bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anomalous dispersion of sea ice in the Fram Strait region
Authors: Gabrielski A. , Badin G. , Kaleschke L. 
Published: February 2015

AbstractThe single‐particle dispersion of sea ice in the Fram Strait region is investigated using ice drift buoys deployed from 2002 to 2009 within the Fram Strait Cyclones and the Arctic Climate System Study campaigns. A new method to estimate the direction of the mean flow, based on a satellite drift product, is introduced. As a result, the bias in the dispersion introduced by the mean flow is eliminated considering only the displacements of the buoys in the cross‐stream direction. Results show an absolute dispersion growing quadratically in time for the first 3 days and an anomalous dispersion regime exhibiting a strongly self‐similar scaling following a 5/4 power law for time scales larger than 6 days persisting over the whole time series of length 32 days. The non‐Gaussian distribution of the velocity fluctuations with a skewness of −0.15 and a kurtosis of 7.33 as well as the slope of the Lagrangian frequency spectrum between −2 and −1 are in agreement with the anomalous diffusion regime. Comparison with data from the International Arctic Buoy Program yields similar results with an anomalous dispersion starting after 10 days and persisting over the whole time series of length 50 days. The results suggest the presence of deformation and shear acting on the sea ice dispersion. The high correlation between the cross‐stream displacements and the cross‐stream wind velocities shows the important role of the wind as a source for the anomalous dispersion.
A multiyear dust devil vortex survey using an automated search of pressure time series
Authors: Jackson Brian , Lorenz Ralph 
Published: February 2015

AbstractDust devils occur in arid climates on the Earth and ubiquitously on Mars, where they likely dominate the supply of atmospheric dust and influence climate. Martian dust devils have been studied with a combination of orbiting and landed spacecraft, while most studies of terrestrial dust devils have involved manned monitoring of field sites, which can be costly both in time and personnel. As an alternative approach, we describe a multiyear in situ survey of terrestrial dust devils using pressure loggers deployed at El Dorado Playa in Nevada, USA, a site known for dust devil activity. Analogous to previous surveys for Martian dust devils, we conduct a posthoc analysis of the barometric data to search for putative dust devil pressure dips using a new automated detection algorithm. We investigate the completeness and false positive rates of our new algorithm and conduct several statistically robust analyses of the resulting population of dips. We also investigate possible seasonal, annual, and spatial variability of the putative dust devil dips, possible correlations with precipitation, and the influence of sample size on the derived population statistics. Our results suggest that large numbers of dips (>1000) collected over multiple seasons are probably required for accurate assessment of the underlying dust devil population. Correlating long‐term barometric time series with other data streams (e.g., solar flux measurements from photovoltaic cells) can uniquely elucidate the natures and origins of dust devils, and accurately assessing their influence requires consideration of the full distribution of dust devil properties, rather than average values.
Constraining a coupled erosion and soil organic carbon model using hillslope‐scale patterns of carbon stocks and pool composition
Authors: Wang Zhengang , Doetterl Sebastian , Vanclooster Marnik , van Wesemael Bas , Van Oost Kristof 
Published: February 2015

AbstractA large amount of soil organic carbon (SOC) is laterally redistributed by agricultural erosion. Recent studies have shown that this leads to strong horizontal (i.e., spatial) and vertical (i.e., with soil depth) gradients in SOC stock and C pool distribution in eroding landscapes. However, the mechanisms leading to these gradients in relation to erosion and deposition are still poorly documented. In particular, the effect of the inherent properties of SOC (as controlled by the SOC pool composition) versus the effect of depth‐related soil environmental condition (i.e., differences in soil humidity, temperature, aeration, etc.) on the persistence of SOC in eroding landscapes is uncertain. Nonetheless, a detailed understanding of these factors is important to correctly assess landscape‐scale soil C turnover and vulnerability to disturbance from human activities. This study utilizes observational data on long‐term erosion/deposition rates and C pool composition derived from soil C fractionation experiments along an eroding agricultural hillslope to constrain a coupled erosion‐SOC dynamics model. The simulation results show that the data set used can result in a robust parameter estimation of a multipool C model for an eroding landscape with parameter values that are consistent with incubation experiments. A scenario analysis, where we evaluate the contribution of different processes, demonstrates that soil redistribution is essential to explain the observation that depositional locations contain more SOC in subsoils, while the SOC content of the surface layer is similar to those observed along an eroding hillslope. The spatial variability of plant production could explain some of the observed variability in SOC content, but our results suggest that the spatial variability of SOC pool composition is mainly related to soil redistribution. Finally, we suggest that environmental factors may play a more important role than the inherent properties of SOC in determining the vertical variation of SOC mineralization. This implies that depositional C stocks might be highly vulnerable to disturbance from human activities that may reconnect the buried SOC with the atmosphere.
Importance of nondiffusive transport for soil CO2 efflux in a temperate mountain grassland
Authors: Roland Marilyn , Vicca Sara , Bahn Michael , Ladreiter‐Knauss Thomas , Schmitt Michael , Janssens Ivan A. 
Published: February 2015

