bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of LEAP® 5000 Deadtime and Precision via Silicon Pre-Sharpened-Microtip™ Standard Specimens
Authors: Prosa Ty J , Oltman Edward 
Published: July 2021

AbstractAtom probe tomography (APT) is a technique that has expanded significantly in terms of adoption, dataset size, and quality during the past 15 years. The sophistication used to ensure ultimate analysis precision has not kept pace. The earliest APT datasets were small enough that deadtime and background considerations for processing mass spectrum peaks were secondary. Today, datasets can reach beyond a billion atoms so that high precision data processing procedures and corrections need to be considered to attain reliable accuracy at the parts-per-million level. This paper considers options for mass spectrum ranging, deadtime corrections, and error propagation as applied to an extrinsic-silicon standard specimen to attain agreement for silicon isotopic fraction measurements across multiple instruments, instrument types, and acquisition conditions. Precision consistent with those predicted by counting statistics is attained showing agreement in silicon isotope fraction measurements across multiple instruments, instrument platforms, and analysis conditions.
“They Proved to Be Very Good Sailors”: Slavery and Freedom in the South Sea
Authors: Walker Tamara J. 
Published: July 2021

AbstractThis article mines archival sources and published accounts from the late seventeenth and early eighteenth centuries to highlight the extent to which enslaved men, women, and children in the South Sea came into contact with British corsairs. It does so in ways that lend to three important observations: that people of African descent occupied a central role within the history of British corsair activity in the South Sea; that British corsair activity in the South Sea forms part of the history of the slave trade; and that there are important differences between British corsairs’ use of enslaved and free people of African descent in the South Sea as compared to the Atlantic World. The latter point, which rests on the recognition of the particular linguistic skills and geographic knowledge held by people of African descent in the South Sea and British corsairs' particular vulnerabilities, also provides a useful framework for future research on both the specificity of black life in the region and the meanings those skills and knowledge held for Africans and their descendants themselves.
A passive mechanism for decoupling energy storage and return in ankle–foot prostheses: A case study in recycling collision energy
Authors: Quraishi Hashim A. , Shepherd Max K. , McManus Leo , Harlaar Jaap , Plettenburg Dick H. , Rouse Elliott J. 
Published: July 2021

Abstract
Individuals with lower limb amputation experience reduced ankle push-off work in the absence of functional muscles spanning the joint, leading to decreased walking performance. Conventional energy storage and return (ESR) prostheses partially compensate by storing mechanical energy during midstance and returning this energy during the terminal stance phase of gait. These prostheses can provide approximately 30% of the push-off work performed by a healthy ankle–foot during walking. Novel prostheses that return more normative levels of mechanical energy may improve walking performance. In this work, we designed a Decoupled ESR (DESR) prosthesis which stores energy usually dissipated at heel-strike and loading response, and returns this energy during terminal stance, thus increasing the mechanical push-off work done by the prosthesis. This decoupling is achieved by switching between two different cam profiles that produce distinct, nonlinear torque–angle mechanics. The cams automatically interchange at key points in the gait cycle via a custom magnetic switching system. Benchtop characterization demonstrated the successful decoupling of energy storage and return. The DESR mechanism was able to capture energy at heel-strike and loading response, and return it later in the gait cycle, but this recycling was not sufficient to overcome mechanical losses. In addition to its potential for recycling energy, the DESR mechanism also enables unique mechanical customizability, such as dorsiflexion during swing phase for toe clearance, or increasing the rate of energy release at push-off.
Polarimetric Calibration and Spatio‐Temporal Polarimetric Distortion Analysis of UAVSAR PolSAR Data
Authors: Babu Arun , Kumar Shashi , Agrawal Shefali 
Published: July 2021

