bluuebunny/crossref_metadata_2025 huggingface dataset:
An Efficient Catalytic Approach for Epoxidation of Styrene over Activated Marble Powder
Authors: Yadagiri Jyothi , Kannapu Hari Prasad Reddy , Suh Young‐Woong , Puppala Veera Somaiah , Kamaraju Seetha Rama Rao , Burri David Raju
Published: August 2018

Styrene to styrene epoxide is conducted for the first time over marble powder (MP), consisting of CaO (62.12%), MgO (26.8%), SiO2 (9.24%) and minor amount of Fe (1.94%), Na (0.70%), P (0.019%), K (0.11%) and Mn (0.13%) under aqueous t‐butyl hydroperoxide as a simple and green process. Due to the calcium enriched marble, higher basicity (ca. CO2 3980 μ mol g−1) was observed from temperature programmed desorption (TPD) of CO2. The excellent catalytic activity with styrene conversion of 98% and styrene epoxide selectivity of 84% during the course of recyclability test for five consecutive cycles is mainly attributed to the constant basicity of the marble.
Laser‐Induced Freestanding Graphene Papers: A New Route of Scalable Fabrication with Tunable Morphologies and Properties for Multifunctional Devices and Structures
Authors: Wang Yanan , Wang Yong , Zhang Peipei , Liu Fu , Luo Sida
Published: August 2018

The recently emergent laser‐induced graphene (LIG) technology has endowed the fabrication of smart devices with one‐step processing and scalable/designable features. Graphene paper (GP), an important architecture of 2D layered carbon, however, is never produced through LIG. Herein, a novel strategy is reported for production of freestanding GP through LIG technology. It is first determined that the unique spatial configuration of polyimide (PI) paper is critical for the preparation of GP without the appearance of intense shape distortion. Benefiting from the mechanism, the as‐produced laser‐induced graphene paper (LIGP) is foldable, trimmable, and integratable to customized shapes and structures with the largest dimension of 40 × 35 cm2. Based on the processing–structure–property relationship study, one is capable of controlling and tuning various physical and chemical properties of LIGPs, rendering them unique for assembling flexible electronics and smart structures, e.g., human/robotic motion detectors, liquid sensors, water–oil separators, antibacterial media, and flame retardant/deicing/self‐sensing composites. With the key findings, the escalation of LIGP for commercialization, roll‐to‐roll manufacturing, and multidisciplinary applications are highly expected.
A model‐based systems engineering approach to critical infrastructure vulnerability assessment and decision analysis
Authors: Huff Johnathon , Medal Hugh , Griendling Kelly
Published: August 2018

Securing
critical infrastructure against attack presents significant challenges. As new infrastructure is built and existing infrastructure is maintained, a method to assess the vulnerabilities and support decision makers in determining the best use of security resources is needed. In response to this need, this research develops a methodology for performing vulnerability assessment and decision analysis of critical infrastructure using model‐based systems engineering, an approach that has not been applied to this problem. The approach presented allows architects to link regulatory requirements, system architecture, subject matter expert opinion and attack vectors to a Department of Defense Architecture Framework (DoDAF)‐based model that allows decision makers to evaluate system vulnerability and determine alternatives to securing their systems based on their budget constraints. The decision analysis is done using an integer linear program that is integrated with DoDAF to provide solutions for how to allocate scarce security resources. Securing an electrical substation is used as an illustrative case study to demonstrate the methodology. The case study shows that the method presented here can be used to answer key questions, for example, what security resources should a decision maker invest in based on their budget constraints? Results show that the modeling and analysis approach provides a means to effectively evaluate the infrastructure vulnerability and presents a set of security alternatives for decision makers to choose from, based on their vulnerabilities and budget profile.
Chemosensitizing effect of honokiol in oral carcinoma stem cells via regulation of IL‐6/Stat3 signaling
Authors: Chang Min‐Te , Lee Shiao‐Pieng , Fang Chih‐Yuan , Hsieh Pei‐Ling , Liao Yi‐Wen , Lu Ming‐Yi , Tsai Lo‐Lin , Yu Cheng‐Chia , Liu Chia‐Ming
Published: August 2018

Oral squamous cell carcinoma (OSCC) is one of the most common cancers worldwide with poor prognosis. Numerous studies have attempted to explore alternative regimens aimed at reducing cancer stem cells (CSCs) without compromising the efficacy of conventional chemoradiotherapy. The present study sought to assess the effect of a natural compound honokiol on the reduction of elevated cancer stemness, metastatic capacity, and chemoresistance of oral carcinoma stem cells (OCSCs). Our results demonstrated that honokiol attenuated the cell survival and self‐renewal of OCSCs in a dose‐dependent manner. Moreover, honokiol downregulated the expression of 2 selective markers of OCSCs, ALDH1, and CD44, as well as the migration and invasion abilities, indicating its potential to suppress cancer stemness. We showed that honokiol reduced the secretion of IL‐6 and phosphorylation of STAT3, and the honokiol‐inhibited self‐renewal, invasion and colony formation were reversed by administration of IL‐6. Most importantly, our data demonstrated that honokiol was able to potentiate the effect of Cisplatin, leading to a lower proportion of OCSCs and the decreased cancer stemness features. Taken together, this study demonstrated the benefits of utilizing honokiol as an adjunct therapy for OSCC treatment.
Correlation between central and uterine hemodynamics in hypertensive disorders of pregnancy
Authors: Perry H. , Lehmann H. , Mantovani E. , Thilaganathan B. , Khalil A.
Published: August 2018

Objective

Pregnancies affected by a hypertensive disorder (HDP) have increased uterine artery pulsatility index (UtA‐PI) compared with that in healthy pregnancies. Women with HDP are also known to have lower cardiac output and increased systemic vascular resistance. The aim of this study was to investigate the relationship between central and uterine hemodynamics in HDP and uncomplicated pregnancy.

