1,513 research outputs found

    National pupil projections : future trends in pupil numbers

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    Linewidths in bound state resonances for helium scattering from Si(111)-(1x1)H

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    Helium-3 spin-echo measurements of resonant scattering from the Si(111)–(1 × 1)H surface, in the energy range 4–14 meV, are presented. The measurements have high energy resolution yet they reveal bound state resonance features with uniformly broad linewidths. We show that exact quantum mechanical calculations of the elastic scattering, using the existing potential for the helium/Si(111)–(1 × 1)H interaction, cannot reproduce the linewidths seen in the experiment. Further calculations rule out inelastic and other mechanisms that might give rise to losses from the elastic scattering channels. We show that corrugation in the attractive part of the atom–surface potential is the most likely origin of the experimental lineshapes

    The certification of anti-myeloperoxidase immunoglobulin G in human serum ERM® - DA476/IFCC

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    This report describes the production and certification of ERM-DA476/IFCC, a new serum protein reference material intended for the standardisation of measurements of anti-myeloperoxidase immunoglobulin G (anti-MPO IgG) antibodies. The material was produced according to ISO Guide 34:2009. The raw material used to prepare ERM-DA476/IFCC was a plasmapheresis material containing a high concentration of anti-MPO IgG. After a thorough commutability study lyophilised serum was selected as the format for the candidate reference material. Serum processing was performed based on the procedure used for the reference material ERM-DA470k/IFCC. The plasma was converted into serum which was then delipidated. After the addition of preservatives the processed serum was diluted with plasmapheresis solution containing albumin, prior to the transfer of 1 mL aliquots to glass vials. The serum was then lyophilised and the vials closed with rubber stoppers and screw caps under nitrogen atmosphere prior to storage at -70 °C. The between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The material was characterised by an inter-laboratory comparison exercise performed by laboratories of demonstrated competence and with adherence to ISO/IEC 17025 , using a purified anti-MPO IgG preparation as calibrant. This was achieved using a value transfer protocol previously used in the characterisation of ERM-DA470k/IFCC. Technically invalid results were removed. However no other outliers were eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance to the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties relating to possible lack of homogeneity, instability and characterisation. The material is intended for the calibration of methods and quality control. As any reference material, it can also be used for control charts or validation studies. The CRM is available in glass vials containing the lyophilised residue of 1 g serum. The minimum amount of reconstituted sample to be used is 10 μL. The CRM was accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium

    Genome-wide microRNA and gene analysis of mesenchymal stem cell chondrogenesis identifies an essential role and multiple targets for miR-140-5p

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    microRNAs (miRNAs) are abundantly expressed in development where they are critical determinants of cell differentiation and phenotype. Accordingly miRNAs are essential for normal skeletal development and chondrogenesis in particular. However, the question of which miRNAs are specific to the chondrocyte phenotype has not been fully addressed. Using microarray analysis of miRNA expression during mesenchymal stem cell chondrogenic differentiation and detailed examination of the role of essential differentiation factors, such as SOX9, TGF-b, and the cell condensation phase, we characterize the repertoire of specific miRNAs involved in chondrocyte development, highlighting in particular miR-140 and miR-455. Further with the use of mRNA microarray data we integrate miRNA expression and mRNA expression during chondrogenesis to underline the particular importance of miR-140, especially the -5p strand. We provide a detailed identification and validation of direct targets of miR-140-5p in both chondrogenesis and adult chondrocytes with the use of microarray and 30 UTR analysis. This emphasizes the diverse array of targets and pathways regulated by miR-140-5p. We are also able to confirm previous experimentally identified targets but, additionally, identify a novel positive regulation of the Wnt signaling pathway by miR-140-5p. Wnt signaling has a complex role in chondrogenesis and skeletal development and these findings illustrate a previously unidentified role for miR-140-5p in regulation of Wnt signaling in these processes. Together these developments further highlight the role of miRNAs during chondrogenesis to improve our understanding of chondrocyte development and guide cartilage tissue engineering

    A geometric approach to visualization of variability in functional data

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    We propose a new method for the construction and visualization of boxplot-type displays for functional data. We use a recent functional data analysis framework, based on a representation of functions called square-root slope functions, to decompose observed variation in functional data into three main components: amplitude, phase, and vertical translation. We then construct separate displays for each component, using the geometry and metric of each representation space, based on a novel definition of the median, the two quartiles, and extreme observations. The outlyingness of functional data is a very complex concept. Thus, we propose to identify outliers based on any of the three main components after decomposition. We provide a variety of visualization tools for the proposed boxplot-type displays including surface plots. We evaluate the proposed method using extensive simulations and then focus our attention on three real data applications including exploratory data analysis of sea surface temperature functions, electrocardiogram functions and growth curves
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