bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrodynamic condition and suspended sediment diffusion in the Yellow Sea and East China Sea
Authors: Li Guangxue , Qiao Lulu , Dong Ping , Ma Yanyan , Xu Jishang , Liu Shidong , Liu Yong , Li Jianchao , Li Pin , Ding Dong , Wang Nan , Olusegun A Dada , Liu Ling 
Published: August 2016

AbstractBased on monthly averaged current, temperature, and salinity, we analyzed the changes of suspended sediment concentration (SSC) and the relationship with the warm current, coastal current, and cold water mass (CWM) in the East China Seas (ECSs). The result shows that the coastal current and surface diluted water are the route for transporting suspended sediment. The Kuroshio and its derived warm current branches play the important role of the continental shelf circulation system and control the diffusion of suspended sediment. High SSC has been mainly concentrated in coastal current and CWM. Two sedimentary dynamic patterns have been identified. The winter‐half‐year pattern lasts almost 7 months. The coastal currents off the Shandong Peninsula, northern Jiangsu, Zhejiang‐Fujian coast are the main routes for diffusion and deposition of the suspended sediment from the Yellow River and Changjiang River. The summer‐half‐year pattern is characterized by the well‐developed CWM. All CWMs have a unique function to trap suspended sediment under the thermocline due to weakening tidal current and residual current there. These CWMs in the Yellow Sea (YS) and north ECS are connected together. The layer above the thermocline is characterized by diluted water with low salinity, high temperature. Suspended sediment can be transported into the Okinawa Trough and the South Korea coast during this period. A strong eddy always occur nearby the Kuroshio bend at northeast Taiwan, which has promoted the exchange between the ECS shelf and Okinawa Trough, and the development of the shelf edge current and Taiwan warm current (TWC).
Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance
Authors: Balch William M. , Bates Nicholas R. , Lam Phoebe J. , Twining Benjamin S. , Rosengard Sarah Z. , Bowler Bruce C. , Drapeau Dave T. , Garley Rebecca , Lubelczyk Laura C. , Mitchell Catherine , Rauschenberg Sara 
Published: August 2016

AbstractThe Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% of the global ocean and is thought to result from elevated, seasonal concentrations of coccolithophores. Here we describe field observations and experiments from two cruises that crossed the GCB in the Atlantic and Indian sectors of the SO. We confirm the presence of coccolithophores, their coccoliths, and associated optical scattering, located primarily in the region of the subtropical, Agulhas, and Subantarctic frontal regions. Coccolithophore‐rich regions were typically associated with high‐velocity frontal regions with higher seawater partial pressures of CO2 (pCO2) than the atmosphere, sufficient to reverse the direction of gas exchange to a CO2 source. There was no calcium carbonate (CaCO3) enhancement of particulate organic carbon (POC) export, but there were increased POC transfer efficiencies in high‐flux particulate inorganic carbon regions. Contemporaneous observations are synthesized with results of trace‐metal incubation experiments, 234Th‐based flux estimates, and remotely sensed observations to generate a mandala that summarizes our understanding about the factors that regulate the location of the GCB.
Regional patterns in current and future export production in the central Arctic Ocean quantified from nitrate fluxes
Authors: Randelhoff Achim , Guthrie John D. 
Published: August 2016

AbstractDue to severe nutrient and light limitation, the central Arctic Ocean has been characterized as a region of low primary productivity, with high retention of carbon in the surface waters. Using an in‐depth analysis of published and new measurements of turbulent microstructure and high‐resolution profiles of nitrate concentration, we reassess the vertical supply of nitrate to the Polar Mixed Layer and the associated export of particulate organic matter across the nitracline. We estimate annual export production to be approximately 1.5–3 g C m−2, but regional differences in both current and future potential of export production are large, with the eastern Arctic being least constrained by vertical nutrient supply and the western Arctic the most. Future changes in export production are assessed using a 1‐D budget model; increases in the Atlantic sector are possibly compensated by decreases in the rest of the central Arctic Ocean such that the net change might be insignificant.
Late Neogene changes in North America and Antarctica absolute plate motions inferred from the Mid‐Atlantic and Southwest Indian Ridges spreading histories
Authors: Iaffaldano G. , DeMets C. 
Published: August 2016

