RESUMEN
Increasing resource efficiency and reducing the energy consumption of cloud data centers is critical, especially during the global CORONA virus pandemic. Virtual machines' consolidation using live migration maximizes the hosts' and the reduction of energy consumption. An increase in the host's virtual machines in the consolidation process and the dynamic workload of the virtual machines may cause the overloading in the hosts. One approach to overcome this problem is reducing the hosts' virtual machines. One crucial issue to improve the quality of the consolidation process's quality is determining the best virtual machine for the migration process. Although the selection process has lower computational complexity than other challenges (like placement and overload prediction) in the consolidation process, this issue has received less attention. This article aims to present an efficient algorithm for the selection process. We first considered five main criteria for the selection process: migration time, migration risk, virtual machine connectivity, releasable resources, and penalty for SLA violation. Then, we propose an algorithm based on analytic hierarchy process multi‐criteria decision‐making technique. Next, to determine the weight of the proposed criteria, we simulate thousands of virtual machines of the PlanetLab workloads. These weights are tunable based on the data center preferences. The results of the suggested approach results show 23% reduction in the hosts' energy consumption, 49% reduction in the number of migrations, and 18% reduction in the SLA violation compared with other techniques. So, using the proposed method may significantly reduce the overall cost of the data centers.
RESUMEN
Platelet-leukocyte crosstalk is commonly manifested by reciprocal links between thrombosis and inflammation. Platelet thrombus acts as a reactive matrix that recruits leukocytes to the injury site where their massive accumulation, activation and migration promote thrombotic events while triggering inflammatory responses. As a life-threatening condition with the associations between inflammation and thrombosis, COVID-19 presents diffuse alveolar damage due to exaggerated macrophage activity and cytokine storms. These events, together with direct intracellular virus invasion lead to pulmonary vascular endothelialitis, cell membranes disruption, severe endothelial injury, and thrombosis. The developing pre-alveolar thrombus provides a hyper-reactive milieu that recruits circulating leukocytes to the injury site where their activation contributes to thrombus stabilization and thrombosis propagation, primarily through the formation of Neutrophil extracellular trap (NET). NET fragments can also circulate and deposit in further distance where they may disseminate intravascular thrombosis in severe cases of disease. Thrombi may also facilitate leukocytes migration into alveoli where their accumulation and activation exacerbate cytokine storms and tissue damage, further complicating the disease. Based on these mechanisms, whether an effective anti-inflammatory protocol can prevent thrombotic events, or on the other hand; efficient antiplatelet or anticoagulant regimens may be associated with reduced cytokine storms and tissue damage, is now of interests for several ongoing researches. Thus shedding more light on platelet-leukocyte crosstalk, the review presented here discusses the detailed mechanisms by which platelets may contribute to the pathogenesis of COVID-19, especially in severe cases where their interaction with leukocytes can intensify both inflammatory state and thrombosis in a reciprocal manner.