bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismicity Structure of the Northern Chile Forearc From >100,000 Double‐Difference Relocated Hypocenters
Authors: Sippl C. , Schurr B. , Asch G. , Kummerow J. 
Published: April 2018

AbstractIn this study, we present high‐resolution seismicity images of the northern Chile subduction zone forearc. We used 8 years of continuous seismic waveform data from the Integrated Plate Boundary Observatory Chile network and auxiliary stations to produce an extensive earthquake catalog containing 101,601 double‐difference relocated earthquake hypocenters using automatic event detection and phase picking routines. The minimum magnitude of retrieved events is <2, and the catalog is estimated to be complete at magnitudes above ∼2.8. Intraslab seismicity makes up the majority of detected earthquakes. Where the seismogenic zone of the megathrust is active, a clear separation of seismicity into three distinct planes can be observed. The uppermost plane corresponds to the plate interface, which is observed to terminate downdip at a depth of 50–55 km. The other two planes, located ∼7 and ∼26 km below the slab surface, dip at a constant angle of about 20° until they are absorbed by a 25 km thick highly active cluster of intermediate‐depth seismicity at depths of 80–120 km. Downdip of this cluster, the slab steepens and lower plate seismicity is considerably sparser, even absent in the northern part of the study area. Upper plate seismicity is also considerable, with a segment between 21 and 21.6°S standing out for featuring pervasive activity occurring all the way down to the plate interface. Here the seismicity resembles a wedge in west‐east profile view and occurs where the upper plate crust is coldest based on thermal models.
Gulf Stream Transport and Mixing Processes via Coherent Structure Dynamics
Authors: Liu Yi , Wilson Chris , Green Melissa A. , Hughes Chris W. 
Published: April 2018

AbstractThe Gulf Stream has been characterized as either a barrier or blender to fluid transfer, a duality relevant to gyre‐scale climate adjustment. However, previous characterization depended on relatively sparse, Lagrangian in situ observations. The finite‐time Lyapunov exponent (FTLE) is calculated from satellite altimetry to identify Lagrangian coherent structures (LCS) in the Gulf Stream region. These LCS provide dense sampling of flow and capture distinct regions associated with mixing. Independent observations of ocean color contain similar flow‐dependent structures, providing verification of the method and highlighting transport and mixing processes that influence sea surface temperature and chlorophyll, among other water properties. Diagnosed LCS support the existing Bower kinematic model of the Gulf Stream, but also highlight novel behavior of comparable importance. These include vortex pinch‐off and formation of spiral eddies, clearly identified by LCS and which may be explained by considering changes to flow topology and the dynamics of shear‐flow instability at both small and large Rossby number. Such processes, seen though LCS, may further enable validation of climate models. The spatial distribution of these intermittent processes is characterized in terms of the criticality of jet dynamics with respect to Rossby wave propagation, and whether the jet is in an unstable or wave‐maker regime. The generation and connectivity of hyperbolic trajectories in the flow appears to play an important role in governing large‐scale transport and mixing across the Gulf Stream.
Indo‐Atlantic Exchange, Mesoscale Dynamics, and Antarctic Intermediate Water
Authors: Capuano Tonia Astrid , Speich Sabrina , Carton Xavier , Laxenaire Remi 
Published: April 2018

