Wood mouse feeding effort and decision-making when encountering a restricted unknown food source

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Animals making foraging decisions must balance the energy gained, the time invested, and the influence of key environmental factors. In our work, we examined the effect of predation risk cues and experience on feeding efforts when a novel food resource was made available. To achieve this, we live-trapped wood mouse Apodemus sylvaticus in Monte de Valdelatas (Madrid), where 80 Sherman traps were set in four plots. Traps were subjected to two food-access difficulties in treatments consisting of three consecutive nights: open plastic bottles (easy) and closed bottles (difficult), both using corn as bait. To simulate predation risk, we set fox faeces in half of the traps in each plot. We also considered moonlight (medium/low) as an indirect predation risk cue. We analysed whether bottles had been bitten by mice and the gnawed area of each bottle was measured. Our results indicated that food access difficulty, experience, and predation risk determined mice feeding decisions and efforts. The ability of mice to adapt feeding effort when a new food source is available was demonstrated because a higher proportion of closed bottles exhibited bite marks and the gnawed area was bigger. Moreover, mouse experience was determinant in the use of this new resource since recaptured mice gnawed broader orifices in the bottles and the gnawed area increased each time an individual was recaptured. Additionally, direct predation risk cues prompted mice to bite the bottles whereas the effect of different moon phases varied among the food access treatments. This study provides direct evidence of formidable efficacy of wild mice to exploit a new nutrient resource while considering crucial environmental factors that shape the decision-making procedur

Estudi del procés de mineralització en el sòl compost de deixalles

Per tal de conèixer i poder explicar tots els processos que segueixen les diferents formes nitrogenades d'un sòl en el qual s'ha barrejat compost de residus sòlids urbans, es fan servir dos mètodes diferents: I- Incubació de les barreges sota condicions controlades, registrant l'activitat microbiana mitjançant una respirometria i analizant periòdicament el nivell de N-NH4+, N-NO3-. N.org. sol., N org. total i de C ox. sol. que hi ha a la barreja. II- Assaig de conreu de margall en tests, prenent mensualment mostres de substrat, del qual s'analitza el mateix que a les incubacions, i mostres de teixits vegetals, dels quals es determina la producció total i la riquesa en nitrogen. La mineralització del nitrogen i la producció vegetal als tractaments adobats amb compost presenten un retard considerable respecte als controls més com més alta és l'activitat dels microorganismes. Aquest retard s'atribueix a la immobilització microbiana.To know amd to explain the processes followed by the different nitrogenate forms of a soil where compost of City garbage has been added, two methods are used: I- Incubation of the mixture under controllate conditions, studying the microbial activity with respirometry and periodically analysing the level of N-NO3-, water soluble organic N, total organic N and oxidable water soluble carbon of the mixture. II- Growing test of ray grass in pots, taking soil and vegetable samples monthly doing the same analysis than in the incubation for the soil and controlling total dry production and nitrogen content for the ray grass. The high doses of compost used and its low stability initially produce nitrogen immobilization in the incubation as well as in the growing tests.Para conocer y poder explicar todos los procesos que siguen las diferentes formas nitrogenadas de un suelo al que se le ha mezclado compost de residus urbanos, se utilizan dos métodos diferentes: I- Incubación de la mezcla bajo condiciones controladas, registrando la actividad microbiana mediante una respirometria y analizando periódicamente el nivel de N-NH4 +, N-NO3-, N org. sol., N org. total y de C ox. sol. que hay en la mezcla. II- Ensayo de cultivo de ray-gras en macetas, tomando mensualmente muestras de sustrato, del que se analiza lo mismo que en las incubaciones, y muestras de tejido vegetal, del que se determina la producción total y la riqueza en nitrógeno. La mineralización del nitrógeno y la producción vegetal en los tratamientos abonados con compost presentan un retraso considerable respecto al control, mayor cuanto mayor es la actividad de los microorganismos. Este retraso se atribuye a la inmovilización microbiana

Diffusion–dispersion numerical discretization for solute transport in 2D transient shallow flows

