890 research outputs found
The Mass of the Convective Zone in FGK Main Sequence Stars and the Effect of Accreted Planetary Material on Apparent Metallicity Determinations
The mass of the outer convective zone in FGK main sequence stars decreases
dramatically with stellar mass. Therefore, any contamination of a star's
atmosphere by accreted planetary material should affect hotter stars much more
than cool stars. If recent suggestions that high metal abundances in stars with
planets are caused by planetesimal accretion are correct, then metallicity
enhancements in earlier-type stars with planets should be very pronounced. No
such trend is seen, however.Comment: Submitted ApJ Letters March 26th; accepted April 30th. 12 pages, 2
figure
Emitter-site selective photoelectron circular dichroism of trifluoromethyloxirane
The angle-resolved inner-shell photoionization of R-trifluoromethyloxirane,
C3H3F3O, is studied experimentally and theoretically. Thereby, we investigate
the photoelectron circular dichroism (PECD) for nearly-symmetric O 1s and F 1s
electronic orbitals, which are localized on different molecular sites. The
respective dichroic and angular distribution parameters
are measured at the photoelectron kinetic energies from 1 to 16 eV by using
variably polarized synchrotron radiation and velocity map imaging spectroscopy.
The present experimental results are in good agreement with the outcome of ab
initio electronic structure calculations. We report a sizable chiral asymmetry
of up to about 9% for the K-shell photoionization of oxygen atom.
For the individual fluorine atoms, the present calculations predict asymmetries
of similar size. However, being averaged over all fluorine atoms, it drops down
to about 2%, as also observed in the present experiment. Our study demonstrates
a strong emitter- and site-sensitivity of PECD in the one-photon inner-shell
ionization of this chiral molecule
INTRODUCTION
All the papers in this edition of Dictynna are devoted to the study of intertextuality in Flavian epic poetry. The initial idea for a special thematic collection arose from work on this topic being carried out as part of a research project funded by the Swiss National Science Foundation and involving the University of Geneva and the University at Buffalo, State University of New York. In an attempt to bring together a series of contributions likely to offer a sample of both current trends and..
Ultrafast absorption of intense x rays by nitrogen molecules
We devise a theoretical description for the response of nitrogen molecules
(N2) to ultrashort and intense x rays from the free electron laser (FEL) Linac
Coherent Light Source (LCLS). We set out from a rate-equation description for
the x-ray absorption by a nitrogen atom. The equations are formulated using all
one-x-ray-photon absorption cross sections and the Auger and radiative decay
widths of multiply-ionized nitrogen atoms. Cross sections are obtained with a
one-electron theory and decay widths are determined from ab initio computations
using the Dirac-Hartree-Slater (DHS) method. We also calculate all binding and
transition energies of nitrogen atoms in all charge states with the DHS method
as the difference of two self-consistent field calculations (Delta SCF method).
To describe the interaction with N2, a detailed investigation of intense
x-ray-induced ionization and molecular fragmentation are carried out. As a
figure of merit, we calculate ion yields and the average charge state measured
in recent experiments at the LCLS. We use a series of phenomenological models
of increasing sophistication to unravel the mechanisms of the interaction of x
rays with N2: a single atom, a symmetric-sharing model, and a
fragmentation-matrix model are developed. The role of the formation and decay
of single and double core holes, the metastable states of N_2^2+, and molecular
fragmentation are explained.Comment: 16 pages, 6 figures, 2 tables, RevTeX4.1, supporting materials in the
Data Conservancy, revise
Area-level socioeconomic characteristics, prevalence and trajectories of cardiometabolic risk
This study examines the relationships between area-level socioeconomic position (SEP) and the prevalence and trajectories of metabolic syndrome (MetS) and the count of its constituents (i.e., disturbed glucose and insulin metabolism, abdominal obesity, dyslipidemia, and hypertension). A cohort of 4,056 men and women aged 18+ living in Adelaide, Australia was established in 2000-2003. MetS was ascertained at baseline, four and eight years via clinical examinations. Baseline area-level median household income, percentage of residents with a high school education, and unemployment rate were derived from the 2001 population Census. Three-level random-intercepts logistic and Poisson regression models were performed to estimate the standardized odds ratio (SOR), prevalence risk ratio (SRR), ratio of SORs/SRRs, and (95% confidence interval (CI)). Interaction between area- and individual-level SEP variables was also tested. The odds of having MetS and the count of its constituents increased over time. This increase did not vary according to baseline area-level SEP (ratios of SORs/SRRs ≈ 1; p ≥ 0.42). However, at baseline, after adjustment for individual SEP and health behaviours, median household income (inversely) and unemployment rate (positively) were significantly associated with MetS prevalence (SOR (95%CI) = 0.76 (0.63-0.90), and 1.48 (1.26-1.74), respectively), and the count of its constituents (SRR (95%CI) = 0.96 (0.93-0.99), and 1.06 (1.04-1.09), respectively). The inverse association with area-level education was statistically significant only in participants with less than post high school education (SOR (95%CI) = 0.58 (0.45-0.73), and SRR (95%CI) = 0.91 (0.88-0.94)). Area-level SEP does not predict an elevated trajectory to developing MetS or an elevated count of its constituents. However, at baseline, area-level SEP was inversely associated with prevalence of MetS and the count of its constituents, with the association of area-level education being modified by individual-level education. Population-level interventions for communities defined by area-level socioeconomic disadvantage are needed to reduce cardiometabolic risks.Anh D. Ngo, Catherine Paquet, Natasha J. Howard, Neil T. Coffee, Anne W. Taylor, Robert J. Adams, and Mark Danie
Brief of Corporate Law Professors as Amici Curie in Support of Respondents
The Supreme Court has looked to the rights of corporate shareholders in determining the rights of union members and non-members to control political spending, and vice versa. The Court sometimes assumes that if shareholders disapprove of corporate political expression, they can easily sell their shares or exercise control over corporate spending. This assumption is mistaken. Because of how capital is saved and invested, most individual shareholders cannot obtain full information about corporate political activities, even after the fact, nor can they prevent their savings from being used to speak in ways with which they disagree. Individual shareholders have no “opt out” rights or practical ability to avoid subsidizing corporate political expression with which they disagree. Nor do individuals have the practical option to refrain from putting their savings into equity investments, as doing so would impose damaging economic penalties and ignore conventional financial guidance for individual investors
- …