Combined determination of highly sensitive troponin T and copeptin for early exclusion of acute myocardial infarction: first experience in an emergency department of a general hospital

Ulrich Lotze1, Holger Lemm2, Anke Heyer2, Karin Müller31Department of Internal Medicine, German Red Cross Hospital Sondershausen, Sondershausen, 2Department of Internal Medicine, 3Department of Laboratory Medicine, Saale-Unstrut Hospital Naumburg, Naumburg, GermanyBackground: The purpose of this observational study was to test the diagnostic performance of the Elecsys® troponin T high-sensitive system combined with copeptin measurement for early exclusion of acute myocardial infarction (MI) in clinical practice.Methods: Troponin T high-sensitive (diagnostic cutoff: <14 pg/mL) and copeptin (diagnostic cutoff: <14 pmol/L) levels were determined at admission in addition to other routine laboratory parameters in patients with suspected acute MI presenting to the emergency department of a general hospital over a period of five months.Results: Data from 142 consecutive patients (mean age 71.2 ± 13.5 years, 76 men) were analyzed. Final diagnoses were acute MI in 13 patients (nine ST elevation MI, four non-ST elevation MI, 9.2%) unstable angina pectoris in three (2.1%), cardiac symptoms not primarily associated with myocardial ischemia in 79 (55.6%), and noncardiac disease in 47 patients (33.1%). The patients with acute MI were younger and had higher troponin T high-sensitive and copeptin values than patients without acute MI. Seventeen patients had very high copeptin values (>150 pmol/L), one of whom had a level of >700 pmol/L and died of pulmonary embolism. A troponin T high-sensitive level of <14 pg/mL in combination with copeptin <14 pmol/L at initial presentation ruled out acute MI in 45 of the 142 patients (31.7%), each with a sensitivity and negative predictive value of 100%.Conclusion: According to this early experience, a single determination of troponin T high-sensitive and copeptin may enable early and accurate exclusion of acute MI in one third of patients, even in an emergency department of a general hospital.Keywords: highly sensitive troponin T, copeptin, acute myocardial infarction, exclusio

Caste, Kinship, and Life Course: Rethinking Women's Work and Agency in Rural South India

This paper reexamines the linkages between women's work, agency, and well-being based on a household survey and in-depth interviews conducted in rural Tamil Nadu in 2009 and questions the prioritization of workforce participation as a path to gender equality. It emphasizes the need to unpack the nature of work performed by and available to women and its social valuation, as well as women's agency, particularly its implications for decision making around financial and nonfinancial household resources in contexts of socioeconomic change. The effects of work participation on agency are mediated by factors like age and stage in the life cycle, reproductive success, and social location – especially of caste – from which women enter the workforce

The Scale Dependence of the Molecular Gas Depletion Time in M33

We study the Local Group spiral galaxy M33 to investigate how the observed scaling between the (kpc-averaged) surface density of molecular gas (\Sigma_H2) and recent star formation rate (\Sigma_SFR) relates to individual star-forming regions. To do this, we measure the ratio of CO emission to extinction-corrected Halpha emission in apertures of varying sizes centered both on peaks of CO and Halpha emission. We parameterize this ratio as a molecular gas (H_2) depletion time (\tau_dep). On large (kpc) scales, our results are consistent with a molecular star formation law (Sigma_SFR \sim Sigma_H2^b) with b \sim 1.1 - 1.5 and a median \tau_dep \sim 1 Gyr, with no dependence on type of region targeted. Below these scales, \tau_dep is a strong function of adopted angular scale and the type of region that is targeted. Small (\lesssim 300pc) apertures centered on CO peaks have very long \tau_dep (i.e., high CO-to-Halpha flux ratio) and small apertures targeted toward Halpha peaks have very short \tau_dep. This implies that the star formation law observed on kpc scales breaks down once one reaches aperture sizes of \lesssim 300pc. For our smallest apertures (75pc), the difference in \tau_dep between the two types of regions is more than one order of magnitude. This scale behavior emerges from averaging over star-forming regions with a wide range of CO-to-Halpha ratios with the natural consequence that the breakdown in the star formation law is a function of the surface density of the regions studied. We consider the evolution of individual regions the most likely driver for region-to-region differences in \tau_dep (and thus the CO-to-Halpha ratio).Comment: Accepted for publication in the Astrophysical Journal, 9 pages, 5 figure

