1,233 research outputs found
Chandra Observations of Arp 220: The Nuclear Source
We present the first results from 60ks of observations of Arp 220 using the
ACIS-S instrument on Chandra. We report the detection of several sources near
the galaxy's nucleus, including a point source with a hard spectrum that is
coincident with the western radio nucleus B. This point source is mildly
absorbed (N_H ~ 3 x 10^22 cm^-2) and has an estimated luminosity of 4 x 10^40
erg/s. In addition, a fainter source may coincide with the eastern nucleus A.
Extended hard X-ray emission in the vicinity raises the total estimated nuclear
2-10 keV X-ray luminosity to 1.2 x 10^41 erg/s, but we cannot rule out a hidden
AGN behind columns exceeding 5 x 10^24 cm^-2. We also detect a peak of soft
X-ray emission to the west of the nucleus, and a hard point source 2.5 kpc from
the nucleus with a luminosity of 6 x 10^39 erg/s.Comment: Accepted for publication in Ap
Chandra Observations of Arp 220: The Nuclear Source
We present the first results from 60ks of observations of Arp 220 using the
ACIS-S instrument on Chandra. We report the detection of several sources near
the galaxy's nucleus, including a point source with a hard spectrum that is
coincident with the western radio nucleus B. This point source is mildly
absorbed (N_H ~ 3 x 10^22 cm^-2) and has an estimated luminosity of 4 x 10^40
erg/s. In addition, a fainter source may coincide with the eastern nucleus A.
Extended hard X-ray emission in the vicinity raises the total estimated nuclear
2-10 keV X-ray luminosity to 1.2 x 10^41 erg/s, but we cannot rule out a hidden
AGN behind columns exceeding 5 x 10^24 cm^-2. We also detect a peak of soft
X-ray emission to the west of the nucleus, and a hard point source 2.5 kpc from
the nucleus with a luminosity of 6 x 10^39 erg/s.Comment: Accepted for publication in Ap
A Hubble Space Telescope Snapshot Survey of Dynamically Close Galaxy Pairs in the CNOC2 Redshift Survey
We compare the structural properties of two classes of galaxies at
intermediate redshift: those in dynamically close galaxy pairs, and those which
are isolated. Both samples are selected from the CNOC2 Redshift Survey, and
have redshifts in the range 0.1 < z <0.6. Hubble Space Telescope WFPC2 images
were acquired as part of a snapshot survey, and were used to measure bulge
fraction and asymmetry for these galaxies. We find that paired and isolated
galaxies have identical distributions of bulge fractions. Conversely, we find
that paired galaxies are much more likely to be asymmetric (R_T+R_A >= 0.13)
than isolated galaxies. Assuming that half of these pairs are unlikely to be
close enough to merge, we estimate that 40% +/- 11% of merging galaxies are
asymmetric, compared with 9% +/- 3% of isolated galaxies. The difference is
even more striking for strongly asymmetric (R_T+R_A >= 0.16) galaxies: 25% +/-
8% for merging galaxies versus 1% +/- 1% for isolated galaxies. We find that
strongly asymmetric paired galaxies are very blue, with rest-frame B-R colors
close to 0.80, compared with a mean (B-R)_0 of 1.24 for all paired galaxies. In
addition, asymmetric galaxies in pairs have strong [OII]3727 emission lines. We
conclude that close to half of the galaxy pairs in our sample are in the
process of merging, and that most of these mergers are accompanied by triggered
star formation.Comment: Accepted for publication in the Astronomical Journal. 40 pages,
including 15 figures. For full resolution version, please see
http://www.trentu.ca/physics/dpatton/hstpairs
A study of the remarkable galaxy system AM 546-324 (the core of Abell S0546)
We report first results of an investigation of the tidally disturbed galaxy
system AM\,546-324, whose two principal galaxies 2MFGC 04711 and AM\,0546-324
(NED02) were previously classified as interacting doubles. This system was
selected to study the interaction of ellipticals in a moderately dense
environment. We provide spectral characteristics of the system and present an
observational study of the interaction effects on the morphology, kinematics,
and stellar population of these galaxies. The study is based on long-slit
spectrophotometric data in the range of 4500-8000 obtained with
the Gemini Multi-Object Spetrograph at Gemini South (GMOS-S). We have used the
stellar population synthesis code STARLIGHT to investigate the star formation
history of these galaxies. The Gemini/GMOS-S direct r-G0303 broad band pointing
image was used to enhance and study fine morphological structures. The main
absorption lines in the spectra were used to determine the radial velocity.
