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The precipitation of dusty material via unstable orbits on to Saturn from the ring plane is a phenomenon known as ring rain. A key open question for Saturn’s rings is whether silicates and organics rain out of the rings on to Saturn faster than water ice. Such preferential precipitation of dusty material would ‘clean’ the rings and make them appear youthful. In this paper, we investigate the stability of orbiting dust that is stochastically charged and may precipitate on to the planet, be ejected from the system, or remain stable over the duration of our numerical integrations. We find no clear relationship between dust particles’ launch locations in the main rings and their final deposition latitudes on the planet because the orbital motion is sensitive to initial conditions and the charging environment, but averaging over distributions of dust particle properties should lead to high-resolution stability maps for dust in the rings and deposition distributions on the planet, and hence predictions for the observable $\rm H_3^+$ emission strength.

We use deep follow-up XMM-Newton observations of 6 clusters discovered in the XXL Survey at $z>1$ to gain robust measurements of their X-ray properties and to investigate the extent to which scaling relations at low redshift are valid at $z>1$. This sample is unique as it has been investigated for AGN contamination, which ensures measurements are not undermined by systematic uncertainties, and pushes to lower mass at higher redshift than is usually possible, for example with Sunyaev-Zel'dovich (SZ) selected clusters. We determine the flux contribution of point sources to the XXL cluster flux in order to test for the presence of AGN in other high-redshift cluster candidates, and find 3XLSS J231626.8-533822 to be a point source misclassified as a cluster and 3XLSS J232737.3-541618 to be a genuine cluster. We present the first attempt to measure the hydrostatic masses in a bright subsample of $z>1$ X-ray selected galaxy clusters with a known selection function. Periods of high particle background significantly reduced the effective exposure times of observations (losing >50% in some cases) limiting the power of this study. When combined with complementary SZ selected cluster samples at higher masses, the data appear broadly consistent with the self-similar evolution of the low redshift scaling relations between ICM properties and cluster mass, suggesting that properties such as the X-ray temperature, gas mass and SZ signal remain reliable mass proxies even at high redshift., Comment: 13 pages, 7 figures, published in MNRAS

To realise an ISO standard for offshore structures account has to be taken of the differing engineering and safety demands of the participating bodies experienced in their analysis, design and construction. This process of harmonisation began with the strength requirements of tubular members and joints but now involves all platform components and systems. This paper concentrates on members. The competing documents are identified and briefly discussed. The basis of the formulations for the two most suitable candidates is reviewed. Strength formulations are compared and sensitivities to basic variables evaluated. Criteria for selection of the preferred formulations are presented. These are identified but are recommended for improvement. The effects of some of the improvements are examined. In one case, a difference in failure probability of one order of magnitude between competing designs is found. Notwithstanding, the selected formulations are judged to be suitable when implemented with the proposed improvements.