Solar cell radiation response near the interface of different atomic number materials

The response of cobalt 60 irradiated N/P silicon solar cells was measured as a function of the atomic number of the medium adjacent to the cell and the direction of the gamma ray beam. The interpositioning of various thicknesses of aluminum between the adjacent material and the cell had the effect of moving the cell to various locations in an approximate monatomic numbered medium. Using this technique the solar cell response was determined at various distances from the interface for gold and beryllium. The results were compared with predictions based upon ionization chamber measurements of dose perturbations in aluminum and found to agree within five percent. Ionization chamber data was then used to estimate the influence of various base contact materials

Molecular gas temperature and density in spiral galaxies

We combine beam-matched CO-13, CO-12 J = 3 yields 2 and J = 2 yields 1 line data to infer the molecular gas excitation conditions in the central 500 to 1600 pc diameters of a small sample of infrared-bright external galaxies: NGC253, IC342, M 83, Maffei 2, and NGC6946. Additional observations of the J = 1 yields 0 lines of C-18O and CO-13 set limits on the opacity of the CO-13 J = 1 yields 0 line averaged over the central kiloparsec of these spiral galaxies

Effect of Gravitational Lensing on Measurements of the Sunyaev-Zel'dovich Effect

The Sunyaev-Zel'dovich (SZ) effect of a cluster of galaxies is usually measured after background radio sources are removed from the cluster field. Gravitational lensing by the cluster potential leads to a systematic deficit in the residual intensity of unresolved sources behind the cluster core relative to a control field far from the cluster center. As a result, the measured decrement in the Rayleigh-Jeans temperature of the cosmic microwave background is overestimated. We calculate the associated systematic bias which is inevitably introduced into measurements of the Hubble constant using the SZ effect. For the cluster A2218, we find that observations at 15 GHz with a beam radius of 0'.4 and a source removal threshold of 100 microJy underestimate the Hubble constant by 6-10%. If the profile of the gas pressure declines more steeply with radius than that of the dark matter density, then the ratio of lensing to SZ decrements increases towards the outer part of the cluster.Comment: 11 pages, 3 figures, submitted to ApJ

Response to ‘Assessing the energy requirements and global warming potential of the production of rare earth elements’

This is the final version. Available on open access from Elsevier via the DOI in this recordIn this letter, we respond to the article in this journal by Weng et al. (2016) which performs a cradle to gate scale life cycle impact assessment for 26 operating and potential rare earth element (REE) mining projects. The work focuses on gross energy requirement and the global warming impacts of the primary REE production stage. The results suggest that the declining ore grades of REE significantly increase the environmental impact of REE production. We agree that a life cycle impact approach can be useful in comparing proposed REE production routes in the various different deposits currently under exploration, and were pleased to see a range of deposit types included in this work. However, we would like to make five points to clarify some of the results, which if taken at ‘face value’ from the graphs presented by Weng et al. (2016) may be misleading.Research was funded by SoS RARE NERC consortium (NE/ M011429/1), www.sosrare.org with University of Exeter cofunding for R. Pell’s PhD project. Mkango Resources Ltd, owners of the Songwe Hill exploration project, are one of the industry partners on this project

Model projects as tools for cooperative urban development: The case of Haus der Statistik in Berlin

According to the New Leipzig Charter, urban development processes should be ‘a matter of all’ – the common good, climate protection and environmental justice, to name but a few aspects. Currently, new forms of innovation seeking models emerge within this context of sustainable urban planning practice - for example, real-world field laboratories and model projects. Haus der Statistik in Berlin is one such ‘model project for cooperative and common-good-oriented urban development’. It is widely recognized for its demand- and process-driven approach, as well as its project development being based on public-civic partnership. As anthropological and urbanist researchers and practitioners involved in the project, we give a situated account on the socio-political elements of the Haus der Statistik’s public-civic partnership and investigate the potentials of this model for a more sustainable urban development. The structure of the paper is threefold: Firstly, we introduce the so-called model project Haus der Statistik and its common-good orientated agenda and relate it to sustainability goals of the New Leipzig Charter. Secondly, we introduce the specific public-civic-framework in regard to its methodological framing within the context of model projects and comparable approaches that focus on collaborative, transdisciplinary and innovative methods, such as real-world field laboratories. Thirdly, we reflect on the elements of the public-civic-partnership framework that have been explored and developed at the ‘model project’ Haus der Statistik since 2015 and its implications for a more sustainable urban development.Peer Reviewe

Applying and advancing the economic resource scarcity potential (ESP) method for rare earth elements

This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this record.A number of studies have identified rare earth elements (REE) as critical metals due to their high economic importance combined with a high risk of supply disruption (Du et al, 2011; Nassar et al, 2015; Schneider et al, 2014). The current methods used to calculate resource depletion in life cycle assessments (LCA) neglect socio-economic, regulatory and geopolitical aspects, nor do they include functionalities such as material recycling or reuse that control the supply of raw materials. These are important factors in determining criticality and are the controlling factors on REE availability rather than geological availability. The economic scarcity potential (ESP) method introduced by Schneider et al. (2014) provides a framework to calculate criticality. This paper reviews the ESP method and advances the method based on recent developments in material criticality. ESP criticality scores for 15 REE with the addition of Au, Cu, platinum-group metals (PGM), Fe and Li are measured. The results highlight that Nd and Dy are the most critical REE, owing mainly to the high demand growth forecast for these two elements. A pathway is presented for incorporating these calculated scores into the ReCiPe life cycle impact assessment (LCIA) method of a LCA.Research was funded by NERC SoS RARE consortium (NE/M011429/1), www.sosrare.org with University of Exeter co-funding for R. Pell’s PhD project. The authors appreciate the funding assistance from the Camborne School of Mines Trust to visit and present this research in USA and gain insight from the Critical Metals team from Yale University and Nedal Nassar and his team at USGS

