99 results on '"K. Xiong"'
Search Results
2. [Status of HVPG clinical application in China in 2021]
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W, Zhang, F Q, Liu, L P, Zhang, H G, Ding, Y Z, Zhuge, J T, Wang, L, Li, G C, Wang, H, Wu, H, Li, G H, Cao, X F, Lu, D R, Kong, L, Sun, W, Wu, J H, Sun, J T, Liu, H, Zhu, D L, Li, W H, Guo, H, Xue, Y, Wang, C J C, Gengzang, T, Zhao, M, Yuan, S R, Liu, H, Huan, M, Niu, X, Li, J, Ma, Q L, Zhu, W W, Guo, K P, Zhang, X L, Zhu, B R, Huang, J N, Li, W D, Wang, H F, Yi, Q, Zhang, L, Gao, G, Zhang, Z W, Zhao, K, Xiong, Z X, Wang, H, Shan, M S, Li, X Q, Zhang, H B, Shi, X G, Hu, K S, Zhu, Z G, Zhang, H, Jiang, J B, Zhao, M S, Huang, W Y, Shen, L, Zhang, F, Xie, Z W, Li, C L, Hou, S J, Hu, J W, Lu, X D, Cui, T, Lu, S S, Yang, W, Liu, J P, Shi, Y M, Lei, J L, Bao, T, Wang, W X, Ren, L, Yu, Q, Yu, H L, Xiang, W W, Luo, and X L, Qi
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Liver Cirrhosis ,China ,Hypertension, Portal ,Humans ,Hepatic Veins ,Portal Pressure - Published
- 2022
3. Assessment of options for small-scale groundwater irrigation in Lao PDR
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P. Pavelic, D. Suhardiman, O. Keovilignavong, C. Clément, J. Vinckevleugel, S.M. Bohsung, K. Xiong, L. Valee, M. Viossanges, S. Douangsavanh, T. Sotoukee, K.G. Villholth, B.R. Shivakoti, and K. Vongsathiane
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- 2022
4. Recent advances of perovskite materials for surface enhanced Raman scattering and their applications
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Z. Yin, Y. Li, J. Xu, Z.F. Qian, and K. Xiong
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Physics and Astronomy (miscellaneous) ,General Materials Science ,Energy (miscellaneous) - Published
- 2022
5. Structural Stability, Elasticity, Thermodynamics and Electronic Structures of L12-Type Ni3X (X=Al, Ti, V, Nb) Phases Under External Pressure Condition
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Y H Wu, J Y Ji, Q Z Wang, Y Z Zhang, J S Chen, and K Xiong
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Inorganic Chemistry ,Materials science ,Computational Theory and Mathematics ,Structural stability ,Organic Chemistry ,Thermodynamics ,Physical and Theoretical Chemistry ,Type (model theory) ,Elasticity (economics) ,Catalysis ,Computer Science Applications ,External pressure - Abstract
In this paper, the impacts of external pressure on structural stability, elasticity, thermodynamics and relevant electronic structures of L12-type Ni3X (X=Al, Ti, V, Nb) phases were investigated using the first-principles methods. The lattice parameters(a,b,c) and volume(V) of the Ni3X phases decrease with increasing pressure. however, the elastic constants(Cij ), bulk modulus(B), shear modulus(G), and Young's modulus (E) increase. The calculated elastic constants indicate that the mechanical stability and ductility of Ni3X phases enhance with increasing pressure. The mechanical anisotropy of Ni3X phases are enhanced by the raised pressure. Electronic analysis shows that increase pressure makes Ni-d-orbital and X(X=Al, Ti, V, Nb) -d-orbital hybridization stronger and electron transfer increases. The sequence in regard to electron aggregation strength is Ni3Ti>Ni3Nb>Ni3V>Ni3Al. It is more directly reflected in the charge density difference maps. This is consistent with the analysis results of the enthalpy of formation(ΔH) and Debye temperature (ΘD).
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- 2021
6. Structural stability, elasticity, thermodynamics, and electronic structures of L1
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Y H, Wu, J S, Chen, J Y, Ji, Y Z, Zhang, Q Z, Wang, and K, Xiong
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In this paper, the effect of pressure on the structural stability, elasticity, thermodynamics, and associated electronic structure of L1
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- 2021
7. Hydrophobic metal organic framework for enhancing performance of acoustic wave formaldehyde sensor based on polyethyleneimine and bacterial cellulose nanofilms
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Xiaotao Zu, Hamdi Torun, Y. Y. Jiang, Yong Qing Fu, W. K. Xiong, Y. J. Guo, J. H. Shang, Jinshan Li, Jiejun Wang, and X. Yang
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Materials science ,H600 ,Surface acoustic wave ,Formaldehyde ,F200 ,Humidity ,G900 ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Bacterial cellulose ,Surface roughness ,Relative humidity ,Electrical and Electronic Engineering ,Layer (electronics) ,Zeolitic imidazolate framework - Abstract
A surface acoustic wave (SAW) formaldehyde gas sensor was fabricated on a 42° 75′ ST-cut quartz substrate, with a composite sensing layer of zeolitic imidazolate framework (ZIF)-8 on polyethyleneimine (PEI)/bacterial cellulose (BC) nanofilms. The addition of snowflake-like ZIF-8 structure on the PEI/BC sensitive film significantly improves the hydrophobicity of the SAW sensor and increases its sensitivity to formaldehyde gas. It also significantly increases surface roughness of the sensitive film. The hydrophobic nature of ZIF-8 prevents water molecules from entering into the internal pores of the BC film, thereby avoiding a significant mass loading caused by humidity when the sensor is used to detect low-concentration formaldehyde gas. The Zn2+ sites at the surface of ZIF-8 improves the sensor's response to formaldehyde gas through enhanced physical adsorptions of gas molecules. Experimental results show that the ZIF-8@PEI/BC SAW sensor has a response (e.g., frequency shift) of 40.3 kHz to 10 ppm formaldehyde gas at 25 °C and 30% relative humidity (RH). When the relative humidity is increased from 30 to 93%, the response of the sensor only varies ~ 5%, and the change in response is negligible at medium humidity levels (~ 50 to 60% RH).
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- 2021
8. FPGA-Based modular multilevel converter (MMC) controller for efficient voltage balancing in real-time simulation
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Guanghui He, Jian Zhang, Guoxing Wang, and K. Xiong
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Control theory ,business.industry ,Real-time simulation ,Gate array ,Computer science ,sort ,Bucket sort ,Modular design ,business ,Field-programmable gate array ,Bottleneck ,Computer hardware - Abstract
At present, the implementation of the capacitor voltage balancing controller is a great challenge for the real-time simulation of the MMC systems. In this paper, a field-programmable gate array (FPGA)-based MMC controller is presented. In order to break through the bottleneck of sort scheme in real-time simulation, an efficient sorting scheme is proposed. This scheme is integrated by bucket sort and oddeven sort. It can greatly reduce the comparison times and highly leverage the inherent parallelism in FPGA. A special storage scheme is proposed and can greatly reduce resource consumption of sub-module (SM) voltages and make the utilization of FPGA more efficient. This proposed MMC controller is implemented by high-level synthesis (HLS) and a set of optimization methods are proposed to reduce the timestep. The proposed controller offers a controller timestep of 50us on Xilinx VC709 and support for 640 SMs each bridge-arm and 6 bridge-arms in one MMC on a single board. The performance and accuracy are evaluated on a case study of a back-to-back MMC-HVDC system on ADPSS.
