Essai sur les déterminants empiriques de développement des marchés obligataires

Based on the methodology adopted by Eichengreen and Luengnaruemitchai (2004), Luengnaruemitchai and Ong (2005), Borensztein and al. (2006), and Eichengreen and al. (2006), this study analyse the development of local bond markets. We show that the development of bond markets is a phenomenon with multiple dimensions. The contribution of our study is threefold. First, we do not limit our analysis to Asian and Latin-American emerging countries, we consider although countries from the Middle East and Africa according to data availability. Then we introduce other factors to better understand the development of bond markets. Finally, we present a dynamic version of the determinants of bond market development.Bond markets, economic factors, institutional factors, economic policy, dynamic panel data, GMM system

Symbiotic and phylogenetic diversity of rhizobia associated with native and introduced Acacias in Algeria

In the arid zones were crop production is reduced due to drought combined to low soil fertility, the use of symbiotic native legume trees adapted to such harsh conditions could enhance the productivity of agroforestry systems. In North Africa, Acacia species are good candidates for this purpose since they can grow on N-deficient soils and improve their N balnce due to their symbiotic association with rhizobia, nitrogen-fixing soil bacteria. In order to identify and select. Efficient acacia-rhizobia symbiotic associations, soil samples and root nodules from seven Acacia species, five native (A ehrenbergiana, A laeta, A. niIotica, A. seyal, A. tortimis) and two introduced (A. karroo, A. saligna). were collected in arid and semi-arid regions of Algeria from Oran to Tamanrasset. A collection of 22 bacteria1 strains was obtained after trapping on Acacia seedlings inoculated with soil samples originating from nine geographic sites. 16S rDNA sequencing revealed that the new strains represented different species in Sinorhizobium and Rhizobium. This genetic diversity was confirmed by phenotypic characterisation through biochemical assays and host spectrum. Some strains were particularly tolerant to low pH and high NaCl concentrations. temperature and osmotic stress in vitro conditions. In a next step, selection of efficient rthizobia displaying a high nitrogen-fixing potential under stress conditions will be carried out in controlled conditions before testing them in field conditions. (Texte intégral

Valorisation of legume nodulating bacteria diversity for degraded arid and saline Algerian land restoration

In Algeria soils available for agriculture are limited by salinity and drought. In this country there is a need for plant production improvement to face the increasing demand for human food and fodder. The global strategy for saline and degraded areas restoration includes the use of plant species developing nitrogen-fixing symbioses well adapted to these constraints, especially legumes. In this study plant and soil samples originating from arid and saline regions were collected all around the country. 72 bacterial nodule isolates were obtained and characterised phenotypically and genotypically. Their salinity tolerance was tested on YEM medium and 23 of them tolerated 800mM NaCl. The growth kinetics of the most tolerant strains was determined on M9 medium added with either 600mM or 800mM NaCl. AIl strains were tested for nodulation and nitrogen fixation with their host plants in standard tube conditions. After 16SrDNA sequencing, isolates were affiliated to Sinorhizobium, Rhizobium, Agrobacterium, Phyllobacterium and Bradyrhizobium. Some of them, forming a separate group possibly representing a new species in Rhizobium were further characterised by Multi Locus Sequence Analysis (MLSA) of five housekeeping genes and by auxanographic tests. Three S. medicae and two S. meliloti strains were selected for their efficiency and tolerance to NaCI in vitro and further tested as inoculants for the growth of Medicago ciliaris and M. polymorpha, the two dominant forage legumes in arid and saline regions of Algeria. The effectivity of strains was estimated by measuring ARA and plant aerial part dry weights with statistical treatments of data. Tests were performed both in a greenhouse and in open field located in a semi-arid region, South-Western part of Algeria. (Texte intégral

Technical advances in the design and deployment of future heterogeneous networks

The trend in wireless communications systems is the enhancement of the network infrastructure with the introduction of small cells, where a specific geographical area is served by low-range, low-power access points. The result is the creation of a heterogeneous topology where macrocells coexist with a variety of small-cell types. In this editorial article we briefly summarize the recent technical advances in the design and deployment of future heterogeneous networks addressed in the papers that compose this special issue. In particular the following aspects are considered: the design of interference and radio resource management algorithms, the analysis of the energy efficiency and power control issues in heterogeneous networks, the concept of coordination in small cell networks, key backhaul aspects of HetNets, deployment issues and overall management strategies.Peer ReviewedPostprint (published version

Does The Expectations Hypothesis Explain The Term Structure Of Treasury Bond Yields In Tunisia?

This paper tests the expectations hypothesis (EH) using monthly data for Treasury bond yields (TBYs) over the period 1994m5–2014m12 and ranging in maturity from one year to 10 years. We apply cointegrated-VAR jointly on more than one pair of yields. The results suggest rejection of the EH throughout the medium maturity spectrum. However, for longer maturities they suggest the validity of the EH for the TBYs. This indeed confirms the smooth functioning of Tunisian bond market which gives an indication that the yield curve should serve as an indicator to the monetary policymakers to manage inflation and to influence the aggregate demand in the economy.

