bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polygonal Eyewall Asymmetries During the Rapid Intensification of Hurricane Michael (2018)
Authors: Cha Ting‐Yu , Bell Michael M. , Lee Wen‐Chau , DesRosiers Alexander J. 
Published: July 2020

AbstractPolygonal eyewall asymmetries of Hurricane Michael (2018) during rapid intensification (RI) are analyzed from ground‐based single Doppler radar. Here, we present the first observational evidence of the evolving wind field of a polygonal eyewall during RI to Category 5 intensity by deducing the axisymmetric and asymmetric winds at 5‐min intervals. Spectral time decomposition of the retrieved tangential wind structure shows quantitative evidence of low (1–4) azimuthal wavenumbers with propagation speeds that are consistent with linear wave theory on a radial vorticity gradient, suggesting the presence of rapidly evolving vortex Rossby waves. Dual‐Doppler winds from the NOAA P‐3 Hurricane Hunter airborne radar provide further evidence of the three‐dimensional vortex structure that supports growth of asymmetries during RI. Both reflectivity and tangential wind fields show polygonal structure and propagate at similar speeds, suggesting a close coupling of the dynamics and the convective organization during the intensification.
Turbidity Hysteresis in an Estuary and Tidal River Following an Extreme Discharge Event
Authors: Ralston David K. , Yellen Brian , Woodruff Jonathan D. , Fernald Sarah 
Published: July 2020

AbstractNonlinear turbidity‐discharge relationships are explored in the context of sediment sourcing and event‐driven hysteresis using long‐term (≥12‐year) turbidity observations from the tidal freshwater and saline estuary of the Hudson River. At four locations spanning 175 km, turbidity generally increased with discharge but did not follow a constant log‐log dependence, in part due to event‐driven adjustments in sediment availability. Following major sediment inputs from extreme precipitation and discharge events in 2011, turbidity in the tidal river increased by 20–50% for a given discharge. The coherent shifts in the turbidity‐discharge relationship along the tidal river over the subsequent 2 years suggest that the 2011 events increased sediment availability for resuspension. In the saline estuary, changes in the sediment‐discharge relationship were less apparent after the high discharge events, indicating that greater background turbidity due to internal sources make event‐driven inputs less important in the saline estuary at interannual time scales.
Subsurface Weathering Revealed in Hillslope‐Integrated Porosity Distributions
Authors: Callahan Russell P. , Riebe Clifford S. , Pasquet Sylvain , Ferrier Ken L. , Grana Dario , Sklar Leonard S. , Taylor Nicholas J. , Flinchum Brady A. , Hayes Jorden L. , Carr Bradley J. , Hartsough Peter C. , O'Geen Anthony T. , Holbrook W. Steven 
Published: July 2020

AbstractSubsurface weathering has traditionally been measured using cores and boreholes to quantify vertical variations in weathered material properties. However, these measurements are typically available at only a few, potentially unrepresentative points on hillslopes. Geophysical surveys, conversely, span many more points and, as shown here, can be used to obtain a representative, site‐integrated perspective on subsurface weathering. Our approach aggregates data from multiple seismic refraction surveys into a single frequency distribution of porosity and depth for the surveyed area. We calibrated the porosities at a site where cores are coincident with seismic refraction surveys. Modeled porosities from the survey data match measurements at the core locations but reveal a frequency distribution of porosity and depth that differs markedly from the cores. Our results highlight the value of using the site‐integrated perspective obtained from the geophysical data to quantify subsurface weathering and water‐holding capacity.
High‐Spatiotemporal Resolution Observations of Jupiter Lightning‐Induced Radio Pulses Associated With Sferics and Thunderstorms
Authors: Imai Masafumi , Wong Michael H. , Kolmašová Ivana , Brown Shannon T. , Santolík Ondřej , Kurth William S. , Hospodarsky George B. , Bolton Scott J. , Levin Steven M. 
Published: July 2020

