Innovation et action collective : le semis direct des cultures pluviales au Moyen Sébou (Maroc)

Les exploitations familiales des pays du Sud, au foncier cultivable souvent limité, doivent pouvoir entretenir la fertilité de leurs terres si elles veulent améliorer leur productivité. L'agriculture de conservation et le semis direct sans travail du sol constituent des pratiques pouvant répondre à cet enjeu. Mais on constate qu'elles sont très peu adoptées par ce type d'exploitations. Cet article vise à décrire comment et pourquoi des agriculteurs de la région du Moyen Sébou au Maroc ont pu adopter le semis direct des cultures pluviales. Des entretiens avec les agriculteurs et quelques mesures au champ ont été réalisés. L'analyse du chantier de semis direct montre que l'agriculteur réalise une économie de temps et d'argent pour l'implantation du blé, comparativement au semis après préparation du sol. L'évolution du système de culture en semis direct vers un système d'agriculture de conservation avec couverture du sol est complexe et peu envisageable, du fait des enjeux économiques et sociaux autour de l'usage des résidus de cultures dans les exploitations de polyculture-élevage. Le renforcement de l'action collective apparaît important pour assurer la durabilité de cette expérience (meilleure organisation des chantiers, mise en place d'un suivi-évaluation, collaboration recherche-développement, etc.). (Résumé d'auteur

Phase Distribution in an Upflow Monolith Reactor using Computed Tomography

Computed Tomography (CT) is Known to Be a Viable Technique for Determining Flow Maldistribution in Two-Phase Flow through Packed Beds. in This Study, Gamma Ray Computed Tomography Has Been Used to Quantify the Flow Distribution in a Monolith Catalytic Bed, with Water as the Liquid Phase and Air as the Gas Phase, Flowing Co-Currently Upward. the Flow Conditions Were Selected to Bracket Some Commercially Viable Operating Conditions for Such Reactors. in the Monolith Core Region, Fairly Uniform Flow Distribution Has Been Obtained for All the Flow Conditions Used. This Distribution is Quantified using the Standard Deviation of the Holdup Distribution. However, Maldistribution of Air and Water in the Monolith Bed Wall Region Due to Wall Effects at the Monolith Entrance Has Been Observed and Quantified by CT. the Obtained Results Confirm that the Entrance and Exit Regions of the Monolith Bed Need to Be Carefully Designed and to Be Free of Obstacles and Vortex Creating Devices. © 2005 American Institute of Chemical Engineers

Experimental Investigation of the Hydrodynamics in a Liquid-Solid Riser

Liquid-Solid Fluid Dynamics Has Been Investigated in a 6-In. (0.15 M) Cold-Flow Circulating Fluidized Bed Riser using Non-Invasive Flow Monitoring Methods. Gamma-Ray Computed Tomography (CT) Was Used to Measure the Time-Averaged Cross-Sectional Solids Volume Fraction Distributions at Several Elevations. the Time-Averaged Mean and Fluctuating Solids Velocity Fields Were Quantified using the Computer-Automated Radioactive Particle Tracking (CARPT) Technique. the Experimental Equipment, Protocol of Implementation, and Data Analysis Have Been Discussed Briefly, with Particular Emphasis on the Specific Features in the Use of These Techniques for Studying High-Density Turbulent Flows as in a Liquid-Solid Riser. the Experimental Study Examines Nine Operating Conditions, that Is, Three Liquid Superficial Velocities and Three Solids Flow Rates. the Solids Holdup Profile is Found to Be Relatively Uniform Across the Cross Section of the Riser, with Marginal Segregation Near the Walls. the Time-Averaged Solids Velocity Profiles Are Found to Have a Negative Component at the Walls, Indicating Significant Solids Backmixing. Detailed Characterization of the Solids Velocity Fields in Terms of RMS Velocities, Kinetic Energies, Hurst Exponents, Residence Time Distributions, Trajectory Length Distributions, Dispersion Coefficients, and So Forth Are Presented. Comparative and Symbiotic Analyses of the Results Were Used to Develop a Coherent Picture of the Solids Flow Field. in Addition, the Work Also Serves to Demonstrate the Power and Versatility of These Flow-Imaging Techniques in Studying Highly Turbulent and Opaque Multiphase Systems. © 2005 American Institute of Chemical Engineers

A Lagrangian Description of Flows in Stirred Tanks Via Computer-Automated Radioactive Particle Tracking (CARPT)

In This Study, Computer-Automated Radioactive Particle Tracking (CARPT) is Implemented for the First Time in the Characterization of Flows in Stirred Tanks. Both the Experimental Set-Up Are Discussed. the CARPT Technique is Seen to Capture Qualitatively Most of the Important Flow Phenomena Observed in Stirred Tank Flows, Like the Two Recirculating Loops above and Below the Impeller and the Dead Zones at the Bottom of the Tank. the CARPT Data is Also Used to Extract \u27\u27Sojourn\u27\u27 Time Distributions in Different Zones of the Reactor. These Distributions Are Used to Partially Quantify the Observed Dead and Active Zones in the Tank. © 2001 Elsevier Science Ltd. All Rights Reserved

Episodes of falling among elderly people: a systematic review and meta-analysis of social and demographic pre-disposing characteristics

