Dynamic Brain Sources of Visual Evoked Responses Makeig, S.; Westerfield, M.; T.-P. Jung ...
Science (American Association for the Advancement of Science),
01/2002, Volume:
295, Issue:
5555
Journal Article
Peer reviewed
It has been long debated whether averaged electrical responses recorded from the scalp result from stimulus-evoked brain events or stimulus-induced changes in ongoing brain dynamics. In a human ...visual selective attention task, we show that nontarget event-related potentials were mainly generated by partial stimulus-induced phase resetting of multiple electroencephalographic processes. Independent component analysis applied to the single-trial data identified at least eight classes of contributing components, including those producing central and lateral posterior alpha, left and right mu, and frontal midline theta rhythms. Scalp topographies of these components were consistent with their generation in compact cortical domains.
Most members of the oomycete genus Phytophthora are primary plant pathogens. Both soil- and airborne Phytophthora species are able to survive adverse environmental conditions with enduring resting ...structures, mainly sexual oospores, vegetative chlamydospores and hyphal
aggregations. Soilborne Phytophthora species infect fine roots and the bark of suberized roots and the collar region with motile biflagellate zoospores released from sporangia during wet soil conditions. Airborne Phytophthora species infect leaves, shoots, fruits and bark of
branches and stems with caducous sporangia produced during humid conditions on infected plant tissues and dispersed by rain and wind splash. During the past six decades, the number of previously unknown Phytophthora declines and diebacks of natural and semi-natural forests and woodlands
has increased exponentially, and the vast majority of them are driven by introduced invasive Phytophthora species. Nurseries in Europe, North America and Australia show high infestation rates with a wide range of mostly exotic Phytophthora species. Planting of infested nursery
stock has proven to be the main pathway of Phytophthora species between and within continents. This review provides insights into the history, distribution, aetiology, symptomatology, dynamics and impact of the most important canker, decline and dieback diseases caused by soil- and
airborne Phytophthora species in forests and natural ecosystems of Europe, Australia and the Americas.
LiNiO2 (LNO) is a promising cathode material for next‐generation Li‐ion batteries due to its exceptionally high capacity and cobalt‐free composition that enables more sustainable and ethical ...large‐scale manufacturing. However, its poor cycle life at high operating voltages over 4.1 V impedes its practical use, thus motivating efforts to elucidate and mitigate LiNiO2 degradation mechanisms at high states of charge. Here, a multiscale exploration of high‐voltage degradation cascades associated with oxygen stacking chemistry in cobalt‐free LiNiO2, is presented. Lattice oxygen loss is found to play a critical role in the local O3–O1 stacking transition at high states of charge, which subsequently leads to Ni‐ion migration and irreversible stacking faults during cycling. This undesirable atomic‐scale structural evolution accelerates microscale electrochemical creep, cracking, and even bending of layers, ultimately resulting in macroscopic mechanical degradation of LNO particles. By employing a graphene‐based hermetic surface coating, oxygen loss is attenuated in LNO at high states of charge, which suppresses the initiation of the degradation cascade and thus substantially improves the high‐voltage capacity retention of LNO. Overall, this study provides mechanistic insight into the high‐voltage degradation of LNO, which will inform ongoing efforts to employ cobalt‐free cathodes in Li‐ion battery technology.
Lattice oxygen loss is found to play a critical role in the O3–O1 stacking transition in cobalt‐free LiNiO2 lithium‐ion battery cathodes, which subsequently induces Ni‐ion migration and irreversible stacking faults, microscale creep, cracking, and even bending of layers after high‐voltage cycling. By suppressing oxygen evolution, hermetic graphene coatings arrest this degradation cascade, resulting in substantially improved high‐voltage capacity retention.
