| 1. |
- Stephan, K., et al.
(författare)
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Regions of interest on Ganymede's and Callisto's surfaces as potential targets for ESA's JUICE mission
- 2021
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Ingår i: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 208
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Tidskriftsartikel (refereegranskat)abstract
- The JUpiter Icy moons Explorer (JUICE) will investigate Ganymede's and Callisto's surfaces and subsurfaces from orbit to explore the geologic processes that have shaped and altered their surfaces by impact, tectonics, possible cryovolcanism, space weathering due to micrometeorites, radiation and charged particles as well as explore the structure and properties of the icy crust and liquid shell (Grasset et al., 2013). The best possible synergy of the JUICE instruments is required to answer the major science objective of this mission and to fully exploit the po-tential of the JUICE mission. Therefore, the JUICE team is aiming to define high priority targets on both Gany-mede's and Callisto's surfaces to support the coordination of the planning activities by the individual instrument teams. Based on the science objectives of the JUICE mission and the most recent knowledge of Ganymede's and Callisto's geologic evolution we propose a collection of Regions of Interest (RoIs), which characterize surface features and terrain types representing important traces of geologic processes, from past and/or present cryovolcanic and tectonic activity to space weathering processes, which are crucial to understand the geologic evolution of Ganymede and Callisto. The proposed evaluation of RoIs is based on their scientific importance as well as on the opportunities and conditions to observe them during the currently discussed mission profile.
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| 4. |
- Tosi, F., et al.
(författare)
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Characterization of the Surfaces and Near-Surface Atmospheres of Ganymede, Europa and Callisto by JUICE
- 2024
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Ingår i: Space Science Reviews. - : Springer Nature. - 0038-6308 .- 1572-9672. ; 220:5
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Tidskriftsartikel (refereegranskat)abstract
- We present the state of the art on the study of surfaces and tenuous atmospheres of the icy Galilean satellites Ganymede, Europa and Callisto, from past and ongoing space exploration conducted with several spacecraft to recent telescopic observations, and we show how the ESA JUICE mission plans to explore these surfaces and atmospheres in detail with its scientific payload. The surface geology of the moons is the main evidence of their evolution and reflects the internal heating provided by tidal interactions. Surface composition is the result of endogenous and exogenous processes, with the former providing valuable information about the potential composition of shallow subsurface liquid pockets, possibly connected to deeper oceans. Finally, the icy Galilean moons have tenuous atmospheres that arise from charged particle sputtering affecting their surfaces. In the case of Europa, plumes of water vapour have also been reported, whose phenomenology at present is poorly understood and requires future close exploration. In the three main sections of the article, we discuss these topics, highlighting the key scientific objectives and investigations to be achieved by JUICE. Based on a recent predicted trajectory, we also show potential coverage maps and other examples of reference measurements. The scientific discussion and observation planning presented here are the outcome of the JUICE Working Group 2 (WG2): “Surfaces and Near-surface Exospheres of the Satellites, dust and rings”.
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| 5. |
- Jallow, Muminatou, et al.
(författare)
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Genome-wide and fine-resolution association analysis of malaria in West Africa.
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; , s. 657-665
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Tidskriftsartikel (refereegranskat)abstract
- We report a genome-wide association (GWA) study of severe malaria in The Gambia. The initial GWA scan included 2,500 children genotyped on the Affymetrix 500K GeneChip, and a replication study included 3,400 children. We used this to examine the performance of GWA methods in Africa. We found considerable population stratification, and also that signals of association at known malaria resistance loci were greatly attenuated owing to weak linkage disequilibrium (LD). To investigate possible solutions to the problem of low LD, we focused on the HbS locus, sequencing this region of the genome in 62 Gambian individuals and then using these data to conduct multipoint imputation in the GWA samples. This increased the signal of association, from P = 4 x 10(-7) to P = 4 x 10(-14), with the peak of the signal located precisely at the HbS causal variant. Our findings provide proof of principle that fine-resolution multipoint imputation, based on population-specific sequencing data, can substantially boost authentic GWA signals and enable fine mapping of causal variants in African populations.
