15 research outputs found
Controls on zooplankton methane production in the central Baltic Sea
Several methanogenic
pathways in oxic surface waters were recently discovered, but their relevance
in the natural environment is still unknown. Our study examines distinct
methane (CH4) enrichments that repeatedly occur below the thermocline during the
summer months in the central Baltic Sea. In agreement with previous studies
in this region, we discovered differences in the methane distributions
between the western and eastern Gotland Basin, pointing to in situ methane
production below the thermocline in the latter (concentration of CH4 14.1±6.1 nM, δ13C CH4 −62.9 ‰). Through
the use of a high-resolution hydrographic model of the Baltic Sea, we showed
that methane below the thermocline can be transported by upwelling events
towards the sea surface, thus contributing to the methane flux at the
sea–air interface. To quantify zooplankton-associated methane production
rates, we developed a sea-going methane stripping-oxidation line to determine
methane release rates from copepods grazing on 14C-labelled
phytoplankton. We found that (1)Â methane production increased with the number
of copepods, (2)Â higher methane production rates were measured in incubations
with Temora longicornis (125±49 fmol methane copepod−1 d−1) than in incubations with
Acartia spp. (84±19 fmol CH4 copepod−1 d−1) dominated zooplankton
communities, and (3)Â methane was only produced on a Rhodomonas sp.
diet, and not on a cyanobacteria diet. Furthermore, copepod-specific methane
production rates increased with incubation time. The latter finding suggests
that methanogenic substrates for water-dwelling microbes are released by cell
disruption during feeding, defecation, or diffusion from fecal pellets. In
the field, particularly high methane concentrations coincided with stations
showing a high abundance of DMSP/DMSO-rich Dinophyceae. Lipid biomarkers extracted
from phytoplankton- and copepod-rich samples revealed that Dinophyceae are a
major food source of the T. longicornis dominated zooplankton
community, supporting the proposed link between copepod grazing, DMSP/DMSO
release, and the build-up of subthermocline methane enrichments in the
central Baltic Sea.</p
COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing
Background
Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour.
Methods
LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces).
Findings
4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3).
Interpretation
Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission.
Funding
Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research
Gender and Diastolic Dysfunction May be the Driver of Failure of Myocardial Recovery Following LVAD Implantation
The role of multidetector CT angiography in characterizing vascular compression syndromes of the abdomen
Assessment of Surface-Layer Coherent Structure Detection in Dual-Doppler Lidar Data Based on Virtual Measurements
Data from: Dynamics of deep soil carbon - insights from 14C time series across a climatic gradient
Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest, as it represents large stocks and its turnover times remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ~1-9 °C) gradient are determined using time-series (~20 years) 14C data from bulk soil and water-extractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last two decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. Turnover time estimates of both the bulk and WEOC pool show that the latter cycles up to a magnitude faster than the former. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning WEOC pool across the climatic gradient implies that there likely is a dynamic component of carbon in the deep soil. Precipitation and bedrock type appear to exert a stronger influence on soil C turnover time and stocks as compared to temperature