Abstract
We present Atacama Large Millimeter Array C i(1 − 0) (rest frequency 492 GHz) observations for a sample of 13 strongly lensed dusty star-forming galaxies (DSFGs) originally discovered at ...1.4 mm in a blank-field survey by the South Pole Telescope (SPT). We compare these new data with available C i observations from the literature, allowing a study of the interstellar medium (ISM) properties of ∼30 extreme DSFGs spanning a redshift range 2 < z < 5. Using the C i line as a tracer of the molecular ISM, we find a mean molecular gas mass for SPT-DSFGs of 6.6 × 1010 M⊙. This is in tension with gas masses derived via low-J
12CO and dust masses; bringing the estimates into accordance requires either (a) an elevated CO-to-H2 conversion factor for our sample of αCO ∼ 2.5 and a gas-to-dust ratio ∼200, or (b) an high carbon abundance
$X_{\rm C\,\small {I}} \sim 7\times 10^{-5}$
. Using observations of a range of additional atomic and molecular lines (including C i, C iiand multiple transitions of CO), we use a modern photodissociation region code (3d-pdr) to assess the physical conditions (including the density, UV radiation field strength and gas temperature) within the ISM of the DSFGs in our sample. We find that the ISM within our DSFGs is characterized by dense gas permeated by strong UV fields. We note that previous efforts to characterize photodissociation region regions in DSFGs may have significantly under-estimated the density of the ISM. Combined, our analysis suggests that the ISM of extreme dusty starbursts at high redshift consists of dense, carbon-rich gas not directly comparable to the ISM of starbursts in the local Universe.
Even though large extents of boreal peatlands are still in a pristine condition, especially in North America, extensive areas have been affected by natural or anthropogenic disturbances that change ...some of the systems from being sinks to sources of carbon dioxide and shift the methane production/consumption patterns through alterations of both above- and below-ground communities and functions. In order to fully assess the role of peatlands on global C balance, now and in the future, it is imperative that we deepen our understanding of the relative contributions of various groups of microorganisms to organic matter transformations. Here, we review the drivers structuring fungal, bacterial and archaeal communities in natural peatlands and the response of these microbial communities to natural and anthropogenic disturbances, including fire, drainage, nutrient deposition, peat mining and climate change. The microbial diversity in peatlands is characterized by organisms that have developed physiological and metabolic adaptations to cope with the constraining conditions found in these ecosystems, such as low oxygen availability, cold temperature, acidity and oligotrophy. Furthermore, these unique organisms sometimes appear to be organized as repeat mosaics responding to vegetation, physico-chemical and hydrological characteristics more than to geographical distance, in other words, similar to the much valued biodiversity aspects of the peatland vegetation itself and associated higher organisms. The response of microbial communities to disturbances is far from fully understood. In particular, whilst many studies have identified changes in microbial community composition or on microbially driven processes following a given disturbance, it remains unclear how the two components, diversity and function, relate with each other. Future challenges involve designing studies that will test whether ecological theories like species sorting, stress physiology, temporal niche or functional redundancy can be used to understand what regulates microbial populations and activity in peatlands, and studies that will allow us to predict more accurately how peatlands respond to global change or anthropogenic disturbances.
► Specialized microorganisms add to the much valued biodiversity aspects of peatlands. ► Natural/anthropogenic disturbances alters peatland microbial community structure. ► Species-sorting and functional redundancy are key mechanisms for microbial resilience. ► Synergetic effects of multiple disturbances on microbial diversity deserve attention. ► Clear need to better relate microbial diversity and functions in peatlands.
Background
Postoperative ileus (POI) is characterized by delayed gastrointestinal recovery following surgery. Current knowledge of pathophysiology, clinical interventions and methodological ...challenges was reviewed to inform modern practice and future research.
Methods
A systematic search of MEDLINE and Embase databases was performed using search terms related to ileus and colorectal surgery. All RCTs involving an intervention to prevent or reduce POI published between 1990 and 2016 were identified. Grey literature, non‐full‐text manuscripts, and reanalyses of previous RCTs were excluded. Eligible articles were assessed using the Cochrane tool for assessing risk of bias.
Results
Of 5614 studies screened, 86 eligible articles describing 88 RCTs were identified. Current knowledge of pathophysiology acknowledges neurogenic, inflammatory and pharmacological mechanisms, but much of the evidence arises from animal studies. The most common interventions tested were chewing gum (11 trials) and early enteral feeding (11), which are safe but of unclear benefit for actively reducing POI. Others, including thoracic epidural analgesia (8), systemic lidocaine (8) and peripheral μ antagonists (5), show benefit but require further investigation for safety and cost‐effectiveness.
Conclusion
POI is a common condition with no established definition, aetiology or treatment. According to current literature, minimally invasive surgery, protocol‐driven recovery (including early feeding and opioid avoidance strategies) and measures to avoid major inflammatory events (such as anastomotic leak) offer the best chances of reducing POI.
No easy answers
Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs
. The high-redshift progenitors of ...these galaxy clusters-termed 'protoclusters'-can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter
. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts
. However, recent detections of possible protoclusters hosting such starbursts
do not support the kind of rapid cluster-core formation expected from simulations
: the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.
Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, ...supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.
Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts--that is, increased ...rates of star formation--in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ~5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A 'maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.
