300 research outputs found
Cenozoic Contourites in the Eastern Great Australian Bight, Offshore Southern Australia: Implications For the Onset of the Leeuwin Current
Thermohaline oceanic currents influence global heat transfer, controlling local and global variations in climate, biodiversity, and the terrestrial biosphere. Paleoceanographic studies typically use biostratigraphic and geochemical proxies to reconstruct the dynamics of these currents in Earth's ancient oceans, although seismic reflection data have also been successfully employed, most commonly in the North Atlantic Ocean. Here we use 2D seismic reflection data from the Ceduna Sub-basin, Great Australian Bight, offshore southern Australia, to describe middle Eocene to Recent contourites deposited in an overall carbonate-dominated succession. These deposits comprise large (100 m wavelength by up to 50 m tall) bedforms and deep (10–90 m), wide (up to 3 km) erosional scours. The scours are particularly well developed at one specific stratigraphic level, defining moats that encircle middle Eocene shield volcanoes, which formed syndepositional bathymetric highs. We suggest that sediment erosion, transport, and deposition record middle Eocene initiation of the Leeuwin Current, one of the most important ocean currents in the southern hemisphere. Deepest seabed scouring occurs in the middle of the middle Eocene to Recent sequence, and may reflect middle Miocene waxing of the so-called “proto-Leeuwin Current,” possibly driven by changes in ocean circulation patterns caused by the Miocene Global Optimum. The results of this seismic reflection-based study are consistent with results derived from other paleoceanographic proxies, thereby highlighting the continued key role seismic reflection data have in understanding the occurrence, geographical distribution, and significance of ancient ocean currents
Leaky salt: Pipe trails record the history of cross‐evaporite fluid escape in the northern Levant Basin, Eastern Mediterranean
Despite salt being regarded as an extremely efficient, low‐permeability hydraulic seal, an increasing number of cross‐evaporite fluid escape features have been documented in salt‐bearing sedimentary basins. Because of this, it is clear that our understanding of how thick salt deposits impact fluid flow in sedimentary basins is incomplete. We here examine the causes and evolution of cross‐evaporite fluid escape in the northern Levant Basin, Eastern Mediterranean. High‐quality 3D seismic data offshore Lebanon image hundreds of supra‐salt fluid escape pipes distributed widely along the margin. The pipes consistently originate at the crest of prominent sub‐salt anticlines, where overlying salt is relatively thin. The fact the pipes crosscut the salt suggests that hydrofracturing occurred, permitting focused fluid flow. Sequential pipes from unique emission points are organized along trails that are several kilometres long, and which are progressively deformed due to basinward gravity gliding of salt and its overburden. Correlation of pipes in 12 trails suggests margin‐wide fluid escape started in the Late Pliocene/Early Pleistocene, coincident with a major phase of uplift of the Levant margin. We interpret that the consequent transfer of overpressure from the central basin area, in addition to gas exsolution from hydrocarbons already trapped in sub‐salt anticlines, triggered seal failure and cross‐evaporite fluid flow. We infer that other causes of fluid escape in the Eastern Mediterranean, such as subsurface pressure changes driven by sea‐level variations and salt deposition associated with the Messinian Salinity Crisis, played only a minor role in triggering cross‐evaporite fluid flow in the northern Levant Basin. Further phases of fluid escape are unique to each anticline and cannot be easily correlated across the margin. Therefore, despite a common initial cause, long‐term fluid escape proceeded according to structure‐specific characteristics, such as local dynamics of fluid migration and anticline geometry. Our work shows that the mechanisms triggering cross‐evaporite fluid flow in salt basins vary in time and space
Bisphosphonate nephrotoxicity
Bisphosphonates are valuable agents for the treatment of post-menopausal osteoporosis (PMO), hypercalcemia of malignancy, and osteolytic bone metastases. Oral bisphosphonates are used mainly to treat PMO and are not associated with significant nephrotoxicity. In contrast, nephrotoxicity is a significant potential limiting factor to the use of intravenous (IV) bisphosphonates, and the nephrotoxicity is both dose-dependent and infusion time-dependent. The two main IV bisphosphonates available to treat hypercalcemia of malignancy and osteolytic bone disease in the United States are zoledronate and pamidronate. Patterns of nephrotoxicity described with these agents include toxic acute tubular necrosis and collapsing focal segmental glomerulosclerosis, respectively. With both of these agents, severe nephrotoxicity can be largely avoided by stringent adherence to guidelines for monitoring serum creatinine prior to each treatment, temporarily withholding therapy in the setting of renal insufficiency, and adjusting doses in patients with pre-existing chronic kidney disease. In patients with PMO, zoledronate and pamidronate are associated with significantly less nephrotoxicity, which undoubtedly relates to the lower doses and longer dosing intervals employed for this indication. Ibandronate is approved in the US for treatment of PMO and in Europe for treatment of PMO and malignancy-associated bone disease. Available data suggest that ibandronate has a safe renal profile without evidence of nephrotoxicity, even in patients with abnormal baseline kidney function
A systematic review of patient reported factors associated with uptake and completion of cardiovascular lifestyle behaviour change
