bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Devonian volcanics of southeastern Gorny Altai: geochemistry, isotope (Sr, Nd, and O) composition, and petrogenesis (Aksai complex)
Authors: Krupchatnikov V.I. , Vrublevskii V.V. , Kruk N.N.
Published: August 2018

Geological, geochemical, and isotope (Sr, Nd, and O) parameters of Early Devonian (405 Ma) volcanics of southeastern Gorny Altai (Aksai and Kalguty volcanotectonic structures) are discussed. The studied igneous rock association comprises magnesian andesitoids, Nb-enriched andesite basalts, and A-type peraluminous silicic rocks (dacites, rhyolites, granites, and leucogranites). Magnesian andesitoids (mg# > 50) are characterized by a predominance of Na among alkalies (K2O/Na2O ≈ 0.1–0.7), medium contents of TiO2 (~0.8–1.3 wt.%) and Al2O3 (~12–15 wt.%), enrichment in Cr (up to 216 ppm), and low Sr/Y ratios (4–15). The Nb-enriched (Nb = 10–17 ppm) andesite basalts have high contents of TiO2 (1.7–2.7 wt.%) and P2O5 (0.4–1.4 wt.%). The A-type granitoids are characterized by high contents of K(K2O/Na2O ≤ 60) and alumina (ASI ≤ 2.9) and depletion in Ba, Sr, P, and Ti. The magnesian andesitoids and Nb-enriched andesite basalts are products of melts generated in the metasomatized lithospheric mantle; silicic magmas were formed through the melting of Cambrian–Ordovician metaturbidites of the Gorny Altai Group and, partly, Early–Middle Cambrian island-arc metabasites. The above rock association might have resulted from a plume impact on the lithospheric substrates of the continental paleomargin during the evolution of the Altai–Sayan rift system.
Hydrocarbons occluded by asphaltenes
Authors: Kashirtsev V.A.
Published: August 2018

Homologous series of n-alkenes and dimethylalkanes with the odd or even number of carbon atoms in the molecule have been identified in chloroform extracts from the organic matter of Upper Paleozoic deposits of the Vilyui syneclise penetrated by the superdeep well SV-27 at depths below 5 km. It is presumed that these unusual hydrocarbons resulted from the destruction of asphaltene occlusions under severe P–T conditions at great depths and that the hydrocarbon generation began in the zone of postdiagenetic transformations of sediments. This hypothesis was tested in the sections of deposits whose organic matter underwent catagenesis of different grades. On the basis of these results, zones of emergence, transition, and destruction of occlusions have been recognized.
Noble metals in black shales of the Sukhoi Log gold deposit (East Siberia): evidence from scintillation arc atomic-emission spectrometry
Authors: Vasil’eva I.E. , Shabanova E.V. , Goryacheva E.M. , Sotskaya O.T. , Labusov V.A. , Nekludov O.A. , Dzyuba A.A.
Published: August 2018

Scintillation arc atomic-emission spectrometry (SAES) is used to study noble metals (NM), including Au, Ag, Pt, Pd, Ir, Os, Rh, and Ru, in black shales of the Sukhoi Log gold deposit (Irkutsk Region, Russia), with a focus on NM total contents in samples and on the compositions and sizes of NM-bearing particles. The estimated sizes of gold particles and their distribution are confirmed by results of scanning electron microscopy combined with energy dispersive X-ray microanalysis (SEM-EDX). The SAES results are in satisfactory agreement with earlier SEM-EDX data on NM species but reveal a much greater number and diversity of element associations.
Features of magmatim-related metallogeny of Gorny Altai and Rudny Altai (Russia)
Authors: Gaskov I.V.
Published: August 2018

The Rudny Altai and Gorny Altai regions had different geologic histories and differ in metallogenic patterns. The Vendian–Early Cambrian to Permian–Triassic multistage evolution of Gorny Altai included subduction, accretion–collision, and rifting events accompanied by magmatism and related mineralization. Metallogeny evolved in discrete pulses, with especially abundant Late Paleozoic–earliest Mesozoic mineralization. The Devonian–Carboniferous pulse produced diverse mineral deposits (iron, mercury, gold, silver, molybdenum, tungsten, cobalt, polymetallic ores, and rare earths), some of considerable economic value. The territory of Gorny Altai includes several large ore districts that belong to different zones. They are the Beloretsk–Kholzun iron district in the west, the Kayancha–Sinyukha fluorine–gold district in the northeast, the Kurai gold–mercury and Yustyd rare-metal–silver districts in the southeast, and the Kalguty rare-metal–tungsten and Ulandryk U–REE–Cu districts in the south. The largest mineral deposits are Kholzun (Fe, P2O5), Karakul (Co, Bi), Sinyukha (Au), Aktash and Chagan-Uzun (Hg), Ozernoe and Pogranichnoe (Ag), Kalguty (Mo, W), Alakha (Li, Ta), Rudnyi Log (Y,Fe-specularite), and Urzarsai (W-scheelite). Mineralization in Rudny Altai is mainly pyritic: copper–pyrite, pyrite–polymelallic ore, and barite–polymelallic ore. It resides in suprasubduction basalts and rhyolites and in Emsian to Frasnian island-arc volcanics at different stratigraphic levels of Devonian volcanosedimentary sequences in six ore districts. The Kurchum high-grade metamorphic block hosts copper–pyrite and gold–quartz mineralization related to Hercynian volcanism.
First results of GPS measurements on the Ulaanbaatar geodynamic testing area
Authors: Miroshnichenko A.I. , Radziminovich N.A. , Lukhnev A.V. , Zuev F.L. , Demberel S. , Erdenezul D. , Ulziibat M.
Published: August 2018

