100 research outputs found
Rockall and the limits of national jurisdiction of the UK : Part 2
No full textPart 1 of this article, published in the July issue of Marine Policy, contained the first in a four-section examination of the Rockall question. Section I presented a survey of the law governing the delimitation of the continental shelf, the EEZ, and exclusive fishing zones, thus providing a background for sections II-IV, which constitute Part 2. In this Part, the author examines the geography and geology of the Rockall sector and the claims made by the UK, Ireland and Denmark, before drawing conclusions from the whole article.
Megafaunal distribution and biodiversity in a heterogeneous landscape: the iceberg scoured Rockall Bank, NE Atlantic
No full textSpecies distributions are influenced by spatial structure in environmental factors, but the scales at which these dependencies occur and the effect of habitat patch diversity, connectivity and spatial arrangement have rarely been investigated in deep-sea settings. In this study, spatially-limited photographic transects collected from Rockall Bank, Northeast Atlantic, were combined with sidescan and multibeam sonar maps to model spatial patterns in species distribution and biodiversity. Sediment interpretation maps were created and canonical ordination techniques were used to examine relationships between fine-scale sediment characteristics extracted from the digital stills as well as landscape metrics describing the patch mosaic structure of the surrounding areas. Fine-scale sediment characteristics explained 45.1% and 63.8% of the variation in species composition and biodiversity (H′) respectively. This survey effectively captured variation in species distribution resulting from iceberg ploughmarks, occurring at a scale of < 50 m which would normally go undetected by traditional ship-based studies. Our study suggests that fine-scale environmental information is required to capture the spatial heterogeneity of complex seafloor areas in sufficient detail to model species distributions and biodiversity
Geotechnical characterization of sediments from the Rockall Bank Slide Complex
No full textThe main reason for this research is the possibility of landslides that could trigger a tsunami together with general interest from the oil and gas industry. The goal of this thesis is to find out what the geotechnical properties are of the 7 different locations at the eastern flank of the Rockall bank which is located to the west of Ireland and to the south of Iceland in the Atlantic Ocean. The possible effects of these properties on slope stability are then discussed. This will be done by geotechnically testing the sediments in a laboratory. All standards used during testing can be seen in chapter 3.1.1. The gravity cores used for this research were found to contain parts of sediment that were quite intact together with other more disturbed parts of sediment. The sediments that were found could be classified as silty SAND, clayey SILTS and silty CLAYS which are calcareous to very higly calcareous,from medium to very high plasticity, low to medium-organic and have extremely low to very low undrained shear strengths. Grain size distribtions were found to be gap-graded and well graded and the the sediments were found to be inactive to normal soil based on the Atterberg limits.Geotechnical properties such as gravimetric water contents are found to range from 0.20 to 1.18, the volumetric water contents range from 0.50 to 0.80, a liquidity index from 0 to 3, specific gravities from 2.72 to 2.79, void ratios from 1 to 3, bulk volumetric weights from 14 kN/m3 to 18 kN/m3, dry volumetric weights from 7 kN/m3 to 13 kN/m3, clay contents from 10% to 60%, a silt content of 15% to 60%, a sand content from 8% to 70%, calcite contents from 17.3% to 57.4%, organic matter contents from 2.6% to 9.0%, liquid limits from 0.40 to 0.82 and plastic limits from 0.23 to 0.49. The undrained shear strength for the original and remoulded sediments from the UU DS tests is found to range from 2 kPa to 8 kPa and from 0 kPa to 4 kPa. The undrained shear strengths from original and remoulded sediments from the fall cone test range from 4 kPa to 33 kPa and from 0 kPa to 4 kPa. The undrained shear strengths from the original pocket vane tests range from 5 kPa to 22 kPa. The sensitivities of the sediments measured by the fall cone tests are found to range from 2 to 28 and the sensitivities obtained by direct shear testing are found to range from 0.5 to 4.Based on these undrained shear strengths a failure mechanism similar to that of a direct shear test is found to be more likely on the undisturbed sediments and a failure mechanism like that of a fall cone test is found to be more likely for the remoulded sediments. The non-phyllosilicate minerals that are present are Smectite, Illite, Muscovite, Chlorite and Kaolinite. The phyllosilicate minerals that are present are Quartz, Alkali feldspar, Plagioclase, Calcite, Ankerite, Siderite, Anatase, Rutile, Hematite, Pyrite, Halite and Apatite. This mineral composition can be logically explained by their possible weathering paths and indicates that the possible parent material is Monzogranite type 2 