The electron resonant interaction with whistler‐mode waves is characterized by transport in pitch angle–energy space. We calculate electron diffusion and advection coefficients (a simplified ...characterization of transport) for a large range of electron pitch angle and energy using test particle simulations. Nonlinear effects are analyzed by comparing the diffusion coefficients using test particle simulations and quasilinear theory, and by evaluating the advection rates. Dependence of nonlinear effects on the wave amplitude and bandwidth of whistler‐mode waves is evaluated by running test particle simulations with a broad range of wave amplitude and bandwidth. The maximum amplitudes where the quasilinear approach is valid are found to increase with increasing bandwidth, from 50 pT for narrowband waves to 300 pT for broadband waves at L‐shell of 6. Moreover, interactions between intense whistler‐mode waves and small pitch angle electrons lead to large positive advection, which limits the applicability of diffusion‐based models. This study demonstrates the parameter range of the applicability of quasilinear theory and diffusion model for different wave amplitudes and frequency bandwidths of whistler‐mode waves, which is critical for evaluating the effects of whistler‐mode waves on energetic electrons in the Earth’s magnetosphere.
Key Points
The maximum wave amplitude threshold for the applicability of quasilinear theory increases with increasing bandwidth
Electron diffusion acceleration due to intense broadband whistler‐mode waves is limited by phase trapping trajectory along the field line
Interactions between intense whistler‐mode waves and small pitch angle electrons limit the applicability of diffusion models
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The increasing number of accidents arising from falling objects from the façade of tall buildings has attracted much attention globally. To regulators, a preventive approach based on a mandatory ...periodic façade inspection has been deemed as a necessary measure to maintain the functionality and integrity of the façade of tall buildings. Researchers worldwide have been working towards a predictive approach to allow for the assessment of the likely failure during some future period, by measuring the condition of the façade to detect latent defects and anomalies. The methods proposed include laser scanning, image-based sensing and infrared thermography to support the automatic façade visual inspection. This paper aims to review and analyse the state-of-the-art literature on the automated inspection of building façades, with emphasis on the detection and maintenance management of latent defects and anomalies for falling objects from tall buildings. A step-by-step holistic method is leveraged to retrieve the available literature from databases, followed by the analyses of relevant articles in different long-standing research themes. The types and characteristics of façade falling objects, legislations, practices and the effectiveness of various inspection techniques are discussed. Various diagnostic, inspection and analytical methods which support façade inspection and maintenance are analysed with discussion on the potential future research in this field.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Protein expression of major hepatic uptake and efflux drug transporters in human pediatric (n = 69) and adult (n = 41) livers was quantified by liquid chromatography / tandem mass spectroscopy ...(LC‐MS/MS). Transporter protein expression of OCT1, OATP1B3, P‐gp, and MRP3 was age‐dependent. Particularly, significant differences were observed in transporter expression (P < 0.05) between the following age groups: neonates vs. adults (OCT1, OATP1B3, P‐gp), neonates or infants vs. adolescents and/or adults (OCT1, OATP1B3, and P‐gp), infants vs. children (OATP1B3 and P‐gp), and adolescents vs. adults (MRP3). OCT1 showed the largest increase, of almost 5‐fold, in protein expression with age. Ontogenic expression of OATP1B1 was confounded by genotype and was revealed only in livers harboring SLCO1B1*1A/*1A. In livers >1 year, tissues harboring SLCO1B1*14/*1A showed 2.5‐fold higher (P < 0.05) protein expression than SLCO1B1*15/*1A. Integration of these ontogeny data in physiologically based pharmacokinetic (PBPK) models will be a crucial step in predicting hepatic drug disposition in children.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Energetic electron dynamics is highly affected by plasma waves through quasilinear and/or nonlinear interactions in the Earth's inner magnetosphere. In this letter, we provide physical explanations ...for a previously reported intriguing event from the Van Allen Probes observations, where bursts of electron butterfly distributions at tens of keV exhibit remarkable correlations with chorus waves. Both test particle and quasilinear simulations are used to reveal the formation mechanism for the bursts of electron butterfly distribution. The test particle simulation results indicate that nonlinear phase trapping due to chorus waves is the key process to accelerate electrons to form the electron butterfly distribution within ~30 s, and reproduces the observed features. Quasilinear simulation results show that although the diffusion process alone also contributes to form the electron butterfly distribution, the timescale is slower. Our study demonstrates the importance of nonlinear interaction in rapid electron acceleration at tens of keV by chorus waves.
