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Engineering in Medicine and Biology Magazine, IEEE

Issue 4 • Date Aug.-Sept. 1994

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Displaying Results 1 - 14 of 14
  • A digital approach to the cardiac cycle

    Publication Year: 1994 , Page(s): 454 - 456
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (346 KB)  

    The timing diagram model could provide the cardiologist with the ways and means of quantifying interval/segment patterns. This analysis would be more exact than present use of electrocardiograms, which relies on subjective analyses of pathological events and the graph patterns they present. Improving the predictability of pathological events by filtering out overriding ventricular depolarization could identify sequential patterns of the atrial repolarization interval/segment. A healthy heart could provide a standard against which specific syndromes might be compared and contrasted for diagnostic purposes. The clinician would have yet another diagnostic tool which could identify patterns requiring aggressive preventive therapy much earlier in the clinical cycle of the patient with a family history of cardiovascular disease. Results of various treatments prescribed for the broad spectrum of cardiological pathologies could also be evaluated in relation to the manner in which these treatments bring the cardiac cycle into synchrony with normal patterns. This comparison would be accomplished by comparing the sequencing and length of time for specific interval/segment patterns demonstrated before, during, and after the treatment occurs. If successful, the proposed analysis of the ECG would ultimately contribute to more positive outcomes for patients who presently may have a poor prognosis.<> View full abstract»

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  • Biomedical engineering in China. A look at the growth of the BME Society, and advanced education

    Publication Year: 1994 , Page(s): 460 - 462
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    Freely Available from IEEE
  • Determining hearing threshold from brain stem evoked potentials. Optimizing a neural network to improve classification performance

    Publication Year: 1994 , Page(s): 465 - 471
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    Feed-forward neural networks in conjunction with back-propagation are an effective tool to automate the classification of biomedical signals. Most of the neural network research to date has been done with a view to accelerate learning speed. In the medical context, however, generalisation may be more important than learning speed. With the brain stem auditory evoked potential classification task described in this study, the authors found that parameter values that gave fastest learning could result in poor generalisation. In order to achieve maximum generalisation, it was necessary to fine tune the neural net for gain, momentum, batch size, and hidden layer size. Although this maximization could be time consuming, especially with larger training sets, the authors' results suggest that fine tuning parameters can have important clinical consequences, which justifies the time involved. In the authors' case, fine tuning parameters for high generalisation had the additional effect of reducing false negative classifications, with only a small sacrifice in learning speed.<> View full abstract»

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  • Pharmocokinetics of dicarboxylic acids in man

    Publication Year: 1994 , Page(s): 472 - 478
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (901 KB)  

    In order to study the feasibility of using dicarboxylic acids for parenteral nutrition, the authors studied the pharmacokinetics in man of azelaic acid and sebacic acid. The pharmacokinetic analysis presented here shows that there are different modalities in the urinary excretion of the dicarboxylic acids with 9 or 10 carbon atoms. While azelaic acid seems to be actively secreted, sebacic acid is actively reabsorbed.<> View full abstract»

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  • Origin of the electrocardiogram

    Publication Year: 1994 , Page(s): 479 - 486
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1016 KB)  

    In this review, the authors examine the source of the electric field and the physics relating to some common abnormalities in the ECG. They also look at the use of three dimensional modeling in unravelling the potential fields within the thorax. Initially, the authors refer the reader to an excellent recent text, which includes detailed discussion of the physics of the origin of the electrocardiogram (P.W. Macfurlane and T.D.V. Lawie eds., Comprehensive electrocardiography; theory and practice in health and disease, vol.1, Oxford, Pergamon Press, 1989); and a list of key references that will provide significant information (J. Holneau, Circulation, vol. 64, no. 1, p. 208-13, 1981).<> View full abstract»

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  • Solving the inverse problem in magnetocardiography

    Publication Year: 1994 , Page(s): 487 - 496
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1480 KB)  

