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See detailAbundance determination in massive stars: challenges for mixing processes
Cazorla, Constantin ULiege

Doctoral thesis (2017)

Massive stars, the most luminous stars, are the true “cosmic engines” of our Universe. They eject large quantity of material throughout their life, which strongly influences their evolutionary path as ... [more ▼]

Massive stars, the most luminous stars, are the true “cosmic engines” of our Universe. They eject large quantity of material throughout their life, which strongly influences their evolutionary path as well as their environment. An important feature of massive stars is their high rotational velocities that are either acquired at birth or due to the influence of a companion. Rotation is believed to transport nitrogen-rich and carbon/oxygen-poor material generated in the stellar core through the CNO cycle, to the surface. A way to test the e ciency of rotational mixing is to study the chemical composition at the surface of stars, in particular the fastest rotators. The incentive for this study was the discovery, in the context of the VLT- FLAMES Survey of Massive Stars, of fast rotators exhibiting an unenriched nitrogen composition at their surface, contrary to predictions from single-star evolutionary models including rotation. However, their multiplicity may a ect this conclusion, since both rotation and abundances can change as a result of binary interactions. In this work, we combined, for the first time, a detailed surface abundance analysis with a radial-velocity study to quantify the importance of binary e ects. This work was conducted for a sample of 40 bright, OB fast rotators in our Galaxy. Statistical tests and period-search techniques revealed that ≥ 40% of our targets whose multiplicity status can be probed, are binary or binary candidates. We derived the projected rotational velocity of our targets and model atmosphere codes were then used to derive stellar parameters and surface abundances of all sample stars. This abundance study revealed a correlation between the helium and nitrogen abundances of our targets, which is predicted by the rotational mixing theory. Finally, we compared our results to predictions of single-star evolutionary models. We found that 10 – 20% of our 40 targets exhibit no enhancement of the [N/O] abundance ratio, in line with results of the VLT-FLAMES Survey of Massive Stars. The properties of only half of our sample are explained by such models, and surprisingly we also uncovered a quite common large abundance of helium at the surface of our targets. Modifying the di usion coe cient in single-star models and models of non-rotating mergers did not reproduce simultaneously both the observed helium abundances and the [N/O] abundance ratios. Binary models considering a mass-transfer episode can, however, reproduce the [N/O] values of the majority of our targets and even the helium abundances of some of the most helium-enriched targets, but they cannot explain stars displaying little helium enrichment but high [N/O] values. In conclusion, we found that not every feature of massive stars can be explained by models, suggesting that they lack a physical ingredient and thus require further improvements. The second part of this thesis aimed at improving our knowledge of the X-ray emission of early B-type stars. We studied 11 such stars at high resolution thanks to two X-ray facilities, XMM-Newton and Chandra, doubling the number of B-stars analysed at high resolution. In many aspects, our study confirmed previous ones: early B-stars display rather narrow and unshifted lines arising from a warm (of typically 0.2 – 0.6 keV) plasma located at a few stellar radii over the stellar surface. We also found that abundances derived in the X-ray domain are in fair agreement with photospheric ones derived in the optical domain. Furthermore, most early B-stars are moderately bright X-ray emitters – though we also unexpectedly found that this X-ray emission varies, on short and/or long timescales, for half of our sample. A few stars display peculiar features: the presence of a very hot (1.6 – 4.4 keV) component and strong variations. These features suggest that the recorded X-ray emission may not be entirely linked to the B-stars, but could be contaminated by emission from a companion or an interaction with it. Indeed, in one case, HD 79351, a flare was detected, of a luminosity compatible with those from PMS stars, and which could be associated to its companion. Finally, the data used also led to the discovery of the second case of X-ray pulsations associated to beta Cephei activity. [less ▲]

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See detailHollow Nanoparticles for Low Cost, High Activity and Durability for the Oxygen Reduction Reaction for Fuel Cell Applications
Asset, Tristan ULiege

Doctoral thesis (2017)

This Ph.D. thesis investigates the mechanisms driving the formation, the enhanced activity for the oxygen reduction reaction (ORR) and the durability of porous hollow PtM/C nanoparticles (NPs) for proton ... [more ▼]

