二维主元分析法在心肌梗死心电信号检测中的应用

利用基于联合能量百分比搜索的二维主元分析法对12导高分辨率心电信号（ECG）进行全局特征提取和分类检测研究。所用数据取自PTB诊断数据库,包括健康状态ECG,早期心肌梗死（MI）ECG,急性期MI ECG,恢复期 MI ECG。结果表明,所用的方法能有效地融合12导ECG信号及其高频分量中的细微结构信息,与常规主元分析法相比,其平均分类检测精度可提高10.43%,与常规二维主元分析法相比,能得到维数更低的特征表示,并可获得99.46 %的平均分类检测精度。     

MALDI mass spectrometric imaging of cardiac tissue following myocardial infarction in a rat coronary artery ligation model

Although acute myocardial infarction (MI) is consistently among the top causes of death in the United States, the spatial distribution of lipids and metabolites following MI remains to be elucidated. This work presents the investigation of an in vivo rat model of MI using mass spectrometric imaging (MSI) and multivariate data analysis. MSI was conducted on cardiac tissue following a 24-h left anterior descending coronary artery ligation to analyze multiple compound classes. First, the spatial distribution of a small metabolite, creatine, was used to identify areas of infarcted myocardium. Second, multivariate data analysis and tandem mass spectrometry were used to identify phospholipid (PL) markers of MI. A number of lysophospholipids demonstrated increased ion signal in areas of infarction. In contrast, select intact PLs demonstrated decreased ion signal in the area of infarction. The complementary nature of these two lipid classes suggests increased activity of phospholipase A(2), an enzyme that has been implicated in coronary heart disease and inflammation.     

Smart CardioWatch System for Patients with Cardiovascular Diseases Who Live Alone

The widespread use of smartwatches has increased their specific and complementary activities in the health sector for patient’s prognosis. In this study, we propose a framework referred to as smart forecasting CardioWatch (SCW) to measure the heart-rate variation (HRV) for patients with myocardial infarction (MI) who live alone or are outside their homes. In this study, HRV is used as a vital alarming sign for patients with MI. The performance of the proposed framework is measured using machine learning and deep learning techniques, namely, support vector machine, logistic regression, and decision-tree classification techniques. The results indicated that the analysis of heart rate can help health services that are located remotely from the patient to render timely emergency health care. Further, taking more cardiac parameters into account can lead to more accurate results. On the basis of our findings, we recommend the development of health-related software to aid researchers to develop frameworks, such as SCW, for effective provision of emergency health.     

露天矿爆破时砖混结构房屋振动响应的模态参数识别与爆破减振方法

为确保矿区周围房屋安全,采集矿区周围单层砖混结构房屋的爆破振动信号,根据运筹模态分析（operational modal analysis,OMA）相关理论,运用希尔伯特黄变换（Hilbert Huang transform,HHT）和小波包分解的方法对爆破地震波信号进行了分析。确定了单层砖混结构房屋地基与墙壁爆破振动信号的各阶固有频率,得到了不同振动方向各阶的固有模态函数（intrinsic mode function,IMF）贡献率。结果表明:地基与墙壁的IMF贡献率存在明显差异;地基高频序列IMF贡献率较高,墙壁的低频序列IMF贡献率较高。对墙壁测点数据进行分析可知:随着墙壁高度的增加,低频段,低频能量逐渐减小;高频段,高频能量逐渐增加。改变装药结构与间隔起爆时间,可使爆破地震波出现峰谷叠加现象,从而减小爆破振动效应,降低质点的振速。     

Modulation instability dynamics of coupling pulses with different powers in nonlinear fibers

In the paper, the modulation instability (MI) of the pulses with different powers is studied based on the modified coupled nonlinear Schrödinger equations in nonlinear fiber. By analyzing MI gain spectrum with different power ratios, it shows that the increase of power ratio leads to the diminution in the range of strongly unstable frequency and the decrease in the gain of MI spectra. With a fixed power ratio, the increased relaxation time is equally suppressing overall MI.     

