Plant genetic resources: Advancing conservation and use through biotechnology

Conservation and sustainable use of genetic resources is essential to meet the demand for future food security. Advances in biotechnology have generated new opportunities for genetic resources conservation and utilization. Techniques like in vitro culture and cryopreservation have made it easy to collect and conserve genetic resources, especially of species that are difficult to conserve as seeds. While technologies like enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) have provided tools that are more sensitive and pathogen specific for seed health testing, tissue culture methods are now widely applied for elimination of systemic diseases such as viruses for safe exchange of germplasm. Molecular markers are increasingly used for screening of germplasm to study genetic diversity, identify redundancies in the collections, test accession stability and integrity, and resolve taxonomic relationships. The technology is also expanding the scope of genetic resources utilization. Key Words: Biotechnology, conservation, plant genetic resources. African Journal of Biotechnology Vol.3(2) 2004: 136-14

Do Hydrogen-Deficient Carbon Stars Have Winds?

We present high resolution spectra of the five known hydrogen-deficient carbon (HdC) stars in the vicinity of the 10830 angstrom line of neutral helium. In R Coronae Borealis (RCB) stars the He I line is known to be strong and broad, often with a P Cygni profile, and must be formed in the powerful winds of those stars. RCB stars have similar chemical abundances as HdC stars and also share greatly enhanced O-18 abundances with them, indicating a common origin for these two classes of stars, which has been suggested to be white dwarf mergers. A narrow He I absorption line may be present in the hotter HdC stars, but no line is seen in the cooler stars, and no evidence for a wind is found in any of them. The presence of wind lines in the RCB stars is strongly correlated with dust formation episodes so the absence of wind lines in the HdC stars, which do not make dust, is as expected.NSFScience and Technology FacilitiesCouncilthe National Research CouncilCONICYTAustralian Research CouncilMinistﾴerio da Ciﾴencia e TecnologiaSECYTMcDonald Observator

Dynamic Analysis of Foundations for Heavy Duty Diesel Engines

Coupled motion analysis of Machine-Foundation-Soil systems subjected to periodic dynamic forces and moments which are of general nature (both in amplitudes and periods) has been carried out using Fourier analysis and numerical techniques. Free vibration as well as forced vibration analysis in all the coupled and uncoupled modes of the system has been presented. The procedure is illustrated in the case of an eight cylinder heavy duty diesel engine generator assembly and results have been graphically shown in terms of frequency ratios and maximum steady state responses in the all the relevant modes of vibration