Suchergebnisse

In this paper, we extend the dynamic spherical cavity expansion model for rate-independent materials developed by Durban and Masri (Int J Solids Struct 41(20):5697-5716, 2004), Masri and Durban (J Appl Mech 72(6):887-898, 2005), and Cohen et al. (J Appl Mech 77(4):041009, 2010) to viscoplastic media. For that purpose, we describe the material behavior with an isotropic Perzyna-type overstress formulation (Perzyna in Q Appl Math 20:321&#-332, 1963; Adv Appl Mech 9:243-377, 1966) in which the material rate dependence is controlled by the viscosity parameter η. The theoretical predictions of the cavity expansion model, which assumes that the cavity expands at constant velocity, are compared with finite element simulations performed in ABAQUS/Explicit (Abaqus Explicit v6.13 User's Manual, ABAQUS Inc., Richmond). The agreement between theory and numerical simulations is excellent for the whole range of cavitation velocities investigated, and for different values of the parameter η. We show that, as opposed to the steady-state self-similar solutions obtained for rate-independent materials (Durban and Masri 2004; Masri and Durban 2005; Cohen et al. 2010), the material viscosity leads to time-dependent cavitation fields and stress relaxation as the cavity enlarges. In addition, we also show that the material viscosity facilitates to model the shock waves that emerge at the highest cavitation velocities investigated, controlling the amplitude and the width of the shock front. ; The research leading to these results has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme. Project PURPOSE, Grant Agreement 758056. RR wishes to acknowledge the support of CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico, grant number 306058/2018-9.

Non-communicable diseases (NCDs) represent the primary cause of morbidity and mortality worldwide. Specific attention needs to be given in fragile and crisis-affected contexts, where health systems have even more difficulties in addressing and managing these diseases. Humanitarian actors intervening in crisis situations increasingly include NCD management in the services they support and provide. This review aims at presenting a series of questions that humanitarian agencies could consider when addressing NCDs in humanitarian crises. They include, among others, what conditions to address and for which target population, how to ensure continuity of care, which guidelines and medications to use, and what can be done beyond classical management of NCDs. Research and evidence are lacking on how to address care effectively for NCDs in emergencies. Therefore, advocacy is needed for NCD-oriented research so as to make interventions more effective and sustainable. No government or single agency can address NCDs in humanitarian crises alone. Strong leadership and partnerships between humanitarian actors, health providers, government bodies, research and academic institutions are required. Only a coordinated multidisciplinary and multi-stakeholder approach will achieve the required impact for affected populations.