舰船地声信号的谱能量分析及相关性研究

分析浅水环境下舰船地震波信号和水声信号的功率谱比值（SAR）与频率的关系,以及它们的能量在频率上的差异。利用频域相关系数,分析两种信号的相关性。结果表明,在地震波信号很强的低频带（5—15Hz）和声信号很强的高频带（35—50Hz）,SAR值和相关系数都很高,而在两种信号能量强弱的过渡频带内SAR值和相关系数偏低。     

液态CO2相变破岩振动信号能量分布特征

针对液态CO_2相变破岩,设计振动信号监测试验,基于小波包变换分析振动信号能量分布规律。结果表明:液态CO2相变破岩振动信号主振频带与振动信号方向及传播距离相关性较小,基本位于0~4 Hz子频带,但主振频率对应能量分布百分比随着传播距离增加逐渐降低。随传播距离的增加,垂向振动信号高频段能量百分比逐渐增加,低频段能量百分比逐渐降低,且在中高频附近出现与主振频带对应能量百分比逐渐接近的"子中心"频带。同一测点不同方向频率能量分布百分比在0~100 Hz频带存在一定差异,但在其他频域内基本一致。     

Myocardial‐Infarction‐Responsive Smart Hydrogels Targeting Matrix Metalloproteinase for On‐Demand Growth Factor Delivery

Although in situ restoration of blood supply to the infarction region and attenuating pre‐existing extracellular matrix degradation remain potential therapeutic approaches for myocardial infarction (MI), local delivery of therapeutics has been limited by low accumulation (inefficacy) and unnecessary diffusion (toxicity). Here, a dual functional MI‐responsive hydrogel is fabricated for on‐demand drug delivery to promote angiogenesis and inhibit cardiac remodeling by targeting upregulated matrix metalloproteinase‐2/9 (MMP‐2/9) after MI. A glutathione (GSH)‐modified collagen hydrogel (collagen‐GSH) is prepared by conjugating collagen amine groups with GSH sulfhydryl groups and the recombinant protein GST‐TIMP‐bFGF (bFGF: basic fibroblast growth factor) by fusing bFGF with glutathione‐S‐transferase (GST) and MMP‐2/9 cleavable peptide PLGLAG (TIMP). Specific binding between GST and GSH significantly improves the amount of GST‐TIMP‐bFGF loaded in collagen‐GSH hydrogel. The TIMP peptide enclosed between GST and bFGF responds to MMPs for on‐demand release during MI. Additionally, the TIMP peptide is a competitive substrate of MMPs that inhibits the excessive degradation of cardiac matrix by MMPs after MI. GST‐TIMP‐bFGF/collagen‐GSH hydrogels promote the recovery of MI rats by enhancing vascularization and ameliorating myocardium remodeling. The results suggest that on‐demand growth factor delivery by synchronously controlling binding and responsive release to promote angiogenesis and attenuate cardiac remodeling might be promising for the treatment of ischemic heart disease.     

Implementing emergency department observation units within a multihospital network

BACKGROUND: The proportion of emergency department (ED) chest pain patients who undergo an extended "rule out MI (myocardial infarction)" evaluation beyond the ED determines both the quality and cost of patient care. The higher an organization's rate of such evaluations, the lower the average miss rate for MI. Five of the 13 hospitals in the Voluntary Hospital Association Northeast multihospital network implemented ED observation units by June 1997 for outpatient rule out MI evaluations. RESULTS: Compared with historical and case controls, the five hospitals with ED observation units had a higher observation rate (16% versus 0% [p < .001] and 2% [p < .001]) and a higher rule out MI evaluation rate (61% versus 46% [p < .01] and 45% [p < .01]), without a significantly higher admission rate (47% versus 46% and 45%). For the three hospitals with observation units that collected charge data during 1997 on a consecutive series of chest pain patients who had negative rule out MI evaluations, charges for patient services were lower for patients evaluated in the ED observation unit ($2,214.80 +/- $80.40) than in the hospital ($5,464.30 +/- $393.60). CONCLUSIONS: ED observation units represent a cost-effective restructuring of the diagnostic approach to patients with acute chest pain. In an improvement of quality of patient care, a larger proportion of ED chest pain patients receive an extended evaluation than is possible with hospital admission as the only ED disposition option.     

