Systèmes de culture, habitudes alimentaires et durabilité des agrosystèmes forestiers en Afrique (Guinée, Cameroun): une approche géoagronomique

International audienceThe population growth is generally considered as the main cause of the fast degradation of forest ecosystems in sub Sahara Africa. This contribution presents a comparative analysis of spatial and temporal dynamics in two forest regions from West Africa (Forest Guinea) and Centre Africa (Centre-South Cameroon). It shows that the choice of cropping systems especially food crops, (and related food preferences) explains the difference in anthropic pressure on natural resources between these two situations, with similar low (20hab./km2) population density. The cropping systems based on upland rice have a higher spatial impact (0.91 ha/habitant) than those observed in Centre-south Cameroon based on tubers and plantain (0.15 ha/habitant). Simultaneously the extension of agroforests based on perennial crops (coffee, cocoa, fruit trees) requiring more space is active in Forest Guinea and still contributes to increase the pressure on land. In Cameroon, this anthropic pressure remains low unless the food crops become more urban market oriented. Decisions about crops and rotation are based on bio-physical conditions locally or regionally, but also and particularly on endogenous factors like food preferences (rice in Guinea, roots and plantain in Cameroon) and local and regional urban market demand. Understanding these socioeconomic and agroecological changes requires to mobilize various disciplinary approaches combining geoagronomy, economy and socio-anthropology

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

Revealing the inner circumstellar disk of the T Tauri star S Coronae Australis N using the VLTI

Copyright © ESO, 2012Aims. We investigate the structure of the circumstellar disk of the T Tauri star S CrA N and test whether the observations agree with the standard picture proposed for Herbig Ae stars. Methods. Our observations were carried out with the VLTI/AMBER instrument in the H and K bands with the low spectral resolution mode. For the interpretation of our near-infrared AMBER and archival mid-infrared MIDI visibilities, we employed both geometric and temperature-gradient models. Results. To characterize the disk size, we first fitted geometric models consisting of a stellar point source, a ring-shaped disk, and a halo structure to the visibilities. In the H and K bands, we measured ring-fit radii of 0.73  ± 0.03 mas (corresponding to 0.095   ±   0.018 AU for a distance of 130 pc) and 0.85   ±   0.07 mas (0.111   ±   0.026 AU), respectively. This K-band radius is approximately two times larger than the dust sublimation radius of ≈0.05 AU expected for a dust sublimation temperature of 1500 K and gray dust opacities, but approximately agrees with the prediction of models including backwarming (namely a radius of ≈0.12 AU). The derived temperature-gradient models suggest that the disk is approximately face-on consisting of two disk components with a gap between star and disk. The inner disk component has a temperature close to the dust sublimation temperature and a quite narrow intensity distribution with a radial extension from 0.11 AU to 0.14 AU. Conclusions. Both our geometric and temperature-gradient models suggest that the T Tauri star S CrA N is surrounded by a circumstellar disk that is truncated at an inner radius of ≈ 0.11 AU. The narrow extension of the inner temperature-gradient disk component implies that there is a hot inner rim.International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Universities of Bonn and Cologn

Quelle place du conseil agricole dans les services support a l'innovation a Madagascar?

