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Your search keyword '"Chen, H. T."' showing total 22 results
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22 results on '"Chen, H. T."'

1. Quantum Frequency Combs with Path Identity for Quantum Remote Sensing

Author

Dalvit, D. A. R., Volkoff, T. J., Choi, Y. -S., Azad, A. K., Chen, H. -T., and Milonni, P. W.

Subjects
Quantum Physics, Physics - Applied Physics, Physics - Optics
Abstract

Quantum sensing promises to revolutionize sensing applications by employing quantum states of light or matter as sensing probes. Photons are the clear choice as quantum probes for remote sensing because they can travel to and interact with a distant target. Existing schemes are mainly based on the quantum illumination framework, which requires a quantum memory to store a single photon of an initially entangled pair until its twin reflects off a target and returns for final correlation measurements. Existing demonstrations are limited to tabletop experiments, and expanding the sensing range faces various roadblocks, including long-time quantum storage and photon loss and noise when transmitting quantum signals over long distances. We propose a novel quantum sensing framework that addresses these challenges using quantum frequency combs with path identity for remote sensing of signatures (``qCOMBPASS"). The combination of one key quantum phenomenon and two quantum resources, namely quantum induced coherence by path identity, quantum frequency combs, and two-mode squeezed light, allows for quantum remote sensing without requiring a quantum memory. The proposed scheme is akin to a quantum radar based on entangled frequency comb pairs that uses path identity to detect/range/sense a remote target of interest by measuring pulses of one comb in the pair that never flew to target, but that contains target information ``teleported" by quantum-induced coherence from the other comb in the pair that did fly to target but is not detected., Comment: To appear in PRX

Published
2024

2. Global destabilization of drift-tearing mode with coupling to discretized electron drift-wave instability

Author

Bao, J., Zhang, W. L., Lin, Z., Cai, H. S., Liu, D. J., Chen, H. T., Dong, C., Cao, J. T., and Li, D.

Subjects
Physics - Plasma Physics
Abstract

The global linear behaviors of 2/1 DTM in the collisional regime are investigated based on a concisely resistive drift-MHD model. Besides DTM, extra normal modes including EDW and SAW are coupled together and destabilized in different parameter regimes by considering resistivity in this system. The EVP approach is applied for solving the eigenstate spectra with the distribution of all unstable solutions. It is found that in the small EDD frequency (omega_*e) regime, DTM growth rate agrees well with local theory that is reduced with increasing omega_*e. However, when omega_*e exceeds a critical threshold omega_*crit, the strongly linear coupling between DTM and other discretized EDW instabilities happens so that the free energies from current and pressure channels can be released together and thus enhance the DTM, of which growth rate increases with increasing omega_*e and deviates from local theory results qualitatively. Correspondingly, a cross-scale mode structure forms with mixed polarization, namely, phi perturbation is dominated by electrostatic polarized short-wavelength oscillation as EDW instability character, and A_para perturbation remains typical tearing mode solution of Alfvenic polarized macroscopic structure. Within omega_*e > omega_*crit, the additional IDD causes phi oscillating structure to shift towards small density gradient domain, which cancels the extra drive from ion channel and thus DTM growth rate is insensitive to IDD frequency. Compared to EDD effects, the IDD effect alone with zero-omega_*e only leads to the stabilization of RTM that shows agreements between global simulation and local theory, which is no longer the condition for DTM regime. These results are useful for clarifying the DTM global properties with underlying physics mechanisms, which occurs in the regime of omega_*e >> gamma_c that is relevant to nowadays tokamak discharges with hot plasmas., Comment: 23 pages, 15 figues

Published
2024

7. Melatonin alleviates heme-induced ferroptosis via activating the Nrf2/HO-1 pathway in neurons.

Author

CHEN, H.-T., HAN, R.-L., YU, B.-B., ZHANG, Y.-F., FU, L.-H., LV, B.-Q., TIAN, Y.-Z., YANG, S.-J., HU, Y.-T., HUA, J.-H., ZUO, Q.-Q., and GONG, S.-P.

