A GIS model-based assessment of the environmental distribution of g-hexachlorocyclohexane in European soils and waters

The MAPPE GIS based multimedia model is used to produce a quantitative description of the behaviour of γ-hexachlorocyclohexane (γ-HCH) in Europe, with emphasis on continental surface waters. The model is found to reasonably reproduce γ-HCH distributions and variations along the years in atmosphere and soil; for continental surface waters, concentrations were reasonably well predicted for year 1995, when lindane was still used in agriculture, while for 2005, assuming severe restrictions in use, yields to substantial underestimation. Much better results were yielded when same mode of release as in 1995 was considered, supporting the conjecture that for γ-HCH, emission data rather that model structure and parameterization can be responsible for wrong estimation of concentrations. Future research should be directed to improve the quality of emission data. Joint interpretation of monitoring and modelling results, highlights that lindane emissions in Europe, despite the marked decreasing trend, persist beyond the provisions of existing legislation. An spatially-explicit multimedia modelling strategy was applied to describe the historical distribution of γ-HCH in European soils and surface waters

Open-cast mine slope deformation and failure mechanisms interpreted from slope radar monitoring

The monitoring of open-pit mine slopes using radar systems is becoming more and more common. The output from radar monitoring is the displacement of the full slope surface after each radar scan, allowing displacements, velocities and acceleration to be determined. The displacement trends obtained from radar monitoring are a representation of the deformation taking place within the mine slope. The research deals with the analysis of the displacement trends in order to understand the slope deformation behaviour. The main objectives of this research work were: To interpret the deformation behaviour and failure mechanisms of open-cast mine slopes based primarily on displacement data from radar monitoring; and To develop a method using the radar displacement data for predicting the time to failure of open-cast mine slopes. The research established that slope failure is preceded by the gradual accumulation of deformation within the slope. Identifying where the deformation is taking place, the magnitudes and state of the deformation is crucial in understanding and interpreting the slope deformation and failure mechanisms. The main accomplishments of the research include: The interpretation of deformation and failure mechanisms from radar displacement data of both stable and unstable open-cast mine slopes. The interpretation of deformation was used in classifying the deformation behaviour of unstable open-cast mine slopes into five main stages, consisting of three pre-failure stages and two post-failure stages. From the displacement data, two types of deformation behaviour of stable slopes were also identified; The development of a simple model for estimating the threshold values for the cumulative rate of displacement. The cumulative rate of displacement threshold determines when mine personnel and equipment must evacuate the unstable area of the slope. The model can also be used to effectively identify the deformation state of open-cast mine slopes; and The development of a Slope Failure Prediction Model (SFPM) for estimating the time to failure of open-cast mine slopes. The model was effective in predicting the time to failure when validated with four case examples of open cast mine slope failures. The development of the SFPM is a novel approach which provides an automated prediction of time to failure

Nemo: a computational tool for analyzing nematode locomotion

The nematode Caenorhabditis elegans responds to an impressive range of chemical, mechanical and thermal stimuli and is extensively used to investigate the molecular mechanisms that mediate chemosensation, mechanotransduction and thermosensation. The main behavioral output of these responses is manifested as alterations in animal locomotion. Monitoring and examination of such alterations requires tools to capture and quantify features of nematode movement. In this paper, we introduce Nemo (nematode movement), a computationally efficient and robust two-dimensional object tracking algorithm for automated detection and analysis of C. elegans locomotion. This algorithm enables precise measurement and feature extraction of nematode movement components. In addition, we develop a Graphical User Interface designed to facilitate processing and interpretation of movement data. While, in this study, we focus on the simple sinusoidal locomotion of C. elegans, our approach can be readily adapted to handle complicated locomotory behaviour patterns by including additional movement characteristics and parameters subject to quantification. Our software tool offers the capacity to extract, analyze and measure nematode locomotion features by processing simple video files. By allowing precise and quantitative assessment of behavioral traits, this tool will assist the genetic dissection and elucidation of the molecular mechanisms underlying specific behavioral responses.Comment: 12 pages, 2 figures. accepted by BMC Neuroscience 2007, 8:8

Behavioural effects of the common brain-infecting parasite Pseudoloma neurophilia in laboratory zebrafish (Danio rerio)

Research conducted on model organisms may be biased due to undetected pathogen infections. Recently, screening studies discovered high prevalence of the microsporidium Pseudoloma neurophilia in zebrafish (Danio rerio) facilities. This spore-forming unicellular parasite aggregates in brain regions associated with motor function and anxiety, and despite its high occurrence little is known about how sub-clinical infection affects behaviour. Here, we assessed how P. neurophilia infection alters the zebrafish´s response to four commonly used neurobehavioral tests, namely: mirror biting, open field, light/dark preference and social preference, used to quantify aggression, exploration, anxiety, and sociability. Although sociability and aggression remained unaltered, infected hosts exhibited reduced activity, elevated rates of freezing behaviour, and sex-specific effects on exploration. These results indicate that caution is warranted in the interpretation of zebrafish behaviour, particularly since in most cases infection status is unknown. This highlights the importance of comprehensive monitoring procedures to detect sub-clinical infections in laboratory animals.publishedVersio