2,126 research outputs found
The Baby Blues: Postpartum Depression and The ways we can combat its Long-Term Effects
As nurses, effective interventions for new mothers, both non pharmacological and pharmacological, are essential to improving these patients’ outcomes and minimizing their risk for postpartum depression (PPD). New mothers undergo an immense amount of stress, both physically and mentally. As a result of this, many hospitals have standard postpartum care to minimize the risk of postpartum depression. Despite this, many mothers find themselves at a higher risk for PPD and managing these symptoms. Prescription medications are typically used in treating some symptoms of PPD but many patients may seek other forms of therapies. It is essential that alternative methods in managing and minimizing the long-term effects of postpartum depression in order to improve both the mother and child outcomes. Psychosocial support and a healthy diet have shown significance in managing the symptoms of PPD.
This thesis contains a review of recent research literature examining the long-term effects of PPD along with potential interventions to minimize these effects, and is followed by a proposal for further study on this important topic
From flux to dust mass: Does the grain-temperature distribution matter for estimates of cold dust masses in supernova remnants?
The amount of dust estimated from infrared to sub-millimetre (submm)
observations strongly depends on assumptions of different grain sizes,
compositions and optical properties. Here we use a simple model of thermal
emission from cold silicate/carbon dust at a range of dust grain temperatures
and fit the spectral energy distribution (SED) of the Crab Nebula as a test.
This can lower the derived dust mass for the Crab by ~50% and 30-40% for
astronomical silicates and amorphous carbon grains compared to recently
published values (0.25M_sun -> 0.12M_sun and 0.12M_sun -> 0.072M_sun,
respectively), but the implied dust mass can also increase by as much as almost
a factor of six (0.25M_sun -> 1.14M_sun and 0.12M_sun -> 0.71M_sun) depending
on assumptions regarding the sizes/temperatures of the coldest grains. The
latter values are clearly unrealistic due to the expected metal budget, though.
Furthermore, we show by a simple numerical experiment that if a cold-dust
component does have a grain-temperature distribution, it is almost unavoidable
that a two-temperature fit will yield an incorrect dust mass estimate. But we
conclude that grain temperatures is not a greater uncertainty than the often
poorly constrained emissivities (i.e., material properties) of cosmic dust,
although there is clearly a need for improved dust emission models. The
greatest complication associated with deriving dust masses still arises in the
uncertainty in the dust composition.Comment: 13 pages, 7 figures, to appear in MNRA
The Three-Dimensional Structure of Interior Ejecta in Cassiopeia A at High Spectral Resolution
We used the Spitzer Space Telescope's Infrared Spectrograph to create a high
resolution spectral map of the central region of the Cassiopeia A supernova
remnant, allowing us to make a Doppler reconstruction of its 3D structure. The
ejecta responsible for this emission have not yet encountered the remnant's
reverse shock or the circumstellar medium, making it an ideal laboratory for
exploring the dynamics of the supernova explosion itself. We observe that the
O, Si, and S ejecta can form both sheet-like structures as well as filaments.
Si and O, which come from different nucleosynthetic layers of the star, are
observed to be coincident in velocity space in some regions, and separated by
500 km/s or more in others. Ejecta traveling toward us are, on average, ~900
km/s slower than the material traveling away from us. We compare our
observations to recent supernova explosion models and find that no single model
can simultaneously reproduce all the observed features. However, models of
different supernova explosions can collectively produce the observed geometries
and structures of the interior emission. We use the results from the models to
address the conditions during the supernova explosion, concentrating on
asymmetries in the shock structure. We also predict that the back surface of
Cassiopeia A will begin brightening in ~30 years, and the front surface in ~100
years.Comment: 35 pages, 16 figures, accepted to Ap
A Dust Twin of Cas A: Cool Dust and 21-micron Silicate Dust Feature in the Supernova Remnant G54.1+0.3
We present infrared (IR) and submillimeter observations of the Crab-like
supernova remnant (SNR) G54.1+0.3 including 350 micron (SHARC-II), 870 micron
(LABOCA), 70, 100, 160, 250, 350, 500 micron (Herschel) and 3-40 micron
(Spitzer). We detect dust features at 9, 11 and 21 micron and a long wavelength
continuum dust component. The 21 micron dust coincides with [Ar II] ejecta
emission, and the feature is remarkably similar to that in Cas A. The IRAC 8
micron image including Ar ejecta is distributed in a shell-like morphology
which is coincident with dust features, suggesting that dust has formed in the
ejecta. We create a cold dust map that shows excess emission in the
northwestern shell. We fit the spectral energy distribution of the SNR using
the continuous distributions of ellipsoidal (CDE) grain model of pre-solar
grain SiO2 that reproduces the 21 and 9 micron dust features and discuss grains
of SiC and PAH that may be responsible for the 10-13 micron dust features. To
reproduce the long-wavelength continuum, we explore models consisting of
different grains including Mg2SiO4, MgSiO3, Al2O3, FeS, carbon, and Fe3O4. We
tested a model with a temperature-dependent silicate absorption coefficient. We
detect cold dust (27-44 K) in the remnant, making this the fourth such SNR with
freshly-formed dust. The total dust mass in the SNR ranges from 0.08-0.9 Msun
depending on the grain composition, which is comparable to predicted masses
from theoretical models. Our estimated dust masses are consistent with the idea
