strong radio emission, due to its close proximity to its magnetically active host star. Here, we model the stellar wind of its host star, based on reconstructed surface stellar magnetic field maps. We use the local stellar wind properties at the planetary orbit obtained from our models to compute the expected radio emission from the planet. Our findings show that the planet emits with a peak flux density within the detection capabilities of LOFAR. However, due to absorption by the stellar wind itself, this emission may be attenuated significantly. We show that the best time to observe the system is when the planet is near primary transit of the host star, as the attenuation from the stellar wind is lowest in this region.
Communicating about health risks in the Arctic can be challenging. Numerous factors can hinder or promote effective communication. One of the most important components in effective communication is trust in an information source. This is particularly true when a risk is unfamiliar or complex because the public must rely on expert assessment rather than personal evaluation of the risk. A total of 112 Inuit residents from Nunavik, Canada, were interviewed to better understand the factors that influence trust in individuals or organisations. Results indicate that there are six primary factors that influence trust in an information source. These factors include: (1) whether the information source is a friend or family member; (2) past performance of the individual or organisation; (3) the general disposition of the audience member (that is, he or she believes that most people are trustworthy); (4) the openness or candidness of the source; (5) value similarity (referring to the perceived correspondence in values between the audience member and communicator); and (6) the credibility of the source. The results of this study can help determine who or what agencies should provide messages about health risks in the Arctic. It also provides insight about effective strategies for engendering trust among Arctic residents.
The WAIS (West Antarctic Ice Sheet) Divide deep ice core was recently completed to a total depth of 3405 m, ending 50 m above the bed. Investigation of the visual stratigraphy and grain characteristics indicates that the ice column at the drilling location is undisturbed by any large-scale overturning or discontinuity. The climate record developed from this core is therefore likely to be continuous and robust. Measured grain-growth rates, recrystallization characteristics, and grain-size response at climate transitions fit within current understanding. Significant impurity control on grain size is indicated from correlation analysis between impurity loading and grain size. Bubble-number densities and bubble sizes and shapes are presented through the full extent of the bubbly ice. Where bubble elongation is observed, the direction of elongation is preferentially parallel to the trace of the basal (0001) plane. Preferred crystallographic orientation of grains is present in the shallowest samples measured, and increases with depth, progressing to a vertical-girdle pattern that tightens to a vertical single-maximum fabric. This single-maximum fabric switches into multiple maxima as the grain size increases rapidly in the deepest, warmest ice. A strong dependence of the fabric on the impurity-mediated grain size is apparent in the deepest samples.
The proper characterisation of stellar winds is essential for the study of propagation of eruptive events (flares, coronal mass ejections) and the study of space weather events on exoplanets. Here, we quantitatively investigate the nature of the stellar winds surrounding the hot Jupiters HD46375b, HD73256b, HD102195b, HD130322b, HD179949b. We simulate the three-dimensional winds of their host stars, in which we directly incorporate their observed surface magnetic fields. With that, we derive the wind properties at the position of the hot-Jupiters’ orbits (temperature, velocity, magnetic field intensity and pressure). We show that the exoplanets studied here are immersed in a local stellar wind that is much denser than the local conditions encountered around the solar system planets (e.g., 5 orders of magnitude denser than the conditions experienced by the Earth). The environment surrounding these exoplanets also differs in terms of dynamics (slower stellar winds, but higher Keplerian velocities) and ambient magnetic fields (2 to 3 orders of magnitude larger than the interplanetary medium surrounding the Earth). The characterisation of the host star's wind is also crucial for the study of how the wind interacts with exoplanets. For example, we compute the exoplanetary radio emission that is released in the wind-exoplanet interaction. For the hot-Jupiters studied here, we find radio fluxes ranging from 0.02 to 0.13 mJy. These fluxes could become orders of magnitude higher when stellar eruptions impact exoplanets, increasing the potential of detecting exoplanetary radio emission.
Spectropolarimetric observations combined with tomographic imaging techniques have revealed that all pre-main sequence (PMS) stars host multipolar magnetic fields, ranging from strong and globally axisymmetric with ≳kilo-Gauss dipole components, to complex and non-axisymmetric with weak dipole components (≲0.1 kG). Many host dominantly octupolar large-scale fields. We argue that the large-scale magnetic properties of a PMS star are related to its location in the Hertzsprung-Russell diagram. This conference paper is a synopsis of Gregory et al. (2012), updated to include the latest results from magnetic mapping studies of PMS stars.
