We consider a system of transmission of the wave equation with Neumann feedback control that contains a delay term and acts on the exterior boundary. First, we prove under some assumptions that the closed-loop system generates a C 0 -semigroup of contractions on an appropriate Hilbert space. Then, under further assumptions, we show that the closed-loop system is exponentially stable. To establish this result, we introduce a suitable energy function and use multiplier method together with an estimate taken from Lasiecka & Triggiani (1992, Appl. Math. Optim., 25, 189–244.) (Lemma 7.2) and compactness-uniqueness argument.

In radiotherapy using 18-fluorodeoxyglucose positron emission tomography (18F-FDG-PET), the accurate delineation of the biological tumour volume (BTV) is a crucial step. In this study, the authors suggest a new approach to segment the BTV in 18F-FDG-PET images. The technique is based on the k-means clustering algorithm incorporating automatic optimal cluster number estimation, using intrinsic positron emission tomography image information. Clinical dataset of seven patients have a laryngeal tumour with the actual BTV defined by histology serves as a reference, were included in this study for the evaluation of results. Promising results obtained by the proposed approach with a mean error equal to (0.7%) compared with other existing methods in clinical routine, including fuzzy c-means with (35.58%), gradient-based method with (19.14%) and threshold-based methods.

In this study, pomace olives coming from different mills (Press process, continuous process two-phases and threephases) were used for extraction of oils. The highest oil yield (12.92%) was obtained with pomace olives coming from press process. Total contents of phenolics (13.47 - 21.25 mg GAE/100 g oil) and flavonoids (5.90 - 12.52mg QE/100 g oil)were determined spectrophotometrically. The pomace olive oil “POO3” (Pomace olive coming from 3-phases system) presented the highest phenolic, flavonoid contents and showed the highest DPPH, ABTS scavenging, metal chelating activity. In vitro anticholinesterase activity, the olive pomace oils showed moderate inhibition against AChE and BChE which are the key enzymes taking place in pathogenesis of Alzheimer’s disease. These results showed that the tested oils can be considered as sources of natural antioxidant, as well as moderate anticholinesterase agents.

This paper is about groundwater’s quality in Ghassira which is located in El-Abiod valley in eastern Algeria. The water is used for human consumption and irrigation. The different layers belong to several types of rocks (limestone and evaporate ...). To study the behaviour   of dissolved salts in this water, we have used geology of the aquifers and statistics. This combination gives us information about minerals those are responsible of water’s quality.  80% of analyzed samples are influenced by evaporate rocks (gypsum, halite…) and 20% by limestone. Many processes have generated these two classes and are relating, especially, with the rocks of aquifers.

Ain Djacer Area is the seat of an aquifer which is located in the alluvial deposits of Mio-Plio-Quaternary. This groundwater has to bedrock clays and gypsum marl Miocene, is surrounded by Cretaceous limestones which are limited to a fixed potential. It is a synclinal filled by sediments Mio-Plio-Quaternary where all flows converge toward the center of the plain. The intensive exploitation of groundwater resources in the region has greatly influenced the hydrodynamic and hydrochemical functioning of the shallow aquifer. This caused a decrease in the static level and mineralization of groundwater. To demonstrate the effect of this situation on the quality of groundwater, a hydrogeochemical study was conducted. This study showed that the calcium bicarbonate facies is near limestone and sodium chloride concentration in the center of the plain in liaison with the lithology. The thermodynamic analysis showed that the main geochemical processes involved in the acquisition of saline load are related to water-rock interaction (dissolution of carbonate and evaporate minerals), the cation exchange and concentrating along flow.