| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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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.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Fenstermacher, M.E., et al.
(författare)
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DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
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| 10. |
- Bluth, Thomas, et al.
(författare)
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Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) With Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients : A Randomized Clinical Trial.
- 2019
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Ingår i: Journal of the American Medical Association (JAMA). - : American Medical Association (AMA). - 0098-7484 .- 1538-3598. ; 321:23, s. 2292-2305
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Tidskriftsartikel (refereegranskat)abstract
- Importance: An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain.Objective: To determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP.Design, Setting, and Participants: Randomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018.Interventions: Patients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight.Main Outcomes and Measures: The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute).Results: Among 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P = .23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P < .001).Conclusions and Relevance: Among obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications.Trial Registration: ClinicalTrials.gov Identifier: NCT02148692.
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| 11. |
- Bluth, T., et al.
(författare)
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Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE) : study protocol for a randomized controlled trial
- 2017
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise hemodynamics, and the effects on PPCs are uncertain. We hypothesized that intraoperative mechanical ventilation using high PEEP with periodic recruitment maneuvers, as compared with low PEEP without recruitment maneuvers, prevents PPCs in obese patients.Methods/design: The PRotective Ventilation with Higher versus Lower PEEP during General Anesthesia for Surgery in OBESE Patients (PROBESE) study is a multicenter, two-arm, international randomized controlled trial. In total, 2013 obese patients with body mass index >= 35 kg/m(2) scheduled for at least 2 h of surgery under general anesthesia and at intermediate to high risk for PPCs will be included. Patients are ventilated intraoperatively with a low tidal volume of 7 ml/kg (predicted body weight) and randomly assigned to PEEP of 12 cmH(2)O with lung recruitment maneuvers (high PEEP) or PEEP of 4 cmH(2)O without recruitment maneuvers (low PEEP). The occurrence of PPCs will be recorded as collapsed composite of single adverse pulmonary events and represents the primary endpoint.Discussion: To our knowledge, the PROBESE trial is the first multicenter, international randomized controlled trial to compare the effects of two different levels of intraoperative PEEP during protective low tidal volume ventilation on PPCs in obese patients. The results of the PROBESE trial will support anesthesiologists in their decision to choose a certain PEEP level during general anesthesia for surgery in obese patients in an attempt to prevent PPCs.
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| 12. |
- Rudakov, D. L., et al.
(författare)
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Dust measurements in tokamaks (invited)
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:10, s. 10F303-
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Tidskriftsartikel (refereegranskat)abstract
- Dust production and accumulation present potential safety and operational issues for the ITER. Dust diagnostics can be divided into two groups: diagnostics of dust on surfaces and diagnostics of dust in plasma. Diagnostics from both groups are employed in contemporary tokamaks; new diagnostics suitable for ITER are also being developed and tested. Dust accumulation in ITER is likely to occur in hidden areas, e.g., between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In the DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering is able to resolve particles between 0.16 and 1.6 mu m in diameter; using these data the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in two-dimension with a single camera or three-dimension using multiple cameras, but determination of particle size is challenging. In order to calibrate diagnostics and benchmark dust dynamics modeling, precharacterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase in carbon line (CI, CII, C(2) dimer) and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.
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| 13. |
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| 14. |
- Serpa Neto, Ary, et al.
