bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehensive Insight into the Mechanism, Material Selection and Performance Evaluation of Supercapatteries
Authors: Balasubramaniam Saravanakumar , Mohanty Ankita , Balasingam Suresh Kannan , Kim Sang Jae , Ramadoss Ananthakumar
Published: April 2020

Electrochemical energy storage devices (EESs) play a crucial role for the construction of sustainable energy storage system from the point of generation to the end user due to the intermittent nature of renewable sources. Additionally, to meet the demand for next-generation electronic applications, optimizing the energy and power densities of EESs with long cycle life is the crucial factor. Great efforts have been devoted towards the search for new materials, to augment the overall performance of the EESs. Although there are a lot of ongoing researches in this field, the performance does not meet up to the level of commercialization. A further understanding of the charge storage mechanism and development of new electrode materials are highly required. The present review explains the overview of recent progress in supercapattery devices with reference to their various aspects. The different charge storage mechanisms and the multiple factors involved in the performance of the supercapattery are described in detail. Moreover, recent advancements in this supercapattery research and its electrochemical performances are reviewed. Finally, the challenges and possible future developments in this field are summarized.
Beyond sectarianism: Intermarriage and social difference in Lebanon
Authors: Deeb Lara
Published: April 2020

Based on interviews with Lebanese in over 150 mixed-religion marriages and their extended family members, I argue that sect may conceal or stand in for other forms of difference, including ideas about status and hierarchy related to class and regional origin in Lebanon. Because it is the most readily available discourse for understanding social difference, parents often use sectarian rhetoric to describe their concerns about a variety of problems they see in their children's chosen partners. By listening between the lines of parental objections, I suggest that expressions of bias against people of other sects may mask concerns with other forms of social difference, in effect reducing a complex and shifting social field of multiple axes of difference into sect. Rather than assume sectarianism's a priori importance, this approach allows me to bring other discourses of difference and analytic lenses to the foreground.
Selenium deficiency risks in sub-Saharan African food systems and their geospatial linkages
Authors: Ligowe I. S. , Phiri F. P. , Ander E. L. , Bailey E. H. , Chilimba A. D. C. , Gashu D. , Joy E. J. M. , Lark R. M. , Kabambe V. , Kalimbira A. A. , Kumssa D. B. , Nalivata P. C. , Young S. D. , Broadley M. R.
Published: April 2020

Selenium (Se) is an essential element for human health. However, our knowledge of the prevalence of Se deficiency is less than for other micronutrients of public health concern such as iodine, iron and zinc, especially in sub-Saharan Africa (SSA). Studies of food systems in SSA, in particular in Malawi, have revealed that human Se deficiency risks are widespread and influenced strongly by geography. Direct evidence of Se deficiency risks includes nationally representative data of Se concentrations in blood plasma and urine as population biomarkers of Se status. Long-range geospatial variation in Se deficiency risks has been linked to soil characteristics and their effects on the Se concentration of food crops. Selenium deficiency risks are also linked to socio-economic status including access to animal source foods. This review highlights the need for geospatially-resolved data on the movement of Se and other micronutrients in food systems which span agriculture–nutrition–health disciplinary domains (defined as a GeoNutrition approach). Given that similar drivers of deficiency risks for Se, and other micronutrients, are likely to occur in other countries in SSA and elsewhere, micronutrient surveillance programmes should be designed accordingly.
The Call to Play: New Work and Labor at Artsadmin
Authors: Livergant Elyssa
Published: April 2020

February 2010. The lights are off. As I adjust to the dark I can make out shapes of others scattered around the room. Disoriented and uncertain I wait for some sign or direction of what to do. The air is thick with anticipation, but as time drags it becomes clear that no instructions are coming. Then it begins all around me. Sat in the dark in a workshop in the courtroom studio of Toynbee Studios, I begin to feel anxious. I see the outline of another body in front of me and I panic. I should do something. I reach for anything that might keep things working, that might keep play going. Does anyone want to dance, I ask. I waltz. I sense someone dancing behind me.

In what follows I think through my participation in a 2010 workshop led by Anne Bean, recounted in part above, to understand better the role of play in the conditions of production for theatre and performance under capital. Bean is an interdisciplinary artist, belonging to (or claimed by) multiple experimental art scenes, including visual, performance, and sound art, who has been a central figure of European live art since the 1970s. The workshop, which was conducted largely in the dark and focused on the aestheticization of cooperation through an emphasis on its participants doing play was held at Artsadmin's Toynbee Studios, the influential UK arts producing organization's home in East London. This article puts my account of Bean's workshop in conversation with Victorian economist Arnold Toynbee's demand for a new capitalist morality. Toynbee's appeal was, of course, not directed at me or the other workshop participants disoriented and uncertain in the dark. But, I argue, the situation of play that arose in Bean's workshop is a contemporary iteration of what Toynbee called agospel of life,a term referring to a commitment to self and civic betterment at the core of a burgeoning capitalist morality. The connection between the shaping of Victorian labor practices and the staging of cooperation between participants in Bean's contemporary workshop is the basis for this essay's core assertion: that the value of play as a counterpoint to work within practices and discourses of theatre and performance needs considerable rethinking.
On the Magnetospheric ULF Wave Counterpart of Substorm Onset
Authors: Smith A. W. , Rae I. J. , Forsyth C. , Watt C. E. J. , Murphy K. R.
Published: April 2020

