Spatial scaling of CO2 efflux in a temperate grazed grassland

Understanding CO2 efflux from soil at different scales is important when up-scaling CO2 measurements from plot to larger scales, but there have been few studies investigating spatial CO2 efflux in temperate environments. We conducted a nested analysis of variation to explore how the CO2 efflux variation occurs between different spatial scales. Ninety-six manual dynamic chamber flux measurements of CO2 were undertaken during three, four hour surveys within seven grouped sites, each containing an optimised nested design with lag distances of 0.3m, 1m, 3m and 9m across six hectares of grazed hillslope grassland. This design also included continuous logging soil moisture sensors (plus conductivity and temperature) at 10cm soil depth. A previous study showed at this site that the variation of soil moisture is divided relatively equally between the four spatial scales 9m. The proportion of large-scale (>9m) variation increased after rainfall. In contrast in the three surveys analysed to date, the vast majority of the variation in CO2 flux occurred over the two smallest scales. No significant correlation between CO2 and soil moisture was observed over any of the spatial scales. All of these three surveys were conducted on relatively dry soils. We also investigated whether there were significant temporal variations in CO2 efflux over a period of three weeks using an automated soil flux system. These data showed there was no significant temporal variability between 10:00 to 16:00 hrs during late summer. There has recently been substantial rainfall at the field site and we are now conducting additional surveys to examine how the total CO2 fluxes and their spatial variation is effected by these wetter conditions

The novel design of an energy efficient superconductor-based series reactor for installation at a grid connected research site

This paper proposes the development of a superconducting series reactor (SSR) as an alternative to traditionally employed technologies and superconducting fault current limiters when managing fault levels on the electrical power grid. By utilizing superconducting tape, which has negligible resistance, in the construction of a series reactor, it is proposed that fault level mitigation could be achieved in a more energy efficient manner. Once constructed the SSR will be installed and tested at a grid-connected power engineering research site, and the proposed impact of this installation is firstly simulated using Reticmaster® power system simulation software. Design parameters for the prototype SSR are then calculated enabling the total cost of the modifications and prototype SSR to be determined. A desktop SSR was also constructed and tested as a pre-cursor to the prototype construction to confirm functionality and design and was found to be up to four times more energy efficient as the equivalent copper reactor. Finally, the calorimetric method of power loss determination was investigated and experimentally shown to be a viable alternative to the traditional electrical method of power loss determination. In the past, the relatively cheap cost of electricity in South Africa had favoured the installation of poor power efficiency devices that required a lower initial capital investment. With increasing energy costs and a focus on carbon emission reductions, the development of the SSR augurs a new era in power system engineering in which designs are proposed considering both total lifecycle costs and energy efficiency. Design proposal for the first superconducting power device in Africa Alternative to less efficient fault current management technologies currently employed Construction and testing of a desktop superconducting series reactor Verification of the calorimetric method for power loss determination

Assessing the accuracy of current near infra-red reflectance spectroscopy analysis for fresh grass-clover mixture silages and development of new equations for this purpose

The purpose of this study was to ascertain whether Near Infra-Red Reflectance Spectroscopy (NIRS) prediction equations calibrated on grass silage samples, could accurately predict the chemical composition of mixed grass-clover silage samples, and furthermore, to develop and calibrate new grass-clover equations should the grass-based equations be insufficiently accurate for these silages. A set of 94 silage samples from mixed grass-clover swards (clover concentration (CC) ranging from 4 to 1000 g/kg as fed; determined manually) were analysed for chemical composition using reference laboratory techniques, in vivo digestible organic matter in the dry matter (DOMD, in sheep), and in situ degradability of dry matter and crude protein (in cows). The same samples were scanned fresh (undried and unmilled, as is standard practice for silage analysis within UK laboratories) using NIRS (at AFBI, Northern Ireland) and grass-based prediction equations applied. Predicted and observed results were compared. Of 15 chemical components that were tested for prediction accuracy, only volatile-corrected dry matter and nitrogen were well predicted (RPD values of 4.9 and 2.4 respectively, with low root mean square errors of prediction (RMSEP)). Neutral detergent fibre and DOMD showed low RPD values, however the predicted and observed datasets had no significant bias between them and were therefore also considered as fit for purpose. Variables with significant bias between predicted and observed datasets that were not considered suitably accurate included crude protein, acid detergent fibre, microbial dry matter yield and the effective degradability of protein. For many components, bias could be attributed at least in part to CC and changes in the fractionation of nutrients present. For some variables such as crude protein, grass-based equations were sufficiently accurate at low CCs but became inaccurate as CC increased, as expected. In response to inadequate prediction accuracy of certain nutrients, new grass-clover equations were calibrated using the obtained spectra. These were validated and results indicated that the grass-clover-based equations outperformed their grass-based counterparts. The adoption of new grass-clover equations, or alternatively, with further development, the use of a CC correction factor to the existing grass-based equations, is recommended for commercial laboratories offering undried and unmilled silage analysis on samples containing clover

