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Almahwasi A.A.,University of Surrey | Jeynes J.C.,University of Exeter | Bradley D.A.,University of Surrey | Regan P.H.,UK National Engineering Laboratory
Radiation Physics and Chemistry | Year: 2017

Radiation-induced giant-nucleated cells (GCs) have been observed to occur within survivors of irradiated cancerous and within healthy cells, both in vivo and in vitro. The expression of such morphological alterations is associated with genomic instability. This study was designed to investigate the fate of GCs induced in a normal human fibroblast cell line (AG1522) after exposure to 0.2, 1 or 2Gy of X-ray or proton irradiation. The total of 79 individual AG1522 GCs present at 7, 14 or 21 days after each dose point were analysed from fluorescence microscopy images captured over approximately 120h. The GCs were identified at the beginning of the observation period for each time point post-irradiation and the area of the cell nucleus was measured (μm2) using a cell-recognition MATLAB code. The results demonstrate that the majority of GCs had undergone a prolonged mitotic arrest, which might be an indication of the survival strategy. The live cell microscopy confirms that a giant-nucleated cell formed 14 days after exposure to 0.2Gy of proton irradiation was divided into two asymmetrical normal-sized cells. These results suggest that a small fraction of GCs can proliferate and form progeny. Some of GCs had disappeared from the microscopy fields. The rate of their loss was decreased as the dose increased but there remains the potential for them to have progeny that could continue to proliferate, ultimately contributing to development of cancer risk. This important method to access delayed effects in normal tissues could act as a potential radioprotective assay for a dose-limiting parameter when applying radiotherapy. These results might have important implications in evaluating risk estimates for patients during radiation therapy treatment. © 2017 Elsevier Ltd.

Chen Y.,Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular SciencesInstitute of Chemistry | Du S.,Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular SciencesInstitute of Chemistry | Huang C.,Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular SciencesInstitute of Chemistry | Solan G.A.,UK National Engineering Laboratory | And 2 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2017

The N,N-diaryliminoacenaphthenes, 1,2-[2,4-((4-FC6H4)2CH)2-6-MeC6H4N]2-C2C10H6 (L1) and 1-[2,4-((4-FC6H4)2CH)2-6-MeC6H4N]-2-(ArN)C2C10H6 (Ar=2,6-Me2C6H3 L2, 2,6-Et2C6H3 L3, 2,6-i-Pr2C6H3 L4, 2,4,6-Me3C6H2 L5, 2,6-Et2-4-MeC6H2 L6), incorporating at least one N-2,4-bis(difluoro benzhydryl)-6-methylphenyl group, have been synthesized and fully characterized. Interaction of L1-L6 with (DME)NiBr2 (DME=1,2-dimethoxyethane) generates the corresponding nickel(II) bromide N,N-chelates, LNiBr2 (1-6), in high yield. The molecular structures of 3 and 6 reveal distorted tetrahedral geometries at nickel with the ortho-substituted difluorobenzhydryl group providing enhanced steric protection to only one side of the metal center. On activation with various aluminum alkyl co-catalysts, such as methylaluminoxane (MAO) or Et2AlCl, 1-6 displayed outstanding activity toward ethylene polymerization (up to 1.02 × 107 g of PE (mol of Ni)-1 h-1). Notably 1, bearing equivalent fluorobenzhydryl-substituted N-aryl groups, was able in the presence of Et2AlCl to couple high activity with exceptional thermal stability generating high molecular weight branched polyethylenes at temperatures as high as 100 °C. © 2017 Wiley Periodicals, Inc.

Li Z.,UK National Engineering Laboratory | Song Y.,UK National Engineering Laboratory | McLoughlin I.,University of Kent | Dai L.,UK National Engineering Laboratory
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2016

Transfer learning methods have demonstrated state-of-the-art performance on various small-scale image classification tasks. This is generally achieved by exploiting the information from an ImageNet convolution neural network (ImageNet CNN). However, the transferred CNN model is generally with high computational complexity and storage requirement. It raises the issue for real-world applications, especially for some portable devices like phones and tablets without high-performance GPUs. Several approximation methods have been proposed to reduce the complexity by reconstructing the linear or non-linear filters (responses) in convolutional layers with a series of small ones., In this paper, we present a compact CNN transfer learning method for small-scale image classification. Specifically, it can be decomposed into fine-tuning and joint learning stages. In fine-tuning stage, a high-performance target CNN is trained by transferring information from the ImageNet CNN. In joint learning stage, a compact target CNN is optimized based on ground-truth labels, jointly with the predictions of the high-performance target CNN. The experimental results on CIFAR-10 and MIT Indoor Scene demonstrate the effectiveness and efficiency of our proposed method. © 2016 IEEE.

