Documenting the Recovery of Vascular Services in European Centres Following the Initial COVID-19 Pandemic Peak: Results from a Multicentre Collaborative Study

Objective: To document the recovery of vascular services in Europe following the first COVID-19 pandemic peak. Methods: An online structured vascular service survey with repeated data entry between 23 March and 9 August 2020 was carried out. Unit level data were collected using repeated questionnaires addressing modifications to vascular services during the first peak (March – May 2020, “period 1”), and then again between May and June (“period 2”) and June and July 2020 (“period 3”). The duration of each period was similar. From 2 June, as reductions in cases began to be reported, centres were first asked if they were in a region still affected by rising cases, or if they had passed the peak of the first wave. These centres were asked additional questions about adaptations made to their standard pathways to permit elective surgery to resume. Results: The impact of the pandemic continued to be felt well after countries’ first peak was thought to have passed in 2020. Aneurysm screening had not returned to normal in 21.7% of centres. Carotid surgery was still offered on a case by case basis in 33.8% of centres, and only 52.9% of centres had returned to their normal aneurysm threshold for surgery. Half of centres (49.4%) believed their management of lower limb ischaemia continued to be negatively affected by the pandemic. Reduced operating theatre capacity continued in 45.5% of centres. Twenty per cent of responding centres documented a backlog of at least 20 aortic repairs. At least one negative swab and 14 days of isolation were the most common strategies used for permitting safe elective surgery to recommence. Conclusion: Centres reported a broad return of services approaching pre-pandemic “normal” by July 2020. Many introduced protocols to manage peri-operative COVID-19 risk. Backlogs in cases were reported for all major vascular surgeries

Optimizing Pub/Sub Systems by Advertisement Pruning

Abstract. Supporting advertisements in large publish/subscribe services has an improving influence on the system scalability. The additional application of event routing optimizations based on subscriptions further increases the event throughput and decreases the memory usage of publish/subscribe systems. However, also advertisement-based optimizations can improve these system properties but have been widely neglected so far. In particular, no current optimizations are applicable to advertisements defined as arbitrary Boolean filter expressions. In this paper, we outline the final milestone on the way to practically support the arbitrary Boolean publish/subscribe model: We firstly develop a novel optimization approach, advertisement pruning, that is tailored to arbitrary Boolean advertisements. Secondly, we present a detailed evaluation of the optimization potential of this advertisement-based solution. We finally analyze the effects of additionally optimizing subscriptions on the advertisement pruning optimization.

A Resource and QoS Management Framework for a Real-time Event System

A new class of applications can now be envisaged with the emergence of both mobile ad hoc computing and ubiquitous computing. Applications of such kind are characterised by being largely distributed and proactive, i.e. able to operate without human intervention. The anonymous and asynchronous paradigm, which is advocated by event models, has shown to be well-suited for this kind of applications. However, current real-time event-oriented middleware technologies do not provide a complete solution for the requirements of mobile ad hoc environments. In this paper, we present the research carried out on both a resource and a QoS management framework to achieve real-time support for an event system operating in mobile ad hoc environments. The framework makes use of both reflection and component technology. The implementation of our resource system is developed in OpenCOM, which is a lightweight, efficient and reflective model based on Microsoft’s COM. 1

A generic component model for building systems software

Component-based software structuring principles are now commonplace at the application level; but componentization is far less established when it comes to building low-level systems software. Although there have been pioneering efforts in applying componentization to systems-building, these efforts have tended to target specific application domains (e.g., embedded systems, operating systems, communications systems, programmable networking environments, or middleware platforms). They also tend to be targeted at specific deployment environments (e.g., standard personal computer (PC) environments, network processors, or microcontrollers). The disadvantage of this narrow targeting is that it fails to maximize the genericity and abstraction potential of the component approach. In this article, we argue for the benefits and feasibility of a generic yet tailorable approach to component-based systems-building that offers a uniform programming model that is applicable in a wide range of systems-oriented target domains and deployment environments. The component model, called OpenCom, is supported by a reflective runtime architecture that is itself built from components. After describing OpenCom and evaluating its performance and overhead characteristics, we present and evaluate two case studies of systems we have built using OpenCom technology, thus illustrating its benefits and its general applicability