First results of the analysis of GPS measurement data obtained from 18 sites of two local networks in the vicinity of Ulaanbaatar (Mongolia) for the period 2010–2015 have been presented. Horizontal velocity vectors are consistent with each other in the ITRF2014 system and with the velocities of the IGS permanent station ULAB. The sites move in the E–SE direction at a rate of 25–30 mm/yr, with the displacement azimuth averaging 105°. With respect to Eurasia, the vectors for most of the sites are slighly turned to the south, but they are still of SE orientation with the azimuth range of 130°–150° and magnitude values of 2–4 mm/yr. Relative horizontal velocities tend to decrease towards southeast that determines a zonal distribution of different type of relative strain patterns. The western part of the Ulaanbaatar network is characterized by the W–E oriented extension with the elongation rate ε1 = 12–16 × 10–8 yr–1. The shortening NW–SE trending strain with calculated value ε2 = 22.4 × 10–8 yr–1 characterizes the network’s eastern part. The highest values of the maximum shear strains (εmax = 10–14 × 10–8 yr–1) form an extended area in the center of the testing ground, which is elongated in the northeastern direction, conformably with the strike of the major geologic structures. The strain distribution pattern of the Emeelt network located within the eponymous seismogenic structures is characterized by the crustal elongation (5 × 10–6 yr–1) trending SE–NW and less pronounced shortening in the SW–SE directions.

The axial part of the fault crossing the network in the NW direction exhibits maximum deformations.
The shape evolution of liquid droplets in miscible environments
Authors: Walls Daniel J. , Meiburg Eckart , Fuller Gerald G.
Published: August 2018

Miscible liquids often come into contact with one another in natural and technological situations, commonly as a drop of one liquid present in a second, miscible liquid. The shape of a liquid droplet present in a miscible environment evolves spontaneously in time, in a distinctly different fashion than drops present in immiscible environments, which have been reported previously. We consider drops of two classical types, pendant and sessile, in building upon our prior work with miscible systems. Here we present experimental findings of the shape evolution of pendant drops along with an expanded study of the spreading of sessile drops in miscible environments. We develop scalings considering the diffusion of mass to group volumetric data of the evolving pendant drops and the diffusion of momentum to group leading-edge radial data of the spreading sessile drops. These treatments are effective in obtaining single responses for the measurements of each type of droplet, where the volume of a pendant drop diminishes exponentially in time and the leading-edge radius of a sessile drop grows following a power law of $t^{1/2}$ at long times. A complementary numerical approach to compute the concentration and velocity fields of these systems using a simplified set of governing equations is paired with our experimental findings.
TEST MAP AND DISCRETENESS IN SL(2, ℍ)
Authors: GONGOPADHYAY KRISHNENDU , MUKHERJEE ABHISHEK , SARDAR SUJIT KUMAR
Published: August 2018

Let ℍ be the division ring of real quaternions. Let SL(2, ℍ) be the group of 2 × 2 quaternionic matrices $A={\scriptsize{(\begin{array}{l@{\quad}l} a & b \\ c & d \end{array})}}$ with quaternionic determinant det A = |ad − aca−1b| = 1. This group acts by the orientation-preserving isometries of the five-dimensional real hyperbolic space. We obtain discreteness criteria for Zariski-dense subgroups of SL(2, ℍ).
Sliding mode nonlinear disturbance observer-based adaptive back-stepping control of a humanoid robotic dual manipulator
Authors: Bai Keqiang , Gong Xuantao , Chen Sihai , Wang Yingtong , Liu Zhigui
Published: August 2018

An adaptive back-stepping sliding mode controller (ABSMC) algorithm was developed for nonlinear uncertain systems based on a nonlinear disturbance observer (NDO). The developed ABSMC was applied to attitude control for the dual arm of a humanoid robot. Considering the system uncertainty and the unknown external disturbances, the ABSMC scheme was designed to eliminate the chattering phenomenon in the traditional sliding mode control and to reduce the tracking error closer to zero. The ABSMC algorithm solved problems related to the chattering of the system for both uncertainties and disturbances in the humanoid robotic system with an NDO in a two-dimensional environment. The algorithm was designed to work equally well with agents, with higher degrees of freedom in different applications. The method was appropriate for improving tracking performance. The ABSMC algorithm guaranteed global stability and improved the dynamic performance of the system. The algorithm inherited a low computational cost, probabilistic completeness, and asymptotic optimality from the fuzzy sliding mode control. This algorithm has a practical application in the dual arm of a humanoid robot with a circular trajectory. This paper showed the effectiveness and applicability of the proposed methods, which reduced the output of the controller and improved the control performance of the humanoid robotic system. The new combined control algorithm, ABSMC, was able to feasibly and efficiently weaken the chattering on the robot's closed-loop paths, starting and finishing at the same configuration.
New therapeutic patents used for the treatment of leprosy: a review
Authors: Gomes Lima Santos Nayara , Perez Pereira Ramos Karen , Shanmugam Saravanan , Oliveira de Carvalho Fernanda , Garcez Barreto Teixeira Luciana , Ramos Silva Érika , de Vasconcelos Cerqueira-Braz Juliana , Santos Nunes Paula , Antunes de Souza Araújo Adriano
Published: August 2018