(författare)
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Epidemiological characteristics, practice of ventilation, and clinical outcome in patients at risk of acute respiratory distress syndrome in intensive care units from 16 countries (PRoVENT) : an international, multicentre, prospective study
- 2016
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Ingår i: The Lancet Respiratory Medicine. - 2213-2600 .- 2213-2619. ; 4:11, s. 882-893
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Tidskriftsartikel (refereegranskat)abstract
- Background Scant information exists about the epidemiological characteristics and outcome of patients in the intensive care unit (ICU) at risk of acute respiratory distress syndrome (ARDS) and how ventilation is managed in these individuals. We aimed to establish the epidemiological characteristics of patients at risk of ARDS, describe ventilation management in this population, and assess outcomes compared with people at no risk of ARDS. Methods PRoVENT (PRactice of VENTilation in critically ill patients without ARDS at onset of ventilation) is an international, multicentre, prospective study undertaken at 119 ICUs in 16 countries worldwide. All patients aged 18 years or older who were receiving mechanical ventilation in participating ICUs during a 1-week period between January, 2014, and January, 2015, were enrolled into the study. The Lung Injury Prediction Score (LIPS) was used to stratify risk of ARDS, with a score of 4 or higher defining those at risk of ARDS. The primary outcome was the proportion of patients at risk of ARDS. Secondary outcomes included ventilatory management (including tidal volume [V-T] expressed as mL/kg predicted bodyweight [PBW], and positive end-expiratory pressure [PEEP] expressed as cm H2O), development of pulmonary complications, and clinical outcomes. The PRoVENT study is registered at ClinicalTrials.gov, NCT01868321. The study has been completed. Findings Of 3023 patients screened for the study, 935 individuals fulfilled the inclusion criteria. Of these critically ill patients, 282 were at risk of ARDS (30%, 95% CI 27-33), representing 0.14 cases per ICU bed over a 1-week period. V-T was similar for patients at risk and not at risk of ARDS (median 7.6 mL/kg PBW [IQR 6.7-9.1] vs 7.9 mL/kg PBW [6.8-9.1]; p=0.346). PEEP was higher in patients at risk of ARDS compared with those not at risk (median 6.0 cm H2O [IQR 5.0-8.0] vs 5.0 cm H2O [5.0-7.0]; p<0.0001). The prevalence of ARDS in patients at risk of ARDS was higher than in individuals not at risk of ARDS (19/260 [7%] vs 17/556 [3%]; p=0.004). Compared with individuals not at risk of ARDS, patients at risk of ARDS had higher in-hospital mortality (86/543 [16%] vs 74/232 [32%]; p<0.0001), ICU mortality (62/533 [12%] vs 66/227 [29%]; p<0.0001), and 90-day mortality (109/653 [17%] vs 88/282 [31%]; p<0. 0001). V-T did not differ between patients who did and did not develop ARDS (p=0.471 for those at risk of ARDS; p=0.323 for those not at risk). Interpretation Around a third of patients receiving mechanical ventilation in the ICU were at risk of ARDS. Pulmonary complications occur frequently in patients at risk of ARDS and their clinical outcome is worse compared with those not at risk of ARDS. There is potential for improvement in the management of patients without ARDS. Further refinements are needed for prediction of ARDS.
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| 15. |
- Simonis, Fabienne D., et al.
(författare)
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Potentially modifiable respiratory variables contributing to outcome in ICU patients without ARDS : a secondary analysis of PRoVENT
- 2018
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Ingår i: Annals of Intensive Care. - : Springer Berlin/Heidelberg. - 2110-5820. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: The majority of critically ill patients do not suffer from acute respiratory distress syndrome (ARDS). To improve the treatment of these patients, we aimed to identify potentially modifiable factors associated with outcome of these patients. Methods: The PRoVENT was an international, multicenter, prospective cohort study of consecutive patients under invasive mechanical ventilatory support. A predefined secondary analysis was to examine factors associated with mortality. The primary endpoint was all-cause in-hospital mortality. Results: 935 Patients were included. In-hospital mortality was 21%. Compared to patients who died, patients who survived had a lower risk of ARDS according to the 'Lung Injury Prediction Score' and received lower maximum airway pressure (P-max), driving pressure (Delta P), positive end-expiratory pressure, and FiO(2) levels. Tidal volume size was similar between the groups. Higher P-max was a potentially modifiable ventilatory variable associated with in-hospital mortality in multivariable analyses. Delta P was not independently associated with in-hospital mortality, but reliable values for Delta P were available for 343 patients only. Non-modifiable factors associated with in-hospital mortality were older age, presence of immunosuppression, higher non-pulmonary sequential organ failure assessment scores, lower pulse oximetry readings, higher heart rates, and functional dependence. Conclusions: Higher P-max was independently associated with higher in-hospital mortality in mechanically ventilated critically ill patients under mechanical ventilatory support for reasons other than ARDS.
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| 16. |
- Bulte, Carolien S. E., et al.
