2,297 research outputs found
Young Clusters in the Nuclear Starburst of M 83
We present a photometric catalog of 45 massive star clusters in the nuclear
starburst of M 83 (NGC 5236), observed with the Hubble Space Telescope WFPC2,
in both broad-band (F300W, F547M, and F814W) and narrow-band (F656N and F487N)
filters. By comparing the photometry to theoretical population synthesis
models, we estimate the age and mass of each cluster. We find that over 75% of
the star clusters more massive than 2*10^4 Msun in the central 300 pc of M 83
are less than 10 Myr old. Among the clusters younger than 10 Myr and more
massive than 5*10^3 Msun, 70% are between 5 and 7 Myr old. We list an
additional 330 clusters that are detected in our F300W images, but not in the
shallower F547M and F814W images. The clusters are distributed throughout a
semicircular annulus that identifies the active region in the galaxy core,
between 50 and 130 pc from the optical center of M 83. Clusters younger than 5
Myr are preferentially found along the perimeter of the semicircular annulus.
We suggest that the 5-7 Myr population has evacuated much of the interstellar
material from the active ringlet region, and that star formation is continuing
along the edges of the region.Comment: 40 pages, 13 figures, accepted to ApJ
The Luminous Starburst Ring in NGC 7771: Sequential Star Formation?
Only two of the twenty highly luminous starburst galaxies analyzed by Smith
et al. exhibit circumnuclear rings of star formation. These galaxies provide a
link between 10^11 L_sun systems and classical, less-luminous ringed systems.
We report the discovery of a near-infrared counterpart to the nuclear ring of
radio emission in NGC 7771. A displacement between the ~10 radio bright clumps
and the ~10 near-infrared bright clumps indicates the presence of multiple
generations of star formation. The estimated thermal emission from each radio
source is equivalent to that of ~35000 O6 stars. Each near-infrared bright knot
contains ~5000 red supergiants, on average. The stellar mass of each knot is
estimated to be ~10^7 M_sun. The implied time-averaged star formation rate is
\~40 M_sun per yr. Several similarities are found between the properties of
this system and other ringed and non-ringed starbursts. Morphological
differences between NGC 7771 and the starburst + Seyfert 1 galaxy NGC 7469
suggest that NGC 7771 may not be old enough to fuel an AGN, or may not be
capable of fueling an AGN. Alternatively, the differences may be unrelated to
the presence or absence of an AGN and may simply reflect the possibility that
star formation in rings is episodic.Comment: accepted for publication in The Astrophysical Journal (10 January
1999); 48 pages including 13 figures; AAS LaTe
Developing and sustaining specialist and advanced practice roles in nursing and midwifery: A discourse on enablers and barriers
Aims and objectives
To collate, synthesise and discuss published evidence and expert professional opinion on enablers and barriers to the development and sustainability of specialist and advanced practice roles in nursing and midwifery. Background
Expanded practice is a response to population health needs, healthcare costs and practitioners’ willingness to expand their scope of practice through enhanced responsibility, accountability and professional autonomy. Design
This discursive paper is based on a rapid review of literature on enablers and barriers to the development and sustainability of specialist and advanced practice roles and is part of a wider policy analysis. Methods
We analysed and synthesised of 36 research articles, reviews and discussion papers on enablers and barriers in the development and sustainability of expanded practice roles. Results
Several factors enable role expansion, including: role clarity; credentialing and endorsement; availability of education for expanded roles; individual practitioners’ dispositions towards role expansion; support from peers, other professionals and the work organisation; and costs. Where limited or absent, these same factors can constrain role expansion. Conclusions
Enabling nurses and midwives to practice to their full scope of education and expertise is a global challenge for disciplinary leadership, a national challenge for professional regulation and a local challenge for employers and individual clinicians. These challenges need to be addressed through multistakeholder coordinated efforts at these four levels. Relevance to clinical practice
This discursive paper synthesises empirical evidence and expert professional opinion on the factors that enable or hinder the development and sustainability of specialist and advanced practice roles. Providing a critical appraisal of current knowledge, it provides a reference source for disciplinary debate and policy development regarding the nursing and midwifery resource and informs clinicians of the myriad issues that can impact on their capacity to expand their scope of practice
Wetland mapping and fen survey in the White River National Forest
Prepared for: John Proctor, Forest Botanist, White River National Forest.Includes bibliographical references (page 10).In January 2011, Colorado State University and the Colorado Natural Heritage Program (CNHP) contracted with the White River National Forest (WRNF) to complete wetland mapping and fen field surveys within the White River National Forest (WRNF). Since, 2008, CNHP has been working with the U.S. Fish and Wildlife Service's National Wetland Inventory (NWI) Program and numerous funding partners to create a comprehensive digital map of wetlands for the state of Colorado by 2015. The digitizing and mapping of the wetlands within the WRNF is integral to CNHP's goal to determine the extent and location of wetlands across the state. In addition to the digitizing of the 124 NWI maps, a subset of mapped wetlands consisting of 39 (original number was 25) fens were field surveyed during 2011. The data collected from this project will be added to the CNHP database of critical biological resources, including unique wetlands such as fens. This project will continue to build upon CNHP's past wetland survey and assessment projects
Optometric assessment and co-management of patients with inner ear disorders
Patients often present to the optometrist with symptoms of dizziness and imbalance. This article reviews the most common visual signs and symptoms of individuals suffering from peripheral vestibular disorders. It also explains the five most common peripheral vestibular disorders-benign paroxysmal positional vertigo/nystagmus, Meniere\u27s disease, secondary hydrops, perilymph fistula, and vestibular neuritis. A vestibular screening battery that can be performed by optometrists in office is presented. Management and treatment options such as lenses, prisms and vision therapy are explored. In addition, proper referral guidelines to neuro-otologists, physical therapists, occupational therapists, and psychologists are discussed
Sudden Cardiac Death Among Firefighters ≤45 Years of Age in the United States
Sudden cardiac death (SCD) is the leading cause of death in firefighters.
