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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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| 6. |
- Alseekh, Saleh, et al.
(författare)
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Mass spectrometry-based metabolomics: a guide for annotation, quantification and best reporting practices
- 2021
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Ingår i: Nature Methods. - : Springer Science and Business Media LLC. - 1548-7091 .- 1548-7105. ; 18:7, s. 747-756
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Forskningsöversikt (refereegranskat)abstract
- This Perspective, from a large group of metabolomics experts, provides best practices and simplified reporting guidelines for practitioners of liquid chromatography- and gas chromatography-mass spectrometry-based metabolomics. Mass spectrometry-based metabolomics approaches can enable detection and quantification of many thousands of metabolite features simultaneously. However, compound identification and reliable quantification are greatly complicated owing to the chemical complexity and dynamic range of the metabolome. Simultaneous quantification of many metabolites within complex mixtures can additionally be complicated by ion suppression, fragmentation and the presence of isomers. Here we present guidelines covering sample preparation, replication and randomization, quantification, recovery and recombination, ion suppression and peak misidentification, as a means to enable high-quality reporting of liquid chromatography- and gas chromatography-mass spectrometry-based metabolomics-derived data.
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| 8. |
- Boelhouwers, Jan, et al.
(författare)
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The maritime Subantarctic: a distinct periglacial environment
- 2003
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Ingår i: Geomorphology. - : Elsevier. - 0169-555X .- 1872-695X. ; 52:1-2, s. 39-55
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Tidskriftsartikel (refereegranskat)abstract
- Recent research on slope processes and weathering on Marion Island has highlighted distinctive attributes of the maritime Subantarctic periglacial environment, compared to other periglacial environments. This is reflected morphologically by sorted stripe characteristics and stratified solifluction forms, but the wind factor and low diurnal temperature range also results in differences with other diurnal frost environments. Its hyper-maritime setting at low mean annual temperatures results in very high frost cycle frequencies, with associated effectiveness in surface sediment transport and patterned ground development. In addition, a high frequency of wetting and drying cycles is observed in rocks. Small seasonal temperature ranges and steep temperature profiles indicate a high sensitivity to climate change in the Subantarctic, as reflected in a rich relict periglacial record on most islands. This sensitivity appears absent in high tropical environments of low annual temperature range.
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- Klein, Daniel B., Adjungerad professor
(författare)
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What 21st-Century Works Will Merit a Close Reading in 2050? : Second Tranche of Responses
- 2021
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Ingår i: Econ Journal Watch. - : Econ Journal Watch. - 1933-527X. ; 18:1, s. 164-191
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Adam Smith applied the expression “never to be forgotten” to two thinkers he knew personally, born more than 300 years ago, and those two thinkers are not yet forgotten.We undertook the present query in 2020, looking a mere 30 years ahead. What 21st-century works will merit a close reading in 2050? That is the question asked of Econ Journal Watch authors (specifically: those who authored material in sections other than the Comments section of the journal). The previous issue of this journal provided responses from authors with last names beginning A through K (link). Here we present nineteen responses from authors L through Z.
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