1,585 research outputs found
More Evidence for an Oscillation Superimposed on the Hubble Flow
In a recent investigation evidence was presented for a low-level sinusoidal
oscillation superimposed on top of the Hubble flow. This oscillation was in
V, in a sample of type Ia Supernovae sources with accurate distances,
and it was found to have a wavelength close to 40 Mpc. It became easily visible
after the removal of several previously identified discrete velocity
components. Its amplitude like that of the Hubble velocity showed an increase
with distance, as would be expected for a constant-amplitude space oscillation.
Here we report that this oscillation is also present in distance clumping in
these sources, with the same wavelength, but in phase quadrature. The discrete
velocity components do not play a role in detecting the distance clumping
wavelength. Assuming that time proceeds from high cosmological redshift to low,
the blue-shifted velocity peaks, which represent the contraction stage of the
velocity oscillation, then lead the density peaks. With the discrete velocity
components removed we also find evidence for at least one other, weaker
velocity oscillation. It is found to have a wavelength similar to one reported
in density clumping by previous investigators. In those cases the source
samples were much larger.Comment: 7 pages, with 6 figures, accepted for publication in Astrophysics and
Space Scienc
On The Depolarization Asymmetry Seen in Giant Radio Lobes
The depolarization asymmetry seen in double-lobed radio sources, referred to
as the Laing-Garrington (L-G) effect where more rapid depolarization is seen in
the lobe with no visible jet as the wavelength increases, can be explained
either by internal differences between the two lobes, or by an external Faraday
screen that lies in front of only the depolarized lobe. If the jet
one-sidedness is due to relativistic beaming the depolarization asymmetry must
be due to an intervening Faraday screen. If it is intrinsic the depolarization
asymmetry must be related to internal differences in the lobes. We assume in
this paper that the speed in the outer jet of several Fanaroff-Riley Class 1
(FRI) sources exhibiting the L-G effect is close to the 0.1c reported by
several other investigators. For these sources we find that the jet
one-sidedness cannot be explained by beaming and therefore must be intrinsic.
In these FRI sources the L-G effect must be due to differences that originate
inside the lobes themselves. Although it is not known if the flow in the outer
jets of FRII sources also slows to this speed it is suggested that the
explanation of the L-G effect is likely to be the same in both types. This
argument is strengthened by the recent evidence that FRII galaxies have very
large viewing angles, which in turn implies that the L-G model cannot work
regardless of the jet velocity. It may therefore be too soon to completely rule
out internal depolarization in the lobes as the true explanation for the L-G
effect.Comment: 8 pages with 4 figures. Accepted for publication in Ap&S
Towards White, Anti-Racist Mothering Practices: Confronting Essentialist Discourses of Race and Culture
Children\u27s Mental Health over the Early Life Course: The Impact of Economic Resources, Neighborhood Disorder, and Family Processes
Drawing upon a stress process and life course framework, and using data from the Child Supplement of the National Longitudinal Survey of Youth, the three papers presented in this dissertation examine the extent to which economic resources, neighborhood disorder, and family processes influence children’s trajectories of mental health.
In the first paper, I empirically construct six categories that represent children with comparable profiles of family income over time: increasing, decreasing, fluctuating, and stability across low-, medium-, and high-income families. The income categories are incorporated in multiple group latent growth curve models to assess the extent to which they initiate and shape children’s mental health trajectories from age 4 to 14. Results reveal significant disparities in antisocial behavior and depression/anxiety at age 4 and over time across the income categories.
In the second paper, I use these income categories to examine how stability and change in family income influences trajectories of maternal emotional support and the provision of cognitive stimulation in children’s home environments. In subsequent analyses, I examine the extent to which these different economic profiles moderate the relationship between family processes and children’s mental health trajectories.
In the third and final paper, I examine the relationship between stability and change in perceived neighborhood disorder and children’s trajectories of mental health. I conceptualize perceived neighborhood disorder as a two-part process involving a binary component that distinguishes between children exposed to minimal vs. high levels of disorder, and a continuous component that represents the actual level of disorder for children in the latter category. These two processes capture stability and change in neighborhood disorder over time, and are included in parallel process latent growth models to examine their separate and distinct impact on children’s trajectories of mental health.
The results from these papers underscore that the duration and sequencing of socioeconomic status, both at the family and neighborhood level, have important implications for children’s mental health and family processes. The results also underscore the complex and dynamic ways family processes influence children’s mental health in different economic contexts
Alien Registration- Comeau, Loretta M. (Milo, Piscataquis County)
https://digitalmaine.com/alien_docs/8420/thumbnail.jp
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