Your search for: 'author:("Xu, Zhi")' has returned 11 results. (0.019s) Save search

Authors: Rampersad, Narad | Shallit, Jeffrey | Xu, Zhi

Article Type: Research Article

Abstract: In this paper we consider the computational complexity of the following problems: given a DFA or NFA representing a regular language L over a finite alphabet Σ, is the set of all prefixes (resp., suffixes, factors, subwords) of all words of L equal to Σ* ? In the case of testing universality for factors of languages, there is a connection to two classic problems: the synchronizing words problem of Černý, and Restivo's conjecture on the minimal uncompletable word.

Keywords: prefix, suffix, factor, subword, universality, PSPACE-complete, decision problem, polynomial time, synchronizing word, synchronizing automaton, Restivo's conjecture

DOI: 10.3233/FI-2012-680

Citation: Fundamenta Informaticae, vol. 116, no. 1-4, pp. 223-236, 2012

Authors: Chiniforooshan, Ehsan | Kari, Lila | Xu, Zhi

Article Type: Research Article

Abstract: Repetition avoidance has been intensely studied since Thue's work in the early 1900's. In this paper, we consider another type of repetition, called pseudopower, inspired by the Watson-Crick complementarity property of DNA sequences. A DNA single strand can be viewed as a string over the four-letter alphabet {A,C,G, T}, wherein A is the complement of T, while C is the complement of G. Such a DNA single strand will bind to a reverse complement DNA single strand, called its Watson-Crick complement, to form a helical double-stranded DNA molecule. The Watson-Crick complement of a DNA strand is deducible from, and thus …informationally equivalent to, the original strand. We use this fact to generalize the notion of the power of a word by relaxing the meaning of “sameness” to include the image through an antimorphic involution, the model of DNA Watson-Crick complementarity. Given a finite alphabet Σ, an antimorphic involution is a function θ : Σ* → Σ* which is an involution, i.e., θ2 equals the identity, and an antimorphism, i.e., θ(uv) = θ(v)θ(u), for all u ∈ Σ* . For a positive integer k, we call a word w a pseudo-kth-power with respect to θ if it can be written as w = u1 ... uk , where for 1 ≤ i, j ≤ k we have either ui = uj or ui = θ(uj ). The classical kth-power of a word is a special case of a pseudo-kth-power, where all the repeating units are identical. We first classify the alphabets Σ and the antimorphic involutions θ for which there exist arbitrarily long pseudo-kth-power-free words. Then we present efficient algorithms to test whether a finite word w is pseudo-kth-power-free. Show more

Keywords: pseudopower, pseudosquare, pseudocube, antimorphic involution, pattern avoidance

DOI: 10.3233/FI-2011-617

Citation: Fundamenta Informaticae, vol. 114, no. 1, pp. 55-72, 2012

Authors: Tao, Yaqin | Wang, Jingang | Xu, Zhi

Article Type: Research Article

Abstract: A double differential D-dot overvoltage sensor is proposed based on the D-dot principle for the purpose of faster and more accurate measurement of overvoltage signals. The proposed sensor is a new D-dot sensor structure consisting of four electrodes. It is applied together with the double differential input structure. This structure allows the sensor to operate in self-integration mode and achieve a wide frequency response characteristic while has a stronger anti-interference capability. The simulation demonstration and parameter design are carried out by using the Ansoft Maxwell. A test platform is constructed and used in the steady-state performance and lightning impulse transient-state …test of the sensor. Test results demonstrate that the double differential D-dot sensor has satisfying steady-state performances, manifested by small measurement phase and amplitude errors. It can be applied to internal overvoltage measurement of power system. Moreover, the double differential D-dot sensor is equipped with good transient characteristics. The relative error of the lightning wave rise time which is measured by the double differential D-dot sensor is controlled in the range of ±1.7% and the relative measurement error of lightning wave peak is smaller than ±2.0%. It can measure external overvoltages effectively. Show more

Keywords: Double differential input, D-dot sensor, overvoltage signal measurement, non-contact, Ansoft Maxwell

DOI: 10.3233/JAE-180076

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 58, no. 4, pp. 431-449, 2018

Authors: Xu, Zhi Wei | Chan, K.W. | Liao, W.H.

Article Type: Research Article

Abstract: Particle damping is an effective vibration suppression method. The purpose of this paper is to develop an empirical method for particle damping design based on extensive experiments on three structural objects – steel beam, bond arm and bond head stand. The relationships among several key parameters of structure/particles are obtained. Then the procedures with the use of particle damping are proposed to provide guidelines for practical applications. It is believed that the results presented in this paper would be helpful to effectively implement the particle damping for various structural systems for the purpose of vibration suppression.