AbstractThe polarimetric distortions present in the polarimetric SAR (PolSAR) data sets leads to unexpected results from the polarimetric decomposition and classification models, which in turn result in the ground target misinterpretation. The most important polarimetric distortions in airborne PolSAR data sets are the channel imbalance and crosstalk. The minimization of these polarimetric distortions using polarimetric calibration techniques is very important to carry out the quantitative analysis using PolSAR data and time series analysis and to compare results between different sensors. In the current state of the art, the spatial variability of the polarimetric distortions at different slant‐range positions in the data set was not completely analyzed and also the temporal variability of the polarimetric distortions using multiple data sets needs to be more investigated. Therefore, the main objectives of this study were to develop an operational processor to perform the external polarimetric calibration of the L‐band Uninhibited Aerial Vehicle Synthetic Aperture Radar system and to analyze the spatio‐temporal behavior of the polarimetric distortions. The polarimetric distortion matrix (PDM) was formulated after considering the crosstalk and channel imbalance polarimetric distortions to derive the scattering matrix free from all kinds of polarimetric distortions from the observed scattering matrix. The Quegan, improved Quegan, and Ainsworth methods for polarimetric calibration were implemented to solve the PDM. The residual channel imbalance and crosstalk after polarimetric calibration were estimated to compare the calibration efficiency of these methods. After that, a spatio‐temporal analysis was carried out with several data sets to assess the spatio‐temporal behavior of these polarimetric distortions. The polarimetric signatures and the coherency matrix behavior of the trihedral corner reflectors were used to analyze the ground target characterization improvement after polarimetric calibration. The results obtained from this study revealed that the crosstalk is the major cause for the polarimetric distortions and the channel imbalance and phase bias present in the data sets were not high. From the spatio‐temporal analysis, it was found that the variability of these polarimetric distortions both in spatial and temporal domains was minimum and can be discarded without causing any considerable error in the polarimetric calibration process.
The 2019 Autumn Hot Drought Over the Middle‐Lower Reaches of the Yangtze River in China: Early Propagation, Process Evolution, and Concurrence
Authors: Liu Zhenchen , Zhou Wen 
Published: July 2021

AbstractHot droughts (i.e., concurrent droughts and hot anomalies) have drawn much attention recently, but current knowledge about early propagation and concurrence remains limited. The 2019 autumn severe hot drought (2019AHD) over the middle‐lower reaches of the Yangtze River (MLYR) is employed for process‐based analysis, while water vapor transport, heating budgets, and atmospheric dynamics are comprehensively investigated. The main achievements are as follows: (a) The 2019AHD over MLYR is not isolated and is related to early propagation from adjacent North China (NC) two months earlier. (b) Direct physical causes are explored. Drought evolution is related to anomalous water vapor transport dominated by low‐level cyclonic anomalies over the East China Sea. Concurrently, local low‐level hot anomalies over MLYR are related to amplified horizontal advection heating, while near‐surface warming is favored by decreased low cloud cover and enhanced downward shortwave radiation. (c) Regional‐scale concurrence of droughts and hot extremes might be understood by the combined effects of amplified subsidence (suppressing precipitation formation) and intensified low‐level divergence (reducing low cloud cover). (d) From a large‐scale dynamic perspective, early propagation and development of the 2019AHD are related to the southward shift and enhancement of the subsidence branch of meridional circulations. Meanwhile, intensity variation in 200 hPa cyclonic anomalies over MLYR corresponds well with local drought development, and the enhanced intensity at the time of drought occurrence is probably related to Silk Road Pattern–like wave train propagation over Eurasia. These insights can help us understand the mechanisms and detect early signals of hot droughts.
Mathematical Modeling and Numerical Simulation of Water‐Rock Interaction in Shale Under Fracturing‐Fluid Flowback Conditions
Authors: Chen Qiaoyun , Wang Fei 
Published: July 2021

AbstractWater‐rock interaction cannot be ignored for shale reservoirs with high‐salinity formation brine and complex rock composition, and stimulated by massive slick‐water fracturing treatment. However, there have been few studies on the flowback model fully coupled with different effects of water‐rock interaction. This paper presents the development of a coupled hydro‐chemical‐mechanical model for modeling water‐rock interaction in fractured shale during the post‐fracturing flowback period. The model considers distinguishing water‐rock interaction phenomena, that is, mineral dissolution, clay swelling and chemical osmosis, and accounts for multi‐phase flow in a fractured shale reservoir. The coupling and solution method and a numerical simulator were developed. Numerical simulation indicates that the swelling volume of clay minerals occupies the pores and leads to a decline in matrix porosity, while mineral dissolution increases both the matrix porosity and the solute concentration in the aqueous phase in matrix pores. Clay swelling mainly affects the shape of the porosity ratio profiles. The effect of mineral dissolution becomes increasingly stronger as flowback progresses. Mineral dissolution mainly affects the relative positions of the porosity ratio curves with the progress of flowback. The water‐rock interaction coupled flowback modeling and the numerical simulation results in this study quantify the effects of chemical osmosis, clay swelling and mineral dissolution. Results from this study provide new insights into the mechanisms of fracturing‐fluid flowback and value to flowback transient analysis.
The Consumption‐Based Carbon Emissions in the Jing‐Jin‐Ji Urban Agglomeration Over China's Economic Transition
Authors: Bai Yangchun , Zheng Heran , Shan Yuli , Meng Jing , Li Yuan 
Published: July 2021

