CDN slicing over a multi-domain edge cloud

Abstract We present an architecture for the provision of video Content Delivery Network (CDN) functionality as a service over a multi-domain cloud. We introduce the concept of a CDN slice, that is, a CDN service instance which is created upon a content provider’s request, is autonomously managed, and spans multiple, potentially heterogeneous, edge cloud infrastructures. Our design is tailored to a 5G mobile network context, building on its inherent programmability, management flexibility, and the availability of cloud resources at the mobile edge level, thus close to end users. We exploit Network Functions Virtualization (NFV) and Multi-access Edge Computing (MEC) technologies, proposing a system which is aligned with the recent NFV and MEC standards. To deliver a Quality-of-Experience (QoE) optimized video service, we derive empirical models of video QoE as a function of service workload, which, coupled with multi-level service monitoring, drive our slice resource allocation and elastic management mechanisms. These management schemes feature autonomic compute resource scaling, and on-the-fly transcoding to adapt video bit-rate to the current network conditions. Their effectiveness is demonstrated via testbed experiments.</P

PPCS:a progressive popularity-aware caching scheme for edge-based cache redundancy avoidance in information-centric networks

Abstract This article proposes a novel chunk-based caching scheme known as the Progressive Popularity-Aware Caching Scheme (PPCS) to improve content availability and eliminate the cache redundancy issue of Information-Centric Networking (ICN). Particularly, the proposal considers both entire-object caching and partial-progressive caching for popular and non-popular content objects, respectively. In the case that the content is not popular enough, PPCS first caches initial chunks of the content at the edge node and then progressively continues caching subsequent chunks at upstream Content Nodes (CNs) along the delivery path over time, according to the content popularity and each CN position. Therefore, PPCS efficiently avoids wasting cache space for storing on-path content duplicates and improves cache diversity by allowing no more than one replica of a specified content to be cached. To enable a complete ICN caching solution for communication networks, we also propose an autonomous replacement policy to optimize the cache utilization by maximizing the utility of each CN from caching content items. By simulation, we show that PPCS, utilizing edge-computing for the joint optimization of caching decision and replacement policies, considerably outperforms relevant existing ICN caching strategies in terms of latency (number of hops), cache redundancy, and content availability (hit rate), especially when the CN’s cache size is small

AVIATOR: An open international registry to evaluate medical and surgical outcomes of aortic valve insufficiency and ascending aorta aneurysm

Objectives: Current national registries are lacking detailed pathology-driven analysis and long-term patients outcomes. The Heart Valve Society (HVS) aortic valve (AV) repair research network started the Aortic Valve Insufficiency and ascending aorta Aneurysm InternATiOnal Registry (AVIATOR) to evaluate long-term patient outcomes of AV repair and replacement. The purpose of the current report is to describe the AVIATOR initiative and report in a descriptive manner the patients included.Methods: The AV repair research network includes surgeons, cardiologists, and scientists and established an online database compliant with the guidelines for reporting valve-related events. Prospective inclusion started from January 2013. Adult patients (18 years or older) who were operated on between 1995 and 2017 with complete procedural specification of the type of repair/replacement were selected for descriptive analysis.Results: Currently 58 centers from 17 countries include 4896 patients with 89% AV repair (n = 4379) versus 11% AV replacement (n = 517). AV repair was either isolated (28%), or associated with tubular/partial root replacement (22%) or valve-sparing root replacement (49%) with an in-hospital mortality of 0.5%, 1.7%, and 1.2%, respectively. AV replacement was either isolated (24%), associated with tubular/partial root replacement (17%) or root replacement (59%) with an in-hospital mortality of 1%, 2.6%, and 2.0%, respectively.Conclusions: The multicenter surgical AVIATOR registry, by applying uniform definitions, should provide a solid evidence base to evaluate the place of repair versus replacement on the basis of long-term patient outcomes. Obtaining data completeness and adequate representation of all surgery types remain challenging. Toward the near future AVIATOR-medical will start to study natural history, as will AVIATOR-kids, with a focus on pediatric disease.Thoracic Surger