Near-Infrared Spectroscopy of 0.4<z<1.0 CFRS Galaxies: Oxygen Abundances, SFRs and Dust

Using new J-band VLT-ISAAC and Keck-NIRSPEC spectroscopy, we have measured Halpha and [NII] line fluxes for 0.47<z<0.92 CFRS galaxies which have [OII], Hbeta and [OIII]a line fluxes available from optical spectroscopy, to investigate how the properties of the star forming gas in galaxies evolve with redshift. We derive the extinction and oxygen abundances for the sample using a method based on a set of ionisation parameter and oxygen abundance diagnostics, simultaneously fitting the [OII], Hbeta,[OIII], Halpha, and [NII] line fluxes. The individual reddening measurements allow us to accurately correct the Halpha-based star formation rate (SFR) estimates for extinction. Our most salient conclusions are: a) in all 30 CFRS galaxies the source of gas ionisation is not due to AGN activity; b) we find a range of 0<AV<3, suggesting that it is important to determine the extinction for every single galaxy in order to reliably measure SFRs and oxygen abundances in high redshift galaxies; c) high values of [NII]/Halpha >0.1 for most (but not all) of the CFRS galaxies indicate that they lie on the high-metallicity branch of the R23 calibration; d) about one third of the 0.47<z<0.92 CFRS galaxies in our sample have lower metallicities than local galaxies with similar luminosities and star formation rates; e) comparison with a chemical evolution model indicates that these low metallicity galaxies are unlikely to be the progenitors of metal-poor dwarf galaxies at z~0.Comment: Accepted for publication in the Astrophysical Journa

Physical Conditions of Accreting Gas in T Tauri Star Systems

We present results from a low resolution (R~300) near-infrared spectroscopic variability survey of actively accreting T Tauri stars (TTS) in the Taurus-Auriga star forming region. Paschen and Brackett series H I recombination lines were detected in 73 spectra of 15 classical T Tauri systems. The values of the Pan/PaB, Brn/BrG, and BrG/Pan H I line ratios for all observations exhibit a scatter of < 20% about the weighted mean, not only from source to source, but also for epoch-to-epoch variations in the same source. A representative or `global' value was determined for each ratio in both the Paschen and Brackett series as well as the BrG/Pan line ratios. A comparison of observed line ratio values was made to those predicted by the temperature and electron density dependent models of Case B hydrogen recombination line theory. The measured line ratios are statistically well-fit by a tightly constrained range of temperatures (T < 2000 K) and electron densities 1e9 < n_e < 1e10 cm^-3. A comparison of the observed line ratio values to the values predicted by the optically thick and thin local thermodynamic equilibrium cases rules out these conditions for the emitting H I gas. Therefore, the emission is consistent with having an origin in a non-LTE recombining gas. While the range of electron densities is consistent with the gas densities predicted by existing magnetospheric accretion models, the temperature range constrained by the Case B comparison is considerably lower than that expected for accreting gas. The cooler gas temperatures will require a non-thermal excitation process (e.g., coronal/accretion-related X-rays and UV photons) to power the observed line emission.Comment: 12 pages, emulateapj format, Accepted for publication in Ap

Temperature Fluctuations and Abundances in HII Galaxies

There is evidence for temperature fluctuations in Planetary Nebulae and in Galactic HII regions. If such fluctuations occur in the low-metallicity, extragalactic HII regions used to probe the primordial helium abundance, the derived 4He mass fraction, Y_P, could be systematically different from the true primordial value. For cooler, mainly high-metallicity HII regions the derived helium abundance may be nearly unchanged but the oxygen abundance could have been seriously underestimated. For hotter, mainly low-metallicity HII regions the oxygen abundance is likely accurate but the helium abundance could be underestimated. The net effect is to tilt the Y vs. Z relation, making it flatter and resulting in a higher inferred Y_P. Although this effect could be large, there are no data which allow us to estimate the size of the temperature fluctuations for the extragalactic HII regions. Therefore, we have explored this effect via Monte Carlos in which the abundances derived from a fiducial data set are modified by \Delta-T chosen from a distribution with 0 < \Delta-T < \Delta-T_max where \Delta-T_max is varied from 500K to 4000K. It is interesting that although this effect shifts the locations of the HII regions in Y vs. O/H plane, it does not introduce any significant additional dispersion.Comment: 11 pages, 9 postscript figures; submitted to the Ap

The BRACELET Study: surveys of mortality in UK neonatal and paediatric intensive care trials.

