Electromagnetic scale modeling techniques have been extensively used as a design tool to provide verification of computer model predictions and optimization of design parameters. The model antennas are scaled up in size and down in frequency. The design parameters relate directly to the requirements of obtaining antennas that meet thermal field performance goals. The basic laws of electrodynamic similitude are reviewed and specific applications of the theory to the design of implantable microwave antennas are presented.<>
{"title":"Electromagnetic scale modeling of implantable microwave antennas for cancer hyperthermia","authors":"R.S. Kasevish","doi":"10.1109/NEBC.1988.19401","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19401","url":null,"abstract":"Electromagnetic scale modeling techniques have been extensively used as a design tool to provide verification of computer model predictions and optimization of design parameters. The model antennas are scaled up in size and down in frequency. The design parameters relate directly to the requirements of obtaining antennas that meet thermal field performance goals. The basic laws of electrodynamic similitude are reviewed and specific applications of the theory to the design of implantable microwave antennas are presented.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128960569","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}
The cardiac electrophysiological phenomena of reentrant excitation has been postulated as a possible mechanism for ventricular arrhythmias. Reentrant activation has been shown with the surviving epicardial layer as the electrophysiological substrate in a four-day canine post left anterior descending artery occlusion model. The thin surviving epicardial layer was simulated by a two-dimensional finite cable model with the active membrane properties modeled by modified Beeler-Reuter kinetics. The model surface consists of the periphery-reflecting normal membrane properties with progressively depressed membrane properties and decreased cellular coupling at the center of the surface. The functional significance of the simulation study of cell-cell electrical interaction during reentrant excitation is to provide a basis for understanding the spatial gradations of conduction velocity observed as regions of slow conduction leading to functional conduction block in the reentrant circuit.<>
{"title":"Simulation of cell to cell interaction during reentrant activation","authors":"V. Kowtha, J.K. Li","doi":"10.1109/NEBC.1988.19359","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19359","url":null,"abstract":"The cardiac electrophysiological phenomena of reentrant excitation has been postulated as a possible mechanism for ventricular arrhythmias. Reentrant activation has been shown with the surviving epicardial layer as the electrophysiological substrate in a four-day canine post left anterior descending artery occlusion model. The thin surviving epicardial layer was simulated by a two-dimensional finite cable model with the active membrane properties modeled by modified Beeler-Reuter kinetics. The model surface consists of the periphery-reflecting normal membrane properties with progressively depressed membrane properties and decreased cellular coupling at the center of the surface. The functional significance of the simulation study of cell-cell electrical interaction during reentrant excitation is to provide a basis for understanding the spatial gradations of conduction velocity observed as regions of slow conduction leading to functional conduction block in the reentrant circuit.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129249228","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}
A. Erickson, B. Beynnon, C. Werthiemer, B. Fleming, M. Pope, R. Johnson, J. Howe, C. Nichols
To diagnose an anterior cruciate ligament (ACL) injury, clinicians perform a Lachman test at 30 degrees of flexion or a Drawer test at 90 degrees of flexion to record how far the tibia displaces anteriorly with respect to the femur. A study was undertaken to characterize the normal strain pattern of the ACL in vivo during the Lachman and Drawer tests, and to determine if there is a significant difference between the strain patterns at clinically applied load levels. Five patients were studied. After routine arthroscopic surgery a Hall-effect displacement transducer was attached arthroscopically to the ACL to measure strain. Loads were applied by a hand-held load cell in a transverse plane directed through the midtibial tuberosity at flexion angles of 90 degrees and 30 degrees . The difference in percentage strain between the Lachman and Drawer tests was highly significant at p<0.01 level. These results clearly show that the Lachman test produces a greater elongation or strain in the ACL in comparison to the Drawer test at loads to 35 lb. From these data the authors characterize the normal ACL strain pattern.<>
{"title":"An in-vivo study of ACL strain in the normal knee during Lachman and Drawer tests","authors":"A. Erickson, B. Beynnon, C. Werthiemer, B. Fleming, M. Pope, R. Johnson, J. Howe, C. Nichols","doi":"10.1109/NEBC.1988.19332","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19332","url":null,"abstract":"To diagnose an anterior cruciate ligament (ACL) injury, clinicians perform a Lachman test at 30 degrees of flexion or a Drawer test at 90 degrees of flexion to record how far the tibia displaces anteriorly with respect to the femur. A study was undertaken to characterize the normal strain pattern of the ACL in vivo during the Lachman and Drawer tests, and to determine if there is a significant difference between the strain patterns at clinically applied load levels. Five patients were studied. After routine arthroscopic surgery a Hall-effect displacement transducer was attached arthroscopically to the ACL to measure strain. Loads were applied by a hand-held load cell in a transverse plane directed through the midtibial tuberosity at flexion angles of 90 degrees and 30 degrees . The difference in percentage strain between the Lachman and Drawer tests was highly significant at p<0.01 level. These results clearly show that the Lachman test produces a greater elongation or strain in the ACL in comparison to the Drawer test at loads to 35 lb. From these data the authors characterize the normal ACL strain pattern.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133748164","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}