Leprosy is a granulomatous disease, infectious and transmissible, which affects the skin and peripheral nerves, havingMycobacterium lepraeas causative agent. The manifestation of this disease causes cutaneous lesions, peripheral neuropathies and, in more extreme cases, may generate deformities and disabilities in affected individuals. Patents were identified using the descriptor ‘leprosy’ and code A61K of the international patent classification, which indicates only products that meet human needs. The analysis was made using theWIPO,ESPACENETandUSPTOdatabases, until the month of September 2016. Through this review, we found a variety of in vitro, pre-clinical and clinical studies relating to the treatment of leprosy with different types of compounds and forms of administration. New treatment proposals should include pain reduction capabilities, prevention or limitation of the appearance of cutaneous lesions, as well as prevention of the progression of the disease to more severe stages that may lead to loss of function or potentiate the individual's immune response to theM. lepraebacillus in order to prevent bacterial spread. We concluded that any patents developed with natural products were not found in the treatment of leprosy. All the deposited products were synthetic origin, mostly tested in humans and of varied forms of administration.
Archaeological Demography as a Tool for the Study of Women and Gender in the Past
Authors: French Jennifer C.
Published: August 2018

In the last 20 years, demography has re-emerged as a key research area within archaeology. This research has refined archaeological demographic methods and examined the relationships between demographic, cultural and environmental change. Here, I discuss how the results of the growing corpus of archaeological demographic studies can contribute to gender archaeology, aiding the incorporation of women into narratives of the past. By considering the important role of women in the demographic regimes of small-scale societies, I explain how archaeological demography can provide insights into the behaviour and lives of women, without relying on the often problematic identification of gendered artefacts, activities and/or places. Archaeological demography as a tool for gender archaeology also permits a move away from the female empiricism of simply adding women into archaeological narratives, to provide an alternative framework for the analysis of gender roles and practices. I demonstrate the feasibility and benefits of this approach using an example from the Upper Palaeolithic of southwestern France.
Social values and institutional change: an experimental study
Authors: GËRXHANI KLARITA , VAN BREEMEN JACQUELINE
Published: August 2018

We experimentally investigate whether and how individuals change formal institutions governing an organization. The focus is on formal rules prescribing individual cooperation to achieve a collective goal. Our analysis accounts for the role of social norms and individuals’ social values. We observe that prosocial individuals –who value cooperation and have a conflict between this value and existing rules allowing for low cooperation– attempt to change this rule. In line with our theoretical discussion, we also find that prosocial individuals first try to change the institutional environment by changing social norms. If this fails, these individuals change formal rules directly.
Frequency reconfigurable antenna for cognitive radios with sequential UWB mode of perception and multiband mode of operation
Authors: Mansoul Ali , Ghanem Farid
Published: August 2018

In this work, an UWB/narrow band reconfigurable elliptical-shaped monopole antenna for cognitive radio applications with sequential perception and operation modes is presented. The proposed approach consists in integrating a reconfigurable filter, in an UWB antenna ground plan, by the mean of four horizontal slots and integrated switches that allow inserting/removing/varying zeros and poles in the frequency response. By acting on the slot lengths in order to alter their resonance frequencies, the different switch configurations allow the antenna to switch between an UWB mode that could be used for the perception (sensing) and different narrowband modes, mono-band and dual-band, that could be used for the operation at 2.4 or/and 3.5 GHz. To validate the concept, an experimental prototype has been fabricated and a good agreement between the simulated and the measured S-parameters has been obtained. While the presented work uses the presence/absence of a perfect conductive strip (PEC) to model real switch operation, it is believed that the obtained results conjugated with previous work using real switches on a very similar structure allows validating approach.
Novel dual band patch antenna With Gap coupled composite right/left-handed transmission line
Authors: Ahmed Z. , Ahmed M. M. , Ihsan M. B. , Chaudhary A. A. , Arif J. K.
Published: August 2018

A novel low profile dual band patch antenna is presented. It consists of a composite right/left-handed transmission line (CRLH TL) unit cell gap coupled with the radiating edge of a rectangular patch antenna. The dual band behavior is achieved by coupling the zeroth order resonance mode of CRLH TL and TM10 mode of the patch antenna. It is shown that frequency ratio can be changed by varying the gap between the patch and CRLH TL unit cell. The proposed configuration enables frequency reconfigurability by changing the CRLH TL unit cell using a switch. A prototype of the antenna having frequency ratio f2/f1 = 1.08 is designed and fabricated. The proposed antenna shows measured S11 ≤ −10 dB bandwidth of 100 and 50 MHz at resonance frequencies of f1 = 4.84 and f2 = 5.22 GHz, respectively. A 2 × 2 dual band CRLH TL coupled patch array is also presented, showing more than 12.7 dBi gain at both resonance frequencies.
Fallbericht einer 15-jährigen Patientin mit einer schweren wahnhaften Depression, behandelt mit Elektrokonvulsionstherapie
Authors: Reinhardt Martin , Wunsch Katja , Weirich Steffen , Häßler Frank , Buchmann Johannes
Published: August 2018

