50 ans d’independance : Quelle evolution de la situation du marche du travail en Algerie ?

Les analyses « standards » de la participation au marché du travail ne prennent pas en compte la dynamique de celui-ci et donc, les effets de cycle de vie, de génération et de cycle économique se confondent, ce qui affecte la précision des résultats obtenus et masque d’autres réa-lités sur le fonctionnement du marché du travail. Seules les analyses en cohorte permettent de décomposer et de mesurer ces trois effets. Les travaux empiriques sur le marché du travail en termes de cohortes sont plus nombreux dans les pays développés et les pays d’Amérique latine.Dans cet article, nous commencerons par donner un aperçu de l’évolution du marché du travail algérien depuis l’indépendance puis nous analyserons la participation au marché du travail au niveau des cohortes en  distinguant entre les hommes et les femmes. Pour cela, nous avons exploité différentes enquêtes emploi  réalisées auprès des ménages algériens par l’Office National des Statistiques de 1997 à 2007. Pour le  traitement des données, nous avons utilisé des techni-ques économétriques spécifiques pour les analyses par cohorte.Mots clés : Force de travail, Démographie, Analyse de cohorte

Etude phenomenologique sur la convection naturelle au dessus d’un disque rainure par voie optique

Parmi toutes les méthodes expérimentales, l’optique a toujours occupé une place de choix grâce à son caractère non intrusif : la traversée d’un écoulement par un faisceau lumineux n’entraine pas de perturbation dans les conditions requises par la visualisation ou la mesure. C’est ce qui explique l’importance de la technique que nous allons décrire. Cette étude vise la mise en place d'un banc d'essai en vue de visualiser et traiter numériquement la convection naturelle induite par un disque rainuré et chauffée par le bas dans un système ouvert. La méthode de visualisation choisie est l'ombroscopie comme méthode non intrusive afin de ne pas perturber la convection. Il est utile aussi de rappeler que cette dernière technique délivre en fait des images qu'il faudra lire et éventuellement traiter. Ainsi, dans pratiquement tous les cas de contrôle optique, il faut, pour obtenir des images reconstituées de bonne qualité et envisager une vision nette, mettre en oeuvre un système élaboré de traitement d'images. Ce système a pour premier but d'améliorer la qualité de l'image sur le plan du contraste et du niveau de bruit; il doit en seconde lieu très souvent prendre en compte la morphologie des objectifs recherchés afin de rendre l'image reconstituée parfaitement exploitable.Mots clés: Convection naturelle, Disque rainuré, Ombroscopie, Traitement d’image, thermographi

"Geological Setting/Cadre Géologique" in English and French Petrology Articles: Muted Indications of Explored Places

There has been considerable interest over the past 15 years in the scientific research article, its schematic structure and how it responds to discourse community expectations. While these features have been widely investigated in numerous disciplines, relatively scant attention has been paid to the important discipline of geology. Moreover, within the sub-discipline of petrology, we find a sub-section as yet unrecognized in the extensive literature on the research article. The 'Geological Setting' (GS), an introductory part-genre occurring before the onset of petrological analysis, is a multi-functional description which frames researchers' results within their geological context. Based on a corpus of 20 articles (10 in French and 10 in English), it is argued that this part-genre is not only a complex of the topography, geological history and characteristics of the research site, but also serves to establish the authors' credentials and authority as experts. This is accomplished not through agentive narratives marking the authors' presence on the site, but through more muted and indirect means. Similarities at the macro-level and general discourse structure are found in both the French and English texts, with important stylistic differences on a local level

On the dynamics of polyelectrolyte solutions

A general formalism to study the dynamics of polyelectrolyte solutions is presented. We show in particular that the Berne–Pecora equations for charged pointlike particles are obtained by neglecting the memory function and using the Debye–Huckel potential with the linear approximation exp(−U/kBT)≂1−U/kBT. We generalize Berne–Pecora results by introducing the effect of hydrodynamic interaction. Our calculations show a plasmon mode which corresponds to a nonzero frequency at zero scattering angle.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70342/2/JCPSA6-80-6-2762-1.pd

