Editorial: The Impact of Microorganisms on Consumption of Atmospheric Trace Gases

Editorial on the Research Topic: The Impact of Microorganisms on Consumption of Atmospheric Trace Gase

Neural Correlates of Speech Processing in Prelingually Deafened Children and Adolescents with Cochlear Implants

Prelingually deafened children with cochlear implants stand a good chance of developing satisfactory speech performance. Nevertheless, their eventual language performance is highly variable and not fully explainable by the duration of deafness and hearing experience. In this study, two groups of cochlear implant users (CI groups) with very good basic hearing abilities but non-overlapping speech performance (very good or very bad speech performance) were matched according to hearing age and age at implantation. We assessed whether these CI groups differed with regard to their phoneme discrimination ability and auditory sensory memory capacity, as suggested by earlier studies. These functions were measured behaviorally and with the Mismatch Negativity (MMN). Phoneme discrimination ability was comparable in the CI group of good performers and matched healthy controls, which were both better than the bad performers. Source analyses revealed larger MMN activity (155–225 ms) in good than in bad performers, which was generated in the frontal cortex and positively correlated with measures of working memory. For the bad performers, this was followed by an increased activation of left temporal regions from 225 to 250 ms with a focus on the auditory cortex. These results indicate that the two CI groups developed different auditory speech processing strategies and stress the role of phonological functions of auditory sensory memory and the prefrontal cortex in positively developing speech perception and production

Detectable contributions of colloids to soil P and C content in arid and hyperarid region of the Atacama (Chile)

Atacama Desert is mainly known as the driest place on Earth where life has been developed under arid to hyper arid conditions since Oligocene-Miocene. Therefore, soils of Atacama contain fingerprints of past and present life which might be used as an analog to study the evolution of life under equivalent arid conditions, like Mars. In this study, we quantify the colloidal phosphorus and carbon distribution in the first 10 cm of soil profile along an altitudinal transect. Samples were taken along a transect in the region of Quebrada Aroma spanning from the arid Percordillera of the Andes (2720 m a.s.l.) towards the hyper arid core of the desert (1340 m a.s.l.). Water dispersible colloids (WDC) were separated and measured using the field-flow-field fractionation (FFF) method and subsequently their Corg and P content were characterized and quantified by detectors (DLS, ICP-MS, UV, OCD, fluorescence). Data was compared to total C, P and (available) Olsen-P also measured in the samples. The Olsen-P (available-P) varied within the Aroma transect from ca. 2 to 8 mg P kg-1, but was not related to either altitude or depth in the upper soil (0-10 cm). Colloidal P contents ranged from <0.1 to 4 mg P kg-1 soil, with increasing trend from low to higher elevations. Thereby, suggesting an increasing proportion of the available P potential being present in the WDC fraction. The Colloidal Corg content of the Aroma transect did range from 65 to 90 (for sites 2020 to 1340m) and 110 mg Corg kg-1 soil WDC (2720 m). Colloidal Corg content as a function of the altitude showed a similar trend to the Corg content of the soils: the highest colloidal Corg content was found at 2720 m. The proportion of soil Corg within the colloidal fraction was up to 6% of the bulk soil organic matter (OM) content, as the OM content was intensively enriched in the colloidal fraction. Further quantification of phosphorus and carbon content in WDC in deeper part of soil is required to obtain a more comprehensive view of role of colloidal inputs and dynamics in the Atacama Desert

Electronic Structure of Dangling Bonds in Amorphous Silicon Studied via a Density-Matrix Functional Method

A structural model of hydrogenated amorphous silicon containing an isolated dangling bond is used to investigate the effects of electron interactions on the electronic level splittings, localization of charge and spin, and fluctuations in charge and spin. These properties are calculated with a recently developed density-matrix correlation-energy functional applied to a generalized Anderson Hamiltonian, consisting of tight-binding one-electron terms parametrizing hydrogenated amorphous silicon plus a local interaction term. The energy level splittings approach an asymptotic value for large values of the electron-interaction parameter U, and for physically relevant values of U are in the range 0.3-0.5 eV. The electron spin is highly localized on the central orbital of the dangling bond while the charge is spread over a larger region surrounding the dangling bond site. These results are consistent with known experimental data and previous density-functional calculations. The spin fluctuations are quite different from those obtained with unrestricted Hartree-Fock theory.Comment: 6 pages, 6 figures, 1 tabl

