Great Salt Lake Halophilic Archaea as a Model For Possible Extant Life on Mars

Expansive evaporite mineral deposits and other geological features on Mars are evidence of ancient lacustrine systems before the planet experienced global climatic change (~3.5 Ga). On Mars, as the surface water dried up, hypersaline lakes would have filled the ancient lake basins. On Earth, the Bonneville Basin, in the western United States, tells a similar story in a more recent timeframe. Today, the bottom of this basin is the modern Great Salt Lake (GSL) and the Bonneville Salt Flats. Evaporation of this freshwater lake left large evaporitic mineral deposits that continually supply salt to modern GSL. Parts of the lake are at salt saturation due to shrinking shorelines and human intervention, and it is here that haloarchaea thrive. The current Martian ultraviolet flux, magnetosphere, lack of tectonic activity, and desiccation suggests that continued life would be challenging. However, microorganisms such as GSL haloarchaea may resist these extreme conditions, especially if entombed in minerals. We propose GSL haloarchaea as excellent analogues for life that could have been in hypersaline lakes on Mars and may remain preserved in the evaporitic minerals there

The Mass Inflow Rate in the Barred Galaxy NGC 1530

Mass inflow in barred galaxies has been invoked to account for a wide variety of phenomena, but until now direct evidence for inflow has been lacking. We present Fabry-Perot H-alpha observations of the barred spiral galaxy NGC 1530 from which we determine velocities of the ionized gas for the entire region swept by the bar. We compare the velocity field to models of gas flow in barred spirals and show that it is well reproduced by ideal gas hydrodynamic models. Inspection of the models and observations reveals that gas entering the bar dust lanes streams directly down the dust lanes toward the 2 kpc radius nuclear ring. The models predict that approximately 20% of the gas flowing down the dust lane enters the nuclear ring; the remaining gas sprays around the ring to the other bar dust lane. The fraction of the gas entering the ring is relatively insensitive to the shape or size of the bar. Our observations of the velocity field and dust optical depth yield a mass inflow rate into the nuclear ring of 1 solar mass per year.Comment: 13 pages, 3 figures, aastex 4.0, accepted for publication in Ap J Letter

Risk factors for COPD exacerbations in inhaled medication users: the COPDGene study biannual longitudinal follow-up prospective cohort.

BackgroundDespite inhaled medications that decrease exacerbation risk, some COPD patients experience frequent exacerbations. We determined prospective risk factors for exacerbations among subjects in the COPDGene Study taking inhaled medications.Methods2113 COPD subjects were categorized into four medication use patterns: triple therapy with tiotropium (TIO) plus long-acting beta-agonist/inhaled-corticosteroid (ICS ± LABA), tiotropium alone, ICS ± LABA, and short-acting bronchodilators. Self-reported exacerbations were recorded in telephone and web-based longitudinal follow-up surveys. Associations with exacerbations were determined within each medication group using four separate logistic regression models. A head-to-head analysis compared exacerbation risk among subjects using tiotropium vs. ICS ± LABA.ResultsIn separate logistic regression models, the presence of gastroesophageal reflux, female gender, and higher scores on the St. George's Respiratory Questionnaire were significant predictors of exacerbator status within multiple medication groups (reflux: OR 1.62-2.75; female gender: OR 1.53 - OR 1.90; SGRQ: OR 1.02-1.03). Subjects taking either ICS ± LABA or tiotropium had similar baseline characteristics, allowing comparison between these two groups. In the head-to-head comparison, tiotropium users showed a trend towards lower rates of exacerbations (OR = 0.69 [95 % CI 0.45, 1.06], p = 0.09) compared with ICS ± LABA users, especially in subjects without comorbid asthma (OR = 0.56 [95% CI 0.31, 1.00], p = 0.05).ConclusionsEach common COPD medication usage group showed unique risk factor patterns associated with increased risk of exacerbations, which may help clinicians identify subjects at risk. Compared to similar subjects using ICS ± LABA, those taking tiotropium showed a trend towards reduced exacerbation risk, especially in subjects without asthma.Trial registrationClinicalTrials.gov NCT00608764, first received 1/28/2008