AbstractSoil respiration and its biotic and abiotic drivers have been an important research topic in recent years. While the bulk of these efforts has focused on the emission of CO2 from soils, the production and subsequent transport of CO2 from soil to atmosphere received far less attention. However, to understand processes underlying emissions of CO2 from terrestrial ecosystems, both processes need to be fully evaluated. In this study, we tested to what extent the transport of CO2 in a grassland site in the Austrian Alps could be modeled based on the common assumption that diffusion is the main transport mechanism for trace gases in soils. Therefore, we compared the CO2 efflux calculated from the soil CO2 concentration gradient with the CO2 efflux from chamber measurements. We used four commonly used diffusion‐driven models for the flux‐gradient approach. Models generally underestimated the soil chamber effluxes and their amplitudes, indicating that processes other than diffusion were responsible for the transport of CO2. We further observed that transport rates correlated well with irradiation and, below a soil moisture content of 33%, with wind speed. This suggests that mechanisms such as bulk soil air transport, due to pressure pumping or thermal expansion of soil air due to local surface heating, considerably influence soil CO2 transport at this site. Our results suggest that nondiffusive transport may be an important mechanism influencing diel and day‐to‐day dynamics of soil CO2 emissions, leading to a significant mismatch (10–87% depending on the model used) between the two approaches at short time scales.
Regionally coupled atmosphere‐ocean‐sea ice‐marine biogeochemistry model ROM: 1. Description and validation
Authors: Sein Dmitry V. , Mikolajewicz Uwe , Gröger Matthias , Fast Irina , Cabos William , Pinto Joaquim G. , Hagemann Stefan , Semmler Tido , Izquierdo Alfredo , Jacob Daniela 
Published: February 2015

AbstractThe general circulation models used to simulate global climate typically feature resolution too coarse to reproduce many smaller‐scale processes, which are crucial to determining the regional responses to climate change. A novel approach to downscale climate change scenarios is presented which includes the interactions between the North Atlantic Ocean and the European shelves as well as their impact on the North Atlantic and European climate. The goal of this paper is to introduce the global ocean‐regional atmosphere coupling concept and to show the potential benefits of this model system to simulate present‐day climate. A global ocean‐sea ice‐marine biogeochemistry model (MPIOM/HAMOCC) with regionally high horizontal resolution is coupled to an atmospheric regional model (REMO) and global terrestrial hydrology model (HD) via the OASIS coupler. Moreover, results obtained with ROM using NCEP/NCAR reanalysis and ECHAM5/MPIOM CMIP3 historical simulations as boundary conditions are presented and discussed for the North Atlantic and North European region. The validation of all the model components, i.e., ocean, atmosphere, terrestrial hydrology, and ocean biogeochemistry is performed and discussed. The careful and detailed validation of ROM provides evidence that the proposed model system improves the simulation of many aspects of the regional climate, remarkably the ocean, even though some biases persist in other model components, thus leaving potential for future improvement. We conclude that ROM is a powerful tool to estimate possible impacts of climate change on the regional scale.
From analytical solutions of solute transport equations to multidimensional time‐domain random walk (TDRW) algorithms
Authors: Bodin Jacques 
Published: February 2015

