The effect of sample preparation on uranium hydriding

AbstractThe influence of sample cleaning preparation on the early stages of uranium hydriding has been examined, by using four identical samples but concurrently prepared using four different methods. The samples were reacted together in the same corrosion cell to ensure identical exposure conditions. From the analysis, it was found that the hydride nucleation rate was proportional to the level of strain exhibiting higher number density for the more strained surfaces. Additionally, microstructure of the metal plays a secondary role regarding initial hydrogen attack on the highly strained surfaces yet starts to dominate the system while moving to more pristine samples

A unified framework for Schelling's model of segregation

Schelling's model of segregation is one of the first and most influential models in the field of social simulation. There are many variations of the model which have been proposed and simulated over the last forty years, though the present state of the literature on the subject is somewhat fragmented and lacking comprehensive analytical treatments. In this article a unified mathematical framework for Schelling's model and its many variants is developed. This methodology is useful in two regards: firstly, it provides a tool with which to understand the differences observed between models; secondly, phenomena which appear in several model variations may be understood in more depth through analytic studies of simpler versions.Comment: 21 pages, 3 figure

Empowering open science with reflexive and spatialised indicators

Bibliometrics have become commonplace and widely used by authors and journals to monitor, to evaluate and to identify their readership in an ever-increasingly publishing scientific world. This contribution introduces a multi-method corpus analysis tool, specifically conceived for scientific corpuses with spatialised content. We propose a dedicated interactive application that integrates three strategies for building semantic networks, using keywords (self-declared themes), citations (areas of research using the papers) and full-texts (themes derived from the words used in writing). The networks can be studied with respect to their temporal evolution as well as to their spatial expressions, by considering the countries studied in the papers under inquiry. The tool is applied as a proof-of-concept on the papers published in the online open access geography journal Cybergeo since its creation in 1996. Finally, we compare the three methods and conclude that their complementarity can help go beyond simple statistics to better understand the epistemological evolution of a scientific community and the readership target of the journal. Our tool can be applied by any journal on its own corpus, fostering thus open science and reflexivity

In-situ, time resolved monitoring of uranium in BFS:OPC grout. Part 1: Corrosion in water vapour

Uranium encapsulated in grout was exposed to water vapour for extended periods of time. Through synchrotron x-ray powder difraction and tomography measurements, uranium dioxide was determined the dominant corrosion product over a 50-week time period. The oxide growth rate initiated rapidly, with rates comparable to the U+H2O reaction. Over time, the reaction rate decreased and eventually plateaued to a rate similar to the U+H2O+O2 reaction. This behaviour was not attributed to oxygen ingress, but instead the decreasing permeability of the grout, limiting oxidising species access to the metal surface

Dynamic modelling of the potential habitat loss of endangered species: the case of the Canarian houbara bustard (Chlamydotis undulata fuerteventurae)

In this work, we apply a dynamic modelling approach to analyse the habitat loss of the Canarian houbara bustard (Chlamydotis undulata fuerteventurae). This tool allows us to assess the effects of the socio-economic and environmental interactions on the factors threatening the habitat and to carry out a prospective analysis. The results show a potential habitat loss of around 13 % during the period 1996–2011, the land uptake and increase in new roads and tracks being the factors contributing most. After model testing, a set of scenarios was explored. Under the business as usual (BAU) scenario, around 20 % of the habitat would be lost by the end of the period considered (2012–2025). The impact of the economic growth scenario on the habitat would mean an additional loss of around 21 % with respect to BAU, whereas under the recession scenario, the loss might be around 6.5 % lower than BAU. The policy of restoration of gavias—traditional farming systems—would suppose an additional loss of almost 6 %, relative to BAU. If this policy took place under economic growth conditions, it might mean an additional loss of almost 28 % relative to BAU. These results point to the existence of a potential trade-off between the recuperation of ecosystem services offered by restored gavias and the conservation of the houbara habitat, which must be addressed within the management processes, as well as to the need for compensatory measures to guarantee the conservation goals