Near-Infrared, Kilosecond Variability of the Wisps and Jet in the Crab Pulsar Wind Nebula

We present a time-lapse sequence of 20 near-infrared (J- and K'-band) snapshots of the central 20x20 arcsec of the Crab pulsar wind nebula, taken at subarcsecond resolution with the Hokupa'a/QUIRC adaptive optics camera on the Gemini North Telescope, and sampled at intervals of 10 min and 24 hr. It is observed that the equatorial wisps and polar knots in the termination shock of the pulsar wind appear to fluctuate in brightness on kilosecond time-scales. Maximum flux variations of +/-24 +/-4 and +/-14 +/-4 per cent relative to the mean (in 1.2 ks) are measured for the wisps and knots respectively, with greatest statistical significance in J band where the nebula background is less prominent. The J and K' flux densities imply different near-infrared spectra for the nonthermal continuum emission from the wisps and outermost polar knot (sprite), giving F_nu ~ nu^{-0.56+/-0.12} and F_nu ~ nu^{-0.21+/-0.13) respectively. The data are compared with existing optical and UV photometry and applied to constrain theories of the variability of the wisps (relativistic ion-cyclotron instability) and knots (relativistic fire hose instability).Comment: 10 pages, 9 figures, to be published in The Astrophysical Journa

Near-Infrared, Kilosecond Variability of the Wisps And Jet in the Crab Pulsar Wind Nebula

We present a time-lapse sequence of 20 near-infrared (J- and K'-band) snapshots of the central 20'' x 20'' of the Crab pulsar wind nebula, taken at sub-arcsecond resolution with the Hokupa'a/QUIRC adaptive optics camera on the Gemini North Telescope, and sampled at intervals of 10 minutes and 24 hours. It is observed that the equatorial wisps and polar knots in the termination shock of the pulsar wind appear to fluctuate in brightness on kilosecond time-scales. Maximum flux variations of {+-}24 {+-} 4 and {+-}14 {+-} 4 per cent relative to the mean (in 1.2 ks) are measured for the wisps and knots respectively, with greatest statistical significance in J band where the nebula background is less prominent. The J and K' flux densities imply different near-infrared spectra for the nonthermal continuum emission from the wisps and outermost polar knot (''sprite''), giving F{sub {nu}} {proportional_to} {nu}{sup -0.56{+-}0.12} and F{sub {nu}} {proportional_to} {nu}{sup -0.21{+-}0.13} respectively. The data are compared with existing optical and UV photometry and applied to constrain theories of the variability of the wisps (relativistic ion-cyclotron instability) and knots (relativistic fire hose instability)

Effectiveness of oncogenetics training on general practitioners' consultation skills: a randomized controlled trial

Contains fulltext : 137892.pdf (publisher's version ) (Open Access)PURPOSE: General practitioners are increasingly called upon to deliver genetic services and could play a key role in translating potentially life-saving advancements in oncogenetic technologies to patient care. If general practitioners are to make an effective contribution in this area, their genetics competencies need to be upgraded. The aim of this study was to investigate whether oncogenetics training for general practitioners improves their genetic consultation skills. METHODS: In this pragmatic, blinded, randomized controlled trial, the intervention consisted of a 4-h training (December 2011 and April 2012), covering oncogenetic consultation skills (family history, familial risk assessment, and efficient referral), attitude (medical ethical issues), and clinical knowledge required in primary-care consultations. Outcomes were measured using observation checklists by unannounced standardized patients and self-reported questionnaires. RESULTS: Of 88 randomized general practitioners who initially agreed to participate, 56 completed all measurements. Key consultation skills significantly and substantially improved; regression coefficients after intervention were equivalent to 0.34 and 0.28 at 3-month follow-up, indicating a moderate effect size. Satisfaction and perceived applicability of newly learned skills were highly scored. CONCLUSION: The general practitioner-specific training proved to be a feasible, satisfactory, and clinically applicable method to improve oncogenetics consultation skills and could be used as an educational framework to inform future training activities with the ultimate aim of improving medical care

Development of an instrument (the COLT) to measure conceptions on learning and teaching of teachers, in student-centred medical education

Item does not contain fulltextBACKGROUND: Conceptions of medical teachers regarding learning and teaching affect their teaching practice. Therefore conceptions should be addressed in faculty development. AIM: To facilitate this, we constructed the Conceptions Of Learning and Teaching (COLT) instrument. METHOD: The COLT was adapted based on experts' comments during a meeting and interviews, followed by a Delphi procedure (Part I). It was administered to teachers from two Dutch medical schools with different traditions in student-centred education (Part II; N=646). The data were analyzed using confirmatory factor analysis and reliability analysis. RESULTS: 324 Teachers (50.2%) completed the questionnaire. Confirmatory factor analysis did not confirm the underlying theoretical model, but an alternative model demonstrated a good fit. This led to an instrument with eighteen items reflecting three underlying factors: 'teacher centredness', 'appreciation of active learning', and 'orientation to professional practice'. We found significant differences in COLT scores between the faculty of the two medical schools. CONCLUSIONS: The COLT appears to be a construct valid tool resulting in reliable scores of teachers' conceptions of learning and teaching, in student-centred medical education. Two of the three factors are new and may be specific for student-centred medical education. The COLT may be a promising tool to improve faculty development

Five teacher profiles in student-centred curricula based on their conceptions of learning and teaching

Contains fulltext : 170678.pdf (publisher's version ) (Open Access)BACKGROUND: Teachers' conceptions of learning and teaching are partly unconscious. However, they are critical for the delivery of education and affect students' learning outcomes. Lasting changes in teaching behaviour can only be realized if conceptions of teachers have been changed accordingly. Previously we constructed a questionnaire named COLT to measure conceptions. In the present study, we investigated if different teacher profiles could be assessed which are based on the teachers' conceptions. These teacher profiles might have implications for individual teachers, for faculty development activities and for institutes. Our research questions were: (1) Can we identify teacher profiles based on the COLT? (2) If so, how are these teacher profiles associated with other teacher characteristics? METHODS: The COLT questionnaire was sent electronically to all teachers in the first three years of the undergraduate curriculum of Medicine in two medical schools in the Netherlands with student-centred education. The COLT (18 items, 5 point Likert scales) comprises three scales: 'teacher centredness', 'appreciation of active learning' and 'orientation to professional practice'. We also collected personal information about the participants and their occupational characteristics. Teacher profiles were studied using a K-means cluster analysis and calculating Chi squares. RESULTS: The response rate was 49.4% (N = 319/646). A five-cluster solution fitted the data best, resulting in five teacher profiles based on their conceptions as measured by the COLT. We named the teacher profiles: Transmitters (most traditional), Organizers, Intermediates, Facilitators and Conceptual Change Agents (most modern). The teacher profiles differed from each other in personal and occupational characteristics. CONCLUSIONS: Based on teachers' conceptions of learning and teaching, five teacher profiles were found in student-centred education. We offered suggestions how insight into these teacher profiles might be useful for individual teachers, for faculty development activities and for institutes and departments, especially if involved in a curriculum reform towards student-centred education