Three-dimensional S-wave velocity structure of oceanic core complexes at 13N on the Mid-Atlantic Ridge

13°N on the Mid-Atlantic Ridge is regarded as a type site for oceanic core complexes (OCCs). Within ~70 km along the spreading centre, it hosts four OCCs in different stages of their life cycle making this an ideal location to determine how OCCs are formed, and what drives the hydrothermal circulation that sustains the vent fields associated with them. Here we describe the results of S-wave seismic tomographic modelling within a 60 x 60 km footprint containing several OCCs, the spreading centre and both flanks. A grid of 17 wide-angle seismic refraction profiles was shot within this footprint and recorded by a network of 46 ocean-bottom seismographs (OBS). Approximately 6200 S-wave arrival travel times have been modelled, constraining primarily the velocity-depth structure of the upper-to-mid-crust. Depth slices through the resulting 3-D S-wave velocity (Vs) model reveal the OCCs located at 13°20’N and 13°30’N to each have a region of relatively low Vs (3 km s-1 ) in the inter-OCC basin and regions surrounding the detachments. Using the equivalent 3-D P-wave velocity (Vp) model of Simão et al. (2020), the corresponding Vp/Vs model is calculated to investigate lithology, permeability and the existence of any off-axis magmatic intrusions that may drive fluid flow. The Vp/Vs model clearly shows that the crust beneath the deep lava-floored inter-OCC basin is characteristically oceanic (Vp/Vs ratio of 1.85, suggesting that they formed under magma poor (tectonic) conditions. The Vp/Vs model also shows that the OCCs are not connected, at least to mid-crustal level. Alternatively, if the OCCs lie on the same detachment surface, that surface would have to undulate >3 km in amplitude over a distance of <20 km for these OCCs to appear to be unconnected. Our 3-D Swave and Vp/Vs models thus support MacLeod et al.’s (2009) model of localized OCC evolution. Our S-wave velocity model also suggests that the Irinovskoe (13°20’N) and Semyenov (13°30’N) vent fields have different hydrothermal circulation drivers, with the Semyenov field being driven by magma intrusion(s) and the Irinovskoe field being driven by the spreading centre thermal gradient and pervasive flow along open permeability within the detachment footwall, perhaps further opened by roll-over to lower dip angle as it exhumes at the seabed

The importance of cephalopods in the diet of fish on the northwest European shelf.

Cephalopods are universal to the world's oceans and prey to many fish species. On the northwest European shelf, integrated ecosystem assessments are rapidly evolving into the preferred method for holistically assessing stocks, but cephalopods appear to be an overlooked component, perhaps because their roles in ecosystems have seldom been quantified in recent years. We have analysed historical fish stomach records and revisited literature at local and regional level to determine the importance of cephalopods to the diets of 26 ecologically important finfish. We conclude that, in contrast to most other large marine ecosystems, cephalopods found in the Greater North Sea and the Celtic Seas regions appear to contribute only a small fraction to the diets of ecologically important finfish (found in the stomachs of ~14% of specimens among some species, but generally only 1–3% in most species), though their role as predator may be important and require further investigation. Based on our findings, cephalopods may not represent a key component for integrated ecosystem assessments, though as squid populations have been shown to expand throughout the North Sea in recent years, regular monitoring is encouraged to identify the point where their inclusion into such models may be necessary

Extension parallel to the rift zone during segmented fault growth: application to the evolution of the NE Atlantic

