4,863 research outputs found
EVLA Observations of OH Masers in ON 1
This Letter reports on initial Expanded Very Large Array (EVLA) observations
of the 6035 MHz masers in ON 1. The EVLA data are of good quality, lending
confidence in the new receiver system. Nineteen maser features, including six
Zeeman pairs, are detected. The overall distribution of 6035 MHz OH masers is
similar to that of the 1665 MHz OH masers. The spatial resolution is sufficient
to unambiguously determine that the magnetic field is strong (~ -10 mG) at the
location of the blueshifted masers in the north, consistent with Zeeman
splitting detected in 13441 MHz OH masers in the same velocity range. Left and
right circularly polarized ground-state features dominate in different regions
in the north of the source, which may be due to a combination of magnetic field
and velocity gradients. The combined distribution of all OH masers toward the
south is suggestive of a shock structure of the sort previously seen in W3(OH).Comment: 4 pages using emulateapj.cls including 2 tables and 2 color figure
Lithium abundances in nearby FGK dwarf and subgiant stars: internal destruction, Galactic chemical evolution, and exoplanets
We derive atmospheric parameters and lithium abundances for 671 stars and
include our measurements in a literature compilation of 1381 dwarf and subgiant
stars. First, a "lithium desert" in the effective temperature (Teff) versus
lithium abundance (A_Li) plane is observed such that no stars with Teff~6075 K
and A_Li~1.8 are found. We speculate that most of the stars on the low A_Li
side of the desert have experienced a short-lived period of severe surface
lithium destruction as main-sequence or subgiant stars. Next, we search for
differences in the lithium content of thin-disk and thick-disk stars, but we
find that internal processes have erased from the stellar photospheres their
possibly different histories of lithium enrichment. Nevertheless, we note that
the maximum lithium abundance of thick-disk stars is nearly constant from
[Fe/H]=-1.0 to -0.1, at a value that is similar to that measured in very
metal-poor halo stars (A_Li~2.2). Finally, differences in the lithium abundance
distribution of known planet-host stars relative to otherwise ordinary stars
appear when restricting the samples to narrow ranges of Teff or mass, but they
are fully explained by age and metallicity biases. We confirm the lack of a
connection between low lithium abundance and planets. However, we find that no
low A_Li planet-hosts are found in the desert Teff window. Provided that subtle
sample biases are not responsible for this observation, this suggests that the
presence of gas giant planets inhibit the mechanism responsible for the lithium
desert.Comment: ApJ, in press. Complete Tables 1 and 3 are available upon reques
Large Magnetic Fields and Motions of OH Masers in W75 N
We report on a second epoch of VLBA observations of the 1665 and 1667 MHz OH
masers in the massive star-forming region W75 N. We find evidence to confirm
the existence of very strong (~40 mG) magnetic fields near source VLA 2. The
masers near VLA 2 are dynamically distinct and include a very bright spot
apparently moving at 50 km/s relative to those around VLA 1. This fast-moving
spot may be an example of a rare class of OH masers seen in outflows in
star-forming regions. Due to the variability of these masers and the rapidity
of their motions, tracking these motions will require multiple observations
over a significantly shorter time baseline than obtained here. Proper motions
of the masers near VLA 1 are more suggestive of streaming along magnetized
shocks rather than Keplerian rotation in a disk. The motions of the easternmost
cluster of masers in W75 N (B) may be tracing slow expansion around an unseen
exciting source.Comment: 7 pages including 4 figures (2 color) & 3 tables, to appear in Ap
Editing Sophia Peabody’s Cuba Journal: Travel, Recovery, and Interpretation
Some collaborations are born out of chance encounters. For us, it happened at a recent conference of the Society for the Study of American Women Writers. Having briefly met before on the common ground of studies in nineteenth- century American literature, we said “Hello” and discovered in the space of a five-minute conversation that both of us had our eyes on the early nineteenth- century journal-account of a young New Englander’s rest cure in Cuba. The traveler who authored the journal was Sophia Amelia Peabody (1809–1871), an accomplished visual artist, writer, member of a family that was vitally involved in the intellectual and cultural life of antebellum New England, and later Nathaniel Hawthorne’s collaborator and wife. Creating an edition of her crumb - ling unpublished manuscript from the 1830s had begun to take shape in our respective research plans, but after discussing our individual intentions, we eventually agreed to embark on the project together. We come to Peabody’s text with complementary angles of interest: Cheryl J. Fish, in women’s travel texts of nineteenth-century America and the intersections among travel, race, and disability studies; Jana Argersinger, in “relational aesthetics,” theories of antebellum female authorship, and scholarly editing
Magnetic Field Clumping in Massive Star-Forming Regions as Determined from Excited-State OH Absorption and Maser Emission
We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2
lines of OH using the GBT in order to investigate whether the magnetic field,
and hence the density, measured in absorption differs from that implied by
maser Zeeman splitting. We detect absorption in both the 13441 and 13434 MHz
main lines in all six sources. Zeeman splitting in the F = 3-3 absorption line
in W3(OH) implies a line-of-sight magnetic field strength of 3.0 +/- 0.3 mG.
