bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modest net autotrophy in the oligotrophic ocean
Authors: Letscher Robert T. , Moore J. Keith 
Published: April 2017

AbstractThe metabolic state of the oligotrophic subtropical ocean has long been debated. Net community production (NCP) represents the balance of autotrophic carbon fixation with heterotrophic respiration. Many in vitro NCP estimates based on oxygen incubation methods and the corresponding scaling relationships used to predict the ecosystem metabolic balance have suggested the ocean gyres to be net heterotrophic; however, all in situ NCP methods find net autotrophy. Reconciling net heterotrophy requires significant allochthonous inputs of organic carbon to the oligotrophic gyres to sustain a preponderance of respiration over in situ production. Here we use the first global ecosystem‐ocean circulation model that contains representation of the three allochthonous carbon sources to the open ocean, to show that the five oligotrophic gyres exhibit modest net autotrophy throughout the seasonal cycle. Annually integrated rates of NCP vary in the range ~1.5–2.2 mol O2 m−2 yr−1 across the five gyre systems; however, seasonal NCP rates are as low as ~1 ± 0.5 mmol O2 m−2 d−1 for the North Atlantic. Volumetric NCP rates are heterotrophic below the 10% light level; however, they become net autotrophic when integrated over the euphotic zone. Observational uncertainties when measuring these modest autotrophic NCP rates as well as the metabolic diversity encountered across space and time complicate the scaling up of in vitro measurements to the ecosystem scale and may partially explain the previous reports of net heterotrophy. The oligotrophic ocean is autotrophic at present; however, it could shift toward seasonal heterotrophy in the future as rising temperatures stimulate respiration.
Locating tremor using stacked products of correlations
Authors: Li Ka Lok , Sadeghisorkhani Hamzeh , Sgattoni Giulia , Gudmundsson Olafur , Roberts Roland 
Published: April 2017

AbstractWe introduce a back‐projection method to locate tremor sources using products of cross‐correlation envelopes of time series between seismic stations. For a given subset of n stations, we calculate the (n − 1)th‐order product of cross‐correlation envelopes and we stack the back‐projected products over combinations of station subsets. We show that compared to existing correlation methods and for realistic signal and noise characteristics, this way of combining information can significantly reduce the effects of correlated (spurious or irrelevant signals) and uncorrelated noise. Each back‐projected product constitutes an individual localized estimate of the source locations, as opposed to a hyperbola for the existing correlation techniques, assuming a uniform velocity in two dimensions. We demonstrate the method with synthetic examples and a real‐data example from tremor at Katla Volcano, Iceland, in July 2011. Despite very complex near‐surface structure, including strong topography and thick ice cover, the method appears to produce robust estimates of tremor location.
A directional model of tropospheric horizontal gradients in Global Positioning System and its application for particular weather scenarios
Authors: Masoumi Salim , McClusky Simon , Koulali Achraf , Tregoning Paul 
Published: April 2017

AbstractImproper modeling of horizontal tropospheric gradients in GPS analysis induces errors in estimated parameters, with the largest impact on heights and tropospheric zenith delays. The conventional two‐axis tilted plane model of horizontal gradients fails to provide an accurate representation of tropospheric gradients under weather conditions with asymmetric horizontal changes of refractivity. A new parametrization of tropospheric gradients whereby an arbitrary number of gradients are estimated as discrete directional wedges is shown via simulations to significantly improve the accuracy of recovered tropospheric zenith delays in asymmetric gradient scenarios. In a case study of an extreme rain event that occurred in September 2002 in southern France, the new directional parametrization is able to isolate the strong gradients in particular azimuths around the GPS stations consistent with the “V” shape spatial pattern of the observed precipitation. In another study of a network of GPS stations in the Sierra Nevada region where highly asymmetric tropospheric gradients are known to exist, the new directional model significantly improves the repeatabilities of the stations in asymmetric gradient situations while causing slightly degraded repeatabilities for the stations in normal symmetric gradient conditions. The average improvement over the entire network is ∼31%, while the improvement for one of the worst affected sites P631 is ∼49% (from 8.5 mm to 4.3 mm) in terms of weighted root‐mean‐square (WRMS) error and ∼82% (from −1.1 to −0.2) in terms of skewness. At the same station, the use of the directional model changes the estimates of zenith wet delay by 15 mm (∼25%).
Estimation of supraglacial debris thickness using a novel target decomposition on L‐band polarimetric SAR images in the Tianshan Mountains
Authors: Huang L. , Li Zh. , Tian B. S. , Han H. D. , Liu Y. Q. , Zhou J. M. , Chen Q. 
Published: April 2017

