We report observations of several deuterated species in the dark clouds L134N and TMC1, and in particular of NH2D (deuterated ammonia). NH2D has been detected for the first time towards the dense core TMC1-N and very strong emission has been confirmed towards L134N. The deuterium fractionation is very different in these two clouds, with abundance ratio [NH2D]/[NH3]∼ 0.1 and ∼ 0.02, [N2D]/[N2H]∼...

We present the first results from a time-dependent chemical model to include a gas-phase reaction scheme for producing doubly-deuterated species. Under normal conditions the formation of these species is inefficient. However, when the effects of the freeze out of gas phase species onto grains is included in the chemistry we find that the fractionation of both singly and doubly deuterated specie...

the optimal fractionation schedule for radiotherapy of head and neck cancer has been controversial. the objective of this randomized trial was to test the efficacy of hyperfractionation vs. standard fractionation. patients with squamous cell carcinoma of head and neck organs were randomly assigned to receive radiotherapy delivered with a) standard fractionation at 2 gy/fraction/day, 5 days/week...