bluuebunny/crossref_metadata_2025_split huggingface dataset:
Classification of geochemical data based on multivariate statistical analyses: Complementary roles of cluster, principal component, and independent component analyses
Authors: Iwamori Hikaru , Yoshida Kenta , Nakamura Hitomi , Kuwatani Tatsu , Hamada Morihisa , Haraguchi Satoru , Ueki Kenta 
Published: January 2017

AbstractIdentifying the data structure including trends and groups/clusters in geochemical problems is essential to discuss the origin of sources and processes from the observed variability of data. An increasing number and high dimensionality of recent geochemical data require efficient and accurate multivariate statistical analysis methods. In this paper, we show the relationship and complementary roles of k‐means cluster analysis (KCA), principal component analysis (PCA), and independent component analysis (ICA) to capture the true data structure. When the data are preprocessed by primary standardization (i.e., with the zero mean and normalized by the standard deviation), KCA and PCA provide essentially the same results, although the former returns the solution in a discretized space. When the data are preprocessed by whitening (i.e., normalized by eigenvalues along the principal components), KCA and ICA may identify a set of independent trends and groups, irrespective of the amplitude (power) of variance. As an example, basalt isotopic compositions have been analyzed with KCA on the whitened data, demonstrating clear rock type/tectonic occurrence/mantle end‐member discrimination. Therefore, the combination of these methods, particularly KCA on whitened data, is useful to capture and discuss the data structure of various geochemical systems, for which an Excel program is provided.
Upper mantle seismic anisotropy beneath the Northern Transantarctic Mountains, Antarctica from PKS, SKS, and SKKS splitting analysis
Authors: Graw Jordan H. , Hansen Samantha E. 
Published: January 2017

AbstractUsing data from the new Transantarctic Mountains Northern Network, this study aims to constrain azimuthal anisotropy beneath a previously unexplored portion of the Transantarctic Mountains (TAMs) to assess both past and present deformational processes occurring in this region. Shear‐wave splitting parameters have been measured for PKS, SKS, and SKKS phases using the eigenvalue method within the SplitLab software package. Results show two distinct geographic regions of anisotropy within our study area: one behind the TAMs front, with an average fast axis direction of 42 ± 3° and an average delay time of 0.9 ± 0.04 s, and the other within the TAMs near the Ross Sea coastline, with an average fast axis oriented at 51 ± 5° and an average delay time of 1.5 ± 0.08 s. Behind the TAMs front, our results are best explained by a single anisotropic layer that is estimated to be 81–135 km thick, thereby constraining the anisotropic signature within the East Antarctic lithosphere. We interpret the anisotropy behind the TAMs front as relict fabric associated with tectonic episodes occurring early in Antarctica's geologic history. For the coastal stations, our results are best explained by a single anisotropic layer estimated to be 135–225 km thick. This places the anisotropic source within the viscous asthenosphere, which correlates with low seismic velocities along the edge of the West Antarctic Rift System. We interpret the coastal anisotropic signature as resulting from active mantle flow associated with rift‐related decompression melting and Cenozoic extension.
An evaluation of benthic foraminiferal U/Ca and U/Mn proxies for deep ocean carbonate chemistry and redox conditions
Authors: Chen Pujiao , Yu Jimin , Jin Zhangdong 
Published: January 2017

AbstractThe deep ocean is thought to have played a crucial role in modulating atmospheric CO2 changes, and thus reconstructions of deep ocean conditions can place important constraints on the past global carbon cycle. Some previous studies suggested that foraminiferal U/Ca could be used to infer seawater carbonate chemistry changes, but others showed complications from diagenesis and temperature. A recent downcore study suggested that foraminiferal U/Mn may be used for sedimentary redox‐conditions, but no core‐top work has been done to investigate factors affecting U/Mn. We investigate controlling factors on U/Ca and U/Mn in two benthic foraminiferal species from 120 global core‐tops and three Atlantic sediment cores. Our core‐top data reveal no significant correlation between core‐top benthic U/Ca and carbonate system parameters. The lack of an influence of deep‐water [
] on U/Ca is further supported by our downcore results. Together, our data highlight complications to use benthic U/Ca for deep‐water carbonate chemistry reconstructions. Although no correlation is found between core‐top U/Mn and hydrographic data, high‐resolution U/Mn and U/Ca in core TNO57‐21 show similar patterns to authigenic U (aU) and vary in tandem with atmospheric CO2 on millennial timescales. Changes in U/Mn, U/Ca and aU in TNO57‐21 may reflect postdepositional diagenesis linked to sedimentary oxygen, which is controlled by subantarctic surface productivity and ventilation of deep South Atlantic in the past. We suggest that benthic U/Mn and U/Ca may be used as auxiliary indicators for past sedimentary redox‐conditions and along with other proxies could reflect deep‐water oxygenation.
Common climatic signal from glaciers in the European Alps over the last 50 years
Authors: Vincent C. , Fischer A. , Mayer C. , Bauder A. , Galos S. P. , Funk M. , Thibert E. , Six D. , Braun L. , Huss M. 
Published: January 2017