Plain Language Summary
In the Earth's magnetosphere, wave‐particle interactions play an important role in changing energetic electron dynamics. In particular, whistler mode chorus waves are known to cause efficient electron acceleration. Electron butterfly distribution is a special type of electron pitch angle distribution with double flux peaks away from 90° pitch angle. In this letter, we provide physical explanations for a previously reported intriguing event from the Van Allen Probes observations, where bursts of electron butterfly distributions exhibit remarkable correlations with chorus waves. We use test particle and quasilinear simulations to evaluate the wave‐particle interactions between the observed energetic electrons and chorus waves. The test particle simulation results indicate that nonlinear effects due to chorus waves are critical to form the electron butterfly distribution, which is consistent with the observation, while quasilinear results show that the diffusion process alone is insufficient to reproduce the observed electron butterfly distribution. Our study demonstrates the importance of nonlinear interaction in rapid acceleration of energetic electrons by chorus waves.
Key Points
Formation mechanism for the bursts of electron butterfly distributions is studied using test particle and quasilinear simulations
Nonlinear phase trapping due to chorus waves plays an important role in forming the electron butterfly distributions
Diffusive scattering contributes to electron acceleration but is insufficient to reproduce the rapid formation of electron bursts
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Magnetic skyrmions are particle-like magnetization configurations which can be found in materials with broken inversion symmetry. Their topological nature allows them to circumvent around random ...pinning sites or impurities as they move within the magnetic layer, which makes them interesting as information carriers in memory devices. However, when the skyrmion is driven by a current, a Magnus force is generated which leads to the skyrmion moving away from the direction of the conduction electron flow. The deflection poses a serious problem to the realization of skyrmion-based devices, as it leads to skyrmion annihilation at the film edges. Here, we show that it is possible to guide the movement of the skyrmion and prevent it from annihilating by surrounding and compressing the skyrmion with strong local potential barriers. The compressed skyrmion receives higher contribution from the spin transfer torque, which results in the significant increase of the skyrmion speed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
We report unusual Electromagnetic Ion Cyclotron (EMIC) waves with a very narrow frequency bandwidth, closely following and approaching the proton gyrofrequency. One interesting case analysis shows ...that magnetosonic waves, anisotropic suprathermal proton distributions, and high frequency EMIC waves are closely related. Magnetosonic waves potentially cause the resonant heating of suprathermal protons and the temperature anisotropy of suprathermal protons (10–100 eV) likely provides free energy for the excitation of high frequency EMIC waves. The statistical analysis shows that this type of EMIC waves has a typical wave amplitude of ~100 pT, left‐handed polarization, and small wave normal angles. Moreover, these low frequency EMIC waves typically occur near the equator in the low‐density regions from dawn to dusk. These newly observed high frequency EMIC waves provide new insights into understanding the generation of EMIC waves and the energy transfer between magnetosonic waves and EMIC waves.
Plain Language Summary
Electromagnetic Ion Cyclotron (EMIC) waves are commonly observed in the Earth's magnetosphere and play an important role in causing the loss of ring current ions and relativistic electrons due to pitch angle scattering. In this study, we report unusual high frequency EMIC waves with frequency very close to the proton gyrofrequency. An interesting case study clearly shows the correlation between magnetosonic waves, the enhancement of suprathermal protons, and high frequency EMIC waves. The protons at suprathermal energies could be heated by magnetosonic waves and the anisotropic distribution of suprathermal protons is likely responsible for the excitation of high frequency EMIC waves. The statistical analysis shows that this type of EMIC waves has a typical wave amplitude of ~100 pT, left‐handed polarization, and small wave normal angles. These newly observed high frequency EMIC waves provide new insights into understanding the generation of EMIC waves and the energy transfer between magnetosonic waves and EMIC waves.
Key Points
Unusually high frequency EMIC waves are observed near the proton gyrofrequency with a very narrow bandwidth
Temperature anisotropy of suprathermal protons in association with magnetosonic waves likely excites high frequency EMIC waves
Statistical results show that high frequency EMIC waves typically occur near the equator in the low‐density regions from dawn to dusk
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Electromagnetic ion cyclotron waves in the Earth's outer radiation belt drive rapid electron losses through wave‐particle interactions. The precipitating electron flux can be high in the hundreds ...of keV energy range, well below the typical minimum resonance energy. One of the proposed explanations relies on nonresonant scattering, which causes pitch‐angle diffusion away from the fundamental cyclotron resonance. Here we propose the fractional sub‐cyclotron resonance, a second‐order nonlinear effect that scatters particles at resonance order n = 1/2, as an alternate explanation. Using test‐particle simulations, we evaluate the precipitation ratios of sub‐MeV electrons for wave packets with various shapes, amplitudes, and wave normal angles. We show that the nonlinear sub‐cyclotron scattering produces larger ratios than the nonresonant scattering when the wave amplitude reaches sufficiently large values. The ELFIN CubeSats detected several events with precipitation ratio patterns matching our simulation, demonstrating the importance of sub‐cyclotron resonances during intense precipitation events.
