18,267 research outputs found

    An investigation of the grindability of two torrefied energy crops

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    The process of torrefaction alters the physical properties of biomass, reducing its fibrous tenacious nature. This could allow increased rates of co-milling and therefore co-firing in coal fired power stations, which in turn would enable a reduction in the amount of coal used and an increase in the use of sustainable fuels, without the need for additional plant. This paper presents an experimental investigation of the pulverisation behaviour of two torrefied energy crops, namely: willow and Miscanthus. A multifactorial method approach was adopted to investigate the three process parameters of temperature, residence time and particle size, producing fuels treated using four different torrefaction conditions. The untreated and torrefied fuels were subjected to standard fuel analysis techniques including ultimate analysis, proximate analysis and calorific value determination. The grindability of these fuels was then determined using a laboratory ball mill and by adapting the Hardgrove Grindability Index (HGI) test for hard coals. After grinding, two sets of results were obtained. Firstly a determination similar to the HGI test was made, measuring the proportion of sample passing through a 75 mu m sieve and plotting this on a calibrated HGI chart determined using four standard reference coals of known HGI values. Secondly the particle size distributions of the entire ground sample were measured and compared with the four standard reference coals. The standard fuel tests revealed that temperature was the most significant parameter in terms of mass loss, changes in elemental composition and energy content increase. The first grindability test results found that the untreated fuels and fuels treated at low temperatures showed very poor grindability behaviour. However, more severe torrefaction conditions caused the fuels to exhibit similar pulverisation properties as coals with low HGI values. Miscanthus was found to have a higher HGI value than willow. On examining the particle size distributions it was found that the particle size distributions of torrefied Miscanthus differed significantly from the untreated biomass and had comparable profiles to those of the standard reference coals with which they had similar HGI values. However, only the torrefied willow produced at the most severe conditions investigated exhibited this behaviour, and the HGI of torrefied willow was not generally a reliable indicator of grindability performance for this energy crop. Overall it was concluded that torrefied biomass can be successfully pulverised and that torrefied Miscanthus was easier to grind than torrefied willow

    The response of a floating ice sheet to an accelerating line load

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    The two-dimensional response of a thin, floating sheet of ice to a line load that accelerates from rest at t=0t = 0 to a uniform velocity V for tā‰„Tt \geq T is determined through an integral-transform solution of the linearized equations of motion. If T=0T = 0 ā€“ i.e. if the load is impulsively started with velocity V ā€“ the solution exhibits singularities at V=c0V = c_0, the shallow-water-gravity-wave speed, and V=cminā”V = c_{\min}, the minimum speed for transverse motion of the ice, but these singularities are avoided by the acceleration of the load through the critical speeds

    Impact of pain and postoperative complications on patient-reported outcome measures 5Ā years after microvascular decompression or partial sensory rhizotomy for trigeminal neuralgia

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    BACKGROUND: Microvascular decompression (MVD) and partial sensory rhizotomy (PSR) provide longstanding pain relief in trigeminal neuralgia (TN). Given their invasiveness, complications can result from such posterior fossa procedures, but the impact of these procedures and their complications on patient-reported outcome measures (PROM), such as quality of life and distress, are not well established. METHOD: Five years after surgery, patients who underwent first MVD or PSR for TN at one institution, between 1982 and 2002, were sent a self-completion assessment set containing a range of PROMs: the Short Form-12 (SF-12) questionnaire to assess quality of life, the Hospital Anxiety and Depression Scale (HADS) to assess distress, and a questionnaire containing questions about postoperative complications, their severity and impact on quality of life. These findings and demographic data were compared between MVD and PSR. RESULTS: One hundred and eighty-one of 245 (73.9%) patients after first MVD and 49 of 60 (81.7%) after PSR responded, and were included in analyses. The mean SF-12 scores of patients after MVD and PSR at five-year follow-up were significantly lower than English age-matched norms. Though there were no differences in SF-12 physical or mental component scores between the two procedures, patients after PSR were more likely to have case-level anxiety (RRĀ =Ā 3.3; 95% CI, 1.1-10.5; pĀ =Ā 0.03), had more postoperative complications, and of greater severity, including pain (RRĀ =Ā 2.52; 95% CI, 1.5-4.1; pĀ <Ā 0.001), numbness (RRĀ =Ā 5.9; 95% CI, 3.8-9.2; pĀ <Ā 0.001), burning sensations (RRĀ =Ā 3.0; 95% CI, 1.5-5.8; pĀ =Ā 0.001) and difficulty in eating (RRĀ =Ā 17.1; 95% CI, 5.6-53.1; pĀ <Ā 0.001), and these had a larger impact on quality of life for PSR compared to MVD. CONCLUSIONS: The quality of life 5Ā years after MVD or PSR is poorer than in the general population and associated with postoperative complications such as pain, numbness, burning sensation and difficulty in eating. These complications are commoner after PSR than MVD, and this is associated with anxiety in PSR patients at five-year follow-up. However, these differences are not reflected by quality of life scores. Outcome measures need to incorporate patient experience after treatment for TN, and represent patient priorities for quality of life

