bluuebunny/crossref_metadata_2025 huggingface dataset:
An assessment of child care facility playground surfacing safety in Calgary, Alberta
Authors: East Dana , Gustafson Karla , Cabaj Jason , Navratil Lynne
Published: March 2018

Absorption capacity of playground surfaces is a well-recognized factor in injury prevention as most playground injuries result from falls on playground surfaces. In the past, Environmental Health Officers had no way of evaluating impact absorption of playground surfaces so injury prevention capacities of surfacing were unknown. To assess injury prevention characteristics of playground surfaces in the Calgary Zone, Environmental Public Health began testing surfaces in 2012 with a Triax Surface Impact Tester. A total of 102 playground surfaces were tested to the end of 2016. Forty-five (44%) playgrounds failed the impact absorption test, indicating falls from the equipment onto these surfaces could result in a life-threatening head injury. These findings suggest a large percentage of playground surfaces are not providing adequate fall safety. Playground owners/operators require additional knowledge and resources to inform decisions about playground surfacing, and changes to public health legislation should be considered to require formal assessment of playgrounds and ensure playground surfacing is addressed in a consistent manner.
Module 9: Production
Authors: Stranack Kevin , Frederiksen Niels Erik
Published: March 2018

Production
Module 10: Issue Management
Authors: Stranack Kevin , Frederiksen Niels Erik
Published: March 2018

Issue Management

Kevin Stranack (Author) Niels Erik Frederiksen (Editor)
”For mine børns skyld”: Affektiv cirkulation af risiko, ansvar og køn i BRCA genetisk udredning
Authors: Youssufi Anne Vestergaard , Huniche Lotte
Published: March 2018

Genetisk udredning benyttes i stigende grad af raske mennesker, som er i risiko for at udvikle alvorlige eller livstruende sygdomme. Nogle tilfælde af brystkræft og kræft i æggestokke og æggeledere, skyldes en mutation i et af de to BRCA-gener og kan forårsage tidlig sygdom og død. Gennem interviews med kvinder der er testet positive for en BRCA mutation, og med en genetisk rådgiver, udforsker artiklen, hvilken rolle affekter og køn har i den genetiske rådgivningsproces og for valg af testning og profylaktisk kirurgi. Analysen viser, at især frygt cirkulerer bredt og klistrer til mange af kvindernes familiemedlemmer både før, under og efter testning. For kvinder, og særligt for mødre, accelererer den affektive cirkulation af frygt, når den kædes sammen med deres egen og andres forventninger om, at kvinder, for at være omsorgsfulde og beskytte deres familie, må håndtere deres genetiske risiko, ved at gøre brug af de tilbud, som den medicinske genetik stiller til rådighed. Selvom genetisk rådgivning praktiseres som ikke-direktiv og ud fra principper om delt beslutningstagen, virker den udbredte forestilling om, at man kan få viden om sine gener og træffe beslutninger på den baggrund, som begrundelse for at opfatte genetisk testning og profylaktisk kirurgi, som den ansvarlige måde for kvinder at håndtere risiko. Kønnede forestilling om kvinders og mødres udvidede ansvar, lagt oveni den medicinske genetiks muligheder, virker disciplinerende på kvindernes valg af testning og profylaktisk kirurgi, for familiemedlemmers, og især for deres børns skyld, også selvom det har omfattende konsekvenser for deres egne kroppe og liv.
Efterskælv. Pejlinger af terrorfrygtens anatomi
Authors: Laustsen Carsten Bagge
Published: March 2018

Spørgsmålet om frygtens betydning for det politiske er omtrent lige så gammelt som spørgsmålet om den politiske magt. Den italienske renæssancefilosof Niccolo Machiavelli fortalte fx sin fyrste i Firenze Lorenzo di Piero de’ Medici, at det var bedre at blive frygtet end elsket – altså hvis man ikke kunne være begge dele (Machiavelli 1999: 53ff). Folket ville til hver en tid foretrække en rå, barsk og handlekraftig leder frem for en blid, gavmild og dannet. Og det er ifølge Machiavelli sådan, fordi folk primært har én bekymring, og det er frygten for at miste deres liv. Den stærke leder skulle stå i spidsen for bystatens forsvar, og her trumfede magt og handlekraft det finkulturelle raffinement, som de italienske eliter ellers lod sig definere ved. Der var nogen, de frygtede mere end deres leder, og det var bystatens fjender.
La réflexivité et les géographes français au XXe siècle. D’une approche historique à une approche épistémologique
Authors: Lefort Isabelle , Péaud Laura
Published: March 2018

Au cours du XXesiècle, les géographes français ont fait leurs des démarches et explicitations réflexives qui corrélativement ont vu sensiblement évoluer leurs places et leurs statuts dans la production disciplinaire. Cessant d’en être un angle mort, ces démarches ont été dotées d’un outillage conceptuel et méthodologique, leur assurant aujourd’hui visibilité et reconnaissance dans le champ des études géographiques. Passant d’un projet d’histoire de la discipline à un projet plus explicitement épistémologique, les modalités de l’écriture réflexive géographique participent aujourd’hui d’une nouvelle forme d’habitus disciplinaire mobilisant de nouveaux objets, questionnements et méthodes.
Gymnastique épistémologique, critique et réflexive : la construction d’une recherche en « ex-Yougoslavie » face à la colonialité du savoir
Authors: Blondel Cyril
Published: March 2018

