bluuebunny/crossref_metadata_2025_split huggingface dataset:
A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean
Authors: Jickells T. D. , Buitenhuis E. , Altieri K. , Baker A. R. , Capone D. , Duce R. A. , Dentener F. , Fennel K. , Kanakidou M. , LaRoche J. , Lee K. , Liss P. , Middelburg J. J. , Moore J. K. , Okin G. , Oschlies A. , Sarin M. , Seitzinger S. , Sharples J. , Singh A. , Suntharalingam P. , Uematsu M. , Zamora L. M. 
Published: January 2017

AbstractWe report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate that about 75% of this fluvial nitrogen escapes from the shelf to the open ocean. Biological dinitrogen fixation is the main external source of nitrogen to the open ocean, i.e., beyond the continental shelf. Atmospheric deposition is the primary mechanism by which land‐based nitrogen inputs, and hence human perturbations of the nitrogen cycle, reach the open ocean. We estimate that anthropogenic inputs are currently leading to an increase in overall ocean carbon sequestration of ~0.4% (equivalent to an uptake of 0.15 Pg C yr−1 and less than the Duce et al. (2008) estimate). The resulting reduction in climate change forcing from this ocean CO2 uptake is offset to a small extent by an increase in ocean N2O emissions. We identify four important feedbacks in the ocean atmosphere nitrogen system that need to be better quantified to improve our understanding of the perturbation of ocean biogeochemistry by atmospheric nitrogen inputs. These feedbacks are recycling of (1) ammonia and (2) organic nitrogen from the ocean to the atmosphere and back, (3) the suppression of nitrogen fixation by increased nitrogen concentrations in surface waters from atmospheric deposition, and (4) increased loss of nitrogen from the ocean by denitrification due to increased productivity stimulated by atmospheric inputs.
Accelerated flows at Jupiter's magnetopause: Evidence for magnetic reconnection along the dawn flank
Authors: Ebert R. W. , Allegrini F. , Bagenal F. , Bolton S. J. , Connerney J. E. P. , Clark G. , DiBraccio G. A. , Gershman D. J. , Kurth W. S. , Levin S. , Louarn P. , Mauk B. H. , McComas D. J. , Reno M. , Szalay J. R. , Thomsen M. F. , Valek P. , Weidner S. , Wilson R. J. 
Published: January 2017

AbstractWe report on plasma and magnetic field observations from Juno's Jovian Auroral Distributions Experiment and Magnetic Field Investigation at 18 magnetopause crossings when the spacecraft was located at ~6 h magnetic local time and 73–114 Jovian radii from Jupiter. Several crossings showed evidence of plasma energization, accelerated ion flows, and large magnetic shear angles, each representing a signature of magnetic reconnection. These signatures were observed for times when the magnetosphere was in both compressed and expanded states. We compared the flow change magnitudes to a simplified Walén relation and found ~60% of the events to be 110% or less of the predicted values. Close examination of two magnetopause encounters revealed characteristics of a rotational discontinuity and an open magnetopause. These observations provide compelling evidence that magnetic reconnection can occur at Jupiter's dawn magnetopause and should be incorporated into theories of solar wind coupling and outer magnetosphere dynamics at Jupiter.
Seasonal variations of meteoric potassium layer over Beijing (40.41°N, 116.01°E)
Authors: Wang Zelong , Yang Guotao , Wang Jihong , Yue Chuan , Yang Yong , Jiao Jing , Du Lifang , Cheng Xuewu , Chi Wang 
Published: January 2017

AbstractA dual‐wavelength resonance fluorescence lidar facility, operating at 770 nm and 589 nm, was set up in the midlatitude of East Asia, Beijing (40.41°N, 116.01°E), to detect the upper atmospheric potassium and sodium layers simultaneously. This fluorescence lidar system has been operational for 220 nights, clocking 1250 h in total from November 2010 to October 2011 and May 2013 to April 2014. The observations reveal that the potassium layer shows considerable semiannual seasonal variations. Specifically, the column and peak densities vary semiannually with maxima in winter and summer. The centroid height displays semiannual variation, reaching maxima in spring and autumn. The RMS width has a slight semiannual seasonality with maxima in July and December. The seasonal behavior of the potassium layer in Beijing is similar to that in other potassium lidar sties. However, the unexpected difference is that the column and peak densities of the potassium layer are extremely large in winter, compared to the maximum values in summer.
Far ultraviolet instrument technology
Authors: Paxton Larry J. , Schaefer Robert K. , Zhang Yongliang , Kil Hyosub 
Published: January 2017

