| 1. |
- van Leeuwen, F., et al.
(author)
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Gaia Data Release 1 : Open cluster astrometry: Performance, limitations, and future prospects
- 2017
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
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Journal article (peer-reviewed)abstract
- Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs.
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| 2. |
- 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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| 3. |
- Watson, Hunna J., et al.
(author)
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Common Genetic Variation and Age of Onset of Anorexia Nervosa
- 2022
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In: BIOLOGICAL PSYCHIATRY: GLOBAL OPEN SCIENCE. - : Elsevier BV. - 2667-1743. ; 2:4, s. 368-378
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Journal article (peer-reviewed)abstract
- BACKGROUND: Genetics and biology may influence the age of onset of anorexia nervosa (AN). The aims of this study were to determine whether common genetic variation contributes to age of onset of AN and to investigate the genetic associations between age of onset of AN and age at menarche.METHODS: A secondary analysis of the Psychiatric Genomics Consortium genome-wide association study (GWAS) of AN was performed, which included 9335 cases and 31,981 screened controls, all from European ancestries. We conducted GWASs of age of onset, early-onset AN (,13 years), and typical-onset AN, and genetic correlation, genetic risk score, and Mendelian randomization analyses.RESULTS: Two loci were genome-wide significant in the typical-onset AN GWAS. Heritability estimates (single nucleotide polymorphism-h2) were 0.01-0.04 for age of onset, 0.16-0.25 for early-onset AN, and 0.17-0.25 for typical-onset AN. Early-and typical-onset AN showed distinct genetic correlation patterns with putative risk factors for AN. Specifically, early-onset AN was significantly genetically correlated with younger age at menarche, and typical-onset AN was significantly negatively genetically correlated with anthropometric traits. Genetic risk scores for age of onset and early-onset AN estimated from independent GWASs significantly predicted age of onset. Mendelian randomization analysis suggested a causal link between younger age at menarche and early -onset AN.CONCLUSIONS: Our results provide evidence consistent with a common variant genetic basis for age of onset and implicate biological pathways regulating menarche and reproduction.
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| 4. |
- Siddiqui, Adeel M., et al.
(author)
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Relationships between cardiac magnetic resonance imaging abnormalities in the inter-ventricular septum and Selvester QRS scoring criteria for anterior-septal myocardial infarction in patients with right ventricular volume overload
- 2013
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In: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 46:3, s. 256-262
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Journal article (peer-reviewed)abstract
- Background: Patients with ostium secundum atrial septal defects (ASDs) were studied to determine the prevalence of Selvester anteroseptal myocardial infarction QRS points, and to test the hypothesis that there is a relationship between these criteria and thinning and/or scarring of the inter-ventricular septum (IVS). Methods: Demographic, electrocardiographic (ECG), and cardiac magnetic resonance imaging (CMR) data were acquired on 46 patients with a secundum ASD closed percutaneously. Selvester QRS scoring on patient ECGs was performed for areas representing the anteroseptal region of the left ventricle (LV). The IVS to LV free wall thickness ratio was used to assess thinning of the IVS while late gadolinium enhancement (LGE) of the IVS was used for scarring; both using CMR. Results: Twenty-four (52%) patients scored Selvester QRS points in the anteroseptal region with a mean score of 2.6 +/- 1.8. The mean IVS/LV free wall thickness ratio at the basal level and mid-ventricular level was 1.1 +/- 0.3 and 1.3 +/- 0.3, respectively. There was no association of Selvester QRS points with IVS/LV free wall ratio at the basal (p= 0.59) or mid-ventricular (p=0.13) levels. The one patient with LGE in the IVS had 4 Selvester anteroseptal QRS points. Conclusion: The results of our study demonstrate that in our patient population there is a 52% prevalence of Selvester anteroseptal QRS points which are due to thinning and/or scarring of the IVS in only one patient. (C) 2013 Elsevier Inc. All rights reserved.
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