RESUMO
We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be A = 3.1(-1.2)(+1.6) × 10(-8) s(-1) for the first time, which is in good agreement with the theoretical value of 3.37 × 10(-8) s(-1).
RESUMO
Two chemically defined media were developed for the induction of germ tubes in exponential phase cells of Candida albicans. One medium was N-acetyl-D-glucosamine medium which is composed of L-thiazolidine-4-carboxylic acid, L-proline, NaHCO3, sodium acetate, NaH2PO4 and N-acetyl-D-glucosamine. The other one was glucose medium in which N-acetyl-D-glucosamine is exchanged for glucose plus NH4Cl in N-acetyl-D-glucosamine medium. In these media, a high percentage of germ tube forming cells was obtained without a temperature shift. However, starvation of the cells in water at 37 degrees C was a necessary pretreatment to consistently obtain a high percentage of germ tube forming cells. The effect of starvation was remarkable in glucose medium, the percentages of germ tube forming cells among the normal cells and starved cells were 20 and 80, respectively. As for intracellular changes during starvation, a decrease in adenosine triphosphate concentration and an increase in adenosine 3',5'-cyclic monophosphate concentration were observed.