The habitable zone is the range of orbital distances from a host star in which an exoplanet would have a surface temperature suitable for maintaining liquid water. This makes the orbital distance of exoplanets an important variable when searching for extra-solar Earth analogues. However, the orbital distance is not the only important factor determining whether an exoplanet is potentially suitable for life. The ability of an exoplanet to retain an atmosphere is also vital since it helps regulate surface temperatures. One mechanism by which a planetary atmosphere can be lost is erosion due to a strong stellar wind from the host star. The presence of a magnetosphere can help to shield a planetary atmosphere from this process. Using a simple stellar wind model, we present the impact that stellar winds might have on magnetospheric sizes of exoplanets. This is done with the aim of further constraining the parameter space in which we look for extra-solar Earth analogues.
Asymmetries in exoplanet transits are a useful tool for developing our understanding of magnetic activity on both stars and planets outside our Solar System. Near-UV observations of the WASP-12 system have revealed asymmetries in the timing of the transit when compared with the optical light curve. In this proceedings we review a number of reported asymmetries and present work simulating near-UV transits for the hot-Jupiter hosting star HD 189733.
Recent results showed that the magnetic field of M-dwarf (dM) stars, currently the main targets in searches for terrestrial planets, is very different from the solar one, both in topology as well as in intensity. In particular, the magnetised environment surrounding a planet orbiting in the habitable zone (HZ) of dM stars can differ substantially to the one encountered around the Earth. These extreme magnetic fields can compress planetary magnetospheres to such an extent that a significant fraction of the planet's atmosphere may be exposed to erosion by the stellar wind. Using observed surface magnetic maps for a sample of 15 dM stars, we investigate the minimum degree of planetary magnetospheric compression caused by the intense stellar magnetic fields. We show that hypothetical Earth-like planets with similar terrestrial magnetisation (~1 G) orbiting at the inner (outer) edge of the HZ of these stars would present magnetospheres that extend at most up to 6.1 (11.7) planetary radii. To be able to sustain an Earth-sized magnetosphere, the terrestrial planet would either need to orbit significantly farther out than the traditional limits of the HZ; or else, if it were orbiting within the life-bearing region, it would require a minimum magnetic field ranging from a few G to up to a few thousand G.
Asymmetries in exoplanet transits are proving to be a useful tool for furthering our understanding of magnetic activity on both stars and planets outside our Solar System. Near-UV observations of the WASP- 12 system have revealed asymmetries in the timing of the transit when compared with the optical light curve. In this paper we review a number of reported asymmetries and present work simulating near-UV transits for the hot-Jupiter hosting star HD 189733.
The steady increase of the sample of know extrasolar planets broadens our knowledge and at the same time, reveals our lack of understanding. Habitability is a wide expression, needing planet formation theory and microphysics of cloud formation at the same time. The habitability of a planet depends, amongst other things, on how much radiation reached the ground and how much of potentially dangerous radiation is absorbed on the way through the atmosphere. For this, we need to understand cloud formation and it's impact on the atmosphere.
We have studied the formation of mineral clouds on planetary atmospheres by a kinetic approach which allows us to predict the size distribution and material composition of the cloud particles. With these results we show that mineral cloud particles can be electrically charged and at which point inside a cloud charge separation will cause an electric field breakdown. Such streamer processes result in an extreme increase of the local number of free charges. Given the strong magnetic field in Brown Dwarfs and maybe in giant gas planets, these charges will than be accelerated upward out of the atmosphere where they become detectable as radio emission.
Here, we summarise the conditions that might lead to the formation of a bow shock surrounding a planet's magnetosphere. Such shocks are formed as a result of the interaction of a planet with its host star wind. In the case of close-in planets, the shock develops ahead of the planetary orbit. If this shocked material is able to absorb stellar radiation, the shock signature can be revealed in (asymmetric) transit light curves. We propose that this is the case of the gas giant planet WASP-12b, whose near-UV transit observations have detected the presence of an extended material ahead of the planetary orbit. We show that shock detection through transit observations can be a useful tool to constrain planetary magnetic fields.