AbstractReconstructions of absolute plate motions underpin our understanding of the plate torque balance, but are challenging due to difficulties in inferring well‐dated rates and directions of plate movements from hot spot tracks. Useful information about plate dynamics can be inferred from rapid absolute plate motion changes, as these are linked only to the torque(s) that changed. Here we infer late Neogene changes in the absolute motions of North America and possibly Antarctica from changes in the easier‐to‐determine relative plate motions recorded along the Arctic, northern Mid‐Atlantic and Southwest Indian Ridges. We show that Eurasia/North America and Nubia/North America motions changed by the same amount between 8 and 5 Ma, as may have Nubia/Antarctica and Somalia/Antarctica plate motions. By considering additional, independent constraints on Somalia/India plate motion, we argue that a scenario in which North America and Antarctica absolute motions changed is the simplest one that explains the observed changes in relative motions. We speculate that these changes are linked to the late Neogene dynamics of the Pacific plate.
Alfvén wave‐driven ionospheric mass outflow and electron precipitation during storms
Authors: Hatch S. M. , Chaston C. C. , LaBelle J. 
Published: August 2016

AbstractWe explore the global Alfvénic response of the transition region between the topside ionosphere and magnetosphere to geomagnetic storms. From superposed epoch and storm phase‐dependent analyses, it is found that subsequent to storm commencement the occurrence rate of Alfvénic field variations on electron inertial scales through this region increases by as much as a factor of 5 relative to prestorm levels. This increase is accompanied by order‐of‐magnitude enhancements in coincident energy deposition rates into the ionosphere and ion outflow rates into the magnetosphere, particularly near noon, premidnight, and on the dawn flank. During main phase on the dayside these waves shift to lower invariant latitudes (ILATs), expanding over a large range of ILATs and magnetic local times, where they are associated with significant enhancements in upward ion flux. Nightside storm‐enhanced occurrence probability of Alfvén waves and upward ion flux is lower than on the dayside, but the average precipitating electron energy flux is larger. There is also a localized region of intense ion outflow premidnight at low latitudes during storm main phase. Wave occurrence rates subside to prestorm levels about 20 h after storm commencement.
Solar quiet current response in the African sector due to a 2009 sudden stratospheric warming event
Authors: Bolaji O. S. , Oyeyemi E. O. , Owolabi O. P. , Yamazaki Y. , Rabiu A. B. , Okoh D. , Fujimoto A. , Amory‐Mazaudier C. , Seemala G. K. , Yoshikawa A. , Onanuga O. K. 
Published: August 2016

AbstractWe present solar quiet (Sq) variation of the horizontal (H) magnetic field intensity deduced from Magnetic Data Acquisition System (MAGDAS) records over Africa during an unusual strong and prolonged 2009 sudden stratospheric warming (SSW) event. A reduction in the SqH magnitude that enveloped the geomagnetic latitudes between 21.13°N (Fayum FYM) in Egypt and 39.51°S (Durban DRB) in South Africa was observed, while the stratospheric polar temperature was increasing and got strengthened when the stratospheric temperature reached its maximum. Another novel feature associated with the hemispheric reduction is the reversal in the north‐south asymmetry of the SqH, which is indicative of higher SqH magnitude in the Northern Hemisphere compared to the Southern Hemisphere during SSW peak phase. The reversal of the equatorial electrojet (EEJ) or the counter electrojet (CEJ) was observed after the polar stratospheric temperature reached its maximum. The effect of additional currents associated with CEJ was observed in the Southern Hemisphere at middle latitude. Similar changes were observed in the EEJ at the South America, Pacific Ocean, and Central Asia sectors. The effect of the SSW is largest in the South American sector and smallest in the Central Asian sector.
Characteristics of the equatorial plasma drifts as obtained by using Canadian Doppler ionosonde over southern tip of India
Authors: Sripathi S. , Singh Ram , Banola S. , Sreekumar Sreeba , Emperumal K. , Selvaraj C. 
Published: August 2016