One near‐ubiquitous signature of substorms observed on the ground is the azimuthal structuring of the onset auroral arc in the minutes prior to onset. Termed auroral beads, these optical signatures correspond to concurrent exponential increases in ground ultralow frequency (ULF) wave power and are likely the result of a plasma instability in the magnetosphere. Here, we present a case study showing the development of auroral beads from a Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky camera with near simultaneous exponential increases in auroral brightness, ionospheric and conjugate magnetotail ULF wave power, evidencing their intrinsic link. We further present a survey of magnetic field fluctuations in the magnetotail around substorm onset. We find remarkably similar superposed epoch analyses of ULF power around substorm onset from space and conjugate ionospheric observations. Examining periods of exponential wave growth, we find the ground‐ and space‐based observations to be consistent, with average growth rates of ∼0.01 s−1, lasting for ∼4 min. Cross‐correlation suggests that the space‐based observations lead those on the ground by approximately 1–1.5 min. Meanwhile, spacecraft located premidnight and ∼10 RE downtail are more likely to observe enhanced wave power. These combined observations lead us to conclude that there is a magnetospheric counterpart of auroral beads and exponentially increasing ground ULF wave power. This is likely the result of the linear phase of a magnetospheric instability, active in the magnetotail for several minutes prior to auroral breakup.
A Subtidal Box Model Based on the Longitudinal Anomaly of Potential Energy for Narrow Estuaries. An Application to the Guadalquivir River Estuary (SW Spain)
Authors: Cobos M. , Baquerizo A. , Díez‐Minguito M. , Losada M. A.
Published: April 2020

The objective of the present study is to demonstrate the informative capacity of the longitudinal anomaly of potential energy (LAPE) in the analysis of the magnitude and spatiotemporal variability of estuarine processes. For this purpose, a LAPE balance equation is formulated. The LAPE integrates and varies with the vertical and longitudinal density distribution. The formulation is applied on a subtidal scale to each box or stretch of the Guadalquivir River estuary, a narrow, highly turbid, weakly stratified, and strongly anthropized estuary. Data recorded by a large network of monitoring stations in 2008 and 2009 are used to quantify advective transports as well as the transports associated with longitudinal dispersion and vertical turbulent mixing in different hydraulic regimes. In low‐river flow conditions, (river flows Q<40 m3s−1), the magnitude of LAPE transports decreases upstream and varies locally, depending on neap‐spring tidal cycles. The direction of the net LAPE transport creates convergence zones that are particularly consistent with maximum levels of estuarine turbidity. During high‐river flows (Q>400 m3s−1), this convergence disappears and the maximum longitudinal density gradient moves towards the mouth. More specifically, tidal pumping ‐induced LAPE governs during these conditions and manages to compensate the sum of the mean nontidal and dispersive and differential advective LAPE transports. However, during the post‐riverflood period, the mechanisms controlling recovery downstream from the mouth are the longitudinal dispersive and differential advective LAPE transports. Furthermore, the convergence zone reappears with a longitudinal gradient of the net LAPE transport that is even greater than in low‐river flow conditions.
The Influence of Diapycnal Nutrient Fluxes on Phytoplankton Size Distribution in an Area of Intense Mesoscale and Submesoscale Activity off Concepción, Chile
Authors: Corredor‐Acosta A. , Morales C. E. , Rodríguez‐Santana A. , Anabalón V. , Valencia L. P. , Hormazabal S.
Published: April 2020

Mesoscale and submesoscale processes that contribute to localized increases in nutrients in the sunlit layer can stimulate phytoplankton growth and community changes, but the mechanisms involved remain sparsely documented with in situ data in the case of Eastern Boundary Upwelling Systems (EBUSs) and of most ocean regions. The role of diapycnal mixing in providing nutrients to the upper layer and in influencing phytoplankton size structure was analyzed in an area of intense mesoscale and submesoscale activity during the coastal upwelling season off Concepción (~36–37°S), the Humboldt Current EBUS. Diapycnal nutrient fluxes based on conductivity, temperature, and depth vertical eddy diffusivity (Kz) values (the Thorpe scale method) and on nutrient gradients were assessed in association with size‐fractionated chlorophyll‐a and microdiatom abundance derived from in situ sampling in an area including a mesoscale intrathermocline eddy (ITE) adjacent to a coastal upwelling front (CUF). The indirect estimates of Kz values spanned between 0.01 and 4 × 10−4 m2 s−1, and maxima in diapycnal nitrate flux per station ranged between 0.08 and 19.1 mmol m−2 day−1. Maxima in the upward fluxes were detected at the subsurface (15–40 m depth) in the CUF and ITE areas, coinciding with maxima in the micro‐ and nano‐chlorophyll‐a fractions and in microdiatom abundance. These results suggest that ITE and CUF features, as well as their interaction, can generate intense diapycnal mixing and, thereby, contribute to increasing nutrient availability below the mixed layer. In turn, these processes enhance the contribution of larger phytoplankton cells in the coastal transition zone of EBUSs.
Surface Methane Concentrations Along the Mid‐Atlantic Bight Driven by Aerobic Subsurface Production Rather Than Seafloor Gas Seeps
Authors: Leonte Mihai , Ruppel Carolyn D. , Ruiz‐Angulo Angel , Kessler John D.
Published: April 2020

