bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scaling the Ion Inertial Length and Its Implications for Modeling Reconnection in Global Simulations
Authors: Tóth Gábor , Chen Yuxi , Gombosi Tamas I. , Cassak Paul , Markidis Stefano , Peng Ivy Bo 
Published: September 2017

AbstractWe investigate the use of artificially increased ion and electron kinetic scales in global plasma simulations. We argue that as long as the global and ion inertial scales remain well separated, (1) the overall global solution is not strongly sensitive to the value of the ion inertial scale, while (2) the ion inertial scale dynamics will also be similar to the original system, but it occurs at a larger spatial scale, and (3) structures at intermediate scales, such as magnetic islands, grow in a self‐similar manner. To investigate the validity and limitations of our scaling hypotheses, we carry out many simulations of a two‐dimensional magnetosphere with the magnetohydrodynamics with embedded particle‐in‐cell (MHD‐EPIC) model. The PIC model covers the dayside reconnection site. The simulation results confirm that the hypotheses are true as long as the increased ion inertial length remains less than about 5% of the magnetopause standoff distance. Since the theoretical arguments are general, we expect these results to carry over to three dimensions. The computational cost is reduced by the third and fourth powers of the scaling factor in two‐ and three‐dimensional simulations, respectively, which can be many orders of magnitude. The present results suggest that global simulations that resolve kinetic scales for reconnection are feasible. This is a crucial step for applications to the magnetospheres of Earth, Saturn, and Jupiter and to the solar corona.
Imprints of Quasi‐Adiabatic Ion Dynamics on the Current Sheet Structures Observed in the Martian Magnetotail by MAVEN
Authors: Grigorenko E. E. , Shuvalov S. D. , Malova H. V. , Dubinin E. , Popov V. Yu. , Zelenyi L. M. , Espley J. , McFadden J. P. 
Published: September 2017

AbstractNumerous studies of the current sheets (CS) in the Earth's magnetotail showed that quasi‐adiabatic ion dynamics plays an important role in the formation of complicated multilayered current structures. In order to check whether the similar mechanisms operate in the Martian magnetotail, we analyzed 80 CS crossings using MAVEN measurements on the nightside of Mars at radial distances ~1.0–2.8RM. We found that CS structures experience similar dependence on the value of the normal component of the magnetic field at the neutral plane (BN) and on the ratio of the ion drift velocity outside the CS to the thermal velocity (VT/VD) as it was observed for the CSs in the Earth's magnetotail. For the small values of BN, a thin and intense CS embedded in a thicker one is observed. The half‐thickness L of this layer is ~30–100 km ≤ ρH+ (ρH+ is a gyroradius of thermal protons outside the CS). With the increase of BN, the L also increases up to several hundred kilometers (~ρO+, ρO2+), the current density decreases, and the embedding feature disappears. Our statistical analysis showed a good agreement between L values observed by MAVEN and the CS scaling obtained from the quasi‐adiabatic model, if the plasma characteristics in Martian CSs are used as input parameters. Thus, we may conclude that in spite of the differences in magnetic topology, ion composition, and plasma thermal characteristics observed in the Earth's and Martian magnetotails, similar quasi‐adiabatic mechanisms contribute to the formation of the CSs in the magnetotails of both planets.
MMS Observations of Reconnection at Dayside Magnetopause Crossings During Transitions of the Solar Wind to Sub‐Alfvénic Flow
Authors: Farrugia C. J. , Lugaz N. , Alm L. , Vasquez B. , Argall M. R. , Kucharek H. , Matsui H. , Torbert R. B. , Lavraud B. , Le Contel O. , Cohen I. J. , Burch J. L. , Russell C. T. , Strangeway R. J. , Shuster J. , Dorelli J. C. , Eastwood J. P. , Ergun R. E. , Fuselier S. A. , Gershman D. J. , Giles B. L. , Khotyaintsev Y. V. , Lindqvist P. A. , Marklund G. T. , Paulson K. W. , Petrinec S. M. , Phan T. D. , Pollock C. J. 
Published: September 2017