also called Muscovite-metagranite. Magnetic particles are found to be present in all sediments in small amounts that are not quantified. Similar sediments are found to be present from the research of ( Georgiopoulou, Krastel et al., 2019). This confirms the presence of turbidty deposits. These turbidity deposits are indicated to be present at all sites based on the fininng-upward sequences found. Also the presence of lighter interglacial and darker glacial sediments is found. It was also found that the likley reasons for slope instability on the eastern side of the Rockall Bank are the much higher water contents and clay contents of the sediments present compared to the sediments found on eastern side of the Rockall through.The risk of liquefaction upon distrubance is found at sites 1736, 1672, 1988, 1959 and 1604. No risk of liquefaction upon disturbance is found at site 688. The organic matter content is considered to not have an effect on strenght parameters of the sediments present whereas an increase in the amount of foraminifera shells could increase stability of the sediments. Only differential compaction is not found to be a probable factor in lanslide initiation. A long term instability could arise from weathering of Smectite minerals. Erosion could cause slope instability due to sediments with widely varying grain size distributions. The high water content sediments that are present are prone to liquefaction due a disturbance possibly from seismic activity. It is recommended that in future studies a quantification of the marine shell fraction is made. Also a microscope spectrometry is recommended to be done on the sand fraction together with an X-ray diffraction on the <63µm fraction. The most important recommendation is to do a slope stability analysis on the RBSC using the geotechnical properties presented in this thesis.Applied Earth Science
A benign technique for mapping coral distribution in the closed areas of the Rockall Plateau
No full textNo abstracts are to be cited without prior reference to the author. Cold-water corals (Lophelia spp.) occur throughout the north east Atlantic and have been identified in bottom trawl records occurring in abundant patches on the Rockall Plateau. As a result, several large areas have been closed to bottom trawling to protect this habitat. However, our understanding of the distribution of deep-water coral remains poor. A non-destructive visual survey method using a deep towed camera system was deployed to collect data on the occurrence of Lophelia spp. around the closed areas at Rockall. The species distribution model (SDM) Random Forest was used to predict the potential spatial distribution of Lophelia spp. and infer the environmental requirements of the species. The model used coral presence-absence data from the towed camera survey and the trawl record data. Performance was evaluated by partitioning the data into ‘training’ and ‘testing’ data. The model showed good performance based on Cohen’s Kappa and the area under the curve of the receiver operator characteristic curve. Depth, aspect, and slope were the most important environmental variables for predicting the presence of Lophelia spp. The predictive map suggests that potential Lophelia habitat occurs most abundantly along the west of the plateau in a depth range of 200 – 400 m
Does dietary nitrate supplementation improve performance in cardiopulmonary exercise testing and post-operative recovery in patients with colorectal cancer? A randomised controlled trial
No full textMajor surgery generates a stress response which increases oxygen demand and consumption post-operatively. Patients with low cardiopulmonary reserve may not be able to meet the increased oxygen demand and are at risk of increased morbidity. Dietary nitrate reduces the amount of oxygen required to perform a set amount of exercise and enhances exercise tolerance and performance in athletes by improving oxygen utilisation.
Cardiopulmonary exercise testing (CPX) is an established method of assessing patients’ cardiopulmonary reserve prior to surgery. The anaerobic threshold (AT) is the oxygen uptake at which anaerobic metabolism supplements aerobic metabolism; is calculated during CPX and can predict short and long term outcomes after surgery and postoperative complications.
We conducted a single centre, randomised, double-blind, placebo controlled trial to determine if dietary organic nitrate supplementation with beetroot juice (BRJ) improves pre-operative performance in CPX in patients with colorectal cancer (CRC). Eligible patients were adults undergoing elective laparoscopic resection for CRC. Patients were randomised to receive BRJ or nitrate-depleted BRJ (Placebo). Initial CPX was performed to a standard ramped incremental exercise protocol. Patients then received BRJ or placebo every day for 7 days followed by a second CPX. The primary outcome measure was the change in AT.
There was a statistically significant increase in the mean AT in the nitrate group (+0.706, 95% CI 0.130 to 1.281; p=0.018) but not in the placebo group. There was a significantly lower length of stay in nitrates group. There was no significant difference in rate of complications between the two groups.
