Metamorphism in the lower Witwatersrand Supergroup exposed in the Vredefort Dome has previously been proposed to be related to elevated heat flow linked to the 2.06 Ga Bushveld magmatic event; however, there are no unambiguous chronological data to confirm this timing. Microtextural and mineral compositional analysis of a garnet-bearing metapelite in the northwestern collar of the Vredefort Dome suggests at least two metamorphic events with distinctly different P-T conditions preceding the Dome-forming meteorite impact at 2.02 Ga. THERMOCALC mineral equilibrium calculations yield P-T conditions of 500°C, 3.1 kbar for the M1 mineral assemblage garnet1-plagioclase-muscovite-biotite-chlorite-ilmenite. Thin, discontinuous, garnet2 overgrowths on the garnet1 porphyroblasts define a subsequent, M2, event with P-T conditions of 530°C, 5 kbar. Garnet Sm-Nd chronology yields an isochron age of 2 796.0 ± 1.5 Ma, indicating an early Ventersdorp (Klipriviersberg) timing of M1 metamorphism. Although the M2 garnet overgrowths are volumetrically too small to date, the calculated M2 pressure is consistent with the predicted overburden thickness above the lower Witwatersrand Supergroup during emplacement of the Bushveld Complex. While elevated, the M2 apparent geotherm (30°C/km) is significantly lower than the M1 apparent geotherm (46°C/km); however, thermal modelling suggests both events benefitted from local perturbations caused by contemporaneous sill emplacement. Our results thus show that the initial garnet-forming, mid-amphibolite facies metamorphism in the collar of the Vredefort Dome is not related to the emplacement of the Bushveld Complex, but rather to the early stages of magmatism associated with the Ventersdorp Large Igneous Province (LIP). Nonetheless, elevated heat flow associated with the Bushveld LIP also reached comparable amphibolite facies conditions.

Abstract Garnet Lu–Hf and Sm–Nd ages from the Shetland Caledonides provide evidence of a polyorogenic history as follows: (1) c. 1050 Ma Grenvillian reworking of Neoarchaean basement; (2) c. 910 Ma Renlandian metamorphism of the Westing Group; (3) c. 622–606 Ma metamorphism of the Walls Metamorphic Series but of uncertain significance because the eastern margin of Laurentia is thought to have been in extension at that time; (4) Grampian I ophiolite obduction at c. 491 Ma followed by crustal thickening and metamorphism between c. 485 and c. 466 Ma; (5) Grampian II metamorphism between c. 458 and c. 442 Ma that appears to have been focused in areas where pre-existing foliations were gently inclined and thus may have been relatively easily reworked; (6) Scandian metamorphism at c. 430 Ma, although the paucity of these ages suggests that much of Shetland did not attain temperatures for garnet growth. There is no significant difference in the timing of Caledonian orogenic events either side of the Walls Boundary Fault, although this need not preclude linkage with the Great Glen Fault. However, the incompatibility of Ediacaran events either side of the Walls Boundary Fault may indicate significant lateral displacement and requires further investigation.

This paper presents a novel approach to masonry construction: utilising cooperating robots to construct complex doubly-curved vault geometries while eliminating the need for falseor formwork. An integrated design method that was developed, which takes into account both robotic and structural constraints and includes the following steps: (1) the overall design volume is defined based on the robots’ position, reach, and collision constraints; (2) a form-finding approach using Airy’s stress function is used to generate the target geometry; (3) the geometry is tessellated into a herringbone brick pattern; (4) the robotic construction sequence is defined based on stability and reachability constraints. Parallel to the development of the design methodology, the paper presents the physical prototyping and implementation of the robotic assembly process. The fabrication process uses a cooperative assembly technique in which robots alternate between placement and support to first build a stable central arch. Subsequently, the construction is continued individually by the robots building out from the central arch following an interlocking herringbone brick sequence. This methodology is implemented in a full-scale vault (3.6m x 6.5m x 2.2m) structure consisting of 338 glass bricks, built using two large-scale industrial robotic arms.

The purpose of this study is to assess the feasibility and efficacy of autologous bioprinted skin in the treatment of full-thickness porcine wounds. We hypothesize that bioprinted skin constructs will improve wound healing by modulating inflammation, skin remodeling, and epidermal maturation. Porcine keratinocytes, fibroblasts, pre-adipocytes, and endothelial cells were isolated, expanded, suspended in bioink, and bioprinted to form a biomimetic tri-layer skin construct. 5x5cm excisional full-thickness wounds were then treated with bioprinted skin from autologous or allogeneic cells, skin autograft or allograft, hydrogel, or left without treatment. Digital planimetry of photographs taken over 28 days demonstrated improved wound closure in autologous bioprinted skin treated wounds. Histological analysis confirmed these results and showed improved epidermal maturity, less fibrosis, and more normal collagen organization in the bioprinted autologous skin group. Hydrogel and skin allograft groups had increased total wound serum proteins and proteolytic activity, with an associated increase in inflammatory and proteolytic gene expression compared to the bioprinted autograft. These findings suggest that treatment of full-thickness porcine wounds with hydrogel generates inflammatory wound healing and protease activity. Alternatively, bioprinted constructs composed of autologous skin cells embedded in hydrogel induce healthy, pro-remodeling protease activity, resulting in normal wound healing. Taken together, our results suggest that bioprinted autologous skin rapidly integrates into the wound to support skin regeneration and confirms the feasibility of skin bioprinting technology for clinical treatment of full-thickness wounds in human patients.

