Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 609
Filter
1.
Nat Commun ; 15(1): 2975, 2024 Apr 06.
Article in English | MEDLINE | ID: mdl-38582938

ABSTRACT

Indirect Drive Inertial Confinement Fusion Experiments on the National Ignition Facility (NIF) have achieved a burning plasma state with neutron yields exceeding 170 kJ, roughly 3 times the prior record and a necessary stage for igniting plasmas. The results are achieved despite multiple sources of degradations that lead to high variability in performance. Results shown here, for the first time, include an empirical correction factor for mode-2 asymmetry in the burning plasma regime in addition to previously determined corrections for radiative mix and mode-1. Analysis shows that including these three corrections alone accounts for the measured fusion performance variability in the two highest performing experimental campaigns on the NIF to within error. Here we quantify the performance sensitivity to mode-2 symmetry in the burning plasma regime and apply the results, in the form of an empirical correction to a 1D performance model. Furthermore, we find the sensitivity to mode-2 determined through a series of integrated 2D radiation hydrodynamic simulations to be consistent with the experimentally determined sensitivity only when including alpha-heating.

3.
J Neurointerv Surg ; 2023 Nov 08.
Article in English | MEDLINE | ID: mdl-37940386

ABSTRACT

BACKGROUND: Periprocedural ischemic stroke remains a serious complication in patients undergoing transcatheter aortic valve replacement (TAVR). We used a novel robotic transcranial Doppler (TCD) system equipped with artificial intelligence (AI) for real-time continuous intraoperative neuromonitoring during TAVR to establish the safety and potential validity of this tool in detecting cerebral emboli, report the quantity and distribution of high intensity transient signals (HITS) with and without cerebral protection, and correlate HITS occurrence with various procedural steps. METHODS: Consecutive patients undergoing TAVR procedures during which the robotic system was used between October 2021 and May 2022 were prospectively enrolled in this pilot study. The robotic TCD system included autonomous adjustment of the TCD probes and AI-assisted post-processing of HITS and other cerebral flow parameters. Basic demographics and procedural details were recorded. Continuous variables were analyzed by a two-sample Mann-Whitney t-test and categorical variables by a χ2 or Fisher test. RESULTS: Thirty-one patients were prospectively enrolled (mean age 79.9±7.6 years; 16 men (51.6%)). Mean aortic valve stenotic area was 0.7 cm2 and mean aortic-ventricular gradient was 43 mmHg (IQR 31.5-50 mmHg). Cerebral protection was used in 16 cases (51.6%). Significantly fewer emboli were observed in the protection group than in the non-protection group (mean 470.38 vs 693.33; p=0.01). Emboli counts during valve positioning and implantation were significantly different in the protection and non-protection groups (mean 249.92 and 387.5, respectively; p=0.01). One (4%) transient ischemic attack occurred post-procedurally in the non-protection group. CONCLUSION: We describe a novel real-time intraoperative neuromonitoring tool used in patients undergoing TAVR. Significantly fewer HITS were detected with protection. Valve positioning-implantation was the most significant stage for intraprocedural HITS.

4.
Ann R Coll Surg Engl ; 105(4): 306-313, 2023 Apr.
Article in English | MEDLINE | ID: mdl-35174720

ABSTRACT

INTRODUCTION: Emergency laparotomy for either trauma or non-trauma indications is common and management is varied. Use of the open abdomen technique allowing for planned re-look is an option; however, performing delayed definitive fascial closure (DFC) following this can be a challenge. The use of botulinum toxin-A (BTX) infiltration into the lateral abdominal wall has been well documented within the elective setting; its use within the emergency setting is undecided. This systematic review assesses the efficacy and safety of BTX injection into the lateral abdominal wall muscles in the emergency setting. The primary outcome is DFC rate. METHODS: Systematic review was performed according to the PROSPERO registered protocol (CRD42020205130). Papers were dual screened for eligibility, and included if they met pre-stated criteria where the primary outcome was DFC. Articles reporting fewer than five cases were excluded. Bias was assessed using the Cochrane Risk of Bias and Joanna Brigg's appraisal tools. FINDINGS: Fourteen studies were screened for eligibility, twelve full texts were reviewed and two studies were included. Both studies showed evidence of bias due to confounding factors and lack of reporting. Both studies suggested significantly higher rates of DFC than reported in the literature against standard technique (90.7% vs 66%); however, these data are difficult to interpret due to strict study inclusion criteria or lack of a control population. CONCLUSION: The use of BTX is deemed safe and its effects in the emergency situation may have great potential. Unfortunately, to date, there is insufficient evidence to facilitate opinion.


