Declan C. Hughes

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BACKGROUND The zona pellucida (ZP) is an extracellular glycoprotein matrix which surrounds all mammalian oocytes. Recent data have shown the presence of four human zona genes (ZP1, ZP2, ZP3 and ZPB). The aim of the study was to determine if all four ZP proteins are expressed and present in the human. METHODS cDNA derived from human oocytes were used to(More)
A functional zona pellucida is critical for both fertilization and the early stages of embryo development. Recent data from genomic and proteomic studies have questioned our simplistic view of the zona as being composed of three proteins whose functions are clearly defined. In the human, for example, the zona pellucida is composed of four proteins, not(More)
A novel approach for vision sensing and vision-based proximity navigation of spacecraft is presented. We have recently invented a new sensor which utilizes area Position Sensing Diode (PSD) photodetectors in the focal plane of an omni-directional camera. These analog detectors inherently centroid incident light, from which a line of sight vector can be(More)
Autonomous in-flight aerial refueling is an important capability for the future deployment of unmanned aerial vehicles, because they will likely be ferried in flight to overseas theaters of operation instead of being shipped unassembled in containers. A reliable sensor, capable of providing accurate relative position measurements of sufficient bandwidth, is(More)
The tectorial membrane is an extracellular matrix of the inner ear that contacts the stereocilia bundles of specialized sensory hair cells. Sound induces movement of these hair cells relative to the tectorial membrane, deflects the stereocilia, and leads to fluctuations in hair-cell membrane potential, transducing sound into electrical signals.(More)
The multiple enzymatic activities and functions of transglutaminase type 2 (TG2) may be attributed to alternative TG2 molecules produced by differential splicing of TG2 mRNA. Different RNA transcripts of the human TG2 gene (TGM2) have been identified, but the expression of TG2 multiple transcripts has never been systematically addressed. We have confirmed(More)
This paper presents a robust and efficient approach for relative navigation and attitude estimation of spacecraft flying in formation. This approach uses measurements from a new optical sensor that provides a line of sight vector from the master spacecraft to the secondary satellite. The overall system provides a novel, reliable, and autonomous relative(More)
A structured model reference adaptive control law has been developed for vision based spacecraft rendezvous and docking problem. A highly accurate relative motion of chaser spacecraft can be estimated by processing the reliable high bandwidth measurements of newly developed VISNAV sensor through a nonlinear geometric estimation process. The adaptive control(More)
A structured model reference adaptive control law has been developed for vision based spacecraft rendezvous and docking problem. A highly accurate relative motion of chaser spacecraft can be estimated by processing the reliable high bandwidth measurements of newly developed VISNAV sensor through a nonlinear geometric estimation process. The adaptive control(More)