Using eddy covariance to measure the dependence of air–sea CO2 exchange rate on friction velocity

Parameterisation of the air–sea gas transfer velocity of CO2 and other trace gases under open-ocean conditions has been a focus of air–sea interaction research and is required for accurately determining ocean carbon uptake. Ships are the most widely used platform for air–sea flux measurements but the quality of the data can be compromised by airflow distortion and sensor cross-sensitivity effects. Recent improvements in the understanding of these effects have led to enhanced corrections to the shipboard eddy covariance (EC) measurements. Here, we present a revised analysis of eddy covariance measurements of air–sea CO2 and momentum fluxes from the Southern Ocean Surface Ocean Aerosol Production (SOAP) study. We show that it is possible to significantly reduce the scatter in the EC data and achieve consistency between measurements taken on station and with the ship underway. The gas transfer velocities from the EC measurements correlate better with the EC friction velocity (u*) than with mean wind speeds derived from shipboard measurements corrected with an airflow distortion model. For the observed range of wind speeds (u10 N = 3–23 m s−1), the transfer velocities can be parameterised with a linear fit to u*. The SOAP data are compared to previous gas transfer parameterisations using u10 N computed from the EC friction velocity with the drag coefficient from the Coupled Ocean–Atmosphere Response Experiment (COARE) model version 3.5. The SOAP results are consistent with previous gas transfer studies, but at high wind speeds they do not support the sharp increase in gas transfer associated with bubble-mediated transfer predicted by physically based models

Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Shipboard measurements of eddy covariance dimethylsulfide (DMS) air–sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s−1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air–sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air–sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions

Early adoption of conservation agriculture practices: Understanding partial compliance in programs with multiple adoption decisions

Land degradation and soil erosion have emerged as serious challenges to smallholder farmers throughout Southern Africa. To combat these challenges, conservation agriculture (CA) – a suite of agricultural practices consisting of zero tillage, mulching of crop residues, and intercropping with legumes – is widely promoted as a “sustainable” package of agricultural practices. Despite the many potential benefits of CA, however, adoption remains low. Yet relatively little is known about the decisionmaking process in choosing to adopt CA or any of its constituent practices. This article attempts to fill this important knowledge gap by studying CA adoption in southern Malawi. Unlike what is implicitly assumed when these packages of practices are introduced, farmers view adoption of CA as a series of separate decisions, rather than a single decision. But the adoption decisions need not be wholly independent. We find strong evidence of interrelated decisions, particularly among mulching crop residues and practicing zero tillage, suggesting that mulching residues and intercropping or rotating with legumes introduces a multiplier effect on the adoption of zero tillage

Transformative change through Payments for Ecosystem Services (PES): a conceptual framework and application to conservation agriculture in Malawi

Non-technical summary: A major challenge in addressing the loss of benefits and services provided by the natural environment is that it can be difficult to find ways for those who benefit from them to pay for their preservation. We examine one such context in Malawi, where erosion from soils disturbed by agriculture affects not only farmers’ incomes, but also damages aquatic habitat and inhibits the storage and hydropower potential of dams downstream. We demonstrate that payments from hydropower producers to farmers to maintain land cover and prevent erosion can have benefits for all parties involved. Technical summary: Payments for ecosystem services (PES) schemes provide a mechanism to connect beneficiaries of ecosystem services with those whose actions could provide them. Recent work on PES has demonstrated a priority on matching costs and benefits at the margin, where, on the whole, payments are also low. We draw on dynamic systems theory to demonstrate that reinforcing feedbacks that benefit ecosystem services producers may warrant much higher initial investments in PES programs, and provide evidence of behavioural drivers from a PES trial in Malawi to support these claims. Specifically, in our study, peer effects and improvement to soil structure are processes that can encourage adoption of sustainable land management practices, alongside or in the absence of other incentives. Under this framing, PES programs can be vehicles to shift systems between basins of attraction over a time-limited period, rather than programs necessary for long-term maintenance of services

The relationship between ocean surface turbulence and air-sea gas transfer velocity: An in-situ evaluation

Although the air-sea gas transfer velocity k is usually parameterized with wind speed, the so-called small-eddy model suggests a relationship between k and ocean surface dissipation of turbulent kinetic energy . Laboratory and field measurements of k and have shown that this model holds in various ecosystems. Here, field observations are presented supporting the theoretical model in the open ocean. These observations are based on measurements from the Air-Sea Interaction Profiler and eddy covariance CO2 and DMS air-sea flux data collected during the Knorr11 cruise. We show that the model results can be improved when applying a variable Schmidt number exponent compared to a commonly used constant value of 1/2. Scaling to the viscous sublayer allows us to investigate the model at different depths and to expand its applicability for more extensive data sets

Important steps towards a big change for lung health: a joint approach by the European Respiratory Society, the European Society of Radiology and their partners to facilitate implementation of the European Union's new recommendations on lung cancer screening.

