Détermination de la capacité de nodulation de quelques lignées du haricot : cas du Moyen Ouest de Madagascar

La capacité de nodulation des plantes de haricot est fonction de la présence de Rhizobia et de la fertilité des sols, et surtout fonction de la disponibilité en phosphore de ces sols. L’objectif principal de notre travail vise à étudier le potentiel de nodulation des haricots dans diverses parcelles agricoles afin de tester le lien éventuel entre cette disponibilité en phosphore du sol et la capacité de nodulation des variétés. Ce travail est mené en collaboration avec FOFIFA, IRD et PABRA/ECABREN. L’étude est concentrée dans la zone du Moyen Ouest du Vakinankaratra (Ankazomiriotra et Vinany), basée sur des réseaux de parcelles paysannes. Les matériels végétaux utilisés sont les variétés Goiano Precoce (variété tolérante sur tanety), utilisé comme témoin à long terme et Soafianarana pour témoins local. Les lignées contrastantes, RIL 115 et RIL 147 ont été testées. La fertilisation phosphate de Super triple phosphate est apporté avec 46% de P2O5. La quantité de P2O5 apporté est 50 kg/ha. L’expérimentation comprend 25 répétitions repartis dans le Moyen Ouest du Vakinankaratra. Une parcelle paysanne représente une répétition. Chacune de ces parcelles a reçu les quatre variétés de haricot avec deux niveaux de phosphore zéro et 50 kg/ha P2O5. De ce fait, le dispositif comporte huit traitements qui sont randomisés au hasard dans la parcelle et séparés par un canal pour éviter les contaminations entre traitements. Ainsi, les résultats permettent de classifier les parcelles en quatre typologies par rapport à la fixation symbiotique d’azote et selon les variétés. En effet, les résultats ont montré une faible réponse sur l’apport de phosphate. Ainsi, des analyses de corrélation entre le poids de nodosités et le poids de la biomasse aérienne n’ont pas montré un effet significatif

Global error evaluation strategies in multistep methods applied to ordinary differential equations and index 1 differential algebraic systems

Differential Equations (DEs) are among the most widely used mathematical tools in different area of sciences. Solving DEs, either analytically or numerically, has become a centre of interest for many mathematicians and a large variety of methods are nowadays available to solve DEs numerically. When solving a mathematical problem numerically, evaluating the error is of high importance in practice. Most of the methods already available for solving DEs are implemented with a mechanism to perform a local error control. However, in the real realm, it is common to require the numerical solution to approximate the exact solution with accuracy to a certain number of decimal places or significant figures. To satisfy this condition, we require the global error to be bounded by a specifically determined tolerance. In this case, a local error control is not longer efficient. On one hand, controlling the local error only cannot ensure that the required accuracy will be achieved. On the other hand, the use of such approach requires the user to do some preliminary studies on the problem, and have deep understanding of the method. Thus, we need a mechanism to control the global error in order to compute the numerical solution for a user-supplied accuracy requirement in automatic mode. The global error estimate calculated in the course of such a control can also be applied to improve the numerical solution obtained. It is straight forward since, if the error estimate is found with sufficiently high accuracy, we can just add it to the numerical solution to get a better approximation to the exact value. Thus, accurate evaluation of the the global error is crucial for the purpose mentioned above. Several techniques are already developed to compute the global error of the numerical solution. The most common algorithms include the Richardson extrapolation, Zadunaisky’s technique, Solving for the correction, and Using two different methods. These methods use two integrations to evaluate the global error, and the provided error estimate is valid if the global error admits an expansion in powers of the step size. Another approach, known as solving the linearised discrete variational equation, can also be used. This last differs from the others by the use of a truncated Taylor expansion of the defect of the method to estimate the global error; and solving the problem and estimating the error is roughly the same as one step of the underlying method. In this research, we will investigate numerically and compare the efficiency of different techniques for global error evaluation applied to multistep methods for solving ordinary differential equations (ODEs) and differential algebraic equations (DAEs). We will first study the global error evaluation techniques in multistep formulas for solving ODEs on uniform grids. In the case of nonuniform grids, both multistep methods with variable coefficients and interpolation-type multistep methods will be considered. Then, we will extend our study to multistep methods for solving DAEs. Theoretical background will accompany numerical works. The accuracy and reliability of the global error evaluation strategies will be discussed and compared for different types of multistep methods for solving ODEs and DAEs. We will analyse the efficiency in terms of accuracy obtained and CPU time spent. For that, a series of numerical experiments is conducted on a set of test problems with known solutions

Diversity of aphyllous Vanilla species in the south-west Indian Ocean region: a challenge for orchid taxonomy, evolution and conservation research