AbstractWe present here characteristics of the Doppler drift measurements over Tirunelveli (8.73°N, 77.70°E; dip 0.5°N), an equatorial site over Southern India using Doppler interferometry technique of Canadian ionosonde. Three‐dimensional bulk motions of the scatterers as reflected from the ionosphere are derived by using Doppler interferometry technique at selected frequencies using spaced receivers arranged in magnetic E‐W and N‐S directions. After having compared with Lowell's digisonde drifts at Trivandrum, we studied the temporal and seasonal variabilities of quiet time drifts for the year 2012. The observations showed higher vertical drifts during post sunset in the equinox followed by winter and summer seasons. The comparison of Doppler vertical drifts with the drifts obtained from (a) virtual height and (b) Fejer drift model suggests that Doppler vertical drifts are relatively higher as compared to the drifts obtained from model and virtual height methods. Further, it is seen that vertical drifts exhibited equinoctial asymmetry in prereversal enhancement quite similar to such asymmetry observed in the spread F in the ionograms and GPS L band scintillations. The zonal drifts, on the other hand, showed westward during daytime with mean drifts of ~150–200 m/s and correlated well with equatorial electrojet strength indicating the role of E region dynamo during daytime, while they are eastward during nighttime with mean drifts of ~100 m/s resembling F region dynamo process. Also, zonal drifts showed large westward prior to the spread F onset during autumn equinox than vernal equinox, suggesting strong zonal shears which might cause equinoctial asymmetry in spread F.
Effect of static pressure on absolute paleointensity recording with implications for meteorites
Authors: Volk Michael W. R. , Gilder Stuart A. 
Published: August 2016

AbstractWe investigated the influence of hydrostatic and nonhydrostatic stress on the recording process of magnetic field intensity with particular relevance for meteorites that experienced pressures lower than 5 GPa corresponding to the lowest shock stage classification (S1) in meteorites. Thermal remanent magnetizations were imparted on natural obsidian samples containing pseudo‐single domain titanomagnetite, analogous to some achondritic meteorites. Thellier‐type paleointensity experiments were carried out at ambient conditions after pressure cycling to 0.6, 1.2, and 1.8 GPa. Each experiment used 10 samples to assess reproducibility, which is better than ±5%. The recorded paleointensity decreased 10%/GPa under hydrostatic stress and 20%/GPa under nonhydrostatic stress, leading to the fundamental conclusion that paleointensity results from meteorites may be appreciably underestimated. Pressure cycling shifts the blocking and unblocking spectra, thereby producing more linear slopes on an Arai diagram with increasing strain. We explain why, for samples with a single magnetization component that does not alter, a two‐step paleointensity protocol sufficiently resolves the true paleointensity. Moreover, we propose that pressure cycling of pseudo‐single domain bearing samples will remove the inherent curvature of the Arai slope, thereby allowing one to obtain a more accurate estimate of the true paleointensity. This likely also holds true for samples possessing multidomain grains. Conversely, linear trends on Arai plots in meteorites might have their origin in a pressure effect that does not necessarily reflect the ubiquitous presence of single domain particles.
The plumbing of the global biological pump: Efficiency control through leaks, pathways, and time scales
Authors: Pasquier Benoît , Holzer Mark 
Published: August 2016

AbstractWe systematically quantify the pathways and time scales that set the efficiency,
, of the global biological pump by applying Green‐function‐based diagnostics to a data‐assimilated phosphorus cycle embedded in a jointly assimilated ocean circulation. We consider “bio pipes” that consist of phosphorus paths that connect specified regions of last biological utilization with regions where regenerated phosphate first reemerges into the euphotic zone. The bio pipes that contribute most to Ebio connect the Eastern Equatorial Pacific (EEqP) and Equatorial Atlantic to the Southern Ocean ((21 ± 3)% of
), as well as the Southern Ocean to itself ((15 ± 3)% of
). The bio pipes with the largest phosphorus flow rates connect the EEqP to itself and the subantarctic Southern Ocean to itself. The global mean sequestration time of the biological pump is 130 ± 70 years, while the sequestration time of the bio pipe from anywhere to the Antarctic region of the Southern Ocean is 430 ± 30 years. The distribution of phosphorus flowing within a given bio pipe is quantified by its transit‐time partitioned path density. For the largest bio pipes, ∼1/7 of their phosphorus is carried by thermocline paths with transit times less than ∼300–400 years, while ∼4/7 of their phosphorus is carried by abyssal paths with transit times exceeding ∼700 years. The path density reveals that Antarctic Intermediate Water carries about a third of the regenerated phosphate last utilized in the EEqP that is destined for the Southern Ocean euphotic zone. The Southern Ocean is where (62 ± 2)% of the regenerated inventory and (69 ± 1)% of the preformed inventory first reemerge into the euphotic zone.
Cometary origin of atmospheric methane variations on Mars unlikely
Authors: Roos‐Serote M. , Atreya S. K. , Webster C. R. , Mahaffy P. R. 
Published: August 2016