AbstractConventional glacier‐wide mass balances are commonly used to study the effect of climate forcing on glacier melt. Unfortunately, the glacier‐wide mass balances are also influenced by the glacier's dynamic response. Investigations on the effects of climate forcing on glaciers can be largely improved by analyzing point mass balances. Using a statistical model, we have found that 52% of the year‐to‐year deviations in the point mass balances of six glaciers distributed across the entire European Alps can be attributed to a common variability. Point mass balance changes reveal remarkable regional consistencies reaching 80% for glaciers less than 10 km apart. Compared to the steady state conditions of the 1962–1982 period, the surface mass balance changes are −0.85 m water equivalent (w.e.) a−1 for 1983–2002 and −1.63 m w.e. a−1 for 2003–2013. This indicates a clear and regionally consistent acceleration of mass loss over recent decades over the entire European Alps.
Mesospheric temperatures estimated from the meteor radar observations at Mohe, China
Authors: Liu Libo , Liu Huixin , Le Huijun , Chen Yiding , Sun Yang‐Yi , Ning Baiqi , Hu Lianhuan , Wan Weixing , Li Na , Xiong Jiangang 
Published: January 2017

AbstractIn this work, we report the estimation of mesospheric temperatures at 90 km height from the observations of the VHF all‐sky meteor radar operated at Mohe (53.5°N, 122.3°E), China, since August 2011. The kinetic temperature profiles retrieved from the observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics satellite are processed to provide the temperature (TSABER) and temperature gradient (dT/dh) at 90 km height. Based on the SABER temperature profile data an empirical dT/dh model is developed for the Mohe latitude. First, we derive the temperatures from the meteor decay times (Tmeteor) and the Mohe dT/dh model gives prior information of temperature gradients. Second, the full width at half maximum (FWHM) of the meteor height profiles is calculated and further used to deduce the temperatures (TFWHM) based on the strong linear relationship between FWHM and TSABER. The temperatures at 90 km deduced from the decay times (Tmeteor) and from the meteor height distributions (TFWHM) at Mohe are validated/calibrated with TSABER. The temperatures present a considerable annual variation, being maximum in winter and minimum in summer. Harmonic analyses reveal that the temperatures have an annual variation consistent with TSABER. Our work suggests that FWHM has a good performance in routine estimation of the temperatures. It should be pointed out that the slope of FWHM as a function of TSABER is 10.1 at Mohe, which is different from that of 15.71 at King Sejong (62.2°S, 58.8°E) station.
High‐resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales
Authors: Schwartz Stephen E. , Huang Dong , Vladutescu Daniela Viviana 
Published: January 2017

