المؤلفون: Wieland, Raphael, Kizilaslan, Olcay, Kinev, Nickolay, Dorsch, Eric, Guénon, Stefan, Song, Ziyu, Wei, Zihan, Wang, Huabing, Wu, Peiheng, Koelle, Dieter, Koshelets, Valery P., Kleiner, Reinhold

مصطلحات موضوعية: Condensed Matter - Superconductivity

الوصف: Suitably patterned single crystals made of the cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ (BSCCO), intrinsically forming a stack of Josephson junctions, can generate electromagnetic radiation in the lower terahertz regime. Due to Joule heating the emission power of single stacks seems to be limited to values below 100 $\mu$W. To increase the radiation power, mutually synchronized arrays situated on the same BSCCO base crystal have been studied. Mutual electromagnetic interactions via a connecting BSCCO base crystal have been considered essential for synchronization, but the approach still suffers from Joule heating, preventing the synchronization of more than three stacks. In the present paper we show, on the basis of two emitting stacks, that mutual synchronization can also be achieved by stand-alone stacks contacted by gold layers and sharing only a common gold layer. Compared to BSCCO base crystals, the gold layers have a much higher thermal conductivity and their patterning is not very problematic. We analyze our results in detail, showing that the two oscillators exhibit phase correlations over a range of $\pm$0.4 GHz relative to their center frequencies, which we mainly studied between 745 GHz and 765 GHz. However, we also find that strong phase gradients in the beams radiated from both the mutually locked stacks and the unlocked ones play an important role and, presumably, diminish the detected emission power due to destructive interference. We speculate that the effect arises from higher-order cavity modes which are excited in the individual stacks. Our main message is that the mutual interaction provided by a common gold layer may open new possibilities for relaxing the Joule-heating-problem, allowing the synchronization of a higher number of stacks. Our findings may boost attempts to substantially increase the output power levels of the BSCCO terahertz oscillators.

الوصول الحر: http://arxiv.org/abs/2405.20742Test

المؤلفون: Zhang, Ping, Lyu, Yang-Yang, Lv, Jingjing, Wei, Zihan, Chen, Shixian, Wang, Chenguang, Du, Hongmei, Li, Dingding, Wang, Zixi, Hou, Shoucheng, Su, Runfeng, Sun, Hancong, Du, Yuan, Du, Li, Gao, Liming, Wang, Yong-Lei, Wang, Huabing, Wu, Peiheng

مصطلحات موضوعية: Physics - Applied Physics, Condensed Matter - Superconductivity

الوصف: Advanced microwave technologies constitute the foundation of a wide range of modern sciences, including quantum computing, microwave photonics, spintronics, etc. To facilitate the design of chip-based microwave devices, there is an increasing demand for state-of-the-art microscopic techniques capable of characterizing the near-field microwave distribution and performance. In this work, we integrate Josephson junctions onto a nano-sized quartz tip, forming a highly sensitive microwave mixer on-tip. This allows us to conduct spectroscopic imaging of near-field microwave distributions with high spatial resolution. Leveraging its microwave-sensitive characteristics, our Josephson microscope achieves a broad detecting bandwidth of up to 200 GHz with remarkable frequency and intensity sensitivities. Our work emphasizes the benefits of utilizing the Josephson microscope as a real-time, non-destructive technique to advance integrated microwave electronics.

الوصول الحر: http://arxiv.org/abs/2401.12545Test

المؤلفون: Zhao Qian, Liu Lu, Wei Zihan, Bai Qianyue, Zhao Chungang, Zhang Shuheng, Pan Jiali, Yu Jiaxin, Zhang Shuang, Wei Jian

المصدر: BMC Plant Biology, Vol 24, Iss 1, Pp 1-18 (2024)

مصطلحات موضوعية: Climate change, Abiotic stress, Salinity, Physiology, Antioxidant mechanism, Ion homeostasis, Botany, QK1-989

