Omentalisation of a caudal mediastinal abscess in a dog.

A caudal mediastinal abscess was diagnosed in a 2-year-old German Short-haired Pointer with acute onset of lethargy, pyrexia and tachypnoea. The abscess was managed surgically by median sternotomy, abscess content evacuation and omentalisation of the abscess cavity via the diaphragm. Although surgical management of mediastinal abscesses has been reported previously, this is the first report to describe successful management of the condition in a dog by omentalisation.

Stifle synovial cyst in a Labrador Retriever with concurrent cranial cruciate ligament deficiency.

A seven-year-old Labrador Retriever dog was presented with the complaint of chronic left hindlimb lameness. A diagnosis of partial rupture of the left cranial cruciate ligament with concurrent cranio-medial synovial cyst formation was made. This cystic structure was assumed to be communicating with the stifle joint. There was no evidence of a meniscal tear, but superficial fibrillation of the axial border was present. Surgical excision of the cyst with concurrent treatment of the cranial cruciate ligament deficiency by tibial tuberosity advancement was performed with a successful outcome. Whilst commonly encountered in humans, synovial cysts are uncommon in dogs. To the authors' knowledge this is the first reported case of synovial cyst formation in the stifle of a dog.

Comparative Density Measurements for Solid Specimens Weighing a Few Milligrams.

A density comparison technique previously described has been used to compare the densities of tungsten wires weighing about 1.3 mg to within a few percent error. For larger, less dense specimens the expected random error of a few parts in 104 was confirmed by comparing the known densities of Si and CaF2.

Electric Fields Produced in Cubic Crystals by Point Defects.

Charged point defects in crystals polarize the surrounding ions. These induced dipoles contribute to the electric field in the crystal. In this paper, lattice sums for the calculation of this contribution are given for the NaCl, CsCl, CaF2, and ZnS structures. Various positions for the defect are chosen, and the field evaluated near lattice sites in the vicinity of the defect, with radial (with respect to the defect) displacements of ± 20 percent of the cation-anion distance allowed away from each lattice site. The lattice sums are expressed in power series, including terms up to cubic in the displacements, and the coefficients tabulated.

Surface-Layer Relaxation in the Dielectric Spectrum of CaF2 Doped With GdF3.

CaF2 crystals doped with 0.1 percent GdF3 were observed to develop surface layers when annealed above 700 °C in air, during application of Pt paste electrodes. The conductivity in these surface layers was much higher than in the bulk, due presumably to the large numbers of anion vacancies produced by dissolved oxygen. The presence of these high conductivity surface layers produced a relaxation in the dielectric spectrum with (1) an approximately temperature-independent magnitude, Δκ, (2) a relaxation time controlled by the conductivity of the surface layers, and influenced therefore by heat treatment of the specimen, and (3) an activation energy equal to that for conductivity of the surface layers, about 0.9 eV. This relaxation is sufficiently similar to dielectric relaxations observed previously in ionic crystals and ascribed to defect pairs to suggest that great care must be taken in interpreting dielectric measurements in these materials. What is thought to be dipole relaxation may in fact be due to the presence of thin layers accidentally present on the crystal. There is a marked electrode polarization effect in these crystals. The electrode capacitance at not-too-low frequencies depended upon the frequency and both the number and mobility of the charge carriers with 3/2 power laws.