Climate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change. Here, we use a global synthesis (n = 9,404) to reveal ...the drivers of dissolved organic carbon (DOC), which is an important component of water chemistry and substrate for microorganisms that control biogeochemical reactions. Dissolved inorganic chemistry, local climate and land use explained ~ 31% of observed variability in groundwater DOC, whilst aquifer age explained an additional 16%. We identify a 19% increase in DOC associated with urban land cover. We predict major groundwater DOC increases following changes in precipitation and temperature in key areas relying on groundwater. Climate change and conversion of natural or agricultural areas to urban areas will decrease groundwater quality and increase water treatment costs, compounding existing constraints on groundwater resources.
Donation after circulatory death (DCD) offers a potential additional source of cardiac allografts. We used a porcine asphyxia model to evaluate viability of DCD hearts subjected to warm ischemic ...times (WIT) of 20–40 min prior to flushing with Celsior (C) solution. We then assessed potential benefits of supplementing C with erythropoietin, glyceryl trinitrate and zoniporide (Cs), a combination that we have shown previously to activate ischemic postconditioning pathways. Hearts flushed with C/Cs were assessed for functional, biochemical and metabolic recovery on an ex vivo working heart apparatus. Hearts exposed to 20‐min WIT showed full recovery of functional and metabolic profiles compared with control hearts (no WIT). Hearts subjected to 30‐ or 40‐min WIT prior to C solution showed partial and no recovery, respectively. Hearts exposed to 30‐min WIT and Cs solution displayed complete recovery, while hearts exposed to 40‐min WIT and Cs solution demonstrated partial recovery. We conclude that DCD hearts flushed with C solution demonstrate complete recovery up to 20‐min WIT after which there is rapid loss of viability. Cs extends the limit of WIT tolerability to 30 min. DCD hearts with ≤30‐min WIT may be suitable for transplantation and warrant assessment in a transplant model.
In this study of cardiac donation after circulatory death, supplementation of cardioplegic flush solution with a combination of erythropoietin, glyceryl trinitrate, and zoniporide significantly extends the tolerability of the porcine heart to warm ischemia following withdrawal of life support. See online supporting information for supplemental video content.
The negative effect of increasing atmospheric nitrogen (N) pollution on grassland biodiversity is now incontrovertible. However, the recent introduction of cleaner technologies in the UK has led to ...reductions in the emissions of nitrogen oxides, with concomitant decreases in N deposition. The degree to which grassland biodiversity can be expected to 'bounce back' in response to these improvements in air quality is uncertain, with a suggestion that long-term chronic N addition may lead to an alternative low biodiversity state. Here we present evidence from the 160-year-old Park Grass Experiment at Rothamsted Research, UK, that shows a positive response of biodiversity to reducing N addition from either atmospheric pollution or fertilizers. The proportion of legumes, species richness and diversity increased across the experiment between 1991 and 2012 as both wet and dry N deposition declined. Plots that stopped receiving inorganic N fertilizer in 1989 recovered much of the diversity that had been lost, especially if limed. There was no evidence that chronic N addition has resulted in an alternative low biodiversity state on the Park Grass plots, except where there has been extreme acidification, although it is likely that the recovery of plant communities has been facilitated by the twice-yearly mowing and removal of biomass. This may also explain why a comparable response of plant communities to reduced N inputs has yet to be observed in the wider landscape.
The creation and disruption of inertially collimated plasma flows are investigated through experiment, simulation, and analytical modeling. Supersonic plasma jets are generated by laser-irradiated ...plastic cones and characterized by optical interferometry measurements. Targets are magnetized with a tunable B field with strengths of up to 5 T directed along the axis of jet propagation. These experiments demonstrate a hitherto unobserved phenomenon in the laboratory, the magnetic disruption of inertially confined plasma jets. This occurs due to flux compression on axis during jet formation and can be described using a Lagrangian-cylinder model of plasma evolution implementing finite resistivity. The basic physical mechanisms driving the dynamics of these systems are described by this model and then compared with two-dimensional radiation-magnetohydrodynamic simulations. Experimental, computational, and analytical results discussed herein suggest that contemporary models underestimate the electrical conductivity necessary to drive the amount of flux compression needed to explain observations of jet disruption.