The CO-to-H2 Conversion Factor From Infrared Dust Emission Across the Local Group

We estimate the conversion factor relating CO emission to H2 mass, alpha_CO, in five Local Group galaxies that span approximately an order of magnitude in metallicity - M31, M 33, the Large Magellanic Cloud (LMC), NGC 6822, and the Small Magellanic Cloud (SMC). We model the dust mass along the line of sight from infrared (IR) emission and then solve for the alpha_CO that best allows a single gas-to-dust ratio (delta_GDR) to describe each system. This approach remains sensitive to CO-dark envelopes of H2 surrounding molecular clouds. In M 31, M 33, and the LMC we find alpha_CO \approx 3-9 M_sun pc^-2 (K km s^-1)^-1, consistent with the Milky Way value within the uncertainties. The two lowest metallicity galaxies in our sample, NGC 6822 and the SMC (12 + log(O/H) \approx 8.2 and 8.0), exhibit a much higher alpha_CO. Our best estimates are \alpha_NGC6822 \approx 30 M_sun/pc^-2 (K km s^-1)^-1 and \alpha_SMC \approx 70 M_sun/pc^-2 (K km s-1)-1. These results are consistent with the conversion factor becoming CO a strong function of metallicity around 12 + log(O/H) \sim 8.4 - 8.2. We favor an interpretation where decreased dust-shielding leads to the dominance of CO-free envelopes around molecular clouds below this metallicity.Comment: Accepted for publication in the Astrophysical Journal, 15 pages, 7 figure

Low CO Luminosities in Dwarf Galaxies

[Abridged] We present maps of CO 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13 arcsec angular resolution, ~250 pc at our average distance of 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarfs outside the Local Group ranging from single lines-of-sight, stacked over IR-bright regions of embedded star formation, and stacked over the entire galaxy. We detect 5 dwarfs in CO with total luminosities of L_CO = 3-28 1e6 Kkmspc2. The other 11 dwarfs remain undetected in CO even in the stacked data and have L_CO < 0.4-8 1e6 Kkmspc2. We combine our sample of dwarfs with a large literature sample of spirals to study scaling relations of L_CO with M_B and metallicity. We find that dwarfs with metallicities of Z ~ 1/2-1/10 Z_sun have L_CO about 1e2-1e4x smaller than spirals and that their L_CO per unit L_B is 10-100x smaller. A comparison with tracers of star formation (FUV and 24 micron) shows that L_CO per unit SFR is 10-100x smaller in dwarfs. One possible interpretation is that dwarfs form stars much more efficiently, however we argue that the low L_CO/SFR ratio is due to significant changes of the CO-to-H2 conversion factor, alpha_CO, in low metallicity environments. Assuming a constant H2 depletion time of 1.8 Gyr (as found for nearby spirals) implies alpha_CO values for dwarfs with Z ~ 1/2-1/10 Z_sun that are more than 10x higher than those found in solar metallicity spirals. This significant increase of alpha_CO at low metallicity is consistent with previous studies, in particular those which model dust emission to constrain H2 masses. Even though it is difficult to parameterize the metallicity dependence of alpha_CO, our results suggest that CO is increasingly difficult to detect at lower metallicities.Comment: Accepted for publication in the Astronomical Journal, 19 pages, 7 figure