Subject(s)
Abdominal Cavity , Abdominal Wall , Abdominal Wound Closure Techniques , Botulinum Toxins, Type A , Humans , Botulinum Toxins, Type A/therapeutic use , Abdominal Wall/surgery , Abdomen/surgery , Abdominal Muscles/surgery , Laparotomy/methods
6.
Phys Rev E ; 106(2-2): 025202, 2022 Aug.
Article in English | MEDLINE | ID: mdl-36109932

ABSTRACT

An inertial fusion implosion on the National Ignition Facility, conducted on August 8, 2021 (N210808), recently produced more than a megajoule of fusion yield and passed Lawson's criterion for ignition [Phys. Rev. Lett. 129, 075001 (2022)10.1103/PhysRevLett.129.075001]. We describe the experimental improvements that enabled N210808 and present the first experimental measurements from an igniting plasma in the laboratory. Ignition metrics like the product of hot-spot energy and pressure squared, in the absence of self-heating, increased by ∼35%, leading to record values and an enhancement from previous experiments in the hot-spot energy (∼3×), pressure (∼2×), and mass (∼2×). These results are consistent with self-heating dominating other power balance terms. The burn rate increases by an order of magnitude after peak compression, and the hot-spot conditions show clear evidence for burn propagation into the dense fuel surrounding the hot spot. These novel dynamics and thermodynamic properties have never been observed on prior inertial fusion experiments.

7.
Phys Rev E ; 106(2-2): 025201, 2022 Aug.
Article in English | MEDLINE | ID: mdl-36110025

ABSTRACT

We present the design of the first igniting fusion plasma in the laboratory by Lawson's criterion that produced 1.37 MJ of fusion energy, Hybrid-E experiment N210808 (August 8, 2021) [Phys. Rev. Lett. 129, 075001 (2022)10.1103/PhysRevLett.129.075001]. This design uses the indirect drive inertial confinement fusion approach to heat and compress a central "hot spot" of deuterium-tritium (DT) fuel using a surrounding dense DT fuel piston. Ignition occurs when the heating from absorption of α particles created in the fusion process overcomes the loss mechanisms in the system for a duration of time. This letter describes key design changes which enabled a ∼3-6× increase in an ignition figure of merit (generalized Lawson criterion) [Phys. Plasmas 28, 022704 (2021)1070-664X10.1063/5.0035583, Phys. Plasmas 25, 122704 (2018)1070-664X10.1063/1.5049595]) and an eightfold increase in fusion energy output compared to predecessor experiments. We present simulations of the hot-spot conditions for experiment N210808 that show fundamentally different behavior compared to predecessor experiments and simulated metrics that are consistent with N210808 reaching for the first time in the laboratory "ignition."

10.
Nature ; 601(7894): 542-548, 2022 01.
Article in English | MEDLINE | ID: mdl-35082418

ABSTRACT

Obtaining a burning plasma is a critical step towards self-sustaining fusion energy1. A burning plasma is one in which the fusion reactions themselves are the primary source of heating in the plasma, which is necessary to sustain and propagate the burn, enabling high energy gain. After decades of fusion research, here we achieve a burning-plasma state in the laboratory. These experiments were conducted at the US National Ignition Facility, a laser facility delivering up to 1.9 megajoules of energy in pulses with peak powers up to 500 terawatts. We use the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule via the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work. The burning-plasma state was created using a strategy to increase the spatial scale of the capsule2,3 through two different implosion concepts4-7. These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics3,8. Additionally, we describe a subset of experiments that appear to have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction. These results provide an opportunity to study α-particle-dominated plasmas and burning-plasma physics in the laboratory.