Abstract The presence of mélange at the subduction interface influences numerous geochemical and geophysical processes. However, the relationship between the timescales of mélange development, deformation, and resultant mass transport is poorly understood. Here, we use Sm‐Nd garnet geochronology to elucidate the timing of peak metamorphism for five garnet amphibolite tectonic blocks from the amphibolite‐facies mélange zone of the Catalina Schist (Santa Catalina Island, CA). Ages range from 108 to 116 Ma and do not appear to correlate with the peak metamorphic temperature recorded by each block (between 640 and 740°C). The lack of correlation between age and peak temperature favors the tectonic mixing model previously proposed for the unit. These ages overlap with previous estimates of 111–114 Ma for peak metamorphism of the mélange zone but are predominately younger than an estimate for the structurally lower coherent amphibolite unit of ca. 115 Ma. White mica 40Ar/39Ar ages from previous studies suggest that the units cooled asynchronously to 400–425°C by 106 to 97 Ma at rates between 18 and 43°C/Ma. Collectively, these results demonstrate that mélange formation occurred over at least 8 Myr from 116 to 108 Ma and was followed by cooling. The structural and chronologic relationship between the mélange zone and underlying lower‐grade units indicates that the cooling occurred in conjunction with an underplating event between 109 and 108 Ma. The age discrepancy between the mélange zone and the underlying coherent amphibolite unit may indicate that the two units were juxtaposed either during or after the underplating event.

Tidal stream energy has the potential to contribute to global renewable energy generation, but this remains largely untapped. Technical developments have helped create a nascent industry with several pre-commercial installations. However, planned projects experience a cautious investment climate due to perceived risk of failure, and maintenance and repair cost. This paper reviews 58 tidal stream energy deployments between 2003 and August 2020. The analysis reviews commonalities, success and engineering issues, to inform current and future projects. The work classifies each deployment by type, rated power, number of devices, grid connection and foundation. In each case, project status and (if appropriate) failure mode is identified. Failure modes are compared to deployment classification to identify potential relationships. Most deployments were of horizontal axis turbines. The majority (54%) of deployments performed well. 18% failed, 14% were withdrawn from service, and 14% generated less power than planned. The most common failure cause was blade failure, followed by generator and monitoring failures. Ducted devices and devices in high velocity locations were more likely to fail, suggesting that flow velocity is a key factor. Most blade failures were attributed to underestimation of loads during design. Floating deployments were less likely to fail than fixed deployments, but more likely to be curtailed. Off-grid and grid connected deployments showed similar failure rates, suggesting sector immaturity. Tidal stream energy has accumulated around 1.4 million operating hours. Analysis shows a falling empirical failure rate, and likelihood of failure similar to that experienced by the wind industry at a similar stage. This work will be useful for project planners, developers and technology companies and investors in de-risking future project efforts.

Our view of the interstellar medium of the Milky Way and the universe beyond is affected by the structure of the local environment in the Solar neighborhood. Here, we present the discovery of a thirty-degree long arc of ultraviolet emission with a thickness of only a few arcminutes: the Ursa Major Arc. It consists of several arclets seen in the near- and far-ultraviolet bands of the GALEX satellite. A two-degree section of the arc was first detected in the H{\alpha} optical spectral line in 1997; additional sections were seen in the optical by the team of amateur astronomers included in this work. This direction of the sky is known for very low hydrogen column density and dust extinction; many deep fields for extra-galactic and cosmological investigations lie in this direction. Diffuse ultraviolet and optical interstellar emission are often attributed to scattering of light by interstellar dust. The lack of correlation between the Ursa Major Arc and thermal dust emission observed with the Planck satellite, however, suggests that other emission mechanisms must be at play. We discuss the origin of the Ursa Major Arc as the result of an interstellar shock in the Solar neighborhood.

