Longitudinal interrelationship between HIV viral suppression, maternal weight change, breastfeeding, and length in HIV-exposed and uninfected infants participating in the Kabeho study in Kigali, Rwanda

Purpose: The health of infants that are HIV-exposed and -uninfected (HEU) is a major public health concern as HIV becomes a chronic condition. We investigate the interrelationship between maternal viral suppression, maternal weight status, breastfeeding, and infants that are HEU. Methods: The Kabeho study followed 502 HEU infants in Kigali, Rwanda, for 24 months from 2013 to 2014. We use a structural equation modeling approach to investigate the dynamic relationships between viral suppression, maternal weight change, breastfeeding, and infant length-for-age z-score (LAZ) as defined by the WHO. Results: Older mothers are more likely to be virally suppressed and to breastfeed. Viral suppression and the mother being on antiretroviral treatment for longer were related to lower infant LAZ at three months. A more positive maternal weight change was related to higher infant LAZ at the end of each period. At 12 months, a higher infant LAZ was related to increased probability of continued breastfeeding. At 18 months, continued breastfeeding was related to lower LAZ, and food shortages were related to higher LAZ. Conclusion: There is a complex interrelationship between viral suppression, maternal weight change, breastfeeding, and infant LAZ. These relationships demonstrate the link between maternal and infant health in the context of HIV

Physical State of Molecular Gas in High Galactic Latitude Translucent Clouds

The rotational transitions of carbon monoxide (CO) are the primary means of investigating the density and velocity structure of the molecular interstellar medium. Here we study the lowest four rotational transitions of CO towards high-latitude translucent molecular clouds (HLCs). We report new observations of the J = (4-3), (2-1), and (1-0) transitions of CO towards eight high-latitude clouds. The new observations are combined with data from the literature to show that the emission from all observed CO transitions is linearly correlated. This implies that the excitation conditions which lead to emission in these transitions are uniform throughout the clouds. Observed 13CO/12CO (1-0) integrated intensity ratios are generally much greater than the expected abundance ratio of the two species, indicating that the regions which emit 12CO (1-0) radiation are optically thick. We develop a statistical method to compare the observed line ratios with models of CO excitation and radiative transfer. This enables us to determine the most likely portion of the physical parameter space which is compatible with the observations. The model enables us to rule out CO gas temperatures greater than 30K since the most likely high-temperature configurations are 1 pc-sized structures aligned along the line of sight. The most probable solution is a high density and low temperature (HDLT) solution. The CO cell size is approximately 0.01 pc (2000 AU). These cells are thus tiny fragments within the 100 times larger CO-emitting extent of a typical high-latitude cloud. We discuss the physical implications of HDLT cells, and we suggest ways to test for their existence.Comment: 19 pages, 13 figures, 2 tables, emulateapj To be published in The Astrophysical Journa

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)

AST/RO, a 1.7 m diameter telescope for astronomy and aeronomy studies at wavelengths between 200 and 2000 microns, was installed at the South Pole during the 1994-1995 Austral summer. The telescope operates continuously through the Austral winter, and is being used primarily for spectroscopic studies of neutral atomic carbon and carbon monoxide in the interstellar medium of the Milky Way and the Magellanic Clouds. The South Pole environment is unique among observatory sites for unusually low wind speeds, low absolute humidity, and the consistent clarity of the submillimeter sky. Four heterodyne receivers, an array receiver, three acousto-optical spectrometers, and an array spectrometer are installed. A Fabry-Perot spectrometer using a bolometric array and a Terahertz receiver are in development. Telescope pointing, focus, and calibration methods as well as the unique working environment and logistical requirements of the South Pole are described.Comment: 57 pages, 15 figures. Submitted to PAS

Gas Density, Stability, and Starbursts Near the Inner Lindblad Resonance of the Milky Way

A key project of the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) reported by Martin et al. (2004) is the mapping of CO J=4-3 and J=7-6 emission from the inner Milky Way, allowing determination of gas density and temperature. Galactic center gas that Binney et al. (1991) identify as being on x_2 orbits has a density near 10^3.5 cm ^-3, which renders it only marginally stable against gravitational coagulation into a few Giant Molecular Clouds, as discussed by Elmegreen (1994). This suggests a relaxation oscillator mechanism for starbursts in the Milky Way, where inflowing gas accumulates in a ring at 150 pc radius for approximately 20 million years, until the critical density is reached, and the resulting instability leads to the sudden formation of giant clouds and the deposition of 4 x 10^7 solar masses of gas onto the Galactic center.Comment: 11 pages, 1 table 1 color figure, submitted to ApJ

