...some refugees and migrants are travelling from countries not yet substantially affected by COVID-19 and entering countries with increasing numbers of COVID-19 cases. The ability to access ...health-care services in humanitarian settings is usually compromised and exacerbated by shortages of medicines and lack of health-care facilities. ...refugees typically face administrative, financial, legal, and language barriers to access the health system.4 Conditions in refugee camps are concerning. There must be no forced returns and refoulement justified by or based on fears or suspicion of COVID-19 transmission, especially because there is estimated to be low risk of transmitting communicable disease from refugee and migrant populations to host populations in the WHO European region.4 Yet migrants and refugees are often stigmatised and unjustly discriminated against for spreading disease and such unacceptable attitudes further risk wider public health outcomes, including for host populations, since refugees and migrants could be fearful to seek treatment or disclose symptoms.6 Refugees and migrants must be included in national public health systems, with no risk of financial or legal consequences for them.
Methanogenic archaea in peatlands L. Bräuer, Suzanna; Basiliko, Nathan; M. P. Siljanen, Henri ...
FEMS microbiology letters,
10/2020, Volume:
367, Issue:
20
Journal Article
Peer reviewed
Open access
ABSTRACT
Methane emission feedbacks in wetlands are predicted to influence global climate under climate change and other anthropogenic stressors. Herein, we review the taxonomy and physiological ...ecology of the microorganisms responsible for methane production in peatlands. Common in peat soils are five of the eight described orders of methanogens spanning three phyla (Euryarchaeota, Halobacterota and Thermoplasmatota). The phylogenetic affiliation of sequences found in peat suggest that members of the thus-far-uncultivated group Candidatus Bathyarchaeota (representing a fourth phylum) may be involved in methane cycling, either anaerobic oxidation of methane and/or methanogenesis, as at least a few organisms within this group contain the essential gene, mcrA, according to metagenomic data. Methanogens in peatlands are notoriously challenging to enrich and isolate; thus, much remains unknown about their physiology and how methanogen communities will respond to environmental changes. Consistent patterns of changes in methanogen communities have been reported across studies in permafrost peatland thaw where the resulting degraded feature is thermokarst. However much remains to be understood regarding methanogen community feedbacks to altered hydrology and warming in other contexts, enhanced atmospheric pollution (N, S and metals) loading and direct anthropogenic disturbances to peatlands like drainage, horticultural peat extraction, forestry and agriculture, as well as post-disturbance reclamation.
Peat-forming wetlands and peatland microorganisms that produce the greenhouse gas methane.
Multiagent navigation systems present opportunities for many applications due to their agility and cooperation. In any multiagent navigation system, it is critical that actual interagent collisions ...are strictly prevented. In this article, we present a solution to the 2-D multiagent navigation problem with collision avoidance. Our solution to this problem is based on a novel extension to Gauss's principle of least constraint (GPLC), in which a fixed set of strict equality constraints is replaced by time-varying sets of active inequality constraints. To the best of our knowledge, this is the first instance that extends GPLC with dynamic incorporation and stabilization of active inequality constraints and with actuator delay and saturation. Herein, the dynamics of a collision-free multiagent system satisfies the Karush-Kuhn-Tucker conditions. Active inequality constraints enforce collision avoidance, leader following, and agglomeration behaviors, and they are stabilized using Baumgarte's error stabilization approach. We show that in dense configurations, the positional arrangement of the agents can lead to linearly dependent constraints, and we propose specialized solutions involving QR decomposition and regularization. The efficacy and efficiency of the proposed method are demonstrated by a dimensional analysis of a worst-case scenario and numerical studies of up to 100 agents tracking a prescribed virtual leader.
A voltammetric biosensor for Ara h 6 (a peanut allergen) detection in food samples was developed. Gold nanoparticle-modified screen-printed carbon electrodes were used to develop a sandwich-type ...immunoassay using two-monoclonal antibodies. The antibody-antigen interaction was detected through the electrochemical detection of enzymatically deposited silver. The immunosensor presented a linear range between 1 and 100 ng/ml, as well as high precision (inter-day RSD ≤9.8 %) and accuracy (recoveries ≥96.7 %). The detection and quantification limits were 0.27 and 0.88 ng/ml, respectively. It was possible to detect small levels of Ara h 6 in complex food matrices.
The performance of symmetric Mach-Zehnder interferometric ( MZI ) sensor employing ring-resonator circuits for slow-light enhancement of the sensor performance was theoretically investigated. The ...slow-light structures considered in this study are coupled-resonator optical waveguide ( CROW ), four-port single ring-resonator ( FPRR ), and two-port single ring-resonator ( TPRR ) circuits. The performance of the sensors was quantitatively formulated for resolution of refractive index of measurand and figure of merit ( FoM ) with respect to similar MZI without employing slow-light structure. The effect of attenuation constant of mode traveling in the ring-resonator to the theoretical ultimate sensor resolution limited by available insertion loss budget was also discussed. Taking realistic ring attenuation constant of 1 dB/cm, ring radius of 300 μm, and 20 dB insertion loss budget, the theoretical ultimate sensing performance using a single-resonator TPRR can reach resolution of 3.63E-10 RIU which is 5 times better than single-resonator FPRR and 3-resonator CROW while giving FoM of 5 and 15 times better compared to circuit employing FPRR and 3-resonator CROW , respectively.
