Over the past few years there has been an increasing interest to investigate the potential of Video-Based Learning (VBL) as a result of new forms of online education, such as flipped classrooms and Massive Open Online Courses (MOOCs) in order to engage learners in a self-organized and networked learning experience. However, current VBL approaches suffer from several limitations. These include the focus on the traditional teacher-centered model, the lack of human interaction, the lack of interactivity around the video content, lack of personalization, as well as assessment and feedback. In this paper, we investigate the effective design of VBL environments and present the design, implementation, and evaluation details of CourseMapper as a mind map-based collaborative video annotation and analytics platform that enables learners' collaboration and interaction around a video lecture. Thereby, we focus on the application of learning analytics mainly from a learner perspective to support self-organized and networked learning through personalization of the learning environment, monitoring of the learning process, awareness, self-reflection, motivation, and feedback.

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The current study analyses the activity in cardiac pacing in Bulgaria in 2019, 2020 and 2021 based on data derived from a national registry of patients with cardiac electronic implantable devices (CIEDs). Materials and methods. Data from the national registry BG-Pace in the period 08.2019-06.2021 was retrospectively studied. Demographic data, procedure and device type, pacing mode, etiology, symptoms, preimplantation ECG, number of implantations and centre and operator volumes were analysed. Results. Six thousand nine hundred forty-nine devices were implanted by 47 operators in 28 centres for the study period. Median age was 75 (IQR 68-81, 21-103) years in males and 77 (IQR 71-82, 17-98) years in females, P< 0.05. The largest number of devices were implanted in the age group 70-79 years. The most commonly implanted CIEDs were antibradycardia devices with a total of 486.7/million implantations for the period 08.2019-08.2020 and 353.9/million for the period 08.2020-06.2021. Implanted cardioverter-defibrillators demonstrated a growth from 14.1/million to 20.1/million in the period 08.2020 – 06.2021. The number of all implantations dropped signifi cantly during the two epidemic waves of COVID-19. The mean number of implantations per centre and per operator for the whole period was 232.3±204 (2-705) and 148±139.1 (2-660), respectively. Dual chamber device implantations were more prevalent, representing 65.8% of implantations in AV block I and II degree, 63.5% in complete AV block, 59.8% in intraventricular conduction disturbances and 60.9% in sick sinus syndrome. Pacing modes with atrial sensing represented more than 55% of the implantations for all indications. Increasing age was associated with signifi cantly more common use of VVI pacing mode (P < 0.001). Conclusion. The national registry BG-Pace includes systematic clinical, demographical and procedural data for CIED implantations in Bulgaria. Results demonstrate lower number of implantations compared to the average European volume. There was a signifi cant drop in the implantation rate during the two waves of COVID-19.