Numerical study on the influence of boundary conditions on the blast response of composite plates

Blast loading represents a critical dynamic condition for both metal and composite structures. The blast response of metal materials has been extensively dealt with by researchers through experimental, analytical and numerical analyses, while composite materials appear to have been investigated in less detail. In this work, the blast response of a composite plate is numerically investigated employing the pure Lagrangian and the fully coupled Eulerian-Lagrangian (CEL) approaches using the LS-DYNA® software package. The latter methodology is set up to describe the effects determined by close-range explosions, such as the strongly non-uniform pressure distribution on the plate exposed area. Moreover, this work focuses on the characterisation of the influence of the boundary conditions on the plate response. The numerical methodology established in this work is set up and validated according to similar studies present in the literature

Damage assessment of CFRP laminate plate subjected to close-range blast loading: hydrocode methodology validation and case study

Blast loading represents a critical damaging event in all structures. Although composite materials have been increasingly adopted in structural application, the effect of such dynamic loading event on composite structures is still to be evaluated in detail. This work defines a reliable numerical methodology to assess the damage occurring in carbon fiber reinforced polymer (CFRP) plate subjected to close-range blast loading. The numerical methodology is validated with a benchmark experiment found in literature and is employed to study in detail the damage mechanisms and eventual Fluid Structure Interaction (FSI) effects. The numerical analyses are carried out through a commercially available software package employing two methods, i.e., the ConWep and the hybrid coupled Eulerian-Lagrangia (CEL)-ConWep approaches, and the results from the simulations are compared with experimental evidence from the original work. The results show that (i) the hybrid approach seems to be a promising solution in terms of efficiency and accuracy in modelling blast events, (ii) the ConWep approach accurately reproduces experimental observations, even though such a method has strong limitations. (C) 2022 The Authors. Published by Elsevier B.V

Global public health policies: gathering public health associations' perspectives

Background Advocacy is one of the core functions of public health and is a key tool for achieving Sustainable Development Goals. Public health associations play a key role in advocating for the development and implementation of strategies to prevent diseases and promote health and well-being. Objective This study aims to map out the focus of public health advocacy carried out by selected national public health associations over 4 years, between 2018 and 2021, in order to identify gaps and strengths and support associations and professionals in their advocacy efforts. Methods Twelve national public health associations participated in the study. Official policy documents produced between 2018 and 2021 were collected and analysed. The title and summary of the policy documents were examined line by line and coded into the main subject categories and themes. A qualitative thematic analysis was conducted. Policies were assessed from global and regional perspectives. Results A total of 220 policy documents were analysed. Overall, the largest number of policy documents came from high-income countries and dealt with environmental health and communicable diseases, including COVID-19, with, however, important differences among regions. In the African region, public health advocacy focused mainly on strengthening health systems; Europe and South America were mostly concerned with communicable diseases and pandemic management; and North America and the Western Pacific regions focused primarily on climate change. Limited attention was paid to international health and health as a human right in all regions. Conclusion Our study showed that, especially in high-income countries, public health associations actively engage in advocacy; however, more effort needs to be devoted to implementing a more international and intersectoral approach at the global level, anchored in health as a human right and aligned with the Sustainable Development Goals

Sleep-Deprivation Regulates α-2 Adrenergic Responses of Rat Hypocretin/Orexin Neurons

