236 research outputs found
The determination of selenium and tellurium in blister copper and copper concentrates
Selenium and tellurium do not occur to any great extent in Nature and they are seldom studied in any detail. However, a general understanding of their properties, both physical and chemical, is essential in an investigation of their analytical determination. A general account may be found in many of the text-books on inorganic chemistry, but the following resumè has been included in this dissertation for the sake of completeness
Coral bleaching following wintry weather
Extensive coral bleaching Occurred intertidally in early August 2003 in the Capricorn Bunker group (Wistari Reef, Heron and One Tree Islands; Southern Great Barrier Reef). The affected intertidal coral had been exposed to unusually cold (minimum = 13.3degreesC; wet bulb temperature = 9degreesC) and dry winds (44% relative humidity) for 2 d during predawn low tides. Coral bleached in the upper 10 cm of their branches and had less than 0.2 x 10(6) cell cm(-2) as compared with over 2.5 x 10(6), Cell cm(-2) in nonbleached areas. Dark-adapted quantum yields did not differ between symbionts in bleached and nonbleached areas. Exposing symbionts to light, however, led to greater quenching of Photosystem 11 in symbionts in the bleached coral. Bleached areas of the affected colonies had died by September 2003, with areas that were essentially covered by more than 80% living coral decreasing to less than 10% visible living coral cover. By January 2004, coral began to recover, principally from areas of colonies that were not exposed during low tide (i.e., from below dead, upper regions). These data highlight the importance of understanding local weather patterns as well as the effects of longer term trends in global climate
Tsunami observations by coastal ocean radar
When tsunami waves propagate across the open ocean, they are steered by the Coriolis effect and refraction due to gentle gradients in the bathymetry on scales longer than the wavelength. When the wave encounters steep gradients at the edges of continental shelves and at the coast, the wave becomes nonlinear and conservation of momentum produces squirts of surface current at the head of submerged canyons and in coastal bays. High frequency (HF) coastal ocean
radar is well conditioned to observe the surface current bursts at the edge of the continental shelf and give a warning of 40 minutes to 2 hours when the shelf is 50
to 200km wide. The period of tsunami waves is invariant over changes in bathymetry and is in the range 2 to 30 minutes. Wavelengths for tsunamis (in 500 to 3000m depth) are in the range 8.5 to over 200 km, and on a shelf where the depth is about 50m (as in the Great Barrier Reef (GBR)) the wavelengths are in the range 2.5 to 30 km. In the use of HF radar technology, there is a trade-off between the precision of surface current speed measurements and time
resolution. It is shown that the phased array HF ocean surface radar being deployed in the GBR and operating in a routine way for mapping surface currents, can resolve surface current squirts from tsunamis in the wave period
range 20 to 30 minutes and in the wavelength range greater than about 6 km. An advantage in signal-to-noise ratio can be obtained from the prior knowledge of the spatial pattern of the squirts at the edge of the continental shelf, and it is estimated that, with this analysis, the time resolution of the GBR radar may be reduced to about 2.5 minutes, which corresponds to a capability to detect tsunamis at the shelf edge in the period range 5 to 30 minutes. It is estimated that the lower limit of squirt velocity detection at the shelf edge would correspond to a tsunami with water elevation of about 2.5 cm in the open ocean. This means
that the GBR HF radar is well conditioned for use as a monitor of small, as well as larger, tsunamis and has the potential to contribute to the understanding of tsunami genesis research
Identifying oceanic thermal anomalies in the coral triangle region
Mass coral bleaching has historically been linked to episodes of thermal stress. While locationspecific time-series data have been examined, the oceanic thermal anomalies that underlie broad-scale thermal stress events are apparently unstudied quantitatively in terms of their spatial extent, temporal development, and intensity. Knowledge of the spatial and temporal parameters that characterise anomalies can be useful in understanding how bleaching-level stress develops, providing context for and a basis for modelling of future events. Here we examine historical satellite sea-surface temperature (SST) data with the goal of identifying and characterising oceanic anomalies in the Coral Triangle region. This region is of interest because it is influenced by the Indian and Pacific Oceans and is the centre of coral ecosystem diversity and significant coral reef conservation efforts. Oceanic anomalies are defined here using the HotSpot metric, which is the positive variation in temperature above the maximum of the monthly mean climatology values. This metric describes thermal stress that has been linked to coral bleaching episodes. It is proposed that the method for identifying oceanic anomalies described here be applied to datasets of varying spatial resolutions to evaluate if, and how, the characterisations are resolution-dependent. If these anomalies can be comparably identified and characterised at a coarser spatial resolution, this could open the way to examining the likely impact of oceanic thermal anomalies further back in time using historical datasets or in the future using climate models, both of which are available only at lower spatial and temporal resolutions