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- 2021
9. A coherent detection algorithm for the high-speed targets based on radon inverse fourier transform
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L. Yan, Guanghui Zhao, K. Xiong, and Z. Gao
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symbols.namesake ,Rift ,Fourier transform ,Computational complexity theory ,Computer science ,Frequency domain ,Echo (computing) ,Range (statistics) ,symbols ,Focus (optics) ,Algorithm ,Interpolation - Abstract
Within the long-time coherent integration (CI) in radar detection, high-speed targets generally suffer from the range walk (RW) effect, which leads to the typical coherent detection failure. To acquire robust coherent detection, this paper proposes Radon inverse Fourier transform (RIFT). In this paper, we focus on the fact in fast frequency-slow frequency domain that the echo of the target is characterized as a unique straight line whose location simply corresponds to the velocity. Benefiting from this fact, the velocity can be estimated through velocity searching via RIFT, in which the inverse Fourier transform (IFT) is exploited along the velocity-related straight line. Then, we can conduct the CI employing RIFT with the estimated velocity. In comparison with keystone transform (KT) and Radon-Fourier transform (RFT), the advantages of RIFT are as follows: low computational complexity, no interpolation loss as well as the blind speed sidelobe (BSSL) simultaneously. Numerical results demonstrate the effectiveness and the efficiency of the proposed RIFT. Specifically, the proposed algorithm yields 2dB better antinoise performance than scaled inverse Fourier transform (SCIFT) and frequency-domain deramp-keystone transform (FDDKT) in the high-speed target detections.
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- 2021
10. Expression of lncRNA AK058003 in esophageal carcinoma and analysis of its intervention effect
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P, Zhang, K, Xiong, P, Lv, and Y-T, Cui
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Esophageal Neoplasms ,Cell Line, Tumor ,Humans ,RNA, Long Noncoding ,Esophageal Squamous Cell Carcinoma ,Cell Proliferation - Abstract
The aim of this study was to investigate the expression of long non-coding ribonucleic acid (lncRNA) AK058003 in esophageal carcinoma (EC) tissues, and to analyze its intervention effect.The expression of lncRNA AK058003 in EC tissues and para-carcinoma tissues from 130 EC patients was detected via quantitative Polymerase Chain Reaction (qPCR). EC cell lines were selected for exogenous interference in lncRNA AK058003. Subsequently, the expression of lncRNA AK058003 in normal esophageal epithelial cell line (Het-1A) and EC cell lines (EC109, EC9706, KYSE-150, KYSE-30, and TE-1) was detected by qPCR. EC9706 cell lines with the highest expression of lncRNA AK058003 were selected and transfected with lncRNA AK058003 siRNA and lncRNA AK058003 control, respectively. After transfection, the expression of lncRNA AK058003 was determined using PCR. The changes in cell growth and proliferation were analyzed via cell growth curve and cell cycle assay. Meanwhile, the changes in cell migration and invasion were analyzed through wound healing assay. Protein expressions of matrix metalloproteinase-1 (MMP1) and MMP2 were determined by Western blot. Clinical data were collected from EC patients, and the association between lncRNA AK058003 expression and tumor-node-metastasis (TNM) stage was finally analyzed.LncRNA AK058003 was highly expressed EC tissues compared with para-carcinoma tissues (p0.01). Compared with Het-1A cells, the expression of lncRNA AK058003 was significantly higher in EC109, EC9706, KYSE-150, KYSE-30, and TE-1 cells, with highest level in EC9706 cells (p0.05). The expression of lncRNA AK058003 remarkably declined in lncRNA AK058003 siRNA group compared with lncRNA AK058003 control group (p0.001). Compared with lncRNA AK058003 control group, the proliferation of EC cells was significantly weakened in lncRNA AK058003 siRNA group, with the greatest difference at 3 d. Flow cytometry results revealed that cell cycle was arrested in G0/G1 phase in lncRNA AK058003 siRNA group. Wound healing assay indicated that the intercellular distance became large, and cell migration ability was evidently enhanced in lncRNA AK058003 siRNA group with time (p0.05). Besides, the protein expressions of MMP1 and MMP2 were remarkably lower in lncRNA AK058003 siRNA group than those in lncRNA AK058003 control group. This indicated remarkably declined invasion and metastasis ability. In addition, the postoperative prognosis was significantly worse in patients with higher expression of lncRNA AK058003 (p0.05). All these findings suggested that lncRNA AK058003 could serve as a biomarker for EC prognosis.LncRNA AK058003 is highly expressed in EC patients, which promotes proliferation, migration, invasion, and metastasis of EC cells. In addition, the postoperative prognosis of EC patients with high expression of lncRNA AK058003 is relatively poor.
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- 2020
11. Effect of interfacial conductivity on electrical characteristics of negative capacitance field effect transistors
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K. Xiong, G. Li, K. C. Kang, M. H. Tang, Z. Li, Y. G. Xiao, and L. Y. Tian
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Biomaterials ,Materials science ,Polymers and Plastics ,business.industry ,Subthreshold swing ,Metals and Alloys ,Optoelectronics ,Field-effect transistor ,Conductivity ,business ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Negative impedance converter - Abstract
In this article, an interfacial conductivity model for the surface potential and the drain current was proposed based on the metal-interface-ferroelectric-insulator-semiconductor (MIFIS) structure negative capacitance field effect transistor (NC-FET). The simulating results illustrate that the electrical conductivity (σ) of the interface layer between the electrode and ferroelectric thin film caused by lattice misfit plays an important role in the process of voltage amplifying and steep switching for the NC-FET. It is indicated that new device design rules should take into account this scenario.
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- 2021
12. Attention training to pleasant stimuli in anxiety
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F. Mirghassemi, Travis C. Evans, K. Xiong, Sarah M. Sass, and Huy Tran
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Adult ,Male ,050103 clinical psychology ,medicine.medical_specialty ,Adolescent ,genetic structures ,media_common.quotation_subject ,Emotions ,Electroencephalography ,Attentional bias ,Audiology ,Placebo ,Arousal ,Attentional Bias ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Reaction Time ,medicine ,Humans ,0501 psychology and cognitive sciences ,Young adult ,Evoked Potentials ,media_common ,Cerebral Cortex ,medicine.diagnostic_test ,General Neuroscience ,Panic disorder ,05 social sciences ,medicine.disease ,Anxiety Disorders ,Paired-Associate Learning ,Semantics ,Neuropsychology and Physiological Psychology ,Practice, Psychological ,Panic Disorder ,Anxiety ,Female ,Worry ,medicine.symptom ,Psychology ,030217 neurology & neurosurgery ,Cognitive psychology - Abstract
Attentional bias for threatening stimuli in anxiety is a common finding in the literature. The present study addressed whether attention training toward pleasant stimuli can reduce anxiety symptoms and induce a processing bias in favor of pleasant information in nonpatients who were selected to score similarly to individuals with generalized anxiety or panic disorder on a measure of worry or physiological arousal, respectively. Participants were randomly assigned to attention training to pleasant (ATP) stimuli or to a placebo control (PC) condition. All participants completed baseline and post-test dot-probe measures of attentional bias while event-related brain potentials were recorded. As expected, worry symptoms decreased in the ATP and not PC condition. ATP was also associated with early evidence (P100 amplitude) of greater attentional prioritization of probes replacing neutral stimuli within threat-neutral word pairs from pre-to-post intervention and later RT evidence of facilitated processing of probes replacing pleasant stimuli within pleasant-threat word pairs at post compared to PC. PC was associated with later evidence (P300 latency) of less efficient evaluation of probes following pleasant stimuli within pleasant-threat word pairs from pre-to-post and later RT evidence of facilitated processing of probes following threat stimuli within pleasant-threat word pairs at post compared to ATP. Results highlight early and later mechanisms of attention processing changes and underscore the potential of pleasant stimuli in optimizing attention-training interventions for anxiety.
