Valorisation de substrats organiques divers dans l'agriculture péri-urbaine de Ouagadougou (Burkina Faso) pour l'amendement et la fertilisation des sols : acteurs et pratiques

Organic substrates recycling in the sub-urban agriculture of Ouagadougou (Burkina Faso) for soils fertilization: description of the different actors and their practices. This study aimed to establish an overview of the main actors of the sub-urban agriculture of Ouagadougou, their practices and expectations, and to characterize the used organic substrates (OS). For that, a farm survey was carried out on the most representative sites with 64 persons (cereal farmers, truckers and nurserymen) randomly chosen. OS were sampled with each actor, when available. Thus, 27 samples were taken and characterized through chemical analyses and laboratory incubations to follow organic carbon mineralization. The results highlighted that 35% of cereal farmers, 69% of truckers and 95% of nurserymen were 20 to 40 years old, that a large proportion of cereal farmers and truckers were not sent to school while 70% of nurserymen had at least primary education. Sub-urban agriculture was the only activity for 43% of farmers, 83% of truckers and 91% of nurserymen. Moreover, 71% of cereal farmers and 73% of nurserymen used municipal wastes as source of organic matter against only 17% of truckers, the majority of them using animal manures. The main criterion of choice of OS was their availability without any other consideration. Even if a large majority of the actors think that composts of OS were better than brut OS, a minority of them used currently composts. The best ways for an adoption and utilization of OS composts were to facilitate their accessibility and to promote these composts, composting techniques and their interests through advertising in mass media. Chemical analyses and laboratory incubations showed a great variability of the SUW, both in the same group and actors' groups. However, in case of total organic carbon, total nitrogen and total phosphorous contents, the following tendencies were observed: Contenttruckers > Contentfarmers > Contentnurserymen. For the sum of major elements Ca, K, Mg, Na (SME), it was observed that SMEtruckers ≈ SMEfarmers > SMEnurserymen. In addition, except a few atypical substrates, OS used by nurserymen were largely stabilized compared to those of cereal farmers and truckers

Regional and local emissions in red river delta, Northern Vietnam

Fine (PM2.2) and coarse (PM2.2–10) particles concurrently collected in urban (Hanoi) and rural (Lucnam) areas were analyzed for ionic and elemental compositions to provide input for PMF receptor modeling of emission sources in the Red River Delta (RRD), a key economic development region in Vietnam. Long-range transport (LRT) aerosol, coal fly ash from major coal-fired plants in RRD, and marine aerosols are regional sources, which explain the minor variability of the mass concentrations of fine particles across the region. Local sources include soil/resuspended road dust, local coal fly ash, and biomass burning. Soil/resuspended road dust is the largest source component of coarse particles at the two sites. It is more abundant in Hanoi than in Lucnam reflecting the urban–rural contrast in traffic and construction works. Receptor models reveal the incorporation of secondary sulfate, nitrate, and ammonium into the various primary particles, i.e., soot, minerals, soil organic matter, and sea salt. Soot particles from LRT carry the largest amounts of sulfate and ammonium mass concentrations measured at the two sites. Based on receptor models, the yields and possible chemical forms of secondary sulfate, nitrate, and ammonium in different types of primary particles can be inferred

Design an Intelligent System to automatically Tutor the Method for Solving Problems

Nowadays, intelligent systems have been applied in many real-word domains. The Intelligent chatbot is an intelligent system, it can interact with the human to tutor how to work some activities. In this work, we design an architecture to build an intelligent chatbot, which can tutor to solve problems, and construct scripts for automatically tutoring. The knowledge base of the intelligent tutoring chatbot is designed by using the requirements of an Intelligent Problem Solver. It is the combination between the knowledge model of relations and operators, and the structures of hint questions and sample problems, which are practical cases. Based on the knowledge base and tutoring scripts, a tutoring engine is designed. The tutoring chatbot plays as an instructor for solving real-world problems. It simulates the working of the instructor to tutor the user for solving problems. By utilizing the knowledge base and reasoning, the architecture of the intelligent chatbot are emerging to apply in the real-world. It is used to build an intelligent chatbot to support the learning of high-school mathematics and a consultant system in public administration. The experimental results show the effectiveness of the proposed method in comparison with the existing systems