(författare)
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The effects of preoperative moderate to severe anaemia on length of hospital stay : A propensity score-matched analysis in non-cardiac surgery patients
- 2021
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Ingår i: European Journal of Anaesthesiology. - : Wolters Kluwer. - 0265-0215 .- 1365-2346. ; 38:6, s. 571-581
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Anaemia is frequently recorded during preoperative screening and has been suggested to affect outcomes after surgery negatively.OBJECTIVES The objectives were to assess the frequency of moderate to severe anaemia and its association with length of hospital stay.DESIGN Post hoc analysis of the international observational prospective ‘Local ASsessment of VEntilatory management during General Anaesthesia for Surgery’ (LAS VEGAS) study.PATIENTS AND SETTING The current analysis included adult patients requiring general anaesthesia for non-cardiac surgery. Preoperative anaemia was defined as a haemoglobin concentration of 11 g dl−1 or lower, thus including moderate and severe anaemia according to World Health Organisation criteria.MAIN OUTCOME MEASURES The primary outcome was length of hospital stay. Secondary outcomes included hospital mortality, intra-operative adverse events and postoperative pulmonary complications (PPCs).RESULTS Haemoglobin concentrations were available for 8264 of 9864 patients. Preoperative moderate to severe anaemia was present in 7.7% of patients. Multivariable analysis showed that preoperative moderate to severe anaemia was associated with an increased length of hospital stay with a mean difference of 1.3 ((95% CI 0.8 to 1.8) days; P < .001). In the propensity-matched analysis, this association remained present, median 4.0 [IQR 1.0 to 5.0] vs. 2.0 [IQR 0.0 to 5.0] days, P = .001. Multivariable analysis showed an increased in-hospital mortality (OR 2.9 (95% CI 1.1 to 7.5); P = .029), and higher incidences of intra-operative hypotension (36.3 vs. 25.3%; P < .001) and PPCs (17.1 vs. 10.5%; P = .001) in moderately to severely anaemic patients. However, this was not confirmed in the propensity score-matched analysis.CONCLUSIONS In this international cohort of non-cardiac surgical patients, preoperative moderate to severe anaemia was associated with a longer duration of hospital stay but not increased intra-operative complications, PPCs or in-hospital mortality.
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| 17. |
- Bykov, I., et al.
(författare)
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Modification of adhered dust on plasma-facing surfaces due to exposure to ELMy H-mode plasma in DIII-D
- 2017
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Ingår i: NUCLEAR MATERIALS AND ENERGY. - : Elsevier BV. - 2352-1791. ; 12, s. 379-385
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Tidskriftsartikel (refereegranskat)abstract
- Transient heat load tests have been conducted in the lower divertor of DIII-D using DiMES manipulator in order to study the behavior of dust on tungsten Plasma Facing Components (PFCs) during ELMy H-mode discharges. Samples with pre- adhered, pre- characterized dust have been exposed at the outer strike point (OSP) in a series of discharges with varied intra-(inter-) ELM heat fluxes. We used C dust because of its high sublimation temperature and non-metal properties. Al dust as a surrogate for Be and W dust were employed as relevant to that in the ITER divertor. The poor initial thermal contact between the substrate and the particles led to overheating, sublimation and shrinking of the carbon dust, and wetting induced coagulation of Al dust. Little modification of the W dust was observed. An enhanced surface adhesion and improvement of the thermal contact of C and Al dust were the result of exposure. A post mortem "adhesive tape" sampling showed that 70% of Al, <5% of W and C particles could not be removed from the surface owing to the improved adhesion. Al and C but not W particles that could be lifted had W inclusions indicating damage to the substrate. This suggests that non destructive methods may be inefficient for removal of dust in ITER.
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| 18. |
- Glas, Gerie J., et al.
(författare)
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Ventilation practices in burn patients-an international prospective observational cohort study
- 2021
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Ingår i: BURNS & TRAUMA. - : Oxford University Press. - 2321-3868 .- 2321-3876. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is unknown whether lung-protective ventilation is applied in burn patients and whether they benefit from it. This study aimed to determine ventilation practices in burn intensive care units (ICUs) and investigate the association between lung-protective ventilation and the number of ventilator-free days and alive at day 28 (VFD-28). Methods: This is an international prospective observational cohort study including adult burn patients requiring mechanical ventilation. Low tidal volume (V-T) was defined as V-T <= 8 mL/kg predicted body weight (PBW). Levels of positive end-expiratory pressure (PEEP) and maximum airway pressures were collected. The association between V-T and VFD-28 was analyzed using a competing risk model. Ventilation settings were presented for all patients, focusing on the first day of ventilation. We also compared ventilation settings between patients with and without inhalation trauma. Results: A total of 160 patients from 28 ICUs in 16 countries were included. Low V-T was used in 74% of patients, median V-T size was 7.3 [interquartile range (IQR) 6.2-8.3] mL/kg PBW and did not differ between patients with and without inhalation trauma (p= 0.58). Median VFD-28 was 17 (IQR 0-26), without a difference between ventilation with low or high V-T (p= 0.98). All patients were ventilated with PEEP levels >= 5 cmH(2)O; 80% of patients had maximum airway pressures <30 cmH(2)O. Conclusion: In this international cohort study we found that lung-protective ventilation is used in the majority of burn patients, irrespective of the presence of inhalation trauma. Use of low V-T was not associated with a reduction in VFD-28.
