bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Early Neolithic Grave and Occupation, and an Early Bronze Age Hearth on the Thames Foreshore at Yabsley Street, Blackwall, London
Authors: Coles Sarah , Ford Steve , Taylor Andy , Anthony Sian , Gale Rowena , Keith-Lucas Michael , Raymond Frances , Robinson Mark , Vince Alan 
Published: January 2020

Excavation on the Thames floodplain in London revealed traces of Early Neolithic occupation and burial on a sand and gravel bar beneath alluvium. A large expanse of peat also buried by alluvium was recorded between these finds and the modern river Thames suggesting that the occupation was situated on or close to the foreshore. A single grave cut into the natural sand contained a poorly preserved crouched inhumation, possibly of a woman. The burial was accompanied by a fragment of carinated bowl, a flint knife, and other struck flints. A radiocarbon date from an oak retaining plank within the grave of 5252±28 BP (4220–3970 cal BC: KIA20157) makes this burial one of the earliest from the British Isles and the earliest known for London. A scatter of struck flint and pottery predominantly of Early Neolithic date was recovered from adjacent areas of the sand. A nearby hearth contained fragments of Early Bronze Age pottery pointing to later prehistoric activity nearby.Charred plant remains indicate both the collection of wild plant foods and cultivated cereals in the Early Neolithic. Radiocarbon dating of the adjacent peat deposits indicated their rapid growth within the Middle Bronze Age with a marked decline in woodland cover at the start of the sequence and a rise in grassland and herb species. Cereal pollen then briefly became a significant component of the sequence before declining to more modest levels.
Neolithic Causewayed Enclosures and Later Prehistoric Farming: Duality, Imposition and the Role of Predecessors at Kingsborough, Isle of Sheppey, Kent, UK
Authors: Allen Michael J. , Leivers Matt , Ellis Chris , Stevens Simon , Clelland Susan , Bayliss Alex , Butler Chris , Gale Rowena , Gibson Alex , McKinley Jacqueline I. , Knight Stephanie , Mepham Lorraine , Scaife Robert , Stevens Chris J. 
Published: January 2020

Developer-funded archaeology on the Isle of Sheppey resulted in the discovery of not one but two Neolithic causewayed enclosures on the same hilltop in very close (c. 300 m) proximity. In the later Bronze Age enclosures and cremation cemeteries were constructed immediately to the east, followed by Iron Age enclosures and, ultimately, field systems dating to the later Iron Age onwards.A radiocarbon programme enabled the chronological sequence and hiatus between all of these events to be discerned, but the majority of this paper explores the physical, chronological, and social relationship between the two Neolithic causewayed enclosures. These were of different forms and, although on the same hilltop, they each seem to have had distinctly different viewsheds over the Thames and the Swale respectively. There are subtle, but potentially significant, differences in the material culture and deposition which allow exploration of the possible functions and role(s) of the two largely contemporaneous sites. Questions may be addressed such as whether they performed the same functions for two communities or had separate and distinct roles for a single community. Beyond the Neolithic, the paper also explores the nature of the later use of the hilltop. The Bronze Age enclosures, though agricultural in function, clearly seem to respect their Neolithic predecessors invoking a remembrance of space, which is lost by the Iron Age. The shift away from the special function of this landscape in the Neolithic to a subsequent agricultural use is explored, as is the hiatus in use and subsequent re-use of the area.
Politics of Scale, Bargaining Power and Its Spatial Impacts: Planning for Intercity Railways in the Pearl River Delta, China
Authors: Zhang Mengmeng , Xu Jiang , Chung Calvin King Lam 
Published: January 2020

AbstractThe recent proliferation of China's railways has posed challenges to the dominance of the national-level railway authority on railway development. Since the 2000s, the planning of new railways has evolved into a politics of scale in which actors across multiple scales of government have bargained over railway alignment and station siting for their respective interests. This politics is shaped by the uneven bargaining powers of the contending state agents over railway planning. Interscalar division of regulatory oversight over strategic resources for railway development enables state agents at some scales to bargain more successfully, whereas variations in administrative and economic standing further differentiate the interscalar bargaining powers of municipal governments. Different results of bargaining across scales for each city have produced, as intercity railway planning in the Pearl River Delta illustrates, significant intercity variations in average travel times to the stations for the new railways that these cities share. Owing to the peculiar scalar distribution of the costs and benefits of the new railways, municipal governments with greater bargaining power have, contrary to traditional wisdom, bargained for less accessibility to intercity railway stations.
Oscillatory brain dynamics of pronoun processing in native Spanish speakers and in late second language learners of Spanish
Authors: Rossi Eleonora , Prystauka Yanina 
Published: January 2020

