bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficacy of fluoroscopy-guided endoscopic cricopharyngeal myotomy
Authors: Fujiwara K , Kawamoto K , Taira K , Fukuhara T , Koyama S , Kataoka H , Kitano H , Takeuchi H 
Published: January 2019

AbstractBackgroundIn endoscopic cricopharyngeal myotomy, surgeons sometimes have concerns about performing an adequate incision with only a narrow intra-cavital view from one direction. In order to overcome these issues, fluoroscopic radiography was used during endoscopic cricopharyngeal myotomy.MethodsPeri-operative fluoroscopic radiography was utilised to check the position of the diverticuloscope, and to confirm the extent of the incision during surgery. A balloon catheter was used to determine whether the cricopharyngeal muscle was sufficiently resected. Blood loss, peri-operative complications, and functional oral swallowing scale and penetration aspiration scale scores were evaluated.ResultsIn 12 out of 15 patients, intra-operative fluoroscopic radiography showed the diverticuloscope positioned in the post-cricoid area, and the cricopharyngeal muscle was raised and the surgery completed without adverse effect. Swallowing functions improved following surgery.ConclusionIntra-operative fluoroscopy might improve endoscopic cricopharyngeal myotomy by allowing surgeons to confirm the extent of resection, and by reducing peri-operative morbidity and complication rates.
Mineral‐Filled Fractures as Indicators of Multigenerational Fluid Flow in the Pahrump Hills Member of the Murray Formation, Gale Crater, Mars
Authors: Kronyak R. E. , Kah L. C. , Edgett K. S. , VanBommel S. J. , Thompson L. M. , Wiens R. C. , Sun V. Z. , Nachon M. 
Published: January 2019

AbstractMineral‐filled fractures (veins) are valuable indicators of deformation and fluid flow within a sedimentary package. Information obtained from vein morphology, texture, and chemistry may elucidate the sequence and nature of postdepositional fluid events. Additional information from vein patterns and interactions between veins and host rock provides insight into fracture formation mechanism(s). The widespread occurrence of veins and other diagenetic features in the sedimentary rock record preserved in Gale crater, Mars, indicates that postdepositional fluids were regionally active considerably later in time than the primary fluviolacustrine environments responsible for the deposition of Mount Sharp strata. Here we report a suite of veins within the Murray formation at the Pahrump Hills locality that were investigated using the scientific payload of the Mars Science Laboratory Curiosity rover. Based on an analysis of vein color, morphology, and texture, and corroborated by vein chemistry, we interpret three distinct vein types at Pahrump Hills: gray veins, white veins, and dark‐toned veins. These veins represent distinct, separate episodes of postdepositional fluid flow, suggesting a protracted history of fluid stability in Gale crater. Additionally, we utilize vein patterns across multiple lithologies at the Pahrump Hills field site to suggest hydrofracture as the primary mechanism of fracture formation.
Masked Shoreline Erosion at Large Spatial Scales as a Collective Effect of Beach Nourishment
Authors: Armstrong Scott B. , Lazarus Eli D. 
Published: January 2019

AbstractSea‐level rise along low‐lying coasts of the world's passive continental margins should, on average, drive net shoreline retreat over large spatial scales (>102 km). A variety of natural physical factors can influence trends of shoreline erosion and accretion, but trends in recent rates of shoreline change along the U.S. Atlantic Coast reflect an especially puzzling increase in accretion, not erosion. A plausible explanation for the apparent disconnect between environmental forcing and shoreline response along the U.S. Atlantic Coast is the application, since the 1960s, of beach nourishment as the predominant form of mitigation against chronic coastal erosion. Using U.S. Geological Survey shoreline records from 1830–2007 spanning more than 2,500 km of the U.S. Atlantic Coast, we calculate a mean rate of shoreline change, prior to 1960, of −55 cm/year (a negative rate denotes erosion). After 1960, the mean rate reverses to approximately +5 cm/year, indicating widespread apparent accretion despite steady (and, in some places, accelerated) sea‐level rise over the same period. Cumulative sediment input from decades of beach‐nourishment projects may have sufficiently altered shoreline position to mask “true” rates of shoreline change. Our analysis suggests that long‐term rates of shoreline change typically used to assess coastal hazard may be systematically underestimated. We also suggest that the overall effect of beach nourishment along of the U.S. Atlantic Coast is extensive enough to constitute a quantitative signature of coastal geoengineering and may serve as a bellwether for nourishment‐dominated shorelines elsewhere in the world.
Mechanisms of Low‐Frequency Oxygen Variability in the North Pacific
Authors: Ito Takamitsu , Long Matthew C. , Deutsch Curtis , Minobe Shoshiro , Sun Daoxun 
Published: January 2019