Relatively minor amounts of methane, a potent greenhouse gas, are currently emitted from the oceans to the atmosphere, but such methane emissions have been hypothesized to increase as oceans warm. Here, we investigate the source, distribution, and fate of methane released from the upper continental slope of the U.S. Mid‐Atlantic Bight, where hundreds of gas seeps have been discovered between the shelf break and ~1,600 m water depth. Using physical, chemical, and isotopic analyses, we identify two main sources of methane in the water column: seafloor gas seeps and in situ aerobic methanogenesis which primarily occurs at 100–200 m depth in the water column. Stable isotopic analyses reveal that water samples collected at all depths were significantly impacted by aerobic methane oxidation, the dominant methane sink in this region, with the average fraction of methane oxidized being 50%. Due to methane oxidation in the deeper water column, below 200 m depth, surface concentrations of methane are influenced more by methane sources found near the surface (0–10 m depth) and in the subsurface (10–200 m depth), rather than seafloor emissions at greater depths.
A Physically Based Method for Real‐Time Monitoring of Tidal River Discharges From Water Level Observations, With an Application to the St. Lawrence River
Authors: Bourgault Daniel , Matte Pascal
Published: April 2020

A fast, physically based, fully nonlinear, and nonsteady reach‐averaged river model is developed to provide instantaneous freshwater discharge rates in the tidally influenced stretch of the St. Lawrence River (Canada) from water level measurements alone at two tide gauge stations. The model does not require any a priori knowledge of the river geometry (width and depth) or hydraulic conditions (hydraulic slope and friction coefficient) as those parameters are inferred by inverse modeling. The model is fast in that several decades of hourly discharges can be reproduced in few seconds on any modern desktop computer. The method is accurate in that it reproduces to within 3% the observed tidal discharge variability at 8 different cross‐sections distributed along the tidally influenced portion of the St. Lawrence River. Although much simpler, the new method performs as well as, or better than, much more sophisticated models for reproducing daily and monthly discharge averages. Being physically based, it is also shown that the model can perform well outside the limited range of measurements that are generally available for calibration. The method is simple and easy to manage in that the main function only contains a few lines of code such that it could be readily implemented as a tool for real‐time discharge monitoring of the St. Lawrence River near Québec City. Being physically based, the model developed here could likely be applied more generally to highly unsteady tidal rivers with flow reversals.
Radiation Controls the Interannual Variability of Evaporation of a Subtropical Lake
Authors: Xiao Wei , Zhang Zhen , Wang Wei , Zhang Mi , Liu Qiang , Hu Yongbo , Huang Wenjing , Liu Shoudong , Lee Xuhui
Published: April 2020

Does lake evaporation increase or decrease under the scenario of climate warming? This paper aims to answer this question by investigating the controlling mechanism of interannual variations in lake evaporation at a subtropical lake. The research methodology is based on continuous eddy covariance measurement over >7 years and a diagnostic analysis using the surface energy balance principle. The results indicate that lake evaporation was enhanced mainly by increasing energy inputs including solar radiation and incoming longwave radiation and was weakened by surface feedback through outgoing longwave radiation. The incoming longwave radiation was positively correlated with cloud cover. Bowen ratio and surface albedo had slight effect on the change of lake evaporation. The annual lake evaporation can be predicted by the Priestly‐Taylor model using a larger coefficient of 1.39 than the original value of 1.26, suggesting that advection or entrainment in the atmospheric boundary layer may play a role in lake evaporation.
Enhanced New Particle Formation Above the Marine Boundary Layer Over the Yellow Sea: Potential Impacts on Cloud Condensation Nuclei
Authors: Takegawa N. , Seto T. , Moteki N. , Koike M. , Oshima N. , Adachi K. , Kita K. , Takami A. , Kondo Y.
Published: April 2020

Aircraft measurements of aerosols were conducted over the Yellow Sea and the East China Sea from February 14 to March 10, 2013, during the Aerosol Radiative Forcing in East Asia 2013 Winter campaign. Ground‐based measurements of aerosols were also conducted on Fukue Island (32.8°N, 128.7°E), located near the boundary of the Yellow Sea and the East China Sea. The aircraft measurements revealed large increases in particle number concentrations in the nucleation mode (2.5–10 nm and up to ~105 cm−3) at altitudes of ~0.5–3 km over the Yellow Sea. This was attributed to enhanced new particle formation (NPF) above the marine boundary layer over the Yellow Sea. The number ratios of Aitken‐mode (10–90 nm) or accumulation‐mode (>90 nm) particles to black carbon particles (tracer for primary emissions) were used to quantify the effects of NPF on particle number concentrations. We estimated that NPF increased median Aitken‐mode particle number concentrations by an order of magnitude at altitudes of ~1–3 km over the Yellow Sea. Synchronized aircraft and ground‐based data suggest that vertical transport of Aitken‐mode particles formed over the Yellow Sea led to a large variability in the particle growth events observed on Fukue Island. A shift of sea surface temperature near Fukue Island and the resultant promotion of vertical mixing are probably the key mechanisms responsible for this complex feature. Evolution of accumulation‐mode particles was observed farther downwind over the East China Sea, suggesting significant impacts of NPF on the regional distributions of cloud condensation nuclei.
Convectively Generated Gravity Waves During Solstice and Equinox Conditions
Authors: Heale C. J. , Lund T. S. , Fritts D. C.
Published: April 2020