11.
Postepy Kardiol Interwencyjnej ; 17(3): 245-250, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34819960

ABSTRACT

Stroke, a vascular disease of the brain, is the #1 cause of disability and a major cause of death worldwide. Stroke has a major negative impact on the life of stroke-affected individuals, their families and the society. A significant proportion of stroke victims indicate that would have preferred death over their after-stroke quality of life. Mechanical thrombectomy (MT), opening the occluded artery using mechanical aspiration or a thrombus-entrapment device, is a guideline-mandated (class I, level of evidence A) treatment modality in patients with large vessel occlusion stroke. MT clinical benefit magnitude indicates that a universal access to this treatment strategy should be the standard of care. Today there is a substantial geographic variation in MT deliverability, with large-scale disparities in MT implementation. In many countries effective access to MT remains severely limited. In addition, many of the MT-treated patients are treated too late for a good functional outcome because of logistic delays that include transportations to remotely located, scarce, comprehensive stroke centres. Position Paper from the European Society of Cardiology Council on Stroke and European Association for Percutaneous Cardiovascular Interventions on interdisciplinary management of acute ischaemic stroke, developed with the support of the European Board of Neurointervention fills an important gap in systematically enabling interventional cardiologists to support stroke intervention in the geographic areas of unmet needs in particular. We review strengths and weaknesses of the document, and suggest directions for the next steps that are swiftly needed to deliver MT to stroke patients more effectively.

12.
Phys Rev E ; 104(1): L013201, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34412205

ABSTRACT

A series of thin glass-shell shock-driven DT gas-filled capsule implosions was conducted at the OMEGA laser facility. These experiments generate conditions relevant to the central plasma during the shock-convergence phase of ablatively driven inertial confinement fusion (ICF) implosions. The spectral temperatures inferred from the DTn and DDn spectra are most consistent with a two-ion-temperature plasma, where the initial apparent temperature ratio, T_{T}/T_{D}, is 1.5. This is an experimental confirmation of the long-standing conjecture that plasma shocks couple energy directly proportional to the species mass in multi-ion plasmas. The apparent temperature ratio trend with equilibration time matches expected thermal equilibration described by hydrodynamic theory. This indicates that deuterium and tritium ions have different energy distributions for the time period surrounding shock convergence in ignition-relevant ICF implosions.

13.
BJS Open ; 5(4)2021 07 06.
Article in English | MEDLINE | ID: mdl-34323917

ABSTRACT

INTRODUCTION: Core surgical training programmes are associated with a high risk of burnout. This study aimed to assess the influence of a novel enhanced stress-resilience training (ESRT) course delivered at the start of core surgical training in a single UK statutory education body. METHOD: All newly appointed core surgical trainees (CSTs) were invited to participate in a 5-week ESRT course teaching mindfulness-based exercises to develop tools to deal with stress at work and burnout. The primary aim was to assess the feasibility of this course; secondary outcomes were to assess degree of burnout measured using Maslach Burnout Inventory (MBI) scoring. RESULTS: Of 43 boot camp attendees, 38 trainees completed questionnaires, with 24 choosing to participate in ESRT (63.2 per cent; male 13, female 11, median age 28 years). Qualitative data reflected challenges delivering ESRT because of arduous and inflexible clinical on-call rotas, time pressures related to academic curriculum demands and the concurrent COVID-19 pandemic (10 of 24 drop-out). Despite these challenges, 22 (91.7 per cent) considered the course valuable and there was unanimous support for programme development. Of the 14 trainees who completed the ESRT course, nine (64.3 per cent) continued to use the techniques in daily clinical work. Burnout was identified in 23 trainees (60.5 per cent) with no evident difference in baseline MBI scores between participants (median 4 (range 0-11) versus 5 (1-11), P = 0.770). High stress states were significantly less likely, and mindfulness significantly higher in the intervention group (P < 0.010); MBI scores were comparable before and after ESRT in the intervention cohort (P = 0.630, median 4 (range 0-11) versus 4 (1-10)). DISCUSSION: Despite arduous emergency COVID rotas ESRT was feasible and, combined with protected time for trainees to engage, deserves further research to determine medium-term efficacy.