The pantropical genus Vanilla is a member of the Orchidaceae family, one of the largest and most ancient families of angiosperms in the world. It originated in America and differentiated in America, Africa and Asia. About 126 species of Vanilla have been catalogued since the discovery of the genus: 25 can be found in Africa, 31 are indigenous to Asia, New Guinea and Pacific islands, and 70 are distributed in tropical America. The south-west Indian Ocean (SWIO) region, a biodiversity hotspot for orchids, is home to 9 native species of the genus with 7 aphyllous species and 2 leafy species. These 7 aphyllous are represented by two species with yellow flowers (V. humblotii, V. perrieri) and five species with white flowers (V. madagascariensis, V. bosseri, V. decaryana, V. phalaenopsis, V. roscheri). Recent molecular phylogenetic studies showed that these aphyllous species form a recent monophyletic group. Morphological descriptions of these aphyllous species in databases (MNHN, RBG Kew, Tropicos..) and in scientific publications are based on a limited number of individuals. The morphological traits (petals, sepals, label, and stems) are very similar between species and do not provide reliable identification despite possible flower size differences. Moreover, the species have more or less the same flowering period (October-December) and their geographical distribution areas overlap in Madagascar, increasing the probability of finding some sympatric species such as V. madagascariensis, V. bosseri and V. perrieri, and therefore possible hybrids. As the available information on genetic structuring and phylogeny of these species is insufficient, the resolution of their taxonomy is problematic. Aphyllous Vanilla species from the SWIO islands are thus an excellent model for understanding the evolution of orchids. For their conservation and to confirm the identity of these aphyllous species, an integrated approach with classical taxonomy using a large number of samples, intense fieldwork on biology and ecology, and molecular studies using variable markers is currently underway

Profil épidémiologique, clinique et thérapeutique des cardiopathies congénitales à Antananarivo: Epidemiological, clinical and therapeutic profile of congenital heart disease in Antananarivo

Context and objective. Little is known about the management of congenital heart disease in sub-Saharan Africa. The aim of our study was to assess the epidemiological profile and management of congenital heart disease. Methods. A retrospective and descriptive study was carried out at the pediatric referral centers of Antananarivo and from the data registry of the Association « Doctors of the world ». Patients aged 0-15 years who had performed a cardiac Doppler between from January 2011 to December 2014 to assess the diagnosis of congenital heart disease, were included. Results. The frequency of congenital heart disease was 1.94%. The age range of 1-30 months was mostly found (55%). No cardiac disease was detected during the antenatal period. Extracardiac-associated manifestations were observed in 21%. Cardiac malformations were unique in 54% and multiple in 46%. Interventricular communication was the most common form of congenital heart disease (17%). The association of an interventricular communication with a persistence of the arterial canal was frequent (10.6%). The patients were seen at the complicated stage in 79% of which 0.97% were in irreversible pulmonary hypertension stage. Only 13.95% of patients were operated in Antananarivo, while 61.24% were transferred outside of the country. Conclusion. Congenital heart defects exist in Antananarivo, but there are limitations in screening and care of these conditions in local settings. Contexte et objectif. La prise en charge des cardiopathies congénitales dans les pays d’Afrique subsaharienne. L’objectif de la présente étude était de déterminer les aspects épidémiologiques et de prise en charge des cardiopathies congénitales. Méthodes. Etude documentaire et descriptive, entre janvier 2011 et décembre 2014, réalisée dans les deux centres hospitaliers de référence de pédiatrie à Antananarivo et à partir des données du registre de l’Association « Médecins du Monde ». Etaient éligibles, tous les patients âgés de 0 à 15 ans et ayant eu un écho-doppler cardiaque de confirmation d’une cardiopathie congénitale. Résultats. La fréquence de la cardiopathie congénitale était de 1,94%. Leur âge moyen était de 24 ± 5,8 mois. Aucune cardiopathie n’avait été détectée pendant la période anténatale. De manifestations extracardiaques associées étaient observées dans 21% de cas. Les malformations cardiaques étaient isolées dans 54% des cas ou associées dans 46%. Les communications interventriculaires étaient les cardiopathies congénitales les plus observées (17%).L’association d’une communication interventriculaire avec une persistance du canal artériel a été retrouvée dans 10,6%. Les patients étaient vus au stade de complications dans 79% cas, dont 0,97% au stade d’hypertension artérielle pulmonaire irréversible. Seuls 13,9% ont pu être opérés localement et 61,2% ont bénéficié d’une évacuation sanitaire. Conclusion. Les cardiopathies congénitales sont une réalité à Antananarivo, cependant certaines limites entravent leur dépistage et leur prise en charge