Tidal stream energy has great potential to reduce the greenhouse gas emissions of electricity supply, but development has been slow, in part due to high costs and challenging engineering required to operate in the marine environment. Floating support structures may be able to help reduce these costs. A laboratory study comparing the performance of a turbine mounted on fixed and floating support structures was used to investigate this potential. Realistic flow and wave cases were established from two installation sites. The turbine was found to generate greater power when mounted on a floating structure across all wave and flow cases, and the support structure experienced less strain. In both cases, the ability of the floating structure to move in response to wave action is believed to be the key factor. Floating support structures are not without challenges, but may offer a route to lower cost tidal stream turbine installations.

The large, faint supernova remnant (SNR) G70.0-21.5 is believed to be the result of a Type Ia supernova some 90,000 yr ago at a distance of similar to 1 kpc based on the Gaia proper motion and parallax of an unusual white dwarf. We have obtained narrow passband optical images and high-resolution spectroscopy to determine shock speeds of 70 to 110 km s(-1). The shock itself is unusual in that the sharp H alpha filaments arise from a very thin postshock zone where preshock neutral atoms are rapidly excited and ionized. Combining the shock speed with the remnant's estimated age, distance, and diameter, we investigate the SNR evolution in the post-Sedov phase. One-dimensional models that ignore such factors as magnetic fields, cosmic rays, and thermal conduction are marginally consistent with the observations.

We were pleased that the first national guidelines for paediatric Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN) were published in your journal last year1 . They highlighted the higher rate of infectious triggers in children compared to adults. This message is especially important for us, as author SW's son had SJS/TEN triggered by Mycoplasma pneumoniae, which accounts for up to 50% of infectious causes. SW experienced first-hand the frustration of aetiological uncertainty in this disease. Accurate diagnosis of Mycoplasma-induced SJS/TEN is important as it allows for continuation of simple analgesia (otherwise implicated as a possible trigger), possible avoidance of further drug allergy testing (which can be inconclusive), focused treatment of Mycoplasma with antibiotics, and management of recurrence risk.

Our view of the interstellar medium of the Milky Way and the universe beyond is affected by the structure of the local environment in the solar neighborhood. We present the discovery of a 30-degree-long arc of ultraviolet emission with a thickness of only a few arcminutes: the Ursa Major arc. This consists of several arclets seen in the near- and far-ultraviolet bands of the GALEX satellite. A two degree section of the arc was first detected in the H α optical spectral line in 1997; additional sections were seen in the optical by the team of amateur astronomers included in this work. This direction of the sky is known for very low hydrogen column density and dust extinction; many deep fields for extragalactic and cosmological investigations lie in this direction. Diffuse ultraviolet and optical interstellar emission are often attributed to scattering of light by interstellar dust. The lack of correlation between the Ursa Major arc and thermal dust emission observed with the Planck satellite, however, suggests that other emission mechanisms must be at play. We discuss the origin of the Ursa Major arc as the result of an interstellar shock in the solar neighborhood.

Imagery training is practiced with the goal of improving consistency of performance under pressure and to maximize skill execution. A recent model for advanced imagery training incorporates seven areas into the protocol to make it more realistic and vivid for athletes. These include Physical, Environment, Task, Timing, Learning, Emotion, and Perspective (PETTLEP). PURPOSE: To investigate the effect of a PETTLEP-based imagery script on college shot putter performance as measured by peak force (PF), release angle (RA), release height (RH), release velocity (RV), and distance thrown (DT). METHODS: Ten NCAA shot putters (n=5 females & n=5 males) participated in this study. Each participant created a personal imagery script with personal cues. Imagery was conducted five days per week for three weeks. A pre- and posttest design was used to evaluate the efficacy of PETTLEP-based imagery. Data was recorded using advanced force plate technology, biomechanical sensors, and infrared camera equipment and performance variables recorded included peak force, release angle, height of release, and release velocity. RESULTS: While all dependent variables increased in value, results yielded no significant difference in pre- to posttest for PF (Pre: 969.50 ± 185.18N; Post: 1030.16 ± 201.37N, p > 0.05), RA (Pre:33.42 ± 4.62°; Post: 36.95 ± 8.08°, p > 0.05), RH (Pre: 2.00 ± 0.11m; Post: 36.95 ± 8.08m, p > 0.05), and RV (Pre:10.89 ± 0.97m/s; Post: 11.29 ± 0.79m/s, p > 0.05). However, a significant difference was found for DT (Pre: 12.49 ± 2.14m; Post: 11.29 ± 1.67m, p < 0.05). Additionally, release velocity significantly correlated with distance thrown in both the pre- and post-tests (r= .962 and r= .834 respectively). Findings from the pretest linear regression analysis support using the model for release angle, release height, release velocity, and peak force production as a predictor of distance thrown with a level of confidence (F (4,5) = 26.29, p< 0.001; R2 of .918). CONCLUSION: While these findings are encouraging, the PETTLEP-based imagery training model employed in the present study needs to be valuated further to determine its effectiveness for consistently enhancing athletic performance.