103 research outputs found

    NON-FREE VORTEX FLOW EFFECTS IN AN AXIAL FLOW ROTOR

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    This paper presents the analysis of three-dimensional flow field developing through an industrial axial flow fan rotor of non-free vortex design carried out on the basis of concerted experimental and numerical investigations. The paper focuses on non-free vortex flow effects requiring consideration in rotor blade design theories. The distortion of stream surfaces through the blading has been observed and a quantitative analysis of its effects on the blade loading condition has been carried out in the through-flow core region. The streamlines close to the blades have been modelled fitting to outward and inward conical stream tubes on the blade suction and pressure sides, respectively - termed `cone couple model´. It has been pointed out that the blade lift can be satisfactorily described at midspan on the basis of the cone couple model, with use of pitch-averaged flow data. The loading aspects of the tested axial rotor have been discussed on the basis of both the pressure distribution in the vicinity of the blades and pitch-averaged flow data obtained upstream and downstream of the rotor. Sample calculations suggested that separate optimisation of the blade suction and pressure sides is essential if the three-dimensional blade-to-blade flow is intended to be considered in NFV fan design with use of two-dimensional cascade data

    The Subjective Nature Of Programming Complexity

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    One of the more difficult problems confronting software engineers today is the construction of accurate predictive models of the software development process, [21,[8] and [93. It has long been recognized that one of the most essential elements of any successful model of this process is a quantification of the complexity of software systems. During the past several years a great deal of work has been performed by researchers such as Halstead [3], McCab [5], and others in an attempt to develop metrics which adequately capture the complexity of software systems. Yet one very important aspect of software development complexity seems to have been overlooked in the rush to develop software complexity metrics, q.e. it\u27s psychological nature

    Effective local connectivity properties

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    We investigate, and prove equivalent, effective versions of local connectivity and uniformly local arcwise connectivity for connected and computably compact subspaces of Euclidean space. We also prove that Euclidean continua that are computably compact and effectively locally connected are computably arcwise connected.Comment: Final versio

    European registry on the management of helicobacter pylori infection (HP-EUREG protocol): The first results of Russian centers

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    Aim: To assess the clinical practice of diagnosis and treatment in patients with Helicobacter pylori infection and to compare this practice with the international guidelines in the European Registry on the management of Helicobacter pylori infection, Hp-EuReg protocol), a multicenter prospective observational study initiated by the European Helicobacter and Microbiota Study Group. Materials and methods: The data of 813 patients infected with H. pylori and entered in the Hp-EuReg register by the Russian centers in 2013-2015 were analyzed. Results: The most common methods for the primary diagnosis of H. pylori infection are histology (40.3%), rapid urease test (35.7%), and serology (17.2%). The duration of H. pylori eradication therapy was 7, 10, and 14 days in 18.0, 49.3, and 25.1%, respectively. To monitor the effectiveness of treatment, the investigators used a histological examination (34%), a urea breath test (27.3%), H. pylori stool antigen (22.8%), and a rapid urease test (16.3%). A serological test was carried out in 2.5% of the cases. No monitoring was done in 13.5% of the patients. The average eradication efficiency was 82.6%. If the therapy was ineffective, 80% of physicians did not intend to prescribe a new cycle of treatment. Conclusion: Significant differences were found between clinical practice and the current guidelines

    Anti-tumour necrosis factor discontinuation in inflammatory bowel disease patients in remission: study protocol of a prospective, multicentre, randomized clinical trial

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    Background: Patients with inflammatory bowel disease who achieve remission with anti-tumour necrosis factor (anti-TNF) drugs may have treatment withdrawn due to safety concerns and cost considerations, but there is a lack of prospective, controlled data investigating this strategy. The primary study aim is to compare the rates of clinical remission at 1?year in patients who discontinue anti-TNF treatment versus those who continue treatment. Methods: This is an ongoing, prospective, double-blind, multicentre, randomized, placebo-controlled study in patients with Crohn?s disease or ulcerative colitis who have achieved clinical remission for ?6?months with an anti-TNF treatment and an immunosuppressant. Patients are being randomized 1:1 to discontinue anti-TNF therapy or continue therapy. Randomization stratifies patients by the type of inflammatory bowel disease and drug (infliximab versus adalimumab) at study inclusion. The primary endpoint of the study is sustained clinical remission at 1?year. Other endpoints include endoscopic and radiological activity, patient-reported outcomes (quality of life, work productivity), safety and predictive factors for relapse. The required sample size is 194 patients. In addition to the main analysis (discontinuation versus continuation), subanalyses will include stratification by type of inflammatory bowel disease, phenotype and previous treatment. Biological samples will be obtained to identify factors predictive of relapse after treatment withdrawal. Results: Enrolment began in 2016, and the study is expected to end in 2020. Conclusions: This study will contribute prospective, controlled data on outcomes and predictors of relapse in patients with inflammatory bowel disease after withdrawal of anti-TNF agents following achievement of clinical remission. Clinical trial reference number: EudraCT 2015-001410-1