Cet article tente de retracer une histoire, celle de l’évolution de ma propre réflexivité durant le temps d’une thèse intitulée « Aménager les frontières des périphéries européennes. La frontière Serbie/Croatie à l’épreuve des injonctions à la coopération et à la réconciliation » (thèse de doctorat, Tours, Université François-Rabelais, 2016). Mon propos ici est de rendre compte d’une conviction, la nécessité de s’engager dans une démarche réflexive et critique avant, pendant et après la production de la recherche en elle-même. Cet article constitue ainsi une tentative de démonstration par l’exemple de l’intérêt d’une telle posture. Je vise, d’une part, à exposer comment j’ai construit mes réflexions épistémologiques, par une déconstruction progressive des cadres théoriques classiques (nationalistes, post-socialiste, post-yougoslave) choisis ou imposés. D’autre part, j’expose les aboutissements de cette réflexivité, c’est-à-dire principalement ma prise de conscience de la colonialité du savoir (et du mien en particulier). Cette gymnastique m’a permis de parfois dépasser certaines limites de mon travail, et plus souvent d’en rendre compte, mais aussi d’accepter l’indépassable lié à certains aspects de ma situation de recherche, de la manière dont je l’ai énoncée et conduite. Mener ce type d’exercice et en rendre compte contribuent alors à mieux préciser les conditions de validité scientifique de ces travaux, à mieux situer le propos et l’apport du chercheur, sa position et donc sa positionalité.
Réflexivité et recherche-action en contrat CIFRE, quand les contraintes du terrain deviennent opportunités
Authors: Rouchi Camille
Published: March 2018

Cet article propose de communiquer sur un retour d’expérience et d’engager une réflexion sur la réalisation d’une recherche critique en sciences humaines financée par son terrain de recherche. L’ambition est ainsi d’adopter un double point de vue : celui de l’universitaire et du professionnel. Cette posture n’étant pas sans inconvénient puisqu’elle implique de se poser la question à la fois des attentes et des besoins du monde professionnel et scientifique dans le cadre de ce qui relève de la recherche-action. Être engagé par son terrain, c’est se confronter à la contradiction des temporalités et de multiples intérêts. Nous verrons que l’élaboration de l’objet de recherche, l’obtention des données et les modalités de restitution, interpelle la nécessité d’adopter un point de vue réflexif et pour le chercheur de transformer les contraintes en opportunités.
Joaquim Martí Mestre, «Diccionari de fraseologia (segles XVII-XXI)», València, PUV / PUA / AVL / Institut Alfons el Magnànim, 2017, 1848 pp.
Authors: Reig Eugeni S.
Published: March 2018

Ressenya sobre el llibre de Joaquim Martí Mestre, «Diccionari de fraseologia (segles XVII-XXI)». Pròleg d’Antoni Ferrando. València, Publicacions de la Universitat de València / Publicacions de la Universitat d’Alacant / Acadèmia Valenciana de la Llengua / Institut Alfons el Magnànim («Biblioteca Lingüística Catalana», 32), 2017, 1848 pp., ISBN: 978-84-9134-007-2.
Quantitative trait loci associated with soft wheat quality in a cross of good by moderate quality parents
Authors: Garcia-Santamaria Gioconda , Hua Duc , Sneller Clay
Published: March 2018

Information on the genetic control of the quality traits of soft wheat (Triticum aestivum) is essential for breeding. Our objective was to identify QTL associated with end-use quality. We developed 150 F4-derived lines from a cross of Pioneer 26R46 × SS550 and tested them in four environments. We measured flour yield (FY), softness equivalent (SE), test weight (TW), flour protein content (FP), alkaline water retention capacity (AWRC), and solvent retention capacity (SRC) of water (WA), lactic acid (LA), sucrose (SU), sodium carbonate (SO). Parents differed for nine traits, transgressive segregants were noted, and heritability was high (0.67 to 0.90) for all traits. We detected QTL distributed on eight genomic regions. The QTL with the greatest effects were located on chromosome 1A, 1B, and 6B with each affecting at least five of ten quality traits. Pioneer 26R46 is one of the best quality soft wheats. The large-effect QTL on 1A novel and accounted for much of the variation for AWRC (r2 = 0.26), SO (0.26) and SE (0.25), and FY (0.15) and may explain why Pioneer 26R46 has such superior quality. All alleles that increased a trait came from the parent with the highest trait value. This suggests that in any population that marker-assisted selection for these quality traits could be conducted by simply selecting for the alleles at key loci from the parent with the best phenotype without prior mapping.
Spectral bimodality of waves produced by hurricanes in the Caribbean coastal zone off Mexico
Authors: Martell-Dubois Raúl , Silva-Casarin Rodolfo , Mendoza-Baldwin Edgar G , Muñoz-Pérez Juan J , Cerdeira-Estrada Sergio , Escalante-Mancera Edgar , Laiz Irene
Published: March 2018