Sustainable Farming Systems in the Sub-Sahelian Zone of Burkina Faso : Key Factors

Rapid population growth and climatic change threatens the sustainability of natural resources. Farming practices can mitigate environmental change and degradation. The aim of this research conducted in Yatenga region was to describe and to analyse manure practices management. In 2005, a survey was carried out to assess the evolution of farming practices. A survey was initially conducted with a sample of 44 farmers, selected randomly in the three neighbouring villages. Subsequently, 18 farms were selected for in-depth interviews. The grain yield was measured and the different practices of soil and water conservation developed by farmers were compared. According to the enquiries, two practices, called “zaï” and “djengo”, were largely used in cereals production. The “zaï” practice, known as a traditional technique for restoration of degraded soil, is characterized by the capture of runoff by micro-watersheds and a localized organic matter supply at the soil-plant system scale. The “djengo” practice is based on the same principle of the “zaï” practice but was applied on the sandy soil as traditionally “zaï” concerned the degraded and crusty soils. The two practices could increase grain crop production but moreover could limit the risk of crops failure. In addition, our observations also showed that frequent tree regenerations occurred in plots and watersheds where “zaï” or “djengo” practices were used. This study highlights the necessity of better controlling soil, water and organic matter to improve agrosystem sustainability in sub Saharan Africa.Rapid population growth and climatic change threatens the sustainability of natural resources. Farming practices can mitigate environmental change and degradation. The aim of this research conducted in Yatenga region was to describe and to analyse manure practices management. In 2005, a survey was carried out to assess the evolution of farming practices. A survey was initially conducted with a sample of 44 farmers, selected randomly in the three neighbouring villages. Subsequently, 18 farms were selected for in-depth interviews. The grain yield was measured and the different practices of soil and water conservation developed by farmers were compared. According to the enquiries, two practices, called “zaï” and “djengo”, were largely used in cereals production. The “zaï” practice, known as a traditional technique for restoration of degraded soil, is characterized by the capture of runoff by micro-watersheds and a localized organic matter supply at the soil-plant system scale. The “djengo” practice is based on the same principle of the “zaï” practice but was applied on the sandy soil as traditionally “zaï” concerned the degraded and crusty soils. The two practices could increase grain crop production but moreover could limit the risk of crops failure. In addition, our observations also showed that frequent tree regenerations occurred in plots and watersheds where “zaï” or “djengo” practices were used. This study highlights the necessity of better controlling soil, water and organic matter to improve agrosystem sustainability in sub Saharan Africa

Advanced Camera for Surveys Observations of Young Star Clusters in the Interacting Galaxy UGC 10214

We present the first Advanced Camera for Surveys (ACS) observations of young star clusters in the colliding/merging galaxy UGC 10214. The observations were made as part of the Early Release Observation (ERO) program for the newly installed ACS during service mission SM3B for the Hubble Space Telescope (HST). Many young star clusters can be identified in the tails of UGC 10214, with ages ranging from ~3 Myr to 10 Myr. The extreme blue V-I (F606W-F814W) colors of the star clusters found in the tail of UGC 10214 can only be explained if strong emission lines are included with a young stellar population. This has been confirmed by our Keck spectroscopy of some of these bright blue stellar knots. The most luminous and largest of these blue knots has an absolute magnitude of M_V = -14.45, with a half-light radius of 161 pc, and if it is a single star cluster, would qualify as a super star cluster (SSC). Alternatively, it could be a superposition of multiple scaled OB associations or clusters. With an estimated age of ~ 4-5 Myr, its derived mass is < 1.3 x 10^6 solar masses. Thus the young stellar knot is unbound and will not evolve into a normal globular cluster. The bright blue clusters and associations are much younger than the dynamical age of the tail, providing strong evidence that star formation occurs in the tail long after it was ejected. UGC 10214 provides a nearby example of processes that contributed to the formation of halos and intra-cluster media in the distant and younger Universe.Comment: 6 pages with embedded figures, ApJ in pres