The 2D solute transport equation can be incorporated into the 2D shallow water equations in order to solve both flow and solute interactions in a coupled system of equations. In order to solve this system, an explicit finite volume scheme based on Roe’s linearization is proposed. Moreover, it is feasible to decouple the solute transport equation from the hydrodynamic system in a conservative way. In this case, the advection part is solved in essence defining a numerical flux, allowing the use of higher order numerical schemes. However, the discretization of the diffusion–dispersion terms have to be carefully analysed. In particular, time-step restrictions linked to the nature of the solute equation itself as well as the numerical diffusion associated to the numerical scheme used are question of interest in this work. These improvements are tested in an analytical case as well as in a laboratory test case with a passive solute (fluorescein) released from a reservoir. Experimental measurements are compared against the numerical results obtained with the proposed model and a sensitivity analysis is carried out, confirming an agreement with the longitudinal coefficients and an underestimation of the transversal ones, respectively

Implicit finite volume simulation of 2D shallow water flows in flexible meshes

In this work, an implicit method for solving 2D hyperbolic systems of equations is presented, focusing on the application to the 2D shallow water equations. It is based on the first order Roe''s scheme, in the framework of finite volume methods. A conservative linearization is done for the flux terms, leading to a non-structured matrix for unstructured meshes thus requiring iterative methods for solving the system. The validation is done by comparing numerical and exact solutions in both unsteady and steady cases. In order to test the applicability of the implicit scheme to real world situations, a laboratory scale tsunami simulation is carried out and compared to the experimental data. The implicit schemes have the advantage of the unconditional stability, but a quality loss in the transient solution can appear for high CFL numbers. The properties of the scheme are well suited for the simulation of unsteady shallow water flows over irregular topography using all kind of meshes

Implicit 2D surface flow models performance assessment: Shallow Water Equations vs. Zero-Inertia Model

Zero-Inertia (ZI) models are used in overland flow simulation due to their mathematical simplicity, compared to more complex formulations such as Shallow Water (SW) models. The main hypothesis in ZI models is that the flow is driven by water surface and friction gradients, neglecting local accelerations. On the other hand, SW models are a complete dynamical formulation that provide more information at the cost of a higher level of complexity. In realistic problems, the usually huge number of cells required to ensure accurate spatial representation implies a large amount of computing effort and time. This is particularly true in 2D models. Hence, there is an interest in developing efficient numerical methods. In general terms, numerical schemes used to solve time dependent problems can be classified in two groups, attending to the time evaluation of the unknowns: explicit and implicit methods. Explicit schemes offer the possibility to update the solution at every cell from the known values but are restricted by numerical stability reasons. This can lead to very slow simulations in case of using fine meshes. Implicit schemes avoid this restriction at the cost of generating a system of as many equations as computational cells multiplied by the number of variables to solve. In this work, an implicit finite volume numerical scheme has been used to solve the 2D equations in both ZI and SW models. The scheme is formulated so that both quadrilateral and triangular meshes can be used. A conservative linearization is done for the flux terms, leading to a non-structured matrix for unstructured meshes thus requiring iterative methods for solving the system. A comparison between 2D SW and 2D ZI is done in terms of performance, efficiency and mesh requirements, in which both models benefit of an implicit temporal discretization in steady and nearly-steady situations

Coupled environmental and demographic fluctuations shape the evolution of cooperative antimicrobial resistance

There is a pressing need to better understand how microbial populations respond to antimicrobial drugs, and to find mechanisms to possibly eradicate antimicrobial-resistant cells. The inactivation of antimicrobials by resistant microbes can often be viewed as a cooperative behavior leading to the coexistence of resistant and sensitive cells in large populations and static environments. This picture is however greatly altered by the fluctuations arising in volatile environments, in which microbial communities commonly evolve. Here, we study the eco-evolutionary dynamics of a population consisting of an antimicrobial resistant strain and microbes sensitive to antimicrobial drugs in a time-fluctuating environment, modeled by a carrying capacity randomly switching between states of abundance and scarcity. We assume that antimicrobial resistance is a shared public good when the number of resistant cells exceeds a certain threshold. Eco-evolutionary dynamics is thus characterized by demographic noise (birth and death events) coupled to environmental fluctuations which can cause population bottlenecks. By combining analytical and computational means, we determine the environmental conditions for the long-lived coexistence and fixation of both strains, and characterize a fluctuation-driven antimicrobial resistance eradication mechanism, where resistant microbes experience bottlenecks leading to extinction. We also discuss the possible applications of our findings to laboratory-controlled experiments.Comment: 19+7 pages, 4+1 figures. Simulation data and codes for all figures are electronically available from the University of Leeds Data Repository. DOI: https://doi.org/10.5518/136

