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See detailDynamique des transactions foncières et vulnérabilité rurale au Niger : cas des communes rurales de Tchadoua et Yaouri
Lawali Mani, Sitou ULg

Doctoral thesis (2011)

Summary In Niger, agriculture is the principal activity of the rural populations. Unfortunately the access to the land becomes very difficult to the farmers in the center-south of the country. This area ... [more ▼]

Summary In Niger, agriculture is the principal activity of the rural populations. Unfortunately the access to the land becomes very difficult to the farmers in the center-south of the country. This area is confronted to the space saturation and the emergence of the land transactions whose causes, process and impacts on the agricultural households are little known. The study undertaken in the rural municipality of Tchadoua and Yaouri aimed at analyzing the dynamics of the land transactions in bond with the rural vulnerability in terms of the stakes of access and management of the grounds, but also their securisation. The problems were studied with a multidisciplinary approach. The analyses (quantitative and qualitative) were carried out on the basis of the data collected in the village areas of Maijanguero and Gomba through cards of investigations and semi-structured interviews with a sample of 30% of the households. We also used participatory observations of agricultural practices and consultation of different sources of documentation. Administration and others authorities have been also interviewed aswel as members of the land commissions and the intermediaries of the transactions. The results obtained show that the problem of access and management of the land in these agricultural areas is an important concern for rural producers. The land blocking due to the strong demographic pressure and the increase of economic stakes (crop rent) influence the excessive parceling out of the grounds and the individualization of the farms. This individualization supports consequently, the emergence of the commercial land speculations for the profit of the economic operators installed from now in logic of monopolization of grounds. The purchase, the pledge and the lease constitute the principal access modes to the ground instead of old forms of solidarity (gift, loan). Also, the new agrarian initiatives of assistance appear and take part in the improvement of the socio-economic conditions of the rural households. The results also made it possible to highlight a diversity of trajectories of the exploitations. The land ‘’monetarisation’’ influenced strongly the land management and reinforced the exclusion of the vulnerable groups. The strong changes of technical transformation and farming system are observed. It as revealed as the land accumulation or ‘’décapitalisation’’ depends of the type of farm, its strategy and its revenue. Indeed, three tendencies become apparent from the trajectories: great manufacturing units with dominant commercial accumulate land, use the hired labor work and araw cash crop (souchet); a strong land ‘’decapitalisation’’ at the extremely vulnerable and without viable strategy of adaptation in the long term. Lastly, the small farm witch made a diversification and a strong intensification, and there resist to the multiple attempts of land spoliation. These last constitute a model of stable and durable farm whose strategy is based primarily on the agricultural intensification through effective and less expensive agroforestry practices to increase their production and their land capital. The informel and discrete character of land transactions and the networks of intermediation by which are negotiated the land sales accentuate the land insecurity and contribute to increase the land prices. The analysis of the securisation practices of the land rights proves that legal formalization though timid, reduced considerably the frequency of the rural conflicts and offers agricultural opportunities of investments. However, the land commissions encounter difficulties which, slow down the generalization of the legal formalization of transactions. All things considered, the land problem remains a central stake of development thus, the securisation of the land rights of the rural poor must be a priority of the priorities to reach a durable food safety. It is thus urgent to make the land commissions more operational in their giving the means of operation in order to ensure a broad diffusion of the procedures of formalization for more impact and also encouraging the producers through small subsidies to practice the carrying agri-environmental measurements. [less ▲]

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See detailDynamique du carbone inorganique dans l'estuaire de l'Escaut. Premiers résultats
Frankignoulle, Michel; Bourge, Isabelle; Canon, Christine et al

in Bulletin de la Société Royale des Sciences de Liège (1992), 61

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See detailDynamique du carbone inorganique des eaux de surface dans l'embouchure de l'Escaut
Frankignoulle, Michel; Biondo, Renzo ULg; Bouquegneau, Jean-Marie ULg et al

in Bulletin de la Société Royale des Sciences de Liège (1994), 61

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See detailDynamique et chimie dans l'atmosphère de la face nocturne de Vénus
Collet, Arnaud ULg

Book published by Éditions Universitaires Européennes (2011)

