Bio-Medical Materials and Engineering - Volume 4, issue 6

Authors: Lam, F. K. | Chan, F. H. Y. | Poon, P. W. F. | Qiu, W. | Xu, B .Z.

Article Type: Research Article

Abstract: The method of ensemble averaging (EA), commonly used to improve signal-to-noise ratio (SNR) in evoked potential measurements, loses potentially useful information regarding response variability across trials. Due to the usually low SNR, it is difficult to extract the response from individual trials. The present paper describes an adaptive signal enhancer (ASE) that is capable of tracking the variation of visual evoked potential (VEP) from trial to trial as well as improving SNR. This ASE requires two inputs: a primary input, which is the raw noise-corrupted response, and a reference input, which is designed for an optimal performance of ASE. We …used moving ensemble averaging (MEA) to form the dynamic reference input. Experimental results in humans show a satisfactory performance of the ASE in determining VEP to single stimulus and in tracking the temporal changes of the signal. Show more

Keywords: visual evoked potential (VEP), adaptive signal enhancer (ASE), moving ensemble averaging (MEA), tracking capability

DOI: 10.3233/BME-1994-4601

Citation: Bio-Medical Materials and Engineering, vol. 4, no. 6, pp. 409-417, 1994

Authors: Hoff, Craig J. | Yang, Wen-Jei

Article Type: Research Article

Abstract: Current mathematical models for describing pulse propagation in arteries are summarized. These models include the effects of viscoelasticity, frequency dependent friction, and other factors. One factor that has not been previously considered is the effect of distributed flow leakage. This leakage is known to have a significant effect on pulse propagation in rigid tubes and it has been assumed to have a similar effect in compliant tubes. These effects are described here, along with the results of a recent study by these authors on the effects of the distributed flow leakage in compliant tubes.

Keywords: blood flow, pulse propagation, viscoelastic arteries

DOI: 10.3233/BME-1994-4602

Citation: Bio-Medical Materials and Engineering, vol. 4, no. 6, pp. 419-437, 1994

Authors: Ito, Michio | Miyazaki, Akimichi | Yamagishi, Toshio | Yagasaki, Hiroshi | Hashem, Azza | Oshida, Yoshiki

Article Type: Research Article

Abstract: Bone filling substances are needed to meet several requirements including nontoxicity, setting time, changes in pH values, and amount of dissolved elements as well as mechanical properties. In this study, the bone-generating composites were prepared by employing the in vivo absorbable (β-tricalcium phosphate as a parent matrix kneaded with CaO, MgO, and ZnO as bone mineral additives with different compositions. The setting time, pH values, compressive strength were investigated as a function of the amount of these bone mineral additives. It was found that the setting time was shortened by increasing CaO, MgO, and ZnO contents. Increasing ZnO contents resulted …in the pH value lower, while the pH values increased by increasing CaO and MgO contents. Increasing ZnO contents caused the compressive strength stronger, on the other hand, the compressive strength was weakened by increasing MgO contents. Furthermore, calcium appears to be selectively released from the hardened composite sample. Show more

Keywords: chitosan, β-tricalcium phosphate, bone filling paste, calcium ion release, compressive strength, pH values

DOI: 10.3233/BME-1994-4603

Citation: Bio-Medical Materials and Engineering, vol. 4, no. 6, pp. 439-449, 1994

Authors: Kim, Jeong K. | Park, Joon B. | Weinstein, James N. | Marsh, John L. | Kim, Yong S. | Loening, Stefan A. H.

Article Type: Research Article

Abstract: The present study has examined the efficacy of shock wave treatment to aid in the removal of bone cement in human cadaver femora after femoral prosthesis implantation. The shock waves were applied to the specimens at four points, in the circumference 90° apart, at three levels. Four hundred shocks were applied at each point with intensity level of 25 kV. Extraction time of the bone cement was significantly (p<0.002) faster in the treated versus untreated control groups. The average extraction time was decreased by 32%. Shock wave treatment also reduced the amount of residual cement inside the bone surface by …an average of 55% (p<0.006). The number of shocks needed to remove the prosthesis from bone cement also decreased significantly (p<0.001) after shock wave treatment. Show more

Keywords: extracorporeal shock wave lithotripsy, revision total hip joint surgery, interface, bone cement, extraction

DOI: 10.3233/BME-1994-4604

Citation: Bio-Medical Materials and Engineering, vol. 4, no. 6, pp. 451-461, 1994