Elastically deformable 3D organs for haptic surgical simulation.

This paper describes a technique for incorporating real-time elastically deformable 3D organs in haptic surgical simulators. Our system is a physically based particle model utilizing a mass-springs-damper connectivity with an implicit predictor to speed up calculations during each time step. The solution involves repeated application of Newton's 2ndd Law of motion: F = ma using an implicit solver for numerically solving the differential equations.

Estimation of the developmental age of the bovine fetus and newborn calf.

Jersey cows from several herds provided 97 fetuses and 24 calves at fixed gestational intervals between 80 and 290 days after conception. The fetuses and calves were killed, weighed and measured and, after dissection, the sizes and weights of a range of skeletal and soft tissues were recorded. Six morphological measurements emerged as most suitable for the determination of developmental age in the normal fetus.

Observations on transplacental infection with bluetongue virus in sheep.

Twenty-four ewes were inoculated with 1 of 2 strains of bluetongue virus type 4 at 40, 60, or 80 days of gestation. Two ewes aborted, 2 ewes died, and 1 was killed during the experiment, but their fetuses were recovered. At term, 2 mummified fetuses, 4 dead lambs, and 17 clinically healthy lambs were produced by 12 sheep, and the remaining 7 sheep were barren.

Border disease of sheep: spinal cord morphometry.

Semi-automated planimetry was used to determine cross-sectional areas of spinal grey and white matter by direct microscopy of paraffin sections of spinal cord from Border disease (BD) and normal lambs at segments C4, C8, T6 and L4. Spinal cord cross-sectional area was significantly reduced in cases of BD produced by either intramuscular or intranasal inoculation of ewes in the first half of pregnancy with Weybridge strains of BD virus. The reduction was apparent at all 4 levels and in both grey and white matter, though the white matter was the more severely affected.

Bovine virus diarrhoea-mucosal disease virus-induced fetopathy in cattle: Efficacy of prophylactic maternal pre-exposure.

Maternal immunity was produced in Jersey heifers by exposing them to bovine virus diarrhoea-mucosal disease virus before conception. In the following pregnancy this immunity protected the fetuses from transplacental infection arising from challenge of the dams at 100 days gestation with homologous virus. Unprotected Jersey heifers showed a high incidence of death and fetal intrauterine growth retardation associated with transplacental viral infection.