Zusammenfassung. Fragestellung: Die Elektrokonvulsionstherapie (EKT) ist ein modernes Therapieverfahren für schwere psychiatrische Erkrankungen. Die EKT findet jedoch nur selten Anwendung bei Kindern und Jugendlichen. Dieser Fallbericht handelt von der Anwendung der EKT bei einer 15-jährigen Patientin mit einer schweren depressiven Episode mit psychotischen Symptomen. Methodik: Nach erfolgloser kombinierter verhaltenstherapeutischer und medikamentöser Behandlung erhielt die Patientin insgesamt 11 EKT-Behandlungen mit rechts unilateraler Elektrodenplatzierung. Vor, während und nach dem Behandlungszeitraum wurde mittels Eigen- (BDI-II) und Fremdurteil (HDRS21) das Ausmaß der Depressivität bestimmt. Ergebnisse: Klinisch konnte ein schneller und deutlicher Rückgang der depressiven Symptomatik festgestellt werden. Schlussfolgerungen: Der Einsatz einer EKT sollte im Rahmen eines Gesamtbehandlungskonzepts für schwere psychiatrische Störungen bei Kindern und Jugendlichen frühzeitig erwogen werden.
Diagnostik des psychosozialen und kognitiven Entwicklungsstandes bei Intelligenzminderung im Kindes- und Jugendalter
Authors: Neumann Frederike , Nestler Judith , Lührs da Silva Claudia , Allroggen Marc
Published: August 2018

Zusammenfassung. Die Diagnostik der kognitiven Einschränkung und damit verbundener Auffälligkeiten der sozialen Entwicklung im Kindes- und Jugendalter ist essenziell für die weitere Förderung, aber auch für die Behandlungsplanung bei komorbid vorliegenden psychischen Störungen. Dieser komplexe Prozess sollte auf mehreren Ebenen mit unterschiedlichen Methoden erfolgen. Die daraus resultierende praxisrelevante Frage ist, welche Vor- und Nachteile aktuelle Verfahren zur Erfassung des psychosozialen und kognitiven Entwicklungsstandes von Kindern und Jugendlichen mit Intelligenzminderung aufweisen. Die onlinebasierte systematische Literaturrecherche in einschlägigen Datenbanken zu dieser Frage ergab 3 324 Artikel. Nach Überprüfen der Ausschlusskriterien im Volltext ergaben sich 30 Verfahren. 24 konnten der Kategorie „Entwicklungs- und Intelligenztests“ und sechs der Kategorie „Fremd- und Selbstbeurteilungsverfahren“ zugeordnet werden. Es wird deutlich, dass die Mehrheit der Verfahren für normalintelligente Kinder und Jugendliche normiert wurde bzw. nur ungenaue Informationen zur Beteiligung von Kindern und Jugendlichen mit Intelligenzminderung an der Normierungsstichprobe gegeben werden. Damit einher gehen Gütekriterien, die nicht unter Berücksichtigung der Bedarfe von Personen mit Intelligenzminderung überprüft wurden. Trotz der unbefriedigenden aktuellen Lage besteht die Nachfrage an Diagnostik des psychosozialen und kognitiven Entwicklungsstandes für Kinder und Jugendliche mit Intelligenzminderung. Aktuell empfehlen sich KABC-II und ADOS-2 als Testbatterien in Kombination mit den Fremdbeurteilungsverfahren ADI-R, VFE und SRS.
Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate‐Based Standardization
Authors: Bernasconi Stefano M. , Müller Inigo A. , Bergmann Kristin D. , Breitenbach Sebastian F. M. , Fernandez Alvaro , Hodell David A. , Jaggi Madalina , Meckler Anna Nele , Millan Isabel , Ziegler Martin
Published: August 2018

About a decade after its introduction, the field of carbonate clumped isotope thermometry is rapidly expanding because of the large number of possible applications and its potential to solve long‐standing questions in Earth Sciences. Major factors limiting the application of this method are the very high analytical precision required for meaningful interpretations, the relatively complex sample preparation procedures, and the mass spectrometric corrections needed. In this paper we first briefly review the evolution of the analytical and standardization procedures and discuss the major remaining sources of uncertainty. We propose that the use of carbonate standards to project the results to the carbon dioxide equilibrium scale can improve interlaboratory data comparability and help to solve long‐standing discrepancies between laboratories and temperature calibrations. The use of carbonates reduces uncertainties related to gas preparation and cleaning procedures and ensures equal treatment of samples and standards. We present a set of carbonate standards of diverse composition, discuss how they can be used to correct for mass spectrometric biases, and demonstrate that their use significantly improves the comparability among four laboratories. We propose that the use of these standards or of a similar set of carbonate standards will improve the comparability of data across laboratories.
CCN Spectral Shape and Stratus Cloud and Drizzle Microphysics
Authors: Hudson James G. , Noble Stephen , Tabor Samantha
Published: August 2018

The shapes of high‐resolution cloud condensation nucleus (CCN) spectra are compared with cloud and precipitation characteristics observed in the Marine Stratus/Stratocumulus Experiment. These high‐resolution spectra often revealed bimodality that is usually caused by in‐cloud processing. Bimodal CCN spectra were associated with clouds that had as much as double the concentrations of droplets with narrower distributions and as much as an order of magnitude less drizzle than clouds associated with the most extreme unimodal CCN spectra. We introduce objective CCN spectral metrics: (1) CCN concentration differences between the two modes, unprocessed (Aitken, Nu) and processed (accumulation, Np), and (2) slopes of cumulative CCN spectra. Both of these CCN spectral shape classifications show similar cloud droplet concentration (Nc) trends to that of an earlier subjective modal rating system. When there are two modes, they are separated either by minimal concentrations or concentration inflections. Enhancement of Nc is traced to greater CCN bimodality that causes narrower droplet spectra that suppress drizzle. These effects could augment indirect aerosol effects and can only be revealed by high‐resolution CCN spectral shape comparisons with cloud and drizzle microphysics.
A Large Eddy Model Study on the Effect of Overshooting Convection on Lower Stratospheric Water Vapor
Authors: Sang Wenjun , Huang Qian , Tian Wenshou , Wright Jonathon S. , Zhang Jiankai , Tian Hongying , Luo Jiali , Hu Dingzhu , Han Yuanyuan
Published: August 2018