الوصف: Abstract Background In plants, GABA plays a critical role in regulating salinity stress tolerance. However, the response of soybean seedlings (Glycine max L.) to exogenous gamma-aminobutyric acid (GABA) under saline stress conditions has not been fully elucidated. Results This study investigated the effects of exogenous GABA (2 mM) on plant biomass and the physiological mechanism through which soybean plants are affected by saline stress conditions (0, 40, and 80 mM of NaCl and Na2SO4 at a 1:1 molar ratio). We noticed that increased salinity stress negatively impacted the growth and metabolism of soybean seedlings, compared to control. The root-stem-leaf biomass (27- and 33%, 20- and 58%, and 25- and 59% under 40- and 80 mM stress, respectively]) and the concentration of chlorophyll a and chlorophyll b significantly decreased. Moreover, the carotenoid content increased significantly (by 35%) following treatment with 40 mM stress. The results exhibited significant increase in the concentration of hydrogen peroxide (H2O2), malondialdehyde (MDA), dehydroascorbic acid (DHA) oxidized glutathione (GSSG), Na+, and Cl− under 40- and 80 mM stress levels, respectively. However, the concentration of mineral nutrients, soluble proteins, and soluble sugars reduced significantly under both salinity stress levels. In contrast, the proline and glycine betaine concentrations increased compared with those in the control group. Moreover, the enzymatic activities of ascorbate peroxidase, monodehydroascorbate reductase, glutathione reductase, and glutathione peroxidase decreased significantly, while those of superoxide dismutase, catalase, peroxidase, and dehydroascorbate reductase increased following saline stress, indicating the overall sensitivity of the ascorbate-glutathione cycle (AsA-GSH). However, exogenous GABA decreased Na+, Cl−, H2O2, and MDA concentration but enhanced photosynthetic pigments, mineral nutrients (K+, K+/Na+ ratio, Zn2+, Fe2+, Mg2+, and Ca2+); osmolytes (proline, glycine betaine, soluble sugar, and soluble protein); enzymatic antioxidant activities; and AsA-GSH pools, thus reducing salinity-associated stress damage and resulting in improved growth and biomass. The positive impact of exogenously applied GABA on soybean plants could be attributed to its ability to improve their physiological stress response mechanisms and reduce harmful substances. Conclusion Applying GABA to soybean plants could be an effective strategy for mitigating salinity stress. In the future, molecular studies may contribute to a better understanding of the mechanisms by which GABA regulates salt tolerance in soybeans.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1471-2229Test

الوصول الحر: https://doaj.org/article/a57753480019450b819080927deb20edTest

المؤلفون: Cao, Lei, Zhang, Huijun, Feng, Ling, Wei, Zihan, Wang, Xin, Li, Ningyun, He, Xiaohao

مصطلحات موضوعية: Computer Science - Computation and Language

الوصف: Despite detection of suicidal ideation on social media has made great progress in recent years, people's implicitly and anti-real contrarily expressed posts still remain as an obstacle, constraining the detectors to acquire higher satisfactory performance. Enlightened by the hidden "tree holes" phenomenon on microblog, where people at suicide risk tend to disclose their inner real feelings and thoughts to the microblog space whose authors have committed suicide, we explore the use of tree holes to enhance microblog-based suicide risk detection from the following two perspectives. (1) We build suicide-oriented word embeddings based on tree hole contents to strength the sensibility of suicide-related lexicons and context based on tree hole contents. (2) A two-layered attention mechanism is deployed to grasp intermittently changing points from individual's open blog streams, revealing one's inner emotional world more or less. Our experimental results show that with suicide-oriented word embeddings and attention, microblog-based suicide risk detection can achieve over 91\% accuracy. A large-scale well-labelled suicide data set is also reported in the paper.
Comment: Accepted to EMNLP 2019

الوصول الحر: http://arxiv.org/abs/1910.12038Test

المؤلفون: Mitchell, Samuel J, Houghton, Bruce F, Carey, Rebecca J, Manga, Michael, Fauria, Kristen E, Jones, Max P, Soule, S Adam, Conway, Chris E, Wei, Zihan, Giachetti, Thomas

المصدر: Bulletin of Volcanology. 81(7)

مصطلحات موضوعية: Earth Sciences, Geochemistry, Geology, Geophysics, Giant pumice, Submarine volcanism, Banding, Tube pumice, Bubble deformation, Conduit dynamics, Geochemistry & Geophysics