AbstractDebris is widely distributed in the ablation zones of mountain glaciers in the Tianshan Mountains. Supraglacial debris can accelerate or hamper glacier ablation, depending on its thickness. Thus, it plays an important role in the mass balance of debris‐covered glaciers. This paper proposes a novel method to estimate supraglacial debris thickness by using L‐band polarimetric synthetic aperture radar. A new model‐based target decomposition is used to extract the surface scattering, double bounce, and volume scattering components. The surface scatter model uses the extended Bragg scatter, which considers the depolarization effect for rough surfaces. The volume scatter model uses elliptical scatterers, which approximate the shape of the solids in the debris. The volume scattering power is related to the dielectric properties of the debris, the radar wavelength, the incidence angle, and the elliptical scatter shape. Once the target decomposition is performed, the debris thickness can be inverted from the volume scattering power and other known parameters. Through comparison with a large number of field measurements, the inversion is shown to be reasonable, and the accuracy is validated to be ±0.12 m. Based on the inversion map in the study area, the debris thicknesses of the Koxkar glacier and its neighboring glaciers are presented and analyzed.
Rupture characteristics of the 2016 Meinong earthquake revealed by the back projection and directivity analysis of teleseismic broadband waveforms
Authors: Jian Pei‐Ru , Hung Shu‐Huei , Meng Lingsen , Sun Daoyuan 
Published: April 2017

AbstractThe 2016 Mw 6.4 Meinong earthquake struck a previously unrecognized fault zone in midcrust beneath south Taiwan and inflicted heavy causalities in the populated Tainan City about 30 km northwest of the epicenter. Because of its relatively short rupture duration and P wave trains contaminated by large‐amplitude depth phases and reverberations generated in the source region, accurate characterization of the rupture process and source properties for such a shallow strong earthquake remains challenging. Here we present a first high‐resolution MUltiple SIgnal Classification back projection source image by using both P and depth‐phase sP waves recorded at two large and dense arrays to understand the source behavior and consequent hazards of this peculiar catastrophic event. The results further corroborated by the directivity analysis indicate a unilateral rupture propagating northwestward and slightly downward on the shallow NE‐dipping fault plane. The source radiation process is primarily characterized by one single peak, ~7 s duration, with a total rupture length of ~17 km and average rupture speed of 2.4 km/s. The rupture terminated immediately east of the prominent off‐fault aftershock cluster about 20 km northwest of the hypocenter. Synergistic amplification of ground shaking by the directivity and strong excitation of sP and reverberations mainly caused the destruction concentrated in the area further to the northwest away from the rupture zone.
Identify the nonlinear wave‐particle interaction regime in rising tone chorus generation
Authors: Tao Xin , Zonca Fulvio , Chen Liu 
Published: April 2017

AbstractNonlinear wave‐particle interaction during chorus wave generation was assumed to be in the adiabatic regime in previous studies, i.e., the particle phase‐space trapping timescale (τtr) is considered to be much smaller than the nonlinear dynamics timescale τNL. In this work, we use particle‐in‐cell simulations to demonstrate that τtr∼τNL, i.e., the interaction regime during chorus generation is in the nonadiabatic regime. The timescale for nonlinear evolution of resonant particle phase‐space structures is determined by making the time‐averaged power exchange plot, which clearly demonstrates that particles with pitch angle near 80° make the most significant contribution to wave growth. The phase‐space trapping timescale is also comparable to the amplitude modulation timescale of chorus, suggesting that chorus subpackets are formed because of the self‐consistent evolution of resonant particle phase‐space structures and spatiotemporal features of the fluctuation spectrum.
Integrating GPS with GLONASS for high‐rate seismogeodesy
Authors: Geng Jianghui , Jiang Peng , Liu Jingnan 
Published: April 2017