The mechanical interaction of propagating normal faults is known to influence the linkage geometry of first-order faults, and the development of second-order faults and fractures, which transfer displacement within relay zones. Here we use natural examples of growth faults from two active volcanic rift zones (Koa`e, island of Hawai`i, and Krafla, northern Iceland) to illustrate the importance of horizontal-plane extension (heave) gradients, and associated vertical axis rotations, in evolving continental rift systems. Second-order extension and extensional-shear faults within the relay zones variably resolve components of regional extension, and components of extension and/or shortening parallel to the rift zone, to accommodate the inherently three-dimensional (3-D) strains associated with relay zone development and rotation. Such a configuration involves volume increase, which is accommodated at the surface by open fractures; in the subsurface this may be accommodated by veins or dikes oriented obliquely and normal to the rift axis. To consider the scalability of the effects of relay zone rotations, we compare the geometry and kinematics of fault and fracture sets in the Koa`e and Krafla rift zones with data from exhumed contemporaneous fault and dike systems developed within a > 5×104 km2 relay system that developed during formation of the NE Atlantic margins. Based on the findings presented here we propose a new conceptual model for the evolution of segmented continental rift basins on the NE Atlantic margins

UK monitoring and deposition of tephra from the May 2011 eruption of Grímsvötn, Iceland

Mapping the transport and deposition of tephra is important for the assessment of an eruption’s impact on health, transport, vegetation and infrastructure, but it is challenging at large distances from a volcano (> 1000 km), where it may not be visible to the naked eye. Here we describe a range of methods used to quantify tephra deposition and impact on air quality during the 21–28 May 2011 explosive basaltic eruption of Grímsvötn volcano, Iceland. Tephra was detected in the UK with tape-on-paper samples, rainwater samples, rainwater chemistry analysis, pollen slides and air quality measurements. Combined results show that deposition was mainly in Scotland, on 23–25 May. Deposition was patchy, with adjacent locations recording different results. Tape-on-paper samples, collected by volunteer citizen scientists, and giving excellent coverage across the UK, showed deposition at latitudes >55°N, mainly on 24 May. Rainwater samples contained ash grains mostly 20–30 μm long (maximum recorded grainsize 80 μm) with loadings of up to 116 grainscm-2. Analysis of rainwater chemistry showed high concentrations of dissolved Fe and Al in samples from N Scotland on 24–27 May. Pollen slides recorded small glass shards (3–4 μm long) deposited during rainfall on 24–25 May and again on 27 May. Air quality monitoring detected increased particulate matter concentrations in many parts of the country. An hourly concentration of particles  53°N) on 24 May but no negative effects on health were reported. Although the eruption column reached altitudes of 20 km above sea level, air mass trajectories suggest that only tephra from the lowest 4 km above sea level of the eruption plume was transported to the UK. This demonstrates that even low plumes could deliver tephra to the UK and suggests that the relative lack of basaltic tephra in the tephrochronological record is not due to transport processes

The extraordinary outburst in the massive protostellar system NGC 6334 I-MM1 : strong increase in mid-infrared continuum emission

Financial support for this work was provided by NASA through award #07_0156 issued by USRA. Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 089.C-0852(A).In recent years, dramatic outbursts have been identified toward massive protostars via infrared and millimeter dust continuum and molecular maser emission. The longest lived outburst (>6 yr) persists in NGC 6334 I-MM1, a deeply embedded object with no near-IR counterpart. Using FORCAST and HAWC+ on SOFIA, we have obtained the first mid-IR images of this field since the outburst began. Despite being undetected in pre-outburst ground-based 18 μm images, MM1 is now the brightest region at all three wavelengths (25, 37, and 53 μm), exceeding the UCHII region MM3 (NGC 6334 F). Combining the SOFIA data with ALMA imaging at four wavelengths, we construct a spectral energy distribution of the combination of MM1 and the nearby hot core MM2. The best-fit Robitaille radiative transfer model yields a luminosity of (4.9 ± 0.8) × 104 L⊙. Accounting for an estimated pre-outburst luminosity ratio MM1:MM2 = 2.1 ± 0.4, the luminosity of MM1 has increased by a factor of 16.3 ± 4.4. The pre-outburst luminosity implies a protostar of mass 6.7 M⊙, which can produce the ionizing photon rate required to power the pre-outburst HCHII region surrounding the likely outbursting protostar MM1B. The total energy and duration of the outburst exceed the S255IR-NIRS3 outburst by a factor of 3, suggesting a different scale of event involving expansion of the protostellar photosphere (to 20 R⊙), thereby supporting a higher accretion rate (0.0023 M⊙ yr−1) and reducing the ionizing photon rate. In the grid of hydrodynamic models of Meyer et al., the combination of outburst luminosity and magnitude (3) places the NGC 6334 I-MM1 event in the region of moderate total accretion (~0.1–0.3 M⊙) and hence long duration (~40–130 yr).PostprintPeer reviewe

