241 research outputs found
BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN Demographics
We present the first catalog and data release of the Swift-BAT AGN
Spectroscopic Survey (BASS). We analyze optical spectra of the majority of AGN
(77%, 641/836) detected based on their 14-195 keV emission in the 70-month
Swift BAT all-sky catalog. This includes redshift determination, absorption and
emission line measurements, and black hole mass and accretion rate estimates
for the majority of obscured and un-obscured AGN (74%, 473/641) with 340
measured for the first time. With ~90% of sources at z<0.2, the survey
represents a significant census of hard-X-ray selected AGN in the local
universe. In this first catalog paper, we describe the spectroscopic
observations and datasets, and our initial spectral analysis. The FWHM of the
emission lines show broad agreement with the X-ray obscuration (~94%), such
that Sy 1-1.8 have NH10^21.9 cm^-2.
Seyfert 1.9 show a range of column densities. Compared to narrow line AGN in
the SDSS, the X-ray selected AGN have a larger fraction of dusty host galaxies
suggesting these types of AGN are missed in optical surveys. Using the most
sensitive [OIII]/Hbeta and [NII]/Halpha emission line diagnostic, about half of
the sources are classified as Seyferts, ~15% reside in dusty galaxies that lack
an Hbeta detection, but for which the line upper limits imply either a Seyfert
or LINER, ~15% are in galaxies with weak or no emission lines despite high
quality spectra, and a few percent each are LINERS, composite galaxies, HII
regions, or in known beamed AGN.Comment: Accepted ApJ, see www.bass-survey.com for dat
Role of microstructure and surface defects on the dissolution kinetics of CeO2, a UO2 fuel analogue.
The release of radionuclides from spent fuel in a geological disposal facility is controlled by the surface mediated dissolution of UO2 in groundwater. In this study we investigate the influence of reactive surface sites on the dissolution of a synthesised CeO2 analogue for UO2 fuel. Dissolution was performed on: CeO2 annealed at high temperature, which eliminated intrinsic surface defects (point defects and dislocations); CeO2-x annealed in inert and reducing atmospheres to induce oxygen vacancy defects; and on crushed CeO2 particles of different size fractions. BET surface area measurements were used as an indicator of reactive surface site concentration. Cerium stoichiometry, determined using X-ray Photoelectron Spectroscopy (XPS) and supported by X-ray Diffraction (XRD) analysis, was used to determine oxygen vacancy concentration. Upon dissolution in nitric acid medium at 90°C, a quantifiable relationship was established between the concentration of high energy surface sites and CeO2 dissolution rate; the greater the proportion of intrinsic defects and oxygen vacancies, the higher the dissolution rate. Dissolution of oxygen vacancy-containing CeO2-x gave rise to rates that were an order of magnitude greater than for CeO2 with fewer oxygen vacancies. While enhanced solubility of Ce3+ influenced the dissolution, it was shown that replacement of vacancy sites by oxygen significantly affected the dissolution mechanism due to changes in the lattice volume and strain upon dissolution and concurrent grain boundary decohesion. These results highlight the significant influence of defect sites and grain boundaries on the dissolution kinetics of UO2 fuel analogues and reduce uncertainty in the long-term performance of spent fuel in geological disposal
BAT AGN spectroscopic survey–II. X-ray emission and high-ionization optical emission lines
We investigate the relationship between X-ray and optical line emission in 340 nearby (z ≃ 0.04) AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction corrected [O iii] and hard X-ray luminosity (L^(int)_([OIII])∝L_(14-195) with a large scatter (R_(Pear) = 0.64, σ = 0.62 dex) and a similarly large scatter with the intrinsic 2–10 keV to [O iii] luminosities (R_(Pear) = 0.63, σ = 0.63 dex). Correlations of the hard X-ray fluxes with the fluxes of high-ionization narrow lines ([O iii], He ii, [Ne iii] and [Ne v]) are not significantly better than with the low-ionization lines (H α, [S ii]). Factors like obscuration or physical slit size are not found to be a significant part of the large scatter. In contrast, the optical emission lines show much better correlations with each other (σ = 0.3 dex) than with the X-ray flux. The inherent large scatter questions the common usage of narrow emission lines as AGN bolometric luminosity indicators and suggests that other issues such as geometrical differences in the scattering of the ionized gas or long-term AGN variability are important
iPSCORE: A Resource of 222 iPSC Lines Enabling Functional Characterization of Genetic Variation across a Variety of Cell Types.