الوصف: Meter-scale vesicular blocks, termed “giant pumice,” are characteristic primary products of many subaqueous silicic eruptions. The size of giant pumices allows us to describe meter-scale variations in textures and geochemistry with implications for shearing processes, ascent dynamics, and thermal histories within submarine conduits prior to eruption. The submarine eruption of Havre volcano, Kermadec Arc, in 2012, produced at least 0.1 km3 of rhyolitic giant pumice from a single 900-m-deep vent, with blocks up to 10 m in size transported to at least 6 km from source. We sampled and analyzed 29 giant pumices from the 2012 Havre eruption. Geochemical analyses of whole rock and matrix glass show no evidence for geochemical heterogeneities in parental magma; any textural variations can be attributed to crystallization of phenocrysts and microlites, and degassing. Extensive growth of microlites occurred near conduit walls where magma was then mingled with ascending microlite-poor, low viscosity rhyolite. Meter- to micron-scale textural analyses of giant pumices identify diversity throughout an individual block and between the exteriors of individual blocks. We identify evidence for post-disruption vesicle growth during pumice ascent in the water column above the submarine vent. A 2D cumulative strain model with a flared, shallow conduit may explain observed vesicularity contrasts (elongate tube vesicles vs spherical vesicles). Low vesicle number densities in these pumices from this high-intensity silicic eruption demonstrate the effect of hydrostatic pressure above a deep submarine vent in suppressing rapid late-stage bubble nucleation and inhibiting explosive fragmentation in the shallow conduit.

الوصول الحر: https://escholarship.org/uc/item/12m0c8rbTest

المؤلفون: Liu, Ruomao, Xiang, Yuxuan, Wei, Zihan, Zhang, Jiachen

المساهمون: City University of Hong Kong

المصدر: Advanced Intelligent Systems ; volume 6, issue 2 ; ISSN 2640-4567 2640-4567

الوصف: Untethered magnetic millirobots with a characteristic length of a few millimeters can be wirelessly controlled. They exhibit promising potential in a wide variety of applications, particularly for tasks in clinic workspaces. However, magnetically controlling these robots is counter‐intuitive and requires a steep learning curve, hindering their wide adoption. Herein, a computer‐aided teleoperation platform is developed to operate a soft millirobot, with its feedback control being conducted behind‐the‐scenes, bridging the user's inputs directly with the millirobot's actions to offer an intuitive control. This system enables untrained users to conveniently control the position and actions of the millirobot inside a human stomach phantom by pointing‐and‐clicking on a real‐time video monitor or using a keyboard. The platform automatically materializes the user's instructions by maneuvering a robotic arm with a tip‐mounted magnet to exert a magnetic field to induce the desired response from the millirobot. Experiments show that the system allows the user to intuitively operate the millirobot and deliver its cargo without splitting their attention to monitor the workspace or to calculate the constantly changing control parameters. This platform can lower the barrier for healthcare practitioners without engineering expertise to adopt miniature robotic systems into their workflow and realize these systems’ promising potential.

الإتاحة: https://doi.org/10.1002/aisy.202300325Test

المؤلفون: Wei, Zihan, Yang, Sizhen, Zhang, Ying, Ye, Jiawen, Chu, Tong-wei

المساهمون: General project of Chongqing Natural Science Foundation of China, National Key Research and Development Plan Project, Clinical Research Project of the Second Affiliated Hospital of the Army Military Medical University

المصدر: Global Spine Journal ; ISSN 2192-5682 2192-5690

مصطلحات موضوعية: Neurology (clinical), Orthopedics and Sports Medicine, Surgery

الوصف: Study Design A retrospective study was performed. Objective To investigate the prevalence and risk factors for adjacent segment disease (ASD) after anterior cervical discectomy and fusion (ACDF) and the clinical efficacy of revision surgery. Method A total of 219 patients treated with ACDF were analyzed retrospectively. Demographic characteristics, including age, sex, body mass index (BMI) and bone mineral density (BMD), and radiographic measurements, including C2-C7 cervical sagittal vertical axis (cSVA), T1 slope (T1S), thoracic inlet angle (TIA) and C2-C7 Cobb angle, were analyzed. Modified Japanese Orthopaedic Association (mJOA) score and visual analog scale (VAS) score were used to evaluate patient function. Parameters were analyzed with Student's t test, and potential risk factors for ASD were further analyzed with multivariate logistic regression analysis. Results The incidence of ASD after ACDF surgeries was 21%. The severity of osteoporosis, BMI and C2-C7 cSVA were significantly higher in the ASD group than in the NASD group ( P < .05). The preoperative and postoperative TIAs were lower in the ASD group ( P < .05). Multivariate logistic regression analysis showed that a high BMI, severe osteoporosis and a high C2-C7 cSVA were risk factors for ASD after ACDF ( P < .05). The postoperative TIA and postoperative T1S were also correlated with ASD ( P < .05). Conclusion Patients with a high BMI, severe osteoporosis, and a large C2-C7 cSVA after ACDF have a higher risk of ASD, while a large T1S and TIA may be protective factors. In addition, revision surgery can restore cervical spine balance in patients with ASD and promote better clinical outcomes.