We recently demonstrated, in rat brain slices, that the usual excitation by noradrenaline (NA) of hypocretin/orexin (hcrt/orx) neurons was changed to an inhibition following sleep deprivation (SD). Here we describe that in control condition (CC), i.e. following 2 hours of natural sleep in the morning, the α2-adrenergic receptor (α2-AR) agonist, clonidine, had no effect on hcrt/orx neurons, whereas following 2 hours of SD (SDC), it hyperpolarized the neurons by activating G-protein-gated inwardly rectifying potassium (GIRK) channels. Since concentrations of clonidine up to a thousand times (100 µM) higher than those effective in SDC (100 nM), were completely ineffective in CC, a change in the availability of G-proteins is unlikely to explain the difference between the two conditions. To test whether the absence of effect of clonidine in CC could be due to a down-regulation of GIRK channels, we applied baclofen, a GABAB agonist known to also activate GIRK channels, and found that it hyperpolarized hcrt/orx neurons in that condition. Moreover, baclofen occluded the response to clonidine in SDC, indicating that absence of effect of clonidine in CC could not be attributed to down-regulation of GIRK channels. We finally tested whether α2-ARs were still available at the membrane in CC and found that clonidine could reduce calcium currents, indicating that α2-ARs associated with calcium channels remain available in that condition. Taken together, these results suggest that a pool of α2-ARs associated with GIRK channels is normally down-regulated (or desensitized) in hcrt/orx neurons to only become available for their inhibition following sleep deprivation

Custom Made Candy Plug for Distal False Lumen Occlusion in Aortic Dissection: International Experience

Objective: To evaluate early and midterm outcomes of the Candy Plug (CP) technique for distal false lumen (FL) occlusion in thoracic endovascular aortic repair for aortic dissection (AD) in a more real world cohort of patients from an international multicentre registry. Methods: A multicentre retrospective study was conducted of all consecutive patients from the contributing centres with subacute and chronic AD treated with the CP technique from October 2013 to April 2020 at 18 centres. Results: A custom made CP was used in 155 patients (92 males, mean age 62 ± 11 years). Fourteen (9%) presented with ruptured false lumen aneurysms. Technical success was achieved in all patients (100%). Clinical success was achieved in 138 patients (89%). The median hospital stay was 7 days (1 – 77). The 30 day mortality rate was 3% (n = 5). Stroke occurred in four patients (3%). Spinal cord ischaemia occurred in three patients (2%). The 30 day computed tomography angiogram (CTA) confirmed successful CP placement at the intended level in all patients. Early complete FL occlusion was achieved in 120 patients (77%). Early (30 day) CP related re-intervention was required in four patients (3%). The early (30 day) stent graft related re-intervention rate was 8% (n = 12). Follow up CTA was available in 142 patients (92%), with a median follow up of 23 months (6 – 87). Aneurysmal regression was achieved in 68 of 142 patients (47%); the aneurysm diameter remained stable in 69 of 142 patients (49%) and increased in five of 142 patients (4%). A higher rate of early FL occlusion was detected in the largest volume centre patients (50 [88%] vs. 70 [71%] from other centres; p = .019). No other differences in outcome were identified regarding volume of cases or learning curve. Conclusion: This international CP technique experience confirmed its feasibility and low mortality and morbidity rates. Aortic remodelling and false lumen thrombosis rates were high and support the concept of distal FL occlusion in AD using the CP technique

Analysis of the blast wave – structure interface phenomenon in case of explosive events

Several structures need their response to blast loads to be investigated to grant an acceptable survivability level. To this purpose, experimental campaigns are complex, but some numerical methods are commonly exploited. The explosion pressure-time history is typically estimated characterizing the detonation of an energetically equivalent explosion involving the detonation of a specific amount of TNT. The pressure-time history at a point, fixed in space, involved by the blast wave is described by the Friedlander equation. A specific approach to modelling the complex blast wave-target structure coupling is reported in the UFC 3-340-02. This method, although consolidated and valid for aerospace, civil and mechanical structure, is not adopted in predictive simulations, which involve naive methods for characterizing that interface phenomenon. This work aims to give an insight on the blast wave-structure interaction event. A methodological approach combining the Friedlander equation and the theory reported in the UFC 3-340-02 is presented, which confidently characterizes the effects of explosive loads on common structures. This fully analytical method may be implemented into numerical codes to perform simple, but effective, preliminary characterizations of the structural response to explosive loads. Finally, a possible application of the proposed method to thin-walled structures is shown