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1.
目的了解冠心病患者糖代谢异常的情况。方法分析2009年1-9月,我科诊断冠心病的住院患者315例,除住院前已诊断为糖尿病者外,其余均接受口服葡萄糖耐量试验(OGTT)了解糖代谢情况;糖尿病患者接受空腹、餐后2h血糖检测及全血糖化血红蛋白检测。结果冠心病合并糖代谢异常比例为84.8%,糖尿病患病率50.5%,IFG或IGT患病率34.3%。结论冠心病人中大部分合并糖代谢异常,进行OGTT试验有利于早期发现冠心病合并糖代谢异常,以进行早期干预。  相似文献   

2.
The authors present a survey of modern nonlinear CAD (computer-aided design) techniques as applied to the specific field of microwave circuits. A number of fundamental aspects of the nonlinear CAD problem, including simulation, optimization, intermodulation, frequency conversion, stability, and noise, are addressed and developed. For each one it is shown that either well-established CAD solutions are available, or at least a solution approach suitable for implementation in a general-purpose CAD environment can be outlined. Also, the discussion shows that the various subjects are not just separate items, but rather can be chained in a strictly logical sequence. Finally, an elementary treatment of vector processing is given, to show that supercomputers can handle the involved large-size numerical problems efficiently  相似文献   

3.
The first-order nonlinear analysis of IMPATT diodes is performed and a model is obtained in which the nonlinear effects due to avalanche are separated from the activity and transit-time effects. Such a mildly nonlinear model is suitable for CAD applications. The determination of the model parameters by means of small signal measurements is outlined, and the applicability of the proposed model is demonstrated on real devices.  相似文献   

4.
Sample entropy, a nonlinear signal processing approach, was used as a measure of signal complexity to evaluate the cyclic behavior of heart rate variability (HRV) in obstructive sleep apnea syndrome (OSAS). In a group of 10 normal and 25 OSA subjects, the sample entropy measure showed that normal subjects have significantly more complex HRV pattern than the OSA subjects (p < 0.005). When compared with spectral analysis in a minute-by-minute classification, sample entropy had an accuracy of 70.3% (69.5% sensitivity, 70.8% specificity) while the spectral analysis had an accuracy of 70.4% (71.3% sensitivity, 69.9% specificity). The combination of the two methods improved the accuracy to 72.9% (72.2% sensitivity, 73.3% specificity). The sample entropy approach does not show major improvement over the existing methods. In fact, its accuracy in detecting sleep apnea is relatively low in the well classified data of the physionet. Its main achievement however, is the simplicity of computation. Sample entropy and other nonlinear methods might be useful tools to detect apnea episodes during sleep.  相似文献   

5.
The diagnosis of coronary artery disease (CAD) is an important task in the management of cardiology patients. Recently, the use of pharmacological stress testing has become available as an alternative to exercise stress testing (ETT). A new system (device-drug combination) was developed specifically for the diagnosis of coronary artery disease. The system uses a novel catecholamine, arbutamine, which is infused intravenously to increase heart rate (HR) and cardiac contractility in order to evoke signs of ischemia. The development of a closed-loop control algorithm for the delivery of this drug and a pharmacodynamic (PD) model representing the HR response to arbutamine infusions are presented. Model parameters are estimated from clinical data on normal volunteers and patients. Based on this mathematical model, a rule-based control algorithm is designed. The structure of the control algorithm is discussed and testing of the algorithm based on simulations and animal and human trials are summarized. Results from clinical trials shows that the algorithm controls the HR increase according to a selected trajectory. The automated delivery of the drug can provide the cardiologist with an efficient, effective, and safe method for administering a pharmacological stress test  相似文献   

6.
Coronary artery disease (CAD) causes oscillations in peripheral arteries. Oscillations of the walls of the brachial arteries of 51 patients were recorded [together with the electrocardiogram (ECG)] by an accelerometer at different cuff pressures. By analyzing the energy of the oscillations in the 30-250 Hz band, 16 of 22 patients with CAD and 26 of 29 non-CAD subjects were classified correctly, independent of the ECG, and with no effect of heart murmurs.  相似文献   