Wave data collected near the Caribbean coast of Mexico were used to study the frequency and directional structure of the wave field that was generated during the passing of 3 hurricanes. The data were recorded with 2 different acoustic wave gauges, which were installed at a depth of about 20 m. These records provided 183 directional wave spectra corresponding to the occurrence of hurricanes Wilma (October 2005), Dean (August 2007) and Rina (October 2011). The simultaneity of wind waves and swell was detected from different directions, due to the presence of bimodal spectra. For the 3 events, the relation between the translational speed of hurricanes and wave group celerity can explain the presence or absence of spectral bimodality, in either frequency or direction.
ISUAL‐Observed Blue Luminous Events: The Associated Sferics
Authors: Chou Jung‐Kuang , Hsu Rue‐Ron , Su Han‐Tzong , Chen Alfred Bing‐Chih , Kuo Cheng‐Ling , Huang Sung‐Ming , Chang Shu‐Chun , Peng Kang‐Ming , Wu Yen‐Jung
Published: March 2018

The blue luminous events (BLEs) recorded by ISUAL (Imager of Sprites and Upper Atmospheric Lightning) radiate unambiguous middle ultraviolet to blue emissions (230–450 nm) but contain dim red emissions (623–754 nm). The BLE appears to be dot‐like on one ISUAL image with an integration time of 29 ms. A few BLEs develop upward into blue jets/starters or type II gigantic jets (GJs). The associated sferics of the BLEs in the extremely low frequency to very low frequency band and in the low‐frequency band exhibit similar patterns to the narrow bipolar events (NBEs) identified in the very low frequency and low‐frequency band. The ISUAL BLEs are conjectured to be the accompanied light emissions of the NBEs. Both upward and downward propagating current obtained from the associated sferics of the BLEs have been found. The source heights of the six BLEs related to negative NBEs are estimated in the range of 16.2–17.8 km. These six events are suggested to occur between the upper positive charge layer and the negative screen charge layer on the top of the normally electrified thunderstorm. The six blue starters, one blue jet, and one type II GJ are inferred to be positive upward discharges from their associated sferics in the extremely low frequency to very low frequency band. Based on the simultaneous radio and optical observations, a NBE is conjectured to be the initiation discharge with rapidly flowing current within the thunderstorm, while a blue jet/starter or a type II GJ is suggested to be the ensuing discharge with slowly varying current propagating upward from the thunderstorm.
Solar Wind Properties During Juno's Approach to Jupiter: Data Analysis and Resulting Plasma Properties Utilizing a 1‐D Forward Model
Authors: Wilson R. J. , Bagenal Fran , Valek Philip W. , McComas D. J. , Allegrini Frederic , Ebert Robert W. , Kim Thomas K. , Kurth W. S. , Szalay Jamey R. , Thomsen Michelle F.
Published: March 2018

The Jovian Auroral Distributions Experiment ion sensor (JADE‐I) on board the National Aeronautics and Space Administration's Juno mission measured solar wind ions for ≈40 days prior to the spacecraft's arrival at Jupiter, simultaneous with numerous telescope observations of the Jovian aurora. JADE‐I is a thermal plasma time‐of‐flight instrument designed to measure Jovian auroral and magnetospheric ions. This study provides a solar wind parameter data set for the approach phase that may be used in coordinated studies with remote measurements of the Jovian aurora, to compare with models that propagate solar wind conditions from Earth and to apply to Jovian bow shock or magnetopause models. While multiple bow shock crossings were predicted during Juno's approach, there was only one observed suggesting a compressed magnetosphere that was shrinking as Juno approached. However, the calculated ram pressure at the bow shock was near the median value of those 40 days, rather than being in an upper percentile.
Climatology of the Occurrence Rate and Amplitudes of Local Time Distinguished Equatorial Plasma Depletions Observed by Swarm Satellite
Authors: Wan Xin , Xiong Chao , Rodriguez‐Zuluaga Juan , Kervalishvili Guram N. , Stolle Claudia , Wang Hui
Published: March 2018

In this study, we developed an autodetection technique for the equatorial plasma depletions (EPDs) and their occurrence and depletion amplitudes based on in situ electron density measurements gathered by Swarm A satellite. For the first time, comparisons are made among the detected EPDs and their amplitudes with the loss of Global Positioning System (GPS) signal of receivers onboard Swarm A, and the Swarm Level‐2 product, Ionospheric Bubble Index (IBI). It has been found that the highest rate of EPD occurrence takes place generally between 2200 and 0000 magnetic local time (MLT), in agreement with the IBI. However, the largest amplitudes of EPD are detected earlier at about 1900–2100 MLT. This coincides with the moment of higher background electron density and the largest occurrence of GPS signal loss. From a longitudinal perspective, the higher depletion amplitude is always witnessed in spatial bins with higher background electron density. At most longitudes, the occurrence rate of postmidnight EPDs is reduced compared to premidnight ones; while more postmidnight EPDs are observed at African longitudes. CHAMP observations confirm this point regardless of high or low solar activity condition. Further by comparing with previous studies and the plasma vertical drift velocity from ROCSAT‐1, we suggest that while the F region vertical plasma drift plays a key role in dominating the occurrence of EPDs during premidnight hours, the postmidnight EPDs are the combined results from the continuing of former EPDs and newborn EPDs, especially during June solstice. And these newborn EPDs during postmidnight hours seem to be less related to the plasma vertical drift.
Low‐Altitude Observations of Recurrent Short‐Lived keV Ion Microinjections Inside the Diffuse Auroral Zone
Authors: Sauvaud J.‐A. , Delcourt D. , Parrot M. , Payan D. , Raita T. , Penou E.
Published: March 2018