Tropical scleractinian corals support a diverse assemblage of microbial symbionts. This 'microbiome' possesses the requisite functional diversity to conduct a range of nitrogen (N) transformations ...including denitrification, nitrification, nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA). Very little direct evidence has been presented to date verifying that these processes are active within tropical corals. Here we use a combination of stable isotope techniques, nutrient uptake calculations and captured metagenomics to quantify rates of nitrogen cycling processes in a selection of tropical scleractinian corals. Denitrification activity was detected in all species, albeit with very low rates, signifying limited importance in holobiont N removal. Relatively greater nitrogen fixation activity confirms that corals are net N importers to reef systems. Low net nitrification activity suggests limited N regeneration capacity; however substantial gross nitrification activity may be concealed through nitrate consumption. Based on nrfA gene abundance and measured inorganic N fluxes, we calculated significant DNRA activity in the studied corals, which has important implications for coral reef N cycling and warrants more targeted investigation. Through the quantification and characterisation of all relevant N-cycling processes, this study provides clarity on the subject of tropical coral-associated biogeochemical N-cycling.
Solar radio emissions are electromagnetic waves emitted in the solar wind as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as interplanetary coronal ...mass ejections. Different physical mechanisms have been suggested to describe their origin. A good understanding of the emission process would enable to infer the kinetic energy transferred from accelerated electrons to radio waves. Even if the electrostatic case has been extensively studied, full electromagnetic simulations were attempted only recently. In this work, we report large‐scale 2D3V electromagnetic particle‐in‐cell simulations that enable to identify the generation of both electrostatic and electromagnetic waves originated by a succession of plasma instabilities. They confirm that an efficient mechanism to generate solar radio emissions close to T2f, the harmonic of the plasma frequency, is a multistage model based on a succession of nonlinear three‐wave interaction processes. Through a parametric study of the electron beam parameters, we show that (i) the global efficiency of the multistep conversion mechanism from the electron beam kinetic energy to the T2f radio wave is independent of the beam parameters, approximately 10−5 in all tested configurations, while (ii) the directivity of the electromagnetic radio wave strongly depends on the origin electron beam. Those results represent a step forward toward the use of solar wind radio emissions, observed remotely, as a diagnostic for the properties of the electron beam located at the source of the radio emission, and therefore to eventually better characterize remotely electron acceleration mechanisms in space regions not directly accessible to in situ measurements.
Key Points
We single out the successive steps of the generation mechanisms of solar radio emissions
We quantify the energy transferred from energetic particles to radio waves and show it is independent of energetic particles parameters
We identify the directivity of the radio emissions and show its strong dependence on energetic particles parameters.
The ever-increasing presence of contaminants in environmental waters is an alarming issue, not only because of their harmful effects in the environment but also because of their risk to human health. ...Pharmaceuticals and pesticides, among other compounds of daily use, such as personal care products or plasticisers, are being released into water bodies. This release mainly occurs through wastewater since the treatments applied in many wastewater treatment plants are not able to completely remove these substances. Therefore, the analysis of these contaminants is essential but this is difficult due to the great variety of contaminating substances. Facing this analytical challenge, electrochemical sensing based on molecularly imprinted polymers (MIPs) has become an interesting field for environmental monitoring. Benefiting from their superior chemical and physical stability, low-cost production, high selectivity and rapid response, MIPs combined with miniaturized electrochemical transducers offer the possibility to detect target analytes in-situ. In most reports, the construction of these sensors include nanomaterials to improve their analytical characteristics, especially their sensitivity. Moreover, these sensors have been successfully applied in real water samples without the need of laborious pre-treatment steps. This review provides a general overview of electrochemical MIP-based sensors that have been reported for the detection of pharmaceuticals, pesticides, heavy metals and other contaminants in water samples in the past decade. Special attention is given to the construction of the sensors, including different functional monomers, sensing platforms and materials employed to achieve the best sensitivity. Additionally, several parameters, such as the limit of detection, the linear concentration range and the type of water samples that were analysed are compiled.
Display omitted
•Contaminant analysis faces great challenges because of their variety and levels.•Advantages of MIPs as recognition elements: low-cost, robustness, reusability.•Main inconvenient of MIP-based sensors for environmental analysis: sensitivity.•Discussion of MIP-based electrochemical sensors for environmental analysis.•Discussion of advances and trends in MIP-based electrochemical sensors.
An electrochemical magnetic immunosensing strategy was developed for the determination of HER2-ECD, a breast cancer biomarker, and breast cancer cells in human serum. A sandwich assay was performed ...on carboxylic acid-functionalized magnetic beads (MBs) using a screen-printed carbon electrode (SPCE) as transducer surface. The affinity process was detected using electroactive labels; core/shell streptavidin-modified CdSe@ZnS Quantum Dots (QDs). Cd
2+
ions, released from the QDs, were determined by differential pulse anodic stripping voltammetry (DPASV). An assay time of 90 min, with an actual hands-on time of about 20 min, a linear range between 0.50–50 ng·mL
−1
of HER2-ECD and a limit of detection of 0.29 ng·mL
−1
were achieved. Analysis of live breast cancer cells was also performed using the optimized assay. Breast cancer cell lines SK-BR-3 (a HER2-positive cell line), MDA-MB-231 (a HER2-negative cell line) and MCF-7 (a cell line with low HER2 expression) were tested. The selectivity of the assay towards SK-BR-3 cells was confirmed. A concentration-dependent signal that was 12.5× higher than the signal obtained for the HER2-negative cells (MDA-MB-231) and a limit of detection of 2 cells·mL
−1
was obtained.
Graphical abstract
Schematic representation of the electrochemical immunomagnetic assay for the determination of the breast cancer biomarker HER2-ECD and cancer cells using magnetic beads (MBs), a screen-printed carbon electrode (SPCE) as transducer surface and quantum dots (QD) as electroactive labels.
PDF