Methods

This was a prospective study of HDP and normotensive control singleton pregnancies presenting at a tertiary referral hospital between January 2012 and December 2017. Paired measurements of maternal hemodynamics, using a non‐invasive device (USCOM‐1A®), and UtA‐PI were performed in the third trimester. HDP pregnancies were divided into preterm (onset < 37 weeks' gestation) and term (onset ≥ 37 weeks). Spearman's rank coefficient was used to assess the correlation between the central and uteroplacental hemodynamics. Regression analysis was performed to assess the association of UtA‐PI with independent variables.

Results

We included 231 women with HDP (152 with preterm and 79 with term HDP) and 378 controls with normotensive pregnancy. Compared with controls, women with preterm HDP had significantly lower cardiac output (median (interquartile range (IQR)), 6.0 (5.1–7.2) vs 6.6 (5.8–7.5) L/min; P < 0.001) and significantly higher systemic vascular resistance (median (IQR), 1394 (1189–1670) vs 1063 (915–1222) dynes × s/cm5; P < 0.001) and UtA‐PI (median (IQR), 1.0 (0.75–1.4) vs 0.67 (0.58–0.83); P < 0.001). Conversely, in women with term HDP, there were no significant differences in heart rate, cardiac output or UtA‐PI compared with controls (all P > 0.05), while systemic vascular resistance was significantly higher (median (IQR), 1315 (1099–1527) vs 1063 (915–1222) dynes × s/cm5; P < 0.001). On multiple regression analysis, heart rate, mean arterial pressure and stroke volume were associated significantly with mean UtA‐PI (all P < 0.001).

Conclusions

Differences observed between HDP and normotensive pregnancies in third‐trimester UtA resistance are mirrored in the central maternal hemodynamic parameters. Late pregnancy differences in the uteroplacental circulation in preterm and term HDP are an index of maternal cardiovascular function rather than being related to inadequate spiral artery remodeling and impaired placentation. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.
Aerodynamic measurements on wind turbines
Authors: Schepers J. G. , Schreck S. J.
Published: August 2018

This article reviews the aerodynamic measurement programs on wind turbines that have been performed in the last decades. It is largely based on results from four projects carried out under auspices of the International Energy Agency (IEA), which are denoted as IEA Tasks 14, 18, 20, and 29. The aim of these projects was to collect and analyze aerodynamic measurements on five field facilities (IEA Tasks 14 and 18), the National Renewable Energy Laboratory Phase VI turbine placed in the large NASA Ames wind tunnel (IEA Task 20), and the Mexico turbine placed in the Large Low Speed Facility of the German Dutch Wind tunnel DNW (IEA Task 29). Other experimental programs with an important aerodynamic content are touched upon as well. Research areas for which these measurements have led to important progress are identified. The progress is illustrated with analyses on these experiments. It is shown that detailed aerodynamic measurements are an absolute necessity for the validation and improvement of wind turbine design codes, where it is also concluded that the amount of measurement data which has been produced until now is still far too limited.

This article is categorized under:

Wind Power > Science and Materials
First subleading power resummation for event shapes
Authors: Moult Ian , Stewart Iain W. , Vita Gherardo , Zhu Hua Xing
Published: August 2018

Abstract

We derive and analytically solve renormalization group (RG) equations of gauge invariant non-local Wilson line operators which resum logarithms for event shape observables τ at subleading power in the τ ≪ 1 expansion. These equations involve a class of universal jet and soft functions arising through operator mixing, which we call θ-jet and θ-soft functions. An illustrative example involving these operators is introduced which captures the generic features of subleading power resummation, allowing us to derive the structure of the RG to all orders in α

s
, and provide field theory definitions of all ingredients. As a simple application, we use this to obtain an analytic leading logarithmic result for the subleading power resummed thrust spectrum for H → gg in pure glue QCD. This resummation determines the nature of the double logarithmic series at subleading power, which we find is still governed by the cusp anomalous dimension. We check our result by performing an analytic calculation up to

$$ \mathcal{O}\left({\alpha}_s^3\right) $$

O

α
s
3

. Consistency of the subleading power RG relates subleading power anomalous dimensions, constrains the form of the θ-soft and θ-jet functions, and implies an exponentiation of higher order loop corrections in the subleading power collinear limit. Our results provide a path for carrying out systematic resummation at subleading power for collider observables.
Toward automatic verification of quantum programs
Authors: Ying Mingsheng
Published: August 2018

