Terahertz frequency standard based on three-photon coherent population trapping.

A scheme for a terahertz frequency standard based on three-photon coherent population trapping in stored ions is proposed. Assuming the propagation directions of the three lasers obey the phase matching condition, we show that stability of few 10(-14) at 1 s can be reached with a precision limited by power broadening to 10(-11) in the less favorable case. The referenced terahertz signal can be propagated over long distances, the useful information being carried by the relative frequency of the three optical photons.

Linewidth reduction by 6 orders of magnitude of a broad-area 729-nm diode laser.

Diode lasers with a power output superior to 100 mW are in widespread use in medical as well as research applications. However, for such diodes lasing oscillation generally occurs simultaneously in several longitudinal and transverse modes that are unsuitable for high-resolution spectroscopy. We spectrally narrow a 100-mW broad-area diode laser by first using an extended cavity and then an electrical feedback produced by a Pound-Drever-Hall stabilization on a low-finesse reference cavity.

Maternal inheritance of a chloroplast microsatellite marker in controlled hybrids between Fraxinus excelsior and Fraxinus angustifolia.

Restriction fragment length polymorphism, polymerase chain reaction-restriction fragment length polymorphism and simple sequence repeat (SSR or microsatellites) analyses were performed to detect chloroplast DNA polymorphisms between two ash species, Fraxinus excelsior and F. angustifolia. Only one SSR locus was found to be polymorphic, confirming the very close relatedness of these species.

Source of resistance against Ralstonia solanacearum in fertile somatic hybrids of eggplant (Solanum melongena L.) with Solanum aethiopicum L.

Solanum aethiopicum is reported to carry resistance to bacterial wilt disease caused by Ralstonia solanacearum, which is one of the most important diseases of eggplant (Solanum melongena). These two species can sexually be crossed but the fertility of their progeny is very low. In order to transfer the resistance and improve the fertility, somatic hybrids between S.

Resistance to bacterial wilt in somatic hybrids between Solanum tuberosum and Solanum phureja.

Somatic hybrid plants were produced after protoplast electrofusion between a dihaploid potato, cv. BF15, and a wild tuber-bearing relative, Solanum phureja, with a view to transferring bacterial wilt resistance into potato lines. A total of ten putative hybrids were selected.