Photon fractional uncertainty

Fig. 7.7. Effects of Poisson photon noise on calculated SE and FRET values. (A) Statistical distribution of number of incoming photons for the mean fluorescence intensities of 5,10, 20, 50, and 100 photons/pixel, respectively. For n = 100 (rightmost curve), the SD is 10 thus the relative coefficient of variation (RCV this is SD/mean) is 10 %. In this case, 95% of observations are between 80 and 120. For example, n — 10 the RCY has increased to 33%. (B) To visualize the spread in s.e. caused by the Poisson distribution of pixel intensities that averaged 100 photons for each A, D, and S (right-most curve), s.e. was calculated repeatedly using a Monte Carlo simulation approach. Realistic correction factors were used (a = 0.0023,/ = 0.59, y = 0.15, <5 = 0.0015) that determine 25% FRET efficiency. Note that spread in s.e. based on a population of pixels with RCY = 10 % amounts to RCV = 60 % for these particular settings Other curves for photon counts decreasing as in (A), the uncertainty further grows and an increasing fraction of calculated s.e. values are actually below zero. (C) Spread in Ed values for photon counts as in (A). Note that whereas the value of the mean remains the same, the spread (RCV) increases to several hundred percent. (D) Spread depends not only on photon counts but also on values of the correction...

Figure 7.18 Mean lifetime vs. the positronium fraction, obtained from the 3-to-2 photon ratio. Down triangles lifetime data without the aperture up triangles with the aperture. Open symbols samples with porogen load > 50% (positronium reaches the Si interface). Line a liner fit to no-aperture for <37% load. Numbers porogen loads in %. A typical error (incl. systematic uncertainties) is shown for 40% porogen load.

Figure 4. The predictions of standard BBN [22], with thermonuclear rates based on the NACRE compilation [24]. (a) Primordial abundances as a function of the baryon-to-photon ratio tj. Abundances are quantified as ratios to hydrogen, except for He which is given in baryonic mass fraction Yp = Ph/Pb-The lines give the mean values, and the surrounding bands give the la uncertainties, (b) The la abundance uncertainties, expressed as a fraction of the mean value p for each q.

Primordial abundances as a function of baryon density PbOt fraction of critical density il b (these two quantities are directly related to the baryon-to-photon ratio ri see text). The widths of the curves give the nuclear physics uncertainties. The boxes specify the ranges of abundances and densities constrained by observation (there is only an upper limit for He from observation) as given in Buries et al. (1999, 2001). The shaded area marks the density range consistent with all observations (Buries et al. 1999,2001). Symbol D represents deuterium, (Reprinted from Tytler... 

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