AbstractThe detection of methane in the atmosphere of Mars was first reported in 2004. Since then a number of independent observations of methane have been reported, all showing temporal variability. Up until recently, the origin of methane was attributed to sources either indigenous to Mars or exogenous, where methane is a UV degradation byproduct of organics falling on to the surface. Most recently, a new hypothesis has been proposed that argues that the appearance and variation of methane are correlated with specific meteor events at Mars. Indeed, extraplanetary material can be brought to a planet when it passes through a meteoroid stream left behind by cometary bodies orbiting the Sun. This occurs repeatedly at specific times in a planet's year as streams tend to be fairly stable in space. In this paper, we revisit this latest hypothesis by carrying out a complete analysis of all available data on Mars atmospheric methane, including the very recent data not previously published, together with all published predicted meteor events for Mars. Whether we consider the collection of individual data points and predicted meteor events, whether we apply statistical analysis, or whether we consider different time spans between high methane measurements and the occurrence of meteor events, we find no compelling evidence for any correlation between atmospheric methane and predicted meteor events.
Perchlorate formation on Mars through surface radiolysis‐initiated atmospheric chemistry: A potential mechanism
Authors: Wilson Eric H. , Atreya Sushil K. , Kaiser Ralf I. , Mahaffy Paul R. 
Published: August 2016

AbstractRecent observations of the Martian surface by the Phoenix lander and the Sample Analysis at Mars indicate the presence of perchlorate (ClO4–). The abundance and isotopic composition of these perchlorates suggest that the mechanisms responsible for their formation in the Martian environment may be unique in our solar system. With this in mind, we propose a potential mechanism for the production of Martian perchlorate: the radiolysis of the Martian surface by galactic cosmic rays, followed by the sublimation of chlorine oxides into the atmosphere and their subsequent synthesis to form perchloric acid (HClO4) in the atmosphere, and the surface deposition and subsequent mineralization of HClO4 in the regolith to form surface perchlorates. To evaluate the viability of this mechanism, we employ a one‐dimensional chemical model, examining chlorine chemistry in the context of Martian atmospheric chemistry. Considering the chlorine oxide, OClO, we find that an OClO flux as low as 3.2 × 107 molecules cm–2 s–1 sublimated into the atmosphere from the surface could produce sufficient HClO4 to explain the perchlorate concentration on Mars, assuming an accumulation depth of 30 cm and integrated over the Amazonian period. Radiolysis provides an efficient pathway for the oxidation of chlorine, bypassing the efficient Cl/HCl recycling mechanism that characterizes HClO4 formation mechanisms proposed for the Earth but not Mars.
Fracture size and transmissivity correlations: Implications for transport simulations in sparse three‐dimensional discrete fracture networks following a truncated power law distribution of fracture size
Authors: Hyman J. D. , Aldrich G. , Viswanathan H. , Makedonska N. , Karra S. 
Published: August 2016