AbstractWe present MMS observations during two dayside magnetopause crossings under hitherto unexamined conditions: (i) when the bow shock is weakening and the solar wind transitioning to sub‐Alfvénic flow and (ii) when it is reforming. Interplanetary conditions consist of a magnetic cloud with (i) a strong B (∼20 nT) pointing south and (ii) a density profile with episodic decreases to values of ∼0.3 cm−3 followed by moderate recovery. During the crossings the magnetosheath magnetic field is stronger than the magnetosphere field by a factor of ∼2.2. As a result, during the outbound crossing through the ion diffusion region, MMS observed an inversion of the relative positions of the X and stagnation (S) lines from that typically the case: the S line was closer to the magnetosheath side. The S line appears in the form of a slow expansion fan near which most of the energy dissipation is taking place. While in the magnetosphere between the crossings, MMS observed strong field and flow perturbations, which we argue to be due to kinetic Alfvén waves. During the reconnection interval, whistler mode waves generated by an electron temperature anisotropy (Te⊥>Te∥) were observed. Another aim of the paper is to distinguish bow shock‐induced field and flow perturbations from reconnection‐related signatures. The high‐resolution MMS data together with 2‐D hybrid simulations of bow shock dynamics helped us to distinguish between the two sources. We show examples of bow shock‐related effects (such as heating) and reconnection effects such as accelerated flows satisfying the Walén relation.
Fingerprints of Sea Level Rise on Changing Tides in the Chesapeake and Delaware Bays
Authors: Ross Andrew C. , Najjar Raymond G. , Li Ming , Lee Serena Blyth , Zhang Fan , Liu Wei 
Published: September 2017

AbstractSecular tidal trends are present in many tide gauge records, but their causes are often unclear. This study examines trends in tides over the last century in the Chesapeake and Delaware Bays. Statistical models show negative M2 amplitude trends at the mouths of both bays, while some upstream locations have insignificant or positive trends. To determine whether sea level rise is responsible for these trends, we include a term for mean sea level in the statistical models and compare the results with predictions from numerical and analytical models. The observed and predicted sensitivities of M2 amplitude and phase to mean sea level are similar, although the numerical model amplitude is less sensitive to sea level. The sensitivity occurs as a result of strengthening and shifting of the amphidromic system in the Chesapeake Bay and decreasing frictional effects and increasing convergence in the Delaware Bay. After accounting for the effect of sea level, significant negative background M2 and S2 amplitude trends are present; these trends may be related to other factors such as dredging, tide gauge errors, or river discharge. Projected changes in tidal amplitudes due to sea level rise over the 21st century are substantial in some areas, but depend significantly on modeling assumptions.
Effects of the Relaxation of Upwelling‐Favorable Winds on the Diurnal and Semidiurnal Water Temperature Fluctuations in the Santa Barbara Channel, California
Authors: Aristizábal María F. , Fewings Melanie R. , Washburn Libe 
Published: September 2017

AbstractIn the Santa Barbara Channel, California, and around the Northern Channel Islands, water temperature fluctuations in the diurnal and semidiurnal frequency bands are intermittent, with amplitudes that vary on time scales of days to weeks. The cause of this intermittency is not well understood. We studied the effects of the barotropic tide, vertical stratification, propagation of coastal‐trapped waves, regional wind relaxations, and diurnal‐band winds on the intermittency of the temperature fluctuations during 1992–2015. We used temperature data from 43 moorings in 10–200 m water depth and wind data from two buoys and one land station. Subtidal‐frequency changes in vertical stratification explain 20–40% of the intermittency in diurnal and semidiurnal temperature fluctuations at time scales of days to weeks. Along the mainland north of Point Conception and at the Northern Channel Islands, the relaxation of upwelling‐favorable winds substantially increases vertical stratification, accounting for up to 55% of the subtidal‐frequency variability in stratification. As a result of the enhanced stratification, wind relaxations enhance the diurnal and semidiurnal temperature fluctuations at those sites, even though the diurnal‐band wind forcing decreases during wind relaxation. A linear model where the background stratification is advected vertically explains a substantial fraction of the temperature fluctuations at most sites. The increase of vertical stratification and subsequent increase in diurnal and semidiurnal temperature fluctuations during wind relaxation is a mechanism that can supply nutrients to the euphotic zone and kelp forests in the Channel in summer when upwelling is weak.
Hydrological Drought in the Anthropocene: Impacts of Local Water Extraction and Reservoir Regulation in the U.S.
Authors: Wan Wenhua , Zhao Jianshi , Li Hong‐Yi , Mishra Ashok , Ruby Leung L. , Hejazi Mohamad , Wang Wei , Lu Hui , Deng Zhiqun , Demissisie Yonas , Wang Hao 
Published: September 2017

