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- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)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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- Jones, Geraint H., et al.
(author)
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The Comet Interceptor Mission
- 2024
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In: Space Science Reviews. - : Springer Nature. - 0038-6308 .- 1572-9672. ; 220:1
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Journal article (peer-reviewed)abstract
- Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum Δ V capability of 600 ms − 1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.
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- Rawtaer, Iris, et al.
(author)
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A Risk Score for the Prediction of Neurocognitive Disorders among Community-Dwelling Chinese Older Adults
- 2016
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In: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 41:5-6, s. 348-358
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Journal article (peer-reviewed)abstract
- Background: Several risk scores have been developed for predicting cognitive impairment and dementia, but none have been validated in Asian samples. We aimed to produce a risk score that best predicts incident neurocognitive disorder (NCD) among Chinese elderly and to validate this score against the modified risk score derived from the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study. Methods: Data from participants enrolled in the Singapore Longitudinal Ageing Study (SLAS) 1 were analyzed. A total of 957 participants >55 years of age with normal cognition at baseline were included. Incident cases of NCD were measured using the global Clinical Dementia Rating (CDR) and determined by a consensus panel. Results: The best prediction model from SLAS included age, gender, education, depression, heart disease, social and productive activities and Mini-Mental State Examination score. This model predicted the short-term risk of incident NCD in elderly participants moderately well, with a C statistic (area under the curve) of 0.72. Modified CAIDE models applied to our sample had a C statistic of 0.71. Conclusion: Our risk score performs as well as other available risk scores. It is the only risk score formulated for ethnic Chinese, rendering it valuable for clinical use in Asia; at-risk individuals can be identified for early intervention.
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