L'atmosphère de Vénus est le siège de phénomènes lumineux appelés "airglows" traduits en français par "émissions du ciel". Ces émissions ont lieu dans les domaines UV et IR du spectre électromagnétique et ... [more ▼]

L'atmosphère de Vénus est le siège de phénomènes lumineux appelés "airglows" traduits en français par "émissions du ciel". Ces émissions ont lieu dans les domaines UV et IR du spectre électromagnétique et permettent de déduire des informations à la fois sur la dynamique de l'atmosphère et sur sa composition en espèces minoritaires (oxygène et azote atomiques). L'émission IR à 1.27 µm est due à la désexcitation radiative de l'oxygène moléculaire excité dans l'état métastable singulet delta au sein de la haute mésosphère. Quant à l'émission UV, elle est produite par la recombinaison radiative d'atomes d'azote N(4S) et d'oxygène O(3P) dans la basse thermosphère. Les nombreuses observations de ces deux airglows ont montré qu'ils présentent de grandes variabilités spatiales et temporelles et ne semblent pas présenter de corrélation significative au niveau de leur intensité et de leur localisation spatiale. De plus, étant donné la multitude de processus physiques et chimiques impliqués dans la formation de ces airglows, il est indispensable, pour quantifier le rôle relatif des différents mécanismes, de traiter le problème numériquement. C'est précisément le sujet de cet ouvrage. [less ▲]

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See detailDynamique et composition des atmosphères supérieures de Mars et Vénus observées par les spectrographes ultraviolets à bord de Mars Express et Vénus Express
Stiepen, Arnaud ULg

Doctoral thesis (2014)

Venus has a dense CO2-dominated atmosphere. Above 50 km, the atmospheric circulation is composed of two dominants patterns: the Retrograde Superrotating Zonal (RSZ) circulation up to 65 km and the ... [more ▼]

Venus has a dense CO2-dominated atmosphere. Above 50 km, the atmospheric circulation is composed of two dominants patterns: the Retrograde Superrotating Zonal (RSZ) circulation up to 65 km and the subsolar to antisolar (SSAS) circulation beyond 120 km. The SSAS is caused by the temperature gradient between the day and the night hemispheres and it generates a global flow from the dayside to the nightside. Between 65 and 120 km, the circulation is complex as it is the superposition of the two main components. I have used the nightglow emitted by the NO* molecule (180-300 nm) produced by recombination of N(4S) and O(3P) atoms. These atoms are created by photodissociation of N2 and CO2 molecules on the dayside and carried to the nightside by the SSAS circulation. I analyze the full set of measurements of the NO δ and γ bands measured by the SPICAV instrument on board the ESA Venus Express spacecraft. I discuss the altitude and brightness of the emission peak (60 kR at 115 km) and show that the emission profile exhibits a secondary peak in ~10% of the cases. This additional peak is probably caused by upward-moving gravity waves propagating from below. I have developed an inversion method of the observed limb profiles to compare the results with a chemical-diffusive model of the atmosphere of Venus and constrain the vertical fluxes of N and O. On the basis of an extended statistical analysis, I characterize the presence of a bright spot of the nightglow of NO shifted from the antisolar point and located around 0230LT, 10°S. I use the vast SPICAV airglow database to statistically demonstrate that the NO nightglow is highly variable, both temporally and spatially. Mars experiences seasons as its rotation axis is inclined from its spin axis. Its upper atmospheric dynamics is dominated by summer-to-winter global transport. I study the upper atmosphere of Mars using nightglow observations performed by the SPICAM instrument on board ESA’s Mars Express spacecraft. I analyze the δ and γ bands of molecule NO in the nightside mesosphere to confirm, on statistical basis, the peak brightness and altitude of the NO UV emission (5 kR at 72 km). I show that the NO nightglow is located following the relation Latitude = -80xsin(Solar Longitude), in agreement with results based on stellar occultations and from the LMD model, which simulates the photochemistry and dynamics of the Mars atmosphere. I have performed a detailed study of the CO Cameron band (170 to 270 nm) and CO2+ doublet (290 nm) dayglow. I have developed a method to deduce the temperature profile around 150 km, an important study as the distribution of the temperature in the Mars atmosphere is poorly known. I showed that the temperature at high altitude is only weakly correlated with the solar EUV flux. This result suggests that the variability of the upper atmosphere may include internal processes. Comparisons with the Mars Global Ionosphere Thermosphere Model show that the model can reproduce the observation for high solar conditions but predicts lower temperature for low to moderate solar conditions. Further study will therefore be necessary to identify and understand the mechanisms that govern the temperature variability. [less ▲]

