Determination of the local group gravitational acceleration using all-sky red-shift surveys

A consolidation of the Local Group velocity as inferred from measurements of the Cosmic Microwave Background, and that inferred from gravitational arguments, is of major importance to modern cosmology. Agreement between the two lends strength to modern ideas of structure formation, and can in principle, be used to estimate the matter density parameter, Ωm. Measurement of the change of the Local Group velocity with respect to increasingly distant objects can also be used as a probe of the mass of nearby structures.Modern methods of velocity determination employ information about the local matter density to construct an estimate of the local gravitational field. The most effective current method of probing the local matter density is by using all-sky galaxy redshift surveys to map the 3-dimensional distribution of nearby galaxies, and then use these galaxies to infer the distribution of matter throughout the local Universe.However, any practical determination of the Local Group velocity is fraught with errors. Among these are: distortion effects on the data introduced by using an galaxy’s redshift as a measure of its distance; sampling effects caused by the approximate representation of a continuous mass distribution by a sample of discrete galaxies; intrinsic uncertainty caused by only sampling a nearby finite subset of the (effectively infinite) mass distribution; and the uncertainty in the determination of a correction for non-linear effects caused by nearby massive structures.This thesis aims to give a definitive measure of the velocity of the Local Group from gravitational arguments while attempting to minimise errors in the calculation. Iterative techniques are used to converge on a self consistent solution to the Local Group velocity and surrounding spatial galaxy distribution. To minimise intrinsic survey error, a new dataset— the Behind The Plane (B T P ) galaxy redshift survey has been completed and analysed. The BTP is the low-latitude extension to the previously completed Point Source Catalogue redshift (PSCz) survey of galaxies. Near-infrared and radio techniques were used to identify and measure optically obscured galaxies that were excluded from the PSCz, increasing the overall sky coverage from 84% to 93%. This high degree of sky coverage makes the PSCz + BTP the best available dataset for dynamical studies of the local Universe. The reduction of the gap in sky coverage significantly reduces uncertainty in dynamical predictions, especially as the missing strip behind the Milky Way is known to include the Great Attractor.The major result of this work is the possible discovery o f an unexpectedly large mass concentration beyond the Great Attractor, at an approximate distance of cz = 20,000kms-1 in the direction l = 300,b = 0. The misalignment between the inferred Local Group velocity vector and the CMB temperature dipole significantly increases, and β parameter estimates yield inconsistency with many other current and reliable estimates in the literature, if this structure is excluded. Upon the inclusion of this concentration, estimates for the Local Group velocity center upon I = 245, b = 30, and yield a value of βIRAS = 0-65 ± 0.01. Directional misalignment is consistent to within 2-σ, but is robust across significant variation in both the data and calculation method applied

Density and Velocity Fields from the PSCz Survey

We present the results for the predicted density and peculiar velocity fields and the dipole from the PSCz survey of 15,000 IRAS galaxies over 84% of the sky. We find a significant component to the dipole arising between 6000 and 15,000 km/s, but no significant component from greater distances. The misalignment with the CMB is 20 degrees. The most remarkable feature of the PSCz model velocity field is a coherent large-scale flow along the baseline connecting Perseus-Pisces, the Local Supercluster, Great Attractor and the Shapley Concentration. We have measured the parameter beta using the amplitude of the dipole, bulk flow and point by point comparisons between the individual velocities of galaxies in the MarkIII and SFI datasets, and the large-scale clustering distortion in redshift space.All our results are consistent with beta = 0.6 +- 0.1.Comment: 8 pages, 8 figures. To appear in 'Towards an Understanding of Cosmic Flows', Victoria, July 1999, eds Courteau,S., Strauss,M., Willick,J. PAS

Comparative transcriptome in large-scale human and cattle populations:Comparative transcriptome in humans and cattle

BACKGROUND: Cross-species comparison of transcriptomes is important for elucidating evolutionary molecular mechanisms underpinning phenotypic variation between and within species, yet to date it has been essentially limited to model organisms with relatively small sample sizes. RESULTS: Here, we systematically analyze and compare 10,830 and 4866 publicly available RNA-seq samples in humans and cattle, respectively, representing 20 common tissues. Focusing on 17,315 orthologous genes, we demonstrate that mean/median gene expression, inter-individual variation of expression, expression quantitative trait loci, and gene co-expression networks are generally conserved between humans and cattle. By examining large-scale genome-wide association studies for 46 human traits (average n = 327,973) and 45 cattle traits (average n = 24,635), we reveal that the heritability of complex traits in both species is significantly more enriched in transcriptionally conserved than diverged genes across tissues. CONCLUSIONS: In summary, our study provides a comprehensive comparison of transcriptomes between humans and cattle, which might help decipher the genetic and evolutionary basis of complex traits in both species. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13059-022-02745-4

A multi-tissue atlas of regulatory variants in cattle:Cattle Genotype-Tissue Expression Atlas

Characterization of genetic regulatory variants acting on the livestock gene expression is essential for interpreting the molecular mechanisms underlying traits of economic value and for increasing the rate of genetic gain through artificial selection. Here we build a Cattle Genotype-Tissue Expression atlas (CattleGTEx) as part of the pilot phase of Farm animal GTEx (FarmGTEx) project for the research community based on publicly available 7,180 RNA-Seq samples. We describe the transcriptomic landscape of over 100 tissues/cell types and report hundreds of thousands of genetic associations with gene expression and alternative splicing for 23 distinct tissues. We evaluate the tissue-sharing patterns of these genetic regulatory effects, and functionally annotate them using multi-omics data. Finally, we link gene expression in different tissues to 43 economically important traits using both transcriptome-wide association and colocalization analyses to decipher the molecular regulatory mechanisms underpinning such agronomic traits in cattle

COVID-19 Host Genetics Initiative. A first update on mapping the human genetic architecture of COVID-19

The COVID-19 pandemic continues to pose a major public health threat, especially in countries with low vaccination rates. To better understand the biological underpinnings of SARS-CoV-2 infection and COVID-19 severity, we formed the COVID-19 Host Genetics Initiative1. Here we present a genome-wide association study meta-analysis of up to 125,584 cases and over 2.5 million control individuals across 60 studies from 25 countries, adding 11 genome-wide significant loci compared with those previously identified2. Genes at new loci, including SFTPD, MUC5B and ACE2, reveal compelling insights regarding disease susceptibility and severity.</p