AbstractSince the 2008 financial crisis, China has been undergoing an economic transition consisting of prioritizing green economic and sustainable development instead of rapid growth driven by large‐scale investment. However, there is still a lack of fine print on how subregional effort can contribute to national or full supply chain mitigation plans, especially downscaling to the city level. To bridge this knowledge gap, we selected Jing‐Jin‐Ji urban agglomeration, one of the economic centers but also featured by intensive emission for decades, to analyze the emission variance and driving forces from 2012 to 2015 as a case study. Based on the consumption accounting framework, the carbon emissions of Jing‐Jin‐Ji have decreased by 11.7 Mt CO2 in total over the study period, and most cities showed the similar descending trend. The driving forces show that the emission intensity and production structure have largely reduced Jing‐Jin‐Ji's total due to measurements of economic transition. For instance, Beijing has decreased by 28.7 Mt of emission reduction which led by declined emission intensity. By contrast, per capita demands and growth of its population were the primary forces to increase emissions. To conclude, although the mitigation achievement is undeniable, we should also note that the economic transition has not changed the uneven pattern of selected urban agglomeration so far.
Coral Ba/Ca Analysis Using ICP‐OES With an Ultrasonic Nebulizer
Authors: Watanabe Takaaki K. , Watanabe Tsuyoshi , Ohmori Kazuto , Yamazaki Atsuko 
Published: July 2021

AbstractThe barium/calcium ratio (Ba/Ca) in coral skeletons has been used as a proxy to understand river floods and oceanic upwelling in the tropics and subtropics for the past centuries. Here, we establish a new method for Ba/Ca analysis using inductively coupled plasma optical emission spectrometry (ICP‐OES), which has been widely used for coral proxy analyses and can save analysis time compared to other methods. We analyze Ba/Ca by combining an ultrasonic nebulizer with the intensity ratio calibration method to improve the signal intensity of Ba. Our method can determine Ba/Ca in samples with a Ca concentration of 9 mg/L with excellent analytical precision (<0.17 μmol/mol) using ICP‐OES.
Cycling of CO2 and N2 Along the Hikurangi Subduction Margin, New Zealand: An Integrated Geological, Theoretical, and Isotopic Approach
Authors: Epstein Gabe S. , Bebout Gray E. , Christenson Bruce W. , Sumino Hirochika , Wada Ikuko , Werner Cynthia , Hilton David R. 
Published: July 2021

AbstractWe present a quantitative assessment of the input and output of CO2 and N2 along the Hikurangi margin based on the chemical and stable isotope composition of sediments and basalts (from IODP 375), previously accreted metasedimentary rocks, and volcanic/hydrothermal gases (together with noble gas data for the latter). We compare these results with 3‐D thermo‐petrologic models for four lithologic structures, representing different plateau inputs. The model results indicate that 59%–85% of initially subducted C and 5%–12% of N is lost from the slab during metamorphism, with both volatiles being dominantly sourced from altered oceanic crust with some contribution from subducted sediment at the forearc‐arc transition (75–90 km depth). The δ13CVPDB and CO2/3He values for the arc gases range from −8.3 to −1.4‰ and 2 × 109 to 2.7 × 1011, indicating contributions from slab carbonate, organic C, and mantle C of 67%, 30%, and 3%, respectively. The δ15Nair and N2/36Ar values of arc gases are −1.0 to +2.3‰ and 1.54 × 104 to 1.9 × 105, indicating slab and mantle contributions of 74% and 26%. The δ13C signature of gases requires addition of organic C by tectonic erosion and/or shallow crustal assimilation. These calculations yield whole‐margin fluxes of 5.4–7.0 Tg/yr for CO2 and 0.0022–0.0057 Tg/yr for N2, corresponding to ∼2.2% and 1%–30% of the global CO2 and N2 flux from subaerial volcanoes worldwide (assuming no loss during transit). This unique assessment of volatile cycling could prove useful in refining regional and global estimates of volatile recycling efficiency.
Global Wave Hindcasts Using the Observation‐Based Source Terms: Description and Validation
Authors: Liu Qingxiang , Babanin Alexander V. , Rogers W. Erick , Zieger Stefan , Young Ian R. , Bidlot Jean‐Raymond , Durrant Tom , Ewans Kevin , Guan Changlong , Kirezci Cagil , Lemos Gil , MacHutchon Keith , Moon Il‐Ju , Rapizo Henrique , Ribal Agustinus , Semedo Alvaro , Wang Juanjuan 
Published: July 2021