Inner Molecular Rings in Barred Galaxies: BIMA SONG CO Observations

Although inner star-forming rings are common in optical images of barred spiral galaxies, observational evidence for the accompanying molecular gas has been scarce. In this paper we present images of molecular inner rings, traced using the CO (1-0) emission line, from the Berkeley-Illinois-Maryland-Association Survey of Nearby Galaxies (BIMA SONG). We detect inner ring CO emission from all five SONG barred galaxies classified as inner ring (type (r)). We also examine the seven SONG barred galaxies classified as inner spiral (type (s)); in one of these, NGC 3627, we find morphological and kinematic evidence for a molecular inner ring. Inner ring galaxies have been classified as such based on optical images, which emphasize recent star formation. We consider the possibility that there may exist inner rings in which star formation efficiency is not enhanced. However, we find that in NGC 3627 the inner ring star formation efficiency is enhanced relative to most other regions in that galaxy. We note that the SONG (r) galaxies have a paucity of CO and H alpha emission interior to the inner ring (except near the nucleus), while NGC 3627 has relatively bright bar CO and H alpha emission; we suggest that galaxies with inner rings such as NGC 3627 may be misclassified if there are significant amounts of gas and star formation in the bar.Comment: To be published in the Astrophysical Journal, July 2002 A version of the paper with full resolution figures is available at: http://www.astro.umd.edu/~mregan/ms.ps.g

Using Hubble Space Telescope Imaging of Nuclear Dust Morphology to Rule Out Bars Fueling Seyfert Nuclei

If AGN are powered by the accretion of matter onto massive black holes, how does the gas in the host galaxy lose the required angular momentum to approach the black hole? Gas easily transfers angular momentum to stars in strong bars, making them likely candidates. Although ground-based searches for bars in active galaxies using both optical and near infrared surface brightness have not found any excess of bars relative to quiescent galaxies, the searches have not been able to rule out small-scale nuclear bars. To look for these nuclear bars we use HST WFPC2-NICMOS color maps to search for the straight dust lane signature of strong bars. Of the twelve Seyfert galaxies in our sample, only three have dust lanes consistent with a strong nuclear bar. Therefore, strong nuclear bars cannot be the primary fueling mechanism for Seyfert nuclei. We do find that a majority of the galaxies show an spiral morphology in their dust lanes. These spiral arms may be a possible fueling mechanism.Comment: To be published in the Astronomical Journal, June 1999. 25 pages and 14 figures. Full resolution figures are available at ftp://www.ciw.edu/pub/mregan/fullfigs.tar.g

Epidemiology, genetics, and subtyping of preserved ratio impaired spirometry (PRISm) in COPDGene.

BackgroundPreserved Ratio Impaired Spirometry (PRISm), defined as a reduced FEV1 in the setting of a preserved FEV1/FVC ratio, is highly prevalent and is associated with increased respiratory symptoms, systemic inflammation, and mortality. Studies investigating quantitative chest tomographic features, genetic associations, and subtypes in PRISm subjects have not been reported.MethodsData from current and former smokers enrolled in COPDGene (n = 10,192), an observational, cross-sectional study which recruited subjects aged 45-80 with ≥10 pack years of smoking, were analyzed. To identify epidemiological and radiographic predictors of PRISm, we performed univariate and multivariate analyses comparing PRISm subjects both to control subjects with normal spirometry and to subjects with COPD. To investigate common genetic predictors of PRISm, we performed a genome-wide association study (GWAS). To explore potential subgroups within PRISm, we performed unsupervised k-means clustering.ResultsThe prevalence of PRISm in COPDGene is 12.3%. Increased dyspnea, reduced 6-minute walk distance, increased percent emphysema and decreased total lung capacity, as well as increased segmental bronchial wall area percentage were significant predictors (p-value <0.05) of PRISm status when compared to control subjects in multivariate models. Although no common genetic variants were identified on GWAS testing, a significant association with Klinefelter's syndrome (47XXY) was observed (p-value < 0.001). Subgroups identified through k-means clustering include a putative "COPD-subtype", "Restrictive-subtype", and a highly symptomatic "Metabolic-subtype".ConclusionsPRISm subjects are clinically and genetically heterogeneous. Future investigations into the pathophysiological mechanisms behind and potential treatment options for subgroups within PRISm are warranted.Trial registrationClinicaltrials.gov Identifier: NCT000608764

Barred Galaxies at z > 0.7: NICMOS HDFN Observations

Previous optical studies found an unexpected deficit of bars at z > 0.7. To investigate the effects of bandshifting, we have studied the fraction of barred spirals in the NICMOS Deep Field North. At z > 0.7 we find at least four barred spirals, doubling the number previously detected. The number of barred galaxies is small because these (and previous) data lack adequate spatial resolution. A typical 5 kpc bar at z > 0.7 is only marginally detectable for WFPC2 at 0.8microns; the NICMOS data have even lower resolution and can only find the largest bars. The average size of the four bars seen at z > 0.7 is 12 kpc. The fraction of such large bars (4/95) is higher than that seen in nearby spirals (1/44); all known selection effects suggest that the observed fraction is a lower limit. However, important caveats such as small numbers and difficulties in defining comparable samples at high and low redshifts should be noted. We conclude that there is no significant evidence for a decrease in the fraction of barred spirals beyond z ~ 0.7.Comment: Accepted for publication in ApJ Letters, 4 pages in emulate-apj style, includes 3 figure