AbstractJupiter lightning discharges produce various kinds of phenomena including radio wave pulses at different frequencies. On 6 April 2019, the Juno Waves instrument captured an extraordinary series of radio pulses at frequencies below 150 kHz on timescales of submilliseconds. Quasi‐simultaneous multi‐instrument data show that the locations of their magnetic footprints are very close to the locations of ultrahigh frequency (UHF) sferics recorded by the Juno MWR instrument. Hubble Space Telescope images show that the signature of active convection includes cloud‐free clearings, in addition to the convective towers and deep water clouds that were also recognized in previous spacecraft observations of lightning source regions. Furthermore, the detections of 17 very low frequency/low‐frequency (VLF/LF) radio pulses suggest a minimum duration of lightning processes on the order of submilliseconds. These observations provide new constraints on the physical properties of Jupiter lightning.
Critical Zone Storage Controls on the Water Ages of Ecohydrological Outputs
Authors: Kuppel S. , Tetzlaff D. , Maneta M. P. , Soulsby C. 
Published: July 2020

AbstractSpatially explicit knowledge of the origins of water resources for ecosystems and rivers is challenging when using tracer data alone. We use simulations from a spatially distributed model calibrated by extensive ecohydrological data sets in a small, energy‐limited catchment, where hillslope‐riparian dynamics are broadly representative of humid boreal headwater catchments that are experiencing rapid environmental transition. We hypothesize that in addition to wetness status, landscape heterogeneity modulates the water pathways that sustain ecosystem function and streamflows. Simulations show that catchment storage inversely controls stream water ages year‐round, but only during the drier seasons for transpiration and soil evaporation. The ages of these evaporative outputs depend much less on wetness status in the oft‐saturated riparian soils than on the freely draining hillslopes that subsidize them. This work highlights the need to consider local dynamics and time‐changing lateral heterogeneities when interpreting the ages, and thus the vulnerability, of water resources feeding streams and ecosystems in landscapes.
Observation of High‐Energy Electrons Precipitated by NWC Transmitter From PROBA‐V Low‐Earth Orbit Satellite
Authors: Cunningham G. S. , Botek E. , Pierrard V. , Cully C. , Ripoll J.‐F. 
Published: July 2020

AbstractThe very low‐frequency transmitter in the Northwest Cape of Australia (NWC) has previously been observed to pitch‐angle scatter electrons with energies from 30–400 keV, creating enhanced fluxes measured by low‐Earth orbiting (LEO) satellites. Here we use observations from the Energetic Particle Telescope on PROBA‐V. We compare the measured flux, as a function of local magnetic field strength, when the NWC transmitter is “on” versus “off,” and find enhanced fluxes only when NWC is “on” and located on the nightside. The enhanced fluxes occur in the population gradually transitioning from “permanently trapped” to “quasi‐trapped.” We show that electrons up to 800 keV, substantially higher energy than previously studied, are scattered by resonant interactions with NWC to produce enhanced fluxes. The enhanced fluxes appear at multiple L‐shells for each energy channel, consistent with resonance conditions at distinct wave normal angles, that indicate ducted interactions at L < 1.55 and unducted interactions at L > 1.65.
The Effect of a Liquid Phase on Force Distribution During Deformation in a Granular System
Authors: Ladd Christopher R. , Reber Jacqueline E. 
Published: July 2020

AbstractTwo‐phase systems, where one phase is solid and the other is fluid, are widespread in nature. Examples include reservoir rocks holding vital fluids like water or petroleum, slurries of partially crystallized magmas, fluids migrating along faults filled with fault gouge, and even the semibrittle crust. Previous studies of two‐phase systems have shown that the fluid phase plays an important role in deformation localization and dynamics (e.g., Higashi & Sumita, 2009, https://doi.org/10.1029/2008JB005999; Reber et al., 2014, https://doi.org/10.1002/2014GL059832). Here, we present results from experiments investigating the influence of a fluid phase on force distribution in a granular media during simple shear. We use photoelastic polyurethane discs as the granular or solid phase and a linear viscous silicone as the fluid phase. The photoelastic property of the discs allows for direct observation and measurement of force magnitude and distribution. We compare the two‐phase experiments to granular experiments without silicone. The addition and percentage of the fluid phase has a strong impact on the force distribution and the overall force chain orientations. In the two‐phase system, the force chains form parallel to the shear plane and only rotate to the principal stress direction with an increase in strain. Locally, the fluid phase can support forces and terminate force chains over an extended period of time. Our results are in line with findings from numerical studies investigating the formation of slow slip events, proposing that these events are the result of dynamic interactions between solid and viscous phases.
Rough Correlations: Meta‐Analysis of Roughness Measures in Gravel Bed Rivers
Authors: Chen Xingyu , Hassan Marwan A. , An Chenge , Fu Xudong 
Published: July 2020

