The influence of a changing bacterial community on trace metal scavenging in a deep-sea particle plume

An extensive set of particle samples was collected from the extended (nonbuoyant) hydrothermal plume, the distal remnant plume, and the adjacent waters in a transect across the Southern Juan de Fuca Ridge. Bacterial capsules comprised the primary species of particulate Mn. However, the data also showed significant shifts in the relative abundance of distinctive subpopulations of this bacterial community, as expressed by several consistently recurring capsule morphologies. The data are discussed with respect to distance from plume origins (relative plume age), total bacterial numbers, experimentally determined scavenging rate constants and total particulate and dissolved Mn. The relative distribution of one morph (Fibrous) corresponded (r = .825, p \u3c 0.001) to that of the scavenging rate constant, k1 (Cowen et al., 1990) for dissolved Mn onto particles. The greatest Mn deposits (by a factor of over 10×) were associated with this same morph, which was also the numerically dominant capsule morph at the off-axis stations where total particulate Mn plume values were highest. The disequilibrium in the particle population and the geochemical cycle of Mn in an evolving hydrothermal vent plume is reflected in the distribution coefficients for Mn (KD), which increase with distance from vent origins. The potential influence that changing subpopulations of bacteria may exert on the overall scavenging behavior of Mn in this evolving natural particle population is emphasized

Vacancy induced zero energy modes in graphene stacks: The case of ABC trilayer

The zero energy modes induced by vacancies in ABC stacked trilayer graphene are investigated. Depending on the position of the vacancy, a new zero energy solution is realised, different from those obtained in multilayer compounds with Bernal stacking. The electronic modification induced in the sample by the new vacancy states is characterised by computing the local density of states and their localisation properties are studied by the inverse participation ratio. We also analyse the situation in the presence of a gap in the spectrum due to a perpendicular electric field.Comment: 6 pages, 4 figures Published in special issue: Exploring Graphene, Recent Research Advance

Receptor Quaternary Organization Explains G Protein-Coupled Receptor Family Structure.

The organization of Rhodopsin-family G protein-coupled receptors (GPCRs) at the cell surface is controversial. Support both for and against the existence of dimers has been obtained in studies of mostly individual receptors. Here, we use a large-scale comparative study to examine the stoichiometric signatures of 60 receptors expressed by a single human cell line. Using bioluminescence resonance energy transfer- and single-molecule microscopy-based assays, we found that a relatively small fraction of Rhodopsin-family GPCRs behaved as dimers and that these receptors otherwise appear to be monomeric. Overall, the analysis predicted that fewer than 20% of ∼700 Rhodopsin-family receptors form dimers. The clustered distribution of the dimers in our sample and a striking correlation between receptor organization and GPCR family size that we also uncover each suggest that receptor stoichiometry might have profoundly influenced GPCR expansion and diversification

Higher media multi-tasking activity is associated with smaller gray-matter density in the anterior cingulate cortex

Media multitasking, or the concurrent consumption of multiple media forms, is increasingly prevalent in today’s society and has been associated with negative psychosocial and cognitive impacts. Individuals who engage in heavier media-multitasking are found to perform worse on cognitive control tasks and exhibit more socio-emotional difficulties. However, the neural processes associated with media multi-tasking remain unexplored. The present study investigated relationships between media multitasking activity and brain structure. Research has demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. Thus, we expected differential engagements in media multitasking to correlate with brain structure variability. This was confirmed via Voxel-Based Morphometry (VBM) analyses: Individuals with higher Media Multitasking Index (MMI) scores had smaller gray matter density in the anterior cingulate cortex (ACC). Functional connectivity between this ACC region and the precuneus was negatively associated with MMI. Our findings suggest a possible structural correlate for the observed decreased cognitive control performance and socio-emotional regulation in heavy media-multitaskers. While the cross-sectional nature of our study does not allow us to specify the direction of causality, our results brought to light novel associations between individual media multitasking behaviors and ACC structure differences

Enhanced nitrogen and phosphorus flows in a mixed land use basin: drivers and consequences

Rapid increase in accumulation of phosphorus (P) relative to nitrogen (N) has been observed in human-impacted regions, but the reasons are largely unknown. We developed an Integrated Nutrient Flow Analysis (INFA) model in order to assess the changes in nutrient flows of the Chaohu Lake basin from 1978 to 2015. Results show that the increase in total N input is slower than that of P (3.5-fold versus 4.2-fold) during 1978–2015, while total N loss increases much faster than that of P (3.1-fold versus 2.3-fold). We found a decline trend in the N:P ratio of nutrient input and accumulation since the mid-1990s. The decline in N:P ratio of nutrient loss to waterbodies in the basin is correlated (p < 0.05) with TN:TP of water concentration in Chaohu Lake, which may be related to the frequent algal blooms in the P-limited lake by supplying more P than N. Using an extended STIRPAT model, we found that nutrient use efficiency, urban rate, diet choice and population are key factors driving the change in nutrient flows, which contribute over 90% to the total change. This study confirms that human activities decrease N:P in regional environment and demonstrates the importance of P management to balance nutrient for improving water quality. The method in this study has a wide application for many other mixed land use regions to address nutrient flows imbalance problems and to explore nutrient management options