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4,348 result(s) for "Shan, Chang"
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First-Principles Theory of the Rate of Magnetic Reconnection in Magnetospheric and Solar Plasmas
The rate of magnetic reconnection is of the utmost importance in a variety of processes because it controls, for example, the rate energy is released in solar flares, the speed of the Dungey convection cycle in Earth’s magnetosphere, and the energy release rate in harmful geomagnetic substorms. It is known from numerical simulations and satellite observations that the rate is approximately 0.1 in normalized units, but despite years of effort, a full theoretical prediction has not been obtained. Here, we present a first-principles theory for the reconnection rate in non-relativistic electron-ion collisionless plasmas, and show that the same prediction explains why Sweet-Parker reconnection is considerably slower. The key consideration of this analysis is the pressure at the reconnection site (i.e., the x-line). We show that the Hall electromagnetic fields in antiparallel reconnection cause an energy void, equivalently a pressure depletion, at the x-line, so the reconnection exhaust opens out, enabling the fast rate of 0.1. If the energy can reach the x-line to replenish the pressure, the exhaust does not open out. In addition to heliospheric applications, these results are expected to impact reconnection studies in planetary magnetospheres, magnetically confined fusion devices, and astrophysical plasmas.
Birth and death of entanglement between two accelerating Unruh-DeWitt detectors coupled with a scalar field
A bstract We study two accelerating Unruh-DeWitt detectors coupled linearly or quadratically with a scalar field, by using an approach different from previous ones. We use Rindler frame, and integrate over the spacetime coordinates before over the momenta. In this way, the divergent problem previously encountered is avoided. We show that entanglement between the detectors can be created by coupling with the field, and is divergent only in the limit that the two detectors coincide in spacetime. For linear coupling, entanglement increases monotonically with the decrease of acceleration, as previously found, while for quadratic coupling, entanglement behaves non-monotonically, as noted for the first time.
Tannin-Derived Hard Carbon for Stable Lithium-Ion Anode
Graphite anodes are well established for commercial use in lithium-ion battery systems. However, the limited capacity of graphite limits the further development of lithium-ion batteries. Hard carbon obtained from biomass is a highly promising anode material, with the advantage of enriched microcrystalline structure characteristics for better lithium storage. Tannin, a secondary product of metabolism during plant growth, has a rich source on earth. But the mechanism of hard carbon obtained from its derivation in lithium-ion batteries has been little studied. This paper successfully applied the hard carbon obtained from tannin as anode and illustrated the relationship between its structure and lithium storage performance. Meanwhile, to further enhance the performance, graphene oxide is skillfully compounded. The contact with the electrolyte and the charge transfer capability are effectively enhanced, then the capacity of PVP-HC is 255.5 mAh g−1 after 200 cycles at a current density of 400 mA g−1, with a capacity retention rate of 91.25%. The present work lays the foundation and opens up ideas for the application of biomass-derived hard carbon in lithium anodes.
Accelerating Unruh-DeWitt detectors coupled with a spinor field
A bstract The behavior of accelerating Unruh-DeWitt detectors coupled with a spinor field in (3+1)-dimensional spacetime is investigated. For a single point-like detector with Gaussian switching function, the transition probability increases with the acceleration and thus the antiUnruh effect effect cannot occur. Due to the spinor structure of the Dirac field, UV divergences are encountered in the calculation of the entanglement between the detectors. After introducing some UV cutoff Λ, the negativity of detectors is shown to behave nonmonotonically with respect to the acceleration. Besides, the negativity increases with the cutoff Λ and decreases with the distance between the detectors. The mutual information between the two detectors is also discussed.
Electrical tuning of branched flow of light
Branched flows occur ubiquitously in various wave systems, when the propagating waves encounter weak correlated scattering potentials. Here we report the experimental realization of electrical tuning of the branched flow of light using a nematic liquid crystal (NLC) system. We create the physical realization of the weakly correlated disordered potentials of light via the inhomogeneous orientations of the NLC. We demonstrate that the branched flow of light can be switched on and off as well as tuned continuously through the electro-optical properties of NLC film. We further show that the branched flow can be manipulated by the polarization of the incident light due to the optical anisotropy of the NLC film. The nature of the branched flow of light is revealed via the unconventional intensity statistics and the rapid fidelity decay along the light propagation. Our study unveils an excellent platform for the tuning of the branched flow of light which creates a testbed for fundamental physics and offers a new way for steering light. Here the authors experimentally realize the electrical tuning of branched flow of light in nematic liquid crystals. The statistical properties and the polarization effect of the branched flow of light in the film are systematically studied adding fundamental insights on branched flow of light.