AbstractThis study evaluates the capability of eddy‐permitting regional ocean models to reproduce the interocean exchange south of Africa. In this highly turbulent region, we show that the vertical structure of the horizontal flows need to be appropriately resolved to realistically advect thermocline water masses into the South Atlantic. Our results point out that a grid‐spacing of 1/24° on the horizontal and 50 m on the vertical homogeneously distributed are required to account for a correct transport of surface and subsurface water masses properties and their in‐route transformation by mixing. Preliminary Lagrangian analyses highlight the primary role of the upper‐ocean mesoscale eddies on water masses transport and fate, with a particular emphasis on Antarctic Intermediate Waters (AAIWs) dynamics and characteristics. We evaluate the numerical results against observations (AVISO data and Argo floats profiles). Modeled and observed eddies were examined in number, polarity, size, trajectory, and for their contribution to AAIW properties. A clear asymmetry, in number and radius, emerges between cyclones and anticyclones. The high‐resolution simulation was the most energetic, with more abundant and smaller structures than those detected in AVISO. However, eddy statistics compare reasonably well in terms of mean pathways when restricted to Agulhas Rings, which are on average quasi‐Gaussian in shape. Regionally, the Ertel potential vorticity anomaly is marked at the surface by a temporal variability with winter intensification, directly reflected in the seasonal cycle of the eddies number. Noting the growth of the baroclinic Rossby radius in winter, this suggests baroclinic processes as essential for these eddies generation.
Exploring the Utility of IASI for Monitoring Volcanic SO2 Emissions
Authors: Taylor Isabelle A. , Preston James , Carboni Elisa , Mather Tamsin A. , Grainger Roy G. , Theys Nicolas , Hidalgo Silvana , Kilbride Brendan McCormick 
Published: April 2018

AbstractSatellite remote sensing is a valuable method for detecting and quantifying sulfur dioxide (SO2) emissions at volcanoes. The use of ultraviolet satellite instruments for monitoring purposes has been assessed in numerous studies, but there are advantages to using infrared measurements, including that they can operate at night and during high‐latitude winters. This study focuses on the Infrared Atmospheric Sounding Interferometer (IASI). Retrievals developed for this instrument have been shown to be successful when applied to large eruptions, but little has been done to explore their potential for detecting and quantifying emissions from smaller and lower altitude emissions or for the assessment of ongoing activity. Here a “fast” linear retrieval has been applied across the globe to detect volcanic sources of SO2. The results are dominated by emissions from explosive eruptions, but signals are also evident from weak eruptions, passive degassing, and anthropogenic activity. Ecuador and Kamchatka were selected for further study with a more processing intensive iterative retrieval which can quantify the SO2 amount. At Tungurahua in Ecuador, good agreement was seen between IASI, the Ozone Monitoring Instrument (OMI) and ground‐based flux data, demonstrating that the retrieval is capable of capturing relative changes in activity. Similarly, good agreement was found between IASI and OMI in Kamchatka. In this high‐latitude region, OMI is unable to operate for 3 or 4 months in each year. It is therefore suggested that IASI could be used alongside other instruments for evaluating changes in volcanic activity.
Explaining the Year‐to‐Year Variability of the Eastern Pacific Intertropical Convergence Zone in the Boreal Spring
Authors: Yu Haiyang , Zhang Minghua 
Published: April 2018

AbstractThe year‐to‐year variability of the Intertropical Convergence Zone (ITCZ) in the eastern tropical Pacific is a significant phenomenon of the tropical climate system. Asymmetric interannual variation of precipitation on two sides of the Equator is often observed there in the boreal spring. We introduce a simple normalized asymmetric index and a double ITCZ index as well as a hierarchical clustering method to describe the ITCZ variation based on the tropical boreal spring precipitation from 1979 to 2017. We show that the indices and the clustering method give consistent categorization of asymmetric ITCZ variation. We find that the asymmetry of precipitation can be explained by the remote impact of the interannual variability of the central Pacific sea surface temperature (SST) on the horizontal gradient of surface pressure and surface wind convergence, especially the Modoki mode. The central Pacific SST also remotely modulates free‐tropospheric temperature and vertical stability in the eastern equatorial Pacific, but this remote impact is secondary to the wind convergence. Interannual variability of local SST south of the Equator plays little role in the precipitation variability, which is supported by numerical experiments with a regional atmospheric model. Results imply that surface wind convergence should be considered in convection schemes to improve the simulation of precipitation in the eastern tropical Pacific in climate models.
Zonally Symmetric Oscillations of the Thermosphere at Planetary Wave Periods
Authors: Forbes Jeffrey M. , Zhang Xiaoli , Maute Astrid , Hagan Maura E. 
Published: April 2018

