Market Power and Collusion on Interconnection Phone Market in Tunisia : What Lessons from International Experiences

We try in this paper to characterize the state of mobile phone market in Tunisia. Our study is based on a survey of foreign experience (Europe) in detecting collusive behavior and a comparison of the critical threshold of collusion between operators in developing countries like Tunisia. The market power is estimated based on the work of Parker Roller (1997) and the assumption of "Balanced Calling Pattern". We use then the model of Friedman (1971) to compare the critical threshold of collusion. We show that the "conduct parameter" measuring the intensity of competition is not null during the period 1993-2011. Results show also that collusion is easier on the Tunisian market that on the Algerian, Jordanian, or Moroccan one

Age- and season-dependent pattern of flavonol glycosides in Cabernet Sauvignon grapevine leaves

Flavonols play key roles in many plant defense mechanisms, consequently they are frequently investigated as stress sensitive factors in relation to several oxidative processes. It is well known that grapevine (Vitis vinifera L.) can synthesize various flavonol glycosides in the leaves, however, very little information is available regarding their distribution along the cane at different leaf levels. In this work, taking into consideration of leaf position, the main flavonol glycosides of a red grapevine cultivar (Cabernet Sauvignon) were profiled and quantified by HPLC–DAD analysis. It was found that amount of four flavonol glycosides, namely, quercetin-3-O-galactoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside and kaempferol-3-O-glucuronide decreased towards the shoot tip. Since leaf age also decreases towards the shoot tip, the obtained results suggest that these compounds continuously formed by leaf aging, resulting in their accumulation in the older leaves. In contrast, quercetin-3-O-glucuronide (predominant form) and quercetin-3-O-rutinoside were not accumulated significantly by aging. We also pointed out that grapevine boosted the flavonol biosynthesis in September, and flavonol profile differed significantly in the two seasons. Our results contribute to the better understanding of the role of flavonols in the antioxidant defense system of grapevine

Transcriptomic and biochemical investigations support the role of rootstock-scion interaction in grapevine berry quality

Background In viticulture, rootstock genotype plays a critical role to improve scion physiology, berry quality and to adapt grapevine (Vitis viniferaL.) to different environmental conditions. This study aimed at investigating the effect of two different rootstocks (1103 Paulsen - P - and Mgt 101-14 - M) in comparison with not grafted plants - NGC - on transcriptome (RNA-seq and small RNA-seq) and chemical composition of berry skin inPinot noir, and exploring the influence of rootstock-scion interaction on grape quality. Berry samples, collected at veraison and maturity, were investigated at transcriptional and biochemical levels to depict the impact of rootstock on berry maturation. Results RNA- and miRNA-seq analyses highlighted that, at veraison, the transcriptomes of the berry skin are extremely similar, while variations associated with the different rootstocks become evident at maturity, suggesting a greater diversification at transcriptional level towards the end of the ripening process. In the experimental design, resembling standard agronomic growth conditions, the vines grafted on the two different rootstocks do not show a high degree of diversity. In general, the few genes differentially expressed at veraison were linked to photosynthesis, putatively because of a ripening delay in not grafted vines, while at maturity the differentially expressed genes were mainly involved in the synthesis and transport of phenylpropanoids (e.g. flavonoids), cell wall loosening, and stress response. These results were supported by some differences in berry phenolic composition detected between grafted and not grafted plants, in particular in resveratrol derivatives accumulation. Conclusions Transcriptomic and biochemical data demonstrate a stronger impact of 1103 Paulsen rootstock than Mgt 101-14 or not grafted plants on ripening processes related to the secondary metabolite accumulations in berry skin tissue. Interestingly, theMYB14gene, involved in the feedback regulation of resveratrol biosynthesis was up-regulated in 1103 Paulsen thus supporting a putative greater accumulation of stilbenes in mature berries

Genome-Wide Identification of R2R3-MYB Genes and Expression Analyses During Abiotic Stress in

The R2R3-MYB is one of the largest families of transcription factors, which have been implicated in multiple biological processes. There is great diversity in the number of R2R3-MYB genes in different plants. However, there is no report on genome-wide characterization of this gene family in cotton. In the present study, a total of 205 putative R2R3-MYB genes were identified in cotton D genome (Gossypium raimondii), that are much larger than that found in other cash crops with fully sequenced genomes. These GrMYBs were classified into 13 groups with the R2R3-MYB genes from Arabidopsis and rice. The amino acid motifs and phylogenetic tree were predicted and analyzed. The sequences of GrMYBs were distributed across 13 chromosomes at various densities. The results showed that the expansion of the G. Raimondii R2R3-MYB family was mainly attributable to whole genome duplication and segmental duplication. Moreover, the expression pattern of 52 selected GrMYBs and 46 GaMYBs were tested in roots and leaves under different abiotic stress conditions. The results revealed that the MYB genes in cotton were differentially expressed under salt and drought stress treatment. Our results will be useful for determining the precise role of the MYB genes during stress responses with crop improvement

Discharge performance of blended salt in matrix materials for low enthalpy thermochemical storage