Plain Language Summary
High‐energy electrons in the Earth's radiation belt are constantly being scattered by the ubiquitous electromagnetic plasma waves. A portion of these scattered electrons is lost to the atmosphere, where the particles deposit their energy and cause a chain of chemical reactions, possibly contributing to ozone destruction. The energy and flux of the precipitating electrons depend on the nature of the wave‐particle interactions in the radiation belt. The electromagnetic ion cyclotron wave (EMIC), known to be responsible for scattering relativistic electrons, has been observed to cause precipitation at energies much lower than expected by the standard theory. We numerically investigate two types of interactions, the nonresonant scattering and the nonlinear sub‐cyclotron scattering, and show how both influence the relative precipitating fluxes. We demonstrate that sub‐cyclotron interactions driven by intense EMIC waves can cause stronger precipitation than nonresonant scattering at sub‐MeV energies. The dual ELFIN CubeSats detected precipitation profiles that match our numerical results, confirming the importance of nonlinear sub‐cyclotron scattering in the analysis of intense precipitation events.
Key Points
Electrons resonate with intense quasiparallel electromagnetic ion cyclotron wave waves at fractions of the minimum resonance energy
Fractional resonant scattering causes significant precipitation when the wave amplitude reaches above 1% of the ambient field
Precipitating electron flux spectrum observed by the ELFIN CubeSats supports the estimated influence of fractional resonances
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Non-invasive brain stimulation is being increasingly used to interrogate neurophysiology and modulate brain function. Despite the high scientific and therapeutic potential of non-invasive brain ...stimulation, experience in the developing brain has been limited.
To determine the safety and tolerability of non-invasive neurostimulation in children across diverse modalities of stimulation and pediatric populations.
A non-invasive brain stimulation program was established in 2008 at our pediatric, academic institution. Multi-disciplinary neurophysiological studies included single- and paired-pulse Transcranial Magnetic Stimulation (TMS) methods. Motor mapping employed robotic TMS. Interventional trials included repetitive TMS (rTMS) and transcranial direct current stimulation (tDCS). Standardized safety and tolerability measures were completed prospectively by all participants.
Over 10 years, 384 children underwent brain stimulation (median 13 years, range 0.8–18.0). Populations included typical development (n = 118), perinatal stroke/cerebral palsy (n = 101), mild traumatic brain injury (n = 121) neuropsychiatric disorders (n = 37), and other (n = 7). No serious adverse events occurred. Drop-outs were rare (<1%). No seizures were reported despite >100 participants having brain injuries and/or epilepsy. Tolerability between single and paired-pulse TMS (542340 stimulations) and rTMS (3.0 million stimulations) was comparable and favourable. TMS-related headache was more common in perinatal stroke (40%) than healthy participants (13%) but was mild and self-limiting. Tolerability improved over time with side-effect frequency decreasing by >50%. Robotic TMS motor mapping was well-tolerated though neck pain was more common than with manual TMS (33% vs 3%). Across 612 tDCS sessions including 92 children, tolerability was favourable with mild itching/tingling reported in 37%.
Standard non-invasive brain stimulation paradigms are safe and well-tolerated in children and should be considered minimal risk. Advancement of applications in the developing brain are warranted. A new and improved pediatric NIBS safety and tolerability form is included.
•No serious adverse events occurred during TMS or tDCS in children.•All NIBS modalities were favorably tolerated.•Tolerability improved over time with side-effect frequency decreasing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As air pollution becomes an increasing concern globally, governments, and research institutions have attached great importance to air quality prediction to help give early warnings and prevent the ...impacts of air pollution. The existing prediction methods for air quality forecasting include deterministic methods, statistical methods, machine learning, and deep learning methods. Deep learning-based prediction methods have attracted much attention these years due to its high performance and powerful modeling capability. However, the majority of the deep learning methods only focus on the prediction of the places where there have monitoring stations, and limited studies have integrated deep learning to predict places without monitoring stations. To address the limitations, this paper proposes a new methodology framework combining a deep learning network, namely, bi-directional long short-term memory (BLSTM) network and the inverse distance weighting (IDW) technique for the spatiotemporal predictions of air pollutants at different time granularities. The BLSTM can effectively capture the long-term temporal mechanism of air pollution. The IDW layer, on the other hand, can consider the spatial correlation of air pollution and interpolate the spatial distribution. A case study is conducted to validate the effectiveness of the proposed methodology. The PM2.5 concentration at Guangdong, China is forecasted. Prediction performances of the LSTM network at hourly, daily, and weekly granularities and over different time spans are presented. Spatial distribution of the predicted PM2.5 concentrations and the prediction errors are analyzed. The experimental results demonstrate that the proposed method can achieve better prediction performance for the PM2.5 concentration compared with other models.
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