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A major challenge in tokamak fusion research is first-wall erosion caused by steady heat loads and sudden energy bursts known as edge-localized modes. Divertor detachment reduces steady-state heat flux, while resonant magnetic perturbations can suppress these instabilities. However, integrating the two has been difficult because they require conflicting operating conditions. Here we demonstrate simultaneous achievement of resonant magnetic perturbations mitigated small edge-localized modes and impurity seeded partial divertor detachment in plasmas with an ITER-similar shape on the DIII-D tokamak. Experiments and simulations show that resonant magnetic perturbations facilitate detachment by redistributing particles, lowering the core density and increasing the scrape-off layer density, thereby reducing the amount of injected gas required. Cooling-gas injection eliminates the secondary heat-flux peak created by three-dimensional magnetic lobes, while edge cooling weakens the plasma response to the applied magnetic fields. These advances illustrate a viable pathway for integrating edge stability control with power exhaust in future fusion reactors.

In a magnetic configuration that has been sufficiently optimized for quasi-symmetry, the neoclassical transport and viscosity can be small enough that other terms can compete in the momentum balance to determine the plasma rotation and radial electric field. The Reynolds stress generated by plasma turbulence is identified as the most likely candidate for non-neoclassical flow drive in the HSX stellarator. Using multi-tipped Langmuir probes in the edge of HSX in the quasi-helically symmetric (QHS) configuration, the radial electric field and parallel flows are found to deviate from the values calculated by the neoclassical transport code PENTA using the ambipolarity constraint in the absence of externally injected momentum. The local Reynolds stress in the parallel and perpendicular directions on a surface is also measured using the fluctuating components of floating potential and ion saturation current measurements. Although plasma turbulence enters the momentum balance as the flux surface averaged radial gradient of the Reynolds stress, the locally measured quantity implies a significant contribution to the momentum balance. If extrapolated to a flux surface average, this locally measured Reynolds stress gradient is calculated to result in a flow drive many times larger than the observed flows. Probe measurements made at two locations on the device in regions with different magnetic geometry indicate very different, but consistently large Reynolds stress drive terms. The large variation of the local Reynolds stress on a flux surface suggests that a small number of measurement locations is insufficient to properly sample the flux surface averaged quantity. Contrary to expectations, measurements in configurations with the quasi-symmetry intentionally degraded deviate more from the neoclassically calculated velocity profiles than those in the QHS configuration. Measured density fluctuations and the Reynolds stress are reduced in these cases, indicating that additional terms may be important in the momentum balance.

Experiments have been conducted in the DIII-D tokamak to explore the in-situ growth of silicon-rich layers as a potential technique for real-time replenishment of surface coatings on plasma-facing components (PFCs) during steady-state long-pulse reactor operation. Silicon (Si) pellets of 1 mm diameter were injected into low- and high-confinement (L-mode and H-mode) plasma discharges with densities ranging from \\(3.9-7.5\\times10^{19}\\) m\\(^{-3}\\) and input powers ranging from \\(5.5-9\\) MW. The small Si pellets were delivered with the impurity granule injector (IGI) at frequencies ranging from 4-16 Hz corresponding to mass flow rates of \\(5-19\\) mg/s (\\(1-4.2\\times10^{20}\\) Si/s) at cumulative amounts of up to 34 mg of Si per five-second discharge. Graphite samples were exposed to the scrape-off layer and private flux region plasmas through the divertor material evaluation system (DiMES) to evaluate the Si deposition on the divertor targets. The Si II emission at the sample correlates with silicon injection and suggests net surface Si-deposition in measurable amounts. Post-mortem analysis showed Si-rich coatings containing silicon oxides, of which SiO\\(_2\\) is the dominant component. No evidence of SiC was found, which is attributed to low divertor surface temperatures. The in-situ and ex-situ analysis found that Si-rich coatings of at least \\(0.4-1.2\\) nm thickness have been deposited at \\(0.4-0.7\\) nm/s. The technique is estimated to coat a surface area of at least 0.94 m\\(^2\\) on the outer divertor. These results demonstrate the potential of using real-time material injection to form Si-enriched layers on divertor PFCs during reactor operation.

