Simplification rationnelle des outils hydrologiques de gestion : recommandations méthodologiques pour la construction de modèles semi-empiriques à origine mécaniste

Les modèles de simulation hydrologiques sont reconnus comme des outils mathématiques très performants mais généralement d'application difficile, principalement à cause du nombre élevé des paramètres requis. À l'inverse, les outils actuels de gestion sont généralement développés à l'aide d'approches empiriques limitant leur application. De plus, leurs paramètres ne sont pas des grandeurs mesurables et doivent être ajustés pour chaque situation. Une approche est proposée pour le développement d'outils semi empiriques de gestion. Elle consiste à simuler un grand nombre de scénarios en utilisant un modèle complexe de simulation puis à rationaliser l'information obtenue pour développer un nouveau modèle semi empirique. L'exemple illustrant cette approche concerne l'évaluation des flux d'eau ruisselée à la surface des champs, lessivée vers la nappe souterraine et drainée par les drains agricoles spécifiquement pour le contexte du Québec. À partir des résultats de simulation de 4500 scénarios, une simplification.rationalisation a permis de réduire à 120 le nombre de scénarios de référence à l'aide desquels peuvent être évalués tous les scénarios possibles par de simples interpolations linéaires. Une application de l'algorithme résultant sur un site du Québec a montré la bonne concordance entre les résultats calculés et mesurés. À la fois l'ordre de grandeur du ruissellement et du drainage et leur grandeur relative sont bien évalués.Considering the complexity of the water cycle in soil systems, models are used more than ever in parallel with field investigations to assist in the decision making process (KHAKURAL et ROBERT, 1993). Most available models are either too complicated (many non-measurable parameters) or too simple (empirical or site-specific) to be used as management tools. Such tools should conform to known theory and should be structured to enable efficient analysis of field situations with minimal requirements for parameters (CARSEL et al 1984). However, if the mechanistic models are very performing tools with regards to their representation of the processes and for the accuracy and reliability of their results, they are criticized for their complexity and for the large number of parameters they require. For this reason, their potential application as management tools cannot be recommended especially in preliminary investigations when the methodology has to be straight forward and rapidly implemented. On the other hand, existing management tools are often developed using an empirical approach for a specific context which considerably limits their transferability to different situations. Moreover, their empirical parameters often cannot be measured for the new situations, and must be adjusted for each new application. A new approach conciliating the qualities of both kinds of tools was elaborated for the development of management tools. This approach consists in using mechanistic models for simulating a set of possible situations and in rationalizing the information obtained by simulation through regression analyses or other methods. An example of this methodology is presented in this paper with the development of the hydrological part (runoff, leaching and drainage) of a management tool dedicated to the evaluation of nutrient losses related to manure applications. Developed for the Quebec conditions, 4500 theoretical situations were considered corresponding to ten climates, nine soil textures, 25 crops and two slope values. Independently, agricultural management practices and drainage were taken into account.For the mechanistic simulation of the water budget in the 4500 theoretical situations, the hydrologic module of the mechanistic-stochastic model AgriFlux was used (BANTON et al. 1993b). Because of the important field variability of most parameters, the stochastic AgriFlux model incorporates the variability resulting from field heterogeneity, measurement errors and intrinsic uncertainty related to parameter definition. The soil profile is divided in plot scale homogeneous horizons (or compartments) and a daily time step is used in the calculations. The water budget module in AgriFlux is named HydriFlux and simulates all the water-related processes (precipitations, snowmelt, infiltration, runoff, water uptake by plants, evaporation, percolation and drainage) using characteristic water contents and unsaturated hydraulic conductivity.In the example presented, the simulation results obtained by running HydriFlux have shown that the soil water fluxes (runoff and percolation) vary as linear functions of both the annual rain volume (the most important characteristic of the climate) and the logarithm of the saturated hydraulic conductivity (the most important characteristic of the soil type). A reduction of the number of crops could also be achieved by taking into account the water needs and the water uptake curves of the crops. This rationalization-simplification reduced the number of theoretical simulations to be stored in the management tool to 120 (2 climates x 3 textures x 10 crops x 2 slopes). These represent only 2.7% of the initial situations simulated by the mechanistic HydriFlux model. The different water fluxes are stored in the management tool as tables in which direct interpolations are performed to calculate the fluxes corresponding to all the potential intermediary situations. Such developed management tool presents good qualities at the same time for its calculation speed, for its easy parameterization, for the reliability of its evaluation (through the evaluation of the mechanistic model) and for its high transferability and applicability to various situations. The calculations are rapidly done and their programming can be very easily made by using a spreadsheet software.An application of this evaluation method has been done on an experimental site located in Quebec (ENRIGHT et MADRAMOOTOO, 1994), the only one for which both the runoff and the drainage have been measured during many years (1989 to 1991, April to December). The application on two fields (1.84 et 4.63 ha) has shown a good concordance between the calculated and measured results, as well for the magnitude of the fluxes than for the relative importance of these fluxes. Moreover, this application has shown that the variability of the measured values is higher than the calculated ones, attesting of the great influence of the variations in climatic, soil, crop and management conditions on the water budget. However, the good evaluation of the fluxes (for relative and absolute values) confirms the reliability of the proposed approach and of the simplification