Keywords: particle damping, vibration suppression

Citation: Shock and Vibration, vol. 11, no. 5-6, pp. 647-664, 2004

Authors: Xu, Zhi | Ding, Hongwei | Liu, Qianlin | Yang, Zhijun | Bao, Liyong | Zhan, Gang

Article Type: Research Article

Abstract: In order to solve the contradiction between wireless network application requirements and increasingly scarce spectrum resources, cognitive wireless network technology emerged. Based on the characteristics of wireless network nodes and combining multiple hybrid control strategies, this paper proposes a multi-priority dual-clock probability detection CSMA(MPDCPD-CSMA) protocol with a monitoring mechanism. The field-programmable gate array (FPGA) hardware circuit is used as an experimental research platform for the first time. Cognitive wireless network MAC protocol design and implementation. The design took full advantage of the flexibility of the FPGA, using a hardware description language Verilog HDL and schematic input combined with the QuartusII9.0 …circuit design. By comparing the statistical values of the circuit system with the theoretical values, it is verified that the design has the characteristics of good real-time performance, high reliability, and strong portability. It can effectively reduce system node energy consumption, improve system throughput, and can be applied to wireless networks. Show more

Keywords: cognitive wireless network, hybrid control strategy, field programmable gate array, schematic input, throughput

DOI: 10.3233/JIFS-169678

Citation: Journal of Intelligent & Fuzzy Systems, vol. 35, no. 2, pp. 1353-1361, 2018

Authors: Zhang, Yi | Zhao, Zhao | Xu, Hui-jie | He, Chong | Peng, Hao | Gao, Zhan | Xu, Zhi-yong

Article Type: Research Article

Abstract: BACKGROUND: Snoring source analysis is essential for an appropriate surgical decision for both simple snorers and obstructive sleep apnea/hypopnea syndrome (OSAHS) patients. OBJECTIVE: As snoring sounds carry significant information about tissue vibrations within the upper airway, a new feature entitled compressed histogram of oriented gradients (CHOG) is proposed to recognize vibration patterns of the snoring source acoustically by compressing histogram of oriented gradients (HOG) descriptors via the multilinear principal component analysis (MPCA) algorithm. METHODS: Each vibration pattern corresponds to a sole or combinatorial vibration among the four upper airway soft tissues of soft palate, lateral pharyngeal wall, tongue base, and …epiglottis. 1037 snoring events from noncontact sound recordings of 76 simple snorers or OSAHS patients during drug-induced sleep endoscopy (DISE) were evaluated. RESULTS: With a support vector machine (SVM) as the classifier, the proposed CHOG achieved a recognition accuracy of 89.8% for the seven observable vibration patterns of the snoring source categorized in our most recent work. CONCLUSION: The CHOG outperforms other single features widely used for acoustic analysis of sole vibration site. Show more

Keywords: Snoring source analysis, vibration pattern recognition, compressed histogram of oriented gradients, multilinear principal component analysis

DOI: 10.3233/BME-201086

Citation: Bio-Medical Materials and Engineering, vol. 31, no. 3, pp. 143-155, 2020

Authors: Xu, Zhi-Hong | Liu, Cai-Hong | Hang, Jun-Biao | Gao, Bei-Li | Hu, Jia-An

Article Type: Research Article

Abstract: Tyrosine kinase inhibitors (TKIs), a novel group of target-specific anti lung cancer drugs, have recently been found to resistant to some NSCLC cells which have the T790M EGFR mutation. However, recent investigations on the therapies of resistance to EGFR-TKIs are very limited. Therefore, it is important to develop more effective therapies to reverse EGFR-TKIs resistance. In our present study, erlotinib was used as the TKIs drug and the effects of the erlotinib on cell growth were evaluated. Cell viability and concentration dependent studies were performed using HCI-H1975 and HCI-H1299 cells alone with erlotinib, respectively. Further combined with rituximab, the results …showed that erlotinib and rituximab were significantly inhibited the cell growth. Furthermore, the combination of erlotinib and rituximab greatly decreased the expression of p-mTOR and p-EGFR. Additional results from western blotting and immunofluorescence assays demonstrated that the accumulation of rictor was also decreased on MAM. Thus, all these results suggested that EGFR-TKIs combined with CD20 mono-antibody significantly decrease the cell growth of H1975 cells and H1299, with T790M EGFR mutation, and inhibit the localization of the key mTOR pathway proteins to MAM. So, it may be a promising strategy for overcoming EGFR TKI resistance in NSCLC patients. Show more