MacAulay G.D.,UK National Engineering Laboratory | Giusca C.L.,UK National Engineering Laboratory
CIRP Annals - Manufacturing Technology | Year: 2016

Structured surfaces are increasingly popular for many applications and are characterised by dimensional properties, such as diameter, often reported without an uncertainty or one based on a reproducibility analysis, which does not account for systematic effects. This paper presents a method to assess uncertainty in structured surfaces using the instrument's metrological characteristics and applies it to an example surface. Information, such as the flatness map, is used to estimate uncertainty via Monte Carlo calculations, as single values of the metrological characteristics, which are usually estimated, do not give enough information. The calculated standard uncertainty of a feature is slightly larger than that provided by a reproducibility study for the same surface, but the proposed approach accounts for additional uncertainty sources due to systematic effects. © 2016.

Corlett A.E.,UK National Engineering Laboratory
2nd World Congress on Industrial Process Tomography | Year: 2013

An experimental study of an electrical capacitance tomography (ECT) system in multiphase flow was made at the National Engineering Laboratory. Its aim was to examine the system’s flow pattern recognition and void fraction measurement capabilities. A commercial ECT system was used together with a custom-made sensor spoolpiece. The test envelope spanned a wide range of multiphase flow conditions involving mixtures of crude oil, water and nitrogen gas. The water fraction was varied between 5% and 90% and two different water phases, tap water and a MgS04 solution, were used.Results indicated that the ECT system was most suitable for flow pattern identification purposes at low water fractions, although slug and stratified regimes could be identified at higher water fractions. Void fraction measurement was not found to be particularly successful. The sensitivity map and image reconstruction algorithm used were found to be critical factors in the quality and reliability of the generated results. © 2014 International Society for Industrial Process Tomography.

PubMed | UK National Engineering Laboratory, University of Cambridge and Massachusetts Institute of Technology
Type: Journal Article | Journal: The journal of physical chemistry. C, Nanomaterials and interfaces | Year: 2016

The wettability of graphene is both fundamental and crucial for interfacing in most applications, but a detailed understanding of its time evolution remains elusive. Here we systematically investigate the wettability of metal-supported, chemical vapor deposited graphene films as a function of ambient air exposure time using water and various other test liquids with widely different surface tensions. The wettability of graphene is not constant, but varies with substrate interactions and air exposure time. The substrate interactions affect the initial graphene wettability, where, for instance, water contact angles of 85 and 61 were measured for Ni and Cu supported graphene, respectively, after just minutes of air exposure. Analysis of the surface free energy components indicates that the substrate interactions strongly influence the Lewis acid-base component of supported graphene, which is considerably weaker for Ni supported graphene than for Cu supported graphene, suggesting that the classical van der Waals interaction theory alone is insufficient to describe the wettability of graphene. For prolonged air exposure, the effect of physisorption of airborne contaminants becomes increasingly dominant, resulting in an increase of water contact angle that follows a universal linear-logarithmic relationship with exposure time, until saturating at a maximum value of 92-98. The adsorbed contaminants render all supported graphene samples increasingly nonpolar, although their total surface free energy decreases only by 10-16% to about 37-41 mJ/m

PubMed | UK National Engineering Laboratory, Japan National Institute of Advanced Industrial Science and Technology, Bureau International des Poids et Mesures BIPM, INRIM - Istituto Nazionale di Ricerca Metrologica and 3 more.
Type: Journal Article | Journal: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences | Year: 2016

In 2018, it is expected that there will be a major revision of the International System of Units (SI) which will result in all of the seven base units being defined by fixing the values of certain atomic or fundamental constants. As part of this revision, the kelvin, unit of thermodynamic temperature, will be redefined by assigning a value to the Boltzmann constant k. This explicit-constant definition will define the kelvin in terms of the SI derived unit of energy, the joule. It is sufficiently wide to encompass any form of thermometry. The planned redefinition has motivated the creation of an extended mise en pratique (practical realization) of the definition of the kelvin (MeP-K), which describes how the new definition can be put into practice. The MeP-K incorporates both of the defined International Temperature Scales (ITS-90 and PLTS-2000) in current use and approved primary-thermometry methods for determining thermodynamic temperature values. The MeP-K is a guide that provides or makes reference to the information needed to perform measurements of temperature in accord with the SI at the highest level. In this article, the background and the content of the extended second version of the MeP-K are presented.