Use of internal boundary conditions for levees representation: application to river flood management

River floods can be simulated with the 2D shallow water system of equations using finite volume methods, where the terrain is discretized in cells that form the computational mesh. Usually a proper treatment of wet/dry fronts is required. River levees can be modelled as part of the topography by means of sufficiently small cells of higher elevation than the rest of the bed level in locally refined meshes. This procedure is associated with a large computational time since the time step depends directly on the cell size. The alternative proposed in this work includes the levees as internal boundary conditions in the 2D numerical scheme. In particular, levees have been defined by a weir law that, depending on the relative values of water surface levels on both sides, can formulate the discharge for different situations (i.e. free flow and submerged flow). In addition, having identified numerical difficulties in cases of low discharge under free flow conditions, a novel procedure to avoid oscillations has been developed and called volume transport method. The validation and comparison between methods has been carried out with benchmark test cases and, in addition, with a real flood event in the Ebro River (Spain)

2D numerical simulation of unsteady flows for large scale floods prediction in real time

The challenge of finding a compromise between computational time and level of accuracy and robustness has traditionally expanded the use simplified models rather than full two-dimensional (2D) models for flood simulation. This work presents a GPU accelerated 2D shallow water model for the simulation of flood events in real time. In particular, an explicit first-order finite volume scheme is detailed to control the numerical instabilities that are likely to appear when used in complex topography. The model is first validated with the benchmark test case of the Toce River (Italy) and numerical fixes are demonstrated to be necessary. The model is next applied to reproduce real events in a reach of the Ebro River (Spain) in order to compare simulation results with field data. The second case deals with a large domain (744 km2) and long flood duration (up to 20 days) allowing an analysis of the performance and speed-up achieved by different GPU devices. The high values of fit between observed and simulated results as well as the computational times achieved are encouraging to propose the use of the model as forecasting system

Estudio de las redes educativas de centros escolares en Andalucía (España): claves para su análisis de la evaluación de los asesores de centros de profesores

Every school constitutes a singular case when it comes to changes and improvements as each of them belongs to a social and cultural context with their own idiosyncrasy and needs. This article aims to study 12 in depth a research on educative networks organized in groups of teachers, focusing on its origin, structure, resources, organization and impact. The process of data gathering has followed a descriptivenarrative methodology, based on a qualitative research, and using a questionnaire for advisors in Teachers Centers within Seville, where they inform about the benefits of networking. The results of the analysis show that the development and setting of these networks occur in response to both the need of support that teachers are sometimes missing in their professional day to day; and the requirements of the regional inspection service of education, Servicio de Inspección Educativa, in order to cope with basic difficulties that may arise in the teaching learning process, such as the reading and writing learning process or the improvement of the coexistence within the educational community. Feedback from this research proves the impact that the networking procedures have had in the educational community and centers, as well as its positive results and improvements in their development.Cada escuela se constituye en un caso especial para la implementación de cambios y mejoras, de forma que cada una responde a un contexto social y cultural con su propia idiosincrasia y necesidades. El objetivo principal del artículo es dar a conocer el estudio de las redes educativas configuradas en grupos de trabajo entre profesores en lo que se refiere a su origen, diseño, recursos, organización e impacto, con la finalidad de profundizar en su funcionamiento y repercusión en los centros escolares. Para la recogida de datos se ha utilizado una metodología descriptivo narrativa, basada en la investigación cualitativa, a partir de un cuestionario para asesores de centros de profesores de Sevilla capital y provincia, donde informan de la idoneidad del trabajo en red. Los resultados del análisis determinan que el desarrollo y puesta en marcha de las redes responde a las necesidades de apoyo que los docentes encuentran en su desarrollo profesional y a la exigencia del Servicio de Inspección Educativa para paliar problemas básicos dentro del proceso de enseñanza aprendizaje, como es el aprendizaje de la lectoescritura y la mejora de la convivencia en la comunidad educativa. Las principales conclusiones reconocen el impacto del trabajo en red en los centros y en la comunidad educativa, sus resultados y las mejoras en el desarrollo de las mismas