This study investigates the mechanisms of interannual and decadal variability of dissolved oxygen (O2) in the North Pacific using historical observations and a hindcast simulation using the Community Earth System Model. The simulated variability of upper ocean (200 m) O2 is moderately correlated with observations where sampling density is relatively high. The dominant mode of O2 variability explains 24.8% of the variance and is significantly correlated with the Pacific Decadal Oscillation (PDO) index (r = 0.68). Two primary mechanisms are hypothesized by which the PDO controls upper ocean O2 variability. Vertical movement of isopycnals (“heave”) drives O2 variations in the deep tropics; isopycnal surfaces are depressed in the eastern tropics under the positive (El Niño‐like) phase of PDO, leading to O2 increases in the upper water column. In contrast to the tropics, changes in subduction are the primary control on extratropical O2 variability. These hypotheses are tested by contrasting O2 anomalies with the heave‐induced component of variability calculated from potential density anomalies. Isopycnal heave is the leading control on O2 variability in the tropics, but heave alone cannot fully explain the amplitude of tropical O2 variability, likely indicating reinforcing changes from the biological O2 consumption. Midlatitude O2 variability indeed reflects ocean ventilation downstream of the subduction region where O2 anomalies are correlated with the depth of winter mixed layer. These mechanisms, synchronized with the PDO, yield a basin‐scale pattern of O2 variability that are comparable in magnitude to the projected rates of ocean deoxygenation in this century under “unchecked” emission scenario.
Modeling the Recent Changes in the Arctic Ocean CO2Sink (2006–2013)
Authors: Manizza Manfredi , Menemenlis Dimitris , Zhang Hong , Miller Charles E. 
Published: January 2019

The Arctic Ocean (AO) and its associated marginal seas have recently experienced rapid climate and environmental changes, most notably sea‐ice area (SIA) loss and warming potentially impacting its uptake of carbon dioxide (CO2). We used the state‐of‐the‐art ECCO2‐Darwin coupled ocean‐biogeochemistry model to simulate the 2006–2013 period and investigate the impact of changing SIA on the CO2uptake of the AO. We find that the mean annual CO2sink of the AO is 153 ± 14 TgC a−1and the CO2sink decreased at a rate of 3.6 TgC a−1even though SIA decreased by 8 × 104 km2 a−1over the same period. Extreme SIA loss in 2007 resulted in a 185.4 TgC CO2sink, an increase ∼20% over the 2006–2013 mean. In contrast, extreme SIA loss of 2012 resulted in a CO2sink of the AO of only 146.3 TgC due to two main factors: (1) increased both wind speed and stratification in the Eastern Siberian Sea absorbing less CO2and (2) decreased primary production and area of air‐sea gas exchange in the Chukchi and Nordic Seas. Our model captures a trend of decreasing CO2sink in most of the Chukchi Sea during fall but does not show the changes in winter CO2sink in the Nordic and Barents Seas as previous independent studies have suggested. Our results indicate that future AO‐atmosphere CO2exchange will be determined by complex interplay of SIA and other environmental drivers.
Rapid Exhumation of Earth's Youngest Exposed Granites Driven by Subduction of an Oceanic Arc
Authors: Spencer C. J. , Danišík M. , Ito H. , Hoiland C. , Tapster S. , Jeon H. , McDonald B. , Evans N. J. 
Published: January 2019