SANS From Tetradecylpyridinium Bromide Based Microemulsions

Small-angle neutron scattering is used to investigate tetradecyl pyridinium bromide/pentanol/heptane/heavy water microemulsions in the water-in-oil (W/O) microemulsion phase diagram region. The heavy water content is increased while the other components (surfactant, cosurfactant, hydrocarbon) are kept constant. With use of a simple model assuming spherical micelles interacting with a hard-sphere potential (Percus-Yevick model), aggregate sizes and packing fractions have been extracted and found to agree with values determined from the mixing conditions. These experiments clearly show the transition from the single-particle (heavy water + Stern layer droplet) scattering regime at low water concentration to the mixed single/interdroplet scattering regime when the intermicellar distance becomes comparable to the size of the micelles. © 1990 American Chemical Society

Distributed Document Clustering and Cluster Summarization in Peer-to-Peer Environments

This thesis addresses difficult challenges in distributed document clustering and cluster summarization. Mining large document collections poses many challenges, one of which is the extraction of topics or summaries from documents for the purpose of interpretation of clustering results. Another important challenge, which is caused by new trends in distributed repositories and peer-to-peer computing, is that document data is becoming more distributed. We introduce a solution for interpreting document clusters using keyphrase extraction from multiple documents simultaneously. We also introduce two solutions for the problem of distributed document clustering in peer-to-peer environments, each satisfying a different goal: maximizing local clustering quality through collaboration, and maximizing global clustering quality through cooperation. The keyphrase extraction algorithm efficiently extracts and scores candidate keyphrases from a document cluster. The algorithm is called CorePhrase and is based on modeling document collections as a graph upon which we can leverage graph mining to extract frequent and significant phrases, which are used to label the clusters. Results show that CorePhrase can extract keyphrases relevant to documents in a cluster with very high accuracy. Although this algorithm can be used to summarize centralized clusters, it is specifically employed within distributed clustering to both boost distributed clustering accuracy, and to provide summaries for distributed clusters. The first method for distributed document clustering is called collaborative peer-to-peer document clustering, which models nodes in a peer-to-peer network as collaborative nodes with the goal of improving the quality of individual local clustering solutions. This is achieved through the exchange of local cluster summaries between peers, followed by recommendation of documents to be merged into remote clusters. Results on large sets of distributed document collections show that: (i) such collaboration technique achieves significant improvement in the final clustering of individual nodes; (ii) networks with larger number of nodes generally achieve greater improvements in clustering after collaboration relative to the initial clustering before collaboration, while on the other hand they tend to achieve lower absolute clustering quality than networks with fewer number of nodes; and (iii) as more overlap of the data is introduced across the nodes, collaboration tends to have little effect on improving clustering quality. The second method for distributed document clustering is called hierarchically-distributed document clustering. Unlike the collaborative model, this model aims at producing one clustering solution across the whole network. It specifically addresses scalability of network size, and consequently the distributed clustering complexity, by modeling the distributed clustering problem as a hierarchy of node neighborhoods. Summarization of the global distributed clusters is achieved through a distributed version of the CorePhrase algorithm. Results on large document sets show that: (i) distributed clustering accuracy is not affected by increasing the number of nodes for networks of single level; (ii) we can achieve decent speedup by making the hierarchy taller, but on the expense of clustering quality which degrades as we go up the hierarchy; (iii) in networks that grow arbitrarily, data gets more fragmented across neighborhoods causing poor centroid generation, thus suggesting we should not increase the number of nodes in the network beyond a certain level without increasing the data set size; and (iv) distributed cluster summarization can produce accurate summaries similar to those produced by centralized summarization. The proposed algorithms offer high degree of flexibility, scalability, and interpretability of large distributed document collections. Achieving the same results using current methodologies require centralization of the data first, which is sometimes not feasible

Dynamics of Diblock Copolymers in Dilute Solutions

We consider the dynamics of freely translating and rotating diblock (A-B), Gaussian copolymers, in dilute solutions. Using the multiple scattering technique, we have computed the diffusion and the friction coefficients D_AB and Zeta_AB, and the change Eta_AB in the viscosity of the solution as functions of x = N_A/N and t = l_B/l_A, where N_A, N are the number of segments of the A block and of the whole copolymer, respectively, and l_A, l_B are the Kuhn lengths of the A and B blocks. Specific regimes that maximize the efficiency of separation of copolymers with distinct "t" values, have been identified.Comment: 20 pages Revtex, 7 eps figures, needs epsf.tex and amssymb.sty, submitted to Macromolecule