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Suzanne S. Stensaas, Donald K. Eddington and William H. Dobelle

to position between 54 and 196 electrodes per hemisphere and twice that number per patient. Computer simulation 29 suggests that a display of 256 points with 8 levels of brightness modulation can transmit meaningful half-tone pictures, and Brindley 4 has calculated that many fewer points are needed to permit reading at reasonable speeds. The cortex above and below the calcarine fissure represents the lower and upper parts of the visual field. The rostral-caudal extent of the mesial exposed striate cortex and its distribution above and below the fissure is

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Said H. Koozekanani, W. Michael Vise, Reza M. Hashemi and Robert B. McGhee

some possible sources of such deviations. The purpose of this paper is to further explore the mechanics of experimental spinal cord injury and to relate the results obtained to the remarks of Osterholm and others 3 using data obtained both from laboratory experiments and from a computer simulation of injury dynamics. Materials and Methods This study was conducted in two parts. In the first part, we fabricated three different drop-masses, an impounder, and two glass guide tubes with lateral slits for ventilation. Our impounder weighed 2 gm and had a circular

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Manuel Dujovny, Norman Wakenhut, Nir Kossovsky, Carl W. Gomes, Ranjit K. Laha, Louis Leff and Debra Nelson

finite element technique, we determined the stresses in a vessel wall produced by the clipping action. A computer simulation was modeled on a three-layered vascular ellipse. Vessel material properties suggested by Weiderhielm, et al., 18 and adapted by Hrico 10 were employed in a computer library program, PLNESS, available at the University of Pittsburgh Computer Center. Two types of clip pressures were investigated. The first was a uniform compressive load of 2 × 10 6 dynes per unit width (simulating parallel closing clip jaws), with a simulated internal blood

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Sung C. Choi, John D. Ward and Donald P. Becker

presented in this paper provide a very quick estimate of prognosis with a reasonably good accuracy using only the GCS score, oculocephalic response, and age. A fundamental question regarding the chart is its accuracy in prediction. The expected percentage of correct prediction in a prospective setting was evaluated by a computer simulation. Using Fig. 1 , suppose that a patient is predicted on Day 1 to have a “good” outcome probability by the chart of 50% or greater (and a “poor” outcome of 50% or less). A correct prediction will be made in about 79% of the cases. To

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Michael S. B. Edwards, James E. Boggan and Terry A. Fuller

. Diagram of the effects of laser light on neural tissue. The use of computerized tomography with three-dimensional computer simulation-guided stereotaxic CO 2 laser resection of deeply located cerebral lesions such as gliomas, metastatic tumors, and AVM's has provided promising preliminary results. 28, 29 This technique may allow a relatively atraumatic and more complete method for excision of these lesions. Beck 5 and Takeuchi, et al. , 46 have reported their clinical experience using the Nd:YAG laser in patients with a variety of cerebral lesions. The Nd

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Hermes A. Kontos and Enoch P. Wei

Wei EP, Lamb RG, Kontos HA: Increased phospholipase C activity after experimental brain injury. J Neurosurg 56: 695–698, 1982 28. Yokota K , Yamazaki I : Analysis and computer simulation of aerobic oxidation of reduced nicotinamide adenine dinucleotide catalyzed by horseradish peroxidase. Biochemistry 16 : 1913 – 1920 , 1977 Yokota K, Yamazaki I: Analysis and computer simulation of aerobic oxidation of reduced nicotinamide adenine dinucleotide catalyzed by horseradish peroxidase. Biochemistry 16: 1913–1920, 1977

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David W. Roberts, John W. Strohbehn, John F. Hatch, William Murray and Hans Kettenberger

investigated theoretically using computer simulations. Clinical Experience Initial clinical experience with this system has been limited to operative procedures not dependent upon its accuracy and has included craniotomies for meningioma and glioblastoma multiforme. The goals of these trials have been assessment of the feasibility of using this system in the actual operating room environment and determination of the quality of the optical projection component. Results Laboratory Findings Direct measurements of the precision of the digitizer's slant

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Patrick J. Kelly, Catherine Daumas-Duport, David B. Kispert, Bruce A. Kall, Bernd W. Scheithauer and Joseph J. Illig

Engineering in Medicine and Biology Society. Piscataway, NJ : Institute of Electrical and Electronics Engineers , 1985 , pp 939 – 942 Kall BA, Kelly PJ, Goerss SJ, et al: Cross-registration of points and lesion volumes from MR and CT, in Lin JC, Feinberg BN (eds): Proceedings of the 75th Annual Conference of the IEEE Engineering in Medicine and Biology Society. Piscataway, NJ: Institute of Electrical and Electronics Engineers, 1985, pp 939–942 15. Kelly PJ , Kall BA , Goerss S : Computer simulation for the stereotactic

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) values to be between 20 and 40 ml/100 gm/min. Their own data show that within this range of blood flow, errors can be expected to be on the order of 40%. Our computer simulations have shown that the situation is even more complicated for nonhomogeneously perfused tissue, and the errors are much less predictable. 6 Strohbehn, et al. , 4 quantified the contribution of conduction in terms of a time constant τ cond = R o 2 ρ t c t /k, where R o is the effective heating radius of the hyperthermia system, ρ t is the tissue density, c t is the specific heat of the

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J. Alexander Marchosky, Christopher J. Moran, Neal E. Fearnot and Charles F. Babbs

approximately 2 hours. This technique is being evaluated in further clinical studies. Acknowledgments The authors thank Deborah Welsh, R.N., and Connie Zumwalt, R.N., for their assistance with the development of this technique. References 1. Babbs , CF , Fearnot NE , Marchosky JA , et al : Properties of interstitial conductive heat therapy for cancer, demonstrated in computer simulation. IEEE Trans Biomed Eng ( In press , 1990 ) Babbs, CF, Fearnot NE, Marchosky JA, et al: Properties of interstitial conductive heat