892 research outputs found

    Generalised analysis of compensating balancing sleeves with experimental results from a scaled industrial turbine coupling shaft

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    The paper furthers the analysis of a recently proposed balancing methodology for high-speed, flexible shafts. This mechanism imparts corrective balancing moments, having the effect of\ud simulating the fixing moments of equivalent double or single encastre mounted shafts. This is shown to theoretically eliminate/nullify the 1st lateral critical speed (LCS), and thereby facilitate safe operation with reduced LCS margins. The paper extends previously reported research to encompass a more generalised case of multiple, concentrated, residual imbalances, thereby facilitating analysis of any imbalance distribution along the shaft. Solutions provide greater insight of the behaviour of the balancing sleeve concept, and the beneficial implications for engineering design. Specifically: 1) a series of concentrated imbalances can be regarded as an equivalent level of uniform eccentricity, and balance sleeve compensation is equally applicable to a generalised unbalanced distribution, 2) compensation depends on the sum of the applied balancing sleeve moments and can therefore be achieved using a single balancing sleeve (thereby simulating a single encastre shaft), 3) compensation of the 2nd critical speed, and to a lesser extent higher orders, is possible by use of two balancing sleeves, positioned at shaft ends, 4) the concept facilitates on-site commissioning of trim balance which requires a means of adjustment at only one end of the shaft, 5) the Reaction Ratio, RR, (simply supported/ encastre), is independent of residual eccentricity, so that the implied benefits resulting from the ratio (possible reductions in the equivalent level of eccentricity) are additional to any balancing procedures undertaken prior to encastre simulation. Analysis shows that equivalent reductions in the order of 1/25th, are possible. Experimental measurements from a scaled model of a typical drive coupling employed on an industrial gas turbine package, loaded asymmetrically with a concentrated point of imbalance, are used to support the analysis and conclusions

    The scale of population structure in Arabidopsis thaliana

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    The population structure of an organism reflects its evolutionary history and influences its evolutionary trajectory. It constrains the combination of genetic diversity and reveals patterns of past gene flow. Understanding it is a prerequisite for detecting genomic regions under selection, predicting the effect of population disturbances, or modeling gene flow. This paper examines the detailed global population structure of Arabidopsis thaliana. Using a set of 5,707 plants collected from around the globe and genotyped at 149 SNPs, we show that while A. thaliana as a species self-fertilizes 97% of the time, there is considerable variation among local groups. This level of outcrossing greatly limits observed heterozygosity but is sufficient to generate considerable local haplotypic diversity. We also find that in its native Eurasian range A. thaliana exhibits continuous isolation by distance at every geographic scale without natural breaks corresponding to classical notions of populations. By contrast, in North America, where it exists as an exotic species, A. thaliana exhibits little or no population structure at a continental scale but local isolation by distance that extends hundreds of km. This suggests a pattern for the development of isolation by distance that can establish itself shortly after an organism fills a new habitat range. It also raises questions about the general applicability of many standard population genetics models. Any model based on discrete clusters of interchangeable individuals will be an uneasy fit to organisms like A. thaliana which exhibit continuous isolation by distance on many scales

    Comparison of cytokine and phosphoprotein profiles in idiopathic and Crohn's disease-related perianal fistula.