A reliable Pade analytical continuation method based on a high accuracy symbolic computation algorithm

We critique a Pade analytic continuation method whereby a rational polynomial function is fit to a set of input points by means of a single matrix inversion. This procedure is accomplished to an extremely high accuracy using a novel symbolic computation algorithm. As an example of this method in action we apply it to the problem of determining the spectral function of a one-particle thermal Green's function known only at a finite number of Matsubara frequencies with two example self energies drawn from the T-matrix theory of the Hubbard model. We present a systematic analysis of the effects of error in the input points on the analytic continuation, and this leads us to propose a procedure to test quantitatively the reliability of the resulting continuation, thus eliminating the black magic label frequently attached to this procedure.Comment: 11 pages, 8 eps figs, revtex format; revised version includes reference to anonymous ftp site containing example codes (MapleVr5.1 worksheets) displaying the implementation of the algorithm, including the padematinv.m library packag

Transmission Electron Study of Heteroepitaxial Growth in the BiSrCaCuO System

Films of Bi$\rm _2$Sr$\rm _2$CaCu$\rm _2$O$\rm _8$ and Bi$\rm _2$Sr$\rm _2$CuO$\rm _6$ have been grown using Atomic-Layer-by-Layer Molecular Beam Epitaxy (ALL-MBE) on lattice-matched substrates. These materials have been combined with layers of closely-related metastable compounds like Bi$\rm _2$Sr$\rm _2$Ca$\rm _7$Cu$\rm _8$O$\rm _{20}$ (2278) and rare-earth-doped compounds like Bi$\rm _2$Sr$\rm _2$Dy$\rm _x$Ca$\rm _{1-x}$Cu$\rm _2$O$\rm _8$ (Dy:2212) to form heterostructures with unique superconducting properties, including superconductor/insulator multilayers and tunnel junctions. Transmission electron microscopy (TEM) has been used to study the morphology and microstructure of these heterostructures. These TEM studies shed light on the physical properties of the films, and give insight into the growth mode of highly anisotropic solids like Bi$\rm _2$Sr$\rm _2$CaCu$\rm _2$O$\rm _8$.Comment: 17 pages, submitted to J. Materials Research. Email to [email protected] if you want to receive copies of the figure

In vitro analysis of the invasive phenotype of SUM 149, an inflammatory breast cancer cell line

BACKGROUND: Inflammatory breast cancer (IBC) is the most lethal form of locally invasive breast cancer known. However, very little information is available on the cellular mechanisms responsible for manifestation of the IBC phenotype. To understand the unique phenotype of IBC, we compared the motile and adhesive interactions of an IBC cell line, SUM 149, to the non-IBC cell line SUM 102. RESULTS: Our results demonstrate that both IBC and non-IBC cell lines exhibit similar adhesive properties to basal lamina, but SUM 149 showed a marked increase in adhesion to collagen I. In vitro haptotaxis assays demonstrate that SUM 149 was less invasive, while wound healing assays show a less in vitro migratory phenotype for SUM 149 cells relative to SUM 102 cells. We also demonstrate a role for Rho and E-cadherin in the unique invasive phenotype of IBC. Immunoblotting reveals higher E-cadherin and RhoA expression in the IBC cell line but similar RhoC expression. Rhodamine phalloidin staining demonstrates increased formation of actin stress fibers and larger focal adhesions in SUM 149 relative to the SUM 102 cell line. CONCLUSION: The observed unique actin and cellular architecture as well as the invasive and adhesive responses to the extracellular matrix of SUM 149 IBC cells suggest that the preference of IBC cells for connective tissue, possibly a mediator important for the vasculogenic mimicry via tubulogenesis seen in IBC pathological specimens. Overexpression of E-cadherin and RhoA may contribute to passive dissemination of IBC by promoting cell-cell adhesion and actin cytoskeletal structures that maintain tissue integrity. Therefore, we believe that these findings indicate a passive metastatic mechanism by which IBC cells invade the circulatory system as tumor emboli rather than by active migratory mechanisms

Magnetic properties of REE fluorcarbonate minerals and their implications for minerals processing

This is the final version. Available on open access from Elsevier via the DOI in this recordRare earth elements (REE) are considered as critical metals for electronics and green technology. The REE fluorcarbonates are one of the main REE ore minerals, common in many different types of REE deposit and yet some of their fundamental properties have still not been determined. This study measured the magnetic properties of pure REE fluorcarbonate single crystal minerals using a vibrating sample magnetometer (VSM) and determined their elemental compositions using electron probe microanalysis (EPMA). The results provide the first measurements of the magnetic behaviour and susceptibility of REE fluorcarbonates other than bastnäsite-(Ce). The magnetic susceptibility of REE fluorcarbonates varies systematically from one mineral to another and is highly dependent on the mineral chemistry. It is positive (paramagnetic) for bastnäsite-(Ce) and gradually decreases as the amount of Ca increases in parisite-(Ce), becoming negative (diamagnetic) for the Ca-rich member of the series, röntgenite. Synchysite-(Ce) is difficult to measure, generate good signal and acquire accurate readings because it practically always occurs as <5 mg crystals. Its magnetic susceptibility in samples from a REE ore deposit was experimentally determined by magnetic separation and checked by an associated study using a SQUID magnetometer, synchysite-(Ce) behaved as a diamagnetic mineral. This can be explained by the increase of Ca content and decrease of REE content, in addition to the variations in the layered structure common to the REE fluorcarbonate series minerals. Given the wide range of magnetic susceptibility of REE fluorcarbonates, it is important that the mineralogy is determined carefully before setting up a mineral processing flow sheet.Mkango Resources LtdNatural Environment Research Council (NERC