1,030 research outputs found

    Gingival and Periodontal Conditions As Related to Menstruation and Endocrine Disorders in the Female

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    An introductory note is followed by a short discourse on the history of periodontal disease, with particular emphasis on the conditions which are discussed in the treatise. The normal clinical and microscopical features of the gingiva and periodontal membrane are summarised and illustrated. A summary of the mechanism of the menstrual cycle is given, this being followed by a classification and summary of the aetiological factors of periodontal disease. The results of the research are given. These are based on the observations noted during the examination and treatment of 250 female patients for periodontal disease. Also taken into account are the microscopical findings of the examination of gingival tissue removed from these patients at various stages in their menstrual cycles. The results of observations were noted after the examination and treatment of nineteen cases of known endocrine disorders. A discussion is included. This part of the thesis is presented in two main sections. The first section deals with the gingival changes which occur during the normal menstrual cycle, and also the gingival changes which take place in endocrine disorders which may influence the ovarian cycle. The changes which occur in the basal cell layer of the gingival epithelium are illustrated and discussed as are the changes which take place in the cornified surface layer of the gingival epithelium. A similar account is given of the blood vessel changes which take place in the gingival connective tissue during the menstrual cycle. It is shown that these changes are similar to the changes which take place in the endometrium and the epithelium of the vagina. Periodontal disease in cases of known endocrine imbalance is discussed and illustrated, and it is recorded that recurrence of periodontal disease in many of these cases is associated with recurrence of the endocrine imbalance reflected in the ovarian cycle. The rate of healing and discomfort following gingivectomy is discussed, and it is shown that rapid healing and little post-operative discomfort can be expected in the proliferative phase, but slow healing and much discomfort follow gingivectomy in the progestational phase of the cycle. Oral ulceration of a cyclical nature is shown to be associated with irritation of the mucosa in the progestational phase of the cycle, while oral ulceration of a more acute nature, apparently associated with emotional stress is discussed. Desquamative gingivitis at the menopause is considered. The second section of the discussion is devoted to the treatment of periodontal disease during the normal menstrual cycle, during pregnancy, at the menopause, and in disorders of the endocrine system. It is stated that, when the complete co-operation of the patient is obtained, periodontal treatment is successful even when the cyclical gingival changes are very obvious. Periodontal treatment in pregnancy is best performed after the second month and before the end of the sixth month of pregnancy since healing is rapid and discomfort minimal during this period of four months. It is considered that periodontal treatment in cases of desquamative gingivitis can be successful when the patient co-operates and all sources of irritation are removed, and the epithelium stimulated to activity with oestrogen. In cases of medically controlled endocrine disorders, periodontal treatment is possible. A summary of the case histories of 100 patients has been included as an appendix. A bibliography appears at the end of each chapter of the treatise

    Final shuttle-derived atmospheric database: Development and results from thirty-two flights

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    The final Shuttle-derived atmospheric data base is presented. The relational data base is comprised of data from 32 Space Transportation System (STS) descent flights, to include available meteorology data taken in support of each flight. For the most part, the available data are restricted to the middle atmosphere. In situ accelerations, sensed by the tri-redundant Inertial Measurement Unit (IMU) to an accuracy better than 1 mg, are combined with post-flight Best Estimate Trajectory (BET) information and predicted, flight-substantiated Orbiter aerodynamics to provide determinations up to altitudes of 95 km. In some instances, alternate accelerometry data with micro-g resolution were utilized to extend the data base well into the thermosphere. Though somewhat limited, the ensemble of flights permit a reasonable sampling of monthly, seasonal, and latitudinal variations which can be utilized for atmospheric science investigations and model evaluations and upgrades as appropriate. More significantly, the unparallel vertical resolution in the Shuttle-derived results indicate density shears normally associated with internal gravity waves or local atmospheric instabilities. Consequently, these atmospheres can also be used as stress-atmospheres for Guidance, Navigation and Control (GN and C) system development and analysis as part of any advanced space vehicle design activities

    Cross-hole seismic reflection surveying in coal measures

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    This thesis is concerned with the development of the cross-hole seismic reflection surveying method with particular application to the shallow Coal Measures strata found in opencast coal mining prospects in the U.K.A field acquisition technique developed for shallow boreholes utilising explosive sources and hydrophone receivers is described. Data have been acquired from several test sites in northern England. Data-processing techniques including wavefield separation and waveshaping deconvolution have been developed for cross-hole data and the theories behind these techniques are discussed. Methods of imaging cross-hole reflection data including the 'VSP-CDF transformation and Generalised Kirchhoff migration are applied to computer- generated synthetic data and to real data in order to yield a depth section of the seismic reflectivity between the boreholes. Finally, the data-processing and imaging techniques developed are applied to real data acquired at British Coal Opencast exploration sites in northern England between 1987 and 1990