This Ph.D. thesis investigates the mechanisms driving the formation, the enhanced activity for the oxygen reduction reaction (ORR) and the durability of porous hollow PtM/C nanoparticles (NPs) for proton ex-change membrane fuel cell (PEMFC) applications. The formation and growth of the NPs, synthesized by a ‘one-pot’ process, were discussed in the light of microscopic, operando X-ray and electron-based tech-niques, unveiling the different intermediate steps of the synthesis. The synthe-sis process was extended to different non-noble metals (M = Ni, Co, Cu, Zn and Fe) and to different carbon supports. The enhanced activity for the ORR resulted from (i) the contraction of the lattice pa-rameter by the non-noble metal (the final NPs contains ca. 15 – 20 at. % of M), (ii) the open porosity and (iii) the density of structural defects at the surface of the NPs, which was semi-quantitativey estimated by COads stripping measurements and Rietveld analysis of wide-angle X-ray scattering patterns. The non-noble metal was found to be annealed (dissolved) faster than the structural defects during the accelerated stress tests. [less ▲]

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See detailDe la R&D à la mise sur le marché de produits industriels, évolutions de la recherche au service des entreprises
Blecker, Christophe ULiege

Conference (2017, September 26)

Ce séminaire retrace par des exemples concrets de développement de produits l'évolution des interactions entre le secteur alimentaire et la recherche fondamentale et appliquée. L'objectif est de mettre en ... [more ▼]

Ce séminaire retrace par des exemples concrets de développement de produits l'évolution des interactions entre le secteur alimentaire et la recherche fondamentale et appliquée. L'objectif est de mettre en avant l'apport de certaines méthodes de travail pour obtenir un partenariat entreprises-centres de recherche optimal. Pour conclure, il présente les principaux résultats de recherche dont son domaine dont les entreprises pourraient trouver un intérêt. [less ▲]

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See detailDiez preguntas para auto-evaluar el perfil de egreso, el Programa y los cursos en una perspectiva de ABC (Aprendizaje Basado en Competencias) y con enfoque programa en la Ensenanza superior.
Leclercq, Dieudonné ULiege

in Garcia-Calderon, Leandro (Ed.) La evaluacion de competencias en la Educacion Superior (2017)

Actualmente las universidades estructuran sus perfiles de egreso, programas y cursos aplicando dos principios esenciales: (1) el Aprendizaje Basado en Competencias o ABC y (2) el Enfoque Programa. En la ... [more ▼]

Actualmente las universidades estructuran sus perfiles de egreso, programas y cursos aplicando dos principios esenciales: (1) el Aprendizaje Basado en Competencias o ABC y (2) el Enfoque Programa. En la presente ponencia se analiza las significaciones e implicaciones de estas expresiones, así como el impacto que tienen sobre las evaluaciones en estos tres niveles. Además se presentan algunas preguntas clave que los docentes pueden (deben) hacerse para autoevaluar sus logros en cada nivel; proceso permanente porque los currículos viven y se trasforman para adaptarse a los cambios en el mundo o para inducirlos. Cada una de las preguntas de autoevaluación se explican en detalle, con conceptos y ejemplos, en el libro Ideas e Innovaciones, Dispositivos de Evaluación de los Aprendizajes en la Educación, o IDEAS (Leclercq y Cabrera, 2014), escrito con la contribución de 16 autores. Para ilustrar lo que se puede hacer al evaluar, en el capítulo 3 de IDEAS, se usa una rosa de los vientos —motivo de la línea gráfica de este encuentro—, la cual describe lo existente o aquello que podría ser. Entre todas estas posibilidades, esta ponencia, presenta aquello que, desde mi punto de vista, se debe hacer. Las preguntas servirán para abordar sucesivamente la estructura de un currículo, la cual puede concebirse como un cubo, que en su cara frontal (dimensión horizontal), contiene a los tres pilares de la formación, siendo el pilar central el de los objetivos o del perfil de egreso, el cual puede articularse en cuatro pisos (dimensión vertical) llamados DIME (competencias Dinámicas, Instrumentales, Metacognitivas y Específicas); el pilar izquierdo representa los métodos y el derecho, las evaluaciones. En este esquema, las evaluaciones a las que puede someterse una propuesta curricular, se sitúan en cuatro niveles de profundidad o de amplitud temporal. El ABC implica que son los docentes, trabajando en equipos, los que deben concebir instrumentos para evaluar desempeños complejos. Se explicará por qué un Enfoque Programa es imprescindible para (1) Concebir situaciones reales o simuladas que agrupen saberes, destrezas y actitudes, (desarrollados en varios cursos), y cómo los docentes, sin perder de vista las competencias (concordancia vertical), pueden preparar a los estudiantes para esto. (2) Que cada curso (o cada actividad de enseñanza-aprendizaje) evidencie la Triple Concordancia entre Objetivos, Métodos y Evaluaciones (concordancia horizontal). Aquí, los criterios de calidad de las evaluaciones serán sólo mencionados, porque los ejemplos de sus aplicaciones a casos concretos se darán en la ponencia de Álvaro Cabrera. Finalmente, expondré lo que es el currículo oculto y cómo combatirlo. Ver documento atado. [less ▲]