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| 19. |
- Hemmes, Sabrine N. T., et al.
(författare)
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Rationale and study design of PROVHILO - a worldwide multicenter randomized controlled trial on protective ventilation during general anesthesia for open abdominal surgery
- 2011
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 12, s. 111-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Post-operative pulmonary complications add to the morbidity and mortality of surgical patients, in particular after general anesthesia >2 hours for abdominal surgery. Whether a protective mechanical ventilation strategy with higher levels of positive end-expiratory pressure (PEEP) and repeated recruitment maneuvers; the "open lung strategy", protects against post-operative pulmonary complications is uncertain. The present study aims at comparing a protective mechanical ventilation strategy with a conventional mechanical ventilation strategy during general anesthesia for abdominal non-laparoscopic surgery. Methods: The PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure ("PROVHILO") trial is a worldwide investigator-initiated multicenter randomized controlled two-arm study. Nine hundred patients scheduled for non-laparoscopic abdominal surgery at high or intermediate risk for post-operative pulmonary complications are randomized to mechanical ventilation with the level of PEEP at 12 cmH(2)O with recruitment maneuvers (the lung-protective strategy) or mechanical ventilation with the level of PEEP at maximum 2 cmH(2)O without recruitment maneuvers (the conventional strategy). The primary endpoint is any post-operative pulmonary complication. Discussion: The PROVHILO trial is the first randomized controlled trial powered to investigate whether an open lung mechanical ventilation strategy in short-term mechanical ventilation prevents against postoperative pulmonary complications.
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| 20. |
- Hollmann, E M, et al.
(författare)
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Estimate of pre-thermal quench non-thermal electron density profile during Ar pellet shutdowns of low-density target plasmas in DIII-D
- 2021
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 28:7
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Tidskriftsartikel (refereegranskat)abstract
- The radial density profile of pre-thermal quench (pre-TQ) early-time non-thermal (hot) electrons is estimated by combining electron cyclotron emission and soft x-ray data during the rapid shutdown of low-density (ne≲1019m−3) DIII-D target plasmas with cryogenic argon pellet injection. This technique is mostly limited in these experiments to the pre-TQ phase and quickly loses validity during the TQ. Two different cases are studied: a high (10 keV) temperature target and a low (4 keV) temperature target. The results indicate that early-time, low-energy (∼10 keV) hot electrons form ahead of the argon pellet as it enters the plasma, affecting the pellet ablation rate; it is hypothesized that this may be caused by rapid cross field transport of argon ions ahead of the pellet or by rapid cross field transport of hot electrons. Fokker-Planck modeling of the two shots suggests that the hot electron current is quite significant during the pre-TQ phase (up to 50% of the total current). Comparison between modeled pre-TQ hot electron current and post-TQ hot electron current inferred from avalanche theory suggests that hot electron current increases during the high-temperature target TQ but decreases during the low-temperature target TQ. The uncertainties in this estimate are large; however, if true, this suggests that TQ radial loss of hot electron current could be larger than previously estimated in DIII-D.
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| 21. |
- Hollmann, E M, et al.
(författare)
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Status of research toward the ITER disruption mitigation system
- 2015
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 22:2, s. 021802-
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Tidskriftsartikel (refereegranskat)abstract
- An overview of the present status of research toward the final design of the ITER disruption mitigation system (DMS) is given. The ITER DMS is based on massive injection of impurities, in order to radiate the plasma stored energy and mitigate the potentially damaging effects of disruptions. The design of this system will be extremely challenging due to many physics and engineering constraints such as limitations on port access and the amount and species of injected impurities. Additionally, many physics questions relevant to the design of the ITER disruption mitigation system remain unsolved such as the mechanisms for mixing and assimilation of injected impurities during the rapid shutdown and the mechanisms for the subsequent formation and dissipation of runaway electron current.
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| 22. |
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| 23. |
- Paz-Soldan, C., et al.
