Outil pour le masquage/démasquage des fautes byzantines

L'exigence de la tolérance aux fautes est incontournable avec les systèmes distribués. Plusieurs techniques assurent cette tolérance dans de tels systèmes. L'une des approches les plus connues est celle des généraux Byzantins dont l'algorithme est nommé OM. Ce dernier permet d'atteindre un consensus entre tous les composants non-fautifs d'un système malgré la nature aléatoire des fautes traitées. Toutefois à partir de cette approche, plusieurs autres ont vu le jour essayant d'améliorer les résultats qu'elle a engendrés. Par conséquent le développement d'un outil générique et flexible traitant les mécanismes de tolérance aux fautes dans un système Byzantin s'est présenté comme une nécessité induite par la multiplicité des travaux traitant ce problème. Ce mémoire présente un outil graphique permettant à l'utilisateur de simuler le déroulement d'un ensemble d'algorithmes traitant le problème des généraux Byzantins ainsi que d'avoir les résultats sous une forme pratique et conviviale. Tout d'abord, nous présenterons l'état de l'art dans la modélisation du problème Byzantin tout en mettant l'accent sur le principe de consensus et de masquage des fautifs. Ensuite, nous détaillerons une récente approche nommée ABA, permettant de démasquer les fautifs dans un système Byzantin tout en gardant les mêmes contraintes et hypothèses utilisées par l'algorithme OM. Cette approche vise à remédier les défauts de celles qui l'ont précédées par le biais de l'identification des composants fautifs. Des expérimentations subséquentes à l'application de notre outil à cette approche essaieront d'appuyer l'ensemble des résultats théoriques de l'algorithme ABA

Vaccination coverage against COVID-19 in a Tunisian general hospital

Lettor to the editor

Democracy, Investment and Economic Growth

The main purpose of this paper is to identify the relationship between democracy, investment and economic growth for a sample of 11 countries from the MENA region during the period 2000-2009, by using a dynamic panel data model. The democracy’ effect on the contribution of investment to economic growth has been the subject of a second empirical study within the framework of this research paper. The main outcomes drawn by these two empirical tests prove that there is a significant link between on the one hand the democracy and investment and on the other hand between civil liberties and economic growth. The outcomes also highlight a positive interaction between political rights and investment

4-Ammonio-2,2,6,6-tetra­methyl­piperidinium bis­(dihydrogen phosphate) monohydrate

In the crystal structure of the title compound, C9H22N2 2+·2H2PO4 −·H2O, the H2PO4 − anions are hydrogen bonded to each other, forming a ribbon parallel to the b axis. The water mol­ecules connect these ribbons via O—H⋯O hydrogen bonds. The organic cations are attached to the dihydrogen phosphate anions and water mol­ecules through N—H⋯O and C—H⋯O hydrogen bonds, forming an infinite three-dimensional network

The Determinants of Home Bias in Stock Portfolio: An Emerging and Developed Markets Study

The objective of this paper is to measure the degree of Home Bias within holdings portfolio and to identify their determining factors. By following literature and an international CAPM, we have chosen quite a number of susceptible factors that impact Home Bias. This model is, hence, estimated for 20 countries, with cross-section econometrics, between 2008 and 2013. Our results show that all countries have recorded a high level of Home bias in their holdings portfolio. After that, we test if the Home Bias of the emerging markets and that of the developed markets react differently to the determining factors. The volatility of the exchange rate is statistically significant with emerging markets, while it is hardly remarkable for the developed countries. Co-variance, size, distance, language, legal framework and foreign organization stocks prevents American investors to invest abroad. Keywords: International portfolio, Home Bias, exchange rate, emerging market, CAPM JEL Classifications: F31, G1

5-Chloro-2-methoxy­anilinium nitrate

The title salt, C7H9ClNO+·NO3 −, exhibits extensive hydrogen bonding between the ammonium functional group and the nitrate anion. A two-dimensional network of bifurcated N—H⋯O hydrogen bonds generates corrugated layers in the bc plane. The organic mol­ecules are stacked in a parallel orientation as a result of π–π inter­actions, with an inter-ring distance of 3.837 Å

2-Phenyl­anilinium dihydrogen phosphate

In the crystal structure of the title compound, C12H12N+·H2PO4 −, the dihydrogen phosphate anions and the 2-phenyl­anilinium cations are associated via O—H⋯O and N—H⋯O hydrogen bonds so as to build inorganic layers around the x = 1/2 plane. The organic entities are anchored between these layers through C—H⋯O hydrogen bonds, forming a three-dimensional infinite network. The dihedral angle between the aromatic rings is 44.7 (4)°

Distribution of resting cysts of the potentially toxic dinoflagellate Alexandrium pseudogonyaulax in recently-deposited sediment within Bizerte Lagoon (Mediterranean coast, Tunisia)

This study investigated the spatial distribution of Alexandrium pseudogonyaulax resting cysts in recently deposited sediment of Bizerte lagoon (South-Western Mediterranean, Tunisia). This lagoon is the subject of many anthropogenic impacts, such as holding important fishing and aquaculture activities. A. pseudogonyaulax has been shown to produce Goniodomin A, which is a biologically-active compound. We showed that this dinoflagellate produces two types of resting cysts, which could be distinguished by the presence or the absence of a paratabulate wall. The average cyst density across the whole lagoon was rather high, reaching 639 cysts g1 of dry sediment (DS). Cyst densities varied widely among the sampled stations, with the highest density of 1685 cyst g1 DS being recorded at station 51 near a mussel farm. With respect to sediment characteristics, the highest cyst densities were found within silty sediments with high water content values. The distribution of A. pseudongoyaulax cysts in Bizerte lagoon appears to be related to hydrodynamic factors.peer-reviewe

Do the levels of industrial pollutants influence the distribution and abundance of dinoflagellate cysts in the recently-deposited sediment of a Mediterranean coastal ecosystem?

We studied the relationships between sediment industrial pollutants concentrations, sediment characteristics and the dinoflagellate cyst abundance within a coastal lagoon by investigating a total of 55 sampling stations within the Bizerte lagoon, a highly anthropized Mediterranean ecosystem. The sediment of Bizerte lagoon is char- acterized by a high dinocyst abundance, reaching a maximum value of 2742 cysts·g−1 of dry sediment. The investigated cyst diversity was characterized by the presence of 22 dominant dinocyst morphotypes belonging to 11 genera. Two dinoflagellate species dominated the assemblage: Alexandrium pseudogonyaulax and Protoperidinium claudicans, representing 29 to 89% and 5 to 38% of the total cyst abundance, respectively, depending on the station. Seven morphotypes belonging to potentially toxic species were detected, including Alexandrium minutum, A. pseudogonyaulax, Alexandrium catenella/tamarense species complex, Lingulodinium polyedrum, Gonyaulax cf. spinifera complex, Prorocentrum micans and Protoceratium reticulatum. Pearson correlation values showed a positive correlation (α = 0.05) between cyst abundance and both water content and fine silt sediment content. Clustering revealed that the highest abundance of cysts corresponds to stations presenting the higher amounts of heavy metals. The simultaneous autoregressive model (SAM) highlighted a significant correlation (α = 0.05) between cyst accumulation and two main factors: sediment water content and sediment content for several heavy metals, including Hg, Cd, Cu, Ni and Cr. These results suggest that the degree of heavy metal pollution could influence cyst accumulation patterns.peer-reviewe