Development of highly selective ligands for separations of actinides from lanthanides in the nuclear fuel cycle

This account summarizes recent work by us and others on the development of ligands for the separation of actinides from lanthanides contained in nuclear waste streams in the context of a future European strategy for nuclear waste management. The current status of actinide/lanthanide separations worldwide is briefly discussed, and the synthesis, development, and testing of different classes of heterocyclic soft N- and S-donor ligands in Europe over the last 20 years is presented. This work has led to the current benchmark ligand that displays many of the desirable qualities for industrial use. The improvement of radiolytic stability through ligand design is also discussed

Unveiling the cause of hybrid morphology radio sources (HyMoRS)

19 pages, 4 figures, 6 tables. Accepted for publication in MNRASHybrid morphology radio sources (HyMoRS) are a rare group of radio galaxies in which differing Fanaroff & Riley morphologies (FR I/II) are observed for each of the two lobes. While they potentially provide insights into the formation of lobe structure, particle acceleration, and the FR dichotomy, previous work on HyMoRS has mainly been limited to low-resolution studies, searches for new candidates, and milliarcsecond-scale VLBI observations of the core region. In this paper, we use new multi-array configuration Very Large Array (VLA) observations between 1 and 8 GHz to determine the morphology of HyMoRS on arcsecond scales and perform the first well-resolved spectral study of these unusual sources. We find that while the apparent FR I lobe is centre-brightened, this is the result of a compact acceleration region resembling a hotspot with a spectrum more consistent with an FR II ("strong-flavour") jet. We find that the spectra of the apparent FR I lobes are not similar to their classical counterparts and are likely the result of line-of-sight mixing of plasma across a range of spectral ages. We consider possible mechanisms that could lead to the formation of HyMoRS under such conditions, including environment asymmetry and restarted sources, concluding through the use of simple modelling that HyMoRS are the result of orientation effects on intrinsically FR II sources with lobes non-parallel to the inner jet.Peer reviewedFinal Accepted Versio

Deep Metric Learning and Image Classification with Nearest Neighbour Gaussian Kernels

We present a Gaussian kernel loss function and training algorithm for convolutional neural networks that can be directly applied to both distance metric learning and image classification problems. Our method treats all training features from a deep neural network as Gaussian kernel centres and computes loss by summing the influence of a feature's nearby centres in the feature embedding space. Our approach is made scalable by treating it as an approximate nearest neighbour search problem. We show how to make end-to-end learning feasible, resulting in a well formed embedding space, in which semantically related instances are likely to be located near one another, regardless of whether or not the network was trained on those classes. Our approach outperforms state-of-the-art deep metric learning approaches on embedding learning challenges, as well as conventional softmax classification on several datasets.Comment: Accepted in the International Conference on Image Processing (ICIP) 2018. Formerly titled Nearest Neighbour Radial Basis Function Solvers for Deep Neural Network

A Genetic and Physiological Study of the Role of Extracellular Copper-Binding Proteins in Copper Detoxification by the Marine Bacterium \u3ci\u3eVibrio alginolyticus\u3c/i\u3e

Supernatant proteins in Vibrio alginolyticus batch cultures were analyzed by SDS-PAGE before copper was added, 24 and 48 hours after the addition of copper, and in 24 hour control (no Cu) cultures. Two proteins, one 21 kilodalton (kDa) and one 19 kDa, were found to be copper-induced, and were designated copper-binding protein 1 (CuBP1) and CuBP2. CuBP1 and CuBP2 became detectable in supernatants during the Cu-induced lag phase, and increased in concentration over the following 48 hours. Chloramphenicol inhibited production of these proteins. Gel-to-gel variability was implicated as the dominant factor determining whether one or two Cu-induced proteins were detected in Vibrio alginolyticus supernatants, and ca. 20 kDa Cu-induced proteins were quantitated together in subsequent analyses. Experiments in continuous (chemostat) cultures of Vibrio alginolyticus demonstrated that the bacteria could survive copper stress in an open system. Copper stress reversibly inhibited swarming in most colonies from long-term copper-stressed cultures, and permanent inhibition of swarming was observed in some isolates. Mutation to an oxidase negative phenotype, which was not reversible, occurred at high frequency in copper-stressed continuous cultures. The stability of two Cur mutants isolated from continuous culture was demonstrated by subculturing each isolate ten times on nonselective marine agar (10° MA), and comparing plate counts on unamended and 40μM Cu-amended agar to corresponding plate counts of isolates freshly passed on Cu-amended agar. One Cur isolate, Cu40B3, constitutively produced a ca. 21 kDa protein which displayed the same chromatographic behavior (immobilized metal ion affinity chromatography followed by reverse phase high performance liquid chromatography) as CuBP. After fifteen nonselective subcultures, a revertant Cus derivative of Cu40B3 (Cu40B3(SW)) was isolated. Cu40B3(SW) lost the mutation to constitutive CuBP production and copper resistance simultaneously, indicating that constitutive CuBP production in Cu40B3 is necessary for maintenance of its copper-resistant phenotype. Copper-sensitive Vibrio alginolyticus mutants displayed a range of alterations in supernatant protein profiles, and two of the seven mutants were indistinguishable from the wild-type in terms of supernatant proteins with and without copper stress. One Cus mutant was isolated which contained no CuaP in supernatants from 50 μM copper-stressed cultures