Modeling and phantom studies of ultrasonic wall shear rate measurements using coded pulse excitation

Wall shear rate (WSR) is the derivative of blood velocity with respect to vessel radius at the endothelial cell (EC) surface. The product of WSR and blood viscosity is the wall shear stress (WSS) that has been identified as an important factor for atherosclerosis development. High echo signal-to-noise ratio (eSNR) and high spatial resolution are crucial for minimizing the errors in WSR estimates. By transmitting coded pulses with time-bandwidth product greater than one, high eSNR from weak blood scatter can be achieved without increasing instantaneous power or sacrificing spatial resolution. This paper summarizes a series of measurements in a straight tube (5-mm diameter), constant velocity flow phantom using a 10 MHz transducer (60% bandwidth, f/1.5) imaged with a 72 degrees Doppler angle, 125 MHz sampling frequency and 1 kHz pulse repetition frequency. Measurements were made using a frequency-modulated (FM) code, phase-modulated (PM) codes, and uncoded broadband and narrow band pulse transmissions. Both simulation and experimental results show that coded-pulse excitation increases accuracy and precision in WSR estimation for laminar flow over a broad range of peak velocity values when compared to standard pulsing techniques in noise-limited conditions (eSNR < 30 dB). The code sequence and its length are selected to balance range lobe suppression with eSNR and echo coherence enhancements to minimize WSR errors. In our study, the combination of an eight bit Optimal coded pulse with a Wiener compression filter yielded the highest WSR estimation performance.     

ECG steganography based on tunable Q‐factor wavelet transform and singular value decomposition

The article presents a novel ECG steganography scheme based on the tunable Q‐factor wavelet transformation (TQWT) and also singular value decomposition (SVD) techniques that ensure better safety and confidentiality of patient information. Initial parameters such as Q, r, and J are used to decompose the cover signal into individual frequency sub‐bands with the tunable Q‐factor wavelet transform (TQWT). The singular value decomposition (SVD) technique is used to further decompose high‐frequency sub‐band coefficients into singular values. The watermark information is then embedded with high‐frequency sub‐band coefficients by involving the quantization process. The performance of this proposed system is successfully evaluated by considering various metrics, such as peak signal to noise ratio (PSNR), structural similarity index (SSIM), percentage residual difference (PRD), and bit error rate (BER). The simulation results of the proposed scheme are observed to be better than other traditional algorithms.     

Sustained release of a p38 inhibitor from non-inflammatory microspheres inhibits cardiac dysfunction

Cardiac dysfunction following acute myocardial infarction is a major cause of death in the world and there is a compelling need for new therapeutic strategies. In this report we demonstrate that a direct cardiac injection of drug-loaded microparticles, formulated from the polymer poly(cyclohexane-1,4-diylacetone dimethylene ketal) (PCADK), improves cardiac function following myocardial infarction. Drug-delivery vehicles have great potential to improve the treatment of cardiac dysfunction by sustaining high concentrations of therapeutics within the damaged myocardium. PCADK is unique among currently used polymers in drug delivery in that its hydrolysis generates neutral degradation products. We show here that PCADK causes minimal tissue inflammatory response, thus enabling PCADK for the treatment of inflammatory diseases, such as cardiac dysfunction. PCADK holds great promise for treating myocardial infarction and other inflammatory diseases given its neutral, biocompatible degradation products and its ability to deliver a wide range of therapeutics.     

Cardiovascular conditions in hemodialysis patients may be worsened by extensive interdialytic weight gain

The risk of death is increased for hemodialysis (HD) patients compared with age-matched healthy subjects, the main reason for this being cardiovascular conditions. This prospective study investigated whether the burden of interdialytic weight gain (IDWG) was of importance for cardiovascular end points and survival. A total of 97 HD patients were studied. The end points included death (reasons given), acute myocardial infarction, or coronary vascular intervention. The extent of ultrafiltration was measured at predefined follow-up points. The IDWG was calculated as ultrafiltration/body weight given in weight%. The burden of IDWG was analyzed. End points occurred in 77 (79%) of the patients during the 5-year study period. The extent of IDWG was higher in those with end points due to cardiovascular reasons (3.77 weight% vs. 3.19 P<0.001), cardiac reasons (P<0.001), congestive heart failure (P<0.01), aortic aneurysm, and intracerebral bleeding (P<0.024). To reduce the risk for cardiovascular events, it is important to avoid too extensive IDWG in HD patients.     