Open Access Article; Published online: 19 Jul 2021Le conseil agricole occupe une place prépondérante dans l’appui aux processus d’innovation, particulièrement dans les pays du Sud. Or, l’accompagnement de l’innovation nécessite une diversité de formes d’appuis, appelés services support à l’innovation (SSI). À partir d’une analyse exploratoire à Madagascar, cet article questionne la place du conseil agricole vis-à-vis de la diversité des organisations et des activités d’accompagnement de l’innovation. Les principales organisations fournissant des SSI ont été étudiées dans quatre régions des Hautes Terres de Madagascar et leur offre de SSI caractérisée. Les résultats montrent que le conseil technique reste prépondérant dans l’éventail de l’offre de SSI, avec un fort pluralisme des fournisseurs de conseil et une diversité de combinaisons avec les autres SSI. Or, les porteurs d’innovation doivent bénéficier d’autres SSI, tels que le renforcement de capacité, la mise en réseau, des appuis institutionnels, un accès au financement, intrants et équipements nécessaires à l’innovation. Ces résultats appellent à renouveler les postures du conseiller agricole vers davantage d’appui au renforcement de capacité et interrogent la stratégie des organisations vis-à-vis de leur appui à l’innovation : la spécialisation dans le conseil, la combinaison à d’autres SSI ou la collaboration avec d’autres organisations. Ces éléments renouvellent le constat du pluralisme de l’offre de conseil qui, analysé par le prisme des SSI, ne s’applique pas seulement à l’échelon de l’agent-conseiller ou de l’organisation, mais également dans des réseaux d’organisations aux configurations variables. Les perspectives de cette analyse sont d’assurer la coordination des dispositifs de conseil avec les autres fournisseurs de SSI pour une plus grande efficacité dans l’accompagnement des porteurs d’innovation. Which place of agricultural advisory services among innovation support services in Madagascar? Agricultural advisory services play a major role in supporting innovation processes, particularly in developing countries. However, innovation support requires a variety of forms of support, called innovation support services (ISS). Based on an exploratory analysis in Madagascar, this article examines the role of agricultural advisory services in relation to the diversity of organizations and activities to support innovation. We interviewed the main organizations acting as providers of ISS in four geographic regions of the Highlands of Madagascar and we characterized their ISS offer. Results show that the technical advice service remains the most common type of ISS offered, with a high degree of pluralism among the providers of advice and a diversity of combinations with other ISS. However, innovators need to benefit from other ISS, such as capacity building, networking, institutional support and access to finance, inputs and equipment necessary for innovation. These results call for a renewal of the postures of the agricultural advisors towards more support oriented toward capacity building. They question the strategy of the organizations with regard to their support for innovation: a specialization in advisory service, a combination with other ISS or a collaboration with other organizations. Those results renew insights into the pluralism of the offer of advisory services. When analyzed through the prism of ISS, those services are not only applied at the level of the advisor or the advisory organization, but also at the level of the supporting network, which may exhibit various configurations. Perspectives call for a better coordination of advisory systems with the other service providers in order to ensure greater efficiency in supporting innovators

Epigenetic mechanisms of lung carcinogenesis involve differentially methylated CpG sites beyond those associated with smoking

Smoking-related epigenetic changes have been linked to lung cancer, but the contribution of epigenetic alterations unrelated to smoking remains unclear. We sought for a sparse set of CpG sites predicting lung cancer and explored the role of smoking in these associations. We analysed CpGs in relation to lung cancer in participants from two nested case–control studies, using (LASSO)-penalised regression. We accounted for the effects of smoking using known smoking-related CpGs, and through conditional-independence network. We identified 29 CpGs (8 smoking-related, 21 smoking-unrelated) associated with lung cancer. Models additionally adjusted for Comprehensive Smoking Index-(CSI) selected 1 smoking-related and 49 smoking-unrelated CpGs. Selected CpGs yielded excellent discriminatory performances, outperforming information provided by CSI only. Of the 8 selected smoking-related CpGs, two captured lung cancer-relevant effects of smoking that were missed by CSI. Further, the 50 CpGs identified in the CSI-adjusted model complementarily explained lung cancer risk. These markers may provide further insight into lung cancer carcinogenesis and help improving early identification of high-risk patients

Study protocol to investigate the effect of a lifestyle intervention on body weight, psychological health status and risk factors associated with disease recurrence in women recovering from breast cancer treatment

