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JIANG, YONG-YUAN, and ZONG-JING SHEN. "GUIDING CHARACTERISTICS OF AN AIR WAVEGUIDE WITH LEFT-HANDED METAMATERIALS CLADDING." Journal of Nonlinear Optical Physics & Materials 17, no. 04 (2008): 465–71. http://dx.doi.org/10.1142/s021886350800441x.
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The characteristics of guided modes of a planar waveguide in which an air core is sandwiched by two left-handed metamaterials are studied. The dispersion relation of the guided modes in this air waveguide is derived where the left-handed metamaterials claddings can be either isotropic or uniaxially anisotropic. We analyze the fast and slow wave characteristics of the guided modes. The problem of whether the dispersion relation of slow wave modes has a solution is explored. The relation between the electromagnetic parameters of the waveguide and the solution of the dispersion relation of the slow wave modes is discussed in detail.
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KURT, H. "ALL-DIELECTRIC PERIODIC MEDIA ENGINEERED FOR SLOW LIGHT STUDIES." International Journal of Modern Physics B 27, no. 27 (2013): 1330020. http://dx.doi.org/10.1142/s021797921330020x.
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The paper presents various novel approaches to implementing slow light media by manipulating the group velocity via dispersion engineering of guided modes. Light is confined and then linked with a low group velocity inside a photonic crystal waveguide (PCW) and at the PC-air interface. We discuss both basic and engineered slow light waveguide structures. The structural changes in PCs greatly modify the spectral characteristics of the dispersion curves. The search for flat bands gives rise to various strategies for slowing the optical pulses. An appropriate and commonly adopted figure of merit (FOM) is accepted to quantify and characterize the performance of the designed slow light devices. The trade-off relationship between the group index and the bandwidth is highlighted. Efficient excitation of slow modes demands the design of additional interfaces as couplers between the input waveguide and slow mode guide structure. Other challenges of slow light studies, such as various loss sources, are mentioned. Finally, the potential applications of slow light are outlined, and remarks on future directions are presented.
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Liu, Qi, and Qi Chao Liu. "Slow Light Properties of 2D Photonic Crystal Waveguide for Optical Storage in Optical Computers." Advanced Materials Research 452-453 (January 2012): 1210–14. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1210.
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Slow light properties of the photonic crystal line-defect waveguide are researched with the plane wave expansion method. The structure of the waveguide is adjusted with several methods mentioned above at the same time and the slow light properties get better. For the structure of dielectric rods, central frequency and the group velocity of the guided modes decrease with the increase of the radii of the defected rods as well as the dielectric constant. Effects on the slow light from the change of the defected rods’ position are also studied, through moving the rods up and down; we get the almost linear guide mode which has flat slow light curve and smaller group velocity. In a word, group velocity of the slow light is mainly affected by the radii and dielectric constant of the defected rods, and group velocity dispersion is decided by the change of the defected rods’ location.
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Amorntep, W., and P. Wanchai. "Guided Modes of Slow Photon in Silicon Photonic Crystal Waveguide with Honeycomb Lattice." Advanced Science Letters 19, no. 3 (2013): 893–97. http://dx.doi.org/10.1166/asl.2013.4829.
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Li, Guofeng, Junbo Yang, Zhaojian Zhang, et al. "Double Electromagnetically Induced Transparency and Its Slow Light Application Based on a Guided-Mode Resonance Grating Cascade Structure." Materials 13, no. 17 (2020): 3710. http://dx.doi.org/10.3390/ma13173710.
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In recent years, the achievement of the electromagnetically induced transparency (EIT) effect based on the guided-mode resonance (GMR) effect has attracted extensive attention. However, few works have achieved a double EIT-like effect using this method. In this paper, we numerically achieve a double EIT-like effect in a GMR system with a three-layer silicon nitride waveguide grating structure (WGS), using the multi-level atomic system model for theoretical explanation. In terms of slow light performance, the corresponding two delay times reach 22.59 ps and 8.43 ps, respectively. We also investigate the influence of wavelength detuning of different GMR modes on the transparent window and slow light performance. Furthermore, a wide-band flat-top transparent window was also achieved by appropriately adjusting the wavelength detuning between GMR modes. These results indicate that the EIT-like effect in the WGS has potential application prospects in low-loss slow optical devices, optical sensing, and optical communications.
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Ballai, Istvan, Fisal Asiri, Viktor Fedun, Gary Verth, Emese Forgács-Dajka, and Abdulrahman B. Albidah. "Slow Body MHD Waves in Inhomogeneous Photospheric Waveguides." Universe 10, no. 8 (2024): 334. http://dx.doi.org/10.3390/universe10080334.
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The present study deals with the investigation of the oscillatory morphology of guided slow body MHD modes in inhomogeneous magnetic waveguides that appear in the solar photospheric plasmas in the forms of pores or sunspots. The eigenvalues and eigenfunctions related to these waves in an isothermal plasma are obtained numerically by solving a Sturm-Liouville problem with Dirichlet boundary conditions set at the boundary of the waveguide. Our results show that the inhomogeneities in density (pressure) and magnetic field have a strong influence on the morphology of waves, and higher-order more are sensitive to the presence of inhomogeneity. Our results suggest that he identification of modes just by a simple visual inspection can lead to a misinterpretation of the nature of modes.
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Laude, Vincent, Jean Charles Beugnot, Sarah Benchabane, et al. "Simultaneous guidance of slow photons and slow acoustic phonons in silicon phoxonic crystal slabs." Optics express 19, no. 10 (2011): 9690–98. https://doi.org/10.1364/OE.19.009690.
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We demonstrate theoretically that photons and acoustic phonons can be simultaneously guided and slowed down in specially designed nanostructures. Phoxonic crystal waveguides presenting simultaneous phononic and photonic band gaps were designed in perforated silicon membranes that can be conveniently obtained using silicon-on-insulator technology. Geometrical parameters for simultaneous photonic and phononic band gaps were first chosen for optical wavelengths around 1550 nm, based on the finite element analysis of a perfect phoxonic crystal of circular holes. A plain core waveguide was then defined, and simultaneous slow light and elastic guided modes were identified for some waveguide width. Joint guidance of light and elastic waves is predicted with group velocities as low as c=25 and 180 m/s, respectively.
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Djuve, Vilde Lunnan, Carl Henrik Knutsen, and Tore Wig. "Patterns of Regime Breakdown Since the French Revolution." Comparative Political Studies 53, no. 6 (2019): 923–58. http://dx.doi.org/10.1177/0010414019879953.
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We present a temporally fine-grained data set on regimes, defined as the formal and informal rules essential for selecting leaders. The data set comprises more than 2,000 regimes from 197 polities, 1789 to 2016. We highlight how the frequency of breakdowns and particular modes of breakdown have followed cyclical rather than monotonic patterns across modern history. The most common breakdown modes, overall, are coups and incumbent-guided regime transformations. Furthermore, we report robust evidence that low income, slow or negative growth, and intermediate levels of democracy predict a higher likelihood of regime breakdown. Yet, by running change-point analysis we establish that breakdown risk has cycled substantively across periods of modern history, and the aforementioned explanatory factors are more clearly related to breakdown during certain periods. When disaggregating different breakdown modes, low income is related to, for example, breakdown due to popular uprisings, whereas intermediate democracy levels clearly predict coup-induced breakdowns and incumbent-guided transitions.
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Fayard, Nikos, Adrien Bouscal, Jeremy Berroir, et al. "The comb waveguide: a new tool for strong interaction between atoms and light." EPJ Web of Conferences 266 (2022): 08002. http://dx.doi.org/10.1051/epjconf/202226608002.
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Coupling quantum emitters and nanostructures, in particular cold atoms and waveguides, has recently raised a large interest due to unprecedented possibilities of engineering light-matter interactions. However, the implementation of these promising concepts has been hampered by various theoretical and experimental issues. In this work, we propose a new type of periodic dielectric waveguide that provides strong interactions between atoms and guided photons with an unusual dispersion. We design an asymmetric comb waveguide that supports a slow mode with a quartic (instead of quadratic) dispersion and an electric field that extends far into the air cladding for an optimal interaction with atoms. We compute the optical trapping potential formed with two guided modes at frequencies detuned from the atomic transition. We show that cold Rubidium atoms can be trapped as close as 100 nm from the structure in a 1.3-mK-deep potential well. For atoms trapped at this position, the emission into guided photons is largely favored, with a beta factor as high as 0.88 and a radiative decay rate into the slow mode 10 times larger than the free-space decay rate.
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Kumari, Sheelu, Vibha Rani Gupta, and Shweta Srivastava. "Analysis of Narrow Slot Loading on a Half Guided Wavelength Folded Substrate Integrated Waveguide." ECTI Transactions on Electrical Engineering, Electronics, and Communications 19, no. 2 (2021): 174–81. http://dx.doi.org/10.37936/ecti-eec.2021192.241655.
