On the security of a new image encryption scheme based on chaotic map lattices

This paper reports a detailed cryptanalysis of a recently proposed encryption scheme based on the logistic map. Some problems are emphasized concerning the key space definition and the implementation of the cryptosystem using floating-point operations. It is also shown how it is possible to reduce considerably the key space through a ciphertext-only attack. Moreover, a timing attack allows the estimation of part of the key due to the existent relationship between this part of the key and the encryption/decryption time. As a result, the main features of the cryptosystem do not satisfy the demands of secure communications. Some hints are offered to improve the cryptosystem under study according to those requirements.Comment: 8 pages, 8 Figure

De l'eau aux dattes : aperçu de la filière datte tunisienne et perspectives d'interventions

La modernisation et l'extension des aménagements hydrauliques dans les oasis du Sud tunisien renchérissent le coût de l'eau tout en accentuant la pression sur la ressource. Or ces oasis sont majoritairement orientées vers la production d'une variété de datte destinée principalement au marché international, la Deglet el Nour. La valorisation de l'eau par ces systèmes de production, et plus généralement, leur durabilité économique et écologique sont donc dépendantes du fonctionnement et des performances de la filière datte, particulièrement dans sa composante exportatrice. Partant des nombreuses études réalisées, complétées par un ensemble d'interviews réalisé dans le cadre du projet Sirma, cet article présente un aperçu de l'organisation et du fonctionnement de la filière. Celle-ci comprend 3 grands types d'acteurs : des producteurs nombreux, de petite taille et atomisés, des conditionneurs-exportateurs peu nombreux mais intégrant faiblement l'amont et l'aval, et des collecteurs jouant le rôle d'intermédiaires entre les précédents. La filière fonctionne essentiellement sous la forme d'un marché spot, sans réelle maîtrise des quantités et qualités livrées. Des stratégies d'investissement dans des capacités de stockage apparaissent néanmoins avec le décalage à venir entre la période de récolte (octobre à décembre) et le ramadan, pic de consommation. Quelques perspectives d'intervention sont tirées de ce premier diagnostic, replacées dans une problématique plus générale de supply chain management

Circumcaval ureter with synchronous ipsilateral transitional cell carcinoma of the renal pelvis and the urinary bladder: report of a case and review of the literature

We report a case of concomitant transitional cell carcinoma (TCC) in a circumcaval ureter and invasive bladder cancer. The diagnosis was based on the findings of excretory urography (IVU) and contrast-enhanced computed tomography (CT). IVU showed a typical J-shaped deformity in the dilated right proximal ureteric segment with moderate hydronephrosis and a filling defect in the renal pelvis, while abdominal CT with contrast showed right hydronephrosis with an intrapelvic tumor. The patient underwent radical cystoprostatectomy and nephroureterectomy. No recurrence was detected after 12 months of follow-up.Key Words: Circumcaval, retrocaval, ureter, bladder, transitional cell carcinom

First report of <i>Pseudocercospora cladosporioides</i>, the causal agent of Cercospora leaf spot of olive trees, in Tunisia

Olive trees (Olea europaea) cv. Meski having leaves with yellow spots on the upper surface and grey blotches on the lower surface were found in three orchards located in the regions of Takelsa, Testour and Enfidha, central and northern Tunisia. The shoots of the olive trees had also become defoliated indicating a severe attack of a pathogen. Pseudocercospora cladosporioides was isolated from symptomatic leaves and Koch’s postulates were fulfilled. This is the first Tunisian report of P. cladosporioides causing Cercospora leaf spot of olive trees