Background Breast cancer survivors often encounter physiological and psychological problems related to their diagnosis and treatment that can influence long-term prognosis. The aim of this research is to investigate the effects of a lifestyle intervention on body weight and psychological well-being in women recovering from breast cancer treatment, and to determine the relationship between changes in these variables and biomarkers associated with disease recurrence and survival. Methods/design Following ethical approval, a total of 100 patients will be randomly assigned to a lifestyle intervention (incorporating dietary energy restriction in conjunction with aerobic exercise training) or normal care control group. Patients randomised to the dietary and exercise intervention will be given individualised healthy eating dietary advice and written information and attend moderate intensity aerobic exercise sessions on three to five days per week for a period of 24 weeks. The aim of this strategy is to induce a steady weight loss of up to 0.5 Kg each week. In addition, the overall quality of the diet will be examined with a view to (i) reducing the dietary intake of fat to ~25% of the total calories, (ii) eating at least 5 portions of fruit and vegetables a day, (iii) increasing the intake of fibre and reducing refined carbohydrates, and (iv) taking moderate amounts of alcohol. Outcome measures will include body weight and body composition, psychological health status (stress and depression), cardiorespiratory fitness and quality of life. In addition, biomarkers associated with disease recurrence, including stress hormones, estrogen status, inflammatory markers and indices of innate and adaptive immune function will be monitored. Discussion This research will provide valuable information on the effectiveness of a practical, easily implemented lifestyle intervention for evoking positive effects on body weight and psychological well-being, two important factors that can influence long-term prognosis in breast cancer survivors. However, the added value of the study is that it will also evaluate the effects of the lifestyle intervention on a range of biomarkers associated with disease recurrence and survival. Considered together, the results should improve our understanding of the potential role that lifestyle-modifiable factors could play in saving or prolonging lives

The biology of inequalities in health: The LIFEPATH project

Socioeconomic differences in health have been consistently observed worldwide. Physical health deteriorates more rapidly with age among men and women with lower socioeconomic status (SES) than among those with higher SES. The biological processes underlying these differences are best understood by adopting a life course approach. In this paper we introduce the pan- European LIFEPATH project which uses multiple cohorts - including biomarker data - to investigate ageing as a phenomenon with two broad stages across life: build-up and decline. The ‘build-up’ stage, from conception and early intra-uterine life to late adolescence or early twenties, is characterised by rapid successions of developmentally and socially sensitive periods. The second stage, starting in early adulthood, is a period of ‘decline’ from maximum attained health to loss of function, overt disease and death. LIFEPATH adopts a study design that integrates social science and public health approaches with biology (including molecular epidemiology), using well-characterised population cohorts and omics measurements (particularly epigenomics). LIFEPATH includes information and biological samples from 17 cohorts, including several with extensive phenotyping and repeat biological samples, and a very large cohort (1 million individuals) without biological samples (WHIP, from Italy). The countries that are covered by the cohorts are France, Italy, Portugal, Ireland, UK, Finland, Switzerland and Australia. These cohorts are only a small proportion of all cohorts available in Europe, but we have chosen them for the combination of good measures of socioeconomic status, risk factors for non-communicable diseases (NCDs) and biomarkers already measured (or availability of blood samples for further testing). The majority of cohorts include ‘hard’ outcomes (diabetes, cancer, Cardiovascular Disease (CVD), total mortality), and the extensively phenotyped cohorts also include several measurements of the functional components of healthy ageing, including frailty, impaired vision, cognitive function, renal and brain function, osteoporosis, sleep disturbances and mental health. All age groups are represented with two birth cohorts, one cohort of adolescents and several cohorts encompassing young adults (age 18 and above). Furthermore, there is a strong representation of elderly subjects in seven cohorts. The specific objectives of the project are: (a) to show that healthy ageing is an achievable goal for society; (b) to improve the understanding of the mechanisms through which healthy ageing pathways diverge by SES, by investigating life course biological pathways using omic technologies; (c) to examine the consequences of the current economic recession on health and the biology of ageing (and the consequent increase in social inequalities); (d) to provide updated, relevant and innovative evidence for healthy ageing policies (particularly ‘health in all policies’) using both observational studies and an experimental approach based on a reanalysis of data from a ‘conditional cash transfer’ randomised experiment in New York and new data collected as part of an earned income tax credit randomised experiment in Atlanta and New York. To achieve these objectives, data are used from three categories of studies: 1. national census-based followup data to obtain mortality by socioeconomic status; 2. cohorts with intense phenotyping and repeat biological samples; 3. large cohorts with biological samples. With these objectives and methodologies, LIFEPATH seeks to provide updated, relevant and innovative evidence to underpin future policies and strategies for the promotion of healthy ageing, targeted disease prevention and clinical interventions that address the issue of social disparities in ageing and the social determinants of health. The present paper describes the design and some initial results of LIFEPATH as an example of the integration of social and biological sciences to provide evidence for public health policies

