108 research outputs found
On the APM power spectrum and the CMB anisotropy: Evidence for a phase transition during inflation?
Adams et al. (1997b) have noted that according to our current understanding
of the unification of fundamental interactions, there should have been phase
transitions associated with spontaneous symmetry breaking {\em during} the
inflationary era. This may have resulted in the breaking of scale-invariance of
the primordial density perturbation for brief periods. A possible such feature
was identified in the power spectrum of galaxy clustering in the APM survey at
the scale Mpc^{-1} and it was shown that the secondary acoustic
peaks in the power spectrum of the CMB anisotropy should consequently be
suppressed. We demonstrate that this prediction is confirmed by the recent
Boomerang and Maxima observations, which favour a step-like spectral feature in
the range Mpc^{-1}, independently of the similar previous
indication from the APM data. Such a spectral break enables an excellent fit to
both APM and CMB data with a baryon density consistent with the BBN value. It
also allows the possibility of a matter-dominated universe with zero
cosmological constant, which we show can now account for even the evolution of
the abundance of rich clusters.Comment: 11 pages (LaTeX, mn.sty) incl. 9 eps figs; small changes to match
version accepted for publication in MNRA
Genome selection in fruit breeding: application to table grapes
ABSTRACT Genomic selection (GS) has recently been proposed as a new selection strategy which represents an innovative paradigm in crop improvement, now widely adopted in animal breeding. Genomic selection relies on phenotyping and high-density genotyping of a sufficiently large and representative sample of the target breeding population, so that the majority of loci that regulate a quantitative trait are in linkage disequilibrium with one or more molecular markers and can thus be captured by selection. In this study we address genomic selection in a practical fruit breeding context applying it to a breeding population of table grape obtained from a cross between the hybrid genotype D8909-15 (Vitis rupestris × Vitis arizonica/girdiana), which is resistant to dagger nematode and Pierce’s disease (PD), and ‘B90-116’, a susceptible Vitis vinifera cultivar with desirable fruit characteristics. Our aim was to enhance the knowledge on the genomic variation of agronomical traits in table grape populations for future use in marker-assisted selection (MAS) and GS, by discovering a set of molecular markers associated with genomic regions involved in this variation. A number of Quantitative Trait Loci (QTL) were discovered but this method is inaccurate and the genetic architecture of the studied population was better captured by the BLasso method of genomic selection, which allowed for efficient inference about the genetic contribution of the various marker loci. The technology of genomic selection afforded greater efficiency than QTL analysis and can be very useful in speeding up the selection procedures for agronomic traits in table grapes
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