This paper summarises the results obtained by the author and his collaborators in a program logic approach to the verification of quantum programs, including quantum Hoare logic, invariant generation and termination analysis for quantum programs. It also introduces the notion of proof outline and several auxiliary rules for more conveniently reasoning about quantum programs. Some problems for future research are proposed at the end of the paper.
Gray matter density reduction associated with adjuvant chemotherapy in older women with breast cancer
Authors: Chen Bihong T. , Jin Taihao , Patel Sunita K. , Ye Ningrong , Sun Can-Lan , Ma Huiyan , Rockne Russell C. , Root James C. , Saykin Andrew J. , Ahles Tim A. , Holodny Andrei I. , Prakash Neal , Mortimer Joanne , Waisman James , Yuan Yuan , Li Daneng , Somlo George , Vazquez Jessica , Levi Abrahm , Tan Heidi , Yang Richard , Katheria Vani , Hurria Arti
Published: August 2018

Purpose

The purpose of this study was to evaluate longitudinal changes in brain gray matter density (GMD) before and after adjuvant chemotherapy in older women with breast cancer.

Methods

We recruited 16 women aged ≥ 60 years with stage I–III breast cancers receiving adjuvant chemotherapy (CT) and 15 age- and sex-matched healthy controls (HC). The CT group underwent brain MRI and the NIH Toolbox for Cognition testing prior to adjuvant chemotherapy (time point 1, TP1) and within 1 month after chemotherapy (time point 2, TP2). The HC group underwent the same assessments at matched intervals. GMD was evaluated with the voxel-based morphometry.

Results

The mean age was 67 years in the CT group and 68.5 years in the HC group. There was significant GMD reduction within the chemotherapy group from TP1 to TP2. Compared to the HC group, the CT group displayed statistically significantly greater GMD reductions from TP1 to TP2 in the brain regions involving the left anterior cingulate gyrus, right insula, and left middle temporal gyrus (pFWE(family-wise error)-corrected < 0.05). The baseline GMD in left insula was positively correlated with the baseline list-sorting working memory score in the HC group (pFWE-corrected < 0.05). No correlation was observed for the changes in GMD with the changes in cognitive testing scores from TP1 to TP2 (pFWE-corrected < 0.05).

Conclusions

Our findings indicate that GMD reductions were associated with adjuvant chemotherapy in older women with breast cancer. Future studies are needed to understand the clinical significance of the neuroimaging findings. This study is registered on ClinicalTrials.gov (NCT01992432).
“A SACRED TRUST FOR THE FUTURE”: REGULATING INSURANCE, 1800–70
Authors: Rawlings Philip
Published: August 2018

The history of commercial law has often been written as if it were merely a product of the common law, disregarding the role played by legislation. The principal exception to this has been work on company law. Until recently, the prevailing view has been that the Companies Acts 1844–62 represented the triumph of the free market and the expulsion of the state from business. But, although these laws did make incorporation easier and granted companies privileges, what this view ignores is that they also imposed regulation, such as obligations to register the company and charges on its assets and to hold shareholder meetings. At the forefront of these legal changes were insurance companies. Yet, in spite of the proliferation of these companies and their role in, for example, the inquiry that led to the 1844 Act, they have been neglected. This may be because, while the successful campaign in 1824 to remove restrictions on access to the marine-insurance market would seem to support the view of legislation driven by free-market ideas, that explanation seems contradicted by the closing of access to the life-assurance market and the imposition of various obligations on life offices in 1870, a time when the liberalisation of company laws seemed at their peak. Neither development can, however, be so easily explained, and both show the effect of fierce divisions within the insurance industry.
Family status and later-life depression among older adults in urban Latin America and the Caribbean
Authors: Quashie Nekehia T. , Andrade Flavia C.D.
Published: August 2018

Rapid fertility declines in Latin American and Caribbean countries since the 1960s have contributed to smaller family sizes among the current cohorts of older adults. This may have mental health implications in these societies as the family unit is highly valued as a source of social support. Utilising data from the 2000 Survey of Health, Well-being and Aging in Latin America and the Caribbean (SABE), this study examines the association between parental status, marital status and the likelihood of experiencing depressive symptoms among adults 60 years and older in seven cities within Latin America and the Caribbean (N = 9,756): Buenos Aires, Bridgetown, São Paulo, Santiago, Havana, Mexico City and Montevideo. Results from multivariate logistic regressions indicate that parental status is not significantly associated with depressive symptoms. Nonetheless, unmarried older adults, both those living alone and those living with others, are more vulnerable to experiencing depressive symptoms than their married counterparts. Marriage is especially protective for older adults in Havana and Montevideo. Older adults’ perceived income adequacy significantly moderates the relationship between marital status and depressive symptoms. Other significant covariates, such as experiencing disability and comorbidity, showed positive associations with depressive symptoms. While families may still represent a critical component for the mental health of older adults, broader investments in health across the lifespan are needed to improve individual psychological wellbeing.
Twelve shades of grey: encountering urban colour in the street in British provincial towns,c. 1945–1970
Authors: FAIRE LUCY , MCHUGH DENISE
Published: August 2018