    Plato\u27s Unwritten Dialectic of the One and the Great and Small

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    In this essay Findlay summarizes his position that the Unwritten Doctrines of Plato, as outlined by Proclus, are essential for understanding the ontological theories of Plato\u27s major dialogues. A. Preu

    Geochemistry of suspended particles in the Tamar estuary

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    ICP analyses of total rare earth element (REE) abundances in intertidal sediments and suspended particles from the Tamar Estuary show little variation in REE concentrations along the estuary and only minor fractionation relative to standard shale. Fe, Mn, Cu, Zn, Ni & Co abundances in the estuarine suspended particles show significant variations in the turbid upper estuary. Acid leachable REE display different shale normalised patterns with slight enrichment of the mid to heavy REE. Sediment porewater analyses confirm the diagenetic mobility of the REE and show significant heavy REE enrichment consistent with their derivation from a non-detrital source. Detailed studies of suspended particles in the turbidity maximum zone reveal the importance of physical processes in the immediate local control of the bulk chemical composition of the suspended particles. Settling experiments performed on particle samples from the turbidity maximum show clear distinctions between populations of particles which are tidally resuspended versus those which remain permanently in suspension. Trace metal-Al ratios and shale normalised REE patterns in the two fractions are consistent with greater non-detrital content in the permanently suspended particles. Modelling of mixing between detrital REE and the riverine REE removed from solution in the low salinity zone indicates that a significant proportion of the leachable particulate REE may be derived from a non-detrital source. Budget calculations using annual fluxes of dissolved REE, Fe, Cu, Ni & Zn and riverine sediment supply confirm that significant modification of particle composition due to uptake of non-detrital metals is likely, but indicate that not all the sediment supplied to the estuary may participate in the chemical scavenging processes

    Shuttle derived atmosphere

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    The shuttle descends along a rather shallow path, thus providing some information on the horizontal structure of the atmosphere. Small scale structures were suggested (shears, potholes). The best estimates of the shuttle drag coefficient and projected areas are used to go from accelerometer data to density through the use of BET's (Best Estimated Trajectories). Data are from the IMU's (Inertial Measurement Unit) and the HiRAP (High Resolution Accelerometer Package)

    Central and peripheral insulin resistance in a large animal model of obesity

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    Non peer reviewedPublisher PD

    Models for organophosphorus pesticide metabolism

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    Impacts of signal crayfish on stream fishes

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    Invasive species cause biodiversity and economic loss globally. Invasive crayfish have a wide range of effects as a result of their high densities and biomass, feeding at multiple trophic levels, aggressive competition for shelter and ecosystem engineering. In Britain, the invasive signal crayfish Pacifastacus leniusculus has displaced the native white-clawed crayfish Austropotamobius pallipes from much of its former range and occupied previously crayfishfree habitats. Signal crayfish could affect fish populations by preying upon eggs, juvenile and adult fish and competing for food and shelter. This thesis assesses the extent to which signal crayfish can affect densities of the commercially important brown trout Salmo trutta, and a species of benthic fish of conservation concern, the European bullhead Cottus gobio, in upland streams. This thesis also investigates the extent to which signal crayfish predation could affect salmonid egg survival through a combination of controlled field and laboratory experiments. Electric fishing was used to estimate fish densities from tributaries of the upper River Tees, north east England. Model selection was then used to determine which factors most affected bullhead and 0+ (less than one year old) brown trout densities. Signal crayfish density was negatively related to both bullhead density and the density of 0+ brown trout. Substrate composition and flow variables and were also selected as predictors of 0+ brown trout and bullhead densities. Small (10-16.2 mm carapace length (CL)) crayfish and fine material apparently reduced buried sea trout S. trutta egg survival in controlled field experiments. However, in laboratory studies, only larger crayfish were found to significantly reduce the survival of salmon S. salar eggs, and this reduction only affected eggs on the surface of the gravel and not buried eggs. These results suggest that signal crayfish pose a threat to both salmonid and bullhead populations, and that, where possible, the sites chosen for reintroduction or habitat enhancement for salmonids and sculpins should be free of invasive crayfish. Evidence for signal crayfish predation upon buried salmonid eggs remains equivocal, although this study provides definite evidence that large signal crayfish will prey upon exposed Atlantic salmon eggs. Both egg predation, and other mechanisms by which signal crayfish may affect salmonid and bullhead populations, are worthy of further investigation. Structural equation models should be used to further investigate relationships between the densities of a range of fish and crayfish species
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