Electrical conductance at initial stage in epitaxial growth of Pb on modified Si(111) surface

The electrical conductance and RHEED intensities as a function of the coverage have been measured during Pb depositions at 105 K on Si(111)-(6x6)Au with up to 4.2 ML of annealed Pb. The experiments show the strong influence of used substrates on the behavior of the conductance during the epitaxy of Pb atoms, especially for very initial stage of growth. Oscillations of the conductance during the layer-by-layer growth are correlated with RHEED intensity oscillations. The analysis of the conductance behavior is made according to the theory described by Trivedi and Aschcroft (Phys.Rev.B 38,12298 (1988)).Comment: 5 pages, 3 figures. Surf. Sci. - accepte

Transport properties of heavy particles in high Reynolds number turbulence

The statistical properties of heavy particle trajectories in high Reynolds numbers turbulent flows are analyzed. Dimensional analysis assuming Kolmogorov scaling is compared with the result of numerical simulation using a synthetic turbulence advecting field. The non-Markovian nature of the fluid velocity statistics along the solid particle trajectories is put into evidence, and its relevance in the derivation of Lagrangian transport models is discussed.Comment: 30 pages, 11 eps figures included. To appear in Physics of Fluid

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Toward using direct numerical simulationto improve primary break-up modeling

cited By 12International audienceno abstrac

Did the retreat of UK trade unionism accelerate during the 1990-3 recession

SIGLEAvailable from British Library Document Supply Centre- DSC:3597.532(NIESR-DP--57) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Romulus: Along Track Formation of Radar Satellites for MTI (Moving Target Identification) and High SAR Performance

International audienc

Comparative electron diffraction study of the diamond nucleation layer on Ir(001)

The carbon layer formed during the bias enhanced nucleation (BEN) procedure on iridium has been studied by different electron diffraction techniques. In reflection high energy electron diffraction (RHEED) and low energy electron diffraction (LEED) the carbon nucleation layer does not give any indication of crystalline diamond even if the presence of domains proves successful nucleation. In contrast, X-ray photoelectron diffraction (XPD) shows a clear C 1s pattern when domains are present after BEN. The anisotropy in the Ir XPD patterns is reduced after BEN while the fine structure is essentially identical compared to a single crystal Ir film. The change in the Ir XPD patterns after BEN can be explained by the carbon layer on top of a crystallographically unmodified Ir film. The loss and change in the fine structure of the C 1s patterns as compared to a single crystal diamond film are discussed in terms of mosaicity and a defective structure of the ordered fraction within the carbon layer. The present results suggest that the real structure of the BEN layer is more complex than a pure composition of small but perfect diamond crystallites embedded in an amorphous matrix