bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of a numerical model to reproduce event‐scale erosion and deposition distributions in a braided river
Authors: Williams R. D. , Measures R. , Hicks D. M. , Brasington J. 
Published: June 2016

AbstractNumerical morphological modeling of braided rivers, using a physics‐based approach, is increasingly used as a technique to explore controls on river pattern and, from an applied perspective, to simulate the impact of channel modifications. This paper assesses a depth‐averaged nonuniform sediment model (Delft3D) to predict the morphodynamics of a 2.5 km long reach of the braided Rees River, New Zealand, during a single high‐flow event. Evaluation of model performance primarily focused upon using high‐resolution Digital Elevation Models (DEMs) of Difference, derived from a fusion of terrestrial laser scanning and optical empirical bathymetric mapping, to compare observed and predicted patterns of erosion and deposition and reach‐scale sediment budgets. For the calibrated model, this was supplemented with planform metrics (e.g., braiding intensity). Extensive sensitivity analysis of model functions and parameters was executed, including consideration of numerical scheme for bed load component calculations, hydraulics, bed composition, bed load transport and bed slope effects, bank erosion, and frequency of calculations. Total predicted volumes of erosion and deposition corresponded well to those observed. The difference between predicted and observed volumes of erosion was less than the factor of two that characterizes the accuracy of the Gaeuman et al. bed load transport formula. Grain size distributions were best represented using two φ intervals. For unsteady flows, results were sensitive to the morphological time scale factor. The approach of comparing observed and predicted morphological sediment budgets shows the value of using natural experiment data sets for model testing. Sensitivity results are transferable to guide Delft3D applications to other rivers.
Geodetically constrained models of viscoelastic stress transfer and earthquake triggering along the North Anatolian fault
Authors: DeVries Phoebe M. R. , Krastev Plamen G. , Meade Brendan J. 
Published: June 2016

AbstractOver the past 80 years, 8 MW > 6.7 strike‐slip earthquakes west of 40° longitude have ruptured the North Anatolian fault (NAF) from east to west. The series began with the 1939 Erzincan earthquake in eastern Turkey, and the most recent 1999 MW = 7.4 Izmit earthquake extended the pattern of ruptures into the Sea of Marmara in western Turkey. The mean time between seismic events in this westward progression is 8.5 ± 11 years (67% confidence interval), much greater than the timescale of seismic wave propagation (seconds to minutes). The delayed triggering of these earthquakes may be explained by the propagation of earthquake‐generated diffusive viscoelastic fronts within the upper mantle that slowly increase the Coulomb failure stress change (
CFS) at adjacent hypocenters. Here we develop three‐dimensional stress transfer models with an elastic upper crust coupled to a viscoelastic Burgers rheology mantle. Both the Maxwell (ηM = 4 × 1018−1 × 1019 Pa s) and Kelvin (ηK = 1 × 1018−1 × 1019 Pa s) viscosities are constrained by studies of geodetic observations before and after the 1999 Izmit earthquake. We combine this geodetically constrained rheological model with the observed sequence of large earthquakes since 1939 to calculate the time evolution of
CFS changes along the North Anatolian fault due to viscoelastic stress transfer. Apparent threshold values of mean
CFS at which the earthquakes in the eight decade sequence occur are between ∼0.02 to ∼3.15 MPa and may exceed the magnitude of static
CFS values by as much as 177%. By 2023, we infer that the mean time‐dependent stress change along the northern NAF strand in the Marmara Sea near Istanbul, which may have previously ruptured in 1766, may reach the mean apparent time‐dependent stress thresholds of the previous NAF earthquakes.
The electric wind of Venus: A global and persistent “polar wind”‐like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions
Authors: Collinson Glyn A. , Frahm Rudy A. , Glocer Alex , Coates Andrew J. , Grebowsky Joseph M. , Barabash Stas , Domagal‐Goldman Shawn D. , Fedorov Andrei , Futaana Yoshifumi , Gilbert Lin K. , Khazanov George , Nordheim Tom A. , Mitchell David , Moore Thomas E. , Peterson William K. , Winningham John D. , Zhang Tielong L. 
Published: June 2016

AbstractUnderstanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an “ambipolar” electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water‐group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an “electric wind” must be considered when studying the evolution and potential habitability of any planet in any star system.
Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics
Authors: Park Jae‐Hyoung , Chang Kyung‐Il , Nam SungHyun 
Published: June 2016

