Phosphorus losses from land to water will be impacted by climate change and land management for food production, with detrimental impacts on aquatic ecosystems. Here we use a unique combination of ...methods to evaluate the impact of projected climate change on future phosphorus transfers, and to assess what scale of agricultural change would be needed to mitigate these transfers. We combine novel high-frequency phosphorus flux data from three representative catchments across the UK, a new high-spatial resolution climate model, uncertainty estimates from an ensemble of future climate simulations, two phosphorus transfer models of contrasting complexity and a simplified representation of the potential intensification of agriculture based on expert elicitation from land managers. We show that the effect of climate change on average winter phosphorus loads (predicted increase up to 30% by 2050s) will be limited only by large-scale agricultural changes (e.g., 20-80% reduction in phosphorus inputs).The impact of climate change on phosphorus (P) loss from land to water is unclear. Here, the authors use P flux data, climate simulations and P transfer models to show that only large scale agricultural change will limit the effect of climate change on average winter P loads in three catchments across the UK.
We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the ...first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km2) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target controllable risk factors, such as soil nutrient status, soil condition and crop cover.
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•Climate change may increase pollutant transfers from agricultural land.•High temporal resolution data enabled present day nutrient dynamics to be analysed.•High flow events (>Q10) transported >90% of sediment, >80% of phosphorus•Longer periods of low flow and high concentration will increase ecological risk.•Average phosphorus loads may increase by 9% with higher rainfall volume and intensity.
To achieve a deeper understanding of the brain, scientists, and clinicians use electroencephalography (EEG) and magnetoencephalography (MEG) inverse methods to reconstruct sources in the cortical ...sheet of the human brain. The influence of structural and electrical anisotropy in both the skull and the white matter on the EEG and MEG source reconstruction is not well understood.
In this paper, we report on a study of the sensitivity to tissue anisotropy of the EEG/MEG forward problem for deep and superficial neocortical sources with differing orientation components in an anatomically accurate model of the human head.
The goal of the study was to gain insight into the effect of anisotropy of skull and white matter conductivity through the visualization of field distributions, isopotential surfaces, and return current flow and through statistical error measures. One implicit premise of the study is that factors that affect the accuracy of the forward solution will have at least as strong an influence over solutions to the associated inverse problem.
Major findings of the study include (1) anisotropic white matter conductivity causes return currents to flow in directions parallel to the white matter fiber tracts; (2) skull anisotropy has a smearing effect on the forward potential computation; and (3) the deeper a source lies and the more it is surrounded by anisotropic tissue, the larger the influence of this anisotropy on the resulting electric and magnetic fields. Therefore, for the EEG, the presence of tissue anisotropy both for the skull and white matter compartment substantially compromises the forward potential computation and as a consequence, the inverse source reconstruction. In contrast, for the MEG, only the anisotropy of the white matter compartment has a significant effect. Finally, return currents with high amplitudes were found in the highly conducting cerebrospinal fluid compartment, underscoring the need for accurate modeling of this space.
We compare multi-epoch sub-arcsecond Very Large Array imaging of the 22 GHz water masers toward the massive protocluster NGC 6334I observed before and after the recent outburst of MM1B in ...(sub)millimeter continuum. Since the outburst, the water maser emission toward MM1 has substantially weakened. Simultaneously, the strong water masers associated with the synchrotron continuum point source CM2 have flared by a mean factor of 6.5 (to 4.2 kJy) with highly blueshifted features (up to 70 km s−1 from the LSR) becoming more prominent. The strongest flaring water masers reside 3000 au north of MM1B and form a remarkable bow shock pattern whose vertex coincides with CM2 and tail points back to MM1B. Excited OH masers trace a secondary bow shock located ∼120 au downstream. Atacama Large Millimeter Array images of CS (6-5) reveal a highly collimated north-south structure encompassing the flaring masers to the north and the nonflaring masers to the south seen in projection toward the MM3-UCHII region. Proper motions of the southern water masers over 5.3 years indicate a bulk projected motion of 117 km s−1 southward from MM1B with a dynamical time of 170 years. We conclude that CM2, the water masers, and many of the excited OH masers trace the interaction of the high-velocity bipolar outflow from MM1B with ambient molecular gas. The previously excavated outflow cavity has apparently allowed the radiative energy of the current outburst to propagate freely until terminating at the northern bow shock where it strengthened the masers. Additionally, water masers have been detected toward MM7 for the first time, and a highly collimated CS (6-5) outflow has been detected toward MM4.
