189 research outputs found

    Parity Nonconservation in Neutron Resonances in 133Cs

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    Spatial parity nonconservation (PNC) has been studied in the compound-nuclear states of 134Cs by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick 133Cs target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range from 5 to 400 eV. A total of 28 new p-wave resonances were found, their neutron widths determined, and the PNC longitudinal asymmetries of the resonance cross sections measured. The value obtained for the root-mean-square PNC element M=(0.06-0.02+0.25) meV in 133Cs is the smallest among all targets studied. This value corresponds to a weak spreading width Γw=(0.006-0.003+0.154)×10-7 eV

    Registration of HiMag Tall Fescue Germplasm

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    HiMag (Reg. no. GP-79, PI 615587) tall fescue (Festuca arundinacea Schreb.) was developed and released by the Missouri Agricultural Experiment Station and the USDA-ARS in 1997. HiMag has relatively high Mg and Ca concentrations and low tetany ratio [K/(Ca + Mg)] expressed as moles of charge. Parental germplasm for the Co cycle of selection for HiMag included 950 plants from 'Kenhy' (Buckner et al., 1977), 831 plants from 'Kentucky-31', and 688 plants from `Missouri-96' (Asay et al., 1979). All plants were endophyte free [ Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin comb. nov.]. Parental plants were transplanted to the field near Columbia, MO, in the fall of 1983. The soil was a Mexico silt loam (a fine, montmorillonitic, mesic Udollic Ochraqualf) with a pH of 6.4. Selection was applied against crown rust (caused by Puccinia coronata Corda. var. coronata), leaving 1011 plants which were harvested in the fall of 1984 and analyzed for elemental concentrations of Mg, Ca, K, and the tetany ratio. Sixty-five plants (11 from Kentucky- 31, 54 from Missouri-96, and 0 from Kenhy) were chosen to generate the C1 cycle of selection. These 65 plants contained 5.0 to 7.0 g kg-1 Mg, 5.0 to 10.2 g kg' Ca, 20 to 33 g K, and had K/(Ca + Mg) values of 0.61 to 0.99. These were allowed to open-pollinate in the greenhouse during the winter of 1985/86. Harvested seeds were germinated in the greenhouse and seedlings were transplanted to the field in the fall of 1986. During the fall of 1987 approximately 1000 plants were analyzed from the CI cycle to determine elemental concentrations of Mg, Ca, K, and the tetany ratio. Forty-six plants chosen for the C2 contained 4.4 to 6.1 g kg -' Mg, 5.5 to 8.1 g kg-' Ca, 17.2 to 30.9 g kg' K, and had tetany ratios of 1.06 to 2.13. These were allowed to open-pollinate in the greenhouse in the winter of 1988-1989. Approximately 1000 seedlings were transplanted to the field having areas of Creldon silt loam (Mollic Fragiudalf) and Hobert silt loam (Umbric Fragiaqualf) at the Southwest Research Center, located near Mt. Vernon, MO, in the fall of 1989. In the summer of 1990, seed was harvested from these spaced plants and planted into an irrigated Portneuf silt loam soil (Durinodic Xeric Haplocalcid) to establish a seed increase block at Kimberly, ID, in April 1991. In 1992, seed from HiMag was harvested with the following characteristics: 1635 kg ha-1, 400 seeds g-1, 2.5 g 1000 seeds-1, and 302 kg m-3

    Thermal Hadron Production in High Energy Heavy Ion Collisions

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    We provide a method to test if hadrons produced in high energy heavy ion collisions were emitted at freeze-out from an equilibrium hadron gas. Our considerations are based on an ideal gas at fixed temperature TfT_f, baryon number density nBn_B, and vanishing total strangeness. The constituents of this gas are all hadron resonances up to a mass of 2 GeV; they are taken to decay according to the experimentally observed branching ratios. The ratios of the various resulting hadron production rates are tabulated as functions of TfT_f and nBn_B. These tables can be used for the equilibration analysis of any heavy ion data; we illustrate this for some specific cases.Comment: 12 pages (not included :13 figures + tables) report CERN-TH 6523/92 and Bielefeld preprint BI-TP 92/0

    Chromatin accessibility reveals insights into androgen receptor activation and transcriptional specificity

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    BACKGROUND: Epigenetic mechanisms such as chromatin accessibility impact transcription factor binding to DNA and transcriptional specificity. The androgen receptor (AR), a master regulator of the male phenotype and prostate cancer pathogenesis, acts primarily through ligand-activated transcription of target genes. Although several determinants of AR transcriptional specificity have been elucidated, our understanding of the interplay between chromatin accessibility and AR function remains incomplete. RESULTS: We used deep sequencing to assess chromatin structure via DNase I hypersensitivity and mRNA abundance, and paired these datasets with three independent AR ChIP-seq datasets. Our analysis revealed qualitative and quantitative differences in chromatin accessibility that corresponded to both AR binding and an enrichment of motifs for potential collaborating factors, one of which was identified as SP1. These quantitative differences were significantly associated with AR-regulated mRNA transcription across the genome. Base-pair resolution of the DNase I cleavage profile revealed three distinct footprinting patterns associated with the AR-DNA interaction, suggesting multiple modes of AR interaction with the genome. CONCLUSIONS: In contrast with other DNA-binding factors, AR binding to the genome does not only target regions that are accessible to DNase I cleavage prior to hormone induction. AR binding is invariably associated with an increase in chromatin accessibility and, consequently, changes in gene expression. Furthermore, we present the first in vivo evidence that a significant fraction of AR binds only to half of the full AR DNA motif. These findings indicate a dynamic quantitative relationship between chromatin structure and AR-DNA binding that impacts AR transcriptional specificity

