Probable changes in lake chemistry in Canada's Atlantic Provinces under proposed North American emission reductions

International audienceAtlantic Canada, located in the extreme north-eastern portion of North America, receives acid precipitation from all major acid emission sources on the eastern part of the continent. The region was glaciated and has thin soils over a generally poorly acid buffering bedrock. Because of regional topography, large groupings of lakes occur in a number of regions. Environment Canada and the Government of New Brunswick have operated lake sampling networks in trend detection studies and have concentrated their work on these lake groupings. The MAGIC model has been applied to these lakes and their catchments to see: a) what initial water chemistry conditions existed before acidification began, b) what the chemistry was like during the worst of regional acid deposition, and c) what it would be like under deposition conditions predicted for new Canadian and US emission reduction proposals. While pH, sulphate, acid neutralisation capacity (ANC) and the sum of the base cations (SBC) of all lakes have been significantly affected by acid deposition, water chemistry conditions are now considerably better than they were in 1975, at the worst of the deposition. However, a 50% reduction in acid deposition from Year 2000 deposition amounts will not return water chemistry to original conditions in most of the region. Keywords: Atlantic Canada, monitoring networks, acidification, predictions, MAGI

Measurement and physical interpretation of the mean motion of turbulent density patterns detected by the BES system on MAST

The mean motion of turbulent patterns detected by a two-dimensional (2D) beam emission spectroscopy (BES) diagnostic on the Mega Amp Spherical Tokamak (MAST) is determined using a cross-correlation time delay (CCTD) method. Statistical reliability of the method is studied by means of synthetic data analysis. The experimental measurements on MAST indicate that the apparent mean poloidal motion of the turbulent density patterns in the lab frame arises because the longest correlation direction of the patterns (parallel to the local background magnetic fields) is not parallel to the direction of the fastest mean plasma flows (usually toroidal when strong neutral beam injection is present). The experimental measurements are consistent with the mean motion of plasma being toroidal. The sum of all other contributions (mean poloidal plasma flow, phase velocity of the density patterns in the plasma frame, non-linear effects, etc.) to the apparent mean poloidal velocity of the density patterns is found to be negligible. These results hold in all investigated L-mode, H-mode and internal transport barrier (ITB) discharges. The one exception is a high-poloidal-beta (the ratio of the plasma pressure to the poloidal magnetic field energy density) discharge, where a large magnetic island exists. In this case BES detects very little motion. This effect is currently theoretically unexplained.Comment: 28 pages, 15 figures, submitted to PPC

A Helitron transposon reconstructed from bats reveals a novel mechanism of genome shuffling in eukaryotes

Helitron transposons capture and mobilize gene fragments in eukaryotes, but experimental evidence for their transposition is lacking in the absence of an isolated active element. Here we reconstruct Helraiser, an ancient element from the bat genome, and use this transposon as an experimental tool to unravel the mechanism of Helitron transposition. A hairpin close to the 3'-end of the transposon functions as a transposition terminator. However, the 3'-end can be bypassed by the transposase, resulting in transduction of flanking sequences to new genomic locations. Helraiser transposition generates covalently closed circular intermediates, suggestive of a replicative transposition mechanism, which provides a powerful means to disseminate captured transcriptional regulatory signals across the genome. Indeed, we document the generation of novel transcripts by Helitron promoter capture both experimentally and by transcriptome analysis in bats. Our results provide mechanistic insight into Helitron transposition, and its impact on diversification of gene function by genome shuffling

Topsoil porosity prediction across habitats at large scales using environmental variables

Soil porosity and its reciprocal bulk density are important environmental state variables that enable modelers to represent hydraulic function and carbon storage. Biotic effects and their ‘dynamic’ influence on such state variables remain largely unknown for larger scales and may result in important, yet poorly quantified environmental feedbacks. Existing representation of hydraulic function is often invariant to environmental change and may be poor in some systems, particularly non-arable soils. Here we assess predictors of total porosity across two comprehensive national topsoil (0-15 cm) data sets, covering the full range of soil organic matter (SOM) and habitats (n = 1385 & n = 2570), using generalized additive mixed models and machine learning. Novel aspects of this work include the testing of metrics on aggregate size and livestock density alongside a range of different particle size distribution metrics. We demonstrate that porosity trends in Great Britain are dominated by biotic metrics, soil carbon and land use. Incorporating these variables into porosity prediction improves performance, paving the way for new dynamic calculation of porosity using surrogate measures with remote sensing, which may help improve prediction in data sparse regions of the world. Moreover, dynamic calculation of porosity could support representation of feedbacks in environmental and Earth System Models. Representing the hydrological feedbacks from changes in structural porosity also requires data and models at appropriate spatial scales to capture conditions leading to near-saturated soil conditions