AbstractWe characterize how different fracture size‐transmissivity relationships influence flow and transport simulations through sparse three‐dimensional discrete fracture networks. Although it is generally accepted that there is a positive correlation between a fracture's size and its transmissivity/aperture, the functional form of that relationship remains a matter of debate. Relationships that assume perfect correlation, semicorrelation, and noncorrelation between the two have been proposed. To study the impact that adopting one of these relationships has on transport properties, we generate multiple sparse fracture networks composed of circular fractures whose radii follow a truncated power law distribution. The distribution of transmissivities are selected so that the mean transmissivity of the fracture networks are the same and the distributions of aperture and transmissivity in models that include a stochastic term are also the same. We observe that adopting a correlation between a fracture size and its transmissivity leads to earlier breakthrough times and higher effective permeability when compared to networks where no correlation is used. While fracture network geometry plays the principal role in determining where transport occurs within the network, the relationship between size and transmissivity controls the flow speed. These observations indicate DFN modelers should be aware that breakthrough times and effective permeabilities can be strongly influenced by such a relationship in addition to fracture and network statistics.
Using Genetically Encodable Self‐Assembling GdIII Spin Labels To Make In‐Cell Nanometric Distance Measurements
Authors: Mascali Florencia C. , Ching H. Y. Vincent , Rasia Rodolfo M. , Un Sun , Tabares Leandro C. 
Published: August 2016

AbstractDouble electron–electron resonance (DEER) can be used to study the structure of a protein in its native cellular environment. Until now, this has required isolation, in vitro labeling, and reintroduction of the protein back into the cells. We describe a completely biosynthetic approach that avoids these steps. It exploits genetically encodable lanthanide‐binding tags (LBT) to form self‐assembling GdIII metal‐based spin labels and enables direct in‐cell measurements. This approach is demonstrated using a pair of LBTs encoded one at each end of a 3‐helix bundle expressed in E. coli grown on GdIII‐supplemented medium. DEER measurements directly on these cells produced readily detectable time traces from which the distance between the GdIII labels could be determined. This work is the first to use biosynthetically produced self‐assembling metal‐containing spin labels for non‐disruptive in‐cell structural measurements.
Insight into the Inhibition of Drug‐Resistant Mutants of the Receptor Tyrosine Kinase EGFR
Authors: Engel Julian , Becker Christian , Lategahn Jonas , Keul Marina , Ketzer Julia , Mühlenberg Thomas , Kollipara Laxmikanth , Schultz‐Fademrecht Carsten , Zahedi René P. , Bauer Sebastian , Rauh Daniel 
Published: August 2016

AbstractTargeting acquired drug resistance represents the major challenge in the treatment of EGFR‐driven non‐small‐cell lung cancer (NSCLC). Herein, we describe the structure‐based design, synthesis, and biological evaluation of a novel class of covalent EGFR inhibitors that exhibit excellent inhibition of EGFR‐mutant drug‐resistant cells. Protein X‐ray crystallography combined with detailed kinetic studies led to a deeper understanding of the mode of inhibition of EGFR‐T790M and provided insight into the key principles for effective inhibition of the recently discovered tertiary mutation at EGFR‐C797S.
Functionalization of Hydrogenated Graphene: Transition‐Metal‐Catalyzed Cross‐Coupling Reactions of Allylic C−H Bonds
Authors: Chua Chun Kiang , Sofer Zdeněk , Pumera Martin 
Published: August 2016

AbstractThe chemical functionalization of hydrogenated graphene can modify its physical properties and lead to better processability. Herein, we describe the chemical functionalization of hydrogenated graphene through a dehydrogenative cross‐coupling reaction between an allylic C−H bond and the α‐C−H bond of tetrahydrothiophen‐3‐one using Cu(OTf)2 as the catalyst and DDQ as the oxidant. The chemical functionalization was confirmed by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy and visualized by scanning electron microscopy. The functionalized hydrogenated graphene material demonstrated improved dispersion stability in water, bringing new quality to the elusive hydrogenated graphene (graphane) materials. Hydrogenated graphene provides broad possibilities for chemical modifications owing to its reactivity.
The Oxygen‐Rich Beryllium Oxides BeO4 and BeO6
Authors: Zhang Qingnan , Jerabek Paul , Chen Mohua , Zhou Mingfei , Frenking Gernot 
Published: August 2016

AbstractTwo novel isomers of BeO4 with the structures OBeOOO and OBe(O3) in the electronic triplet state have been prepared as well as the known disuperoxide complex Be(O2)2 in solid noble‐gas matrices. We also report the synthesis of the oxygen‐rich bis(ozonide) complex Be(O3)2 in the triplet state which has a D2d equilibrium geometry. The molecular structures were identified by infrared absorption spectroscopy with isotopic substitutions as well as quantum chemical calculations.