725 research outputs found

    Ice properties in ISO 19906's second edition

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    The second edition of ISO 19906 Arctic Offshore structures was issued in 2019. In this paper, we describe the changes that were made to sections dealing with ice properties and discuss the relationship between them and ice actions. The changes can be divided into five groups: 1) Physical properties (temperature, density and porosity), 2) modulus of elasticity, 3) ice friction, 4) mechanical properties in level ice (uniaxial and multi-axial compressive strength, flexural strength and borehole jack strength), and 5) the keel properties of first-year ridge (Mohr-Coulomb, macro-porosity). The standard is written in such a way so that simple approaches in design guidelines complement more elaborate models. Both currently face at least three challenges, namely, the lack of full-scale data, a complicated physical environment, and a lack of understanding of the deformation mechanisms taking place in the ice

    Human notochordal cell transcriptome unveils potential regulators of cell function in the developing intervertebral disc

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    The adult nucleus pulposus originates from the embryonic notochord, but loss of notochordal cells with skeletal maturity in humans is thought to contribute to the onset of intervertebral disc degeneration. Thus, defining the phenotype of human embryonic/fetal notochordal cells is essential for understanding their roles and for development of novel therapies. However, a detailed transcriptomic profiling of human notochordal cells has never been achieved. In this study, the notochord-specific marker CD24 was used to specifically label and isolate (using FACS) notochordal cells from human embryonic and fetal spines (7.5-14 weeks post-conception). Microarray analysis and qPCR validation identified CD24, STMN2, RTN1, PRPH, CXCL12, IGF1, MAP1B, ISL1, CLDN1 and THBS2 as notochord-specific markers. Expression of these markers was confirmed in nucleus pulposus cells from aged and degenerate discs. Ingenuity pathway analysis revealed molecules involved in inhibition of vascularisation (WISP2, Noggin and EDN2) and inflammation (IL1-RN) to be master regulators of notochordal genes. Importantly, this study has, for the first time, defined the human notochordal cell transcriptome and suggests inhibition of inflammation and vascularisation may be key roles for notochordal cells during intervertebral disc development. The molecules and pathways identified in this study have potential for use in developing strategies to retard/prevent disc degeneration, or regenerate tissue.This research was funded by Arthritis Research UK (reference 21165 to SMR/JAH/LW) and the Henry Smith Charity (to JAH/SMR/MH). RRP was supported by a grant from the Programme for Advanced Medical Education, sponsored by Fundacão Calouste Gulbenkian, fundação Champalimaud, Ministério da Saúde, Fundação para a Ciência e Tecnologia and Apifarma, Portugal. Support was also received from the UK Medical Research Council (MR/J003352/1 to KPH), the Wellcome Trust (NAH was a senior fellow in clinical science, 088566; additional support from grant, 097820), and the British Council (14BX15NHBG to NAH). Consumable and technical support for this project (Sonal Patel) was funded by the National Institute for Health Research Manchester Musculoskeletal Biomedical Research Unit. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research, or the Department of Health. We are very grateful to all women who consented to take part in our research programme and for the assistance of research nurses and clinical colleagues at Manchester University NHS Foundation Trust. The authors would like to thank Prof Kathy Cheah and group for advice regarding the identification of sex-specific markers within microarray datasets.info:eu-repo/semantics/publishedVersio

    Peptide location fingerprinting reveals tissue region-specific differences in protein structures in an ageing human organ

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    In ageing tissues, long-lived extracellular matrix (ECM) proteins are susceptible to the accumulation of structural damage due to diverse mechanisms including glycation, oxidation and protease cleavage. Peptide location fingerprinting (PLF) is a new mass spectrometry (MS) analysis technique capable of identifying proteins exhibiting structural differences in complex proteomes. PLF applied to published young and aged intervertebral disc (IVD) MS datasets (posterior, lateral and anterior regions of the annulus fibrosus) identified 268 proteins with age-associated structural differences. For several ECM assemblies (collagens I, II and V and aggrecan), these differences were markedly conserved between degeneration-prone (posterior and lateral) and -resistant (anterior) regions. Significant differences in peptide yields, observed within collagen I alpha 2, collagen II alpha 1 and collagen V alpha 1, were located within their triple-helical regions and/or cleaved C-terminal propeptides, indicating potential accumulation of damage and impaired maintenance. Several proteins (collagen V alpha 1, collagen II alpha 1 and aggrecan) also exhibited tissue region (lateral)-specific differences in structure between aged and young samples, suggesting that some ageing mechanisms may act locally within tissues. This study not only reveals possible age-associated differences in ECM protein structures which are tissue-region specific, but also highlights the ability of PLF as a proteomic tool to aid in biomarker discovery