Using a cloud‐resolving large eddy model (LEM), we investigate how overshooting convection affects the water vapor content in the lower stratosphere. We design and conduct a series of sensitivity experiments to diagnose the effects of dynamical and thermodynamical background conditions on the transport of water vapor into the lower stratosphere associated with overshooting convection. The three‐dimensional LEM simulations capture the bulk properties of the target case and track microphysical processes using a three‐phase microphysical parameterization. The model results indicate that the net effect of overshooting convection on lower stratospheric water content is moistening, primarily due to gravity wave breaking and ice sublimation. The contributions of small‐scale turbulent mixing to water vapor transport from the overshooting turret into the stratosphere are relatively weak. Sensitivity experiments show that convective intensity (as measured by updraft velocity) is directly related to the effect of overshooting convection on lower stratospheric humidity. This impact is quantified for the idealized target case. Changes in vertical wind shear near the tropopause have no significant impact on the extent of overshooting but have important impacts on cross‐tropopause water vapor exchange via their modulation of gravity wave breaking. Larger vertical wind shear in the tropopause layer inhibits the transport of water vapor and ice into the lower stratosphere by overshooting convection.
Large‐Amplitude Mountain Waves in the Mesosphere Accompanying Weak Cross‐Mountain Flow During DEEPWAVE Research Flight RF22
Authors: Fritts David C. , Vosper Simon B. , Williams Bifford P. , Bossert Katrina , Plane John M. C. , Taylor Michael J. , Pautet P.‐Dominique , Eckermann Stephen D. , Kruse Christopher G. , Smith Ronald B. , Dörnbrack Andreas , Rapp Markus , Mixa Tyler , Reid Iain M. , Murphy Damian J.
Published: August 2018

Mountain wave (MW) propagation and dynamics extending into the upper mesosphere accompanying weak forcing are examined using in situ and remote‐sensing measurements aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V (GV) research aircraft and the German Aerospace Center Falcon. The measurements were obtained during Falcon flights FF9 and FF10 and GV Research Flight RF22 of the Deep Propagating Gravity Wave Experiment (DEEPWAVE) performed over Mount Cook, New Zealand, on 12 and 13 July 2014. In situ measurements revealed both trapped lee waves having zonal wavelengths of λx ~ 12 km and less, and larger‐scale, vertically propagating MWs primarily at λx ~ 20–60 km and ~100–300 km extending from west to ~400 km east of Mount Cook. GV Rayleigh lidar measurements from 25‐ to 60‐km altitudes showed that the weak forcing and zonal winds that increased from ~12 m/s at 12 km to ~40 and 130 m/s at 30 and 55 km, respectively, enabled largely linear MW propagation and strong amplitude growth with altitude into the mesosphere. GV Na lidar and airglow imager measurements revealed an extensive MW response from ~70 to 87 km with large amplitudes and vertical displacements at λx ~ 40–300 km but with both decreasing with altitude approaching a critical level near 90 km. These MWs exhibited large‐scale MW breaking and among the largest sustained momentum fluxes observed in the mesosphere. UK Met Office Unified Model simulations of the RF22 MW event captured many aspects of the observed MW field and revealed that despite the dominant large‐scale MW responses in the stratosphere, the major momentum fluxes accompanied smaller‐scale waves.
Relationship Between Greenland Ice Sheet Surface Speed and Modeled Effective Pressure
Authors: Stevens Laura A. , Hewitt Ian J. , Das Sarah B. , Behn Mark D.
Published: August 2018

We use a numerical subglacial hydrology model and remotely sensed observations of Greenland Ice Sheet surface motion to test whether the inverse relationship between effective pressure and regional melt season surface speeds observed at individual sites holds on a regional scale. The model is forced with daily surface runoff estimates for 2009 and 2010 across an ~8,000‐km2 region on the western margin. The overall subglacial drainage system morphology develops similarly in both years, with subglacial channel networks growing inland from the ice sheet margin and robust subglacial pathways forming over bedrock ridges. Modeled effective pressures are compared to contemporaneous regional surface speeds derived from TerraSAR‐X imagery to investigate spatial relationships. Our results show an inverse spatial relationship between effective pressure and ice speed in the mid‐melt season, when surface speeds are elevated, indicating that effective pressure is the dominant control on surface velocities in the mid‐melt season. By contrast, in the early and late melt seasons, when surface speeds are slower, effective pressure and surface speed have a positive relationship. Our results suggest that outside of the mid‐melt season, the influence of effective pressures on sliding speeds may be secondary to the influence of driving stress and spatially variable bed roughness.
Framework for the Development of Planetary Spatial Data Infrastructures: A Europa Case Study
Authors: Laura J. R. , Bland M. T. , Fergason R. L. , Hare T. M. , Archinal B. A.
Published: August 2018

