Titanium and Iron in the Cassiopeia A Supernova Remnant Vance, Gregory S.; Young, Patrick A.; Fryer, Christopher L. ...
Astrophysical journal/The Astrophysical journal,
06/2020, Letnik:
895, Številka:
2
Journal Article
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Mixing above the proto-neutron star is believed to play an important role in the supernova engine, and this mixing results in a supernova explosion with asymmetries. Elements produced in the ...innermost ejecta, e.g., 56Ni and 44Ti, provide a clean probe of this engine. The production of 44Ti is particularly sensitive to the exact production pathway and, by understanding the available pathways, we can use 44Ti to probe the supernova engine. Using thermodynamic trajectories from a three-dimensional supernova explosion model, we review the production of these elements and the structures expected to form under the "convective-engine" paradigm behind supernovae. We compare our results to recent X-ray and γ-ray observations of the Cassiopeia A supernova remnant.
We present the isotope yields of two post-explosion, three-dimensional 15 core-collapse supernova models, 15S and 15A, and compare them to the carbon, nitrogen, silicon, aluminum, sulfur, calcium, ...titanium, iron, and nickel isotopic compositions of SiC stardust. We find that these core-collapse supernova models predict similar carbon and nitrogen compositions to SiC X grains and grains with 12C/13C < 20 and 14N/15N < 60, which we will hereafter refer to as SiC 'D' grains. Material from the interior of a 15 explosion reaches high enough temperatures shortly after core collapse to produce the large enrichments of 13C and 15N necessary to replicate the compositions of SiC D grains. The innermost ejecta in a core-collapse supernova is operating in the neutrino-driven regime and undergoes fast proton capture after being heated by the supernova shockwave. Both 3D models predict 0.3 Al/27Al < 1.5, comparable to the ratios seen in SiC X, C, and D grains. Models 15S and 15A, in general, predict very large anomalies in calcium isotopes but do compare qualitatively with the SiC X grain measurements that show 44Ca and 43Ca excesses. The titanium isotopic compositions of SiC X grains are well reproduced. The models predict 57Fe excesses and depletions that are observed in SiC X grains, and in addition predict accurately the 60Ni/58Ni, 61Ni/58Ni, and 62Ni/58Ni ratios in SiC X grains, as a result of fast neutron captures initiated by the propagation of the supernova shockwave. Finally, symmetry has a noticeable effect on the production of silicon, sulfur, and iron isotopes in the SN ejecta.
The aim of this randomized, controlled, blinded clinical study was to compare ridge dimensions and histologic characteristics of ridges preserved with 2 different graft materials.
Twenty-four ...subjects, each requiring a nonmolar extraction and delayed implant placement, were randomly selected to receive ridge preservation treatment with either an allograft in an experimental putty carrier plus a calcium sulfate barrier (PUT) or a bovine-derived xenograft (BDX) plus a collagen membrane. Horizontal and vertical ridge dimensions were determined using a digital caliper and a template. At 4 months postextraction, a trephine core was obtained for histologic analysis.
The average ridge width decreased by 0.50 mm for both groups (P < .05). The midbuccal vertical change for the PUT group was a loss of 0.3+/-0.7 mm versus a gain of 0.7+/-1.2 mm for the BDX group, a difference of 1.0 mm (P > .05). Histologic analysis revealed vital bone in the PUT group of about 61%+/-9% versus 26%+/-20% for the BDX group (P < .05).
Greater vital bone fill in the PUT group may be attributable to earlier and greater vascular invasion of the carrier material. The putty material was characterized by ease of handling, simple placement, and enhanced graft particle containment.
Allograft mixed with an experimental putty carrier produced significantly more vital bone fill than did the use of a xenograft with no carrier material. Ridge width and height dimensions were similarly preserved with both graft materials.