During the past decade, and in particular after the wet year 2002 and the dry year 2003, an increasing number of trees and stands of European beech (Fagus sylvatica L.) in Bavaria were showing ...symptoms typical for Phytophthora diseases: increased transparency and crown dieback, small-sized and often yellowish foliage, root and collar rot and aerial bleeding cankers up to stem heights of >20 m. Between 2003 and 2007 134 mature beech stands on a broad range of geological substrates were surveyed, and collar rot and aerial bleeding cankers were found in 116 (86.6%) stands. In most stands the majority of beech trees were declining and scattered or clustered mortality occurred. Bark and soil samples were taken from 314 trees in 112 stands, and 11 Phytophthora species were recovered from 253 trees (80.6%) in 104 stands (92.9%). The most frequent species were P. citricola, P. cambivora and P. cactorum. Primary Phytophthora lesions were soon infected by a series of secondary bark pathogens, including Nectria coccinea, and wood decay fungi. In addition, infected trees were often attacked by several bark and wood boring insects leading to rapid mortality. Bark necroses were examined for their probable age in order to determine whether the onset of the current Phytophthora epidemic was correlated to rainfall rates recorded at 22 Bavarian forest ecosystem monitoring stations. A small-scale survey in nine Bavarian nurseries demonstrated regular infestations of all beech fields with the same range of Phytophthora species. The results indicate that (1) Phytophthora species are regularly associated with beech decline and may also be involved in the complex of 'Beech Bark Disease', (2) excessive rainfalls and droughts are triggering the disease, and (3) widespread Phytophthora infestations of nursery stock might endanger current and future silvicultural projects aiming on the replacement of non-natural conifer stands by beech dominated mixed stands.
Predictability of the Arctic sea ice edge Goessling, H. F.; Tietsche, S.; Day, J. J. ...
Geophysical research letters,
28 February 2016, Volume:
43, Issue:
4
Journal Article
Peer reviewed
Open access
Skillful sea ice forecasts from days to years ahead are becoming increasingly important for the operation and planning of human activities in the Arctic. Here we analyze the potential predictability ...of the Arctic sea ice edge in six climate models. We introduce the integrated ice‐edge error (IIEE), a user‐relevant verification metric defined as the area where the forecast and the “truth” disagree on the ice concentration being above or below 15%. The IIEE lends itself to decomposition into an absolute extent error, corresponding to the common sea ice extent error, and a misplacement error. We find that the often‐neglected misplacement error makes up more than half of the climatological IIEE. In idealized forecast ensembles initialized on 1 July, the IIEE grows faster than the absolute extent error. This means that the Arctic sea ice edge is less predictable than sea ice extent, particularly in September, with implications for the potential skill of end‐user relevant forecasts.
Key Points
A new sea ice verification metric is introduced that discerns between total extent and misplacement
Variability of the Arctic ice edge is dominated by misplacement rather than total extent
Misplacement errors grow faster than extent errors due to scale‐dependent predictability
We introduce a verification score for probabilistic forecasts of contours – the Spatial Probability Score (SPS). Defined as the spatial integral of local (Half) Brier Scores, the SPS can be ...considered the spatial analogue of the Continuous Ranked Probability Score (CRPS). Applying the SPS to idealized ensemble forecasts of the Arctic sea‐ice edge in a global coupled climate model, we demonstrate that the metric responds in a meaningful way to ensemble size, spread, and bias. When applied to individual forecasts or ensemble means (or quantiles), the SPS is reduced to the ‘volume’ of mismatch, which in the case of the ice edge corresponds to the Integrated Ice Edge Error (IIEE). By comparing initialized forecasts with climatological and persistence forecasts, we confirm earlier findings on the potential predictability of the Arctic sea‐ice edge from a probabilistic viewpoint. We conclude that the SPS is a promising probabilistic verification metric, for contour forecasts in general and for ice‐edge forecasts in particular.
We introduce a verification score for probabilistic forecasts of contours – the Spatial Probability Score (SPS) – and apply it to idealized ensemble forecasts of the Arctic sea‐ice edge in a global coupled climate model. We demonstrate that the metric responds properly to ensemble size, spread, and bias, and conclude that the SPS is a promising probabilistic verification metric, for contour forecasts in general and for ice‐edge forecasts in particular.
Solid‐state supercapacitors and microsupercapacitors are fabricated from a pristine graphene ink by solution casting and inkjet printing. The devices exhibit high performance, with a volumetric ...device capacitance up to 17.8 F cm−3. With a simple fabrication process and robust tolerance to mechanical deformation, this work represents a promising technology for low‐cost, portable, and flexible energy storage.
