Ammit, AJ, Wells, XE & O'Neill, C 1992, 'Structural heterogeneity of platelet-activating factor produced by murine preimplantation embryos', Human Reproduction, vol. 7, no. 6, pp. 865-870.
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Anast, M, Bell, JM, Bell, TJ & Ben-Nissan, B 1992, 'Precision ultra-microhardness measurements of sol-gel-derived zirconia thin films', Journal of Materials Science Letters, vol. 11, no. 22, pp. 1483-1485.
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Ching, NH, Rosenfeld, D & Braun, M 1992, 'Two-dimensional phase unwrapping using a minimum spanning tree algorithm', IEEE Transactions on Image Processing, vol. 1, no. 3, pp. 355-365.
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Phase unwrapping refers to the determination of phase from modulo 2π data. Some of the phase data may not be reliable (e.g., where the magnitude approaches zero or where the signal-to-noise ratio is poor). In two dimensions, this is equivalent to confining the support of the phase function to one or more arbitrarily shaped regions. A phase unwrapping algorithm is presented which works for two-dimensional (2-D) data known only within a set of nonconnected regions with possibly nonconvex boundaries. The algorithm includes the following steps: segmentation to identify connectivity, phase unwrapping within each segment using a Taylor series expansion, phase unwrapping between disconnected segments along an optimum path, and filling of phase information voids. The optimum path for intersegment unwrapping is determined by a minimum spanning tree algorithm. Although the algorithm is applicable to any 2-D data, the main application addressed is magnetic resonance imaging (MRI) where phase maps are useful in determining the distributions of the applied magnetic field, inherent chemical shifts of the object, and the object’s magnetic susceptibility. © 1992 IEEE
Dr. Pocock, NA, Sambrook, PN, Nguyen, T, Kelly, P, Freund, J & Eisman, JA 1992, 'Assessment of spinal and femoral bone density by Dual X-Ray absorptiometry: Comparison of lunar and hologic instruments', Journal of Bone and Mineral Research, vol. 7, no. 9, pp. 1081-1084.
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Abstract Clinical application of techniques for assessing bone mineral density (BMD) requires accurate and precise measurements that can be related to clearly defined normal ranges. In this study we investigated the clinical interpretation of BMD values in a group of individuals measured on the same day with two different dual-energy x-ray densitometers (Lunar DPX and Hologic QDR 1000). The BMD results were analyzed as absolute values in g/cm2 and with respect to young and age-specific normals as defined by each manufacturer. Absolute BMD values measured by the two instruments were highly correlated (lumbar spine r = 0.98, femoral neck r = 0.95; p < 0.0001). In the lumbar spine, the two instruments assigned almost identical values when expressed as a percentage of age-matched values and as a percentage of young normals, despite a small but systematic difference between the values assigned for the latter index. In the femoral neck, however, there were significant differences in assignments between instruments, expressed both as a percentage of young normal (mean difference 6.2%) and with respect to age-matched values (mean difference 3.3%). In particular, in premenopausal subjects femoral neck values with the Hologic instrument were assigned significantly lower values. This study shows effective comnparability between these two instruments for absolute and relative values for the lumbar spine, as well as for absolute values at the femoral neck, but important differences for normality assignments at the femoral neck. These latter differences may produce bias in the “diagnosis” of femoral neck osteoporosis and may have important implications for clinical decision making. Until these differences are resolved, clinicians should not rely solely on femoral neck BMD measurements in clinical decision making.
DUNSTAN, CR, SOMERS, NM, MILTHORPE, B & EVANS, RA 1992, 'BONE VIABILITY IS LOST WITH AGING IN THE FEMORAL-HEAD BUT NOT THE LUMBAR VERTEBRA - THE LOSS OF VIABILITY DOES NOT APPEAR TO AFFECT BONE COMPRESSIVE STRENGTH', JOURNAL OF BONE AND MINERAL RESEARCH, vol. 7, pp. S193-S193.
James, M & Hoang, D 1992, 'Design of low-cost, real-time simulation systems for large neural networks', Journal of Parallel and Distributed Computing, vol. 14, no. 3, pp. 221-235.