PubMed | UK National Engineering Laboratory, VTT Technical Research Center of Finland, Centro Espanol Of Metrologia Cem, National Institute for Standards of Egypt and 3 more.
Type: Journal Article | Journal: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences | Year: 2016

The mise-en-pratique for the definition of the kelvin at high temperatures will formally allow dissemination of thermodynamic temperature either directly or mediated through high-temperature fixed points (HTFPs). In this paper, these two distinct dissemination methods are evaluated, namely source-based and detector-based. This was achieved by performing two distinct dissemination trials: one based on HTFPs, the other based on absolutely calibrated radiation thermometers or filter radiometers. These trials involved six national metrology institutes in Europe in the frame of the European Metrology Research Programme joint project Implementing the new kelvin (InK). The results have shown that both dissemination routes are possible, with similar standard uncertainties of 1-2K, over the range 1273-2773K, showing that, depending on the facilities available in the laboratory, it will soon be possible to disseminate thermodynamic temperatures above 1273K to users by either of the two methods with uncertainties comparable to the current temperature scale.

PubMed | Physikalisch - Technische Bundesanstalt and UK National Engineering Laboratory
Type: Journal Article | Journal: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences | Year: 2016

Above the freezing temperature of silver (1234.93 K), the International Temperature Scale of 1990 (ITS-90) gives a temperature, T90, in terms of a defining fixed-point blackbody and Plancks law of thermal radiation in ratio form. Alternatively, by using Plancks law directly, thermodynamic temperature can be determined by applying radiation detectors calibrated in absolute terms for their spectral responsivity. With the advent of high-quality semiconductor photodiodes and the development of high-accuracy cryogenic radiometers during the last two decades radiometric detector standards with very small uncertainties in the range of 0.01-0.02% have been developed for direct, absolute radiation thermometry with uncertainties comparable to those for the realization of the ITS-90. This article gives an overview of a number of design variants of different types of radiometer used for primary radiometry and describes their calibration. Furthermore, details and requirements regarding the experimental procedure for obtaining low uncertainty thermodynamic temperatures with these radiometers are presented, noting that such radiometers can also be used at temperatures well below the silver point. Finally, typical results obtained by these methods are reviewed.

PubMed | UK National Engineering Laboratory, Japan National Institute of Information and Communications Technology and University of Cambridge
Type: Journal Article | Journal: Current biology : CB | Year: 2016

Pavlovian conditioning underlies many aspects of pain behavior, including fear and threat detection [1], escape and avoidance learning [2], and endogenous analgesia [3]. Although a central role for the amygdala is well established [4], both human and animal studies implicate other brain regions in learning, notably ventral striatum and cerebellum [5]. It remains unclear whether these regions make different contributions to a single aversive learning process or represent independent learning mechanisms that interact to generate the expression of pain-related behavior. We designed a human parallel aversive conditioning paradigm in which different Pavlovian visual cues probabilistically predicted thermal pain primarily to either the left or right arm and studied the acquisition of conditioned Pavlovian responses using combined physiological recordings and fMRI. Using computational modeling based on reinforcement learning theory, we found that conditioning involves two distinct types of learning process. First,a non-specific preparatory system learns aversive facial expressions and autonomic responses such as skin conductance. The associated learning signals-the learned associability and prediction error-were correlated with fMRI brain responses in amygdala-striatal regions, corresponding to the classic aversive (fear) learning circuit. Second, a specific lateralized system learns consummatory limb-withdrawal responses, detectable with electromyography of the arm to which pain is predicted. Its related learned associability was correlated with responses in ipsilateral cerebellar cortex, suggesting a novel computational role for the cerebellum in pain. In conclusion, our results show that the overall phenotype of conditioned pain behavior depends on two dissociable reinforcement learning circuits.

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