Crustal structure of the conjugate Equatorial Atlantic Margins, derived by gravity anomaly inversion

Abstract The crustal structure of the Equatorial Atlantic conjugate margins (South America and West Africa) has been investigated using 3D gravity anomaly inversion, which allows for (1) the elevated geothermal gradient of the lithosphere following rifting and break-up and (2) magmatic addition to the crust during rifting and break-up. It is therefore particularly suitable for the analysis of rifted margins and their associated ocean basins. Maps of crustal thickness and conjugate-margin stretching, derived from gravity anomaly inversion, are used to illustrate how the Equatorial Atlantic opened as a set of stepped rift-transform segments, rather than as a simple orthogonal rifted margin. The influence of the transform faults and associated oceanic fracture zones is particularly clear when the results of the gravity anomaly inversion are combined with a shaded-relief display of the free-air gravity anomaly. A set of crustal cross-sections has been extracted from the results of the gravity inversion along both equatorial margins. These illustrate the crustal structure of both rifted-margin segments and transform-margin segments. The maps and cross-sections are used to delineate crustal type on the margins as (1) inboard, entirely continental, (2) outboard, entirely oceanic and (3) the ocean–continent transition in between where mixed continental and magmatic crust is likely to be present. For a given parameterization of melt generation the amount of magmatic addition within the ocean–continent transition is predicted by the gravity inversion. One of the strengths of the gravity-inversion technique is that these predictions can be made in the absence of any other directly acquired data. On both margins anomalously thick crust is resolved close to a number of oceanic fracture zones. On the South American margin we believe that this thick crust is probably the result of post-break-up magmatism within what was originally normal-thickness oceanic crust. On the West African margin, however, three possible origins are discussed: (1) continental crust extended oceanwards along the fracture zones; (2) oceanic crust magmatically thickened at the fracture zones; and (3) oceanic crust thickened by transpression along the fracture zones. Gravity inversion alone cannot discriminate between these possibilities. The cross-sections also show that, while ‘normal thickness’ oceanic crust (c. 7 km) predominates regionally, local areas of thinner (c. 5 km) and thicker (c. 10 km) oceanic crust are also present along both margins. Finally, using maps of crustal thickness and thinning factor as input to plate reconstructions, the regional palaeogeography of the Equatorial Atlantic during and after break-up is displayed at 10 Ma increments.</jats:p

3D Seismic reflection evidence for lower crustal intrusions beneath the Faroe–Shetland Basin, NE Atlantic Margin

Lower crustal intrusion is considered to be a common process along volcanic or magma-rich passive margins, including the NE Atlantic Margin, where it is thought to have occurred during phases of Paleogene magmatism, both prior to and during continental break-up between NW Europe and Greenland. Evidence of Paleogene magmatism is prevalent throughout the sub-basins of the Faroe–Shetland Basin as extensive lava flows and pervasive suites of igneous intrusions. However, in contrast with other areas located along the NE Atlantic Margin, no lower crustal reflectivity indicative of lower crustal intrusion has been documented beneath the Faroe–Shetland Basin. The nearest documentation of lower crustal reflectivity and interpretation of lower crustal intrusion to the Faroe–Shetland Basin is NW of the Fugloy Ridge, beneath the Norwegian Basin of the Faroese sector. Despite this, the addition of magma within the lower crust and/or at the Mohorovičić discontinuity is thought to have played a part in Paleogene uplift and the subsequent deposition of Paleocene–Eocene sequences. Advances in sub-basalt seismic acquisition and processing have made significant improvements in facilitating the imaging of deep crustal structures along the NE Atlantic Margin. This study used broadband 3D seismic reflection data to map a series of deep (c. 14–20 km depth) high-amplitude reflections that may represent igneous intrusions within the lower crust beneath the central-northern Corona Ridge. We estimate that the cumulative thicknesses of the reflections may be >5 km in places, which is consistent with published values of magmatic underplating within the region based on geochemical and petrological data. We also estimate that the total volume of lower crustal high-amplitude reflections within the 3D dataset may be >2000 km3. 2D gravity modelling of a seismic line located along the central-northern Corona Ridge supports the interpretation of lower crustal intrusions beneath this area. This study provides evidence of a potential mechanism for Paleogene uplift within the region. If uplift occurred as a result of lower crustal intrusions emplaced within the crust during the Paleogene, then we estimate that c. 300 m of uplift may have been generated within the Corona Ridge area

