| 1. |
- Murari, A., et al.
(författare)
-
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
-
Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Leleu, A., et al.
(författare)
-
Six transiting planets and a chain of Laplace resonances in TOI-178
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 649
-
Tidskriftsartikel (refereegranskat)abstract
- Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152 to 2.87 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02 to 0.177 times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes. -0.070 -0.13 -0.23 -0.061 +0.073 +0.14 +0.28 +0.055
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Salganik, E., et al.
(författare)
-
Temporal evolution of under-ice meltwater layers and false bottoms and their impact on summer Arctic sea ice mass balance
- 2023
-
Ingår i: Elementa: Science of the Anthropocene. - 2325-1026. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Low-salinity meltwater from Arctic sea ice and its snow cover accumulates and creates under-ice meltwater layers below sea ice. These meltwater layers can result in the formation of new ice layers, or false bottoms, at the interface of this low-salinity meltwater and colder seawater. As part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), we used a combination of sea ice coring, temperature profiles from thermistor strings and underwater multibeam sonar surveys with a remotely operated vehicle (ROV) to study the areal coverage and temporal evolution of under-ice meltwater layers and false bottoms during the summer melt season from mid-June until late July. ROV surveys indicated that the areal coverage of false bottoms for a part of the MOSAiC Central Observatory (350 by 200 m2) was 21%. Presence of false bottoms reduced bottom ice melt by 7-8% due to the local decrease in the ocean heat flux, which can be described by a thermodynamic model. Under-ice meltwater layer thickness was larger below first-year ice and thinner below thicker second-year ice. We also found that thick ice and ridge keels confined the areas in which under-ice meltwater accumulated, preventing its mixing with underlying seawater. While a thermodynamic model could reproduce false bottom growth and melt, it could not describe the observed bottom melt rates of the ice above false bottoms. We also show that the evolution of under-ice meltwaterlayer salinity below first-year ice is linked to brine flushing from the above sea ice and accumulating in the meltwater layer above the false bottom. The results of this study aid in estimating the contribution of underice meltwater layers and false bottoms to the mass balance and salt budget for Arctic summer sea ice.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Chamberlain, E. J., et al.
(författare)
-
Impacts of sea ice melting procedures on measurements of microbial community structure
- 2022
-
Ingår i: Elementa. - : University of California Press. - 2325-1026. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Microorganisms play critical roles in sea ice biogeochemical processes. However, microbes living within sea ice can be challenging to sample for scientific study. Because most techniques for microbial analysis are optimized for liquid samples, sea ice samples are typically melted first, often applying a buffering method to mitigate osmotic lysis. Here, we tested commonly used melting procedures on three different ice horizons of springtime, first year, land-fast Arctic sea ice to investigate potential methodological impacts on resulting measurements of cell abundance, photophysiology, and microbial community structure as determined by 16S and 18S rRNA gene amplicon sequencing. Specifically, we compared two buffering methods using NaCl solutions (“seawater,” melting the ice in an equal volume of 35-ppt solution, and “isohaline,” melting with a small volume of 250-ppt solution calculated to yield meltwater at estimated in situ brine salinity) to direct ice melting (no buffer addition) on both mechanically “shaved” and “non-shaved” samples. Shaving the ice shortened the melting process, with no significant impacts on the resulting measurements. The seawater buffer was best at minimizing cell lysis for this ice type, retaining the highest number of cells and chlorophyll a concentration. Comparative measurements of bacterial (16S) community structure highlighted ecologically relevant subsets of the community that were significantly more abundant in the buffered samples. The results for eukaryotic (18S) community structure were less conclusive. Taken together, our results suggest that an equivalent-volume seawater-salinity buffered melt is best at minimizing cell loss due to osmotic stress for springtime Arctic sea ice, but that either buffer will reduce bias in community composition when compared to direct melting. Overall, these findings indicate potential methodological biases that should be considered before developing a sea ice melting protocol for microbiological studies and afterwards, when interpreting biogeochemical or ecological meaning of the results.