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    BACKGROUND: Perianal fistulae are either primary (idiopathic) or secondary [commonly associated with Crohn's disease, (CD)]. It is assumed, although not proven, that the pathophysiology differs. AIM: To systematically compare the clinical phenotypes, cytokine and phosphoprotein profiles of idiopathic and CD-related perianal fistulae. METHODS: Sixty-one patients undergoing surgery for perianal fistula were prospectively recruited (48 idiopathic, 13 CD) into a cohort study. Clinical data, including the Perineal Disease Activity Index (PDAI) and EQ-5D-5L were collected. Biopsies of the fistula tract, granulation tissue, internal opening mucosa and rectal mucosa were obtained at surgery. Concentrations of 30 cytokines and 39 phosphoproteins were measured in each biopsy using a magnetic bead multiplexing instrument and a chemiluminescent antibody array respectively. Over 12000 clinical and 23500 laboratory measurements were made. RESULTS: The PDAI was significantly higher (indicating more active disease) in the CD group with a mean difference of 2.40 (95%CI: 0.52-4.28, P = 0.01). Complex pathoanatomy was more prevalent in the CD group, namely more multiple fistulae, supralevator extensions, collections and rectal thickening. The IL-12p70 concentration at the internal opening specimen site was significantly higher (median difference 19.7 pg/mL, 99%CI: 0.2-40.4, P = 0.008) and the IL-1RA/IL-1β ratio was significantly lower in the CD group at the internal opening specimen site (median difference 15.0, 99%CI = 0.4-50.5, P = 0.008). However in the remaining 27 cytokines and all 39 of the phosphoproteins across the four biopsy sites, no significant differences were found between the groups. CONCLUSION: CD-related perianal fistulae are more clinically severe and anatomically complex than idiopathic perianal fistulae. However, overall there are no major differences in cytokine and phosphoprotein profiles

    A secondary RET mutation in the activation loop conferring resistance to vandetanib

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    Resistance to vandetanib, a type I RET kinase inhibitor, developed in a patient with metastatic lung adenocarcinoma harboring a CCDC6-RET fusion that initially exhibited a response to treatment. The resistant tumor acquired a secondary mutation resulting in a serine-to-phenylalanine substitution at codon 904 in the activation loop of the RET kinase domain. The S904F mutation confers resistance to vandetanib by increasing the ATP affinity and autophosphorylation activity of RET kinase. A reduced interaction with the drug is also observed in vitro for the S904F mutant by thermal shift assay. A crystal structure of the S904F mutant reveals a small hydrophobic core around F904 likely to enhance basal kinase activity by stabilizing an active conformer. Our findings indicate that missense mutations in the activation loop of the kinase domain are able to increase kinase activity and confer drug resistance through allosteric effects

    Osteoclasts are multinucleated cells that degrade cartilage as well as bone

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    Osteoclasts are essential for bone remodelling and are normally found at the bone surface where they create resorption pits. Joints are formed where the extremities of bones meet and articulate. Cartilage is composed of chondrocytes and a collagenous extracellular matrix rich in proteoglycan and collagen that lines and lubricates the joint. The bone-cartilage interface comprises the deep layer of non-calcified cartilage, the calcified cartilage and the underlying subchondral bone. Osteoarthritis (OA) is characterized by a degeneration of articular cartilage and the crosstalk between cartilage and subchondral bone plays an important role in the development and progression of OA. Direct biochemical crosstalk or cellular contact between cartilage and bone might modify the cellular environment and influence disease progression. Whether osteoclasts degrade cartilage has been little explored and is a challenging question. We aim to characterise how osteoclasts can affect cartilage degradation

    Strengthening patient-centred communication in rural Ugandan health centres: A theory-driven evaluation within a cluster randomized trial.

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    This article describes a theory-driven evaluation of one component of an intervention to improve the quality of health care at Ugandan public health centres. Patient-centred services have been advocated widely, but such approaches have received little attention in Africa. A cluster randomized trial is evaluating population-level outcomes of an intervention with multiple components, including 'patient-centred services.' A process evaluation was designed within this trial to articulate and evaluate the implementation and programme theories of the intervention. This article evaluates one hypothesized mechanism of change within the programme theory: the impact of the Patient Centred Services component on health-worker communication. The theory-driven approach extended to evaluation of the outcome measures. The study found that the proximal outcome of patient-centred communication was rated 10 percent higher (p < 0.008) by care seekers consulting with the health workers who were at the intervention health centres compared with those at control health centres. This finding will strengthen interpretation of more distal trial outcomes

    Exploring medical student learning in the large group teaching environment: examining current practice to inform curricular development