    Chemical Defence in a Millipede: Evaluation and Characterization of Antimicrobial Activity of the Defensive Secretion from Pachyiulus hungaricus (Karsch, 1881) (Diplopoda, Julida, Julidae)

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    The chemical defence of the millipede Pachyiulus hungaricus is reported in the present paper, in which a chemical characterization is given and antimicrobial activity is determined. In total, independently of sex, 44 compounds were identified. All compounds belong to two groups: quinones and pentyl and hexyl esters of long-chain fatty acids. The relative abundances of quinones and non-quinones were 94.7% vs. 5.3% (males) and 87.3% vs. 12.7% (females), respectively. The two dominant quinones in both sexes were 2-methyl-1,4,-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone. Antibacterial and antifungal activity of the defensive secretion was evaluated in vitro against seven bacterial strains and eight fungal species. With the aid of a dilution technique, the antimicrobial potential of the secretion and high sensitivity of all tested strains were confirmed. The lowest minimum concentrations of these compounds (0.20-0.25 mg/mL) were sufficient for inhibition of Aeromonas hydrophila, Listeria monocytogenes and Methicillin resistant Staphylococcus aureus (MRSA). The growth of eight tested fungal species was inhibited by slightly lower concentrations of the secretion, with Fusarium equisetias the most sensitive fungus and Aspergillus flavus as the most resistant. Values of MIC and MFC in the employed microdilution assay ranged from 0.10 to above 0.35 mg/m L. The given extract contains antimicrobial components potentially useful as therapeutic agents in the pharmaceutical and agricultural industries

    Effective and safe proton pump inhibitor therapy in acid-related diseases – A position paper addressing benefits and potential harms of acid suppression

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    Impact of indoor environmental quality on occupant well-being and comfort : a review of the literature

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    Indoor environmental quality (IEQ) and its effect on occupant well-being and comfort is an important area of study. This paper presents a state of the art study through extensive review of the literature, by establishing links between IEQs and occupant well-being and comfort. A range of issues such as sick building syndrome, indoor air quality thermal comfort, visual comfort and acoustic comfort are considered in this paper. The complexity of the relationship between occupant comfort and well-being parameters with IEQ are further exacerbated due to relationships that these parameters have with each other as well. Based on the review of literature in these areas it is established that design of buildings needs to consider occupant well-being parameters right at the beginning. Some good practices in all these different areas have also been highlighted and documented in this paper. The knowledge established as part of this paper would be helpful for researchers, designer, engineers and facilities maintenance engineers. This paper will also be of great benefit to researchers who endeavour to undertake research in this area and could act as a good starting point for them. Keywords Occupant well-being; Indoor environment quality; Occupant comfort; Offices; Green building

    Student teachers' perceptions of the effects of poverty on learners' educational attainment and well-being: perspectives from England and Scotland

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    This article reports on two UK initial teacher education studies from two contrasting contexts: a secondary school course in Oxford, England and a primary school course in Strathclyde, Scotland. The questions of how student teachers understand the effect of poverty on pupils’ educational achievement, and what they as prospective teachers can do to effect change, are common concerns of the research studies reported here. The Oxford study illustrates the problematic issue of student teachers’ perceptions of poverty, whilst the Strathclyde data suggests the potential power of a focused intervention to change views on poverty and education. A teacher identity framework is used to consider the interactions between external factors (schools, systems, communities of practice) and internal factors (knowledge, activities, thoughts, reflections), to understand how participation, alignment, agency and reification can support or undermine teachers’ understanding and enactment of teaching for social justice
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