High-frequency current distribution was investigated while performing a simulated electrosurgical procedure (transurethral resection/TUR) in a canine model utilizing a function generator, spectrum analyzer, and current probes to measure current. Contour plots from recordings on integument muscle, nerve, vein, and artery tissue at sequential axial sites revealed current totals of 45% in artery, 24% in vein, 13% both in skin and muscle, and 5% in nerve. The investigations reveal that, during endoscopic (TUR) and other electrosurgical procedures, anatomic structures such as great vessels may act as preferential high-frequency current conduits and could potentially facilitate serious sequelae, such as obturator nerve-muscle spasm, electrical burns, or even cardiac arrythmias (at higher power levels).<>
{"title":"High frequency current distribution in axial body structures during electrosurgery","authors":"S. Selikowitz, J. Lacourse, G. Gerhard","doi":"10.1109/NEBC.1988.19360","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19360","url":null,"abstract":"High-frequency current distribution was investigated while performing a simulated electrosurgical procedure (transurethral resection/TUR) in a canine model utilizing a function generator, spectrum analyzer, and current probes to measure current. Contour plots from recordings on integument muscle, nerve, vein, and artery tissue at sequential axial sites revealed current totals of 45% in artery, 24% in vein, 13% both in skin and muscle, and 5% in nerve. The investigations reveal that, during endoscopic (TUR) and other electrosurgical procedures, anatomic structures such as great vessels may act as preferential high-frequency current conduits and could potentially facilitate serious sequelae, such as obturator nerve-muscle spasm, electrical burns, or even cardiac arrythmias (at higher power levels).<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131787543","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}
An optical keyboard emulator (OKE) which allows individuals with severe motor dysfunction to access personal computer systems by small head movements is discussed. The OKE incorporates a focused optical headpointer which can detect one light-emitting diode (LED) on a driven LED keyboard array providing the high information bandwidth of the direct selection technique. The spacing of the LED array, a reference light pointer, and a key memory system provide improvements over commercially available systems allowing individuals without accurate head control to utilize this device. The OKE is microprocessor-based, yielding versatility in keyboard layout and compatibility between computer systems while being completely transparent to the personal computer.<>
{"title":"A microprocessor controlled optical keyboard emulator","authors":"F.C. Hludik, J. LaCourse, P. Caron","doi":"10.1109/NEBC.1988.19373","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19373","url":null,"abstract":"An optical keyboard emulator (OKE) which allows individuals with severe motor dysfunction to access personal computer systems by small head movements is discussed. The OKE incorporates a focused optical headpointer which can detect one light-emitting diode (LED) on a driven LED keyboard array providing the high information bandwidth of the direct selection technique. The spacing of the LED array, a reference light pointer, and a key memory system provide improvements over commercially available systems allowing individuals without accurate head control to utilize this device. The OKE is microprocessor-based, yielding versatility in keyboard layout and compatibility between computer systems while being completely transparent to the personal computer.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126618243","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}
Experiments were conducted in which postures of the elbow and forearm were quasistatically maintained through deliberate cocontraction of the biceps and triceps, the principal flexor and extensor muscles acting about the elbow. The object of these experiments was to record the levels of muscular activation for the biceps and triceps as various postures of the elbow and forearm were maintained for a full range of cocontraction. Trials were conducted over a range of elbow angle from near fully flexed to near fully extended. Preliminary results from these experiments are presented. These show that for forearm postures away from the midrange of the elbow, cocontraction leads to antagonist muscle activation levels that, are significantly larger than the corresponding level of agonist activation i.e., the muscle supporting the limb against gravity is not working as hard as its antagonist counterpart. An explanation of these counterintuitive results is presented, based on assumed length-dependence of the muscle efficiency relating neural input to muscle force.<>
{"title":"Maintenance of elbow equilibrium through co-contraction","authors":"W. Murray","doi":"10.1109/NEBC.1988.19335","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19335","url":null,"abstract":"Experiments were conducted in which postures of the elbow and forearm were quasistatically maintained through deliberate cocontraction of the biceps and triceps, the principal flexor and extensor muscles acting about the elbow. The object of these experiments was to record the levels of muscular activation for the biceps and triceps as various postures of the elbow and forearm were maintained for a full range of cocontraction. Trials were conducted over a range of elbow angle from near fully flexed to near fully extended. Preliminary results from these experiments are presented. These show that for forearm postures away from the midrange of the elbow, cocontraction leads to antagonist muscle activation levels that, are significantly larger than the corresponding level of agonist activation i.e., the muscle supporting the limb against gravity is not working as hard as its antagonist counterpart. An explanation of these counterintuitive results is presented, based on assumed length-dependence of the muscle efficiency relating neural input to muscle force.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117302917","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}
The analysis includes a consideration of the errors introduced by deviation from the simple model and the sensitivity of the algorithm to noise in the data. The procedure is tested by simulations based on analytical solutions for a cone and on a model of the central airways of the human respiratory tract.<>