AbstractIn this study, new multi‐dimensional time‐domain random walk (TDRW) algorithms are derived from approximate one‐dimensional (1‐D), two‐dimensional (2‐D), and three‐dimensional (3‐D) analytical solutions of the advection‐dispersion equation and from exact 1‐D, 2‐D, and 3‐D analytical solutions of the pure‐diffusion equation. These algorithms enable the calculation of both the time required for a particle to travel a specified distance in a homogeneous medium and the mass recovery at the observation point, which may be incomplete due to 2‐D or 3‐D transverse dispersion or diffusion. The method is extended to heterogeneous media, represented as a piecewise collection of homogeneous media. The particle motion is then decomposed along a series of intermediate checkpoints located on the medium interface boundaries. The accuracy of the multi‐dimensional TDRW method is verified against (i) exact analytical solutions of solute transport in homogeneous media and (ii) finite‐difference simulations in a synthetic 2‐D heterogeneous medium of simple geometry. The results demonstrate that the method is ideally suited to purely diffusive transport and to advection‐dispersion transport problems dominated by advection. Conversely, the method is not recommended for highly dispersive transport problems because the accuracy of the advection‐dispersion TDRW algorithms degrades rapidly for a low Péclet number, consistent with the accuracy limit of the approximate analytical solutions. The proposed approach provides a unified methodology for deriving multi‐dimensional time‐domain particle equations and may be applicable to other mathematical transport models, provided that appropriate analytical solutions are available.
Model averaging methods to merge operational statistical and dynamic seasonal streamflow forecasts in Australia
Authors: Schepen Andrew , Wang Q. J. 
Published: February 2015

AbstractThe Australian Bureau of Meteorology produces statistical and dynamic seasonal streamflow forecasts. The statistical and dynamic forecasts are similarly reliable in ensemble spread; however, skill varies by catchment and season. Therefore, it may be possible to optimize forecasting skill by weighting and merging statistical and dynamic forecasts. Two model averaging methods are evaluated for merging forecasts for 12 locations. The first method, Bayesian model averaging (BMA), applies averaging to forecast probability densities (and thus cumulative probabilities) for a given forecast variable value. The second method, quantile model averaging (QMA), applies averaging to forecast variable values (quantiles) for a given cumulative probability (quantile fraction). BMA and QMA are found to perform similarly in terms of overall skill scores and reliability in ensemble spread. Both methods improve forecast skill across catchments and seasons. However, when both the statistical and dynamical forecasting approaches are skillful but produce, on special occasions, very different event forecasts, the BMA merged forecasts for these events can have unusually wide and bimodal distributions. In contrast, the distributions of the QMA merged forecasts for these events are narrower, unimodal and generally more smoothly shaped, and are potentially more easily communicated to and interpreted by the forecast users. Such special occasions are found to be rare. However, every forecast counts in an operational service, and therefore the occasional contrast in merged forecasts between the two methods may be more significant than the indifference shown by the overall skill and reliability performance.
Chaotic level mixing in a two‐band Bose‐Hubbard model
Authors: Parra‐Murillo Carlos A. , Madroñero Javier , Wimberger Sandro 
Published: February 2015

A two‐band Bose‐Hubbard model is presented which is shown to be minimal in the necessary coupling terms at resonant tunneling conditions. The dynamics of the many‐body problem is studied by sweeping the system across an avoided level crossing. The linear sweep generalizes Landau‐Zener transitions from single‐particle to many‐body realizations. The temporal evolution of single‐ and two‐body observables along the sweeps is investigated in order to characterize the non‐equilibrium dynamics in our complex quantum system.
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Remote Chiral Communication in Coadsorber‐Induced Enantioselective 2D Supramolecular Assembly at a Liquid/Solid Interface
Authors: Chen Ting , Li Shu‐Ying , Wang Dong , Yao Man , Wan Li‐Jun 
Published: February 2015