AbstractA longstanding question in the second language acquisition literature is whether late second language (L2) learners process grammatical structures in a native-like manner. Here, we use Time Frequency Representation (TFR) analysis to test morpho-syntactic processing of clitic pronouns in native and late L2 learners of Spanish. The TFR results show overall similar power decreases in theta, alpha, and beta frequencies in both groups. Critically, the observed oscillatory effects persisted in time for native Spanish speakers, but declined earlier for L2 learners. We discuss the results using cell-assembly theory models for language processing (e.g., Pulvermüller, 1999) that posit a biphasic time-course for neural assemblies consisting of an early ignition (recognition) and a later reverberation (re-processing) phase. We propose a working hypothesis for L2 processing in tune with a cell-assembly theory suggesting that the length of the reverberation phase could be a distinguishing feature between native and L2 processing.
LYAPUNOV-TYPE INEQUALITY FOR EXTREMAL PUCCI’S EQUATIONS
Authors: TYAGI J. , VERMA R. B. 
Published: January 2020

AbstractIn this article, we establish a Lyapunov-type inequality for the following extremal Pucci’s equation:$$\begin{eqnarray}\left\{\begin{array}{@{}ll@{}}{\mathcal{M}}_{\unicode[STIX]{x1D706},\unicode[STIX]{x1D6EC}}^{+}(D^{2}u)+b(x)|Du|+a(x)u=0 & \text{in}~\unicode[STIX]{x1D6FA},\\ u=0 & \text{on}~\unicode[STIX]{x2202}\unicode[STIX]{x1D6FA},\end{array}\right.\end{eqnarray}$$where$\unicode[STIX]{x1D6FA}$is a smooth bounded domain in$\mathbb{R}^{N}$,$N\geq 2$. This work generalizes the well-known works on the Lyapunov inequality for extremal Pucci’s equations with gradient nonlinearity.
Association of depression and diabetes complications and mortality: a population-based cohort study
Authors: Wu C.-S. , Hsu L.-Y. , Wang S.-H. 
Published: January 2020

Abstract

Aims
Several studies suggested that depression might worsen the clinical outcome of diabetes mellitus; however, such association was confounded by duration of illness and baseline complications. This study aimed to assess whether depression increases the risk of diabetes complications and mortality among incident patients with diabetes.

Methods
This was a population-based matched cohort study using Taiwan's National Health Insurance Research Database. A total of 38 537 incident patients with diabetes who had depressive disorders and 154 148 incident diabetes patients without depression who were matched by age, sex and cohort entry year were randomly selected. The study endpoint was the development of macrovascular and microvascular complications, all-cause mortality and cause-specific mortality.

Results
Among participants, the mean (±SD) age was 52.61 (±12.45) years, and 39.63% were male. The average duration of follow-up for mortality was 5.5 years, ranging from 0 to 14 years. The adjusted hazard ratios were 1.35 (95% confidence interval [CI], 1.32–1.37) for macrovascular complications and 1.08 (95% CI, 1.04–1.12) for all-cause mortality. However, there was no association of depression with microvascular complications, mortality due to cardiovascular diseases or mortality due to diabetes mellitus. The effect of depression on diabetes complications and mortality was more prominent among young adults than among middle-aged and older adults.

