2,793 research outputs found
Studying the Pulsation of Mira Variables in the Ultraviolet
We present results from an empirical study of the Mg II h & k emission lines
of selected Mira variable stars, using spectra from the International
Ultraviolet Explorer (IUE). The stars all exhibit similar Mg II behavior during
the course of their pulsation cycles. The Mg II flux always peaks after optical
maximum near pulsation phase 0.2-0.5, although the Mg II flux can vary greatly
from one cycle to the next. The lines are highly blueshifted, with the
magnitude of the blueshift decreasing with phase. The widths of the Mg II lines
are also phase-dependent, decreasing from about 70 km/s to 40 km/s between
phase 0.2 and 0.6. We also study other UV emission lines apparent in the IUE
spectra, most of them Fe II lines. These lines are much narrower and not nearly
as blueshifted as the Mg II lines. They exhibit the same phase-dependent flux
behavior as Mg II, but they do not show similar velocity or width variations.Comment: 26 pages, 12 figures; AASTEX v5.0 plus EPSF extensions in mkfig.sty;
to appear in Ap
Repartnering: the relevance of parenthood and gender to cohabitation and remarriage among the formerly married
This paper is an exploratory analysis of the impact of current and anticipated parenthood on cohabitation and remarriage among those formerly living in marriage-type relationships. The focus on children is embedded within a broader analysis of repartnering which takes account of other factors, including gender. Quantitative and qualitative analyses are used, with a multivariate analysis of repartnering patterns, using data from the General Household Survey, being complementedby in-depth interview data examining the attitudes of the formerly married to future relationships. The paper demonstrates that parenthood has a statistically significant effect on the likelihood of formerly married women repartnering, with a higher number of children being associated with a lower probability of repartnering. The presence of children can work against repartnering in a variety of ways. Children place demands on their parents and can deter or object to potential partners. Parents may see their parental role as more important than, and a barrier to, new relationships. However, mothers are typically looking for partners for themselves rather than fathers for their children. Among formerly married people without children, the desire to become a parent encourages repartnering. The paper concludes that parenthood should be a key consideration in analyses of repartnering
Family Ties and Child Placement
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73323/1/j.1545-5300.1978.00289.x.pd
The roots of "Western European societal evolution". A concept of Europe by JenĆ SzƱcs
JenĆ SzƱcs wrote his essay entitled Sketch on the three regions of Europe in the early 1980s in Hungary. During these years, a historically well-argued opinion emphasising a substantial difference between Central European and Eastern European societies was warmly received in various circles of the political opposition. In a wider European perspective SzƱcs used the old âliberty toposâ which claims that the history of Europe is no other than the fulfillment of liberty. In his Sketch, SzƱcs does not only concentrate on questions concerning the Middle Ages in Western Europe. Yet it is this stream of thought which brought a new perspective to explaining European history. His picture of the Middle Ages represents well that there is a way to integrate all typical Western motifs of post-war self-definition into a single theory. Mainly, the âliberty motifâ, as a sign of âEuropeanismâ â in the interpretation of BibĂłâs concept, Anglo-saxon Marxists and Weberâs social theory â, developed from medieval concepts of state and society and from an analysis of economic and social structures. SzƱcsâs historical aspect was a typical intellectual product of the 1980s: this was the time when a few Central European historians started to outline non-Marxist aspects of social theory and categories of modernisation theories, but concealing them with Marxist terminology
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Effects of melting conditions on platinum-inclusion content in phosphate laser glasses
Results from small-scale glass melting experiments aimed at reducing the density of platinum particles in phosphate laser glasses are discussed. The platinum particles originate from the crucibles used to melt the laser glass and can cause optical damage in glasses used in high-peak-power lasers. The melting experiments examine the effects of a) temperature and temperature gradients; b) processing time; and c) Oâ atmosphere on the formation and dissolution of platinum inclusions in LG-750 phosphate laser glass. Results show that most platinum inclusions originate early in the melt cycle, with thermal gradients within the melter being one of the major causes. By using oxidizing conditions (Oâ), the platinum inclusions can be dissolved into the glass during the course of the melt cycle. Results from the laboratory-scale melting experiments have been incorporated into a proprietary laser-glass melting process. The laser glass prepared under these conditions has an average of less than 0.1 platinum inclusions/1, which represents a 1000-fold reduction over the previously available phosphate laser glasses
Modeling RR Tel through the Evolution of the Spectra
We investigate the evolution of RR Tel after the outburst by fitting the
emission spectra in two epochs. The first one (1978) is characterized by large
fluctuations in the light curve and the second one (1993) by the slow fading
trend. In the frame of a colliding wind model two shocks are present: the
reverse shock propagates in the direction of the white dwarf and the other one
expands towards or beyond the giant. The results of our modeling show that in
1993 the expanding shock has overcome the system and is propagating in the
nearby ISM. The large fluctuations observed in the 1978 light curve result from
line intensity rather than from continuum variation. These variations are
explained by fragmentation of matter at the time of head-on collision of the
winds from the two stars. A high velocity (500 km/s) wind component is revealed
from the fit of the SED of the continuum in the X-ray range in 1978, but is
quite unobservable in the line profiles. The geometrical thickness of the
emitting clumps is the critical parameter which can explain the short time
scale variabilities of the spectrum and the trend of slow line intensity
decrease.Comment: 26 pages, LaTeX (including 5 Tables) + 6 PostScript figures. To
appear in "The Astrophysical Journal
The evolutionary status of the semiregular variable QYSge
Repeated spectroscopic observations made with the 6m telescope of yielded new
data on the radial-velocity variability of the anomalous yellow supergiant
QYSge. The strongest and most peculiar feature in its spectrum is the complex
profile of NaI D lines, which contains a narrow and a very wide emission
components. The wide emission component can be seen to extend from -170 to +120
km/s, and at its central part it is cut by an absorption feature, which, in
turn, is split into two subcomponents by a narrow (16km/s at r=2.5) emission
peak. An analysis of all the Vr values leads us to adopt for the star a
systemic velocity of Vr=-21.1 km/s, which corresponds to the position of the
narrow emission component of NaI. The locations of emission-line features of
NaI D lines are invariable, which point to their formation in regions that are
external to the supergiant's photosphere. Differential line shifts of about
10km/s are revealed. The absorption lines in the spectrum of QYSge have a
substantial width of FWHM~45 km/s. The method of model atmospheres is used to
determine the following parameters: Teff=6250K, lg g=2.0, and microturbulence
Vt=4.5km/s. The metallicity of the star is found to be somewhat higher than the
solar one with an average overabundance of iron-peak elements of [Met/H]=+0.20.