Abstract

OBJECTIVE: Ferroptosis of neurons is a significant cause of brain injury following intracerebral hemorrhage (ICH). As an iron-containing compound in hemoglobin, heme contributes to nerve injury post-ICH. Melatonin has been shown to mitigate the effects of ICH, yet its specific functions remain largely elusive. In this study, we aimed to explore the roles and mechanisms of melatonin in heme-induced ferroptosis subsequent to ICH. MATERIALS AND METHODS: C57BL/6 mice were intracranially injected with heme and then treated with melatonin. Behavior tests [modified neurological severity score (mNSS), forelimb placing, and corner turn tests], H&E staining, Nissl staining, and Prussian blue staining were used to evaluate mouse brain tissue injury. In vitro, HT-22 cells were stimulated with heme and cell viability was determined by crystal violet staining. The iron contents were determined in heme-treated brains and cells, and the levels of 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA) were assessed by ELISA. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to investigate the mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Immunoblotting was used to analyze the protein expression of glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), Nrf2, and HO-1. Finally, small interfering RNA (siRNA) was used to knock down Nrf2 in HT-22 cells. RESULTS: Melatonin treatment alleviated heme-induced injuries to neural function, as indicated by improved behavior in the mice. Moreover, melatonin decreased cell death and iron concentrations, increased MDA and 4-HNE levels, and reversed the decreases in GPX4, SLC7A11, Nrf2, and HO-1 induced by heme in vitro and in vivo. These results indicated that melatonin could improve the ferroptosis induced by heme. In addition, we found that Nrf2 knockdown attenuated the therapeutic effect of melatonin on neuronal ferroptosis induced by heme. CONCLUSIONS: In general, melatonin alleviates heme-induced ferroptosis by activating the Nrf2/HO-1 pathway, which implies that melatonin is a promising treatment for ferroptosis in ICH. [ABSTRACT FROM AUTHOR]

Published
2024

9. An EEG-based Experiment on VR Sickness and Postural Instability While Walking in Virtual Environments

Author

Cortes, CAT, Lin, C-T, Do, T-TN, Chen, H-T, Cortes, CAT, Lin, C-T, Do, T-TN, and Chen, H-T

Abstract

Previous studies showed that natural walking reduces the susceptibility to VR sickness However many users still experience VR sickness when wearing VR headsets that allow free walking in room scale spaces This paper studies VR sickness and postural instability while the user walks in an immersive virtual environment using an electroencephalogram EEG headset and a full body motion capture system The experiment induced VR sickness by gradually increasing the translation gain beyond the user s detection threshold A between group comparison between participants with and without VR sickness symptoms found some significant differences in postural stability but found none on gait patterns during the walking In the EEG analysis the group with VR sickness showed a reduction of alpha power a phenomenon previously linked to a higher workload and efforts to maintain postural control In contrast the group without VR sickness exhibited brain activities linked to fine cognitive motor control The EEG result provides new insights into the postural instability theory participants with VR sickness could maintain their postural stability at the cost of a higher cognitive workload Our result also indicates that the analysis of lower frequency power could complement behavioral data for continuous VR sickness detection in both stationary and mobile VR setups

Published
2023

10. Predicting the Onset of Freezing of Gait Using EEG Dynamics

Author

John, AR, Cao, Z, Chen, H-T, Martens, KE, Georgiades, M, Gilat, M, Nguyen, HT, Lewis, SJG, and Lin, C-T

Abstract

Freezing of gait (FOG) severely incapacitates the mobility of patients with advanced Parkinson’s disease (PD). An accurate prediction of the onset of FOG could improve the quality of life for PD patients. However, it is imperative to distinguish the possibility of the onset of FOG from that of voluntary stopping. Our previous work demonstrated the neurological differences between the transition to FOG and voluntary stopping using electroencephalogram (EEG) signals. We employed a timed up-and-go (TUG) task to elicit FOG in PD patients. Some of these TUG tasks had an additional voluntary stopping component, where participants stopped walking based on verbal instruction to “stop”. The performance of the convolutional neural network (CNN) in identifying the transition to FOG from normal walking and the transition to voluntary stopping was explored. To the best of our knowledge, this work is the first study to propose a deep learning method to distinguish the transition to FOG from the transition to voluntary stop in PD patients. The models, trained on the EEG data from 17 PD patients who manifested FOG episodes, considering a short two-second transition window for FOG occurrence or voluntary stopping, achieved close to 75% classification accuracy in distinguishing transition to FOG from the transition to voluntary stopping or normal walking. Our results represent an important step toward advanced EEG-based cueing systems for smart FOG intervention, excluding the potential confounding of voluntary stopping.

Published
2022

11. Error-related potential-based shared autonomy via deep recurrent reinforcement learning

Author

Wang, X, Chen, H-T, and Lin, C-T

Subjects
Brain-Computer Interfaces, Biomedical Engineering, Humans, Electroencephalography, Computer Simulation, Neural Networks, Computer, Reinforcement, Psychology, 0903 Biomedical Engineering, 1103 Clinical Sciences, 1109 Neurosciences
Abstract

Objective.Error-related potential (ErrP)-based brain-computer interfaces (BCIs) have received a considerable amount of attention in the human-robot interaction community. In contrast to traditional BCI, which requires continuous and explicit commands from an operator, ErrP-based BCI leverages the ErrP, which is evoked when an operator observes unexpected behaviours from the robot counterpart. This paper proposes a novel shared autonomy model for ErrP-based human-robot interaction.Approach.We incorporate ErrP information provided by a BCI as useful observations for an agent and formulate the shared autonomy problem as a partially observable Markov decision process. A recurrent neural network-based actor-critic model is used to address the uncertainty in the ErrP signal. We evaluate the proposed framework in a simulated human-in-the-loop robot navigation task with both simulated users and real users.Main results.The results show that the proposed ErrP-based shared autonomy model enables an autonomous robot to complete navigation tasks more efficiently. In a simulation with 70% ErrP accuracy, agents completed the task 14.1% faster than in the no ErrP condition, while with real users, agents completed the navigation task 14.9% faster.Significance.The evaluation results confirmed that the shared autonomy via deep recurrent reinforcement learning is an effective way to deal with uncertain human feedback in a complex human-robot interaction task.