Along the whole long-slit signal, the spectra of the Shadowy galaxy (discovered
by us), 2MFGC 04711, and AM\,0546-324 (NED02) resemble that of an early-type
galaxy. We estimated redshifts of z= 0.0696, z= 0.0693 and z= 0.0718,
corresponding to heliocentric velocities of 20\,141 km s, 20\,057 km
s, and 20\,754 km s for the Shadowy galaxy, 2MFGC 04711 and
AM\,0546-324 (NED02), respectively. ..
Zofenopril: Blood pressure control and cardio-protection
Current hypertension guidelines suggest various strategies to reduce blood pressure levels, thereby reducing cardiovascular events: combinations of drugs with different mechanisms of action, such as an angiotensin converting enzyme inhibitors (ACEIs) and a diuretic, are the cornerstone of the modern treatment of hypertension, also as initial therapy. Among ACEIs, zofenopril has been shown to be effective in the management of hypertension both as monotherapy and in combination with a diuretic: zofenopril/hydrochlorothiazide fixed dose combination is particularly useful to improve treatment adherence through simplification of treatment regimen. Moreover, thanks to the sulfhydryl group, zofenopril has some peculiar properties (higher lipophilicity and tissue penetration, lower bradykinin-dependent effect, higher affinity for, and more persistent binding to, tissue ACE, significant antioxidant effect), which may account for the cardioprotective effects of the drug demonstrated in both pre-clinical studies and randomized clinical trials. The positive impact of zofenopril on clinical outcomes has been extensively documented by the SMILE program, including several clinical trials in patients with different conditions of myocardial ischemia treated with zofenopril: the results of the SMILE program, demonstrating the benefits of zofenopril vs. placebo and other ACEIs, emphasize the importance of a differentiated approach to patients with ischemic heart disease, based on a careful choice of the adopted agent, in order to improve the overall impact of pharmacological treatment on clinical outcomes
Chandra Observations of Extended X-ray Emission in Arp 220
We resolve the extended X-ray emission from the prototypical ultraluminous
infrared galaxy Arp 220. Extended, faint edge-brightened, soft X-ray lobes
outside the optical galaxy are observed to a distance of 10 to 15 kpc on each
side of the nuclear region. Bright plumes inside the optical isophotes coincide
with the optical line emission and extend 11 kpc from end to end across the
nucleus. The data for the plumes cannot be fit by a single temperature plasma,
and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from
bright, diffuse circumnuclear emission in the inner 3 kpc centered on the
Halpha peak, which is displaced from the radio nuclei. There is a close
morphological correspondence between the Halpha and soft X-ray emission on all
spatial scales. We interpret the plumes as a starburst-driven superwind, and
discuss two interpretations of the emission from the lobes in the context of
simulations of the merger dynamics of Arp 220.Comment: Accepted for publication in ApJ; see also astro-ph/0208477 (Paper 1
Stigma of People with HIV/AIDS in Sub-Saharan Africa: A Literature Review
The aim of this
literature review is to elucidate what is known
about HIV/AIDS and stigma in Sub-Saharan Africa.
Literature about HIV/AIDS and stigma in
Sub-Saharan Africa was systematically searched
in Pubmed, Medscape, and Psycinfo up to March
31, 2009. No starting date limit was specified.
The material was analyzed using Gilmore and
Somerville's (1994) four processes of
stigmatizing responses: the definition of the
problem HIV/AIDS, identification of people
living with HIV/AIDS (PLWHA), linking HIV/AIDS
to immorality and other negative
characteristics, and finally behavioural
consequences of stigma (distancing, isolation,
discrimination in care). It was found that the
cultural construction of HIV/AIDS, based on
beliefs about contamination, sexuality, and
religion, plays a crucial role and contributes
to the strength of distancing reactions and
discrimination in society. Stigma prevents the
delivery of effective social and medical care
(including taking antiretroviral therapy) and
also enhances the number of HIV infections. More
qualitative studies on HIV/AIDS stigma including
stigma in health care institutions in
Sub-Saharan Africa are
recommended
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