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Systems with large amounts of computing power and storage are required to simulate very large neural networks capable of tackling complex control problems and real-time emulation of the human sensory, language, and reasoning systems. General-purpose parallel computers do not have communications, processor, and memory architectures optimized for neural computation and so cannot perform such simulations at reasonable cost. This paper analyzes several software and hardware strategies to make feasible the simulation of large neural networks in real-time and presents a particular multicomputer design able to implement these strategies. An important design goal is that the system must not sacrifice computational flexibility for speed as new information about the workings of the brain and new artificial neural network architectures and learning algorithms are continually emerging. © 1992.
James, NL, Schindhelm, K, Slowiaczek, P, Milthorpe, B, Graham, AR, Munro, VF, Johnson, G & Steele, JG 1992, 'In vivo Patency of Endothelial Cell‐Lined Expanded Polytetrafluoroethylene Prostheses in an Ovine Model', Artificial Organs, vol. 16, no. 4, pp. 346-353.
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Abstract: The performance of small‐diameter vascular prostheses may be improved by implantation of grafts lined with endothelial cells. Expanded polytetrafluoroethylene (ePTFE) prostheses (4 mm × 40 mm) were coated with fibronectin (20 γg/ml), seeded with endothelial cells, and cultured for 48 h to produce a confluent, autologous endothelial cell lining. They were implanted as carotid interposition grafts in sheep. Seeded ePTFE grafts were compared with nonseeded ePTFE grafts and autologous carotid artery grafts. No anticoagulant or antiplatelet therapy was administered. making this a stringent test model for the thromboresistance of a small‐diameter prosthesis. After 13 weeks the patencies of seeded, nonseeded, and autologous artery grafts were 16% (116), 0% (0/6), and 100% (6/6), respectively. The one seeded graft that was patent was fully lined with endothelial cells and showed no stenosis. The remaining five seeded grafts were occluded by fibrous tissue and displayed substantial spindle cell hyperplasia. There was no apparent difference between the autologous artery grafts and normal arterial tissue, and the anastomoses showed no stenosis. The ovine model provides a conservative test of prosthesis survival and may be useful for study of graft failure.
LEYDEKKERS, P & TEUNISSEN, B 1992, 'SYNCHRONIZATION OF MULTIMEDIA DATA STREAMS IN OPEN DISTRIBUTED ENVIRONMENTS', LECTURE NOTES IN COMPUTER SCIENCE, vol. 614, pp. 94-104.
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This paper presents a study of synchronization mechanisms for real-time video, audio and text data streams. Synchronization is an important and complex issue when multimedia information, stored at geographically distributed locations, has to be transport
O'Neill, C, Ryan, JP, Collier, M, Saunders, DM, Ammit, AJ & Pike, IL 1992, 'Outcome of pregnancies resulting from a trial of supplementing human IVF culture media with platelet activating factor', Reproduction, Fertility and Development, vol. 4, no. 1, pp. 109-109.
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Pike, IL, Ammit, AJ & O'Neill, C 1992, 'Actions of platelet activating factor (PAF) on gametes and embryos: clinical aspects', Reproduction, Fertility and Development, vol. 4, no. 4, pp. 399-399.
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Platelet activating factor (PAF) is a phospholipid widespread in body tissues. Previous reviews have discussed its production by preimplantation embryos and the evidence implicating it as an autocrine mediator in aspects of gamete and embryo physiology. Human spermatozoa contain variable amounts of PAF, the amount contained depending on the source and method of preparation of the sperm. Incubation of human sperm with PAF tends to increase their forward velocity, especially in samples with slow motility. PAF treatment causes an increase in the proportion of acrosome-reacted sperm and in their ability to penetrate both zona-free hamster ova and cervical mucus. PAF has been found in human follicular fluid at ovulation. A role for PAF in ovulation has been suggested, because PAF antagonists reduce the rate of ovulation in rats. In some studies, modest improvements to mouse in vitro fertilization (IVF) rates have been achieved with PAF supplementation of media under specific conditions. Furthermore, in the rabbit and mouse, PAF antagonists have been reported to inhibit fertilization in vivo and in vitro respectively. However, addition of PAF to human IVF medium, but only at the time of insemination and fertilization, had no effect on either fertilization or pregnancy rates. Sensitive bio- and immuno-assays have shown that PAF is secreted by human embryos into their fluid milieu. PAF secretion by these zygotes during culture, although markedly variable, has been correlated with the achievement of pregnancy and pregnancy outcome. Although the secretion of PAF by the mouse embryo decreases during culture in vitro, exogenous PAF enhances embryo viability during culture. Similarly, culture of human zygotes in PAF-supplemented medium prior to embryo transfer significantly increases the chance of achieving pregnancy. Both the implantation and live-birth rates are increased in human IVF by addition of PAF to the medium.