Key Points

Modeling analysis of future hydrologic droughts over U.S. is provided
Relative contributions from climate change and water managements are quantified
Future hydrologic drought will be alleviated by reservoirs but intensified by local water extraction
Observed Covariations of Aerosol Optical Depth and Cloud Cover in Extratropical Cyclones
Authors: Naud Catherine M. , Posselt Derek J. , van den Heever Susan C. 
Published: September 2017

AbstractUsing NASA Moderate Resolution Imaging Spectroradiometer aerosol optical depth and total cloud cover retrievals, CloudSat‐CALIPSO cloud profiles, and a database of extratropical cyclones and frontal boundary locations, relationships between changes in aerosol optical depth and cloud cover in extratropical cyclones occurring over Northern Hemisphere oceans are examined. A reanalysis data set is used to constrain column water vapor and ascent strength in the cyclones in an attempt to distinguish their impact on cloud cover from the effect of changes in aerosol loading. The results suggest that high aerosol optical depth cyclones exhibit larger middle‐ and high‐level cloud cover than their low aerosol optical depth counterparts. However, the opposite behavior is found for low‐level cloud cover. These relationships are found to depend on the large‐scale environment, in particular the column water vapor and vertical motion. Despite the inability of the observations to provide a causal physical link between aerosol load and cloud cover, these results can help to constrain and evaluate model simulations.
New Insights Into Lithology Distribution Across the Moon
Authors: Wang Xianmin , Zhao Siyuan 
Published: September 2017

AbstractLithology distribution across the Moon is pivotal for understanding lunar evolution. However, so far, the distribution of lunar rock suites is still uncertain; as a result, many related core issues on lunar evolution have long been in dispute. This work reports on a new lithology distribution map across the Moon and discusses some critical issues of the lunar evolutionary process. The oxide abundances derived from Chang'E‐1 Interference Imaging Spectrometer imagery and the Th contents inferred by Lunar Prospector Gamma Ray and Neutron Spectrometer data are employed to generate the lithological map by using the decision tree C5.0 algorithm. The following conclusions are inferred from this new map. (1) Magnesian suite is widely distributed across the Feldspathic Highlands Terrane and in the periphery of the South Pole‐Aitken Terrane. Thus, the viewpoints have been validated that the early magnesian magmatism may be a global phenomenon and that KREEP basalt is not necessary for the petrogenesis of Mg‐rich rocks. Moreover, the regions of Dryden, Chaffee S, Theophilus, and Moscoviense are confirmed as magnesian suite exposures. (2) The observation that the Feldspathic Highlands Terrane has a higher Mg/(Mg + Fe) value than the maria is related to the flood of the Mg suite across the Feldspathic Highlands Terrane. (3) The specific exposed locations of the alkali suite across the Moon have long been unsolved, and this work discloses that the alkali suite prevails in the outskirts of the Procellarum KREEP Terrane, the center of the South Pole‐Aitken Terrane, and some isolated locales. (4) Focusing on distinguishing mare basalts from other mafic rocks, seven geochemical indices are proposed to determine the potential exposures of mare basalts across the Moon. (5) In Mare Insularum, a series of KREEP volcanisms may have occurred and lasted longer than the mare volcanism.
Influence of Sediment Cohesion on Deltaic Morphodynamics and Stratigraphy Over Basin‐Filling Time Scales
Authors: Li Qi , Matthew Benson W. , Harlan Margaret , Robichaux Patrick , Sha Xiaoyu , Xu Kehui , Straub Kyle M. 
Published: September 2017

