43,664 research outputs found
Are Galaxies Optically Thin to Their Own Lyman Continuum Radiation? II. NGC 6822
Halpha and UBV photometry of NGC 6822 are used to study the distribution of
OB stars and HII regions in the galaxy and to determine whether individual
regions of the galaxy are in a state of ionization balance. Four distinct
components of the Halpha emission (bright, halo, diffuse and field)
differentiated by their surface brightnesses are identified. We find that
approximately 1/2 of all OB stars in NGC 6822 are located in the field while
only 1/4 are found in the combined bright and halo regions, suggesting that OB
stars spend roughly 3/4 of their lifetimes outside ``classical'' H II regions.
Comparing the observed Halpha emission with that predicted from stellar
ionizing flux models, we find that although the bright, halo and diffuse
regions are probably in ionization balance, the field region is producing at
least 6 times as much ionizing flux as is observed. The ionization balance
results in NGC 6822 suggest that star formation rates obtained from Halpha
luminosities must underestimate the true star formation rate in this galaxy by
about 50%. Comparing our results for NGC 6822 with previous results for the
spiral galaxy M33, we find that the inner kiloparsec of M33 is in a more
serious state of ionization imbalance, perhaps due to its higher surface
density of blue stars.Comment: Replaced version should now compile with standard aastex style files.
28 pages, aastex preprint format. Accepted in ApJ. Hardcopies of figures
available on request to [email protected]
Urban heritage conservation and rapid urbanization : insights from Surat, India
Currently, heritage is challenged in the Indian city of Surat due to diverse pressures, including rapid urbanization, increasing housing demand, and socio‐cultural and climate changes. Where rapid demographic growth of urban areas is happening, heritage is disappearing at an alarming rate. Despite some efforts from the local government, urban cultural heritage is being neglected and historic buildings keep being replaced by ordinary concrete buildings at a worryingly rapid pace. Discussions of challenges and issues of Surat’s urban area is supported by a qualitative dataset, including in‐depth semi‐structured interviews and focus groups with local policy makers, planners, and heritage experts, triangulated by observation and a photo‐survey of two historic areas. Findings from this study reveal a myriad of challenges such as: inadequacy of urban conservation management policies and processes focused on heritage, absence of skills, training, and resources amongst decision makers and persistent conflict and competition between heritage conservation needs and developers’ interests. Furthermore, the values and significance of Surat’s tangible and intangible heritage is not fully recognized by its citizens and heritage stakeholders. A crucial opportunity exists for Surat to maximize the potential of heritage and reinforce urban identity for its present and future generations. Surat’s context is representative of general trends and conservation challenges and therefore recommendations developed in this study hold the potential to offer interesting insights to the wider planners and conservationists’ international community. This paper recommends thoughtful integration of sustainable heritage urban conservation into local urban development frameworks and the establishment of approaches that recognize the plurality of heritage values
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Promoting positive communication environments: a service evaluation.
Purpose
The purpose of this paper is to present an evaluation of a programme of training and support provided to staff, which aimed to encourage supported communication environments for people with learning disabilities.
Design/methodology/approach
Training, monitoring and support for communication, specifically augmentative and alternative communication (AAC) strategies, was provided by speech and language therapy staff to two residential services over 46 weeks. Staff and service user communications were observed pre- and post-intervention.
Findings
In one provision there was an increase in service user initiations and the use of some AAC strategies by support staff. In the other provision there was no change in service user initiations and a decrease in the range of AAC strategies used. It appears that some forms for AAC remain challenging for staff to implement.
Originality/value
This evaluation explores ways of using specialist support services to improve communication environments for people with learning difficulties. Possible reasons for differences in the outcome of the intervention are discussed. Future research into the types of communication interactions experienced by people with learning disabilities across the range of communication styles may be useful so that support staff can be better helped to provide sustained and enriched communication environments
Expression and regulation of Cek-8, a cell to cell signalling receptor in developing chick limb buds
Are galaxies optically thin to their own Lyman continuum radiation? 2, NGC 6822
Halpha and UBV photometry of NGC 6822 are used to study the distribution of OB stars and HII regions in the galaxy and to determine whether individual regions of the galaxy are in a state of ionization balance. Four distinct components of the Halpha emission (bright, halo, diffuse and field) differentiated by their surface brightnesses are identified. We find that approximately 1/2 of all OB stars in NGC 6822 are located in the field while only 1/4 are found in the combined bright and halo regions, suggesting that OB stars spend roughly 3/4 of their lifetimes outside ``classical'' H II regions. Comparing the observed Halpha emission with that predicted from stellar ionizing flux models, we find that although the bright, halo and diffuse regions are probably in ionization balance, the field region is producing at least 6 times as much ionizing flux as is observed. The ionization balance results in NGC 6822 suggest that star formation rates obtained from Halpha luminosities must underestimate the true star formation rate in this galaxy by about 50%. Comparing our results for NGC 6822 with previous results for the spiral galaxy M33, we find that the inner kiloparsec of M33 is in a more serious state of ionization imbalance, perhaps due to its higher surface density of blue stars
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