Conclusions
Depression was associated with macrovascular complications and all-cause mortality in our patient cohort. However, the magnitude of association was less than that in previous studies. Further research should focus on the benefits and risks of treatment for depression on diabetes outcome.
The Impact of an Intense Cyclone on Short‐Term Sea Ice Loss in a Fully Coupled Atmosphere‐Ocean‐Ice Model
Authors: Stern Daniel P. , Doyle James D. , Barton Neil P. , Finocchio Peter M. , Komaromi William A. , Metzger E. Joseph 
Published: January 2020

AbstractArctic cyclones may be associated with periods of locally enhanced sea ice loss during the summer, and some studies have found that an intense cyclone in August 2012 resulted in a rapid sea ice retreat. This study uses a coupled atmosphere‐ocean‐ice model (Navy‐ESPC) to explore the relationship between the 2012 cyclone and short‐term sea ice melting. There are two mechanisms of cyclone‐induced melting in Navy‐ESPC: turbulent mixing of a warm layer located at 15‐ to 35‐m depth increases bottom melting and warm air advection by the strong surface winds increases surface melting. Although the rate of sea ice melt is substantially increased in association with the cyclone, this effect is confined to a relatively small region and only lasts for a few days. There is no clear signature of the cyclone on the overall Arctic sea ice extent in Navy‐ESPC.
Untangling El Niño‐La Niña Asymmetries Using a Nonlinear Coupled Dynamic Index
Authors: Kim Soong‐Ki , An Soon‐Il 
Published: January 2020

AbstractThe linear recharge oscillator model for the El Niño–Southern Oscillation (ENSO) was expanded to a nonlinear model, thus allowing identification of a nonlinear dynamic ENSO index. This index was applied for a dynamic examination of the El Niño‐La Niña asymmetry. Here, the nonlinear physical processes including the nonlinear dynamical heating were implemented into the linear recharge oscillator model in the form of quadratic nonlinearity. This nonlinear recharge oscillator model revealed that nonlinear (linear) physical processes play a critical role in the long‐term ENSO skewness (amplitude) changes quantitatively. Particularly, the large part of the long‐term ENSO skewness change could be explained by the quadratic nonlinearity associated with the nonlinear ocean dynamical heating, which is closely related to change in mean thermocline. This research provides a unified framework to understand better the past‐present‐future ENSO changes by applying the interdecadal change dynamics on a low hierarchical level.
The Southern Zagros Collisional Orogen: New Insights From Transdimensional Trees Inversion of Seismic Noise
Authors: Pilia S. , Jackson J. A. , Hawkins R. , Kaviani A. , Ali M. Y. 
Published: January 2020

AbstractImaging and resolving the lateral continuity of 3‐D crustal structures enhance our ability to interpret seismicity and to understand how orogens are created. We apply a Bayesian, hierarchical inversion approach based on a transdimensional trees‐structured wavelet parameterization to recover phase velocity maps at 2–40 s periods. We then invert phase velocity dispersion to constrain a 3‐D shear velocity model of the crust beneath south‐central Iran. Together with accurate earthquake centroid depths and focal mechanisms, the pattern of 3‐D velocity variations supports recent suggestions that most large earthquakes in the Zagros occur within the lower sedimentary cover or close to the sediment‐basement interface. Furthermore, we find evidence for Arabian basement underthrusting beneath central Iran, although only in one location does it appear to generate earthquakes. Our new 3‐D tomographic model clarifies and throws new light on the crustal structure of the SE Zagros and its relation to seismicity and active faulting.
Rapid Formation of Clathrate Hydrate From Liquid Ethane and Water Ice on Titan
Authors: Vu T. H. , Choukroun M. , Sotin C. , Muñoz‐Iglesias V. , Maynard‐Casely H. E. 
Published: January 2020

AbstractLiquid ethane is present in the lakes and seas observed on Titan's surface by the Cassini‐Huygens mission. While interaction between liquid hydrocarbons and water ice is expected to result in the formation of clathrate hydrates, such reaction (and its kinetics) has not yet been demonstrated for cryogenic liquids under relevant planetary conditions. In this paper, we report the first experimental evidence for rapid formation of clathrates upon direct contact of liquid ethane with water ice at 1 bar using micro‐Raman spectroscopy. Kinetics experiments conducted in the temperature range 150–173 K yield an activation energy of 14.8 ± 2.2 kJ/mol, which is suggestive of a diffusion‐controlled mechanism for clathrate formation. This implies that a clathrate reservoir can form within seasonal time scales on Titan if liquid ethane comes into contact with a pre‐existing icy bedrock, which may hold important implications for the structure and dynamics of Titan's crust and its global evolution.
Kinetic Alfvén Waves From Magnetotail to the Ionosphere in Global Hybrid Simulation Associated With Fast Flows
Authors: Cheng Lei , Lin Yu , Perez J. D. , Johnson Jay R. , Wang Xueyi 
Published: January 2020