Previous studies suggest that mesospheric concentric wave patterns are more observable in the equinox months than solstice months, despite concentric and semiconcentric waves being readily observed in summer months in the stratosphere. This study uses a 3‐D nonlinear model to simulate the propagation and dissipation of convectively generated gravity waves under averaged equinox and solstice conditions to investigate the influences of wave breaking upon these concentric patterns. It is found that the relatively weak atmospheric winds and shears during the equinox months means that waves can propagate up to the lower thermosphere before breaking. In contrast, strong zonal winds and shears in the summer solstice months lead to in situ breaking in the mesosphere, which causes disruption to the concentric pattern. While the western propagating portion of the concentric pattern is filtered by the stratospheric winds, the eastern propagating portion rapidly transitions to turbulence in the mesosphere making it less likely to observe concentric patterns in the solstice months. The concentric pattern is more complete in the equinox months because the waves are only weakly filtered by winds and relatively little in situ breaking occurs in the mesosphere. However, in situ breaking does not affect the pattern in the stratosphere, where the morphology is primarily dictated by wind filtering. This also helps explain why concentric and semiconcentric patterns are observed in the summer stratosphere but not regularly in the mesosphere.
Mechanisms Responsible for Stratosphere‐to‐Troposphere Transport Around a Mesoscale Convective System Anvil
Authors: Phoenix Daniel B. , Homeyer Cameron R. , Barth Mary C. , Trier Stanley B.
Published: April 2020

Recent observational studies have shown that stratospheric air rich in ozone (O3) is capable of being transported into the upper troposphere in association with tropopause‐penetrating convection (anvil wrapping). This finding challenges the current understanding of upper tropospheric sources of O3, which is traditionally thought to come from thunderstorm outflows where lightning‐generated nitrogen oxides facilitate O3 formation. Since tropospheric O3 is an important greenhouse gas and the frequency and strength of tropopause‐penetrating storms may change in a changing climate, it is important to understand the mechanisms driving this transport process so that it can be better represented in chemistry‐climate models. Simulations of a mesoscale convective system (MCS) around which this transport process was observed are performed using the Weather Research and Forecasting model coupled with Chemistry. The Weather Research and Forecasting model coupled with Chemistry model adequately simulates anvil wrapping of ozone‐rich air. Possible mechanisms that influence the transport, including small‐scale static and dynamic instabilities and MCS‐induced mesoscale circulations, are evaluated. Model results suggest that anvil wrapping is a two‐step transport process (1) compensating subsidence surrounding the MCS, which is driven by mass conservation as the MCS transports tropospheric air into the upper troposphere and lower stratosphere, followed by (2) differential advection beneath the core of the MCS upper‐tropospheric outflow jet which wraps high O3 air around and under the MCS cloud anvil. Static and dynamic instabilities are not a leading contributor to this transport process. Continued fine‐scale modeling of these events is needed to fully represent the stratosphere‐to‐troposphere transport process.
Troposphere‐Stratosphere Coupling in Subseasonal‐to‐Seasonal Models and Its Importance for a Realistic Extratropical Response to the Madden‐Julian Oscillation
Authors: Schwartz Chen , Garfinkel Chaim I.
Published: April 2020

The representation of upward and downward stratosphere‐troposphere coupling and its influence on the teleconnections of the Madden‐Julian oscillation (MJO) to the European sector is examined in five subseasonal‐to‐seasonal models. We show that while the models simulate a realistic stratospheric response to transient anomalies in troposphere, they overestimate the downward coupling. The models with a better stratospheric resolution capture a more realistic stratospheric response to the MJO, particularly after the first week of the integration. However, in all models examined here the connection between the MJO and vortex variability is weaker than that observed. Finally, we focus on the MJO‐SSW (sudden stratospheric warming) teleconnection and specifically initializations during the MJO phase with enhanced convection in the west/central pacific (i.e., 6 and 7) that preceded observed SSW. The integrations that simulated a SSW (as observed) can be distinguished from those that failed to simulate a SSW by the realism of the Pacific response to MJO 6/7, with only the simulations that successfully simulate a SSW capturing the North Pacific low. Furthermore, only the simulations that capture the SSW subsequently simulate a realistic surface response over the North Atlantic and Europe.
Decreased Soil Organic Matter in a Long‐Term Soil Warming Experiment Lowers Soil Water Holding Capacity and Affects Soil Thermal and Hydrological Buffering
Authors: Werner W. J. , Sanderman J. , Melillo J. M.
Published: April 2020