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See detailDu réel qui toujours déborde. Réalité, fiction et usages dans l'oeuvre d'Olivia Rosenthal
Huppe, Justine ULiege

Scientific conference (2017, September 26)

Plan: I. Une écologie politique et poétique II. Le tournant pragmatiste des études littéraires III. Investigation, imitation et identification : des pouvoirs cognitifs de la fiction IV. User de la fiction ... [more ▼]

Plan: I. Une écologie politique et poétique II. Le tournant pragmatiste des études littéraires III. Investigation, imitation et identification : des pouvoirs cognitifs de la fiction IV. User de la fiction, ou pratiquer le réel par ses détours [less ▲]

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See detailWho Cares for Those Who Cared? An Intersectional Ethnography of Global Social Protection Arrangements
Vivas Romero, Maria ULiege

Doctoral thesis (2017)

How and through which repertoires of practices do migrant domestic workers access global social protection? And how do their gender, race, class, and generational positioning along with their ... [more ▼]

How and through which repertoires of practices do migrant domestic workers access global social protection? And how do their gender, race, class, and generational positioning along with their transnational family relations affect this access? This dissertation deals with these questions and focuses on the case of Peruvian and Colombian Migrant Domestic Workers in the city of Brussels. Such migrants share a paradoxical positioning as they contribute productively and reproductively to the development of their receiving and sending societies but experience a lack of formal and informal social protection on both sides. This analysis first maps through a multi-sited ethnography the repertoire of practices they use to strategize their access to Social Protection in the areas of: 1- old-age and survivors benefits, 2- incapacity, 3- health & family, 4- active labor market programs, 5- unemployment, 6-housing, and education, 7- community and family support. Secondly, it theorizes these practices as Global Social Protection Arrangements that are simultaneously made out of transnational interpersonal relationships and formal support systems. Thirdly, building from the work of Anthias (2016) a Translocations lens is used to analyze how these actor’s gender, race, class, religious and generational positioning within the global reproduction of labor as well as within their transnational family networks simultaneously affect the functionality of such arrangements. Concluding, it’s argued that more privileged migrant domestic workers will use arrangements composed mostly of formal resources, while less privileged ones will see formal avenues less open to them and therefore have to rely on an informal arrangement. Far, from the rights based normative approach to social protection, this thesis provides a glance at how transnational access to social protection is strategize across borders. Furthermore, it’s relevant in a context of increasing human mobility where inequalities in access to social protection emerge as a public transnational social question (Faist, 2016) that is suitable both for academics and policy makers. [less ▲]

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See detailBioaccumulation des métaux traces dans les organes la moule Mytilus galloprovincialis de la région ouest algérienne
Rouabhi, Yamina Leila; Rouane-Hacene, Omar; Grosjean, Philippe et al

Scientific conference (2017, September 26)

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See detailPetit pays, grand(s) cinéma(s). Un panorama du cinéma belge.
Hamers, Jérémy ULiege

Conference given outside the academic context (2017)

On ne cesse de le dire et de l’écrire: le cinéma belge a, depuis quelques années, le vent en poupe. Les frères Dardenne, Jaco Van Dormael, Bouli Lanners, Michael Roskam ou encore Felix Van Groeningen ... [more ▼]