The AMBRE experiment onboard the ocean topography mapper JASON‐3 aims at measuring the spacecraft potential as well as auroral particle precipitation using two top‐hat analyzers for electrons and ions in the 20 eV–28 keV energy range. The JASON‐3 spacecraft has a nearly circular orbit at an altitude of 1,336 km with an inclination of 66°, at times probing the equatorward part of the auroral oval in a nearly tangential manner upon leaving the outer radiation belt. In this region of space, during periods of enhanced geomagnetic activity with small or moderate storms, AMBRE detected recurrent “microinjections” of ions with energies in the 200 eV–28 keV range and which exhibit clear time‐of‐flight dispersion. Ray tracing using single trajectory computations suggests that these ions are launched from a source located in the 8,000–12,000 km altitudinal range and subsequently propagate downward toward the ionosphere. Such observations of quasiperiodic dispersed downflowing ions are new, and we argue that these structures could be produced by ion‐wave interactions at midaltitudes.
TheCE1303 Hongdong Earthquake and the Huoshan Piedmont Fault, Shanxi Graben: Implications for Magnitude Limits of Normal Fault Earthquakes
Authors: Xu Yueren , He Honglin , Deng Qidong , Allen Mark B. , Sun Haoyue , Bi Lisi
Published: March 2018

The CE 1303 Hongdong earthquake, with ~270,000 deaths, has been suggested as the first magnitude 8 earthquake recorded in North China. We use 31 AMS‐14C ages to date earthquakes recorded in the Huoshan Piedmont Fault, which is interpreted to be the causative fault for the event. We interpret fault traces and map the Hongdong earthquake surface rupture in detail. Four events are identified with timings constrained at 1,060–590 year BP (corresponding to the Common Era 1303 event), 3,310–3,210 year BP, 5,460–5,380 year BP, and 26,380 year BP, respectively. The later three events have a recurrence interval of ~2,000–3,000 years. We find that the Hongdong earthquake had a rupture length of ~98 km, a maximum throw of 5.0 m and a best estimate for magnitude in the range Mw 7.2–7.6. We suggest that previous magnitude estimates are overestimates. Normal fault earthquakes have smaller upper limits to their magnitudes than thrusts, because their relatively steep dips produce intersections at the base of the seismogenic layer at smaller downdip widths than gently dipping thrust faults. The Hongdong event was not an exception to this pattern. The historic released seismic moment may be closer to the accumulated moment than previously calculated.
On Estimating Turbulent Reynolds Stress in Wavy Aquatic Environment
Authors: Bian Changwei , Liu Zhiyu , Huang Yongxiang , Zhao Liang , Jiang Wensheng
Published: March 2018

Several methods have been developed for the estimation of the turbulent Reynolds stress in wavy aquatic environment. They are based on different physical assumptions and often give discrepant results. It is practically difficult to quantify the uncertainties in these estimations. Using high‐resolution velocity measurements of acoustic Doppler velocimeter (ADV) from a coastal benthic layer subject to moderate wave influence (the ratio of rms wave orbital velocity to current magnitude was 0.23–0.92), this study tests a Synchrosqueezed Wavelet Transform (SWT)‐based method and three existing methods (i.e., the Coherence, Cospectra, and Ensemble Empirical Mode Decomposition [EEMD] methods) for wave‐turbulence decomposition. In particular, we evaluate the performance of different methods for objective estimation of the turbulent Reynolds stress. Power spectra and cospectra analysis is conducted to quantify the uncertainties in the estimations. The results suggest that the Coherence method tends to overestimate the Reynolds stress due to incomplete removal of wave motions from the observed velocity records; the Cospectra method performs poorly because the empirical model does not fit the observed cospectra well; both the EEMD and SWT methods underestimate the Reynolds stress, as they tend to attribute turbulent fluctuations at frequencies in the vicinity of the wave frequencies to wave motions. In general, the SWT method performs best inducing lowest uncertainty in the Reynolds stress estimation. For the data set analyzed in this study, the estimations with the Coherence, Cospectra, EEMD, and SWT methods account for 70%, 50%, 51%, and 60% of the total covariance of horizontal and vertical velocities, respectively.
Partitioning of the Open Waters of the Gulf of Mexico Based on the Seasonal and Interannual Variability of Chlorophyll Concentration
Authors: Damien Pierre , Pasqueron de Fommervault Orens , Sheinbaum Julio , Jouanno Julien , Camacho‐Ibar Victor F. , Duteil Olaf
Published: March 2018

The seasonal and interannual variability of chlorophyll in the Gulf of Mexico open waters is studied using a three‐dimensional coupled physical‐biogeochemical model. A 5 years hindcast driven by realistic open‐boundary conditions, atmospheric forcings, and freshwater discharges from rivers is performed. The use of recent in situ observations allowed an in‐depth evaluation of the model nutrient and chlorophyll seasonal distributions, including the chlorophyll vertical structure. We find that different chlorophyll patterns of temporal variability coexist in the deep basin which thereby cannot be considered as a homogeneous region with respect to chlorophyll dynamics. A partitioning of the Gulf of Mexico open waters based on the winter chlorophyll concentration increase is then proposed. This partition is basically explained by the amount of nutrients injected into the euphotic layer which is highly constrained by the dynamic of the winter mixed layer. The seasonal and interannual variability appears to be affected by the variability of atmospheric fluxes and mesoscale dynamics (Loop Current eddies in particular). Finally, estimates of primary production in the deep basin are provided.
To What Extent Multidecadal Changes in Morphology and Fluvial Discharge Impact Tide in a Convergent (Turbid) Tidal River
Authors: Jalón‐Rojas I. , Sottolichio A. , Hanquiez V. , Fort A. , Schmidt S.
Published: March 2018

