Plant water uptake modelling: added value of cross-disciplinary approaches.

In recent years, research interest in plant water uptake strategies has rapidly increased in many disciplines, such as hydrology, plant ecology and ecophysiology. Quantitative modelling approaches to estimate plant water uptake and spatiotemporal dynamics have significantly advanced through different disciplines across scales. Despite this progress, major limitations, for example, predicting plant water uptake under drought or drought impact at large scales, remain. These are less attributed to limitations in process understanding, but rather to a lack of implementation of cross-disciplinary insights into plant water uptake model structure. The main goal of this review is to highlight how the four dominant model approaches, that is, Feddes approach, hydrodynamic approach, optimality and statistical approaches, can be and have been used to create interdisciplinary hybrid models enabling a holistic system understanding that, among other things, embeds plant water uptake plasticity into a broader conceptual view of soil-plant feedbacks of water, nutrient and carbon cycling, or reflects observed drought responses of plant-soil feedbacks and their dynamics under, that is, drought. Specifically, we provide examples of how integration of Bayesian and hydrodynamic approaches might overcome challenges in interpreting plant water uptake related to different travel and residence times of different plant water sources or trade-offs between root system optimization to forage for water and nutrients during different seasons and phenological stages.

Towards quantitative root hydraulic phenotyping: novel mathematical functions to calculate plant-scale hydraulic parameters from root system functional and structural traits.

Predicting root water uptake and plant transpiration is crucial for managing plant irrigation and developing drought-tolerant root system ideotypes (i.e. ideal root systems). Today, three-dimensional structural functional models exist, which allows solving the water flow equation in the soil and in the root systems under transient conditions and in heterogeneous soils. Yet, these models rely on the full representation of the three-dimensional distribution of the root hydraulic properties, which is not always easy to access. Recently, new models able to represent this complex system without the full knowledge of the plant 3D hydraulic architecture and with a limited number of parameters have been developed. However, the estimation of the macroscopic parameters a priori still requires a numerical model and the knowledge of the full three-dimensional hydraulic architecture. The objective of this study is to provide analytical mathematical models to estimate the values of these parameters as a function of local plant general features, like the distance between laterals, the number of primaries or the ratio of radial to axial root conductances. Such functions would allow one to characterize the behaviour of a root system (as characterized by its macroscopic parameters) directly from averaged plant root traits, thereby opening new possibilities for developing quantitative ideotypes, by linking plant scale parameters to mean functional or structural properties. With its simple form, the proposed model offers the chance to perform sensitivity and optimization analyses as presented in this study.

[Anemia by self-injury: the Lasthenie de Ferjol syndrome]. / L'anémie par spoliation sanguine volontaire: le syndrome de Lasthénie de Ferjol.

Patients with factitious disorders need to be ill and to defy physicians. These syndromes are difficult to diagnose because of the permanent disorder appearing inside the therapeutic relation. The case of a young woman who presents with a factitious anemia, also called Lasthenie de Ferjol syndrome, shows the complexity of such psychosomatic symptoms.

[Electroconvulsive therapy and its mechanism of action]. / L'électroconvulsivothérapie et ses mécanismes d'actions.

Electroconvulsive therapy (ECT) is known as an effective treatment for some depressive disorders. Nevertheless ECT continues to be a subject of controversy. The absence of a unifying theory for its mechanisms of action explains the mistrust about ECT. The aim of this article is to review the literature about ECT and to propose a synthesis concerning its mechanisms of action. At the present time, the most reliable hypothesis suggests selective activations of central serotonergic and dopaminergic systems on the one hand, and a direct stimulation of the neuroendocrine neurons on the other hand.