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- 2017
13. Effect of exosomes derived from MiR-133b-modified ADSCs on the recovery of neurological function after SCI
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Z-W, Ren, J-G, Zhou, Z-K, Xiong, F-Z, Zhu, and X-D, Guo
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Male ,Mesenchymal Stem Cells ,Myelin Basic Protein ,Recovery of Function ,Exosomes ,Axons ,Nerve Regeneration ,Rats ,Up-Regulation ,Rats, Sprague-Dawley ,Disease Models, Animal ,MicroRNAs ,GAP-43 Protein ,Adipose Tissue ,Glial Fibrillary Acidic Protein ,Animals ,Humans ,Spinal Cord Injuries ,Signal Transduction - Abstract
To investigate the recovery effect of exosomes derived from micro ribonucleic acid (miR)-133b-modified adipose-derived stem cells (ADSCs) on neurological function after spinal cord injury (SCI) and its mechanism.The SCI model of rats was used and divided into the following 5 groups: sham-operation group, 4 d SCI group, phosphate-buffered saline (PBS) group, miR-control group and miR-133b group. At 96 h after operation, rats were euthanatized, and spinal tissues were removed. Next, the level of miR-133b was detected via reverse transcription-polymerase chain reaction (RT-PCR), and the expression of RhoA protein was measured via Western blotting. Moreover, expressions of proteins associated with the axon regeneration pathway, including phosphorylated-cAMP-response element binding protein (p-CREB), CREB, phosphorylated-signal transducer and activator of transcription 3 (p-STAT3) and STAT3, along with expressions of neurofilament (NF), growth associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP), were tested by Western blotting and immunofluorescence staining.The miR-133b mimics significantly upregulated the expression of miR-133b in adipose-derived stem cells (ADSCs), compared to blank group (p0.05). The expression of miR-133b was significantly decreased in 4 d SCI group compared with that in sham-operation group (p0.001). The RhoA expression was statistically increased in 4 d SCI group compared with that in sham-operation group (p0.001), and it was partially impaired by using miR-133b compared with that in 4 d SCI group (p0.001). Expressions of NF, GAP43, GFAP and MBP were remarkably higher in 4 d SCI group than those in sham-operation group (p0.01), and they were also significantly increased in miR-133b group than those in 4 d SCI group (p0.01). Besides, our data showed a significant increase of p-CREB/CREB, p-STAT3/STAT3, NF, GAP-43, GFAP and MBP in miR-133b group compared to those in 4 d SCI group, with statistical reduction of RhoA (p0.05).We showed that exosomes derived from miR-133b-modified ADSCs can significantly promote the recovery of neurological function of SCI animals through affecting the signaling pathway related to axon regeneration and expressions of NF, GAP-43, GFAP and MBP.
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- 2019
14. PND93 First LINE Treatment with Natalizumab Reduces Healthcare Resource Use and Work Productivity and Activity Impairment in Relapsing-Remitting Multiple Sclerosis (RRMS) Patients Compared to Natalizumab Delayed Use
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K. Xiong, S. Liao, E Jones, R. Su, C. Acosta, A. Adeyemi, J Husbands, and James Pike
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Work productivity ,Pediatrics ,medicine.medical_specialty ,business.industry ,Health Policy ,Multiple sclerosis ,Public Health, Environmental and Occupational Health ,medicine.disease ,First line treatment ,Natalizumab ,Relapsing remitting ,Health care ,medicine ,Resource use ,business ,medicine.drug - Published
- 2020
15. Striosomes Mediate Value-Based Learning Vulnerable in Age and a Huntington’s Disease Model
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Sebastien Delcasso, Dan Hu, Emily Hueske, Sabrina M. Drammis, Qingyang Zhang, Charu Ramakrishnan, Leif G. Gibb, Joshua K. Xiong, Karl Deisseroth, Cody A. Siciliano, Lara I. Rakocevic, Alexander Friedman, Tomoko Yoshida, Sebastian E. Toro Arana, Erik D. Nelson, Jiajia Zhao, Hope Lutwak, Thomas J. Diefenbach, Kaden S. DiMarco, Ann M. Graybiel, Raimundo X. Rodriguez, and Cody W. Carter
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Aging ,Striosome ,Models, Neurological ,education ,Action Potentials ,Value (computer science) ,Mice, Transgenic ,Striatum ,Biology ,Article ,General Biochemistry, Genetics and Molecular Biology ,Discrimination Learning ,Photometry ,03 medical and health sciences ,0302 clinical medicine ,Calcium imaging ,Reward ,Huntington's disease ,Interneurons ,Task Performance and Analysis ,medicine ,Animals ,Learning ,Discrimination learning ,030304 developmental biology ,0303 health sciences ,Behavior, Animal ,Compartment (ship) ,Task engagement ,medicine.disease ,Corpus Striatum ,Disease Models, Animal ,Huntington Disease ,Parvalbumins ,Nerve Net ,Neuroscience ,Biomarkers ,030217 neurology & neurosurgery - Abstract
Learning valence-based responses to favorable and unfavorable options requires judgments of the relative value of the options, a process necessary for species survival. We have found, using engineered mice, that circuit connectivity and function of the striosome compartment of the striatum are critical for this type of learning. Calcium imaging during valence-based learning exhibited a selective correlation between learning and striosomal, but not matrix, signals. This striosomal activity encoded discrimination learning and was correlated with task engagement, which could, in turn, be regulated by chemogenetic excitation and inhibition. Striosomal function during discrimination learning was disturbed with aging, and severely so in a mouse model of Huntington’s disease. Anatomical and functional connectivity of parvalbumin-positive, putative fast-spiking interneurons (FSIs) to striatal projection neurons was enhanced in striosomes compared to matrix in mice that learned. Computational modeling of these findings suggests that FSIs can modulate striosomal signal-to-noise ratio, crucial for discrimination and learning.