AbstractNew mechanisms for imposing planetary wave (PW) variability on the ionosphere‐thermosphere system are discovered in numerical experiments conducted with the National Center for Atmospheric Research thermosphere‐ionosphere‐electrodynamics general circulation model. First, it is demonstrated that a tidal spectrum modulated at PW periods (3–20 days) entering the ionosphere‐thermosphere system near 100 km is responsible for producing ±40 m/s and ±10–15 K PW period oscillations between 110 and 150 km at low to middle latitudes. The dominant response is broadband and zonally symmetric (i.e., “S0”) over a range of periods and is attributable to tidal dissipation; essentially, the ionosphere‐thermosphere system “vacillates” in response to dissipation of the PW‐modulated tidal spectrum. In addition, some specific westward propagating PWs such as the quasi‐6‐day wave are amplified by the presence of the tidal spectrum; the underlying mechanism is hypothesized to be a second‐stage nonlinear interaction. The S0 total neutral mass density (ρ) response at 325 km consists of PW period fluctuations of order ±3–4%, roughly equivalent to the day‐to‐day variability associated with low‐level geomagnetic activity. The variability in ρ over short periods (∼< 9 days) correlates with temperature changes, indicating a response of hydrostatic origin. Over longer periods ρ is also controlled by composition and mean molecular mass. While the upper‐thermosphere impacts are modest, they do translate to more significant changes in the F region ionosphere.
Low‐Level Baroclinic Jets Over the New Arctic Ocean
Authors: Guest Peter , Persson P. Ola G. , Wang Shouping , Jordan Mary , Jin Yi , Blomquist Byron , Fairall Christopher 
Published: April 2018

AbstractDuring the Sea State cruise in the fall of 2015, in the Chukchi/Beaufort Sea region, there were five strong (>10 m s−1) surface wind events associated with low‐level atmospheric jets. These jets were analyzed using rawinsonde observations, ship measurements, and a numerical forecast model. The jets occurred when easterly winds aligned with the ice edge, generating low‐level baroclinicity in a direction favorable for increasing the geostrophic wind speed toward the surface. The maximum wind speed usually occurred at the top of the atmospheric boundary layer with wind speeds greater than 8 m s−1 extending through the capping inversion to 2,000–3,000 m elevation, with winds decreasing toward the surface in the boundary layer due to friction. The width (crosswind) dimensions of the jets were 250–400 km and they existed downwind for as long as the winds remained generally parallel to the ice edges, typically several hundred kilometers. Thermal winds calculated from crosswind‐oriented rawinsonde temperature profiles matched the observed vertical wind speed gradients in the inversion regions, indicating that the jets were in quasi‐geostrophic (inversion layer) or quasi‐frictional (boundary layer) balance, with low Rossby numbers. We define these as “baroclinic” type jets, which are distinct from “ice/sea breeze” type jets which flow more down the pressure and density gradients, and have high Rossby numbers. The operational model analyses matched the observations quite well, giving confidence that these types of jets can be simulated and predicted as long as the models have sufficient resolution and accurately parameterize vertical heat fluxes.
Entrainment and Energy Transfer Variability Along the Descending Path of the Denmark Strait Overflow Plume
Authors: North Ryan P. , Jochumsen Kerstin , Moritz Martin 
Published: April 2018

AbstractThe descent of the Denmark Strait overflow plume is an important process in the Atlantic Meridional Overturning Circulation. Downstream of the sill, the plume entrains ambient water, increasing its volume transport. The entrainment and related transfer of energy can be driven by vertical or horizontal turbulent mixing, and varies spatially, as the plume descends, and temporally, as the volume transport at the sill changes. Using over 30 years of profile data, this spatial and temporal variability in the first 200 km downstream of the sill was investigated. Dissipation and entrainment rates were derived from Thorpe scales, and each profile was identified as either a low‐ or high‐transport flow, defined as below or above‐average volume transport at the sill. In the first 175 km flow type explains most of the variability in entrainment and dissipation rates, with high‐transport flow producing order of magnitude higher rates. Sections crossing the plume and yo‐yo casts (continuous profiling) indicate that dissipation and entrainment are likely driven by the formation of shear instabilities in the interfacial layer, when the vertical velocity shear overcomes the stratification. This vertical turbulent mixing explains most of the variability within the first 175 km, suggesting horizontal turbulent mixing processes may not play as important a role in this region. The importance of temporal flow variability means that further improvements to our understanding of plume dynamics in the Denmark Strait will require a novel observational approach to fully account for spatial and temporal contributions.
Perception and Action
Authors: Witt Jessica K. 
Published: April 2018