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| 6. |
- Mangano, Valentina D, et al.
(författare)
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Lack of association of Interferon Regulatory Factor 1 with severe malaria in affected child‐parental trio studies across three African populations
- 2009
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:1, s. e4206-
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Tidskriftsartikel (refereegranskat)abstract
- Interferon Regulatory Factor 1 (IRF-1) is a member of the IRF family of transcription factors, which have key and diverse roles in the gene-regulatory networks of the immune system. IRF-1 has been described as a critical mediator of IFN-gamma signalling and as the major player in driving TH1 type responses. It is therefore likely to be crucial in both innate and adaptive responses against intracellular pathogens such as Plasmodium falciparum. Polymorphisms at the human IRF1 locus have been previously found to be associated with the ability to control P. falciparum infection in populations naturally exposed to malaria. In order to test whether genetic variation at the IRF1 locus also affects the risk of developing severe malaria, we performed a family-based test of association for 18 Single Nucleotide Polymorphisms (SNPs) across the gene in three African populations, using genotype data from 961 trios consisting of one affected child and his/her two parents (555 from The Gambia, 204 from Kenya and 202 from Malawi). No significant association with severe malaria or severe malaria subphenotypes (cerebral malaria and severe malaria anaemia) was observed for any of the SNPs/haplotypes tested in any of the study populations. Our results offer no evidence that the molecular pathways regulated by the transcription factor IRF-1 are involved in the immune-based pathogenesis of severe malaria.
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| 7. |
- Roth, Lorenz, et al.
(författare)
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A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations
- 2021
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Ingår i: Nature Astronomy. - : Springer Nature. - 2397-3366. ; 5:10, s. 1043-1051
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Tidskriftsartikel (refereegranskat)abstract
- Ganymede’s atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the O i 1,356 Å and O i 1,304 Å oxygen emissions were used to infer sputtered molecular oxygen (O2) as an atmospheric constituent, but an expected sublimated water (H2O) component remained undetected. Here we present an analysis of high-sensitivity spectra and spectral images acquired by the Hubble Space Telescope revealing H2O in Ganymede’s atmosphere. The relative intensity of the oxygen emissions requires contributions from the dissociative excitation of water vapour, indicating that H2O is more abundant than O2 around the subsolar point. Away from the subsolar region, the emissions are consistent with a pure O2 atmosphere. Eclipse observations constrain atomic oxygen to be at least two orders of magnitude less abundant than these other species. The higher H2O/O2 ratio above the warmer trailing hemisphere compared with the colder leading hemisphere, the spatial concentration in the subsolar region and the estimated abundance of ~1015 molecules of H2O per cm2 are consistent with sublimation of the icy surface as source.
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| 9. |
- Trumbo, Samantha K., et al.
(författare)
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A New UV Spectral Feature on Europa : Confirmation of NaCl in Leading-hemisphere Chaos Terrain
- 2022
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Ingår i: The Planetary Science Journal. - : American Astronomical Society. - 2632-3338. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Recent visible-wavelength observations of Europa's surface obtained with the Hubble Space Telescope (HST) revealed the presence of an absorption feature near 450 nm that appears spatially correlated with leading-hemisphere chaos terrain. This feature was interpreted to reflect the presence of irradiated sodium chloride ultimately sourced from the interior. Here, we use ultraviolet spectra also collected with the HST to detect an additional previously unseen absorption near 230 nm, which spatially correlates with the 450 nm feature and with the same leading-hemisphere chaos terrain. We find that the new ultraviolet feature is also well matched by irradiated sodium chloride at Europa-like conditions. Such confirmation of sodium chloride within geologically young regions has important implications for Europa's subsurface composition.
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