Long‐term soil warming can decrease soil organic matter (SOM), resulting in self‐reinforcing feedback to the global climate system. We investigated additional consequences of SOM reduction for soil water holding capacity (WHC) and soil thermal and hydrological buffering. At a long‐term soil warming experiment in a temperate forest in the northeastern United States, we suspended the warming treatment for 104 days during the summer of 2017. The formerly heated plot remained warmer (+0.39 °C) and drier (−0.024 cm3 H2O cm−3 soil) than the control plot throughout the suspension. We measured decreased SOM content (−0.184 g SOM g−1 for O horizon soil, −0.010 g SOM g−1 for A horizon soil) and WHC (−0.82 g H2O g−1 for O horizon soil, −0.18 g H2O g−1 for A horizon soil) in the formerly heated plot relative to the control plot. Reduced SOM content accounted for 62% of the WHC reduction in the O horizon and 22% in the A horizon. We investigated differences in SOM composition as a possible explanation for the remaining reductions with Fourier transform infrared (FTIR) spectra. We found FTIR spectra that correlated more strongly with WHC than SOM, but those particular spectra did not differ between the heated and control plots, suggesting that SOM composition affects WHC but does not explain treatment differences in this study. We conclude that SOM reductions due to soil warming can reduce WHC and hydrological and thermal buffering, further warming soil and decreasing SOM. This feedback may operate in parallel, and perhaps synergistically, with carbon cycle feedbacks to climate change.
Riparian Lowlands in Clay Till Landscapes Part II: Nitrogen Reduction and Release Along Variable Flow Paths
Authors: Petersen R. J. , Prinds C. , Jessen S. , Iversen B. V. , Kjaergaard C.
Published: April 2020

Riparian lowlands are known to control catchment nitrogen (N) balances. This study examined the role of agricultural tile drainage systems, often present in clay till landscapes, on the transport, transformation, and mass balance of N species in four riparian peat lowland transects receiving agricultural tile drainage water. Monitoring of N speciation of drain, stream, and groundwater, combined with a previously established water balance, enabled the determination of N mass balances for different flow paths including groundwater, subsurface drain water, and overland flow for each piezometer transect. The type of overland flow largely affected nitrate‐N (NO3‐N) removal efficiency, as determined by the total N output from a transect relative to the NO3‐N loading (%). Infiltration and subsurface flow followed by exfiltration (short return flow) allowed an efficient removal of NO3‐N (71–94%), while direct overland flow strongly lowered NO3‐N removal (25%) in one transect. The hydraulic loading rate versus the lowland infiltration capacity determined the transport pathways and thus the resulting NO3‐N removal efficiency. For all transects there was a net export of organic N and/or ammonium, associated with in situ N release from peat decomposition, through overland flow and groundwater discharge. These exports partly counterbalanced NO3‐N removal and significantly reduced the overall total N removal for the riparian lowlands. However, the N removal efficiencies remained positive (1–56%). The study indicates that N budgets for riparian lowlands need to account for overland flow as a transport pathway for N.
Nondispersive Drainage Direction Simulation Based on Flexible Triangular Facets
Authors: Wu Pengfei , Liu Jintao , Han Xiaole , Liang Zhongmin , Liu Yangyang , Fei Junyuan
Published: April 2020

A new eight‐direction algorithm (iFAD8) for the simulation of drainage directions on grid digital elevation models (DEMs) is presented. In this algorithm, a flexible triangular facet construction technique (ND∞) is developed to provide local drainage directions ranging continuously from 0° to 360°. Subsequently, a flow aggregation technique using global deviations of local drainage directions is proposed to simplify the flow paths into a nondispersive format. Another algorithm (FAD8) accompanying the iFAD8 is also presented, which uses the D∞ directions as the local drainage directions. Then FAD8, iFAD8, and three existing algorithms are compared on 10 abstract terrains including nine basic terrains and a Himmelblau terrain. The algorithms are tested to reproduce exact slope lines and specific catchment areas derived from the terrain functions. The results show that iFAD8 has better performance than FAD8. Both iFAD8 and FAD8 outperform existing algorithms in most cases. The flow aggregation technique is shown to be an excellent choice for nondispersive drainage direction simulation based on infinite directions. The ND∞ direction based on flexible triangular facets is also an improvement to the local infinite direction of D∞. We conclude that the iFAD8 algorithm can provide better definitions of drainage directions.
Calvin Receives 2019 Piers J. Sellers Global Environmental Change Mid-Career Award
Authors:   AGU
Published: April 2020

Katherine Calvin received the Piers J. Sellers Global Environmental Change Mid-Career Award at AGU’s Fall Meeting 2019, held 9–13 December in San Francisco, Calif. The award recognizes a scientist or team of midcareer scientists “for outstanding contributions in research, educational, or societal impacts in the area of global environmental change, especially through interdisciplinary approaches.”
Finding Natural Solutions to Man-Made Problems in River Deltas
Authors: Wheeling Kate
Published: April 2020

Decades of research on river deltas identify gaps in our knowledge of delta behavior and the tools required to fill them in.
This Week: From EPA Enforcement to Underwater Eruptions
Authors:   AGU
Published: April 2020