AbstractThe far ultraviolet (FUV) spectral range (from about 115 nm to 180 nm) is one of the most useful spectral regions for characterizing the upper atmosphere (thermosphere and ionosphere). The principal advantages are that there are FUV signatures of the major constituents of the upper atmosphere as well as the signatures of the high‐latitude energy inputs. Because of the absorption by thermospheric O2, the FUV signatures are seen against a “black” background, i.e., one that is not affected by ground albedo or clouds and, as a consequence, can make useful observations of the aurora during the day or when the Moon is above the horizon. In this paper we discuss the uses of FUV remote sensing, summarize the various techniques, and discuss the technological challenges. Our focus is on a particular type of FUV instrument, the scanning imaging spectrograph or SIS: an instrument exemplified by the Defense Meteorological Satellite Program Special Sensor Ultraviolet Imager and Thermosphere Ionosphere Mesosphere Energetics and Dynamics Global Ultraviolet Imager. The SIS combines spatial imaging of the disk with limb profiles as well as spectral information at each point in the scan.
Three‐dimensional simulation of high‐frequency nonlinear internal wave dynamics in Cayuga Lake
Authors: Dorostkar Abbas , Boegman Leon , Pollard Andrew 
Published: January 2017

AbstractThree‐dimensional (3‐D) hydrostatic and nonhydrostatic versions of the MITgcm were applied to simulate the dynamics of the internal wave field (basin‐scale seiches, nonlinear surges, and high‐frequency nonlinear internal waves, NLIWs) in Cayuga Lake, NY. The simulations were performed using up to 226 million computational cells with several horizontal grid resolutions, varying from 450 × 450 m to 22 × 22 m. Vertical grid spacing was not varied and ranged from 0.5 to 2.95 m. The 22 × 22 m nonhydrostatic grid reproduced qualitatively the formation, propagation, and shoaling of observed NLIWs using >10 grid points along the wavelength and a grid lepticity λ of O(1). This ensured, respectively, that the waves were not aliased and physical dispersion predominated over numerical dispersion. Using a sensitivity analysis, we generalize that correctly simulating NLIWs in real domains, using second‐order discretization, requires grid resolutions that are an order of magnitude smaller than the wavelength and amplitude with λ ∼ 2; consistent with published work on idealized domains. Local gyre‐like circulation was simulated, near midbasin headlands, and transverse shoaling of NLIW packets on lateral boundaries was associated with topographic reflection and refraction, in agreement with published field observations from estuaries, which show NLIW propagation in long narrow quasi‐2‐D systems (e.g., Finger Lakes, lochs, fjords, estuaries, and straits) is fundamentally 3‐D. These results, therefore, help fill the gap in understanding and correctly modeling the multiscale 3‐D dynamics of NLIWs in complex natural systems.
Deep sediment resuspension and thick nepheloid layer generation by open‐ocean convection
Authors: Durrieu de Madron X. , Ramondenc S. , Berline L. , Houpert L. , Bosse A. , Martini S. , Guidi L. , Conan P. , Curtil C. , Delsaut N. , Kunesch S. , Ghiglione J. F. , Marsaleix P. , Pujo‐Pay M. , Séverin T. , Testor P. , Tamburini C. ,   the ANTARES collaboration
Published: January 2017

