A high-redshift quasar absorber without CIV - a galactic outflow caught in the act?

We present a detailed analysis of a very unusual sub-damped Lyman alpha (sub-DLA) system at redshift z=2.304 towards the quasar Q0453-423, based on high signal-to-noise (S/N), high-resolution spectral data obtained with VLT/UVES. With a neutral hydrogen column density of log N(HI)=19.23 and a metallicity of -1.61 as indicated by [OI/HI] the sub-DLA mimics the properties of many other optically thick absorbers at this redshift. A very unusual feature of this system is, however, the lack of any CIV absorption at the redshift of the neutral hydrogen absorption, although the relevant spectral region is free of line blends and has very high S/N. Instead, we find high-ion absorption from CIV and OVI in another metal absorber at a velocity more than 220km/s redwards of the neutral gas component. We explore the physical conditions in the two different absorption systems using Cloudy photoionisation models. We find that the weakly ionised absorber is dense and metal-poor while the highly ionised system is thin and more metal-rich. The absorber pair towards Q0453-423 mimics the expected features of a galactic outflow with highly ionised material that moves away with high radial velocities from a (proto)galactic gas disk in which star-formation takes place. We discuss our findings in the context of CIV absorption line statistics at high redshift and compare our results to recent galactic-wind and outflow models.Comment: 11 pages, 7 figures, accepted by A&

VLT/UVES observations of peculiar alpha abundances in a sub-DLA at z ~ 1.8 towards the quasar B1101-26

We present a detailed analysis of chemical abundances in a sub-damped Lyman alpha absorber at z=1.839 towards the quasar B1101-26, based on a very-high-resolution (R ~ 75,000) and high-signal-to-noise (S/N >100) spectrum observed with the UV Visual Echelle spectrograph (UVES) installed on the ESO Very Large Telescope (VLT). The absorption line profiles are resolved into a maximum of eleven velocity components spanning a rest-frame velocity range of 200 km/s. Detected ions include CII, CIV, NII, OI, MgI, MgII, AlII, AlIII, SiII, SiIII, SiIV, FeII, and possibly SII. The total neutral hydrogen column density is log N(HI) = 19.48 +/- 0.01. From measurements of column densities and Doppler parameters we estimate element abundances of the above-given elements. The overall metallicity, as traced by [OI/HI], is -1.56 +/- 0.01. For the nitrogen-to-oxygen ratio we derive an upper limit of [NI/OI] < -0.65, which suggests a chemically young absorption line system. This is supported by a supersolar alpha/Fe ratio of [SiII/FeII] ~ 0.5. The most striking feature in the observed abundance pattern is an unusually high sulphur-to-oxygen ratio of 0.69 < [SII/OI] < 1.26. We calculate detailed photoionisation models for two subcomponents with Cloudy, and can rule out that ionisation effects alone are responsible for the high S/O ratio. We instead speculate that the high S/O ratio is caused by the combination of several effects, such as specific ionisation conditions in multi-phase gas, unusual relative abundances of heavy elements, and/or dust depletion in a local gas environment that is not well mixed and/or that might be related to star-formation activity in the host galaxy. We discuss the implications of our findings for the interpretation of alpha-element abundances in metal absorbers at high redshift.Comment: 16 pages, 10 figures, to be published in A&

Perinatal tissue oxygenation and neurodevelopment in preterm and growth restricted infants

Preterm birth and fetal growth restriction present major risk factors for an inadequate oxygen supply of the developing brain and other organs. Doppler ultrasound and near-infrared spectroscopy help assess organ oxygen delivery in the fetus and newborn. Using these techniques, this thesis investigated how placental insufficiency and drug exposure before birth affect oxygenation of the brain, kidneys, and intestines in preterm and growth restricted infants. Additionally, this thesis assessed how fetal ‘brain-sparing’ (redistribution of blood flow to the brain at the expense of other organs as a compensatory response to chronically low oxygen levels in placental insufficiency) and oxygenation of the brain after birth relate to neurodevelopmental outcome.Our data suggest that fetal brain-sparing and higher cerebral oxygen saturations after birth are related to less behavioral problems and better executive functions. On the other hand, fetal brain-sparing may cause cerebral oxygen levels being too high for preterm babies, which we associated with an increased risk of retinopathy of prematurity, a potentially blinding eye condition, and poorer long-term Performance IQ. Epigenetic changes seem to be involved. Moreover, fetal brain-sparing seems to impair autoregulatory mechanisms, with which the brain protects itself from harmful fluctuations in blood flow and oxygenation after birth. Fetal exposure to drugs with vasodilative properties, appeared to also affect organ oxygen delivery in the newborn. This needs to be taken into account when using these drugs in pregnant women or when investigating new treatments for placental insufficiency

Self-esteem moderates affective reactions to briefly presented emotional faces

According to the sociometer hypothesis individuals with low self-esteem experience increased negative affect in response to negative social stimuli, even when these stimuli are not perceived consciously. Using an affective priming paradigm, the present study examined whether trait self-esteem would moderate mood following briefly presented facial expressions. Results from 43 undergraduates revealed that, after controlling for baseline mood, anxiety and depression, the degree of negative affect experienced by the participants following exposure to expressions of anger and disgust varied as a function of their self-esteem. Implications for individuals with low-self esteem and our understanding of the link between self-esteem and negative affect are discussed