bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity of simulated mesospheric transport of nitrogen oxides to parameterized gravity waves
Authors: Meraner Katharina , Schmidt Hauke , Manzini Elisa , Funke Bernd , Gardini Angela 
Published: October 2016

AbstractGravity waves strongly influence the circulation and transport processes in the middle atmosphere. We analyze the sensitivity of the simulated mesospheric transport of nitrogen oxides (NOx) to differences in a parameterization of nonorographic gravity waves. After particularly strong sudden stratospheric warming (SSW) events as in January 2009, satellite instruments measured a strong mesospheric descent of NOx. However, this downward transport is in general underestimated in models covering this altitude range. We use simulations of the atmospheric general circulation and chemistry model HAMMONIA (Hamburg Model of Neutral and Ionized Atmosphere) to discuss both differences in a homogeneous background gravity wave source and a source related to frontal activity. The results show that the transport of NOx is highly sensitive to such differences. With a stronger gravity wave source, less NOx is transported after the SSW to the mesosphere and the elevated stratopause descends more rapidly to its climatological altitude. We observe the opposite by weakening the gravity wave sources yielding a better agreement with the observations. The amount of the transported NOx is controlled by the altitude at which momentum is deposited in the atmosphere. The higher the altitude where the momentum is deposited in the upper mesosphere, the stronger is the descent of NOx. A small wave amplitude favors the transition to turbulence at a higher altitude due to the exponential increase of the amplitude with height.
Redox dynamics in the active layer of an Arctic headwater catchment; examining the potential for transfer of dissolved methane from soils to stream water
Authors: Street Lorna E. , Dean Joshua F. , Billett Michael F. , Baxter Robert , Dinsmore Kerry J. , Lessels Jason S. , Subke Jens‐Arne , Tetzlaff Doerthe , Wookey Philip A. 
Published: October 2016

AbstractThe linkages between methane production, transport, and release from terrestrial and aquatic systems are not well understood, complicating the task of predicting methane emissions. We present novel data examining the potential for the saturated zone of active layer soils to act as a source of dissolved methane to the aquatic system, via soil water discharge, within a headwater catchment of the continuous permafrost zone in Northern Canada. We monitored redox conditions and soil methane concentrations across a transect of soil profiles from midstream to hillslope and compare temporal patterns in methane concentrations in soils to those in the stream. We show that redox conditions in active layer soils become more negative as the thaw season progresses, providing conditions suitable for net methanogenesis and that redox conditions are sensitive to increased precipitation during a storm event—but only in shallower surface soil layers. While we demonstrate that methane concentrations at depth in the hillslope soils increase over the course of the growing season as reducing conditions develop, we find no evidence that this has an influence on stream water methane concentrations. Sediments directly beneath the stream bed, however, remain strongly reducing at depth throughout the thaw season and contain methane at concentrations 5 orders of magnitude greater than those in hillslope soils. The extent of substreambed methane sources, and the rates of methane transport from these zones, may therefore be important factors determining headwater stream methane concentrations under changing Arctic hydrologic regimes.
Sulfur and iron diagenesis in temperate unsteady sediments of the East China Sea inner shelf and a comparison with tropical mobile mud belts (MMBs)
Authors: Zhu Mao‐Xu , Chen Ke‐Ke , Yang Gui‐Peng , Fan De‐Jiang , Li Tie 
Published: October 2016

AbstractRedox cycling of iron (Fe) and sulfur (S) exerts profound influences on fates of numerous elements in coastal marine sediments. In this study, S and Fe cycling and its geochemical expressions in the East China Sea (ECS) inner shelf, a representative of temperate mobile mud belts (MMBs), were characterized and compared with tropical counterparts (the Amazon shelf and the Gulf of Papua). Fe and S speciation consistently points to the dominance of authigenic nonsulfidized Fe(II) phases (i.e., poorly crystalline clays (PCCs) and carbonates) and the prevalence of Fe redox cycling in the suboxic or weakly sulfidic regimes of the ECS‐MMBs. High contents of authigenic magnetite may be a common diagenetic expression in all MMBs. Compared to the tropical MMBs, three main differences of diagenetic expressions in the ECS‐MMBs are (i) light 34Spyrite in the ECS‐MMB versus characteristically heavy 34Spyrite in the Amazon shelf MMBs; (ii) lower total reactive Fe (FeTR), total diagenetic Fe(II), and ratio of FeTR to total Fe in the ECS‐MMBs; and (iii) Fe(II) carbonates and PCCs are equally important sinks for nonsulfidized Fe(II) in the ECS‐MMBs, whereas PCCs are the predominant sink in the tropical counterparts. These differences are ascribable to factors including low degradability of organic matter, small diffusion scales, less intense chemical weathering in the drainage basin, and/or weaker reverse weathering in the ECS‐MMBs. Despite the differences above, Fe and S diagenetic expressions that characterize the prevalence of Fe redox cycling in the unsteady suboxic regimes are shared by the ECS‐MMBs and tropical MMBs.
DOM composition and transformation in boreal forest soils: The effects of temperature and organic‐horizon decomposition state
Authors: O'Donnell Jonathan A. , Aiken George R. , Butler Kenna D. , Guillemette Francois , Podgorski David C. , Spencer Robert G. M. 
Published: October 2016

