bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sorbitol enhances the physicochemical stability of B12 vitamers
Authors: Hadinata Lie Andrew , V Chandra-Hioe Maria , Arcot Jayashree 
Published: April 2019

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.
Individuelle Entwicklungsverläufe beim Lesen
Authors: Berendes Karin , Becker Michael , Jacoby Johann , Flunger Barbara , Nagengast Benjamin , Trautwein Ulrich 
Published: April 2019

Zusammenfassung. Es ist ein vielfach replizierter Befund, dass Jungen im Durchschnitt über geringere Lesekompetenzen verfügen als Mädchen. Bezogen auf die Entwicklung von Leseleistungen stellt sich allerdings die Frage, ob und wie Unterschiede zwischen den Geschlechtern im Laufe der Sekundarstufe zunehmen, abnehmen oder eher stabil bleiben. Vor allem aus dem englischsprachigen Raum liegen Hinweise dafür vor, dass eine Zunahme der Leistungsunterschiede zwischen Jungen und Mädchen auf Schülerinnen und Schülern mit niedrigem sozioökonomischen Status zurückgeht. Auch der Migrationsstatus und die besuchte Schulform werden als Moderatoren diskutiert. In der vorliegenden Studie wurde den genannten Fragestellungen mit Daten von 2.505 Schülerinnen und Schülern aus Baden-Württemberg nachgegangen. Auf Basis von Daten von vier Testzeitpunkten (5. – 8. Schuljahresstufe) wurden latente Wachstumskurvenmodelle für die Kompetenzbereiche Lesegeschwindigkeit und -verständnis modelliert. Die Ergebnisse zeigen, dass ein Schereneffekt zu Ungunsten der Jungen sowohl in der Lesegeschwindigkeit als auch im Leseverständnis auftrat. Für den sozioökonomischen Status und den Migrationsstatus zeigten sich hingegen keine Schereneffekte der Leseleistungen. Des Weiteren ergaben die Analysen, dass der geschlechterbezogene Schereneffekt nicht durch den sozioökonomischen Status oder den Migrationshintergrund moderiert wird. Die besuchte Schulform stellte sich nicht als bedeutsamer Moderator heraus.
Fluid and Melt Pathways in the Central Chilean Subduction Zone Near the 2010 Maule Earthquake (35–36°S) as Inferred From Magnetotelluric Data
Authors: Cordell Darcy , Unsworth Martyn J. , Diaz Daniel , Reyes‐Wagner Valentina , Currie Claire A. , Hicks Stephen P. 
Published: April 2019

AbstractThe subduction zone of central Chile (36°S) has produced some of the world's largest earthquakes and significant volcanic eruptions. Understanding the fluid fluxes and structure of the subducting slab and overriding plate can provide insight into the tectonic processes responsible for both seismicity and magmatism. Broadband and long‐period magnetotelluric data were collected along a 350‐km profile in central Chile and Argentina and show a regional geoelectric strike of 15 ± 19° east of north. The preferred two‐dimensional inversion model included the geometry of the subducting Nazca plate as a constraint. On the upper surface of the Nazca plate, conductors were interpreted as fluids expelled from the downgoing slab via compaction at shallow depth (C1) and metamorphic reactions at depths of 40–90 km (C2 and C3). At greater depths (130 km), a conductor (C7) is interpreted as a region of partial melt related to deserpentinization in the backarc. A resistor on the slab interface (R1) is coincident with a high‐velocity anomaly which was interpreted as a strong asperity which may affect the coseismic slip behavior of large megathrust earthquakes at this latitude. Correlations with seismicity suggest slab fluids alter the forearc mantle and define the downdip limit of the seismogenic zone. Beneath the volcanic arc, several upper crustal conductors (C4 and C5) represent partial melt beneath the Tatara‐San Pedro Volcano and the Laguna del Maule Volcanic Field. A deeper lower crustal conductor (C6) underlies both volcanoes and suggests a connected network of melt in a thermally mature lower crust.
Nucleation and Kinematic Rupture of the 2017 Mw 8.2 Tehuantepec Earthquake
Authors: Meng Lingsen , Huang Hui , Xie Yuqing , Bao Han , Dominguez Luis A. 
Published: April 2019