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- 2020
16. PMU19 FIRST LINE TREATMENT WITH NATALIZUMAB REDUCES HEALTHCARE RESOURCE USE AND IMPAIRMENT OF WORK PRODUCTIVITY AND ACTIVITY IMPAIRMENT IN RELAPSING-REMITTING MULTIPLE SCLEROSIS (RRMS) PATIENTS COMPARED TO NATALIZUMAB DELAYED USE
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C. Acosta, E. Jones, J. Pike, A. Adeyemi, S. Liao, R. Su, K. Xiong, and J. Husbands
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Health Policy ,Public Health, Environmental and Occupational Health - Published
- 2020
17. Attention Training in Anxiety Using Attention Bias Modification and Electrophysiology Methods
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K. Xiong, Sarah M. Sass, and Travis C. Evans
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Electrophysiology ,medicine ,Anxiety ,Attention training ,Attentional bias ,medicine.symptom ,Psychology ,Cognitive psychology - Published
- 2018
18. Community-managed groundwater irrigation on the Vientiane Plain of Lao PDR: planning, implementation and findings from a pilot trial
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C. Clement, J. Vinckevleugel, P. Pavelic, K. Xiong, L. Valee, T. Sotoukee, B. R. Shivakoti, and K. Vongsathien
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Irrigation ,Geography ,Agricultural development ,Cash crop ,Pilot trial ,Groundwater irrigation ,Soil properties ,Community management ,Climate resilience ,Water resource management - Published
- 2018
19. EP28.13: An analysis of the nursing model in patients with an intrauterine pregnancy complicated with ovarian torsion
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Y. Ouyang, Q. Wu, Q. He, Xia Li, and K. Xiong
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medicine.medical_specialty ,Radiological and Ultrasound Technology ,business.industry ,Obstetrics ,Ovarian torsion ,Obstetrics and Gynecology ,General Medicine ,medicine.disease ,Intrauterine pregnancy ,Reproductive Medicine ,Medicine ,Radiology, Nuclear Medicine and imaging ,In patient ,business - Published
- 2019
20. Compact autonomous navigation system (CANS)
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H. Y. Cheng, Y. C. Hao, K. Xiong, L. Ying, and G. D. Qiao
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Optical fiber ,Spacecraft ,business.industry ,Computer science ,Autonomous Navigation System ,Real-time computing ,law.invention ,Lens (optics) ,law ,Satellite ,Noise (video) ,business ,Energy (signal processing) ,Constellation - Abstract
Autonomous navigation of Satellite and constellation has series of benefits, such as to reduce operation cost and ground station workload, to avoid the event of crises of war and natural disaster, to increase spacecraft autonomy, and so on. Autonomous navigation satellite is independent of ground station support. Many systems are developed for autonomous navigation of satellite in the past 20 years. Along them American MANS (Microcosm Autonomous Navigation System) [1] of Microcosm Inc. and ERADS [2],[3] (Earth Reference Attitude Determination System) of Honeywell Inc. are well known. The systems anticipate a series of good features of autonomous navigation and aim low cost, integrated structure, low power consumption and compact layout. The ERADS is an integrated small 3-axis attitude sensor system with low cost and small volume. It has the Earth center measurement accuracy higher than the common IR sensor because the detected ultraviolet radiation zone of the atmosphere has a brightness gradient larger than that of the IR zone. But the ERADS is still a complex system because it has to eliminate many problems such as making of the sapphire sphere lens, birefringence effect of sapphire, high precision image transfer optical fiber flattener, ultraviolet intensifier noise, and so on. The marginal sphere FOV of the sphere lens of the ERADS is used to star imaging that may be bring some disadvantages., i.e. , the image energy and attitude measurements accuracy may be reduced due to the tilt image acceptance end of the fiber flattener in the FOV. Besides Japan, Germany and Russia developed visible earth sensor for GEO [4]、[5]. Do we have a way to develop a cheaper/easier and more accurate autonomous navigation system that can be used to all LEO spacecraft, especially, to LEO small and micro satellites? To return this problem we provide a new type of the system—CANS (Compact Autonomous Navigation System) [6].
- Published
- 2017
21. Progesterone regulates hypothalamic-pituitary-thyroid axis
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Wang X, K Xiong, and C Zhong
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medicine.medical_specialty ,Messenger RNA ,animal structures ,medicine.medical_treatment ,Thyroid ,Biology ,biology.organism_classification ,Hypothalamic–pituitary–thyroid axis ,Steroid hormone ,medicine.anatomical_structure ,Endocrinology ,Internal medicine ,embryonic structures ,medicine ,Thyroid hormone synthesis ,Endocrine system ,Gene ,Zebrafish - Abstract
Progesterone is a natural steroid hormone excreted by animals and humans, which has been frequently detected in the aquatic ecosystems. The effects of the residual progesterone on fish are unclear. In this study, we aimed to examine the effects of progesterone on the hypothalamic-pituitary-thyroid (HPT) axis by detecting the gene transcriptional expression levels. Zebrafish embryos were treated with different concentrations of progesterone from 12 hours post-fertilization (hpf) to 120 hpf. Total mRNA was extracted and the transcriptional profiles of genes involved in HPT axis were examined using qPCR. The genes related to thyroid hormone metabolism and thyroid hormone synthesis were up-regulated in zebrafish exposed to progesterone. These results indicated that progesterone affected the mRNA expression of genes involved in the HPT axis, which might interrupt the endocrine system in zebrafish. Our data also suggested that zebrafish is a useful tool for evaluating the effects of chemicals on the thyroid endocrine system.
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- 2017
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22. 2D Qp-Wave Anisotropic Stereotomography in Triangulated Model
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J.X. Zhou, W.D. Shao, K. Xiong, and K. Yang
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Physics ,Geometry ,Anisotropy - Published
- 2017
23. [Comparison of two quantitative methods of endobronchial ultrasound real-time elastography for evaluating intrathoracic lymph nodes]
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X W, Mao, J Y, Yang, X X, Zheng, L, Wang, L, Zhu, Y, Li, H K, Xiong, and J Y, Sun
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Adult ,Male ,China ,Biopsy, Fine-Needle ,Middle Aged ,Thorax ,Sensitivity and Specificity ,Endosonography ,Predictive Value of Tests ,Bronchoscopy ,Elasticity Imaging Techniques ,Humans ,Female ,Lymph Nodes ,Endoscopic Ultrasound-Guided Fine Needle Aspiration ,Aged - Published
- 2017
24. Impairment of zebrafish reproduction upon exposure to melengestrol acetate
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C Zhong, Wang X, and K Xiong
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medicine.medical_specialty ,media_common.quotation_subject ,Aquatic animal ,Fish reproduction ,Biology ,biology.organism_classification ,Melengestrol acetate ,Andrology ,chemistry.chemical_compound ,Endocrinology ,chemistry ,Endocrine disruptor ,Internal medicine ,medicine ,Endocrine system ,Reproduction ,Zebrafish ,Testosterone ,media_common - Abstract
Synthetic progestins contamination is common in the aquatic ecosystem, which may lead to serious health problem on aquatic animals. Melengestrol acetate (MGA) has been detected in the aquatic environment; however, its potential effects on fish reproduction are largely unclear. Here, we aimed to investigate the endocrine disruption and impact of MGA on zebrafish reproduction. Six-month old reproductive zebrafish were exposed to four nominal concentrations of MGA (1,10, 100 and 200 ng/L) for 15 days. Treatment with MGA reduced the egg production with a significant decrease at 200 ng/L. The circulating concentrations of estradiol and testosterone in female zebrafish or 11-keto testosterone in male zebrafish were significantly diminished compared to the non-exposed control fish. The early embryonic development or hatching rates were unaffected during the MGA exposure. Our results indicated that MGA was a potent endocrine disruptor in fish and the fish reproduction could be impaired even during a short-term exposure to MGA.