(författare)
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Recent DIII-D advances in runaway electron measurement and model validation
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:6
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Tidskriftsartikel (refereegranskat)abstract
- Novel measurements and modeling of runaway electron (RE) dynamics in DIII-D have resolved experimental discrepancies and validated predictions for ITER, improving confidence that RE avoidance and mitigation can be predictably achieved. Considering RE formation, first experimental assessments of the RE seed current demonstrates that present hot-tail theories are not yet accurate and require improved treatment of the pellet dynamics. Novel measurements of kinetic instabilities in the MHz-range have been made in the RE formation phase, with the intensity of these modes correlated with previously unexplained empirical thresholds for RE generation. Controlled RE dissipation experiments in quiescent regimes have validated RE distribution function dependencies on collisional and synchrotron damping, both in terms of distribution function shape and dissipation rates. Measurements of RE bremsstrahlung and synchrotron emission are now used in tandem to resolve energy and pitch-angle effects. A resolution to long-standing dissipation anomalies in the quiescent regime is offered by taking into account kinetic instability effects on RE phase-space dynamics. Kinetic instabilities in the 100-200 MHz range are directly observed, though modeling finds the largest dissipation arises from GHz range instabilities that are beyond the reach of existing diagnostics. Kinetic instabilities are also observed in the mature post-disruption RE plateau phase, so long as the collisional damping rate is reduced with low-Z injection. Experiments with high-Z injection find that the dissipation rate saturates with injection quantity, likely due to neutral diffusion rates being slower than vertical instability rates in DIII-D. Considering the final loss, a 0D model for first-wall Joule heating is found to be in agreement with experiment, and controlled access to RE equilibria with edge safety factor of two identifies novel dynamics brought about by large-scale kink instabilities. These dynamics are typified by fast (tens of microseconds) RE loss rates without RE beam regeneration. The above measurements and comparison with theory represent significant advances in the understanding of RE dynamics and indicate possible new opportunities for RE avoidance or mitigation via kinetic instabilities.
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| 24. |
- Almeida, Tiago P., et al.
(författare)
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Ultra-Thin Films of Reduced Graphene Oxide (RGO) Nanoplatelets Functionalized with Different Organic Materials
- 2016
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Ingår i: Journal of Bioprocessing & Biotechniques. - : OMICS Publishing Group. - 2155-9821. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- This work aims the functionalization of reduced graphene oxide nanoplatelets with chitosan (G-chitosan) and also with poly(styrenesulfonic acid) (GPSS), thus forming stable, dispersed aqueous solutions. G-chitosan and GPSS solutions allowed the layer-by-layer (LbL) film formation with glucose oxidase (GOx), establishing multilayered nanostructures with elevated control in thickness and morphology. The graphene nanoplatelets were characterized by UV-vis and FTIR spectroscopies, resulting in good adherence and linear deposition of the graphene nanoplatelets with GOx in the LbL structures.Cyclic voltammetry shows an enlargement in the current intensity with increasing number of deposited LbL layers, possibly owing to the formation of conducting paths by the graphene nanoplatelets in the tailored multilayer nanomaterial formed
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| 25. |
- Conzelmann, A., et al.
(författare)
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Internet-based psychotherapy in children with obsessive-compulsive disorder (OCD): protocol of a randomized controlled trial
- 2022
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Obsessive-compulsive disorder (OCD) in children can lead to a huge burden on the concerned patients and their family members. While successful state-of-the art cognitive behavioral interventions exist, there is still a lack of available experts for treatment at home, where most symptoms manifest. Internet-based cognitive behavioral therapy (iCBT) could overcome these restrictions; however, studies about iCBT in children with OCD are rare and mostly target computerized self-help resources and only email contact with the therapist. Therefore, we intended to build up and to evaluate an iCBT approach for children with OCD, replacing successful elements of traditional in-office face-to-face CBT, with face-to-face teleconferences, online materials, and apps. Methods: With the help of a pilot feasibility study, we developed the iCBT consisting of 14 teleconference sessions with the child and parents. The sessions are supported by an app assessing daily and weekly symptoms and treatment course completed by children and parents. Additionally, we obtain heart rate and activity scores from the child via wristbands during several days and exposure sessions. Using a waiting list randomized control trial design, we aim to treat and analyze 20 children with OCD immediately after a diagnostic session whereas the control group of another set of 20 OCD patients will be treated after waiting period of 16 weeks. We will recruit 30 patients in each group to take account for potential dropouts. Outcomes for the treatment group are evaluated before randomization (baseline, t0), 16 weeks (end of treatment, t1), 32 weeks (follow-up 1, t2), and 48 weeks after randomization (follow-up 2, t3). For the waiting list group, outcomes are measured before the first randomization (baseline), at 16 weeks (waiting list period), 32 weeks (end of treatment), 48 weeks after the first randomization (follow-up I), and 64 weeks after the first randomization (follow-up II). Discussion: Based on our experience of feasibility during the pilot study, we were able to develop the iCBT approach and the current study will investigate treatment effectiveness. Building up an iCBT approach, resembling traditional in-office face-to-face therapy, may ensure the achievement of well-known therapy effect factors, the acceptance in both patients and clinicians, and the wide distribution within the health system.
