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UBOAT. Norman Stein CCP4 Daresbury Laboratory York 27/3/07. TRUNCATE replacement. Converts I’s to F’s Negative input I’s give positive output I’s, F’s Calculates Statistics: Moments of I Wilson plot Cumulative intensity distribution
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UBOAT Norman Stein CCP4 Daresbury Laboratory York 27/3/07
TRUNCATE replacement • Converts I’s to F’s • Negative input I’s give positive output I’s, F’s • Calculates Statistics: Moments of I Wilson plot Cumulative intensity distribution Detection of anisotropy (Yorgo Modis)
Mathematical Detail • Use Bayesian statistics • Combine prior knowledge and observations to give the posterior distribution. • Prior is the Wilson distribution • p(J) = (1/Σ) exp( - J/ Σ) if J ≥ 0 (Acentric) • p(J) = 0 if J < 0 • p(J) = 1/(2πΣJ) exp( - J / 2Σ) if J ≥ 0(Centric) • p(J) = 0 if J < 0 • J is intensity, Σ is the mean intensity in the resolution shell S French and K S Wilson ActaCryst. A34, 517 (1978)
K S Wilson A J C Wilson
Output intensity vs Input intensity (acentric) I/σ J/σ – σ/Σ
Output Amplitude vs Input Intensity (acentric) F/σ½ J/σ – σ/Σ
FUTURE WORK • Twinning (H test initially) • Anisotropy (Clipper/Popov and Bourenkov) • Multiple data sets