Cross correlation curve

Fig. 7.6. Guide and passenger strand loading into RISC in the cytoplasm and nucleus. Normalized cross-correlation in the cytoplasm filled boxes) and nucleus open boxes) of EGFP-Ago2 and Cy5 labeled passenger (a) or guide strand (b) of siTK3 for several time points after injection. The bottom graphs display the corresponding cross-correlation curves...

By analysing the photon data fluorescence decay curves and PCS curves are obtained. The decay curves of the individual detectors are obtained by building up the histograms of the micro times, fluorescence correlation curves of the individual detectors are obtained by correlating the macro times of the photons of these detectors. Cross-correlation curves are obtained by correlating the macro time of the photons of different detectors. The (unnormalised) autocorrelation function G( t) of an analog signal I(t) is... 

Figure 24.14 Ion signals for Ba FCH3 (a) and BaF(b) as a function of the delay time t between the pump pulse at 618 nm and probe pulse at 400 nm. The solid lines represent the theoretical fit curves, which in (b) were obtained by superposition of two contributions (dashed and dotted lines). In (c), the pump wavelength is tuned off-resonantto 636 nm thus, the Ba FCFI signal represents the cross-correlation curve of the laser pulses for the width tl = 130 fs. Reproduced from Farmanara etat Chem. Phys. Lett., 1999, 304 127, with permission of Elsevier...

Figure 16.3 Temporal evolution of the excess fluorescence signal versus delay time. A C-C stretching mode of coumarin 6 is excited. Results for a probe pulse polarized parallel and perpendicular are shown. The broken curve represents the cross correlation curve of both pulses.

Figure 3.2.4.7 Time-resolved spectra for the n = 1 image-potential state on Cu(OOl) for two different excitation photon energies The dashed line indicates the cross-correlation curve (Adapted from Ref [27]).

The latter is excited as for Cu(lll), but for the surface state, Hvb is absorbed before Hva- The exponential decays (indicated by straight Hnes in the semilogarithmic plot of Figure 3.2.4.6) appear on different sides relative to the cross-correlation curve. The assignment of the excitation sequence is straightforward because the probe pulse must come after the pump pulse. 

To prevent possible bias from the relative abundance of immunolabeled objects during quantification, the cross-correlation curve is normaUzed by dividing all cross-correlation values by the maximum value in the curve. This normalization provides an unbiased indicator of proximity between two populations of labeled puncta. In this analysis, a sharp drop of the normalized curve would indicate a close spatial relationship, while a slow drop, a further and weak relationship (Fig. 5). 

Fig. 5 Colocalization analyses In array tomography Absolute and normalized cross-correlation analyses of pixels, (a) Schematic example Illustrating the absolute cross-correlation analysis of pixels. Two populations of Immunolabeled puncta colocalize (black and grey dots), and therefore their overlapping pixels are correlated. In this analysis, the extinction of this correlation is studied by arbitrarily increasing the physical distance between these two populations of dots (optical channels). If these labeled puncta colocalize, they would present a maximum value of correlation at no shift (original aligned image) followed by a subsequent drop in correlation values as the distance between both channels increases (image displacement). In the case that both populations of labeled puncta do not colocalize at all, a flat line is obtained after this analysis (dashed lind). Since the cross-correlation analysis could be biased by the relative abundance of labeled puncta, curves obtained in a are normalized by their respective maximum value of cross-correlation (b). These normalized cross-correlation curves represent a magnitude of proximity between the paired populations of labeled puncta. If the curve drops sharply, that Indicates a close relationship (b, solid lind), while if it drops slowly that indicates a further and weak relationship (b, dashed line)...

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