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| 26. |
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| 27. |
- Hemmes, Sabrine N. T., et al.
(författare)
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Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications : LAS VEGAS - an observational study in 29 countries
- 2017
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Ingår i: European Journal of Anaesthesiology. - : LIPPINCOTT WILLIAMS & WILKINS. - 0265-0215 .- 1365-2346. ; 34:8, s. 492-507
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome. TRIAL REGISTRATION The study was registered at Clinicaltrials.gov, number NCT01601223.
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| 28. |
- Hemmes, Sabrine N. T., et al.
(författare)
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High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial) : a multicentre randomised controlled trial
- 2014
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 384:9942, s. 495-503
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Tidskriftsartikel (refereegranskat)abstract
- Background The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery. Methods In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (<= 2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials. com, number ISRCTN70332574. Findings From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher PEEP group versus 172 (39%) of 449 patients in the lower PEEP group (relative risk 1.01; 95% CI 0.86-1.20; p = 0.86). Compared with patients in the lower PEEP group, those in the higher PEEP group developed intraoperative hypotension and needed more vasoactive drugs. Interpretation A strategy with a high level of positive end-expiratory pressure and recruitment manoeuvres during open abdominal surgery does not protect against postoperative pulmonary complications. An intraoperative protective ventilation strategy should include a low tidal volume and low positive end-expiratory pressure, without recruitment manoeuvres.
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| 29. |
- Hollmann, K., et al.
(författare)
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Internet-based cognitive behavioral therapy in children and adolescents with obsessive compulsive disorder: a feasibility study
- 2021
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Ingår i: Journal of Neural Transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 128, s. 1445-1459
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive behavioral therapy (CBT) is the first choice of treatment of obsessive-compulsive disorder (OCD) in children and adolescents. However, there is often a lack of access to appropriate treatment close to the home of the patients. An internet-based CBT via videoconferencing could facilitate access to state-of-the-art treatment even in remote areas. The aim of this study was to investigate feasibility and acceptability of this telemedical approach. A total of nine children received 14 sessions of CBT. The first session took place face-to-face, the remaining 13 sessions via videoconference. OCD symptoms were recorded with a smartphone app and therapy materials were made accessible in a data cloud. We assessed diagnostic data before and after treatment and obtained measures to feasibility, treatment satisfaction and acceptability. Outcomes showed high acceptance and satisfaction on the part of patients with online treatment (89%) and that face-to-face therapy was not preferred over an internet-based approach (67%). The majority of patients and their parents classified the quality of treatment as high. They emphasized the usefulness of exposures with response prevention (E/RP) in triggering situations at home. The app itself was rated as easy to operate and useful. In addition to feasibility, a significant decrease in obsessive-compulsive symptoms was also achieved. Internet-based CBT for pediatric OCD is feasible and well received by the patients and their parents. Furthermore, obsessive-compulsive symptomatology decreased in all patients. The results of this study are encouraging and suggest the significance of further research regarding this technology-supported approach, with a specific focus on efficacy. Trial registration number: Clinical trials AZ53-5400.1-004/44.
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| 30. |
- Kirmeier, Eva, et al.
(författare)
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Post-anaesthesia pulmonary complications after use of muscle relaxants (POPULAR) : a multicentre, prospective observational study.