Antioxidant oils and Salmonella enterica Typhimurium reduce tumor in an experimental model of hepatic metastasis

Fruit seeds high in antioxidants have been shown to have anticancer properties and enhance host protection against microbial infection. Recently we showed that a single oral dose of Salmonella enterica serovar Typhimurium expressing a truncated human interleukin-2 gene (SalpIL2) is avirulent, immunogenic, and reduces hepatic metastases through increased natural killer cell populations in mice. To determine whether antioxidant compounds enhance the antitumor effect seen in SalpIL2-treated animals, we assayed black cumin (BC), black raspberry (BR), and milk thistle (MT) seed oils for the ability to reduce experimental hepatic metastases in mice. In animals without tumor, BC and BR oil diets altered the kinetics of the splenic lymphocyte response to SalpIL2. Consistent with previous reports, BR and BC seed oils demonstrated independent antitumor properties and moderate adjuvant potential with SalpIL2. MT oil, however, inhibited the efficacy of SalpIL2 in our model. Based on these data, we conclude that a diet high in antioxidant oils promoted a more robust immune response to SalpIL2, thus enhancing its antitumor efficacy

Increased prevalence of expiratory flow limitation during exercise in children with bronchopulmonary dysplasia.

Evidence regarding the prevalence of expiratory flow limitation (EFL) during exercise and the ventilatory response to exercise in children born preterm is limited. This study aimed to determine the prevalence of EFL as well as contributing factors to EFL and the ventilatory response to exercise in preterm children with and without bronchopulmonary dysplasia (BPD). Preterm children (=32 weeks gestational age) aged 9-12 years with (n=64) and without (n=42) BPD and term controls (n=43), performed an incremental treadmill exercise test with exercise tidal flow-volume loops. More preterm children with BPD (53%) had EFL compared with preterm children without BPD (26%) or term controls (28%) (p<0.05). The presence of EFL was independently associated with decreased forced expiratory volume in 1 s/forced vital capacity z-score and lower gestational age (p<0.05). There was no difference in peak oxygen uptake between preterm children with BPD and term controls (48.0 versus 48.4 mL·kg-1·min-1; p=0.063); however, children with BPD had a lower tidal volume at peak exercise (mean difference -27 mL·kg-1, 95% CI -49-?-5; p<0.05). Children born preterm without BPD had ventilatory responses to exercise similar to term controls. Expiratory flow limitation is more prevalent in children born preterm with BPD and is associated with airway obstruction and a lower gestational age

Highlights from the 6th International Society for Computational Biology Student Council Symposium at the 18th Annual International Conference on Intelligent Systems for Molecular Biology

This meeting report gives an overview of the keynote lectures and a selection of the student oral and poster presentations at the 6th International Society for Computational Biology Student Council Symposium that was held as a precursor event to the annual international conference on Intelligent Systems for Molecular Biology (ISMB). The symposium was held in Boston, MA, USA on July 9th, 2010

