Prevalence of Decreased Myocardial Blood Flow in Symptomatic Patients with Patent Coronary Stents: Insights from Low-Dose Dynamic CT Myocardial Perfusion Imaging

Yuehua Li,Mingyuan Yuan,Mengmeng Yu,Zhigang Lu,Chengxing Shen,Yining Wang,Bin Lu,Jiayin Zhang 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.4

Objective: To study the prevalence and clinical characteristics of decreased myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) in symptomatic patients without in-stent restenosis. Materials and Methods: Thirty-seven (mean age, 71.3 ± 10 years; age range, 48–88 years; 31 males, 6 females) consecutive symptomatic patients with patent coronary stents and without obstructive de novo lesions were prospectively enrolled to undergo dynamic CT-MPI using a third-generation dual-source CT scanner. The shuttle-mode acquisition technique was used to image the complete left ventricle. A bolus of contrast media (50 mL; iopromide, 370 mg iodine/mL) was injected into the antecubital vein at a rate of 6 mL/s, followed by a 40-mL saline flush. The mean MBF value and other quantitative parameters were measured for each segment of both stented-vessel territories and reference territories. The MBFratio was defined as the ratio of the mean MBF value of the whole stent-vessel territory to that of the whole reference territory. An MBFratio of 0.85 was used as the cut-off value to distinguish hypoperfused from non-hypoperfused segments. Results: A total of 629 segments of 37 patients were ultimately included for analysis. The mean effective dose of dynamic CT-MPI was 3.1 ± 1.2 mSv (range, 1.7–6.3 mSv). The mean MBF of stent-vessel territories was decreased in 19 lesions and 81 segments. Compared to stent-vessel territories without hypoperfusion, the mean MBF and myocardial blood volume were markedly lower in hypoperfused stent-vessel territories (77.5 ± 16.6 mL/100 mL/min vs. 140.4 ± 24.1 mL/100 mL/min [p < 0.001] and 6.4 ± 3.7 mL/100 mL vs. 11.5 ± 4 mL/100 mL [p < 0.001, respectively]). Myocardial hypoperfusion in stentvessel territories was present in 48.6% (18/37) of patients. None of clinical parameters differed statistically significantly between hypoperfusion and non-hypoperfusion subgroups. Conclusion: Decreased MBF is commonly present in patients who are symptomatic after percutaneous coronary intervention, despite patent stents and can be detected by dynamic CT-MPI using a low radiation dose.

Influence of Oleic and Lauric Acid on the Stability of Magnetorheological Fluids

Yuehua Huang,Yuhuan Jiang,Xiongbo Yang,Ruizhen Xu 한국자기학회 2015 Journal of Magnetics Vol.20 No.3

In this paper, magnetorheological fluids (MRFs) based on micro-sized iron particles dispersed in silicone oil are presented. The iron particles are modified by adding different ratios of oleic acid and lauric acid as surfactants to the suspensions. Lauric acid was found to reduce the stability of the MRFs, and more lauric acid results in a higher rate of sedimentation. Further study showed that the formation and structure of lauric acid may result in the sedimentation of micrometer-sized particles. Meanwhile, the electro-resistance of MRF in this paper shows a decrease from beyond 6000 MΩ to 190 Ω with an increase in the external field from 0 mT to 400 mT.

Study of the Non-Linearity on TiO2(0 0 1) Surface with Oxygen Defects: A First-Principles Study

Yuehua Dai,Xu Zhang,Chengzhi Ma,Zhiyong Pan,Feifei Wang,Wenjuan Lu,Jin Yang,Fei Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.8

First-principles plane-wave pseudopotential calculations were performed to study the energetics and electronic structures of oxygen defects on rutile TiO2(0 0 1). The influence of the material thickness on non-linearity (NL) was studied. With the increase in the thickness, the NL became stronger. Calculating the site-projected density of states by applying an external electric field showed that the NL of the bulk is due to the exchange of electrons between O 2p orbitals and Ti 3d orbitals. Finally, the influence of oxygen defects—oxygen vacancies (Vo), oxygen interstitials (Oi), and oxygen vacancies/oxygen interstitial (Vo + Oi) pairs (Frenkel pair defects)—on the NL of TiO2 was studied. These results demonstrate that the band gap (Eg) of TiO2 became gradually narrower as the electric field increased. The Stark effect and defects can lead to the splitting of degenerate energy levels. Stronger electric fields increase the band splitting and reduce Eg. With the increase in the Vo concentration, the decrease in the splitting amplitude and width of the energy level lead to weakening of the transfer of electrons between O and Ti atoms and optimizing the NL of TiO2. Therefore, the incorporation of Vo plays a significant role in improving the NL of TiO2.

Effect of Graphene/TiO2 (001) Interface on Threshold Voltage and Nonlinearity

Yuehua Dai,Shanshan Gong,Zhisheng Zhong,Fengyu Gao,Feifei Wang,Cheng Ding,Jin Yang,Fei Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6

In this work, the threshold voltage (Vth) and nonlinearity (NL) of Graphene (Gra)/TiO2/Gra heterojunction were studied. First, the density functional tight binding (DFTB+) and much more dynamics were used to investigate the IV curves and the resistive switching properties of TiO2 slab and Gra/TiO2/Gra heterojunction. The NL of Gra/TiO2/Gra heterojunction is stronger than that of the TiO2 slab. The Vth of the resistive transition of the heterojunction is larger than that of the TiO2 slab. The tunneling probabilities and the Mulliken atomic population at the Gra/TiO2 interface under different electric fields were calculated by the Cambridge sequential total energy package (CASTEP). Results showed that both the parameters evidently increased under a certain numerical electric field. Finally, the movement of atom in the electric field and the change in the chemical bond were simulated by DFTB+ module. The effect of the Gra/TiO2 interface on Vth and NL was further illustrated. Postponed Vth and improved NL were found at the heterojunction relative to the TiO2 slab due to the presence of the interface barrier. This work provides guidance and reference for design and optimization of TiO2-based selectors.