AbstractExhumation of plutonic systems is driven by a range of mechanisms including isostatic, tectonic, and erosional processes. Variable rates of plutonic exhumation in active subduction systems may be driven by idiosyncrasies of regional geology or by first‐order tectonic features. We report new age, isotope, and low‐temperature thermochronology constraints of granitoids from the Hida Mountains of central Japan that constrain the highest rates and magnitude of plutonic rock exhumation within the Japan and one of the highest worldwide. This extreme exhumation is centered on the apex of a lithospheric scale anticlinorium associated with the subduction of the Izu‐Bonin oceanic arc. The spatial and temporal relationship between the exhumation of these Pleistocene plutons and the subducting/accreting Izu‐Bonin oceanic arc links the plate‐scale geodynamics and regional exhumation patterns. Identifying thermochronological anomalies within magmatic arcs provides an opportunity to identify ancient asperities previously subducted and responsible for rapid exhumation rates within ancient subduction systems.
Seafloor Geodesy Revealed Partial Creep of the North Anatolian Fault Submerged in the Sea of Marmara
Authors: Yamamoto Ryusuke , Kido Motoyuki , Ohta Yusaku , Takahashi Narumi , Yamamoto Yojiro , Pinar Ali , Kalafat Doğan , Özener Haluk , Kaneda Yoshiyuki 
Published: January 2019

AbstractIn this study, the creep rate across the North Anatolian Fault was directly measured in the western Sea of Marmara using the seafloor acoustic ranging technique; the data reveal coupling conditions on the fault interface and stress accumulation with implications for regional seismic risk evaluation. Continuous measurements over a period of 3.5 years at a site in the Western High clearly indicate right‐lateral displacement at a rate of 10.7 ± 4.7 mm/year (95% confidence level); approximately half of the regional block motion at this location is released by this steady motion. A simple model of three elastic layers—a partially creeping sedimentary layer (8 km) at the top with the observed rate, a locked (3 km) and fully creeping layer in the middle, and a bottom layer—assumed from seismicity, reasonably explains onshore Global Navigation Satellite System data for the surrounding region.
Potential Increase in Hazard From Mediterranean Hurricane Activity With Global Warming
Authors: González‐Alemán Juan J. , Pascale Salvatore , Gutierrez‐Fernandez Jesús , Murakami Hiroyuki , Gaertner Miguel A. , Vecchi Gabriel A. 
Published: January 2019

AbstractMediterranean hurricanes (Medicanes) are intense cyclones that acquire tropical characteristics, associated with extreme winds and rainfall, thus posing a serious natural hazard to populated areas along Mediterranean coasts. Understanding how Medicanes will change with global warming remains, however, a challenge, because coarse resolution and/or the lack of atmosphere‐ocean coupling limit the reliability of numerical simulations. Here we investigate the Medicanes' response to global warming using a recently developed 25‐km global coupled climate model, which features a realistic representation of Medicanes in present climate conditions. It is found that despite a decrease in frequency, Medicanes potentially become more hazardous in the late century, lasting longer and producing stronger winds and rainfall. These changes are associated with a more robust hurricane‐like structure and are mainly confined to autumn. Thus, continued anthropogenic warming will increase the risks associated with Medicanes even in an intermediate scenario (Representative Concentration Pathway, RCP4.5), with potential natural and socioeconomic consequences.
Climatic Warming Increases Spatial Synchrony in Spring Vegetation Phenology Across the Northern Hemisphere
Authors: Liu Qiang , Piao Shilong , Fu Yongshuo H. , Gao Mengdi , Peñuelas Josep , Janssens Ivan A. 
Published: January 2019

AbstractClimatic warming has advanced spring phenology across the Northern Hemisphere, but the spatial variability in temperature sensitivity of spring phenology is substantial. Whether spring phenology will continue to advance uniformly at latitudes has not yet been investigated. We used Bayesian model averaging and four spring phenology models, and demonstrated that the start of vegetation growing season across the Northern Hemisphere will become substantially more synchronous (up to 11.3%) under future climatic warming conditions. Larger start of growing season advances are expected at higher than lower latitudes (3.7–10.9 days earlier) due to both larger rate in spring warming at higher latitudes and larger decreases in the temperature sensitivity of start of growing season at low latitudes. The consequent impacts on the northern ecosystems due to this increased synchrony may be considerable and thus worth investigating.
A Study of the F2 Layer Stratification on Ionograms Using a Simple Model of TIDs
Authors: Jiang Chunhua , Yang Guobin , Liu Jing , Zhao Zhengyu 
Published: January 2019