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- 2017
- Full Text
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25. Quantitative Analysis of Dopamine Neuron Subtypes Generated from Mouse Embryonic Stem Cells
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Diane Hoffman-Kim, Kimberly A. Seymour, Jason T. Machan, Yu-Ting L. Dingle, K Xiong, Mark Zervas, and Debra L. Ellisor
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0303 health sciences ,biology ,Anatomy ,Calbindin ,Embryonic stem cell ,Cell biology ,03 medical and health sciences ,0302 clinical medicine ,FGF8 ,medicine.anatomical_structure ,nervous system ,Cell culture ,Dopamine ,embryonic structures ,biology.protein ,medicine ,Neuron ,Sonic hedgehog ,Calretinin ,030217 neurology & neurosurgery ,030304 developmental biology ,medicine.drug - Abstract
Dopamine (DA) neuron subtypes modulate specific physiological functions and are involved in distinct neurological disorders. Embryonic stem cell (ESC) derived DA neurons have the potential to aid in the study of disease mechanisms, drug discovery, and possibly cell replacement therapies. DA neurons can be generated from ESCs in vitro, but the subtypes of ESC-derived DA neurons have not been investigated in detail despite the diversity of DA neurons observed in vivo. Due to cell culture heterogeneity, sampling methods applied to ESC-derived cultures can be ambiguous and potentially biased. Therefore, we developed a quantification method to capture the depth of DA neuron production in vitro by estimating the error associated with systematic random sampling. Using this method, we quantified calbindin+ and calretinin+ subtypes of DA neurons generated from mouse ESCs. We found a higher production of the calbindin+ subtype (11−27%) compared to the calretinin+ subtype (2-13%) of DA neuron; in addition, DA neurons expressing neither subtype marker were also generated. We then examined whether exogenous sonic hedgehog (SHH) and fibroblast growth factor 8 (FGF8) affected subtype generation. Our results demonstrate that exogenous SHH and FGF8 did not alter DA neuron subtype generation in vitro. These findings suggest that a deeper understanding DA neuron derivation inclusive of mechanisms that govern the in vitro subtype specification of ESC-derived DA neurons is required.NoteAll research was planned and conducted while members were at Brown UniversityResearch fundingNIH/NCRR/NIGMS RI Hospital COBRE Center for Stem Cell Biology (8P20GM103468-04) (MZ) Brown Institute for Brain Science Pilot Grant (4-63662) (MZ/DHK)
- Published
- 2016
- Full Text
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26. Corrigendum to 'Attention training to pleasant stimuli in anxiety' [Biol. Psychol. 122 (2017) 80–92]
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F. Mirghassemi, K. Xiong, Sarah M. Sass, H. Tran, and Travis C. Evans
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medicine.medical_specialty ,Neuropsychology and Physiological Psychology ,General Neuroscience ,medicine ,Anxiety ,Attention training ,Audiology ,medicine.symptom ,Psychology - Published
- 2019
27. Influence of the exchange-correlation potential on the electrochemical properties of multicomponent silicate cathode materials
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Kyeongjae Cho, W. Wang, K. Xiong, and Roberto C. Longo
- Subjects
Battery (electricity) ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,Electrochemistry ,Redox ,Cathode ,Silicate ,law.invention ,Ion ,chemistry.chemical_compound ,chemistry ,law ,Electrode ,Physical chemistry ,Density functional theory - Abstract
In this paper we report density-functional theory (DFT) calculations at various levels of accuracy to compare the electrochemical properties of several silicate compounds as possible cathode materials in Li-ion batteries. We have tested the already known olivine-like structure (LiMSiO 4 , M = Mn, Fe, Co, and Ni) and the more recently discovered tetrahedral Pmn 2 1 Li 2 MSiO 4 (M = Mn, Fe, Co, and Ni). Our calculations show the influence of exchange and correlation potentials used to compute the redox potentials, electronic band gaps and other properties of these materials. A detailed study of the multicomponent effect on those characteristics gives us useful insight about how to improve the electrochemical performance of the cathode and its efficiency in the Li-ion battery.
- Published
- 2012
28. Life quality of Chinese patients with chronic urticaria as assessed by the dermatology life quality index
- Author
-
J.-B. Liu, H. Zhou, L.-K. Xiong, A.-L. Si, and M.-Z. Yao
- Subjects
medicine.medical_specialty ,business.industry ,Life quality ,Dermatology ,Dermatology Life Quality Index ,Factor structure ,humanities ,Confirmatory factor analysis ,Chinese version ,Infectious Diseases ,Quality of life ,Physical therapy ,medicine ,business ,Chronic urticaria ,Reliability (statistics) - Abstract
Background No report focused on the life quality of Chinese patients with chronic urticaria (CU). It was also due to lack of data to assess the usage of the Dermatology Life Quality Index (DLQI) in Chinese patients. Objectives We explored the quality of life (QoL) of Chinese patients with CU and assessed the factor structure and reliability of the Chinese version of the DLQI. Methods The DLQI scores were recorded to evaluate the life quality of out-patients with CU. The reliability and the factor structure of the DLQI were assessed using reliability analysis and factor analysis. Results A total of 131 patients completed the DLQI. The mean score was 9.93 that was significantly associated with the patient’s age (P = 0.01). Chronic urticaria had the greatest effect on the ‘Syndrome and Feeling’ (50.64%), followed by ‘Work/School’ (41.98%). A reliability analysis showed that the value of the Cronbach’sα reached 0.85 if item 1 in the DLQI was excluded. Both exploratory and confirmatory factor analysis indicated that there were two latent common factors underlying the items in the questionnaire. Conclusions Chronic urticaria has a moderate impact on the life quality. More attention should be paid to the interference from item 1 in assessing the QoL by the DLQI, although it remains a concise tool with high reliability.
- Published
- 2011
29. Non-linear robust filter design for satellite attitude determination
- Author
-
Y. Liu, K. Xiong, and L. Liu
- Subjects
Engineering ,Control and Optimization ,business.industry ,System identification ,Covariance ,Nonlinear control ,Upper and lower bounds ,Stability (probability) ,Computer Science Applications ,Human-Computer Interaction ,Attitude control ,Control and Systems Engineering ,Control theory ,Filter (video) ,Electrical and Electronic Engineering ,Robust control ,business - Abstract
In this study, a non-linear robust filter (NRF) is proposed for a satellite attitude determination system. The system under consideration is subject to both the model parameter uncertainties and the linearisation errors. The proposed NRF is derived to guarantee an optimised upper bound on the estimation error covariance. The characteristics of the filter are analysed using some standard results from stochastic stability theory. It is specified that the stability of the proposed algorithm can be guaranteed independent of the model uncertainties as well as the linearisation errors. In addition, the efficiency of the NRF is demonstrated with the telemetry data from a satellite. The algorithm is developed in general such that it can be applied to stochastic uncertain non-linear systems other than satellite attitude determination.
- Published
- 2010
30. Robust unscented Kalman filtering for nonlinear uncertain systems
- Author
-
L. D. Liu, K. Xiong, and C. L. Wei
- Subjects
Engineering ,Extended Kalman filter ,Control and Systems Engineering ,Control theory ,business.industry ,Nonlinear filter ,Fast Kalman filter ,Ensemble Kalman filter ,Filter (signal processing) ,Unscented transform ,Kalman filter ,business ,Invariant extended Kalman filter - Abstract
A derivative-free robust Kalman filter algorithm is proposed for nonlinear uncertain systems. The unscented transform (UT) is adopted instead of the linearization technique to obtain the solution of the H∞ filter Riccati equation. A robust unscented Kalman filter (RUKF) is derived to guarantee an optimized upper bound on the estimation error covariance despite the model uncertainties and the approximation error of the UT. The proposed algorithm is applied to a satellite attitude determination system. Simulation results show that the RUKF is more effective than the unscented Kalman filter (UKF) in cases where alignment errors are present. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
- Published
- 2010
31. microRNA-9 Acts as a Tumor Suppressor and Enhances Radio Sensitivity in Radio-Resistant A549 Cells by Targeting NRP1
- Author
-
L. Xue and K. Xiong
- Subjects
A549 cell ,Cancer Research ,Radiation ,business.industry ,Radio sensitivity ,law.invention ,Oncology ,law ,Neuropilin 1 ,Cancer research ,Medicine ,Suppressor ,Radiology, Nuclear Medicine and imaging ,business - Published
- 2017
32. Comparative Study on MOCVD Growth of a-Plane GaN Films on r-Plane Sapphire Substrates Using GaN, AlGaN, and AlN Buffer Layers
- Author
-
Y. Q. Sun, Q. H. He, Q. Zhang, Fernando Ponce, Z. H. Wu, Changqing Chen, X. Y. Han, Jiangnan Dai, L. Z. Tong, C. H. Yu, and Y. K. Xiong
- Subjects
Materials science ,Aluminium nitride ,business.industry ,Gallium nitride ,Condensed Matter Physics ,Epitaxy ,Mosaicity ,Electronic, Optical and Magnetic Materials ,Crystal ,chemistry.chemical_compound ,Crystallography ,chemistry ,Materials Chemistry ,Sapphire ,Optoelectronics ,Metalorganic vapour phase epitaxy ,Electrical and Electronic Engineering ,Thin film ,business - Abstract
In this work, we have comparatively investigated the effects of the GaN, AlGaN, and AlN low-temperature buffer layers (BL) on the crystal quality of a-plane GaN thin films grown on r-plane sapphire substrates. Scanning electron microscopy images of the a-plane GaN epilayers show that using an AlGaN BL can significantly reduce the density of surface pits. The full-width at half-maximum values of the $$ (11\overline{2} 0) $$ x-ray rocking curve (XRC) are 0.19°, 0.36°, and 0.48° for the films grown using Al0.15Ga0.85N, GaN, and AlN BLs, respectively, indicating that an AlGaN BL can effectively reduce the mosaicity of the films. Room-temperature photoluminescence shows that the AlGaN BL results in lower impurity incorporation in the subsequent a-plane GaN films, as compared with the case of GaN and AlN BLs. The higher crystal quality of a-plane GaN films produced by the Al0.15Ga0.85N BL could be due to improvement of BL quality by reducing the lattice mismatch between the BL and r-sapphire substrates, while still keeping the lattice mismatch between the BL and epitaxial a-plane GaN films relatively small.