Experimental characterization of clay soils behavior stabilized by polymers

In this work, we propose to use both PVC and HDPE polymers such additions in cohesive soils to determine their influence on the physical and mechanical properties of soil-polymer material in function of time, which should insure some optimal period of life. For this purpose, different tests including Atterberg Limits, standard compaction, swelling potential, and swelling pressure, were conducted on control and treated soil samples using different Percentage of Polymer (PVC and HDPE) (0, 3 and 6%). Also California Bearing Ratio (CBR) tests were conducted on control and treated samples. The results showed that soil treatment with PVC and HDPE, resulted in improvement of CBR and maximum dry density and reduction in Atterberg Limits, swelling potential and swelling pressure. The addition of a small percentage of polymer causes initially at (t =0 sec) an instantaneous of deformation (elastic response), followed by a time-dependent deformation with the speed of the increasing deformation.Keywords: Mechanic; Polymer; Expansive clay; Optimum; Compressibilit

Prediction of Compressive Strength of Self-Compacting Concrete (SCC) with Silica Fume Using Neural Networks Models

Self-Compacting Concrete (SCC) is a relatively new type of concrete with high workability, high volume of paste and containing cement replacement materials such as slag, natural pozzolana and silica fume. Cement replacement materials provide a wide variety of benefits such as lower cost, reduced consumption of natural resources, reduced carbon dioxide emissions and improved fresh and hardened properties. SCC is used in many applications such as sections with congested reinforcement and high rise shear walls and there is a need for the prediction of the performance of SCC used. Artificial Neural networks (ANN) are widely used in civil engineering for the prediction of the performance of some engineering materials such as compressive strength and durability. However, currently, studies on SCC containing silica fume are very rare. In this paper, an artificial neural networks (ANN) model is developed to predict the compressive strength of SCC with silica fume using the Levenberg-Marquardt back propagation algorithm based on a database from 366 experimental studies. The model developed was correlated with a nonlinear relationship between the constituents (input) and the compressive strength of SCC (output). To evaluate the predictive ability and generalize the developed model, other researchers’ experimental results were compared with the model prediction and good agreements are found. A parametric study was conducted to study the sensitivity of the ANN proposed model to some parameters such as water/binder ratio and superplasticizer content. The model developed in this study can potentially be used for SCC compressive strength prediction with very acceptable results and a high correlation coefficient R2=0.93. The developed model is practical, easy to use and user friendly. Doi: 10.28991/cej-2021-03091642 Full Text: PD

Prediction of Efficiency Factor of Natural Pozzolan by the Use of an Artificial Neural Network

Because of the abundance of the mineral additives and the great variations on their physical and chemical characteristics, the development of a general concept for their use out of concrete is required. In this study, the concept of the efficiency factor is applied like a measurement of the relative performance of these materials compared with Portland cement. The rapid growth of the artificial intelligence had a very important impact on the concrete technology.  It makes it possible to solve complex prediction problems of the properties of the concretes with cementitous materials (slag, fly-ashes, silica fume and natural pozzolan). The main aim of this study is to test the validity of the approach of Artificial Neural Networks (ANN) in developing a model for the prediction of the natural pozzolan efficiency factor. The most suitable model is the feed-forward multi-layer network. It is produced to implement the complexity of the nonlinear relation between the data network (the Water/Binder ratio “”, the percentage of pozzolan and the age of testing) and the produced result (the efficiency factor). It is also established by an incorporation of a large experimental database and by a suitable choice of architecture and the training process. The model was validated by experimental tests. The ANN Model developed provided effective means for the formulation of the concretes containing natural pozzolan for a given water binder ratio (W/B), an age of testing (t) and a rate of substitution of natural pozzolan (P)

Stratégies de l’écriture de l’entre-deux dans Du rêve pour les oufs de Faiza Guene

Résumé: Le présent article vise à mettre en lumière la parole de la deuxième génération des femmes algériennes immigrées. Dans « Du rêve pour les oufs », Faiza Guène relate l’histoire de la jeune Ahlème, qui tente de se frayer un chemin dans une société où la coexistence n’est pas facile pour une jeunesse confrontée au dédoublement culturel. Ce texte issu de l’immigration rime avec « mouvance beure » et double appartenance stéréotypée. Il nous invite à réfléchir, sur les stratégies d’écriture mises au service de la parole des immigrés. Une écriture œuvrant pour l’abolition de toutes formes de discrimination et revendiquant une insertion respectueuse. Un choix thématique et un renouvellement des modes d’expression se fait remarquer dans le roman témoignant d’une volonté indubitablement revendicative. Mots-clés : immigration ; stratégie d’écriture ; stéréotype ; ironie ; emprunt lexica