- 2019
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Ingår i: The Lancet Respiratory Medicine. - 2213-2600 .- 2213-2619. ; 7:2, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Results from retrospective studies suggest that use of neuromuscular blocking agents during general anaesthesia might be linked to postoperative pulmonary complications. We therefore aimed to assess whether the use of neuromuscular blocking agents is associated with postoperative pulmonary complications.METHODS: We did a multicentre, prospective observational cohort study. Patients were recruited from 211 hospitals in 28 European countries. We included patients (aged ≥18 years) who received general anaesthesia for any in-hospital procedure except cardiac surgery. Patient characteristics, surgical and anaesthetic details, and chart review at discharge were prospectively collected over 2 weeks. Additionally, each patient underwent postoperative physical examination within 3 days of surgery to check for adverse pulmonary events. The study outcome was the incidence of postoperative pulmonary complications from the end of surgery up to postoperative day 28. Logistic regression analyses were adjusted for surgical factors and patients' preoperative physical status, providing adjusted odds ratios (ORadj) and adjusted absolute risk reduction (ARRadj). This study is registered with ClinicalTrials.gov, number NCT01865513.FINDINGS: Between June 16, 2014, and April 29, 2015, data from 22 803 patients were collected. The use of neuromuscular blocking agents was associated with an increased incidence of postoperative pulmonary complications in patients who had undergone general anaesthesia (1658 [7·6%] of 21 694); ORadj 1·86, 95% CI 1·53-2·26; ARRadj -4·4%, 95% CI -5·5 to -3·2). Only 2·3% of high-risk surgical patients and those with adverse respiratory profiles were anaesthetised without neuromuscular blocking agents. The use of neuromuscular monitoring (ORadj 1·31, 95% CI 1·15-1·49; ARRadj -2·6%, 95% CI -3·9 to -1·4) and the administration of reversal agents (1·23, 1·07-1·41; -1·9%, -3·2 to -0·7) were not associated with a decreased risk of postoperative pulmonary complications. Neither the choice of sugammadex instead of neostigmine for reversal (ORadj 1·03, 95% CI 0·85-1·25; ARRadj -0·3%, 95% CI -2·4 to 1·5) nor extubation at a train-of-four ratio of 0·9 or more (1·03, 0·82-1·31; -0·4%, -3·5 to 2·2) was associated with better pulmonary outcomes.INTERPRETATION: We showed that the use of neuromuscular blocking drugs in general anaesthesia is associated with an increased risk of postoperative pulmonary complications. Anaesthetists must balance the potential benefits of neuromuscular blockade against the increased risk of postoperative pulmonary complications.FUNDING: European Society of Anaesthesiology.
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| 31. |
- Marini, C., et al.
(författare)
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Runaway electron plateau current profile reconstruction from synchrotron imaging and Ar-II line polarization angle measurements in DIII-D
- 2024
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 64:7
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Tidskriftsartikel (refereegranskat)abstract
- Current profile reconstructions are obtained for high current ( I p ≃ 550 kA) post-disruption runaway electron (RE) plateau plasmas in DIII-D. Two novel methods of measuring the RE current profile in high-current RE plateaus are introduced and compared: localization of the q = 2 rational surface using visible synchrotron emission (SE) imaging and the measurement of the polarization angle of line-integrated Ar-II line emission. The two methods are found to be consistent with each other within the data uncertainties. Different simulations of the RE current profile are compared with the measurements: the toroidal fluid RE model is found to best fit the data, within the measurement uncertainties. In addition to introducing two novel methods to measure the RE current profile and validating present simulation capabilities, this work demonstrates that instabilities can grow at q = 2 and q = 1 surfaces without necessarily causing a RE final loss instability. Numerical simulations are also presented to elucidate the role of these instabilities on synchrotron emission.
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| 32. |
- Mazzinari, Guido, et al.
(författare)
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The Association of Intraoperative driving pressure with postoperative pulmonary complications in open versus closed abdominal surgery patients - a posthoc propensity score-weighted cohort analysis of the LAS VEGAS study
- 2021
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Ingår i: BMC Anesthesiology. - : BioMed Central (BMC). - 1471-2253 .- 1471-2253. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIt is uncertain whether the association of the intraoperative driving pressure (Delta P) with postoperative pulmonary complications (PPCs) depends on the surgical approach during abdominal surgery. Our primary objective was to determine and compare the association of time-weighted average Delta P (Delta P-TW) with PPCs. We also tested the association of Delta P-TW with intraoperative adverse events.MethodsPosthoc retrospective propensity score-weighted cohort analysis of patients undergoing open or closed abdominal surgery in the 'Local ASsessment of Ventilatory management during General Anaesthesia for Surgery' (LAS VEGAS) study, that included patients in 146 hospitals across 29 countries. The primary endpoint was a composite of PPCs. The secondary endpoint was a composite of intraoperative adverse events.ResultsThe analysis included 1128 and 906 patients undergoing open or closed abdominal surgery, respectively. The PPC rate was 5%. Delta P was lower in open abdominal surgery patients, but Delta P-TW was not different between groups. The association of Delta P-TW with PPCs was significant in both groups and had a higher risk ratio in closed compared to open abdominal surgery patients (1.11 [95%CI 1.10 to 1.20], P < 0.001 versus 1.05 [95%CI 1.05 to 1.05], P < 0.001; risk difference 0.05 [95%CI 0.04 to 0.06], P < 0.001). The association of P-TW with intraoperative adverse events was also significant in both groups but had higher odds ratio in closed compared to open abdominal surgery patients (1.13 [95%CI 1.12- to 1.14], P < 0.001 versus 1.07 [95%CI 1.05 to 1.10], P < 0.001; risk difference 0.05 [95%CI 0.030.07], P < 0.001).ConclusionsP is associated with PPC and intraoperative adverse events in abdominal surgery, both in open and closed abdominal surgery.Trial registrationLAS VEGAS was registered at clinicaltrials.gov (trial identifier NCT01601223).