AbstractHigh‐rate GPS is a precious seismogeodetic tool to capture coseismic displacements unambiguously and usually improved by sidereal filtering to mitigate multipath effects dominating the periods of tens of seconds to minutes. We further introduced GLONASS (Globalnaya navigatsionnaya sputnikovaya sistema) data into high‐rate GPS to deliver over 2000 24 h displacements at 99 stations in Europe. We find that the major displacement errors induced by orbits and atmosphere on the low‐frequency band that are not characterized by sidereal repeatabilities can be amplified markedly by up to 40% after GPS sidereal filtering. In contrast, integration with GLONASS can reduce the noise of high‐rate GPS significantly and near uniformly over the entire frequency band, especially for the north components by up to 40%, suggesting that this integration is able to mitigate more errors than only multipath within high‐rate GPS. Integrating GPS with GLONASS outperforms GPS sidereal filtering substantially in ameliorating displacement noise by up to 60% over a wide frequency band (e.g., 2 s–0.5 days) except a minor portion between 100 and 1000 s. High‐rate multi‐GNSS (Global Navigation Satellite System) can be enhanced further by sidereal filtering, which should however be carefully implemented to avoid adverse complications of the noise spectrum of displacements.
The extreme El Niño of 2015–2016 and the end of global warming hiatus
Authors: Hu Shineng , Fedorov Alexey V. 
Published: April 2017

AbstractSlower rates of increase in global mean surface temperature (GMST) after 2000, dubbed “global warming hiatus,” recently gave way to a rapid temperature rise. This rise coincided with persistent warm conditions in the equatorial Pacific between March 2014 and May 2016, which peaked as the 2015 extreme El Niño. Here we show that the El Niño–Southern Oscillation (ENSO) tightly controls interannual variations in atmospheric heating rate in the tropics (r > 0.9), allowing us to construct a simple, physically based model of GMST variations that incorporates greenhouse gas emissions, ENSO forcing, and stratospheric sulfate aerosols produced by volcanoes. The model closely reproduces GMST changes since 1880, including the global warming hiatus and the subsequent temperature rise. Our results confirm that weak El Niño activity, rather than volcanic eruptions, was the cause of the hiatus, while the rapid temperature rise is due to atmospheric heat release during 2014–2016 El Niño conditions concurrent with the continuing global warming trend.
Structural changes and anomalous self‐diffusion of oxygen in liquid iron at high pressure
Authors: Posner Esther S. , Steinle‐Neumann Gerd , Vlček Vojtěch , Rubie David C. 
Published: April 2017

AbstractWe report structural properties and diffusivity of liquid Fe0.96O0.04 over a density range of 5.421–11.620 g cm−3, corresponding to pressures of 0–330 GPa and 2200–5500 K, using first‐principles molecular dynamics. We predict a change in compression mechanism near 8 g cm−3. At lower density, Fe and O coordinations increase from ~10 to ~13 and ~3 to ~6, respectively, the average Fe–O distance increases from ~1.81 Å to ~1.88 Å, and the Fe–Fe distance remains essentially constant. Calculated oxygen diffusivities, DO, remain constant over the corresponding pressure range, consistent with experiments. For larger densities, interatomic distances and diffusion rates for both species decrease monotonically. Oxygen coordination reaches a maximum of ~8.5 at ~9.4 g cm−3, indicating a local B2 packing for Fe around O under conditions of the Earth's core. The pressure‐induced structural evolution provides an explanation for a previously reported change in pressure dependence of oxygen solubility in liquid iron.
Shallow episodic tremor near the Nankai Trough axis off southeast Mie prefecture, Japan
Authors: Annoura Satoshi , Hashimoto Tetsuo , Kamaya Noriko , Katsumata Akio 
Published: April 2017

AbstractWe analyzed long‐term continuous seismic records (from September 2015 to April 2016) of Dense Ocean‐floor Network System for Earthquake and Tsunamis, an ocean‐floor observation system deployed around the fore‐arc slope of the Nankai subduction zone to investigate shallow tremor near the trough axis. We found that the activity of shallow tremor was concentrated in two time periods: 6 days in October 2015 and 2 weeks in April 2016. During the episode in April 2016, migration and triggering of tremor were observed. These characteristics are similar to those of tremor in the deeper part of the subduction zone. The triggering of tremor indicates that the tremor activity is very sensitive to nearby stress perturbation in the area of this study, which is near the initiation points of past large earthquakes along the Nankai Trough. Therefore, it is very important to monitor tremor activity in this region for understanding the stress accumulation process of megathrust earthquakes.
Assessing recent declines in Upper Rio Grande runoff efficiency from a paleoclimate perspective
Authors: Lehner Flavio , Wahl Eugene R. , Wood Andrew W. , Blatchford Douglas B. , Llewellyn Dagmar 
Published: April 2017