AbstractWe have used the Auburn Global Hybrid Code in 3‐D to study the generation, dynamics, and global structure of kinetic Alfvén waves (KAWs) from the magnetotail to the ionosphere. Our results show that KAWs are generated in magnetic reconnection in the plasma sheet, located around fast flows, and carrying transverse electromagnetic perturbations, parallel Poynting fluxes, parallel currents, and parallel electric field. Overall, shear Alfvénic turbulent spectrum is found in the plasma sheet. The KAWs are shear Alfvén waves possessing short perpendicular wavelength with
, where
is the perpendicular wave number and
the ion Larmor radius. The KAWs are identified by their dispersion relation and polarizations. The structures of these KAWs embedded in the plasma sheet are also revealed by placing a virtual satellite in the tail. In order to understand whether the Poynting fluxes carried by the shear Alfvén waves/KAWs in the plasma sheet can be carried directly along field lines to the ionosphere, we have tracked the wave propagation from the plasma sheet to the ionosphere. It is found that in front of the flow‐braking region, the structure and strength of the shear Alfvén waves are significantly altered due to interaction with the dipole‐like field, mainly by the flow shear associated with the azimuthal convection. Also in front of the dipole‐like field region, ion kinetic effects (Hall effects) lead to the generation of additional pairs of KAWs. As such, the generation and transport of the shear Alfvén waves/KAWs to the ionosphere are illustrated for the first time in a comprehensive manner on the global scale.
Estimation of Planar Trend Model Parameters for Midlatitude Ionosphere
Authors: Kumbay Yildiz S. , Arikan F. 
Published: January 2020

AbstractBeing under influence of the polar and equatorial regions, the midlatitude ionosphere poses an important challenge in structural modeling. In this study, the general understanding of regional planar trend model is investigated for 2011 by estimation of trend coefficients in the least squares sense. The northern midlatitude is divided into 24 nonoverlapping regions of 10° by 20° in latitude and longitude, respectively. The magnetic conjugates of 24 regions in the Southern Hemisphere are also extracted. The total electron content values are obtained from global ionospheric maps (GIM) with spatial resolution of 2.5° by 5° in latitude and longitude, respectively. The temporal resolution of GIM can be 1 or 2 hr. Estimated planar trend coefficients are used to reconstruct model maps. The difference between GIM and the estimated planar model is obtained in normalized
norm squares sense. It is observed that the planar trend model in latitude and longitude is an agreeable model for total electron content over midlatitude regions for both Northern and Southern Hemispheres. The estimated model parameters generally follow the diurnal, seasonal, and semiannual trend structures of midlatitude ionosphere. The deviations from the model occur mostly during severe disturbances such as geomagnetic storms. The difference between the reconstructed model maps with estimated parameters and GIM is generally under 1% for land and 2% to 5% for ocean regions. The only region that has a very high spread and mostly up to 10% difference with the GIM throughout the year is on the California Current.
ML‐Helio: An Emerging Community at the Intersection Between Heliophysics and Machine Learning
Authors: Camporeale Enrico ,   The Scientific Organizing Committee of ML‐Helio
Published: January 2020

AbstractThe advancements and breakthroughs achieved in the last 5–10 years in Artificial Intelligence and machine learning (ML) have not gone unnoticed in the scientific community. The body of literature that borrows techniques from ML has steadily grown in all fields of physics. Space physics is particularly well posed to exploit ML due to the large amount of (often under scrutinized) data accumulated over the last few decades. Indeed, ML techniques can offer insights into the data that might enhance our understanding of physical mechanisms. Many of the pioneering studies on the use of ML in Space Physics have been led by several individuals who have independently taken the burden of moving out of their comfort zone to climb the steep slope of learning new jargon, new methodologies, and new coding skills. Such early adopters have recently convened in Amsterdam for the first conference on machine learning in heliophysics. The conference has laid the foundation for a new emerging community, and this commentary summarizes the discussions and steps taken to make such community flourish.
Square‐Root Variable Metric‐Based Nullspace Shuttle: A Characterization of the Nonuniqueness in Elastic Full‐Waveform Inversion
Authors: Liu Qiancheng , Peter Daniel 
Published: January 2020