    Open chromatin profiling in adipose tissue marks genomic regions with functional roles in cardiometabolic traits

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    Identifying the regulatory mechanisms of genome-wide association study (GWAS) loci affecting adipose tissue has been restricted due to limited characterization of adipose transcriptional regulatory elements. We profiled chromatin accessibility in three frozen human subcutaneous adipose tissue needle biopsies and preadipocytes and adipocytes from the Simpson Golabi-Behmel Syndrome (SGBS) cell strain using an assay for transposase-accessible chromatin (ATAC-seq). We identified 68,571 representative accessible chromatin regions (peaks) across adipose tissue samples (FDR, 5%). GWAS loci for eight cardiometabolic traits were enriched in these peaks (P, 0.005), with the strongest enrichment for waist-hip ratio. Of 110 recently described cardiometabolic GWAS loci colocalized with adipose tissue eQTLs, 59 loci had one or more variants overlapping an adipose tissue peak. Annotated variants at the SNX10 waist-hip ratio locus and the ATP2A1-SH2B1 body mass index locus showed allelic differences in regulatory assays. These adipose tissue accessible chromatin regions elucidate genetic variants that may alter adipose tissue function to impact cardiometabolic traits

    Common-variant associations with fragile X syndrome

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    Fragile X syndrome is rare but a prominent cause of intellectual disability. It is usually caused by a de novo mutation that occurs on multiple haplotypes and thus would not be expected to be detectible using genome-wide association (GWA). We conducted GWA in 89 male FXS cases and 266 male controls, and detected multiple genome-wide significant signals near FMR1 (odds ratio = 8.10, P = 2.5 × 10 −10 ). These findings withstood robust attempts at falsification. Fine-mapping yielded a minimum P = 1.13 × 10 −14 , but did not narrow the interval. Comprehensive functional genomic integration did not provide a mechanistic hypothesis. Controls carrying a risk haplotype had significantly longer FMR1 CGG repeats than controls with the protective haplotype (P = 4.75 × 10 −5 ), which may predispose toward increases in CGG number to the premutation range over many generations. This is a salutary reminder of the complexity of even “simple” monogenetic disorders

    Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to Σ+Kπ+\Sigma^+ K^-\pi^+, Σ+Kˉ0\Sigma^+ \bar{K}^{*0}, and ΛKπ+π+\Lambda K^-\pi^+\pi^+

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    We have observed two new decay modes of the charmed baryon Ξc+\Xi_c^+ into Σ+Kπ+\Sigma^+ K^-\pi^+ and Σ+Kˉ0\Sigma^+ \bar{K}^{*0} using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode Ξc+ΛKπ+π+\Xi_c^+\to\Lambda K^-\pi^+\pi^+. The branching fractions for these three modes relative to Ξc+Ξπ+π+\Xi_c^+\to\Xi^-\pi^+\pi^+ are measured to be 1.18±0.26±0.171.18 \pm 0.26 \pm 0.17, 0.92±0.27±0.140.92 \pm 0.27 \pm 0.14, and 0.58±0.16±0.070.58 \pm 0.16 \pm 0.07, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    CommonMind Consortium provides transcriptomic and epigenomic data for Schizophrenia and Bipolar Disorder

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    Schizophrenia and bipolar disorder are serious mental illnesses that affect more than 2% of adults. While large-scale genetics studies have identified genomic regions associated with disease risk, less is known about the molecular mechanisms by which risk alleles with small effects lead to schizophrenia and bipolar disorder. In order to fill this gap between genetics and disease phenotype, we have undertaken a multi-cohort genomics study of postmortem brains from controls, individuals with schizophrenia and bipolar disorder. Here we present a public resource of functional genomic data from the dorsolateral prefrontal cortex (DLPFC; Brodmann areas 9 and 46) of 986 individuals from 4 separate brain banks, including 353 diagnosed with schizophrenia and 120 with bipolar disorder. The genomic data include RNA-seq and SNP genotypes on 980 individuals, and ATAC-seq on 269 individuals, of which 264 are a subset of individuals with RNA-seq. We have performed extensive preprocessing and quality control on these data so that the research community can take advantage of this public resource available on the Synapse platform at http://CommonMind.org

    Evaluation of chromatin accessibility in prefrontal cortex of individuals with schizophrenia

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    Schizophrenia genome-wide association studies have identified >150 regions of the genome associated with disease risk, yet there is little evidence that coding mutations contribute to this disorder. To explore the mechanism of non-coding regulatory elements in schizophrenia, we performed ATAC-seq on adult prefrontal cortex brain samples from 135 individuals with schizophrenia and 137 controls, and identified 118,152 ATAC-seq peaks. These accessible chromatin regions in the brain are highly enriched for schizophrenia SNP heritability. Accessible chromatin regions that overlap evolutionarily conserved regions exhibit an even higher heritability enrichment, indicating that sequence conservation can further refine functional risk variants. We identify few differences in chromatin accessibility between cases and controls, in contrast to thousands of age-related differential accessible chromatin regions. Altogether, we characterize chromatin accessibility in the human prefrontal cortex, the effect of schizophrenia and age on chromatin accessibility, and provide evidence that our dataset will allow for fine mapping of risk variants
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