BACKGROUND: The subject of death and bereavement in the context of randomised controlled trials in neonatal or paediatric intensive care is under-researched. The objectives of this phase of the Bereavement and RAndomised ControlLEd Trials (BRACELET) Study were to determine trial activity in UK neonatal and paediatric intensive care (2002-06); numbers of deaths before hospital discharge; and variation in mortality across intensive care units and trials and to determine whether bereavement support policies were available within trials. These are essential prerequisites to considering the implications of future policies and practice subsequent to bereavement following a child's enrollment in a trial. METHODS: The units survey involved neonatal units providing level 2 or 3 care, and paediatric units providing level II care or above; the trials survey involved trials where allocation was randomized and interventions were delivered to intensive care patients, or to parents but designed to affect patient outcomes. RESULTS: Information was available from 191/220 (87%) neonatal units (149 level 2 or 3 care); and 28/32 (88%) paediatric units. 90/177 (51%) eligible responding units participated in one or more trial (76 neonatal, 14 paediatric) and 54 neonatal units and 6 paediatric units witnessed at least one death. 50 trials were identified (36 neonatal, 14 paediatric). 3,137 babies were enrolled in neonatal trials, 210 children in paediatric trials. Deaths ranged 0-278 (median [IQR interquartile range] 2 [1, 14.5]) per neonatal trial, 0-4 (median [IQR] 1 [0, 2.5]) per paediatric trial. 534 (16%) participants died post-enrollment: 522 (17%) in neonatal trials, 12 (6%) in paediatric trials. Trial participants ranged 1-236 (median [IQR] 21.5 [8, 39.8]) per neonatal unit, 1-53 (median [IQR] 11.5 [2.3, 33.8]) per paediatric unit. Deaths ranged 0-37 (median [IQR] 3.5 [0.3, 8.8]) per neonatal unit, 0-7 (median [IQR] 0.5 [0, 1.8]) per paediatric unit. Three trials had a formal policy for responding to bereavement. CONCLUSIONS: A substantial number of deaths after trial enrollment were identified, distributed over many trials and units. Few trial teams had responses to bereavement in place. Those with the largest numbers of deaths might be best placed to collaborate in developing and assessing responses to bereavement.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Effect of a collector bag for measurement of postpartum blood loss after vaginal delivery: cluster randomised trial in 13 European countries

Objective To evaluate the effectiveness of the systematic use of a transparent plastic collector bag to measure postpartum blood loss after vaginal delivery in reducing the incidence of severe postpartum haemorrhage

The young age of the extremely metal-deficient blue compact dwarf galaxy SBS 1415+437

We use Multiple Mirror Telescope (MMT) spectrophotometry and Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra and Wide Field and Planetary Camera 2 (WFPC2) V and I images to study the properties and evolutionary status of the nearby (D = 11.4 Mpc) extremely metal-deficient blue compact dwarf (BCD) galaxy SBS 1415+437=CG 389. The oxygen abundance in the galaxy is 12+log(O/H)=7.60+/-0.01 or Zsun/21. The helium mass fraction in SBS 1415+437 is Y=0.246+/-0.004 which agrees with the primordial helium abundance determined by Izotov & Thuan using a much larger sample of BCDs. The alpha-elements-to-oxygen abundance ratios (Ne/O, S/O, Ar/O) are in very good agreement with the mean values for other metal-deficient BCDs and are consistent with the scenario that these elements are made in massive stars. The Fe/O abundance ratio is ~2 times smaller than the solar ratio. The Si/O ratio is close to the solar value, implying that silicon is not significantly depleted into dust grains. The values of the N/O and C/O ratios imply that intermediate-mass stars have not had time to evolve in SBS 1415+437 and release their nucleosynthesis products and that both N and C in the BCD have been made by massive stars only. This sets an upper limit of ~100 Myr on the age of SBS 1415+437. The (V-I) color of the low-surface-brightness component of the galaxy is blue (<0.4 mag) indicative of a very young underlying stellar population. The (V-I) - I color-magnitude diagrams of the resolved stellar populations in different regions of SBS 1415+437 suggest propagating star formation from the NE side of the galaxy to the SW. All regions in SBS 1415+437 possess very blue spectral energy distributions (SED). We find that the ages of the stellar populations in SBS 1415+437 to range from a few Myr to 100 Myr.Comment: 25 pages, 12 PS and 5 JPG figures, to appear in Ap

