| 1. |
- Arridge, Christopher S., et al.
(författare)
-
Uranus Pathfinder : exploring the origins and evolution of Ice Giant planets
- 2012
-
Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 753-791
-
Tidskriftsartikel (refereegranskat)abstract
- The "Ice Giants" Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA's Cosmic Vision 2015-2025. UP was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetric magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruise-phase science theme was also developed. The UP mission concept calls for the use of a Mars Express/Rosetta-type platform to launch on a Soyuz-Fregat in 2021 and entering into an eccentric polar orbit around Uranus in the 2036-2037 timeframe. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments.
|
|
| 2. |
- Chakrabarti, Kalyan S., et al.
(författare)
-
A litmus test for classifying recognition mechanisms of transiently binding proteins
- 2022
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Partner recognition in protein binding is critical for all biological functions, and yet, delineating its mechanism is challenging, especially when recognition happens within microseconds. We present a theoretical and experimental framework based on straight-forward nuclear magnetic resonance relaxation dispersion measurements to investigate protein binding mechanisms on sub-millisecond timescales, which are beyond the reach of standard rapid-mixing experiments. This framework predicts that conformational selection prevails on ubiquitin’s paradigmatic interaction with an SH3 (Src-homology 3) domain. By contrast, the SH3 domain recognizes ubiquitin in a two-state binding process. Subsequent molecular dynamics simulations and Markov state modeling reveal that the ubiquitin conformation selected for binding exhibits a characteristically extended C-terminus. Our framework is robust and expandable for implementation in other binding scenarios with the potential to show that conformational selection might be the design principle of the hubs in protein interaction networks.
|
|
| 3. |
- Lanchester, Betty, et al.
(författare)
-
Separating and quantifying ionospheric responses to proton and electron precipitation over Svalbard
- 2011
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. A09322-
-
Tidskriftsartikel (refereegranskat)abstract
- On 16 December 2001, a variable and structured aurora associated with a period of high solar wind velocity and low solar wind density was recorded through optical, radar, and particle measurements from the ground and space. A comprehensive analysis of this data set is carried out using a coupled auroral electron deposition and ion chemistry model. The observations include H beta, N(2)(+) 1N (0, 2), and O(+) (4)P-(4)D optical and electron density radar measurements from the ground, particle data from NOAA 16 and DMSP F14 satellites, and Doppler-shifted H Lyman alpha images from the IMAGE satellite. Modulations in the energy flux of both protons and electrons are seen in the NOAA 16 data as well as in the optical signatures measured on ground and from above. At the time of closest approach of NOAA 16, the observed emissions and electron density at the peak of an enhancement are well reproduced when precipitating protons and electrons with total fluxes of 0.23 and 3.0 mW m(-2), respectively, and mean energies of 2.50 and 0.25 keV, respectively, are used as input for the model. These values are consistent with those measured by the NOAA satellite. The resulting modeled emissions agree well with the ground measurements of enhanced emissions. The correlation between the emissions from N(2)(+) and O(+) suggests that they are primarily due to electron precipitation. This result is confirmed by the agreement between the measured and modeled emissions and by the values of extinction obtained for all three emissions. The modulations to the E region ionization can be explained by proton precipitation alone, while soft electrons are responsible for the changes to the ionization at higher altitudes.
|
|