7.
Analysis of respiratory muscles activity is an effective technique for the study of pulmonary diseases such as obstructive sleep apnea syndrome (OSAS). Respiratory diseases, especially those associated with changes in the mechanical properties of the respiratory apparatus, are often associated with disruptions of the normally highly coordinated contractions of respiratory muscles. Due to the complexity of the respiratory control, the assessment of OSAS related dysfunctions by linear methods are not sufficient. Therefore, the objective of this study was the detection of diagnostically relevant nonlinear complex respiratory mechanisms. Two aims of this work were: (1) to assess coordination of respiratory muscles contractions through evaluation of interactions between respiratory signals and myographic signals through nonlinear analysis by means of cross mutual information function (CMIF); (2) to differentiate between functioning of respiratory muscles in patients with OSAS and in normal subjects. Electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from three respiratory muscles: genioglossus, sternomastoid and diaphragm. Inspiratory pressure and flow were also acquired. All signals were measured in eight patients with OSAS and eight healthy subjects during an increased respiratory effort while awake. Several variables were defined and calculated from CMIF in order to describe correlation between signals. The results indicate different nonlinear couplings of respiratory muscles in both populations. This effect is progressively more evident at higher levels of respiratory effort.  相似文献   

8.
目的了解急性冠脉综合征患者冠脉CTA、冠脉造影、OCT的表现。方法急性冠脉综合征患者3例,在行冠脉造影前均行64排CT(Somatom Definition)冠脉CTA检查,明确罪犯病变;常规冠状动脉造影后行OCT检查(Lightlab),分别分析冠脉CT、冠脉造影和OCT影像学结果。结果冠脉CTA均提示为软斑块,斑块最低CT值均小于100Hu,1例伴有轻度钙化,斑块负荷较重,均呈正性重构;OCT示2例有极薄的纤维帽(分别为50μm和40μm),纤维帽后有大的脂核。结论冠脉CTA对于血管壁较宏观的观察较有优势,冠脉造影可以动态观察血管的情况,OCT可细致观察血管壁、斑块和血栓。  相似文献   

9.
This paper presents a comprehensive study on the effective utilization of large-signal measurement data in the nonlinear computer-aided design (CAD) process. To achieve this goal two distinctive, yet mutually complementary, approaches have been integrated. Measured nonlinear data was, in the first instance, directly integrated into a nonlinear CAD simulator, and in the second instance, utilized for a direct extraction of behavioral model parameters. The formulation of the developed model is based on the polyharmonic distortion approach. The combination of both the direct utilization of nonlinear data and the subsequent model generation into an integrated nonlinear design procedure offers rapid, yet reliable, deployment of the CAD-based design environment for complex large-signal simulations.   相似文献   

10.
In order to use SiC devices in CAD nonlinear circuits, a nonlinear model of 4H-SiC MESFET has been obtained using a technique based on pulsed I(V) characteristics and pulsed S-parameter measurements. The nonlinear I-V drain-source current was represented using a table-based model which was implemented in a harmonic balance simulator. Its accuracy is shown by a comparison with active load-pull measurements  相似文献   

11.
FMCW毫米波雷达中频滤波器的研究   总被引:6,自引:0,他引:6  
针对寄生调幅是影响FMCW毫米波雷达作用距离的重要因素,讨论了中频滤波器在FMCW毫米波雷达系统中的作用,研究了滤波器性能与雷达作用距离的关系,根据分析表明,对中频滤滤器进行了CAD优化,提高了雷达的作用距离。  相似文献   

12.
本文概述了1992年10月在北京举行的1992国际激光与光电子会议。  相似文献   

13.
Arterial diameter estimation from X-ray ciné angiograms is important for quantifying coronary artery disease (CAD) and for evaluating therapy. However, diameter measurement in vessel cross sections < or =1.0 mm is associated with large measurement errors. We present a novel diameter estimator which reduces both magnitude and variability of measurement error. We use a parametric nonlinear imaging model for X-ray ciné angiography and estimate unknown model parameters directly from the image data. Our technique allows us to exploit additional diameter information contained within the intensity profile amplitude, a feature which is overlooked by existing methods. This method uses a two-step procedure: the first step estimates the imaging model parameters directly from the angiographic frame and the second step uses these measurements to estimate the diameter of vessels in the same image. In Monte-Carlo simulation over a range of imaging conditions, our approach consistently produced lower estimation error and variability than conventional methods. With actual X-ray images, our estimator is also better than existing methods for the diameters examined (0.4-4.0 mm). These improvements are most significant in the range of narrow vessel widths associated with severe coronary artery disease.  相似文献   