In Vitro Analysis of Immersed Human Tissues by Raman Microspectroscopy

Raman microspectroscopy is a powerful tool for the analysis of tissue sections, providing a molecular map of the investigated samples. Nevertheless, data pre-processing and, particularly, the removal of the broad background to the spectra remain problematic. Indeed, the physical origin of the background has not been satisfactorily determined. Using 785 nm as source in a confocal geometry, it is demonstrated for the example of the protein kappa-elastin that the background and resulting quality of the recorded spectrum are dependent on the morphology of the sample. Whereas a fine powder yields a dominant broad background, compressed pellets and solution-cast thin films produce, respectively, improved quality spectra and significantly reduced spectral background. As the chemical composition of the samples is identical, the background is ascribed to stray light due to diffuse scattering rather than an intrinsic photoluminescence. The recorded spectra from a tissue sample exhibit a large and spatially variable background, resulting in poorly defined spectral features. A significant reduction of the background signal as well as improvement of the spectral quality is achieved by immersion of the sample in water and measurement with an immersion objective. The significant improvement in signal to background is attributed to a reduction of the diffuse scattering due to a change in the effective morphology as a result of an improved index matching at the water/tissue interface compared to the air/tissue interface. Compared to sections measured in air, the background is reduced to that of the water, and pre-processing is reduced to the subtraction of the substrate and water signal and correction for the instrument response, both of which are highly reproducible. Data pre-processing is thus greatly simplified and the results significantly more reliable

Draft genome sequences of gammaproteobacterial methanotrophs isolated from marine ecosystems

The genome sequences of Methylobacter marinus A45, Methylobacter sp. strain BBA5.1, and Methylomarinum vadi IT-4 were obtained. These aerobic methanotrophs are typical members of coastal and hydrothermal vent marine ecosystems

Computed tomography-osteoabsorptiometry for assessing the density distribution of subchondral bone as a measure of long-term mechanical adaptation in individual joints

To estimate subchondral mineralisation patterns which represent the long-term loading history of individual joints, a method has been developed employing computed tomography (CT) which permits repeated examination of living joints. The method was tested on 5 knee, 3 sacroiliac, 3 ankle and 5 shoulder joints and then investigated with X-ray densitometry. A CT absorptiometric presentation and maps of the area distribution of the subchondral bone density areas were derived using an image analyser. Comparison of the results from both X-ray densitometry and CT-absorptiometry revealed almost identical pictures of distribution of the subchondral bone density. The method may be used to examine subchondral mineralisation as a measure of the mechanical adaptability of joints in the living subject

High-Pressure Amorphous Nitrogen

The phase diagram and stability limits of diatomic solid nitrogen have been explored in a wide pressure--temperature range by several optical spectroscopic techniques. A newly characterized narrow-gap semiconducting phase $\eta$ has been found to exist in a range of 80--270 GPa and 10--510 K. The vibrational and optical properties of the $\eta$ phase produced under these conditions indicate that it is largely amorphous and back transforms to a new molecular phase. The band gap of the $\eta$ phase is found to decrease with pressure indicating possible metallization by band overlap above 280 GPa.Comment: 5 pages, 4 figure

Soil methane sink capacity response to a long-term wildfire chronosequence in Northern Sweden

Boreal forests occupy nearly one fifth of the terrestrial land surface and are recognised as globally important regulators of carbon (C) cycling and greenhouse gas emissions. Carbon sequestration processes in these forests include assimilation of CO2 into biomass and subsequently into soil organic matter, and soil microbial oxidation of methane (CH4). In this study we explored how ecosystem retrogression, which drives vegetation change, regulates the important process of soil CH4 oxidation in boreal forests. We measured soil CH4 oxidation processes on a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. Across these islands the build-up of soil organic matter was observed to increase with time since fire disturbance, with a significant correlation between greater humus depth and increased net soil CH4 oxidation rates. We suggest that this increase in net CH4 oxidation rates, in the absence of disturbance, results as deeper humus stores accumulate and provide niches for methanotrophs to thrive. By using this gradient we have discovered important regulatory controls on the stability of soil CH4 oxidation processes that could not have not been explored through shorter-term experiments. Our findings indicate that in the absence of human interventions such as fire suppression, and with increased wildfire frequency, the globally important boreal CH4 sink could be diminished