Journal of biomedical engineering最新文献

{"title":"Pressure-volume relation in the right ventricle","authors":"R.M. Shoucri","doi":"10.1016/0141-5425(93)90051-Y","DOIUrl":"10.1016/0141-5425(93)90051-Y","url":null,"abstract":"<div><p>The concept of body force (force/unit volume of muscle), which has been suggested as an explanation for the mechanical contraction of the left ventricle, is now applied to the right ventricle. The results indicate that the same mathematical formalism can be applied to a description of the pressure-volume relation and the ejection mechanism in both the right and left ventricles.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 167-169"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90051-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19441775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Motion measurement with high-speed video","authors":"S. Holzreiter,&nbsp;J. Kastner,&nbsp;P. Wagner","doi":"10.1016/0141-5425(93)90044-Y","DOIUrl":"10.1016/0141-5425(93)90044-Y","url":null,"abstract":"<div><p>A new kinematic measurement system based on a high-speed video system, combined with a computer-assisted evaluation for the analysis of gait patterns, is described. The system allows both a reviewable visual assessment in slow motion (up to 1000 frames s⁻¹ as well as automatic measurement of the kinematics of body segments. Specially developed software, which uses a pattern search algorithm and an additional subpixel correction, results in a deviation of less than 0.1% (without considering the lens nonlinearity). For most cases the recognition and tracking of temporarily concealed markers is also achieved. The results of the computer-assisted high-speed video analysis are being applied in rehabilitation programmes to increase the objectivity of standard movements, e.g. gait analysis of people with artificial limbs.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 140-142"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90044-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19443266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mathematical model of the right ventricular muscle geometry and mass","authors":"F. Czegledy ,&nbsp;N. Aebischer ,&nbsp;D. Smith ,&nbsp;J. Katz","doi":"10.1016/0141-5425(93)90041-V","DOIUrl":"10.1016/0141-5425(93)90041-V","url":null,"abstract":"<div><p>An understanding of the geometry of the right ventricular (RV) free wall is imperative for both modelling its mechanics and assessing its mass by imaging techniques such as echocardiography. In this paper, a new model of the RV free wall geometry is discussed in which the wall is assumed to have a parabolic long-axis and a circular short-axis curvature respectively. By use of analytic geometry, mathematical expressions for RV surface area, volume and mass were derived. <em>In vitro</em> model validation was carried out in the following manner: (1) echocardiographic images of 16 isolated calf hearts were obtained; (2) measurements were made from the images to determine the parameters required by the model; (3) wall mass was determined by use of these parameters; and (4) the calculated wall mass was then compared with actual RV wall mass (determined by weighing). The model was found to be very accurate for determination of RV free wall mass (<em>R</em> = 0.92); it should prove useful in the study of the stress-strain relationships for the RV and for precise quantitative assessment of RV free wall mass.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 127-131"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90041-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19443263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foot microcirculation and blood rheology in diabetes","authors":"P. Zioupos ,&nbsp;J.C. Barbenel ,&nbsp;G.D.O. Lowe ,&nbsp;S. MacRury","doi":"10.1016/0141-5425(93)90048-4","DOIUrl":"10.1016/0141-5425(93)90048-4","url":null,"abstract":"<div><p>Diabetes mellitus is associated with circulatory abnormalities. The blood flow in the skin of the dorsum of the foot and haemorheological variables were measured in 36 subjects. They were divided into three equal groups of diabetic patients: those with neuropathy, and both age and sex matched non-diabetic subjects; all were characterized by age, duration of diabetes and blood biochemistry. High and low shear rate blood viscosities were measured; aggregation was characterized using a Myrerene Aggregometer. The microcirculation in the skin of the dorsum of the foot was measured using a laser Doppler flowmeter. Measurements were made at room temperature with the subjects supine with the leg horizontal, and then with the lower leg vertical; the measurements were repeated at 42° C. Both diabetic groups had significantly increased low shear whole blood viscosity compared with normal subjects. The aggregation index was significantly greater in diabetic neuropaths than normal subjects. There were significant differences in the depth of vasomotor activity between the three groups, with the diabetic neuropaths commonly showing no motor activity at room temperature. The only significant correlations were between equilibrium laser Doppler values with the limb horizontal and both the low and high shear whole blood viscosities.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 155-158"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90048-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19441772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wave digital matched filter for electrocardiogram preprocessing","authors":"D. Ebenezer,&nbsp;V. Krishnamurthy","doi":"10.1016/0141-5425(93)90042-W","DOIUrl":"10.1016/0141-5425(93)90042-W","url":null,"abstract":"<div><p>Digital filters play an important role in electrocardiography. Digital filter algorithms having low sensitivity to finite word-length errors are generally desirable. Wave digital filters (WDFs) are a class of filters having excellent sensitivity properties. A wave digital matched filter (WDMF) for ECG preprocessing is presented here.