AbstractGlobal wave hindcasts are developed using the third generation spectral wave model WAVEWATCH III with the observation‐based source terms (ST6) and a hybrid rectilinear‐curvilinear, irregular‐regular‐irregular grid system (approximately at ). Three distinct global hindcasts are produced: (a) a long‐term hindcast (1979–2019) forced by the ERA5 conventional winds and (b) two short‐term hindcasts (2011–2019) driven by the NCEP climate forecast system (CFS)v2 and the ERA5 neutral winds , respectively. The input field for ice is sourced from the Ocean and Sea Ice Satellite Application Facility (OSI SAF) sea‐ice concentration climate data records. These wave simulations, together with the driving wind forcing, are validated against extensive in‐situ observations and satellite altimeter records. The performance of the ST6 wave hindcasts shows promising results across multiple wave parameters, including the conventional wave characteristics (e.g., wave height and wave period) and high‐order spectral moments (e.g., the surface Stokes drift and mean square slope). The ERA5‐based simulations generally present lower random errors, but the CFS‐based run represents extreme sea states (e.g., m) considerably better. Novel wave parameters available in our hindcasts, namely the dominant wave breaking probability, wave‐induced mixed layer depth, freak wave indexes and wave‐spreading factor, are further described and briefly discussed. Inter‐comparisons of from the long‐term (41 years) wave hindcast, buoy measurements and two different calibrated altimeter data sets highlight the inconsistency in these altimeter records arising from different calibration methodology. Significant errors in the low‐frequency bins (period s) for both wave energy and directionality call for further model development.
Proof of concept study to develop a novel connectivity-based electric-field modelling approach for individualized targeting of transcranial magnetic stimulation treatment
Authors: Balderston Nicholas L. , Beer Joanne C. , Seok Darsol , Makhoul Walid , Deng Zhi-De , Girelli Tommaso , Teferi Marta , Smyk Nathan , Jaskir Marc , Oathes Desmond J. , Sheline Yvette I. 
Published: July 2021

AbstractResting state functional connectivity (rsFC) offers promise for individualizing stimulation targets for transcranial magnetic stimulation (TMS) treatments. However, current targeting approaches do not account for non-focal TMS effects or large-scale connectivity patterns. To overcome these limitations, we propose a novel targeting optimization approach that combines whole-brain rsFC and electric-field (e-field) modelling to identify single-subject, symptom-specific TMS targets. In this proof of concept study, we recruited 91 anxious misery (AM) patients and 25 controls. We measured depression symptoms (MADRS/HAMD) and recorded rsFC. We used a PCA regression to predict symptoms from rsFC and estimate the parameter vector, for input into our e-field augmented model. We modeled 17 left dlPFC and 7 M1 sites using 24 equally spaced coil orientations. We computed single-subject predicted ΔMADRS/HAMD scores for each site/orientation using the e-field augmented model, which comprises a linear combination of the following elementwise products (1) the estimated connectivity/symptom coefficients, (2) a vectorized e-field model for site/orientation, (3) rsFC matrix, scaled by a proportionality constant. In AM patients, our connectivity-based model predicted a significant decrease depression for sites near BA9, but not M1 for coil orientations perpendicular to the cortical gyrus. In control subjects, no site/orientation combination showed a significant predicted change. These results corroborate previous work suggesting the efficacy of left dlPFC stimulation for depression treatment, and predict better outcomes with individualized targeting. They also suggest that our novel connectivity-based e-field modelling approach may effectively identify potential TMS treatment responders and individualize TMS targeting to maximize the therapeutic impact.
Microbial drivers of methane emissions from unrestored industrial salt ponds
Authors: Zhou Jinglie , Theroux Susanna M , Bueno de Mesquita Clifton P , Hartman Wyatt H , Tian Ye , Tringe Susannah G 
Published: July 2021