AbstractTo study the effect of gravity waves/traveling ionospheric disturbances (TIDs) on ionograms with the F2 layer stratification, we reconstructed ionograms using a simple of TIDs model through a ray tracing method. Results show that two typical types of the F2 layer stratification induced by gravity waves/TIDs could be synthesized on ionograms by the simple model of TIDs in this study. Furthermore, we found that vertical and horizontal gradients caused by TIDs could cause different features on ionograms. Results suggested that the vertical gradient induced by gravity waves/TIDs could cause the F2 stratification. The horizontal gradient caused by gravity waves/TIDs might play a significant role in forming spread F on ionograms. Moreover, we found that the smaller wavelength and larger periodical time of TIDs could make it easier to form the F2 layer stratification on ionograms through modeling studies.
Cosmic Noise Absorption During Solar Proton Events in WACCM‐D and Riometer Observations
Authors: Heino Erkka , Verronen Pekka T. , Kero Antti , Kalakoski Niilo , Partamies Noora 
Published: January 2019

AbstractSolar proton events (SPEs) cause large‐scale ionization in the middle atmosphere leading to ozone loss and changes in the energy budget of the middle atmosphere. The accurate implementation of SPEs and other particle ionization sources in climate models is necessary to understand the role of energetic particle precipitation in climate variability. We use riometer observations from 16 riometer stations and the Whole Atmosphere Community Climate Model with added D region ion chemistry (WACCM‐D) to study the spatial and temporal extent of cosmic noise absorption (CNA) during 62 SPEs from 2000 to 2005. We also present a correction method for the nonlinear response of observed CNA during intense absorption events. We find that WACCM‐D can reproduce the observed CNA well with some need for future improvement and testing of the used energetic particle precipitation forcing. The average absolute difference between the model and the observations is found to be less than 0.5 dB poleward of about 66° geomagnetic latitude, and increasing with decreasing latitude to about 1 dB equatorward of about 66° geomagnetic latitude. The differences are largest during twilight conditions where the modeled changes in CNA are more abrupt compared to observations. An overestimation of about 1° to 3° geomagnetic latitude in the extent of the CNA is observed due to the fixed proton cutoff latitude in the model. An unexplained underestimation of CNA by the model during sunlit conditions is observed at stations within the polar cap during 18 of the studied events.
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System
Authors: Vore Margot E. , Bartholomaus Timothy C. , Winberry J. Paul , Walter Jacob I. , Amundson Jason M. 
Published: January 2019

AbstractSubglacial water flow impacts glacier dynamics and shapes the subglacial environment. However, due to the challenges of observing glacier beds, the spatial organization of subglacial water systems and the time scales of conduit evolution and migration are largely unknown. To address these questions, we analyze 1.5‐ to 10‐Hz seismic tremor that we associate with subglacial water flow, hat is, glaciohydraulic tremor, at Taku Glacier, Alaska, throughout the 2016 melt season. We use frequency‐dependent polarization analysis to estimate glaciohydraulic tremor propagation direction (related to the subglacial conduit location) and a degree day melt model to monitor variations in melt‐water input. We suggest that conduit formation requires sustained water input and that multiconduit flow paths can be distinguished from single‐conduit flow paths. Theoretical analysis supports our seismic interpretations that subglacial discharge likely flows through a single‐conduit in regions of steep hydraulic potential gradients but may be distributed among multiple conduits in regions with shallower potential gradients. Seismic tremor in regions with multiple conduits evolves through abrupt jumps between stable configurations that last 3–7 days, while tremor produced by single‐conduit flow remains more stationary. We also find that polarized glaciohydraulic tremor wave types are potentially linked to the distance from source to station and that multiple peak frequencies propagate from a similar direction. Tremor appears undetectable at distances beyond 2–6 km from the source. This new understanding of the spatial organization and temporal development of subglacial conduits informs our understanding of dynamism within the subglacial hydrologic system.
Transport Scaling of Dune Dimensions in Shallow Flows
Authors: Bradley Ryan W. , Venditti Jeremy G. 
Published: January 2019