The relentless march of mass coral bleaching: a global perspective of changing heat stress
The global coral bleaching event of 2014-2017 resulted from the latest in a series of heat stress events that have increased in intensity. We assessed global- and basin-scale variations in sea surface temperature-based heat stress products for 1985-2017 to provide the context for how heat stress during 2014-2017 compared with the past 3 decades. Previously, undefined "Heat Stress Year" periods (used to describe interannual variation in heat stress) were identified for the Northern and Southern Hemispheres, in which heat stress peaks during or shortly after the boreal and austral summers, respectively. The proportion of reef pixels experiencing bleaching-level heat stress increased through the record, accelerating during the last decade. This increase in accumulated heat stress at a bleaching level is a result of longer stress events rather than an increase in the peak stress intensity. Thresholds of heat stress extent for the three tropical ocean basins were established to designate "global" events, and a Global Bleaching Index was defined that relates heat stress extent to that observed in 1998. Notably, during the 2014-2017 global bleaching event, more than three times as many reefs were exposed to bleaching-level heat stress as in the 1998 global bleaching
Arthroscopic suprascapular neurectomy for the management of severe shoulder pain.
Hypothesis:
Arthroscopic suprascapular neurectomy is an effective option in the management of patients with severe shoulder pain.
Materials and methods:
We describe and evaluate a technique of suprascapular neurectomy, performed arthroscopically for the treatment of severe shoulder pain in 20 patients (17 with a rotator cuff arthropathy, two with glenohumeral arthritis and one with a rotator cuff deficient shoulder following an unsuccessful arthrodesis). Post-operative pain relief was measured using a new pain scoring system, which combined an assessment of the frequency and severity of pain experienced at night, at rest, with activities and any change in analgesic consumption.
Results:
At an average follow-up of 29 months, 75% of our patients reported good to excellent pain relief scores, 85% reported less night pain, 90% had less rest pain, 70% reported less pain on movement, whilst 75% reported less consumption of pain medication. There were no surgical complications.
Discussion:
Suprascapular neurectomy performed arthroscopically provides an additional surgical option in the management of pain in patients with cuff tear arthropathy and in other selected patients with no functioning rotator cuff. The pain scoring system introduced in this article provides a more comprehensive assessment of shoulder pain than existing pain scores.
Conclusion:
We conclude that arthroscopic suprascapular neurectomy introduces an additional effective option in the management of pain in patients with these pathologies. Level of evidence: Level 4; Retrospective case series, no control group
Climate refugia on the Great Barrier Reef fail when global warming exceeds 3°C.
This is the final version. Available from Wiley via the DOI in this record. DATA AVAILABILITY STATEMENT:
These data are available through Zenodo as the data were used in a previous paper (McWhorter et al., 2021), https://zenodo.org/record/5534875#.YnvfQOjMKUm. The code in this study is available by request.Increases in the magnitude, frequency, and duration of warm seawater temperatures are causing mass coral mortality events across the globe. Although, even during the most extensive bleaching events, some reefs escape exposure to severe stress, constituting potential refugia. Here, we identify present-day climate refugia on the Great Barrier Reef (GBR) and project their persistence into the future. To do this, we apply semi-dynamic downscaling to an ensemble of climate projections released for the IPCC's recent sixth Assessment Report. We find that GBR locations experiencing the least thermal stress over the past 20 years have done so because of their oceanographic circumstance, which implies that longer-term persistence of climate refugia is feasible. Specifically, tidal and wind mixing of warm water away from the sea surface appears to provide relief from warming. However, on average this relative advantage only persists until global warming exceeds ~3°C.UKRICooperative Institute for Satellite Earth System Studie
S2P3-R v2.0: computationally efficient modelling of shelf seas on regional to global scales
This is the final version. Available on open access from the European Geosciences Union via the DOI in this recordCode availability:
S2P3Rv2.0 is available on GitHub: https://github.com/PaulHalloran/S2P3Rv2.0 (last access: 21 September 2021).