AbstractThe Gulf of Lions in the northwestern Mediterranean is one of the few sites around the world ocean exhibiting deep open‐ocean convection. Based on 6 year long (2009–2015) time series from a mooring in the convection region, shipborne measurements from repeated cruises, from 2012 to 2015, and glider measurements, we report evidence of bottom thick nepheloid layer formation, which is coincident with deep sediment resuspension induced by bottom‐reaching convection events. This bottom nepheloid layer, which presents a maximum thickness of more than 2000 m in the center of the convection region, probably results from the action of cyclonic eddies that are formed during the convection period and can persist within their core while they travel through the basin. The residence time of this bottom nepheloid layer appears to be less than a year. In situ measurements of suspended particle size further indicate that the bottom nepheloid layer is primarily composed of aggregates between 100 and 1000 µm in diameter, probably constituted of fine silts. Bottom‐reaching open ocean convection, as well as deep dense shelf water cascading that occurred concurrently some years, lead to recurring deep sediments resuspension episodes. They are key mechanisms that control the concentration and characteristics of the suspended particulate matter in the basin, and in turn affect the bathypelagic biological activity.
Examination of an improved quasi‐stochastic model for the collisional growth of drops
Authors: Lkhamjav Jambajamts , Lee Hyunho , Jeon Ye‐Lim , Baik Jong‐Jin 
Published: January 2017

AbstractThe evolution of cloud drop size distribution due to the collision‐coalescence process is generally described by a quasi‐stochastic model that solves the stochastic collection equation in a deterministic way. In this study, an improved quasi‐stochastic (IQS) model, which is derived by rigorously considering a finite model time step, is examined in the context of comparison with the normal quasi‐stochastic (NQS) model. The IQS model allows a large collector drop to collide with a small collected drop more than one time in a model time step even if the collision probability is small. The number distribution of collector drops then follows the Poisson distribution with respect to the number of collisions. Using a box model that takes turbulence‐induced collision enhancement into account, it is found that large drops in the IQS model tend to have larger sizes than those in the NQS model and that the IQS model accelerates large‐drop formation by a few minutes compared to the NQS model. The effects of the IQS model depend on the model time step and the shape of initial drop size distribution. The IQS model is incorporated into a detailed bin microphysics scheme that is coupled with the Weather Research and Forecasting model, and a single warm cloud is simulated under idealized environmental conditions. It is found that the onset of surface precipitation is accelerated in the IQS model.
First in situ observations of binary raindrop collisions
Authors: Testik F. Y. , Rahman M. K. 
Published: January 2017

AbstractIn this article, we present the first‐time observations of binary raindrop collisions in rainfall events. These observations constitute a critical step in concluding a long‐standing debate on the controlling physical process, binary raindrop collision versus spontaneous raindrop breakup, for the raindrop size distribution (DSD) evolution from cloud to ground level. Our raindrop collision observations were made possible by a new instrument called the High‐speed Optical Disdrometer (HOD) that we recently developed for precipitation microphysics investigations. Our approximately 1 year long field campaign that covered 33 rainfall events provided 11 observations of binary raindrop collisions and outcomes but no spontaneous breakup observation. The field‐observed collision rate (i.e., number of raindrop collisions within the measurement volume of the HOD per unit time) showed an increasing trend with increasing rain rate as expected from the theoretical collision rate predictions. Furthermore, the field‐observed collision rates were (i) comparable (for rain rates less than approximately 50 mm/h) and (ii) significantly larger (for larger rain rates) than the theoretically predicted rates that have been used in various numerical investigations that suggest the controlling role of raindrop collisions in DSD evolution. Our observations, yet to be supplemented with observations from comprehensive field campaigns at different geographic locations and rainfall events for a definitive conclusion, support the collision‐driven DSD evolution hypothesis.
Introduction: Particles and fields
Authors: Moore Thomas , Spann James 
Published: January 2017

AbstractA Conference on Measurement Techniques for Solar and Space Physics was held on 20–24 April 2015 in Boulder, Colorado, at the National Center for Atmospheric Research Center Green Campus. The present volume collects together the papers from this conference in the categories of particles and fields. This also includes neutral gas techniques as well as low‐energy ionospheric plasmas and their interactions with spacecrafts.
A mandible from the Middle Pleistocene Hexian site and its significance in relation to the variability of Asian Homo erectus
Authors: Liu Wu , Martinón‐Torres María , Kaifu Yousuke , Wu Xiujie , Kono Reiko T. , Chang Chun‐Hsiang , Wei Pianpian , Xing Song , Huang Wanbo , Bermúdez de Castro José María 
Published: January 2017

