Abstract: An optical transmitter with a feed-forward compensation is disclosed. The optical transmitter includes a first light source receiving a second electrical signal to convert into a first optical signal, an optical splitter dividing the first optical signal into a second optical signal and a third optical signal, an optical detector converting the third optical signal into a fourth electrical signal, a comparator receiving the fourth electrical signal and a third electrical signal, to produce a fifth electrical signal corresponding to a difference between the third electrical signal and the fourth electrical signal, a second light source converting the fifth electrical signal into a fourth optical signal, and an optical combiner for offsetting a distortion component of the fourth optical signal against the second optical signal to produce a fifth optical signal.

Abstract: Disclosed herein is a multi-band ZigBee transceiver for supporting IEEE 802.15.4 wireless communications. In the multi-band ZigBee transceiver, a Multi-Mode Modem (MMM) selects any one of a European version standard using 860 MHz band, a US version standard using 920 MHz band, and a worldwide version standard using 2.4 GHz ISM band among IEEE 802.15.4 standards. A frequency synthesizing unit variably adjusts a carrier frequency according to the transmission standard. A transmission unit receives a digital modulated signal, low-pass-filters the digital modulated signal with a bandwidth thereof being variably adjusted, and up-converts the filtered digital modulated signal into an RF modulated signal corresponding to the selected transmission channel.

Abstract: Provided herein are human embryonic stem cells and their method of culturing. In one embodiment, the human embryonic stem cells are maintained in an environment containing an extracellular matrix isolated from feeder cells and a conditioned medium pre-conditioned by the feeder cells; the feeder cells are pre-inactivated by either gamma ray radiation or by mitomycin C treatment. The cultured human embryonic stem cells remain substantially undifferentiated and maintain their pluripotency to differentiate into three germ layer cells.

Abstract: The present invention discloses an improved culture system for proliferative and undifferentiated growth of human embryonic stem cells, comprising an extracellular matrix prepared from feeder cells and a conditioned medium preconditioned by feeder cells. This invention also relates to a culture method utilizing the foregoing culture system.