- Published
- 2009
33. Modified unscented Kalman filtering and its application in autonomous satellite navigation
- Author
-
K. Xiong, L.D. Liu, and Hanxin Zhang
- Subjects
Extended Kalman filter ,Noise ,Control theory ,Covariance matrix ,Computer science ,Orbit (dynamics) ,Aerospace Engineering ,Satellite navigation ,Kalman filter ,Unscented transform ,Filter (signal processing) - Abstract
In this paper, a modified unscented Kalman filter (UKF) for nonlinear stochastic systems is proposed, and it is applied to autonomous orbit determination for Earth satellites. Based on some standard results about the boundedness of stochastic processes and a new formulation of the unscented transformation (UT), it is demonstrated that the design of the noise covariance matrix plays an important role in enhancing the filter stability. Furthermore, a particular design of the noise covariance matrix is proposed as a modification of the UKF. The modified UKF is less sensitive to the initial error than the usual one. High performance of the modified UKF is illustrated in comparison with the usual one by using the real data obtained from an Earth sensor.
- Published
- 2009
34. Taxonomic Diversity of Rhizosphere Bacteria in Golf Course Putting Greens at Representative Sites in the Southeastern United States
- Author
-
Monica L. Elliott, J.A. McInroy, H. D. Skipper, Elizabeth A. Guertal, J.H. Kim, and K. Xiong
- Subjects
Bacillus (shape) ,Rhizosphere ,Cynodon ,Agrostis ,biology ,Microbacterium ,Botany ,Poaceae ,Horticulture ,Cynodon dactylon ,biology.organism_classification ,Flavobacterium - Abstract
Taxonomic diversity of bacteria associated with golf course putting greens is a topic that has not been widely explored. The purpose of this project was to isolate and identify culturable bacteria from the rhizosphere of creeping bentgrass (Agrostris palustris Huds.) at two sites (Alabama and North Carolina) and hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] at two sites (Florida and South Carolina) for a minimum of 3 years with sampling initiated after the construction process. Randomly selected colonies were identified using gas chromatography for analysis of fatty acid methyl ester profiles. Over 9000 isolates were successfully analyzed. When a similarity index of 0.300 or higher was used, the average number of unidentifiable isolates was 38.6%. The two dominant genera in both bentgrass and bermudagrass rhizospheres were Bacillus and Pseudomonas with Bacillus dominant in bermudagrass and Pseudomonas dominant or equal to Bacillus in bentgrass. Other genera that comprised at least 1% of the isolates at all four sites were Clavibacter, Flavobacterium, and Microbacterium. Arthrobacter also comprised a significant portion of the bacterial isolates in the bentgrass rhizosphere, but not the bermudagrass rhizosphere. Overall, there were 40 genera common to all four sites. At the species level, there were five that comprised at least 1% of the isolates at each location: B. cereus, B. megaterium, C. michiganensis, F. johnsoniae, and P. putida. As has been reported for many grasses, we found considerable taxonomic diversity among the culturable bacterial populations from the rhizospheres of bentgrass and bermudagrass grown in sand-based putting greens.
- Published
- 2008
35. Adaptive robust extended Kalman filter for nonlinear stochastic systems
- Author
-
Li Liu, K. Xiong, and Hui Zhang
- Subjects
Control and Optimization ,Adaptive control ,Kalman filter ,Nonlinear control ,Invariant extended Kalman filter ,Computer Science Applications ,Human-Computer Interaction ,Adaptive filter ,Extended Kalman filter ,Control and Systems Engineering ,Filter (video) ,Control theory ,Electrical and Electronic Engineering ,Robust control ,Mathematics - Abstract
The authors analyse the error behaviour of the robust extended Kalman filter (REKF) for nonlinear stochastic systems. On the basis of some standard results about the boundedness of stochastic processes, it is specified that stability of the REKF cannot be guaranteed. In order to solve this problem, a novel method is proposed to design the REKF so that the sufficient conditions to ensure filter stability will be fulfilled. Furthermore, an adaptive scheme is adopted to automatically tune the error covariance matrix in response to the changing environment. Numerical example shows the superiority of the proposed adaptive REKF over the usual extended Kalman filter (EKF), the REKF and the adaptive EKF.
- Published
- 2008
36. Effect of degas before metal gate deposition on the threshold voltage
- Author
-
J. Petry, Lars-Ake Ragnarsson, J.C. Hooker, K. Xiong, and R. Singanamalla
- Subjects
Passivation ,business.industry ,Chemistry ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,PMOS logic ,Threshold voltage ,Gate oxide ,Optoelectronics ,Work function ,Electrical and Electronic Engineering ,business ,Metal gate ,NMOS logic ,Leakage (electronics) - Abstract
The interaction between the dielectric and the metal gates is crucial for effective workfunction and V"T. In this work, we investigate the effect of a degas step just before the metal gate deposition. The purpose of this step is to remove the water adsorbed at the surface of the dielectric by heating it under vacuum. Removing the water also means the suppression of an O source during following processing steps of the device. This leads to lower oxygen vacancies passivation. When the maximum of water is removed from the surface, NMOS long channel V"T is decreased and PMOS long channel absolute V"T is increased. From the dielectric point of view, degassing leads to lower intrinsic quality as measured by gate leakage increase as a function of the temperature.
- Published
- 2007
37. Electronic and atomic structure of Ge2Sb2Te5 phase change memory material
- Author
-
K. Xiong, P. W. Peacock, and John Robertson
- Subjects
Phase transition ,Valence (chemistry) ,Condensed matter physics ,Chemistry ,Band gap ,Stereochemistry ,Metals and Alloys ,Surfaces and Interfaces ,Electronic structure ,Crystal structure ,Crystallographic defect ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Materials Chemistry ,Open shell - Abstract
Electronic structure calculations are presented for various model structures of the crystalline and amorphous phases of Ge 2 Sb 2 Te 5 . The structures are all found to possess a band gap of order 0.5 eV, indicating closed shell behaviour. It is pointed out that structural vacancies in A7-like Ge 2 Sb 2 Te 5 are not electronically active. In addition, A7-like structures do not support valence alternation pair defects, which are one model of the conduction processes in the amorphous phase in non-volatile memories.
