Functional and metabolic evaluation of the hypertrophied heart using MRI and31P-MRS

4. Conclusions Diastolic LV function and myocardial HEP metabolism are impaired only when LVH is caused by permanent pressure or volume overload, and not by a temporary increase in cardiac workload during part of the day as in elite athletes. Therefore, training-induced and pressure/volume-overload-induced LVH seem to represent different phenotypes of LVH, possibly related to genetic reprogramming which only occurs during permanent cardiac overload [17]. Moreover, there is an association between impaired LV diastolic function and altered myocardial HEP metabolism in patients with hypertension and in patients with aortic valve disease. Finally we did not find a correlation between myocardial HEP metabolism and LV mass in any of the groups studied. The latter indicates that LVH should be regarded as an epiphenomenon to cardiac overload, and not as a primary factor causing abnormal HEP metabolism.     

Evaluation of myocardial function and perfusion in ischemic heart disease

Ischemic heart disease is the most frequently encountered cardiac disease. Magnetic resonance imaging (MRI) can be used to investigate several facets of this disease. A number of studies over the past several years have shown the capability of cine MRI for quantifying regional myocardial function and for identifying abnormalities of regional myocardial wall thickening in the basal or vasodilated states due to ischemia. Contrast-enhanced inversion recovery fast gradient echo and echo-planar imaging have been applied for monitoring the first passage of contrast media through the myocardium. This technique has depicted regional perfusion deficits in the basal state or in the vasodilated states induced by vasodilators. Recent studies have also disclosed the feasibility of using MR techniques for displaying the morphology of the major coronary arteries and for measuring blood flow velocity in the coronary arteries and coronary bypass grafts. Thus, MRI has the capability for evaluation of morphology and flow in the coronary arteries and for assessment of function and perfusion of the myocardium.     

Functional MR with use of FLASH sequences in the evaluation of the phono-articulatory tract

The aims of this study are to determine visualization of normal phonation structures with the use of MR fast sequences and anatomical reference indices which can be used in evaluating upper resonator pathologies. A total of 12 normal subjects were studied, a 1 T system, a volumetric receiving head and neck coil and FLASH sequences for one sagittal and two coronal scans. Each subject was instructed to take a deep breath and then to produce the vowel sounds for the entire duration of the scan. The movement of the following anatomical structures were considered: lips, tongue, soft palate, pharynx and epiglottis. For each subject sagittal scans were used to measure the minimal palate-tongue distance (p−t), the minimal anterio-posterior diameter of the mesopharynx (mp), and the epiglottis excursion angle (ep) with respect to the plane determined by the false vocal cords. Our results were compared with a diagrammed representation of tongue movements (vocal trapezium). This study underlines the validity of MR imaging techniques in the study of the phono-articulatory tract. because MR provided good detail of the phono-articulatory structures enabling an overall functional evaluation. MR would appear useful in evaluating defects in the velum and palate, in staging of oropharyngeal neoplasms and in surgical reconstructions of the tongue.     

功能材料及其发展

电、磁等特性的功能材料是电工电子技术发展的重要组成部分,介绍了当今相关材料的现状和展望。     

Functional relaxations and spectral techniques in Computer-Aided circuit analysis

Analysis of transients in integrated circuits is performed with the use of highly specialized computer programs. The transient responses are computed using time-marching integration methods and require a substantial amount of computer time. A new method based on spectral analysis and waveform relaxation is proposed. The method results in a substantial saving in computing time without compromising the accuracy. A basic algorithm utilizing the spectral technique in a relaxation framework is described. A prototype simulator based on the algorithm was developed and used to simulate certain types of CMOS circuits. The results showed a significant time savings in comparison with the widely used circuit simulator ‘SPICE’. Example circuits and relevant results are provided.     

IGCT功能仿真模型及其应用

集成门极换流晶闸管(IntegratedGateCommutatedThyristors,简称IGCT)以其优越的性能,在中、高压大功率变换器领域得到越来越广泛的应用。本文在SIMPLORER仿真平台下建立了IGCT器件的功能仿真模型;介绍了建模原理及模型结构。根据5SHY35L4510型IGCT给出的主要参数进行了电路仿真。根据仿真结果,分析了电路中各参数对器件开关瞬态过程电压、电流的影响。     

智能变电站中顺序控制的功能分析与实现

根据<智能变电站技术导则>对智能变电站顺序控制功能的要求,分析了变电站电气设备的各种运行方式以及运行状态的转换,归纳了变电站实现顺序控制操作的主要类型,提出了智能变电站实现顺序控制操作应具备的软硬件条件以及具体的实现方式,基于实践经验总结了智能变电站实现顺序控制操作中需要注意的方面.最后指出变电站实施顺序控制操作可以有...     

功能视角与商业广告翻译

随着世界经济的发展和国际经济一体化的趋势,广告在人们生活中的作用越来越重要,广告翻译在经济生活中的作用也越来越明显.但由于各国语言和文化的差异,广告翻译也同其他翻译一样面临差异带来的各种问题.本文将依据语言文化的特点,分析广告翻译的问题所在,并尝试从功能翻译理论的角度寻找解决美汉广告互译方法.     