Just 7 days of dietary nitrate supplementation results in a significant improvement in oxygen utilisation in an elderly population with colorectal cancer. This is a novel finding and this study is the first in patients undergoing surgery. This trial provides evidence that dietary nitrate supplementation is beneficial in a preoperative setting
Miocene paleoceanography at Rockall Plateau site 982
No full textThe Miocene Epoch contains two juxtaposed end-member climate states beginning with the Miocene Climate Optimum (MCO) (17-14.8 Ma), the most recent interval of ice-free or near ice-free conditions, and ending with the abrupt establishment of a permanent East Antarctic Ice Sheet during the Middle Miocene Climate Transition (MMCT) (14.8-12.8 Ma). The North Atlantic plays an important role in global ocean water circulation and Earth’s climate and yet, relatively few sea surface temperature (SSTs) records have been generated for the Miocene in the subpolar North Atlantic. Biomarker (UK’37, TEX86) SST records at subpolar Ocean Drilling Program (ODP) Site 982 (57.5°N) yield SST estimates which indicate that surface waters in the high latitudes remained warm (>20°C) until ⁓8 Ma when 4°C cooling occurred. In contrast, foraminiferal-based estimates from subtropical and transitional DSDP Sites 563, 558, and 608 (33.6-42.8°N) indicate that the largest cooling (4°C) occurred during the MMCT between 14.8-12.8 Ma, recording little to no cooling after 8 Ma. We analyzed planktonic (G. bulloides and G. praebulloides) and benthic foraminifera (P. wuellerstorfi, S. tenuicarinata) from the Early to Late Miocene (20 to 4.5 Ma) at Site 982 for δ 18O and δ 13C to evaluate SSTs, thermocline and deepwater evolutions, and to test the biomarker-based reconstructions of SSTs in the subpolar North Atlantic. Our results show that planktonic foraminifera from Site 982 record a 1.45‰ increase in δ18O values between 15-13.8 Ma, reaching modern values by 11.75 Ma (1.55‰ Modern for G. bulloides). Accounting for ice volume difference using Miller et al. (2020) ice volume estimates, SSTs varied between 15-17°C during the MCO and cooled to 11-13°C with the MMCT, in line with the modern seasonal SSTs in the region (Modern winter 9°C, Modern Summer 13°C). Our benthic foraminiferal δ18O values record a 0.5‰ increase reflecting a 2-3°C deep-water cooling following the MCO. In contrast, the UK’37 and TEX86 based SSTs recorded modest cooling (22°C) through the MCO and subsequent Antarctic Ice sheet growth. Resolving disparities between SST proxies is important because they present two different and possibly incompatible scenarios. The biomarker-based estimates require an asymmetry in cooling with the subpolar North Atlantic maintaining subtropical conditions while the southern subpolar region cooled dramatically. We favor the stable isotope SST reconstruction because 1) the cooling coincides with CO2 decreases and the growth of a large ice sheet on Antarctica and 2) the resulting SST estimates following the MCO are similar to the modern seasonal SSTs over Rockall Plateau (10-13°C) and supports the preferred temperature ranges for the faunal species found in that interval.M.S.Includes bibliographical reference
Cancer cell-derived extracellular vesicles activate hepatic stellate cells in colorectal cancer
No full textColorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths worldwide, primarily due to the development of metastatic disease. The liver is the most frequently affected site. The metastatic cascade relies on a complex interaction between the immune system, tumor, and distant organs. Communication between the tumor and the metastatic site can be mediated by tumor-derived extracellular vesicles (EVs) and their cargo. The mechanisms underlying this process are starting to be understood through research that has rapidly expanded over the past 15 years. One crucial aspect is the remodeling of the microenvironment at the site of metastasis, which is essential for the formation of a premetastatic niche and the subsequent establishment of metastatic deposits. In the evaluated study, the authors use cellular experiments and a mouse model to investigate how tumour derived extracellular vesicles and their microRNA contents interact with hepatic stellate cells (HSCs). They demonstrate how this may lead to remodelling of the microenvironment and the formation of colorectal liver metastasis using their experimental model. In this mini review, we examine the current evidence surrounding tumour derived EVs and their effect on the tumour microenvironment to highlight potential areas for future research in CRC and other malignancies.</p
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