What Earth and space science stories are we recommending this week?
Heat Flow on the U.S. Beaufort Margin, Arctic Ocean: Implications for Ocean Warming, Methane Hydrate Stability, and Regional Tectonics
Authors: Hornbach Matthew J. , Harris Robert N. , Phrampus Benjamin J.
Published: April 2020

Results from the first focused heat flow study on the U.S. Beaufort Margin provide insight into decadal‐scale Arctic Ocean temperature change and raise new questions regarding Beaufort Margin evolution. This study measured heat flow using a 3.5‐m Lister probe at 103 sites oriented along four north‐south transects perpendicular to the ~700‐km long U.S. Beaufort Margin. The new heat flow measurements, corrected both for seasonal ocean temperature fluctuations and bathymetric effects, reveal low average heat flow values (~35 mW/m2) at seafloor depths of 300–900 m below sea level (mbsl) and anomalously high (~80 mW/m2) values at seafloor depths of >1,000 mbsl, near the predicted continent‐ocean transition. Anomalously low heat flow values measured on the upper margin are consistent with previous studies suggesting decadal‐scale ocean temperature warming to ~500 mbsl. Our results, however, indicate this ocean warming likely extends to depths as great at 900 mbsl—400 m deeper than previous studies suggest—implying widespread, ongoing, methane hydrate destabilization across much of the U.S. Beaufort Margin. The cause of the anomalously high heat flow values observed at seafloor depths >1,000 at the continent‐ocean transition is unclear. We suggest three candidate processes: (1) higher heat production and lower thermal conductivity on the margin edge due to the thickest sedimentary cover at the ocean‐continent transition, (2) seaward migrating subsurface advection, and (3) possible fault‐reactivation at the northern boundary of the Alaskan Microplate.
Serpentinization, Deformation, and Seismic Anisotropy in the Subduction Mantle Wedge
Authors: Horn Charis , Bouilhol Pierre , Skemer Philip
Published: April 2020

Antigorite is a hydrous sheet silicate with strongly anisotropic seismic and rheological properties. Hydrous minerals such as antigorite have been invoked to explain numerous geologic observations within subduction zones including intermediate‐depth earthquakes, arc volcanism, the persistent weakness of the subduction interface, trench‐parallel S wave splitting, and episodic tremor and slip. To understand how the presence of antigorite‐bearing rocks affects observations of seismic anisotropy, three mylonites from the Kohistan palaeo‐island arc in Pakistan were analysed using electron backscatter diffraction. A fourth sample, which displayed optical evidence for crystallographically controlled replacements of olivine, was also investigated using electron backscatter diffraction to identify potential topotactic relationships. The resulting data were used to model the bulk seismic properties of antigorite‐rich rocks. The mylonitic samples exhibit incredibly strong bulk anisotropy (10–20% for the antigorite + olivine). Within the nominally undeformed protomylonite, two topotactic relationships were observed: (1) (010)ant//(100)ol with [100]ant//[001]ol and (2) (010)ant//(100)ol with [100]ant//[010]ol. However, the strength of a texture formed by topotactic replacement is markedly weaker than the strength of the textures observed in mylonitic samples. Since antigorite is thought to be rheologically weak, we hypothesise that microstructures formed from topotactic reactions will be progressively overprinted as deformation is localised in regions with greater percentages of serpentine. Regions of highly sheared serpentine, therefore, have the potential to strongly influence seismic wave speeds in subduction settings. The presence of deformed antigorite in a dipping structure is one explanation for observations of both the magnitude and splitting pattern of seismic waves in subduction zones.
Evidence of Bermuda Hot and Wet Upwelling From Novel Three‐Dimensional Global Mantle Electrical Conductivity Image
Authors: Li Shiwen , Weng Aihua , Zhang Yanhui , Schultz Adam , Li Yabin , Tang Yu , Zou Zonglin , Zhou Zikun
Published: April 2020

A model of electrical conductivity in the mid–mantle transition zone was obtained with improved constraints. An L1‐norm regularization inversion algorithm is proposed here that reduces the influence of noisy data on three‐dimensional geomagnetic depth sounding inversion from C‐responses. Here the regularization is implemented by using an L1‐norm to measure the predicted data error, which is normalized by the C‐response covariance, but an L2‐norm is used to measure the regularization term associated with model parameters. The limited‐memory quasi‐Newton method (L‐BFGS) is used to invert for the three‐dimensional electrical conductivity model. The model is discretized by curved rectangular prisms in spherical coordinates. Sensitivity tests show that for good‐quality data contaminated by Gaussian noise, L1 inversion, which could perform as well as L2 inversion, can adequately recover the main features of the electrical conductivity structure within the region of data coverage. When data errors are drawn from an exponential distribution, L1 inversion obtains relatively reliable reconstruction of the electrical structure, even when the noise level is comparable to that of actual C‐responses. C‐responses from 129 low‐latitude and midlatitude geomagnetic observatories are inverted using L1‐norm minimization of the data error. The resulting model reveals an electrically conductive feature in the lower mantle transition zone and upper lower mantle that is broadly coincident with that found in previous studies. The reduced influence of data with large variances on L1‐norm misfits, along with inclusion of responses estimated from more observatories, makes L1 inversion more clearly identify these deep conductive features while identifying previously obscured anoconductive zones. A feature of particular interest is the high electrical conductivity anomaly beneath the Bermuda‐Sargasso Sea region in the mid–mantle transition zone and the uppermost lower mantle. Rock physics analysis indicates that the anomaly is most possibly caused by the wet upwelling material with excessive ~650 K higher temperature, suggesting a narrow tail with a broad head.
A New Data Set of Thermospheric Molecular Oxygen From the Global‐scale Observations of the Limb and Disk (GOLD) Mission
Authors: Lumpe J. D. , McClintock W. E. , Evans J. S. , Correira J. , Veibell V. , Beland S. , Eastes R.
Published: April 2020