AbstractA 6 year long current measurement at a buoy station off the middle east coast of Korea reveals an equatorward reversal of coastal current in summer opposing poleward local wind stress and offshore boundary current. The current reversal extends about 40 km offshore from the coast and is concurrent with warming and freshening of water column. Estimates of the depth‐averaged alongshore momentum balance suggest a major balance between the alongshore pressure gradient and the lateral friction. Sources of the pressure gradient for the summertime current reversal are identified as the alongshore buoyancy gradient driven by the wind curl gradient and the prevalence of warmer and lower salinity water in the north. Alongshore pressure gradient and velocity induced by the wind curl gradient are quantified, which yields the observed seasonal current reversal.
Evidence for the release of long‐term tectonic strain stored in continental interiors through intraplate earthquakes
Authors: Craig T. J. , Calais E. , Fleitout L. , Bollinger L. , Scotti O. 
Published: June 2016

AbstractThe occurrence of large earthquakes in stable continental interiors challenges the applicability of the classical steady state “seismic cycle” model to such regions. Here we shed new light onto this issue using as a case study the cluster of large reverse faulting earthquakes that occurred in Fennoscandia at 11–9 ka, triggered by the removal of the ice load during the final phase of regional deglaciation. We show that these reverse‐faulting earthquakes occurred at a time when the horizontal strain rate field was extensional, which implies that these events did not release horizontal strain that was building up at the time but compressional strain that had been accumulated and stored elastically in the lithosphere over timescales similar to or longer than a glacial cycle. We argue that the tectonically stable continental lithosphere can store elastic strain on long timescales, the release of which may be triggered by rapid, local transient stress changes caused by surface mass redistribution, resulting in the occurrence of intermittent intraplate earthquakes.
Spatial variations in fault friction related to lithology from rupture and afterslip of the 2014 South Napa, California, earthquake
Authors: Floyd Michael A. , Walters Richard J. , Elliott John R. , Funning Gareth J. , Svarc Jerry L. , Murray Jessica R. , Hooper Andy J. , Larsen Yngvar , Marinkovic Petar , Bürgmann Roland , Johanson Ingrid A. , Wright Tim J. 
Published: June 2016

AbstractFollowing earthquakes, faults are often observed to continue slipping aseismically. It has been proposed that this afterslip occurs on parts of the fault with rate‐strengthening friction that are stressed by the main shock, but our understanding has been limited by a lack of immediate, high‐resolution observations. Here we show that the behavior of afterslip following the 2014 South Napa earthquake in California varied over distances of only a few kilometers. This variability cannot be explained by coseismic stress changes alone. We present daily positions from continuous and survey GPS sites that we remeasured within 12 h of the main shock and surface displacements from the new Sentinel‐1 radar mission. This unique geodetic data set constrains the distribution and evolution of coseismic and postseismic fault slip with exceptional resolution in space and time. We suggest that the observed heterogeneity in behavior is caused by lithological controls on the frictional properties of the fault plane.
Potential tropical Atlantic impacts on Pacific decadal climate trends
Authors: Chikamoto Y. , Mochizuki T. , Timmermann A. , Kimoto M. , Watanabe M. 
Published: June 2016

AbstractThe tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere‐ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three‐dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low‐frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.
A Rossby whistle: A resonant basin mode observed in the Caribbean Sea
Authors: Hughes Chris W. , Williams Joanne , Hibbert Angela , Boening Carmen , Oram James 
Published: June 2016

AbstractWe show that an important source of coastal sea level variability around the Caribbean Sea is a resonant basin mode. The mode consists of a baroclinic Rossby wave which propagates westward across the basin and is rapidly returned to the east along the southern boundary as coastal shelf waves. Almost two wavelengths of the Rossby wave fit across the basin, and it has a period of 120 days. The porous boundary of the Caribbean Sea results in this mode exciting a mass exchange with the wider ocean, leading to a dominant mode of bottom pressure variability which is almost uniform over the Grenada, Venezuela, and Colombia basins and has a sharp spectral peak at 120 day period. As the Rossby waves have been shown to be excited by instability of the Caribbean Current, this resonant mode is dynamically equivalent to the operation of a whistle.
Simultaneous storm time equatorward and poleward large‐scale TIDs on a global scale
Authors: Habarulema John Bosco , Katamzi Zama Thobeka , Yizengaw Endawoke , Yamazaki Yosuke , Seemala Gopi 
Published: June 2016

AbstractWe report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground‐based magnetometer observations and available low‐latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.
Assessing the impact of vertical land motion on twentieth century global mean sea level estimates
Authors: Hamlington B. D. , Thompson P. , Hammond W. C. , Blewitt G. , Ray R. D. 
Published: June 2016

