A near-infrared study of the star forming region RCW 34

We report the results of a near-infrared imaging study of a $7.8 \times 7.8$ arcmin$^2$ region centered on the 6.7 GHz methanol maser associated with the RCW 34 star forming region using the 1.4m IRSF telescope at Sutherland. A total of 1283 objects were detected simultaneously in J, H, and K for an exposure time of 10800 seconds. The J-H, H-K two-colour diagram revealed a strong concentration of more than 700 objects with colours similar to what is expected of reddened classical T Tauri stars. The distribution of the objects on the K {\it vs} J-K colour-magnitude diagram is also suggestive that a significant fraction of the 1283 objects is lower mass pre-main sequence stars. We also present the luminosity function for the subset of about 700 pre-main sequence stars and show that it suggests ongoing star formation activity for about $10^7$ years. An examination of the spatial distribution of the pre-main sequence stars shows that the fainter (older) part of the population is more dispersed over the observed region and the brighter (younger) subset is more concentrated around the position of the O8.5V star. This suggests that the physical effects of the O8.5V star and the two early B-type stars on the remainder of the cloud out of which they formed, could have played a role in the onset of the more recent episode of star formation in RCW 34.Comment: Accepted for publication in The Astronomical Journa

Photodynamic diagnosis of breast tumours after oral application of aminolevulinic acid

Photodynamic diagnosis is of increasing interest for diagnosis in oncology. It is based on a more intense incorporation of a fluorescent dye in tumours compared to normal tissue. As a feasibility study we investigated the effectiveness of oral application of 5-aminolevulinic acid for photodynamic diagnosis of human primary mammary tumours. The study included 16 patients with palpable breast tumours. Aminolevulinic acid was administered at a concentration of 40 mg kg−1bodyweight 150–420 min prior to tumourectomy. Intraoperatively blue light (405 nm) was applied to the operation site. Sections of the excised tumour and some lymph nodes were prepared and analysed with a fluorescent microscope. All primary mammary tumour tissues showed significantly higher fluorescence intensity than surrounding normal mammary tissue. Fluorescence of the mammary tumours could also be discriminated macroscopically and intraoperatively. Fluorescence intensity in nonmetastatic lymph node tissue was higher in 2 out of 3 patients than in primary tumour tissue. By photodynamic diagnosis using aminolevulinic acid we were able to reliably distinguish primary mammary tumours from normal mammary tissue microscopically and macroscopically in all our patients. We suggest that photodynamic diagnosis with aminolevulinic acid for breast tumours should be further investigated and developed for intraoperative use and may well be a simple tool for better intraoperative diagnosis and recognition of tumour margins. We hypothesize that lymph node metastasis of breast tumours will not be detectable by this method. © 2001 Cancer Research Campaign http://www.bjcancer.co

Molecular Line Observations of Infrared Dark Clouds: Seeking the Precursors to Intermediate and Massive Star Formation

We have identified 41 infrared dark clouds from the 8 micron maps of the Midcourse Space Experiment (MSX), selected to be found within one square degree areas centered on known ultracompact HII regions. We have mapped these infrared dark clouds in N2H+(1-0), CS(2-1) and C18O(1-0) emission using the Five College Radio Astronomy Observatory. The maps of the different species often show striking differences in morphologies, indicating differences in evolutionary state and/or the presence of undetected, deeply embedded protostars. We derive an average mass for these clouds using N2H+ column densities of ~2500 solar masses, a value comparable to that found in previous studies of high mass star forming cores using other mass tracers. The linewidths of these clouds are typically ~2.0 - 2.9 km/s. Based on the fact that they are dark at 8 micron, compact, massive, and have large velocity dispersions, we suggest that these clouds may be the precursor sites of intermediate and high mass star formation.Comment: Accepted to ApJS, 22 pages, 10 pages of figures. For full-resolution images, see http://www.astro.lsa.umich.edu/~seragan/pubs/fcrao/figures.tar.g

On the Identification of High Mass Star Forming Regions using IRAS: Contamination by Low-Mass Protostars

We present the results of a survey of a small sample (14) of low-mass protostars (L_IR < 10^3 Lsun) for 6.7 GHz methanol maser emission performed using the ATNF Parkes radio telescope. No new masers were discovered. We find that the lower luminosity limit for maser emission is near 10^3 Lsun, by comparison of the sources in our sample with previously detected methanol maser sources. We examine the IRAS properties of our sample and compare them with sources previously observed for methanol maser emission, almost all of which satisfy the Wood & Churchwell criterion for selecting candidate UCHII regions. We find that about half of our sample satisfy this criterion, and in addition almost all of this subgroup have integrated fluxes between 25 and 60 microns that are similar to sources with detectable methanol maser emission. By identifying a number of low-mass protostars in this work and from the literature that satisfy the Wood & Churchwell criterion for candidate UCHII regions, we show conclusively for the first time that the fainter flux end of their sample is contaminated by lower-mass non-ionizing sources, confirming the suggestion by van der Walt and Ramesh & Sridharan.Comment: 8 pages with 2 figures. Accepted by Ap