AbstractResults from physical and numerical experiments suggest that sediment cohesion influences deltaic morphodynamics by promoting the development and maintenance of channels. As a result, cohesion is thought to increase the magnitude and time scales of internally generated (autogenic) processes and the dimensions of their stratigraphic products. We test these hypotheses by examining the surface processes and stratigraphic products from a suite of physical experiments where the influence of cohesion is isolated over temporal and spatial scales important for basin filling. Given the stochastic nature of autogenic sediment transport processes, we develop and employ a range of statistical tools and metrics. We observe that (1) an increase in sediment cohesion decreases lateral channel mobility and thus increases the time necessary to regrade deltaic surfaces; (2) enhanced channelization, due to sediment cohesion, increases the time necessary for the deposits of autogenic processes to average together and produce stratigraphic products with shapes set by the generation of regional accommodation; (3) cohesion promotes the transport of suspended sediment to terrestrial overbank and marine environments, which decreases the volume of channel, relative to overbank and marine deposits in the stratigraphic record. This increase in overbank and marine deposition changes the spatial distribution of sand in stratigraphy, with higher cohesion linked to enhanced segregation of fine particles from coarse sand in the experimental deposits. Combined, these results illustrate how the cohesion of sediment is fundamental in setting autogenic spatial and temporal scales and needs to be considered when inverting stratigraphic architecture for paleo‐environmental history.
Use of a radial projection to reduce the statistical uncertainty of spot lateral profiles generated by Monte Carlo simulation
Authors: Ding Xiaoning , Liu Wei , Shen Jiajian , Anand Aman , Stoker Joshua B. , Hu Yanle , Bues Martin 
Published: September 2017

AbstractMonte Carlo (MC) simulation has been used to generate commissioning data for the beam modeling of treatment planning system (TPS). We have developed a method called radial projection (RP) for postprocessing of MC‐simulation‐generated data. We used the RP method to reduce the statistical uncertainty of the lateral profile of proton pencil beams with axial symmetry. The RP method takes advantage of the axial symmetry of dose distribution to use the mean value of multiple independent scores as the representative score. Using the mean as the representative value rather than any individual score results in substantial reduction in statistical uncertainty. Herein, we present the concept and step‐by‐step implementation of the RP method, as well as show the advantage of the RP method over conventional measurement methods for generating lateral profile. Lateral profiles generated by both methods were compared to demonstrate the uncertainty reduction qualitatively, and standard error comparison was performed to demonstrate the reduction quantitatively. The comparisons showed that statistical uncertainty was reduced substantially by the RP method. Using the RP method to postprocess MC data, the corresponding MC simulation time was reduced by a factor of 10 without quality reduction in the generated result from the MC data. We concluded that the RP method is an effective technique to increase MC simulation efficiency for generating lateral profiles for axially symmetric pencil beams.
Highly Conductive and Transparent Large‐Area Bilayer Graphene Realized by MoCl5 Intercalation
Authors: Kinoshita Hiroki , Jeon Il , Maruyama Mina , Kawahara Kenji , Terao Yuri , Ding Dong , Matsumoto Rika , Matsuo Yutaka , Okada Susumu , Ago Hiroki 
Published: September 2017

AbstractBilayer graphene (BLG) comprises a 2D nanospace sandwiched by two parallel graphene sheets that can be used to intercalate molecules or ions for attaining novel functionalities. However, intercalation is mostly demonstrated with small, exfoliated graphene flakes. This study demonstrates intercalation of molybdenum chloride (MoCl5) into a large‐area, uniform BLG sheet, which is grown by chemical vapor deposition (CVD). This study reveals that the degree of MoCl5 intercalation strongly depends on the stacking order of the graphene; twist‐stacked graphene shows a much higher degree of intercalation than AB‐stacked. Density functional theory calculations suggest that weak interlayer coupling in the twist‐stacked graphene contributes to the effective intercalation. By selectively synthesizing twist‐rich BLG films through control of the CVD conditions, low sheet resistance (83 Ω ▫−1) is realized after MoCl5 intercalation, while maintaining high optical transmittance (≈95%). The low sheet resistance state is relatively stable in air for more than three months. Furthermore, the intercalated BLG film is applied to organic solar cells, realizing a high power conversion efficiency.
Semiconducting Polymer Nanoparticles for Centimeters‐Deep Photoacoustic Imaging in the Second Near‐Infrared Window
Authors: Wu Jiayingzi , You Liyan , Lan Lu , Lee Hyeon Jeong , Chaudhry Saadia T. , Li Rui , Cheng Ji‐Xin , Mei Jianguo 
Published: September 2017