Enormous progress has been made on the epic journey towards implementation of lung cancer screening in Europe. A breakthrough for lung health has been achieved with the EU proposal for a Council recommendation on cancer screening. https://bit.ly/3J4O0Jb

Transgenerational impact of intimate partner violence on methylation in the promoter of the glucocorticoid receptor

Prenatal exposure to maternal stress can have lifelong implications for psychological function, such as behavioral problems and even the development of mental illness. Previous research suggests that this is due to transgenerational epigenetic programming of genes operating in the hypothalamic–pituitary–adrenal axis, such as the glucocorticoid receptor (GR). However, it is not known whether intrauterine exposure to maternal stress affects the epigenetic state of these genes beyond infancy. Here, we analyze the methylation status of the GR gene in mothers and their children, at 10–19 years after birth. We combine these data with a retrospective evaluation of maternal exposure to intimate partner violence (IPV). Methylation of the mother's GR gene was not affected by IPV. For the first time, we show that methylation status of the GR gene of adolescent children is influenced by their mother's experience of IPV during pregnancy. As these sustained epigenetic modifications are established in utero, we consider this to be a plausible mechanism by which prenatal stress may program adult psychosocial function

Bacterial microevolution and the Pangenome

The comparison of multiple genome sequences sampled from a bacterial population reveals considerable diversity in both the core and the accessory parts of the pangenome. This diversity can be analysed in terms of microevolutionary events that took place since the genomes shared a common ancestor, especially deletion, duplication, and recombination. We review the basic modelling ingredients used implicitly or explicitly when performing such a pangenome analysis. In particular, we describe a basic neutral phylogenetic framework of bacterial pangenome microevolution, which is not incompatible with evaluating the role of natural selection. We survey the different ways in which pangenome data is summarised in order to be included in microevolutionary models, as well as the main methodological approaches that have been proposed to reconstruct pangenome microevolutionary history

Evidence for niche adaptation in the genome of the bovine pathogen Streptococcus uberis.

BACKGROUND: Streptococcus uberis, a Gram positive bacterial pathogen responsible for a significant proportion of bovine mastitis in commercial dairy herds, colonises multiple body sites of the cow including the gut, genital tract and mammary gland. Comparative analysis of the complete genome sequence of S. uberis strain 0140J was undertaken to help elucidate the biology of this effective bovine pathogen. RESULTS: The genome revealed 1,825 predicted coding sequences (CDSs) of which 62 were identified as pseudogenes or gene fragments. Comparisons with related pyogenic streptococci identified a conserved core (40%) of orthologous CDSs. Intriguingly, S. uberis 0140J displayed a lower number of mobile genetic elements when compared with other pyogenic streptococci, however bacteriophage-derived islands and a putative genomic island were identified. Comparative genomics analysis revealed most similarity to the genomes of Streptococcus agalactiae and Streptococcus equi subsp. zooepidemicus. In contrast, streptococcal orthologs were not identified for 11% of the CDSs, indicating either unique retention of ancestral sequence, or acquisition of sequence from alternative sources. Functions including transport, catabolism, regulation and CDSs encoding cell envelope proteins were over-represented in this unique gene set; a limited array of putative virulence CDSs were identified. CONCLUSION: S. uberis utilises nutritional flexibility derived from a diversity of metabolic options to successfully occupy a discrete ecological niche. The features observed in S. uberis are strongly suggestive of an opportunistic pathogen adapted to challenging and changing environmental parameters.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Transformation of the rodent malaria parasite Plasmodium chabaudi and generation of a stable fluorescent line PcGFPCON

<p>Abstract</p> <p>Background</p> <p>The rodent malaria parasite <it>Plasmodium chabaudi </it>has proven of great value in the analysis of fundamental aspects of host-parasite-vector interactions implicated in disease pathology and parasite evolutionary ecology. However, the lack of gene modification technologies for this model has precluded more direct functional studies.</p> <p>Methods</p> <p>The development of <it>in vitro </it>culture methods to yield <it>P. chabaudi </it>schizonts for transfection and conditions for genetic modification of this rodent malaria model are reported.</p> <p>Results</p> <p>Independent <it>P. chabaudi </it>gene-integrant lines that constitutively express high levels of green fluorescent protein throughout their life cycle have been generated.</p> <p>Conclusion</p> <p>Genetic modification of <it>P. chabaudi </it>is now possible. The production of genetically distinct reference lines offers substantial advances to our understanding of malaria parasite biology, especially interactions with the immune system during chronic infection.</p