Study on Food Safety Emergencies Knowledge Acquisition and Representation on Ontology

Yang Yuehua,Du Junping,Sun Zengqi,Jia Yingmin 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

Study knowledge acquisition of food safety emergencies based on ontology, and use this method to acquire classes, properties, relations and axioms of food safety emergencies field; Study knowledge representation based on ontology, and on this basis construct a shared, reusable, extensible food safety emergencies domain ontology, and describe it in OWL form, hence form a set of relatively complete food safety emergencies knowledge acquisition and knowledge representation system, as is applied to the establishment of a food safety emergency knowledge base ,it can greatly improve the efficiency of knowledge search and knowledge reasoning.

Study on SNS Graph Generation and Prediction

Yang Yuehua,Du Junping,Jia Yingmin,Sun Zengqi 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

As the users of social network sites increases, the types of applications service social network sites provide are becoming more and more. This paper establishes an SNS graph generation model based on social services provided by kaixin.com, which describes the intrinsic relationship of entities (users, groups, applications, posts, and albums) in the site; extracts some rules according to the relationship of entities and applies these rules to the SNS graph generation, so the SNS graph can be updated dynamically with the selected social network site;Finally proposes an algorithm used to predict which applications may obtain more users in the future roughly based on SNS graph and according to the prediction results the social network site can adjust its website structure thereby absorbing more users.

Sino-Christian Teology in Chinese Christian Teological Tradition : Its Historical Context and Epistemological Approaches

CHEN Yuehua 장로회신학대학교 2014 ASIA‒PACIFIC JOURNAL OF THEOLOGICAL STUDIES Vol.2 No.-

Sino-Christian Theology is an academic movement of Christian studies in modern Chinese humanities and social science. Through the past 1300 years, the tradition of Chinese Christian theology has attempted to merge into Chinese culture in the way of contextualization, and it is embodied in different forms according to political and social contexts, while each form of Chinese theology positively tries to inherit the successful elements of its predecessors. Sino-Christian Theology is the new embodied form of Chinese theological tradition according to modern Chinese context. It differs from its predecessors because: its knowledge innovator is an academic community rather than the local church; it not only includes the “into-context” approach but also the “out-of-context” approach; its epistemological approaches are fully inter-cultural, inter-disciplinary, and inter-faith.

Modified Constraint Scores for Semi-Supervised Feature Selection

Jianqiao Wang,Yuehua Li,Kun Chen 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

Semi-supervised constraint scores, which utilize both pairwise constraints and the local property of the unlabeled data to select features, achieve comparable performance to the supervised feature selection methods. The local property is characterized without considering the pairwise constraints and these two conditions are introduced independently. However, the pairwise constraints and the local property may contain conflicting information. In this paper, we utilize the conflicting information to improve the local property. Instead of characterizing the local property by all neighbors, samples which do not appear in the cannot-link constraints can be used. A performance indicator, called neighborhood-cannot-link (NC) coefficient, is proposed to measure the improvement of the local property. We use the improved local property and the pairwise constraints to perform semi-supervised constraint scores algorithm. Experiments on several real world data sets demonstrate the effectiveness of the methods.

System Simulation Modeling for Near-field Millimeter Wave Synthetic Aperture Imaging Radiometer

Jianfei Chen,Yuehua Li,Jianqiao Wang,Yuanjiang Li 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.6

Due to the fact that theoretical analysis and instrument construction for antenna array of synthetic aperture imaging radiometer (SAIR) are both complicated, and designers usually hope to predict the imaging effect and analysis the influence of relevant parameters of SAIR before the system design. The imaging simulation is a very useful method in the system design of SAIR. This paper is devoted to establishing an accurate imaging model for simulating the process of near-field millimeter wave SAIR. In this model, the target radiation signals and received signals of receivers are represented by the accurate signals in the time domain, which improves the efficiency of this simulation model significantly. The visibility function is collected by the cross-correlation between I/Q signals of the antenna pairs just as the imaging process of the practical SAIR. Some characteristics (such as the coherence between targets, the resolution and no-aliasing FOV of SAIR and so on) are verified by the corresponding 1D and 2D simulation experiments, and the effectiveness of this imaging model is also tested by these simulation experiments. The simulation experiment results show that this model is an efficient, accurate imaging simulation model, and can be employed in the system design of near-field millimeter wave SAIR.

An Algorithm of De-noising of Millimeter Wave Radar Signal based on Stochastic Resonance

Han Lingyun,Li Yuehua 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.6

Millimeter wave radar echo signals often contain noise and clutter because of rain and fog’s influence on the performance of which, and its performance drop greatly. In recent years, bi-stable stochastic resonance and multi-scale wavelet decomposition theory received great attentions in the field of signal de-noising. This paper proposed a novel mechanism of stochastic resonance which is induced by multi-scale noise for weak signal detection in millimeter wave radar signal. Firstly by multi-scale wavelet decomposition, input signal which is in heavy background noise was decomposed to several signals with different frequencies. After that they were induced by contraction factors of each noise scale, and then were as the input signal of bi-stable system. Simulations of different parameters show that under suitable contraction factors, SNR of output signal can be improved greatly.