    Biomagnetic methods have proven to be valuable as research tools in obtaining functional information that is difficult to gain by conventional clinical imaging methods. Still, the magnetocardiographic localization method has to compete with corresponding bioelectric measurements and other noninvasive methods, such as two-dimensional echocardiography, magnetic resonance imaging, and gated X-ray and radionuclide imaging. All of these methods have their limitations, and the later ones may, in certain cases, afford some risk to the patient. So far, the must successful application of biomagnetic methods has been the localization of bioelectric sources in the body. Promising results have been reported, with accuracies comparable to the localization results obtained by invasive clinical methods. Considering the possible clinical use of magnetocardiographs, the localization of arrhythmogenic regions as well as selection of patients with high risk of arrhythmias and sudden cardiac death are important. Theoretically, the advantage of biomagnetic measurements over corresponding bioelectric surface potential studies is still controversial. However, in practice, the spatial resolution capability of biomagnetic methods seems to be better. In various studies, the combination of both magnetic and electric data can bring improvements in the inverse solution.<> View full abstract»

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  • Modeling and simulation of brain lesions by the finite-element method

    Publication Year: 1994 , Page(s): 497 - 503
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (789 KB)  

    In this study the consolidation model is used to study the influence of the cerebrospinal fluid on the mechanical factors in the brain. First, in the model flow patterns similar to observations by CT were obtained. But these results were dependent on the boundary conditions and material constants. One must examine these factors more exactly with medical data. Second, stress concentration was observed near the horns of the lateral ventricle, areas that coincide with that of periventricular lucency. Cerebrospinal fluid plays an important role in brain lesions. MRI or CT images give one qualitative information, but no quantitative measure of force. Finite element simulations have the possibility of providing such information. The authors believe that if the qualitative model can be constructed, and using the technique of inverse analysis with the image information, it may be possible to obtain quantitative values of material constants from the clinical observations.<> View full abstract»

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  • Resistance of gastric mucosa to self-digestion

    Publication Year: 1994 , Page(s): 504 - 507
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (734 KB)  

    In recent years, the view of the gastric mucosal barrier as a static entity has given way to a dynamic system, the components of which have recently been reviewed in detail. These complex anatomical and physiological properties are conveniently divided into three categories. The major extrinsic factor is the pre-epithelial mucus-bicarbonate barrier, which provides a first line of defence. Intrinsic protection residing with the mucosal cells per se, involves cytoplasmic pH homeostasis together with epithelial restitution and regeneration. Finally, postepithelial factors within the submucosa and interstitium include the microvasculature and maintenance of acid-base balance.<> View full abstract»

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  • Applying bone-adaptive remodelling theory to ligamentous spine. Preliminary results of partial nucleotomy and stabilization

    Publication Year: 1994 , Page(s): 508 - 516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1131 KB)  

    Remodelling theory is applied to show that a vertebral body of a spinal motion segment is an optimum structure. Then, the study is extended to analyze the changes in the shape of the vertebral bodies due to an "injury" to the disc and then the stabilization of the injured motion segment using a rigid fixation device. The salient finding of this study is the demonstration that it is feasible to quantify changes in the spinal structures following surgery. However, keeping in mind the complex nature of the spinal structures, the limitations inherent in this study, and the assumption made for the bone adaptive remodelling theory, one needs to very systematically increase the complexity of the spinal model, and also initiate in parallel experimental studies delineating the remodelling aspects of the spinal structures.<> View full abstract»

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  • Mechanical aspects of vascular graft-host artery anastomoses

    Publication Year: 1994 , Page(s): 517 - 524
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1094 KB)  

