| 11. |
- Krüger, H., et al.
(författare)
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Four years of Ulysses dust data: 1996-1999
- 2001
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Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1303-1324
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse(/i=79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU).Between January /1996 and December /1999 the spacecraft was beyond 3 AUfrom the Sun and crossed the ecliptic plane at aphelion in May /1998. Inthis 4-yr period 218 dust impacts were recorded with the dust detectoron board. We publish and analyse the complete data set of both raw andreduced data for particles with masses10-16-10-8g. Together with 1477 dust impactsrecorded between launch of Ulysses and the end of /1995 publishedearlier (Grün et al., Planet. Space Sci. 43 (/1995a) 971;Krüger et al., Planet. Space Sci. 47 (/1999b) 363), a data set of1695 dust impacts detected with the Ulysses sensor between October /1990and December /1999 is now available. The impact rate measured between1996 and 1999 was relatively constant with about 0.2 impacts per day.The impact direction of the majority of the impacts is compatible withparticles of interstellar origin, the rest are most likelyinterplanetary particles. The observed impact rate is compared with amodel for the flux of interstellar dust particles. The flux of particlesseveral micrometres in size is compared with the measurements of thedust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes,J. Geophys. Res. 85 /(1980) 5841). Between 3 and 5 AU, Pioneer resultspredict that Ulysses should have seen 5 times more (~10mum sized)particles than actually detected.
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| 12. |
- Krüger, H., et al.
(författare)
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Three years of Galileo dust data. II. 1993-1995
- 1999
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Ingår i: Planetary and Space Science. - 1873-5088. ; 47:1-2, s. 85-106
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Tidskriftsartikel (refereegranskat)abstract
- Between January 1993 - December 1995, the Galileo spacecraft traversed the interplanetary space between Earth and Jupiter and arrived at Jupiter on 7 December 1995. The dust instrument onboard the spacecraft was operating during most of the time and data from the instrument were obtained via memory readouts which occurred at rates between twice per day and once per week. All events were classified by an onboard program into 24 categories. Noise events were usually restricted to the lowest categories (class 0). During Galileo's passage through Jupiter's radiation belts on 7 December 1995, several of the higher categories (classes 1 and 2) also show evidence for contamination by noise. The highest categories (class 3) were noise-free all the time. A relatively constant impact rate of interplanetary and interstellar (big) particles of 0.4 impacts per day was detected over the whole three-year time span. In the outer solar system (outside about 2.6 AU) they are mostly of interstellar origin, whereas in the inner solar system they are mostly interplanetary particles. Within about 1.7 AU from Jupiter intense streams of small dust particles were detected with impact rates of up to 20,000 per day whose impact directions are compatible with a Jovian origin. Two different populations of dust particles were detected in the Jovian magnetosphere: small stream particles during Galileo's approach to the planet and big particles concentrated closer to Jupiter between the Galilean satellites. Information about 2883 particles detected by the dust instrument during Galileo's six-year journey to Jupiter is now available.
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| 13. |
- Krüger, H., et al.
(författare)
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Three years of Ulysses dust data: 1993-1995
- 1999
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Ingår i: Planetary and Space Science. - 1873-5088. ; 47:3-4, s. 363-383
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse (i = 79°). After its Jupiter flyby in 1992 at a heliocentric distance of 5.4 AU, the spacecraftreapproached the inner solar system, flew over the Suns south polar region in September 1994,crossed the ecliptic plane at a distance of 1.3 AU in March 1995, and flew over the Suns northpolar region in July 1995. We report on dust impact data obtained with the dust detector onboardUlysses between January 1993 and December 1995. We publish and analyse the complete dataset of 509 recorded impacts of dust particles with masses between 10-16 g-10-7 g. Together with 968 dust impacts from launch until the end of 1992 published earlier ([Gruuml;n et al., 1995c]), information about 1477 particles detected with theUlysses sensor between October 1990 and December 1995 is now available. The impact ratemeasured between 1993 and 1995 stayed relatively constant at about 0.4 impacts per day andvaried by less than a factor of ten. Most of the impacts recorded outside about 3.5 AU arecompatible with particles of interstellar origin. Two populations of interplanetary particles havebeen recognized: big micrometer-sized particles close to the ecliptic plane and smallsub-micrometer-sized particles at high ecliptic latitudes. The observed impact rate is comparedwith a model for the flux of interstellar dust particles which gives relatively good agreement withthe observed impact rate. No change in the instruments noise characteristics or degradation of thechanneltron could be revealed during the three-year period.