- Published
- 2007
38. Detection of satellite attitude sensor faults using the UKF
- Author
-
K. Xiong, C.W. Chan, and H. Y. Zhang
- Subjects
Engineering ,business.industry ,Aerospace Engineering ,Kalman filter ,Fault detection and isolation ,Nonlinear system ,symbols.namesake ,Control theory ,Sample number ,Convergence (routing) ,symbols ,Satellite ,Electrical and Electronic Engineering ,business ,Gaussian process ,Statistical hypothesis testing - Abstract
A novel fault detection (FD) method for nonlinear systems using the residuals generated by the unscented Kalman filter (UKF) is proposed. The errors of the UKF are derived and sufficient conditions for the convergence of the UKF are presented. As the local approach is a powerful statistical technique for detecting changes in the mean of a Gaussian process, it is used to devise a hypothesis test to detect faults from residuals obtained from the UKF. Further, it is demonstrated that the selection of a sample number is important in improving the performance of the local approach. To illustrate the implementation and performance of the proposed technique, it is applied to detect sensor faults in the measurement of satellite attitude.
- Published
- 2007
39. An Efficient High-density Kinematic Invariant Picking Method for Stereotomography Based on Structure Tensors
- Author
-
K. Yang, K. Xiong, and Y. Wang
- Subjects
Regional geology ,Hydrogeology ,Engineering geology ,Kinematics ,Economic geology ,Invariant (mathematics) ,Petrology ,Algorithm ,Structure tensor ,Geology ,Environmental geology - Abstract
The efficiency and effectiveness of the stereotomography is highly dependent on the quality of its data space, the so-called kinematic invariant. The structure tensor is a very robust tool for the slope estimation. In this abstract, we present a highly efficient high-density kinematic invariant picking method based on structure tensors. Compared with the conventional slope search methods, the presented technique can improve the computational efficiency by one or two orders of magnitudes which will greatly enhance the applicability of the stereomography.
- Published
- 2015
40. Towards an Edge-preserving Stereotomography with a Practical Model Regularization Technique
- Author
-
K. Yang, Z.W. Li, Y.X. Wang, Y. Ni, and K. Xiong
- Subjects
Regional geology ,Hydrogeology ,Engineering geology ,Regularization (physics) ,Kinematics ,Economic geology ,Algorithm ,Geomorphology ,Geology ,Synthetic data ,ComputingMethodologies_COMPUTERGRAPHICS ,Environmental geology - Abstract
Despite of the limitation of the ray theory, an edge-preserving velocity model is always preferred for any a ray-based tomography method. In this abstract, we present a practical model regularization technique towards this goal by incorporating the blocky geological boundary information when deriving the Frechet derivatives matrix of the stereotomography. The updated model will automatically present the blocky geological boundary feature as it is supposed to be. The geological boundary information will be updated at the end of each iteration with a kinematic migration based on some zero-offset horizons picked in advance. Compared with the conventional edge preserving tomography or the multi-layer stereotomgraphy, the presented regularization technique does not depend on a hybrid velocity format or the hybrid regularization based on the edge preserving smooth operator. It is more straightforward and more easily implemented. The synthetic data example and the real data case demonstrated the effectiveness of the presented method. We expect that the inverted model can be used for reverse-time migration or as the good starting model for full-wave inversion.
- Published
- 2015
41. A New Beam-ray PSDM with Double-smearing Operator Based on Kinematic Attributes and Unified Kirchhoff Imaging Theory
- Author
-
H.M. Shan, K. Yang, and K. Xiong
- Subjects
Regional geology ,Scheme (programming language) ,Operator (computer programming) ,Engineering geology ,Kinematics ,Economic geology ,Curvature ,Petrology ,Algorithm ,computer ,Geology ,Environmental geology ,computer.programming_language - Abstract
With the help of the unified Kirchhoff imaging theory, we present a different way, the so-called isochrones-smearing scheme, to implement the CRS-beam PSDM based on the local kinematic attributes. Compared with the previous CRS-beam PSDM based on Hugens-curve-stacking scheme, the presented method takes the advantages of isochrones-smearing scheme in Kirchhoff method which will lead to less artifacts and more computational efficient. Moreover, if we just perform the first smearing, a high-S/N-ratio, regularized prestack dataset can be obtained. In the presented scheme, for each sample in data space, we just care about its local slope and local curvature. Thus we don’t have to use CRS or multifocusing method. Instead, we can use some more efficient algorithm to get these local kinematic attributes.It will further save the computational cost.
- Published
- 2015
42. Defect energy states in high-K gate oxides
- Author
-
John Robertson, Stewart J. Clark, and K. Xiong
- Subjects
Condensed matter physics ,Chemistry ,Band gap ,Electric potential energy ,Oxide ,chemistry.chemical_element ,Condensed Matter Physics ,Oxygen ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Vacancy defect ,Frenkel defect ,Energy level ,Atomic physics ,High-κ dielectric - Abstract
The electrical energy levels of the different charge states of the oxygen vacancy and the oxygen interstitial in HfO 2 are calculated, using density functional methods which do not need a band gap correction. Lattice distortions around the defect sites produce substantial shifts in the energy levels. The energy levels are aligned to those of the Si channel. In HfO 2 , the oxygen vacancy gives an energy level in the Si gap or just above the gap, depending on its charge state. The O vacancy is identified as the main electrically active defect and trap. The oxygen interstitial gives levels just above the oxide valence band, and the neutral interstitial also gives a level near the Si conduction band. The defect wavefunctions are given.
- Published
- 2006
43. Band structure of functional oxides by screened exchange and the weighted density approximation
- Author
-
K. Xiong, John Robertson, and Stewart J. Clark
- Subjects
Condensed matter physics ,Chemistry ,business.industry ,Band gap ,Diamond ,Electronic structure ,engineering.material ,Condensed Matter Physics ,Semimetal ,Electronic, Optical and Magnetic Materials ,Semiconductor ,Ab initio quantum chemistry methods ,engineering ,Local-density approximation ,Electronic band structure ,business - Abstract
Most ab-initio calculations of the electronic structure use the local density approximation, which gives good structural data but severely under-estimates the band gaps of semiconductors and insulators. This paper presents calculations of the band structures of some important oxide semiconductors and insulators, using the screened exchange method and the weighted density approximation, which give improved band gaps. The methods are tested on diamond, Si, Ge, MgO, Al 2 O 3 , and SiO 2 and the main interest is for HfO 2 , ZrO 2 , SrTiO 3 , PbTiO 3 , LaAlO 3 , La 2 O 3 , ZrSiO 4 , SnO 2 , CuAlO 2 , and SrCu 2 O 2 .
- Published
- 2006
44. Performance evaluation of UKF-based nonlinear filtering
- Author
-
C.W. Chan, H. Y. Zhang, and K. Xiong
- Subjects
Extended Kalman filter ,Noise ,Mean squared error ,Control and Systems Engineering ,Control theory ,Covariance matrix ,Monte Carlo method ,Kalman filter ,Electrical and Electronic Engineering ,Upper and lower bounds ,Cramér–Rao bound ,Mathematics - Abstract
The performance of the modified unscented Kalman filter (UKF) for nonlinear stochastic discrete-time system with linear measurement equation is investigated. It is proved that under certain conditions, the estimation error of the UKF remains bounded. Furthermore, it is shown that the design of noise covariance matrix plays an important role in improving the stability of the algorithm. Error behavior of the UKF is then derived in terms of mean square error (MSE), and the Cramer-Rao lower bound (CRLB) is introduced as a performance measure. The modified UKF is found to approach the CRLB if the difference between the real noise covariance matrix and the selected one is small enough. These results are verified by using Monte Carlo simulations on two example systems.
