115 research outputs found

    Achieving Effective Road Safety Initiatives: A New Application of the Stage of Change Model

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    Interviews were conducted with managers and employees from two organizations to explore the utility of the Stages of Change model as a framework for explaining perceived effectiveness of work-related road safety initiatives. Perceptions pertaining to initiative effectiveness were found to vary in relation to the stage of change. This paper suggests how practitioners can apply the stages of change framework to tailor safety initiatives to most effectively meet client needs and improve work-related road safety

    A study of filter-feeding behaviour in Simulium larvae (Diptera: Simuliidae)

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    The structure of the mouthparts and distribution of cephalic sense organs of larval simuliids was investigated using the scanning electron microscope and methylene blue staining. The effect of water velocity, temperature and quality on larval feeding behaviour was studied in an artificial stream. Short, controlled, pulses of physical and chemical stimulants were injected into the water to observe their effect on larval feeding behaviour. Too rapid for the unaided eye, movements were described frame by frame from video recordings. Food is filtered from the water by the open cephalic fans. In alternation the fans are rapidly closed , swept by the mandible to remove food particles and opened again. The frequency of this endogenous behaviour pattern was modified by environmental factors that appeared to act mainly on the interval between fan beats.The interval between fan beats was found to be inversely related to water temperature and velocity and was also affected by water borne stimulants, being significantly shorter in unfiltered natural water than particle-free distilled water. Consequently fan cleaning frequency rose as water velocity and temperature were increased and when natural food was available. Larvae responded to pulses of a wide variety of chemical compounds with bursts of mandible and maxilla movements. Fan cleaning was inhibited when these mouthpart movements occurred but filtering continued. Short pulses of inert particles at a relatively high concentration caused a similar response but when a series of pulses was delivered bursts of mouthpart movements lengthened and the fans were often closed for longer than normal, inhibiting filtering. It is suggested that overstimulation of peripheral sense organs, responding to the physical and chemical qualities of food particles, initiates the inhibition of filtering.The temporary inhibition of feeding may regulate the rate of ingestion. A simple model of larval behaviour is proposed, recognising "food gathering" (filtering) and "food ingestion" (mouthpart movements) as its main components.<p

    History, origins and importance of temporary ponds

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    In Europe, temporary ponds are a naturally common and widespread habitat occurring, often in abundance, in all biogeographical regions from the boreal snow-melt pools of northern Scandinavia to the seasonally inundated coastal dune pools of southern Spain. Ecological studies in Europe and elsewhere also emphasise that temporary ponds are a biologically important habitat type, renowned both for their specialised assemblages and the considerable numbers of rare and endemic species they support. They are, however, a habitat currently under considerable threat. Most temporary ponds are inherently shallow and the majority are destroyed even by limited soil drainage for agriculture or urban development. The paper gives an overview of definitions of temporary ponds and examines their formation and abundance. The authors also summarise a visit to the Bialowieza Forest in Poland to investigate the occurrence of temporary ponds

    Dangers and opportunities in managing temporary ponds

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    Although there is a growing awareness of the value of temporary ponds in Europe, there is still remarkably little information available to help guide their conservation and management. General principles which can be used to guide the management of temporary ponds as a whole have yet to be established. The aim of this article, therefore, is to give a broader overview of the main principles of temporary pond conservation, particularly by building on a number of general principles for managing ponds previously described by Biggs et al. (1994) and Williams et al. The authors emphasise the importance of surveys in order to get data on which to base management strategies. The main principles of temporary pond management are described, and examples of three case studies of ponds in England are given

    Pond action: Promoting the conservation of ponds in Britain

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    Pond Action is an independent freshwater conservation project which was started in 1987. It is based in the School of Biological and Molecular Sciences in Oxford Polytechnic and has five full-time staff with two senior advisors. The main aim of Pond Action's work has been to promote the conservation of ponds by creating a sound, scientific basis for pond conservation. An essential aspect of this work is the need to make the results of scientific work available and understandable to everybody concerned with pond conservation

    The size-distribution of earth’s lakes and ponds: Limits to power-law behavior

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    Global-scale characterizations of Earth’s lakes and ponds assume their surface areas are power-law distributed across the full size range. However, empirical power-laws only hold across finite ranges of scales. In this paper, we synthesize evidence for upper and lower limits to power-law behavior in lake and pond size-distributions. We find support for the power-law assumption in general. We also find strong evidence for a lower limit to this power-law behavior, although the specific value for this limit is highly variable (0.001–1 km2), corresponding to orders of magnitude differences of the total number of lakes and ponds. The exact mechanisms that break the power-law at this limit are unknown. The power-law extends to the size of Earth’s largest lake. There is inconsistent evidence for an upper limit at regional-scales. Explaining variations in these limits stands to improve the accuracy of global lake characterizations and shed light on the specific mechanism responsible for forming and breaking lake power-law distributions

    Pump Pulse Bandwidth-Activated Nonlinear Phononic Coupling in CdWO4_4

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    To control structure-function relationships in solids with light, we must harness the shape of the potential energy surface, as expressed in anharmonic coupling coefficients. We use two-dimensional terahertz (THz) spectroscopy to identify trilinear coupling between sets of vibrational modes in CdWO4_4. It is generally understood that efficient trilinear coupling occurs when the frequencies of two coupled modes add or subtract to the frequency of the third mode. Interestingly, we observe that this condition is not necessary: the THz driving-pulse itself can activate the coupling by contributing broad frequency content to the initial motion of the excited modes. Understanding that the bandwidth of the driving force can activate energy-flow pathways has broad implications for coherent control of collective modes using intense THz light pulses.Comment: 27 Pages, 15 Figure

    Pond Action: Promoting the conservation of ponds in Britain

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    Pond Action is an independent freshwater conservation project whichwas started in 1987 by Anne Powell, Roger Sweeting and Jeremy Biggs.It is based in the School of Biological and Molecular Sciences in OxfordPolytechnic and has five full-time staff with two senior advisors.The main aim of Pond Action's work has been to promote theconservation of ponds by creating a sound, scientific basis for pondconservation. An essential aspect of this work is the need to make theresults of scientific work available and understandable to everybodyconcerned with pond conservation
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