AbstractThe boreal region stores large amounts of organic carbon (C) in organic‐soil horizons, which are vulnerable to destabilization via warming and disturbance. Decomposition of soil organic matter (SOM) contributes to the production and turnover of dissolved organic matter (DOM). While temperature is a primary control on rates of SOM and DOM cycling, little is known about temperature effects on DOM composition in soil leachate. Here we conducted a 30 day incubation to examine the effects of temperature (20 versus 5°C) and SOM decomposition state (moss versus fibric versus amorphous horizons) on DOM composition in organic soils of interior Alaska. We characterized DOM using bulk dissolved organic C (DOC) concentration, chemical fractionation, optical properties, and ultrahigh‐resolution mass spectrometry. We observed an increase in DOC concentration and DOM aromaticity in the 20°C treatment compared to the 5°C treatment. Leachate from fibric horizons had higher DOC concentration than shallow moss or deep amorphous horizons. We also observed chemical shifts in DOM leachate over time, including increases in hydrophobic organic acids, polyphenols, and condensed aromatics and decreases in low‐molecular weight hydrophilic compounds and aliphatics. We compared ultrahigh‐resolution mass spectrometry and optical data and observed strong correlations between polyphenols, condensed aromatics, SUVA254, and humic‐like fluorescence intensities. These findings suggest that biolabile DOM was preferentially mineralized, and the magnitude of this transformation was determined by kinetics (i.e., temperature) and substrate quality (i.e., soil horizon). With future warming, our findings indicate that organic soils may release higher concentrations of aromatic DOM to aquatic ecosystems.
Ultrahigh‐resolution mapping of peatland microform using ground‐based structure from motion with multiview stereo
Authors: Mercer Jason J. , Westbrook Cherie J. 
Published: October 2016

AbstractMicroform is important in understanding wetland functions and processes. But collecting imagery of and mapping the physical structure of peatlands is often expensive and requires specialized equipment. We assessed the utility of coupling computer vision‐based structure from motion with multiview stereo photogrammetry (SfM‐MVS) and ground‐based photos to map peatland topography. The SfM‐MVS technique was tested on an alpine peatland in Banff National Park, Canada, and guidance was provided on minimizing errors. We found that coupling SfM‐MVS with ground‐based photos taken with a point and shoot camera is a viable and competitive technique for generating ultrahigh‐resolution elevations (i.e., <0.01 m, mean absolute error of 0.083 m). In evaluating 100+ viable SfM‐MVS data collection and processing scenarios, vegetation was found to considerably influence accuracy. Vegetation class, when accounted for, reduced absolute error by as much as 50%. The logistic flexibility of ground‐based SfM‐MVS paired with its high resolution, low error, and low cost makes it a research area worth developing as well as a useful addition to the wetland scientists' toolkit.
What determines the fate of rising parcels in a heterogeneous environment?
Authors: Brast Maren , Neggers Roel A. J. , Heus Thijs 
Published: October 2016

