8 research outputs found
The OH Masers Towards IRAS 19092+0841
Context. Maser emission is a strong tool for studying high mass star forming
regions and their evolutionary stages. OH masers in particular can trace the
circumstellar material around protostars and determine their magnetic field
strengths at milliarcsecond resolution.
Aims. Imaging OH maser mission towards high mass protostellar objects to
determine their evolutionary stages and to locate the detected maser emission
in the process of high mass star formation.
Methods. In 2007, we surveyed OH maser towards 217 high mass protostellar
objects to study its presence. In this paper, we present a follow up MERLIN
observations of a ground state OH maser emission towards one of these objects,
IRAS 19092+0841.
Results. Emission from the two OH main spectral lines, 1665 and 1667 MHz,
were detected close to the central object. The positions and velocities of the
OH maser features have been determined. The masers are distributed over a
region of ~ 500 corresponding to 22400 AU (or ~ 0.1 pc) at a distance of 4.48
kpc. The polarization properties of the OH maser features were determined as
well. We identify three Zeeman pairs from which we inferred a magnetic field
strength of ~ 4:4mG pointing towards the observer.
Conclusions. The relatively small velocity spread and the relatively wide
spacial distribution of the OH maser features support the suggestion that this
object could be in an early evolutionary state before the presence of disk
and/or jet/outfows.Comment: 6 pages, 2 figures and 3 table
The changing pattern of bloodstream infections associated with the rise in HIV prevalence in northeastern Thailand.
A survey of bloodstream infections was conducted in the large regional hospital in Ubon Ratchatani, northeastern Thailand between 1989 and 1998, during the onset of the HIV epidemic. The incidence of Staphylococcus aureus, Escherichia coli, Klebsiella/Enterobacter and Pseudomonas aeruginosa bacteraemias remained constant whereas infections caused by Burkholderia pseudomallei, non-typhoid Salmonellae, Cryptococcus neoformans, Penicillum marneffei and to a lesser extent Streptococcus pneumoniae all rose. Burkholderia pseudomallei infections were unrelated to HIV, whereas the other infections were associated directly with HIV. Group D non-typhoid Salmonellae bloodstream infections (mainly Salmonella enteritidis) rose coincident with the increase in HIV seroprevalence, and preceded the increase in the other HIV-associated infections. Other non-typhoid Salmonella bacteraemias increased two years after the rise in group D infections, and invasive yeast infections increased four years later, coincident with the increase in AIDS. Increasing Group D non-typhoid Salmonella bloodstream infections are an early warning signal of an impending rise in AIDS