The color of transformation: Investigations into heat treatment of Natufian artifacts from Hayonim Terrace (Israel)

In the Natufian lithic component at Hayonim, both in the cave and the terrace, numerous artifacts of pink/red color may be recognized. Cherts with similar appearance are not present in the geological environment surrounding the site in Northern Israel. Pink chert available in Jordan is shown to be of different nature. Thus this leaves us with the hypothesis of intentional heat treatment of locally available iron-rich yellow chert, of Cenomanian age. Based on experimental replication of chert firing and SEM analysis, we argue that a well-mastered and controlled use of fire was practiced by some skilled craftsmen at Hayonim throughtout the Late Epipalaeolithic

Influence des fluides sur le comportement différé de la craie

National audienceA preliminary experimental study was performed by means of loading stages oedometric tests to highlight the role played by the fluids in the compaction of chalks. Based on a preceding research, the analysis of the North Sea oil reservoir subsidence, the oedometer adaptation to multiphase chalks (air/water or oil/water) required particular precautions. The procedure was validated successfully by the first results which highlight an effect of the fluid saturating on one-dimensional creep. The fluid according to its wettability decreases the resistance and the viscous behaviour starts earlier. Depending on the relationship between the applied stress and the pre consolidation stress, creep is more important when the sample is saturated due to the decrease of the pre consolidation stress. These aspects of the mechanical behaviour of chalks should then be taken into account in an analysis of the long-term stability of underground quarry.Une étude expérimentale préliminaire a été menée au CERMES au moyen d'essais oedométriques par paliers pour mettre en évidence le rôle joué par les fluides lors de la compaction des craies. Fondée sur une recherche précédente, l'analyse de la subsidence des réservoirs pétroliers en Mer du Nord, l'adaptation de l'essai oedométrique aux craies multiphasiques (air/eau ou huile/eau) a nécessité des précautions particulières. La procédure a été validée avec succès par les premiers résultats qui mettent en évidence un effet du fluide saturant sur le fluage unidimensionnel du matériau. En effet, le fluide selon sa mouillabilité diminue la résistance du matériau et amorce un comportement visqueux précoce. Dépendant du rapport entre la contrainte appliquée et la limite élastique, le fluage est plus important quand l'échantillon est saturé du fait de la diminution de la limite élastique qui en suit. La prise en compte de ces aspects du comportement mécanique des craies s'avère indispensable dans l'analyse de la stabilité à long terme d'anciennes carrières souterraines

A constitutive model for unsaturated cemented soils under cyclic loading

On the basis of plastic bounding surface model, the damage theory for structured soils and unsaturated soil mechanics, an elastoplastic model for unsaturated loessic soils under cyclic loading has been elaborated. Firstly, the description of bond degradation in a damage framework is given, linking the damage of soil's structure to the accumulated strain. The Barcelona Basic Model (BBM) was considered for the suction effects. The elastoplastic model is then integrated into a bounding surface plasticity framework in order to model strain accumulation along cyclic loading, even under small stress levels. The validation of the proposed model is conducted by comparing its predictions with the experimental results from multi-level cyclic triaxial tests performed on a natural loess sampled beside the Northern French railway for high speed train and about 140 km far from Paris. The comparisons show the capabilities of the model to describe the behaviour of unsaturated cemented soils under cyclic loading

Determining the unsaturated hydraulic conductivity of a compacted sand-bentonite mixture under constant volume and free-swell conditions

Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of the barrier. In this paper, isothermal infiltration experiments were conducted to determine the unsaturated hydraulic conductivity according to the instantaneous profile method. To do so, total suction changes were monitored at different locations along the soil specimen by using resistivity relative humidity probes. Three constant volume infiltration tests were conducted showing, unexpectedly, a decrease of the hydraulic conductivity during infiltration. One test performed under free-swell conditions showed the opposite and standard trend. These observations were interpreted in terms of microstructure changes during wetting, both under constant volume and free swell conditions

Effects of Ursolic Acid and its Analogues on Soybean 15-Lipoxygenase Activity and the Proliferation Rate of A human Gastric Tumour Cell Line

The authors have previously isolated and purified ursolic acid from heather flowers (Calluna vulgarts). This terpene was found to inhibit HL-60 leukaemic cell proliferation and arachidonic acid oxidative metabolism in various cell species. The effects of ursolic acid and its analogues on soybean 15-lipoxygenase activity and on the proliferation of a human gastric tumour cell line (HGT), have been assessed. These triterpenes inhibited soybean 15-lipoxygenase at its optimal activity (pH 9). The proliferation ofHGT was decreased in a dose-dependent manner. At 20 μM the rank order is: ursolic acid > uvaol > oleanolic acid > methyl ursolate. The carboxylic group at the C28 position of ursolic acid appears to be implicated in the inhibition of both lipoxygenase activity and cell proliferation. Thus methylation of this group decreases these two inhibitory properties. Oleanolic acid, which differs by the position of one methyl group (C20 instead of C19) is less inhibitory than ursolic acid. The lipophilicity of the terpene is also implicated since uvaol appears to be more inhibitory than methyl ursolate

LHCb Preshower Front-End Electronics Board

This note describes the digital part of the fully synchronous solution developped for the lhcb preshower detector Front-End electronics. The general design and the main features of this board are given including trigger part

LHCb Preshower Front-End Electronics Board. Qualification of the final prototype

This note describes the tests performed on the final prototypes of the SPD/Preshower Front-End electronics boards