The central vision-threatening event in glaucoma is dysfunction and loss of retinal ganglion cells (RGCs), thought to be promoted by local tissue deformations. Here, we sought to reduce tissue ...deformation near the optic nerve head by selectively stiffening the peripapillary sclera, i.e. the scleral region immediately adjacent to the optic nerve head. Previous scleral stiffening studies to treat glaucoma or myopia have used either pan-scleral stiffening (not regionally selective) or regionally selective stiffening with limited access to the posterior globe. We present a method for selectively stiffening the peripapillary sclera using a transpupillary annular light beam to activate methylene blue administered by retrobulbar injection. Unlike prior approaches to photocrosslinking in the eye, this approach avoids the damaging effects of ultraviolet light by employing red light. This targeted photocrosslinking approach successfully stiffened the peripapillary sclera at 6 weeks post-treatment, as measured by whole globe inflation testing. Specifically, strain was reduced by 47% when comparing treated vs. untreated sclera within the same eye (n = 7, p=0.0064) and by 54% when comparing the peripapillary sclera of treated vs. untreated eyes (n = 7, p<0.0001). Post-treatment characterization of RGCs (optic nerve axon counts/density, and grading), retinal function (electroretinography), and retinal histology revealed that photocrosslinking was associated with some ocular toxicity. We conclude that a transpupillary photocrosslinking approach enables selective scleral stiffening targeted to the peripapillary region that may be useful in future treatments of glaucoma.
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•Localized stiffening of the posterior eye may be a treatment strategy for glaucoma and myopia.•We sought to photocrosslink scleral collagen, using methylene blue as a photoinitiator, in vivo.•We stiffened an annular region around the optic nerve with a transpupillary red light beam.•Moderate treatment toxicity was identified using axon counts, histology, and electroretinography.
We present (sub)millimeter imaging at 0 5 resolution of the massive star-forming region G358.93−0.03 acquired in multiple epochs at 2 and 3 months following the recent flaring of its 6.7 GHz CH3OH ...maser emission. Using the Submillimeter Array and Atacama Large Millimeter/submillimeter Array, we have discovered 14 new Class II CH3OH maser lines ranging in frequency from 199 to 361 GHz, which originate mostly from = 1 torsionally excited transitions and include one = 2 transition. The latter detection provides the first observational evidence that Class II maser pumping involves levels in the = 2 state. The masers are associated with the brightest continuum source (MM1), which hosts a line-rich hot core. The masers present a consistent curvilinear spatial velocity pattern that wraps around MM1, suggestive of a coherent physical structure 1200 au in extent. In contrast, the thermal lines exhibit a linear pattern that crosses MM1 but at progressive position angles that appear to be a function of either increasing temperature or decreasing optical depth. The maser spectral profiles evolved significantly over one month, and the intensities dropped by factors of 3.0-7.2, with the = 2 line showing the largest change. A small area of maser emission from only the highest excitation lines closest to MM1 has disappeared. There are seven additional dust continuum sources in the protocluster, including another hot core (MM3). We do not find evidence for a significant change in (sub)millimeter continuum emission from any of the sources during the one month interval, and the total protocluster emission remains comparable to prior single-dish measurements.
The severity and frequency of drought has increased around the globe, creating challenges in ensuring food security for a growing world population. As a consequence, improving water use efficiency by ...crops has become an important objective for crop improvement. Some wild crop relatives have adapted to extreme osmotic stresses and can provide valuable insights into traits and genetic signatures that can guide efforts to improve crop tolerance to water deficits. Eutrema salsugineum, a close relative of many cruciferous crops, is a halophytic plant and extremophyte model for abiotic stress research.