that SNe are a significant source of dust in the early Universe.Comment: MNRAS: accepted on June 28, 2018 and published on July 4, 201
An empirical determination of the dust mass absorption coefficient, κd, using the Herschel Reference Survey
We use the published photometry and spectroscopy of 22 galaxies in the Herschel Reference Survey to determine that the value of the dust mass absorption coefficient κ d at a wavelength of 500 μm is κ500 = (0.051 +0.070 −0.026) m^2 kg^-1. We do so by taking advantage of the fact that the dust-to-metals ratio in the interstellar medium of galaxies appears to be constant. We argue that our value for κd supersedes that of James et al. (2002) – who pioneered this approach for determining κd – because we take advantage of superior data, and account for a number of significant systematic effects that they did not consider. We comprehensively incorporate all methodological and observational contributions to establish the uncertainty on our value, which represents a marked improvement on the oft-quoted ‘order-of-magnitude’ uncertainty on κd . We find no evidence that the value of κd differs significantly between galaxies, or that it correlates with any other measured or derived galaxy properties. We note, however, that the availability of data limits our sample to relatively massive (10^9.7 < Mstar < 10&11.0 Msol ), high metallicity (8.61 < [12 + log 10 O/H] < 8.86) galaxies; future work will allow us to investigate a wider range of systems
High-resolution observations of dust in SN 1987A
The dust produced by supernovae is an important topic for understanding supernova
physics and the chemical evolution of galaxies. Recent ALMA observations of SN 1987A have
allowed us to peer into the inner ejecta to the cool dust, with spatial resolution from 0:003 at
300 GHz down to 0:0009 at 680 GHz { an improvement over the previous 300 GHz Cycle 0
observations at 0:0069. Comparison of the dust location and morphology with other multiwave-
length emission presents an interesting picture of the role dust plays in the ejecta. The mm{FIR
SED is compared to radiative models to study the dust composition 30 years after the initial
explosion. Fits to the ring emission also probe the drift of the center of the system over time
Admixture mapping of coronary artery calcification in African Americans from the NHLBI family heart study
BACKGROUND: Coronary artery calcification (CAC) is an imaging biomarker of coronary atherosclerosis. In European Americans, genome-wide association studies (GWAS) have identified several regions associated with coronary artery disease. However, few large studies have been conducted in African Americans. The largest meta-analysis of CAC in African Americans failed to identify genome-wide significant variants despite being powered to detect effects comparable to effects identified in European Americans. Because CAC is different in prevalence and severity in African Americans and European Americans, admixture mapping is a useful approach to identify loci missed by GWAS. RESULTS: We applied admixture mapping to the African American cohort of the Family Heart Study and identified one genome-wide significant region on chromosome 12 and three potential regions on chromosomes 6, 15, and 19 that are associated with CAC. Follow-up studies using previously reported GWAS meta-analysis data suggest that the regions identified on chromosome 6 and 15 contain variants that are possibly associated with CAC. The associated region on chromosome 6 contains the gene for BMP-6, which is expressed in vascular calcific lesions. CONCLUSIONS: Our results suggest that admixture mapping can be a useful hypothesis-generating tool to identify genomic regions that contribute to complex diseases in genetically admixed populations. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12863-015-0196-x) contains supplementary material, which is available to authorized users
The Three-Dimensional Structure of Cassiopeia A
We used the Spitzer Space Telescope's Infrared Spectrograph to map nearly the
entire extent of Cassiopeia A between 5-40 micron. Using infrared and Chandra
X-ray Doppler velocity measurements, along with the locations of optical ejecta
beyond the forward shock, we constructed a 3-D model of the remnant. The
structure of Cas A can be characterized into a spherical component, a tilted
thick disk, and multiple ejecta jets/pistons and optical fast-moving knots all
populating the thick disk plane. The Bright Ring in Cas A identifies the
intersection between the thick plane/pistons and a roughly spherical reverse
shock. The ejecta pistons indicate a radial velocity gradient in the explosion.
Some ejecta pistons are bipolar with oppositely-directed flows about the
expansion center while some ejecta pistons show no such symmetry. Some ejecta
pistons appear to maintain the integrity of the nuclear burning layers while
others appear to have punched through the outer layers. The ejecta pistons
indicate a radial velocity gradient in the explosion. In 3-D, the Fe jet in the
southeast occupies a "hole" in the Si-group emission and does not represent
"overturning", as previously thought. Although interaction with the
circumstellar medium affects the detailed appearance of the remnant and may
affect the visibility of the southeast Fe jet, the bulk of the symmetries and
asymmetries in Cas A are intrinsic to the explosion.Comment: Accepted to ApJ. 54 pages, 21 figures. For high resolution figures
and associated mpeg movie and 3D PDF files, see
http://homepages.spa.umn.edu/~tdelaney/pape
Dust production in supernovae: the case of Kepler's SNR [Abstract]
We compare the submillimetre (submm) emission with the Hi and CO distribution towards Kepler's supernova remnant (SNR), and conclude that 0.1 to 1.2 M⊙ of dust originates from Kepler. Such rates are sufficient to explain the origin of dust in high redshift galaxies
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