The sequestration in soil of organic carbon (SOC) derived from atmospheric carbon dioxide (CO2) by replacing arable crops with leys, has been measured over 70 years on a sandy loam soil. The ...experiment was designed initially to test the effect of leys on the yields of arable crops. A 3‐year grazed grass with clover (grass + clover) ley in a 5‐year rotation with arable crops increased percentage organic carbon (%OC) in the top 25 cm of the soil from 0.98 to 1.23 in 28 years, but with little further increase during the next 40 years with all‐grass leys given fertilizer nitrogen (N). In this second period, OC inputs were balanced by losses, suggesting that about 1.3% OC might be near the equilibrium content for this rotation. Including 3‐year lucerne (Medicago sativa) leys had little effect on %OC over 28 years, but after changing to grass + clover leys, %OC increased to 1.24 during the next 40 years. Eight‐year leys (all grass with N or grass + clover) in 10‐year rotations with arable crops were started in the 1970s, and after three rotations %OC had increased to ca. 1.40 in 2000–2009. Over 70 years, %OC declined from 0.98 to 0.94 in an all‐arable rotation with mainly cereals and to 0.82 with more root crops. Applications of 38 t ha−1 farmyard manure (FYM) every fifth year increased %OC by 0.13% by the mid‐1960s when applications ceased. Soil treated with FYM still contained 0.10% more OC in 2000–2009. Changes in the amount of OC have been modelled with RothC‐26.3 and estimated inputs of C for selected rotations. Little of the OC input during the 70 years has been retained; most was retained in the grazed ley rotation, but 9 t ha−1 only of a total input of 189 t ha−1. In other rotations more than 98% of the total OC input was lost. Despite large losses of C, annual increases in OC of 4‰ are possible on this soil type with the inclusion of grass or grass + clover leys or the application of FYM, but only for a limited period. Such increases in SOC might help to limit increases in atmospheric CO2.
Highlights
Can leys sequester significant amounts of atmospheric CO2 in SOM and contribute to the 4‰ initiative?
Changes in the percentage and amount of OC were measured and modelled over 70 years and OC losses estimated.
Three‐year grass or grass + clover leys increased %OC, but only to an equilibrium level that was then maintained.
Despite large losses, sequestering CO2‐C at 4‰ year−1 by growing grass or grass + clover leys is possible.
X-ray1, 2, 3 and radio4, 5, 6 observations of the supernova remnant Cassiopeia A reveal the presence of magnetic fields about 100 times stronger than those in the surrounding interstellar medium. ...Field coincident with the outer shock probably arises through a nonlinear feedback process involving cosmic rays2, 7, 8. The origin of the large magnetic field in the interior of the remnant is less clear but it is presumably stretched and amplified by turbulent motions. Turbulence may be generated by hydrodynamic instability at the contact discontinuity between the supernova ejecta and the circumstellar gas9. However, optical observations of Cassiopeia A indicate that the ejecta are interacting with a highly inhomogeneous, dense circumstellar cloud bank formed before the supernova explosion10, 11, 12. Here we investigate the possibility that turbulent amplification is induced when the outer shock overtakes dense clumps in the ambient medium13, 14, 15. We report laboratory experiments that indicate the magnetic field is amplified when the shock interacts with a plastic grid. We show that our experimental results can explain the observed synchrotron emission in the interior of the remnant. The experiment also provides a laboratory example of magnetic field amplification by turbulence in plasmas, a physical process thought to occur in many astrophysical phenomena.
Schistosomiasis is a parasitic disease affecting over 200 million people in multiple organs, including the lungs. Despite this, there is little understanding of pulmonary immune responses during ...schistosomiasis. Here, we show type-2 dominated lung immune responses in both patent (egg producing) and pre-patent (larval lung migration) murine Schistosoma mansoni (S. mansoni) infection. Human pre-patent S. mansoni infection pulmonary (sputum) samples revealed a mixed type-1/type-2 inflammatory cytokine profile, whilst a case-control study showed no significant pulmonary cytokine changes in endemic patent infection. However, schistosomiasis induced expansion of pulmonary type-2 conventional dendritic cells (cDC2s) in human and murine hosts, at both infection stages. Further, cDC2s were required for type-2 pulmonary inflammation in murine pre-patent or patent infection. These data elevate our fundamental understanding of pulmonary immune responses during schistosomiasis, which may be important for future vaccine design, as well as for understanding links between schistosomiasis and other lung diseases.