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In this paper, effects due to variation in positioning, width and length of a narrow slot loaded on central metal septum of a half guided wavelength Folded Substrate Integrated Waveguide (FSIW) segment is presented. The study shows that the most significant effect is due to variation in slot length. It was observed that the slot loading can be used both for slow wave structure and filter depending on the length of the slot. The smaller lengths of the slot provide the slow wave effect, whereas the longer lengths result in filtering effect. Both the phenomena are explained with the help of field diagrams for different propagating modes and extracted equivalent circuit for the Slot Loaded Folded Substrate Integrated Waveguide (SFSIW) segment. This study will help in deciding the dimensions of the slot as per application. The measured scattering parameters of the fabricated structure are compared with the simulated results obtained from the HFSS and the circuit simulator in ADS and are in good agreement.
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Yu, Pengchao, Volodymyr I. Fesenko, and Vladimir R. Tuz. "Dispersion features of complex waves in a graphene-coated semiconductor nanowire." Nanophotonics 7, no. 5 (2018): 925–34. http://dx.doi.org/10.1515/nanoph-2018-0026.
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AbstractThe dispersion features of a graphene-coated semiconductor nanowire operating in the terahertz frequency band are consistently studied in the framework of a special theory of complex waves. Detailed classification of the waveguide modes was carried out based on the analysis of characteristics of the phase and attenuation constants obtained from the complex roots of characteristic equation. With such a treatment, the waves are attributed to the group of either “proper” or “improper” waves, wherein their type is determined as the trapped surface waves, fast and slow leaky waves, and surface plasmons. The dispersion curves of axially symmetric TM0n and TE0n modes, as well as nonsymmetric hybrid EH1n and HE1n modes, were plotted and analyzed in detail, and both radiative regime of leaky waves and guided regime of trapped surface waves are identified. The peculiarities of propagation of the TM modes of surface plasmons were revealed. Two subregions of existence of surface plasmons were found out where they appear as propagating and reactive waves. The cutoff conditions for higher-order TM modes of surface plasmons were correctly determined.
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Claes, N., and R. Keppens. "Thermal stability of magnetohydrodynamic modes in homogeneous plasmas." Astronomy & Astrophysics 624 (April 2019): A96. http://dx.doi.org/10.1051/0004-6361/201834699.
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Context. Thermal instabilities give rise to condensations in the solar corona, and are the most probable scenario for coronal rain and prominence formation. We revisit the original theoretical treatment done by Field (1965, ApJ, 142, 531) in a homogeneous plasma with heat-loss effects and combine this with state-of-the-art numerical simulations to verify growth-rate predictions and address the long-term non-linear regime. We especially investigate interaction between multiple magnetohydrodynamic (MHD) wave modes and how they in turn trigger thermal mode development. Aims. We assess how well the numerical MHD simulations retrieve the analytically predicted growth rates. We complete the original theory with quantifications of the eigenfunctions, calculated to consistently excite each wave mode. Thermal growth rates are fitted also in the non-linear regime of multiple wave–wave interaction setups, at the onset of thermal instability formation. Methods. We performed 2D numerical MHD simulations, including an additional (radiative) heat-loss term and a constant heating term to the energy equation. We mainly focus on the thermal (i.e. entropy) and slow MHD wave modes and use the wave amplitude as a function of time to make a comparison to predicted growth rates. Results. It is shown that the numerical MHD simulations retrieve analytically predicted growth rates for all modes, of thermal and slow or fast MHD type. In typical coronal conditions, the latter are damped due to radiative losses, but their interaction can cause slowly changing equilibrium conditions which ultimately trigger thermal mode development. Even in these non-linear wave-wave interaction setups, the growth rate of the thermal instability agrees with the exponential profile predicted by linear theory. The non-linear evolutions show systematic field-guided motions of condensations with fairly complex morphologies, resulting from thermal modes excited through damped slow MHD waves. These results are of direct interest to the study of solar coronal rain and prominence fine structure. Our wave–wave interaction setups are relevant for coronal loop sections which are known to host slow wave modes, and hence provide a new route to explain the sudden onset of coronal condensation.
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Huthwaite, P. "Improving accuracy through density correction in guided wave tomography." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (2016): 20150832. http://dx.doi.org/10.1098/rspa.2015.0832.
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The accurate quantification of wall loss caused by corrosion is critical to the reliable life estimation of pipes and pressure vessels. Traditional thickness gauging by scanning a probe is slow and requires access to all points on the surface; this is impractical in many cases as corrosion often occurs where access is restricted, such as beneath supports where water collects. Guided wave tomography presents a solution to this; by transmitting guided waves through the region of interest and exploiting their dispersive nature, it is possible to build up a map of thickness. While the best results have been seen when using the fundamental modes A0 and S0 at low frequency, the complex scattering of the waves causes errors within the reconstruction. It is demonstrated that these lead to an underestimate in wall loss for A0 but an overestimate for S0. Further analysis showed that this error was related to density variation, which was proportional to thickness. It was demonstrated how this could be corrected for in the reconstructions, in many cases resulting in the near-elimination of the error across a range of defects, and greatly improving the accuracy of life estimates from guided wave tomography.
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ALTMAN, C., and K. SUCHY. "Alfvén modes in a two-species magnetoplasma with anisotropic perturbation pressure-fluid and kinetic calculations." Journal of Plasma Physics 73, no. 4 (2007): 455–71. http://dx.doi.org/10.1017/s0022377806004764.
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AbstractThe octic fluid dispersion equation, the kinetic Boltzmann–Vlasov equation and the MHD (scalar pressure) analysis, programmed for a two-species collisionless magnetoplasma in a form permitting direct comparison between them, have been applied to the study of the Alfvén modes in both low- and high-β plasmas. In the low-βregime all methods give essentially the same solutions for the isotropic fast magnetosonic and the field-guided shear Alfvén modes. The real part of the refractive index of the field-guided slow magnetosonic acoustic mode is almost identical in the fluid and kinetic analyses, but is 50% too high in the MHD analysis owing to neglect of the trace-free part of the pressure tensor which drives almost half of the acoustic energy flux. The strong damping of the acoustic mode in both low- and high-β plasmas is drastically reduced by increase of electron temperature, whereas a moderate increase in the perpendicular ion temperature is sufficient to eliminate shear Alfvén damping in high-β plasmas and even to produce wave growth, the effect being more pronounced the higher the plasma β. The fluid analysis shows the electromagnetic energy flux to be negligible in the acoustic mode, in which the acoustic flux is driven both by the trace-carrying and trace-free parts of the pressure tensor, but is usually the dominant component in the (fast) magnetosonic mode.
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Ofman, Leon, and Tongjiang Wang. "Excitation and Damping of Slow Magnetosonic Waves in Flaring Hot Coronal Loops: Effects of Compressive Viscosity." Astrophysical Journal 926, no. 1 (2022): 64. http://dx.doi.org/10.3847/1538-4357/ac4090.
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Abstract Slow magnetosonic waves associated with flares were observed in coronal loops by Solar and Heliospheric Observatory/Solar Ultraviolet Measurements of Emitted Radiation, Solar Dynamics Observatory/Atmospheric Imaging Assembly in various EUV bandpasses, and other instruments. The excitation and damping of slow magnetosonic waves provides information on the magnetic, temperature, and density structure of the loops. Recently, it was found using 1.5D models that the thermal conduction is suppressed and compressive viscosity is enhanced in hot (T > 6 MK) flaring coronal loops. We model the excitation and dissipation of slow magnetosonic waves in hot coronal loops with realistic magnetic geometry, enhanced density, and temperature (compared to background corona) guided by EUV observations using a 3D magnetohydrodynamic (MHD) visco-resistive model. The effects of the compressive viscosity tensor component along the magnetic field are included with classical and enhanced viscosity coefficient values for the first time in a 3D MHD coronal loop model. The waves are excited by a velocity pulse at the footpoint of the loop at the coronal lower boundary. The modeling results demonstrate the excitation of the slow magnetosonic waves and nonlinear coupling to other wave modes, such as the kink and fast magnetosonic. We find significant leakage of the waves from the hot coronal loops with a small effect of viscous dissipation in cooler (6 MK) loops, and more significant effects of viscous dissipation in hotter (10.5 MK) coronal loops. Our results demonstrate that nonlinear 3D MHD models are required to fully account for the various wave couplings, damping, standing wave formation, and viscous dissipation in hot flaring coronal loops. Our viscous 3D MHD code provides a new tool for improved coronal seismology.
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Belloncle, Gaël, Francine Luppé, Hervé Franklin, and Jean-Marc Conoir. "Influence of the slow wave on the relation between the angular resonances and the leaky guided modes properties for a poroelastic plate embedded in water." Ultrasonics 42, no. 1-9 (2004): 511–14. http://dx.doi.org/10.1016/j.ultras.2004.01.098.
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Boko, Margaret Nampitjinpa, Rosalyn Boko, and Lisa Stefanoff. "Winimaku ara papa wiimatjaraku and other stories." Australian Journal of Anthropology 35, no. 1-2 (2024): 117–34. http://dx.doi.org/10.1111/taja.12488.