Emotional tones of voice affect the acoustics and perception of Mandarin tones
Lexical tones and emotions are conveyed by a similar set of acoustic parameters; therefore, listeners of tonal languages face the challenge of processing lexical tones and emotions in the acoustic signal concurrently. This study examined how emotions affect the acoustics and perception of Mandarin tones. In Experiment 1, Mandarin tones were produced by professional actors with angry, fear, happy, sad, and neutral tones of voice. Acoustic analyses on mean F0, F0 range, mean amplitude, and duration were conducted on syllables excised from a carrier phrase. The results showed that emotions affect Mandarin tone acoustics to different degrees depending on specific Mandarin tones and specific emotions. In Experiment 2, selected syllables from Experiment 1 were presented in isolation or in context. Listeners were asked to identify the Mandarin tones and emotions of the syllables. The results showed that emotions affect Mandarin tone identification to a greater extent than Mandarin tones affect emotion recognition. Both Mandarin tones and emotions were identified more accurately in syllables presented with the carrier phrase, but the carrier phrase affected Mandarin tone identification and emotion recognition to different degrees. These findings suggest that lexical tones and emotions interact in complex but systematic ways.
The mediating role of technology anxiety in the impact of loneliness on technology behavioral intention among community-dwelling older adults
In this modern digital era, older adults encounter considerable challenges in technology adoption, primarily due to varying degrees of technology anxiety and its implications on their behavioral intentions. We conducted a cross-sectional survey with 250 participants aged 60 and older in Taiwan to investigate the mediating role of technology anxiety in the dynamic between loneliness and technology usage intentions. The results reveal that participants exhibited mild levels of loneliness (mean score: 1.53), moderate technology anxiety (mean score: 19.29), and moderate to high intentions toward technology use (mean score: 10.96). The study identifies a significant total effect of loneliness on technology behavioral intention (c = -0.508, p < 0.001). Specifically, loneliness was found to significantly influence technology anxiety (a = 1.158, p < 0.001), which in turn significantly impacted behavioral intention, even after adjusting for loneliness (b = -0.161, p < 0.001). Technology anxiety partially mediated the relationship between loneliness and behavioral intention, exacerbating its negative impact (c’ = -0.322, p < 0.001). These findings highlight the critical need for targeted interventions and policy measures to address and mitigate the barriers to technology adoption faced by older adults.
The giant Zaozigou Au-Sb deposit in West Qinling, China: magmatic- or metamorphic-hydrothermal origin?
Understanding the relationship between mineral occurrences and host granitic rocks can be controversial. The Zaozigou Au-Sb deposit (118 t Au, 0.12 Mt Sb), hosted in metasedimentary rocks and dacitic to granodioritic sills and dikes, is one such example of a large gold deposit argued to have formed from either magmatic or metamorphic hydrothermal processes. Two populations of monazite are identified within a mineralized dacite located along a major shear zone. Magmatic monazite commonly occurs within magmatic biotite and quartz phenocrysts and is characterized by uniform and high Th concentrations. It has a crystallization age of 238.3 ± 2.6 Ma, consistent with the zircon U-Pb age of 238.0 ± 1.8 Ma from the same dacite. Hydrothermal monazite is associated with sulfides and sericite, and has a 207Pb-corrected 206Pb/238U age of 211.1 ± 3.0 Ma. The amount of Th in hydrothermal monazite is widely variable. The low Th content of some monazite grains reflects direct precipitation from a metamorphic hydrothermal fluid. Furthermore, the elevated Th content in other hydrothermal monazite grains is likely due to the release of Th (and U) into hydrothermal fluids by dissolution of pre-existing Th-rich minerals in the country rock during ore-related alteration events. The magmatism, which overlaps Middle-Late Triassic terrane subduction-accretion in the West Qinling orogen, thus pre-dates the ore-forming event by about 30 m.y. The δ34S values of pyrite, arsenopyrite, stibnite, marcasite, and chalcopyrite from disseminated- and vein-type ores range from − 12.0 to − 5.5‰. Such negative values are distinct from those measured for other deposits in the northwestern part of the orogen that are genetically related to Triassic magmatism, including the Xiekeng-Jiangligou-Shuangpengxi Cu-Au-Fe-Mo skarn, Laodou reduced intrusion-related Au, and Gangcha epithermal Au ores. The Zaozigou deposit is best classified as an epizonal orogenic Au-Sb deposit. Our results demonstrate the usefulness of high-precision in situ geochronology on monazite for deciphering age relationships in ore deposits that have spatial associations with granitic rocks, thus aiding in the testing of the veracity of ore formation models.