The shortage of donors in cardiac transplantation may be alleviated by the use of allografts from donation after circulatory death (DCD) donors. We have previously shown that hearts exposed to 30 min ...warm ischemic time and then flushed with Celsior supplemented with agents that activate ischemic postconditioning pathways, show complete recovery on a blood‐perfused ex vivo working heart apparatus. In this study, these findings were assessed in a porcine orthotopic heart transplant model. DCD hearts were preserved with either normothermic ex vivo perfusion (NEVP) using a clinically approved device, or with standard cold storage (CS) for 4 h. Orthotopic transplantation into recipient animals was subsequently undertaken. Five of six hearts preserved with NEVP demonstrated favorable lactate profiles during NEVP and all five could be weaned off cardiopulmonary bypass posttransplant, compared with 0 of 3 hearts preserved with CS (p < 0.05, Fisher's exact test). In conclusion, DCD hearts flushed with supplemented Celsior solution and preserved with NEVP display viability before and after transplantation. Viability studies of human DCD hearts using NEVP are warranted.
In this pig study of heart transplantation from donors after circulatory death, the authors demonstrate that normothermic ex vivo perfusion enables assessment of the viability of the donor heart and provides superior preservation compared with cold storage.
The application of calcium- and magnesium-rich materials to soil, known as liming, has long been a foundation of many agro-ecosystems worldwide because of its role in counteracting soil acidity. ...Although liming contributes to increased rates of respiration from soil thereby potentially reducing soils ability to act as a CO₂ sink, the long-term effects of liming on soil organic carbon (Corg) sequestration are largely unknown. Here, using data spanning 129 years of the Park Grass Experiment at Rothamsted (UK), we show net Corg sequestration measured in the 0-23 cm layer at different time intervals since 1876 was 2-20 times greater in limed than in unlimed soils. The main cause of this large Corg accrual was greater biological activity in limed soils, which despite increasing soil respiration rates, led to plant C inputs being processed and incorporated into resistant soil organo-mineral pools. Limed organo-mineral soils showed: (1) greater Corg content for similar plant productivity levels (i.e. hay yields); (2) higher ¹⁴C incorporation after 1950s atomic bomb testing and (3) lower C : N ratios than unlimed organo-mineral soils, which also indicate higher microbial processing of plant C. Our results show that greater Corg sequestration in limed soils strongly reduced the global warming potential of long-term liming to permanent grassland suggesting the net contribution of agricultural liming to global warming could be lower than previously estimated. Our study demonstrates that liming might prove to be an effective mitigation strategy, especially because liming applications can be associated with a reduced use of nitrogen fertilizer which is a key cause for increased greenhouse gas emissions from agro-ecosystems.
Competitive bacteria-bacteriophage interactions have resulted in the evolution of a plethora of bacterial defense systems preventing phage propagation. In recent years, computational and ...bioinformatic approaches have underpinned the discovery of numerous novel bacterial defense systems. Anti-phage systems are frequently encoded together in genomic loci termed defense islands. Here we report the identification and characterisation of a novel anti-phage system, that we have termed Shield, which forms part of the Pseudomonas defensive arsenal. The Shield system comprises the core component ShdA, a membrane-bound protein harboring an RmuC domain. Heterologous production of ShdA alone is sufficient to mediate bacterial immunity against several phages. We demonstrate that Shield and ShdA confer population-level immunity and that they can also decrease transformation efficiency. We further show that ShdA homologues can degrade DNA in vitro and, when expressed in a heterologous host, can alter the organisation of the host chromosomal DNA. Use of comparative genomic approaches identified how Shield can be divided into four subtypes, three of which contain additional components that in some cases can negatively affect the activity of ShdA and/or provide additional lines of phage defense. Collectively, our results identify a new player within the Pseudomonas bacterial immunity arsenal that displays a novel mechanism of protection, and reveals a role for RmuC domains in phage defense.
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