AbstractIntegrated observations from the 2017 Mw 8.2 Tehuantepec, Mexico, earthquake probe one of the largest normal‐faulting events inside a subducting slab. In this study, we utilize a template matching approach to detect possible missing earthquakes within a 2‐month period before the mainshock. The seismicity rate shows an abrupt increase in the last day around the mainshock hypocenter. The large distance between most of the foreshocks and the mainshock is not consistent with static stress triggering but suggests alternative mechanisms such as delayed dynamic triggering or aseismic transients. Back‐projection using the USArray network reveals that the rupture propagated northwestward unilaterally at a speed of 3.6 km/s and terminated north of the Tehuantepec Ridge. Towards the end of the rupture, a wide step‐over occurred onto an adjacent fault parallel to the main fault plane. The mainshock is likely a reactivation of subducted outer‐rise faults, supported by the similarity of fault‐strike angles. The surprisingly large magnitude is consistent with exceedingly large dimensions of outer‐rise faulting in this segment of the central Mexican trench.
Fast 4‐D Imaging of Fluid Flow in Rock by High‐Speed Neutron Tomography
Authors: Tudisco E. , Etxegarai M. , Hall S. A. , Charalampidou E.‐M. , Couples G. D. , Lewis H. , Tengattini A. , Kardjilov N. 
Published: April 2019

AbstractHigh‐speed neutron tomographies (1‐min acquisition) have been acquired during water invasion into air‐filled samples of both intact and deformed (ex situ) Vosges sandstone. Three‐dimensional volume images have been processed to detect and track the evolution of the waterfront and to calculate full‐field measurement of its speed of advance. The flow process correlates well with known rock properties and is especially sensitive to the distribution of the altered properties associated with observed localized deformation, which is independently characterized by Digital Volume Correlation of X‐ray tomographies acquired before and after the mechanical test. The successful results presented herein open the possibility of in situ analysis of the local evolution of hydraulic properties of rocks due to mechanical deformation.
Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir
Authors: Yao Zhuosen , Qin Kezhang , Wang Qin , Xue Shengchao 
Published: April 2019

AbstractUnderstanding the deformation mechanisms of olivine has been considered as the crucial factor in tracing the dynamic processes from seismic anisotropy. Due to extensive overprinting of deformation and alteration, natural examples of original magmatic fabric of olivine are scarce. In this study we selected one wehrlite and three dunite samples from a deep borehole in the Poyi mafic‐ultramafic intrusion in the Tarim Craton. The fresh samples show adcumulate texture and plastic deformation of dry olivine (≤10 ppm H2O). Thermobarometer calculations yield crystallization conditions at 200–400 MPa and >1,124–1,275 °C. Olivine developed a B‐type fabric characterized by a concentration of [001] axes parallel to the interpreted lineation and that of [010] axes normal to the interpreted foliation. Activation of [001] and [100] dislocations is confirmed by microstructural observations. Simulation of gravity‐driven compaction process reveals extremely rapid compaction of kilometer‐scale crystal mush in the Poyi magmatic system. During the early compaction with high porosity, crystallographic habit of olivine may produce shape‐preferred orientation and the related B‐type fabric. In the final stage of compaction and crystallization, the initial shape‐preferred orientation was gradually overprinted, whereas the weak B‐type fabric has remained with dislocation creep and dislocation‐accommodated grain boundary sliding. Calculated seismic velocities of peridotite samples show low P and S wave anisotropies, with the fastest S wave polarization direction normal to the foliation. Hence, a mush‐dominated ultramafic intrusion exhibits weak seismic anisotropy, which has potential to better understand seismic anisotropy in the transcrustal magmatic systems.
Offshore Landslide Hazard Curves From Mapped Landslide Size Distributions
Authors: Geist Eric L. , ten Brink Uri S. 
Published: April 2019

AbstractWe present a method to calculate landslide hazard curves along offshore margins based on size distributions of submarine landslides. The method utilizes 10 different continental margins that were mapped by high‐resolution multibeam sonar with landslide scar areas measured by a consistent Geographic Information System procedure. Statistical tests of several different probability distribution models indicate that the lognormal model is most appropriate for these siliciclastic environments, consistent with an earlier study of the U.S. Atlantic margin (Chaytor et al., 2009,https://doi.org/10.1016/j.margeo.2008.08.007). Parameter estimation is performed using the maximum likelihood technique, and confidence intervals are determined using likelihood profiles. Pairwise comparison of size distributions for the 10 margins indicates that the U.S. Atlantic and Queen Charlotte margins are different than most other margins. These margins represent end‐members, with the U.S. Atlantic margin having the highest mean scar area and the Queen Charlotte margin the lowest. We demonstrate that empirical, offshore landslide hazard curves can be developed from the landslide size distributions, if the duration of mapped landslide activity is known. This study indicates that the shape parameter of the size distribution is similar among all 10 margins, and thus, the shape of the hazard curves is also similar. Significant differences in hazard curves among the margins are therefore related to differences in mean sizes and, potentially, differences in the duration of landslide activity.
U.S. IOOS Coastal and Ocean Modeling Testbed: Hurricane‐Induced Winds, Waves, and Surge for Deep Ocean, Reef‐Fringed Islands in the Caribbean
Authors: Joyce B. R. , Gonzalez‐Lopez J. , Van der Westhuysen A. J. , Yang D. , Pringle W. J. , Westerink J. J. , Cox A. T. 
Published: April 2019