AbstractWe investigate the potential impact of the local environment on rising parcels in a convective boundary layer. To this end, we use data from an LES simulation of a shallow convective cloud field to feed a parcel model with a range of different local environments, representative of the heterogeneous environment inside a shallow cumulus cloud layer. With this method we can study the statistics of an ensemble of rising parcels, but also the behavior of individual parcels. Through the use of a heterogeneous environment, the interactions between different parcels are indirectly represented. The method, despite its simplicity, allows closer investigation of mechanisms like parcel screening and buoyancy sorting that have frequently been proposed in cumulus parameterization. The relative importance of the entrainment formulation can be assessed, considering various classic entrainment formulations. We found that while the entrainment formulation does affect parcel behavior, the impact of the local environment is significantly more important in determining the eventual fate of the parcel. Using a constant entrainment rate can already explain much of the variation in termination heights seen in nature and LES. The more complex entrainment models then seem to act on top of this mechanism, creating second‐order adaptations in the main distribution as established by the heterogeneity of the environment. A parcel budget analysis was performed for two limit cases, providing more insight into the impact of the local environment on parcel behavior. This revealed that parcel screening inside cumulus clouds can be effective in enabling parcels to reach greater heights.
Assimilation of thermospheric measurements for ionosphere‐thermosphere state estimation
Authors: Miladinovich Daniel S. , Datta‐Barua Seebany , Bust Gary S. , Makela Jonathan J. 
Published: October 2016

AbstractWe develop a method that uses data assimilation to estimate ionospheric‐thermospheric (IT) states during midlatitude nighttime storm conditions. The algorithm Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE) uses time‐varying electron densities in the F region, derived primarily from total electron content data, to estimate two drivers of the IT: neutral winds and electric potential. A Kalman filter is used to update background models based on ingested plasma densities and neutral wind measurements. This is the first time a Kalman filtering technique is used with the EMPIRE algorithm and the first time neutral wind measurements from 630.0 nm Fabry‐Perot interferometers (FPIs) are ingested to improve estimates of storm time ion drifts and neutral winds. The effects of assimilating remotely sensed neutral winds from FPI observations are studied by comparing results of ingesting: electron densities (N) only, N plus half the measurements from a single FPI, and then N plus all of the FPI data. While estimates of ion drifts and neutral winds based on N give estimates similar to the background models, this study's results show that ingestion of the FPI data can significantly change neutral wind and ion drift estimation away from background models. In particular, once neutral winds are ingested, estimated neutral winds agree more with validation wind data, and estimated ion drifts in the magnetic field‐parallel direction are more sensitive to ingestion than the field‐perpendicular zonal and meridional directions. Also, data assimilation with FPI measurements helps provide insight into the effects of contamination on 630.0 nm emissions experienced during geomagnetic storms.
Drainage dynamics controlled by corner flow: Application of the foam drainage equation
Authors: Hoogland Frouke , Lehmann Peter , Or Dani 
Published: October 2016

AbstractIn fast drainage processes water is retained behind the front, defining the plant available water and hydraulic properties of the unsaturated region. In this study we show that the foam drainage equation (FDE) can be applied to predict macroscopic drainage dynamics behind the front because a network of liquid channels controls the liquid flow in both foams and crevices of the pore space. To predict drainage rates at the Darcy scale the FDE is solved numerically after adapting channel geometries and boundary conditions to experimental conditions. The FDE results were in good agreement with measured flow rates behind a drainage front in coarse and fine sand. A notable exception was rapid drainage from fine sand where saturated pore clusters persisted after front passage and drained faster compared to FDE predictions. The dominance of corner capillary flows implied by the good agreement with the FDE formulation could improve the scientific underpinning of the unsaturated hydraulic conductivity function and offers a more realistic view of the geometry of pathways for colloid and pathogen transport in unsaturated media.
Organoaluminum Compounds in Catalytic EnantioselectiveCCBond Forming Reactions
Authors: McGrath Kevin P. , Hoveyda Amir H. 
Published: October 2016

AbstractDifferentorganoaluminum compounds have found use as reagents in catalytic enantioselective CC bond forming reactions. A hallmark of these processes is their efficiency, which is largely rooted in their high activity (especially versus a dialkylzinc species) and stronger Lewis acidity of the corresponding metal center (e.g., as opposed to an organomagnesium). Specifically, readily available trialkylaluminum compound such as Me3Al and Et3Al have been utilized in reactions that involve carbonyl‐ or imine‐containing compounds as well as allylic phosphates (allylic substitutions) or α,β‐unsaturated ketones or esters (conjugate additions). Notable are transformations where an alkenyl, an alkynyl or an arylaluminum reagent is generatedin situby hydroalumination or deprotonation of an alkyne or from the reaction of an aryl or heteroaryllithium or magnesium halide with an inexpensive dialkylaluminumhalide. When dialkyl(alkenyl)‐, dialkyl(alkynyl) or dialkyl(aryl)aluminum compounds are involved, it is the unsaturated moiety that is transferred predominantly. Applications to synthesis of biologically active compounds that involve the use of the above transformations will be presented.
Influences of Fertility Status on Risky Driving Behaviour
Authors: Biassoni Federica , Iannello Paola , Antonietti Alessandro , Ciceri Maria Rita 
Published: October 2016

