2,507 research outputs found

    Competition and economic performance

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    Onderzoek naar het aandeel van concurrentie bij sector prestatie aan de hand van twee tijdsperioden; het verleden (1988 - 1999) en de toekomst (2001-2012). Voor dit onderzoek is een model (MOCO) ontwikkeld om de effecten van turbulentie en concentratie van economische prestaties van sectoren te analyseren.

    Characterization of Yersinia Pseudotuberculosis Abiotic Stress Responses

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    Bacteria require optimal growth conditions in order to thrive. However, stress factors such as cold and oxidation can attribute to the pathogenecity of a species. Ribonuclease E ( RNase E) is a component of the multicomplex protein, the degradosome, which is inclusive of: enolase (a glycolytic enzyme), and RhlB helicase, and 3\u27 -5\u27 exoribonuclease polynucleotide phosphorylase (PNPase). The microbiological model organism, E. coli, is attributed to first indicating the presence of microdomain PNPase in the degradosome. However, the species of interest in this study is Yersinia pseudotuberculosis (YPT) due to its affinity to proliferate and sustain in said abiotic stress environments unlike its enterobacteriaceae counterpart. YPT exposed to oxidative stress need degradosome assembly therefore it is degradosome-dependent. Conversely, the cold growth mechanism of PNPase in YPT is degradosome-independent

    The real-time measurement of wear using ultrasonic reflectometry

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    Ultrasonic reflectometry is commonly used in the fields of non-destructive testing (NDT) for crack detection, wall thickness monitoring and medical imaging. A sound wave is emitted through the material using a piezoelectric transducer. This waveform travels through the host medium at a constant speed and is either partially or fully reflected at an interface. The reflected wave is picked up by the same sensor; the signal is then amplified and digitised. If the speed that sound travels through a host medium is known as well as the time this takes, the thickness of the material can be established using the speed, distance and time relationship. Previous work has concluded that the ultrasonic method is too inaccurate to measure wear due to the errors caused by temperature, vibration and the experimental arrangement. This body of work looks at methods to minimise these errors, particularly the inaccuracies introduced from the change in temperature caused by change of acoustic velocity and the thermal expansion of the material, which can be significant in many applications. Numerous case studies are presented using the technique in both laboratory and industrial environments using low cost retro-fittable sensors and small form electronics

    IMPACT ASSESSMENT OF ENHANCED EXPOSURE FROM NATURALLY OCCURRING RADIOACTIVE MATERIALS (NORM) WITHIN LCA

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    The potential impact of ionising radiation from enhanced exposure to Naturally Occurring Radioactive Materials (NORM) to humans and the environment is not currently accounted for sufficiently in Life Cycle Assessment (LCA). Here we present midpoint and endpoint characterisation factors resulting from the implementation of impact assessment models for human health and ecosystems for NORM exposure. These models build upon existing fate, exposure and effect models from the LCA and radiological literature. The newly developed models are applied to a theoretical study of the utilisation of bauxite residue, a by-product of alumina processing enriched in natural radionuclides, in building materials. The ecosystem models have significant sensitivity to uncertainties surrounding the differential environmental fate of parent and daughter radionuclides that are produced as a part of decay chains, and to assumptions regarding long term releases from landfill sites. However, conservative results for environmental exposure suggest that in addition to landfill of materials, power consumption (burning coal and mining uranium) is a potentially significant source of radiological impact to the environment. From a human perspective, exposure to NORM in the use phase of building materials is the dominant source of impact, with environmental releases of nuclides playing a comparatively minor role. At an endpoint level, the impact of NORM exposure is highly significant in comparison to other impact categories in the area of protection of human health. This highlights the importance within LCA of having sufficient impact assessment models to capture all potential impacts, such that issues of burden shifting between impact measures can be captured, interpreted and resolved in the optimisation of product systems.https://doi.org/10.1016/j.jclepro.2017.11.13
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