| 1. |
- 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. |
- Ning, Yilin, et al.
(författare)
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Handling ties in continuous outcomes for confounder adjustment with rank-ordered logit and its application to ordinal outcomes
- 2020
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Ingår i: Statistical Methods in Medical Research. - : SAGE Publications. - 0962-2802 .- 1477-0334. ; 29:2, s. 437-454
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Tidskriftsartikel (refereegranskat)abstract
- The rank-ordered logit (rologit) model was recently introduced as a robust approach for analysing continuous outcomes, with the linear exposure effect estimated by scaling the rank-based log-odds estimate. Here we extend the application of the rologit model to continuous outcomes with ties and ordinal outcomes treated as imperfectly-observed continuous outcomes. By identifying the functional relationship between survival times and continuous outcomes, we explicitly establish the equivalence between the rologit and Cox models to justify the use of the Breslow, Efron and perturbation methods in the analysis of continuous outcomes with ties. Using simulation, we found all three methods perform well with few ties. Although an increasing extent of ties increased the bias of the log-odds and linear effect estimates and resulted in reduced power, which was somewhat worse when the model was mis-specified, the perturbation method maintained a type I error around 5%, while the Efron method became conservative with heavy ties but outperformed Breslow. In general, the perturbation method had the highest power, followed by the Efron and then the Breslow method. We applied our approach to three real-life datasets, demonstrating a seamless analytical workflow that uses stratification for confounder adjustment in studies of continuous and ordinal outcomes.
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| 3. |
- Ning, Yuping, et al.
(författare)
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Optical simulation and preparation of novel Mo/ZrSiN/ZrSiON/SiO2 solar selective absorbing coating
- 2017
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 167, s. 178-183
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Tidskriftsartikel (refereegranskat)abstract
- A novel Mo/ZrSiN/ZrSiON/SiO2 solar selective absorbing coating has been investigated, which was prepared by magnetron sputtering on stainless steel substrate. A high solar absorptance of 0.94 and a low thermal emittance of 0.06 at 25 degrees C were achieved. By proportionally decreasing the thicknesses of the ZrSiN, ZrSiON and SiO2 layers, the thermal emittance at 500 degrees C was decreased significantly from 0.19 to 0.12 (Delta epsilon = 0.07) while keeping the solar absorptance unchanged. The coating also showed high thermal stability at 500 degrees C in vacuum, implying that it is a promising candidate for high temperature concentrated solar power (CSP) applications.
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