AbstractBed roughness height (k) is a key parameter for velocity prediction in open‐channel flows. There is not yet a firm consensus about whether characteristic particle size D84 or
(standard deviation of the channel thalweg) better describes k in gravel bed streams. A data set of 1,788 flume and 713 field measurements with a wide range of channel morphologies and flow conditions were compiled to test whether D84 or
is a better descriptor of k and to explore the influence of several controls on flow resistance variation. Tests were performed using four well‐known flow resistance equations. The results consistently show that
outperforms D84 in predicting velocity and the Smart and Jäggi equation, with
as k, outperforms other equations. The data set was grouped based on R/k (R is the hydraulic radius), channel morphologies, and study sites.
performs better than D84 as a measure of k in all morphologies and much better for channels with large instream wood. The analysis shows R/k is a major control on resistance variation as
contains more site‐specific information like bed structure. The topography measurements for step‐pool channels should at least contain measurements on key roughness elements like steps. For gravel‐dune or plane‐bed channels, the proper resolution should be higher than 1/2 dune wavelength and 2D84, respectively. The choice of proper reach length relates to both R/k and roughness type. Further, hydraulic geometry functions with either D84 or
as k are proposed, and the relation between the two metrics is discussed.
A scalable method for preparing Cu electrocatalysts that convert CO2 into C2+ products
Authors: Kim Taehee , Palmore G. Tayhas R. 
Published: July 2020

AbstractDevelopment of efficient catalysts for selective electroreduction of CO2 to high-value products is essential for the deployment of carbon utilization technologies. Here we present a scalable method for preparing Cu electrocatalysts that favor CO2 conversion to C2+ products with faradaic efficiencies up to 72%. Grazing-incidence X-ray diffraction data confirms that anodic halogenation of electropolished Cu foils in aqueous solutions of KCl, KBr, or KI creates surfaces of CuCl, CuBr, or CuI, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies show that significant changes to the morphology of Cu occur during anodic halogenation and subsequent oxide-formation and reduction, resulting in catalysts with a high density of defect sites but relatively low roughness. This work shows that efficient conversion of CO2 to C2+ products requires a Cu catalyst with a high density of defect sites that promote adsorption of carbon intermediates and C–C coupling reactions while minimizing roughness.
Dually modulated photonic crystals enabling high-power high-beam-quality two-dimensional beam scanning lasers
Authors: Sakata Ryoichi , Ishizaki Kenji , De Zoysa Menaka , Fukuhara Shin , Inoue Takuya , Tanaka Yoshinori , Iwata Kintaro , Hatsuda Ranko , Yoshida Masahiro , Gelleta John , Noda Susumu 
Published: July 2020

AbstractMechanical-free, high-power, high-beam-quality two-dimensional (2D) beam scanning lasers are in high demand for various applications including sensing systems for smart mobility, object recognition systems, and adaptive illuminations. Here, we propose and demonstrate the concept of dually modulated photonic crystals to realize such lasers, wherein the positions and sizes of the photonic-crystal lattice points are modulated simultaneously. We show using nano-antenna theory that this photonic nanostructure is essential to realize 2D beam scanning lasers with high output power and high beam quality. We also fabricate an on-chip, circuit-driven array of dually modulated photonic-crystal lasers with a 10 × 10 matrix configuration having 100 resolvable points. Our device enables the scanning of laser beams over a wide range of 2D directions in sequence and in parallel, and can be flexibly designed to meet application-specific demands.
Heat and charge transport in H2O at ice-giant conditions from ab initio molecular dynamics simulations
Authors: Grasselli Federico , Stixrude Lars , Baroni Stefano 
Published: July 2020

AbstractThe impact of the inner structure and thermal history of planets on their observable features, such as luminosity or magnetic field, crucially depends on the poorly known heat and charge transport properties of their internal layers. The thermal and electric conductivities of different phases of water (liquid, solid, and super-ionic) occurring in the interior of ice giant planets, such as Uranus or Neptune, are evaluated from equilibrium ab initio molecular dynamics, leveraging recent progresses in the theory and data analysis of transport in extended systems. The implications of our findings on the evolution models of the ice giants are briefly discussed.
A rare variant of African ancestry activates 8q24 lncRNA hub by modulating cancer associated enhancer
Authors: Walavalkar Kaivalya , Saravanan Bharath , Singh Anurag Kumar , Jayani Ranveer Singh , Nair Ashwin , Farooq Umer , Islam Zubairul , Soota Deepanshu , Mann Rajat , Shivaprasad Padubidri V. , Freedman Matthew L. , Sabarinathan Radhakrishnan , Haiman Christopher A. , Notani Dimple 
Published: July 2020

