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| 2. |
- Jallow, Muminatou, et al.
(author)
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Genome-wide and fine-resolution association analysis of malaria in West Africa.
- 2009
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; , s. 657-665
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Journal article (peer-reviewed)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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| 3. |
- Mangano, Valentina D, et al.
(author)
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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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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:1, s. e4206-
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Journal article (peer-reviewed)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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| 4. |
- Stephan, K., et al.
(author)
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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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In: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 208
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Journal article (peer-reviewed)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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| 6. |
- Harrison, C. M., et al.
(author)
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Establishing the impact of powerful AGN on their host galaxies
- 2020
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In: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; , s. 203-211
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Conference paper (peer-reviewed)abstract
- Establishing the role of active galactic nuclei (AGN) during the formation of galaxies remains one of the greatest challenges of galaxy formation theory. Towards addressing this, we summarise our recent work investigating: (1) the physical drivers of ionised outflows and (2) observational signatures of the impact by jets/outflows on star formation and molecular gas content in AGN host galaxies. We confirm a connection between radio emission and extreme ionised gas kinematics in AGN hosts. Emission-line selected AGN are significantly more likely to exhibit ionised outflows (as traced by the [O iii] emission line) if the projected linear extent of the radio emission is confined within the spectroscopic aperture. Follow-up high resolution radio observations and integral field spectroscopy of 10 luminous Type 2 AGN reveal moderate power, young (or frustrated) jets interacting with the interstellar medium. We find that these sources live in highly star forming and gas rich galaxies. Additionally, by combining ALMA-derived dust maps with integral field spectroscopy for eight host galaxies of z ≈ 2 X-ray AGN, we show that Hα emission is an unreliable tracer of star formation. For the five targets with ionised outflows we find no dramatic in-situ shut down of the star formation. Across both of these studies we find that if these AGN do have a negative impact upon their host galaxies, it must be happening on small (unresolved) spatial scales and/or an observable galaxy-wide impact has yet to occur.
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| 7. |
- Roth, Lorenz, et al.
(author)
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Ganymede’s tenuous atmosphere
- 2024. - 1
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In: Ganymede. - Cambridge, UK : Cambridge University Press.
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Book chapter (peer-reviewed)abstract
- Ganymede possesses a tenuous water-based atmosphere, thought to be produced by the solar and Jovian plasma irradiation of its icy surface. Observational evidence for Ganymede's atmosphere is provided by far-ultraviolet (FUV) emission from the atomic oxygen (O) and hydrogen (H) constituents. The relative strengths of the two observed FUV atomic oxygen emission multiplets, which are produced by electron-impact on the atmosphere, allow inference of molecular O2 and H2O components and their relative abundances. Minor species besides O and H have not been detected and the observational constraints can be considered loose overall, partly due to the inherent ambiguity and difficulty in relating the electron-excited emissions to atmospheric properties. Much of our understanding of the configuration of Ganymede’s atmosphere is based on modelling efforts. The modelling studies suggest that O2 is produced primarily through radiolysis and sputtering by the plasma precipitation in the icy polar regions. Since it does not condense, O2 is yet abundant everywhere and likely the dominant species over most of the surface. Ice sublimation increases the abundance of H2O near the sub-solar point, locally exceeding the O2 abundance. The high altitudes, in contrast, are expected to be primarily populated by the lighter H2 molecules everywhere. Inferred column densities for the primary molecules, O2 and H2O, are on the order of 1014 cm-2 to 1015 cm-2. In addition, models suggest that the atmosphere is collisional only up to a few tens of kilometers above the surface, particular in the dense sub-solar region.
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| 8. |
- Trumbo, Samantha K., et al.
(author)
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A New UV Spectral Feature on Europa : Confirmation of NaCl in Leading-hemisphere Chaos Terrain
- 2022
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In: The Planetary Science Journal. - : American Astronomical Society. - 2632-3338. ; 3:2
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Journal article (peer-reviewed)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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