Découverte d'un diatrème de kimberlite diamantifère à Séguéla en Côte-d'Ivoire

The Séguéla area in Ivory Coast is known for its diamond-bearing field related to dykes of kimberlite and lamproite. These dykes, devoid of any deformation and metamorphism, crosscut the Birimian formations. Their N 170° orientation is controlled by the tectonized contact between the Archean and the Paleoproterozoic shields of the West-African craton. Discovery of a diatreme, with its pipe breccias and well-preserved maar sediments, below the present-day colluvia, attests for the probable recent geological age (Cretaceous?) of the kimberlitic activity. To cite this article: A. Pouclet et al., C. R. Geoscience 336 (2004).     

A multiple linear statistical model for estimating the mean maximum urban heat island

Summary ¶This study examines the spatial and quantitative influence of urban factors on the surface air temperature field of the medium-sized of Szeged, Hungary, using mobile measurements under different weather conditions in the periods of March 1999–February 2000 and April–October 2002. Efforts have been concentrated on the development of the urban heat island (UHI) in its peak development during the diurnal cycle. Tasks included: (1) determination of spatial distribution of mean maximum UHI intensity and some urban surface parameters (built-up and water surface ratios, sky view factor, building height) using the standard Kriging procedure, as well as (2) development of a statistical model in the so-called heating and non-heating seasons using the above mentioned parameters and their areal extensions. In both seasons the spatial distribution of the mean maximum UHI intensity fields had a concentric shape with some local irregularities. The intensity reaches more than 2.1°C (heating season) and 3.1°C (non-heating season) in the centre of the city. For both seasons statistical model equations were determined by means of stepwise multiple linear regression analysis. As the measured and calculated mean maximum UHI intensity patterns show, there is a clear connection between the spatial distribution of the urban thermal excess and the examined land-use parameters, so these parameters play an important role in the evolution of the strong UHI intensity field. From the above mentioned parameters the sky-view factor and the building height were the most determining factors which are in line with the urban surface energy balance. Therefore in the future, using our model it will be possible to predict mean maximum UHI intensity in other cities, which have land-use features similar to Szeged.Received September 26, 2002; revised February 25, 2003; accepted March 22, 2003 Published online July 30, 2003     

Moisture source diagnostics and isotope characteristics for precipitation in east Hungary: implications for their relationship

Knowledge relating to the relationship between the characteristics of precipitation and sources of moisture is essential to improve our understanding of the global water cycle. This study presents the first quantitative estimation of the moisture source regions combined with stable isotope analyses for precipitation at K-puszta, east Hungary. The contributions of the following moisture sources were diagnosed according to the sector analysis of 4-day backward trajectories together with the calculation of evaporation and precipitation fluxes based on the specific humidity: Mediterranean region (57.0%), local moisture (14.8%), Atlantic region (14.2%), Northern Europe (7.4%) and Eastern Europe (6.6%). The δD and δ¹⁸O values of daily precipitation were measured and the deuterium excess (d-excess) was calculated. The d-excess showed systematic differences among the marine sources, reflecting the characteristics of the moisture source area. The results suggest that the stable isotope composition of precipitation preserves information regarding the origin of the water vapour.     

USE OF REPLICATION AND SIGNAL-TO-NOISE RATIOS IN THE IDENTIFICATION AND ESTIMATION OF THE COMPOSITION OF LUBRICANT BASESTOCK MIXTURES USING ~(13)C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND PROJECTION INTO PRINCIPAL COMPONENT/CANONICAL VARIATES SPACE

The theory of experimental error in analysis of mixture experiments by abstract factor analysis or targettransformation factor analysis is considered. The theoretical implications of using signal-to-noise ratios(as weights) or canonical variates analysis to reduce the level of imbedded error in the factor model areexamined. The approach is illustrated by application to ~(13)C NMR spectra of lubricant basestockmixtures.