A stochastic individual based model for the growth of a stand of Japanese knotweed including mowing as a management technique

Invasive alien species are a growing threat for environment and health. They also have a major economic impact, as they can damage many infrastructures. The Japanese knotweed (Fallopia japonica), present in North America, Northern and Central Europe as well as in Australia and New Zealand, is listed by the World Conservation Union as one of the world's worst invasive species. So far, most models have dealt with how the invasion spreads without management. This paper aims at providing a model able to study and predict the dynamics of a stand of Japanese knotweed taking into account mowing as a management technique. The model we propose is stochastic and individual-based, which allows us taking into account the behaviour of individuals depending on their size and location, as well as individual stochasticity. We set plant dynamics parameters thanks to a calibration with field data, and study the influence of the initial population size, the mean number of mowing events a year and the management project duration on mean area and mean number of crowns of stands. In particular, our results provide the sets of parameters for which it is possible to obtain the stand eradication, and the minimal duration of the management project necessary to achieve this latter

Mathematical modeling of an urban pigeon population subject to local management strategies

International audienceThis paper addresses the issue of managing urban pigeon population using some possible actions that makes it reach a density target with respect to socio-ecological constraints. A mathematical model describing the dynamic of this population is introduced. This model incorporates the effect of some regulatory actions on the dynamic of this population. We then used mathematical viability theory, which provides a framework to study compatibility between dynamics and state constraints. The viability study shows when and how it is possible to regulate the pigeon population with respect to the constraints

A kd-tree algorithm to discover the boundary of a black box hypervolume or how to peel potatoes by recursively cutting them in halves

11 pagesInternational audienceGiven a subset of \R^\ndim of non-zero measure, defined through a blackbox function (an oracle), and assuming some regularity properties on this set, we build an efficient data structure representing this set. The naive approach would consists in sampling every point on a regular grid. As compared to it, our data structure has a complexity close to gaining one dimension both in terms of space and in number of calls to the oracle. This data structure produces a characteristic function (i.e. a function that can be used in lieu of the oracle), allows to measure the volume of the set, and allows to compute the distance to the boundary of the set for any point

Viabilitree: A kd-tree Framework for Viability-based Decision

The mathematical viability theory offers concepts and methods that are suitable to study the compatibility between a dynamical system described by a set of differential equations and constraints in the state space. The result sets built during the viability analysis can give very useful information regarding management issues in fields where it is easier to discuss constraints than objective functions. However, computational problems arise very quickly with the number of state variables, and the practical implementation of the method is difficult, although there exists a convergent numerical scheme and several approaches to bypass the computational problems. In order to popularize the use of viability analysis we propose a framework in which the viability sets are represented and approximated with particular kd-trees. The computation of the viability kernel is seen as an active learning problem. We prove the convergence of the algorithm and assess the approximation it produces for known problems with analytical solution. This framework aims at simplifying the declaration of the viability problem and provides useful methods to assist further use of viability sets produced by the computation

Hydrodynamic modelling and the dispersion of water fecal contaminants in current and future climates

10 p.International audienceDuring precipitation events in regions with combined sewers, overflows can occur upstream of drinking water treatment plants. The purpose of the research was to model the transport and propagation of pathogens and pharmaceuticals in the Rivière Des Prairies during flood and low flow events. The water quality is quantified in terms of the behaviour of the river, the interactions of contaminants with the environment and the impacts of climate change. Hydrosim was used for hydrodynamic modeling; Dispersim was used to model the dispersion of contaminants. The impact of climate change was represented by the change of flow in the river. To do so, simulations were performed using Hydrotel, a hydrologic model applied to the Ottawa River. Thus, the impact of dispersion and diffusion of contaminants on the water quality were analyzed to determine the potential impact on raw water quality. Water quality will be affected by lower flows and heavy rains, which will change the frequency distributions of fecal contaminants upon which microbial risk models are based

A novel “humanized mouse” model for autoimmune hepatitis and the association of gut microbiota with liver inflammation:Association of Gut Microbiota With Liver Inflammation

BACKGROUND: Autoimmune hepatitis (AIH) in humans is a severe inflammatory liver disease, characterized by interface hepatitis, the presence of circulating autoantibodies and hyper-gammaglobulinemia. There are two types of AIH, type-1 (AIH-1) and type-2 (AIH-2) characterized by distinct autoimmune serology. Patients with AIH-1 are positive for anti-smooth muscle and/or anti-nuclear (SMA/ANA) autoantibodies whereas patients with AIH-2 have anti-liver kidney microsomal type 1 (anti-LKM1) and/or anti-liver cytosol type 1 (anti-LC1) autoantibodies. Cytochrome P4502D6 (CYP2D6) is the antigenic target of anti-LKM1 and formiminotransferase cyclodeaminase (FTCD) is the antigenic target of anti-LC1. It is known that AIH, both type-1 and type-2, is strongly linked to the Human Leukocyte Antigen (HLA) alleles -DR3, -DR4 and -DR7. However, the direct evidence of the association of HLA with AIH is lacking. METHODS: We developed a novel mouse model of AIH using the HLA-DR3 transgenic mouse on the non-obese diabetic (NOD) background (HLA-DR3 NOD) by immunization of HLA-DR3(−) and HLA-DR3(+) NOD mice with a DNA plasmid, coding for human CYP2D6/FTCD fusion protein. RESULTS: Immunization with CYP2D6/FTCD leads to a sustained elevation of alanine aminotransferase (ALT), development of ANA and anti-LKM1/anti-LC1 autoantibodies, chronic immune cell infiltration and parenchymal fibrosis on liver histology in HLA-DR3(+) mice. Immunized mice also showed an enhanced Th1 immune response and paucity of the frequency of regulatory T-cell (Treg) in the liver. Moreover, HLA-DR3(+) mice with exacerbated AIH showed reduced diversity and total load of gut bacteria. CONCLUSION: Our humanized animal model has provided a novel experimental tool to further elucidate the pathogenesis of AIH and to evaluate the efficacy and safety of immunoregulatory therapeutic interventions in vivo

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Collective management of environmental commons with multiple usages: a guaranteed viability approach

In this paper we address the collective management of environmental commons with multiple usages in the framework of the mathematical viability theory. We consider that the stakeholders can derive from the study of their own socioeconomic problem the variables describing their different usages of the commons and its evolution, and a representation of the desirable states for the commons. We then consider the guaranteed viability kernel, subset of the set of desirable states where it is possible to maintain the state of the commons even when its evolution is represented by several conflicting models. This approach is illustrated on a problem of lake eutrophication.Comment: 22 pages, 4 figure