This article examines the neglected sensory experience of visual physical colour in the city/town centre or what is now referred to as the Central Business District. It focuses on the post-war period when reconstruction, town planning, new architecture, novel materials and technologies, and investment were all transforming British city centres. The research uses film, photographs, planning documents, oral history and social media reminiscences to research the users’ experience of colour in the city centre streets. It argues that, although new materials in construction opened up the possibilities of bright, ‘non-natural’ colours in the urban built environment, the visual experience of colour was found mainly in the ephemera of everyday life. Furthermore, it argues that colour was an important component in constructing people's sense of place and belonging in the city.
Annual Sediment Transport Dynamics in the Narayani Basin, Central Nepal: Assessing the Impacts of Erosion Processes in the Annual Sediment Budget
Authors: Morin Guillaume P. , Lavé Jérôme , France‐Lanord Christian , Rigaudier Thomas , Gajurel Ananta Prassad , Sinha Rajiv
Published: August 2018

Identifying the roles of erosional processes in the denudation of mountain ranges requires a better understanding of erosional sensitivity to climatic, topographic, or lithologic controls. We analyzed erosion in the Narayani River basin (draining central Nepal and presenting contrasted lithologic and geochemical signatures in its outcropping rocks and a wide variety of erosional processes and climatic conditions) to assess the relative contributions of erosion processes to the annual sediment export. By combining acoustic Doppler current profiler measurements with depth profiles and daily surface samplings of the suspended load, we propose a simplified model to precisely calculate sediment fluxes at the basin outlet. We estimate an equivalent erosion rate of
 mm/year for the year 2010, similar to the average value of
 mm/year estimated from 15 years of records and long‐term (~ky) denudation rates of 1.7 mm/year derived from cosmogenic nuclides. The stability of erosion is attributed to efficient buffering behavior and spatial integration in the drainage system. Strong relations between rainfall events and the sediment export suggest that the system is mainly supply limited. Combining physical calculation of sediment fluxes with grain size analyses and geochemical tracers (hydroxyl isotopic compositions, carbonate contents, and total organic carbon content), we estimate that glacial and soil erosion do not contribute more than 10% and a few percentage, respectively, to the total budget and are only detectable during premonsoon and early monsoon periods. During the monsoon, erosion by landslides and mass wasting events overwhelms the sediment budget, confirming the dominant role of these erosional processes in active mountain chains.
CloudNet: Ground‐Based Cloud Classification With Deep Convolutional Neural Network
Authors: Zhang Jinglin , Liu Pu , Zhang Feng , Song Qianqian
Published: August 2018

Clouds have an enormous influence on the Earth's energy balance, climate, and weather. Cloud types have different cloud radiative effects, which is an essential indicator of the cloud effect on radiation. Therefore, identifying the cloud type is important in meteorology. In this letter, we propose a new convolutional neural network model, called CloudNet, for accurate ground‐based meteorological cloud classification. We build a ground‐based cloud data set, called Cirrus Cumulus Stratus Nimbus, which consists of 11 categories under meteorological standards. The total number of cloud images is three times that of the previous database. In particular, it is the first time that contrails, a type of cloud generated by human activity, have been taken into account in the ground‐based cloud classification, making the Cirrus Cumulus Stratus Nimbus data set more discriminative and comprehensive than existing ground‐based cloud databases. The evaluation of a large number of experiments demonstrates that the proposed CloudNet model could achieve good performance in meteorological cloud classification.
Investigation of Acoustic Waves in the Ionosphere Generated by a Deep Convection System Using Distributed Networks of GPS Receivers and Numerical Modeling
Authors: Azeem Irfan , Walterscheid Richard L. , Crowley Geoff
Published: August 2018

Acoustic waves generated in the lower atmosphere may become an important source of variability in the upper atmosphere. Although excited with small amplitudes compared to gravity waves, they are minimally subjected to viscous dissipation and may reach large amplitudes at F region altitudes. We present total electron content data from a dense network of ground‐based GPS receivers during an outbreak of severe weather over Kansas on 26 May 2016. The results show annular traveling ionospheric disturbances (TIDs) propagating radially outward from the center of the storm. The TID characteristics were consistent with acoustic waves in the infrasonic range. We have modeled the disturbance by including a heat source representing latent heat release from a large thunderstorm. The modeled disturbance at ionospheric altitudes resembles the TIDs in terms of phase speed, frequency, and horizontal wavelength. We conclude that the observed TIDs were caused by an acoustic wave generated by deep convection.
Saturn's Plasma Density Depletions Along Magnetic Field Lines Connected to the Main Rings
Authors: Farrell W. M. , Hadid L. Z. , Morooka M. W. , Kurth W. S. , Wahlund J.‐E. , MacDowall R. J. , Sulaiman A. H. , Persoon A. M. , Gurnett D. A.
Published: August 2018