On ne cesse de le dire et de l’écrire: le cinéma belge a, depuis quelques années, le vent en poupe. Les frères Dardenne, Jaco Van Dormael, Bouli Lanners, Michael Roskam ou encore Felix Van Groeningen: autant de cinéastes dont la presse internationale se plaît à souligner la « belgitude », rarement définie toutefois. En dressant un rapide panorama du cinéma belge, de ses courants et de ses tendances depuis l’avènement du cinéma parlant, cette mini-conférence resitue les succès contemporains de notre cinéma dans l’histoire riche et passionnante du 7e art belge. [less ▲]

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See detailThe EP’s ‘European Standards’ Resolution in the wake of James Elliott Construction: carving ever more holes in Pandora’s Box?
Van Cleynenbreugel, Pieter ULiege; Demoulin, Iris ULiege

E-print/Working paper (2017)

This blogpost analyses a recent Parliamentary resolution against the background of the Court of Justice's James Elliott Construction judgment, dealing with the legal nature of harmonised technical ... [more ▼]

This blogpost analyses a recent Parliamentary resolution against the background of the Court of Justice's James Elliott Construction judgment, dealing with the legal nature of harmonised technical standards in EU free movement law. [less ▲]

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See detailEjection Fraction May Not Reflect Contractility: Example in Veno-Arterial Extracorporeal Membrane Oxygenation for Heart Failure
MORIMONT, Philippe ULiege

in ASAIO Journal (American Society for Artificial Internal Organs : 1992) (2017)

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See detailExperimental study of methods to increase the shielded volume in passive superconducting magnetic screens
Wera, Laurent ULiege

Doctoral thesis (2017)

This thesis is dedicated to the experimental study of methods to increase the shielded volume in passive magnetic shields made of high temperature superconductors (HTS). Two main approaches are ... [more ▼]

This thesis is dedicated to the experimental study of methods to increase the shielded volume in passive magnetic shields made of high temperature superconductors (HTS). Two main approaches are investigated. The first approach is to study how the size of the shield can be increased. The second is to study how the shielded volume can be extended in a shield of given size. In the first approach, we study how large-scale or scalable magnetic shields could be obtained. Scalability means the possibility of building magnetic shields of various dimensions by keeping the same fabrication technique. First, we study in detail the shielding properties and the behaviour of shields made as an assembly of superconducting coated conductor loops, obtained from second generation superconducting YBa2Cu3O7 coated conductor tapes that are commercially available. We show that such shields are an excellent alternative to bulk magnetic shields for shielding large volumes and fields of the order of 50 mT at 77 K. Different dimensions can be easily obtained by adapting the number and the length of the coated conductor tapes. This technique is shown to be very promising for building easily large size magnetic shields. However, unlike bulk magnetic shields, the shielding efficiency decreases rapidly when the applied field is no longer parallel to the main axis of the shield. The results in these configurations are analyzed to investigate the role played by the peculiar eye-shape cross-section of the shield on the various shielding current loops. We show that in the transverse field configuration, the structure can be used to locally modify the direction of the applied field. Finally, we take advantage of the scalability of such shields to build and study a triaxial structure that is able to attenuate a magnetic field of arbitrary orientation. Next we study the superconducting properties and the shielding efficiency of YBa2Cu3O7 superconducting tubes made by two distinct fabrication techniques allowing large-scale or scalable magnetic shields to be obtained. The first technique is the electrophoretic deposition (EPD) which consists in the deposition of a superconducting thick-film (about 100 μm thick) on a metallic substrate. Compared to previous studies, our results show an improvement of the shielding properties and open encouraging prospects for a future development of magnetic shields made by EPD. For the second technique, the shield is obtained by the pulsed-laser deposition (PLD) of a superconducting thin layer (about 1 μm thick) on a textured metallic substrate. In the case where a continuous layer (i.e. joint-free) has been deposited successfully, we show that the persistent current flowing in the superconducting layer has a critical current density close to that of the commercial YBa2Cu3O7 coated conductor tapes, and point out the similarities with the coated conductor structures studied previously. We also consider a similar material containing joints and compare their impact on the magnetic shielding in various configurations (DC/AC, axial/transverse). The results highlight the profound impact of nΩ level joint resistances on the superconducting shielding. For the second approach used in this thesis, we study how to increase the shielded volume in HTS bulk magnetic shields of given dimensions. In the case of non-textured polycrystalline superconductors (Bi2Sr2Ca2Cu3O10 commercial tubes), we analyse the improvements resulting from closing one or both ends of a tube by a cap made of the same material. In this configuration the joint between the cap and the tube is non-superconducting. Numerical simulations are used to see how the volume can be further increased by increasing the thickness of the cap or increasing its critical current density. Then, we study the shielding efficiency of a melt-textured bulk YBa2Cu3O7 superconducting tube closed at one extremity with a cap in which the joint between the cap and the tube is superconducting. Our results show that such a tube can shield axial fields in excess of 1 tesla at 20 K and is therefore useful for shielding small volumes against high magnetic fields. The beneficial effect of a cap is also studied in the transverse field configuration. We show experimentally and with help of numerical simulations that, in this case, the superconducting character of the joint between the tube and the cap is mandatory. In addition to the increase of the shielded volume, this thesis also addresses another problem relevant to future shielding applications. We investigate experimentally the effect of a magnetic field trapped initially in a bulk HTS hollow cylinder on its shielding performances. In the studied configurations, the initial applied field and the field to be shielded are mutually orthogonal. Remarkably the shielding properties are not affected provided the flux lines have not reached the inner hollow part of the cylinder. A trapped field inside the shield, however, is found to affect the threshold induction significantly. We then study how to efficiently demagnetize the superconducting tube without heating it above its critical temperature. By applying a single demagnetization cycle of adequate amplitude, we show that the initial shielding properties can be recovered. [less ▲]