地调EMS功能需求及算法

提出了地调 Ｅ Ｍ Ｓ 无功电压运行质量评价的功能需求及相应算法。适当实施无功电压运行质量评价,可在补偿装置和调压手段一定的情况下,充分发挥设备潜力,提高母线电压合格率、功率因数,降低线损,延长电容器运行寿命。     

虹桥商务区智能电网功能定位与特色

介绍了上海虹桥商务区建设智能电网的功能定位与特色,从新能源接入、储能系统及智能变电站建设、配电自动化的角度,阐述了虹桥商务区智能电网建设方案构思。     

Separating heart sounds from lung sounds. Accurate diagnosis of respiratory disease depends on understanding noises.

This study reviews the adaptive methods of canceling heart sounds from lung sounds that have been investigated over approximately 20 years. Filtering techniques are categorized as linear adaptive filters and filters employing time-frequency based methods. Several filtering schemes are outlined within these two categories. Methods of heart sound localization are indicated in conjunction with the studies of heart-sound cancellation. Details such as digitization parameters, the location of heart and lung sound recordings, and the number of subjects used in each study. Since a primary objective of respiratory sound research is bring about improvements to monitoring and diagnosis of respiratory disease, the potential usefulness of any method for filtering heart sounds from lung sounds rests on its ability to perform in a clinical setting     

Functional and metabolic consequences of aortic valve replacement

4. Conclusions Severe aortic valve stenosis leads to a decreased myocardial PCr/ATP, and to impairment of LV diastolic function. Following aortic valve replacement, myocardial PCr/ATP normalizes completely, whereas LV diastolic function improves significantly. Moreover, there is an association between altered myocardial HEP metabolism and impaired LV diastolic function.     

Functional MRI study of PASAT in normal subjects

The paced auditory serial addition test (PASAT) is routinely used to evaluate the cognitive part of the multiple sclerosis functional composite (MSFC) score, the new reference index of patient disability. PASAT is sensitive to subtle cognitive impairment related to MS, although the cognitive components of this test still remain unclear. In order to better characterize brain systems involved during this complex task, functional magnetic resonance imaging (fMRI) experiments were conducted during PASAT in a population of ten normal subjects. The paradigm consisted of a series of 61 single-digit numbers delivered every 3 s. After each number, subjects were asked to overt vocalize the result of the addition of the two last numbers heard. A control task consisting of the repetition of the same series of single-digit numbers was used. Statistical group analysis was performed using the random effect procedure (SPM 99). Cortical activation was observed in the left prefontal cortex, the supplementary motor area, the lateral premotor cortex, the cingulate gyrus, the left parietal lobe, the left superior temporal gyrus, the left temporal pole, and visual associative areas. fMRI activations underlying PASAT were consistent with an involvement of verbal working memory and the semantic memory retrieval network which could be related to arithmetic fact retrieval. This study on normal subjects could provide a base for the understanding of the potential abnormal cortical activation in MS patients performing this test for a cognitive evaluation.This revised version was published in March 2005 with corrections to the history.     

Functional learning in signal processing via least squares

This paper addresses certain functional learning tasks in signal processing using familiar algorithms and analytical tools of least squares for autoregressive moving average exogenous input (ARMAX) models, the models can be viewed as conventional ARMAX models but with parameters dependent on variables such as inputs or states, termed function input variables. The functional dependence of the parameters on these variables is represented in terms of basis function expansions or, more generally, interpolation function representations. The interpolation functions in a least-squares identification of coefficients also turn out to be in essence spread functions that spread learning throughout the space of function input variables. Thus for a set of training sequences or trajectories in function input space, system parameters and thereby system functionals can be updated. The idea is that these will have relevance for similar sequences or neighbouring trajectories. The concept of persistence of excitation to achieve complete function learning or, equivalently, signal model learning is studied using least-squares convergence results. Application of the proposed algorithms and theory within the signal-processing context is addressed by means of simple illustrative examples.     

Defects and deceptions-the Bjork-Shiley heart valve

The development of mechanical heart valves is one of the success stories of contemporary medicine. Many people with diseased heart valves become seriously disabled and soon die unless a prosthetic valve can be installed. Shiley, Inc., later a subsidiary of Pfizer, was a pioneer in the development of mechanical heart valves. In 1974 the company developed a radial spherical (R/S) valve, consisting of a disk held in place by two wire struts, allowing it to swing open and closed in response to blood flow. The struts are welded to a metal ring, which is covered with a cloth sewing ring for attachment to the heart. In 1979 Shiley introduced a similar valve, the 60° Convexo-Concave (C/C), which it believed would improve blood flow through the valve. In this valve, the inlet strut was an integral part of the metal ring and only the outlet strut was welded. A C/C valve that opened to 70° was also manufactured, but it was not approved for sale in the US. The original C/C valve was withdrawn from sale due to a less than 1% failure rate. The ethical, legal and moral issues of this decision are discussed