نتایج جستجو برای: biological half

تعداد نتایج: 643486  

Journal: :Japanese Journal of Physiological Psychology and Psychophysiology 1993

Journal: :Physical review letters 2006
Z W Barber C W Hoyt C W Oates L Hollberg A V Taichenachev V I Yudin

We report direct single-laser excitation of the strictly forbidden (6s2)1S0 <--> (6s6p)3P0 clock transition in 174Yb atoms confined to a 1D optical lattice. A small (approximately 1.2 mT) static magnetic field was used to induce a nonzero electric dipole transition probability between the clock states at 578.42 nm. Narrow resonance linewidths of 20 Hz (FWHM) with high contrast were observed, de...

1994
M. E. J. Newman B. W. Roberts

We present a new model for extinction in which species evolve in bursts oràvalanches', during which they become on average more susceptible to environmental stresses such as harsh climates and so are more easily rendered extinct. Results of simulations and analytic calculations using our model show a power-law distribution of extinction sizes which is in reasonable agreement with fossil data. W...

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