Origin and Evolution of Saturn's Ring System

The origin and long-term evolution of Saturn's rings is still an unsolved problem in modern planetary science. In this chapter we review the current state of our knowledge on this long-standing question for the main rings (A, Cassini Division, B, C), the F Ring, and the diffuse rings (E and G). During the Voyager era, models of evolutionary processes affecting the rings on long time scales (erosion, viscous spreading, accretion, ballistic transport, etc.) had suggested that Saturn's rings are not older than 100 My. In addition, Saturn's large system of diffuse rings has been thought to be the result of material loss from one or more of Saturn's satellites. In the Cassini era, high spatial and spectral resolution data have allowed progress to be made on some of these questions. Discoveries such as the ''propellers'' in the A ring, the shape of ring-embedded moonlets, the clumps in the F Ring, and Enceladus' plume provide new constraints on evolutionary processes in Saturn's rings. At the same time, advances in numerical simulations over the last 20 years have opened the way to realistic models of the rings's fine scale structure, and progress in our understanding of the formation of the Solar System provides a better-defined historical context in which to understand ring formation. All these elements have important implications for the origin and long-term evolution of Saturn's rings. They strengthen the idea that Saturn's rings are very dynamical and rapidly evolving, while new arguments suggest that the rings could be older than previously believed, provided that they are regularly renewed. Key evolutionary processes, timescales and possible scenarios for the rings's origin are reviewed in the light of tComment: Chapter 17 of the book ''Saturn After Cassini-Huygens'' Saturn from Cassini-Huygens, Dougherty, M.K.; Esposito, L.W.; Krimigis, S.M. (Ed.) (2009) 537-57

Forecasting the effieniency or storm water tanks by 3d modelling : from experimantal tank to real-life works

International audienc

A Search for centrally produced non q anti-q mesons in proton proton interactions at 450-GeV/c using the CERN Omega spectrometer and GAMS-4000: Proposal (Extension of the WA91 and NA12/2 experiments).

0info:eu-repo/semantics/publishe

Mars Express High Resolution Stereo Camera spectrophotometric data: Characteristics and science analysis

The High Resolution Stereo Camera (HRSC) on the Mars Express (MEx) spacecraft in orbit about Mars is delivering images of the Mars surface and atmosphere from its high-inclination, elliptical orbit that are intended to cover most of the Mars surface by the end of the mission. These are acquired in four specific spectral passbands that sample the scene at different parts of the extended visual spectrum from near 0.4 μm to about 1μm and in five additional channels, four used for stereo and one nadir, that use the same fifth spectral passband. These channels view from different angles and can be used for photometric and spectral analysis. The data allow a variety of studies of the surface and atmosphere of Mars, but these require detailed understanding of the data characteristics, as there are several effects, including of the observation geometry and the atmosphere, that need to be treated. This article is a report to the science community on the current understanding of the HRSC color data after an initial analysis and also a demonstration of their capabilities for study of Mars, which, from this study, appear to be considerable. We first discuss the characteristics and calibration of the HRSC spectral data. The atmospheric influence on the photometric appearance of the surface materials is explored, and methods of compensating are considered. Reflectances are calculated for surface units by assuming the dark material is basalt and scaling the entire HRSC scene using a laboratory basalt spectrum for the selected dark material area; the results and the correction factors for different orbits are compared. We present several examples of what could become a large volume of future science results utilizing the HRSC spectrophotometric data in conjunction with photo-interpretation. For example, we find relatively few but very important distinct spectral components at the HRSC resolution, including what we interpret as iron oxide-rich material, unoxidized basalt, and polar ice, consistent with past works. The major spectral components are distributed in ways that suggest compositional mixing and the need to revise the current geologic understanding of major regions

Épuration des eaux usées domestiques par filtres plantés de macrophytes. Recommandations techniques pour la conception et la réalisation

AutresThis is a state of the art on design and construction of vertical and horizontal flow constructed wetlands. This document will be improved with knowledge acquired in the future.Il s'agit d'un état de l'art sur la conception et la mise en oeuvre des filtres plantés de roseaux à écoulement vertical et horizontal. Ce document est appelé à évoluer avec les connaissances acquises

Anecdotal to actual: identifying users of learning development to inform future practice

With increasing pressure on universities to ensure their students are graduating with a good honours degree, understanding where Learning Development sits in the university and its impact is arguably becoming more important. The Centre for Learning and Study Support (CLaSS) at De Montfort University, Leicester, has investigated data, collected since 2010, on student engagement with our Learning Development Service. The study aimed to discover the diversity of students availing of learning development, with regards to characteristics such as: gender, ethnicity, disability, age, parental education and module marks. The data presented shows how CLaSS can justifiably engage in university wide discussions about retention and achievement, as well as widening participation agendas. It compares, where possible, who is using CLaSS to the diversity of students within the university. Initial findings are presented, with discussion about how findings have impacted practice, with a particular focus on the attainment gap. From close analysis of the findings which demonstrate a lack of engagement by males with learning development, the paper proposes why this may be the case and offers insight into recent activities to try and reduce the gender gap. Overall, the paper recognises how interpretation of and greater awareness of our user diversity has informed our team strategy and future direction