This study presents an implementation framework for the development of planetary spatial data infrastructures (PSDIs) that support improved spatial data management, discovery, access, and utilization. The implementation framework is drawn from terrestrially developed theoretical models (e.g., product‐based, process‐based, and complex adaptive system approaches) and case studies from large‐scale, multiorganization, or transnational spatial data infrastructures. We adapt these terrestrially proven techniques for the planetary sciences and present a Europa case study. This case study includes a knowledge inventory of available foundational and framework data products, the availability and access mechanisms currently used to discover said products, the interoperability of said products in geographic information systems, a review of the policies and standards currently being used by the Europa science community, and discussion of the users a Europa PSDI would serve. This study concludes with a vision for a unified, cross‐organization Europa PSDI to support both current science investigations and future data collection efforts.
Three‐Dimensional Spatially Constrained Sulfur Isotopes Highlight Processes Controlling Sulfur Cycling in the Near Surface of the Iheya North Hydrothermal System, Okinawa Trough
Authors: LaFlamme C. , Hollis S. P. , Jamieson J. W. , Fiorentini M. L.
Published: August 2018

Modern seafloor hydrothermal systems are unique environments in which many of the Earth's reservoirs, including the hydrosphere, biosphere, and geosphere, dynamically interact. Analysis of spatially constrained sulfur isotope compositions from fluids and hydrothermal precipitates within the discharge zone of a volcanogenic system can be used to trace the interactions between the various isotopically distinct sulfur reservoirs that result in the formation of hydrothermal massive sulfide deposits. Here we present in situ sulfur isotope results from laterally and vertically constrained euhedral hydrothermal pyrite from the Iheya North hydrothermal system in the Okinawa Trough, which was investigated during the Integrated Ocean Drilling Program Expedition 331. Hydrothermal pyrite at the North Big Chimney yields δ34S values of ~+11.9 ± 1.1‰ (1σ), which are near identical to the δ34S composition of the vent fluid. Outward, ~150 and ~450 m from North Big Chimney, hydrothermal pyrite within drill core yields δ34S equal to +10.9 ± 1.3‰ (1σ) and +7.0 ± 3.8‰ (1σ), respectively, showing a shift in isotopic composition away from the main vent site. This evolution to a lighter and more scattered isotopic signature of hydrothermal pyrite (which is easily identifiable from biogenic pyrite) is interpreted to indicate that the hydrothermal fluid leached sulfides (formed previously by biogenic processes) from the surrounding sedimentary strata. As the most significant metal enrichments (Fe, Zn, Cu, Bi, Tl, and Cd) are associated with samples that contain average hydrothermal pyrite δ34S values similar to δ34S of the vent fluid, we demonstrate that sulfur isotopes can vector toward metals in seafloor massive sulfide deposits.
Frictional Behavior of Input Sediments to the Hikurangi Trench, New Zealand
Authors: Rabinowitz H. S. , Savage H. M. , Skarbek R. M. , Ikari M. J. , Carpenter B. M. , Collettini C.
Published: August 2018

The Hikurangi subduction zone hosts shallow slow‐slip events, possibly extending to the seafloor. The mechanisms allowing for this behavior are poorly understood but are likely a function of the frictional properties of the downgoing seafloor sediments. We conducted friction experiments at a large range of effective stresses, temperatures, and velocities on incoming sediment to the Hikurangi subduction zone to explore the possible connection of frictional properties to slow‐slip events. These experiments were conducted on multiple apparatuses, allowing us to access a wider range of deformation conditions than is available on any one machine. We find that the material frictionally weakens and becomes less velocity strengthening with increasing effective stress, whereas temperature has only a small effect on both friction and frictional stability. When driven at the plate convergence rate, the sediment exhibits velocity‐weakening behavior. These results imply that the frictional properties of the sediment package subducting at Hikurangi could promote slow‐slip events at the pressures, temperatures, and strain rates expected along the plate boundary thrust up to 10‐km depth without requiring elevated pore fluid pressures. The transition to velocity‐strengthening behavior at faster slip rates could provide a mechanism for limiting unstable slip to slow‐sliding velocities, rather than accommodating deformation through ordinary earthquakes.
Shear Wave Splitting Beneath Eastern North American Continent: Evidence for a Multilayered and Laterally Variable Anisotropic Structure
Authors: Chen Xiaoran , Li Yiran , Levin Vadim
Published: August 2018

Eastern North America records a tectonic history of over 3 Ga in duration. Much of this record is preserved within the lithosphere and may be unraveled by detailed studies of its interior structure. Past episodes of tectonic activity likely left their imprints in the form of anisotropy‐forming rock fabric presently preserved in the lithosphere of the continent. We perform shear wave splitting measurements using observations of core‐refracted waves collected from a ~1,300‐km‐long array extending from James Bay in Quebec to the Fundy basin in Maine, with lateral spacing of 10–100 km between instruments. Close spacing of instruments helps us associate anisotropic properties with geological boundaries. We find that the fast polarizations concentrate between N60°E and N90°E with an average of N80°E and change systematically with backazimuth. In addition, we observe a lateral increase in delay time from 0.56 ±0.25 s at the NW end of the array to 0.90 ± 0.41 s at the SE end. The location of lateral change in delay time does not match geological boundaries on the surface but seems to match the geophysical boundary at depth of 160 km. We interpret this boundary in splitting values to be the edge of cratonic lithosphere at depth. Our observations suggest that the anisotropic structure beneath our study area is complex and possibly both multilayered and laterally variable.
Distinct Geologic Settings of Opal‐A and More Crystalline Hydrated Silica on Mars
Authors: Sun Vivian Z. , Milliken Ralph E.
Published: August 2018