Large-scale collections of induced pluripotent stem cells (iPSCs) could serve as powerful model systems for examining how genetic variation affects biology and disease. Here we describe the iPSCORE resource: a collection of systematically derived and characterized iPSC lines from 222 ethnically diverse individuals that allows for both familial and association-based genetic studies. iPSCORE lines are pluripotent with high genomic integrity (no or low numbers of somatic copy-number variants) as determined using high-throughput RNA-sequencing and genotyping arrays, respectively. Using iPSCs from a family of individuals, we show that iPSC-derived cardiomyocytes demonstrate gene expression patterns that cluster by genetic background, and can be used to examine variants associated with physiological and disease phenotypes. The iPSCORE collection contains representative individuals for risk and non-risk alleles for 95% of SNPs associated with human phenotypes through genome-wide association studies. Our study demonstrates the utility of iPSCORE for examining how genetic variants influence molecular and physiological traits in iPSCs and derived cell lines
Crystal structure of dichlorido(4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane)iron(III) hexafluoridophosphate
The title compound, [FeCl₂(C₁₄H₃₀N₄)]PF₆, contains Fe³⁺ coordinated by the four nitrogen atoms of an ethylene cross-bridged cyclam macrocycle and two cis chloride ligands in a distorted octahedral environment. In contrast to other similar compounds this is a monomer. Intermolecular C-H...Cl interactions exist in the structure between the complex ions. Comparison with the mononuclear Fe²⁺ complex of the same ligand shows that the smaller Fe³⁺ ion is more fully engulfed by the cavity of the bicyclic ligand. Comparison with the μ-oxido dinuclear complex of an unsubstituted ligand of the same size demonstrates that the methyl groups of 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane prevent dimerization upon oxidation
Comparison of abdominal adiposity and overall obesity in relation to risk of small intestinal cancer in a European Prospective Cohort
Published version. Source at http://dx.doi.org/10.1007/s10552-016-0772-z Background: The etiology of small intestinal cancer (SIC)
is largely unknown, and there are very few epidemiological
studies published to date. No studies have investigated
abdominal adiposity in relation to SIC.
Methods: We investigated overall obesity and abdominal
adiposity in relation to SIC in the European Prospective
Investigation into Cancer and Nutrition (EPIC), a large
prospective cohort of approximately half a million men and
women from ten European countries. Overall obesity and abdominal obesity were assessed by body mass index
(BMI), waist circumference (WC), hip circumference
(HC), waist-to-hip ratio (WHR), and waist-to-height ratio
(WHtR). Multivariate Cox proportional hazards regression
modeling was performed to estimate hazard ratios (HRs)
and 95 % confidence intervals (CIs). Stratified analyses
were conducted by sex, BMI, and smoking status.
Results: During an average of 13.9 years of follow-up, 131 incident cases of SIC (including 41 adenocarcinomas, 44 malignant carcinoid tumors, 15 sarcomas and 10 lymphomas, and 21 unknown histology) were identified. WC
was positively associated with SIC in a crude model that also included BMI (HR per 5-cm increase = 1.20, 95 % CI 1.04, 1.39), but this association attenuated in the multivariable model (HR 1.18, 95 % CI 0.98, 1.42). However,
the association between WC and SIC was strengthened when the analysis was restricted to adenocarcinoma of the small intestine (multivariable HR adjusted for
BMI = 1.56, 95 % CI 1.11, 2.17). There were no other significant associations.
Conclusion: WC, rather than BMI, may be positively associated with adenocarcinomas but not carcinoid tumors of the small intestine.
Impact: Abdominal obesity is a potential risk factor for adenocarcinoma in the small intestine
Order parameter and connectivity topology analysis of crystalline ceramics for nuclear waste immobilization
We apply bond order and topological methods to the problem of analysing the results of radiation damage cascade simulations in ceramics. Both modified Steinhardt local order and connectivity topology analysis techniques provide results that are both translationally and rotationally invariant and which do not rely on a particular choice of a reference structure. We illustrate the methods with new analyses of molecular dynamics simulations of single cascades in the pyrochlores Gd2Ti2O7 and Gd2Zr2O7 similar to those reported previously (Todorov et al 2006 J. Phys.: Condens. Matter 18 2217). Results from the Steinhardt and topology analyses are consistent, while often providing complementary information, since the Steinhardt parameters are sensitive to changes in angular arrangement even when the overall topological connectivity is fixed. During the highly non-equilibrium conditions at the start of the cascade, both techniques reveal significant localized transient structural changes and variation in the cation connectivity. After a few picoseconds, the connectivity is largely fixed, while the order parameters continue to change. In the zirconate there is a shift to the anion disordered system while in the titanate there is substantial reversion and healing back to the parent pyrochlore structure
Differentiation of Chronic Lymphocytic Leukemia B Cells into Immunoglobulin Secreting Cells Decreases LEF-1 Expression
Lymphocyte enhancer binding factor 1 (LEF-1) plays a crucial role in B lineage development and is only expressed in B cell precursors as B cell differentiation into mature B and plasma cells silences its expression. Chronic lymphocytic leukemia (CLL) cells aberrantly express LEF-1 and its expression is required for cellular survival. We hypothesized that modification of the differentiation status of CLL cells would result in loss of LEF-1 expression and eliminate the survival advantage provided by its aberrant expression. In this study, we first established a methodology that induces CLL cells to differentiate into immunoglobulin (Ig) secreting cells (ISC) using the TLR9 agonist, CpG, together with cytokines (CpG/c). CpG/c stimulation resulted in dramatic CLL cell phenotypic and morphologic changes, expression of cytoplasmic Ig, and secretion of light chain restricted Ig. CpG/c stimulation also resulted in decreased CLL cell LEF-1 expression and increased Blimp-1 expression, which is crucial for plasma cell differentiation. Further, Wnt pathway activation and cellular survival were impaired in differentiated CLL cells compared to undifferentiated CLL cells. These data support the notion that CLL can differentiate into ISC and that this triggers decreased leukemic cell survival secondary to the down regulation of LEF-1 and decreased Wnt pathway activation
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