AbstractThis paper describes the approach and presents initial results, for a period of several minutes in north central Oklahoma, of an examination of clouds by high‐resolution digital photography from the surface looking vertically upward. A commercially available camera having 35 mm equivalent focal length up to 1200 mm (nominal resolution as fine as 6 µrad, which corresponds to 9 mm for cloud height 1.5 km) is used to obtain a measure of zenith radiance of a 30 m × 30 m domain as a two‐dimensional image consisting of 3456 × 3456 pixels (12 million pixels). Downwelling zenith radiance varies substantially within single images and between successive images obtained at 4 s intervals. Variation in zenith radiance found on scales down to about 10 cm is attributed to variation in cloud optical depth (COD). Attention here is directed primarily to optically thin clouds; COD less than about 2. A radiation transfer model used to relate downwelling zenith radiance to COD and to relate the counts in the camera image to zenith radiance permits determination of COD on a pixel‐by‐pixel basis. COD for thin clouds determined in this way exhibits considerable variation, for example, an order of magnitude within 15 m, a factor of 2 within 4 m, and 25% (0.12 to 0.15) over 14 cm. This approach, which examines cloud structure on scales 3 to 5 orders of magnitude finer than satellite products, opens new avenues for examination of cloud structure and evolution.
Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment
Authors: Blackburn M. , Ledesma José L. J. , Näsholm Torgny , Laudon Hjalmar , Sponseller Ryan A. 
Published: January 2017

AbstractCatchment science has long held that the chemistry of small streams reflects the landscapes they drain. However, understanding the contribution of different landscape units to stream chemistry remains a challenge which frequently limits our understanding of export dynamics. For limiting nutrients such as nitrogen (N), an implicit assumption is that the most spatially extensive landscape units (e.g., uplands) act as the primary sources to surface waters, while near‐stream zones function more often as sinks. These assumptions, based largely on studies in high‐gradient systems or in regions with elevated inputs of anthropogenic N, may not apply to low‐gradient, nutrient‐poor, and peat‐rich catchments characteristic of many northern ecosystems. We quantified patterns of N mobilization along a hillslope transect in a northern boreal catchment to assess the extent to which organic matter‐rich riparian soils regulate the flux of N to streams. Contrary to the prevailing view of riparian functioning, we found that near‐stream, organic soils supported concentrations and fluxes of ammonium (NH4+) and dissolved organic nitrogen that were much higher than the contributing upslope forest soils. These results suggest that stream N chemistry is connected to N mobilization and mineralization within the riparian zone rather than the wider landscape. Results further suggest that water table fluctuation in near‐surface riparian soils may promote elevated rates of net N mineralization in these landscapes.
Estimating belowground carbon stocks in peatlands of the Ecuadorian páramo using ground‐penetrating radar (GPR)
Authors: Comas Xavier , Terry Neil , Hribljan John A. , Lilleskov Erik A. , Suarez Esteban , Chimner Rodney A. , Kolka Randy K. 
Published: January 2017

AbstractThe páramo ecoregion of Ecuador contains extensive peatlands that are known to contain carbon (C) dense soils capable of long‐term C storage. Although high‐altitude mountain peatlands are typically small when compared to low‐altitude peatlands, they are abundant across the Andean landscape and are likely a key component in regional C cycling. Since efforts to quantify peatland distribution and C stocks across the tropical Andes have been limited due to the difficulty in sampling remote areas with very deep peat, there is a large knowledge gap in our quantification of the current C pools in the Andean mountains, which limits our ability to predict and monitor change from high rates of land use and climate change. In this paper we tested if ground‐penetrating radar (GPR), combined with manual coring and C analysis, could be used for estimating C stocks in peatlands of the Ecuadorian páramo. Our results indicated that GPR was successful in quantifying peat depths and carbon stocks. Detection of volcanic horizons like tephra layers allowed further refinement of variability of C stocks within the peat column, while providing information on the lateral extent of tephras at high (centimeter‐scale) resolution that may prove very useful for the correlation of time‐stratigraphic markers between sediments in alpine peatlands. In conclusion, this paper provides a methodological basis for quantifying C stocks in high‐altitude peatlands and to infer changes in the physical properties of soils that could be used as proxies for C content or paleoclimate reconstructions.
A single‐station empirical model for TEC over the Antarctic Peninsula using GPS‐TEC data
Authors: Feng Jiandi , Wang Zhengtao , Jiang Weiping , Zhao Zhenzhen , Zhang Bingbing 
Published: January 2017