Keywords: Rituximab, tyrosine kinase inhibitors, ER-membrane, NSCLC cells

DOI: 10.3233/CBM-170575

Citation: Cancer Biomarkers, vol. 20, no. 4, pp. 581-588, 2017

Authors: Pan, Li-Na | Ma, Yun-Fang | Hu, Jia-An | Xu, Zhi-Hong

Article Type: Research Article

Abstract: Circular RNA (circRNA) has been shown to participate in various tumors, including lung cancer. In the present study, we explored the expression and functional relevance of hsa_circ_0003288 in human non-small cell lung cancer (NSCLC). We verified that hsa_circ_0003288 expression was upregulated in lung cancer tissues and cell lines. Overexpression of hsa_circ_0003288 dramatically promoted lung cancer cell proliferation, colony formation, inhibited apoptosis, and increased cell migration and invasion in vitro . Xenograft experiments showed that hsa_circ_0003288 overexpression accelerated tumor growth in vivo . Mechanistically, hsa_circ_0003288 negatively regulated miR-145 to exert the oncogenic role in lung cancer. Overexpression of miR-145 decreased cell …proliferation, induced apoptosis, and suppressed migration and invasion in lung cancer. Additionally, miR-145 co-transfection abolished the oncogenic role of hsa_circ_0003288. Collectively, these findings identified a novel regulatory role of hsa_circ_0003288/miR-145 axis in the progression of NSCLC. Show more

Keywords: Non-small cell lung cancer, hsa_circ_0003288, miR-145

DOI: 10.3233/CBM-203198

Citation: Cancer Biomarkers, vol. 35, no. 4, pp. 349-357, 2022

Authors: Xu, Zhi-Qiang | Huang, Huang | Chen, Ya-Li | Gao, Yun-Ying | Xu, Jun | Marshall, Charles | Cai, Zhi-You | Xiao, Ming

Article Type: Research Article

Abstract: Extensive loss of hippocampal neurons serves a pathological basis for irreversible cognitive impairment in patients with Alzheimer’s disease (AD). However, this characteristic cannot be replicated by transgenic mouse models, and its underlying mechanisms are unclear. Here, we present evidence that different expression patterns of amyloid-β protein precursor (AβPP) secretases in human and mouse hippocampal neurons are a decisive cause of species difference in the susceptibility to Aβ pathogenesis. Cell bodies of both pyramidal and granular neurons did not appear to undergo Aβ deposits in the 10-month-old transgenic mutant human AβPP/presenilin-1 (PS1) mice. They expressed high levels of non-amyloidogenic α -secretase, …and its neuroprotective products soluble AβPPα , but low levels of amyloidogenic β-secretase and γ -secretase, and a neurotoxic product, Aβ42 peptide. Unlike those found in the mouse, human hippocampal neuronal cell bodies expressed β-secretase and γ -secretase, but not α -secretase, which could increase Aβ generation, thus undergoing death in response to various pathological conditions. Increased hippocampal neuronal apoptosis at 48 h following local microinjection of α -secretase antibody ADAM10 into the hippocampus of AβPP/PS1 mice further suggests that high α -secretase expression in mouse neuronal cell bodies is a factor in the paucity of neuronal loss in AD-like pathology. Therefore, selective down-regulation of brain α -secretase in transgenic AD models will better replicate the disease spectrum, including decreased brain soluble AβPPα levels and massive neuronal loss in AD patients, and be beneficial for preclinical therapeutic evaluation of AD. Show more

Keywords: Alzheimer’s disease, amyloid-β metabolism, AβPP/PS1 mice, hippocampus

DOI: 10.3233/JAD-150634

Citation: Journal of Alzheimer's Disease, vol. 51, no. 1, pp. 179-195, 2016

Authors: Li, Jing | Zhang, Meng | Xu, Zhi-Qiang | Gao, Chang-Yue | Fang, Chuan-Qin | Deng, Juan | Yan, Jia-Chuan | Wang, Yan-Jiang | Zhou, Hua-Dong

Article Type: Research Article

Abstract: To investigate whether vascular risk affects the progression of Alzheimer's disease (AD), 415 AD patients aged 65 years old and over without cerebrovascular diseases were enrolled and administered with a structured interview to assess demography, vascular risk factors, and cognitive and functional status at baseline, and 324 AD patients were followed up annually for 5 years. A mixed random effects regression model was used to identify the association between vascular risk, individual vascular risk factors, and the progression of AD. After adjusting for confounding factors, AD patients with vascular risk had faster cognitive and functional decline rates than the subjects …without such risk factors. Individual vascular risk factors including hypertension and diabetes mellitus, transient ischemic attack and cerebrovascular accident during the follow-up were independently associated with the progression of AD. Our findings suggest that vascular risk aggravates the progression of AD and may be involved in the etiologic process of AD. As such, control of vascular risk may slow down the progression of AD. Show more

Keywords: Alzheimer's disease, progression, vascular risk factor

DOI: 10.3233/JAD-2010-1383

Citation: Journal of Alzheimer's Disease, vol. 20, no. 2, pp. 491-500, 2010