SummaryThe effects of hormones on human behaviour have been extensively studied, but little attention has been paid to the influence of ovarian hormones on risky driving. Twenty‐five normally cycling women took part in three sessions, including an ovulatory phase estimation session and two experimental sessions: high vs low fertile phases. These two phases were monitored through a urine‐based luteinizing hormone predictor test. In the two experimental sessions, participants were administered the Driving Behaviour Questionnaire and the Vienna Risk‐Taking Test. Results showed that women are more risk‐averse in their driving behaviour during their high‐fertile phase. The influence of hormonal fluctuations on self‐perception of risk attitude when driving was non‐significant. Findings are discussed from an evolutionary perspective. Copyright © 2016 John Wiley & Sons, Ltd.
Cross‐Sectional and Longitudinal Associations of Diffuse Idiopathic Skeletal Hyperostosis and Thoracic Kyphosis in Older Men and Women
Authors: Katzman Wendy B. , Parimi Neeta , Mansoori Ziba , Nardo Lorenzo , Kado Deborah M. , Cawthon Peggy M. , Marshall Lynn M. , Schousboe John T. , Lane Nancy E. ,   for the Osteoporotic Fractures in Men Study Research Group and the Study of Osteoporotic Fractures
Published: October 2016

ObjectiveTo investigate cross‐sectional and longitudinal associations of diffuse idiopathic skeletal hyperostosis (DISH) and thoracic kyphosis in older persons.MethodsDISH and kyphosis were assessed in 1,500 men from the Osteoporotic Fractures in Men (MrOS) study and in 1,267 women from the Study of Osteoporotic Fractures (SOF). DISH was assessed using baseline lateral spine radiographs, and Cobb angle of kyphosis was measured from baseline and followup radiographs, a mean 4.6 years later in men, and 3.7 and 15 years later in women. Linear regression was used to analyze associations of DISH with baseline Cobb angle and with percent annualized change in Cobb angle. We tested for heterogeneity among studies.ResultsDISH was identified in 222 participants in MrOS (15%) and in 156 participants in SOF (12%). Participants with DISH in both cohorts had higher baseline Cobb angles (P < 0.05), after adjustment for covariates. After approximately 4 years of followup, there was no significant difference in annualized percent change in Cobb angle in those with DISH compared to those without DISH (P > 0.05) for men or women. Women with DISH had less kyphosis progression over 15 years (0.25% less annualized change in Cobb) than those without DISH.ConclusionPrevalent DISH is associated with greater kyphosis in older men and women, and is not significantly associated with a change in kyphosis over 4–5 years. However, in women followed over 15 years, DISH was associated with less progression of kyphosis. These results suggest that DISH influences kyphosis and may slow progression over the long term. Additional studies of DISH/kyphosis associations are warranted to understand the functional implications of this finding.
Association Between Biochemical Markers of Bone Turnover and Bone Changes on Imaging: Data From the Osteoarthritis Initiative
Authors: Deveza Leticia A. , Kraus Virginia B. , Collins Jamie E. , Guermazi Ali , Roemer Frank W. , Bowes Michael , Nevitt Michael C. , Ladel Christoph , Hunter David J. 
Published: October 2016

