25,215 research outputs found
New Measurements of the Radio Photosphere of Mira based on Data from the JVLA and ALMA
We present new measurements of the millimeter wavelength continuum emission
from the long period variable Mira ( Ceti) at frequencies of 46 GHz, 96 GHz,
and 229 GHz (~7 mm, 3 mm, and 1 mm) based on observations obtained
with the Jansky Very Large Array (JVLA) and the Atacama Large
Millimeter/submillimeter Array (ALMA). The measured millimeter flux densities
are consistent with a radio photosphere model derived from previous
observations, where flux density, . The stellar disk
is resolved, and the measurements indicate a decrease in the size of the radio
photosphere at higher frequencies, as expected if the opacity decreases at
shorter wavelengths. The shape of the radio photosphere is found to be slightly
elongated, with a flattening of ~10-20%. The data also reveal evidence for
brightness non-uniformities on the surface of Mira at radio wavelengths. Mira's
hot companion, Mira B was detected at all three observed wavelengths, and we
measure a radius for its radio-emitting surface of
cm. The data presented here highlight the power of the JVLA and ALMA for the
study of the atmospheres of evolved stars.Comment: Accepted to ApJ; 27 pages, 7 figure
Tripartite entanglement from interlinked parametric interactions
We examine the tripartite entanglement properties of an optical system using
interlinked interactions, recently studied experimentally in terms
of its phase-matching properties by Bondani et al [M. Bondani, A. Allevi, E.
Gevinti, A. Agliati, and A. Andreoni, arXiv:quant-ph/0604002.]. We show that
the system does produce output modes which are genuinely tripartite entangled
and that detection of this entanglement depends crucially on the correlation
functions which are measured, with a three-mode Einstein-Podolsky-Rosen
inequality being the most sensitive.Comment: 15 pages, 5 figure
Parental Trajectories of PTSD and Child Adjustment: Findings From the Building a New Life in Australia Study
© 2019 Global Alliance for Behavioral Health and Social Justice. Evidence suggests that the psychosocial adjustment of children of refugees may be compromised when a parent has symptoms of posttraumatic stress disorder (PTSD). We sought to determine whether trajectories of parental PTSD symptoms might relate to child adjustment and whether there is an additive effect when both parents, as opposed to just one, has prominent PTSD symptoms. We report data from the first three years of a prospective study of recent Australian humanitarian migrants: the Building a New Life in Australia study. Parental PTSD symptoms were assessed on three occasions, and latent class growth analysis was used to identify homogenous groups of parents based on their PTSD symptoms. The Strength and Difficulties Questionnaire was administered to assess child psychosocial adjustment. Regression analyses were then conducted to determine whether trajectories of parental PTSD symptoms predicted child adjustment. After controlling for child age and gender, the presence of either one or both parents with persistently high PTSD symptoms was associated with children's having greater emotional difficulties and poorer overall psychosocial adjustment. Children with both parents with persistently high PTSD had higher levels of emotional difficulties than did children with a single parent with high PTSD symptoms. For emotional difficulties, though not other domains of child psychosocial adjustment, there indeed appears to be an additive impact of having two parents, rather than just one, with persistently high PTSD symptoms, although the magnitude of these effects was small. The clinical and service provision implications of these findings are discussed
The Effects of the Foreclosure Crisis on the Black and Hispanic Population in Lee County, Florida
The housing foreclosure crisis of 2007-2010 in the United States disproportionately affected persons of color. Some states, such as Florida, were heavily impacted by property value losses yet little is known about the experience of losing a home and recovering from that loss from the perspective of the homeowner. Using Carlson’s conceptualization of resiliency theory, the purpose of this phenomenological study was to assess the impact of housing foreclosure and the experience of recovery from foreclosure on Black and Hispanic people in Lee County, Florida. Data were collected through in-depth interviews with 15 people in Lee County who experienced foreclosure and recovery. Interview data were inductively coded and then subjected to a thematic analysis procedure. Findings revealed that a common experience among participants was that they lacked knowledge about government programs that may have helped them avoid foreclosure, and only a few participants took advantage of emergency assistance offered through local or regional government organizations. In general, people experienced a sense of isolation and had little guidance on recovery options. The positive social change implications of this study include recommendations to government organizations on all levels to enhance outreach efforts to help struggling families avoid foreclosure, including considering creative funding mechanisms to offer assistance
A new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant
We present initial results from a time-series BVI survey of two fields in NGC
4258 using the Advanced Camera for Surveys onboard the Hubble Space Telescope.