Magnetic fields of cool stars can be directly investigated through the study of the Zeeman effect on photospheric spectral lines using several approaches. With spectroscopic measurement in unpolarised light, the total magnetic flux averaged over the stellar disc can be derived but very little information on the field geometry is available. Spectropolarimetry provides a complementary information on the large-scale magnetic topology. With Zeeman-Doppler Imaging (ZDI), this information can be retrieved to produce a map of the vector magnetic field at the surface of the star, and in particular to assess the relative importance of the poloidal and toroidal components as well as the degree of axisymmetry of the field distribution.
The development of high-performance spectropolarimeters associated with multi-lines techniques and ZDI allows us to explore magnetic topologies throughout the Hertzsprung-Russel diagram, on stars spanning a wide range of mass, age and rotation period. These observations bring novel constraints on magnetic field generation by dynamo effect in cool stars. In particular, the study of solar twins brings new insight on the impact of rotation on the solar dynamo, whereas the detection of strong and stable dipolar magnetic fields on fully convective stars questions the precise role of the tachocline in this process.
An understanding of the energy transfer that takes place during magnetic reconnection is crucial to the study of this fundamental process. It depends on two factors: the type of reconnection regime (which is determined by the boundary conditions) and the degree of compressibility. Here we examine the role of compressibility in the energetics of a family of reconnection models. When the inflow Mach number (or reconnection rate) Me is small the effects of compressibility may be more important than the differences between regimes. We find that for a slow-compression regime with Me = 0·005 compressibility decreases by 39% the efficiency of the shocks in converting magnetic energy and increases by 14% the ratio of thermal to kinetic energy in the outflow jet. This compares with a 13% decrease in the shock efficiency and a 7% decrease in the jet ratio obtained by choosing instead a flux-pile-up regime. As Me is increased, however, the differences between regimes become larger and may be comparable to or greater than the effects of compressibility. Thus when the above Mach number is doubled we find that a change of regime now has 1–6 times the effect on the jet energy ratio as the introduction of compressibility. For those regimes, therefore, which only exist at low inflow Mach numbers, compressibility will always be important. At higher values of Me the type of regime may be the dominant factor governing the energetics.
We investigate the effects of compressibility on magnetic reconnection, using as a basis the incompressible models of Priest & Forbes and Jardine & Priest. Our results show that compressibility modifies the reconnection process, without changing its essential character. In the region of inflowing plasma, compressibility tends to increase the convergence or divergence of the flow. Also, for regimes with a compression in the inflow the maximum rate of reconnection is increased, while for regimes with an expansion in the inflow the magnetic Mach number at the entrance to the diffusion region is increased. In the region of outflowing plasma the main effects of compressibility are to produce faster and narrower outflow jets, with a lower magnetic field strength.
We examine the global energetics of a recent weakly nonlinear theory of fast steady-state reconnection in an incompressible plasma (Jardine & Priest 1988). This is itself an extension to second order of the Priest & Forbes (1986) family of models, of which Petschek-like and Sonnerup-like solutions are special cases. While to first order we find that the energy conversion is insensitive to the type of solution (such as slow compression or flux pile-up), to second order not only does the total energy converted vary but so also does the ratio of the thermal to kinetic energies produced. For a slow compression with a strongly converging flow, the amount of energy converted is greatest and is dominated by the thermal contribution, while for a flux pile-up with a strongly diverging flow, the amount of energy converted is smallest and is dominated by the kinetic contribution. We also find that the total energy flowing out of the downstream region can be increased either by increasing the external magnetic Mach number Me or the external plasma beta βe Increasing Me also enhances the variations between different types of solutions.
A family of three-dimensional models of reconnection is presented in which the different members of the family are characterized by the vorticity with which plasma flows towards the reconnection site. The nature of this inflow also determines the size and speed of the outflow jet that carries reconnected field lines away from the reconnection site, and the shape of the MHD shocks that bound it. Flows with positive vorticity are of a flux pile-up type, for which the outflow jet is fastest and narrowest. Among those with negative vorticity is the three-dimensional analogue of Petschek reconnection. Not all combinations of vorticity and reconnection rate are possible; for those solutions with negative vorticity, there is a maximum reconnection rate. As the magnetic Reynolds number Rme or the current density is increased, this maximum is reduced and the possible types of solution become more polarized towards the two extremes of flux pile-up and slow compression regimes. Given a distribution of vorticities and inflow speeds, these models give the corresponding distribution of possible steady-state reconnection rates. As an illustrative example, we take Gaussian distributions of both to show that the resulting distribution is dominated by the flux pile-up regime.