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- Albentosa, Ezequiel, et al.
(författare)
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Current Status of the EU-VGOS Project
- 2023
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Ingår i: International VLBI Service for Geodesy and Astrometry 2022 General Meeting Proceedings. ; NASA/ CP–20220018789, s. 85-89
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Konferensbidrag (refereegranskat)abstract
- The EU-VGOS project began in 2018 with the aim of using the VGOS infrastructure in Europe to investigate methods for VGOS data processing. The project is now structured into Working Groups dealing with operations (stations), e-transfer, correlation and post-processing, and analysis. This is a report on the status of the project.
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| 2. |
- Alef, Walter, et al.
(författare)
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Geodetic data analysis of VGOS experiments
- 2021
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Ingår i: 2021 34th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2021.
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Konferensbidrag (refereegranskat)abstract
- Very Long Baseline Interferometry (VLBI) serves as one of the common geodetic methods to define the global reference frames and monitor Earth's orientation variations. The technical upgrade of the VLBI method known as the VLBI Global Observing System (VGOS) includes a critical re-design of the observed frequencies from the dual band mode (S and X band, i.e. 2 GHz and 8 GHz) to observations in a broadband (2-14 GHz). Since 2019 the first VGOS experiments are available for the geodetic analysis in free access at the International VLBI service for Geodesy and Astrometry (IVS). Also regional-only subnetworks such as European VLBI stations have succeeded already in VGOS mode. Based on these brand-new observations we review the current geodetic data analysis workflow to build a bridge between geodetic observed delays derived from different bands.
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| 3. |
- Brunner, Sandra, et al.
(författare)
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Overexpression of RPGR leads to male infertility in mice due to defects in flagellar assembly
- 2008
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Ingår i: Biology of Reproduction. - : Oxford University Press (OUP). - 0006-3363 .- 1529-7268. ; 79:4, s. 608-617
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Tidskriftsartikel (refereegranskat)abstract
- Male infertility is one possible consequence of a group of disorders arising from dysfunction of cilia. Ciliopathies include primary ciliary dyskinesia, polycystic kidney disease, Usher syndrome, nephronophthisis, Bardet-Biedl syndrome, Alstrom syndrome, and Meckel-Gruber syndrome as well as some forms of retinal degenerations. Mutations in the retinitis pigmentosa GTPase regulator gene (RPGR) are best known for leading to retinal degeneration but have also been associated with ciliary dysfunctions affecting other tissues. To further study the involvement of RPGR in ciliopathies, transgenic mouse lines overexpressing RPGR were generated. Animals carrying the transgene in varying copy numbers were investigated. We found that infertility due to aberrant spermatozoa correlated with increased copy numbers. In animals with moderately increased gene copies of Rpgr, structural disorganization in the flagellar midpiece, outer dense fibers, and fibrous sheath was apparent. In contrast, in animals with high copy numbers, condensed sperm heads were present, but the flagellum was absent in the vast majority of spermatozoa, although early steps of flagellar biogenesis were observed. This complexity of defects in flagellar assembly suggests a role of RPGR in intraflagellar transport processes.
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| 4. |
- Haas, Rüdiger, 1966, et al.
(författare)
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GLONASS-VLBI: Onsala-Wettzell test observations
- 2015
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Ingår i: Proceedings of the 22nd European VLBI Group for Geodesy and Astrometry Working Meeting. - 9789892061917 ; , s. 107-111
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Hellerschmied, Andreas, et al.
(författare)
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Scheduling VLBI observations to satellites with VieVS
- 2017
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Ingår i: International Association of Geodesy Symposia. - Cham : Springer International Publishing. - 0939-9585. - 9783319456287 ; 146, s. 59-64
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Konferensbidrag (refereegranskat)abstract
- © Springer International Publishing Switzerland 2016.Observations of satellites with Very Long Baseline Interferometry (VLBI) radio telescopes provide a variety of new possibilities such as the integration of different geodetic techniques, which is one of the main goals of GGOS, the Global Geodetic Observing System of the IAG. Promising applications can be found, among others, in the field of inter-technique frame ties. With the standard geodetic VLBI scheduling software not being prepared to use satellites as radio sources so far, such observations were complicated due to the need to carefully prepare the required interchange files. The newly developed Satellite Scheduling Module for the Vienna VLBI Software (VieVS) offers a solution to this. It allows the user to prepare VLBI schedule files in a standardized format, providing the possibility to carry out actual satellite observations with standard geodetic antennas, e.g. of the IVS network. First successful observations of GLONASS satellites, based on schedules created with the new VieVS module, took place on the baseline Wettzell-Onsala in January 2014.
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| 10. |
- Klopotek, Grzegorz, 1990, et al.
(författare)
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Position determination of the Chang’e 3 lander with geodetic VLBI
- 2019
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Ingår i: Earth, Planets and Space. - : Springer Science and Business Media LLC. - 1880-5981 .- 1343-8832. ; 71:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We present results from the analysis of observations of the Chang’e 3 lander using geodetic Very Long Baseline Interferometry. The applied processing strategy as well as the limiting factors to our approach is discussed. We highlight the current precision of such observations and the accuracy of the estimated lunar-based parameters, i.e., the lunar lander’s Moon-fixed coordinates. Our result for the position of the lander is 44.1219 3 ∘ N , -19.51159∘E and -2637.3 m, with horizontal position uncertainties on the lunar surface of 8.9 m and 4.5 m in latitude and longitude, respectively. This result is in good agreement with the position derived from images taken by the Narrow Angle Camera of the Lunar Reconnaissance Orbiter. Finally, we discuss potential improvements to our approach, which could be used to apply the presented concept to high-precision lunar positioning and studies of the Moon.[Figure not available: see fulltext.].
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