AbstractFull‐waveform inversion (FWI) is for most geophysical applications an ill‐posed inverse problem, with nonunique solutions. We examine its nonuniqueness by exploring the nullspace shuttle, which can efficiently generate an ensemble of data fitting solutions. We construct this shuttle based on a quasi‐Newton method, the square‐root variable‐metric (SRVM) method. The latter provides access to the inverse data‐misfit Hessian in FWI for large‐scale applications. Combining the SRVM method with a randomized singular value decomposition, we obtain the eigenvector subspaces of the inverse data‐misfit Hessian. Its primary eigenvalue and eigenvector are considered to determine the null space of inversion result. Using the SRVM‐based nullspace shuttle, we can modify the inverted result a posteriori in a highly efficient manner without corrupting the data misfit. Also, because the SRVM method is embedded through elastic FWI, our method can be extended to multiparameter problems. We confirm and highlight our approach with the elastic Marmousi example.
Dynamical Ocean Response Controlling the Eastward Movement of a Heat Content Anomaly Caused by the 18.6‐Year Modulation of Localized Tidally Induced Mixing
Authors: Osafune S. , Kouketsu S. , Masuda S. , Sugiura N. 
Published: January 2020

AbstractNumerical experiments based on a long‐term ocean state estimate have been used in previous work to demonstrate that the 18.6‐year modulation of localized tidally induced vertical mixing can influence wintertime sea surface temperature (SST) over a broad area of the northern North Pacific, and may play a role in determining the spatial structure of the Pacific Decadal Oscillation (PDO). This study investigates the mechanism driving the model annual mean surface layer heat content anomaly (SHCa), which is correlated with the SST anomaly, at a location near the center of the PDO in the eastern Pacific. The modulation of mixing first induces an 18.6‐year oscillatory SHCa in the western boundary region, which moves eastward along the boundary between the subtropical and subarctic gyres, taking
10 years to reach the eastern region. Adjoint sensitivity analysis is applied to confirm the importance of the dynamical response of the ocean to the eastward motion of the SHCa. It is shown that the generation of a temperature anomaly by wave‐related current anomalies works to delay the eastward motion of the SHCa. Results also suggest that the generation of a spiciness anomaly in the open ocean may play a role. Although further studies are required to clarify whether the mixing modulation has an impact on the actual climate variability, the mechanism can be applied to any location along an eastward current, independent of the periodicity of the phenomena, and thus might have wide applicability in efforts to understand the role of the ocean in the climate system.
How Machine Learning and High‐Resolution Imagery Can Improve Melt Pond Retrieval From MODIS Over Current Spectral Unmixing Techniques
Authors: Wright Nicholas C. , Polashenski Chris M. 
Published: January 2020

AbstractMeltwater that pools on the surface of Arctic sea ice enhances solar absorption and accelerates further ice melt. The impact of melt ponds on energy absorption is controlled primarily through their influence on ice albedo, which is, in turn, governed in large part by the ponds' spatial coverage. This work seeks to observe the spatial coverage of melt ponds across the Arctic basin with sufficient accuracy to investigate pond‐albedo feedback and presents an improved technique to achieve this goal. We approach the problem by using the Open Source Sea Ice Processing algorithm to classify surface features in submeter resolution optical satellite imagery over select sites where such imagery is available. These data establish “true” estimates of pond coverage and the ponds' spectral reflectance. This information is then used to inform, improve, and test spectral unmixing and machine learning techniques that seek to determine melt pond coverage from more widely available, but lower resolution, optical satellite imagery (e.g., Moderate Resolution Imaging Spectroradiometer). The new machine learning approach improves accuracy from prior work and can contribute to improved efforts to validate melt pond models or understand trends in pond coverage. Nevertheless, we encounter and carefully document significant challenges to retrieving melt pond fractions from low‐resolution optical imagery. These limit accuracy to levels below that necessary for resolving climatologically important trends. We conclude that greatly expanding the collection of high‐resolution satellite imagery over sea ice is necessary to monitor melt pond coverage with the accuracy needed by the scientific community.