This is significantly less than full magnetic field strengths detected from OH
maser Zeeman splitting, suggesting that OH maser regions may be denser than the
non-masing OH material by a factor of several. Zeeman splitting is not detected
in other sources, but we are able to place upper limits on B_parallel of 1.2 mG
in G10.624-0.385 and 2.9 mG in K3-50. These results are consistent with a
density enhancement of the masers, but other explanations for the lower
magnetic field in absorption compared to maser emission are possible for these
two sources. Absorption in one or both of the 13442 and 13433 MHz satellite
lines is also seen in four sources. This is the very first detection of the 2
Pi 3/2, J = 7/2 satellite lines. Ratios of satellite-line to main-line
absorption suggest enhancement of the satellite lines from local thermodynamic
equilibrium values. Masers are seen in the F = 4-4 and 3-3 transitions of
W3(OH) and the 4-4 transition of ON 1. A previously undetected 4-4 maser is
seen near -44.85 km/s in W3(OH).Comment: 29 pages, 22 figures, scheduled to be published in 20 April 2005
issue of ApJ (vol 623, no 2
When the clinic is not yet built … the Avian Park Service Learning Centre story
The Ukwanda Centre for Rural Health (UCRH) opened in 2001, followed 10 years later by the establishment of the Ukwanda Rural Clinical School in one of the rural health districts of the Western Cape. This paper relates the journey of the Faculty with the underserviced community of Avian Park through the provision of healthcare services aimed at addressing needs identified by the local community. It attempts to substantiate the meaning of the word Ukwanda, translated ‘to grow’ and ‘develop within the community’ in order to reach the primary goal of being an ‘engaged institution’. The Avian Park Service Learning Centre (APSLC) is the culmination of the aspirations of a number of stakeholders who wanted to respond to the community needs for access to basic healthcare while providing learning opportunities for students. Initially only patients with chronic diseases of lifestyle, tuberculosis (TB) and HIV/AIDS were seen by community care-workers (CCWs). Through a number of service-learning initiatives in Avian Park, a variety of health services have developed in the community. CCWs have become teachers, community developers and an integral part of the health service team. They enhance access to the residents, community projects and networking within the community.The APSLC improves the opportunities to integrate theoretical academic work with practical application, providing students with a unique opportunity to be involved in healthcare service design and development (as active participants, not observers) based on community-identified needs. University and community collaboration has been purposeful and aims to strengthen community engagement, while up-skilling residents and affording community-based education opportunities for health professions
Full-Polarization Observations of OH Masers in Massive Star-Forming Regions: I. Data
We present full-polarization VLBA maps of the ground-state, main-line, 2 Pi
3/2, J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the
first large polarization survey of interstellar hydroxyl masers at VLBI
resolution. A total of 184 Zeeman pairs are identified, and the corresponding
magnetic field strengths are indicated. We also present spectra of the NH3
emission or absorption in these star-forming regions. Analysis of these data
will be presented in a companion paper.Comment: 111 pages, including 42 figures and 21 tables, to appear in ApJ
Cost of survivorship care and adherence to screening-aligning the priorities of health care systems and survivors.
Childhood cancer survivors (CCS) experience significant morbidity due to treatment- related late effects and benefit from late-effects surveillance. Adherence to screening recommendations is suboptimal. Survivorship care programs often struggle with resource limitations and may benefit from understanding institution-level financial outcomes associated with patient adherence to justify programmatic development and growth. The purpose of this study is to examine how CCS adherence to screening recommendations relates to the cost of care, insurance status, and institution-level financial outcomes. A retrospective chart review of 286 patients, followed in a structured survivorship program, assessed adherence to the Children\u27s Oncology Group follow-up guidelines by comparing recommended versus performed screening procedures for each patient. Procedure cost estimates were based on insurance status. Institutional profit margins and profit opportunity loss were calculated. Bivariate statistics tested adherent versus nonadherent subgroup differences on cost variables. A generalized linear model predicted the likelihood of adherence based on cost of recommended procedures, controlling for age, gender, race, and insurance. Adherence to recommended surveillance procedures was 50.2%. Nonadherence was associated with higher costs of recommended screening procedures compared to the adherent group estimates (1,211.44). Failure to perform the recommended tests resulted in no difference in reimbursement to the health system between groups (1,211.08). For the nonadherent group, this represented 311,850 in lost profit opportunity due to nonadherence in this subgroup. In the final model, nonadherence was related to higher cost of recommended procedures (p \u3c .0001), older age at visit (p = .04), Black race (p = .02), and government-sponsored insurance (p = .03). Understanding institutional financial outcomes related to patient adherence may help inform survivorship care programs and resource allocation. Potential financial burden to patients associated with complex care recommendations is also warranted
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