Understanding nonstationary tides in tidal rivers is a major contemporary challenge. In particular, the response of river tides to natural developments in the estuary remains poorly investigated. This study analyzes the evolution of tidal characteristics over the last six decades in the Garonne Tidal River (GTR, SW France), in order to explore the effect of natural and human‐induced morphological and hydrological changes on river tides. The tidal Garonne is an excellent example, as it has been subject to decreasing river discharges, natural morphological changes, and gravel extraction. Tidal range (TR), distortion (AM4/AM2), and asymmetry direction (2ϕM2‐ϕM4) were calculated at four locations from the water level time series of 1953, 1971, 1982, 1994, 2005, and 2014. The annual time series of M2 and M4 amplitudes and phases were obtained through complex demodulation. Results reveal that both TR and 2ϕM2‐ϕM4 have increased since the 1950s. River flow modulates TR and AM4/AM2 significantly. A long‐term decrease in summer discharges from 200 ± 50 to 100 ± 50 m3 s−1 would increase TR by +11.5% in the upper GTR. Natural morphological changes amplified TR and 2ϕM2‐ϕM4 by up to +12–15% between 1953 and 2014. TR and 2ϕM2‐ϕM4 doubled in the regions affected by gravel extraction between 1953 and 1971. Further, the persistence of mobile mud in the GTR increased TR seasonally but also interannually (by up to +16% in winter and spring of dry years). The potential impact of these changes on suspended sediments is discussed, revealing complex feedback between the evolution of hydrology, morphology, tides, and sediment trapping.
Seasonal and Interannual Variations of Sea Ice Mass Balance From the Central Arctic to the Greenland Sea
Authors: Lei Ruibo , Cheng Bin , Heil Petra , Vihma Timo , Wang Jia , Ji Qing , Zhang Zhanhai
Published: March 2018

The seasonal evolution of sea ice mass balance between the Central Arctic and Fram Strait, as well as the underlying driving forces, remain largely unknown because of a lack of observations. In this study, two and three buoys were deployed in the Central Arctic during the summers of 2010 and 2012, respectively. It was established that basal ice growth commenced between mid‐October and early December. Annual basal ice growth, ranging from 0.21 to 1.14 m, was determined mainly by initial ice thickness, air temperature, and oceanic heat flux during winter. An analytic thermodynamic model indicated that climate warming reduces the winter growth rate of thin ice more than for thick ice because of the weak thermal inertia of the former. Oceanic heat flux during the freezing season was 2–4 W m−2, which accounted for 18–31% of the basal ice energy balance. We identified two mechanisms that modified the oceanic heat flux, i.e., solar energy absorbed by the upper ocean during summer, and interaction with warm waters south of Fram Strait; the latter resulted in basal ice melt, even in winter. In summer 2010, ice loss in the Central Arctic was considerable, which led to increased oceanic heat flux into winter and delayed ice growth. The Transpolar Drift Stream was relatively weak in summer 2013. This reduced sea ice advection out of the Arctic Ocean, and it restrained ice melt because of the cool atmospheric conditions, weakened albedo feedback, and relatively small oceanic heat flux in the north.
New Evidence of Breakpoint Forced Long Waves: Laboratory, Numerical, and Field Observations
Authors: Moura T. , Baldock T. E.
Published: March 2018

Numerical modeling and analysis of laboratory and field data are combined to show new evidence of breakpoint forced long waves. The laboratory data and numerical modeling show that the breakpoint can oscillate at frequencies not directly linked to the wave group envelope for specific bichromatic wave groups. The breakpoint therefore oscillates at frequencies where incident bound long waves are not present, enabling direct identification of breakpoint forced waves. Spectral analysis and cross‐shore wave propagation patterns indicate that the breakpoint forced waves occur at subharmonic wave groups frequencies, the repeat frequency of the short waves within the group, and at frequencies associated with triad interactions. The results indicate that in this case the long waves are generated by breakpoint forcing rather than by energy transfer during shoaling of the incident waves. The slowly varying shape of the short waves in the groups and wave merging at the breakpoint controls the modulation of the breakpoint in these cases. The spectral analysis is applied to two field data sets where the breakpoint oscillation, incident waves and shoreline oscillation were measured, and infragravity wave generation is again identified at discrete frequencies that are not present in the incident wave group envelope, with merging of waves at the breakpoint again evident. The magnitudes of the generated infragravity waves outside the surf zone are also dependent on the normalized surf zone width. Both sets of observations provide further evidence for the generation of infragravity waves by the breakpoint forcing mechanism in the field.
Dynamics of Active Subglacial Lakes in Recovery Ice Stream
Authors: Dow C. F. , Werder M. A. , Babonis G. , Nowicki S. , Walker R. T. , Csatho B. , Morlighem M.
Published: March 2018