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See detailThe weapon system behind the point: Early Gravettian hunting technologies at Maisières-Canal
Taipale, Noora ULiege; Coppe, Justin ULiege; Touzé, Olivier ULiege et al

Conference (2017, September 23)

Hunting and preparing for the hunt – manufacturing, using, and repairing the equipment – were undoubtedly important and time-consuming activities in the lives of Palaeolithic groups [1, 2]. Studying ... [more ▼]

Hunting and preparing for the hunt – manufacturing, using, and repairing the equipment – were undoubtedly important and time-consuming activities in the lives of Palaeolithic groups [1, 2]. Studying hunting equipment in detail is thus essential for our understanding of a crucial aspect of Palaeolithic human behaviour and allows us to understand developments in human technologies and problem-solving across wide geographical and chronological ranges. Yet, our current knowledge about the development of prehistoric hunting technologies (projecting modes, weapon design) is mainly based on a few important but isolated discoveries of organic remains in Europe, such as the Lower Palaeolithic spears or spear fragments recovered at Schöningen, Lehringen, and Clacton-on-Sea, the Solutrean and Magdalenian spear-thrower hooks, and the arrows and bow fragments from Mesolithic and Neolithic contexts [3]. In this paper we demonstrate how to exploit the full potential of a much more durable and ubiquitous type of remains, lithic armatures, in the study of Palaeolithic hunting practices. We present the results of a collaborative project that combines technological and functional analysis with experimental archaeology, and aims at understanding the manufacture and use of a specific lithic projectile type, the Early Gravettian tanged point. Our archaeological material comes from the Gravettian occupation phase of the open-air site of Maisières-Canal (Belgium), dated between 33 and 32 cal BP [4]. This stratigraphically well-isolated sequence has yielded an important collection of tanged points that are in excellent state of preservation. A combined study of the finished armatures and the related shaping waste allows us to present a new, more comprehensive view of the characteristics and constraints of the shaping method. The points were made on large, thin blades produced by hard or soft stone percussion, and subsequently shaped by several generations of direct, flat, invasive (sometimes overshot) removals with an organic hammer. These points, which all display a long, elaborately shaped tang, thus form a distinct tool type with a unique chaîne opératoire and a very particular morphology in terms of weapon design and hafting systems. Many of the points show clear macroscopic and microscopic damage from impact that can be attributed to their use as armatures. The morphology, the organisation, and the orientation of the traces allowed us to propose specific hafting modes that were tested experimentally. The experimental program focused on both the details of the hafting mode and the mode of projection. In addition, alternative tool uses such as butchering were considered, and the points were framed within the broader functional context of tanged and non-tanged tools recovered at the site. The results allow evaluating what kind of weapon system the tanged points were part of, and what their place was in the Early Gravettian technology. We argue that when approached from an experimental and techno-functional point of view, lithic projectile points can help us understand the development of hunting technologies as well as broader patterns of technological change. References:[1] Ellis, C.J., 1997. Factors influencing the use of stone projectile tips. In: Knecht, H. (Ed.), Projectile Technology. Springer Science & Business Media, pp. 37–74 [2] Greaves, R ., 1997. Hunting and multifunctional use of bows and arrows. In: Knecht, H. (Ed.), Projectile Technology. Springer Science & Business Media, New York, pp. 287–320 [3] Knecht, H., 1997. Projectile technology. Springer Science & Business Media, New York [4] Jacobi, R. M., Haesaerts, P., Jadin, I., Basell, L.S., 2010. Radiocarbon chronology for the Early Gravettian of northern Europe: new AMS determinations for Maisières-Canal, Belgium. Antiquity 84 (323), 26–40 [less ▲]