Subject(s)
Burnout, Professional/prevention & control , Curriculum , General Surgery/education , Resilience, Psychological , Stress, Psychological/prevention & control , Surgeons/psychology , Adult , Anxiety/prevention & control , COVID-19/epidemiology , Depression/prevention & control , Feasibility Studies , Female , Humans , Male , Mindfulness , Pandemics , Surveys and Questionnaires , United Kingdom , Work Schedule Tolerance
15.
Eur Heart J ; 42(4): 298-307, 2021 01 21.
Article in English | MEDLINE | ID: mdl-33521827

ABSTRACT

This ESC Council on Stroke/EAPCI/EBNI position paper summarizes recommendations for training of cardiologists in endovascular treatment of acute ischaemic stroke. Interventional cardiologists adequately trained to perform endovascular stroke interventions could complement stroke teams to provide the 24/7 on call duty and thus to increase timely access of stroke patients to endovascular treatment. The training requirements for interventional cardiologists to perform endovascular therapy are described in details and should be based on two main principles: (i) patient safety cannot be compromised, (ii) proper training of interventional cardiologists should be under supervision of and guaranteed by a qualified neurointerventionist and within the setting of a stroke team. Interdisciplinary cooperation based on common standards and professional consensus is the key to the quality improvement in stroke treatment.


Subject(s)
Brain Ischemia , Endovascular Procedures , Ischemic Stroke , Stroke , Brain Ischemia/therapy , Humans , Stroke/therapy , Thrombectomy , Treatment Outcome
16.
Southwest J Pulm Crit Care ; 22(1): 23-25, 2021.
Article in English | MEDLINE | ID: mdl-33614198

ABSTRACT

BACKGROUND: Occupational exposures in mining and oil/gas extraction are known risk factors for thoracic malignancies (TMs). Given the relatively high proportion of these industries in New Mexico (NM), we conducted a feasibility study of adult lifetime occupational history among TM cases. We hypothesized a higher proportion of occupational TM in NM relative to the estimated national average of 10-14%. METHODS: We identified incident TM cases through the population-based New Mexico Tumor Registry (NMTR), from 2017-2018. Cases completed a telephone interview. An adjudication panel reviewed case histories and classified cancers as probable, possible, or non-occupational related, taking into account the presence, duration, and latency of exposures. We characterized recruitment and describe job titles and exposures among those with occupational TMs. We also compared the distributions of industry between those with and without occupational TM. RESULTS: The NMTR identified 400 eligible TM cases, 290 of which were available to be recruited (n=285 lung/bronchial cancer; n=5 mesotheliomas). Of the latter, 60% refused and 18% were deceased, 9% had invalid addresses, 11% were unable to be reached by telephone, and 3% were too ill to participate. The 43 cases who completed an interview held 236 jobs. A total of 33% of cases were classified as probable occupational TM and 5% as possible occupational TM. CONCLUSIONS: High rates of early mortality and refusals were significant barriers to study participation. Nonetheless, the proportion of probable occupational TMs greatly exceeded the estimated national average, highlighting the need for further study of occupational TM in the state.

