66 research outputs found
Spectroscopic Observations of Several Stars Toward the Bok Globule B361
Low dispersion spectroscopic observations have been made of six of the stars toward the Bok globule B361 in order to improve the reliability of the distance to this dark cloud. Five of the six stars have been selected from Schmidt (1975) to confirm and supplement his Photometric data. The results of our MK classification of these stars reduce the uncertainty of the luminosity of the stars as well as they agree well with those by Schmidt in spectral type. Supplemented by our luminosity class estimation, Schmidt\u27s data are used to re-evaluate the distances to the stars. The resultant distance-extinction diagram indicates a more reliable distance to B361 of 400 pc
The star-forming core of Monoceros R2
Publisher's version/PDFThe central region of the Monoceros R2 molecular cloud has been studied using molecular line maps, maps in continuum emission, and an M-band (4.7 [micrometres]) absorption spectrum toward Mon R2 IRS 3. Maps were made in the emission lines CO (3-2) H[subscript 2]CO (5[subscript 1.5]-4[subscript 1.4), and HCN (4-3), all with a 14" beam size. CO (2-1) and [superscript 13]CO (3-2) spectra were obtained at a dozen positions. Maps of continuum emission were made at 1300 [micrometres] (25" resolution), 1100 [micrometres] (20" resolution), 800 [micrometres] (14" resolution), and 450 [micrometres] (14" resolution). The M-band spectrum of IRS 3 has a velocity resolution of 5.2 km s[superscript -1] and shows fundamental vibrational band absorption lines of CO and [superscript 13]CO over a range of rotational states. The CO map has numerous intensity peaks which, if interpreted as clumps, have masses from 0.1 to 3 M [subscript circled dot]. The large velocity dispersion of these structures implies that they cannot be gravitationally bound. The brightest CO-emitting gas shows no bipolar distribution with velocity. Diffuse CO-emitting gas with low velocities does have a generally bipolar distribution, but there are no collimated lobes pointing to a particular source. We conclude that the source (or sources) of the very extended Mon R2 outflow is (are) now inactive. The highest velocity gas is found toward the embedded young stellar object IRS 3, suggesting that IRS 3 is the source of a compact outflow, unresolved at our 14" resolution. The presence of blueshifted CO in the absorption spectrum supports the interpretation of IRS 3 as an outflow source. The H[subscript 2]CO and HCN maps demonstrate that much of the dense gas is distributed within three structures having different velocities. The fundamental band absorption lines of [superscript 13]CO show two gas temperatures in the line of sight to IRS 3. The colder (45 K) is identified as gas in the clump surrounding IRS 3, which is seen in emission lines of CO, H[subscript 2]CO, and HCN. The warmer (310 K) we interpret as gas very close to IRS 3. From the submillimeter continuum maps we identify 11 clumps whose masses lie in the range 3-10 M [subscript circled dot]. A clump that is prominent in the continuum maps but not in the molecular line maps is attributed to heated dust inside the compact H II region, where molecules have been destroyed
Exome-wide association study to identify rare variants influencing COVID-19 outcomes : Results from the Host Genetics Initiative
Publisher Copyright: Copyright: © 2022 Butler-Laporte et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75–10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.Peer reviewe
Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples
Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts
Paramagnetic Grain Alignment Associated with Internal Friction and the Polarization Efficiency
Alignment mechanisms associated with paramagnetic relaxation are re-investigated for spheroidal dielectric grains. By taking into account the tight coupling of grain axis with angular momentum due to effective dissipation of rotational energy by internal friction, the degree of alignment by paramagnetic torque will be distinctly improved as compared with that by the classical Davis-Greenstein process. Incorporated with new results by Rogers and Martin on the polarizing effectiveness of spheroidal grains, the "improved" DG theory is used to calculate the polarization efficiency due to incompletely aligned grains. It is found that oblate grains with axial ratio of 1/2 or less and size of 0.1μm can explain the observed polarization if the magnetic field strength is ≃3μG in the general interstellar medium where n_H≃1 cm^ and T_g≃100 K. Alignments of suprathermally spinning grains are also investigated for various grain models. The alignment efficiency is found to depend strongly on the frequency of crossover and the grain shape
- …