Recovery Ice Stream has a substantial number of active subglacial lakes that are observed, with satellite altimetry, to grow and drain over multiple years. These lakes store and release water that could be important for controlling the velocity of the ice stream. We apply a subglacial hydrology model to analyze lake growth and drainage characteristics together with the simultaneous development of the ice stream hydrological network. Our outputs produce a good match between modeled lake location and those identified using satellite altimetry for many of the lakes. The modeled subglacial system demonstrates development of pressure waves that initiate at the ice stream neck and transit to within 100 km of the terminus. These waves alter the hydraulic potential of the ice stream and encourage growth and drainage of the subglacial lakes. Lake drainage can cause large R‐channels to develop between basal overdeepenings that persist for multiple years. The pressure waves, along with lake growth and drainage rates, do not identically repeat over multiple years due to basal network development. This suggests that the subglacial hydrology of Recovery Ice Stream is influenced by regional drainage development on the scale of hundreds of kilometers rather than local conditions over tens of kilometers.
Spatial Variability of Sediment Transport Processes Over Intratidal and Subtidal Timescales Within a Fringing Coral Reef System
Authors: Pomeroy Andrew W. M. , Lowe Ryan J. , Ghisalberti Marco , Winter Gundula , Storlazzi Curt , Cuttler Michael
Published: March 2018

Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea‐swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea‐swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross‐reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave‐driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave‐driven currents.
Using Stereo Satellite Imagery to Account for Ablation, Entrainment, and Compaction in Volume Calculations for Rock Avalanches on Glaciers: Application to the 2016 Lamplugh Rock Avalanche in Glacier Bay National Park, Alaska
Authors: Bessette‐Kirton Erin K. , Coe Jeffrey A. , Zhou Wendy
Published: March 2018

The use of preevent and postevent digital elevation models (DEMs) to estimate the volume of rock avalanches on glaciers is complicated by ablation of ice before and after the rock avalanche, scour of material during rock avalanche emplacement, and postevent ablation and compaction of the rock avalanche deposit. We present a model to account for these processes in volume estimates of rock avalanches on glaciers. We applied our model by calculating the volume of the 28 June 2016 Lamplugh rock avalanche in Glacier Bay National Park, Alaska. We derived preevent and postevent 2‐m resolution DEMs from WorldView satellite stereo imagery. Using data from DEM differencing, we reconstructed the rock avalanche and adjacent surfaces at the time of occurrence by accounting for elevation changes due to ablation and scour of the ice surface, and postevent deposit changes. We accounted for uncertainties in our DEMs through precise coregistration and an assessment of relative elevation accuracy in bedrock control areas. The rock avalanche initially displaced 51.7 ± 1.5 Mm3 of intact rock and then scoured and entrained 13.2 ± 2.2 Mm3 of snow and ice during emplacement. We calculated the total deposit volume to be 69.9 ± 7.9 Mm3. Volume estimates that did not account for topographic changes due to ablation, scour, and compaction underestimated the deposit volume by 31.0–46.8 Mm3. Our model provides an improved framework for estimating uncertainties affecting rock avalanche volume measurements in glacial environments. These improvements can contribute to advances in the understanding of rock avalanche hazards and dynamics.
Dynamic Hydraulic Conductivity Reconciles Mismatch Between Modeled and Observed Winter Subglacial Water Pressure
Authors: Downs Jacob Z. , Johnson Jesse V. , Harper Joel T. , Meierbachtol Toby , Werder Mauro A.
Published: March 2018

The link between subglacial hydrology and basal sliding has prompted work on basal hydrology models with water pressure and drainage capacity as prognostic variables. We find that the Glacier Drainage System model, which belongs to a commonly used family of subglacial hydrology models that include both channelized and distributed drainage components, underpredicts winter water pressure when compared to borehole observations from western Greenland given a wide range of plausible parameter values and inputs. This problem, though previously noted by other modelers, has not been addressed. Possible causes for the discrepancy including idealized model inputs or unconstrained parameters are investigated through a series of modeling experiments on both synthetic and realistic ice sheet geometries. Numerical experiments reveal that englacial storage and hydraulic conductivity in the distributed system are the primary controls on winter water pressure in Glacier Drainage System model. Observations of temperate layer thickness and englacial water content from western Greenland imply an upper bound on englacial storage, suggesting that a reduction in hydraulic conductivity is the most plausible cause of high winter water pressure. We conclude that hydraulic conductivity acts as a proxy for the subgrid‐scale connectivity of the linked cavity system and should therefore change seasonally in correspondence with melt water availability.
The Effect of IMF Fluctuations on the Subsolar Magnetopause Position: A Study Using a Global MHD Model
Authors: Bonde R. E. F. , Lopez R. E. , Wang J. Y.
Published: March 2018

During southward interplanetary magnetic field (IMF) conditions, the subsolar magnetopause moves inward even under steady solar wind pressure. This is generally referred to as “erosion.” Empirical and computational studies have been conducted to quantify the effect of magnetopause erosion; however, they generally use steady state IMF conditions. Solar wind conditions are not usually constant for very long, especially during such conditions as are present in high‐speed streams, which typically have large fluctuations in the IMF. These IMF fluctuations can occur on a range of times scales and amplitudes, resulting in a series of northward and southward IMF intervals imposed on the magnetosphere. We have simulated the effect of such IMF variations on the magnetopause position using a global magnetohydrodynamic model. We find that there are both time lag and hysteresis‐like effects on the motion of the magnetopause due to the variation in the magnitude of the southward IMF and that the instantaneous position of the magnetopause can be significantly different from what one would expect from steady state conditions.
High‐Citation Papers in Space Physics: Examination of Gender, Country, and Paper Characteristics
Authors: Moldwin Mark B. , Liemohn Michael W.
Published: March 2018