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AbstractThis audio‐visual essay invites readers to enter a new intermedial archive of documentary paintings and stories by a celebrated and prolific multilingual Central Australian Aboriginal woman artist. Addressing our written text to intimate family and audiences from elsewhere, in multiple voices and modes of address, we offer an opportunity to consider the dynamics of creating, keeping and caring for memory through the affordances of digital co‐creativity. These include what we term ‘painting remix animation’, a form of what co‐author Rosalyn Boko calls mixamilani (‘mixing together’ of different elements). Guided by the artist's vibrant palette and life‐expressive practice, visitors to the article can move and rest amongst a variety of standpoints through which to attune to questions of history, memory, pictorial storytelling, love, friendship and joy. We hope that in this way, everyone can sense the world‐making powers and poetics of colour and understand how our style of slow research towards digital mixamilani creates a new kind of archive for holding paintings carefully, outside of the art commodity market.
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Stuckenschneider, Lisa, and Peter L. Graumann. "Localization and Single Molecule Dynamics of Bacillus subtilis Penicillin-Binding Proteins Depend on Substrate Availability and Are Affected by Stress Conditions." Cells 14, no. 6 (2025): 429. https://doi.org/10.3390/cells14060429.
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We have used single molecule tracking to investigate dynamics of four penicillin-binding proteins (PBPs) in Bacillus subtilis to shed light on their possible modes of action. We show that Pbp2a, Pbp3, Pbp4, and Pbp4a, when expressed at very low levels, show at least two distinct states of mobility: a state of slow motion, likely representing molecules involved in cell wall synthesis, and a mode of fast motion, likely representing freely diffusing molecules. Except for Pbp4, all other PBPs showed about 50% molecules in the slow mobility state, suggesting that roughly half of all molecules are engaged in a substrate-bound mode. We observed similar coefficients for the slow mobility state for Pbp4 and Pbp4a on the one hand, and for Pbp2a and Pbp3 on the other hand, indicating possible joint activities, respectively. Upon induction of osmotic stress, Pbp2a and Pbp4a changed from a pattern of localization mostly at the lateral cell membrane to also include localization at the septum, revealing that sites of preferred positioning for these two PBPs can be modified during stress conditions. While Pbp3 became more dynamic after induction of osmotic stress, Pbp4 became more static, showing that PBPs reacted markedly differently to envelope stress conditions. The data suggest that PBPs could take over functions in cell wall synthesis during different stress conditions, increasing the resilience of cell wall homeostasis in different environmental conditions. All PBPs lost their respective localization pattern after the addition of vancomycin or penicillin G, indicating that patterns largely depend on substrate availability. Our findings show that PBPs rapidly alter between non-targeted motion through the cell membrane and capture at sites of active cell wall synthesis, most likely guided by complex formation with other cell wall synthesis enzymes.
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Wang, Jiayu, Guangyi Zhang, Qiaoli Wang, et al. "Improved Thin-Kerf Processing in Cf/SiC Composite by Waterjet-Guided Nanosecond Laser Decreases Oxidation and Thermal Effect." Materials 18, no. 7 (2025): 1560. https://doi.org/10.3390/ma18071560.
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As a hard and brittle material, the processing of Cf/SiC ceramic matrix composites (CMCs) faces significant challenges, especially in the processing of small-sized shapes. To address this challenge, laser processing with gas-assisted nanosecond laser (GNL) and waterjet-guided nanosecond laser (WNL) modes were applied to fabricate thin kerfs in the Cf/SiC composite. The surface morphology, microstructure, and chemical composition of the processed Cf/SiC composite were investigated comparatively. The results revealed that the coupling of helium in the GNL mode laser processing could make full use of the laser energy, but resulted in spattering in the kerf margin and a recast layer in the kerf surface, accompanied by obvious oxidation, while the coupling of the waterjet in the WNL mode laser processing decreased the oxidation significantly and removed the remelting debris, which produced a clear and flat kerf surface. Due to the taper caused by laser energy dissipation, the single-path laser processing in the Cf/SiC composite had a limited depth. The maximum depth of the kerf prepared by single-path laser processing with the GNL mode was about 328 μm, while that with the WNL mode was about 302 μm. The multi-path laser processing with the GNL and WNL modes could fabricate a through kerf in the Cf/SiC composite, but the coupling medium obviously influenced the surface morphology and microstructure of the underlying region. The kerf surface prepared by the GNL mode had a varied surface morphology, which transited from the top layer, covered with oxide particles and some cracks, to the bottom layer, featured with micro-grooves and small oxides. The kerf surface prepared by the WNL mode had a consistently smooth and clean morphology featured with broken carbon fiber and residual SiC matrix. The slow laser energy dissipation and open environment in the GNL mode resulted in a bigger HAZ and relatively serious oxidation, which caused local phase transformation and microstructure degradation. The isolation condition and rapid cooling in the WNL mode decreased the HAZ and restrained the oxidation, almost keeping the original microstructure. The thicknesses of the HAZ in the GNL- and WNL-processed Cf/SiC composite were about 200 μm and 100 μm, respectively. The WNL-processed Cf/SiC composite had a lower oxidation and thermal damage surface, which is instructive for the processing of the Cf/SiC composite.
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Kazys, Rymantas Jonas, Liudas Mazeika, and Justina Sestoke. "Development of Ultrasonic Techniques for Measurement of Spatially Non-Uniform Elastic Properties of Thin Plates by Means of a Guided Sub-Sonic A0 Mode." Applied Sciences 10, no. 9 (2020): 3299. http://dx.doi.org/10.3390/app10093299.
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Air-coupled ultrasonic guided A0 mode is already used for material characterization. By measuring the phase velocity of the A0 mode the elastic properties, such as the Young’s modulus, can be determined. The objective of this work was the development of measurement methods and corresponding signal processing procedures enabling the acquisition of spatial distributions of non-uniform elastic properties of thin films and plates. Those methods are based on the excitation of a slow sub-sonic A0 Lamb wave mode in a plate, the measurement of normal displacements at different distances from the source, the formation of the B-scan, and processing the collected signals. Two different signal processing methods were proposed and investigated. In the first method the all zero-crossing instants of the ultrasonic signals at different distances are found and from them spatial distributions of the A0 mode velocity are determined. According to the second method 2D spatial-temporal spectrum of the B-scan is calculated and propagating A0 modes with different velocities are identified. Efficiency of the proposed methods was evaluated theoretically and experimentally using thin mineral MICA paper samples, which is used in the electrical and aerospace industries as an insulating material. The zones with different A0 mode phase velocities (95 ± ∆3 m/s and (106 ± ∆6 m/s) at the frequency 47 kHz were identified.
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Kehrer, Andreas, Paul I. Heidekrueger, Daniel Lonic, et al. "Technical Aspects of High-Resolution Color-Coded Duplex Sonography for the Design of Perforator Flaps." Journal of Reconstructive Microsurgery 38, no. 03 (2022): 181–92. http://dx.doi.org/10.1055/s-0041-1740956.
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Abstract Background Technical aspects are of utmost significance for an efficient execution in designing perforator flaps with high-resolution color-coded Duplex sonography (CCDS). The following study evaluates decisive factors for a successful microvessel examination conducted by the microsurgeon. Methods Technical knowledge presented in this study was based on a series of more than 200 perforator flaps planned with CCDS. Flap reconstructions were performed at the University Hospital Regensburg, Germany, from July 2013 to January 2021. Standard high-resolution ultrasound (US) devices with linear multifrequency transducers of 4 to 18 MHz were used. Modes and device settings were evaluated regarding applicability by microsurgeons. Key steps for safe perforator identification and further optional steps for additional assessment should be discriminated. Results Different US modes including brightness mode (B-mode), color flow (CF), power Doppler (PD), pulse wave (PW), and blood flow (B-Flow) were used. Transducers from 15 MHz and up were favorable to detect microvessels. Knobology of a standard US device regarding buttons, switches, and specific onscreen options with relevance for perforator mapping was subcategorized in four different groups. For qualitative and quantitative evaluation of microvessels, different US modes were tested with respect to their usefulness.Vital elements of the CCDS exam are disaggregated into three key steps for safe perforator identification and three optional steps for further perforator characterization. A standardized protocol for the CCDS exams was applied. Downregulation of pulse-repetition frequency/scale to adapt device sensitivity to slow-flow velocities represented the most important criterion to visualize microvessels.Qualitative microvessel evaluation was performed in B-mode, CCDS, PD mode, and B-Flow mode. Quantitative assessment was executed using PW-mode and CCDS measuring the microvessels' diameter (mm) and flow characteristics. Quantitative information may be obtained using PW-mode and the distance-measuring tool in CF-mode. Conclusion Technical aspects with respect to proper device trimming and application decisively impact CCDS-guided perforator vessel identification and evaluation.
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Korneev, Valeri, Ludmila Danilovskaya, Seiji Nakagawa, and George Moridis. "Krauklis wave in a trilayer." GEOPHYSICS 79, no. 4 (2014): L33—L39. http://dx.doi.org/10.1190/geo2013-0216.1.
