| 1. |
- Mangold, N., et al.
(författare)
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Perseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, Mars
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6568
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Tidskriftsartikel (refereegranskat)abstract
- Observations from orbital spacecraft have shown that Jezero crater on Mars contains a prominent fan-shaped body of sedimentary rock deposited at its western margin. The Perseverance rover landed in Jezero crater in February 2021. We analyze images taken by the rover in the 3 months after landing. The fan has outcrop faces, which were invisible from orbit, that record the hydrological evolution of Jezero crater. We interpret the presence of inclined strata in these outcrops as evidence of deltas that advanced into a lake. In contrast, the uppermost fan strata are composed of boulder conglomerates, which imply deposition by episodic high-energy floods. This sedimentary succession indicates a transition from sustained hydrologic activity in a persistent lake environment to highly energetic short-duration fluvial flows.
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| 2. |
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| 3. |
- Gehlen, J., et al.
(författare)
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First genome-wide association study of esophageal atresia identifies three genetic risk loci at CTNNA3, FOXF1/FOXC2/FOXL1, and HNF1B
- 2022
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Ingår i: Human Genetics and Genomics Advances. - : Elsevier BV. - 2666-2477. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Esophageal atresia with or without tracheoesophageal fistula (EA/TEF) is the most common congenital malformation of the upper digestive tract. This study represents the first genome-wide association study (GWAS) to identify risk loci for EA/TEF. We used a European case-control sample comprising 764 EA/TEF patients and 5,778 controls and observed genome-wide significant associations at three loci. On chromosome 10q21 within the gene CTNNA3 (p = 2.11 × 10−8; odds ratio [OR] = 3.94; 95% confidence interval [CI], 3.10–5.00), on chromosome 16q24 next to the FOX gene cluster (p = 2.25 × 10−10; OR = 1.47; 95% CI, 1.38–1.55) and on chromosome 17q12 next to the gene HNF1B (p = 3.35 × 10−16; OR = 1.75; 95% CI, 1.64–1.87). We next carried out an esophageal/tracheal transcriptome profiling in rat embryos at four selected embryonic time points. Based on these data and on already published data, the implicated genes at all three GWAS loci are promising candidates for EA/TEF development. We also analyzed the genetic EA/TEF architecture beyond the single marker level, which revealed an estimated single-nucleotide polymorphism (SNP)-based heritability of around 37% ± 14% standard deviation. In addition, we examined the polygenicity of EA/TEF and found that EA/TEF is less polygenic than other complex genetic diseases. In conclusion, the results of our study contribute to a better understanding on the underlying genetic architecture of ET/TEF with the identification of three risk loci and candidate genes. © 2022 The Authors
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| 5. |
- Schweinsberg, Martin, et al.
(författare)
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Same data, different conclusions : Radical dispersion in empirical results when independent analysts operationalize and test the same hypothesis
- 2021
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Ingår i: Organizational Behavior and Human Decision Processes. - : Elsevier BV. - 0749-5978 .- 1095-9920. ; 165, s. 228-249
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Tidskriftsartikel (refereegranskat)abstract
- In this crowdsourced initiative, independent analysts used the same dataset to test two hypotheses regarding the effects of scientists' gender and professional status on verbosity during group meetings. Not only the analytic approach but also the operationalizations of key variables were left unconstrained and up to individual analysts. For instance, analysts could choose to operationalize status as job title, institutional ranking, citation counts, or some combination. To maximize transparency regarding the process by which analytic choices are made, the analysts used a platform we developed called DataExplained to justify both preferred and rejected analytic paths in real time. Analyses lacking sufficient detail, reproducible code, or with statistical errors were excluded, resulting in 29 analyses in the final sample. Researchers reported radically different analyses and dispersed empirical outcomes, in a number of cases obtaining significant effects in opposite directions for the same research question. A Boba multiverse analysis demonstrates that decisions about how to operationalize variables explain variability in outcomes above and beyond statistical choices (e.g., covariates). Subjective researcher decisions play a critical role in driving the reported empirical results, underscoring the need for open data, systematic robustness checks, and transparency regarding both analytic paths taken and not taken. Implications for orga-nizations and leaders, whose decision making relies in part on scientific findings, consulting reports, and internal analyses by data scientists, are discussed.
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| 6. |
- Stack, K. M., et al.
