29 research outputs found
Weisskopf-Wigner Decay Theory for the Energy-Driven Stochastic Schr\"odinger Equation
We generalize the Weisskopf-Wigner theory for the line shape and transition
rates of decaying states to the case of the energy-driven stochastic
Schr\"odinger equation that has been used as a phenomenology for state vector
reduction. Within the standard approximations used in the Weisskopf-Wigner
analysis, and assuming that the perturbing potential inducing the decay has
vanishing matrix elements within the degenerate manifold containing the
decaying state, the stochastic Schr\"odinger equation linearizes. Solving the
linearized equations, we find no change from the standard analysis in the line
shape or the transition rate per unit time. The only effect of the stochastic
terms is to alter the early time transient behavior of the decay, in a way that
eliminates the quantum Zeno effect. We apply our results to estimate
experimental bounds on the parameter governing the stochastic effects.Comment: 29 pages in RevTeX, Added Note, references adde
Factors influencing accumulation of potato glycoalkaloids and their potential manipulation in tuber pathogen control
SIGLEAvailable from British Library Document Supply Centre-DSC:DX197265 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
A field vaccine trial in Tanzania demonstrates partial protection against malignant catarrhal fever in cattle
Malignant catarrhal fever (MCF) is a fatal lymphoproliferative disease of cattle that, in East Africa, results from transmission of the causative virus, alcelaphine herpesvirus 1 (AlHV-1), from wildebeest. A vaccine field trial involving an attenuated AlHV-1 virus vaccine was performed over two wildebeest calving seasons on the Simanjiro Plain of northern Tanzania. Each of the two phases of the field trial consisted of groups of 50 vaccinated and unvaccinated cattle, which were subsequently exposed to AlHV-1 challenge by herding toward wildebeest. Vaccination resulted in the induction of virus-specific and virus-neutralizing antibodies. Some cattle in the unvaccinated groups also developed virus-specific antibody responses but only after the start of the challenge phase of the trial. PCR of DNA from blood samples detected AlHV-1 infection in both groups of cattle but the frequency of infection was significantly lower in the vaccinated groups. Some infected animals showed clinical signs suggestive of MCF but few animals went on to develop fatal MCF, with similar numbers in vaccinated and unvaccinated groups. This study demonstrated a baseline level of MCF-seropositivity among cattle in northern Tanzania of 1% and showed that AlHV-1 virus-neutralizing antibodies could be induced in Tanzanian zebu shorthorn cross cattle by our attenuated vaccine, a correlate of protection in previous experimental trials. The vaccine reduced infection rates by 56% in cattle exposed to wildebeest but protection from fatal MCF could not be determined due to the low number of fatal cases