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The Krauklis wave is a slow dispersive wave mode that propagates in a fluid layer bounded by elastic media. The guided properties of this wave and its ability to generate very short wavelengths at seismic frequency range predict possibility of resonances in fluid-filled rock fractures. Study of Krauklis wave properties at laboratory scales requires evaluation of its propagation velocities in models with finite and thin elastic walls. Analysis of an exact solution for a fluid-filled trilayer with equal thickness plates reveals existence of the Krauklis waves in such a model, as well as another mode which propagates mostly in the solid part. Both propagation modes exist at all frequencies. We derived and verified various asymptotic solutions by comparing their dependencies on layer thicknesses and frequency with the exact numerical solution. Analytical and computational results demonstrate that in a 60-cm-long model, the first resonant frequency can be below 10 Hz. This result suggests that the Krauklis-wave effects can be studied in a laboratory at seismic range of frequencies avoiding a notorious problem of frequency downscaling. Strong dispersive properties of Krauklis waves and their dominant behavior in fluid-fracture systems are likely phenomena explaining the observed frequency-dependent seismic effects in natural underground reservoirs.
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Schmitt, Denis P., Michel Bouchon, and Guy Bonnet. "Full‐wave synthetic acoustic logs in radially semiinfinite saturated porous media." GEOPHYSICS 53, no. 6 (1988): 807–23. http://dx.doi.org/10.1190/1.1442516.
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The wave field generated by a point source in an axisymmetric fluid‐filled borehole embedded in a saturated porous formation is studied in both the spectral domain and time domain. The formation is modeled following Biot theory modified in accordance with homogenization theory. When the borehole wall is permeable, guided waves can be significantly affected by the permeability of the formation. Whatever the formation, fast or slow, Stoneley‐wave phase velocity and energy decrease and attenuation (in the sense of [Formula: see text]) increases with increasing permeability. These effects are more important in the very low‐frequency range, where Darcy’s law governs the fluid motion and the wave energy at the interface is maximum, than at higher frequencies. The effects increase and persist over a larger frequency range with decreasing viscosity and increasing compressibility of the saturant fluid, with increasing pore‐fluid volume, and with decreasing borehole radius. In contrast, the effects decrease with decreasing stiffness of the formation because of more efficient coupling of the interface wave to the surrounding medium. When present, the first pseudo‐Rayleigh mode also carries useful information. Fluid flow affects only the attenuation of the pseudo‐Rayleigh mode’s Airy phase; an increase in attenuation may be used to detect permeable zones and to infer the saturant fluid properties. However, the most reliable types of information are the formation shear‐wave velocity and attenuation from the low‐frequency part of the mode. In the time domain, all the modes overlap. Any signal processing should then be performed in the frequency domain, where mode spectra are more easily separable. The frequency band of the actual logging tool has to be large enough to ensure significant amplitude for each mode. Finally, the larger the number of receivers and the offset range, the better.
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Ghanekar, A., R. Kapadia, and M. L. Povinelli. "Directional control of absorptivity with quasi-localized guided modes." Applied Physics Letters 121, no. 20 (2022): 201701. http://dx.doi.org/10.1063/5.0123685.
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We present a guided mode resonance grating that exhibits high-Q resonances with highly selective directional absorption around 3.7 μm. The grating is designed to create slow guided mode resonances with near-flat dispersion relation. Weakly coupled resonators enable such resonances with small dispersion characteristics. We study the dynamic control of directional absorption using the design presented. We show that weaker dispersion of resonance frequency allows a strong sensitivity concerning the directionality of resonance. Our results indicate that the directionality of absorption can be tuned from normal incidence (0°) to approximately 35° upon small index perturbation. The design presents a pathway toward tunable directional absorption and emission.
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Ryskin, Nikita. "Modulational instability of space-charge waves." Izvestiya VUZ. Applied Nonlinear Dynamics 2, no. 3 (1994): 93–100. https://doi.org/10.18500/0869-6632-1994-2-5-93-100.
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Modulational instability of space-charge waves in a strongly magnetized cylindrical charge-neutralized electron beam in a cylindrical wave guide is investigated. For slowly varying amplitudes of fast and slow space-charge modes a system of coupled nontinear Schrodinger equations is derived. It is shown, that because of the interaction between the fast and slow modes, waves of almost all wave numbers are modulationally unstable.
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KIRINO, Hideki, Kazuhiro HONDA, Kun LI, and Koichi OGAWA. "A Waffle-Iron Ridge Guide with Combined Fast- and Slow-Wave Modes for Array Antenna Applications." IEICE Transactions on Communications E101.B, no. 2 (2018): 349–56. http://dx.doi.org/10.1587/transcom.2017isp0013.
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Dargaville, Peter A. "Respiratory Support in Meconium Aspiration Syndrome: A Practical Guide." International Journal of Pediatrics 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/965159.
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Meconium aspiration syndrome (MAS) is a complex respiratory disease of the term and near-term neonate. Inhalation of meconium causes airway obstruction, atelectasis, epithelial injury, surfactant inhibition, and pulmonary hypertension, the chief clinical manifestations of which are hypoxaemia and poor lung compliance. Supplemental oxygen is the mainstay of therapy for MAS, with around one-third of infants requiring intubation and mechanical ventilation. For those ventilated, high ventilator pressures, as well as a relatively long inspiratory time and slow ventilator rate, may be necessary to achieve adequate oxygenation. High-frequency ventilation may offer a benefit in infants with refractory hypoxaemia and/or gas trapping. Inhaled nitric oxide is effective in those with pulmonary hypertension, and other adjunctive therapies, including surfactant administration and lung lavage, should be considered in selected cases. With judicious use of available modes of ventilation and adjunctive therapies, infants with even the most severe MAS can usually be supported through the disease, with an acceptably low risk of short- and long-term morbidities.
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Andersson, Nils, and Fabian Gittins. "Formulating the r-mode Problem for Slowly Rotating Neutron Stars." Astrophysical Journal 945, no. 2 (2023): 139. http://dx.doi.org/10.3847/1538-4357/acbc1e.
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Abstract We revisit the problem of inertial r-modes in stratified stars, drawing on a more precise description of the composition stratification in a mature neutron star. The results highlight issues with the traditional approach to the problem, leading us to rethink the computational strategy for the r-modes of nonbarotropic neutron stars. We outline two strategies for dealing with the problem. For moderate to slowly rotating neutron stars the only viable alternative may be to approach the problem numerically from the outset, while a meaningful slow-rotation calculation can be carried out for the fastest known spinning stars (which may be close to being driven unstable by the emission of gravitational waves). We demonstrate that the latter approach leads to a problem close, but not identical, to that for barotropic inertial modes. We also suggest that these reformulations of the problem likely resolve the long-standing problem of singular behavior associated with a corotation point in rotating relativistic neutron stars. This issue needs to be resolved in order to guide future gravitational-wave searches.
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Thompson, Christopher. "Radio Emission of Pulsars. I. Slow Tearing of a Quantizing Magnetic Field." Astrophysical Journal 933, no. 2 (2022): 231. http://dx.doi.org/10.3847/1538-4357/ac501f.
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Abstract The pulsed radio emission of rotating neutron stars is connected to slow tearing instabilities feeding off an inhomogeneous twist profile within the open circuit. This paper considers the stability of a weakly sheared, quantizing magnetic field in which the current is supported by a relativistic particle flow. The electromagnetic field is almost perfectly force free, and particles are confined to the lowest Landau state, experiencing no appreciable curvature drift. In a charge-neutral plasma, we find multiple branches of slowly growing tearing modes, relativistic analogs of the double-tearing mode, with peak growth rate s ≳ 4 π k ˜ y J z / B z . Here, B z is the strong (nearly potential) guide magnetic field, J z the field-aligned current density, and k ˜ y is the mode wavenumber normalized by the current gradient scale. These modes are overstable when the plasma carries a net charge, with the real frequency ω ∼ s · ∣ n 0 + − n 0 − ∣ / ( n 0 + + n 0 − ) proportional to the imbalance in the densities of positive and negative charges. An isolated current sheet thinner than the skin depth supports localized tearing modes with growth rate scaling as (sheet thickness/skin depth)−1/2. In a pulsar, the peak growth rate is comparable to the angular frequency of rotation, s ≳ 2 k ˜ y Ω , slow compared with the longitudinal oscillations of particles and fields in a polar gap. The tearing modes experience azimuthal drift reminiscent of subpulse drift and are a promising driver of pulse-to-pulse flux variations. A companion paper demonstrates a Cerenkov-like instability of current-carrying Alfvén waves in thin current sheets with relativistic particle flow and proposes coherent curvature emission by these waves as a source of pulsar radio emission.
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Nicolaidou, Evangelia, Thomas L. Hill, and Simon A. Neild. "Detecting internal resonances during model reduction." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2250 (2021): 20210215. http://dx.doi.org/10.1098/rspa.2021.0215.