The number of citations to a refereed journal article from other refereed journal articles is a measure of its impact. Papers, individuals, journals, departments, and institutions are increasingly judged by the impact they have in their disciplines, and citation counts are now a relatively easy (though not necessarily accurate or straightforward) way of attempting to quantify impact. This study examines papers published in the Journal of Geophysical Research—Space Physics in the year 2012 (n = 705) and analyzes the characteristics of high‐citation papers compared to low‐citation papers. We find that high‐citation papers generally have a large number of authors (>5) and cite significantly more articles in the reference section than low‐citation papers. We also examined the gender and country of institution of the first author and found that there is not a statistically significant gender bias, but there are some significant differences in citation statistics between articles based on the country of first‐author institution.
Looking Beyond the Powder/Dense Flow Avalanche Dichotomy
Authors: Faug T. , Turnbull B. , Gauer P.
Published: March 2018

Köhler et al. (2018, https://doi.org/10.1002/2017JF004375) deploy a high spatial and temporal resolution GEODAR radar system to reveal the inside of snow avalanches over the entire slope. They detect a rich variety of longitudinal and slope normal flow structures across a data set of 77 avalanches recorded over 6 years. Distinctive features in the radar signatures permit the definition of seven flow regimes and three distinct stopping signatures, illustrating behaviors much richer than the conventional dichotomy between dense flow avalanches and powder snow avalanches. This presents modelers with the challenge of exploring the physics of these regimes, the transitions between them and their relationship with the surrounding conditions.
Distributed Student's t filtering algorithm for heavy‐tailed noises
Authors: Xu Chen , Zhao Shunyi , Huang Biao , Liu Fei
Published: March 2018

In this paper, a distributed Student's t filtering algorithm to deal with heavy‐tailed noises is developed. In the traditional Kalman filter, the distribution of the signal is assumed. However, in reality, outliers in the signal are often encountered for which the assumption of Gaussian distribution is no longer valid. The Student's t distribution can describe noises in the presence of outliers. As a result, the weight on each data point within the filter adapts to the data quality so that the filter becomes insensitive to the outliers. We first derive the distributed filtering algorithm from the centralized Student's t filter, which is able to handle heavy‐tailed noises such as outliers and then analyze properties of the proposed method. It is shown that the proposed algorithm provides the same accuracy as the centralized Student's t filtering with no performance loss. Furthermore, the distributed Student's t filtering with feedback is developed, which is in accordance with centralized filtering, and the local error covariance is reduced as expected. Two numerical examples support the theoretical results and illustrate the validity of the proposed method.
Unveiling the Interfaces between β′ Precipitates in Mg–Gd–Y–Zr Alloy: Insights from Atomic‐Scale HAADF‐STEM
Authors: Zheng Jingxu Kent , Zeng Xiaoqin , Chen Bin
Published: March 2018

Previous studies about the precipitation in Mg–Gd–Y–Zr alloy show that the transformation of to subsequent precipitate structures takes place at the interfaces between the . However, the interfaces between precipitates were barely studied. The present study using atomic‐scale HAADF‐STEM is aimed to fully unveil the interfaces between the precipitates. The results show that the interfaces can be categorized into four types that present in large quantities. A type I, type I, or type IV interface contains a gap between two precipitates, while a type III interface contains a transitional structure named as . In addition, the results show that observations from two directions are needed in order to identify complicated interfacial structures.
Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations
Authors: Shiran Chaharsoughi Mina , Tordera Daniel , Grimoldi Andrea , Engquist Isak , Berggren Magnus , Fabiano Simone , Jonsson Magnus P.
Published: March 2018

State‐of‐the‐art solar energy harvesting systems based on photovoltaic technology require constant illumination for optimal operation. However, weather conditions and solar illumination tend to fluctuate. Here, a device is presented that extracts electrical energy from such light fluctuations. The concept combines light‐induced heating of gold nanodisks (acting as plasmonic optical nanoantennas), and an organic pyroelectric copolymer film (poly(vinylidenefluoride‐co‐trifluoroethylene)), that converts temperature changes into electrical signals. This hybrid device can repeatedly generate current pulses, not only upon the onset of illumination, but also when illumination is blocked. Detailed characterization highlights the key role of the polarization state of the copolymer, while the copolymer thickness has minor influence on performance. The results are fully consistent with plasmon‐assisted pyroelectric effects, as corroborated by combined optical and thermal simulations that match the experimental results. Owing to the tunability of plasmonic resonances, the presented concept is compatible with harvesting near infrared light while concurrently maintaining visible transparency.
Epsilon‐Near‐Zero Photonics: A New Platform for Integrated Devices
Authors: Niu Xinxiang , Hu Xiaoyong , Chu Saisai , Gong Qihuang
Published: March 2018

