14,975 research outputs found
Catholic Doctors Look at the Rhythm Method
Editor\u27s introduction: Rhythm is never far from the pages of the Catholic press. During his pontificate Pope Pius XII expressed the wish that science would succeed in providing rhythm ( this licit method as he called it) with a sufficiently secure basis. The Family Life convention held here last year devoted several of its sessions to the subject. More recently the Ford Foundation awarded a grant of $150,000 to Georgetown University for a population problem study related to rhythm. The scientist, the physician, the married couple, the theologian, and the confessor are all obligated to one another and, collectively to God to see that this method, when justifiably employed, does not pose an obstacle to spiritual, moral and physical health. What part and what interest does the Catholic physician have? The St. Louis Review presented a series of questions on this subject to a group of Catholic doctors, members of our local Catholic Physicians\u27 Guild. Here follows a synthesis of their answers
Education and Legislation: Affluent Women\u27s Political Engagement in the Consumers\u27 Leagues of the Progressive Era
This paper examines the extent to which the National Consumersâ League and similar localized leagues provided middle- and upper-class women with new opportunities for involvement in American politics during the early Progressive Era, or roughly the last decade of the nineteenth century and the first decade of the twentieth. These organizations undertook various efforts â including âlistâ and âlabelâ campaigns â to educate the consuming public about the poor working conditions suffered by retail employees and especially factory workers in the garment industry, with a focus on employed women and child laborers. Later on, the leagues provided their female members with important opportunities for extensive political involvement as a more direct means of achieving their goals, including lobbying state legislators and preparing amicus curiae briefs for state courts and even the U.S. Supreme Court in the landmark case known as Muller v. Oregon (1908). Through these efforts, the leagues earned a significant amount of attention from other Progressive reform-minded organizations, including the Russell Sage Foundation
Polarization Light Curve Modeling of Corotating Interaction Regions in the Wind of the Wolf-Rayet Star WR 6
The intriguing WN4b star WR6 has been known to display epoch-dependent
spectroscopic, photometric and polarimetric variability for several decades. In
this paper, we set out to verify if a simplified analytical model in which
Corotating Interaction Regions (CIRs) threading an otherwise spherical wind is
able to reproduce the many broadband continuum light curves from the literature
with a reasonable set of parameters.
We modified the optically thin model we developed in Ignace, St-Louis &
Proulx-Giraldeau (2015) to approximately account for multiple scattering and
used it to fit 13 separate datasets of this star. By including two CIRs in the
wind, we obtained reasonable fits for all datasets with coherent values for the
inclination of the rotation axis () and for its orientation in
the plane of the sky, although in the latter case we obtained two equally
acceptable values ( and ) from the
polarimetry.
Additional line profile variation simulations using the Sobolev approximation
for the line transfer allowed us to eliminate the solution.