'Soldiering by consent' amd military-civil relations: Military transition into the public space of policing

Growth in the Armed Forces undertaking public policing is occurring in the United Kingdom and elsewhere and as such a complex security landscape emerges, both practically and conceptually. The aim here is to pose questions of the manifest and latent issues in the assemblage of multiple actors in public policing. It aks to reader to consider the implications of military actors transitioning from defence duties ordinarily associated with military work, to policing activities in public spaces. Taking the London 2012 Olympic Games as our point of reference, this article argues that to understand military presence, their role must be considered in the broader context of military and policing functions, the ‘war on terror’, accountability, and future priorities for public policing. We must be careful not to assign the presence of the military into pre-existing understandings of how mega-events should be secured – the military patrolling the streets of London represents more. Instead, as their presence comes to be legitimate in certain geopolitical contexts, critical questions must be asked especially as public and private arrangements are continually reworked in the domestic fight against terrorism

The re-professionalization of the police in England and Wales

In this article contemporary police claims to professional status are analysed and related to a new structure of police regulation in England and Wales. It is argued that the notion of the police as a profession is not new and, unlike police and academic commentary, analysis of this subject, should draw on sociological understandings of professions. The wider policy context within which claims to professionalisation are made is also considered. It is argued that a new, loosely-coupled system of regulation has been developed in England and Wales. Policing’s professional body, the College of Policing, is central to this regulatory framework that has placed government at a distance from constabularies and police representative associations. Finally, some of the consequences of the hybrid system are considered and benefits of the framework of analysis proposed are discussed

Impact of local recharge on arsenic concentrations in shallow aquifers inferred from the electromagnetic conductivity of soils in Araihazar, Bangladesh

The high-degree of spatial variability of dissolved As levels in shallow aquifers of the Bengal Basin has been well documented but the underlying mechanisms remain poorly understood. We compare here As concentrations measured in groundwater pumped from 4700 wells <22 m (75 ft) deep across a 25 km2 area of Bangladesh with variations in the nature of surface soils inferred from 18,500 measurements of frequency domain electromagnetic induction. A set of 14 hand auger cores recovered from the same area indicate that a combination of grain size and the conductivity of soil water dominate the electromagnetic signal. The relationship between pairs of individual EM conductivity and dissolved As measurements within a distance of 50 m is significant but highly scattered (r2 = 0.12; n = 614). Concentrations of As tend to be lower in shallow aquifers underlying sandy soils and higher below finer-grained and high conductivity soils. Variations in EM conductivity account for nearly half the variance of the rate of increase of As concentration with depth, however, when the data are averaged over a distance of 50 m (r2 = 0.50; n = 145). The association is interpreted as an indication that groundwater recharge through permeable sandy soils prevents As concentrations from rising in shallow reducing groundwater

On the Functional Significance of the P1 and N1 Effects to Illusory Figures in the Notch Mode of Presentation

The processing of Kanizsa figures have classically been studied by flashing the full “pacmen” inducers at stimulus onset. A recent study, however, has shown that it is advantageous to present illusory figures in the “notch” mode of presentation, that is by leaving the round inducers on screen at all times and by removing the inward-oriented notches delineating the illusory figure at stimulus onset. Indeed, using the notch mode of presentation, novel P1and N1 effects have been found when comparing visual potentials (VEPs) evoked by an illusory figure and the VEPs to a control figure whose onset corresponds to the removal of outward-oriented notches, which prevents their integration into one delineated form. In Experiment 1, we replicated these findings, the illusory figure was found to evoke a larger P1 and a smaller N1 than its control. In Experiment 2, real grey squares were placed over the notches so that one condition, that with inward-oriented notches, shows a large central grey square and the other condition, that with outward-oriented notches, shows four unconnected smaller grey squares. In response to these “real” figures, no P1 effect was found but a N1 effect comparable to the one obtained with illusory figures was observed. Taken together, these results suggest that the P1 effect observed with illusory figures is likely specific to the processing of the illusory features of the figures. Conversely, the fact that the N1 effect was also obtained with real figures indicates that this effect may be due to more global processes related to depth segmentation or surface/object perception