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Biology Application Brief

Human Inferility

The Solution

Davis and colleagues use DADiSP to help them implement an alternative approach to sperm motion analysis. They believe that their new method gives a more accurate characterization of sperm motion than traditional methods.

Adjustable Averaging

Applying the fixed-length running average (FLRA) analysis method to sperm has the effect of overly smoothing some trajectories and insufficiently smoothing others. These errors are compounded further when scientists try to produce average values for an entire cell population. The new method for analysis pioneered by Dr. Davis and colleagues adapts the width of the running average of a sperm cell's path to the changing wavelengths of the major spatial oscillations of each curvilinear trajectory. This new method of measurement may provide more accurate modeling of sperm paths so that more accurate judgments can be made about the healthiness of the sperm.

Kinematic Data Reduction

A high-speed video camera and recorder running at 200 frames per second make a first observation of sperm swimming in seminal plasma at 37 degrees C. The trajectories are recorded and digitized, then analyzed for kinematic parameters for one second (200 data points). The trajectory data are then imported into PathTool, a program written in the lab, which computes their average lengths and two vectors which are exported to DADiSP for harmonic analysis. These new measurements, which reveal the frequencies and amplitudes that occur in highly irregular motion, are based on fast Fourier transforms (FFTs). They include the fundamental harmonic of motion (HAR), the magnitude of HAR (MAG), and the power bandwidth of HAR (PWB), which are basic window calculations in a DADiSP worksheet.

Exploratory Data Analysis

Dr. Russel Davis states that he considers DADiSP's ease of use "one of its most important features." He says he likes being able to use it to design a number of signal processing pathways to use with different signals: "For exploratory data analysis it is very useful." DADiSP allows Dr. Davis and colleagues to discover patterns and periodicities in sperm motion that until now have been obscured.

DADiSP, an Ingredient for Success

As a result of their findings, Davis and colleagues have recommended vigorous empirical testing of their methods, and have made suggestions for new CASA instruments. Ultimately these research efforts will result in greater refinement of the methods used to investigate infertility, and DADiSP will have been a part of the success.

The Problem