The popularity of Electronic Sports (esports) have grown tremendously in the last few years, becoming one of the most popular forms of digital entertainment. Despite continued growth, definitions and ...classifications of esports remain elusive, and the industry is still considered by many to be in its infancy. Understanding of esports originate from diverse, sometimes conflicting fields, which has created fragmented interpretations of its definition, positioning and core components. This has hindered esports from embracing opportunities afforded by emerging digital technologies and progressing as a distinct field. The purpose of this conceptual paper is threefold, to redefine esports, propose a unified framework to capitalise on esports business potential, and inspire a more structured future esports research agenda. The proposed esports Matrix, presents four distinct realms that distinguish esports; esports as a representation of current physical sports (sports digitalisation), esports as traditional (multi-player) game experience (competitive multiplayer computer games), esports that modify existing sports, player rules and setups through digital augmentations (digitally enhanced sports), and new types of esports involving emerging technologies such as virtual and augmented reality (immersive reality sports). The esports Matrix was developed incorporating industry expertise thus verifying its suitability and relevance to advance conceptual and empirical understanding, and importantly, facilitating a more structured approach, to enable businesses to realise the potential of esports.
•Redefines current, disparate, esports perceptions, proposing a more holistic working definition.•esports Matrix, a unified framework to capitalise on esports potential proposed.•Outlines recommendations for further research, to inspire a more structured future research agenda.
The effects of composition and cold groove-rolling on Young's modulus were investigated to achieve low Young's modulus in β Ti–Nb–Sn ternary alloys for orthopedic applications, using ...Ti-(27.5–37.5)%Nb-(2.5–11.25)%Sn ternary alloys. Optical microscopy, transmission electron microscopy, and X-ray diffractometry revealed that the constituent phases of quenched and rolled alloys were classified into three regions of β, β(ω)+α” and α” in the Ti–Nb–Sn ternary phase diagram. The β phase was observed to stabilize by the addition of Sn, and the least stable β alloys existed along a line connecting Ti-37.5Nb-2.5Sn and Ti-27.5Nb–11Sn. Low Young's moduli of approximately 50 GPa were achieved by the least stable, quenched β Ti–Nb–Sn alloys, and these further decreased by cold groove-rolling, reducing the cross section by 75%. The lowest Young's modulus of 36 GPa was realized for the cold groove-rolled Ti–35Nb-3.75Sn alloy, in which the textures of 010α” of deformation-induced α” martensite and 011β of the β matrix developed preferentially, parallel to the rolling direction. The lattice deformation strain along the 010α” axis accompanied by β to α” martensitic transformation was observed to depend on the alloy composition and was maximized in Ti–35Nb-3.75Sn.
Thus, the low Young's modulus of the least stable β Ti–Nb–Sn alloys obtained after cold groove-rolling was attributed to the development of 010α” and 011β textures along the rolling direction, and the lowest Young's modulus of the cold groove-rolled Ti–35Nb-3.75Sn alloy was due to a large lattice deformation strain along the 010α” axis accompanied by β to α” transformation.
Solution‐processed graphene is a promising material for numerous high‐volume applications including structural composites, batteries, sensors, and printed electronics. However, the polydisperse ...nature of graphene dispersions following liquid‐phase exfoliation poses major manufacturing challenges, as incompletely exfoliated graphite flakes must be removed to achieve optimal properties and downstream performance. Incumbent separation schemes rely on centrifugation, which is highly energy‐intensive and limits scalable manufacturing. Here, cross‐flow filtration (CFF) is introduced as a centrifuge‐free processing method that improves the throughput of graphene separation by two orders of magnitude. By tuning membrane pore sizes between microfiltration and ultrafiltration length scales, CFF can also be used for efficient recovery of solvents and stabilizing polymers. In this manner, life cycle assessment and techno‐economic analysis reveal that CFF reduces greenhouse gas emissions, fossil energy usage, water consumption, and specific production costs of graphene manufacturing by 57%, 56%, 63%, and 72%, respectively. To confirm that CFF produces electronic‐grade graphene, CFF‐processed graphene nanosheets are formulated into printable inks, leading to state‐of‐the‐art thin‐film conductivities exceeding 104 S m−1. This CFF methodology can likely be generalized to other van der Waals layered solids, thus enabling sustainable manufacturing of the diverse set of applications currently being pursued for 2D materials.
The polydisperse nature of graphene dispersions following liquid‐phase exfoliation poses major manufacturing challenges since incumbent separation schemes rely on centrifugation, which is highly energy‐intensive and possesses limited scalability. Here, cross‐flow filtration is introduced as a centrifuge‐free processing method that improves the throughput of graphene separation by two orders of magnitude in addition to substantially reducing environmental impact via inline recycling.
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