Tunis University

About: Tunis University is a education organization based out in Tunis, Tunisia. It is known for research contribution in the topics: Population & Thin film. The organization has 11745 authors who have published 15400 publications receiving 154900 citations. The organization is also known as: University of Tunis & UT.

On ( Ψ,φ )-weakly contractive condition in partially ordered metric spaces

Abstract: Recently, Heman Kumar Nashine and Bessem Samet [H.K. Nashine, B. Samet, Fixed point results for mappings satisfying (@j,@f)-weakly contractive condition in partially ordered metric spaces, Nonlinear Anal. 74 (2011) 2201-2209] studied some coincidence fixed point and common fixed point theorems for two mappings satisfying (@j,@f)-weakly contractive condition in an ordered complete metric space. In the present paper, we study some coincidence fixed point and common fixed point theorems for three mappings S,T and R satisfying (@j,@f)-weakly contractive condition in an ordered complete metric space, where the mappings S and T are assumed to be weakly increasing with respect to R. Our results generalize several well-known results in the literature.

Quantifying security threats and their potential impacts: a case study

Abstract: In earlier works we presented a computational infrastructure that allows an analyst to estimate the security of a system in terms of the loss that each stakeholder stands to sustain as a result of security breakdowns. In this paper we illustrate this infrastructure by means of an e-commerce application.

Genetic diversity of different Tunisian fig (Ficuscarica L.) collections revealed by RAPD fingerprints.

Abstract: The genetic diversity in Tunisian fig (Ficus carica L.) was studied using RAPD markers. Thirtyfive fig cultivars originating from diverse geographical areas and belonging to three collections were analysed. Random decamer primers were screened to assess their ability to detect polymorphisms in this crop. Fortyfour RAPD markers were revealed and used to survey the genetic diversity and to detect cases of mislabelling. As a result, considerable genetic diversity was detected among the studied F. carica accessions. The relationships among the 35 varieties were studied by cluster analysis. The dendrogram showed two main groups composed of cultivars with similar geographic origin. Moreover, the male accessions (caprifigs) were clustered indistinctively within the female ones, suggesting a narrow genetic diversity among these accessions. Our data proved that RAPD markers are useful for germplasm discrimination as well as for investigation of patterns of variation in fig. Since this designed procedure has permitted to establish a molecular database of the reference collections, the opportunity of this study is discussed in relation to the improvement and rational management of fig germplasm.

EELS study of interfaces in magnetoresistive LSMO/STO/LSMO tunnel junctions

Abstract: A magnetic tunnel junction consists of two ferromagnetic conducting electrodes separated by an insulating thin layer The performance of such a system strikingly depends on the last conducting atomic layers in contact with the insulator Consequently, the present paper reports a nanoscale electron energy loss spectroscopy (EELS) study, which has been performed across a couple of La066Sr033MnO3,/SrTiO3/La066Sr033MnO3 tunnel junctions with different barrier thickness es (15 nm and 5 nm respectively) It aims at determining not only the chemical composition in the interface areas, but also the effect of the neighbouring atoms on their electronic structure Using recent improvements in the STEM-EELS data acquisition and processing techniques (systematic use of spectrum-line and spectrum-image modes, multivariate statistical analysis, 2D energy deconvolution schemes, etc), the local chemical information is better extracted with shorter acquisition times, while the large increase of the data set contributes to validate the results Within the accuracy level of these measurements, the elemental composition of the different phases remains stable up to the interfaces with no evidence of extra doping Furthermore, weak changes on the Mn-2p edge fine structures (weak shift to lower energy loss values and extra splitting on the top of the Mn L3 line are observed on all the interfaces They are interpreted as a consequence of a slight reduction of the local Mn valence likely accompanied by a strain induced change in local symmetry The discussion is focussed on all spectral changes identified at a (sub)nanometer scale and their potential effects on the degradation of magnetic and transport properties measured, close to room temperature, at a macroscopic level

Pituitary adenylate cyclase-activating polypeptide protects astroglial cells against oxidative stress-induced apoptosis.

Abstract: Oxidative stress, associated with a variety of disorders including neurodegenerative diseases, results from accumulation of reactive oxygen species (ROS) Oxidative stress is not only responsible for neuron apoptosis, but can also provoke astroglial cell death Numerous studies indicate that pituitary adenylate cyclase-activating polypeptide (PACAP) promotes neuron survival, but nothing is known regarding the action of PACAP on astroglial cell survival Thus, the purpose of the present study was to investigate the potential glioprotective effect of PACAP on H(2)O(2)-induced astrocyte death Pre-treatment of cultured rat astrocytes with nanomolar concentrations of PACAP prevented cell death provoked by H(2)O(2) (300 μM), whereas vasoactive intestinal polypeptide was devoid of protective activity The effect of PACAP on astroglial cell survival was abolished by the type 1 PACAP receptor antagonist, PACAP6-38 The protective action of PACAP was blocked by the protein kinase A inhibitor H89, the protein kinase C inhibitor chelerythrine and the mitogen-activated protein (MAP)-kinase kinase (MEK) inhibitor U0126 PACAP stimulated glutathione formation, and blocked H(2)O(2)-evoked ROS accumulation and glutathione content reduction In addition, PACAP prevented the decrease of mitochondrial activity and caspase 3 activation induced by H(2)O(2) Taken together, these data indicate for the first time that PACAP, acting through type 1 PACAP receptor, exerts a potent protective effect against oxidative stress-induced astrocyte death The anti-apoptotic activity of PACAP on astrocytes is mediated through the protein kinase A, protein kinase C and MAPK transduction pathways, and can be accounted for by inhibition of ROS-induced mitochondrial dysfunctions and caspase 3 activation