Although on-duty SCD usually occurs in older victims almost exclusively because
of coronary heart disease, no studies have examined causation across the career
span. In the present retrospective case-control study, cases of SCD in young
(aged ≤45 years) firefighters from the National Institute for Occupational Safety
and Health fatality investigations (n = 87) were compared with 2 age- and
gender-matched control groups: occupationally active firefighters (n = 915) and
noncardiac traumatic firefighter fatalities (n = 56). Of the SCD cases, 63% were
obese and 67% had a coronary heart disease-related cause of death. The SCD
victims had much heavier hearts (522 ± 102 g) than noncardiac fatality controls
(400 ± 91 g, p 450 g) was found in 66% of
the SCD victims and conveyed a fivefold increase (95% confidence interval [CI]
1.93 to 12.4) in SCD risk. Furthermore, hypertension, including cases with left
ventricular hypertrophy, increased SCD risk by 12-fold (95% CI 6.23 to 22.3)
after multivariate adjustment. A history of cardiovascular disease and smoking
were also independently associated with elevated SCD risk (odds ratio 6.89, 95%
CI 2.87 to 16.5; and odds ratio 3.53, 95% CI 1.87 to 6.65, respectively). In
conclusion, SCD in young firefighters is primarily related to preventable
lifestyle factors. Obesity entry standards, smoking bans, and improved screening
and/or wellness program are potential strategies to reduce SCD in younger
firefighters
A New Probe of the Molecular Gas in Galaxies: Application to M101
Recent studies of nearby spiral galaxies suggest that photodissociation
regions (PDRs) are capable of producing much of the observed HI in galaxy
disks. In that case, measurements of the HI column density and the
far-ultraviolet (FUV) photon flux provide a new probe of the volume density of
the local underlying H_2. We develop the method and apply it to the giant Scd
spiral M101 (NGC 5457). We find that, after correction for the best-estimate
gradient of metallicity in the ISM of M101 and for the extinction of the
ultraviolet emission, molecular gas with a narrow range of density from 30-1000
cm^-3 is found near star- forming regions at all radii in the disk of M101 out
to a distance of 12' (approximately 26 kpc), close to the photometric limit of
R_25 = 13.5'.
In this picture, the ISM is virtually all molecular in the inner parts of
M101. The strong decrease of the HI column density in the inner disk of the
galaxy at R_G < 10 kpc is a consequence of a strong increase in the dust-to-gas
ratio there, resulting in an increase of the H_2 formation rate on grains and a
corresponding disappearance of hydrogen in its atomic form.Comment: accepted for publication in The Astrophysical Journal (1 August
2000); 29 pages including 20 figures (7 gif); AAS LaTex; contact authors for
full resolution versions of gif figure
Impact of Cannabis Use on Treatment Outcomes among Adults Receiving Cognitive-Behavioral Treatment for PTSD and Substance Use Disorders
Background: Research has demonstrated a strong link between trauma, posttraumatic stress disorder (PTSD) and substance use disorders (SUDs) in general and cannabis use disorders in particular. Yet, few studies have examined the impact of cannabis use on treatment outcomes for individuals with co-occurring PTSD and SUDs. Methods: Participants were 136 individuals who received cognitive-behavioral therapies for co-occurring PTSD and SUD. Multivariate regressions were utilized to examine the associations between baseline cannabis use and end-of-treatment outcomes. Multilevel linear growth models were fit to the data to examine the cross-lagged associations between weekly cannabis use and weekly PTSD symptom severity and primary substance use during treatment. Results: There were no significant positive nor negative associations between baseline cannabis use and end-of-treatment PTSD symptom severity and days of primary substance use. Cross-lagged models revealed that as cannabis use increased, subsequent primary substance use decreased and vice versa. Moreover, results revealed a crossover lagged effect, whereby higher cannabis use was associated with greater PTSD symptom severity early in treatment, but lower weekly PTSD symptom severity later in treatment. Conclusion: Cannabis use was not associated with adverse outcomes in end-of-treatment PTSD and primary substance use, suggesting independent pathways of change. The theoretical and clinical implications of the reciprocal associations between weekly cannabis use and subsequent PTSD and primary substance use symptoms during treatment are discussed
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