17.
BJS Open ; 5(1)2021 01 08.
Article in English | MEDLINE | ID: mdl-33609373

ABSTRACT

BACKGROUND: Bibliometric and Altmetric analyses provide different perspectives regarding research impact. This study aimed to determine whether Altmetric score was associated with citation rate independent of established bibliometrics. METHODS: Citations related to a previous cohort of 100 most cited articles in surgery were collected and a 3-year interval citation gain calculated. Citation count, citation rate index, Altmetric score, 5-year impact factor, and Oxford Centre for Evidence-Based Medicine levels were used to estimate citation rate prospect. RESULTS: The median interval citation gain was 161 (i.q.r. 83-281); 74 and 62 articles had an increase in citation rate index (median increase 2.8 (i.q.r. -0.1 to 7.7)) and Altmetric score (median increase 3 (0-4)) respectively. Receiver operating characteristic (ROC) curve analysis revealed that citation rate index (area under the curve (AUC) 0.86, 95 per cent c.i. 0.79 to 0.93; P < 0.001) and Altmetric score (AUC 0.65, 0.55 to 0.76; P = 0.008) were associated with higher interval citation gain. An Altmetric score critical threshold of 2 or more was associated with a better interval citation gain when dichotomized at the interval citation gain median (odds ratio (OR) 4.94, 95 per cent c.i. 1.99 to 12.26; P = 0.001) or upper quartile (OR 4.13, 1.60 to 10.66; P = 0.003). Multivariable analysis revealed only citation rate index to be independently associated with interval citation gain when dichotomized at the median (OR 18.22, 6.70 to 49.55; P < 0.001) or upper quartile (OR 19.30, 4.23 to 88.15; P < 0.001). CONCLUSION: Citation rate index and Altmetric score appear to be important predictors of interval citation gain, and better at predicting future citations than the historical and established impact factor and Oxford Centre for Evidence-Based Medicine quality descriptors.


Subject(s)
Bibliometrics , Evidence-Based Medicine , General Surgery , Periodicals as Topic , Humans , Journal Impact Factor , Logistic Models , ROC Curve
18.
Catheter Cardiovasc Interv ; 97(5): 874-875, 2021 04 01.
Article in English | MEDLINE | ID: mdl-33089639

ABSTRACT

Team-based care has been emphasized as a strategy to improve and optimize outcomes for broad groups of patients who have presented with often complex medical conditions including large vessel cerebral occlusion. Although neurointerventionalists from different specialties perform mechanical embolectomy, which has become the standard of care for large vessel cerebral occlusion, these specialties are limited by relatively low numbers typically concentrated in a small number of sites. In this single center experience, approximately 50 patients with large vessel stroke were transferred out of an emergency room to other centers despite the availability of an experienced cardiologist with extensive carotid experience. Such transfer strategies typically result in delays in receiving reperfusion and, therefore, may decrease the success rates and substantial improvement that can be obtained by patients in this setting. Trained interventional cardiologists in centers with limited 24/7/365 coverage could achieve rapid revascularization and reperfusion saving lives. In order to accommodate the need for treating these patients, carotid stent trained cardiologists should enter the arena, learn mechanical embolectomy, and be supported by their colleagues from other disciplines on acute stroke care teams.


Subject(s)
Cardiologists , Cardiology , Endovascular Procedures , Stroke , Embolectomy , Endovascular Procedures/adverse effects , Humans , Stroke/diagnosis , Stroke/therapy , Thrombectomy , Treatment Outcome
19.
Phys Rev Lett ; 125(15): 155003, 2020 Oct 09.
Article in English | MEDLINE | ID: mdl-33095614

ABSTRACT

The implosion efficiency in inertial confinement fusion depends on the degree of stagnated fuel compression, density uniformity, sphericity, and minimum residual kinetic energy achieved. Compton scattering-mediated 50-200 keV x-ray radiographs of indirect-drive cryogenic implosions at the National Ignition Facility capture the dynamic evolution of the fuel as it goes through peak compression, revealing low-mode 3D nonuniformities and thicker fuel with lower peak density than simulated. By differencing two radiographs taken at different times during the same implosion, we also measure the residual kinetic energy not transferred to the hot spot and quantify its impact on the implosion performance.

SELECTION OF CITATIONS
SEARCH DETAIL
...