AbstractCompared with regional or global total electron content (TEC) empirical models, single‐station TEC empirical models may exhibit higher accuracy in describing TEC spatial and temporal variations for a single station. In this paper, a new single‐station empirical total electron content (TEC) model, called SSM‐month, for the O'Higgins Station in the Antarctic Peninsula is proposed by using Global Positioning System (GPS)‐TEC data from 01 January 2004 to 30 June 2015. The diurnal variation of TEC in the O'Higgins Station may have changing features in different months, sometimes even in opposite forms, because of ionospheric phenomena, such as the Mid‐latitude Summer Nighttime Anomaly (MSNA). To avoid the influence of different diurnal variations, the concept of monthly modeling is proposed in this study. The SSM‐month model, which is established by month (including 12 submodels that correspond to the 12 months), can effectively describe the diurnal variation of TEC in different months. Each submodel of the SSM‐month model exhibits good agreement with GPS‐TEC input data. Overall, the SSM‐month model fits the input data with a bias of 0.03 TECU (total electron content unit, 1 TECU = 1016 el m−2) and a standard deviation of 2.78 TECU. This model, which benefits from the modeling method, can effectively describe the MSNA phenomenon without implementing any modeling correction. TEC data derived from Center for Orbit Determination in Europe global ionosphere maps (CODE GIMs), International Reference Ionosphere 2012 (IRI2012), and NeQuick are compared with the SSM‐month model in the years of 2001 and 2015–2016. Result shows that the SSM‐month model exhibits good consistency with CODE GIMs, which is better than that of IRI2012 and NeQuick, in the O'Higgins Station on the test days.
Observability of ionospheric space‐time structure with ISR: A simulation study
Authors: Swoboda John , Semeter Joshua , Zettergren Matthew , Erickson Philip J. 
Published: January 2017

AbstractThe sources of error from electronically steerable array (ESA) incoherent scatter radar (ISR) systems are investigated both theoretically and with use of an open‐source ISR simulator, developed by the authors, called Simulator for ISR (SimISR). The main sources of error incorporated in the simulator include statistical uncertainty, which arises due to nature of the measurement mechanism and the inherent space‐time ambiguity from the sensor. SimISR can take a field of plasma parameters, parameterized by time and space, and create simulated ISR data at the scattered electric field (i.e., complex receiver voltage) level, subsequently processing these data to show possible reconstructions of the original parameter field. To demonstrate general utility, we show a number of simulation examples, with two cases using data from a self‐consistent multifluid transport model. Results highlight the significant influence of the forward model of the ISR process and the resulting statistical uncertainty on plasma parameter measurements and the core experiment design trade‐offs that must be made when planning observations. These conclusions further underscore the utility of this class of measurement simulator as a design tool for more optimal experiment design efforts using flexible ESA class ISR systems.
Historical space weather monitoring of prolonged aurora activities in Japan and in China
Authors: Kataoka Ryuho , Isobe Hiroaki , Hayakawa Hisashi , Tamazawa Harufumi , Kawamura Akito Davis , Miyahara Hiroko , Iwahashi Kiyomi , Yamamoto Kazuaki , Takei Masako , Terashima Tsuneyo , Suzuki Hidehiko , Fujiwara Yasunori , Nakamura Takuji 
Published: January 2017

AbstractGreat magnetic storms are recorded as aurora sightings in historical documents. The earliest known example of “prolonged” aurora sightings, with aurora persistent for two or more nights within a 7 day interval at low latitudes, in Japan was documented on 21–23 February 1204 in Meigetsuki, when a big sunspot was also recorded in China. We have searched for prolonged events over the 600 year interval since 620 in Japan based on the catalogue of Kanda [] and over the 700 year interval since 581 in China based on the catalogues of Tamazawa et al. (2017) and Hayakawa et al. (2015). Before the Meigetsuki event, a significant fraction of the 200 possible aurora sightings in Sòng dynasty (960–1279) of China was detected at least twice within a 7 day interval and sometimes recurred with approximately the solar rotation period of 27 days. The majority of prolonged aurora activity events occurred around the maximum phase of solar cycles rather than around the minimum, as estimated from the 14C analysis of tree rings. They were not reported during the Oort Minimum (1010–1050). We hypothesize that the prolonged aurora sightings are associated with great magnetic storms resulting from multiple coronal mass ejections from the same active region. The historical documents therefore provide useful information to support estimation of great magnetic storm frequency, which are often associated with power outages and other societal concerns.
Characterizing the spatial correlation of daily streamflows
Authors: Betterle A. , Schirmer M. , Botter G. 
Published: January 2017

