2,261 research outputs found

    Mechanisms of NOx formation and control: alternative and petroleum-derived liquid fuels

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    Journal ArticlePetroleum-, coal- and shale-derived liquid fuels were burned in a downfired tunnel furnace to assess the impact of fuel properties on the formation and control of NOx emissions. A nitrogen-free oxidant mixture (Ar, C02 , 02) was used to isolate fuel NOx formation. Under excess air conditions fuel NOx correlated well with total fuel nitrogen content for both the petroleum and alternate fuels. Under staged combustion conditions the influence of fuel nitrogen content was much less pronounced but equally highly correlated except in the case of a coal-derived liquid

    Imaging of canine neoplastic reproductive disorders

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    Diagnostic imaging plays an essential role in the diagnosis and management of reproductive neoplasia in dogs and cats. The initial diagnosis, staging, and planning of surgical and ra-diation treatment and the response to therapy all involve imaging to varying degrees. Routine ra-diographs, ultrasound, nuclear medicine, and cross‐sectional imaging in the form of computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used in canine reproductive disorders. The choice of imaging modality depends on many factors, including the level of referral and the pathological information required. The biological behaviour of the tumour also guides the choice of imaging in cancer staging, and imaging may play an important role in guiding serial tumour biopsy during the course of therapy. The sophistication of imaging modalities is in-creasing exponentially. Each modality has advantages and disadvantages in terms of cost, availa-bility, sensitivity, specificity, and qualities of anatomic versus functional imaging

    Veterinary practitioners’ selection of diagnostic tests for the primary evaluation of colic in the horse

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    The aim of this study was to survey veterinary practitioners’ selection of diagnostic tests for horses with clinical signs of abdominal pain. A questionnaire was distributed to veterinary surgeons involved in the primary evaluation of horses with abdominal pain, including the respondent's demographics, selection of diagnostic tests and factors affecting decision-making. Data analysis included descriptive analysis, categorisation of free text and simple univariable correlations to explore the relationships between independent variables and the relative self-estimated frequency that diagnostic tests were performed. A total of 228 responses were analysed. Participants worked in mixed practice (55.7 per cent), first opinion equine (22.8 per cent), first and second opinion equine (17.9 per cent) and referral practice (3.1 per cent). The majority (48.2 per cent, 105/218) were very confident managing a colic case (confidence level 4/5). The most frequently used diagnostic tests were ‘response to analgesia’ (87.2±24.0 per cent cases), rectal examination (75.9±21.2 per cent) and nasogastric intubation (43.8±27.6 per cent). Approach varied between practitioners, and for all diagnostic tests with frequency of use ranging from 0 to 100 per cent of cases. ‘Risk to personal safety’ was the most common reason for not using rectal examination. Practitioner's opinion of their confidence level in managing a colic case was associated with how frequently they used different diagnostic tests. There was marked variation in practitioners’ approaches, highlighting the need for further evidence to support decision-making

    Ultrasonography of the prostate gland and testes in dogs

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    Ultrasonographic imaging is an important diagnostic tool because it allows assessment of the shape, size, position, margination and internal architecture of organs, as well as facilitating the study of vascular supply and vascularisation. Recently, there has been considerable development of B-mode, Doppler and contrast-enhanced ultrasonography for examination of the reproductive tract of dogs, both for studying normal physiology and in the clinical setting. This article describes the practical examination of the canine prostate gland and testes using a variety of ultrasound techniques, and details the normal appearance and blood flow of these organs as well as changes that may be observed with common reproductive disorders

    Environmental chemicals in dog testes reflect their geographical source and may be associated with altered pathology

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    In humans and dogs, a temporal decline in semen quality and increased incidence of testicular cancer is hypothesised to be associated with exposure to anthropogenic chemicals, particularly during fetal development. Human studies suggest that differential exposures to environmental chemicals may be associated with geographical differences in male reproductive health. Here we investigate testicular chemical profiles and pathologies in dogs residing in the UK [West Midlands (WM), East Midlands (EM), South East (SE)], Denmark (Copenhagen) and Finland (Vantaa). Testes, surplus from routine castrations, contained region specific differences in relative concentrations of diethylhexyl phthalate (DEHP), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB). Relative to UK regions, testes from dogs living in Finland and Denmark had higher concentrations of PBDE and lower concentrations of DEHP and PCBs. Regional differences in the UK in PCB concentrations were also observed. Dog testes from Finland had fewer pathologies, reduced testicular area stained for Sertoli and germ cells and evidence of reduced cellular proliferation. Since the geographical differences in testis pathologies in dogs parallel reports of regional differences in human testicular cancer, we postulate that this may reflect chemical effects within the testis and that this may be related to environmental influences on male reproductive function.Peer reviewe

    Going places

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    Journeys. We all make them. Often they take us to exotic places. Sometimes they take us even further. They might take us through time. Or they might take us into a new way of life. There are times too, when we go all over the world and back again only to find that home is, after all, where it’s all happening. This book contains stories about many different types of journey. We hope you will enjoy travelling into it and finding a world that suits you

    Characterization of the material response in the granular ratcheting

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    The existence of a very special ratcheting regime has recently been reported in a granular packing subjected to cyclic loading \cite{alonso04}. In this state, the system accumulates a small permanent deformation after each cycle. After a short transient regime, the value of this permanent strain accumulation becomes independent on the number of cycles. We show that a characterization of the material response in this peculiar state is possible in terms of three simple macroscopic variables. They are defined that, they can be easily measured both in the experiments and in the simulations. We have carried out a thorough investigation of the micro- and macro-mechanical factors affecting these variables, by means of Molecular Dynamics simulations of a polydisperse disk packing, as a simple model system for granular material. Biaxial test boundary conditions with a periodically cycling load were implemented. The effect on the plastic response of the confining pressure, the deviatoric stress and the number of cycles has been investigated. The stiffness of the contacts and friction has been shown to play an important role in the overall response of the system. Specially elucidating is the influence of the particular hysteretical behavior in the stress-strain space on the accumulation of permanent strain and the energy dissipation.Comment: 13 pages, 20 figures. Submitted to PR

    Enhancing the early student experience

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    This paper is concerned with identifying how the early student experience can be enhanced in order to improve levels of student retention and achievement. The early student experience is the focus of this project as the literature has consistently declared the first year to be the most critical in shaping persistence decisions. Programme managers of courses with high and low retention rates have been interviewed to identify activities that appear to be associated with good retention rates. The results show that there are similarities in the way programmes with high retention are run, with these features not being prevalent on programmes with low retention. Recommendations of activities that appear likely to enhance the early student experience are provided
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