We report on a set of clear and abrupt decreases in the high‐frequency boundary of whistler mode emissions detected by Cassini at high latitudes (about ±40°) during the low‐altitude proximal flybys of Saturn. These abrupt decreases or dropouts have start and stop locations that correspond to L shells at the edges of the A and B rings. Langmuir probe measurements can confirm, in some cases, that the abrupt decrease in the high‐frequency whistler mode boundary is associated with a corresponding abrupt electron density dropout over evacuated field lines connected to the A and B rings. Wideband data also reveal electron plasma oscillations and whistler mode cutoffs consistent with a low‐density plasma in the region. The observation of the electron density dropout along ring‐connecting field lines suggests that strong ambipolar forces are operating, drawing cold ionospheric ions outward to fill the flux tubes. There is an analog with the refilling of flux tubes in the terrestrial plasmasphere. We suggest that the ring‐connected electron density dropouts observed between 1.1 and 1.3 Rs are connected to the low‐density ring plasma cavity observed overtop the A and B rings during the 2004 Saturn orbital insertion pass.
An Improved Prediction of Indian Summer Monsoon Onset From State‐of‐the‐Art Dynamic Model Using Physics‐Guided Data‐Driven Approach
Authors: Sahana A. S. , Ghosh Subimal
Published: August 2018

Prediction of Indian Summer Monsoon onset, which marks the beginning of the South Asian monsoon, has significant implications on monsoon characteristics and subsequent nationwide agricultural planning. Here we make the most skillful prediction of monsoon onset with a physics‐guided data‐driven model integrated with the operational monsoon prediction by Coupled Forecast System version 2. Drivers of the variability of onset, which are well simulated by Coupled Forecast System version 2, viz., tropical Pacific sea surface temperature, reversal of tropospheric temperature gradient and strengthening of westerlies over AS during the early summer are identified as potential predictors. Data‐driven method, Least Absolute Shrinkage and Selection Operator, makes the final selection of predictors for the linear regression model of onset. We obtain an improved correlation of 0.6 between simulated and observed onset dates with the proposed integrated statistical dynamical model as compared to 0.44 obtained with the operational dynamic monsoon prediction model.
Overturning the Mediterranean Thermohaline Circulation
Authors: Waldman Robin , Brüggemann Nils , Bosse Anthony , Spall Michael , Somot Samuel , Sevault Florence
Published: August 2018

For more than five decades, the Mediterranean Sea has been identified as a region of so‐called thermohaline circulation, namely, of basin‐scale overturning driven by surface heat and freshwater exchanges. The commonly accepted view is that of an interaction of zonal and meridional conveyor belts that sink at intermediate or deep convection sites. However, the connection between convection and sinking in the overturning circulation remains unclear. Here we use a multidecadal eddy‐permitting numerical simulation and glider transport measurements to diagnose the location and physical drivers of this sinking. We find that most of the net sinking occurs within 50 km of the boundary, away from open sea convection sites. Vorticity dynamics provides the physical rationale for this sinking near topography: only dissipation at the boundary is able to balance the vortex stretching induced by any net sinking, which is hence prevented in the open ocean. These findings corroborate previous idealized studies and conceptually replace the historical offshore conveyor belts by boundary sinking rings. They challenge the respective roles of convection and sinking in shaping the oceanic overturning circulation and confirm the key role of boundary currents in ventilating the interior ocean.
The Role of Waves, Shelf Slope, and Sediment Characteristics on the Development of Erosional Chenier Plains
Authors: Nardin William , Fagherazzi Sergio
Published: August 2018

Cheniers are sandy ridges parallel to the coast separated by muddy deposits. Here we explore the development of erosional chenier plains, which form by winnowing during storms, through dimensional analysis and numerical results from the morphodynamic model Delft3D‐SWAN. Our results highlight that wave energy and inner‐shelf slope play an important role in the formation of erosional chenier plains. We further show that different sediment characteristics and wave climates lead to three alternative coastal landscapes: sandy strandplains, mudflats, or the more complex erosional chenier plains. Low inner‐shelf slopes are the most favorable for mudflat and chenier plain formation, while high slopes decrease the likelihood of mudflat development and preservation, favoring the formation of strandplains. The present study shows that erosional cheniers can form only when there is enough sediment availability to counteract wave action and for a specific range of shelf slopes.
Impact of Parametrized Nonorographic Gravity Wave Drag on Stratosphere‐Troposphere Coupling in the Northern and Southern Hemispheres
Authors: Polichtchouk Inna , Shepherd Theodore G. , Byrne Nicholas J.
Published: August 2018

The impact of parametrized nonorographic gravity wave drag (NOGWD) on the stratosphere‐troposphere dynamical coupling in atmospheric models is relatively unexplored. Using the European Centre for Medium‐Range Weather Forecasts Integrated Forecast System, we find that changes in NOGWD strength have a substantial impact on the tropospheric eddy‐driven jet (EDJ) in both hemispheres, but the sense of the impact is opposite in the two hemispheres. In the Northern Hemisphere the impact occurs via changes in the amplitude and persistence of stratospheric anomalies. In the Southern Hemisphere it occurs instead via differences in the sensitivity of the EDJ to a given stratospheric anomaly, arising from changes in the seasonal cycle leading up to the polar vortex breakdown. Increasing NOGWD eliminates the springtime phase of the Southern Hemisphere tropospheric semiannual oscillation, resulting in a more equatorward annual‐mean EDJ and showing that the semiannual oscillation cannot be explained entirely from tropospheric mechanisms.
Dipole Types of Autumn Precipitation Variability Over the Subtropical East Asia‐Western Pacific Modulated by Shifting ENSO
Authors: Hu Chundi , Chen Dake , Huang Gang , Yang Song
Published: August 2018