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    Background Lectures continue to be an efficient and standardised way to deliver information to large groups of students. It has been well documented that students prefer interactive lectures, based on active learning principles, to didactic teaching in the large group setting. Despite this, it is often the case than many students do not engage with active learning tasks and attempts at interaction. By exploring student experiences, expectations and how they use lectures in their learning we will provide recommendations for faculty to support student learning both in the lecture theatre and during personal study time. Methods This research employed a hermeneutic phenomenological approach. Three focus groups, consisting of 19 students in total, were used to explore the experiences of second year medical students in large group teaching sessions. Using generic thematic data analysis, these accounts have been developed into a meaningful account of experience. Results This study found there to be a well-established learning culture amongst students and with it, expectations as to the format of teaching sessions. Furthermore, there were set perceptions about the student role within the learning environment which had many implications, including the way that innovative teaching methods were received. Student learning was perceived to take place outside the lecture theatre, with a large emphasis placed on creating resources that can be taken away to use in personal study time. Conclusions Presented here is a constructive review of reasons for student participation, interaction and engagement in large group teaching sessions. Based on this are recommendations constructed with the view to aid educators in engaging students within this setting. Short term, educators can implement strategies that monopolise on the established learning culture of students to encourage engagement with active learning strategies. Long term, it would be beneficial for educators to consider ways to shift the current student learning culture to one that embraces an active learning curriculum

    Concomitant CIS on TURBT does not impact oncological outcomes in patients treated with neoadjuvant or induction chemotherapy followed by radical cystectomy

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    © Springer-Verlag GmbH Germany, part of Springer Nature 2018Background: Cisplatin-based neoadjuvant chemotherapy (NAC) for muscle invasive bladder cancer improves all-cause and cancer specific survival. We aimed to evaluate whether the detection of carcinoma in situ (CIS) at the time of initial transurethral resection of bladder tumor (TURBT) has an oncological impact on the response to NAC prior to radical cystectomy. Patients and methods: Patients were identified retrospectively from 19 centers who received at least three cycles of NAC or induction chemotherapy for cT2-T4aN0-3M0 urothelial carcinoma of the bladder followed by radical cystectomy between 2000 and 2013. The primary and secondary outcomes were pathological response and overall survival, respectively. Multivariable analysis was performed to determine the independent predictive value of CIS on these outcomes. Results: Of 1213 patients included in the analysis, 21.8% had concomitant CIS. Baseline clinical and pathologic characteristics of the ‘CIS’ versus ‘no-CIS’ groups were similar. The pathological response did not differ between the two arms when response was defined as pT0N0 (17.9% with CIS vs 21.9% without CIS; p = 0.16) which may indicate that patients with CIS may be less sensitive to NAC or ≤ pT1N0 (42.8% with CIS vs 37.8% without CIS; p = 0.15). On Cox regression model for overall survival for the cN0 cohort, the presence of CIS was not associated with survival (HR 0.86 (95% CI 0.63–1.18; p = 0.35). The presence of LVI (HR 1.41, 95% CI 1.01–1.96; p = 0.04), hydronephrosis (HR 1.63, 95% CI 1.23–2.16; p = 0.001) and use of chemotherapy other than ddMVAC (HR 0.57, 95% CI 0.34–0.94; p = 0.03) were associated with shorter overall survival. For the whole cohort, the presence of CIS was also not associated with survival (HR 1.05 (95% CI 0.82–1.35; p = 0.70). Conclusion: In this multicenter, real-world cohort, CIS status at TURBT did not affect pathologic response to neoadjuvant or induction chemotherapy. This study is limited by its retrospective nature as well as variability in chemotherapy regimens and surveillance regimens.Peer reviewedFinal Accepted Versio

    Reconstruction of the Transmission History of RNA Virus Outbreaks Using Full Genome Sequences: Foot-and-Mouth Disease Virus in Bulgaria in 2011

