SAVASA project @ TRECVid 2013: semantic indexing and interactive surveillance event detection

In this paper we describe our participation in the semantic indexing (SIN) and interactive surveillance event detection (SED) tasks at TRECVid 2013 [11]. Our work was motivated by the goals of the EU SAVASA project (Standards-based Approach to Video Archive Search and Analysis) which supports search over multiple video archives. Our aims were: to assess a standard object detection methodology (SIN); evaluate contrasting runs in automatic event detection (SED) and deploy a distributed, cloud-based search interface for the interactive component of the SED task. Results from the SIN task, underlying retrospective classifiers for the surveillance event detection and a discussion of the contrasting aims of the SAVASA user interface compared with the TRECVid task requirements are presented

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

Application of Quality of Experience in Networked Services: Review, Trend & Perspectives

Full text embargoed until 17.10.2019 (publisher's embargo period, 12 months

Effective-capacity-based stochastic delay guarantees for systems with time-varying servers, with an application to IEEE 802.11 WLANs

Many network applications rely on stochastic QoS guarantees. With respect to loss-related performance, the effective bandwidth/capacity theory has proved useful for calculating loss probabilities in queues with complex input and server processes and for formulating simple admission control tests to ensure associated QoS guarantees. This success has motivated the application of the theory for delay-related QoS too. However, up until now this application has been justified only heuristically for queues with variable service rate. The paper fills this gap by establishing rigorously that the effective bandwidth/capacity theory may be used for the asymptotically correct calculation and enforcement of delay tail-probabilities in systems with variable rate servers too. Subsequently, the paper applies the general results to IEEE 802.11 WLANs, by representing each IEEE 802.11 station as an On/Off server and employing the effective capacity function for this model. Comparison of analytical results with simulation validates the effectiveness of the On/Off IEEE 802.11 model for delay-related QoS, complementing earlier results on loss-related performance. © 2010 Elsevier B.V. All rights reserved

A novel Effective Capacity-based framework for providing statistical QoS guarantees in IEEE 802.11 WLANs

This article proposes a performance model of the IEEE 802.11 MAC layer that employs the notion of Effective Capacity. In particular, the paper establishes that an IEEE 802.11 mobile station can be regarded as a Semi-Markovian bursty server of the On/Off type, with known distributions for the On and Off periods, and subsequently applies known results for Semi-Markovian models to derive the Effective Capacity function of this On/Off server. The general Effective Bandwidth/Capacity theory can then be used for computing buffer overflow probabilities and for employing simple traffic control policies to enforce related QoS guarantees. The policies guarantee a soft bound on the buffer overflow probability and are suitable for real-time traffic control over WLANs. The Effective Capacity model of IEEE 802.11 stations is originally developed by assuming that the other competing stations are saturated. This is a conservative assumption that becomes very accurate in a highly loaded network. Subsequently, the model is adapted to encompass lightly loaded networks as well. In the adapted model, each mobile station directly measures a few model parameters, instead of calculating them on the basis of the saturation assumption, and uses these measurements in the computation of its Effective Capacity function. The theoretical results are checked against simulations, validating the appropriateness of the model. © 2011 Elsevier B.V. All rights reserved

Motor vehicle trauma: analysis of injury profiles by road-user category

Background: Vehicle accidents in Greece are among the leading causes of death and the primary one in young people. The mechanism of injury influences the patterns of injury in victims of vehicle accidents. Objective: Identification and analysis of injury profiles of motor-vehicle trauma patients in a Greek level I trauma centre, by road-user category. Patients and methods: The trauma registry data of Herakleion University Hospital of adult trauma patients admitted to the hospital after a vehicle accident between 1997 and 2000 were retrospectively examined. Patients were grouped based on the mechanism of injury into three road-user categories: car occupants, motorcyclists, and pedestrians. Results: Of 730 consecutive patients, 444 were motorcyclists (60.8%), 209 were car occupants (28.7%), and 77 were pedestrians (10.5%). Young men constituted the majority of injured motorcyclists whereas older patients (p = 0.0001) and women (p = 0.0001) represented a substantial proportion of the injured pedestrians. With regard to the spectrum of injuries in the groups, craniocerebral injuries were significantly more frequent in motorcyclists and pedestrians (p = 0.0001); abdominal (p = 0.009) and spinal cord trauma (p = 0.007) in car occupants; and pelvic injuries (p = 0.0001) in pedestrians. Although the car occupants had the highest Injury Severity Score (ISS) (p = 0.04), the pedestrians had the poorest outcome with substantially higher mortality (p = 0.007) than the other two groups. Conclusions: The results reveal a clear association between different road-user categories and age and sex incidence patterns, as well as outcomes and injury profiles. Recognition of these features would be useful in designing effective prevention strategies and in comprehensive prehospital and inhospital treatment of motor-vehicle trauma patients