三自由度半正定系统随机振动仿真与试验研究

目的研究三自由度半正定系统在随机振动条件下的加速度动态响应以及加速度功率谱密度。方法以运输包装中常见的三自由度半正定系统为原型,建立了三自由度半正定系统的质量-弹簧-阻尼系统。依据美国ASTM-D4728随机振动标准,利用Matlab/Simulink仿真平台,建立仿真模型,并输入模型参数,得到了三自由度半正定系统随机振动下的动态响应。基于相同试验标准进行试验,对比分析试验结果与仿真结果的差异。结果在低频段内(小于80 Hz),Simulink仿真模拟随机振动的加速度功率谱密度值与随机振动试验的加速度功率谱密度值的相关性系数达到0.983,加速度功率谱密度值最大处仅相差8.8%。在高频段内(大于80 Hz),Simulink仿真模拟随机振动的加速度功率谱密度值与随机振动试验的加速度功率谱密度值的相关性系数只达到0.745,加速度功率谱密度值最大处相差13.1%。结论利用Matlab/Simulink仿真平台分析包装系统的低频随机振动是一种简单可行的方法,一定程度上可以作为随机振动试验的代替手段。     

Regional ejection fraction and regional area strain for left ventricular function assessment in male patients after first-time myocardial infarction

In this work, we present a method to assess left ventricle (LV) regional function from cardiac magnetic resonance (CMR) imaging based on the regional ejection fraction (REF) and regional area strain (RAS). CMR scans were performed for 30 patients after first-time myocardial infarction (MI) and nine age- and sex-matched healthy volunteers. The CMR images were processed to reconstruct three-dimensional LV geometry, and the REF and RAS in a 16-segment model were computed using our proposed methodology. The method of computing the REF was tested and shown to be robust against variation in user input. Furthermore, analysis of data was feasible in all patients and healthy volunteers without any exclusions. The REF correlated well with the RAS in a nonlinear manner (quadratic fit—R² = 0.88). In patients after first-time MI, the REF and RAS were significantly reduced across all 16 segments (REF: p < 0.05; RAS: p < 0.01). Moreover, the REF and RAS significantly decreased with the extent of transmural scar obtained from late gadolinium-enhanced CMR images. In addition, we show that the REF and RAS can be used to identify regions with compromised function in the patients with preserved global ejection fraction with reasonable accuracy (more than 78%). These preliminary results confirmed the validity of our approach for accurate analysis of LV regional function. Our approach potentially offers physicians new insights into the local characteristics of the myocardial mechanics after a MI.     

Noninvasive evaluation of local myocardial thickening and itscolor-coded imaging

For the noninvasive diagnosis of heart disease based on the acoustic characteristics of the heart muscle, we have developed a new method for accurately tracking the movement of the heart wall. By this method, a velocity signal of the heart wall with a small amplitude of less than 10 μm on the motion resulting from a heartbeat with large amplitude of 10 mm can be successfully detected with sufficient reproducibility in the frequency range up to several hundred Hertz continuously for periods of about 10 heartbeats. In this paper, the method is applied to multiple points preset in the left ventricular (LV) wall along the ultrasonic beam so that the spatial (depth) distributions of the velocity at these points are simultaneously obtained. The motion of the heart wall is divided into the following two components: parallel global motion of the heart wall and the change in myocardial layer thickening at each depth across the LV wall during myocardial contraction/relaxation. The latter component is superimposed on the M (motion) mode image using a color code to map contraction as red and expansion as blue. By preliminary human studies, the principle of the method proposed in this paper is verified and the frequency band of the components generated by thickening and/or thinning in the myocardium is identified. This new approach offers potential for research on noninvasive acoustical diagnosis of myocardial local motility, that is, the myocardial layer function at each depth in the ventricular wall     

Propagation of spontaneously actuated pulsive vibration in human heart wall and in vivo viscoelasticity estimation