ObjectiveTo determine the relationship between biochemical markers involved in bone turnover and bone features on imaging in knees with osteoarthritis (OA).MethodsWe analyzed data from the Foundation for the National Institutes of Health OA Biomarkers Consortium within the Osteoarthritis Initiative (n = 600). Bone marrow lesions (BMLs), osteophytes, and subchondral bone area (mm2) and shape (position on 3‐D vector) were assessed on magnetic resonance images, and bone trabecular integrity (BTI) was assessed on radiographs. Serum and urinary markers (serum C‐terminal crosslinked telopeptide of type I collagen [CTX‐I], serum crosslinked N‐telopeptide of type I collagen [NTX‐I], urinary NTX‐I, urinary C‐terminal crosslinked telopeptide of type II collagen [CTX‐II], and urinary CTX‐Iα and CTX‐Iβ) were measured. The associations between biochemical and imaging markers at baseline and over 24 months were assessed using regression models adjusted for covariates.ResultsAt baseline, most biochemical markers were associated with BMLs, with C statistics for the presence/absence of any BML ranging from 0.675 to 0.688. At baseline, urinary CTX‐II was the marker most consistently associated with BMLs (with odds of having ≥5 subregions affected compared to no BML increasing by 1.92‐fold [95% confidence interval (95% CI) 1.25, 2.96] per 1 SD of urinary CTX‐II), large osteophytes (odds ratio 1.39 [95% CI 1.10, 1.77]), bone area and shape (highest partial R2 = 0.032), and changes in bone shape over 24 months (partial R2 range 0.008 to 0.024). Overall, biochemical markers were not predictive of changes in BMLs or osteophytes. Serum NTX‐I was inversely associated with BTI of the vertical trabeculae (quadratic slope) in all analyses (highest partial R2 = 0.028).ConclusionWe found multiple significant associations, albeit mostly weak ones. The role of systemic biochemical markers as predictors of individual bone anatomic features of single knees is limited based on our findings.
DNMT3A mutations are associated with inferior overall and leukemia‐free survival in chronic myelomonocytic leukemia
Authors: Patnaik Mrinal M. , Barraco Daniela , Lasho Terra L. , Finke Christy M. , Hanson Curtis A. , Ketterling Rhett P. , Gangat Naseema , Tefferi Ayalew 
Published: October 2016

DNMT3A mutations are seen in ∼5% of patients with chronic myelomonocytic leukemia (CMML) and thus far, have had an indeterminate prognostic impact on survival. We carried out this study to assess the prognostic impact of DNMT3A mutations on a larger informative cohort of CMML patients (n = 261). DNMT3A mutations were seen in 6% (n = 16); 56% (n = 9) male, with a median age of 64 years. Eighty‐one % of DNMT3A mutations were missense, with the Arg882 mutational hot spot accounting for 63% of all changes. Five (31%) patients had an abnormal karyotype whereas concurrent gene mutations (SF3B1/SRSF2/U2AF1−56%, TET2−50%, and ASXL1−25%) were seen in all patients. Apart from a higher frequency of SF3B1 (P = 0.0001) and PTPN11 (P = 0.005) mutations and a lower frequency of SRSF2 (P = 0.004) mutations, there were no significant differences between DNMT3A mutated patients and their wildtype counterparts. In univariate analysis, survival was shorter in DNMT3A mutated (median 8 months) versus wildtype (median 27 months) patients (P = 0.0007; HR 2.9, 95% CI 1.5–5.7); with other variables of significance including lower hemoglobin (P = 0.002), higher leukocyte count (P = 0.0009), higher monocyte count (P = 0.0012), circulating blast % (P = 0.001), circulating immature myeloid cells (P = 0.01), bone marrow blast % (P = 0.045), abnormal karyotype (P = 0.02), and ASXL1 (P = 0.01) mutations. In a multivariable model that included the aforementioned variables, when both DNMT3A and ASXL1 mutations were added, only DNMT3A (P < 0.0001) and ASXL1 (P = 0.004) mutations remained significant. DNMT3A mutations were also predictive of a shortened leukemia‐free survival. These findings warrant inclusion of DNMT3A mutations in molecularly integrated CMML prognostic models. Am. J. Hematol. 92:56–61, 2017. © 2016 Wiley Periodicals, Inc.
DTBP/TBHP‐Promoted Hydroacylation of Unactivated Alkenes
Authors: Jhuang Huei‐Shu , Reddy Daggula Mallikarjuna , Chen Te‐Hsuan , Lee Chin‐Fa 
Published: October 2016

AbstractDi‐tert‐butyl peroxide (DTBP)‐promoted intermolecular hydroacylation reaction of alkenes with aromatic aldehydes that provides ketones is described. In this study, 4‐chromanones were formed when 2‐(allyloxy)benzaldehydes were treated with tert‐butyl hydroperoxide (TBHP). The reactions were performed under solvent‐ and metal‐free conditions. Reactions proceeded through the generation of acyl radicals, followed by the reaction with alkenes. Remarkably, not only terminal alkenes but also internal alkenes could serve as the starting materials for intramolecular hydroacylation reaction.