First Experimental Demonstration of Full-Duplex Optical Communications on a Single Laser Beam

We present the results of the first experimental demonstration a novel communications architecture that will be deployed on a Space Shuttle mission in 2003. This architecture can provide a very lightweight, low power consumption, low data rate communications link between the earth and LEO satellites. A unique characteristic of this system is that it provides full-duplex communications on a single beam is presented. The results of first experiments demonstrating this full duplex communications architecture are presented

Lightweight Optical Wavelength Communications without a Laser in Space

We will present a model for an earth-to-low-earthorbit optical communications system. The system modeled herein is designed to offer a very lightweight, low power consumption, low data rate communications link from LEO satellites. A novel architecture for a free-space optical communications link is presented and analyzed. For the first time, a method that offers full-duplex communications on a single beam is presented. In addition, a novel data format for free-space optical communications is presented. In this system, both the laser and the downlink receiver are located on the ground. The optical elements located on the spacecraft are a simple uplink receiver and a retromodulator. In fact, the laser transmitter for the system is a semiconductor device. We will present a simple feasibility model for the LOWCAL experiment that provides an estimate of the performance capability and identifies major system tradeoffs. Assuming a laser transmitter power of - 7-dB and a communications data rate of 10-kbps, we expect link margins of 17 dB for the downlink. For the uplink, an SC-FSK format is proposed that is invisible to the downlink and provides a link margin of 20 dB

Microvascularization and angiogenic activity of equine corpora lutea throughout the estrous cycle

Corpus luteum growth and endocrine function are closely dependent on the formation of new capillaries. The objectives of this study were to evaluate (i) tissue growth and microvascular development in the equine cyclic luteal structures; (ii) in vitro angiogenic activity of luteal tissues in response to luteotrophic (LH, PGE2) and luteolytic (PGF2[alpha]) hormones and (iii) to relate data to luteal endocrinological function. Our results show that microvascular density was increased in the early and mid luteal phase, followed by a fall in the late luteal phase and a further decrease in the corpus albicans. Hyperplasia of luteal tissue increased until the mid luteal phase and it was followed by tissue regression. Luteal explants were cultured with no hormone added, or with PGF2[alpha], LH, PGE2, LH + PGE2 or LH + PGF2[alpha]. Media conditioned by equine luteal tissue from different stages of the luteal phase were able to stimulate mitogenesis of bovine aortic endothelial cells (BAEC), suggesting the presence of angiogenic activity. No difference was observed among luteal structures on their mitogenic capacity, for any treatment used. Nevertheless, Late-CL conditioned-media with PGF2[alpha] showed a significant decrease in BAEC proliferation (p < 0.05) and LH + PGF2[alpha] a tendency to reduce mitogenesis. Thus, prostaglandin F2[alpha] may play a role on vascular regression of the CL during the late luteal phase in the mare. These data suggest that luteal angiogenesis and vascular regression in the mare are coordinated with the development of non-vascular tissue and might be regulated by many different factors.http://www.sciencedirect.com/science/article/B6T62-4GV9B4H-2/1/2910d2927d48ce58f5dc2ca572bcd7c