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See detailDynamique et perspectives de la filière cotonnière du Burundi
Gahungu, Antoine ULg

Doctoral thesis (2012)

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the ... [more ▼]

Cotton cultivation was introduced in Burundi in 1919 under the Belgian mandate with the objective to monetize the rural economy and open the country to international trade. After independence (1962), the cotton crop continued to flourish as a vertically integrated chain from upstream to downstream in pursuing the objectives of job creation, import substitution and maximizing the added value generated by various cotton products. Since 1993, the cotton is in perpetual decline due to various factors both endogenous and exogenous to reach in 2009 the lowest level in its history. Its competitiveness is challenged by instability of the global market of cotton fiber, policies (subsidies) of large producers (China, India, USA, Pakistan, ...), competition from synthetic textile industry, the prices of agricultural inputs (fertilizers and phytosanitary products) and raw materials for industries, competition for food crops production factors which are already scarce and especially less remunerative producer prices. Survey work on a sample of 120 farms during three seasons (2007/2008, 2008/2009, 2009/2010) as well as interviews with various agents involved in the cotton sector have been conducted to understand the reasons of the decline of the cotton sector and see the adaptation mechanisms implemented in the segment "producers - COGERCO." It appears from these investigations that the cotton is not competitive with food crops. The price paid to growers is not motivating, production costs are expensive and factors of production become increasingly restrictive. COGERCO however, continues to subsidize cotton without benefit. In this context the majority of cotton producers combine beans or cowpeas with cotton to take advantage of subsidies (inputs, management, ...) and other benefits (loans, fields ...) that the company offers to producers without benefit to the company. The latter is in chronic deficit due to poor sector governance which is under pressure of privatization already imposed on other agro-industrial crops of the country (coffee, tea). [less ▲]

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See detailDynamique et pluralisme culturel dans l’ensemble bruxellois
Martiniello, Marco ULg

in Galissot, R. (Ed.) Pluralisme culturel en Europe : Culture(s) européenne(s) et culture(s) des diasporas (1993)

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See detailDynamique et pluralisme culturels dans l'ensemble Bruxellois
Martiniello, Marco ULg

in Social Sciences Information = Information sur les Sciences Sociales (1992), 31(2), 293-309

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See detailDynamique et production printanière du Mysidacé Leptomysis lingvura en baie de Calvi
Dauby, Patrick ULg

in Annales de la Société Royale Zoologique de Belgique (1984), 114((suppl. 1)), 196

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See detailLa dynamique fluviale d’un cours d’eau de marge passive : le Chassezac (Cévennes, France)
Jacob, N.; Gob, F.; Bravard, J. P. et al

in Géomorphologie : Relief, Processus, Environnement (2006)

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See detailDynamique forestière et enrichissements forestiers. Rapport n° 1.
Doucet, Jean-Louis ULg; Djohnhou, Olivier; Obama, Engelbert et al

Report (2008)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 2.
Doucet, Jean-Louis ULg; Djohnhou, Olivier; Geam, Marie et al

Report (2009)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 3.
Doucet, Jean-Louis ULg; Lagoute, Paul; Mebouomb, Elvis et al

Report (2009)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 4.
Doucet, Jean-Louis ULg; Mebouomb, Elvis; Mouzome, Joselin et al

Report (2010)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 5.
Doucet, Jean-Louis ULg; Mebouomb, Elvis; Mouzome, Joselin et al

Report (2010)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 6.
Doucet, Jean-Louis ULg; Mebouomb, Elvis; Mouzome, Joselin et al

Report (2011)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 7.
Doucet, Jean-Louis ULg; Amandé, Jean; Essik, Jean-Marie et al

Report (2011)

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See detailDynamique forestière et enrichissements forestiers. Site de Mbang. Rapport n° 8.
Doucet, Jean-Louis ULg; Amandé, Jean; Bracke, Charles et al

Report (2012)

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