Summary
Previous association mapping on chromosome 3q13‐21 detected evidence for association at the limbic system‐associated membrane protein (LSAMP) gene in individuals with late‐onset coronary ...artery disease (CAD). LSAMP has never been implicated in the pathogenesis of CAD. We sought to thoroughly characterize the association and the gene. Non‐redundant single nucleotide polymorphisms (SNPs) across the gene were examined in an initial dataset (168 cases with late‐onset CAD, 149 controls). Stratification analysis on left main CAD (N = 102) revealed stronger association, which was further validated in a validation dataset (141 cases with left main CAD, 215 controls), a third control dataset (N = 255), and a family‐based dataset (N = 2954). A haplotype residing in a novel alternative transcript of the LSAMP gene was significant in all independent case‐control datasets (p = 0.0001 to 0.0205) and highly significant in the joint analysis (p = 0.00004). Lower expression of the novel alternative transcript was associated with the risk haplotype (p = 0.0002) and atherosclerosis burden in human aortas (p = 0.0001). Furthermore, silencing LSAMP expression in human aortic smooth muscle cells (SMCs) substantially augmented SMC proliferation (p<0.01). Therefore, the risk conferred by the LSAMP haplotype appears to be mediated by LSAMP down‐regulation, which may promote SMC proliferation in the arterial wall and progression of atherosclerosis.
Multiple sclerosis (MS) is a debilitating neuroimmunological and neurodegenerative disease affecting >4,00,000 individuals in the United States. Population and family-based studies have suggested ...that there is a strong genetic component. Numerous genomic linkage screens have identified regions of interest for MS loci. Our own second-generation genome-wide linkage study identified a handful of non-major histocompatibility complex regions with suggestive linkage. Several of these regions were further examined using single-nucleotide polymorphisms (SNPs) with average spacing between SNPs of approximately 1.0 Mb in a dataset of 173 multiplex families. The results of that study provided further evidence for the involvement of the chromosome 1q43 region. This region is of particular interest given linkage evidence in studies of other autoimmune and inflammatory diseases including rheumatoid arthritis and systemic lupus erythematosus. In this follow-up study, we saturated the region with approximately 700 SNPs (average spacing of 10 kb per SNP) in search of disease-associated variation within this region. We found preliminary evidence to suggest that common variation within the RGS7 locus may be involved in disease susceptibility.
To explore the potential value of recently developed high-density linkage mapping methods in the analysis of complex disease we have regenotyped five nuclear families first studied in the 1996 UK ...multiple sclerosis linkage genome screen, using Applied Biosystems high-density microsatellite linkage mapping set, the Illumina BeadArray™ linkage mapping panel (version 3) and the Affymetrix GeneChip® Human Mapping 10K array. We found that genotyping success, information extraction and genotyping accuracy were improved with all systems. These improvements were particularly marked with the SNP-based methods (Illumina and Affymetrix), with little difference between these. The extent of additional information extracted is considerable, indicating that reanalysis of existing multiplex families using these newer systems would substantially increase power.
Multiple sclerosis (MS) is a common disease of the central nervous system characterized by inflammation, myelin loss, gliosis, varying degrees of axonal pathology, and progressive neurological ...dysfunction. Multiple sclerosis exhibits many of the characteristics that distinguish complex genetic disorders including polygenic inheritance and environmental exposure risks. Here, we used a highly efficient multilocus genotyping assay representing variation in 34 genes associated with inflammatory pathways to explore gene-gene interactions and disease susceptibility in a well-characterized African-American case-control MS data set. We applied the multifactor dimensionality reduction (MDR) test to detect epistasis, and identified single-IL4R(Q576R)- and three-IL4R(Q576R), IL5RA(-80), CD14(-260)- locus association models that predict MS risk with 75-76% accuracy (P<0.01). These results demonstrate the importance of exploring both main effects and gene-gene interactions in the study of complex diseases.
Multiple sclerosis (MS) is a debilitating neuroimmunological and neurodegenerative disease with a strong genetic component. Numerous studies have failed to consistently identify genes that confer ...disease susceptibility except for association with HLA-DR. Seven non-HLA regions (1q, 2q, 9q, 13q, 16q, 18p and 19q) identified in a recent genomic screen were investigated by genotyping approximately 20 single-nucleotide polymorphisms (SNPs) at approximately 1 Mb intervals. Non-parametric multipoint analyses identified a peak LOD* score of 2.99 for the 1q44 region and substantially narrowed the linkage peak to approximately 7 Mb. Ordered subset analyses (OSA) identified significant LOD score increases for 2q35 and 18p11 when ranking families by HLA-DR status and identified a significant LOD score increase in region 2q35 when ranking families by linkage to chromosome 1q44. 1q44 is particularly interesting because of linkage evidence for this region in studies of both rheumatoid arthritis and systemic lupus erythematosus.
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