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Model order reduction of geometrically nonlinear dynamic structures is often achieved via a static condensation procedure, whereby high-frequency modes are assumed to be quasi-statically coupled to a small set of lower frequency modes, which form the reduction basis. This approach is mathematically justifiable for structures characterized by slow/fast dynamics, such as thin plates and slender beams, and has been shown to provide highly accurate results. Nevertheless, selecting the reduction basis without a priori knowledge of the full-order dynamics is a challenging task; retaining redundant modes will lead to computationally suboptimal reduced-order models (ROMs), while omitting dynamically significant modes will lead to inaccurate results, and important features such as internal resonances may not be captured. In this study, we demonstrate how the error associated with static condensation can be efficiently approximated during model reduction. This approximate error can then be used as the basis of a method for predicting when dynamic modal interactions will occur, which will guide the reduction basis selection process. Equivalently, this may serve as a tool for verifying the accuracy of ROMs without the need for full-order simulations. The proposed method is demonstrated using a simple oscillator and a finite element model of a clamped–clamped beam.
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Roberts, B. "Waves in Magnetic Flux Tubes." Symposium - International Astronomical Union 142 (1990): 159–74. http://dx.doi.org/10.1017/s0074180900087891.
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The basic aspects of wave propagation in a magnetic flux tube are reviewed, with particular emphasis on the types of flux tube that occur in the solar atmosphere. Two fundamental speeds arise naturally in a description of wave propagation in a flux tube: the slow magnetoacoustic (cusp) speed cT, which is both subsonic and sub-Alfvénic, and a mean Alfvén speed ck. Both surface and body modes are supported by a tube. It is stressed that a flux tube may act as a wave guide, similar to the guidance of light by a fibre optic, or sound in an ocean layer, or seismic waves in the Earth's crust.
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Chen, Hongting, Zhaojian Zhang, Xiao Zhang, Yunxin Han, Zigang Zhou, and Junbo Yang. "Multifunctional Plasmon-Induced Transparency Devices Based on Hybrid Metamaterial-Waveguide Systems." Nanomaterials 12, no. 19 (2022): 3273. http://dx.doi.org/10.3390/nano12193273.
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In this paper, we design a multifunctional micro-nano device with a hybrid metamaterial-waveguide system, which leads to a triple plasmon-induced transparency (PIT). The formation mechanisms of the three transparent peaks have their own unique characteristics. First, PIT-I can be switched into the BIC (Friedrich–Wintge bound state in continuum), and the quality factors (Q-factors) of the transparency window of PIT-I are increased during the process. Second, PIT-II comes from near-field coupling between two bright modes. Third, PIT-III is generated by the near-field coupling between a low-Q broadband bright mode and a high-Q narrowband guide mode, which also has a high-Q transparent window due to the guide mode. The triple-PIT described above can be dynamically tuned by the gate voltage of the graphene, particularly for the dynamic tuning of the Q values of PIT-I and PIT-III. Based on the high Q value of the transparent window, our proposed structure can be used for highly sensitive refractive index sensors or devices with prominent slow light effects.
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Smith, Eliot R., and Jamie DeCoster. "Dual-Process Models in Social and Cognitive Psychology: Conceptual Integration and Links to Underlying Memory Systems." Personality and Social Psychology Review 4, no. 2 (2000): 108–31. http://dx.doi.org/10.1207/s15327957pspr0402_01.
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Models postulating 2 distinct processing modes have been proposed in several topic areas within social and cognitive psychology. We advance a new conceptual model of the 2 processing modes. The structural basis of the new model is the idea, supported by psychological and neuropsychological evidence, that humans possess 2 memory systems. One system slowly learns general regularities, whereas the other can quickly form representations of unique or novel events. Associative retrieval or pattern completion in the slow-learning system elicited by a salient cue constitutes the effortless processing mode. The second processing mode is more conscious and effortful; it involves the intentional retrieval of explicit, symbolically represented rulesfrom either memory system and their use to guide processing. After presenting our model, we review existing dual-process models in several areas, emphasizing their similar assumptions of a quick, effortless processing mode that rests on well-learned prior associations and a second, more effortful processing mode that involves rule-based inferences and is employed only when people have both cognitive capacity and motivation. New insights and implications of the model for several topic areas are outlined.
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Liebich, Alina, Shenglin Zheng, Theresa Schachner, et al. "Non-pharmaceutical interventions and epigenetic aging in adults: Protocol for a scoping review." PLOS ONE 19, no. 8 (2024): e0301763. http://dx.doi.org/10.1371/journal.pone.0301763.
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Introduction Aging is the strongest risk factor for most chronic diseases. The rising burden of an aging population and non-communicable diseases (NCDs), contributes to escalating costs for society. Several non-pharmaceutical interventions can lower the risk of NCDs, including common mental disorders (CMDs), and may slow down biological aging, as evidenced by outcome markers such as epigenetic clocks. However, a comprehensive overview of whether and which non-pharmaceutical interventions may impact human epigenetic aging is missing. Synthesizing evidence of interventions on epigenetic aging that can be adopted by a wider population is key to guide healthy aging initiatives and to reduce the burden of NCDs and CMDs. This scoping review will identify and assess non-pharmaceutical interventions aimed to slow down epigenetic aging, including their intervention components, and the mode used for intervention delivery. Methods and analysis This protocol will include single- and multicomponent intervention studies that target individuals ≥ 18 years of age and use epigenetic clocks as primary or secondary outcomes. Five electronic databases will be searched for studies between July 2011 until December 2023. The final search will include the search terms adults, non-pharmaceutical interventions, epigenetic aging and their respective synonyms. We will include randomized controlled trials, non-randomized controlled studies, cohort studies, and case-control studies. Additionally, the reference list of other reviews will be screened for relevant articles. Study selection is carried out based on the defined eligibility criteria by two authors. Quality and risk of bias for the included studies will be assessed using the Critical Appraisal Skills Programme (CASP) checklist. Data extraction will include generic key information such as the research question and results, the intervention components, and specific epigenetic outcome measures used. Further data regarding the delivery mode of the treatment protocol will be collected. Ethics and dissemination This scoping review will summarize the characteristics of non-pharmaceutical intervention studies on epigenetic aging. This review will be the first step to formally identify key intervention components and delivery modes to guide future research on healthy aging interventions. The results will be disseminated through a peer-reviewed publication and presented at relevant conferences. This review will synthesize information from available publications and does not require further ethical approval. Registration details Open Science Framework https://doi.org/10.17605/OSF.IO/FEHNB.
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Xu, Zhen, and Shudan Zheng. "Research on the "multi-agent co-governance" system of unfair competition on internet platforms: Based on the perspective of evolutionary game." PLOS ONE 19, no. 4 (2024): e0301627. http://dx.doi.org/10.1371/journal.pone.0301627.
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Unfair competition on internet platforms (UCIP) has become a critical issue restricting the platform economy’s healthy development. This paper applies evolutionary game theory to study how to utilize multiple subjects’ synergy to supervise UCIP effectively. First, the "multi-agent co-governance" mode of UCIP is constructed based on the traditional "unitary supervision" mode. Second, the government and internet platform evolutionary game models are built under two supervision modes. Finally, MATLAB is used to simulate and analyze the evolutionary stage and parameter sensitivity. In addition, we match the model’s evolutionary stage with China’s supervisory process. The results show that (1) the Chinese government’s supervision of UCIP is in the transitional stage from "campaign-style" to "normalization." (2) Moderate government supervision intensity is essential to guide the game system to evolve toward the ideal state. If the supervision intensity is too high, it will inhibit the enthusiasm for supervision. If the supervision intensity is too low, it cannot form an effective deterrent to the internet platforms. (3) When the participation of industry associations and platform users is low, it can only slow down the evolutionary speed of the game system’s convergence to the unfavorable state. Nevertheless, it cannot reverse the evolutionary result. (4) Maintaining the participation level of industry associations and platform users above a specific threshold value while increasing punishment intensity will promote the transition of government supervision from the "campaign-style" to the "normalization" stage. This paper provides ideas and references for the Chinese government to design a supervision mechanism for UCIP.
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Zou, Jiexin, Ning Han, Jiangyan Yan, et al. "Electrochemical Compression Technologies for High-Pressure Hydrogen: Current Status, Challenges and Perspective." Electrochemical Energy Reviews 3, no. 4 (2020): 690–729. http://dx.doi.org/10.1007/s41918-020-00077-0.
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Abstract Hydrogen is an ideal energy carrier in future applications due to clean byproducts and high efficiency. However, many challenges remain in the application of hydrogen, including hydrogen production, delivery, storage and conversion. In terms of hydrogen storage, two compression modes (mechanical and non-mechanical compressors) are generally used to increase volume density in which mechanical compressors with several classifications including reciprocating piston compressors, hydrogen diaphragm compressors and ionic liquid compressors produce significant noise and vibration and are expensive and inefficient. Alternatively, non-mechanical compressors are faced with issues involving large-volume requirements, slow reaction kinetics and the need for special thermal control systems, all of which limit large-scale development. As a result, modular, safe, inexpensive and efficient methods for hydrogen storage are urgently needed. And because electrochemical hydrogen compressors (EHCs) are modular, highly efficient and possess hydrogen purification functions with no moving parts, they are becoming increasingly prominent. Based on all of this and for the first time, this review will provide an overview of various hydrogen compression technologies and discuss corresponding structures, principles, advantages and limitations. This review will also comprehensively present the recent progress and existing issues of EHCs and future hydrogen compression techniques as well as corresponding containment membranes, catalysts, gas diffusion layers and flow fields. Furthermore, engineering perspectives are discussed to further enhance the performance of EHCs in terms of the thermal management, water management and the testing protocol of EHC stacks. Overall, the deeper understanding of potential relationships between performance and component design in EHCs as presented in this review can guide the future development of anticipated EHCs. Graphic Abstract
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Kroon, Sjaak, and Massimiliano Spotti. "L1 Education in Times of Globalization, Digitalization and Super-Diversity." L1-Educational Studies in Language and Literature 24, no. 2 (2024): 1–19. http://dx.doi.org/10.21248/l1esll.2024.24.2.673.