AbstractAs part of a U.S. Integrated Ocean Observing System (IOOS) funded Coastal and Ocean Modeling Testbed (COMT), hindcasts of waves and storm surge for 2017 Hurricanes Irma and Maria are examined and compared to wave and water level gauge data in the vicinity of Puerto Rico and the U.S. Virgin Islands. The region is characterized by adjacent deep ocean water, narrow shelves, and coral reef systems providing coastal protection. The storm physics are analyzed using an unstructured grid third‐generation wave circulation coupled modeling system (ADCIRC+SWAN) with respect to tides, winds, atmospheric pressure, waves, and wave radiation stress‐induced setup. The water level response is generally dominated by the pressure deficit of the hurricanes. Wind‐driven surge is important over the shallow shelf to the east of Puerto Rico and wave‐induced setup becomes significant at locations in close proximity to the coastline. Contrary to conditions along the Gulf of Mexico shelf, geostrophically induced setup is negligible. Characteristics from a range of meteorological forcing models are assessed, and the associated errors in the hydrodynamic response are quantified. A data‐assimilated tropical planetary boundary model leads to the smallest atmospheric pressure, water level and wave property errors across both storms. Through comparisons between ADCIRC+SWAN and SLOSH‐FW (a structured grid first‐generation wave circulation coupled model), it is shown that the response to atmospheric forcing is similar; however, nearshore wave setup is smaller in SLOSH‐FW due to its coarser resolution here. Further, in addition to erroneous wind‐driven surge through depth limiting over the open ocean, numerical oscillations in the water level time series develop in SLOSH‐FW likely due to its small domain size.
Sensitivity of Midlatitude Heavy Precipitation to SST: A Case Study in the Sea of Japan Area on 9 August 2013
Authors: Iizuka Satoshi , Nakamura Hisashi 
Published: April 2019

AbstractThis study investigates the influence of sea surface temperature (SST) over the Sea of Japan on a heavy precipitation event that occurred over the northern part (Northern Tohoku region) of Japan's largest island on 9 August 2013. Sensitivity experiments with the Weather Research and Forecasting model show that warmer (cooler) SSTs prescribed over the Sea of Japan in the simulations lead to an increase (decrease) in 24‐hr precipitation averaged within the Northern Tohoku region, especially on the Sea of Japan (i.e., windward) side. Though no significant relationship is found between the local maxima and SSTs over the Sea of Japan, those SST values over the Sea of Japan affect the evolution of the intense convective precipitation; higher (lower) SSTs act to shift the location of intense precipitation on the upwind (downwind) side in the present event. The different evolution results in a different interaction with the downstream orography, leading to no significant relationship between the local maxima of intense precipitation and SSTs. The differences arise from the sensitivity of convective updraft to SSTs. The simulations thus suggest that uncertainties in currently available SST products may alter both the area‐averaged precipitation and the geographical locations of intense precipitation, which can potentially impact flash flood and landslide warnings.
Characterizing the Representativity Error of Cloud Profiling Observations for Data Assimilation
Authors: Fielding M. D. , Stiller O. 
Published: April 2019

AbstractActive observations from profiling instruments such as cloud radar or lidar have proved invaluable in improving our understanding of clouds and their interaction with the atmosphere. However, while they undoubtedly contain a wealth of information about the atmospheric state, the assimilation of such observations into NWP models has so far had mixed success. One reason is the mismatch of scales between the relatively coarse model resolution and the narrow beam‐width of the instruments. To obtain an optimal analysis, this representativity error due to this mismatch in scales must be included within the observation error covariance matrix. In this paper, we demonstrate how a relatively straightforward approach that uses the local variance of the measurement combined with a global estimate of correlation provides a useful estimate of the representativity error. We also show how the method can be used to estimate the correlation in representativity error between observations in both the horizontal and vertical, potentially removing the need to thin the observations, or inflate their observation error. The method is evaluated using 2‐D and 3‐D fields of simulated and observed radar reflectivity before an example application to profiling observations is shown using Cloudsat data.
The Geomorphic Impact of Outburst Floods: Integrating Observations and Numerical Simulations of the 2000 Yigong Flood, Eastern Himalaya
Authors: Turzewski Michael D. , Huntington Katharine W. , LeVeque Randall J. 
Published: April 2019