Brazil has the second-largest cattle herd in the world and is a major exporter of beef. While ranching in the Amazon-and its destructive environmental consequences-receives attention from both the media and scholars, the states of Mato Grosso and Mato Grosso do Sul actually host the most cattle. A significant beef producer in Brazil beginning in the late nineteenth century, the region served as a laboratory for raising cattle in the tropics, where temperate zone ranching practices do not work. Mato Grosso ranchers and cowboys transformed ranching's relationship with the environment, including the introduction of an exotic cattle breed-the Zebu-that now dominates Latin American tropical ranching. Cattle in the Backlandspresents a comprehensive history of ranching in Mato Grosso. Using extensive primary sources, Robert W. Wilcox explores three key aspects: the economic transformation of a remote frontier region through modern technical inputs; the resulting social changes, especially in labor structures and land tenure; and environmental factors, including the long-term impact of ranching on ecosystems, which, he contends, was not as detrimental as might be assumed. Wilcox demonstrates that ranching practices in Mato Grosso set the parameters for tropical beef production in Brazil and throughout Latin America. As the region was incorporated into national and international economic structures, its ranching industry experienced the entry of foreign investment, the introduction of capitalized processing facilities, and nascent discussions of ecological impacts-developments that later affected many sectors of the Brazilian economy.

As global awareness, science, and policy interventions for plastic escalate, institutions around the world are seeking preventative strategies. Central to this is the need for precise global time series of plastic pollution with which we can assess whether implemented policies are effective, but at present we lack these data. To address this need, we used previously published and new data on floating ocean plastics (n = 11,777 stations) to create a global time-series that estimates the average counts and mass of small plastics in the ocean surface layer from 1979 to 2019. Today’s global abundance is estimated at approximately 82–358 trillion plastic particles weighing 1.1–4.9 million tonnes. We observed no clear detectable trend until 1990, a fluctuating but stagnant trend from then until 2005, and a rapid increase until the present. This observed acceleration of plastic densities in the world’s oceans, also reported for beaches around the globe, demands urgent international policy interventions.

Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.

Bezlotoxumab is human monoclonal antibody against Clostridium difficile toxin B. In two controlled trials, a single intravenous dose of bezlotoxumab, given in addition to antibiotic treatment, provided protection against recurrent infection for up to 12 weeks.

Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.

In patients with severe acute kidney injury (AKI) but no urgent indication for renal replacement therapy (RRT), the optimal time to initiate RRT remains controversial. While starting RRT preemptively may have benefits, this may expose patients to unnecessary RRT. To study this, we conducted a 12-center open-label pilot trial of critically ill adults with volume replete severe AKI. Patients were randomized to accelerated (12 h or less from eligibility) or standard RRT initiation. Outcomes were adherence to protocol-defined time windows for RRT initiation (primary), proportion of eligible patients enrolled, follow-up to 90 days, and safety in 101 fully eligible patients (57 with sepsis) with a mean age of 63 years. Median serum creatinine and urine output at enrollment were 268 micromoles/l and 356 ml per 24 h, respectively. In the accelerated arm, all patients commenced RRT and 45/48 did so within 12 h from eligibility (median 7.4 h). In the standard arm, 33 patients started RRT at a median of 31.6 h from eligibility, of which 19 did not receive RRT (6 died and 13 recovered kidney function). Clinical outcomes were available for all patients at 90 days following enrollment, with mortality 38% in the accelerated and 37% in the standard arm. Two surviving patients, both randomized to standard RRT initiation, were still RRT dependent at day 90. No safety signal was evident in either arm. Our findings can inform the design of a large-scale effectiveness randomized control trial.

Heterogeneity of major depressive disorder (MDD) illness course complicates clinical decision-making. Although efforts to use symptom profiles or biomarkers to develop clinically useful prognostic subtypes have had limited success, a recent report showed that machine-learning (ML) models developed from self-reports about incident episode characteristics and comorbidities among respondents with lifetime MDD in the World Health Organization World Mental Health (WMH) Surveys predicted MDD persistence, chronicity and severity with good accuracy. We report results of model validation in an independent prospective national household sample of 1056 respondents with lifetime MDD at baseline. The WMH ML models were applied to these baseline data to generate predicted outcome scores that were compared with observed scores assessed 10–12 years after baseline. ML model prediction accuracy was also compared with that of conventional logistic regression models. Area under the receiver operating characteristic curve based on ML (0.63 for high chronicity and 0.71–0.76 for the other prospective outcomes) was consistently higher than for the logistic models (0.62–0.70) despite the latter models including more predictors. A total of 34.6–38.1% of respondents with subsequent high persistence chronicity and 40.8–55.8% with the severity indicators were in the top 20% of the baseline ML-predicted risk distribution, while only 0.9% of respondents with subsequent hospitalizations and 1.5% with suicide attempts were in the lowest 20% of the ML-predicted risk distribution. These results confirm that clinically useful MDD risk-stratification models can be generated from baseline patient self-reports and that ML methods improve on conventional methods in developing such models.