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This introduction first briefly sketches the (history of the) International Mother Tongue Education Network (IMEN). IMEN was founded in 1981 as an information and research network that over the years initiated an empirical-interpretive research program focusing on comparative analyses of the rhetoric and practices of L1 education across a dozen of European countries. Main elements of IMEN’s methodology that will be discussed below were the development of different types of research collaboration, a theoretical framework for comparative analysis, and a method for international triangulation. It then describes how, at the turn of the century, IMEN’s way of doing slow science became increasingly threatened by the requirements of publish or perish mainstream research, and how its research program was confronted with the challenges posed to L1 education by processes of globalization, digitalization, and super-diversity, becoming manifest in the superdiverse nature of student bodies, their sociolinguistic and ethnocultural doings, and the increasingly digitalized modes of teaching and learning they are exposed to. All these elements, in one way or another, also have an impact on the teaching-learning practices in mainstream L1 education and consequently must be addressed by IMEN-like studies. Finally this contribution briefly introduces the contributions to this special issue and suggests that they are a strong argument for a renewed interest in international comparative discussion on and around L1 education and a plea to further collaborative research from an empirical interpretive ethnographic perspective on teachers’ professional practical knowledge and classroom practices that can guide our understanding of the ubiquitous school subject L1 education that aims at preparing students for a global, digital, and super-diverse society.
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Elgammal, Ramez Ahmed, Carla Cecilia Fraenza, Thomas A. Zawodzinski, and Steven Greenbaum. "Lithium Ion Battery Electrolytes Based on Deep Eutectic Solvents." ECS Meeting Abstracts MA2023-01, no. 2 (2023): 547. http://dx.doi.org/10.1149/ma2023-012547mtgabs.
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Deep eutectic solvents (DESs) have emerged as an alternative to both common organic solvents and ionic liquids (ILs). DESs share physicochemical properties with ILs such as low vapor pressure, high thermal stability, while offering advantages such as low toxicity, lower cost, and ease of preparation. Moreover, DESs are attractive candidates for electrochemical applications due to their large voltage windows and solubility properties. DESs as a solvent class share a general composition of a hydrogen bond donor (HBD), typically a polyol, amide, or acid, and a hydrogen bond acceptor (HBA), usually a quaternary ammonium or phosphonium salt. At a specific molar composition of a HBD and HBA, the DES forms a eutectic mixture resulting in a large melting point depression. Despite being widely studied, the microscopic structures of DESs have remained largely uncharacterized. Herein, we present a multitechnique NMR study of ethaline (ethylene glycol + choline chloride). Pulsed field gradient diffusion, nuclear Overhauser effect spectroscopy (NOESY), 13C NMR relaxation experiments are deployed to sample a range of frequencies and modes of motion of the polyol and choline components of the DES. Generally, translational and rotational diffusion of polyols are more rapid than those of choline while short-range rotational motions observed from 13C relaxation indicate slow local motion of ethylene glycol at low choline chloride (ChCl) content. Additionally, we have investigated the solubility properties of several lithium salts (LiTFSI, LiFSI, LiBF4, and LiOAc) in these DESs and utilized the same suite of NMR techniques to understand how they act as solvents. One interesting observation is that the Li+ diffusivity exceeds that of the counterion for TFSI-, but not for FSI-. Finally, large changes in the structural organization of DESs that result from the presence of lithium salts may serve as a guide to the design of a new class of electrolytes for lithium-ion batteries.
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Elgammal, Ramez A., Carla Cecilia Fraenza, Steven Greenbaum, and Thomas A. Zawodzinski. "(Digital Presentation) Fundamentals of Deep Eutectic Solvents As Electrolytes for Lithium-Ion Batteries." ECS Meeting Abstracts MA2022-02, no. 46 (2022): 1719. http://dx.doi.org/10.1149/ma2022-02461719mtgabs.
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Deep eutectic solvents (DESs) have emerged as an alternative to both common organic solvents and ionic liquids (ILs). DESs share physicochemical properties with ILs such as low vapor pressure, high thermal stability, high viscosity while offering advantages such as low toxicity, lower cost, and ease of preparation. Moreover, DESs are attractive candidates for electrochemical applications due to their large voltage windows and solubility properties. DESs as a solvent class share a general composition of a hydrogen bond donor (HBD), typically a polyol, amide, or acid, and a hydrogen box acceptor (HBA), usually a quaternary ammonium or phosphonium salt. At a specific molar composition of a HBD and HBD, the DES forms a eutectic mixture resulting in a large melting point depression due to extensive hydrogen bonding between the components. Despite being widely studied, the microscopic structures of DESs have remained largely uncharacterized. Herein, we present a multitechnique NMR study of two DESs: glyceline (glycerol + choline chloride) and ethaline (ethylene glycol + choline chloride). Fast-field cycling 1H relaxometry, pulsed field gradient diffusion, nuclear Overhauser effect spectroscopy (NOESY), 13C NMR relaxation, and pressure-dependent NMR experiments are deployed to sample a range of frequencies and modes of motion of the polyol and choline components of the DES. Generally, translational and rotational diffusion of polyols are more rapid than those of choline while short-range rotational motions observed from 13C relaxation indicate slow local motion of glycerol at low choline chloride (ChCl) content. We show how the additional hydroxyl group present in glycerol contributes to not only higher viscosities, but a larger perturbation of the hydrogen bonding network by the addition of ChCl. Additionally, we have investigated the solubility properties of several lithium salts (LiTFSI, LiFSI, LiPF6, LiBF4, and LiOAc) in these DESs and utilized the same suite of NMR techniques to understand how they act as solvents. We observe that due to anion effects, the heterogeneities present in DES result in differential solvation for some species where there is a distinction of lithium salts co-existing in these holes as well as the bulk. The large changes in the structural organization of DESs that result from the presence of lithium salts will serve as a guide to the design of a new class of electrolytes for lithium-ion batteries.
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Djuanda, Lyon Ambrosio, Muthia Nis Tiadah, Ananda Hisma Putra Kristianto, Fatih Akbar Alim Putra, Aufa Putra Wicaksono, and Florentina Yuni Arini. "Analisis Pengalaman Pengguna dari Segi Fitur "Search for a Pickup" dan "Search for a Destination" pada Gocar dalam Aplikasi Gojek." Jurnal Ilmiah ILKOMINFO - Ilmu Komputer & Informatika 8, no. 1 (2025): 72–86. https://doi.org/10.47324/ilkominfo.v8i1.287.
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Abstrak: Layanan GoCar pada aplikasi Gojek memberikan kemudahan bagi pengguna dalam mencari moda transportasi mobil. Penelitian ini menganalisis layanan GoCar pada aplikasi Gojek dengan fokus pada fitur "Search for a Pickup" dan "Search for a Destination" menggunakan metode studi literatur dan System Usability Scale (SUS) sebagai alat ukur penilaian kegunaan, dengan SPSS sebagai tool untuk menganalisis hasil pengukuran. Kajian ini meninjau berbagai literatur yang relevan terkait pengalaman pengguna, dengan analisis menggunakan parameter SUS yang mencakup aspek pengalaman pengguna, kemudahan penggunaan, kecepatan respon, dan tingkat kepuasan pengguna. Hasil analisis menunjukkan bahwa fitur "Search for a Destination" memiliki performa yang baik dalam aspek kemudahan penggunaan dan antarmuka, namun menghadapi tantangan signifikan dalam kecepatan respon dan akurasi, terutama pada jam-jam sibuk. Ketidakakuratan geolokasi di area dengan sinyal GPS lemah dan lambatnya respon server menjadi kendala utama yang mempengaruhi pengalaman pengguna. Berdasarkan analisis SUS, penelitian ini mengidentifikasi bahwa optimasi algoritma pencarian, pengembangan sistem geolokasi yang lebih akurat, dan peningkatan infrastruktur server diperlukan untuk meningkatkan kualitas kedua fitur tersebut. Hasil penelitian ini dapat menjadi panduan praktis bagi pengembang dalam memperbaiki kualitas layanan di masa mendatang.Kata kunci: GoCar, pengalaman pengguna, System Usability Scale (SUS), kemudahan penggunaan, kecepatan respon, tingkat kepuasan penggunaGoCar service on the Gojek application provides convenience for users in finding car transportation modes. This study analyzes the GoCar service on the Gojek application, focusing on the "Search for a Pickup" and "Search for a Destination" features using literature study methods and the System Usability Scale (SUS) as a usability assessment tool, with SPSS as a tool to analyze the measurement results. This study reviews various relevant literature related to user experience, with analysis using SUS parameters that include aspects of user experience, ease of use, response speed, and user satisfaction levels. The analysis results show that the "Search for a Destination" feature performs well in terms of ease of use and interface, but faces significant challenges in response speed and accuracy, especially during peak hours. Geolocation inaccuracies in areas with weak GPS signals and slow server response are the main constraints affecting user experience. Based on SUS analysis, this study identifies that search algorithm optimization, development of more accurate geolocation systems, and server infrastructure improvements are needed to enhance the quality of both features. The results of this study can serve as a practical guide for developers in improving service quality in the future.Keywords: GoCar, user experience, System Usability Scale (SUS), ease of use, response speed, user satisfaction level
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Bell, Lauren, Claire Garnett, Tianchen Qian, Olga Perski, Elizabeth Williamson, and Henry WW Potts. "Engagement With a Behavior Change App for Alcohol Reduction: Data Visualization for Longitudinal Observational Study." Journal of Medical Internet Research 22, no. 12 (2020): e23369. http://dx.doi.org/10.2196/23369.