The star is found to be slightly overabundant in carbon and nitrogen,
[C/Fe]=+0.25, [N/Fe]=+0.27. The alpha-process elements Mg, Si, and Ca are
slightly overabundant [alpha/H]=+0.12. The strong sodium excess, [Na/Fe]=+0.75,
is likely to be due to the dredge-up of the matter processed in the NeNa cycle.
Heavy elements of the s-process are underabundant relative to the Sun. On the
whole, the observed properties of QYSge do not give grounds for including this
star into the group of RCrB or RVTau-type type objects.Comment: 29 pages, 8 figures, 4 tables; accepted by Astrophys. Bulleti
Discovery of Rapid Hard X-ray Variability and New Jet Activity in the Symbiotic Binary R Aqr
Two Chandra observations of the R Aqr symbiotic binary system taken 3.3 years
apart show dramatic changes in the X-ray morphology and spectral
characteristics in the inner 500 AU of this system. The morphology of the soft
X-ray emission has evolved from a nearly circular region centered on the binary
system to an hourglass shape that indicates the formation of a new southwest
jet. Synchrotron radiation from the new jet in contemporaneous VLA radio
spectra implies the physical conditions in the early stages of jet development
are different from those in the more extended outer thermal jets known to exist
for decades in this system. The central binary source has two X-ray spectral
components in each of the two epochs, a soft component and a highly absorbed
hard component characterized by T ~ 10^8 K if fit with a thermal plasma model.
The spectrum hardened considerably between 2000.7 and 2004.0, primarily due to
increased flux above 5 keV, suggesting a change in the accretion activity of
the white dwarf on a timescale of a few years or less. Point-source Fe K
emission is detected at the position of the central binary system in both
observations. While the earlier observation shows evidence of only a single
emission peak near Fe K alpha at 6.4 keV, the later observation shows a more
complex emission structure between 6 and 7 keV. Finally, we have discovered a
modulation in the hard X-ray flux with a period of 1734 s at a 95% confidence
level in the 2004 observation only. The modulation potentially arises from
standing shocks in an accretion column and we have explored the possibility
that the white dwarf in R Aqr is analogous to the magnetic white dwarfs in
Intermediate Polar.Comment: 31 pages, 14 figures, 1 table To be published in ApJ, expected April
10 issue. AAS LaTex styl
Applying Community-Based Participatory Research Partnership Principles to Public Health Practice-Based Research Networks
With real-world relevance and translatability as important goals, applied methodological approaches have arisen along the
participatory continuum that value context and empower stakeholders to partner actively with academics throughout the
research process. Community-based participatory research (CBPR) provides the gold standard for equitable, partnered
research in traditional communities. Practice-based research networks (PBRNs) also have developed, coalescing communities
of practice and of academics to identify, study, and answer practice-relevant questions. To optimize PBRN potential for
expanding scientific knowledge, while bridging divides across knowledge production, dissemination, and implementation,
we elucidate how PBRN partnerships can be strengthened by applying CBPR principles to build and maintain research
collaboratives that empower practice partners. Examining the applicability of CBPR partnership principles to public health (PH)
PBRNs, we conclude that PH-PBRNs can serve as authentic, sustainable CBPR partnerships, ensuring the co-production of
new knowledge, while also improving and expanding the implementation and impact of research findings in real-world settings.ECU Open Access Publishing Support Fun
A multispectral view of the periodic events in eta Carinae
A full description of the 5.5-yr low excitation events in Eta Carinae is
presented. We show that they are not as simple and brief as previously thought,
but a combination of two components. The first, the 'slow variation' component,
is revealed by slow changes in the ionization level of circumstellar matter
across the whole cycle and is caused by gradual changes in the wind-wind
collision shock-cone orientation, angular opening and gaseous content. The
second, the 'collapse' component, is restricted to around the minimum, and is
due to a temporary global collapse of the wind-wind collision shock. High
energy photons (E > 16 eV) from the companion star are strongly shielded,
leaving the Weigelt objects at low ionization state for >6 months. High energy
phenomena are sensitive only to the 'collapse', low energy only to the 'slow
variation' and intermediate energies to both components. Simple eclipses and
mechanisms effective only near periastron (e.g., shell ejection or accretion
onto the secondary star) cannot account for the whole 5.5-yr cycle.
We find anti-correlated changes in the intensity and the radial velocity of P
Cygni absorption profiles in FeII 6455 and HeI 7065 lines, indicating that the
former is associated to the primary and the latter to the secondary star. We
present a set of light curves representative of the whole spectrum, useful for
monitoring the next event (2009 January 11).Comment: 16 pages, 7 EPS figures, accepted for publication on MNRA
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