14.
A fuzzy rule-based decision support system (DSS) is presented for the diagnosis of coronary artery disease (CAD). The system is automatically generated from an initial annotated dataset, using a four stage methodology: 1) induction of a decision tree from the data; 2) extraction of a set of rules from the decision tree, in disjunctive normal form and formulation of a crisp model; 3) transformation of the crisp set of rules into a fuzzy model; and 4) optimization of the parameters of the fuzzy model. The dataset used for the DSS generation and evaluation consists of 199 subjects, each one characterized by 19 features, including demographic and history data, as well as laboratory examinations. Tenfold cross validation is employed, and the average sensitivity and specificity obtained is 62% and 54%, respectively, using the set of rules extracted from the decision tree (first and second stages), while the average sensitivity and specificity increase to 80% and 65%, respectively, when the fuzzification and optimization stages are used. The system offers several advantages since it is automatically generated, it provides CAD diagnosis based on easily and noninvasively acquired features, and is able to provide interpretation for the decisions made.  相似文献   

15.
The harmonic balance technique from nonlinear simulation is extended to nonlinear adjoint sensitivity analysis. This provides an efficient tool for the otherwise expensive but essential gradient calculations in design optimization. The hierarchical approach widely used for circuit simulation, is generalized to sensitivity analysis and to computing responses in any subnetwork at any level of the hierarchy. Important aspects of frequency-domain circuit computer-aided design (CAD) such as simulation and sensitivity analysis, linear and nonlinear circuits, hierarchical and nonhierarchical approaches, voltage and current excitations, or open- and short-circuit terminations are unified in this general framework. The theory provides a basis for the next generation of microwave CAD software. It takes advantage of mature techniques such as syntax-oriented hierarchical analysis, optimization, and yield-driven design to handle nonlinear as well as linear circuits. The sensitivity analysis approach has been verified by a MESFET mixer example, exhibiting a 90% saving of CPU time over the prevailing perturbation method  相似文献   

16.
频率锁定是实现毫米波合成式扫频信号源的重要因素,由于返波管振荡器非线性时整机的频率锁定有直接且显著的影响,因此合理地消除返波管振荡器的非线性影响,对实现信号源的功能和关键指标起着极其重要的作用。该文从分析返波管振荡器的非线性产生机理入手,讨论了非线性补偿关键技术,并设计了补偿电路,在实际应用中进行了验证,取得了良好的效果。  相似文献   

17.
Noncommunicable diseases are the main reason to the rise of diseases incidence in the developed world. The management and prevention of these diseases can be done by controlling the behavioral and biological risk factors which are related to them. ChronicPrediction is an intelligent system for noncommunicable diseases care which determines in real time the impact on risk factors due to actions taken by users. Based on impact information, the system presents on users’ smartphones strategic messages to help in their treatment. ChronicPrediction applies Bayesian Networks (BNs) which use risk factors for mapping the causes of noncommunicable diseases worsening. The support to multiple chronic diseases and the integrated use of multiple BNs based on risk factors are the main contributions of this work and differentiate the proposed system from related work. We have built a functional prototype that allowed us to conduct two experiments. The first one successfully tested the main functionalities provided by ChronicPrediction to support BNs based on risk factors and the sending of messages to users’ smartphones. The evaluation involved the building of a BN for predicting coronary artery disease made with real world data obtained in a prospective cohort study. The study involved 302 patients from a hospital localized in southern Brazil. The second experiment assessed the ChronicPrediction support to multiple BNs at same time. The test involved the previous BN and another from a thirty part research work to map risk factors of diabetes. The results were encouraging and show potential for implementing ChronicPrediction in real-life situations.  相似文献   

18.
In little more than 10 years computer-aided design (CAD) of microwave circuits has moved from dumb terminals on mainframe computers to PCs, and now to powerful RISC workstations. Commercial CAD software now integrates the various stages of microwave circuit design: schematic capture, simulation and layout. This paper reviews the different CAD packages that are available for microwave circuit design. The basic principles employed in the modelling of microstrip circuits are introduced and the reasons for the extensive use of frequency-domain simulations are explored. The developments in nonlinear, electromagnetic and system-level simulation methods are described  相似文献   

19.
介绍一种毫米波E面电路双工器的简化CAD方法,包括E-T分支的等效电路,双工器散射矩阵的分析和优化.经过在V波段的实测,表明该方法的设计结果与设计指标是相吻合的.  相似文献   

20.
Three approaches are described for investigation of human somatosensory evoked responses in normal subjects and in multiple sclerosis patients. To median-nerve stimulation, the cortical evoked response (SER) reveals components whose shapes and latencies may be altered as a consequence of the disease. The use of periodic trains of stimuli (SERT) demonstrates that the oscillatory response of the nervous system deteriorates with advancing disease. Finally, the use of functional power series to characterize the somatosensory modality shows that responses to temporally interactive stimuli are nonlinear, decrease with increasing rate, and degenerate in the advanced state of the disease.  相似文献   

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