Postal card from J. Harwood Frost

Postal card concerning a copy of the catalogue for Utah Agricultural College

The impact of a young radio galaxy : Clues from the cosmic ray electron population

In the framework of hierarchical structure formation, active galactic nuclei (AGN) feedback shapes the galaxy luminosity function. Low luminosity, galaxy-scale double radio sources are ideal targets to investigate the interplay between AGN feedback and star formation. We use Very Large Array and BIMA millimetre-wave array observations to study the radio continuum emission of NGC 3801 between 1.4 and 112.4 GHz. We find a prominent spectral break at 10 GHz, where the spectrum steepens as expected from cosmic ray electron (CRe) ageing. Using the equipartition magnetic field and fitting JP models locally, we create a spatially resolved map of the spectral age of the CRe population. The spectral age of τint =2.0±0.2Myr agrees within a factor of 2 with the dynamical age of the expanding X-ray emitting shells. The spectral age varies only little across the lobes, requiring an effective mixing process of the CRe such as a convective backflow of magnetized plasma. The jet termination points have a slightly younger CRe spectral age, hinting at in situ CRe re-acceleration. Our findings support the scenario where the supersonically expanding radio lobes heat the interstellar medium (ISM) of NGC 3801 via shock waves, and, as their energy is comparable to the energy of the ISM, are clearly able to influence the galaxy's further evolution.Peer reviewe

Spectral ageing in the era of big data : Integrated versus resolved models

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Continuous injection models of spectral ageing have long been used to determine the age of radio galaxies from their integrated spectrum; however, many questions about their reliability remain unanswered. With various large area surveys imminent (e.g. LOw Frequency ARray, MeerKAT, MurchisonWidefield Array) and planning for the next generation of radio interferometers are well underway (e.g. next generationVLA, SquareKilometreArray), investigations of radio galaxy physics are set to shift away from studies of individual sources to the population as a whole. Determining if and how integrated models of spectral ageing can be applied in the era of big data is therefore crucial. In this paper, I compare classical integrated models of spectral ageing to recent well-resolved studies that use modern analysis techniques on small spatial scales to determine their robustness and validity as a source selection method. I find that integrated models are unable to recover key parameters and, even when known a priori, provide a poor, frequency-dependent description of a source's spectrum. I show a disparity of up to a factor of 6 in age between the integrated and resolved methods but suggest, even with these inconsistencies, such models still provide a potential method of candidate selection in the search for remnant radio galaxies and in providing a cleaner selection of high redshift radio galaxies in z - α selected samples.Peer reviewe

Prolyl Oligopeptidase, Inositol Phosphate Signalling and Lithium Sensitivity

Inhibition of prolyl oligopeptidase (PO) elevates inositol phosphate (IP) signalling and reduces cell sensitivity to lithium (Li+). This review discusses recent evidence that shows PO acts via the multiple inositol polyphosphate phosphatase (MIPP) to regulate gene expression. As a consequence, PO inhibition causes both a transient, rapid increase in I(1,4,5)P3 and a long-term elevation of IP signalling. This pathway is evolutionary conserved, being present in both the social amoeba Dictyostelium and human cell systems, and has potential implications for mental health

Isogrid design handbook

Handbook has been published which presents information needed for design of isogrid triangular integral-stiffened structures. It develops equations, methods, and graphs to handle wide variety of loadings, materials, and geometry. Handbook is divided into seven sections. Handbook may be used by marine and civil engineers and by students and designers without access to computers