AbstractGenetic variation at the 8q24 locus is linked with the greater susceptibility to prostate cancer in men of African ancestry. One such African ancestry specific rare variant, rs72725854 (A>G/T) (~6% allele frequency) has been associated with a ~2-fold increase in prostate cancer risk. However, the functional relevance of this variant is unknown. Here we show that the variant rs72725854 is present in a prostate cancer-specific enhancer at 8q24 locus. Chromatin-conformation capture and dCas9 mediated enhancer blocking establish a direct regulatory link between this enhancer and lncRNAs PCAT1, PRNCR1 and PVT1. The risk allele (‘T’) is associated with higher expression of PCAT1, PVT1 and c-myc in prostate tumors. Further, enhancer with the risk allele gains response to androgen stimulation by recruiting the transcription factor SPDEF whereas, non-risk alleles remain non-responsive. Elevated expression of these lncRNAs and c-myc in risk allele carriers may explain their greater susceptibility to prostate cancer.
Pre-initiation and elongation structures of full-length La Crosse virus polymerase reveal functionally important conformational changes
Authors: Arragain Benoît , Effantin Grégory , Gerlach Piotr , Reguera Juan , Schoehn Guy , Cusack Stephen , Malet Hélène 
Published: July 2020

AbstractBunyavirales is an order of segmented negative-strand RNA viruses comprising several life-threatening pathogens against which no effective treatment is currently available. Replication and transcription of the RNA genome constitute essential processes performed by the virally encoded multi-domain RNA-dependent RNA polymerase. Here, we describe the complete high-resolution cryo-EM structure of La Crosse virus polymerase. It reveals the presence of key protruding C-terminal domains, notably the cap-binding domain, which undergoes large movements related to its role in transcription initiation, and a zinc-binding domain that displays a fold not previously observed. We capture the polymerase structure at pre-initiation and elongation states, uncovering the coordinated movement of the priming loop, mid-thumb ring linker and lid domain required for the establishment of a ten-base-pair template-product RNA duplex before strand separation into respective exit tunnels. These structural details and the observed dynamics of key functional elements will be instrumental for structure-based development of polymerase inhibitors.
Supramolecular double-stranded Archimedean spirals and concentric toroids
Authors: Sasaki Norihiko , Mabesoone Mathijs F. J. , Kikkawa Jun , Fukui Tomoya , Shioya Nobutaka , Shimoaka Takafumi , Hasegawa Takeshi , Takagi Hideaki , Haruki Rie , Shimizu Nobutaka , Adachi Shin-ichi , Meijer E. W. , Takeuchi Masayuki , Sugiyasu Kazunori 
Published: July 2020

AbstractConnecting molecular-level phenomena to larger scales and, ultimately, to sophisticated molecular systems that resemble living systems remains a considerable challenge in supramolecular chemistry. To this end, molecular self-assembly at higher hierarchical levels has to be understood and controlled. Here, we report unusual self-assembled structures formed from a simple porphyrin derivative. Unexpectedly, this formed a one-dimensional (1D) supramolecular polymer that coiled to give an Archimedean spiral. Our analysis of the supramolecular polymerization by using mass-balance models suggested that the Archimedean spiral is formed at high concentrations of the monomer, whereas other aggregation types might form at low concentrations. Gratifyingly, we discovered that our porphyrin-based monomer formed supramolecular concentric toroids at low concentrations. Moreover, a mechanistic insight into the self-assembly process permitted a controlled synthesis of these concentric toroids. This study both illustrates the richness of self-assembled structures at higher levels of hierarchy and demonstrates a topological effect in noncovalent synthesis.
Rapid and high-resolution patterning of microstructure and composition in organic semiconductors using ‘molecular gates’
Authors: Perevedentsev Aleksandr , Campoy-Quiles Mariano 
Published: July 2020

