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.

Global solutions for a semilinear, two‐dimensional Klein‐Gordon equation with exponential‐type nonlinearity

Abstract: We prove the existence and uniqueness of global solutions for a Cauchy problem associated to a semilinear Klein-Gordon equation in two space dimensions. Our result is based on an interpolation estimate with a sharp constant obtained by a standard variational method. © 2006 Wiley Periodicals, Inc.

Plant-associated microbiomes in arid lands: diversity, ecology and biotechnological potential

Abstract: Aridification is a worldwide serious threat directly affecting agriculture and crop production. In arid and desert areas, it has been found that microbial diversity is huge, built of microorganisms able to cope with the environmental harsh conditions by developing adaptation strategies. Plants growing in arid lands or regions facing prolonged abiotic stresses such as water limitation and salt accumulation have also developed specific physiological and molecular stress responses allowing them to thrive under normally unfavorable conditions. Under such extreme selection pressures, special root-associated bacterial assemblages, endowed with capabilities of plant growth promotion (PGP) and extremophile traits, are selected by the plants. In this review, we provide a general overview on the microbial diversity in arid lands and deserts versus specific microbial assemblages associated with plants. The ecological drivers that shape this diversity, how plant-associated microbiomes are selected, and their biotechnological potential are discussed. Selection and recruitment of the plant associated bacterial assemblages is mediated by the combination of the bio-pedo-agroclimatic conditions and the plant species or varieties. Diversity and functional redundancy of these associated PGPR makes them very active in supporting plant improvement, health and resistance to drought, salt and related stresses. Implementing proper biotechnological applications of the arid and desert-adapted PGPR constitute the challenge to be raised.

Comparative fine structure of the cestode spermatozoon. Relationship to phylogenesis

Abstract: The comparison of the ultrastructure of spermatozoa in Cestodes from seven different orders shows that they have the same general pattern of organization. The main common features are following: (a) a long thread-like body; (b) an elongated nucleus; (c) cortical microtubules underlying plasma membrane; (d) the absence of mitochondria and of a typical acrosome. The mode of spermatozoon differentiation indicates an inversion of the polarity. The number of axonemes of the 9 + "1" pattern, characteristic of the platyhelminthes, allow us to distinguish two types of spermatozoa among cestodes: --The "two-axonemes"-type is considered as primitive as it has also been found in the free-living platyhelminths. This type has been observed in the Pseudophyllidea, Proteocephalidea, Tetrarhynchidea and Tetraphyllidea (Onchobothriidae). --The "one-axoneme"-type has been found in the Cyclophyllidea, Caryophyllaeidea, Diphyllidea and Tetraphyllidea (Phyllobothriidae). It has been proved that the one axoneme type of the spermatozoon, observed in Tetraphyllidea, Phyllobothriidae arises from the two axoneme type by early abortion of the second axoneme. In all the tetraphyllidean species studied so far, we found an helicoidal body forming so-called "crested body" or "spiral crest" at the proximal end of the spermatozoon, which is opposite to the nuclear part. This division of the cestodes into two groups, according to the number of axonemes in the spermatozoon is compared with the phylogenetic diagrammes of Cestoda proposed by Freeman (1973) and Euzet (1974). As result, two hypothesis can be forwarded to explain the relationships between the Tetraphyllidea, Proteocephalidea and Cyclophyllidea. The importance of data on the cestode spermatozoa as a criterion in analysis of cestode phylogenesis is drawn and discussed.

A platform as-a-service for hybrid cloud/fog environments

Abstract: Fog computing brings cloud close to end-users and data sources by enabling computation and storage at the edges of the network. An application can have some of its components running in a “distant” cloud and interacting with the other components running in the fog, closer to end-users and data sources such as wireless sensors. Low latency is the main benefit. Applications spanning cloud and fog, such as Internet of Things (IoT) applications, are still provisioned manually nowadays. This paper proposes an architecture for a Platform as-a-Service (PaaS) to automate applications provisioning in a hybrid cloud/fog environment. Cloud Foundry is used as the basis for its implementation. As a use case, the proposed PaaS was employed to provision a simple component-based IoT application that detects fire and dispatches robots to fight the fire. A prototype is built and measurements are made.