AbstractObjectivesThis study presents the first detailed morphological description and comparison of a Middle Pleistocene hominin mandibular fragment (PA 831) and associated teeth from the Hexian site in Eastern China. We aim to investigate where the Hexian mandible fits within the genus Homo variability in the light of an increased and better characterized Asian fossils record.MethodsComparative samples include Pleistocene Homo mandibles and teeth from Africa, Asia, and Europe, as well as earlier African hominins (Australopithecus and early Homo) and Holocene recent humans. Both conventional morphological description and metric analysis were used. In addition, virtual reconstructions of the enamel dentine junction (EDJ) surface, pulp cavity, and roots with micro‐CT were used to the mandible and teeth.ResultsThe Hexian mandible is characterized by a plesiomorphic structural pattern for the Homo clade, with strong corpus robustness and a subparallel and low‐positioned mylohyoid line that differentiates the swollen subalveolar planum from the shallow subalveolar fossa. Features that are derived compared to early Homo include a moderately curved dental arcade, a well‐developed lateral prominence placed at the M2‐M3 level, and multiple mental foramina. The Hexian mandible's complex enamel surface and strong, stout root structure are primitive traits for the Homo clade. Finally, the highly crenulated “dendrite‐like” EDJ found in the molars may represent a dental feature specific to the continental Asian Homo erectus, but more data is needed to confirm this.ConclusionsMandibular and dental features indicate that the Hexian mandible and teeth differ from northern Chinese H. erectus and European Middle Pleistocene hominins, but show some affinities with the Early Pleistocene specimens from Africa (Homo ergaster) and Java (H. erectus), as well as the Middle‐Late Pleistocene mandible from Penghu, Taiwan. Compared to contemporaneous continental Asian hominin populations, the Hexian fossils may represent the survival of a primitive hominin, with more primitive morphologies than other contemporaneous or some chronologically older Asian hominin specimens.
Domestication and human demographic history in South America
Authors: Perez S. Ivan , Postillone María Bárbara , Rindel Diego 
Published: January 2017

AbstractObjectivesThe early groups of hunter‐gatherers who peopled South America faced significant ecological changes in their trophic niche for a relatively short period after the initial peopling. In particular, the incorporation of cultigens during the Holocene led to a wider trophic niche and probably to an increased carrying capacity of the environment. Here, we study the relationship between the incorporation of domestic resources during the Holocene and the demographic dynamics of human populations at a regional scale in South America.Material and methodsWe employ mitochondrial DNA (mtDNA), radiocarbon data and Bayesian methods to estimate differences in population size, human occupation and explore the demographic changes of human populations in three regions (i.e., South‐Central Andes, Northwest, and South Patagonia). We also use archaeological evidence to infer the main diet changes in these regions.ResultsThe absolute population size during the later Late Holocene was fifteen times larger in the South‐Central Andes than in Northwest Patagonia, and two times larger in the latter region than in South Patagonia. The South‐Central Andes display the earlier and more abrupt population growth, beginning about 9000 years BP, whereas Northwest Patagonia exhibits a more slow growth, beginning about 7000–7500 years BP. South Patagonia represents a later and slower population increase.DiscussionIn this work we uncovered a well‐supported pattern of the demographic change in the populations from South‐Central Andes and Patagonia, obtained on the basis of different data and quantitative approaches, which suggests that the incorporation of domestic resources was paramount for the demographic expansion of these populations during the Holocene.
Poly(N‐[4H‐1,2,4‐triazol‐4‐yl]acrylamide) with different ratio of poly(vinyl chloride) composite membrane for liquid phase sensing of alcohol
Authors: Mahato Manmatha , Ghosh Alokesh , Roy Hena , Bhattacharyya Nabarun , Adhikari Basudam 
Published: January 2017