Though myocardial viscoelasticity is essential in the evaluation of heart diastolic properties, it has never been noninvasively measured in vivo. By the ultrasonic measurement of the myocardial motion, we have already found that some pulsive waves are spontaneously excited by aortic-valve closure (AVC) at end-systole (T0). These waves may serve as an ideal source of the intrinsic heart sound caused by AVC. In this study, using a sparse sector scan, in which the beam directions are restricted to about 16, the pulsive waves were measured almost simultaneously at about 160 points set along the heart wall at a sufficiently high frame rate. The consecutive spatial phase distributions, obtained by the Fourier transform of the measured waves, clearly revealed wave propagation along the heart wall for the first time. The propagation time of the wave along the heart wall is very small (namely, several milliseconds) and cannot be measured by conventional equipment. Based on this phenomenon, we developed a means to measure the myocardial viscoelasticity in vivo. In this measurement, the phase velocity of the wave is determined for each frequency component. By comparing the dispersion of the phase velocity with the theoretical one of the Lamb wave (the plate flexural wave), which propagates along the viscoelastic plate (heart wall) immersed in blood, the instantaneous viscoelasticity is determined noninvasively. This is the first report of such noninvasive determination. In in vivo experiments applied to five healthy subjects, propagation of the pulsive wave was clearly visible in all subjects. For the 60-Hz component, the typical propagation speed rapidly decreased from 5 m/s just before the time of AVC (t = T0 - 8 ms) to 3 m/s at t = T0 + 10 ms. In the experiments, it was possible to determine the viscosity more precisely than the elasticity. The typical value of elasticity was about 24-30 kPa and did not change around the time of AVC. The typical transient values of viscosity decreased rapidly from 400 Pa x s at t = T0 - 8 ms to 70 Pa x s at t = T0 + 10 ms. The measured shear elasticity and viscosity in this study are comparable to those obtained for the human tissues using audio frequency in in vitro experiments reported in the literature.     

电子雷管和导爆管雷管起爆的振动信号时频特性对比

为了对比电子雷管和导爆管雷管两种起爆方式的爆破振动信号,开展了某露天采石矿两种雷管起爆的深孔爆破振动测试。基于小波分析方法和Matlab程序小波工具箱,对爆破振动信号按照频率划分为10个频带,分析各频带能量和峰值质点速度(peak partide velocity,PPV)的分布特征及随爆心距的变化。结果表明:采用电子雷管和导爆管雷管起爆时,90%的爆破振动能量分布在2~6频带（9.77~312.50 Hz）和2~7频带（9.77~625.00 Hz）,且PPV分布在3~4频带（19.53~78.13 Hz）和4~5频带（39.06~126.25 Hz）,即电子雷管起爆的爆破地震波能量和PPV均向低频带分布,且信号的PPV更小;中、高频带能量大小与段药量成正比,与爆心距成反比;各频带能量占比和PPV大小是反映爆破振动强度的重要指标,采用电子雷管能有效地减少爆破振动。     

Unlockable Nanocomplexes with Self‐Accelerating Nucleic Acid Release for Effective Staged Gene Therapy of Cardiovascular Diseases

Nucleic acid (NA)‐based therapy is proposed to address serious diseases such as cardiovascular diseases (CVDs). Powerful NA delivery vehicles are essential for effective gene therapy. Herein, a novel type of delivery vehicle, an unlockable core–shell nanocomplex (Hep@PGEA) with self‐accelerating NA release, is structurally designed. Hep@PGEA is composed of disulfide‐bridged heparin nanoparticle (HepNP) core and low‐toxicity PGEA cationic shell. In comparison with NA, heparin, a negatively charged polysaccharide macromolecule, exhibits stronger interactions with cationic species. Upon the breakdown of redox‐responsive HepNP cores, unlocked heparin would interact with the outer cationic shells and replace the condensed NA to facilitate NA release. Such unique Hep@PGEA is successfully explored for effective miRNA–pDNA staged gene therapy of myocardial infarction (MI), one of the most serious CVDs. With the progression of MI, glutathione amounts in heart tissues increase. MiR‐499 (for the inhibition of cardiomyocyte apoptosis) and plasmid encoding vascular endothelial growth factor (for the promotion of angiogenesis) are sequentially delivered for systemic treatment of MI. Such treatment produces impressive results in restoring heart function and suppressing cardiac hypertrophy. Due to the wide existence of redox agents in cells, the proposed unlockable delivery nanovehicle and staged therapy strategy can provide new methods to effectively treat different serious diseases.     

基于变分模态分解与深度信念网络的运动想象分类识别研究

传统人工确定最优时段及最优频段的方法会造成信息遗漏进而导致运动想象识别率的降低, 因此基于脑电信号的运动想象分类研究成为了脑-机接口研究领域的难点问题。针对该问题,变分模态分解和深度信念网络被应用于运动想象分类。对脑电信号进行变分模态分解得到窄带分量,利用希尔伯特变换提取边际谱、特征频带下的瞬时能谱以及时-频联合特征; 特征融合后采用深度信念网络对高维特征降维并实现运动想象模式的识别, 避免了人工确定想象最优时段及最优频段造成的信息遗漏。实验结果表明,利用变分模态分解与深度信念网络自动提取最优时段及最优频段特征的方法有效提升了运动想象识别率。