A Baseline Wander Tracking System for Artifact Rejection in Long-Term Electrocardiography

Long-term electrocardiogram (ECG) signals might suffer from relevant baseline disturbances during physical activity. Motion artifacts in particular are more pronounced with dry surface or esophageal electrodes which are dedicated to prolonged ECG recording. In this paper we present a method called baseline wander tracking (BWT) that tracks and rejects strong baseline disturbances and avoids concurrent saturation of the analog front-end. The proposed algorithm shifts the baseline level of the ECG signal to the middle of the dynamic input range. Due to the fast offset shifts, that produce much steeper signal portions than the normal ECG waves, the true ECG signal can be reconstructed offline and filtered using computationally intensive algorithms. Based on Monte Carlo simulations we observed reconstruction errors mainly caused by the non-linearity inaccuracies of the DAC. However, the signal to error ratio of the BWT is higher compared to an analog front-end featuring a dynamic input ranges above 15 mV if a synthetic ECG signal was used. The BWT is additionally able to suppress (electrode) offset potentials without introducing long transients. Due to its structural simplicity, memory efficiency and the DC coupling capability, the BWT is dedicated to high integration required in long-term and low-power ECG recording systems.

Cost-effectiveness of peer role play and standardized patients in undergraduate communication training.

BACKGROUND The few studies directly comparing the methodological approach of peer role play (RP) and standardized patients (SP) for the delivery of communication skills all suggest that both methods are effective. In this study we calculated the costs of both methods (given comparable outcomes) and are the first to generate a differential cost-effectiveness analysis of both methods. METHODS Medical students in their prefinal year were randomly assigned to one of two groups receiving communication training in Pediatrics either with RP (N = 34) or 19 individually trained SP (N = 35). In an OSCE with standardized patients using the Calgary-Cambridge Referenced Observation Guide both groups achieved comparable high scores (results published). In this study, corresponding costs were assessed as man-hours resulting from hours of work of SP and tutors. A cost-effectiveness analysis was performed. RESULTS Cost-effectiveness analysis revealed a major advantage for RP as compared to SP (112 vs. 172 man hours; cost effectiveness ratio .74 vs. .45) at comparable performance levels after training with both methods. CONCLUSIONS While both peer role play and training with standardized patients have their value in medical curricula, RP has a major advantage in terms of cost-effectiveness. This could be taken into account in future decisions.

Clinical usefulness of gene-expression profile to rule out acute rejection after heart transplantation: CARGO II.

AIMS A non-invasive gene-expression profiling (GEP) test for rejection surveillance of heart transplant recipients originated in the USA. A European-based study, Cardiac Allograft Rejection Gene Expression Observational II Study (CARGO II), was conducted to further clinically validate the GEP test performance. METHODS AND RESULTS Blood samples for GEP testing (AlloMap(®), CareDx, Brisbane, CA, USA) were collected during post-transplant surveillance. The reference standard for rejection status was based on histopathology grading of tissue from endomyocardial biopsy. The area under the receiver operating characteristic curve (AUC-ROC), negative (NPVs), and positive predictive values (PPVs) for the GEP scores (range 0-39) were computed. Considering the GEP score of 34 as a cut-off (>6 months post-transplantation), 95.5% (381/399) of GEP tests were true negatives, 4.5% (18/399) were false negatives, 10.2% (6/59) were true positives, and 89.8% (53/59) were false positives. Based on 938 paired biopsies, the GEP test score AUC-ROC for distinguishing ≥3A rejection was 0.70 and 0.69 for ≥2-6 and >6 months post-transplantation, respectively. Depending on the chosen threshold score, the NPV and PPV range from 98.1 to 100% and 2.0 to 4.7%, respectively. CONCLUSION For ≥2-6 and >6 months post-transplantation, CARGO II GEP score performance (AUC-ROC = 0.70 and 0.69) is similar to the CARGO study results (AUC-ROC = 0.71 and 0.67). The low prevalence of ACR contributes to the high NPV and limited PPV of GEP testing. The choice of threshold score for practical use of GEP testing should consider overall clinical assessment of the patient's baseline risk for rejection.