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    <div><p>Improvements to sequencing protocols and the development of computational phylogenetics have opened up opportunities to study the rapid evolution of RNA viruses in real time. In practical terms, these results can be combined with field data in order to reconstruct spatiotemporal scenarios that describe the origin and transmission pathways of viruses during an epidemic. In the case of notifiable diseases, such as foot-and-mouth disease (FMD), these analyses provide important insights into the epidemiology of field outbreaks that can support disease control programmes. This study reconstructs the origin and transmission history of the FMD outbreaks which occurred during 2011 in Burgas Province, Bulgaria, a country that had been previously FMD-free-without-vaccination since 1996. Nineteen full genome sequences (FGS) of FMD virus (FMDV) were generated and analysed, including eight representative viruses from all of the virus-positive outbreaks of the disease in the country and 11 closely-related contemporary viruses from countries in the region where FMD is endemic (Turkey and Israel). All Bulgarian sequences shared a single putative common ancestor which was closely related to the index case identified in wild boar. The closest relative from outside of Bulgaria was a FMDV collected during 2010 in Bursa (Anatolia, Turkey). Within Bulgaria, two discrete genetic clusters were detected that corresponded to two episodes of outbreaks that occurred during January and March-April 2011. The number of nucleotide substitutions that were present between, and within, these separate clusters provided evidence that undetected FMDV infection had occurred. These conclusions are supported by laboratory data that subsequently identified three additional FMDV-infected livestock premises by serosurveillance, as well as a number of antibody positive wild boar on both sides of the border with Turkish Thrace. This study highlights how FGS analysis can be used as an effective on-the-spot tool to support and help direct epidemiological investigations of field outbreaks.</p> </div

    Genetic evidence for a normal-weight "metabolically obese" phenotype linking insulin resistance, hypertension, coronary artery disease, and type 2 diabetes

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    PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThe mechanisms that predispose to hypertension, coronary artery disease (CAD), and type 2 diabetes (T2D) in individuals of normal weight are poorly understood. In contrast, in monogenic primary lipodystrophy-a reduction in subcutaneous adipose tissue-it is clear that it is adipose dysfunction that causes severe insulin resistance (IR), hypertension, CAD, and T2D. We aimed to test the hypothesis that common alleles associated with IR also influence the wider clinical and biochemical profile of monogenic IR. We selected 19 common genetic variants associated with fasting insulin-based measures of IR. We used hierarchical clustering and results from genome-wide association studies of eight nondisease outcomes of monogenic IR to group these variants. We analyzed genetic risk scores against disease outcomes, including 12,171 T2D cases, 40,365 CAD cases, and 69,828 individuals with blood pressure measurements. Hierarchical clustering identified 11 variants associated with a metabolic profile consistent with a common, subtle form of lipodystrophy. A genetic risk score consisting of these 11 IR risk alleles was associated with higher triglycerides (β = 0.018; P = 4 × 10(-29)), lower HDL cholesterol (β = -0.020; P = 7 × 10(-37)), greater hepatic steatosis (β = 0.021; P = 3 × 10(-4)), higher alanine transaminase (β = 0.002; P = 3 × 10(-5)), lower sex-hormone-binding globulin (β = -0.010; P = 9 × 10(-13)), and lower adiponectin (β = -0.015; P = 2 × 10(-26)). The same risk alleles were associated with lower BMI (per-allele β = -0.008; P = 7 × 10(-8)) and increased visceral-to-subcutaneous adipose tissue ratio (β = -0.015; P = 6 × 10(-7)). Individuals carrying ≥17 fasting insulin-raising alleles (5.5% population) were slimmer (0.30 kg/m(2)) but at increased risk of T2D (odds ratio [OR] 1.46; per-allele P = 5 × 10(-13)), CAD (OR 1.12; per-allele P = 1 × 10(-5)), and increased blood pressure (systolic and diastolic blood pressure of 1.21 mmHg [per-allele P = 2 × 10(-5)] and 0.67 mmHg [per-allele P = 2 × 10(-4)], respectively) compared with individuals carrying ≤9 risk alleles (5.5% population). Our results provide genetic evidence for a link between the three diseases of the "metabolic syndrome" and point to reduced subcutaneous adiposity as a central mechanism
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