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 132-134"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90042-W","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19443264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multielectrode spiral cuff for ordered and reversed activation of nerve fibres","authors":"J. Rozman ,&nbsp;B. Sovinec ,&nbsp;M. Trlep ,&nbsp;B. Zorko","doi":"10.1016/0141-5425(93)90039-2","DOIUrl":"10.1016/0141-5425(93)90039-2","url":null,"abstract":"<div><p>In this paper we present the modelling, design, and experimental testing of a nerve cuff multielectrode system for selective activation of fibres in superficial peripheral nerve trunk regions which is capable of activating fibres in physiological order. The multielectrode system consists of 45 platinum electrodes embedded within a self-curling spiral silicone sheet organized in fifteen longitudinal groups consisting of three electrodes spaced equidistally around the circumference of the cuff. Electrodes in the centre band acted as stimulating cathodes while the two electrodes of the same group in the two outer bands were connected together and corresponded to the position of a particular cathode, serving as anodes to block the nascent action potentials by membrane hyperpolarization. The interpolar distance was 6 mm on both sides, resulting in a total cuff length of about 20 mm. The cuff was constructed with a diameter to fit the size of the dog sciatic nerve. Preliminary animal testing of the nerve cuff was performed on the sciatic nerve of a Bigley female dog. In the 45-electrode stimulation system, biphasic cathodic first pulses with quasitrapezoidal-shaped cathodic and square anodic parts were delivered through the particular group of tripolar electrodes to effect both selective stimulation of motor axons within the gastrocnemius muscle fascicle, and differential block by membrane hyperpolarization. The test was repeated using rectangular cathodic first biphasic current pulses delivered monopolarly on the central electrode of the same group while connected anodes were replaced by a common anode situated elsewhere in the surrounding tissue. In both experiments an isometric torque in the ankle joint elicited by the gastrocnemius muscle was measured and compared. It was shown that tripolar activation with quasitrapezoidal stimulation pulses elicited an isometric torque with a peak value of 0.83 Nm in 65 ms after onset of delivering stimulating pulses in comparison to the monopolar activation with rectangular biphasic pulses where the peak of the same value was observed in 45 ms after onset. Thus, the multipolar cuff stimulating monopolarly provided an effective means of activating motor axons selectively within the gastrocnemius muscle fascicle, while more physiological recruitment of the muscle fibres was evident when stimulating tripolarly.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 113-120"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90039-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19443261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unstable states in four-point walking","authors":"T. Bajd,&nbsp;A. Kralj,&nbsp;M. Žefran","doi":"10.1016/0141-5425(93)90049-5","DOIUrl":"10.1016/0141-5425(93)90049-5","url":null,"abstract":"<div><p>The presently utilized walking patterns in paraplegic subjects with complete spinal cord injury (SCI) are compared by the help of graphic representations. Improved four-point gait assisted by functional electrical stimulation (FES) and crutches is proposed by introducing unstable states into the walking sequence. The unstable states are defined as passive phases of walking where the centre of mass (COM) is gravity driven in the direction of progression. The unstable state is described by a simple inverted pendulum model. Kinematic measurements of the unstable state were performed in normal and paraplegic subjects.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 159-162"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90049-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19441773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stereoradiogrammetric technique for estimating alignment of the joints in the hand and wrist","authors":"R.J. Runciman,&nbsp;J.T. Bryant,&nbsp;C.F. Small,&nbsp;N. Fujita,&nbsp;T.D.V. Cooke","doi":"10.1016/0141-5425(93)90037-Y","DOIUrl":"10.1016/0141-5425(93)90037-Y","url":null,"abstract":"<div><p>A method and apparatus for quantitative measurement of the alignment and motion of the joints of the hand in three dimensions has been developed using stereoradiogrammetric principles. Alignment in planes of flexion-extension and radial-ulnar deviation can be determined to within 2.5°; rotation about the long axis of the metacarpals or phalanges is more difficult to determine, and can be measured to within 7°. Stereo views subtending angles in the range of 40° were found to optimize the total system accuracy.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 99-105"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90037-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19441779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breast compression: a preliminary study","authors":"D.J. Watmough ,&nbsp;K.M. Quan ,&nbsp;R.M. Aspden","doi":"10.1016/0141-5425(93)90040-6","DOIUrl":"10.1016/0141-5425(93)90040-6","url":null,"abstract":"<div><p>X-Ray mammography is the technique employed to image breast tumours; it is the gold standard for both diagnosis and screening¹. To increase the sensitivity of the test and to reduce the dose of X-radiation, breast compression is used. The effect of squeezing a simple model of a breast in which there is an idealized spherical tumour volume is investigated; the cases where the lesion has both a smaller, and a larger compressibility than the surrounding tissues are considered. Surface strain is computed as a function of the deformation of the lesion from its spherical shape. Evidence from earlier studies is adduced to show that when the lesion is malignant care should be exercised to avoid the possibility of disseminating cancer cells by the application of compressive forces.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 121-126"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90040-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19443262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computer generation of complex arterial tree models","authors":"W. Schreiner","doi":"10.1016/0141-5425(93)90046-2","DOIUrl":"10.1016/0141-5425(93)90046-2","url":null,"abstract":"<div><p>Detailed models binary branching arterial trees can be generated on a computer by using a new optimization technique; additional branches are successively added, while given conditions of perfusion pressure, total flow and terminal pressure are fulfilled. The vessel radii at each branching obey certain bifurcation laws, and the process of growing the tree is governed by minimizing a target function. The structure thus generated may serve as substrate for the future simulation of haemodynamics in highly detailed arterial trees.</p></div>","PeriodicalId":75992,"journal":{"name":"Journal of biomedical engineering","volume":"15 2","pages":"Pages 148-150"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0141-5425(93)90046-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19441770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}