This galaxy was selected because of its accurate maser-based distance, which is
anticipated to have a total uncertainty of ~3%. The goal of the HST
observations is to provide an absolute calibration of the Cepheid Distance
Scale and to measure its dependence on chemical abundance (the so-called
"metallicity effect").
We carried out observations of two fields at different galactocentric
distances with a mean abundance difference of 0.5 dex. We discovered a total of
281 Cepheids with periods ranging from 4 to 45 days (the duration of our
observing window). We determine a Cepheid distance modulus for NGC 4258
(relative to the LMC) of 10.88 +- 0.04 (random) +- 0.05 (systematic) mag. Given
the published maser distance to the galaxy, this implies \mu (LMC)=18.41 +-
0.10 (r) +- 0.13 (s) mag or D(LMC)= 48.1 +- 2.3 (r) +- 2.9 (s) kpc. We measure
a metallicity effect of \gamma=-0.29 +- 0.09 (r) +- 0.05 (s) mag/dex. We see no
evidence for a variation in the slope of the Period-Luminosity relation as a
function of abundance.
We estimate a Hubble Constant of H_0= 74 +- 3 (r) +- 6 (s) km/s Mpc using a
recent sample of 4 well-observed type Ia SNe and our new calibration of the
Cepheid Distance Scale. It may soon be possible to measure the value of H_0
with a total uncertainty of 5%, with consequent improvement in the
determination of the equation of state of dark energy.Comment: 39 pages, 24 figures. Accepted for publication in the Astrophysical
Journal. Full-resolution version available in PS and PDF formats at
http://www.noao.edu/staff/lmacri/0608211-full.ps.gz and
http://www.noao.edu/staff/lmacri/0608211-full.pd
Decoherence of Einstein-Podolsky-Rosen steering
We consider two systems A and B that share Einstein-Podolsky-Rosen (EPR)
steering correlations and study how these correlations will decay, when each of
the systems are independently coupled to a reservoir. EPR steering is a
directional form of entanglement, and the measure of steering can change
depending on whether the system A is steered by B, or vice versa. First, we
examine the decay of the steering correlations of the two-mode squeezed state.
We find that if the system B is coupled to a reservoir, then the decoherence of
the steering of A by B is particularly marked, to the extent that there is a
sudden death of steering after a finite time. We find a different directional
effect, if the reservoirs are thermally excited. Second, we study the
decoherence of the steering of a Schr\"odinger cat state, modeled as the
entangled state of a spin and harmonic oscillator, when the macroscopic system
(the cat) is coupled to a reservoir
Building leadership capacity and future leaders in operational research in low-income countries: why and how?
Very limited operational research (OR) emerges from programme settings in low-income countries where the greatest burden of disease lies. The price paid for this void includes a lack of understanding of how health systems are actually functioning, not knowing what works and what does not, and an inability to propose adapted and innovative solutions to programme problems. We use the National Tuberculosis Control Programme as an example to advocate for strong programme-level leadership to steer OR and build viable relationships between programme managers, researchers and policy makers. We highlight the need to create a stimulating environment for conducting OR and identify some of the main practical challenges and enabling factors at programme level. We focus on the important role of an OR focal point within programmes and practical approaches to training that can deliver timely and quantifiable outputs. Finally, we emphasise the need to measure successful OR leadership development at programme level and we propose parameters by which this can be assessed. This paper 1) provides reasons why programmes should take the lead in coordinating and directing OR, 2) identifies the practical challenges and enabling factors for implementing, managing and sustaining OR and 3) proposes parameters for measuring successful leadership capacity development in OR
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