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In this essay, we discuss the under-representation of women in leadership positions in global health (GH) and the importance of mentorship to advance women's standing in the field. We then describe the mentorship model of GROW, Global Research forWomen. We describe the theoretical origins of the model and an adapted theory of change explaining how the GROW model for mentorship advances women's careers in GH. We present testimonials from a range of mentees who participated in a pilot of the GROW model since 2015. These mentees describe the capability-enhancing benefits of their mentorship experience with GROW. Thus, preliminary findings suggest that the GROWmentorship model is a promising strategy to build women's leadership in GH. We discuss supplemental strategies under consideration and next steps to assess the impact of GROW, providing the evidence to inform best practices for curricula elsewhere to build women's leadership in GH. [ABSTRACT FROM AUTHOR]

Many models for slurry transport exist. Usually the models describe one of the 5 main flow regimes: fixed or stationary bed transport; sliding bed transport; heterogeneous transport; homogeneous transport and sliding flow transport. The transition between these flow regimes is seldom described, as well as the difference between spatial and delivered concentration and the behavior of graded sands or gravels. A framework is described connecting the different flow regimes. Additional models for; the limit deposit velocity, the holdup function, the bed height, the concentration distribution and graded sands and gravels, complete the framework. The framework is based on constant spatial volumetric concentration curves for uniform sands and gravels. The models for the flow regimes and the limit deposit velocity are based on energy considerations. By means of a holdup function, the constant spatial volumetric concentration curves can be transformed into constant delivered volumetric concentration curves. Curves for graded sands and gravels can be constructed by splitting the particle size distribution (PSD) into fractions and use the superposition principle on the resulting curves of each fraction. The framework is validated with many experiments from literature. [ABSTRACT FROM AUTHOR]

Two regimes can be distinguished for the pickup flux of sand. At a Shields parameter of less than about 0.5 (corresponding with flow velocities of 0.5-1 m=s), the erosion process is dominated by the size and density of the grains (grain by grain pickup). At higher flow velocities, the bulk properties of the sand bed start to influence the erosion process. Dilative behavior results in the inflow of water to the sand bed, which reduces the pickup flux (dilatancy-reduced pickup) because of the shearing of layers of sand. A pickup function was recently developed for this regime, incorporating the effect of bulk properties, such as permeability and porosity, on the pickup. This function agrees well with data of previous erosion experiments in which the permeability and porosity of the sand bed were varied. However, these experiments just met the condition for dilatancy-reduced pickup. The flow velocity during these previous experiments was between 1 and 1.5 m=s, while the Shields parameter varied between 1 and 2. In order to validate this pickup function for dike breaching and jetting of sand, during which the flow velocity ranges within 5-50 m=s, erosion experiments were executed at higher flow velocities. These experiments were executed in an adapted closed flume of the slurry circuit of the Dredging Research Laboratory at the Delft University of Technology (DUT) at flow velocities of 2-6 m=s (Shields parameter is between 50 and 1,000). The results of these experiments are consistent with the theory of dilatancy-reduced pickup. The porosity of the sand bed influences the erosion process, especially at flow velocities of more than 4 m=s bulk property. [ABSTRACT FROM AUTHOR]