AbstractTheories of perception and action challenge the current mainstream model of the mind that processing is sequential from perceiving to thinking to acting. Three challenges of this model are that action is often for the purpose of perception, perception depends on action, and perception and action share a common currency. Many actions are taken with the purpose of enriching the information for perception—making action the start, rather than the end, of mental processing. Perception depends on action, as demonstrated by the role for action in perceptual development, perception of biological motion, spatial perception, and perhaps all of perception, according to Gibson's ecological approach. In turn, actions are learned, selected, and controlled by their perceptual outcomes, thus making perception and action share a common language with each other. Action and perception should be considered in relation to each other.
Perceptual Organization
Authors: Wagemans Johan 
Published: April 2018

AbstractPerceptual organization is the process of giving structure to our experience of objects, scenes, and events in the world. The literature on this complex and fascinating topic is huge, dealing with a wide range of phenomena, processes, neural mechanisms, models, and theories. The present overview starts from the seminal work by the Gestalt psychologists, covering the classic laws of perceptual grouping and figure–ground organization. Then follows a review of the main lines of psychophysical and neural research carried out on these and related topics in the past 50 years. The final section covers new directions of research. They refine the conceptual framework and sketch theoretical approaches that could offer interesting alternatives to the mainstream view of information processing in the cortical hierarchy. There is hope for a synthesis to emerge from this scattered field of research, leading to a better understanding of perceptual organization.
Models and Methods for Reinforcement Learning
Authors: Dayan Peter , Nakahara Hiroyuki 
Published: April 2018

AbstractAdaptive behavior requires learning predictions of rewards and punishments, and learning actions that increase the chance or magnitude of the former and avoid the latter. This is the purview of many fields; we consider it in the context of reinforcement learning, which was spawned by behavioral psychology and artificial intelligence, but now also encompasses a wealth of findings in neuroscience. We consider the foundational algorithms of reinforcement learning, such as direct and indirect actors, temporal difference learning, ‐learning and the actor‐critic, discuss aspects of their links to sophisticated ideas from conditioning, and hint at the geography of the main aspects of the terrain that is currently being explored.
Open Science
Authors: Spellman Barbara A. , Gilbert Elizabeth A. , Corker Katherine S. 
Published: April 2018

AbstractOpen science is a collection of actions designed to make scientific processes more transparent and results more accessible. Its goal is to build a more replicable and robust science; it does so using new technologies, altering incentives, and changing attitudes. The current movement toward open science was spurred, in part, by a recent series of unfortunate events within psychology and other sciences. These events include the large number of studies that have failed to replicate and the prevalence of common research and publication procedures that could explain why. Many journals and funding agencies now encourage, require, or reward some open science practices, including preregistration, providing full materials, posting data, distinguishing between exploratory and confirmatory analyses, and running replication studies. Individuals can practice and promote open science in their many roles as researchers, authors, reviewers, editors, teachers, and members of hiring, tenure, promotion, and awards committees. A plethora of resources are available to help scientists, and science, achieve these goals.
The N‐Methylpyrrolidone (NMP) Effect in Iron‐Catalyzed Cross‐Coupling with Simple Ferric Salts and MeMgBr
Authors: Muñoz Salvador B. , Daifuku Stephanie L. , Sears Jeffrey D. , Baker Tessa M. , Carpenter Stephanie H. , Brennessel William W. , Neidig Michael L. 
Published: April 2018