The AST/RO Survey of the Galactic Center Region. I. The Inner 3 Degrees

We present fully-sampled maps of 461 GHz CO (4-3), 807 GHz CO (7-6), and 492 GHz [CI] (3P1-3P0) emission from the inner 3 degrees of the Galactic Center region taken with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) in 2001--2002. The data cover -1.3 < l < 2, -0.3 < b < 0.2 with 0.5 arcmin spacing, resulting in spectra in 3 transitions at over 24,000 positions on the sky. The CO (4-3) emission is found to be essentially coextensive with lower-J transitions of CO. The CO (7-6) emission is spatially confined to a far smaller region than the lower-J CO lines. The [CI] (3P1-3P0) emission has a spatial extent similar to the low-J CO emission, but is more diffuse. Bright CO (7-6) emission is detected in the well-known Galactic Center clouds Sgr A and Sgr B. We also detect CO (4-3) and CO (7-6) absorption from spiral arms in the galactic disk at velocities near 0 km s^-1 along the line of sight to the Galactic Center. Analyzing our CO (7-6) and CO (4-3) data in conjunction with J = 1 - 0 12CO and 13CO data previously observed with the Bell Laboratories 7-m antenna, we apply a Large Velocity Gradient (LVG) model to estimate the kinetic temperature and density of molecular gas in the inner 200 pc of the Galactic Center region. We show maps of the derived distribution of gas density and kinetic temperature as a function of position and velocity for the entire region. Kinetic temperature was found to decrease from relatively high values (>70K) at cloud edges to low values (<50K) in the interiors. Typical gas pressures in the Galactic Center gas are n(H_2) T_kin approx 10^5.2 K cm^-3. We also present an (l,b) map of molecular hydrogen column density derived from our LVG results.Comment: 41 pages, 29 figures reduced to low resolution for astro-ph, for high resolution figures please go to http://cfa-www.harvard.edu/ASTRO/galcen_1.pdf this version incorporates changes due to accepted erratum (to appear in ApJS 153

Training of Instrumentalists and Development of New Technologies on SOFIA

This white paper is submitted to the Astronomy and Astrophysics 2010 Decadal Survey (Astro2010)1 Committee on the State of the Profession to emphasize the potential of the Stratospheric Observatory for Infrared Astronomy (SOFIA) to contribute to the training of instrumentalists and observers, and to related technology developments. This potential goes beyond the primary mission of SOFIA, which is to carry out unique, high priority astronomical research. SOFIA is a Boeing 747SP aircraft with a 2.5 meter telescope. It will enable astronomical observations anywhere, any time, and at most wavelengths between 0.3 microns and 1.6 mm not accessible from ground-based observatories. These attributes, accruing from the mobility and flight altitude of SOFIA, guarantee a wealth of scientific return. Its instrument teams (nine in the first generation) and guest investigators will do suborbital astronomy in a shirt-sleeve environment. The project will invest $10M per year in science instrument development over a lifetime of 20 years. This, frequent flight opportunities, and operation that enables rapid changes of science instruments and hands-on in-flight access to the instruments, assure a unique and extensive potential - both for training young instrumentalists and for encouraging and deploying nascent technologies. Novel instruments covering optical, infrared, and submillimeter bands can be developed for and tested on SOFIA by their developers (including apprentices) for their own observations and for those of guest observers, to validate technologies and maximize observational effectiveness.Comment: 10 pages, no figures, White Paper for Astro 2010 Survey Committee on State of the Professio

Large Scale CO and [CI] emission in the rho Ophiuchi Molecular Cloud

We present a comprehensive study of the rho Ophiuchi molecular cloud that addresses aspects of the physical structure and condition of the molecular cloud and its photodissociation region (PDR) by combining far-infrared and submillimeter-wave observations with a wide range of angular scale and resolution. We present 40'x40' maps in CO(4-3) and [CI](3P1-3P0) line emission from the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO), and pointed observations in the CO(7-6) and [CI](3P2-3P1) lines. Within, smaller spectral line maps of the cloud in CO, CS, HCO+ and their rare isotopomers are made at the Heinrich Hertz Submillimeter Telescope Observatory (HHT) in Arizona. Comparison with far-infrared and submillimeter continuum emission, and near-infrared H2 emission allows clearer determination of the physical and chemical structure of the rho Oph photodissociation region (PDR). The excitation conditions needed to produce the observed HCO+ and [OI] emission directly imply inhomogeneous structure. Strong chemical gradients are observed in HCO+ and CS; the former is ascribed to a local enhancement in the H2 ionization rate, the latter is principally due to shocks. The distribution of [CI] is very similar to C18O, and generally consistent with illumination from the 'far' side of the cloud. A notable exception is found at the the western edge of the cloud, where UV photons create a PDR viewed `edge-on'. The abundance of atomic carbon is accurately modeled using a radiation field that decreases with increasing projected distance from the exciting star HD147889. In contrast to conclusions of other studies, we find that no non-equilibrium chemistry is needed to enhance the atomic carbon abundance.Comment: 17 pages, 21 figures. To be published in the Astrophysical Journal. High resolution color version (PS, PDF formats) available at http://loke.as.arizona.edu/~ckulesa/research/publications/rhooph