Evaluation of a peri-urban community health worker project in the western Cape

The South African Christian Leadership Assembly (SACLA) Health Project is a non-governmental organisation that runs a community health worker (CHW) programme in 4 peri-urban townships of Cape Town. A cross-sectional descriptive community survey was conducted in April 1990 to evaluate coverage and health education on oral rehydration solution (ORS) and to plan future preventive, promotive and development programmes.· Research concepts and methods were made accessible to the CHWs through a training process designed to facilitate participation in every stage of the research. A multi-stage cluster sampling scheme was used, and the CHWs interviewed 822 residents. Coverage indicators showed that over 80% of all respondents had previously known about or consulted the CHW. The most common community problems related to water, filth and refuse, toilets, housing, unemployment and lack of community facilities. The most common health problems were generalised aches and pains, chest problems, skin problems, worms, and diarrhoea. An index developed to measure knowledge of ORS showed very few respondents had 'complete knowledge'. The community's expectations of the CHW included health education, attending to sanitation problems, providing a clean environment, organising community facilities, and helping with employment

A multidimensional examination of marital conflict and subjective health over 16 years

Guided by stress process perspectives, this study conceptualizes marital conflict as a multidimensional stressor to assess how three aspects of conflict—frequency of disagreements, breadth of disagreements, and cumulative disagreements—impact subjective health. Longitudinal data of married couples spanning 16 years (n = 373 couples) were analyzed using multilevel modeling. For husbands, more frequent disagreements than usual within a given year were associated with poorer subjective health. For wives, the greater cumulative effects of disagreements over 16 years were harmful for subjective health. We discuss how gendered self‐representations and relationship power issues help explain the findings. This research demonstrated the importance of examining multiple aspects of marital conflict to reveal that their subjective health consequences function differently for wives and husbands.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151831/1/pere12292_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151831/2/pere12292.pd

New Periodic 6.7 GHz Class II Methanol Maser Associated with G358.460-0.391

Eight new class II methanol masers selected from the 6.7 GHz Methanol Multibeam survey catalogues I and II were monitored at 6.7 GHz with the 26m Hartebeesthoek Radio Astronomy Observatory (HartRAO) radio telescope for three years and seven months, from February 2011 to September 2014. The sources were also observed at 12.2 GHz and two were sufficiently bright to permit monitoring. One of the eight sources, namely G358.460-0.391, was found to show periodic variations at 6.7 GHz. The period was determined and tested for significance using the Lomb-Scargle, epoch-folding and Jurkevich methods, and by fitting a simple analytic function. The best estimate for the period of the 6.7 GHz class II methanol maser line associated with G358.460-0.391 is 220.0 $\pm$ 0.2 day.Comment: 8 pages, 11 figures, accepted for publication in MNRAS. The appendix of 4 pages (with 16 figures) will be published as online versio

Methanol masers : Reliable tracers of the early stages of high-mass star formation

The GLIMPSE and MSX surveys have been used to examine the mid-infrared properties of a statistically complete sample of 6.7 GHz methanol masers. The GLIMPSE point sources associated with methanol masers are clearly distinguished from the majority, typically having extremely red mid-infrared colors, similar to those expected of low-mass class 0 young stellar objects. The intensity of the GLIMPSE sources associated with methanol masers is typically 4 magnitudes brighter at 8.0 micron than at 3.6 micron. Targeted searches towards GLIMPSE point sources with [3.6]-[4.5] > 1.3 and an 8.0 micron magnitude less than 10 will detect more than 80% of class II methanol masers. Many of the methanol masers are associated with sources within infrared dark clouds (IRDC) which are believed to mark regions where high-mass star formation is in its very early stages. The presence of class II methanol masers in a significant fraction of IRDC suggests that high-mass star formation is common in these regions. Different maser species are thought to trace different evolutionary phases of the high-mass star formation process. Comparison of the properties of the GLIMPSE sources associated with class II methanol masers and other maser species shows interesting trends, consistent with class I methanol masers tracing a generally earlier evolutionary phase and OH masers tracing a later evolutionary phase.Comment: 45 pages, 19 figures, accepted for publication in Ap

Time evolution of the Rabi Hamiltonian from the unexcited vacuum

The Rabi Hamiltonian describes a single mode of electromagnetic radiation interacting with a two-level atom. Using the coupled cluster method, we investigate the time evolution of this system from an initially empty field mode and an unexcited atom. We give results for the atomic inversion and field occupation, and find that the virtual processes cause the field to be squeezed. No anti-bunching occurs.Comment: 25 pages, 8 figures, RevTe