AbstractNear‐global and continuous measurements from satellite altimetry have provided accurate estimates of global mean sea level in the past two decades. Extending these estimates further into the past is a challenge using the historical tide gauge records. Not only is sampling nonuniform in both space and time, but tide gauges are also affected by vertical land motion (VLM) that creates a relative sea level change not representative of ocean variability. To allow for comparisons to the satellite altimetry estimated global mean sea level (GMSL), typically the tide gauges are corrected using glacial isostatic adjustment (GIA) models. This approach, however, does not correct other sources of VLM that remain in the tide gauge record. Here we compare Global Positioning System (GPS) VLM estimates at the tide gauge locations to VLM estimates from GIA models, and assess the influence of non‐GIA‐related VLM on GMSL estimates. We find that the tide gauges, on average, are experiencing positive VLM (i.e., uplift) after removing the known effect of GIA, resulting in an increase of 0.24 ± 0.08 mm yr−1 in GMSL trend estimates from 1900 to present when using GPS‐based corrections. While this result is likely dependent on the subset of tide gauges used and the actual corrections used, it does suggest that non‐GIA VLM plays a significant role in twentieth century estimates of GMSL. Given the relatively short GPS records used to obtain these VLM estimates, we also estimate the uncertainty in the GMSL trend that results from limited knowledge of non‐GIA‐related VLM.
A comparative study of wave‐current interactions over the eastern Canadian shelf under severe weather conditions using a coupled wave‐circulation model
Authors: Wang Pengcheng , Sheng Jinyu 
Published: June 2016

AbstractA coupled wave‐circulation model is used to examine interactions between surface gravity waves and ocean currents over the eastern Canadian shelf and adjacent deep waters during three severe weather events. The simulated significant wave heights (SWHs) and peak wave periods reveal the importance of wave‐current interactions (WCI) during and after the storm. In two fast‐moving hurricane cases, the maximum SWHs are reduced by more than 11% on the right‐hand side of the storm track and increased by about 5% on the left‐hand side due to different WCI mechanisms on waves on two sides of the track. The dominate mechanisms of the WCI on waves include the current‐induced modification of wind energy input to the wave generation, and current‐induced wave advection and refraction. In the slow‐moving winter storm case, the effect of WCI decreases the maximum SWHs on both sides of the storm track due to different results of the current‐induced wave advection, which is affected greatly by the storm translation speed. The simulated sea surface temperature (SST) cooling induced by hurricanes and SST warming induced by the winter storm are also enhanced (up to 1.2°C) by the WCI mechanisms on circulation and hydrography. The 3D wave forces can affect water columns up to 200 m in all three storm cases. By comparison, the effect of breaking wave‐induced mixing in the ocean upper layer is more important under strong stratification conditions in two hurricane cases than under weak stratification conditions in the winter storm case.
Dose–response between pedometer assessed physical activity, functional fitness, and fatness in healthy adults aged 50–80 years
Authors: Duncan Michael J. , Minatto Giseli , Wright Sheila Leddington 
Published: June 2016

ObjectivesThis study examined dose–response relationships of walking with multiple aspects of physical function and measures of body fatness in apparently healthy, independent adults aged 50–80 years.Methods201 adults (81 male, 120 female) aged 50–80 years underwent assessment of body mass index (BMI), body fatness, waist circumference (WC) and 6 measures of functional fitness. Sealed pedometery, worn over 7 days, was used to determine physical activity (PA). PA was categorized into three groups (low = 2,501–5,000; medium = 5,001–7,500; and high=>7,501 steps/day).ResultsResults from a series of 2 (gender) × 3 (PA dose) way analysis of covariance (ANCOVA), controlling for age, indicated dose–response effects of PA for all functional fitness tests where participants classed as high PA had higher scores for arm curl, chair stand, 6 minute walk, back scratch, and sit and reach and lower scores for the timed up and go test compared to those classed as low and medium PA. There were also significant main effects for PA dose for BMI, WC, and body fat %. Those classed as low PA had significantly higher BMI, WC and body fatness compared to those classed as medium and high PA.ConclusionsThis study shows a positive dose–response trend whereby as an individual undertakes more daily steps (based on previously established step‐count groups), multiple aspects of functionality increase and anthropometric markers of overweight and obesity decrease. Am. J. Hum. Biol., 2016. © 2016 Wiley Periodicals, Inc. Am. J. Hum. Biol. 28:890–894, 2016. © 2016Wiley Periodicals, Inc.
In vivo cortical spreading pattern of tau and amyloid in the Alzheimer disease spectrum
Authors: Cho Hanna , Choi Jae Yong , Hwang Mi Song , Kim You Jin , Lee Hye Mi , Lee Hye Sun , Lee Jae Hoon , Ryu Young Hoon , Lee Myung Sik , Lyoo Chul Hyoung 
Published: June 2016