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
- Hollis, Chris, et al.
(författare)
-
Online remote behavioural intervention for tics in 9- to 17-year-olds : the ORBIT RCT with embedded process and economic evaluation
- 2023
-
Ingår i: Health Technology Assessment. - 1366-5278. ; 27:18, s. 1-120
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Behavioural therapy for tics is difficult to access, and little is known about its effectiveness when delivered online.OBJECTIVE: To investigate the clinical and cost-effectiveness of an online-delivered, therapist- and parent-supported therapy for young people with tic disorders.DESIGN: Single-blind, parallel-group, randomised controlled trial, with 3-month (primary end point) and 6-month post-randomisation follow-up. Participants were individually randomised (1 : 1), using on online system, with block randomisations, stratified by site. Naturalistic follow-up was conducted at 12 and 18 months post-randomisation when participants were free to access non-trial interventions. A subset of participants participated in a process evaluation.SETTING: Two hospitals (London and Nottingham) in England also accepting referrals from patient identification centres and online self-referrals.PARTICIPANTS: Children aged 9-17 years (1) with Tourette syndrome or chronic tic disorder, (2) with a Yale Global Tic Severity Scale-total tic severity score of 15 or more (or > 10 with only motor or vocal tics) and (3) having not received behavioural therapy for tics in the past 12 months or started/stopped medication for tics within the past 2 months.INTERVENTIONS: Either 10 weeks of online, remotely delivered, therapist-supported exposure and response prevention therapy (intervention group) or online psychoeducation (control).OUTCOME: Primary outcome: Yale Global Tic Severity Scale-total tic severity score 3 months post-randomisation; analysis done in all randomised patients for whom data were available. Secondary outcomes included low mood, anxiety, treatment satisfaction and health resource use. Quality-adjusted life-years are derived from parent-completed quality-of-life measures. All trial staff, statisticians and the chief investigator were masked to group allocation.RESULTS: Two hundred and twenty-four participants were randomised to the intervention (n = 112) or control (n = 112) group. Participants were mostly male (n = 177; 79%), with a mean age of 12 years. At 3 months the estimated mean difference in Yale Global Tic Severity Scale-total tic severity score between the groups adjusted for baseline and site was -2.29 points (95% confidence interval -3.86 to -0.71) in favour of therapy (effect size -0.31, 95% confidence interval -0.52 to -0.10). This effect was sustained throughout to the final follow-up at 18 months (-2.01 points, 95% confidence interval -3.86 to -0.15; effect size -0.27, 95% confidence interval -0.52 to -0.02). At 18 months the mean incremental cost per participant of the intervention compared to the control was £662 (95% confidence interval -£59 to £1384), with a mean incremental quality-adjusted life-year of 0.040 (95% confidence interval -0.004 to 0.083) per participant. The mean incremental cost per quality-adjusted life-year gained was £16,708. The intervention was acceptable and delivered with high fidelity. Parental engagement predicted child engagement and more positive clinical outcomes.HARMS: Two serious, unrelated adverse events occurred in the control group.LIMITATIONS: We cannot separate the effects of digital online delivery and the therapy itself. The sample was predominately white and British, limiting generalisability. The design did not compare to face-to-face services.CONCLUSION: Online, therapist-supported behavioural therapy for young people with tic disorders is clinically and cost-effective in reducing tics, with durable benefits extending up to 18 months.FUTURE WORK: Future work should compare online to face-to-face therapy and explore how to embed the intervention in clinical practice.TRIAL REGISTRATION: This trial is registered as ISRCTN70758207; ClinicalTrials.gov (NCT03483493). The trial is now complete.FUNDING: This project was funded by the National Institute for Health and Care Research (NIHR) Health and Technology Assessment programme (project number 16/19/02) and will be published in full in Health and Technology Assessment; Vol. 27, No. 18. See the NIHR Journals Library website for further project information.
|
|