Music Piracy on Peer-to-Peer Networks

Content providers from the music industry argue that peer-to-peer (P2P) networks such as KaZaA, Morpheus, iMesh, or Audiogalaxy are an enormous threat to their business. They furthermore blame these networks for their recent decline in sales figures. For this reason, an empirical investigation was conducted during a period of 6 weeks on one of the most popular files-sharing systems, in order to determine the quantity and quality of pirated music songs shared. We present empirical evidence as to what extent and in which quality music songs are being shared. A number of hypotheses are outlined and were tested. We studied, among other things, the number of users online and the number of flies accessible on such networks, the free riding problem, and the duration per search request. We further tested to see if there are any differences in the accessibility of songs based on the nationality of the artist, the language of the song, and the corresponding chart position. Finally, we outline the main hurdles users may face when downloading illegal music and the probability of obtaining high quality music tracks on such peer-to-peer networks.

Interprofessionelle Vermittlung praktischer Fertigkeiten durch Peer-Tutoren am Beispiel der Punktion peripherer Venen

1. Hintergrund An der Medizinischen Fakultät der Universität Bern wird seit 2014 ein Kurs in peripherer Venenpunktion (Blutentnahme und Anlage eines peripheren Venenkatheters) zusammen mit der Berner Fachhochschule und dem Bildungszentrum Pflege Bern interprofessionell im Peer Teaching Verfahren unterrichtet. 2. Fragestellung Dabei stellt sich die Frage, ob der interprofessionelle Kurs effektiv in der Vermittlung der Lehrinhalte (Blutentnahme und Anlage eines peripheren Venenkatheters) ist und ob er von den Teilnehmern akzeptiert wird. 3. Methoden Sowohl bei den Teilnehmern, als auch bei den Tutoren sind Studierende aller drei Institutionen vertreten. Der Lernerfolg wird bei den Medizinstudierenden mit einem Posten in einem summativen OSCE (Objektive Structured Clinical Exam) durch ärztliche Dozenten überprüft. Der Posten im OSCE 2015 betraf die Blutentnahme und enthielt 7 Items zum Patientengespräch und 12 Items zur praktischen Durchführung. Die Beurteilung des Kurses durch die Teilnehmer wurde mit offenen Fragen zu Lob und Kritik erhoben. Jede Gruppe von 4-6 Teilnehmern füllte zusammen einen Fragebogen aus. Die Bögen wurden qualitativ nach Prinzipien der Häufigkeitsanalyse ausgewertet. 4. Ergebnisse Im Rahmen des OSCE demonstrierten die Medizinstudierenden, dass sie die Blutentnahme entsprechend den Erwartungen der Experten erlernt hatten. 2015 wurden im Durchschnitt 85% aller Items richtig durchgeführt. Von den Teilnehmern wurde der Kurs sehr positiv evaluiert. 42 von 45 Gruppen gaben einen Bogen ab. Besonders positiv wurde die Kompetenz der Peer Tutoren wahrgenommen (20 von 42 Bögen). 16 von 42 Gruppen lobten die kleine Gruppengrösse und 13 von 42 Gruppen gefiel das didaktische Konzept. 5. Schlussfolgerung Peer Teaching ist auch im interprofessionellen Kontext effektiv und akzeptiert. Der Kurs ist ein Beispiel für einen Grundstein in interprofessioneller Ausbildung auf dem Strukturen zur Weiterentwicklung und Forschung in dem Bereich aufgebaut werden können.

The influence of parent's body mass index on peer selection: An experimental approach using virtual reality

Relatively little is known about the influence of psychosocial factors, such as familial role modeling and social network on the development and maintenance of childhood obesity. We investigated peer se- lection using an immersive virtual reality environment. In a virtual schoolyard, children were confronted with normal weight and overweight avatars either eating or playing. Fifty-seven children aged 7–13 participated. Interpersonal distance to the avatars, child's BMI, self-perception, eating behavior and parental BMI were assessed. Parental BMI was the strongest predictor for the children's minimal distance to the avatars. Specifically, a higher mothers' BMI was associated with greater interpersonal distance and children approached closer to overweight eating avatars. A higher father's BMI was associated with a lower interpersonal distance to the avatars. These children approached normal weight playing and overweight eating avatar peers closest. The importance of parental BMI for the child's social approach/ avoidance behavior can be explained through social modeling mechanisms. Differential effects of pa- ternal and maternal BMI might be due to gender specific beauty ideals. Interventions to promote social interaction with peer groups could foster weight stabilization or weight loss in children.