Opaline silica deposits have been identified on Mars from orbital near‐infrared (NIR) reflectance spectra, but opal types (e.g., −A,/CT) have not yet been conclusively determined due to insufficient laboratory spectra acquired at Mars‐relevant conditions. NIR reflectance spectra of siliceous deposits acquired by the Compact Reconnaissance Imaging Spectrometer for Mars instrument are compared with new laboratory spectra of terrestrial opal samples that we measured under Mars‐relevant conditions. Opal‐A occurrences on Mars are commonly associated with bedrock exposures, whereas more crystalline hydrated silica (opal‐CT and quartz/chalcedony) is primarily observed in unconsolidated sediments. These differences suggest some opal‐bearing deposits may have experienced prolonged interaction with near‐surface water or diagenetic fluids, and bedrock exposures dominated by opal‐A may have experienced less post‐formation diagenesis compared with those containing more crystalline hydrated silica. NIR data thus provide a useful tool to assess opal maturity and relative potential for biosignature preservation for different siliceous deposits on Mars.
Organic Carbon Aging During Across‐Shelf Transport
Authors: Bao Rui , Uchida Masao , Zhao Meixun , Haghipour Negar , Montlucon Daniel , McNichol Ann , Wacker Lukas , Hayes John M. , Eglinton Timothy I.
Published: August 2018

Compound‐specific radiocarbon analysis was performed on different grain‐size fractions of surficial sediments to examine and compare lateral transport times (LTTs) of organic carbon. 14C aging of long‐chain leaf wax fatty acids along two dispersal pathways of fluvially derived material on adjacent continental margins implies LTTs over distances of ~30 to 500 km that range from hundreds to thousands of years. The magnitude of aging differs among grain size fractions. Our finding suggests that LTTs vary both temporally and spatially as a function of the specific properties of different continental shelf settings. Observations suggest that 14C aging is widespread during lateral transport over continental shelves, with hydrodynamic particle sorting inducing age variations among organic components residing in different grain sizes. Consideration of these phenomena is of importance for understanding carbon cycle processes and interpretation on sedimentary records on continental margins.
Weakening of Nonlinear ENSO Under Global Warming
Authors: Kohyama Tsubasa , Hartmann Dennis L. , Battisti David S.
Published: August 2018

The amplitude response of the El Niño–Southern Oscillation (ENSO) to global warming is examined in two global climate models with realistic ENSO nonlinearity. Geophysical Fluid Dynamics Laboratory Earth System Model Version 2M (GFDL‐ESM2M) and Model for Interdisciplinary Research on Climate version 5 (MIROC5) are the two models that exhibit realistic ENSO nonlinearity. With quadrupled atmospheric carbon dioxide, the ENSO amplitude of GFDL‐ESM2M decreases by about 40%, whereas that of MIROC5 remains almost constant. Because GFDL‐ESM2M exhibits stronger climatological thermal stratification than MIROC5, greenhouse gas forcing increases the upper ocean stability and causes the thermocline to be less sensitive to wind perturbations. The stiffer thermocline inhibits the nonlinear variations of sea surface temperature so that the ENSO amplitude substantially weakens. Idealized nonlinear recharge oscillator model experiments further support climatological thermal stratification as a determinant of the warming response. Observations exhibit stronger thermal stratification than both models, which suggests that the real world may terminate strong, nonlinear El Niños sooner than model‐based projections.
Structures of Hall Fields in Asymmetric Magnetic Reconnection
Authors: Dai Lei
Published: August 2018

Unlike a quadrupolar Hall magnetic field in symmetric magnetic reconnection, a bipolar or quadrupolar Hall magnetic field occurs in asymmetric reconnection as indicated by recent observations from the Magnetospheric Multiscale (MMS) mission. Here we present analytic calculations of the structures of Hall magnetic fields in asymmetric reconnection. The Hall magnetic fields are analyzed in terms of kinetic Alfvén wave eigenmodes of the reconnection layer. The bipolar and quadrupolar patterns of Hall magnetic fields correspond to a dominance of the n = 0 and n = 1 kinetic Alfvén wave eigenmode, respectively. The asymmetry of Hall fields is linked to the asymmetry of the Alfvé speed profile. The Hall magnetic fields are shifted toward and enhanced on the low Alfvén speed side of the reconnection layer. The asymmetry in the magnetic field strength of the reconnection layer has a major effect on the structures of Hall magnetic fields.
Comparison of Variations of TEC at Disturbed and Quiet Time Using Nonlinear Dynamics Tools
Authors: Eapen Suja , Asokan K. , Kumar K. Satheesh , Ramamohan T. R. , Kumar Anil
Published: August 2018

We analyze the underlying dynamics at three different latitudes of ionosphere through total electron content‐series for 4 months. The global dynamics reconstructed from the data is shown to be deterministic with low dimensional chaotic attractors at all the locations, and the dynamics is seen to be less complex at the midlatitude station with smaller dimension of correlation (CD) and maximum Lyapunov exponent (MLE). The influence of geomagnetic storms on the ionospheric dynamics is studied, by analyzing the local dynamics during disturbed and quiet periods, reconstructed from segments of total electron content‐series of shorter duration. With positive MLEs and smaller CDs, the local dynamics is seen to be deterministic and chaotic at the low latitude, midlatitude, and high latitude during both the disturbed and quiet days. However, it is interesting to observe that the dynamics is less chaotic and complex during the disturbed days of the entire period of observation compared to the adjacent quiet days at the three locations. This is further evidenced by sample predictions made using nonlinear tools, yielding better predictions during storms. The smaller CD value during disturbed periods indicates that the geomagnetic activities tend to make a few of the variables dominant enough to control the essential dynamics of the system. Further, the MLEs of the disturbed days are found to increase nearly in a linear fashion from beginning to end of the observation period at all the locations considered. This is an indication of the strong influence of geomagnetic activities on the ionosphere and might have caused the restructuring of the ionospheric dynamics.
Reply to Comment on the Article “Parametric Instability Induced by X‐Mode Wave Heating at EISCAT” by Wang et al. (2016)
Authors: Wang Xiang , Zhou Chen , Honary Farideh
Published: August 2018

