Individual-Based Modelling Potentials and Limitations

Individual-based modelling (IBM) is an important option in ecology for the study of specific properties of complex ecological interaction networks. The main application of this model type is the analysis of population characteristics at high resolution. IBM also contributes to the advancement of ecological theory. One of the remarkable potentials of the approach is the possibility of studying self-organization and emergent properties that arise from individual actions on higher integration levels, especially on the population level

A Review of Time Relaxation Methods

The time relaxation model has proven to be effective in regularization of Navier–Stokes Equations. This article reviews several published works discussing the development and implementations of time relaxation and time relaxation models (TRMs), and how such techniques are used to improve the accuracy and stability of fluid flow problems with higher Reynolds numbers. Several analyses and computational settings of TRMs are surveyed, along with parameter sensitivity studies and hybrid implementations of time relaxation operators with different regularization techniques

An individual-based approach to depict the influence of the feeding strategy on the population structure of roach (Rutilus rutilus L.)

AbstractWe used an individual-based modelling strategy to simulate the growth of a roach population. Individual growth is based on food utilization, bioenergetics, spatial distribution, and seasonal influences. With this approach, it is possible to connect the animals' activity pattern with the energetic needs required for this activity. This allows investigating the role of spatial heterogeneity and individual variability for the dynamics of fish growth. The parameterisation is based on laboratory measurements and field studies performed at Lake Belau (Schleswig-Holstein, Northern Germany). The interactions of the behavioural repertoire, growth processes, and food preferences emerge in the context of a decreasing proportion of zooplankton in the food composition of simulated roach. Roach feeding on molluscs grow faster. The ontogenetic shift is related to the necessity to switch to larger prey as a consequence of the increase of energetic demands with body size

Religious melancholy in the music of John Dowland

This study examines the religious music of John Dowland as it relates to his association with the Elizabethan cult of melancholy. In examining his music, I have distinguished several different types of melancholy and I feel that Dowland’s musical treatment of these types is more nuanced then has yet been recognized. While scholars from the early modern era realized that the complaint of melancholy was a highly complex, multi-faceted issue, modern scholars tend to identify the melancholy tendencies of Dowland’s music as a one-dimensional concept. By exploring the expression of religious melancholy in the music of Dowland through the lens of contemporaneous medical and religious treatises, I am applying the early seventeenth-century conception of melancholy in my own interpretation of Dowland’s religious-themed music

The birds of Gongoni Forest Reserve, South Coast, Kenya

Between November 2007 and February 2008, bird species composition, richness and abundance were assessed at Gongoni Forest Reserve (classified as a Key Biodiversity Area) using transect and timed-species counts. A total of 140 bird species in 51 families were recorded with species accumulation curves indicating that a few more species could be discovered with additional search efforts. Four Near Threatened species―Southern Banded Snake Eagle Circaetus fasciolatus, Sooty Falcon Falco concolor, Martial Eagle Polemaetus bellicocus and Fischer’s Turaco Tauraco fischeri, 15 East Africa Coast biome species and 13 regionally threatened species were recorded. Owing to the presence of these species of conservation concern both globally and regionally, and past and ongoing threats, this site merits more attention than previously accorded

Discrete and continuous time simulations of spatial ecological processes predict different final population sizes and interspecific competition outcomes

Cellular automata (CAs) are commonly used to simulate spatial processes in ecology. Although appropriate for modelling events that occur at discrete time points, they are also routinely used to model biological processes that take place continuously. We report on a study comparing predictions of discrete time CA models to those of their continuous time counterpart. Specifically, we investigate how the decision to model time discretely or continuously affects predictions regarding long-run population sizes, the probability of extinction and interspecific competition. We show effects on predicted ecological outcomes, finding quantitative differences in all cases and in the case of interspecific competition, additional qualitative differences in predictions regarding species dominance. Our findings demonstrate that qualitative conclusions drawn from spatial simulations can be critically dependent on the decision to model time discretely or continuously. Contrary to our expectations, simulating in continuous time did not incur a heavy computational penalty. We also raise ecological questions on the relative benefits of reproductive strategies that take place in discrete and continuous time

A framework for a European network for a systematic environmental impact assessment of genetically modified organisms (GMO)

The assessment of the impacts of growing genetically modified (GM) crops remains a major political and scientific challenge in Europe. Concerns have been raised by the evidence of adverse and unexpected environmental effects and differing opinions on the outcomes of environmental risk assessments (ERA). The current regulatory system is hampered by insufficiently developed methods for GM crop safety testing and introduction studies. Improvement to the regulatory system needs to address the lack of well designed GM crop monitoring frameworks, professional and financial conflicts of interest within the ERA research and testing community, weaknesses in consideration of stakeholder interests and specific regional conditions, and the lack of comprehensive assessments that address the environmental and socio economic risk assessment interface. To address these challenges, we propose a European Network for systematic GMO impact assessment (ENSyGMO) with the aim directly to enhance ERA and post-market environmental monitoring (PMEM) of GM crops, to harmonize and ultimately secure the long-term socio-political impact of the ERA process and the PMEM in the EU. These goals would be achieved with a multi-dimensional and multi-sector approach to GM crop impact assessment, targeting the variability and complexity of the EU agro-environment and the relationship with relevant socio-economic factors. Specifically, we propose to develop and apply methodologies for both indicator and field site selection for GM crop ERA and PMEM, embedded in an EU-wide typology of agro-environments. These methodologies should be applied in a pan-European field testing network using GM crops. The design of the field experiments and the sampling methodology at these field sites should follow specific hypotheses on GM crop effects and use state-of-the art sampling, statistics and modelling approaches. To address public concerns and create confidence in the ENSyGMO results, actors with relevant specialist knowledge from various sectors should be involved

In-Situ Visualization of Long-Range Defect Interactions at the Edge of Melting

Connecting a bulk material's microscopic defects to its macroscopic properties is an age-old problem in materials science. Long-range interactions between dislocations (line defects) are known to play a key role in how materials deform or melt, but we lack the tools to connect these dynamics to the macroscopic properties. We introduce time-resolved dark-field X-ray microscopy to directly visualize how dislocations move and interact over hundreds of micrometers, deep inside bulk aluminum. With real-time movies, we reveal the thermally-activated motion and interactions of dislocations that comprise a boundary, and show how weakened binding forces inhomogeneously destabilize the structure at 99% of the melting temperature. Connecting dynamics of the microstructure to its stability, we provide important opportunities to guide and validate multiscale models that are yet untested