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- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Cortes, Dina, et al.
(författare)
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A new model of paired clinical teaching of international and Danish medical students
- 2016
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Ingår i: Danish Medical Journal. - 2245-1919. ; 63:7, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Since 2006, one hospital has offered two clinical courses in obstetrics/gynaecology and paediatrics to international (I) students. However, as I-student enrolment increased, the hospital faced cut-backs. As from 2010, I-team course evaluations therefore dropped to unacceptable levels and more I- than Danish (DK) students failed exams. Therefore, in 2012 we started a three-year internationalisation project (I-project) at two hospitals. The primary intervention was to pair training for I- and DK-students at clinical contact, and to offer an exclusive daily lecturer for I-teams.METHODS: We compared the course evaluations and exam grades of I-teams and DK-teams for two years prior to (107 from I-teams - 211 participants from DK-teams) and during the I-project (245 participants from I-teams - 575 from DK-teams).RESULTS: During the I-project, the I-teams' course evaluations increased to acceptable values and to levels comparable to the evaluation scores of DK-teams. Furthermore, I-students now considered that their communication with the patients was acceptable. Before the I-project, I-students had lower exam grades (median = 10 (range: 0-12)) than DK-students (10 (4-12)) (p = 0.03), but during the I-project, exam grades increased to the levels achieved by DK-students (10 (2-12) - 10 (0-12) (p = 0.22), and no more I- than DK-students failed exams (p = 0.51).CONCLUSIONS: Pairing students for clinical training and allocating an exclusive lecturer for I-teams produced improved courses for internationalisation. Allocating an exclusive lecturer was associated with a cost of about 615 EUR per student per course when the team consisted of ten students.FUNDING: The Capital Region of Denmark and the University of Copenhagen.TRIAL REGISTRATION: not relevant.
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