    For vascular graft implantation the mechanical stresses induced by abnormal flow dynamics as well as regions of stress concentration in the walls of the host artery and the graft appear to play an important role in neo-intimal fibrous hyperplasia formation and loss of patency. Detailed in vitro and in vivo experimental studies as well as theoretical analysis, will help delineate the factors responsible for hyperplasia formation and thus enable modifications in the design characteristics to minimize the problem. In the case of end-to-end anastomoses the compliance mismatch between the host artery and the vascular graft appears to be the dominant factor for the abnormal flow dynamics in the anastomotic region. However, in end-to-side anastomoses, the geometry at the anastomosis appears to be more important, with the compliance mismatch playing a secondary role. Further detailed experimental studies complemented by detailed three-dimensional unsteady flow analysis in realistic anastomotic geometries are needed to suggest possible solutions to minimize the problem of loss of patency, particularly with medium and small diameter vascular grafts.<> View full abstract»

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  • Clinical biomechanics of spinal fixation-anterior, posterior, and lateral

    Publication Year: 1994 , Page(s): 525 - 531
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1105 KB)  

    The three primary systems of spinal fracture-fixation may be categorized as follows: (a) Posterior fixation of the fractured spine by means of devices attached to posterior structures of the spinal column. These devices apply flexion-resisting forces to the deformed spinal column but cannot correct the spinal deformity nor decompress the spinal cord; (b) Lateral fixation of the fractured spine by means of devices that are attached parallel to the intact vertebral bodies above and below the fractured body, and bypass the loading on the spine across its fractured segment; (c) Anterior fixation of the fractured spine by means of a device that replaces the fractured vertebral body segment and transmits the load through it from the intact vertebral body above the fractured body to the intact spinal fracture below it. Here the authors provide biomechanical analyses of the function and efficacy of each of these systems, supported by some case histories.<> View full abstract»

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  • The first stimulators-reviewing the history of electrical stimulation and the devices crucial to its development

    Publication Year: 1994 , Page(s): 532 - 542
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1147 KB)  

    The following topics are discussed: the capacitor-discharge stimulator; empirical strength-duration curve; theoretical strength-duration curve; basis for stimulation; galvanic (direct-current) stimulation; Daniell cell; Grove (Bunsen) cell; Leclanche cell; interrupted direct-current stimulators; the inductorium; Galvanic-Faradic stimuli to diagnose nerve injury; modern stimulators.<> View full abstract»

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  • Federal law and individual activities

    Publication Year: 1994 , Page(s): 544 - 546
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (582 KB)  

    The old federalism resulted in the establishment of basic rights that are protected from infringement by government. The new federalism results in extensions of both the scope of one's rights and the scope of their protection. The scope of natural rights protected is determined by the inalienability of such rights for all men. The scope of their protection depends on such issues as the points of overlap of the individual rights of the parties, the extent to which the parties engage the public in their transduction, etc. When do the rights of one party yield to the conflicting rights another? A logical standard is the extent to which each party has a claim based on a natural right or freedom. You may elect to constrain your right to free speech if you know I will exert my right to privacy and collect money damages from you if you tell a malicious lie about me.<> View full abstract»

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  • Engineering automated systems for physical mapping

    Publication Year: 1994 , Page(s): 547 - 550
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB)  

    The automated physical mapping system described here is currently being used to complete physical maps of both the human and the mouse genomes. The originally targeted 5,000 screenings per day has been surpassed with about 18,000 daily screenings on a routine basis. Thus far, 3,500 STSs have been mapped and the remaining 6,500 required to make the first low-density STS physical map are likely to be completed very early in 1995. Many of the biochemical and automation techniques used for this physical mapping project may also have applications in other areas such as DNA genotyping, and DNA diagnostics. For example, it may be possible to screen large populations for particular genetic diseases (such as cystic fibrosis and a propensity for certain cancers) before they exhibit any symptoms, thereby allowing potential treatments to start as early as possible.<> View full abstract»

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Aims & Scope

IEEE Engineering in Medicine and Biology Magazine contains articles on current technologies and methods used in biomedical and clinical engineering.

 

This Magazine ceased publication in 2010. The current retitled publication is IEEE Pulse.

Full Aims & Scope