New constraints on the mass of fermionic dark matter from dwarf spheroidal galaxies

Theoretical Physic

Impact of shortened crop rotation of oilseed rape on soil and rhizosphere microbial diversity in relation to yield decline

Oilseed rape (OSR) grown in monoculture shows a decline in yield relative to virgin OSR of up to 25%, but the mechanisms responsible are unknown. A long term field experiment of OSR grown in a range of rotations with wheat was used to determine whether shifts in fungal and bacterial populations of the rhizosphere and bulk soil were associated with the development of OSR yield decline. The communities of fungi and bacteria in the rhizosphere and bulk soil from the field experiment were profiled using terminal restriction fragment length polymorphism (TRFLP) and sequencing of cloned internal transcribed spacer regions and 16S rRNA genes, respectively. OSR cropping frequency had no effect on rhizosphere bacterial communities. However, the rhizosphere fungal communities from continuously grown OSR were significantly different to those from other rotations. This was due primarily to an increase in abundance of two fungi which showed 100% and 95% DNA identity to the plant pathogens Olpidium brassicae and Pyrenochaeta lycopersici, respectively. Real-time PCR confirmed that there was significantly more of these fungi in the continuously grown OSR than the other rotations. These two fungi were isolated from the field and used to inoculate OSR and Brassica oleracea grown under controlled conditions in a glasshouse to determine their effect on yield. At high doses, Olpidium brassicae reduced top growth and root biomass in seedlings and reduced branching and subsequent pod and seed production. Pyrenochaeta sp. formed lesions on the roots of seedlings, and at high doses delayed flowering and had a negative impact on seed quantity and quality

Repurposing a photosynthetic antenna protein as a super-resolution microscopy label

Techniques such as Stochastic Optical Reconstruction Microscopy (STORM) and Structured Illumination Microscopy (SIM) have increased the achievable resolution of optical imaging, but few fluorescent proteins are suitable for super-resolution microscopy, particularly in the far-red and near-infrared emission range. Here we demonstrate the applicability of CpcA, a subunit of the photosynthetic antenna complex in cyanobacteria, for STORM and SIM imaging. The periodicity and width of fabricated nanoarrays of CpcA, with a covalently attached phycoerythrobilin (PEB) or phycocyanobilin (PCB) chromophore, matched the lines in reconstructed STORM images. SIM and STORM reconstructions of Escherichia coli cells harbouring CpcA-labelled cytochrome bd 1 ubiquinol oxidase in the cytoplasmic membrane show that CpcA-PEB and CpcA-PCB are suitable for super-resolution imaging in vivo. The stability, ease of production, small size and brightness of CpcA-PEB and CpcA-PCB demonstrate the potential of this largely unexplored protein family as novel probes for super-resolution microscopy

Become the best coach you can be: the role of coach training and coaching experience in workplace coaching quality and quality control

This paper explores whether coach training or coaching experience leads to better coaching quality and quality control. In two large studies, both coaches (N1 = 2267) and personnel managers who book coaches for their company (N2 = 754) answered questions about coaching quality and quality control. The results show that more coach training leads to not only a better self-perceived coaching quality (Study 1) but also a better other-perceived coaching-quality (Study 2); moreover, more coach training positively affects quality control. It is remarkable that coaching experience showed no significant relation regarding other-perceived coaching quality and quality control. Study 2 further revealed that references lead to more recommendations but not to a better coaching quality or quality control. Thus, coach training is an essential factor when selecting organizational coaches. Further research is needed to understand the impact of different approaches to coach trainings on coaching outcomes