Published
2022

13. Ultrafast phenomena and terahertz waves: introduction

Author

Zhu, L.-G., Sheng, Z., (0000-0002-8060-8504) Schneider, H., (0000-0003-2014-7571) Chen, H.-T., Tani, M., Zhu, L.-G., Sheng, Z., (0000-0002-8060-8504) Schneider, H., (0000-0003-2014-7571) Chen, H.-T., and Tani, M.

Abstract

In this introduction, we provide an overview of the papers that were accepted for publication in the feature issue on ultrafast phenomena and terahertz (THz) waves. This feature issue presents cutting-edge research on ultrafast phenomena and highlights recent developments inTHz technology.

Published
2022

14. The Effects of Virtual and Physical Elevation on Physiological Stress during Virtual Reality Height Exposure.

Author

Zhu, HY, Chen, H-T, Lin, C-T, Zhu, HY, Chen, H-T, and Lin, C-T

Abstract

Advances in virtual reality technology have greatly benefited the acrophobia research field. Virtual reality height exposure is a reliable method of inducing stress with low variance across ages and demographics. When creating a virtual height exposure environment, researchers have often used haptic feedback elements to improve the sense of realism of a virtual environment. While the quality of the rendered for the virtual environment increases over time, the physical environment is often simplified to a conservative passive haptic feedback platform. The impact of the increasing disparity between the virtual and physical environment on the induced stress levels is unclear. This paper presents an experiment that explored the effect of combining an elevated physical platform with different levels of virtual heights to induce stress. Eighteen participants experienced four different conditions of varying physical and virtual heights. The measurements included gait parameters, heart rate, heart rate variability, and electrodermal activity. The results show that the added physical elevation at a low virtual height shifts the participant's walking behaviour and increases the perception of danger. However, the virtual environment still plays an essential role in manipulating height exposure and inducing physiological stress. Another finding is that a person's behaviour always corresponds to the more significant perceived threat, whether from the physical or virtual environment.

Published
2022

19. Phase evolution, microstructure, microhardness and corrosion performance of CoCrFeNiNbx high entropy alloy coatings on 316 stainless steel fabricated by laser cladding.

Author

Wu, H., Zhang, S., Wang, Z. Y., Zhang, C. H., Zhang, D. X., Chen, H. T., and Wu, C. L.

Subjects
MICROHARDNESS, ENTROPY, MICROSTRUCTURE, LAVES phases (Metallurgy), ALLOYS, STAINLESS steel, ALLOY powders
Abstract

FeNiCoCrNbx (x: molar ratio, x = 0, 0.1, 0.2, 0.3) high entropy alloy coatings (HEACs) were fabricated on 316 stainless steel (SS) by laser cladding (LC). Experimental results showed that the addition of Nb increased the lattice constant of FeNiCoCrNb high entropy alloy system. HEAC exhibited the transformation from columnar crystal at the interface to equiaxed crystal at the surface on the cross-sectional plane because of the change in the temperature gradient (G) and solidification rate (R). When x = 0.3, lamellar Laves phases appeared in ID. The microhardness of the four HEACs was 1.78, 2.19, 2.30 and 2.37 times that of 316 SS. The HEAC with x = 0.3 as well as 316 SS exhibited typical p-type semiconductor characteristics, which showed excellent corrosion resistance as indicated by the lowest I corr of 2.46 × 10−9 A cm−2 and a larger passivation region with 2 times that of 316 SS. [ABSTRACT FROM AUTHOR]

Published
2022
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20. Traditional Chinese medicine use may reduce medical utility in patients with asthma: correspondence.

Author

Chou, M -C, Jou, I -M, Chen, H -T, and Chang, R

Subjects
CHINESE medicine, ASTHMATICS, PATIENT compliance, WHEEZE
Abstract

The extent of annual outpatient consultations, medication adherence[2] and frequency of emergency room visits for asthma at baseline may have constituted a substantial impact on study outcomes. We read with great interest the epidemiological study by Liao I et al i I . i [1] investigating traditional Chinese medicine use may reduce hospitalization for asthma in a dose-effect manner. [Extracted from the article]

Published
2023
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