AbstractThienoisoindigo‐based semiconducting polymer with a strong near‐infrared absorbance is synthesized and its water‐dispersed nanoparticles (TSPNs) are investigated as a contrast agent for photoacoustic (PA) imaging in the second near‐infrared (NIR‐II) window (1000–1350 nm). The TSPNs generate a strong PA signal in the NIR‐II optical window, where background signals from endogenous contrast agents, including blood and lipid, are at the local minima. By embedding a TSPN‐containing tube in chicken‐breast tissue, an imaging depth of more than 5 cm at 1064 nm excitation is achieved with a contrast‐agent concentration as low as 40 µg mL−1. The TSPNs under the skin or in the tumor are clearly visualized at 1100 and 1300 nm, with negligible interference from the tissue background. TSPN as a PA contrast in the NIR‐II window opens new opportunities for biomedical imaging of deep tissues with improved contrast.
Hybrid Plasmonic Modes in Multilayer Trench Grating Structures
Authors: Liu Xiaoyi , Gao Jinsong , Yang Haigui , Wang Xiaoyi , Tian Sicong , Guo Chengli 
Published: September 2017

AbstractFor common plasmonic structures, it is difficult to considerate both the abilities of confining light and reducing loss. Here, two plasmonic multilayer structures comprised of five alternate Al and Si layers are demonstrated. First, the multilayer gratings with near‐infrared dual narrowband peaks are given in the spectrum excited by Fabry–Perot resonance. Through investigating the modes of electric field distributions, the frequency‐sensitivity, and linear designable characteristic of its working bands are clarified. Second, the multilayer trench gratings containing both stripes and trenches, which can induce the cavity effect additionally, are demonstrated. When the incidence is oblique, some new modes can be observed, leading to the C‐S hybrid plasmonic coupling modes. Besides, by changing the length of designed waveguide, the Fabry–Perot resonance modes can successively merge with the cavity effect modes, generating the hybrid modes regularly. As a contrast, their quality factors to evaluate the losses and qualities of designed two structures are calculated, and the results imply that the multilayer trench gratings reduce the loss effectively without decreasing energy localization. Detailed process and significance of calculations are discussed carefully.
Enzymatic Synthesis of Bufadienolide O‐Glycosides as Potent Antitumor Agents Using a Microbial Glycosyltransferase
Authors: Li Kai , Feng Jin , Kuang Yi , Song Wei , Zhang Meng , Ji Shuai , Qiao Xue , Ye Min 
Published: September 2017

AbstractBufadienolides are a class of natural cardiotonic steroids and are well known for their antitumor activities. Their clinical use has been hindered by poor water solubility. Enzymatic glycosylation is a favorable approach to improve the solubility of natural products. In this work, we describe the highly efficient one‐step synthesis of bufadienolide O‐glucosides and O‐galactosides using a microbial glycosyltransferase YjiC1, with conversion rates from 63% to 99%. Altogether 24 glycosides including 17 new compounds were obtained from 14 substrates, and their structures were identified by extensive NMR and high‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS) analyses. These products belong to five types: glycosylation at 3β‐OH, 7β‐OH, 3β,7β‐di‐OH, 11α‐OH, and 12β‐OH. The C‐7β or C‐11α O‐glycosides of bufadienolide are reported for the first time. Moreover, the 3‐O‐glycosides exhibited significant cytotoxic activities against A549 and MCF7 human cancer cell lines, and showed potent inhibitory activities against Na+/K+‐ATPase with IC50 values in the range 0.053–0.76 μM. In particular, bufalin 3‐O‐β‐d‐glucoside showed enhanced water solubility (25‐fold increase from bufalin) and potent antitumor activities (30% inhibition rate, 1.4 mg kg−1, i.p.) on A549 human lung cancer xenograft Balb/c nude mice model, and could be a promising drug candidate.magnified image
Catalyst‐ and Oxidant‐Free Desulfonative C−P Couplings for the Synthesis of Phosphine Oxides and Phosphonates
Authors: Guo Hong‐Mei , Zhou Quan‐Quan , Jiang Xuan , Shi De‐Qing , Xiao Wen‐Jing 
Published: September 2017

AbstractAn efficient and practical approach towards phosphine oxides and phosphonates has been successfully developed through the desulfonative coupling of various sulfones with secondary phosphine oxides and phosphites. This protocol features simple experimental procedures under mild conditions (i. e., catalyst‐ and oxidant‐free, room temperature and open to air). By doing so, a variety of alkynyl, alkenyl and allyl phosphine oxides or phosphonates can be produced in generally good reaction efficiency and selectivity (31 examples, up to 98% yield).magnified image