Nature's contributions to human well‐being under climate change: Evidence from Central and Eastern Madagascar

Anthropogenic climate change has an unprecedented impact on ecosystems and their services, with severe consequences for human well-being, particularly for the marginalised and vulnerable members of society in the Global South. The well-being of communities relies not only on material and regulating services ecosystems provide but also on non-material services. In this paper, we unravel the diverse ways that climate change impacts affect Nature's Contributions to People (NCP) and the well-being of rural populations in four sites in Madagascar—a biodiversity hotspot but one of the economically poorest countries in the world. We conducted participatory community workshops, mapping and semi-structured interviews with local residents across social subgroups to understand the mechanisms of climate-related degradation and the resulting impacts on different dimensions of human well-being through an NCP lens. We found that non-material services are generally more often associated with well-being effects. Climate change degrades material and non-material services through sea level rise, biodiversity loss, drought, precipitation and temperature variability, with consequences for materials, companionship and labour, food and feed, and physical and psychological experiences. Loss of land and forests is expressed through ecological grief. The outcome of our research provides evidence-based information to local policymakers, conservation practitioners, and climate change agencies. This information can help improve government efforts toward holistic conservation and climate change adaptation by addressing the impacts on the physical and mental well-being of the most vulnerable communities

Remote sensing combined with social-ecological data: The importance of diverse land uses for ecosystem service provision in north-eastern Madagascar

Through ongoing deforestation in the tropics, forest-related ecosystem services are declining, while ecosystem services provided by agricultural land uses are on the increase. Land system science provides a framework for analysing the links between land use change and the resulting socio-environmental trade-offs. However, the evidence base to support the navigation of such trade-offs is often lacking, as information on land use cannot directly be obtained through remote sensing and census data is often unavailable at sufficient spatial resolution. The global biodiversity hotspot of north-eastern Madagascar exemplifies these challenges. Combining land use data obtained through remote sensing with social-ecological data from a regional level household survey, we attempt to make the links between land use and ecosystem service benefits explicit. Our study confirmed that remotely sensed information on landscapes reflects households’ involvement in rice production systems. We further characterized landscapes in terms of “ecosystem service bundles” linked to specific land uses, as well as in terms of ecosystem service benefits to households. The map of landscape types could help direct future conservation and development efforts towards places where there is potential for success

Bilan d’une cure chirurgicale d’aspergillome pulmonaire secondaire a une lesion sequellaire de tuberculose au CHU/JRA

La prise en charge d’un aspergillome pulmonaire, dans le cas des lésions limitées accessibles, est une des activités courantes en chirurgie thoracique dans les pays endémique à la tuberculose comme Madagascar. Sur une période allant de janvier 2005 en mars 2010, 15 patients, ancien tuberculeux, atteints d’une aspergillome pulmonaire sont traités par une résection segmentaire ou une lobectomie. La circonstance de découverte repose sur la clinique par des tableaux très polymorphes. L’imagerie garde une place importante. L’examen histologique des pièces d’exérèse chirurgicale confirme le diagnostic. Tous les patients ont été opérés de manière élective. Le résultat a été pour l’ensemble des patients jugés satisfaisant. Ces patients sont suivis pendant 1 à 39 mois. L’étude des résultats à distance est encore en cours et est fondamentale si le traitement chirurgical a un effet bénéfique sur la survie et la qualité de vie des malades. Le but de ce travail a été, à partir de la revue de la littérature et de notre petite expérience, de définir quels éléments pertinents mis en exergue sur le sujet.Pan African Medical Journal 2013; 14: 8

How context affects transdisciplinary research: insights from Asia, Africa and Latin America

Transdisciplinary research (TDR) has been developed to generate knowledge that effectively fosters the capabilities of various societal actors to realize sustainability transformations. The development of TDR theories, principles, and methods has been largely governed by researchers from the global North and has reflected their contextual conditions. To enable more contextsensitive TDR framing, we sought to identify which contextual characteristics affect the design and implementation of TDR in six case studies in Asia, Latin America, and Africa, and what this means for TDR as a scientific approach. To this end, we distinguished four TDR process elements and identified several associated context dimensions that appeared to influence them. Our analysis showed that contextual characteristics prevalent in many Southern research sites—such as highly volatile socio-political situations and relatively weak support infrastructure—can make TDR a challenging endeavour. However, we also observed a high degree of variation in the contextual characteristics of our sites in the global South, including regarding group deliberation, research freedom, and dominant perceptions of the appropriate relationship between science, society, and policy. We argue that TDR in these contexts requires pragmatic adaptations as well as more fundamental reflection on underlying epistemological concepts around what it means to conduct “good science”, as certain contextual characteristics may influence core epistemological values of TDR