Recent autumns have exhibited two dipole types of precipitation variability (DIPO1 and DIPO2) over the subtropical East Asia‐western Pacific (SEAWP). Meanwhile, El Niño–Southern Oscillation (ENSO) has undergone significant mode shift, exhibiting as the eastern Pacific or central Pacific ENSO (EPSO or CPSO). Whether there was any physical linkage between the two remains unclear. Here we demonstrate for the first time that interannual variations of DIPO1 and DIPO2 are closely linked to EPSO and CPSO, respectively. Shifting ENSO modulates the patterns of SEAWP precipitation dipole mainly via changing the path of tropospheric moisture transport and the location of anomalous water vapor convergence/divergence due to different low‐level cyclone/anticyclone activities induced by EPSO or CPSO. Further analysis shows that the interdecadal variability of SEAWP precipitation is also linked to the La Niña‐like climate shift in 1998. Hence, our study provides some new insight into the ongoing hot debate on the shifting ENSO and increasing autumn drought in southeastern China.
Great Expectations: Plans and Predictions for New Horizons Encounter With Kuiper Belt Object 2014 MU69 (“Ultima Thule”)
Authors: Moore Jeffrey M. , McKinnon William B. , Cruikshank Dale P. , Gladstone G. Randall , Spencer John R. , Stern S. Alan , Weaver Harold A. , Singer Kelsi N. , Showalter Mark R. , Grundy William M. , Beyer Ross A. , White Oliver L. , Binzel Richard P. , Buie Marc W. , Buratti Bonnie J. , Cheng Andrew F. , Howett Carly , Olkin Cathy B. , Parker Alex H. , Porter Simon B. , Schenk Paul M. , Throop Henry B. , Verbiscer Anne J. , Young Leslie A. , Benecchi Susan D. , Bray Veronica J. , Chavez Carrie L. , Dhingra Rajani D. , Howard Alan D. , Lauer Tod R. , Lisse C. M. , Robbins Stuart J. , Runyon Kirby D. , Umurhan Orkan M.
Published: August 2018

The New Horizons encounter with the cold classical Kuiper Belt object 2014 MU69 (informally named “Ultima Thule,” hereafter Ultima) on 1 January 2019 will be the first time a spacecraft has ever closely observed one of the free‐orbiting small denizens of the Kuiper Belt. Related to but not thought to have formed in the same region of the solar system as the comets that been explored so far, it will also be the most distant, and most primitive body yet visited by spacecraft. In this letter we begin with a brief overview of cold classical Kuiper Belt objects, of which Ultima is a prime example. We give a short preview of our encounter plans. We note what is currently known about Ultima from Earth‐based observations. We then review our expectations and capabilities to evaluate Ultima's composition, surface geology, structure, near space environment, small moons, rings, and the search for activity.
MMS Observations of Harmonic Electromagnetic Ion Cyclotron Waves
Authors: Usanova M. E. , Ahmadi N. , Malaspina D. M. , Ergun R. E. , Trattner K. J. , Reece Q. , Leonard T. , Fuselier S. A. , Torbert R. B. , Russell C. T. , Burch J. L.
Published: August 2018

Harmonically related electromagnetic ion cyclotron waves with the fundamental frequency near the double oxygen cyclotron frequency were observed by the MMS spacecraft on 18–20 May 2016. The wave activity lasted for three days, detected by the spacecraft on their consecutive inbound passages through the Earth's plasma sheet boundary layer. The waves were seen in both magnetic and electric fields, formed by over 10 higher order harmonics. Simultaneous ion flux measurements show the presence of ion ring distributions suggesting the energy source for the observed waves. The ion cyclotron harmonics were observed together with broadband waves extending from ~Hz to ~kHz frequency range, ion and electron phase space holes, and chorus waves. During some intervals, there is a clear modulation of chorus wave packets at the ion cyclotron fundamental harmonic frequency. These observations are particularly interesting since they suggest cross‐frequency and cross‐species coupling between processes happening on ion and electron scales.
Faults and Non‐Double‐Couple Components for Induced Earthquakes
Authors: Wang Ruijia , Gu Yu Jeffrey , Schultz Ryan , Chen Yunfeng
Published: August 2018

Focal mechanisms of induced earthquakes reflect anthropogenic contributions to preexisting geological features and fault slippages. In this paper, we examine fault‐related (double‐couple (DC)) and possibly fluid‐related (non‐double‐couple (non‐DC)) mechanisms of induced earthquakes (M2–6) at regional scales. We systematically compare well‐resolved focal mechanisms of 33 events in the Western Canada Sedimentary Basin, among which 12 were induced by hydraulic fracturing and one by secondary recovery. Most of the seismicity is dominated by strike‐slip/thrust faulting regimes, whereas limited (but consistent) non‐DC components are obtained from injection‐induced seismicity in central Alberta. We interpret the persistent compensated‐linear‐vector‐dipole components (M2.1–3.8) as reflecting fracture growth and/or noncoplanar faults slippages during hydraulic‐fracturing stimulations. We further expand the moment tensor decomposition analysis to four representative classes of induced seismicity globally and find that the overall contribution of non‐DC components is comparable between induced and tectonic earthquakes.
Improved Reanalysis and Prediction of Atmospheric Fields Over the Southern Ocean Using Campaign‐Based Radiosonde Observations
Authors: Sato Kazutoshi , Inoue Jun , Alexander Simon P. , McFarquhar Greg , Yamazaki Akira
Published: August 2018