    Delivery of small-for-gestational-age neonate and association with early-onset impaired maternal endothelial function

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    Objective Women who have delivered a small-for-gestational-age (SGA) infant are at an increased risk of developing cardiovascular disease (CVD) in later life. Endothelial dysfunction is a subclinical sign of early CVD. It is unknown whether women who have recently had a pregnancy complicated by SGA, in the absence of other maternal and fetal diseases, have subclinical endothelial dysfunction. Our aim was to assess maternal endothelial function 6 months after a pregnancy complicated by SGA. Methods This was a caseā€“control study conducted in a tertiary referral hospital in London, UK, over a 15-month period. Flow-mediated dilatation (FMD) of the brachial artery was measured in women 6.9 Ā± 2.5 months after childbirth. Forty-four women were included in the study, of whom 15 had a SGA neonate (mean Ā± SD customized birth centile of 1.9 Ā± 2.3) and 29 delivered an appropriately grown baby (mean Ā± SD customized birth centile of 47.5 Ā± 26.3). The primary continuous variable, FMD, was assessed in each group and compared using unpaired t-test. Results Women who had a SGA neonate had lower postpartum FMD (6.79 Ā± 0.95%) than did those who had an appropriately grown offspring (10.26 Ā± 2.44% (95% CI for difference between groups, āˆ’5.37 to āˆ’1.57); P = 0.0007). There were no differences in postnatal maternal blood pressure, abdominal circumference, weight and glucose, insulin and lipid profiles between the two groups. Conclusions Women who had a pregnancy affected by SGA, probably due to placental failure in the absence of pre-eclampsia, have evidence of subclinical endothelial dysfunction within 6 months of childbirth. These women may benefit from lifestyle measures focused on the primary prevention of CVD. Further research in larger populations is needed to ascertain if such postpartum maternal endothelial dysfunction is a pregnancy-induced phenomenon or if it is related to the pre-existing maternal phenotype, and whether it persists long term

    Encoding of low-quality DNA profiles as genotype probability matrices for improved profile comparisons, relatedness evaluation and database searches

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    Many DNA profiles recovered from crime scene samples are of a quality that does not allow them to be searched against, nor entered into, databases. We propose a method for the comparison of profiles arising from two DNA samples, one or both of which can have multiple donors and be affected by low DNA template or degraded DNA. We compute likelihood ratios to evaluate the hypothesis that the two samples have a common DNA donor, and hypotheses specifying the relatedness of two donors. Our method uses a probability distribution for the genotype of the donor of interest in each sample. This distribution can be obtained from a statistical model, or we can exploit the ability of trained human experts to assess genotype probabilities, thus extracting much information that would be discarded by standard interpretation rules. Our method is compatible with established methods in simple settings, but is more widely applicable and can make better use of information than many current methods for the analysis of mixed-source, low-template DNA profiles. It can accommodate uncertainty arising from relatedness instead of or in addition to uncertainty arising from noisy genotyping. We describe a computer program GPMDNA, available under an open source license, to calculate LRs using the method presented in this paper

    An exploratory qualitative study of health professional perspectives on clinical outcomes in UK orthotic practice