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See detailLes enjeux didactiques de la mobilité étudiante en Francophonie : état des lieux et perspectives
Meunier, Deborah ULiege

Conference (2017, September 23)

En quoi les programmes de mobilité étudiante universitaire obligent-t-ils à repenser la didactique des langues et des cultures, ses objectifs, ses ambitions, ses conditions d’existence, ses modes ... [more ▼]

En quoi les programmes de mobilité étudiante universitaire obligent-t-ils à repenser la didactique des langues et des cultures, ses objectifs, ses ambitions, ses conditions d’existence, ses modes d’expression locaux ? Quelles sont les spécificités de l’enseignement-apprentissage du français à/par ces étudiants en séjour dans des universités francophones ? Après une brève mise en contexte sociohistorique de la mobilité étudiante, en particulier en Francophonie, nous proposerons, d’une part, un état des lieux des recherches sur l’enseignement du français pour ce public d’étudiants universitaires nomades et plurilingues, et, d’autre part, quelques résultats de nos recherches passées et en cours. L’objectif de cette communication sera de présenter des pistes susceptibles de pallier le vide pédagogique et les difficultés rencontrées par les enseignants et les étudiants mobiles. Ce public d’apprenants, à la fois « exigeant et fuyant » (Anquetil, 2011), nécessite des ajustements, des dispositifs, des méthodes à la fois pluriels et spécifiques, dont nous tracerons les lignes principales. Notre intervention bénéficiera d’un triple éclairage : celui de la littérature scientifique récente (notamment les travaux de chercheurs publiés dans un numéro du Langage et l’Homme, à paraitre en juin 2017, que nous coordonnons) ; de notre recherche doctorale sur les représentations des acteurs (institutions et étudiants) à propos de la mobilité étudiante en Europe et des langues, en particulier du français (2013) ; et enfin, d’une recherche actuelle que nous menons sur les compétences écrites en français d’étudiants universitaire non francophones, débutée en 2016 à l’université de Sherbrooke, au Québec. [less ▲]

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See detailConférence d'ouverture : La morale de 1964 : une écriture en débats
Cormann, Grégory ULiege; Bourgault, Jean

Conference (2017, September 22)

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See detailPlantes pesticides et protection des cultures maraichères en Afrique de l’Ouest (synthèse bibliographique)
Yarou, Boni Barthélémy ULiege; Silvie, Pierre; Assogba Komlan, Françoise et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2017), 21(4), 288-304

Introduction. Les cultures maraichères occupent une place importante pour l’alimentation humaine et contribuent significativement aux revenus des familles en Afrique de l’Ouest, mais leur production est ... [more ▼]

Introduction. Les cultures maraichères occupent une place importante pour l’alimentation humaine et contribuent significativement aux revenus des familles en Afrique de l’Ouest, mais leur production est confrontée à une pression des bioagresseurs qui limite leur productivité. Littérature. Cette revue, basée sur des publications scientifiques, a pour objectif d’évaluer le potentiel des plantes pesticides comme alternative à l’usage des pesticides de synthèse pour lutter contre les bioagresseurs des cultures maraichères en Afrique de l’Ouest. Elle montre que le principal moyen actuel pour combattre ces bioagresseurs repose essentiellement sur les pesticides de synthèse. Cependant, compte tenu de leur nocivité sur l’homme et l’environnement, en plus de la sélection de populations résistantes chez les bioagresseurs, la recherche de solutions alternatives s’impose. Les plantes pesticides se présentent comme une alternative prometteuse dans le contexte ouest-africain. En effet, diverses espèces de plantes pesticides peuvent être utilisées comme extraits de plantes ou en association avec d’autres cultures pour le contrôle des bioagresseurs. Celles-ci sont présentées dans le présent article de synthèse. Conclusions. Les plantes pesticides peuvent être une alternative prometteuse pour la gestion des bioagresseurs des cultures maraichères. Cependant, la plupart d’entre elles ne sont pas cultivées. Explorer les capacités biocides de plantes d’intérêt comme le genre Ocimum, connu pour ses usages thérapeutique, médicinal et alimentaire pourrait être intéressant pour le producteur. Toutefois, les populations doivent être sensibilisées sur les avantages à long terme des produits traités avec les pesticides à base de plantes pour faciliter leur utilisation. [less ▲]