Using comparative transcriptomics, we show that two E. salsugineum ecotypes display significantly different transcriptional responses towards a two-stage drought treatment. Even before visibly wilting, water deficit led to the differential expression of almost 1,100 genes for an ecotype from the semi-arid, sub-arctic Yukon, Canada, but only 63 genes for an ecotype from the semi-tropical, monsoonal, Shandong, China. After recovery and a second drought treatment, about 5,000 differentially expressed genes were detected in Shandong plants versus 1,900 genes in Yukon plants. Only 13 genes displayed similar drought-responsive patterns for both ecotypes. We detected 1,007 long non-protein coding RNAs (lncRNAs), 8% were only expressed in stress-treated plants, a surprising outcome given the documented association between lncRNA expression and stress. Co-expression network analysis of the transcriptomes identified eight gene clusters where at least half of the genes in each cluster were differentially expressed. While many gene clusters were correlated to drought treatments, only a single cluster significantly correlated to drought exposure in both ecotypes.
Extensive, ecotype-specific transcriptional reprogramming with drought was unexpected given that both ecotypes are adapted to saline habitats providing persistent exposure to osmotic stress. This ecotype-specific response would have escaped notice had we used a single exposure to water deficit. Finally, the apparent capacity to improve tolerance and growth after a drought episode represents an important adaptive trait for a plant that thrives under semi-arid Yukon conditions, and may be similarly advantageous for crop species experiencing stresses attributed to climate change.
Abstract
We present the most complete to date interferometric study of the centimeter-wavelength methanol masers detected in G358.93−0.03 at the burst and post-burst epochs. A unique, ...near-IR/(sub)millimeter-dark and far-IR-loud massive young stellar object accretion burst was recently discovered in G358.93−0.03. The event was accompanied by flares of an unprecedented number of rare methanol maser transitions. The first images of three of the newly discovered methanol masers at 6.18, 12.23, and 20.97 GHz are presented in this work. The spatial structure evolution of the methanol masers at 6.67, 12.18, and 23.12 GHz is studied at two epochs. The maser emission in all detected transitions resides in a region of ∼0.″2 around the bursting source and shows a clear velocity gradient in the north–south direction, with redshifted features to the north and blueshifted features to the south. A drastic change in the spatial morphology of the masing region is found: a dense and compact “spiral” cluster detected at epoch I evolved into a disperse, “round” structure at epoch II. During the transition from the first epoch to the second, the region traced by masers expanded. The comparison of our results with the complementary Very Large Array, very long baseline interferometry, Submillimeter Array, and Atacama Large Millimeter/submillimeter Array maser data is conducted. The obtained methanol maser data support the hypothesis of the presence of spiral arm structures within the accretion disk, which was suggested in previous studies of the source.
809 deep IODP Hole U1473A at Atlantis Bank, SWIR, is 2.2 km from 1,508‐m Hole 735B and 1.4 from 158‐m Hole 1105A. With mapping, it provides the first 3‐D view of the upper levels of a 660‐km2 lower ...crustal batholith. It is laterally and vertically zoned, representing a complex interplay of cyclic intrusion, and ongoing deformation, with kilometer‐scale upward and lateral migration of interstial melt. Transform wall dives over the gabbro‐peridotite contact found only evolved gabbro intruded directly into the mantle near the transform. There was no high‐level melt lens, rather the gabbros crystallized at depth, and then emplaced into the zone of diking by diapiric rise of a crystal mush followed by crystal‐plastic deformation and faulting. The residues to mass balance the crust to a parent melt composition lie at depth below the center of the massif—likely near the crust‐mantle boundary. Thus, basalts erupted to the seafloor from >1,550 mbsf. By contrast, the Mid‐Atlantic Ridge lower crust drilled at 23°N and at Atlantis Massif experienced little high‐temperature deformation and limited late‐stage melt transport. They contain primitive cumulates and represent direct intrusion, storage, and crystallization of parental MORB in thinner crust below the dike‐gabbro transition. The strong asymmetric spreading of the SWIR to the south was due to fault capture, with the northern rift valley wall faults cutoff by a detachment fault that extended across most of the zone of intrusion. This caused rapid migration of the plate boundary to the north, while the large majority of the lower crust to spread south unroofing Atlantis Bank and uplifting it into the rift mountains.
Key Points
No evidence of a high‐level melt lens with gabbros intruded at depth, then emplaced to high levels by crystal mush diapirism, plastic deformation, and faulting
Diving over the crust‐mantle boundary on the transform wall found no primitive cumulates, and evolved gabbro was intruded directly into the mantle at the transform
Primitive cumulates needed to mass balance MORB must lie at depth near the crust‐mantle boundary, while the few diabase dikes encountered intrude the gabbro
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