The Global‐scale Observations of the Limb and Disk (GOLD) instrument was launched on 25 January 2018 onboard the SES‐14 commercial communications satellite and began nominal science operations in October 2018. Operating from geostationary orbit at 47.5°W longitude, GOLD images the Earth's thermosphere and ionosphere in the far‐ultraviolet (132–162 nm), measuring critical geophysical parameters by continuously scanning the Earth's disk and limb 18 hours per day. GOLD also performs stellar occultation measurements using bright type O and B stars. Up to 10 occultations per day are obtained at latitudes ranging from 60°S to 45°N and two fixed longitudes, ~33°E and ~128°W. The occultation data provide a direct measurement of atmospheric absorption in the O2 Schumann Runge continuum, which is used to retrieve the O2 density profile from 130‐ to 200‐km altitude. This paper describes the GOLD occultation measurement technique and the operational retrieval algorithm used to derive the Level 2 O2DEN data product. The spatial, temporal, and local time sampling of the GOLD O2 data product is summarized, and the data quality, retrieval errors, and validation plans are discussed. Occultations are observed under both daytime and nighttime conditions, providing the O2 density over a complete range of local times. GOLD retrievals have an estimated precision of 10% and a vertical resolution of 5–10 km, depending on altitude. The data have sufficient accuracy and resolution to provide scientifically useful constraints on the O2 abundance and variability. Initial comparisons show qualitative agreement, but also notable differences, between the GOLD O2 data and the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar (NRLMSISE‐00) empirical model predictions.
Role of M1-polarized tumor-associated macrophages in the prognosis of advanced ovarian cancer patients
Authors: Macciò Antonio , Gramignano Giulia , Cherchi Maria Cristina , Tanca Luciana , Melis Luca , Madeddu Clelia
Published: April 2020

The identification of prognostic and predictive markers is crucial for choosing the most appropriate management method for ovarian cancer patients. We aimed to assess the prognostic role of tumor-associated macrophage (TAM) polarization in advanced ovarian cancer patients. We carried out a prospective observational study that included 140 consecutive patients with advanced-stage high-grade serous ovarian cancer as well as patients with other histotypes of ovarian cancer and patients with ovarian metastasis from other sites between June 2013 and December 2018. Patients were enrolled at the time of laparoscopic surgery before receiving any antineoplastic treatment. We found that patients with high-grade serous papillary ovarian cancers had a prevalence of M1 TAMs, a higher M1/M2 ratio, and a longer overall survival (OS) and progression-free survival (PFS) than other patients. Regression analysis confirmed that there was a significant positive association between the M1/M2 ratio and an improved OS, PFS and platinum-free interval (PFI), both in the entire population and in patients stratified according to tumor type and initial surgery. Kaplan-Meier analysis was performed after the patients were divided into 2 groups according to the median M1/M2 ratio and revealed that patients with a high M1/M2 ratio had a higher OS, PFS and PFI than those with a low M1/M2 ratio. In conclusion, the prognostic and predictive role of TAM polarization in the tumor microenvironment could be of great clinical relevance and may allow the early identification of patients who are likely to respond to therapy. Further studies in a larger prospective sample are warranted.
Theoretical evaluation of inter-ion and intra-ion isotope effects in fragmentation: insights into chlorine and bromine isotope effects of halogenated organic compounds occurring in electron ionization mass spectrometry
Authors: Tang Caiming , Tan Jianhua , Fan Yujuan , Zheng Ke , Yu Zhiqiang , Peng Xianzhi
Published: April 2020

A theoretical basis is proposed for elucidating the details and implications of chlorine and bromine isotope effects in dehalogenation reactions.
Alleviating effects of noni fruit polysaccharide on hepatic oxidative stress and inflammation in rats under a high-fat diet and its possible mechanisms
Authors: Yang Xiaobing , Mo Wenjing , Zheng Chuanjin , Li Wenzhi , Tang Jian , Wu Xiaoyong
Published: April 2020

Non-alcoholic fatty liver disease is associated with gut microbiota, oxidative stress, and inflammation.
Development and research of mathematical model of current transformer reproducing magnetic hysteresis based on Preisach theory
Authors: Andreev Mikhail , Suvorov Alexey , Ruban Nikolay , Ufa Ruslan , Gusev Alexander , Askarov Alisher , Kievets Anton
Published: April 2020