Epsilon‐near‐zero (ENZ) photonics is the study of light–matter interactions in the presence of structures with near‐zero permittivity and has been emerging as an important field of research in recent years. The introduction of zero permittivity structures also introduces a number of unique features to traditional photonic systems, including decoupling of their spatial and temporal field variations, tunneling through arbitrary channels, constant phase transmission, strong field confinement, and ultrafast phase transitions. Along with the continued developments in the theoretical research on ENZ photonics, many novel functional photonic devices are proposed and demonstrated experimentally, thus indicating the broad prospects of ENZ photonics for fabrication of high‐performance integrated photonic chips. Zero‐epsilon materials, which represent a singular point in optical materials, are expected to lead to remarkable developments in the fields of integrated photonic devices and optical interconnections. This review summarizes the underlying principles, the related novel physical effects, the fundamental principles for realization of ENZ photonic systems, and the integrated device applications of ENZ photonics. The review concludes with a brief overview of the challenges to be confronted and the potential development directions that may be pursued to realize extensive applications of ENZ photonics in the field of integrated photonic signal processing.
Light‐Induced Charge Separation in Mixed Electronic/Ionic Semiconductor Driving Lithium‐Ion Transfer for Photo‐Rechargeable Electrode
Authors: Andriamiadamanana Christian , Sagaidak Iryna , Bouteau Gaspard , Davoisne Carine , Laberty‐Robert Christel , Sauvage Frédéric
Published: March 2018

Li‐ion batteries need to be regularly recharged, requiring chargers and connection to the grid to reverse the lithium‐ion transfer. Autonomous power sources independent of the electrical infrastructure are desired. A strategy to develop continuously functioning Li‐ion batteries is focused on a new architecture of electrodes which are capable of both harvesting light energy and storing it. One possible way to achieve this lies in a study aimed at evaluating whether lithium ions can display mobility inside a crystal structure upon light absorption, as in analogy to the dissociation process of excitons. Herein, it is demonstrated that by using LixTiO2 nanoparticles, bandgap excitation can induce a quantitative Li‐ion deinsertion reaction by the free holes generated. The half‐electrochemical cells containing these mesoporous lithiated TiO2 can be fully oxidized in only 1 h of light exposure. It displays close to 3 V open‐circuit potential under light and electrical load, and, provides a constant output power under fluctuating light conditions. Such an approach has the potential, when integrated into a fully regenerative device containing a suitable counter electrode, to generate energy during both day and night, thus having the potential to close the gap between electrochemical energy storage batteries and energy conversion photovoltaics.
High Temperature Polymer Electrolyte Membrane Fuel Cells for Integrated Fuel Cell – Methanol Reformer Power Systems: A Critical Review
Authors: Zhang Jin , Xiang Yan , Lu Shanfu , Jiang San Ping
Published: March 2018

The development of reliable power sources is important for the continuous operation of various electric equipment in unmanned aircraft and the field environment. Currently electric power delivery to such systems is mainly by battery packs. An alternative is to use fuel cells (FCs). FCs are electrochemical devices that are used to convert chemical energy of fuels such as hydrogen and methanol to electricity. Methanol is an attractive fuel because it is liquid at ambient temperature, has a much higher energy density than hydrogen and low reforming temperature (220–300 °C). Thus, integration of methanol steam reformers (MSRs) with FCs makes it possible to continuously produce electricity. The key challenge in such power system is the development of fuel cells which can be effectively operated at compatible temperature range of MSR, i.e., 220–300 °C in order to increase synergetic heat integration and system reliability. Herein, the latest development of high temperature polymer electrolyte membrane fuel cells (HT‐PEMFCs) is critically reviewed. The prospect of the integrated HT‐PEMFCs‐MSR as a reliable and compact power source is discussed. The results indicate that phosphoric acid doped polybenzimidazole (PA/PBI) membranes with in situ formed phosphosilicate nanocluster proton carriers show the technical feasibility of the development of HT‐PEMFCs at temperatures of 200–300 °C.
Densification by Compaction as an Effective Low‐Cost Method to Attain a High Areal Lithium Storage Capacity in a CNT@Co3O4 Sponge
Authors: Chen Yijun , Wang Yunsong , Wang Zhipeng , Zou Mingchu , Zhang Hui , Zhao Wenqi , Yousaf Muhammad , Yang Liusi , Cao Anyuan , Han Ray P. S.
Published: March 2018

Achieving a high areal capacity is essential for the transfer of outstanding laboratory electrode results to commercial applications and also to ensure there exists a capacity matched cathode and anode for a properly tuned battery. Despite intensive efforts, most electrode materials exhibit areal capacities lower than that of the graphite anodes (4 mA h cm−2). An effective and low‐cost approach is reported to attain a high areal capacity via an intense densification by compacting a porous carbon nanotube sponge grafted with Co3O4 nanoparticles. The hybrid sponge can be compacted to a large degree (up to a tenfold densification) while still keeping its structural integrity and the 3D porous network. This method allows achieving a mass loading of up ‑to 14.3 mg cm−2 and an areal capacity of 12 mA h cm−2 (at a current density of 200 mA g−1) together with a gravimetric capacity of >800 mA h g−1. This densification by compaction approach offers an effective and low‐cost strategy to develop high mass loading and areal capacity electrodes for practical energy storage systems.
RuII‐Catalyzed Regioselective Debrominative Annulation Reaction of Salicylaldehydes and Propargyl Bromide: Synthesis of 2‐Methylchromones
Authors: Borthakur Somadrita , Kaishap Partha P. , Gogoi Sanjib
Published: March 2018

A new method for the annulation reaction of salicylaldehydes with propargyl bromide is described. This RuII‐catalyzed annulation reaction provides 2‐methylchromones, which are a substructure of many biologically active natural products. The annulation reaction could be further extended to the synthesis of 2‐methylfuran‐fused compounds.