    HMM based scenario generation for an investment optimisation problem

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    This is the post-print version of the article. The official published version can be accessed from the link below - Copyright @ 2012 Springer-Verlag.The Geometric Brownian motion (GBM) is a standard method for modelling financial time series. An important criticism of this method is that the parameters of the GBM are assumed to be constants; due to this fact, important features of the time series, like extreme behaviour or volatility clustering cannot be captured. We propose an approach by which the parameters of the GBM are able to switch between regimes, more precisely they are governed by a hidden Markov chain. Thus, we model the financial time series via a hidden Markov model (HMM) with a GBM in each state. Using this approach, we generate scenarios for a financial portfolio optimisation problem in which the portfolio CVaR is minimised. Numerical results are presented.This study was funded by NET ACE at OptiRisk Systems

    Using environmental monitoring to complement in-depth qualitative interviews in cold homes research

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    Cold homes contribute to twenty to forty thousand excess winter deaths each year in the UK and approximately 300,000 hospital admissions. Using fuel poverty as an identifier for those at risk does not always capture everyday exposure to cold homes due to variations in financial trade-offs and behavioural factors. Few fuel poverty studies have combined environmental measurements with qualitative data on lived experiences of fuel poverty and cold homes. This paper looks at the strengths and limitations of using a mixed method, environmental and qualitative interviewing approach. A series of six discreet studies were conducted between 2001 and 2015 using a similar methodology with a mixed methods design where in-depth interviews were conducted alongside temperature and humidity measurements. The research studies found that combining environmental monitoring with qualitative research methods allows both cross validation and triangulation of data in order to provide a richer and more insightful examination into the lives of people living in cold homes. The studies demonstrate how a combined methodological approach can help explain the choices, decisions and behaviour of households experiencing cold homes and fuel poverty. The paper concludes with recommendations for future development and implementation of the research method

    Designing Peptide/Graphene Hybrid Hydrogels through Fine-Tuning of Molecular Interactions

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    A recent strategy that has emerged for the design of increasingly functional hydrogels is the incorporation of nanofillers in order to exploit their specific properties to either modify the performance of the hydrogel or add functionality. The emergence of carbon nanomaterials in particular has provided great opportunity for the use of graphene derivatives (GDs) in biomedical applications. The key challenge when designing hybrid materials is the understanding of the molecular interactions between the matrix (peptide nanofibers) and the nanofiller (here GDs) and how these affect the final properties of the bulk material. For the purpose of this work, three gelling β-sheet-forming, self-assembling peptides with varying physiochemical properties and five GDs with varying surface chemistries were chosen to formulate novel hybrid hydrogels. First the peptide hydrogels and the GDs were characterized; subsequently, the molecular interaction between peptides nanofibers and GDs were probed before formulating and mechanically characterizing the hybrid hydrogels. We show how the interplay between electrostatic interactions, which can be attractive or repulsive, and hydrophobic (and π–π in the case of peptide containing phenylalanine) interactions, which are always attractive, play a key role on the final properties of the hybrid hydrogels. The shear modulus of the hydrid hydrogels is shown to be related to the strength of fiber adhesion to the flakes, the overall hydrophobicity of the peptides, as well as the type of fibrillar network formed. Finally, the cytotoxicity of the hybrid hydrogel formed at pH 6 was also investigated by encapsulating and culturing human mesemchymal stem cells (hMSC) over 14 days. This work clearly shows how interactions between peptides and GDs can be used to tailor the mechanical properties of the resulting hydrogels, allowing the incorporation of GD nanofillers in a controlled way and opening the possibility to exploit their intrinsic properties to design novel hybrid peptide hydrogels for biomedical applications

    Recombinant MVA-prime elicits neutralizing antibody responses by inducing antigen-specific B cells in the germinal center.

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    The RV144 HIV-1 vaccine trial has been the only clinical trial to date that has shown any degree of efficacy and associated with the presence of vaccine-elicited HIV-1 envelope-specific binding antibody and CD4+ T-cell responses. This trial also showed that a vector-prime protein boost combined vaccine strategy was better than when used alone. Here we have studied three different priming vectors-plasmid DNA, recombinant MVA, and recombinant VSV, all encoding clade C transmitted/founder Env 1086 C gp140, for priming three groups of six non-human primates each, followed by a protein boost with adjuvanted 1086 C gp120 protein. Our data showed that MVA-priming favors the development of higher antibody binding titers and neutralizing activity compared with other vectors. Analyses of the draining lymph nodes revealed that MVA-prime induced increased germinal center reactivity characterized by higher frequencies of germinal center (PNA <sup>hi</sup> ) B cells, higher frequencies of antigen-specific B-cell responses as well as an increased frequency of the highly differentiated (ICOS <sup>hi</sup> CD150 <sup>lo</sup> ) Tfh-cell subset
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