ObjectiveTo determine the in vivo cortical spreading pattern of tau and amyloid and to establish positron emission tomography (PET) image‐based tau staging in the Alzheimer disease (AD) spectrum.MethodsWe included 195 participants (53 AD, 52 amnestic mild cognitive impairment [MCI], 23 nonamnestic MCI, and 67 healthy controls) who underwent 2 PET scans (18F‐florbetaben for amyloid‐β and 18F‐AV‐1451 for tau). We assumed that regions with earlier appearances of pathology may show increased binding in a greater number of participants and acquired spreading order of tau accumulation by sorting the regional frequencies of involvement. We classified each participant into image‐based tau stage based on the Z score of the composite region for each stage.ResultsTau accumulation was most frequently observed in the medial temporal regions and spread stepwise to the basal and lateral temporal, inferior parietal, posterior cingulate, and other association cortices, and then ultimately to the primary cortical regions. In contrast, amyloid accumulation was found with similar frequency in the diffuse neocortical areas and then finally spread to the medial temporal regions. The image‐based tau stage correlated with the general cognitive status, whereas cortical thinning was found only in the advanced tau stages: medial temporal region in stage V and widespread cortex in stage VI.InterpretationOur PET study replicated postmortem spreading patterns of tau and amyloid‐β pathologies. Unlike the diffuse accumulation of amyloid throughout the neocortex, tau spreading occurred in a stepwise fashion through the networks. Image‐based tau staging may be useful for the objective assessment of AD progression. Ann Neurol 2016;80:247–258
Allosterically Regulated Phosphatase Activity from Peptide–PNA Conjugates Folded Through Hybridization
Authors: Machida Takuya , Dutt Som , Winssinger Nicolas 
Published: June 2016

AbstractThe importance of spatial organization in short peptide catalysts is well recognized. We synthesized and screened a library of peptides flanked by peptide nucleic acids (PNAs) such that the peptide would be constrained in a hairpin loop upon hybridization. A screen for phosphatase activity led to the discovery of a catalyst with >25‐fold rate acceleration over the linear peptide. We demonstrated that the hybridization‐enforced folding of the peptide is necessary for activity, and designed a catalyst that is allosterically controlled using a complementary PNA sequence.
Fast‐Geomimicking using Chemistry in Supercritical Water
Authors: Dumas Angela , Claverie Marie , Slostowski Cédric , Aubert Guillaume , Careme Cristel , Le Roux Christophe , Micoud Pierre , Martin François , Aymonier Cyril 
Published: June 2016

AbstractHerein we introduce a powerful and fast method to produce nanominerals using a bottom up approach. The supercritical hydrothermal flow synthesis is exploited to produce model nanominerals by mimicking natural environments at high temperatures under pressure. This innovative concept is demonstrated with the talc synthesis; this represents a major technical breakthrough since it allows decreasing the mineral‐synthesis time from tens of hours to tens of seconds. Through this example, we show these nanominerals exhibit new crystal‐chemistry signals and new properties. This approach provides a means to reproduce the early stages of formation of minerals in different natural environments from sedimentary environments (low temperature and pressure) to hydrothermal/metamorphic environments (high temperature and high pressure).
The Uranyl Cation as a Visible‐Light Photocatalyst for C(sp3)−H Fluorination
Authors: West Julian G. , Bedell T. Aaron , Sorensen Erik J. 
Published: June 2016

AbstractThe fluorination of unactivated C(sp3)−H bonds remains a desirable and challenging transformation for pharmaceutical, agricultural, and materials scientists. Previous methods for this transformation have used bench‐stable fluorine atom sources; however, many still rely on the use of UV‐active photocatalysts for the requisite high‐energy hydrogen atom abstraction event. Uranyl nitrate hexahydrate is described as a convenient, hydrogen atom abstraction catalyst that can mediate fluorinations of certain alkanes upon activation with visible light.
C‐Propargylation Overrides O‐Propargylation in Reactions of Propargyl Chloride with Primary Alcohols: Rhodium‐Catalyzed Transfer Hydrogenation
Authors: Liang Tao , Woo Sang Kook , Krische Michael J. 
Published: June 2016

AbstractThe canonical SN2 behavior displayed by alcohols and activated alkyl halides in basic media (O‐alkylation) is superseded by a pathway leading to carbinol C‐alkylation under the conditions of rhodium‐catalyzed transfer hydrogenation. Racemic and asymmetric propargylations are described.