Some Unsolved Problems Concerning Bovine Tuberculosis

Attempts to control any infectious disease are aimed at eliminating either the source of infection or the means of its transmission, or at altering the susceptibility of the host to the disease. Since in the treatment of bovine tuberculosis it has not been found practicable to alter the susceptibility of the animal by immunization, or to prevent transmission of the disease by isolating infected cattle, the disease has been attacked by removing the source ofthe infection. This consists of applying the tuberculin test and destroying all cattle that exhibit hypersensitivity to tuberculin

Some Unsolved Problems Concerning Bovine Tuberculosis

Attempts to control any infectious disease are aimed at eliminating either the source of infection or the means of its transmission, or at altering the susceptibility of the host to the disease. Since in the treatment of bovine tuberculosis it has not been found practicable to alter the susceptibility of the animal by immunization, or to prevent transmission of the disease by isolating infected cattle, the disease has been attacked by removing the source of the infection. This consists of applying the tuberculin test and destroying all cattle that exhibit hypersensitivity to tuberculin

Hydronephrosis in Swine

Hydronephrosis is the distention of the renal pelvis and calyces by urine , due to some obstruction along the course of the urinary passage. The obstruction may be in the ureter, the bladder, or the urethra. The term hydronephrosis is often used to include an accompanying hydroureter which develops when the obstruction is below the uretero-pelvic junction. The enlargement of the pelvis and calyces causes atrophy of the adjacent parenchyma. The amount of kidney destruction may vary from merely a flattening of the papillae to complete replacement, leaving but a thin shell of inactive cortex. When there is a superimposed infection and the renal pelvis fills with pus, the condition is called pyonephrosis

Influence of Spin Wave Excitations on the Ferromagnetic Phase Diagram in the Hubbard-Model

The subject of the present paper is the theoretical description of collective electronic excitations, i.e. spin waves, in the Hubbard-model. Starting with the widely used Random-Phase-Approximation, which combines Hartree-Fock theory with the summation of the two-particle ladder, we extend the theory to a more sophisticated single particle approximation, namely the Spectral-Density-Ansatz. Doing so we have to introduce a `screened` Coulomb-interaction rather than the bare Hubbard-interaction in order to obtain physically reasonable spinwave dispersions. The discussion following the technical procedure shows that comparison of standard RPA with our new approximation reduces the occurrence of a ferromagnetic phase further with respect to the phase-diagrams delivered by the single particle theories.Comment: 8 pages, 9 figures, RevTex4, accepted for publication in Phys. Rev.