AbstractWetlands are important carbon (C) sinks, yet many have been destroyed and converted to other uses over the past few centuries, including industrial salt making. A renewed focus on wetland ecosystem services (e.g., flood control, and habitat) has resulted in numerous restoration efforts whose effect on microbial communities is largely unexplored. We investigated the impact of restoration on microbial community composition, metabolic functional potential, and methane flux by analyzing sediment cores from two unrestored former industrial salt ponds, a restored former industrial salt pond, and a reference wetland. We observed elevated methane emissions from unrestored salt ponds compared to the restored and reference wetlands, which was positively correlated with salinity and sulfate across all samples. 16S rRNA gene amplicon and shotgun metagenomic data revealed that the restored salt pond harbored communities more phylogenetically and functionally similar to the reference wetland than to unrestored ponds. Archaeal methanogenesis genes were positively correlated with methane flux, as were genes encoding enzymes for bacterial methylphosphonate degradation, suggesting methane is generated both from bacterial methylphosphonate degradation and archaeal methanogenesis in these sites. These observations demonstrate that restoration effectively converted industrial salt pond microbial communities back to compositions more similar to reference wetlands and lowered salinities, sulfate concentrations, and methane emissions.
Anillin propels myosin-independent constriction of actin rings
Authors: Kučera Ondřej , Siahaan Valerie , Janda Daniel , Dijkstra Sietske H. , Pilátová Eliška , Zatecka Eva , Diez Stefan , Braun Marcus , Lansky Zdenek 
Published: July 2021

AbstractConstriction of the cytokinetic ring, a circular structure of actin filaments, is an essential step during cell division. Mechanical forces driving the constriction are attributed to myosin motor proteins, which slide actin filaments along each other. However, in multiple organisms, ring constriction has been reported to be myosin independent. How actin rings constrict in the absence of motor activity remains unclear. Here, we demonstrate that anillin, a non­motor actin crosslinker, indispensable during cytokinesis, autonomously propels the contractility of actin bundles. Anillin generates contractile forces of tens of pico-Newtons to maximise the lengths of overlaps between bundled actin filaments. The contractility is enhanced by actin disassembly. When multiple actin filaments are arranged into a ring, this contractility leads to ring constriction. Our results indicate that passive actin crosslinkers can substitute for the activity of molecular motors to generate contractile forces in a variety of actin networks, including the cytokinetic ring.
Mechanistic insights into the three steps of poly(ADP-ribosylation) reversal
Authors: Rack Johannes Gregor Matthias , Liu Qiang , Zorzini Valentina , Voorneveld Jim , Ariza Antonio , Honarmand Ebrahimi Kourosh , Reber Julia M. , Krassnig Sarah C. , Ahel Dragana , van der Marel Gijsbert A. , Mangerich Aswin , McCullagh James S. O. , Filippov Dmitri V. , Ahel Ivan 
Published: July 2021

AbstractPoly(ADP-ribosyl)ation (PAR) is a versatile and complex posttranslational modification composed of repeating units of ADP-ribose arranged into linear or branched polymers. This scaffold is linked to the regulation of many of cellular processes including the DNA damage response, alteration of chromatin structure and Wnt signalling. Despite decades of research, the principles and mechanisms underlying all steps of PAR removal remain actively studied. In this work, we synthesise well-defined PAR branch point molecules and demonstrate that PARG, but not ARH3, can resolve this distinct PAR architecture. Structural analysis of ARH3 in complex with dimeric ADP-ribose as well as an ADP-ribosylated peptide reveal the molecular basis for the hydrolysis of linear and terminal ADP-ribose linkages. We find that ARH3-dependent hydrolysis requires both rearrangement of a catalytic glutamate and induction of an unusual, square-pyramidal magnesium coordination geometry.