Molecular Gas and Star Formation in Nearby Disk Galaxies

We compare molecular gas traced by ^(12)CO (2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order linear correspondence between Σ_(mol) and Σ_(SFR) but also find important second-order systematic variations in the apparent molecular gas depletion time, τ_(dep)^(mol) = ∑_(mol)/∑_(SFR). At the 1 kpc common resolution of HERACLES, CO emission correlates closely with many tracers of the recent SFR. Weighting each line of sight equally, using a fixed α_(CO) equivalent to the Milky Way value, our data yield a molecular gas depletion time, τ_(dep)^(mol)= ∑_(mol)∑_(SFR) ≈ 2.2 Gyr with 0.3 dex 1σ scatter, in very good agreement with recent literature data. We apply a forward-modeling approach to constrain the power-law index, N, that relates the SFR surface density and the molecular gas surface density, ∑_(SFR) ∝ ∑_(mol)^N. We find N = 1 ± 0.15 for our full data set with some scatter from galaxy to galaxy. This also agrees with recent work, but we caution that a power-law treatment oversimplifies the topic given that we observe correlations between τ_(dep)^(mol) and other local and global quantities. The strongest of these are a decreased τ_(dep)^(mol) in low-mass, low-metallicity galaxies and a correlation of the kpc-scale τ_(dep)^(mol) with dust-to-gas ratio, D/G. These correlations can be explained by a CO-to-H_2 conversion factor (α_(CO)) that depends on dust shielding, and thus D/G, in the theoretically expected way. This is not a unique interpretation, but external evidence of conversion factor variations makes this the most conservative explanation of the strongest observed τ_(dep)^(mol) trends. After applying a D/G-dependent α_(CO), some weak correlations between τ_(dep)^(mol) and local conditions persist. In particular, we observe lower τ_(dep)^(mol) and enhanced CO excitation associated with nuclear gas concentrations in a subset of our targets. These appear to reflect real enhancements in the rate of star formation per unit gas, and although the distribution of τ_(dep) does not appear bimodal in galaxy centers, τ_(dep) does appear multivalued at fixed Σ_(H2), supporting the idea of "disk" and "starburst" modes driven by other environmental parameters

Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-Forming Galaxies

Date of Acceptance: 15/05/2015We present a new survey of HCN(1-0) emission, a tracer of dense molecular gas, focused on the little-explored regime of normal star-forming galaxy disks. Combining HCN, CO, and infrared (IR) emission, we investigate the role of dense gas in Star Formation (SF), finding systematic variations in both the apparent dense gas fraction and the apparent SF efficiency (SFE) of dense gas. The latter may be unexpected, given the popularity of gas density threshold models to explain SF scaling relations. We used the IRAM 30-m telescope to observe HCN(1-0) across 29 nearby disk galaxies whose CO(2-1) emission has previously been mapped by the HERACLES survey. Because our observations span a range of galactocentric radii, we are able to investigate the properties of the dense gas as a function of local conditions. We focus on how the IR/CO, HCN/CO, and IR/HCN ratios (observational cognates of the SFE, dense gas fraction, and dense gas SFE) depend on the stellar surface density and the molecular/atomic ratio. The HCN/CO ratio correlates tightly with these two parameters across a range of 2.1 dex and increases in the high surface density parts of galaxies. Simultaneously, the IR/HCN ratio decreases systematically with these same parameters and is ~6-8 times lower near galaxy centers than in the outer regions. For fixed line-mass conversion factors, these results are incompatible with a simple model in which SF depends only on the gas mass above some density threshold. Only a specific set of environment-dependent conversion factors can render our observations compatible with such a model. Whole cloud models, such as the theory of turbulence regulated SF, do a better job of matching our data. We explore one such model in which variations in the Mach number and in the mean density would respectively drive the trends within galaxy disks and the differences between disk and merging galaxies (abridged).Peer reviewe

Evaluating the potential of ecological niche modelling as a component in marine non-indigenous species risk assessments

Marine biological invasions have increased with the development of global trading, causing the homogenization of communities and the decline of biodiversity. A main vector is ballast water exchange from shipping. This study evaluates the use of ecological niche modelling (ENM) to predict the spread of 18 non-indigenous species (NIS) along shipping routes and their potential habitat suitability (hot/cold spots) in the Baltic Sea and Northeast Atlantic. Results show that, contrary to current risk assessment methods, temperature and sea ice concentration determine habitat suitability for 61% of species, rather than salinity (11%). We show high habitat suitability for NIS in the Skagerrak and Kattegat, a transitional area for NIS entering or leaving the Baltic Sea. As many cases of NIS introduction in the marine environment are associated with shipping pathways, we explore how ENM can be used to provide valuable information on the potential spread of NIS for ballast water risk assessment