Brain function and clinical characterization in the Boston adolescent neuroimaging of depression and anxiety study

We present a Human Connectome Project study tailored toward adolescent anxiety and depression. This study is one of the first studies of the Connectomes Related to Human Diseases initiative and is collecting structural, functional, and diffusion-weighted brain imaging data from up to 225 adolescents (ages 14–17 years), 150 of whom are expected to have a current diagnosis of an anxiety and/or depressive disorder. Comprehensive clinical and neuropsychological evaluations and long-itudinal clinical data are also being collected. This article provides an overview of task functional magnetic resonance imaging (fMRI) protocols and preliminary findings (N = 140), as well as clinical and neuropsychological characterization of adolescents. Data collection is ongoing for an additional 85 adolescents, most of whom are expected to have a diagnosis of an anxiety and/or depressive disorder. Data from the first 140 adolescents are projected for public release through the National Institutes of Health Data Archive (NDA) with the timing of this manuscript. All other data will be made publicly-available through the NDA at regularly scheduled intervals. This article is intended to serve as an introduction to this project as well as a reference for those seeking to clinical, neurocognitive, and task fMRI data from this public resource

Comparison of the oxidative reactivity of recombinant fetal and adult human hemoglobin: implications for the design of hemoglobin-based oxygen carriers.

Hemoglobin based oxygen carriers (HBOCs) have been engineered to replace or augment the oxygen carrying capacity of erythrocytes. However, clinical results have generally been disappointing due, in part due to the intrinsic oxidative toxicity of hemoglobin. The most common HBOC starting material is adult human or bovine hemoglobin. However, it has been suggested that fetal hemoglobin may offer advantages due to decreased oxidative reactivity. Large scale manufacturing of a HBOC will likely ultimately require recombinant sources of human proteins. We therefore directly compared the functional properties and oxidative reactivity of recombinant fetal (rHbF) and recombinant adult (rHbA) hemoglobin. rHbA and rHbF produced similar yields of purified functional protein. No differences were seen in the two proteins in: autoxidation rate; the rate of hydrogen peroxide reaction; NO scavenging dioxygenase activity; and the NO producing nitrite reductase activity. The rHbF protein was: less damaged by low levels of hydrogen peroxide; less damaging when added to human umbilical vein endothelial cells (HUVEC) in the ferric form; and had a slower rate of intrinsic heme loss. The rHbA protein was: more readily reducible by plasma antioxidants such as ascorbate in both the reactive ferryl and ferric states; less readily damaged by lipid peroxides; and less damaging to phosphatidylcholine liposomes. In conclusion in terms of oxidative reactivity there are advantages and disadvantages to the use of recombinant adult or fetal Hb as the basis for an effective HBOC

Environment and Rural Affairs Monitoring & Modelling Programme – ERAMMP Year 1 Report 12: ‘Quick Start’ Modelling (Phase 1)

The potential impact of Brexit on the farming sector and wider environment is just one of the many challenges facing the Welsh Government. There are a range of decision and modelling tools which can be used to explore potential outcomes and the areas at risk where the environmental regulatory floor needs to be enhanced or social transition programmes put in place. The same tools can also be used to explore a range of ‘what if’ scenarios for different land management options which could be included in new Payment for Ecosystem Service (PES) schemes or in national land management payment schemes to replace CAP. To meet this challenge in Wales, a partnership between the Welsh Government, their stakeholders and a consortium of research organisations led by the Centre for Ecology and Hydrology (CEH) was formed. This partnership, called ERAMMP, (https://erammp.wales/en) combined expert knowledge and a range of decision and modelling tools to examine potential changes in agricultural land use that might result from Brexit, and to explore potential benefits of new land management options

Environment and Rural Affairs Monitoring & Modelling Programme – ERAMMP Year 1 Report 12TA1: ‘Quick Start’ Modelling (Phase 1) Technical Annex.

Farmscoper is a decision support tool that can be used to assess diffuse agricultural pollutant loads on a farm and quantify the impacts of farm mitigation methods on these pollutants. The farm systems within the tool can be customised to reflect management and environmental conditions representative of farming across England and Wales. The tool contains over 100 mitigation methods, including many of those in the latest Defra Mitigation Method User Guide