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    Background: Despite potential savings to the National Health Service, the collection of data on outcomes of NHS orthotic services is patchy. Indeed, several reports into orthotic services in the UK have reported a lack of data relating to outcomes of care and highlighted the need to routinely measure outcomes to demonstrate efficacy of services. Whilst a previous study provided an overview of the use of outcome measures in orthotic practice and identified some barriers to their use, further questions emerged. Hence, this qualitative study aimed to explore orthotistsā€™ opinions and personal experiences on the influences on outcomes, how appropriate and relevant outcomes can be measured and also how barriers to the use of outcome measures can be overcome. Methods: Following a review of the literature, an initial advisory group informed semi-structured questions. These were used to create dialogue in a focus group of 12 orthotists. Data from the focus group was transcribed verbatim and analysed using thematic analysis, creating themes and subthemes for discussion. Results: The setting of realistic and agreed goals through managing expectations, compromise and patient education/information were seen as factors that could inform and improve outcomes. Barriers to the collection of outcome measures were associated with inadequate technology to manage the data, lack of time to complete them, lack of training in them and difficulties selecting appropriate outcome measures for patients with complex problems managed by different health professionals. The participants discussed ways of addressing these barriers, such as the use of ā€˜snapshotsā€™ and delegation of data collection. Conclusions: This study has revealed that measuring outcomes is considered to be an important activity. In order to achieve good outcomes, it is important to address patient expectations, discuss and establish joint goals for care at the outset and inform and include patients in the decision-making process. The identified barriers to measuring outcomes can be overcome with the solutions revealed by these participants. Hence, this study has contributed to current knowledge which has relevance for clinical practice and may provide the theoretical basis for future research

    Electroencephalogram of Healthy Horses During Inhaled Anesthesia.

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    BackgroundPrevious study of the diagnostic validity of electroencephalography (EEG) to detect abnormalities in equine cerebral cortical function relied on the administration of various drugs for sedation, induction, and maintenance of general anesthesia but used identical criteria to interpret recordings.ObjectivesTo determine the effects of 2 inhalation anesthetics on the EEG of healthy horses.AnimalsSix healthy horses.MethodsProspective study. After the sole administration of one of either isoflurane or halothane at 1.2, 1.4, and 1.6 times the minimum alveolar concentration, EEG was recorded during controlled ventilation, spontaneous ventilation, and nerve stimulation.ResultsBurst suppression was observed with isoflurane, along with EEG events that resembled epileptiform discharges. Halothane results were variable between horses, with epileptiform-like discharges and bursts of theta, alpha, and beta recorded intermittently. One horse died and 2 were euthanized as the result of anesthesia-related complications.Conclusions and clinical importanceThe results of this study indicate that the effects of halothane and isoflurane on EEG activity in the normal horse can be quite variable, even when used in the absence of other drugs. It is recommended that equine EEG be performed without the use of these inhalation anesthetics and that general anesthesia be induced and maintained by other contemporary means

    Qualitative and Quantitative Characteristics of the Electroencephalogram in Normal Horses during Administration of Inhaled Anesthesia.

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    BackgroundThe effects of anesthesia on the equine electroencephalogram (EEG) after administration of various drugs for sedation, induction, and maintenance are known, but not that the effect of inhaled anesthetics alone for EEG recording.ObjectiveTo determine the effects of isoflurane and halothane, administered as single agents at multiple levels, on the EEG and quantitative EEG (qEEG) of normal horses.AnimalsSix healthy horses.MethodsProspective study. Digital EEG with video and quantitative EEG (qEEG) were recorded after the administration of one of the 2 anesthetics, isoflurane or halothane, at 3 alveolar doses (1.2, 1.4 and 1.6 MAC). Segments of EEG during controlled ventilation (CV), spontaneous ventilation (SV), and with peroneal nerve stimulation (ST) at each MAC multiple for each anesthetic were selected, analyzed, and compared. Multiple non-EEG measurements were also recorded.ResultsSpecific raw EEG findings were indicative of changes in the depth of anesthesia. However, there was considerable variability in EEG between horses at identical MAC multiples/conditions and within individual horses over segments of a given epoch. Statistical significance for qEEG variables differed between anesthetics with bispectral index (BIS) CV MAC and 95% spectral edge frequency (SEF95) SV MAC differences in isoflurane only and median frequency (MED) differences in SV MAC with halothane only.Conclusions and clinical importanceUnprocessed EEG features (background and transients) appear to be beneficial for monitoring the depth of a particular anesthetic, but offer little advantage over the use of changes in mean arterial pressure for this purpose
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