- Published
- 2006
45. Band gaps and defect levels in functional oxides
- Author
-
K. Xiong, Stewart J. Clark, and John Robertson
- Subjects
Condensed matter physics ,Chemistry ,Band gap ,business.industry ,Doping ,Metals and Alloys ,Wide-bandgap semiconductor ,Surfaces and Interfaces ,Electronic structure ,Semimetal ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Semiconductor ,Materials Chemistry ,Local-density approximation ,business ,Electronic band structure - Abstract
Most ab-initio calculations of the electronic structure use the local density approximation, which gives good structural data but severely underestimates the band gaps of semiconductors and insulators. This paper presents calculations of the band structures and oxygen vacancy levels of some important oxide semiconductors and insulators, using density functional methods which do give more accurate band gaps. The materials SnO2, Cu2O, SrCu2O2, CuAlO2, SrTiO3, HfO2, ZrO2, La2O3, ZrSiO4, and SiO2 are covered.
- Published
- 2006
46. LOCAL APPROACH FOR FAULT DETECTION IN REDUNDANT SENSOR CONFIGURATION
- Author
-
K. Xiong and H.Y. Zhang
- Subjects
Engineering ,Dodecahedron ,business.industry ,Control theory ,Inertial measurement unit ,Fault coverage ,Redundancy (engineering) ,General Medicine ,business ,Fault (power engineering) ,Algorithm ,Selection (genetic algorithm) ,Fault detection and isolation - Abstract
This paper presents the application of the local approach to detect small fault in redundant inertial sensors with a dodecahedron configuration. It is demonstrated that the selection of samples number plays an important role in improving the performance of the local approach. By enlarging the number of samples, the ability of the technique to detect fault will be enhanced significantly. In order to illustrate the effectiveness of the proposed method, the local approach is compared with the Generalized Likelihood Test (GLT) approach by experiment.
- Published
- 2006
47. UNSCENTED KALMAN FILTER FOR FAULT DETECTION
- Author
-
K. Xiong, H.Y. Zhang, and C.W. Chan
- Subjects
Nonlinear system ,Extended Kalman filter ,Engineering ,Control theory ,business.industry ,Convergence (routing) ,Unscented transform ,Kalman filter ,Fault (power engineering) ,business ,Fault detection and isolation - Abstract
In this paper, the approximation of nonlinear systems using unscented Kalman filter (UKF) is discussed, and the conditions for the convergence of the UKF are derived. The detection of faults from residuals generated by the UKF is presented. As fault detection often reduced to detecting irregularities in the residuals, such as the mean, the local approach, a powerful statistical technique to detect such changes, is used to detect fault from the residuals generated from the UKF. The properties of the proposed method are also presented. To illustrate the performance of the proposed method, it is applied to detect faults in the attitude sensors of a satellite.
- Published
- 2005
48. Diversity of Root Bacteria from Peanut Cropping Systems
- Author
-
D. T. Gooden, K. Xiong, J. H. Kim, and H. D. Skipper
- Subjects
Crop ,biology ,Agronomy ,Arthrobacter ,Sustainable agriculture ,Soil water ,Biological pest control ,Monoculture ,Crop rotation ,biology.organism_classification ,Rhizobacteria - Abstract
Rhizobacteria play an important role in sustainable agriculture via plant growth and biological control of pests in a number of ecosystems. Understanding the interactions of crop rotation and rhizobacteria on peanut production is a critical research need. Development of a database on the rhizobacteria obtained from continuous and rotational fields of peanut was initiated in 1997 and terminated in 2000. Peanut was planted in monoculture for 4 yr. In rotational plots, peanut, cotton, corn, and peanut were planted in sequence. Rhizobacteria were isolated from the roots of crop plants grown in a Norfolk soil near Florence, SC. These isolates were identified by composition of fatty acids from gas chromatography analysis (GC/FAME). Arthrobacter and Bacillus were the major genera from non-rhizosphere soils. At initiation of this study in July 1997, the plots selected for continuous peanut had more diversity in rhizobacteria than those plots selected for rotation. In July 2000, rhizobacteria diversity was greater from peanut roots in the rotation cropping system than continuous peanut. Even though rhizobacteria diversity was greater in the rotation system, higher peanut yields were recorded in the continuous peanut system in 2000. Burkholderia spp. were always isolated from the peanut and other crop rhizospheres at each sampling date.
- Published
- 2004
49. BIODEGRADATION AND SORPTION OF POLYASPARTATE IN SOILS 1
- Author
-
A. P. Wheeler, K. Xiong, and H. D. Skipper
- Subjects
integumentary system ,Chemistry ,Soil Science ,Mineralogy ,Mineralization (soil science) ,Biodegradation ,Soil type ,complex mixtures ,Nutrient ,Soil pH ,Environmental chemistry ,Soil water ,Microbial biodegradation ,Incubation - Abstract
Thermally synthesized polyaspartate (TPA, AmiSorb) is marketed as a crop growth enhancer. However, the stability and adsorption of this product in soils have not been fully evaluated. In this study, microbial degradation of TPA was determined in 10 different soils using 14 C-labeled TPA. Biodegradation, measured as mineralization (CO 2 production), varied with soil type ranging from 2.15% for a Hort Mix to 32.05% for the Pullman soil after 35 days incubation under the defined conditions. Percentages of degradation also varied with concentrations of the applied TPA. In most of the soils evaluated, TPA degradation rates were higher at 100 μg g -1 than at 2 or 10 μg g -1 after 35 days of incubation. In general, C and N supplements, as primary nutrients for microbial growth, reduced mineralization, suggesting that the level of readily available macronutrients in the soil influenced TPA utilization. Biodegradation of TPA was highly correlated with soil pH but was not correlated with any other soil parameters measured in this study, including Kd. The Kd values of the tested soils for TPA ranged from 10.6 to 98.8 mL g -1 for the Norfolk and Bolfar soils, respectively.
- Published
- 2003
50. A diagnosis of linear eddy-viscosity in turbulence modeling
- Author
-
Q.-D. Cai, Hui Zhao, A.-K. Xiong, Weidong Su, and Jiezhi Wu
- Subjects
Fluid Flow and Transfer Processes ,Physics ,Turbulence ,Mechanical Engineering ,Mathematical analysis ,Computational Mechanics ,Turbulence modeling ,Dissipation ,Condensed Matter Physics ,Vortex ,Physics::Fluid Dynamics ,Classical mechanics ,Mechanics of Materials ,Compressibility ,Boundary value problem ,Navier–Stokes equations ,Hyperbolic partial differential equation - Abstract
A general diagnosis is introduced to examine whether and under what condition any Reynolds-averaged Navier–Stokes or large-eddy simulation using models based on linear eddy-viscosity νt is mathematically compatible with the incompressible turbulent flows to be modeled. It is shown that νt is governed by two independent second-order linear partial differential equations with the spatial derivatives of mean or filtered velocity as coefficients. In particular, for two-dimensional mean or filtered flows the νt equation is globally hyperbolic except in some degenerated cases. Numerical examples show that when the hyperbolic equation is incompatible with the boundary condition for νt, the characteristics of the same family may self-intersect to form shocks with finite jumps of νt, caused by the strong dissipation gradient near strong shear layers and vortices. Since in any modeled flow the νt field is globally continuous, once the “νt-shocks” occur the modeling must distort the real flow by weakening or even el...
- Published
- 2002
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