Due to increasing complexity of power systems the task of ensuring adequate operation of relay protection becomes more urgent. Detailed mathematical models of relay protection together with modern power system simulators are proposed to be used as a solution of this problem. At the same time, the adequate simulation of instrumental transformers, in particular the magnetization process of the core, is very important because the waveform of signals controlled by relay protection largely determined by transducers' errors. The developed mathematical model of current transformer reproducing the magnetic hysteresis in accordance with the Preisach theory is presented in the paper. Unlike other similar models, the Preisach' particle distribution function in the developed model is based not on the reference typical magnetizing curves, but on the volt–ampere characteristic of current transformer. This approach is better applicable in practice, since typical magnetization curves are not always available and become less relevant during transformer operation. There are presented the results of impact assessment of different types and values of burden on current transformer operation and comparison of the implemented model with existing methods of magnetization and hysteresis modeling. The adequate behavior of the developed model has been confirmed by the research.
Structured approach to downsize data administration and improve fault recognition accuracy for large power systems
Authors: Jana Subhra , De Abhinandan
Published: April 2020

This study presents a structured pattern‐recognition framework for fault pattern recognition in large power systems. The main novelty of the study is in the efficient use of techniques to reduce data acquisition and administration requirements and limiting the computational overhead without sacrificing fault recognition accuracy and reliability. Optimal fault recorder placement based on the criterion of ‘network observability’ has been suggested for real‐time monitoring of voltage and current at strategic network locations. An efficient feature‐screening method has been adopted to select only the recorders whose data are assessed to be critical for fault recognition. ‘Wavelet’‐based multi‐resolution decomposition facilitated the extraction of important fault features from recorded waveforms and feature‐screening was leveraged, once more, to eliminate irrelevant features to ensure that the data presented to the fault classifier is precise and feature‐enriched. Random forest ensemble classifier was used for final class prediction and location of faults through voting of several individual learners to achieve high prediction accuracy. The proposed approach proved to be computationally efficient and consistent when tested on IEEE 118‐bus system.
Research on the harmonic in new continuous cable traction power supply system and its transmission characteristic
Authors: Zhang Liyan , Liang Shiwen , Li Xin
Published: April 2020

This study does research on resonance and harmonic transmission problems in a new continuous cable traction power supply system (CCTPSS), CCTPSS can realise long‐distance co‐phase power supply and effectively reduce phase separation and is applicable for extended power supply in areas with the weak power grid. Firstly, the system structure is introduced, a cable traction network is divided into three kinds of subnets for its complicated topology and huge system scale. The equivalent circuit model and mathematical model of each subnet are established with distribution parameters, especially the cable capacitance effect be considered. Then, according to the two‐port network analysis theory, the system equivalent circuit is constructed by considering the electrical connection relationship, system harmonic impedance expression is calculated. Resonance influence factors and harmonic transmission mechanisms are analysed. Finally, theoretical analysis validity is verified in simulation; harmonic transmission characteristics CCTPSS including traction cable and overhead catenary, are studied. The new system shows better resonance performance compared with the existing AT traction power supply system.
Joint estimation of DOA and polarisation for radar signals based on dual‐polarised antenna array
Authors: Wu Jian , Zhu Xiaojin , He Xiaoming , Gao Zhiyuan , Fang Yubin
Published: April 2020

To apply polarisation information of radar signal in radar reconnaissance equipment, a joint estimation algorithm of the radar signal direction of arrival (DOA) and polarisation parameters based on dual‐polarisation antenna array has been researched in this study. The mathematical model of dual‐polarised circular array has been given, and the joint estimation method of DOA and polarisation parameters for radar signal based on multiple signal classification (MUSIC) algorithm has been analysed. To overcome the shortcomings such as high calculation cost for the MUSIC algorithm, the DOA‐matrix algorithm has been presented. DOA‐matrix algorithm can effectively distinguish the radar signals with different polarisation states in the same direction by use of eigen‐decomposition of the DOA‐matrix. Through matrix correlation calculation, spectral peak search has been avoided, and the computational cost and algorithm complexity are greatly reduced. Finally, the feasibility of the DOA‐matrix algorithm has been simulated and analysed. The simulation results show that the DOA‐matrix algorithm can effectively complete the joint estimation of DOA and polarisation parameters for radar signal. The running time reaches millisecond level, which has a strong application value in engineering.
Improved alternating projection algorithm for pattern synthesis with dual polarised conformal arrays
Authors: Liu Chao , Li Chuan , Yang Bo
Published: April 2020

In this study, an improved alternating projection algorithm is presented for the pattern synthesis of a dual‐polarised conformal array. An extra desired pattern is introduced to find an appropriate solution in the process of projecting the desired solution set to the feasible solution set. Virtual interferences are introduced to modify the solution iteratively based on the deviation between the obtained and desired pattern. Finally, the authors' algorithm is applied to dual‐polarised conformal arrays and can achieve a suitable solution set between the predefined upper and lower bounds, which can synthesise both orthogonal polarisation components of the array pattern more effectively. Simulation examples are presented to verify the validity of the proposed algorithm.