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See detailContraintes et stratégies d’amélioration de la filière maïs au Rwanda
Musabanganji, Edouard ULiege

Doctoral thesis (2017)

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In ... [more ▼]

For more than a decade, Rwanda has adopted a series of policies and strategies aimed at economic development and the improvement of the living conditions of its predominantly agricultural population. In agriculture, implementation of these strategies and related programs has been accompanied by a series of advances in the adoption of farming technologies and increasing agricultural production. However, the country's economy is still characterized by subsistence agriculture, and for the maize sector in particular, the country is continuously depending on imports to meet domestic demand, and maize processing plants always operate below their productive capacity. This research aims to examine the level of competitiveness of this sector in the current production and marketing conditions in order to identify existing constraints and formulate the strategies that can improve the level of economic performance of maize production and maize marketing system. The data used to study the economic performance of maize production come from close monitoring of maize production activities on a sample of 50 producers from five maize producers’ cooperatives selected in the districts of Huye, Rusizi, Gasabo, Burera and Bugesera during two growing seasons. They were supplemented by direct observation, interviews with targeted resource persons, and focus group discussions. The analysis was done using group analysis and appropriate statistical methods. The study of the maize marketing system used the 'Structure-Conduct-Performance' model with data collected from a sample of 150 producers and 17 assemblers selected in the districts of Burera, Bugesera and Huye, and 15 transporters, 5 wholesalers and 15 retailers selected at the national market of Kigali. The results revealed that for many producers, the yield is very low compared to theoretical expected yields, production costs are higher and exceed sales prices, gross margin and family labor income are negative, and the gross added value created by maize producers is not high even though it is positive. The analysis showed that the increase in the selling price positively influences the gross margin, added value and family labor income, and that the rational use of improved seeds, chemical fertilizers and soil conditioners improves the yield. This clearly shows that improving the selling price and rational use of inputs can significantly contribute to making maize production a more profitable and income-generating activity. The study also identified challenges that hamper the production process. These include non-availability of, and low access to inputs, inadequate technical support, limited financial resources and low access to formal agricultural credit, high marshlands rental fee, method of fixing the maize floor price and lack of mechanisms ensuring its use by potential buyers, the lack of storage infrastructure, and the unsustainability of inputs subsidies granted by the government. At the marketing level, the results revealed that several actors are involved in the marketing of maize. The study also revealed that maize imported from Uganda is sold on domestic market at lower prices than locally produced maize, which attests the increase in the cost of maize production in Rwanda compared to Uganda and the low level of competitiveness of the local maize compared to Ugandan maize. The improved status of feeder roads and the high level of access to price information by actors were highlighted among the technological innovations that helped improve the marketing system of foodstuffs in general and maize in particular, which was also evidenced by the level of integration observed between districts maize markets and the national market of Kigali. However, the lack of enough capital and low access to formal credit were noted as major constraints by most of the chain actors. In the light of all these results, it is clear that the production and marketing of maize are not done in good conditions at all levels. This in turn undermines the sector's ability to respond adequately to domestic demand, generate income for actors and integrate itself into both domestic and regional markets. Therefore, strategies aiming at scaling-up the maize production and marketing, and improving working conditions of the sector operators were recommended. These strategies include the implementation of actions to improve access to finance by farmers and other actors; making inputs avail and accessible; reorganizing the marketing system especially in terms of fixing and using the floor price; making available storage facilities where necessary; improving the monitoring, training and sensitization of maize producers on farming techniques and the use of improved technologies; and harmonizing the marshland rental fee at national level. [less ▲]

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