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Background Behavior change apps can develop iteratively, where the app evolves into a complex, dynamic, or personalized intervention through cycles of research, development, and implementation. Understanding how existing users engage with an app (eg, frequency, amount, depth, and duration of use) can help guide further incremental improvements. We aim to explore how simple visualizations can provide a good understanding of temporal patterns of engagement, as usage data are often longitudinal and rich. Objective This study aims to visualize behavioral engagement with Drink Less, a behavior change app to help reduce hazardous and harmful alcohol consumption in the general adult population of the United Kingdom. Methods We explored behavioral engagement among 19,233 existing users of Drink Less. Users were included in the sample if they were from the United Kingdom; were 18 years or older; were interested in reducing their alcohol consumption; had a baseline Alcohol Use Disorders Identification Test score of 8 or above, indicative of excessive drinking; and had downloaded the app between May 17, 2017, and January 22, 2019 (615 days). Measures of when sessions begin, length of sessions, time to disengagement, and patterns of use were visualized with heat maps, timeline plots, k-modes clustering analyses, and Kaplan-Meier plots. Results The daily 11 AM notification is strongly associated with a change in engagement in the following hour; reduction in behavioral engagement over time, with 50.00% (9617/19,233) of users disengaging (defined as no use for 7 or more consecutive days) 22 days after download; identification of 3 distinct trajectories of use, namely engagers (4651/19,233, 24.18% of users), slow disengagers (3679/19,233, 19.13% of users), and fast disengagers (10,903/19,233, 56.68% of users); and limited depth of engagement with 85.076% (7,095,348/8,340,005) of screen views occurring within the Self-monitoring and Feedback module. In addition, a peak of both frequency and amount of time spent per session was observed in the evenings. Conclusions Visualizations play an important role in understanding engagement with behavior change apps. Here, we discuss how simple visualizations helped identify important patterns of engagement with Drink Less. Our visualizations of behavioral engagement suggest that the daily notification substantially impacts engagement. Furthermore, the visualizations suggest that a fixed notification policy can be effective for maintaining engagement for some users but ineffective for others. We conclude that optimizing the notification policy to target both effectiveness and engagement is a worthwhile investment. Our future goal is to both understand the causal effect of the notification on engagement and further optimize the notification policy within Drink Less by tailoring to contextual circumstances of individuals over time. Such tailoring will be informed from the findings of our micro-randomized trial (MRT), and these visualizations were useful in both gaining a better understanding of engagement and designing the MRT.
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Raab, Marc S., Jonathan L. Kaufman, Shambavi Richard, et al. "Hdp-101, an Anti-BCMA Antibody-Drug Conjugate with a Novel Payload Amanitin in Patients with Relapsed Multiple Myeloma, Initial Findings of the First in Human Study." Blood 142, Supplement 1 (2023): 3334. http://dx.doi.org/10.1182/blood-2023-182480.
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Introduction Several antibody-drug conjugates (ADCs) are currently being evaluated in clinical trials in a variety of malignancies. The vast majority of these are based on a few toxic compounds, largely limited to microtubule- or DNA-targeting toxins which impact proliferating cells and have limited efficacy in diseases with a low proliferative fraction such as multiple myeloma. Thus, new compounds with alternative modes of action and the ability to actively induce cell death in non-proliferating tumor cells could enhance the therapeutic potential of ADCs. We are currently developing amanitin based ADCs. Amanitin specifically inhibits RNA polymerase II thereby inhibiting the cellular transcription process at very low concentrations irrespective of the proliferation status of the target cell. Subsequently tumor cells enter apoptosis and are eliminated. HDP-101 an Amanitin based antibody drug conjugate HDP-101 is a new ADC targeting BCMA carrying a synthetic version of amanitin as a payload. In vitro cytotoxic potency of HDP-101 was demonstrated on BCMA-positive myeloma cell lines, as well as on non-proliferating primary CD138+ cells isolated from patients with refractory myeloma The cytotoxic effects of HDP-101 were seen even in non-proliferating myeloma cells with low BCMA density. Toxicity was observed neither in non-BCMA expressing control cells nor in myeloma cells exposed to an amanitin-loaded non-target control antibody. In murine xenograft models of human myeloma, HDP-101 caused dose-dependent tumor regression including complete remissions after a single dose in subcutaneous and as well as in disseminated models. Safety profiling in Cynomolgus monkeys revealed a good therapeutic index after repeated dosing. Our non-clinical studies concluded that this amanitin-based ADC is a novel promising approach in the therapy of multiple myeloma to overcome drug resistance and improve patient outcome. HDP-101-01 Clinical study HDP-101-01 is a first-in-human, open label, non-randomized, multicenter, phase 1/2a trial with HDP-101 in patients with myeloma whose disease has progressed. The aim of the Phase 1 dose escalation part is to determine the Maximum Tolerated Dose and/or establish the Recommended Phase 2 Dose. The primary objective of the phase 2 dose expansion phase is to assess the preliminary anti-tumor activity of HDP-101. An adaptive Bayesian logistic regression model with overdose control principle is used to guide the dose escalation steps. An Interim Analysis is planned after each cohort is completed. The design of the study ensures a safe and adaptive dose escalation to reach a potential clinical benefit in a patient who have limited or no therapeutic options. HDP-101-01 Study progress The study started enrollment in February, 2022. As of 10th of July, 2023, eight (2 female and 6 male) patients were dosed in 3 consecutive dose cohorts. The median age of the patients was 70 years, ranging between 50 and 80. All 8 patients were heavily pre-treated and multidrug-resistant. The median previous lines of treatment were 7 (5 to 15). Table 1 HDP-101-01 Results Seven of 8 patients were evaluable for dose limiting toxicities (DLTs) in the first 3 treatment cohorts. The initial 3 cohorts were well tolerated, without any DLTs, there were no signs of liver and kidney toxicity, no infusion reaction was detected. No reports of keratopathy or visual acuity loss were observed. Free payload was not detected in any of the available pharmacokinetic samples. Based on the limited data, the PK of HDP-101 was in line with our expectation based on the preclinical observations, exposure to HDP-101 is dose proportional. Anti-drug antibody (ADA) was not detected and there's no sign of immunogenicity. Objective responses were not reported in these initial cohorts however in Cohort #3 (60μg/Kg) there was one patient ongoing after 8 cycles of treatment with SD. This patient had a slow decrease in M-protein levels. Image 1 The initial dose cohorts showed good tolerability in late stage relapsed and/or refractory multiple myeloma patients. The study continues to enroll patients to higher dose cohorts at selected sites in the US, Germany, Poland and Hungary. Currently the study is enrolling patients in Cohort #4 at the dose of 80μg/Kg. Additional updates will be provided at the 2023 ASH Annual Meeting.
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Gomez-Urrea, Hernan Alejandro, Jose Gerardo Cardona, Francisco Jose Caro-Lopera, and Miguel Eduardo Mora-Ramos. "Photonic band gaps and waveguide slow-light propagation in Bravais-Moiré two-dimensional photonic crystals." Journal of Optics, November 7, 2022. http://dx.doi.org/10.1088/2040-8986/aca0aa.
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Abstract Photonic band gap widths and slow-light optical guided modes are theoretically investigated for Bravais-Moiré photonic crystals made of cylindrical dielectric cores which are formed from the combination of two square Bravais lattices. Moiré pattern forms due to a commensurable rotation of one of these lattices with respect to the other. The analysis of gap maps is made versus the radii of dielectric cores -both rotated and unrotated- contained in the Bravais-Moiré unit cell. Guided modes are considered within the framework of coupled-resonator optical waveguides, built from the generation of a point defect chain along the direction of electromagnetic wave propagation. For the analyzed structures, rather wide photonic band gaps were found. It was noticed that changing the core radii can significantly affect the dielectric contrast in the unit cell, leading to wider gaps. In addition, due to the kind of crystal cell structure considered, guided modes with group velocities smaller than those typically observed in photonic crystals with simple square lattices were found for the investigated coupled-resonator optical waveguides.