AbstractRemote chiral communication in 2D supramolecular assembly at a liquid/solid interface was investigated at the molecular level. The stereochemical information in a chiral coadsorber was transmitted over a flexible spacer with a length of up to five methylene groups to a 2D supramolecular assembly of achiral building blocks with the cooperation of specific hydrogen bonding between the chiral coadsorber and achiral building blocks and the confinement effect during 2D crystallization. When the position of the stereogenic center was changed with respect to the stereocontrolling moiety, an odd–even effect was found. A stereogenic center closer to the stereocontrolling moiety transmitted the stereochemical information to the 2D supramolecular assembly more reliably. This result is beneficial not only for mechanistic understanding of chiral communication in 2D supramolecular assembly on surfaces but also for the rational design of homochiral supramolecular assemblies on surfaces.
Directed Evolution of RebH for Site‐Selective Halogenation of Large Biologically Active Molecules
Authors: Payne James T. , Poor Catherine B. , Lewis Jared C. 
Published: February 2015

AbstractWe recently characterized the substrate scope of wild‐type RebH and proceeded to evolve variants of this enzyme with improved stability for biocatalysis. The substrate scopes of both RebH and the stabilized variants, however, are limited primarily to compounds similar in size to tryptophan. A substrate walking approach was used to further evolve RebH variants with expanded substrate scope. Two particularly notable variants were identified: 3‐SS, which provides high conversion of tricyclic tryptoline derivatives; and 4‐V, which accepts a broad range of large indoles and carbazoles. This constitutes the first reported use of directed evolution to enable the functionalization of substrates not accepted by wild‐type RebH and demonstrates the utility of RebH variants for the site‐selective halogenation of biologically active compounds.
Magnetic‐field‐assisted electrospinning highly aligned composite nanofibers containing well‐aligned multiwalled carbon nanotubes
Authors: Mei Lin‐Yu , Song Ping , Liu Ya‐Qing 
Published: February 2015

ABSTRACTComposite nanofiber meshes of well‐aligned polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) nanofibers containing multiwalled carbon nanotubes (MWCNTs) were successfully fabricated by a magnetic‐field‐assisted electrospinning (MFAES) technology, which was confirmed to be a favorable method for preparation of aligned composite nanofibers in this article. The MFAES experiments showed that the diameters of composite nanofibers decreased first and then increased with the increase of voltage and MWCNTs content. With the increase of voltage, the degree of alignment of the composite nanofibers decreased, whereas it increased with increasing MWCNTs concentration. Transmission electron microscopy observation showed that MWCNTs were parallel and oriented along the axes of the nanofibers under the low concentration. A maximum enhancement of 178% in tensile strength was manifested by adding 2 wt % MWCNTs in well‐aligned composite nanofibers. In addition, the storage modulus of PAN/PVP/MWCNTs composite nanofibers was significantly higher than that of the PAN/PVP nanofibers. Besides, due to the highly ordered alignment structure, the composite nanofiber meshes showed large anisotropic surface resistance, that is, the surface resistance of the composite nanofiber films along the fiber axis was about 10 times smaller than that perpendicular to the axis direction. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41995.
Chloromethane–Water Adduct: Rotational Spectrum, Weak Hydrogen Bonds, and Internal Dynamics
Authors: Gou Qian , Spada Lorenzo , Lòpez Juan Carlos , Grabow Jens‐Uwe , Caminati Walther 
Published: February 2015

AbstractThe rotational spectra of four isotopologues of the 1:1 complex between chloromethane and water revealed the presence of only one rotamer in a pulsed jet expansion. The two subunits are linked through two weak hydrogen bonds, OH⋅⋅⋅Cl (RH⋅⋅⋅Cl=2.638(2) Å) and CH⋅⋅⋅O (RH⋅⋅⋅O=2.501(2) Å), forming a five‐membered ring. All transitions display the hyperfine structure due to the 35Cl (or 37Cl) nuclear quadrupole effects. Dynamical features in the spectrum are caused by two large‐amplitude motions. Each component line appears as an asymmetric doublet with a relative intensity ratio of 1:3. The splittings led to the determination of barrier to internal rotation of water around its symmetry axis, V2=320(10) cm−1. Finally, an unexpected small value of the inertial defect (−0.96 uÅ2 rather than −3.22 uÅ2) allowed the estimation of the barrier to the internal rotation of the CH3 group, V3≈8 cm−1.
Dibenzocarbazolediimides: Synthesis, Solid Structure, Self‐Assembly Behavior, and Optoelectronic Properties
Authors: Wu Di , Zhang Yufeng , Zhang Jing , Liu Sheng Hua , Yin Jun 
Published: February 2015