Roe, SC, Milthorpe, BK, True, K, Rogers, GJ & Schindhelm, K 1992, 'The effect of gamma irradiation on a xenograft tendon bioprosthesis', Clinical Materials, vol. 9, no. 3-4, pp. 149-154.
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Ryan, JP, O'Neill, C, Ammit, AJ & Roberts, CG 1992, 'Metabolic and developmental responses of preimplantation embryos to platelet activating factor (PAF)', Reproduction, Fertility and Development, vol. 4, no. 4, pp. 387-387.
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Platelet activating factor (PAF) is an ether phospholipid produced by preimplantation embryos of a number of species. Production of PAF by embryos has been measured by detecting thrombocytopenia in a splenectomized mouse bioassay, platelet aggregation bioassays in vitro and a specific radioimmunoassay. Production is highly variable and is adversely affected by culture in vitro. It has, however, been correlated with morphology, development rates in vitro and the pregnancy potential of embryos following transfer. Investigations using PAF-antagonists have established an essential role for PAF in early pregnancy. Together with studies that have shown PAF to have direct effects on embryonic metabolism during culture in vitro, these observations suggest that PAF acts as an embryonic autocoid. Hence, a major site of action for embryo-derived PAF in vivo is the embryo itself. Supplementation of embryo culture media with PAF had no effect on the rate of development in vitro of 2-cell mouse embryos through to the blastocyst stage. However, PAF increased cell numbers of blastocysts cultured from the 2-cell stage and the mitotic index of embryos at both the 8-cell and blastocyst stages. Supplementation of culture media with PAF has also been shown to increase the implantation potential of both mouse and human embryos cultured in vitro. In the mouse, the effect of PAF in enhancing implantation rates was most evident when the developmental potential of untreated embryos was suboptimal. These observations suggest that the production of embryo-derived PAF is one limiting factor in maintaining the viability of embryos cultured in vitro.
SAMBROOK, P & NGUYEN, T 1992, 'Vertebral Osteoporosis in Rheumatoid Arthritis Patients: Effect of Low Dose Prednisone Therapy', Rheumatology, vol. 31, no. 8, pp. 573-573.
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Wang, H, Rosenfeld, D, Braun, M & Yan, H 1992, 'An efficient algorithm for MR image reconstruction and compression.', Australas Phys Eng Sci Med, vol. 15, no. 3, pp. 133-137.
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In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be efficiently compressed using the discrete cosine transform (DCT). We present here a method of using DCT to treat the sampled data, which combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.
Wang, H, Rosenfeld, D, Braun, M & Yan, H 1992, 'Compression and reconstruction of MRI images using 2D DCT', Magnetic Resonance Imaging, vol. 10, no. 3, pp. 427-432.
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In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be compressed using the discrete cosine transform (DCT). We present here a method of treating the data that combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues. © 1992.
WATTERSON, PA, ZHU, JG & RAMSDEN, VS 1992, 'OPTIMIZATION OF PERMANENT-MAGNET MOTORS USING FIELD CALCULATIONS OF INCREASING PRECISION', IEEE TRANSACTIONS ON MAGNETICS, vol. 28, no. 2, pp. 1589-1592.
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An algorithm is given for the fast optimization over a constrained domain of an objective function calculated iteratively. To apply the algorithm to optimizing the efficiency of permanent magnet synchronous motors, an iterative magnetic field calculatio