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Madiot, Guilhem, Omar Florez, and Clivia Sotomayor Torres. "Brillouin light scattering spectroscopy of cavity optomechanical crystals." APL Photonics 10, no. 3 (2025). https://doi.org/10.1063/5.0240489.
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We present a detailed study of Brillouin light scattering (BLS) spectroscopy applied to phononic waveguides embedded within optomechanical crystal structures. By comparing numerical simulations with experimental spectra, we validate the capability of BLS to probe GHz mechanical modes, including acoustic slow modes at 6.7 GHz, in silicon-on-insulator platforms at room temperature. Our results highlight the potential of BLS to characterize mechanical dispersion, guided modes, and acoustic bandgaps in cavity optomechanics, where photons and phonons are colocalized. This work provides critical insights into the feasibility of leveraging hypersonic phonons for in-chip interconnects and integrated broadband communication systems.
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Madiot, Guilhem, Marcus Albrechtsen, Søren Stobbe, Clivia M. Sotomayor-Torres, and Guillermo Arregui. "Multimode optomechanics with a two-dimensional optomechanical crystal." APL Photonics 8, no. 11 (2023). http://dx.doi.org/10.1063/5.0170883.
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Chip-scale multimode optomechanical systems have unique benefits for sensing, metrology, and quantum technologies relative to their single-mode counterparts. Slot-mode optomechanical crystals enable sideband resolution and large optomechanical couplings of a single optical cavity to two microwave-frequency mechanical modes. Still, previous implementations have been limited to nanobeam geometries, whose effective quantum cooperativity at ultralow temperatures is limited by their low thermal conductance. In this work, we design and experimentally demonstrate a two-dimensional mechanical–optical–mechanical (MOM) platform that dispersively couples a slow-light slot-guided photonic-crystal waveguide mode and two slow-sound ∼ 7 GHz phononic wire modes localized in physically distinct regions. We first demonstrate optomechanical interactions in long waveguide sections, unveiling acoustic group velocities below 800 m/s, and then move on to mode-gap adiabatic heterostructure cavities with a tailored mechanical frequency difference. Through optomechanical spectroscopy, we demonstrate optical quality factors Q ∼ 105, vacuum optomechanical coupling rates, go/2π, of 1.5 MHz, and dynamical back-action effects beyond the single-mode picture. At a larger power and adequate laser-cavity detuning, we demonstrate regenerative optomechanical oscillations involving a single mechanical mode, extending to both mechanical modes through modulation of the input laser drive at their frequency difference. This work constitutes an important advance toward engineering MOM systems with nearly degenerate mechanical modes as part of hybrid multipartite quantum systems.
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Kiefer, Daniel A., Sylvain Mezil, and Claire Prada. "Beating resonance patterns and extreme power flux skewing in anisotropic elastic plates." Science Advances 9, no. 51 (2023). http://dx.doi.org/10.1126/sciadv.adk6846.
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Elastic waves in anisotropic media can exhibit a power flux that is not collinear with the wave vector. This has notable consequences for waves guided in a plate. Through laser-ultrasonic experiments, we evidence remarkable phenomena due to slow waves in a single-crystal silicon wafer. Waves exhibiting power flux orthogonal to their wave vector are identified. A pulsed line source that excites these waves reveals a wave packet radiated parallel to the line. Furthermore, there exist precisely eight plane waves with zero power flux. These so-called zero–group-velocity modes are oriented along the crystal’s principal axes. Time acts as a filter in the wave-vector domain that selects these modes. Thus, a point source leads to beating resonance patterns with moving nodal curves on the surface of the infinite plate. We observe this pattern as it emerges naturally after a pulsed excitation.
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Fung, Kit-Man, Shu-Jung Lai, Tzu-Lu Lin, and Tien-Sheng Tseng. "Antigen–Antibody Complex-Guided Exploration of the Hotspots Conferring the Immune-Escaping Ability of the SARS-CoV-2 RBD." Frontiers in Molecular Biosciences 9 (March 22, 2022). http://dx.doi.org/10.3389/fmolb.2022.797132.
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The COVID-19 pandemic resulting from the spread of SARS-CoV-2 spurred devastating health and economic crises around the world. Neutralizing antibodies and licensed vaccines were developed to combat COVID-19, but progress was slow. In addition, variants of the receptor-binding domain (RBD) of the spike protein confer resistance of SARS-CoV-2 to neutralizing antibodies, nullifying the possibility of human immunity. Therefore, investigations into the RBD mutations that disrupt neutralization through convalescent antibodies are urgently required. In this study, we comprehensively and systematically investigated the binding stability of RBD variants targeting convalescent antibodies and revealed that the RBD residues F456, F490, L452, L455, and K417 are immune-escaping hotspots, and E484, F486, and N501 are destabilizing residues. Our study also explored the possible modes of actions of emerging SARS-CoV-2 variants. All results are consistent with experimental observations of attenuated antibody neutralization and clinically emerging SARS-CoV-2 variants. We identified possible immune-escaping hotspots that could further promote resistance to convalescent antibodies. The results provide valuable information for developing and designing novel monoclonal antibody drugs to combat emerging SARS-CoV-2 variants.
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Li, Lixia, Wanlu Li, Xueyang Zong, and Yufang Liu. "Self-hybridized exciton-polaritons in perovskite-based subwavelength photonic crystals." New Journal of Physics, August 15, 2022. http://dx.doi.org/10.1088/1367-2630/ac89a5.
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Abstract Self-coupled photonic resonators made of exciton materials have recently provoked great interest in the context of light–matter interactions due to their ability to produce large normal mode splittings. In order to obtain giant Rabi energy, it is rather necessary to ensure large electromagnetic fields within exciton materials. Here, using two independent numerical algorithms, namely, the finite-element method and the rigorous coupled wave analysis, we demonstrate that, even with a moderate oscillation strength, giant Rabi splittings in excess of 250 meV can be achieved in subwavelength perovskite-based photonic crystals. This can be attributed to the fact that quasi-guided resonance modes supported by photonic systems are strongly confined inside the exciton material, highly conducing to increasing the volume of light-matter interaction. We reveal how the oscillator strength of excitons and the thickness of perovskite photonic crystals influence photon–exciton couplings. Moreover, the perovskite nanostructures investigated allow us to engineer polaritonic dispersions with linear or slow-light characters. These findings show that perovskite-based photonic crystals could be an appealing and promising platform in realizing polaritonic devices.
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Bedrosian, Austin D., Andrew Hrymak, Gisela Lanza, and Michael R. Thompson. "Understanding a frequency shifting phenomenon interfering with in-line acoustic monitoring of an extrusion compounding process for polymer composites." Journal of Thermoplastic Composite Materials, March 11, 2025. https://doi.org/10.1177/08927057251321492.
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This study investigated an anomalous frequency shift observed in collected spectra from an inline monitoring system based on guided ultrasonic waves, with the changing flow rate of an extrusion compounding process for fiber-reinforced thermoplastics. Three possible process parameters to explain the ultrasonic peak shifting, namely melt temperature, velocity, and fiber length were evaluated. The unlikely potential of a doppler moment due to melt velocity, was readily dismissed in the analysis since fluid flow through the die was too slow and while resonance frequency variation may be possible from the related fiber damage associated with increasing flow rates, there was insufficient physical evidence of this anticipated effect in this study. Melt temperature variation associated with viscous dissipation was concluded to be the dominant cause for the frequency shifting noted in the acoustic spectra. The changes in material temperature through which the sound travelled were varying the extent and frequency of the dispersion modes in the polymer melt. These findings are new guidance to processors on setting up a system using active ultrasonics for in-line monitoring in the polymer composites industry.
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Jeong, Byeongha, Jin Hee Hong, Hyun Kim, Han Kyoung Choe, Kyungjin Kim, and Kyoung J. Lee. "Multi-stability of circadian phase wave within early postnatal suprachiasmatic nucleus." Scientific Reports 6, no. 1 (2016). http://dx.doi.org/10.1038/srep21463.
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Abstract The suprachiasmatic nucleus (SCN) is a group of cells that functions as a biological master clock. In different SCN cells, oscillations of biochemical markers such as the expression-level of clock genes, are not synchronized but instead form slow circadian phase waves propagating over the whole cell population. Earlier studies presumed that their spatio-temporal structure is a fixed property set by the anatomy of a given SCN. Here, we show that this is not the case in early postnatal SCN. Based on bioluminescence imaging experiments with Per2-Luciferase mice SCN cultures which guided computer simulations of a realistic model of the SCN, we demonstrate that the wave is not unique but can be in various modes including phase- coherent oscillation, crescent-shaped wave, and most notably, a rotating pinwheel wave that conceptually resembles a wall clock with a rotating hand. Furthermore, mode transitions can be induced by a pulse of 38.5 °C temperature perturbation. Importantly, the waves support a significantly different period, suggesting that neither a spatially-fixed phase ordering nor a specialized pacemaker having a fixed period exist in these studied SCNs. These results lead to new important questions of what the observed multi-stability means for the proper function of an SCN and its arrhythmia.