Recent Developments in Modeling Heteroepitaxy/Heterogeneous Nucleation by Dynamical Density Functional Theory

Crystallization of supersaturated liquids usually starts by epitaxial growth or by heterogeneous nucleation on foreign surfaces. Herein, we review recent advances made in modeling heteroepitaxy and heterogeneous nucleation on flat/modulated surfaces and nanoparticles within the framework of a simple dynamical density functional theory, known as the phase-field crystal model. It will be shown that the contact angle and the nucleation barrier are nonmonotonous functions of the lattice mismatch between the substrate and the crystalline phase. In continuous cooling studies for substrates with lattice mismatch, we recover qualitatively the Matthews–Blakeslee mechanism of stress release via the misfit dislocations. The simulations performed for particle-induced freezing will be confronted with recent analytical results, exploring thus the validity range of the latter. It will be demonstrated that time-dependent studies are essential, as investigations based on equilibrium properties often cannot identify the preferred nucleation pathways. Modeling of these phenomena is essential for designing materials on the basis of controlled nucleation and/or nano-patterning

Epigenetic Dysregulation of the Drp1 Binding Partners MiD49 and MiD51 Increases Mitotic Mitochondrial Fission and Promotes Pulmonary Arterial Hypertension: Mechanistic and Therapeutic Implications

Background -Mitotic fission is increased in pulmonary arterial hypertension (PAH), a hyperproliferative, apoptosis-resistant disease. The fission mediator, dynamin related protein 1 (Drp1) must complex with adaptor proteins to cause fission. Drp1-induced fission has been therapeutically targeted in experimental PAH. Here we examine the role of two recently discovered, poorly understood, Drp1 adapter proteins, mitochondrial dynamics protein of 49 and 51 kDa (MiD49 and MiD51) in normal vascular cells and explore their dysregulation in PAH. Methods -Immunoblots of pulmonary artery smooth muscle cells (PASMC, control, n=6; PAH, n=8) and immunohistochemistry of lung sections (control, n=6; PAH, n=6) were used to assess the expression of MiD49 and MiD51. The effects of manipulating MiDs on cell proliferation, cell cycle, and apoptosis were assessed in human and rodent PAH PASMC using flow cytometry. Mitochondrial fission was studied by confocal imaging. A microRNA (miR) involved in the regulation of MiD expression was identified using microarray techniques andin silicoanalyses. The expression of circulatory miR was assessed using qRT-PCR in healthy volunteers (HV) vs PAH patients from Sheffield, UK (plasma, HV, n=29, PAH, n=27; whole blood, HV, n=11, PAH, n=14), and then confirmed in a cohort from Beijing, China (plasma, HV, n=19, PAH, n=36; whole blood, HV, n=20, PAH, n=39). This work was replicated in monocrotaline and SU5416-hypoxia, preclinical PAH models. siRNA targeting MiDs or a miR mimic were nebulized to rats with monocrotaline-induced PAH (n=4-10). Results -MiD expression is increased in PAH PASMC, which accelerates Drp1-mediated mitotic fission, increases cell proliferation and decreases apoptosis. Silencing MiDs (but not other Drp1 binding partners, Fis1 or MFF) promotes mitochondrial fusion and causes G1-phase cell cycle arrest, through ERK1/2 and CDK4-dependent mechanism. Augmenting MiDs in normal cells causes fission and recapitulates the PAH phenotype. MiD upregulation results from decreased miR-34a-3p expression. Circulatory miR-34a-3p expression is decreased in both PAH patients and in preclinical models of PAH. Silencing MiDs or augmenting miR-34a-3p regresses experimental PAH. Conclusions -In health, MiDs regulate Drp1-mediated fission whilst in disease, epigenetic upregulation of MiDs increases mitotic fission, which drives pathologic proliferation and apoptosis resistance. The miR-34a-3p-MiD pathway offers new therapeutic targets for PAH

