The Nature and Origin of Low-Redshift O VI Absorbers

The O VI ion observed in quasar absorption line spectra is the most accessible tracer of the cosmic metal distribution in the low redshift (z<0.5) intergalactic medium (IGM). We explore the nature and origin of O VI absorbers using cosmological hydrodynamic simulations including galactic outflows. We consider the effects of ionization background variations, non-equilibrium ionization and cooling, uniform metallicity, and small-scale (sub-resolution) turbulence. Our main results are 1) IGM O VI is predominantly photo-ionized with T= 10^(4.2+/-0.2) K. A key reason for this is that O VI absorbers preferentially trace over-enriched regions of the IGM at a given density, which enhances metal-line cooling such that absorbers can cool within a Hubble time. As such, O VI is not a good tracer of the WHIM. 2) The predicted O VI properties fit observables only if sub-resolution turbulence is added. The required turbulence increases with O VI absorber strength such that stronger absorbers arise from more recent outflows with turbulence dissipating on the order of a Hubble time. The amount of turbulence is consistent with other examples of turbulence observed in the IGM and galactic halos. 3) Metals traced by O VI and H I do not trace exactly the same baryons, but reside in the same large-scale structure. Observed alignment statistics are reproduced in our simulations. 4) Photo-ionized O VI traces gas in a variety of environments, and is not directly associated with the nearest galaxy, though is typically nearest to ~0.1L* galaxies. Weaker O VI components trace some of the oldest cosmic metals. 5) Very strong absorbers are more likely to be collisionally ionized, tracing more recent enrichment (<2 Gyr) within or near galactic halos.Comment: 33 pages, 18 figures, accepted to MNRAS. Two new figures adde

Structural brain anomalies in patients with FOXG1 syndrome and in Foxg1+/- mice

Objective FOXG1 syndrome is a rare neurodevelopmental disorder associated with heterozygous FOXG1 variants or chromosomal microaberrations in 14q12. The study aimed at assessing the scope of structural cerebral anomalies revealed by neuroimaging to delineate the genotype and neuroimaging phenotype associations. Methods We compiled 34 patients with a heterozygous (likely) pathogenic FOXG1 variant. Qualitative assessment of cerebral anomalies was performed by standardized re-analysis of all 34 MRI data sets. Statistical analysis of genetic, clinical and neuroimaging data were performed. We quantified clinical and neuroimaging phenotypes using severity scores. Telencephalic phenotypes of adult Foxg1+/- mice were examined using immunohistological stainings followed by quantitative evaluation of structural anomalies. Results Characteristic neuroimaging features included corpus callosum anomalies (82%), thickening of the fornix (74%), simplified gyral pattern (56%), enlargement of inner CSF spaces (44%), hypoplasia of basal ganglia (38%), and hypoplasia of frontal lobes (29%). We observed a marked, filiform thinning of the rostrum as recurrent highly typical pattern of corpus callosum anomaly in combination with distinct thickening of the fornix as a characteristic feature. Thickening of the fornices was not reported previously in FOXG1 syndrome. Simplified gyral pattern occurred significantly more frequently in patients with early truncating variants. Higher clinical severity scores were significantly associated with higher neuroimaging severity scores. Modeling of Foxg1 heterozygosity in mouse brain recapitulated the associated abnormal cerebral morphology phenotypes, including the striking enlargement of the fornix. Interpretation Combination of specific corpus callosum anomalies with simplified gyral pattern and hyperplasia of the fornices is highly characteristic for FOXG1 syndrome.Peer reviewe

Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere

Vegetation fires are a significant source for atmospheric trace gases and aerosol particles (APs) on both local and global scale. The biomass burning APs affect cloud formation as well as microphysical and chemical processes in clouds. They influence the radiation budget directly and via altered cloud properties. Finally, this results in changes of the atmospheric energy budgets and circulation. The joint research project EFEU addressed these topics with a combined experimental and numerical approach of eight different research groups. Three series of experiments were carried out at the laboratory oven facility at MPI Mainz. Characteristic vegetation from different burning regions was investigated, e.g., Musasa (Africa), aleppo pine (Mediterranian), spruce (boreal) and peat (Indonesia). Trace gases and a wide range of AP parameters were measured, including size distributions as well as morphological, chemical, hygroscopic and radiative properties. Experimental results indicate that hygroscopic properties and drop nucleating abilities are rather similar for APs from burns of different types of hard wood but different to APs from other burning material such as maize or peat. Generally, the soluble fraction of the APs is quite small and their EC content fairly high. Radiative properties (single scattering albedo) are well correlated with the burn conditions (flaming/smoldering). For the numerical studies of the complex impact of biomass burning emissions on the atmosphere a suite of independent models was employed. Ranging from the microscale to the regional scale they complement each other in terms of spatial and temporal resolution as well as complexity of the processes described. Modelling efforts covered a detailed description of the microphysics including the ice phase, the evolution of individual biomass burning plumes, effects of radiative transport on chemistry and dynamics as well as regional atmospheric budgets of trace constituents, water and energy. Main results are: Precipitation is initiated only via the ice phase in the clouds explored. The dilution of an individual plume was predicted successfully and realistic heating and photolysis rates were simulated. Total particulate matter was correctly calculated for the Indonesian case study using emission factors and sizes of the burning areas

Comparison of 1.0 M gadobutrol and 0.5 M gadopentetate dimeglumine-enhanced magnetic resonance imaging in five hundred seventy-two patients with known or suspected liver lesions: results of a multicenter, double-blind, interindividual, randomized clinical phase-III trial

To evaluate the diagnostic efficacy (accuracy, sensitivity, specificity) of 1.0 M gadobutrol versus 0.5 M gadopentetate for the classification of lesions as either benign or malignant in patients with known or suspected liver lesions