2,276 research outputs found
Mineralocorticoid receptor blockade during a rat's first violent encounter inhibits its subsequent propensity for violence.
In individuals naive to serious conflict in an unfamiliar environment, violence has long-lasting effects on subsequent aggressive behavior. This effect of the stressful experience of a first violent conflict occurs in victims as well as offenders. The authors study in the male rat as offender the role of a rapid corticosterone signal mediated by brain mineralocorticoid receptors (MR) in adjusting the threshold of aggressive responses. For this purpose, the authors have applied electrical stimulation of the brain's aggression circuit via the hypothalamic attack area or HAA. Using this paradigm, they found that in inexperienced rats, retesting of the animals on subsequent days facilitated aggression. Hypothalamic attack thresholds decreased to about 50% of their initial level. However, blocking the MR once with the mineralocorticoid antagonist spironolactone, during the very first evoked attacks, permanently prevented attack facilitation in subsequent conflicts in that same environment. The MR-mediated effect blocked by the antagonist occurred within an hour following the start of the first aggression tests only. A later MR blockade was not effective. These findings suggest that the corticosterone stress response during a very first serious conflict initializes an enhanced propensity for violent aggression through the brain MR
BD-22 3467, a DAO-type star exciting the nebula Abell 35
Spectral analyses of hot, compact stars with NLTE (non-local thermodynamical
equilibrium) model-atmosphere techniques allow the precise determination of
photospheric parameters. The derived photospheric metal abundances are crucial
constraints for stellar evolutionary theory.
Previous spectral analyses of the exciting star of the nebula A 35, BD-22
3467, were based on He+C+N+O+Si+Fe models only. For our analysis, we use
state-of-the-art fully metal-line blanketed NLTE model atmospheres that
consider opacities of 23 elements from hydrogen to nickel. For the analysis of
high-resolution and high-S/N (signal-to-noise) FUV (far ultraviolet, FUSE) and
UV (HST/STIS) observations, we combined stellar-atmosphere models and
interstellar line-absorption models to fully reproduce the entire observed UV
spectrum.
The best agreement with the UV observation of BD-22 3467 is achieved at Teff
= 80 +/- 10 kK and log g =7.2 +/- 0.3. While Teff of previous analyses is
verified, log g is significantly lower. We re-analyzed lines of silicon and
iron (1/100 and about solar abundances, respectively) and for the first time in
this star identified argon, chromium, manganese, cobalt, and nickel and
determined abundances of 12, 70, 35, 150, and 5 times solar, respectively. Our
results partially agree with predictions of diffusion models for DA-type white
dwarfs. A combination of photospheric and interstellar line-absorption models
reproduces more than 90 % of the observed absorption features. The stellar mass
is M ~ 0.48 Msun.
BD-22 3467 may not have been massive enough to ascend the asymptotic giant
branch and may have evolved directly from the extended horizontal branch to the
white dwarf state. This would explain why it is not surrounded by a planetary
nebula. However, the star, ionizes the ambient interstellar matter, mimicking a
planetary nebula.Comment: 13 pages, 17 figure
Household decision-making about delivery in health facilities: evidence from Tanzania.
This study investigated how partners' perceptions of the healthcare system influence decisions about delivery-location in low-resource settings. A multistage population-representative sample was used in Kasulu district, Tanzania, to identify women who had given birth in the last five years and their partners. Of 826 couples in analysis, 506 (61.3%) of the women delivered in the home. In multivariate analysis, factors associated with delivery in a health facility were agreement of partners on the importance of delivering in a health facility and agreement that skills of doctors are better than those of traditional birth attendants. When partners disagreed, the opinion of the woman was more influential in determining delivery-location. Agreement of partners regarding perceptions about the healthcare system appeared to be an important driver of decisions about delivery-location. These findings suggest that both partners should be included in the decision-making process regarding delivery to raise rates of delivery at facility
Stellar laboratories. IX. New Se V, Sr IV - VII, Te VI, and I VI oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191-B2B and RE 0503-289
To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium
(NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is for
the calculation of such model atmospheres.
We aim to calculate new Sr IV - VII oscillator strengths to identify for the
first time Sr spectral lines in hot white dwarf (WD) stars and to determine the
photospheric Sr abundances. o measure the abundances of Se, Te, and I in hot
WDs, we aim to compute new Se V, Te VI, and I VI oscillator strengths.
To consider radiative and collisional bound-bound transitions of Se V, Sr IV
- VII, Te VI, and I VI in our NLTE atmosphere models, we calculated oscillator
strengths for these ions.
We newly identified four Se V, 23 Sr V, 1 Te VI, and three I VI lines in the
ultraviolet (UV) spectrum of RE0503-289. We measured a photospheric Sr
abundance of 6.5 +3.8/-2.4 x 10**-4 (mass fraction, 9500 - 23800 times solar).
We determined the abundances of Se (1.6 +0.9/-0.6 x 10**-3, 8000 - 20000), Te
(2.5 +1.5/-0.9 x 10**-4, 11000 - 28000), and I (1.4 +0.8/-0.5 x 10**-5, 2700 -
6700). No Se, Sr, Te, and I line was found in the UV spectra of G191-B2B and we
could determine only upper abundance limits of approximately 100 times solar.
All identified Se V, Sr V, Te VI, and I VI lines in the UV spectrum of
RE0503-289 were simultaneously well reproduced with our newly calculated
oscillator strengths.Comment: 26 pages, 5 figure
Metal abundances in PG1159 stars from Chandra and FUSE spectroscopy
We investigate FUSE spectra of three PG1159 stars and do not find any
evidence for iron lines. From a comparison with NLTE models we conclude a
deficiency of 1-1.5 dex. We speculate that iron was transformed into heavier
elements. A soft X-ray Chandra spectrum of the unique H- and He-deficient star
H1504+65 is analyzed. We find high neon and magnesium abundances and confirm
that H1504+65 is the bare core of either a C-O or a O-Ne-Mg white dwarf.Comment: To be published in: Proceedings 13th European Workshop on White
Dwarfs, NATO Science Series, 4 pages, 1 figur
The WFIRST Galaxy Survey Exposure Time Calculator
This document describes the exposure time calculator for the Wide-Field
Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works
in both imaging and spectroscopic modes. In addition to the standard ETC
functions (e.g. background and S/N determination), the calculator integrates
over the galaxy population and forecasts the density and redshift distribution
of galaxy shapes usable for weak lensing (in imaging mode) and the detected
emission lines (in spectroscopic mode). The source code is made available for
public use.Comment: 44 pages. The current C source code and version history can be found
at http://www.tapir.caltech.edu/~chirata/web/software/space-etc/ ; IPAC
maintains a web interface at
http://wfirst-web.ipac.caltech.edu/wfDepc/wfDepc.js
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