Granular dynamics of cohesive powders in a rotating drum as revealed by speckle visibility spectroscopy and synchronous measurement of forces due to avalanching

We have used speckle visibility spectroscopy (SVS) and synchronized force measurements to compare the granular dynamics of two cohesive lactose powders, with Sauter mean diameters of ~29 and ~151 μm, in a rotating drum. A load cell (LC) was used to measure forces on the drum mounting frame and enable monitoring of bulk powder motion; SVS is a dynamic light scattering technique particularly suited for studying dynamics in dense, non-ergodic granular systems. Our results reveal that surface slumping and intermittent collisional dynamics in the bulk of the bed are correlated, especially for the fine more cohesive particles (Geldart group C/A boundary), but not as much for the less cohesive larger particles (Geldart group A/B boundary). The specific dissipation energy of the particles in the drum is similar for both powders, and increases linearly with increasing drum speed. However, the dependencies of the load cell and SVS signals on rotation speed have opposing trends for these two powders, indicating different dissipation mechanisms for the different Geldart Groups; collisional dissipation is more important for the Geldart C/A powder, while for the Geldart A/B powder avalanche dissipation is dominant

Projecting the future: modelling Australian dialysis prevalence 2021–30

To project the prevalence of people receiving dialysis in Australia for 2021–30 to inform service planning and health policy. Methods. Estimates were based on data from 2011 to 2020 from the Australia & New Zealand Dialysis & Transplant (ANZDATA) Registry and the Australian Bureau of Statistics. We projected dialysis and functioning kidney transplant recipient populations for the years 2021–30. Discrete-time, non-homogenous Markov models were built on probabilities for transition between three mutually exclusive states (Dialysis, Functioning Transplant, Death), for five age groups. Two scenarios were employed – stable transplant rate vs a continued increase – to assess the impact of these scenarios on the projected prevalences. Results. Models projected a 22.5–30.4% growth in the dialysis population from 14 554 in 2020 to 17 829 (‘transplant growth’) – 18 973 (‘transplant stable’) by 2030. An additional 4983–6484 kidney transplant recipients were also projected by 2030. Dialysis incidence per population increased and dialysis prevalence growth exceeded population ageing in 40–59 and 60–69 year age groups. The greatest dialysis prevalence growth was seen among those aged ≥70 years. Conclusion. Modelling of the future prevalence of dialysis use highlights the increasing demand on services expected overall and especially by people aged ≥70 years. Appropriate funding and healthcare planning must meet this demand.Dominic Keuskamp, Christopher E. Davies, Georgina L. Irish, Shilpanjali Jesudason and Stephen P. McDonal

The demography and dynamics of an expanding, managed African wild dog metapopulation

Long-term demographic data are central for the evaluation of endangered species recovery plans. We present the demography and dynamics of a managed African wild dog (Lycaon pictus) metapopulation in South Africa, based on life histories of 553 individually known animals collected between 1998 and 2006. This metapopulation, distributed across nine sites (and not including Kruger National Park), was established through reintroductions (n = 9 events) and maintained by periodic augmentation (n = 10 events) and translocation (n = 20 events). In total, 66 founders were used to establish subpopulations and mean founder group size was 9.6 animals. The metapopulation grew from17 individuals in 1998 to a peak of 202 in 2005. Mean annual population density was 3.3 (S.E. 0.44) wild dogs/100 km2, approaching the upper limit of densities reported from unmanaged populations. Mean size of breeding packs was 11.0 (S.E. 0.76), comparable to pack sizes in Kruger National Park (Kruger), the only viable unmanaged population in South Africa. Fecundity was lower than in Kruger – particularly in the older age classes. Pup survival to adulthood was 45% – nearly three times the survival rate for pups in Kruger.Mean annual population growth rate (ë = 1.08, S.E. 0.13) was higher than in unmanaged populations (range 1.000–1.038), with implications for population viability and management.H.D.M. was supported through grants to D.W.M. from Fauna & Flora International and Siren. Fieldwork was supported by the Endangered Wildlife Trust, De Beers Consolidated Mines and Jaguar Land Rover South Africa.http://www.sawma.co.zaam201