ABSTRACTFunctionalized polymer membranes have been used as sensor materials for fabrication of electronic tongue. Here, we report the synthesis and characterization of a novel poly(N‐[4H‐1,2,4‐triazol‐4‐yl]acrylamide) (PNTA) for liquid phase aliphatic alcohol sensing in the form of membranes prepared after blending with poly(vinyl chloride) (PVC). Three PNTA‐PVC based membranes were prepared for sensing of six aliphatic alcohols. Polymer membranes were characterized by spectroscopic techniques. Polar groups on PNTA molecules contribute to the alcohol sensing characteristics. The membrane electric potential, generated by the interaction between membrane surface and aqueous aliphatic alcohols, was monitored with the developed multi‐channel electrode based prototype sensing system (MEBPSS). The polymer membranes showed distinct and repeatable response patterns toward different aliphatic alcohols. Among them PNTA‐PVC12 membrane showed maximum discrimination ability due to the PNTA molecules on the membrane surface with highest charge density as ascertained from field emission scanning electron microscopic studies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44675.
Thermal, mechanical, and dielectric studies on the DGEBA epoxy blends by using liquid oxidized poly(1,2‐butadiene) as a reactive component
Authors: Gao Limei , Wang Jinwei 
Published: January 2017

ABSTRACTLiquid oxidized poly(1,2‐butadiene) (LOPB) with multi epoxy groups is synthesized to modify diglycidyl end‐caped poly(bisphenol A‐co‐epichlorohydrin) (DGEBA) cured by 4,4′‐diaminodiphenyl sulfone (DDS). FTIR spectra shows that DGEBA and LOPB can be effectively cured by DDS, and the epoxide rubber particles are evenly distributed in the composites till their addition up to 20 wt % of DGEBA as seen from the scanning electron microscope (SEM). Their decomposition temperatures (Td) increase with the increase in LOPB addition at around 10 wt % of DGEBA while the Td for the composite containing 20 wt % LOPB of DGEBA is lower than that of the neat epoxy. The addition of LOPB improves their storage moduli and especially these values at temperatures higher above 150 °C; all the composites exhibit higher glass transition temperature (Tg) than that of the neat epoxy, and the maximum Tg reaches up to 255 °C for the composite containing 15 wt % LOPB of DGEBA. The incorporation of LOPB effectively decreases their dielectric constants and the composite with 10 wt % LOPB of DGEBA possesses the lowest one. The synergic improvements in their various properties are attributed to the networks formation via covalent linkage between the two phases in these reactive blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44689.
Inducing surface porosity in aqueous‐quenched, microporous Nylon 11 and Nylon 12 films
Authors: Funk Caleb V. , Billovits Gerald F. , Koreltz Michael S. , Dooley Joseph , Chiou Nan‐Rong 
Published: January 2017

ABSTRACTNylon 11 and Nylon 12 have been studied for many years for the purpose of fabricating microporous films. Unfortunately, these polymers have somewhat unique properties that prevent the films from exhibiting porous surfaces when their solutions undergo thermally induced phase separation by quenching in water. Without surface pores, these films have limited utility as water purification membranes. In this work, application of high temperature diluent coatings to the surface prior to quenching is shown to enable the formation of surface porosity in Nylon 11 and Nylon 12 films. Furthermore, the pore sizes achieved are suitable for ultrafiltration applications. Following successful lab‐scale coating experiments, the effects of coating thickness, temperature, and solvent type on surface morphology are demonstrated over five film extrusion trials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44695.
Biopolymer agar‐agar doped with NH4SCN as solid polymer electrolyte for electrochemical cell application
Authors: Selvalakshmi S. , Vijaya N. , Selvasekarapandian S. , Premalatha M. 
Published: January 2017

ABSTRACTA new polymer electrolyte based on the biopolymer Agar‐Agar doped with ammonium thiocyanate (NH4SCN) has been prepared and characterized by FTIR analysis, X‐ray diffraction measurements, AC impedance spectroscopy, transference number measurements, and DSC analysis. The Fourier transform infrared analysis confirms the complex formation between agar and NH4SCN. The amorphous nature of the polymer electrolyte has been revealed from X‐ray diffraction analysis. The highest ionic conductivity has been observed for the sample of composition 1:1 between Agar and NH4SCN. As a function of temperature, the ionic conductivity of this sample exhibits Arrhenius behavior increasing from 1.03 × 10−3 S cm−1 at ambient temperature to 3.16 × 10−3 S cm−1 at 343 K. The transference number has been estimated by the dc polarization method, and it has been proven that the conducting species are predominantly cations. Using the highest conductivity polymer electrolyte, solid state electrochemical cell has been fabricated and cell parameters are reported. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44702.