An overlooked mechanism underlying the attenuated temperature response of soil heterotrophic respiration

Biogeochemical reactions occurring in soil pore space underpin gaseous emissions measured at macroscopic scales but are difficult to quantify due to their complexity and heterogeneity. We develop a volumetric-average method to calculate aerobic respiration rates analytically from soil with microscopic soil structure represented explicitly. Soil water content in the model is the result of the volumetric-average of the microscopic processes, and it is nonlinearly coupled with temperature and other factors. Since many biogeochemical reactions are driven by oxygen (O2) which must overcome various resistances before reaching reactive microsites from the atmosphere, the volumetric-average results in negative feedback between temperature and soil respiration, with the magnitude of the feedback increasing with soil water content and substrate quality. Comparisons with various experiments show the model reproduces the variation of carbon dioxide emission from soils under different water content and temperature gradients, indicating that it captures the key microscopic processes underpinning soil respiration. We show that alongside thermal microbial adaptation, substrate heterogeneity and microbial turnover and carbon use efficiency, O2 dissolution and diffusion in water associated with soil pore space is another key explanation for the attenuated temperature response of soil respiration and should be considered in developing soil organic carbon models

Excavations and the afterlife of a professional football stadium, Peel Park, Accrington, Lancashire: towards an archaeology of football

Association football is now a multi-billion dollar global industry whose emergence spans the post-medieval to the modern world. With its professional roots in late 19th-century industrial Lancashire, stadiums built for the professionalization of football first appear in frequency in the North of England. While many historians of sport focus on consumerism and ‘topophilia’ (attachment to place) regarding these local football grounds, archaeological research that has been conducted on the spectator experience suggests status differentiation within them. Our excavations at Peel Park confirm this impression while also showing a significant afterlife to this stadium, particularly through children’s play

A comparison between water uptake and root length density in winter wheat: effects of root density and rhizosphere properties

© 2020, The Author(s). Background and aims: We aim to quantify the variation in root distribution in a set of 35 experimental wheat lines. We also compared the effect of variation in hydraulic properties of the rhizosphere on water uptake by roots. Methods: We measured the root length density and soil drying in 35 wheat lines in a field experiment. A 3D numerical model was used to predict soil drying profiles with the different root length distributions and compared with measured soil drying. The model was used to test different scenarios of the hydraulic properties of the rhizosphere. Results: We showed that wheat lines with no detectable differences in root length density can induce soil drying profiles with statistically significant differences. Our data confirmed that a root length density of at least 1cm/cm3 is needed to drain all the available water in soil. In surface layers where the root length density was far greater than 1cm/cm3 water uptake was independent of rooting density due to competition for water. However, in deeper layers where root length density was less than 1cm/cm3, water uptake by roots was proportional to root density. Conclusion: In a set of wheat lines with no detectable differences in the root length density we found significant differences in water uptake. This may be because small differences in root density at depth can result in larger differences in water uptake or that the hydraulic properties of the rhizosphere can greatly affect water uptake

Optimisation and analysis of streamwise-varying wall-normal blowing in a turbulent boundary layer

Skin-friction drag is a major engineering concern, with wide-ranging consequences across many industries. Active flow-control techniques targeted at minimising skin friction have the potential to significantly enhance aerodynamic efficiency, reduce operating costs, and assist in meeting emission targets. However, they are difficult to design and optimise. Furthermore, any performance benefits must be balanced against the input power required to drive the control. Bayesian optimisation is a technique that is ideally suited to problems with a moderate number of input dimensions and where the objective function is expensive to evaluate, such as with high-fidelity computational fluid dynamics simulations. In light of this, this work investigates the potential of low-intensity wall-normal blowing as a skin-friction drag reduction strategy for turbulent boundary layers by combining a high-order flow solver (Incompact3d) with a Bayesian optimisation framework. The optimisation campaign focuses on streamwise-varying wall-normal blowing, parameterised by a cubic spline. The inputs to be optimised are the amplitudes of the spline control points, whereas the objective function is the net-energy saving (NES), which accounts for both the skin-friction drag reduction and the input power required to drive the control (with the input power estimated from real-world data). The results of the optimisation campaign are mixed, with significant drag reduction reported but no improvement over the canonical case in terms of NES. Selected cases are chosen for further analysis and the drag reduction mechanisms and flow physics are highlighted. The results demonstrate that low-intensity wall-normal blowing is an effective strategy for skin-friction drag reduction and that Bayesian optimisation is an effective tool for optimising such strategies. Furthermore, the results show that even a minor improvement in the blowing efficiency of the device used in the present work will lead to meaningful NES

