L'amélioration des plantes tropicales

L'amélioration des plantes a connu au cours des dix dernières années une évolution rapide. D'une part, elle bénéficie désormais des outils biotechnologiques d'exploitation des ressources génétiques et de création de variétés, qui viennent enrichir les méthodes classiques de sélection. D'autre part, elle doit répondre à de nouvelles attentes : gérer la biodiversité et concourir à une agriculture durable. Cet ouvrage présente les derniers progrès réalisés en amélioration des plantes tropicales. Il se fonde principalement sur les travaux que les équipes françaises du CIRAD et de l'ORSTOM conduisent en collaboration avec leurs homologues des pays tropicaux. Il comprend vingt-quatre chapitres, chacun étant consacré à une culture et rédigé par des spécialistes de la génétique et de la sélection de l'espèce. Pour chaque plante ou groupe de plantes, les auteurs analysent la diversité des formes cultivées et leurs relations avec les espèces sauvages apparentées. Ils décrivent les méthodes d'amélioration et les apports des biotechnologies dans la pratique du sélectionneur. Ils examinent les progrès génétiques réalisés en partant d'exemples tirés des programmes de création variétale. Enfin ils traitent de la diffusion des variétés améliorées. Cet ouvrage de référence s'adresse au chercheur, à l'enseignant, à l'étudiant comme au professionnel de la sélection. (Résumé d'auteur

Pressure-stabilized fixed-stress iterative solutions of compositional poromechanics

We consider the numerical behavior of the fixed-stress splitting method for coupled poromechanics as undrained regimes are approached. We explain that pressure stability is related to the splitting error of the scheme, not the fact that the discrete saddle point matrix never appears in the fixed-stress approach. This observation reconciles previous results regarding the pressure stability of the splitting method. Using examples of compositional poromechanics with application to geological CO$_2$ sequestration, we see that solutions obtained using the fixed-stress scheme with a low order finite element-finite volume discretization which is not inherently inf-sup stable can exhibit the same pressure oscillations obtained with the corresponding fully implicit scheme. Moreover, pressure jump stabilization can effectively remove these spurious oscillations in the fixed-stress setting, while also improving the efficiency of the scheme in terms of the number of iterations required at every time step to reach convergence

End-to-End Evaluation in Simultaneous Translation

This paper presents the end-to-end evaluation of an automatic simultaneous translation system, built with state-of-the-art components. It shows whether, and for which situations, such a system might be advantageous when compared to a human interpreter. Using speeches in English translated into Spanish, we resent the evaluation procedure and we discuss the results both for the recognition and translation components as well as for the overall system. Even if the translation process remains the Achilles’ heel of the system, the results show that the system can keep at least half of the information, becoming potentially useful for final users

Geochemical indices allow estimation of heavy metal background concentration in soils

Defining background concentrations for heavy metals in soils is essential for recognizing and managing soil pollution. However, background concentrations of metals in soils can vary naturally by several orders of magnitude. Moreover, many soils have also been subject to unquantifiable anthropogenic inputs of metals, in some cases, for centuries. Hence determination of heavy metal background concentrations in soils has to date been fraught with difficulty. Here we demonstrate that there are associations between the background heavy metal and Fe or Mn contents in soils which appear to be consistent for seven important heavy metals of environmental concern. The relationships are remarkably independent of both soil type and climatic setting. These observations provide the basis for a series of general equations from which it is proposed Southeast Asian including Australian, and possibly worldwide background concentrations for As, Cr, Co, Cu, Ni, Pb, and Zn in soils can be derived.R. E. Hamon, M. J. McLaughlin, R. J. Gilkes, A. W. Rate, B. Zarcinas, A. Robertson, G. Cozens, N. Radford and L. Bettena

New perspectives in the pathophysiology and treatment of affective disorders: the role of melatonin and serotonin

Более 40 лет в области исследований патогенеза депрессии и разработки адекватных препаратов для эффективной терапии этого расстройства доминировала моноаминовая гипотеза, предполагающая в основе депрессии дисбаланс функции серотонина, норадреналина и, возможно, дофамина. Хотя эти моноаминовые нейротрансмиттеры, роль которых обсуждается в данной публикации, несомненно, участвуют в патогенезе депрессии, их дефицит — лишь часть истории, так как для полного объяснения механизмов депрессии необходимо также учитывать другие нарушения вне рамок дисбаланса моноаминов. Существует явная потребность в более эффективных препаратах с улучшенной переносимостью и более быстрым действием. Разработка новых антидепрессантов на основании механизмов, не связанных с моноаминовой гипотезой, представляется более перспективной. Сегодня повышенное внимание уделяется связи аффективных расстройств, включая и депрессию, с аномальными изменениями в циркадианных ритмах. В этой публикации рассматривается роль мелатонина и его рецепторов при депрессии, а также данные по недавно разработанному антидепрессанту с подтвержденной клинической эффективностью — Вальдоксану. Этот препарат, обладающий свойствами агониста мелатонина и антагониста 5-НТ2С-рецепторов, является предвестником нового концептуального подхода к терапии депрессии