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| 14. |
- Hilchenbach, M., et al.
(författare)
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COMET 67P/CHURYUMOV-GERASIMENKO : CLOSE-UP on DUST PARTICLE FRAGMENTS
- 2016
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 816:2
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Tidskriftsartikel (refereegranskat)abstract
- The COmetary Secondary Ion Mass Analyser instrument on board ESA's Rosetta mission has collected dust particles in the coma of comet 67P/Churyumov-Gerasimenko. During the early-orbit phase of the Rosetta mission, particles and particle agglomerates have been imaged and analyzed in the inner coma at distances between 100 km and 10 km off the cometary nucleus and at more than 3 AU from the Sun. We identified 585 particles of more than 14 μm in size. The particles are collected at low impact speeds and constitute a sample of the dust particles in the inner coma impacting and fragmenting on the targets. The sizes of the particles range from 14 μm up to sub-millimeter sizes and the differential dust flux size distribution is fitted with a power law exponent of -3.1. After impact, the larger particles tend to stick together, spread out or consist of single or a group of clumps, and the flocculent morphology of the fragmented particles is revealed. The elemental composition of the dust particles is heterogeneous and the particles could contain typical silicates like olivine and pyroxenes, as well as iron sulfides. The sodium to iron elemental ratio is enriched with regard to abundances in CI carbonaceous chondrites by a factor from ∼1.5 to ∼15. No clear evidence for organic matter has been identified. The composition and morphology of the collected dust particles appear to be similar to that of interplanetary dust particles.
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| 15. |
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| 16. |
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| 17. |
- Schnieders, R, et al.
(författare)
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1H, 13C and 15N chemical shift assignment of the stem-loop 5a from the 5'-UTR of SARS-CoV-2
- 2021
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Ingår i: Biomolecular NMR assignments. - : Springer Science and Business Media LLC. - 1874-270X .- 1874-2718. ; 15:1, s. 203-211
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Tidskriftsartikel (refereegranskat)abstract
- The SARS-CoV-2 (SCoV-2) virus is the causative agent of the ongoing COVID-19 pandemic. It contains a positive sense single-stranded RNA genome and belongs to the genus of Betacoronaviruses. The 5′- and 3′-genomic ends of the 30 kb SCoV-2 genome are potential antiviral drug targets. Major parts of these sequences are highly conserved among Betacoronaviruses and contain cis-acting RNA elements that affect RNA translation and replication. The 31 nucleotide (nt) long highly conserved stem-loop 5a (SL5a) is located within the 5′-untranslated region (5′-UTR) important for viral replication. SL5a features a U-rich asymmetric bulge and is capped with a 5′-UUUCGU-3′ hexaloop, which is also found in stem-loop 5b (SL5b). We herein report the extensive 1H, 13C and 15N resonance assignment of SL5a as basis for in-depth structural studies by solution NMR spectroscopy.
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| 18. |
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| 19. |
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| 20. |
- Wacker, A, et al.
(författare)
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Secondary structure determination of conserved SARS-CoV-2 RNA elements by NMR spectroscopy
- 2020
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Ingår i: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 48:22, s. 12415-12435
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Tidskriftsartikel (refereegranskat)abstract
- The current pandemic situation caused by the Betacoronavirus SARS-CoV-2 (SCoV2) highlights the need for coordinated research to combat COVID-19. A particularly important aspect is the development of medication. In addition to viral proteins, structured RNA elements represent a potent alternative as drug targets. The search for drugs that target RNA requires their high-resolution structural characterization. Using nuclear magnetic resonance (NMR) spectroscopy, a worldwide consortium of NMR researchers aims to characterize potential RNA drug targets of SCoV2. Here, we report the characterization of 15 conserved RNA elements located at the 5′ end, the ribosomal frameshift segment and the 3′-untranslated region (3′-UTR) of the SCoV2 genome, their large-scale production and NMR-based secondary structure determination. The NMR data are corroborated with secondary structure probing by DMS footprinting experiments. The close agreement of NMR secondary structure determination of isolated RNA elements with DMS footprinting and NMR performed on larger RNA regions shows that the secondary structure elements fold independently. The NMR data reported here provide the basis for NMR investigations of RNA function, RNA interactions with viral and host proteins and screening campaigns to identify potential RNA binders for pharmaceutical intervention.
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