Broad Recombination Line Objects in W49N on 600 AU Scales

High resolution 7 mm observations of the W49N massive star forming region have detected recombination line emission from the individual ultracompact (UC) HII regions on 50 milliarcsecond (600 AU) scales. These line observations, combined with multifrequency, high-resolution continuum imaging of the region at 7 mm (VLA) and at 3 mm and 1 mm (BIMA), indicate that five to seven of the eighteen ultracompact sources in W49N are broad recombination line objects (BRLOs) as described by Jaffe & Martin-Pintado (1999). BRLOs have both broad radio recombination lines ($\Delta$V$>$60 \kms) and rising spectra (S$_{\nu}\sim\nu^{\alpha}$), with $\alpha$ values greater than 0.4. The broad line widths of the H52$\alpha$ line are probably related to motions in the ionized gas rather than pressure broadening. A number of models have been proposed to explain the long lifetime of UC HII regions, including the photoevaporated disk model proposed by Hollenbach et al. (1994). This model can also explain the broad lines, rising spectra and bipolar morphologies of some sources. We suggest$-$based on line and continuum observations as well as source morphology$-$that in a subset of the W49N ultracompact sources we may be observing ionized winds that arise from circumstellar disks.Comment: 15 pages, 2 figures, to appear in The Astrophysical Journal (v. 600, no. 1), 1 January 200

Management and implications of severe COVID-19 in pregnancy in the UK: data from the UK Obstetric Surveillance System national cohort

INTRODUCTION: There is a lack of population level data on risk factors and impact of severe COVID-19 in pregnancy. The aims of this study were to determine the characteristics, and maternal and perinatal outcomes associated with severe COVID-19 in pregnancy compared with those with mild and moderate COVID-19 and to explore the impact of timing of birth. MATERIAL AND METHODS: This was a secondary analysis of a national, prospective cohort study. All pregnant women admitted to hospital in the UK with symptomatic SARS-CoV-2 from March 1, 2020 to October 31, 2021 were included. The severity of maternal infection (need for high flow or invasive ventilation, intensive care admission or died), pregnancy and perinatal outcomes, and the impact of timing of birth were analyzed using multivariable logistic regression. RESULTS: Of 4436 pregnant women, 13.9% (n = 616) had severe infection. Women with severe infection were more likely to be aged ≥30 years (adjusted odds ratio [aOR] aged 30-39 1.48, 95% confidence interval [CI] 1.20-1.83), be overweight or obese (aOR 1.73, 95% CI 1.34-2.25 and aOR 2.52 95% CI 1.97-3.23, respectively), be of mixed ethnicity (aOR 1.93, 95% CI 1.17-3.21) or have gestational diabetes (aOR 1.43, 95% CI 1.09-1.87) compared with those with mild or moderate infection. Women with severe infection were more likely to have a pre-labor cesarean birth (aOR 8.84, 95% CI 6.61-11.83), a very or extreme preterm birth (28-31+ weeks' gestation, aOR 18.97, 95% CI 7.78-14.85; <28 weeks' gestation, aOR 12.35, 95% CI 6.34-24.05) and their babies were more likely to be stillborn (aOR 2.51, 95% CI 1.35-4.66) or admitted to a neonatal unit (aOR 11.61, 95% CI 9.28-14.52). Of 112 women with severe infection who were discharged and gave birth at a later admission, the majority gave birth ≥36 weeks (85.7%), noting that three women in this group (2.7%) had a stillbirth. CONCLUSIONS: Severe COVID-19 in pregnancy increases the risk of adverse outcomes. Information to promote uptake of vaccination should specifically target those at greatest risk of severe outcomes. Decisions about timing of birth should be informed by multidisciplinary team discussion; however, our data suggest that women with severe infection who do not require early delivery have mostly good outcomes but that those with severe infection at term may warrant rapid delivery