AbstractIn this study we propose an analytical framework to estimate the spatial correlation of daily flows at two arbitrary locations within a given hydrologic district or river basin. The method builds on the description of the coupled streamflow dynamics at the outlet of two catchments, which are represented as correlated shot noises forced by Poisson rainfall. Novel analytical expressions for the spatial correlation of discharge are derived using a limited number of parameters that encapsulate effective precipitation regime and catchment drainage rates. The method is suited to describe how heterogeneity of climate and landscape features impact the spatial and temporal variability of flow regimes along river systems. The analysis suggests that frequency and intensity of synchronous effective rainfall events in the relevant contributing catchments are the main driver of the spatial correlation of daily discharge, unless the drainage rates of the two catchments differ by almost one order of magnitude. The method also portrays how the topological arrangement of the two outlets along the river network influences the underlying streamflow correlation and shows how nested catchments tend to maximize the spatial correlation of flow regimes. To demonstrate the potential of the tool, the model is tested on a set of 16 catchments belonging to a 120,000 km2region of the United States. The application evidences satisfactory performance in reproducing the observed spatial correlation of daily streamflows among the study sites (RMSE < 0.1). The approach provides a clue for the characterization of water availability in space at seasonal time scale, with implications for water resources assessment, risk prevention, and ecological studies.
Released for Public Comment: Space Weather Benchmarks and Operations‐to‐Research Plan
Authors: Jonas Seth , Murtagh William , Bonadonna Michael 
Published: January 2017

AbstractThe National Oceanic and Atmospheric Administration, on behalf of the National Science and Technology Council, published two notices in the Federal Register seeking public comment on draft products from the National Space Weather Action Plan: Space weather benchmarks and an operations‐to‐research plan.
Clustered assembly of Au nanoparticles from spherical diblock copolymer micelles encapsulating Au nanoparticle
Authors: Kim Jang Hwan , Zakia Maulida , Kim Joo Hyun , Park Seong Soo , Yoon Jinhwan , Huh PilHo , Yoo Seong II 
Published: January 2017

ABSTRACTSuperstructures composed of diblock copolymer micelles and inorganic nanoparticles are quite interesting because the specific arrangement of inorganic nanoparticles within the micellar structure can reveal interesting opportunities in many field of science. In this perspective, we report a simple method to produce clustered assembly of Au nanoparticles in the micelles in attempt to induce plasmonic coupling among multiple Au nanoparticles in the assembled structures. Here, we utilized polystyrene‐block‐poly(acrylic acid), PS‐PAA, micelles containing single Au nanoparticle in the core (Au@PS‐PAA micelles) as building materials to initiate next‐level assembling process. In particular, the addition of HCl to the solution of Au@PS‐PAA micelles affected the overall equilibrium condition as well as kinetic process in the micellar solution. As a result, individual Au@PS‐PAA micelles could be merged together to form more large micelles with inclusion of multiple nanoparticles in the core, the process of which was accompanied with plasmonic coupling of Au nanoparticles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44693.
Hydrogels based on copolymers of 2‐hydroxyethylmethacrylate and 2‐hydroxyethylacrylate as a delivery system for proteins: Interactions with lysozyme
Authors: Hackl Ellen V. , Khutoryanskiy Vitaliy V. , Ermolina Irina 
Published: January 2017

ABSTRACTHydrogels have attracted considerable attention due to numerous applications, in particular as contact lenses and carriers for sustained drug delivery. The aim of the present work is to characterize the interactions of copolymer hydrogels consisted of 2‐hydroxyethylmethacrylate (HEMA) and 2‐hydroxyethylacrylate (HEA) with a small protein (lysozyme) and to assess the potential applications of these hydrogels as a drug delivery system for sustained release of protein‐based therapeutics. Physicochemical properties of protein‐loaded hydrogels, as well as lysozymein vitroloading and release and the conformation of the protein released from hydrogels were studied. The effect of copolymer composition on the protein deposition on hydrogels and protein aggregation in the presence of hydrogels was also assessed. The results show that introduction of HEA into the copolymeric hydrogels enhances their suitability as a delivery system for proteins. Copolymerisation of HEMA and HEA allows controlling the physicochemical properties of hydrogels and the protein release rate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 44768.