The Cooperative Participatory Evaluation of Renewable Technologies on Ecosystem Services (CORPORATES)

Publisher PD

Thermal and electrical conductivity of iron at Earth's core conditions

The Earth acts as a gigantic heat engine driven by decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes, and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing to grow the solid inner core, and on chemical convection due to light elements expelled from the liquid on freezing. The power supplied to the geodynamo, measured by the heat-flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat-flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent difficulties in experimentation and theory. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles- the first directly computed values that do not rely on estimates based on extrapolations. The mixtures of Fe, O, S, and Si are taken from earlier work and fit the seismologically-determined core density and inner-core boundary density jump. We find both conductivities to be 2-3 times higher than estimates in current use. The changes are so large that core thermal histories and power requirements must be reassessed. New estimates of adiabatic heat-flux give 15-16 TW at the CMB, higher than present estimates of CMB heat-flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted and future models of mantle evolution must incorporate a high CMB heat-flux and explain recent formation of the inner core.Comment: 11 pages including supplementary information, two figures. Scheduled to appear in Nature, April 201

Systematic literature review of Rift Valley fever virus seroprevalence in livestock, wildlife and humans in Africa from 1968 to 2016

Background: Rift Valley fever virus (RVFV) is a zoonotic arbovirus that causes severe disease in livestock and humans. The virus has caused recurrent outbreaks in Africa and the Arabian Peninsula since its discovery in 1931. This review sought to evaluate RVFV seroprevalence across the African continent in livestock, wildlife and humans in order to understand the spatio-temporal distribution of RVFV seroprevalence and to identify knowledge gaps and areas requiring further research. Risk factors associated with seropositivity were identified and study designs evaluated to understand the validity of their results. Methodology: The Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to produce a protocol to systematically search for RVFV seroprevalence studies in PubMed and Web of Science databases. The Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement guided the evaluation of study design and analyses. Principal findings: A total of 174 RVFV seroprevalence studies in 126 articles fulfilled the inclusion criteria. RVFV seroprevalence was recorded in 31 African countries from 1968 to 2016 and varied by time, species and country. RVFV seroprevalence articles including either livestock and humans or livestock and wildlife seroprevalence records were limited in number (8/126). No articles considered wildlife, livestock and human seroprevalence concurrently, nor wildlife and humans alone. Many studies did not account for study design bias or the sensitivity and specificity of diagnostic tests. Conclusions: Future research should focus on conducting seroprevalence studies at the wildlife, livestock and human interface to better understand the nature of cross-species transmission of RVFV. Reporting should be more transparent and biases accounted for in future seroprevalence research to understand the true burden of disease on the African continent

Self-assessed proficiency and application of various skills learned during postgraduate pharmacy teaching skills development programs

The purpose of this study was to identify teaching skills commonly taught during the postgraduate pharmacy teaching skills development programs, to describe trainees\u27 perceived teaching proficiency, and the extent to which the learned teaching skills are applied in trainees\u27 current positions. An online survey was developed for pharmacists who completed postgraduate teaching skills development programs. The survey included demographic and program queries as well as questions on 23 teaching skills. Participants self-assessed their proficiency in and application of their learned teaching skills. The online survey resulted in 122 qualified responses. After training, the perceived proficiency in nearly all 23 teaching skills was high; however, the scores for application of teaching skills were significantly lower. A majority (91.7%) of survey respondents were engaged in experiential education. There is wide variability among the postgraduate pharmacy teaching skills development programs. Though the trainees perceived their proficiency in teaching skills to be high, the acquired teaching skills were underused

Reversals in nature and the nature of reversals

The asymmetric shape of reversals of the Earth's magnetic field indicates a possible connection with relaxation oscillations as they were early discussed by van der Pol. A simple mean-field dynamo model with a spherically symmetric $\alpha$ coefficient is analysed with view on this similarity, and a comparison of the time series and the phase space trajectories with those of paleomagnetic measurements is carried out. For highly supercritical dynamos a very good agreement with the data is achieved. Deviations of numerical reversal sequences from Poisson statistics are analysed and compared with paleomagnetic data. The role of the inner core is discussed in a spectral theoretical context and arguments and numerical evidence is compiled that the growth of the inner core might be important for the long term changes of the reversal rate and the occurrence of superchrons.Comment: 24 pages, 12 figure

Identifying culturally significant areas for marine spatial planning

Despite the growing recognition of their importance, immaterial cultural values associated with the sea still tend to be neglected in marine spatial planning (MSP). This socio-cultural evidence gap is due to inherent difficulties in defining and eliciting cultural values, but also to difficulties in linking cultural values to specific places, thus enabling an area-based approach to management. This paper addresses three aspects that are important for including marine cultural values in MSP: Defining cultural values, identifying places of cultural importance, and establishing the relative significance of places of cultural importance. We argue that common classification schemes such as cultural ecosystem services can be a helpful starting point for identifying cultural values, but only go so far in capturing communities' cultural connections with the sea. A method is proposed for structuring a community-based narrative on cultural values and “spatialising” them for MSP purposes, using five criteria that can lead to the definition of “culturally significant areas”. A baseline of culturally significant areas is suggested as an aid to planners to pinpoint places where cultural connections to the sea are particularly strong. Throughout, we emphasise the need for participative processes

Time resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The underlying research dataset supporting this publication is available under a Creative Commons Attribution-ShareAlike 4.0 International License (https://creativecommons. org/licenses/by-sa/4.0/) and can be publicly accessed in Open Research Exeter via the following persistent identifier: http://hdl.handle.net/10871/21108.To meet growing data storage needs, the density of data stored on hard disk drives must increase. In pursuit of this aim the magnetodynamics of the hard disk write head must be characterized and understood, particularly the process of “flux beaming”. In this study, seven different configurations of perpendicular magnetic recording (PMR) write heads were imaged using time-resolved scanning Kerr microscopy, revealing their detailed dynamic magnetic state during the write process. It was found that the precise position and number of driving coils can significantly alter the formation of flux beams during the write process. These results are applicable to the design and understanding of current PMR and next-generation heat-assisted magnetic recording (HAMR) devices, as well as being relevant to other magnetic devices.The authors gratefully acknowledge financial support from the Seagate Plan

Dissociation of Water on Defective Carbon Substrates

Article on the dissociation of water on defective carbon substrates

Transmission and Control of African Horse Sickness in The Netherlands: A Model Analysis

African horse sickness (AHS) is an equine viral disease that is spread by Culicoides spp. Since the closely related disease bluetongue established itself in The Netherlands in 2006, AHS is considered a potential threat for the Dutch horse population. A vector-host model that incorporates the current knowledge of the infection biology is used to explore the effect of different parameters on whether and how the disease will spread, and to assess the effect of control measures. The time of introduction is an important determinant whether and how the disease will spread, depending on temperature and vector season. Given an introduction in the most favourable and constant circumstances, our results identify the vector-to-host ratio as the most important factor, because of its high variability over the country. Furthermore, a higher temperature accelerates the epidemic, while a higher horse density increases the extent of the epidemic. Due to the short infectious period in horses, the obvious clinical signs and the presence of non-susceptible hosts, AHS is expected to invade and spread less easily than bluetongue. Moreover, detection is presumed to be earlier, which allows control measures to be targeted towards elimination of infection sources. We argue that recommended control measures are euthanasia of infected horses with severe clinical signs and vector control in infected herds, protecting horses from midge bites in neighbouring herds, and (prioritized) vaccination of herds farther away, provided that transport regulations are strictly applied. The largest lack of knowledge is the competence and host preference of the different Culicoides species present in temperate regions