Mass and Redshift Dependence of Dark Halo Structure

Using a combination of N-body simulations with different resolutions, we study in detail how the concentrations of cold dark matter (CDM) halos depend on halo mass at different redshifts. We confirm that halo concentrations at the present time depend strongly on halo mass, but our results also show marked differences from the predictions of some early empirical models. Our main result is that the mass dependence of the concentrations becomes weaker at higher redshifts, and at z >~ 3 halos of mass greater than 10^{11} Msun/h all have a similar median concentration, c ~ 3.5. While the median concentrations of low-mass halos grow significantly with time, those of massive halos change only little with redshifts. These results are quantitatively in good agreement with the empirical model proposed by Zhao et al. which shows that halos in the early fast accretion phase all have similar concentrations.Comment: 11 pages, including 2 figures and 1 table, publicated in ApJL, the first paper stating the zero mass-dependence of concentrations for massive and/or high redshift dark matter halos, which are still in the fast growth phase, quoted by the second version of ; v2: references corrected to be the same as the published versio

Towards molecular breeding of reproductive traits in cereal crops

The transition from vegetative to reproductive phase, flowering per se, floral organ development, panicle structure and morphology, meiosis, pollination and fertilization, cytoplasmic male sterility (CMS) and fertility restoration, and grain development are the main reproductive traits. Unlocking their genetic insights will enable plant breeders to manipulate these traits in cereal germplasm enhancement. Multiple genes or quantitative trait loci (QTLs) affecting flowering (phase transition, photoperiod and vernalization, flowering per se), panicle morphology and grain development have been cloned, and gene expression research has provided new information about the nature of complex genetic networks involved in the expression of these traits. Molecular biology is also facilitating the identification of diverse CMS sources in hybrid breeding. Few Rf (fertility restorer) genes have been cloned in maize, rice and sorghum. DNA markers are now used to assess the genetic purity of hybrids and their parental lines, and to pyramid Rf or tms (thermosensitive male sterility) genes in rice. Transgene(s) can be used to create de novo CMS trait in cereals. The understanding of reproductive biology facilitated by functional genomics will allow a better manipulation of genes by crop breeders and their potential use across species through genetic transformation

Correspondence. Anomalous cuspids.

Editors: Aug. 1859-July 1865, J. D. White, J. H. McQuillen, G. J. Ziegler.--Aug. 1865-Dec. 1871, J. H. McQuillen, G. J. Ziegler.--Jan. 1872-May 1891, J. W. White.--July 1891-Apr. 1930, E. C. Kirk (with L. P. Anthony, Dec. 1917-Apr. 1930).--May 1930-Dec. 1936, L. P. Anthony.Vols. 1-13 are called "new series."Merged in Jan. 1937 with: Journal of the American Dental Association, ISSN 1048-6364, to form: Journal of the American Dental Association and dental cosmos, ISSN 0375-8451