Genomic diversity of bacteriophages infecting Microbacterium spp

The bacteriophage population is vast, dynamic, old, and genetically diverse. The genomics of phages that infect bacterial hosts in the phylum Actinobacteria show them to not only be diverse but also pervasively mosaic, and replete with genes of unknown function. To further explore this broad group of bacteriophages, we describe here the isolation and genomic characterization of 116 phages that infect Microbacterium spp. Most of the phages are lytic, and can be grouped into twelve clusters according to their overall relatedness; seven of the phages are singletons with no close relatives. Genome sizes vary from 17.3 kbp to 97.7 kbp, and their G+C% content ranges from 51.4% to 71.4%, compared to ~67% for their Microbacterium hosts. The phages were isolated on five different Microbacterium species, but typically do not efficiently infect strains beyond the one on which they were isolated. These Microbacterium phages contain many novel features, including very large viral genes (13.5 kbp) and unusual fusions of structural proteins, including a fusion of VIP2 toxin and a MuF-like protein into a single gene. These phages and their genetic components such as integration systems, recombineering tools, and phage-mediated delivery systems, will be useful resources for advancing Microbacterium genetics

CONQUER Scleroderma: Association of Gastrointestinal Tract Symptoms in Early Disease With Resource Utilization

OBJECTIVES: SSc is associated with increased health-care resource utilization and economic burden. The Collaborative National Quality and Efficacy Registry (CONQUER) is a US-based collaborative that collects longitudinal follow-up data on SSc patients withparticipants. METHODS: CONQUER participants who had completed a baseline and 12-month Gastrointestinal Tract Questionnaire (GIT 2.0) and a Resource Utilization Questionnaire (RUQ) were included in this analysis. Patients were categorized by total GIT 2.0 severity: none-to-mild (0-0.49); moderate (0.50-1.00), and severe-to-very severe (1.01-3.00). Clinical features and medication exposures were examined in each of these categories. The 12-month RUQ responses were summarized by GIT 2.0 score categories at 12 months. RESULTS: Among the 211 CONQUER participants who met the inclusion criteria, most (64%) had mild GIT symptoms, 26% had moderate symptoms, and 10% severe GIT symptoms at 12 months. The categorization of GIT total severity score by RUQ showed that more upper endoscopy procedures and inpatient hospitalization occurred in the CONQUER participants with severe GIT symptoms. These patients with severe GIT symptoms also reported the use of more adaptive equipment. CONCLUSION: This report from the CONQUER cohort suggests that severe GIT symptoms result in more resource utilization. It is especially important to understand resource utilization in early disease cohorts when disease activity, rather than damage, primarily contributes to health-related costs of SSc

Centriole movements in mammalian epithelial cells during cytokinesis

<p>Abstract</p> <p>Background</p> <p>In cytokinesis, when the cleavage furrow has been formed, the two centrioles in each daughter cell separate. It has been suggested that the centrioles facilitate and regulate cytokinesis to some extent. It has been postulated that termination of cytokinesis (abscission) depends on the migration of a centriole to the intercellular bridge and then back to the cell center. To investigate the involvement of centrioles in cytokinesis, we monitored the movements of centrioles in three mammalian epithelial cell lines, HeLa, MCF 10A, and the p53-deficient mouse mammary tumor cell line KP-7.7, by time-lapse imaging. Centrin1-EGFP and α-Tubulin-mCherry were co-expressed in the cells to visualize respectively the centrioles and microtubules.</p> <p>Results</p> <p>Here we report that separated centrioles that migrate from the cell pole are very mobile during cytokinesis and their movements can be characterized as 1) along the nuclear envelope, 2) irregular, and 3) along microtubules forming the spindle axis. Centriole movement towards the intercellular bridge was only seen occasionally and was highly cell-line dependent.</p> <p>Conclusions</p> <p>These findings show that centrioles are highly mobile during cytokinesis and suggest that the repositioning of a centriole to the intercellular bridge is not essential for controlling abscission. We suggest that centriole movements are microtubule dependent and that abscission is more dependent on other mechanisms than positioning of centrioles.</p