AbstractThe use of N‐methylpyrrolidone (NMP) as a co‐solvent in ferric salt catalyzed cross‐coupling reactions is crucial for achieving the highly selective, preparative scale formation of cross‐coupled product in reactions utilizing alkyl Grignard reagents. Despite the critical importance of NMP, the molecular level effect of NMP on in situ formed and reactive iron species that enables effective catalysis remains undefined. Herein, we report the isolation and characterization of a novel trimethyliron(II) ferrate species, [Mg(NMP)6][FeMe3]2 (1), which forms as the major iron species in situ in reactions of Fe(acac)3 and MeMgBr under catalytically relevant conditions where NMP is employed as a co‐solvent. Importantly, combined GC analysis and 57Fe Mössbauer spectroscopic studies identified 1 as a highly reactive iron species for the selective formation generating cross‐coupled product. These studies demonstrate that NMP does not directly interact with iron as a ligand in catalysis but, alternatively, interacts with the magnesium cations to preferentially stabilize the formation of 1 over [Fe8Me12]− cluster generation, which occurs in the absence of NMP.
Catalytic Asymmetric Dearomatization by Visible‐Light‐Activated [2+2] Photocycloaddition
Authors: Hu Naifu , Jung Hoimin , Zheng Yu , Lee Juhyeong , Zhang Lilu , Ullah Zakir , Xie Xiulan , Harms Klaus , Baik Mu‐Hyun , Meggers Eric 
Published: April 2018

AbstractA novel method for the catalytic asymmetric dearomatization by visible‐light‐activated [2+2] photocycloaddition with benzofurans and one example of a benzothiophene is reported, thereby providing chiral tricyclic structures with up to four stereocenters including quaternary stereocenters. The benzofurans and the benzothiophene are functionalized at the 2‐position with a chelatingN‐acylpyrazole moiety which permits the coordination of a visible‐light‐activatable chiral‐at‐rhodium Lewis acid catalyst. Computational molecular modeling revealed the origin of the unusual regioselectivity and identified the heteroatom in the heterocycle to be key for the regiocontrol.
A Perioperative Approach to Increase Limb Salvage When Treating Foot Ulcers in Patients With Diabetes
Authors: Howell Raelina S. , Criscitelli Theresa , Woods Jon S. , Gillette Brian M. , Brem Harold , Gorenstein Scott 
Published: April 2018

ABSTRACTFoot ulceration in patients with diabetes increases the risk of lower extremity amputation. Major amputations produce substantial adverse consequences, increase length of hospital stay, diminish quality of life, and increase mortality. In this article, we describe approaches that decrease amputations and improve the quality of life for patients with diabetes and foot ulcers. We highlight the role of the perioperative nurse, who is essential to providing optimal patient care in the perioperative period. Perioperative care of patients with diabetes involves providing optimal surveillance for a break in the skin of the foot, screening for neuropathy, following guidelines for foot ulcer infections, preparing for pathophysiology‐based debridement, using adjuvant therapies, and offloading the patient's affected foot. Nurses should understand the disease process and pathophysiology and how to use these approaches in the perioperative setting to assist in curtailing the morbidity and mortality associated with foot ulcers in patients with diabetes.
Pediatric Perioperative Nurses and the Ethics of Organ Donation After Cardiac Death
Authors: Austin Elizabeth A. , Lovett Pamela , Moore Wendy C. , Zuzarte Ingrid 
Published: April 2018

AbstractPediatric perioperative nurses are experiencing increased opportunities to participate in donations after cardiac death. An increased public awareness regarding transplantation has inspired more people to donate than in previous years. The demand for transplantable organs has led to opportunities that have increased donor candidates including living donors and cardiac death donors. Cardiac death in children is often sudden and unexpected, and is an emotional time not only for the family members but also for the hospital staff members, including perioperative nurses. However, when perioperative nurses adhere to standards and guidelines, they can perform their responsibilities in an ethical and compassionate manner and assist their team in doing so. This article reviews the guiding principles of pediatric organ donation after cardiac death, the phases of the process, and the ethical and moral issues surrounding donation.