Using the Australia Telescope Compact Array, we conducted a survey of CO J = 1 − 0 and J = 2 − 1 line emission towards strongly lensed high-redshift dusty star-forming galaxies (DSFGs) previously ...discovered with the South Pole Telescope (SPT). Our sample comprises 17 sources that had CO-based spectroscopic redshifts obtained with the Atacama Large Millimeter/submillimeter Array and the Atacama Pathfinder Experiment. We detect all sources with known redshifts in either CO J = 1 − 0 or J = 2 − 1. 12 sources are detected in the 7-mm continuum. The derived CO luminosities imply gas masses in the range (0.5–11) × 1010 M⊙ and gas depletion time-scales t
dep < 200 Myr, using a CO to gas mass conversion factor αCO = 0.8 M⊙ (K km s−1 pc2)−1. Combining the CO luminosities and dust masses, along with a fixed gas-to-dust ratio, we derive αCO factors in the range 0.4–1.8 M⊙ (K km s−1 pc2)−1, similar to what is found in other starbursting systems. We find small scatter in αCO values within the sample, even though inherent variations in the spatial distribution of dust and gas in individual cases could bias the dust-based αCO estimates. We find that lensing magnification factors based on the CO linewidth to luminosity relation (μCO) are highly unreliable, but particularly when μ < 5. Finally, comparison of the gas and dynamical masses suggest that the average molecular gas fraction stays relatively constant at z = 2–5 in the SPT DSFG sample.
We present C ii observations of 20 strongly lensed dusty star-forming galaxies at 2.1 < z < 5.7 using Atacama Pathfinder EXperiment and Herschel. The sources were selected on their 1.4 mm flux (S
1.4 ...mm > 20 mJy) from the South Pole Telescope (SPT) survey, with far-infrared (FIR) luminosities determined from extensive photometric data. The C ii line is robustly detected in 17 sources, all but one being spectrally resolved. 11 out of 20 sources observed in C ii also have low-J CO detections from Australia Telescope Compact Array. A comparison with mid- and high-J CO lines from Atacama Large Millimeter/submillimeter Array reveals consistent C ii and CO velocity profiles, suggesting that there is little differential lensing between these species. The C ii, low-J CO and FIR data allow us to constrain the properties of the interstellar medium. We find C ii to CO(1–0) luminosity ratios in the SPT sample of 5200 ± 1800, with significantly less scatter than in other samples. This line ratio can be best described by a medium of C ii and CO emitting gas with a higher C ii than CO excitation temperature, high CO optical depth τCO(1–0) ≫ 1, and low to moderate C ii optical depth
$\tau _{{\rm C\,\small {II}}}$
≲ 1. The geometric structure of photodissociation regions allows for such conditions.
Objective
To estimate the incidence of cystic fibrosis in pregnancy and to explore obstetric and neonatal outcomes.
Design
A population‐based descriptive study using the methodology of the UK ...Obstetric Surveillance System (UKOSS).
Setting
All consultant‐led maternity units in the UK.
Population
All pregnant women with a diagnosis of cystic fibrosis who booked for antenatal care in a UK obstetric unit between March 2015 and February 2017.
Methods
Prospective case collection identified using UKOSS monthly notification.
Main outcome measures
Incidence, maternal morbidity, maternal mortality, gestation at delivery, neonatal mortality, neonatal morbidity.
Results
We report 71 pregnancies over a 2‐year period. There was one early miscarriage, four terminations and three sets of twins, resulting in the live birth of 69 infants. There were no maternal deaths. One infant died following spontaneous preterm birth at 29 weeks’ gestation. The mean gestation at delivery was 36.2 completed weeks. The mean birthweight centile for gestational age was the 61st centile. We report a positive correlation between both maternal lung function (FEV1) and mean gestation at delivery, and between FEV1 and mean birthweight centile for gestational age.
Conclusions
Pregnancy outcomes are generally good in women with cystic fibrosis. Successful pregnancy is possible even in those women with FEV1 <60% predicted, although such women have higher chance of preterm delivery and a smaller baby.
Tweetable
Pregnant women with cystic fibrosis who have poorer lung function at the beginning of pregnancy have a higher risk of having a premature or smaller baby.
Tweetable
Pregnant women with cystic fibrosis who have poorer lung function at the beginning of pregnancy have a higher risk of having a premature or smaller baby.
This article includes Author Insights, a video available at https://vimeo.com/rcog/authorinsights16423
ABSTRACT The South Pole Telescope has discovered 100 gravitationally lensed, high-redshift, dusty, star-forming galaxies (DSFGs). We present 0 5 resolution 870 Atacama Large Millimeter/submillimeter ...Array imaging of a sample of 47 DSFGs spanning , and construct gravitational lens models of these sources. Our visibility-based lens modeling incorporates several sources of residual interferometric calibration uncertainty, allowing us to properly account for noise in the observations. At least 70% of the sources are strongly lensed by foreground galaxies ( ), with a median magnification of , extending to . We compare the intrinsic size distribution of the strongly lensed sources to a similar number of unlensed DSFGs and find no significant differences in spite of a bias between the magnification and intrinsic source size. This may indicate that the true size distribution of DSFGs is relatively narrow. We use the source sizes to constrain the wavelength at which the dust optical depth is unity and find this wavelength to be correlated with the dust temperature. This correlation leads to discrepancies in dust mass estimates of a factor of two compared to estimates using a single value for this wavelength. We investigate the relationship between the C ii line and the far-infrared luminosity and find that the same correlation between the C ii/ ratio and found for low-redshift star-forming galaxies applies to high-redshift galaxies and extends at least two orders of magnitude higher in . This lends further credence to the claim that the compactness of the IR-emitting region is the controlling parameter in establishing the "C ii deficit."
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