A novel study is undertaken on low cost thermochemical storage which utilizes temperatures which are compatible with low grade renewable energy capture. The discharge performance of thermochemical storage matrix materials is assessed using a custom developed experimental apparatus which provides a means of comparing materials under scaled reactor conditions. The basic performance of three salts (CaCl2, LiNO3 and MgSO4) was investigated and their subsequent performance using layering and blending techniques established that the performance could be increased by up to 24% through the correct choice of mixing technique. Layering the CaCl2 on the LiNO3 provided the most efficient thermal release strategy and yielded a thermal storage density of 0.2 GJ/m3. The research also uniquely highlights the important finding that incorrect mixing of the materials can lead to a significant reduction in efficiency with freely mixed CaCl2 and LiNO3 possessing a storage capacity of less than 0.01 GJ/m3 as a result of chemical interactions between the deliquesced materials in close proximity. The paper has impact for the design and control of thermochemical storage systems as it clearly identifies how performance can be improved or degraded by the choice and the structuring of the materials

Berry Flesh and Skin Ripening Features in Vitis vinifera as Assessed by Transcriptional Profiling

Background Ripening of fleshy fruit is a complex developmental process involving the differentiation of tissues with separate functions. During grapevine berry ripening important processes contributing to table and wine grape quality take place, some of them flesh- or skin-specific. In this study, transcriptional profiles throughout flesh and skin ripening were followed during two different seasons in a table grape cultivar ‘Muscat Hamburg’ to determine tissue-specific as well as common developmental programs. Methodology/Principal Findings Using an updated GrapeGen Affymetrix GeneChip® annotation based on grapevine 12×v1 gene predictions, 2188 differentially accumulated transcripts between flesh and skin and 2839 transcripts differentially accumulated throughout ripening in the same manner in both tissues were identified. Transcriptional profiles were dominated by changes at the beginning of veraison which affect both pericarp tissues, although frequently delayed or with lower intensity in the skin than in the flesh. Functional enrichment analysis identified the decay on biosynthetic processes, photosynthesis and transport as a major part of the program delayed in the skin. In addition, a higher number of functional categories, including several related to macromolecule transport and phenylpropanoid and lipid biosynthesis, were over-represented in transcripts accumulated to higher levels in the skin. Functional enrichment also indicated auxin, gibberellins and bHLH transcription factors to take part in the regulation of pre-veraison processes in the pericarp, whereas WRKY and C2H2 family transcription factors seems to more specifically participate in the regulation of skin and flesh ripening, respectively. Conclusions/Significance A transcriptomic analysis indicates that a large part of the ripening program is shared by both pericarp tissues despite some components are delayed in the skin. In addition, important tissue differences are present from early stages prior to the ripening onset including tissue-specific regulators. Altogether, these findings provide key elements to understand berry ripening and its differential regulation in flesh and skin.This study was financially supported by GrapeGen Project funded by Genoma España within a collaborative agreement with Genome Canada. The authors also thank The Ministerio de Ciencia e Innovacion for project BIO2008-03892 and a bilateral collaborative grant with Argentina (AR2009-0021). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

Thermal and calorimetric methods: application in the clean and renewable energies field

International @ ENERGIE+SBE:EML:AJH:AAUInternational audienceThe energy challenge imposed by exhaustion of fossil fuels and their increasing consumption has favoured the emergence of optimal energy management based on the use of intermittent energies produced starting from alternative resources such as solar, wind and geothermic energies. The problem to solve for the efficient use of these clean and renewable energies remains their storage and transportation. In the present work, three different research subjects based on storage and transportation of renewable energies are described. 1- In the first application the solar energy is applied to the building heating systems domain, where a good management of household thermal comfort nowadays implies the decrease in consumption of energy, while maintaining the same indoor temperature. This can be achieved through the use of thermo-chemical energy storage technology. Salt hydrates and their composites (obtained by incorporating the salt hydrates into a highly porous host matrix) have shown great potential as thermochemical heat storage materials. They can be utilized in applications such as providing heating in homes during winter (exothermic hydration of the solid material) by discharging the stored (solar) energy gained during the summer months (endothermic dehydration of the solid). For this aim, several composites were tested during hydration-dehydration in a TG-DSC apparatus. 2- The second application implies the combined use of solar and geothermic energies for house heating systems. In summer the thermal solar energy storage is achieved using water vapour absorption-desorption in binary or ternary systems with a desiccant salt like lithium bromide, lithium chloride, zinc bromide, zinc chloride, etc. The water vapour is condensed and stored in the water tank. The resulting more concentrated solution is stored in a semi crystallized form in a second tank. In winter, the previous condensed water is evaporated at low temperature, using geothermal source, and absorbed by the highly concentrated salt solution in the absorber, thus generating thermal energy. In this work, dissolution and dilution enthalpies of various anhydrous salts were determined by titration calorimetry. 3- The development of solid-state hydrogen storage materials with enhanced performances and improved safety is a key point for the commercialization of hydrogen as energy carrier. Mg hydride is one of the most promising materials for hydrogen storage. MgH2 presents low cost, high hydrogen capacity, light weight, abundance, excellent reversibility, and it is relatively safe to handle. To overcome the kinetic limitation and thermodynamic stability of MgH2, the addition of various activators has been tested by performing Pressure-Composition-Isotherm (PCI) experiments at different temperatures and temperature-programmed-desorption (TPD) measurements. Looking at the obtained results we can state that calorimetry and thermal analysis are necessary techniques in the renewable energy research field and that further developments and applications of these tools have to be expected in the very near future