AbstractPhotolithography has been a major enabling tool for miniaturisation of silicon devices that underpinned the electronics revolution. Rapid, high-resolution patterning of key material characteristics would, similarly, accelerate the advent of molecular electronics and photonics. Here we advance a versatile approach employing local diffusion of functional small-molecular compounds through a solution-processed ‘molecular gate’ interlayer. Diffusion is activated using laser light or solvent vapour jets―a process that can be finely modulated down to molecule-on-demand deposition precision with almost photolithographic resolution (<5 μm) and speeds (3 mm s–1). Examples of principal pattern types are presented including molecular conformation for integrated photonics; chain orientation for polarised security features and micro-engineered electronics; and doping with local conductivity values >3 S cm–1 for improved electronic devices. Finally, we demonstrate the unique capability for one-step patterning of multiple functionalities by spatially modulating composition in ternary blends, leading to locally tunable photoluminescence from blue to red.
Unimolecularly thick monosheets of vinyl polymers fabricated in metal–organic frameworks
Authors: Hosono Nobuhiko , Mochizuki Shuto , Hayashi Yuki , Uemura Takashi 
Published: July 2020

AbstractPolymers with two-dimensional (2D) network topologies are currently gaining significant attention due to their unique properties that originate from their regulated conformations. However, in contrast to conventional 1D- and 3D-networked macromolecules, the synthesis of such 2D networks provides challenges for polymer chemists because of the nature of the networking polymerisation reaction, which occurs in a spatially random fashion when conventional solution-phase synthesis is performed. Here we report a versatile synthesis of polymeric monosheets with unimolecularly thick networking architectures by exploiting the 2D nanospaces of metal–organic frameworks (MOFs) as reaction templates. Crosslinking radical polymerisation in the 2D nanospaces of pillared-layer-type MOFs affords monosheets of typical vinyl polymers and can be carried out on the gram scale. Remarkably, the prepared polymer monosheets are highly soluble in organic solvents and show atypical thermal and rheological properties that result from their 2D-regulated conformations that cannot be adopted by their 1D or 3D analogues.
A transition to sustainable ocean governance
Authors: Brodie Rudolph Tanya , Ruckelshaus Mary , Swilling Mark , Allison Edward H. , Österblom Henrik , Gelcich Stefan , Mbatha Philile 
Published: July 2020

AbstractHuman wellbeing relies on the Biosphere, including natural resources provided by ocean ecosystems. As multiple demands and stressors threaten the ocean, transformative change in ocean governance is required to maintain the contributions of the ocean to people. Here we illustrate how transition theory can be applied to ocean governance. We demonstrate how current economic and social systems can adapt to existing pressures and shift towards ocean stewardship through incorporation of niche innovations within and across economic sectors and stakeholder communities. These novel approaches support an emergent but purposeful transition and suggest a clear path to a thriving and vibrant relationship between humans and the ocean. Oceans provide important natural resources, but the management and governance of the ocean is complex and the ecosystem is suffering as a result. The authors discuss current barriers to sustainable ocean governance and suggest pathways forward.
Calcium isotopic ecology of Turkana Basin hominins
Authors: Martin Jeremy E. , Tacail Théo , Braga José , Cerling Thure E. , Balter Vincent 
Published: July 2020

AbstractDiet is a major driver of hominin evolution, but most of the geochemical evidence relies on carbon isotopes (δ13C). Here, we report enamel stable calcium isotope (δ44/42Ca) values against δ13C values for several hominins and co-existing primates in the Turkana Basin area, circa 4 to 2 Ma. Australopithecus anamensis clusters with mammal browsers, Kenyanthropus platyops is distinct from A. anamensis in foraging into more open environments and the coexisting Theropithecus brumpti encompasses both the grazer and omnivore/carnivore domains. Early Homo is remarkable for its wide distribution in δ44/42Ca values, possibly reflecting omnivorous and opportunistic preferences. Paranthropus boisei is uniquely distributed in the δ13C versus δ44/42Ca iso-space being distinct from all other hominins from the Turkana Basin area as well as from the co-existing Theropithecus oswaldi. Several hypotheses are explored to discuss the unique δ44/42Ca values of Paranthropus boisei including significant differences observed with δ44/42Ca values recently reported for P. robustus from South Africa, questioning the monophyly of this genus.