Multimessenger astronomy with the Einstein Telescope

Gravitational waves (GWs) are expected to play a crucial role in the development of multimessenger astrophysics. The combination of GW observations with other astrophysical triggers, such as from gamma-ray and X-ray satellites, optical/radio telescopes, and neutrino detectors allows us to decipher science that would otherwise be inaccessible. In this paper, we provide a broad review from the multimessenger perspective of the science reach offered by the third generation interferometric GW detectors and by the Einstein Telescope (ET) in particular. We focus on cosmic transients, and base our estimates on the results obtained by ET's predecessors GEO, LIGO, and Virgo.Comment: 26 pages. 3 figures. Special issue of GRG on the Einstein Telescope. Minor corrections include

The Stroop revisited: a meta-analysis of interference control in AD/HD

Background: An inhibition deficit, including poor interference control, has been implicated as one of the core deficits in AD/HD. Interference control is clinically measured by the Stroop Colour-Word Task. The aim of this meta-analysis was to investigate the strength of an interference deficit in AD/HD as measured by the Stroop Colour-Word Task and to assess the role of moderating variables that could explain the results. These moderating variables included: methods of calculating the interference score, comorbid reading and psychiatric disorders, AD/HD-subtypes, gender, age, intellectual functioning, medication, and sample size. Methods: Seventeen independent studies were located including 1395 children, adolescents, and young adults, in the age range of 6-27 years. A meta-analysis was conducted to assess the effect sizes for the scores on the word and the colour card as well as the interference score. Results: Children with AD/HD performed more poorly on all three dependent variables. The effect sizes for word reading (d = .49) and colour naming (d = .58) were larger and more homogeneous than the effect size for the interference score (d = .35). The method used to calculate the interference score strongly influenced the findings for this measure. When interference control was calculated as the difference between the score on the colour card minus the score on the colour-word card, no differences were found between AD/HD groups and normal control groups. Discussion: The Stroop Colour-Word Task, in standard form, does not provide strong evidence for a deficit in interference control in AD/HD. However, the Stroop Colour-Word Task may not be a valid measure of interference control in AD/HD and alternative methodologies may be needed to test this aspect of the inhibitory deficit model in AD/HD. © Association for Child Psychology Psychiatry, 2004

Deformed negative-parity excitations in 71 As

High-spin states in the neutron-deficient 71As nucleus have been studied using in-beam g -ray spectroscopic techniques combined with mass identification. A new decay sequence of negative parity has been assigned to 71As and previously known sequences have been extended to higher spin and excitation. The new sequence has been identified as originating from the proton f 7/2 extruder orbital, which approaches the Fermi surface at large prolate deformations. Comparisons of experimental B(M1)/B(E2) ratios to theoretical expectations support this interpretation

Odd-even staggering in the πg9/2vg9/2 band in 72Br

High-spin positive-parity states in 72Br have been studied using the 16O+58Ni reaction. The πg9/2vg9/2 decoupled band in 72Br has been observed up to ∼10 MeV excitation energy and the expected odd-even staggering has been delineated. A larger signature splitting is observed for this band in 72Br than in the same collective structures in the heavier 74,76,78Br. No signature inversion at low spin is observed for this band in 72Br, in contrast to the heavier isotopes, 74,76,78Br, in which signature inversion is observed below ∼10(Latin small letter h with stroke sign). The observations are in general agreement with theoretical models in this mass region which predict no signature inversion for nuclei with less than 39 protons and neutrons