7 research outputs found
Redshifts and Velocity Dispersions of Galaxy Clusters in the Horologium-Reticulum Supercluster
We present 118 new optical redshifts for galaxies in 12 clusters in the
Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data
were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the
Australian National University at Siding Spring Observatory. After combining 42
previously unpublished redshifts with our new sample, we determine mean
redshifts and velocity dispersions for 13 clusters, in which previous
observational data were sparse. In six of the 13 clusters, the newly determined
mean redshifts differ by more than 750 km/s from the published values. In the
case of three clusters, A3047, A3109, and A3120, the redshift data indicate the
presence of multiple components along the line of sight. The new cluster
redshifts, when combined with other reliable mean redshifts for clusters in the
HRS, are found to be distinctly bi-modal. Furthermore, the two redshift
components are consistent with the bi-modal redshift distribution found for the
inter-cluster galaxies in the HRS by Fleenor et al. (2005).Comment: 13 pages, 3 figures, Accepted to A
Large-Scale Velocity Structures in the Horologium-Reticulum Supercluster
We present 547 optical redshifts obtained for galaxies in the region of the
Horologium-Reticulum Supercluster (HRS) using the 6dF multi-fiber spectrograph
on the UK Schmidt Telescope at the Anglo Australian Observatory. The HRS covers
an area of more than 12deg x 12deg on the sky centered at approximately RA =
03h19m, DEC = -50deg 02amin. Our 6dF observations concentrate upon the
inter-cluster regions of the HRS, from which we describe four primary results.
First, the HRS spans at least the redshift range from 17,000 to 22,500 km s^-1.
Second, the overdensity of galaxies in the inter-cluster regions of the HRS in
this redshift range is estimated to be 2.4, or del rho/ rho ~ 1.4. Third, we
find a systematic trend of increasing redshift along a Southeast-Northwest
(SE-NW) spatial axis in the HRS, in that the mean redshift of HRS members
increases by more than 1500 km s^-1 from SE to NW over a 12 deg region. Fourth,
the HRS is bi-modal in redshift with a separation of ~ 2500 km s^-1 (35 Mpc)
between the higher and lower redshift peaks. This fact is particularly evident
if the above spatial-redshift trend is fitted and removed. In short, the HRS
appears to consist of two components in redshift space, each one exhibiting a
similar systematic spatial-redshift trend along a SE-NW axis. Lastly, we
compare these results from the HRS with the Shapley supercluster and find
similar properties and large-scale features.Comment: 20 pages, 9 figures, accepted to A
2nd Annual Computer & Technology Law Institute
Materials from the 2nd Annual Computer & Technology Law Institute held by UK/CLE in March 2000
The rde-1 gene, RNA interference, and transposon silencing in C. elegans
Double-stranded (ds) RNA can induce sequence-specific inhibition of gene function in several organisms. However, both the mechanism and the physiological role of the interference process remain mysterious. In order to study the interference process, we have selected C. elegans mutants resistant to dsRNA-mediated interference (RNAi). Two loci, rde-1 and rde-4, are defined by mutants strongly resistant to RNAi but with no obvious defects in growth or development. We show that rde-1 is a member of the piwi/sting/argonaute/zwille/eIF2C gene family conserved from plants to vertebrates. Interestingly, several, but not all, RNAi-deficient strains exhibit mobilization of the endogenous transposons. We discuss implications for the mechanism of RNAi and the possibility that one natural function of RNAi is transposon silencing
The major genetic determinants of HIV-1 control affect HLA class I peptide presentation.
Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection