A Generalized Diffusion Tensor for Fully Anisotropic Diffusion of Energetic Particles in the Heliospheric Magnetic Field

The spatial diffusion of cosmic rays in turbulent magnetic fields can, in the most general case, be fully anisotropic, i.e. one has to distinguish three diffusion axes in a local, field-aligned frame. We reexamine the transformation for the diffusion tensor from this local to a global frame, in which the Parker transport equation for energetic particles is usually formulated and solved. Particularly, we generalize the transformation formulas to allow for an explicit choice of two principal local perpendicular diffusion axes. This generalization includes the 'traditional' diffusion tensor in the special case of isotropic perpendicular diffusion. For the local frame, we motivate the choice of the Frenet-Serret trihedron which is related to the intrinsic magnetic field geometry. We directly compare the old and the new tensor elements for two heliospheric magnetic field configurations, namely the hybrid Fisk and the Parker field. Subsequently, we examine the significance of the different formulations for the diffusion tensor in a standard 3D model for the modulation of galactic protons. For this we utilize a numerical code to evaluate a system of stochastic differential equations equivalent to the Parker transport equation and present the resulting modulated spectra. The computed differential fluxes based on the new tensor formulation deviate from those obtained with the 'traditional' one (only valid for isotropic perpendicular diffusion) by up to 60% for energies below a few hundred MeV depending on heliocentric distance.Comment: 8 pages, 6 figures, accepted in Ap

The effects of a kappa-distribution in the heliosheath on the global heliosphere and ENA flux at 1 AU

We investigate heliosheath energetic neutral atom (ENA) fluxes at keV energies, by assuming that the heliosheath proton distribution can be approximated by a kappa-distribution. The choice of the kappa parameter derives from observational data of the solar wind (SW). This has direct applications to the upcoming IBEX mission. We will look at all-sky ENA maps within the IBEX energy range (10 eV to 6 keV), as well as ENA energy spectra in several directions. We find that the use of kappa, as opposed to a Maxwellian, gives rise to greatly increased ENA fluxes above 1 keV, while medium energy fluxes are somewhat reduced. We show how IBEX data can be used to estimate the spectral slope in the heliosheath, and that the use of kappa reduces the differences between ENA maps at different energies. We also investigate the effect introducing a kappa-distribution has on the global interaction between the SW and the local interstellar medium (LISM), and find that there is generally an increase in energy transport from the heliosphere into the LISM, due to the modified profile of ENA's energies. This results in a termination shock that moves out by 4 AU, a heliopause that moves in by 9 AU and a bow shock 25 AU farther out, in the nose direction

Minimal Holocene retreat of large tidewater glaciers in Køge Bugt, southeast Greenland

Abstract Køge Bugt, in southeast Greenland, hosts three of the largest glaciers of the Greenland Ice Sheet; these have been major contributors to ice loss in the last two decades. Despite its importance, the Holocene history of this area has not been investigated. We present a 9100 year sediment core record of glaciological and oceanographic changes from analysis of foraminiferal assemblages, the abundance of ice-rafted debris, and sortable silt grain size data. Results show that ice-rafted debris accumulated constantly throughout the core; this demonstrates that glaciers in Køge Bugt remained in tidewater settings throughout the last 9100 years. This observation constrains maximum Holocene glacier retreat here to less than 6 km from present-day positions. Retreat was minimal despite oceanic and climatic conditions during the early-Holocene that were at least as warm as the present-day. The limited Holocene retreat of glaciers in Køge Bugt was controlled by the subglacial topography of the area; the steeply sloping bed allowed glaciers here to stabilise during retreat. These findings underscore the need to account for individual glacier geometry when predicting future behaviour. We anticipate that glaciers in Køge Bugt will remain in stable configurations in the near-future, despite the predicted continuation of atmospheric and oceanic warming

Pressure ulcers in palliative ward patients: hyponatremia and low blood pressure as indicators of risk

Danuta Sternal,1 Krzysztof Wilczyński,2 Jan Szewieczek2 1Department of Nursing and Paramedical Sciences, Faculty of Health Sciences, University of Bielsko-Biala, Bielsko-Biala, 2Department of Geriatrics, School of Health Sciences in Katowice, Medical University of Silesia, Katowice, Poland Background: Prevention strategies for pressure ulcer formation remain critical in patients with an advanced illness. We analyzed factors associated with the development of pressure ulcers in patients hospitalized in a palliative care ward setting.Patients and methods: This study was a retrospective analysis of 329 consecutive patients with a mean age (± standard deviation) of 70.4±11.8 years (range: 30–96 years, median 70.0 years; 55.3% women), who were admitted to the Palliative Care Department between July 2012 and May 2014.Results: Patients were hospitalized for mean of 24.8±31.4 days (1–310 days, median 14 days). A total of 256 patients (77.8%) died in the ward and 73 patients (22.2%) were discharged. Two hundred and six patients (62.6%) did not develop pressure ulcers during their stay in the ward, 84 patients (25.5%) were admitted with pressure ulcers, and 39 patients (11.9%) developed pressure ulcers in the ward. Four factors assessed at admission appear to predict the development of pressure ulcers in the multivariate logistic regression model: Waterlow score (odds ratio [OR] =1.140, 95% confidence interval [CI] =1.057–1.229, P=0.001), transfer from other hospital wards (OR =2.938, 95% CI =1.339–6.448, P=0.007), hemoglobin level (OR =0.814, 95% CI =0.693–0.956, P=0.012), and systolic blood pressure (OR =0.976, 95% CI =0.955–0.997, P=0.023). Five other factors assessed during hospitalization appear to be associated with pressure ulcer development: mean evening body temperature (OR =3.830, 95% CI =1.729–8.486, P=0.001), mean Waterlow score (OR =1.194, 95% CI =1.092–1.306, P<0.001), the lowest recorded sodium concentration (OR =0.880, 95% CI =0.814–0.951, P=0.001), mean systolic blood pressure (OR =0.956, 95% CI =0.929–0.984, P=0.003), and the lowest recorded hemoglobin level (OR =0.803, 95% CI =0.672–0.960, P=0.016).Conclusion: Hyponatremia and low blood pressure may contribute to the formation of pressure ulcers in patients with an advanced illness. Keywords: pressure ulcers, palliative care, advanced illness, Waterlow score, hyponatremia, blood pressur

Calculation of the energetic neutral atom flux from a 3D time-dependent model heliosphere

With the Interstellar Boundary Explorer (IBEX) the measurement of energetic neutral atoms (ENAs) will enable a remote sensing of the heliospheric boundary region where the solar wind plasma flow meets the interstellar medium. Together with Voyager 1 (& 2) in (and at least near) the healiosheath there will be a very fortunate instrument configuration in space that will allow us to obtain valuable information about the large-scale structure and dynamics of the heliosphere. Following ongoing theoretical discussions we have computed all-sky maps of the differential flux of ENAs produced from charge exchange with solar wind protons in a three-dimensionally structured and time-varying heliosheath. We employ a three-dimensional, time-dependent hydrodynamic model heliosphere to compute the production of ENAs by a generalisation of previous two-dimensional approaches. We find three-dimensionally structured all-sky ENA flux maps that are time-varying due to the solar activity cycle. While the study adds to the complexity of the task to correctly interpret the forthcoming measurements to be made with IBEX, it underlines the potential of this mission to significantly increase our understanding of the structure and dynamics of the heliosphere