This paper is a response to the comment by Blagoveshchenskaya et al. (2017, https://doi.org/10.1002/2017JA023880) on the paper by Wang et al. (2016, https://doi.org/10.1002/2016JA023070). Although we disagree with Blagoveshchenskaya et al. (2017), nevertheless, we do thank them for their comments, since they have given us the opportunity to clarify some points.
Geodetically Inferred Locking State of the Cascadia Megathrust Based on a Viscoelastic Earth Model
Authors: Li Shaoyang , Wang Kelin , Wang Yanzhao , Jiang Yan , Dosso Stan E.
Published: August 2018

In a viscoelastic Earth, stresses slowly built up due to fault locking are relaxed concurrently during the entire interseismic period. This interseismic stress relaxation causes crustal deformation much farther away from the locked fault than can be explained using elastic models that neglect the relaxation. Here we develop a viscoelastic geodetic inversion model to address this problem at Cascadia. We invert ~500 horizontal velocity vectors based on continuous and campaign geodetic measurements over the past two decades. Ambiguities arising from long‐term rotation of upper‐plate crustal blocks are addressed by test‐correcting the geodetic velocities with two different block‐motion models. Fault back slip (i.e., slip deficit) Green's functions are derived using a Maxwell viscoelastic finite element model with realistic subduction zone structure and megathrust geometry. The preferred model features a narrow and shallow megathrust locked zone, consistent with earlier thermorheological reasoning. For an elastic model to fit the data to the same fidelity, megathrust locking has to extend to much greater depths. However, even with the viscoelastic model, the land‐based geodetic data still cannot resolve whether there is some creep (incomplete locking) in the shallowest part of the megathrust far offshore. Neither can the land data fully resolve along‐strike variations of the locking state. These ambiguities can be resolved only when adequate seafloor geodetic data are obtained.
A Tensile Origin for Fault Rock Pulverization
Authors: Griffith W. Ashley , St. Julien Rene C. , Ghaffari Hamed O. , Barber Troy J.
Published: August 2018

The origin of highly fragmented, but weakly strained rocks found along major strike‐slip faults has been enigmatic since their first recognition. These so‐called pulverized rocks occur up to 100 m away from the principal slip zone of seismogenic faults around the world. Previous dynamic compression experiments have suggested that rock pulverization occurs at strain rates on the order of 102 s−1, pointing to a coseismic origin; however, strain rates during earthquake rupture 100 m from faults is expected to be 4 orders of magnitude smaller. We present evidence from new modified Split‐Hopkinson Pressure Bar experiments that instead supports a tensile origin for coseismic rock pulverization. In the new experimental configuration, the axial compressive load from the Split‐Hopkinson Pressure Bar induces radially isotropic tension in a Westerly Granite disk bonded between two lead cylinders. The isotropic tensile state of stress results in the formation of polygonal fracture arrays that bound axis‐parallel columnar fragments. The tensile strength of Westerly Granite measured at strain rates between ~5 and 50 s−1 bridges the gap between low strain rate and shock strengths reported previously, supporting an interpretation that highly fragmented rocks may form in a state of isotropic tension. The resulting fragment size is independent of strain rate and instead appears to be controlled by elastic strain energy, a strong function of material strength, and fracture toughness. Our results provide a solution to the strain rate‐distance scaling problem between laboratory experiments and field observations of pulverized rocks and also explain the asymmetric distribution of pulverized fault rocks about strike‐slip faults.
Olivine Grain Size Distributions in Faults and Shear Zones: Evidence for Nonsteady State Deformation
Authors: Aupart Claire , Dunkel Kristina G. , Angheluta Luiza , Austrheim Håkon , Ildefonse Benoit , Malthe‐Sørenssen Anders , Jamtveit Bjørn
Published: August 2018

The grain size distribution of deformed rocks may provide valuable information about their deformation history and the associated mechanisms. Here we present a unique set of olivine grain size distributions from ultramafic rocks deformed under a wide range of stress and strain rate conditions. Both experimentally deformed and naturally deformed samples are included. We observe a surprisingly uniform behavior, and most samples show power law grain size distributions. Convincing lognormal distributions across all scales were only observed for samples experimentally deformed at high temperature (1200 °C) and for some mantle‐deformed natural samples. Single power law distributions were observed for natural samples deformed by brittle mechanisms and by samples deformed experimentally in the regime of low‐temperature plasticity. Most natural samples show a crossover in power law scaling behavior near the median grain size from a steep slope for the larger grain fraction to a more gentle slope for the smaller grains. The small grain fraction shows a good data collapse when normalized to the crossover length scale. The associated power law slope indicates a common grain size controlling process. We propose a model that explains how such a scaling behavior may arise in the dislocation creep regime from the competition between the rate involved in the dislocation dynamics and the imposed strain rate. The common departure from lognormal distributions suggests that naturally deformed samples often have a deformation history that is far from a steady state scenario and probably reflects deformation under highly variable stress and strain rates.