الإتاحة: https://doi.org/10.1177/21925682231185332Test

المؤلفون: Pan, Yuanhang, Hu, Gengyao, Wang, Zezhi, Yuan, Na, Wei, Zihan, Li, Xia, Hou, Xiaohua, Wang, Jian, Zhang, Xinbo, Chen, Ze, Qu, Shuyi, Bao, Junxiang, Liu, Yonghong

المصدر: Frontiers in Neurology ; volume 14 ; ISSN 1664-2295

مصطلحات موضوعية: Neurology (clinical), Neurology

الوصف: Background and objective Sudden unexpected death in epilepsy (SUDEP) has been regarded as a leading cause of premature death in patients with epilepsy (PWE). Although patients, relatives and caregivers have the right to be informed of SUDEP, neurologists prefer not to release the facts for fear of associated anxiety. In the study, a Chinese questionnaire survey was carried out to elucidate effect of SUDEP disclosure on anxiety in PWE and variables determining the anxiety of patients and provided suggestions for SUDEP disclosure. Methods A survey study in China was conducted. We recruited 305 PWE from 3 tertiary epilepsy centers who attended outpatient clinic from December 2021 to February 2022. Two hundred and thirty-two PWE completed the screening evaluation, survey and Hamilton anxiety rating scale (HAMA) twice with 171 PWE completing third HAMA at follow-up. HAMA scores at baseline, T1, T2 were compared using analysis of variance and dependent samples t -test. The variables related to anxiety were screened out by univariate analysis and used for multivariate logistic regression. Result We found 127 (54.7%) among the 232 participants experienced anxiety after SUDEP disclosure. HAMA scores at T1 were significantly higher than at baseline and T2, while there was no statistical difference between baseline and T2. Medical insurance, seizure severity, and whether the PWE supported SUDEP being disclosed to their relatives and caregivers only were associated with the occurrence of anxiety. Conclusion SUDEP disclosures may cause short-term acute anxiety, but have no long-term effects in PWE. Acute anxiety caused by SUDEP disclosure may be more common in PWE with NCMI and severe seizures. Meanwhile, compared with indirect SUDEP disclosure to their relatives and caregivers, direct SUDEP disclosure to PWE reduces the risk of anxiety. Recommendations are provided to avoid anxiety caused by SUDEP disclosure.

الإتاحة: https://doi.org/10.3389/fneur.2023.1284050Test

المؤلفون: Zhang, Ping, Lv, Jingjing, Hou, Shoucheng, Liu, Tao, Cheng, Xinsheng, Wei, Zihan, Lyu, Yang-Yang, Wang, Yong-Lei, Du, Yuan, Du, Li, Wang, Huabing, Wu, Peiheng

المصدر: Nano Letters; 5/8/2024, Vol. 24 Issue 18, p5453-5459, 7p

المؤلفون: Fauria, Kristen E, Manga, Michael, Wei, Zihan

مصطلحات موضوعية: Earth Sciences, buoyancy, capillary processes, percolation theory, submarine volcanism, X-ray microtomography, Physical Sciences, Geochemistry & Geophysics, Earth sciences, Physical sciences

الوصف: Pumice can float on water for months to years – long enough for pumice to travel across oceans and facilitate the spread of species. Long-lived pumice floatation is unexpected, however, because pumice pores are highly connected and water wets volcanic glass. As a result, observations of long floating times have not been reconciled with predictions of rapid sinking. We propose a mechanism to resolve this paradox – the trapping of gas bubbles by water within the pumice. Gas trapping refers to the isolation of gas by water within pore throats such that the gas becomes disconnected from the atmosphere and unable to escape. We use X-ray microtomography to image partially saturated pumice and demonstrate that non-condensable gas trapping occurs in both ambient temperature and hot (500 °C) pumice. Furthermore, we show that the size distribution of trapped gas clusters matches predictions of percolation theory. Finally, we propose that diffusion of trapped gas determines pumice floatation time. Experimental measurements of pumice floatation support a diffusion control on pumice buoyancy and we find that floatation time τ scales as τ∝L2Dθ2 where L is the characteristic length of pumice, D is the gas–water diffusion coefficient, and θ is pumice water saturation. A mechanistic understanding of pumice floatation is a step towards understanding how pumice is partitioned into floating and sinking components and provides an estimate for the lifetime of pumice rafts in the ocean.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/5032h14qTest
https://escholarship.org/content/qt5032h14q/qt5032h14q.pdfTest