AbstractBoth planar and nonplanar polycyclic aromatic hydrocarbons (PAHs) have attracted attention owing to their potential applications in optoelectronic materials. Four twist benzopicenediimides with good optoelectronic properties have been reported previously. Following on from this work, four functionalized dibenzocarbazoles have been synthesized and reported herein. The fluorescence quantum yields of these compounds were high in dichloromethane and moderate in the solid state. They have interesting self‐assembling behavior and tunable packing motifs in single crystals obtained by introducing different functional groups. Their good optoelectronic properties make them potential candidates for organic devices, bioimaging, and biolabeling.
Investigation of omeprazole and phenacetin first‐pass metabolism in humans using a microscale bioreactor and pharmacokinetic models
Authors: Bricks Thibault , Hamon Jérémy , Fleury Marie José , Jellali Rachid , Merlier Franck , Herpe Yves Edouard , Seyer Alexandre , Regimbeau Jean‐Marc , Bois Frédéric , Leclerc Eric 
Published: February 2015

AbstractA new in vitro microfluidic platform (integrated insert dynamic microfluidic platform, IIDMP) allowing the co‐culture of intestinal Caco‐2 TC7 cells and of human primary hepatocytes was used to test the absorption and first‐pass metabolism of two drugs: phenacetin and omeprazole. The metabolism of these drugs by CYP1A2, CYP2C19 and CYP3A4 was evaluated by the calculation of bioavailabilities and of intrinsic clearances using a pharmacokinetic (PK) model. To demonstrate the usefulness of the device and of the PK model, predictions were compared with in vitro and in vivo results from the literature. Based on the IIDMP experiments, hepatic in vivo clearances of phenacetin and omeprazole in the IIDMP were predicted to be 3.10 ± 0.36 and 1.46 ± 0.25 ml/min/kg body weight, respectively. This appeared lower than the in vivo observed data with values ranging between 11.9–19.6 and 5.8–7.5 ml/min/kg body weight, respectively. Then the calculated hepatic and intestinal clearances led to predicting an oral bioavailability of 0.85 and 0.77 for phenacetin and omeprazole versus 0.92 and 0.78 using separate data from the simple monoculture of Caco‐2 TC7 cells and hepatocytes in Petri dishes. When compared with the in vivo data, the results of oral bioavailability were overestimated (0.37 and 0.71, respectively). The feasibility of co‐culture in a device allowing the integration of intestinal absorption, intestinal metabolism and hepatic metabolism in a single model was demonstrated. Nevertheless, further experiments with other drugs are needed to extend knowledge of the device to predict oral bioavailability and intestinal first‐pass metabolism. Copyright © 2015 John Wiley & Sons, Ltd.
Physiological Correlates of Choice‐Induced Dissonance: An Exploration of HPA‐Axis Responses
Authors: Kimel Sasha Y. , Lopez‐Duran Nestor , Kitayama Shinobu 
Published: February 2015

AbstractChoice can produce a negatively arousing cognitive conflict (called dissonance), which is thought to motivate the chooser to spread their preferences for the relevant options (called Spreading of Alternatives, or SA). The current work aimed to determine the relationship between HPA‐axis activity and both choice‐induced dissonance and its reduction (i.e. SA) among individuals with varying cultural backgrounds. European–Americans and Asians made a choice between two equally attractive CDs either in the presence of a cue indicative of social eyes (i.e. public‐choice condition) or in the absence thereof (i.e. private‐choice condition). As predicted, European–Americans and Asians showed a reliable SA primarily in the private and public choice conditions, respectively. Importantly, a sharp decline of salivary cortisol was observed over the span of 30 min, and, moreover, this decline was reliably predicted by the magnitude of SA regardless of either culture or the choice being private vs. public. These results suggest that although choice‐induced dissonance is too weak to elicit an HPA‐axis stress response, SA is associated with variability in the decline of salivary cortisol during the laboratory task. Copyright © 2015 John Wiley & Sons, Ltd.