(författare)
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Sedimentology and Stratigraphy of the Shenandoah Formation, Western Fan, Jezero Crater, Mars
- 2024
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Ingår i: Journal of Geophysical Research: Planets. - 2169-9097. ; 129:2
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Tidskriftsartikel (refereegranskat)abstract
- Sedimentary fans are key targets of exploration on Mars because they record the history of surface aqueous activity and habitability. The sedimentary fan extending from the Neretva Vallis breach of Jezero crater's western rim is one of the Mars 2020 Perseverance rover's main exploration targets. Perseverance spent ∼250 sols exploring and collecting seven rock cores from the lower ∼25 m of sedimentary rock exposed within the fan's eastern scarp, a sequence informally named the “Shenandoah” formation. This study describes the sedimentology and stratigraphy of the Shenandoah formation at two areas, “Cape Nukshak” and “Hawksbill Gap,” including a characterization, interpretation, and depositional framework for the facies that comprise it. The five main facies of the Shenandoah formation include: laminated mudstone, laminated sandstone, low-angle cross stratified sandstone, thin-bedded granule sandstone, and thick-bedded granule-pebble sandstone and conglomerate. These facies are organized into three facies associations (FA): FA1, comprised of laminated and soft sediment-deformed sandstone interbedded with broad, unconfined coarser-grained granule and pebbly sandstone intervals; FA2, comprised predominantly of laterally extensive, soft-sediment deformed laminated, sulfate-bearing mudstone with lenses of low-angle cross-stratified and scoured sandstone; and FA3, comprised of dipping planar, thin-bedded sand-gravel couplets. The depositional model favored for the Shenandoah formation involves the transition from a sand-dominated distal alluvial fan setting (FA1) to a stable, widespread saline lake (FA2), followed by the progradation of a river delta system (FA3) into the lake basin. This sequence records the initiation of a relatively long-lived, habitable lacustrine and deltaic environment within Jezero crater.
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| 8. |
- Cousin, A., et al.
(författare)
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Compositions of coarse and fine particles in martian soils at gale: A window into the production of soils
- 2015
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Ingår i: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 249, s. 22-42
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Tidskriftsartikel (refereegranskat)abstract
- The ChemCam instrument onboard the Curiosity rover provides for the first time an opportunity to study martian soils at a sub-millimeter resolution. In this work, we analyzed 24 soil targets probed by ChemCam during the first 250 sols on Mars. Using the depth profile capability of the ChemCam LIBS (Laser-Induced Breakdown Spectroscopy) technique, we found that 45% of the soils contained coarse grains (>500 μm). Three distinct clusters have been detected: Cluster 1 shows a low SiO2 content; Cluster 2 corresponds to coarse grains with a felsic composition, whereas Cluster 3 presents a typical basaltic composition. Coarse grains from Cluster 2 have been mostly observed exposed in the vicinity of the landing site, whereas coarse grains from Clusters 1 and 3 have been detected mostly buried, and were found all along the rover traverse. The possible origin of these coarse grains was investigated. Felsic (Cluster 2) coarse grains have the same origin as the felsic rocks encountered near the landing site, whereas the origin of the coarse grains from Clusters 1 and 3 seems to be more global. Fine-grained soils (particle size < laser beam diameter which is between 300 and 500 μm) show a homogeneous composition all along the traverse, different from the composition of the rocks encountered at Gale. Although they contain a certain amount of hydrated amorphous component depleted in SiO2, possibly present as a surface coating, their overall chemical homogeneity and their close-to-basaltic composition suggest limited, or isochemical alteration, and a limited interaction with liquid water. Fine particles and coarse grains from Cluster 1 have a similar composition, and the former could derive from weathering of the latter. Overall martian soils have a bulk composition between that of fine particles and coarse grains. This work shows that the ChemCam instrument provides a means to study the variability of soil composition at a scale not achievable by bulk chemical analyses.
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| 9. |
- Lasue, J., et al.
(författare)
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Martian Eolian Dust Probed by ChemCam
- 2018
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Ingår i: Geophysical Research Letters. - : John Wiley & Sons. - 0094-8276 .- 1944-8007. ; 45:20, s. 10968-10977
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitous eolian dust on Mars plays important roles in the current sedimentary and atmospheric processes of the planet. The ChemCam instrument retrieves a consistent eolian dust composition at the submillimeter scale from every first laser shot on Mars targets. Its composition presents significant differences with the Aeolis Palus soils and the Bagnold dunes as it contains lower CaO and higher SiO2. The dust FeO and TiO2contents are also higher, probably associated with nanophase oxide components. The dust spectra show the presence of volatile elements (S and Cl), and the hydrogen content is similar to Bagnold sands but lower than Aeolis Palus soils. Consequently, the dust may be a contributor to the amorphous component of soils, but differences in composition indicate that the two materials are not equivalent.
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| 10. |
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