{"title":"Investigation of the limitations of acoustic airway measurement","authors":"C. Strowbridge, G. Cano","doi":"10.1109/NEBC.1988.19394","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19394","url":null,"abstract":"The analysis includes a consideration of the errors introduced by deviation from the simple model and the sensitivity of the algorithm to noise in the data. The procedure is tested by simulations based on analytical solutions for a cone and on a model of the central airways of the human respiratory tract.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124973850","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}
A computer simulation of the Penn State rollerscrew electric ventricular assist device (EVAD) and the mock circulatory system has been developed for the purpose of control system design. The system model and simulation were verified for accuracy with a mock circulatory system using an EVAD. An observer based on a Luenberger observer was used to predict unmeasurable system pressures necessary for pump output control. From the simulation, accurate aortic pressure values were obtained using the observer during systole at a beat rate of 60 beats/min. The gains used in the observer were judiciously chosen, but a method for optimizing the feedback gains was developed. This method of selecting the observer gains which minimizes the error between the observer and the system is by pole placement rather than by statistical techniques.<>
{"title":"Aortic pressure estimation for the Penn State electric ventricular assist device","authors":"J. Koontz, U. Tsach, D. Geselowitz","doi":"10.1109/NEBC.1988.19375","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19375","url":null,"abstract":"A computer simulation of the Penn State rollerscrew electric ventricular assist device (EVAD) and the mock circulatory system has been developed for the purpose of control system design. The system model and simulation were verified for accuracy with a mock circulatory system using an EVAD. An observer based on a Luenberger observer was used to predict unmeasurable system pressures necessary for pump output control. From the simulation, accurate aortic pressure values were obtained using the observer during systole at a beat rate of 60 beats/min. The gains used in the observer were judiciously chosen, but a method for optimizing the feedback gains was developed. This method of selecting the observer gains which minimizes the error between the observer and the system is by pole placement rather than by statistical techniques.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117018980","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}
Several design variations were tested in Guy muscle equivalent phantom. A phantom experiment was set up to measure power deposition at 221 or 425 points in the plane of a single antenna or pair of antennas. Antennas were constructed and tested with different helical designs. Antennas with helical-tip vs. helical-junction connections were compared. Oppositely wound pairs were tested and compared with identically wound helixes. The effect of a large junction gap was investigated. A dual-density winding antenna was tested to improve power deposition. All antennas were tested singly and in pairs to gauge interaction. The control antennas were Dartmouth dipoles used in clinical hyperthermia. Finally, actual human temperature data are shown and compared to power deposition patterns. Clinical implications for the antenna array data are discussed.<>
{"title":"Variations in the design of a helical tip microwave antenna for hyperthermia","authors":"T. Ryan, J. Strohbehn","doi":"10.1109/NEBC.1988.19364","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19364","url":null,"abstract":"Several design variations were tested in Guy muscle equivalent phantom. A phantom experiment was set up to measure power deposition at 221 or 425 points in the plane of a single antenna or pair of antennas. Antennas were constructed and tested with different helical designs. Antennas with helical-tip vs. helical-junction connections were compared. Oppositely wound pairs were tested and compared with identically wound helixes. The effect of a large junction gap was investigated. A dual-density winding antenna was tested to improve power deposition. All antennas were tested singly and in pairs to gauge interaction. The control antennas were Dartmouth dipoles used in clinical hyperthermia. Finally, actual human temperature data are shown and compared to power deposition patterns. Clinical implications for the antenna array data are discussed.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131841575","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}
Recent literature suggests a correlation between the acoustic signals produced by working muscles and the health, effort, and fatigue levels of the muscles. Practical experience gained in setting up a computer-based system to acquire and analyze the myoacoustic signal is discussed. Topics discussed include: obtaining the low frequency (5-50-Hz) signals; signal-to-noise ratio; protocol; and artifact considerations. Preliminary results indicate that large artifact signals are inherent in the frequency range of interest. A simple signal and transducer model is proposed to explain these observations.<>
{"title":"Practical experience obtaining acoustic myographic signals","authors":"C. Tupper, G. Gerhard","doi":"10.1109/NEBC.1988.19370","DOIUrl":"https://doi.org/10.1109/NEBC.1988.19370","url":null,"abstract":"Recent literature suggests a correlation between the acoustic signals produced by working muscles and the health, effort, and fatigue levels of the muscles. Practical experience gained in setting up a computer-based system to acquire and analyze the myoacoustic signal is discussed. Topics discussed include: obtaining the low frequency (5-50-Hz) signals; signal-to-noise ratio; protocol; and artifact considerations. Preliminary results indicate that large artifact signals are inherent in the frequency range of interest. A simple signal and transducer model is proposed to explain these observations.<<ETX>>","PeriodicalId":165980,"journal":{"name":"Proceedings of the 1988 Fourteenth Annual Northeast Bioengineering Conference","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134496607","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}
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