Background: Healthy lifestyles are an important facet of cardiovascular risk management. Unfortunately many individuals fail to engage with lifestyle change programmes. There are many factors that patients report as influencing their decisions about initiating lifestyle change. This is challenging for health care professionals who may lack the skills and time to address a broad range of barriers to lifestyle behaviour. Guidance on which factors to focus on during lifestyle consultations may assist healthcare professionals to hone their skills and knowledge leading to more productive patient interactions with ultimately better uptake of lifestyle behaviour change support. The aim of our study was to clarify which influences reported by patients predict uptake and completion of formal lifestyle change programmes. Methods: A systematic narrative review of quantitative observational studies reporting factors (influences) associated with uptake and completion of lifestyle behaviour change programmes. Quantitative observational studies involving patients at high risk of cardiovascular events were identified through electronic searching and screened against pre-defined selection criteria. Factors were extracted and organised into an existing qualitative framework. Results: 374 factors were extracted from 32 studies. Factors most consistently associated with uptake of lifestyle change related to support from family and friends, transport and other costs, and beliefs about the causes of illness and lifestyle change. Depression and anxiety also appear to influence uptake as well as completion. Many factors show inconsistent patterns with respect to uptake and completion of lifestyle change programmes. Conclusion: There are a small number of factors that consistently appear to influence uptake and completion of cardiovascular lifestyle behaviour change. These factors could be considered during patient consultations to promote a tailored approach to decision making about the most suitable type and level lifestyle behaviour change support
Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR
Interpretative and predictive modelling of Joint European Torus collisionality scans
Transport modelling of Joint European Torus (JET) dimensionless collisionality scaling experiments in various operational scenarios is presented. Interpretative simulations at a fixed radial position are combined with predictive JETTO simulations of temperatures and densities, using the TGLF transport model. The model includes electromagnetic effects and collisions as well as □(→┬E ) X □(→┬B ) shear in Miller geometry. Focus is on particle transport and the role of the neutral beam injection (NBI) particle source for the density peaking. The experimental 3-point collisionality scans include L-mode, and H-mode (D and H and higher beta D plasma) plasmas in a total of 12 discharges. Experimental results presented in (Tala et al 2017 44th EPS Conf.) indicate that for the H-mode scans, the NBI particle source plays an important role for the density peaking, whereas for the L-mode scan, the influence of the particle source is small. In general, both the interpretative and predictive transport simulations support the experimental conclusions on the role of the NBI particle source for the 12 JET discharges
Whole-genome sequencing reveals host factors underlying critical COVID-19
Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2–4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease
The role of ETG modes in JET-ILW pedestals with varying levels of power and fuelling
We present the results of GENE gyrokinetic calculations based on a series of JET-ITER-like-wall (ILW) type I ELMy H-mode discharges operating with similar experimental inputs but at different levels of power and gas fuelling. We show that turbulence due to electron-temperature-gradient (ETGs) modes produces a significant amount of heat flux in four JET-ILW discharges, and, when combined with neoclassical simulations, is able to reproduce the experimental heat flux for the two low gas pulses. The simulations plausibly reproduce the high-gas heat fluxes as well, although power balance analysis is complicated by short ELM cycles. By independently varying the normalised temperature gradients (omega(T)(e)) and normalised density gradients (omega(ne )) around their experimental values, we demonstrate that it is the ratio of these two quantities eta(e) = omega(Te)/omega(ne) that determines the location of the peak in the ETG growth rate and heat flux spectra. The heat flux increases rapidly as eta(e) increases above the experimental point, suggesting that ETGs limit the temperature gradient in these pulses. When quantities are normalised using the minor radius, only increases in omega(Te) produce appreciable increases in the ETG growth rates, as well as the largest increases in turbulent heat flux which follow scalings similar to that of critical balance theory. However, when the heat flux is normalised to the electron gyro-Bohm heat flux using the temperature gradient scale length L-Te, it follows a linear trend in correspondence with previous work by different authors
Spectroscopic camera analysis of the roles of molecularly assisted reaction chains during detachment in JET L-mode plasmas
The roles of the molecularly assisted ionization (MAI), recombination (MAR) and dissociation (MAD) reaction chains with respect to the purely atomic ionization and recombination processes were studied experimentally during detachment in low-confinement mode (L-mode) plasmas in JET with the help of experimentally inferred divertor plasma and neutral conditions, extracted previously from filtered camera observations of deuterium Balmer emission, and the reaction coefficients provided by the ADAS, AMJUEL and H2VIBR atomic and molecular databases. The direct contribution of MAI and MAR in the outer divertor particle balance was found to be inferior to the electron-atom ionization (EAI) and electron-ion recombination (EIR). Near the outer strike point, a strong atom source due to the D+2-driven MAD was, however, observed to correlate with the onset of detachment at outer strike point temperatures of Te,osp = 0.9-2.0 eV via increased plasma-neutral interactions before the increasing dominance of EIR at Te,osp < 0.9 eV, followed by increasing degree of detachment. The analysis was supported by predictions from EDGE2D-EIRENE simulations which were in qualitative agreement with the experimental observations
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
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