AbstractRecent decades have seen strong trends in hydroclimate over the American Southwest, with major river basins such as the Rio Grande exhibiting intermittent drought and declining runoff efficiencies. The extent to which these observed trends are exceptional has implications for current water management and seasonal streamflow forecasting practices. We present a new reconstruction of runoff ratio for the Upper Rio Grande basin back to 1571 C.E., which provides evidence that the declining trend in runoff ratio from the 1980s to present day is unprecedented in context of the last 445 years. Though runoff ratio is found to vary primarily in proportion to precipitation, the reconstructions suggest a secondary influence of temperature. In years of low precipitation, very low runoff ratios are made 2.5–3 times more likely by high temperatures. This temperature sensitivity appears to have strengthened in recent decades, implying future water management vulnerability should recent warming trends in the region continue.
New estimate of the current rate of sea level rise from a sea level budget approach
Authors: Dieng H. B. , Cazenave A. , Meyssignac B. , Ablain M. 
Published: April 2017

AbstractWe revisit the global mean sea level (GMSL) budget during the whole altimetry era (January 1993 to December 2015) using a large number of data sets. The budget approach allows quantifying the TOPEX A altimeter drift (amounting 1.5 ± 0.5 mm/yr over 1993–1998). Accounting for this correction and using ensemble means for the GMSL and components lead to closure of the sea level budget (trend of the residual time series being 0.0 ± 0.22 mm/yr). The new GMSL rate over January 1993 to December 2015 is now close to 3.0 mm/yr. An important increase of the GMSL rate, of 0.8 mm/yr, is found during the second half of the altimetry era (2004–2015) compared to the 1993–2004 time span, mostly due to Greenland mass loss increase and also to slight increase of all other components of the budget.
Fueguian crania and the circum‐Pacific rim variation
Authors: Turbon D. , Arenas C. , Cuadras C. M. 
Published: April 2017

AbstractObjectivesThe Fueguians are descendants of the first settlers of America, a 'relict' isolated geographically for 10,000 years. We compared their cranial variation with other Americans, and samples from Asia and Australia to know whether the modern extinct Fueguians can be considered Paleoamericans or not.Materials and MethodsHerein we study 176 Fuego‐Patagonian skulls, the largest cranial sample to be studied, refined and well documented, using CVA, and the D2 of Mahalanobis. The affinities between populations and sexual dimorphism were jointly studied.ResultsTerrestrial hunters (Selknam) have a different cranial morphology from sea canoeists (Yamana, Alakaluf) particularly with regard to cranial size and robustness. In the American context, there are extreme differences between the canoeists of Santa Cruz (California) and the Eskimos and canoeists of Fuego‐Patagonia in terms of cranial size, prognathism and development of the frontal region. Fueguian canoeists are cranially closer to the Californian ones than to their Fueguian neighbors, the Selknam. Our results favor the hypothesis of two different flows for the origin of the first populators of Tierra del Fuego.DiscussionWe concluded that the robusticity of some Fuegians (Selknam) might be the result of an allometric pattern of overall robusticity expression well as a result of epigenetics or differential reproduction (Larsen, 2015:264) or hypothetical endocrine changes (Bernal et al. in Am J Hum Biol 2006;18:748–765). When compared with three Australian–Melanesian series, the group comprising Amerindians, Ainu, and Eskimos clusters together as they are all extremely different from the former in terms of both cranial size and shape.
Performance review of regional emergency medical service pre‐arrival cardiopulmonary resuscitation with or without dispatcher instruction: a population‐based observational study
Authors: Fukushima Hidetada , Kawai Yasuyuki , Asai Hideki , Seki Tadahiko , Norimoto Kazunobu , Urisono Yasuyuki , Okuchi Kazuo 
Published: April 2017