Appraising empirical applications of Structuration Theory in management and organization studies

There is an increasing interest in the application of Structuration Theory in the fields of management and organization studies. Based upon a thorough literature review, we have come up with a data-set to assess how Structuration Theory has been used in empirical research. We use three key concepts of this theory (duality of structure, knowledgeability, and time-space) as sensitizing concepts for our analysis. We conclude that the greatest potential of Structuration Theory for management and organization studies is to view it as a process theory that offers a distinct building block for explaining intra and interorganizational change, as exemplified through concepts such as routine, script, genre, practice, and discourse

Patterns of ash (Fraxinus excelsior L.) colonization in mountain grasslands: the importance of management practices

International audienceWoody colonization of grasslands is often associated with changes in abiotic or biotic conditions or a combination of both. Widely used as fodder and litter in the past traditional agro-pastoral system, ash (Fraxinus excelsior L.) has now become a colonizing species of mountain grasslands in the French Pyrenees. Its present distribution is dependent on past human activities and it is locally controlled by propagule pressure and abiotic conditions. However, even when all favourable conditions are met, all the potentially colonizable grasslands are not invaded. We hypothesize that management practices should play a crucial role in the control of ash colonization. From empirical field surveys we have compared the botanical composition of a set of grasslands (present and former) differing in management practices and level of ash colonization. We have displayed a kind of successional gradient positively linked to both ash cover and height but not to the age of trees. We have tested the relationships between ash presence in grassland and management types i.e. cutting and/or grazing, management intensity and some grassland communities' features i.e. total and local specific richness and species heterogeneity. Mixed use (cutting and grazing) is negatively linked to ash presence in grassland whereas grazing alone positively. Mixed use and high grazing intensity are directly preventing ash seedlings establishment, when low grazing intensity is allowing ash seedlings establishment indirectly through herbaceous vegetation neglected by livestock. Our results show the existence of a limit between grasslands with and without established ashes corresponding to a threshold in the intensity of use. Under this threshold, when ash is established, the colonization process seems to become irreversible. Ash possesses the ability of compensatory growth and therefore under a high grazing intensity develops a subterranean vegetative reproduction. However the question remains at which stage of seedling development and grazing intensity these strategies could occur

Schools out : Adam Smith and pre-disciplinary international political economy

In this article, I argue that invocations of Adam Smith in international political economy (IPE) often reveal the influence therein of a disciplinary ontological disaggregation of economic and non-economic rationality, which I claim is obscured by the tendency to map its complex intellectual contours in terms of competing schools. I trace the origins of the disciplinary characterisation of Smith as the founder of IPE's liberal tradition to invocations of his thought by centrally important figures in the perceived Austrian, Chicago and German historical schools of economics, and reflect upon the significance to IPE of the reiteration of this portrayal by apparent members of its so-called American and British schools. I additionally contrast these interpretations to those put forward by scholars who seek to interpret IPE and Smith's contribution to it in pre-disciplinary terms, which I claim reflects a distinct ontology to that attributed to the British school of IPE with which their work is often associated. I therefore contend that reflection upon invocations of Smith's thought in IPE problematises the longstanding tendency to map its intellectual terrain in terms of competing schools, reveals that the disciplinary ontological consensus that informs this tendency impacts upon articulations of its core concerns and suggests that a pre-disciplinary approach offers an alternative lens through which such concerns might be more effectively framed