The general fault in our fault lines

Pervading global narratives suggest that political polarization is increasing, yet the accuracy of such group meta-perceptions has been drawn into question. A recent US study suggests that these beliefs are inaccurate and drive polarized beliefs about out-groups. However, it also found that informing people of inaccuracies reduces those negative beliefs. In this work, we explore whether these results generalize to other countries. To achieve this, we replicate two of the original experiments with 10,207 participants across 26 countries. We focus on local group divisions, which we refer to as fault lines. We find broad generalizability for both inaccurate meta-perceptions and reduced negative motive attribution through a simple disclosure intervention. We conclude that inaccurate and negative group meta-perceptions are exhibited in myriad contexts and that informing individuals of their misperceptions can yield positive benefits for intergroup relations. Such generalizability highlights a robust phenomenon with implications for political discourse worldwide

Socioeconomic position, lifestyle habits and biomarkers of epigenetic aging: A multi-cohort analysis

Differences in health status by socioeconomic position (SEP) tend to be more evident at older ages, suggesting the involvement of a biological mechanism responsive to the accumulation of deleterious exposures across the lifespan. DNA methylation (DNAm) has been proposed as a biomarker of biological aging that conserves memory of endogenous and exogenous stress during life.We examined the association of education level, as an indicator of SEP, and lifestyle-related variables with four biomarkers of age-dependent DNAm dysregulation: the total number of stochastic epigenetic mutations (SEMs) and three epigenetic clocks (Horvath, Hannum and Levine), in 18 cohorts spanning 12 countries.The four biological aging biomarkers were associated with education and different sets of risk factors independently, and the magnitude of the effects differed depending on the biomarker and the predictor. On average, the effect of low education on epigenetic aging was comparable with those of other lifestyle-related risk factors (obesity, alcohol intake), with the exception of smoking, which had a significantly stronger effect.Our study shows that low education is an independent predictor of accelerated biological (epigenetic) aging and that epigenetic clocks appear to be good candidates for disentangling the biological pathways underlying social inequalities in healthy aging and longevity

Allostatic load and subsequent all-cause mortality: which biological markers drive the relationship? Findings from a UK birth cohort

The concept of allostatic load (AL) refers to the idea of a global physiological ‘wear and tear’ resulting from the adaptation to the environment through the stress response systems over the life span. The link between socioeconomic position (SEP) and mortality has now been established, and there is evidence that AL may capture the link between SEP and mortality. In order to quantitatively assess the role of AL on mortality, we use data from the 1958 British birth cohort including eleven year mortality in 8,113 adults. Specifically, we interrogate the hypothesis of a cumulative biological risk (allostatic load) reflecting 4 physiological systems potentially predicting future risk of death (N = 132). AL was defined using 14 biomarkers assayed in blood from a biosample collected at 44 years of age. Cox proportional hazard regression analysis revealed that higher allostatic load at 44 years old was a significant predictor of mortality 11 years later [HR = 3.56 (2.3 to 5.53)]. We found that this relationship was not solely related to early-life SEP, adverse childhood experiences and young adulthood health status, behaviours and SEP [HR = 2.57 (1.59 to 4.15)] . Regarding the ability of each physiological system and biomarkers to predict future death, our results suggest that the cumulative measure was advantageous compared to evaluating each physiological system sub-score and biomarker separately. Our findings add some evidence of a biological embodiment in response to stress which ultimately affects mortality