Antimicrobial activity from endophytic fungi isolated from plant leaves in Dipterocarpous forest at Viengsa district Nan province, Thailand

Eleven fungal endophytes representing different morphotaxa were characterized from 68 cultures, which were isolated from 4 species of Dipterocapous trees (Dipterocarpus tuberculatus Roxb., Shorea obtusa Wall., Shorea siamensis Miq. and Dalbergia oliveri Gamble.) growing in the Dipterocapous forest at Viengsa district, Nan province. Species of Phyllosticta spp. (15 isolates), Nodulisporium spp. (13 isolates) and Xylaria sp.1 (10 isolates) were the most frequently found. All endophytic fungal isolates were tested for potential production of bioactive metabolites. They were tested for antimicrobial activity against pathogenic microorganisms such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aerogenosa, Escherichia coli and Candida albicans by the paper disk susceptibility test. They inhibited the growth of Gram positive bacteria more than Gram negative bacteria. Candida albicans was inhibited only by Nodulissporium sp. (DT6) and Xylaria sp.1 (DO9)

Stereotactic ablative body radiotherapy for the treatment of spinal oligometastases

Abstract not availableJ.H. Chang, S. Gandhidasan, R. Finnigan, D. Whalley, R. Nair, A. Herschtal, T. Eade, A. Kneebone, J. Ruben, M. Foote, S. Siv

Early Life Socioeconomic Circumstance and Late Life Brain Hyperintensities : A Population Based Cohort Study

Funding: Image acquisition and image analysis for this study was funded by the Alzheimer's Research Trust (now Alzheimer's Research UK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Acknowledgments The authors would like to thank the participants of the Aberdeen 1936 Birth Cohort (ABC36), without whom this research would not have been possible.Peer reviewedPublisher PD

Impacts of bromine and iodine chemistry on tropospheric OH and HO2 : Comparing observations with box and global model perspectives

The chemistry of the halogen species bromine and iodine has a range of impacts on tropospheric composition, and can affect oxidising capacity in a number of ways. However, recent studies disagree on the overall sign of the impacts of halogens on the oxidising capacity of the troposphere. We present simulations of OH and HO2 radicals for comparison with observations made in the remote tropical ocean boundary layer during the Seasonal Oxidant Study at the Cape Verde Atmospheric Observatory in 2009. We use both a constrained box model, using detailed chemistry derived from the Master Chemical Mechanism (v3.2), and the three-dimensional global chemistry transport model GEOS-Chem. Both model approaches reproduce the diurnal trends in OH and HO2. Absolute observed concentrations are well reproduced by the box model but are overpredicted by the global model, potentially owing to incomplete consideration of oceanic sourced radical sinks. The two models, however, differ in the impacts of halogen chemistry. In the box model, halogen chemistry acts to increase OH concentrations (by 9.8% at midday at the Cape Verde Atmospheric Observatory), while the global model exhibits a small increase in OH at the Cape Verde Atmospheric Observatory (by 0.6% at midday) but overall shows a decrease in the global annual mass-weighted mean OH of 4.5%. These differences reflect the variety of timescales through which the halogens impact the chemical system. On short timescales, photolysis of HOBr and HOI, produced by reactions of HO2 with BrO and IO, respectively, increases the OH concentration. On longer timescales, halogen-catalysed ozone destruction cycles lead to lower primary production of OH radicals through ozone photolysis, and thus to lower OH concentrations. The global model includes more of the longer timescale responses than the constrained box model, and overall the global impact of the longer timescale response (reduced primary production due to lower O3 concentrations) overwhelms the shorter timescale response (enhanced cycling from HO2 to OH), and thus the global OH concentration decreases. The Earth system contains many such responses on a large range of timescales. This work highlights the care that needs to be taken to understand the full impact of any one process on the system as a whole

Reliably Classifying Novice Programmer Exam Responses using the SOLO Taxonomy

Abstract: Past papers of the BRACElet project have described an approach to teaching and assessing students where the students are presented with short pieces of code, and are instructed to explain, in plain English, what the code does. The student responses to these types of questions can be analysed according to the SOLO taxonomy. Some students display an understanding of the code as a single, functional whole, while other students cannot âsee the forest for the treesâ . However, classifying student responses into the taxonomy is not always straightforward. This paper analyses the reliability of the SOLO taxonomy as a means of categorising student responses. The paper derives an augmented set of SOLO categories for application to the programming domain, and proposes a set of guidelines for researchers to use