CONTEXT: The multifactorial nature of falls among elderly people is well-known. Identifying the social-demographic characteristics of elderly people who fall would enable us to define the typical profile of the elderly who are at risk of falling. OBJECTIVE: We aimed to isolate studies in which the social-demographic risk factors for falls among the elderly have been evaluated and to carry out a meta-analysis by combining the results of all of these selected studies. METHOD: We did a systematic literature review using the key words "accidental fall / numerical data" and "risk factors." Inclusion criteria entailed the selection of articles with the following characteristics: population of subjects aged 60 years or over, falls that took place in everyday life, and social-demographic risk factors for falls. RESULTS: 3,747 indexed articles published between 1981 and 2007 were identified, and 177 studies with available data were included, of which 129 had data on social-demographic risk factors for falls. Difficulties in activities of daily living (ADL) or in instrumental activities of daily living (IADL) double the risk of falling: The OR and 95% Cl were 2.26 (2.09, 2.45) for disturbance ADL and 2.10 (1.68, 2.64) for IADL. The OR and 95% Cl for Caucasians were 1.68 (0.98 - 2.88) and 0.64 (0.51 - 0.80) for Hispanics. In the subgroup of patients older than eighty, being married protected people from falling with an OR and 95% Cl =0.68 (0.53 - 0.87). CONCLUSION: Defining factors that create a risk of falling and protect elderly people from falls using social-demographic characteristics lets us focus on an "at risk" population for which a specific program could be developed

Inferring Liquid Chaotic Dynamics in Bubble Columns

Experiments Carried Out to Study the Liquid Displacements in Bubble Columns Via the Computer Automated Radioactive Particle Tracking Technique Are Analyzed by Means of Lagrangian and Qualitative Dynamics Tools. the Lagrangian Approach Yields the Detailed Motion Sequences of the Tracer as Entrained by the Fast Ascending Bubbles or by the Liquid Flow Alongside the Column Walls. the Qualitative Dynamics Tools, on the Other Hand, Provide Prima Facie Corroboration of Chaos in Liquid Motion based on an Analysis of the Volume-Averaged Kolmogorov Entropy and the Mutual Information Function. Other Features of the Chaotic Motion, the Reconstructed Attractors and the Radial and Axial Distributions of Lyapunov Exponents, Are Noted. Variations in the Liquid Hydrodynamics Due to Changes in Column Diameter and Operating Pressure Are Inspected. by Increasing Pressure the Attractor\u27s Correlation Dimension and the Information Loss Rate Decrease, Whereas the Liquid Flow Path is Dramatically Affected. © 2001 Published by Elsevier Science Ltd

Virtual Promenade: A New Serious Game for the Rehabilitation of Older Adults with Post-fall Syndrome

International audience—We introduce a novel rehabilitation tool to treat Post-Fall Syndrome (PFS) in older adults: a serious game, called Virtual Promenade, combined with a haptic chair imitating the hips movements of human walk. We report on the user-centered design of our prototype, following " living lab " principles, which was well received by our test participants. This system aims at addressing the psycho-motor consequences of older adults' falls; they are often neglected in current post-fall care practices. We first checked for feasibility and tolerability of such interventions. We then applied a living lab participatory design approach, involving health care professionals and older adults, to build the Virtual Promenade prototype. We found that patients with PFS tolerated the system well and that there were no major obstacles to feasibility. We also report that the aesthetics of the virtual environment is an important motivational factor for older adults and discuss our results in searching for the most suitable game controller for this type of patients and game. Finally, we observed that the chairs' movements improved the immersion in the game

Measuring Gas-Liquid Distribution in a Pilot Scale Monolith Reactor Via an Industrial Tomography Scanner (ITS)

An Industrial Tomography Scanner (ITS) Was Designed and Developed to Study and Quantify the Phase Distribution in a Two-Phase Flow Pilot Scale Monolith Reactor that Was 24 In. (0.60 M) in Diameter and 192 In. (4.9 M) in Height. the Monolith Reactor Was Operated Co-Current Up-Flow in the Taylor Flow Regime with Water as the Liquid Phase and Air as the Gas Phase. the Cross-Sectional Holdup Distributions Were Measured at Three Axial Elevations. the Operating Conditions Were Selected to Bracket Commercial Operating Conditions for Fixed Bed Monolithic Reactor Systems. the Results Show that its Can Capture the Flow Features in a Large Diameter Column. Also, the Findings Suggest the Need for Careful Design of the Internals of the Reactor. Spatial Resolution Down to 1.5 Cm Was Obtained So that Gross Phase Maldistribution Could Be Reliably Observed. However, Improvement is Needed for the its to Be Effectively Utilized in Industry. © 2006 Elsevier B.V. All Rights Reserved

IMPACT OF TYPE 2 DIABETES ON THE DEVELOPMENT OF PERIODONTAL DISEASE IN THE MOUSE

Oral Communication presented at the ";;Forum des Jeunes Chercheurs";;, Brest (France) 2011

Comparative Hydrodynamics Study in a Bubble Column using Computer-Automated Radioactive Particle Tracking (CARPT)/computed Tomography (CT) and Particle Image Velocimetry (PIV)

The Hydrodynamics of a 10-Cm-Diameter Cylindrical Bubble Column at the Superficial Gas Velocity of 2, 4, and 8 Cm/s Are Investigated by Computer-Automated Radioactive Particle Tracking (CARPT), Particle Image Velocimetry (PIV), and Computed Tomography (CT). These Experimental Techniques Are Capable of Providing the Knowledge of Velocity and Holdup Fields in a Bubble Column System, Which Are Essential as the Experimental Benchmark for Modeling of Such Systems. the Flow Field of Liquid Phase, as Well as the Reynolds Stresses, Obtained by CARPT and PIV in an Air-Water System Are Compared in Detail. the Results Indicate that CARPT and PIV Complement Each Other Well. Further, the Profile of Gas Holdup Obtained by Gamma Ray based on CT Compares Favorably to the Independently Determined Holdup