Harnessing disordered photonics via multi-task learning towards intelligent four-dimensional light field sensors
The complete description of a continuous-wave light field includes its four fundamental properties: wavelength, polarization, phase and amplitude. However, the simultaneous measurement of a multi-dimensional light field of such four degrees of freedom is challenging in conventional optical systems requiring a cascade of dispersive and polarization elements. In this work, we demonstrate a disordered-photonics-assisted intelligent four-dimensional light field sensor. This is achieved by discovering that the speckle patterns, generated from light scattering in a disordered medium, are intrinsically sensitive to a high-dimension light field given their high structural degrees of freedom. Further, the multi-task-learning deep neural network is leveraged to process the single-shot light-field-encoded speckle images free from any prior knowledge of the complex disordered structures and realizes the high-accuracy recognition of full-Stokes vector, multiple orbital angular momentum (OAM), wavelength and power. The proof-of-concept study shows that the states space of four-dimensional light field spanning as high as 1680=4 (multiple-OAM) × 2 (OAM power spectra) × 15 (multiple-wavelength) × 14 (polarizations) can be well recognized with high accuracy in the chip-integrated sensor. Our work provides a novel paradigm for the design of optical sensors for high-dimension light fields, which can be widely applied in optical communication, holography, and imaging.
Effect of malignant‐associated pleural effusion on endothelial viability, motility and angiogenesis in lung cancer
Malignant pleural effusion (MPE) and paramalignant pleural effusion (PPE) remain debilitating complications in lung cancer patients with poor prognosis and limited treatment options. The role of vascular endothelial cells has not been explored in the pleural environment of lung cancer. By integrating MPE and PPE as malignant‐associated pleural fluid (MAPF), the current study aimed to evaluate the effect of MAPF on cell proliferation, migration and angiogenesis of HUVEC. First, increased capillaries were identified in the subpleural layer of lung adenocarcinoma. Compatible with pathological observations, the ubiquitous elevation of HUVEC survival was identified in MAPF culture regardless of the underlying cancer type, the driver gene mutation, prior treatments and evidence of malignant cells in pleural fluid. Moreover, MAPF enhanced HUVEC motility with the formation of lamellipodia and filopodia and focal adhesion complex. Tube formation assay revealed angiogenic behavior with the observation of sheet‐like structures. HUVEC cultured with MAPF resulted in a significant increase in MAPK phosphorylation. Accompanied with VEGFR2 upregulation in MAPF culture, there was increased expressions of p‐STAT3, HIF‐1α and Nf‐kB. VEGF/VEGFR2 blockade regressed endothelial migration and angiogenesis but not cell proliferation. Our data indicate the angiogenic activities of MAPF on vascular endothelial cells that revealed increased pleural capillaries in lung cancer. Targeting the VEGF/VEGFR2 pathway might modulate the angiogenic propensity of MAPF in future clinical investigations. Increased microvessel formation manifested in the subpleural layer of lung carcinoma specimens. In addition, the potency of MAPF to promote endothelial viability and motility was universal regardless of the histological type of cancer, the presence of malignant cells in pleural fluid, and whether or not patients harbored gene mutations. Blockade of VEGFR2 signaling did not compromise MAPF‐induced endothelial viability, and more bioactive factors were, thus, needed to investigate the drug development of MAPF.