BackgroundTo investigate variations in emergency medical service (EMS) pre‐arrival cardiopulmonary resuscitation (CPR), including both bystander CPR without dispatch assistance and dispatch‐assisted CPR (DACPR).MethodsWe carried out an observational study by implementing EMS pre‐arrival CPR reports in three fire agencies. We included adult, non‐traumatic, and non‐EMS witnessed out‐of‐hospital cardiac arrests. This reporting system comprised the dispatch instruction process and bystander CPR quality based on evaluations by EMS crews who arrived on the scene. Bystander CPR was categorized as “ongoing CPR” if the bystander was performing CPR when the EMS reached the patient's side and “good‐quality CPR” if the CPR was performed proficiently. We compared the frequencies of ongoing and good‐quality CPR in the bystander CPR already started without dispatch assistance (CPR in progress) group and DACPR group.ResultsOf 688 out‐of‐hospital cardiac arrests, CPR was already started in 150 cases (CPR in progress group). Dispatcher CPR instruction was provided in 368 cases. Among these, callers started chest compressions in 162 cases (DACPR group). Ongoing CPR was performed in 220 cases and was more frequent in the DACPR group (128/162 [79.0%] versus 92/150 [61.3%], P < 0.001). Good‐quality CPR was more frequent in the CPR in progress group, but the difference was not statistically significant (36/92 [39.1%] versus 42/128 [29.0%], P = 0.888).ConclusionsOngoing CPR and good‐quality CPR were not frequent in EMS pre‐arrival CPR. Detailed analysis of dispatch instructions and bystander CPR can contribute to improvement in EMS pre‐arrival CPR.
Schwache Wechselwirkungen unter Druck: hp‐CuBi und seine Analoga
Authors: Guo Kai , Akselrud Lev , Bobnar Matej , Burkhardt Ulrich , Schmidt Marcus , Zhao Jing‐Tai , Schwarz Ulrich , Grin Yuri 
Published: April 2017

AbstractDie metastabile binäre Verbindung hp‐CuBi wurde durch direkte chemische Reaktion von Kupfer und Bismut bei einem Druck von 5 GPa und einer Temperatur von 720 K hergestellt. Die Atomanordnung besteht aus Schichtsegmenten, in denen gewellte Cu‐Ebenen zwischen planaren Bi‐Schichten eingebettet sind. Berechnete QTAIM‐Ladungen für Übergangsmetallverbindungen von Bismut zeigen im Fall von hp‐CuBi nur geringfügigen Ladungstransfer. Die Analyse der chemischen Bindung mit Ortsraumtechniken offenbart Mehrzentrenwechselwirkungen innerhalb der Bi‐Cu‐Bi‐Schichten und Van‐der‐Waals‐Wechselwirkungen der freien Elektronenpaare zwischen diesen Einheiten. hp‐CuBi zeigt metallartige elektrische Leitfähigkeit und Einsetzen von Supraleitung bei Tc=1.3 K.
Mixed‐Matrix‐Membranen
Authors: Dechnik Janina , Gascon Jorge , Doonan Christian J. , Janiak Christoph , Sumby Christopher J. 
Published: April 2017

AbstractDie Forschung zu ausgedehnten porösen Materialien wie Metall‐organischen und porösen organischen Gerüstverbindungen (MOFs und POFs) sowie den analogen Metall‐organischen Polyedern (MOPs) und porösen organischen Käfigen (POCs) hat sich im letzten Jahrzehnt stark entwickelt. Mit ihrer chemischen und strukturellen Vielfalt und bemerkenswerten Porosität wurden MOFs als neue Adsorbentien für industrielle Gastrennungen und als vielversprechende Füllstoffkomponenten für leistungsstarke gemischt(Mixed)‐Matrix‐Membranen (MMMs) vorgeschlagen. Die Forschung in diesem Bereich konzentrierte sich auf die Verbesserung der chemischen Kompatibilität der MOFs mit der Polymerphase durch sinnvolle Funktionalisierung der organischen MOF‐Linker, auf die Modifizierung der MOF‐Oberflächenchemie und in jüngster Zeit auf Untersuchungen, wie Partikelgröße, ‐morphologie und ‐verteilung die Trennleistung erhöhen. Andere Füllstoffmaterialien, wie POFs, MOPs und POCs, werden ebenfalls als Additive für MMMs untersucht und zeigen eine bemerkenswerte Wirkung gegen Polymeralterung und ausgezeichnete chemische Kompatibilität mit handelsüblichen Polymeren. Dieser Aufsatz gibt einen Überblick zum Stand der Technik im MOF‐MMM‐Aufbau und zu aktuellen Anwendungen von porösen organischen Gerüsten und molekularen Additiven für MMMs.
Ruthenium(II)‐Catalyzed C−C Arylations and Alkylations: Decarbamoylative C−C Functionalizations
Authors: Moselage Marc , Li Jie , Kramm Frederik , Ackermann Lutz 
Published: April 2017

AbstractRuthenium(II)biscarboxylate catalysis enabled selective C−C functionalizations by means of decarbamoylative C−C arylations. The versatility of the ruthenium(II) catalysis was reflected by widely applicable C−C arylations and C−C alkylations of aryl amides, as well as acids with modifiable pyrazoles, through facile organometallic C−C activation.