With the adopted configuration ( and ), we
were able to reproduce all datasets relatively well with two CIRs located near
the stellar equator and always separated by in longitude. The
epoch-dependency comes from the fact that these CIRs migrate along the surface
of the star. Density contrasts smaller than a factor of two and large opening
angles for the CIR () were found to best reproduce the
type of spectroscopic variability reported in the literature.Comment: 15 pages, 5 figures,5 table
A Systematic Search for Corotating Interaction Regions in Apparently Single Galactic Wolf-Rayet Stars. II. A Global View of the Wind Variability
This study is the second part of a survey searching for large-scale
spectroscopic variability in apparently single Wolf-Rayet (WR) stars. In a
previous paper (Paper I), we described and characterized the spectroscopic
variability level of 25 WR stars observable from the northern hemisphere and
found 3 new candidates presenting large-scale wind variability, potentially
originating from large-scale structures named Co-rotating Interaction Regions
(CIRs). In this second paper, we discuss an additional 39 stars observable from
the southern hemisphere. For each star in our sample, we obtained 4-5
high-resolution spectra with a signal-to-noise ratio of ~100 and determined its
variability level using the approach described in Paper I. In total, 10 new
stars are found to show large-scale spectral variability of which 7 present
CIR-type changes (WR 8, WR 44, WR 55, WR 58, WR 61, WR 63, WR 100). Of the
remaining stars, 20 were found to show small-amplitude changes and 9 were found
to show no spectral variability as far as can be concluded from the data in
hand. Also, we discuss the spectroscopic variability level of all single
galactic WR stars that are brighter than v~12.5, and some WR stars with 12.5 <
v <= 13.5; i.e. all the stars presented in our two papers and 4 more stars for
which spectra have already been published in the literature. We find that 23/68
stars (33.8 %) present large-scale variability, but only 12/54 stars (~22.1 %)
are potentially of CIR-type. Also, we find 31/68 stars (45.6 %) that only show
small-scale variability, most likely due to clumping in the wind. Finally, no
spectral variability is detected based on the data in hand for 14/68 (20.6 %)
stars. Interestingly, the variability with the highest amplitude also have the
widest mean velocity dispersion.Comment: 14 pages, 24 figures, 2 tables, Accepted in Ap
Polarimetric modeling of corotating interaction regions (CIRs) threading massive-star winds
Massive star winds are complex radiation-hydrodynamic (sometimes
magnetohydrodynamic) outflows that are propelled by their enormously strong
luminosities. The winds are often found to be structured and variable, but can
also display periodic or quasi-periodic behavior in a variety of wind
diagnostics. The regular variations observed in putatively single stars,
especially in UV wind lines, have often been attributed to corotating
interaction regions (CIRs) like those seen in the solar wind. We present light
curves for variable polarization from winds with CIR structures. We develop a
model for a time-independent CIR based on a kinematical description. Assuming
optically thin electron scattering, we explore the range of polarimetric light
curves that result as the curvature, latitude, and number of CIRs are varied.
We find that a diverse array of variable polarizations result from an
exploration of cases. The net polarization from an unresolved source is
weighted more toward the inner radii of the wind. Given that most massive stars
have relatively fast winds compared to their rotation speeds, CIRs tend to be
conical at inner radii, transitioning to a spiral shape at a few to several
stellar radii in the wind. Winds with a single CIR structure lead to easily
identifiable polarization signatures. By contrast allowing for multiple CIRs,
all emerging from a range of azimuth and latitude positions at the star, can
yield complex polarimetric behavior. Although our model is based on some
simplifying assumptions, it produces qualitative behavior that we expect to be
robust, and this has allowed us to explore a wide range of CIR configurations
that will prove useful for interpreting polarimetric data.Comment: accepted to A&
High-resolution X-ray spectroscopy reveals the special nature of Wolf-Rayet star winds
We present the first high-resolution X-ray spectrum of a putatively single
Wolf-Rayet star. 400 ks observations of WR 6 by the XMM-Newton-telescope
resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis
reveals that the X-rays originate far out in the stellar wind, more than 30
stellar radii from the photosphere, and thus outside the wind acceleration zone
where the line-driving instability could create shocks. The X-ray emitting
plasma reaches temperatures up to 50\,MK, and is embedded within the
un-shocked, "cool" stellar wind as revealed by characteristic spectral
signatures. We detect a fluorescent Fe line at approx 6.4 keV. The presence of
fluorescence is consistent with a two-component medium, where the cool wind is
permeated with the hot X-ray emitting plasma. The wind must have a very porous
structure to allow the observed amount of X-rays to escape. We find that
neither the line-driving instability nor any alternative binary scenario can
explain the data. We suggest a scenario where X-rays are produced when the fast
wind rams into slow "sticky clumps" that resist acceleration. Our new data show
that the X-rays in single WR-star are generated by some special mechanism
different from the one operating in the O-star winds.Comment: ApJL, Figure 3 is update
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We need to talk about sexism in science
The events that culminated in the resignation of Bora Zivkovic from Scientific American last week demonstrate that women in science face a long struggle to root out sexis
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