This study investigated the impact of radiosonde observations from the Southern Ocean obtained by the Australian R/V Aurora Australis on the ALERA2 experimental ensemble reanalysis data set and ensemble forecast experiment. An observing system experiment (OSE) that included additional ship‐launched radiosonde data captured the atmospheric structure over the Southern Ocean. ALERA2 without additional radiosondes had positive temperature biases exceeding 7 °C in the upper troposphere when low‐pressure cyclonic systems passed over the ship. The spread in the upper level was reduced by 15% in the OSE, which propagated downstream from the ship's position because of the sparse observing network over southern high latitudes. Comparison of two 63‐member ensemble forecast experiments initialized by ALERA2 and the OSE revealed that prediction of midlatitude cyclone tracks was improved by the realistic representation of upper‐level troughs in the OSE forecast. This confirms that additional radiosondes over the Southern Ocean reduce uncertainty and error in midlatitude cyclone forecasts.
The Bagnold Dunes in Southern Summer: Active Sediment Transport on Mars Observed by the Curiosity Rover
Authors: Baker Mariah M. , Lapotre Mathieu G. A. , Minitti Michelle E. , Newman Claire E. , Sullivan Robert , Weitz Catherine M. , Rubin David M. , Vasavada Ashwin R. , Bridges Nathan T. , Lewis Kevin W.
Published: August 2018

Orbiter‐based observations have demonstrated that active aeolian environments are ubiquitous across Mars. Here we examine one such environment, the Bagnold Dune Field in Gale crater, with repeat imaging campaigns conducted from Curiosity during southern summer. Images reveal widespread migration of aeolian impact ripples (up to 2.8 cm/sol), which is in stark contrast to the inactivity of similar bedforms during southern winter. The winds responsible for steady southwestward migration of ripples are consistent with predictions of regional‐scale flows that enter the crater from the north and interact with the topography of Mount Sharp but are not fully representative of all dune‐forming winds. Inferred friction speeds of 1.5 m/s needed to explain mobilization of bedforms are likely not being achieved, and thus, a majority of sediment transport may be taking place at subthreshold conditions. This hypothesis is further supported by sand flux estimates that suggest a low saltation flux environment within the dune field.
Perpendicular Current Reduction Caused by Cold Ions of Ionospheric Origin in Magnetic Reconnection at the Magnetopause: Particle‐in‐Cell Simulations and Spacecraft Observations
Authors: Toledo‐Redondo Sergio , Dargent Jérémy , Aunai Nicolas , Lavraud Benoit , André Mats , Li Wenya , Giles Barbara , Lindqvist Per‐Arne , Ergun Robert E. , Russell Christopher T. , Burch James L.
Published: August 2018

Cold ions of ionospheric origin are present throughout the Earth's magnetosphere, including the dayside magnetopause, where they modify the properties of magnetic reconnection, a major coupling mechanism at work between the magnetosheath and the magnetosphere. We present Magnetospheric MultiScale (MMS) spacecraft observations of the reconnecting magnetopause with different amounts of cold ions and show that their presence reduces the Hall term in the Ohm's law. Then, we compare two particle‐in‐cell simulations, with and without cold ions on the magnetospheric side. The cold ions remain magnetized inside the magnetospheric separatrix region, leading to the reduction of the perpendicular currents associated with the Hall effect. Moreover, this reduction is proportional to the relative number density of cold ions. And finally, the Hall electric field peak is reduced along the magnetospheric separatrix owing to cold ions. This should have an effect on energy conversion by reconnection from electromagnetic fields to kinetic energy of the particles.
Interaction Between Moderate Earthquakes and Volcanic Eruptions: Analyses of Global Data Catalog
Authors: Nishimura Takeshi
Published: August 2018

The interaction between earthquakes and volcanic eruptions is investigated by analyzing a modern seismic data catalog of centroid moment tensor solutions and eruption records summarized by the Smithsonian Institution. To determine the average features of the interactions, the numbers of earthquakes that occurred before and after the initiation of each eruption with a volcanic explosivity index of larger than or equal to 2 are analyzed. The results show that moderate earthquakes, which have moment magnitudes of 5 to 6 (Mw 5–6), are activated within a horizontal distance of 50 km from volcanoes for about 0.3 years after the initiation of an eruption. About 13% of volcanic eruptions are accompanied by moderate earthquakes. The occurrence possibility of earthquakes every 0.1 years for 0.3 years after an eruption is about 5 times larger than normal. No significant dependence on the tectonic settings and major rock types is recognized.
Radar Altimetry as a Robust Tool for Monitoring the Active Lava Lake at Erebus Volcano, Antarctica
Authors: Peters N. J. , Oppenheimer C. , Brennan P. , Lok L. B. , Ash M. , Kyle P.
Published: August 2018

