131,717 research outputs found

    Central area redd project [Ribble, Hodder and Lune catchments]

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    Redd counting is an integral part of most Fishery Officers duties. The number and distribution of salmonid redds throughout salmonid catchments provides invaluable information on the range and extent of spawning by both salmon and sea trout. A project was initiated by the Fisheries Science and Management Team of Central Area, North West Region in England in liaison with the Flood Defence function. The main objective of this project was to assess redd count data for Central Area and attempt to quantify these data in order to produce a grading system that would highlight key salmonid spawning areas. By showing which were the main areas for salmon and sea trout spawning, better informed decisions could be made on whether or not in-stream Flood Defence works should be given the go-ahead. The main salmonid catchments in Central Area were broken into individual reaches, approximately 1 km in length. The number of redds in these individual reaches were then calculated and a density per lkm value was obtained for each reach. A grading system was devised which involved looking at the range of density per km values and dividing this by five to produce 5 classes, A - E. A sixth class (F) was used where the density per Ion value was 0.00. This grading system was calculated at two levels of detail. Grades for salmon and sea trout were produced for each individual catchment and also on an Area-wide level. Maps were produced using a range of colours to represent the grade for each reach. These maps provide a highly useful overview of the status of salmonid spawning for each catchment over individual years and highlight the key salmon and sea trout spawning areas in each catchment. These maps and the associated summary data should now provide Flood Defence and Fisheries staff with a fairly detailed overview of the status of spawning in any location within the. main salmonid catchments in Central Area. Although these maps are very useful they should only be used as a guide. The current practice of consulting with the local Fishery Officer should be continued to ensure that expert local knowledge is taken into account

    Les Pygmées Batwa du Rwanda: un peuple ignoré du Rwanda / The Twa Pygmies: Rwanda's ignored people

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    Forest People or Village People: Whose voice will be heard?'

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    With reference to the current situation of the Mbendjele Yaka in northern Congo (Brazzaville) this paper summarises some of the problems facing them as outside interest in their forest increases. Issues relating to traditional and modern land ownership, international forest exploitation by both commercial loggers and wildlife protectionists, and representation are raised in the Mbendjele context. Mbendjele conceptualisations of themselves as ‘forest people’, as opposed to ‘village people’, are considered from the point of view of the contemporary indigenous peoples and minority rights movements. This offers an interesting analysis that highlights some of the challenges to be overcome in coming years. In effect, ‘forest people’ are currently marginalized from these processes by the ‘village people’ character of international procedural forms and structures within which they are expected to represent themselves

    Wheel/Rail Contact Isolation Due to Track Contamination

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    An experimental study has been carried out to investigate the effect of sanding on the electrical isolation of a wheel/rail contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit. Sand in the wheel/rail interface means that contact between the wheelsets and the track may be compromised, inhibiting train identification. Static tests were performed using sections cut from wheels and rail and dynamic tests on a twin disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the amount of sand applied, below which there is a measurable, but not severe, change in voltage, but above which the contact conductance decreases by an order of magnitude. A model of electrical isolation has been developed assuming either full disc separation by a sand layer or partial disc contact with some sand present. Idealisations inherent in both test methods mean that they represent a severe case. Given these limitations, it is likely that the test methods, at their present stage of development, should be used as a means to qualitatively assess the relative effects on electrical isolation of different contaminants

    Head imaging and craniometry: A historical note on a base line error

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    This is the author's PDF version of an article published in Radiography today© 1995. Figure 1 and figure 2 are not available.This journal article discusses the work of Lysholm, Reid, and von Ihering in standarding patient positioning during radiological examination of the skull

    The use of radiography in osteological measurement

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    This is the author's PDF version of an book chapter published in Current and Recent Research in Osteoarchaeology 2 ©1999. The paper was originally delivered at the sixth meeting of the Osteoarchaeological Research Group at the Institute of Archaeology, University of Durham on 7 June 1997.Radiographs provide a means of obtaining permanent images of objects. These images may be readily and repeatedly copied, disseminated or used in a variety of ways without the need further to disturb the original material. Although measurements are frequently taken from such images for metrical analysis, it must be remembered that these images are only representations of the original object. To obtain accurate data, one must be aware of the sources of error inherent in the image-forming process so that radiographs can be used in the appropriate way. This paper outlines the factors involved in the production of radiographic images and applies this to the generation of accurate metrical data

    Some research possibilities in diagnostic radiography

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    This is tha author's PDF version of an article published in Radiography© 1998. The definitive version is available at www.elsevierhealth.comAlthough scientific method is usually viewed as starting with hypotheses which must then be exposed to experimental test, there are situations where this rigid scenario is inappropriate. Fortunately, the alternatives provide avenues for valuable investigative work in radiographic research. Research questions may be addressed by collecting data from existing sources in a way that not only provides fundamental information about human biology, but may improve the efficacy of radiographic practice while avoiding ethical problems about the use of patients. Among those involved in osteology, it is radiographers who see and store the most bone images. Subsequently, they have access to more osteological information than anyone else. All that remains is for this information to be extracted and put into a more accessible form. Since they are closely involved with the patients from whom their radiographs stem, there are research questions which radiographers are uniquely situated to raise.Supported by a University of Liverpool research development gran

    The osteological use of diagnostic radiographs: Further material for osteoarchaeologists

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    This article discusses the use of radiography in osteoarchaeology
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