Numerical Simulations Reproduce Field Observations Showing Transient Weakening During Shear Zone Formation by Diffusional Hydrogen Influx and H2O Inflow

Exposures on Holsnøy island (Bergen Arcs, Norway) indicate fluid infiltration through fractures into a dry, metastable granulite, which triggered a kinetically delayed eclogitization, a transient weakening during fluid-rock interaction, and formation of shear zones that widened during shearing. It remains unclear whether the effects of grain boundary-assisted aqueous fluid inflow on the duration of granulite hydration were influenced by a diffusional hydrogen influx accompanying the fluid inflow. To better estimate the fluid infiltration efficiencies and the parameter interdependencies, a 1D numerical model of a viscous shear zone is utilized and validated using measured mineral phase abundance distributions and H2O-contents in nominally anhydrous minerals of the original granulite assemblage to constrain the hydration by aqueous fluid inflow and diffusional hydrogen influx, respectively. Both hydrations are described with a diffusion equation and affect the effective viscosity. Shear zone kinematics are constrained by the observed shear strain and thickness. The model fits the phase abundance and H2O-content profiles if the effective hydrogen diffusivity is approximately one order of magnitude higher than the diffusivity for aqueous fluid inflow. The observed shear zone thickness is reproduced if the viscosity ratio between dry granulite and deforming, reequilibrating eclogite is ∼104 and that between dry granulite and hydrated granulite is ∼102. The results suggest shear velocities <10−2 cm/a, hydrogen diffusivities of ∼10−13±1 m2/s, and a shearing duration of <10 years. This study successfully links and validates field data to a shear zone model and highlights the importance of hydrogen diffusion for shear zone widening and eclogitization

How fluid infiltrates dry crustal rocks during progressive eclogitization and shear zone formation: insights from H2O contents in nominally anhydrous minerals

Granulites from Holsnøy (Bergen Arcs, Norway) maintained a metastable state until fluid infiltration triggered the kinetically delayed eclogitization. Interconnected hydrous eclogite-facies shear zones are surrounded by unreacted granulites. Macroscopically, the granulite–eclogite interface is sharp and there are no significant compositional changes in the bulk chemistry, indicating the fluid composition was quickly rock buffered. To better understand the link between deformation, fluid influx, and fluid–rock interaction one cm-wide shear zone at incipient eclogitization is studied here. Granulite and eclogite consist of garnet, pyroxene, and plagioclase. These nominally anhydrous minerals (NAMs) can incorporate H2O in the form of OH groups. H2O contents increase from granulite to eclogite, as documented in garnet from ~ 10 to ~ 50 µg/g H2O, pyroxene from ~ 50 to ~ 310 µg/g H2O, and granulitic plagioclase from ~ 10 to ~ 140 µg/g H2O. Bowl-shape profiles are characteristic for garnet and pyroxene with lower H2O contents in grain cores and higher at the rims, which suggest a prograde water influx into the NAMs. Omphacite displays a H2O content range from ~ 150 to 425 µg/g depending on the amount of hydrous phases surrounding the grain. The granulitic plagioclase first separates into a hydrous, more albite-rich plagioclase and isolated clinozoisite before being replaced by new fine-grained phases like clinozoisite, kyanite and quartz during ongoing fluid infiltration. Results indicate a twofold fluid influx with different mechanisms to act simultaneously at different scales and rates. Fast and more pervasive proton diffusion is recorded by NAMs that retain the major element composition of the granulite-facies equilibration where hydrogen decorates pre-existing defects in the crystal lattice and leads to OH increase. Contemporaneously, slower grain boundary-assisted aqueous fluid influx enables element transfer and results in progressive formation of new minerals, e.g., hydrous phases. Both mechanisms lead to bulk H2O increase from ~ 450 to ~ 2500 µg/g H2O towards the shear zone and convert the system from rigid to weak. The incorporation of OH groups reduces the activation energy for creep, promotes formation of smaller grain sizes (phase separation of plagioclase), and synkinematic metamorphic mineral reactions. These processes are part of the transient weakening, which enhance the sensitivity of the rock to deform

2013 Colorado forest insect and disease update

The reports describes "an annual investigation of critical forest health issues, including the identification of priority areas across the state where current forest conditions demand timely action." They are intended to "expand Coloradans' knowledge of and interest in our state's forest resources.".Reports produced by the Colorado State Forest Service in conjunction with Colorado Department of Natural Resources, Division of Forestry.Includes bibliographical references.January 2014.Includes the 2013 Colorado forest insect and disease update supplement.The theme of the 2013 report is Caring for Colorado's Forests: Today's Challenges, Tomorrow's Opportunities. How best to care for this vital resource has been a major topic of discussion. This year's report focuses on the values our forests provide and includes several examples of the successful collaborative forest management programs that were created to address the impacts of mountain pine beetle, threats associated with wildfire, and protection of critical watersheds and other values at risk. Hopefully theseexamples will lead to the identification of other potential solutions to the challenges our forests are facing. One thing is clear: forest stewardship is best achieved through the collective efforts of private landowners, public land managers, non-governmentalconservation organizations, elected officials and other interested stakeholders. The mission of the Colorado State Forest Service is to "achieve stewardship of Colorado's diverse forest environments for the benefit of present and future generations." At no time in Colorado's history has the CSFS mission been so relevant - and working with stakeholders to identify and implement innovative programs will help us further our mission

Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission

Classical scrapie is an environmentally transmissible prion disease of sheep and goats. Prions can persist and remain potentially infectious in the environment for many years and thus pose a risk of infecting animals after re-stocking. In vitro studies using serial protein misfolding cyclic amplification (sPMCA) have suggested that objects on a scrapie- affected sheep farm could contribute to disease transmission. This in vivo study aimed to determine the role of field furniture (water troughs, feeding troughs, fencing, and other objects that sheep may rub against) used by a scrapie-infected sheep flock as a vector for disease transmission to scrapie-free lambs with the prion protein genotype VRQ/VRQ, which is associated with high susceptibility to classical scrapie. When the field furniture was placed in clean accommodation, sheep became infected when exposed to either a water trough (four out of five) or to objects used for rubbing (four out of seven). This field furniture had been used by the scrapie-infected flock 8 weeks earlier and had previously been shown to harbor scrapie prions by sPMCA. Sheep also became infected (20 out of 23) through exposure to contaminated field furniture placed within pasture not used by scrapie-infected sheep for 40 months, even though swabs from this furniture tested negative by PMCA. This infection rate decreased (1 out of 12) on the same paddock after replacement with clean field furniture. Twelve grazing sheep exposed to field furniture not in contact with scrapie-infected sheep for 18 months remained scrapie free. The findings of this study highlight the role of field furniture used by scrapie-infected sheep to act as a reservoir for disease re-introduction although infectivity declines considerably if the field furniture has not been in contact with scrapie-infected sheep for several months. PMCA may not be as sensitive as VRQ/VRQ sheep to test for environmental contamination

Rapid, B1B_1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux

Purpose: Phosphorus saturation-transfer experiments can quantify metabolic fluxes non-invasively. Typically, the forward flux through the creatine-kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of $\gamma$-ATP. The quantification of total ATP utilisation is currently under-explored, as it requires simultaneous saturation of inorganic phosphate (Pi) and PCr. This is challenging, as currently available saturation pulses reduce the already-low $\gamma$-ATP signal present. Methods: Using a hybrid optimal-control and Shinnar-Le-Roux method, a quasi-adiabatic RF pulse was designed for the dual-saturation of PCr and Pi to enable determination of total ATP utilisation. The pulses were evaluated in Bloch equation simulations, compared with a conventional hard-cosine DANTE saturation sequence, before application to perfused rat hearts at 11.7 Tesla. Results: The quasi-adiabatic pulse was insensitive to a $>2.5$-fold variation in $B_1$, producing equivalent saturation with a 53% reduction in delivered pulse power and a 33-fold reduction in spillover at the minimum effective $B_1$. This enabled the complete quantification of the synthesis and degradation fluxes for ATP in 30-45 minutes in the perfused rat heart. While the net synthesis flux ($4.24\pm0.8$ mM/s, SEM) was not significantly different from degradation flux ($6.88\pm2$ mM/s, $p=0.06$) and both measures are consistent with prior work, nonlinear error analysis highlights uncertainties in the Pi-to-ATP measurement that may explain a trend suggesting a possible imbalance. Conclusion: This work demonstrates a novel quasi-adiabatic dual-saturation RF pulse with significantly improved performance that can be used to measure ATP turnover in the heart in vivo.Comment: 26 pages, Accepted at Magnetic Resonance in Medicine, 24/11/2020 [This version post reviews

Compensating farmers for ecosystem services: Lessons and an agenda for innovation

The CompensACTION Initiative aims to promote payments for ecosystem services (PES) to improve smallholder farmers’ incomes at large scales while incentivizing climate action, sustainable farming and other environmental outcomes. Key drivers for scaling up PES programs are increasing farmers’ benefits in PES schemes, using public finance to leverage private sector capital, and facilitating PES project readiness. Priority areas for action to meet the CompensACTION Initiative objectives are to: • Foster technical innovation and disruption to support low-cost, high- volume PES transactions. • Increase public and private investment to scale up PES programs. • Support public policy reform to establish national frameworks for PES schemes. • G7 members and other countries can play a leadership role in mobilizing action

Fatty acids prevent Hypoxia-Inducible Factor 1α signalling in type 2 diabetes

SUMMARYHypoxia-inducible factor (HIF)-1ais essential following a myocardial infarction (MI), and diabetic patients havepoorer prognosis post-MI. Could HIF-1aactivation be abnormal in the diabetic heart, and could metabolism becausing this? Diabetic hearts had decreased HIF-1aprotein following ischemia, and insulin-resistant cardio-myocytes had decreased HIF-1a-mediated signaling and adaptation to hypoxia. This was due to elevated fattyacid (FA) metabolism preventing HIF-1aprotein stabilization. FAs exerted their effect by decreasing succinateconcentrations, a HIF-1aactivator that inhibits the regulatory HIF hydroxylase enzymes. In vivo and in vitropharmacological HIF hydroxylase inhibition restored HIF-1aaccumulation and improved post-ischemic func-tional recovery in diabetes

Exploration of Antiferromagnetic CoO and NiO using Reverse Monte Carlo Total Neutron Scattering Refinement

The atomic and magnetic structures of CoO and NiO have been probed using reverse Monte Carlo refinements of neutron total scattering data. The results obtained show that the known magnetic structure for NiO can be recovered by the reverse Monte Carlo process starting from random spin configurations, but it is insensitive to the spin direction in the {111} ferromagnetic planes. Refinements of the magnetic structure of CoO starting from random spin configurations result in collinear or non-collinear magnetic structure, consistent with those reported by other techniques. Starting from an ordered collinear spin structure for CoO and NiO leads to different results than when starting from a random arrangement of spins, evidence for configurational bias that highlights the need to take care when selecting a starting model for reverse Monte Carlo refinements of magnetic structures