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| 33. |
- Nijbroek, Sunny G., et al.
(författare)
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Sex difference and intra-operative tidal volume : Insights from the LAS VEGAS study
- 2021
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Ingår i: European Journal of Anaesthesiology. - : Wolters Kluwer. - 0265-0215 .- 1365-2346. ; 38:10, s. 1034-1041
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg−1 or less predicted bodyweight (PBW). A VT was deemed ‘default’ if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg−1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients’ height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION The study was registered at Clinicaltrials.gov, NCT01601223
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| 34. |
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| 35. |
- Serpa Neto, Ary, et al.
(författare)
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Protective versus Conventional Ventilation for Surgery : A Systematic Review and Individual Patient Data Meta-analysis
- 2015
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Ingår i: Anesthesiology. - 0003-3022 .- 1528-1175. ; 123:1, s. 66-78
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Recent studies show that intraoperative mechanical ventilation using low tidal volumes (VT) can prevent postoperative pulmonary complications (PPCs). The aim of this individual patient data meta-analysis is to evaluate the individual associations between VT size and positive end-expiratory pressure (PEEP) level and occurrence of PPC.METHODS: Randomized controlled trials comparing protective ventilation (low VT with or without high levels of PEEP) and conventional ventilation (high VT with low PEEP) in patients undergoing general surgery. The primary outcome was development of PPC. Predefined prognostic factors were tested using multivariate logistic regression.RESULTS: Fifteen randomized controlled trials were included (2,127 patients). There were 97 cases of PPC in 1,118 patients (8.7%) assigned to protective ventilation and 148 cases in 1,009 patients (14.7%) assigned to conventional ventilation (adjusted relative risk, 0.64; 95% CI, 0.46 to 0.88; P < 0.01). There were 85 cases of PPC in 957 patients (8.9%) assigned to ventilation with low VT and high PEEP levels and 63 cases in 525 patients (12%) assigned to ventilation with low VT and low PEEP levels (adjusted relative risk, 0.93; 95% CI, 0.64 to 1.37; P = 0.72). A dose-response relationship was found between the appearance of PPC and VT size (R = 0.39) but not between the appearance of PPC and PEEP level (R = 0.08).CONCLUSIONS: These data support the beneficial effects of ventilation with use of low VT in patients undergoing surgery. Further trials are necessary to define the role of intraoperative higher PEEP to prevent PPC during nonopen abdominal surgery.
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| 36. |
- Stahl, Adam, 1985, et al.
(författare)
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Synchrotron radiation from a runaway electron distribution in tokamaks
- 2013
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 20:9, s. 093302-
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Tidskriftsartikel (refereegranskat)abstract
- The synchrotron radiation emitted by runaway electrons in a fusion plasma provides information regarding the particle momenta and pitch-angles of the runaway electron population through the strong dependence of the synchrotron spectrum on these parameters. Information about the runaway density and its spatial distribution, as well as the time evolution of the above quantities, can also be deduced. In this paper, we present the synchrotron radiation spectra for typical avalanching runaway electron distributions. Spectra obtained for a distribution of electrons are compared with the emission of mono-energetic electrons with a prescribed pitch-angle. We also examine the effects of magnetic field curvature and analyse the sensitivity of the resulting spectrum to perturbations to the runaway distribution. The implications for the deduced runaway electron parameters are discussed. We compare our calculations to experimental data from DIII-D and estimate the maximum observed runaway energy.
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| 37. |
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