The level of lava within a volcanic conduit reflects the overpressure within a connected magma reservoir. Continuous monitoring of lava level can therefore provide critical insights into volcanic processes and aid hazard assessment. However, accurate measurements of lava level are not easy to make, partly owing to the often dense fumes that hinder optical techniques. Here we present the first radar instrument designed for the purpose of monitoring lava level and report on its successful operation at Erebus volcano, Antarctica. We describe the hardware and data‐processing steps followed to extract a time series of lava lake level, demonstrating that we can readily resolve ∼1 m cyclic variations in lake level that have previously been recognized at Erebus volcano. The performance of the radar (continuous, automated data collection in temperatures of around −30 °C) indicates the suitability of this approach for sustained automated measurements at Erebus and other volcanoes with lava lakes.
Comparison of Intraseasonal East Asian Winter Cold Temperature Anomalies in Positive and Negative Phases of the Arctic Oscillation
Authors: Song Lei , Wu Renguang
Published: August 2018

This study investigates the relationship between intraseasonal variations of the Arctic Oscillation (AO) and East Asian winter temperature. Based on the lead‐lag correlation between 30‐ and 60‐day band‐pass filtered daily AO index and regional mean surface temperature anomalies over eastern China, it is found that the cold temperature anomalies occur following both positive and negative AO phases with nearly the same probability. Composite analysis reveals prominent differences in surface temperature and tropospheric circulation anomalies between the two types of years. During the years when negative AO leads cold anomalies over East Asia, the AO‐related pressure anomalies extend to Eurasia, inducing an enhanced Siberian high with a large spatial coverage in midlatitude and high latitude; the midtropospheric wave train along the polar front jet takes an eastward path and induces the deepening of the East Asian trough; the resultant cold surface temperature anomalies affect a large region over East Asia. During the years when positive AO leads cold anomalies, the AO‐related pressure anomalies extend to North America and the high pressure anomalies over East Asia are located at midlatitudes with a relatively small spatial coverage; the midtropospheric wave train along the polar front jet takes a southward path over Asia, inducing the development of a trough over subtropical Asia with a supplementary contribution from a subtropical wave train; the resultant cold surface temperature anomalies influence inland East Asia with a relatively small extent. There appears to be a notable difference in the relationship between the stratospheric and tropospheric change between the two types of years.
B Vitamins and Their Congeners as Potential Drivers of Microbial Community Composition in an Oligotrophic Marine Ecosystem
Authors: Suffridge C. P. , Gómez‐Consarnau L. , Monteverde D. R. , Cutter L. , Arístegui J. , Alvarez‐Salgado X. A. , Gasol J. M. , Sañudo‐Wilhelmy S. A.
Published: August 2018

Determining the factors that influence marine microbial growth and community structure are critical for the understanding of global carbon cycling. Since the early twentieth century, it has been known that B vitamins play an important role in phytoplankton community dynamics. Limited oceanic dissolved B vitamin distributions indicate that these important coenzymes are present at picomolar levels, which could be too low to support maximal phytoplankton growth, and vast regions of the ocean exist where they are undetectable. Despite their importance, particulate B vitamin concentrations of field microbial populations are unknown. Here we report B vitamin concentrations measured in both the particulate and dissolved fractions, including multiple biochemically relevant B vitamin congeners. We establish their spatial distributions spanning distinct biogeographic and oceanographic regimes in the Mediterranean Sea and the Eastern Atlantic Ocean and show that all congeners are present both dissolved in seawater and in suspended particles. We observe that B vitamins cooccur in patches defined by regional biogeographic and oceanographic features. Additionally, distinct patterns of congener relative abundance in the dissolved and particulate pools provide insight to biological and chemical cycling of these compounds between and within the dissolved and particulate pools. Finally, linear model results demonstrate that model fits of microbial assemblages are strongest when they include both inorganic nutrients and dissolved B vitamin concentrations. We believe that these findings represent an advance in our understanding of B vitamin oceanographic distributions and point to interesting hypotheses of their influence on marine microbial ecology.
Characteristics and Discharge Processes of M Events With Large Current in Triggered Lightning
Authors: Zhang Yang , Zhang Yi Jun , Zheng Dong , Lu Weitao
Published: August 2018

Observations have been obtained of M events during triggered lightning flashes with a broadband very high frequency interferometer and measurements of electric field changes, channel‐base current, and high‐speed video. The current characteristics of 239 M events in 18 triggered lightning flashes are analyzed, and the discharge processes leading to large M currents are investigated. Sixty‐eight of the M events (28%) had peak currents exceeding 1 kA. The geometric average values of peak current, duration, 10–90% rise time, half peak width, charge transfer, interval from return stroke to M and background current are 2.358 kA, 0.627 ms,0.078 ms, 0.165 ms, 0.417 C, 2.172 ms, and 579 A, respectively. Compared to other M events, the M events with large peak current occurred closer in time to the preceding return stroke, and their corresponding current changes were more rapid. Three cases associated with the initiation processes of M events reveal that some large M events were initiated by fast positive streamers propagating away at a velocity of about 107 m/s followed by a possible recoil event, or by a dart leader while the channel of continuing current generated by previous leader still existed. It is found that a fast current pulse with 10–90% rise time of less than 300 μs is a necessary, but not sufficient, condition for the occurrence of large M events. The fast current pulse often corresponded to a low/close junction site.