Leveraging mathematical models of disease dynamics and machine learning to improve development of novel malaria interventions

BACKGROUND: Substantial research is underway to develop next-generation interventions that address current malaria control challenges. As there is limited testing in their early development, it is difficult to predefine intervention properties such as efficacy that achieve target health goals, and therefore challenging to prioritize selection of novel candidate interventions. Here, we present a quantitative approach to guide intervention development using mathematical models of malaria dynamics coupled with machine learning. Our analysis identifies requirements of efficacy, coverage, and duration of effect for five novel malaria interventions to achieve targeted reductions in malaria prevalence. METHODS: A mathematical model of malaria transmission dynamics is used to simulate deployment and predict potential impact of new malaria interventions by considering operational, health-system, population, and disease characteristics. Our method relies on consultation with product development stakeholders to define the putative space of novel intervention specifications. We couple the disease model with machine learning to search this multi-dimensional space and efficiently identify optimal intervention properties that achieve specified health goals. RESULTS: We apply our approach to five malaria interventions under development. Aiming for malaria prevalence reduction, we identify and quantify key determinants of intervention impact along with their minimal properties required to achieve the desired health goals. While coverage is generally identified as the largest driver of impact, higher efficacy, longer protection duration or multiple deployments per year are needed to increase prevalence reduction. We show that interventions on multiple parasite or vector targets, as well as combinations the new interventions with drug treatment, lead to significant burden reductions and lower efficacy or duration requirements. CONCLUSIONS: Our approach uses disease dynamic models and machine learning to support decision-making and resource investment, facilitating development of new malaria interventions. By evaluating the intervention capabilities in relation to the targeted health goal, our analysis allows prioritization of interventions and of their specifications from an early stage in development, and subsequent investments to be channeled cost-effectively towards impact maximization. This study highlights the role of mathematical models to support intervention development. Although we focus on five malaria interventions, the analysis is generalizable to other new malaria interventions

Forced Abstinence from Cocaine Self-Administration is Associated with DNA Methylation Changes in Myelin Genes in the Corpus Callosum: a Preliminary Study

Background: Human cocaine abuse is associated with alterations in white matter integrity revealed upon brain imaging, an observation that is recapitulated in an animal model of continuous cocaine exposure. The mechanism through which cocaine may affect white matter is unknown and the present study tested the hypothesis that cocaine self-administration results in changes in DNA methylation that could result in altered expression of several myelin genes that could contribute to the effects of cocaine on white matter integrity. Methods: In the present study, we examined the impact of forced abstinence from cocaine self-administration on chromatin associated changes in white matter. To this end, rats were trained to self-administer cocaine (0.75 mg/kg/0.1 mL infusion) for 14 days followed by forced abstinence for 1 day (n = 6) or 30 days (n = 6) before sacrifice. Drug-free, sham surgery controls (n = 7) were paired with the experimental groups. Global DNA methylation and DNA methylation at specific CpG sites in the promoter regions ofmyelin basic protein (Mbp), proteolipid protein-1 (Plp1), and SRY-related HMG-box-10 (Sox10) genes were analyzed in DNA extracted from corpus callosum. Results: Significant differences in the overall methylation patterns of the Sox10 promoter region were observed in the corpus callosum of rats at 30 days of forced abstinence from cocaine self-administration relative to sham controls; the −189, −142, −93, and −62 CpG sites were significantly hypomethylated point-wise at this time point. After correction for multiple comparisons, no differences in global methylation or the methylation patterns of Mbp or Plp1 were found. Conclusion: Forced abstinence from cocaine self-administration was associated with differences in DNA methylation at specific CpG sites in the promoter region of the Sox10 gene in corpus callosum. These changes may be related to reductions in normal age related changes in DNA methylation and could be a factor in white matter alterations seen after withdrawal from repeated cocaine self-administration. Further research is warranted examining the effects of cocaine on DNA methylation in white matter