Efficiences Des Nutriments P Et K En Riziculture Irriguée Dans Un Bas-Fond Secondaire En Zone De Savane Guinéenne De La Côte d’Ivoire

N-nitrogen is the most limiting element in rice-growing on lowland soils in the central part of Côte d'Ivoire. In addition to its direct effect, poor management of P and K fertilizers in basic manure can induce low yields and losses of currencies. However, inappropriate use of these nutrients (P and K) in these shallows can induce other adverse effects on crops and even on the environment. So, for the eficient management of lowland ricegrowing fertiliszation, three agronomic trials have been set up in the Central part of Côte d'Ivoire to determine the optimum P and K doses to improve fertilizer efficiency in the relevant agroecology. Three rates of PCa(H2PO4)2H2O [30, 60 and 90 kgPha-1 ] as well as three of K-KCl [25, 50 and 75kgKha-1 ] and their recommended rates (13kgPha-1 and 25kgKha-1 ) in the humid forest zone were the treatments. A total of 80kgNha-1 (urea) was applied in three splits to each of the micro-plots except in the control including no fertilizer. The rice variety named NERICA L19 was transplanted.An agronomic trial including eleven (11) treatments in three replications was laid out in a complete randomized blocks design The highest K recovery rate is obtained with the 25kgKha -1 rates, while the lowest rate is with 50kgKha-1 in the three trials. There is a gradual decrease in P-level recovery as rates increase, regardless of the test. Increased rates of P and K induce a decrease in agronomic efficiency. The partial productivity factor (PFP) of nutrients P and K decreases with increasing rates for all three trials. The highest grains and straw yields are obtained for 75kgKha-1 doses regardless of the dose of P. However, it should be noted that the different efficiencies obtained are better for the lower rates of P and

Polarimetry and Unification of Low-Redshift Radio Galaxies

We have made high-quality measurements of the polarization spectra of 13 FR II radio galaxies and taken polarization images for 11 of these with the Keck telescopes. Seven of the eight narrow-line radio galaxies (NLRG) are polarized, and six of the seven show prominent broad Balmer lines in polarized light. The broad lines are also weakly visible in total flux. Some of the NLRG show bipolar regions with roughly circumferential polarization vectors, revealing a large reflection nebula illuminated by a central source. Our observations powerfully support the hidden quasar hypothesis for some NLRG. Classification as NLRG, broad-line radio galaxy (BLRG), or quasar therefore depends on orientation. However, not all objects fit into this unification scheme. Our sample is biased towards objects known in advance to be polarized, but the combination of our results with those of Hill, Goodrich and DePoy (1996) show that at least 6 out of a complete, volume and flux-limited sample of 9 FR II NLRG have broad lines, seen either in polarization or P_alpha.Comment: To appear in November 1999 Astronomical Journal. 49 pages, 13 figure

Discovery of Two Distant Type Ia Supernovae in the Hubble Deep Field North with the Advanced Camera for Surveys

We present observations of the first two supernovae discovered with the recently installed Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The supernovae were found in Wide Field Camera images of the Hubble Deep Field North taken with the F775W, F850LP, and G800L optical elements as part of the ACS guaranteed time observation program. Spectra extracted from the ACS G800L grism exposures confirm that the objects are Type Ia supernovae (SNe Ia) at redshifts z=0.47 and z=0.95. Follow-up HST observations have been conducted with ACS in F775W and F850LP and with NICMOS in the near-infrared F110W bandpass, yielding a total of 9 flux measurements in the 3 bandpasses over a period of 50 days in the observed frame. We discuss many of the important issues in doing accurate photometry with the ACS. We analyze the multi-band light curves using two different fitting methods to calibrate the supernovae luminosities and place them on the SNe Ia Hubble diagram. The resulting distances are consistent with the redshift-distance relation of the accelerating universe model, although evolving intergalactic grey dust remains as a less likely possibility. The relative ease with which these SNe Ia were found, confirmed, and monitored demonstrates the potential ACS holds for revolutionizing the field of high-redshift SNe Ia, and therefore of testing the accelerating universe cosmology and constraining the "epoch of deceleration".Comment: 11 pages, 8 embedded figures. Accepted for publication in Ap