Analysis of Tunisian date palm germplasm using simple sequence repeat primers

Inter Simple Sequence Repeat (ISSR) markers involve polymerase chain reaction (PCR) amplification of DNA using a single primer composed of a microsatellite sequence. ISSR technology rapidly reveals high polymorphic fingerprints and determines genetic diversity. We used genetic markers generated from selected ISSR primers to assess genetic diversity among a set of Tunisian date palm varieties. Seven primers were used to cluster 12 date palm varieties and 77 polymorphic markers were sufficient to identify all of the varieties. These discrete molecular markers were used to estimate genetic distances among the 12 accessions and to examine their genetic relationships. Data analysis identified phenetic groups that were in agreement with those obtained according to agronomic traits and random amplified polymorphic DNA (RAPD) markers. Among the 12 simple sequence repeat (SSR) motifs tested, the most abundant were AG. Key Words: Genetic diversity; ISSR polymorphisms; date palm; Pheonix dactylifera. African Journal of Biotechnology Vol. 3 (4), 2004: 215-21

Efficacy of fungicides for control of powdery mildew on grapevines in Chott Sidi Abdel Salam oasis, southeastern Tunisia

Grapevine is an important fruit crop grown in the Chott Sidi Abdel Salam oasis in south eastern Tunisia. It provides great economic potential for the oasis population due to its higher yield and monetary returns. It, also, has a good nutritional value and is consumed fresh or in dried form. Powdery mildew represents one of the most destructive diseases affecting viticulture, especially in temperate-humid climate. It is an economically important fungal disease in the grapevine farms. This pathogen is able to differentially attack leaves and grapes, and is currently controlled with repeated applications of fungicides. This research aimed to use chemical control in order to assess the ability of contact, systemic and the combination of both routes of fungicides’ administration, at three different sampling moments to manage powdery mildew infestation of grapevines (Cv. Bazzoul Kalba), under field conditions. The experiments were conducted in the oasis of Chott Sidi Abdel Salam in southeastern Tunisia. Both Pristine WG and Vectra 10 SC allowed controlling the disease intensity of powdery mildew compared to Talendo® showing a highly significant augmentation of the inhibitory growth potential (84.26% and 88.94%, respectively at 21 days after the first fungicide application) and the protective potential (73.11% and 76.92%, respectively at 21 day). This information can be used to help grapevines growers to improve powdery mildew control and enhance marketable yields

Efficacy of the Non-Pathogenic Agrobacterium Strains K84 and K1026 against Crown Gall in Tunisia

The non-pathogenic Agrobacterium radiobacter strain K84 and its genetically modified (GEM) strain K1026 were tested for their effectiveness against local Tunisian strains and two reference strains (C58 and B6) of the crown gall bacterium Agrobacterium tumefaciens. Tests in planta were carried out on herbaceous plants (tomato and tagetes) and on some sensitive rootstocks (bitter almond, peach almond hybrid GF677 and quince BA29). In vitro tests showed that both K84 and K1026 were effective and that the difference between these strains was not statistically significant. On tomato and tagetes, strain K84 was effective against all crown gall isolates with the exception of the A. tumefaciens reference strain B6. GEM strain K1026 was very effective against all isolates from Tunisia and against the reference strains. Both antagonistic strains significantly reduced the percentage of galled plants as well as the number of galls per plant. Under field conditions, both antagonists controlled crown gall effectively. Best results were obtained on the bitter almond-tree rootstock. Antagonist effectiveness was less evident on quince BA29 and peach almond GF677 rootstocks. The genetically modified strain K1026 is of interest in controlling crown gall disease in Tunisia

Susceptibility of Some Stone and Pome Fruit Rootstocks to Crown Gall

The susceptibility of different fruit rootstocks to crown gall disease was investigated in greenhouse and field experiments with numerous strains of Agrobacterium tumefaciens over three years. Plants were inoculated in the roots and shoots for pot experiments. Field experiments were performed in a naturally contaminated nursery plot. The genotypes Prunus dulcis and P. persica showed a high level of susceptibility to A. tumefaciens. Among the stone rootstocks, bitter almond was highly susceptible in all experiments. Apricot and Cadaman rootstocks displayed low susceptibility but larger galls, showing that there was no relation between rootstock susceptibility and gall size. Among pome rootstocks, quince BA29 was resistant to the disease, while MM106 was susceptible in potted trials; however, in the field essays, pome rootstocks did not become galled, possibly because the strains had selected for and adapted to stone rootstocks