Mark Swan

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Human spermatozoa were prepared by swim-up from semen into in-vitro fertilization (IVF) culture medium, and their movement recorded by videomicrography using NTSC video to give 60 images/s on freeze-frame playback. Trajectories in which spermatozoa appeared to switch from one type of motility pattern to another (from non-hyperactivated to transitional or(More)
For technical reasons sperm head movement is assessed in kinematic analysis, while flagellar movement is the determining factor of head movement, not vice versa. It follows then that the development of new kinematic values to describe the movement of capacitating human spermatozoa should include the analysis of their flagellar movement. The aim of this(More)
—Power has recently been recognized as one of the major obstacles in fielding a Peta-FLOPs class system. To reach Exa-FLOPs, the challenge will certainly be compounded. In this paper we will discuss a number of High Performance Computing power related topics. We first describe our implementation of a scalable power measurement framework that has enabled us(More)
While head centroid-derived kinematic values have been determined for the trajectories of hyperactivated human spermatozoa, the definitions are not robust with respect to image sampling frequency and track analysis methods. The determination of the fractal dimension of a trajectory has been suggested as an alternative descriptive parameter for(More)
Hyperactivation is a concomitant of eutherian sperm capacitation, characterized by the development of high amplitude flagellar waves with a corresponding increase in velocity. In humans, kinematic values have been derived which describe the movement characteristics of spermatozoa analysed at 30 images/s. However, these values are frame rate-dependent, and(More)
Accessory fibers in most sperm surround the axoneme so that their function in propulsion is difficult to assess. In the sperm of the toad Bufo marinus, an accessory fiber is displaced from the axoneme, being connected to it by the thin undulating membrane in such a way that the movement of axoneme and accessory fiber can be viewed independently. The axoneme(More)
In unipolar cells of Spirillum volutans, the flagellar rotation frequency is halved, approximately, when the flagellar bundle reorientates to rotate about the cell body and reverse the swimming direction. The viscous drag resulting from a concomitant increase in flagellar wave amplitude is probably responsible for the reduced frequency of flagellar rotation.
The kinematic values which are determined relative to the average path by computer-aided sperm analysis (CASA) instruments are reliant upon the algorithm used for track smoothing, and therefore may differ depending upon the shape and complexity of the trajectories analysed. To overcome this potential source of error in the identification of particular(More)
It is known that image sampling frequency affects sperm kinematic values, although no study has considered the relative effect upon hyperactivated and non-hyperactivated spermatozoa. We determined the relative effect of image sampling frequency on the classification of capacitating human spermatozoa, using the established kinematic measures as well as a(More)
In the procedure described, demembranated ram sperm models were treated to decondense their nuclei, and the movement of their sperm tails was then reactivated. The duration of movement was sustained for more than 30 min, with a tail-wave frequency of up to 14 Hz. Decondensed sperm models adhered to each other and to the slide; but adherence was prevented by(More)