Severity of maternal infection and perinatal outcomes during periods of SARS-CoV-2 wildtype, alpha, and delta variant dominance in the UK: prospective cohort study

OBJECTIVE: To compare the severity of maternal infection and perinatal outcomes during periods in which wildtype, alpha variant, and delta variant of SARS-CoV-2 were dominant in the UK. DESIGN: Prospective cohort study. SETTING: 194 obstetric units across the UK, during the following periods: between 1 March and 30 November 2020 (wildtype dominance), between 1 December 2020 and 15 May 2021 (alpha variant dominance), and between 16 May and 31 October 2021 (delta variant dominance). PARTICIPANTS: 4436 pregnant women admitted to hospital with covid-19 related symptoms. MAIN OUTCOME MEASURES: Moderate to severe maternal SARS-CoV-2 infection (indicated by any of the following: oxygen saturation <95% on admission, need for oxygen treatment, evidence of pneumonia on imaging, admission to intensive care, or maternal death), and pregnancy and perinatal outcomes (including mode and gestation of birth, stillbirth, live birth, admission to neonatal intensive care, and neonatal death). RESULTS: 1387, 1613, and 1436 pregnant women were admitted to hospital with covid-19 related symptoms during the wildtype, alpha, and delta dominance periods, respectively; of these women, 340, 585, and 614 had moderate to severe infection, respectively. The proportion of pregnant women admitted with moderate to severe infection increased during the subsequent alpha and delta dominance periods, compared with the wildtype dominance period (wildtype 24.5% v alpha 36.2% (adjusted odds ratio 1.98, 95% confidence interval 1.66% to 2.37%); wildtype 24.5% v delta 42.8% (2.66, 2.21 to 3.20)). Compared with the wildtype dominance period, women admitted during the alpha dominance period were significantly more likely to have pneumonia, require respiratory support, and be admitted to intensive care; these three risks were even greater during the delta dominance period (wildtype v delta: pneumonia, adjusted odds ratio 2.52, 95% confidence interval 2.06 to 3.09; respiratory support, 1.90, 1.52 to 2.37; and intensive care, 2.71, 2.06 to 3.56). Of 1761 women whose vaccination status was known, 38 (2.2%) had one dose and 16 (1%) had two doses before their diagnosis (of whom 14 (88%) had mild infection). The proportion of women receiving drug treatment for SARS-CoV-2 management was low, but did increase between the wildtype dominance period and the alpha and delta dominance periods (10.4% wildtype v 14.9% alpha (2.74, 2.08 to 3.60); 10.4% wildtype v 13.6% delta (2.54, 1.90 to 3.38)). CONCLUSIONS: While limited by the absence of variant sequencing data, these findings suggest that during the periods when the alpha and delta variants of SARS-CoV-2 were dominant, covid-19 was associated with more severe maternal infection and worse pregnancy outcomes than during the wildtype dominance period. Most women admitted with SARS-CoV-2 related symptoms were unvaccinated. Urgent action to prioritise vaccine uptake in pregnancy is essential. STUDY REGISTRATION: ISRCTN40092247

Improving Predictions for Helium Emission Lines

We have combined the detailed He I recombination model of Smits with the collisional transitions of Sawey & Berrington in order to produce new accurate helium emissivities that include the effects of collisional excitation from both the 2 (3)S and 2 (1) S levels. We present a grid of emissivities for a range of temperature and densities along with analytical fits and error estimates. Fits accurate to within 1% are given for the emissivities of the brightest lines over a restricted range for estimates of primordial helium abundance. We characterize the analysis uncertainties associated with uncertainties in temperature, density, fitting functions, and input atomic data. We estimate that atomic data uncertainties alone may limit abundance estimates to an accuracy of 1.5%; systematic errors may be greater than this. This analysis uncertainty must be incorporated when attempting to make high accuracy estimates of the helium abundance. For example, in recent determinations of the primordial helium abundance, uncertainties in the input atomic data have been neglected.Comment: ApJ, accepte