![]() Once created the gates can be modified by clicking on the intersection point and dragging it. ![]() Flowjo will then curve the quads based on the intensity of the axes beyond the intersection point. Once you select the Curly Quad icon a set of curled quads will appear on your Graph Window. As you move the mouse around the screen the shape of the quadrants will change to match the intensity. The lines below and to the left of the intersection point will always be straight so that the user may indicate where the upper limits of background fluorescence are, which makes this an effective tool to use with FMO controls. To use the Curly Quad gating tool both parameters must be fluorescent. ![]() Selecting curly quadrantsĬurly quadrants can be selected from the gating tool bar at the top of the graph window as shown in the figure below. Each compensated fluorescence parameter in an FCS file has a bivariate detection limit represented by the formula p2=a*p1^0.5 +b, where p1 and p2 are the two parameters in the plot, and a is a parameter modeling curliness from secondary PMT noise, and b models background fluorescence. FlowJo still shows the quads as “curly” even on a log-log plot for stylistic reasons. Click here for a paper by Mario Roederer discussing the theory behind photon counting error and the 1:2 scale.Ī curly quad is a non rectangular gate based on the error profiles of photomultiplier tubes (PMT). Photo counting error is proportional to the square root of the intensity, so curly quads curve upward when one parameter is displayed on a log scale, and could be represented as a straight line with a slope of 1:2 when both parameters are displayed on a logarithmic scale. It is useful for data that exhibits spread due to photon counting error, which includes almost all fluorescent parameters. The curly quadrant tool is a gating tool that creates a quadrant gate with curved arms. Curly quad gates are designed to account for the error introduced by intensely fluorescent data. Spectral spreading affecting your data? FlowJo v10 has the cure. ![]()
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