Educating renal nurses - inferior vena caval ultrasound for intravascular volume assessment

Aim: Volume status of haemodialysis patients can be evaluated by trained doctors using ultrasound (US) of the inferior vena cava (IVC). To date, renal nurses have not been taught this skill. As part of a larger study exploring the use of US by renal nurses we developed an educational program to ensure that renal nurses received adequate US training to attain competence in IVC ultrasound (IVC-US). Methods: The educational program was divided into four parts. Initially a clinical US expert delivered the necessary theoretical and then practical components of the program. After this the nurse undertook a period of self-directed US practice (100 scans). During this period three formative reviews of the recorded scan clips with feedback occurred. Specific feedback covered US technique, image optimisation and acquisition and image interpretation. Finally, as a summative assessment the nurse performed and interpreted 60 scans on 10 dialysis patients. These scans were independently assessed for quality and the nurse interpretations reviewed for accuracy, prior to deeming the candidate competent to independently perform IVC-US. Findings: Ultrasound education involves knowledge and skill acquisition. Initial theoretical and practical education must be translated into competence through task repetition and targeted feedback. A staged educational program that involves these components is likely to be successful. The rate for US skill acquisition varies and a summative assessment ensuring competence prior to independent scanning is important. Conclusions: This four-step program demonstrated that it is feasible to educate a renal nurse in IVC-US for intravascular volume assessment

Driving galactic outflows with magnetic fields at low and high redshift

Although galactic outflows play a key role in our understanding of the evolution of galaxies, the exact mechanism by which galactic outflows are driven is still far from being understood and, therefore, our understanding of associated feedback mechanisms that control the evolution of galaxies is still plagued by many enigmas. In this work, we present a simple toy model that can provide insight on how non-axisymmetric instabilities in galaxies (bars, spiral arms, warps) can lead to local exponential magnetic field growth by radial flows beyond the equipartition value by at least two orders of magnitude on a timescale of a few 100 Myr. Our predictions show that the process can lead to galactic outflows in barred spiral galaxies with a mass-loading factor η ≈ 0.1, in agreement with our numerical simulations. Moreover, our outflow mechanism could contribute to an understanding of the large fraction of barred spiral galaxies that show signs of galactic outflows in the CHANG-ES survey. Extending our model shows the importance of such processes in high-redshift galaxies by assuming equipartition between magnetic energy and turbulent energy. Simple estimates for the star formation rate in our model together with cross correlated masses from the star-forming main sequence at redshifts z ∼ 2 allow us to estimate the outflow rate and mass-loading factors by non-axisymmetric instabilities and a subsequent radial inflow dynamo, giving mass-loading factors of η ≈ 0.1 for galaxies in the range of M⋆ = 109–1012 M⊙, in good agreement with recent results of SINFONI and KMOS3D

On the origin of magnetic driven winds and the structure of the galactic dynamo in isolated galaxies

We investigate the build-up of the galactic dynamo and subsequently the origin of a magnetic driven outflow. We use a set-up of an isolated disc galaxy with a realistic circum-galactic medium (CGM). We find good agreement of the galactic dynamo with theoretical and observational predictions from the radial and toroidal components of the magnetic field as function of radius and disc scale height. We find several field reversals indicating dipole structure at early times and quadrupole structure at late times. Together with the magnetic pitch angle and the dynamo control parameters Rα, Rω, and D, we present strong evidence for an α2–Ω dynamo. The formation of a bar in the centre leads to further amplification of the magnetic field via adiabatic compression which subsequently drives an outflow. Due to the Parker instability the magnetic field lines rise to the edge of the disc, break out, and expand freely in the CGM driven by the magnetic pressure. Finally, we investigate the correlation between magnetic field and star formation rate. Globally, we find that the magnetic field is increasing as function of the star formation rate surface density with a slope between 0.3 and 0.45 in good agreement with predictions from theory and observations. Locally, we find that the magnetic field can decrease while star formation increases. We find that this effect is correlated with the diffusion of magnetic field from the spiral arms to the interarm regions which we explicitly include by solving the induction equation and accounting for non-linear terms

The challenge of simulating the star cluster population of dwarf galaxies with resolved interstellar medium

We present results on the star cluster properties from a series of high resolution smoothed particles hydrodynamics (SPH) simulations of isolated dwarf galaxies as part of the griffin project. The simulations at sub-parsec spatial resolution and a minimum particle mass of 4 M⊙ incorporate non-equilibrium heating, cooling, and chemistry processes, and realize individual massive stars. The simulations follow feedback channels of massive stars that include the interstellar-radiation field variable in space and time, the radiation input by photo-ionization and supernova explosions. Varying the star formation efficiency per free-fall time in the range ϵff = 0.2–50 per cent neither changes the star formation rates nor the outflow rates. While the environmental densities at star formation change significantly with ϵff, the ambient densities of supernovae are independent of ϵff indicating a decoupling of the two processes. At low ϵff, gas is allowed to collapse more before star formation, resulting in more massive, and increasingly more bound star clusters are formed, which are typically not destroyed. With increasing ϵff, there is a trend for shallower cluster mass functions and the cluster formation efficiency Γ for young bound clusters decreases from 50 per cent to ∼1 per cent showing evidence for cluster disruption. However, none of our simulations form low mass (3 M⊙) clusters with structural properties in perfect agreement with observations. Traditional star formation models used in galaxy formation simulations based on local free-fall times might therefore be unable to capture star cluster properties without significant fine tuning