AbstractOutburst floods in mountainous landscapes traverse complex topography and interact with the channel and valley walls, producing intense flow hydraulics that drive geomorphic change and impact people and infrastructure. Evidence of modern and ancient outburst floods is scattered around the eastern Himalaya, but hydraulics related to these geomorphic features are uncharacterized, limiting our understanding of the role of large floods in long‐term evolution of the region. Here we combine remote and field observations of the 2000 Yigong River landslide‐dam outburst flood with 2‐D numerical flood simulations using the software GeoClaw. Modeling results agree with field evidence to the extent that we judge the simulated hydraulics to be relevant to flood hazard and geomorphic investigations. Results show that the hydraulics of outburst floods through rugged topography differ from those expected for nonflood flows, in magnitude and in the spatial patterns of flow speed, direction, and shear stress. The flood produced sustained high bed shear stresses capable of plucking meter‐scale blocks immediately downstream of breach, in the steep Tsangpo Gorge, and in isolated locations associated with valley constrictions. Simulated shear stresses suggest that outburst floods deposited numerous kilometer‐scale boulder bars observed along the flood pathway, armoring the bed, increasing channel roughness, and inhibiting incision in locations that would not be predicted for nonflood flows. Our findings highlight the potential for different magnitude flows to promote not only different amounts, but also different patterns of bedrock erosion, with implications for the role of prehistoric megafloods in the topographic evolution of the eastern Himalaya.
A Cloud Top Radiative Cooling Model Coupled With CLUBB in the Community Atmosphere Model: Description and Simulation of Low Clouds
Authors: Guo Zhun , Wang Minghuai , Larson Vincent E. , Zhou Tianjun 
Published: April 2019

AbstractIn this study, a higher‐order closure scheme known as Cloud Layers Unified By Binormals (CLUBB) is coupled with a cloud top radiative cooling scheme (RAD). The cloud top radiative cooling scheme treats the buoyancy flux generated near the top of the boundary layer which helps the CLUBB scheme to better represent the radiation‐turbulence interaction on the condition of coarse vertical resolution. CLUBB with RAD is found to improve subtropical low‐cloud simulations, and the improvement is particularly evident for nocturnal stratocumulus. The improvements are caused by the stronger and more symmetric vertical turbulent mixing in the boundary layer, as CLUBB with RAD increases the variance of vertical velocity and vertical turbulent transports and reduces the skewness of vertical velocity by enhancing the radiative cooling effects and buoyancy fluxes at the cloud layer. The pumping effect related to the stronger vertical turbulent transports further cools and dries the lower boundary layer, which increases the local surface heating fluxes and further improves the low‐cloud simulations.
Reanalysis of Ring Current Electron Phase Space Densities Using Van Allen Probe Observations, Convection Model, and Log‐Normal Kalman Filter
Authors: Aseev N. A. , Shprits Y. Y. 
Published: April 2019

AbstractModels of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting errors in model predictions associated with uncertainties in electron lifetimes, boundary conditions, and convection electric fields. We demonstrate that reanalysis retains features which cannot be fully reproduced by the convection model such as storm‐time earthward propagation of the electrons down to 2.5 RE. The Kalman filter can adjust model predictions to satellite measurements even in regions where data are not available. We show that the Kalman filter can adjust model predictions in accordance with observations for μ = 0.1, 2.3, and 9.9 MeV/G and constant K = 0.3 G1/2RE electrons. The results of this study demonstrate that data assimilation can improve performance of ring current models, better quantify model uncertainties, and help deeper understand the physics of the ring current particles.
Permeability Prediction in Rocks Experiencing Mineral Precipitation and Dissolution: A Numerical Study
Authors: Niu Qifei , Zhang Chi 
Published: April 2019

AbstractIn this study, we focus on the electrical tortuosity‐based permeability model k = reff2/8F (reff is an effective pore size, and F is the formation factor) and analyze its applicability to rocks experiencing mineral precipitation and dissolution. Two limiting cases of advection‐dominated water‐rock reactions are simulated, that is, the reaction‐limited and transport‐limited cases. At the pore scale, the two precipitation/dissolution patterns are simulated with a geometrical model and a phenomenological model. The fluid and electric flows in the rocks are simulated by directly solving the linear Stokes equation and Laplace equation on the representative elementary volume of the samples. The numerical results show that evolutions of k and F differ significantly in the two limiting cases. In general, the reaction‐limited precipitation/dissolution would result in a smooth variation of k and F, which can be roughly modeled with a power function of porosity ϕ with a constant exponent. In contrast, the transport‐limited precipitation/dissolution mostly occurs near the pore throats where the fluid velocity is high. This induces a sharp change in k and F despite a minor variation in ϕ. The commonly used power laws with constant exponents are not able to describe such variations. The results also reveal that the electrical tortuosity‐based permeability prediction generally works well for rocks experiencing precipitation/dissolution if reff can be appropriately estimated, for example, with the electrical field normalized pore size Λ. The associated prediction errors are mainly due to the use of electrical tortuosity, which might be considerably larger than the true hydraulic tortuosity.