AbstractDune dimensions in sand‐bedded rivers are often thought to scale with flow depth (h), with height (H) scaling as 1/6h and length (L) as 5h, even though substantial scatter about the relations has been observed. Transport stage has been shown to affect bedform geometry, but this control is often ignored in favor of depth scaling relations. Here, we use a series of flume experiments to systematically test controls on dune dimensions and variability. Experiments involved three sets of runs under five constant transport stages, ranging threshold to washout conditions, at three different flow depths. The mobile bed was repeatedly scanned during a 10‐hr equilibrium period to derive mean values and quantify the variability. The results show that dune‐depth scaling is not consistent because of a transport stage effect. Dune height increases with transport stage until a point when H decreases. Length remains nearly constant with transport stage until further increases in transport stage leads to lengthening. In general, dunes grow higher when significant bedload transport occurs but become flatter and longer in the presence of substantial suspension. Ultimately, dunes scale with transport stage, which is a function of slope, grain size, and h. The results are used to derive transport stage relations to guide predictions of dune dimensions in rivers and reconstructions of paleoflows based on dimensions estimated from cross strata. The relations incorporate the nonlinear response of dune dimensions with transport stage and provide metrics of uncertainty to include in predictions.
A Seasonal to Interannual View of Inorganic and Organic Carbon and pH in Western Lake Superior
Authors: Minor Elizabeth C. , Tennant Cody James , Brown Erik T. 
Published: January 2019

AbstractTo investigate the carbon cycle of Lake Superior, Earth's largest freshwater lake by surface area, we performed total organic carbon, dissolved organic carbon, chlorophyll, spectrophotometric pH, total inorganic carbon, and alkalinity measurements on seasonal samples from the western lake. The last three parameters, along with in situ temperature, were used to calculate the partial pressure of carbon dioxide in surface water (pCO2(w)) using the CO2SYS algorithm. There was a strong positive correlation between pH and water temperature and a weaker but significant positive correlation between pH and chlorophyll concentration. Total organic carbon exhibited higher nearshore concentrations (as determined by a negative correlation with total water column depth); such a spatial relationship did not appear in the inorganic carbon parameters (total inorganic carbon, pH, or pCO2(w)). Western Lake Superior exhibited net outgassing in spring, little net gas transfer in summer, and some outgassing in the fall. The pCO2(w) values were negatively correlated with both water temperature and chlorophyll concentration. Seasonal differences in pCO2(w) in Lake Superior appeared more strongly driven by biology and terrestrial inputs as compared to direct effects of temperature on CO2 solubility. Interannual data from the long‐term Great Lakes Environmental Database data set indicated that lake alkalinity has been increasing over the past 20 years, and lake surface water pH appeared relatively stable. Modeling pH change over the same time frame in CO2SYS shows that increases in alkalinity and lake surface water temperature counteract the increase in atmospheric carbon dioxide concentration, leading to a relatively constant pH, consistent with observational data.
Evaluating the Representation of Vegetation Phenology in the Community Land Model 4.5 in a Temperate Grassland
Authors: Zhang Lexin , Lei Huimin , Shen Hong , Cong Zhentao , Yang Dawen , Liu Tingxi 
Published: January 2019

AbstractVegetation plays an important role in terrestrial ecosystems and affects both water and carbon cycles. It is crucial to predict vegetation phenology accurately to understand the Earth's ecosystems better. In this study, we evaluated the temperate grassland phenology simulated by the Community Land Model 4.5 for the Northeast China Transect with the Moderate Resolution Imaging Spectroradiometer leaf area index (LAI) data set. Results show that although the CLM could partly capture the seasonal patterns of LAI for temperate grasslands, shortcomings lie in a delayed end date of growing season and a problematic senescence existed in early summer. The reason is attributed to the low temperature threshold set for leaf offset and an inaccurate carbon allocation strategy for its display and storage. With the adjusted key phenology parameters, the modeled temperate grassland phenology has been substantially improved for this system: An overestimation of the growing‐season LAI as well as the annual gross primary productivity can be constrained. Meanwhile, the modified phenology would effectively change the partition of evapotranspiration in a more reasonable pattern.