The release associated with this paper (https://github.com/PaulHalloran/S2P3Rv2.0/releases/tag/v1.0.1, last access: 21 September 2021) has been archived on Zenodo with the following DOI: https://doi.org/10.5281/zenodo.4147559 (Halloran, 2020a).
The readme file available on GitHub or via the DOI link provides step-by-step instructions for how to install, set up and run the model, and it provides a basic script for analysing the model output. At the bottom of the readme, a worked example is provided to help the user go through the full process from generating model forcing files, running the model and displaying the output with some example data.Data availability:
The model minus satellite SST data from the global (65∘ S–65∘ N) simulation averaged between 2006 and 2016, from which the global validation has been undertaken in this paper, is archived as NetCDF and csv files to allow potential users to undertake bespoke assessment of the model http://doi.org/10.5281/zenodo.4018815 (Halloran, 2020b).The marine impacts of climate change on our societies will be largely felt through coastal waters and shelf seas. These impacts involve sectors as diverse as tourism, fisheries and energy production. Projections of future marine climate change come from global models. Modelling at the global scale is required to capture the feedbacks and large-scale transport of physical properties such as heat, which occur within the climate system, but global models currently cannot provide detail in the shelf seas. Version 2 of the regional implementation of the Shelf Sea Physics and Primary Production (S2P3-R v2.0) model bridges the gap between global projections and local shelf-sea impacts. S2P3-R v2.0 is a highly simplified coastal shelf model, computationally efficient enough to be run across the shelf seas of the whole globe. Despite the simplified nature of the model, it can display regional skill comparable to state-of-the-art models, and at the scale of the global (excluding high latitudes) shelf seas it can explain >50 % of the interannual sea surface temperature (SST) variability in ∼60 % of grid cells and >80 % of interannual variability in ∼20 % of grid cells. The model can be run at any resolution for which the input data can be supplied, without expert technical knowledge, and using a modest off-the-shelf computer. The accessibility of S2P3-R v2.0 places it within reach of an array of coastal managers and policy makers, allowing it to be run routinely once set up and evaluated for a region under expert guidance. The computational efficiency and relative scientific simplicity of the tool make it ideally suited to educational applications. S2P3-R v2.0 is set up to be driven directly with output from reanalysis products or daily atmospheric output from climate models such as those which contribute to the sixth phase of the Climate Model Intercomparison Project, making it a valuable tool for semi-dynamical downscaling of climate projections. The updates introduced into version 2.0 of this model are primarily focused around the ability to geographical relocate the model, model usability and speed but also scientific improvements. The value of this model comes from its computational efficiency, which necessitates simplicity. This simplicity leads to several limitations, which are discussed in the context of evaluation at regional and global scales.Natural Environment Research Council (NERC)European Union Horizon 2020NOA
The importance of 1.5°C warming for the Great Barrier Reef
This is the final version. Available on open access from Wiley via the DOI in this recordData and code availability. The data that support the findings of this study are openly available in Zenodo at https://doi.org/10.5281/zenodo.5534875Tropical coral reefs are among the most sensitive ecosystems to climate change and will benefit from the more ambitious aims of the United Nations Framework Convention on Climate Change’s Paris Agreement, which proposed to limit global warming to 1.5° rather than 2°C above pre-industrial levels. Only in the latest IPCC focussed assessment, the Coupled Model Intercomparison Project phase 6 (CMIP6), have climate models been used to investigate the 1.5° warming scenario directly. Here, we combine the most recent model updates from CMIP6 with a semi-dynamic downscaling to evaluate the difference between the 1.5°C and 2°C global warming targets on coral thermal stress metrics for the Great Barrier Reef. By ~2080, severe bleaching events are expected to occur annually under intensifying emissions (Shared Socioeconomic Pathway SSP5-8.5). Adherence to 2° warming (SSP1-2.6) halves this frequency but the main benefit of confining warming to 1.5° (SSP1-1.9) is that bleaching events are reduced further to 3 events per decade. Attaining low emissions of 1.5° is also paramount to prevent the mean magnitude of thermal stress from stabilizing close to a critical thermal threshold (8 DHW). Thermal stress under the more pessimistic pathways SSP3-7.0 and SSP5-8.5 is 3- to 4-fold higher than present day, with grave implications for future reef ecosystem health. As global warming continues, our projections also indicate more regional warming in the central and southern Great Barrier Reef than the far north and northern Great Barrier Reef.QUEX InstituteNatural Environment Research Council (NERC)Australian Research Council (ARC)NOA
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