Objectives This study sought to evaluate the safety and efficacy of the CoreValve transcatheter heart valve (THV) for the treatment of severe aortic stenosis in patients at extreme risk for surgery. ...Background Untreated severe aortic stenosis is a progressive disease with a poor prognosis. Transcatheter aortic valve replacement (TAVR) with a self-expanding bioprosthesis is a potentially effective therapy. Methods We performed a prospective, multicenter, nonrandomized investigation evaluating the safety and efficacy of self-expanding TAVR in patients with symptomatic severe aortic stenosis with prohibitive risks for surgery. The primary endpoint was a composite of all-cause mortality or major stroke at 12 months, which was compared with a pre-specified objective performance goal (OPG). Results A total of 41 sites in the United States recruited 506 patients, of whom 489 underwent attempted treatment with the CoreValve THV. The rate of all-cause mortality or major stroke at 12 months was 26.0% (upper 2-sided 95% confidence bound: 29.9%) versus 43.0% with the OPG (p < 0.0001). Individual 30-day and 12-month events included all-cause mortality (8.4% and 24.3%, respectively) and major stroke (2.3% and 4.3%, respectively). Procedural events at 30 days included life-threatening/disabling bleeding (12.7%), major vascular complications (8.2%), and need for permanent pacemaker placement (21.6%). The frequency of moderate or severe paravalvular aortic regurgitation was lower 12 months after self-expanding TAVR (4.2%) than at discharge (10.7%; p = 0.004 for paired analysis). Conclusions TAVR with a self-expanding bioprosthesis was safe and effective in patients with symptomatic severe aortic stenosis at prohibitive risk for surgical valve replacement. (Safety and Efficacy Study of the Medtronic CoreValve System in the Treatment of Symptomatic Severe Aortic Stenosis in High Risk and Very High Risk Subjects Who Need Aortic Valve Replacement; NCT01240902 )
Transcatheter aortic-valve replacement with a new self-expanding prosthesis was compared with surgical aortic-valve replacement in patients with aortic stenosis who were at high surgical risk. The ...rate of death from any cause at 1 year was lower in the TAVR group.
Aortic stenosis is a debilitating disease in elderly persons that carries a dismal prognosis after symptom onset.
1
Although surgical aortic-valve replacement remains the standard treatment for aortic stenosis,
2
many patients are not suitable candidates for surgical replacement owing to an increased risk of death during surgery.
3
,
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Transcatheter aortic-valve replacement (TAVR) with a balloon-expandable device improves survival, as compared with medical therapy, in patients with severe aortic stenosis who cannot undergo surgery.
5
Balloon-expandable TAVR and surgical aortic-valve replacement are associated with similar survival rates at 1 year among patients considered to be at high surgical risk, although the frequency of . . .
Collectively Encoded Rydberg Qubit Spong, Nicholas L. R.; Jiao, Yuechun; Hughes, Oliver D. W. ...
Physical review letters,
08/2021, Letnik:
127, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We demonstrate a collectively encoded qubit based on a single Rydberg excitation stored in an ensemble of N entangled atoms. Qubit rotations are performed by applying microwave fields that drive ...excitations between Rydberg states. Coherent readout is performed by mapping the excitation into a single photon. Ramsey interferometry is used to probe the coherence of the qubit, as well as to test the robustness to external perturbations. We show that qubit coherence is preserved even as we lose atoms from the polariton mode, preserving Ramsey fringe visibility. We show that dephasing due to electric field noise scales as the fourth power of field amplitude. These results show that robust quantum information processing can be achieved via collective encoding using Rydberg polaritons, and hence this system could provide an attractive alternative coding strategy for quantum computation and networking.
The CoreValve U.S. Pivotal High Risk Trial was the first randomized trial to show superior 1-year mortality of transcatheter aortic valve replacement (TAVR) compared with surgical aortic valve ...replacement (SAVR) among high operative mortality–risk patients.
The authors sought to compare TAVR to SAVR for mid-term 5-year outcomes of safety, performance, and durability.
Surgical high-risk patients were randomized (1:1) to TAVR with the self-expanding bioprosthesis or SAVR. VARC-1 (Valve Academic Research Consortium I) definitions were applied. Severe hemodynamic structural valve deterioration was defined as a mean gradient ≥40 mm Hg or a change in gradient ≥20 mm Hg or new severe aortic regurgitation. Five-year follow-up was planned.
A total of 797 patients were randomized at 45 U.S. centers, of whom 750 underwent an attempted implant (TAVR = 391, SAVR = 359). The overall mean age was 83 years, and the STS score was 7.4%. All-cause mortality rates at 5 years were 55.3% for TAVR and 55.4% for SAVR. Subgroup analysis showed no differences in mortality. Major stroke rates were 12.3% for TAVR and 13.2% for SAVR. Mean aortic valve gradients were 7.1 ± 3.6 mm Hg for TAVR and 10.9 ± 5.7 mm Hg for SAVR. No clinically significant valve thrombosis was observed. Freedom from severe SVD was 99.2% for TAVR and 98.3% for SAVR (p = 0.32), and freedom from valve reintervention was 97.0% for TAVR and 98.9% for SAVR (p = 0.04). A permanent pacemaker was implanted in 33.0% of TAVR and 19.8% of SAVR patients at 5 years.
This study shows similar mid-term survival and stroke rates in high-risk patients following TAVR or SAVR. Severe structural valve deterioration and valve reinterventions were uncommon. (Safety and Efficacy Study of the Medtronic CoreValve® System in the Treatment of Symptomatic Severe Aortic Stenosis in High Risk and Very High Risk Subjects Who Need Aortic Valve Replacement; NCT01240902)
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Pembrolizumab and pembrolizumab-chemotherapy demonstrated efficacy in recurrent/metastatic head and neck squamous cell carcinoma in KEYNOTE-048. Post hoc analysis of long-term efficacy and ...progression-free survival on next-line therapy (PFS2) is presented.
Patients were randomly assigned (1:1:1) to pembrolizumab, pembrolizumab-chemotherapy, or cetuximab-chemotherapy. Efficacy was evaluated in programmed death ligand 1 (PD-L1) combined positive score (CPS) ≥ 20, CPS ≥ 1, and total populations, with no multiplicity or alpha adjustment.
The median study follow-up was 45.0 months (interquartile range, 41.0-49.2; n = 882). At data cutoff (February 18, 2020), overall survival improved with pembrolizumab in the PD-L1 CPS ≥ 20 (hazard ratio HR, 0.61; 95% CI, 0.46 to 0.81) and CPS ≥ 1 populations (HR, 0.74; 95% CI, 0.61 to 0.89) and was noninferior in the total population (HR, 0.81; 95% CI, 0.68 to 0.97). Overall survival improved with pembrolizumab-chemotherapy in the PD-L1 CPS ≥ 20 (HR, 0.62; 95% CI, 0.46 to 0.84), CPS ≥ 1 (HR, 0.64; 95% CI, 0.53 to 0.78), and total (HR, 0.71; 95% CI, 0.59 to 0.85) populations. The objective response rate on second-course pembrolizumab was 27.3% (3 of 11). PFS2 improved with pembrolizumab in the PD-L1 CPS ≥ 20 (HR, 0.64; 95% CI, 0.48 to 0.84) and CPS ≥ 1 (HR, 0.79; 95% CI, 0.66 to 0.95) populations and with pembrolizumab-chemotherapy in the PD-L1 CPS ≥ 20 (HR, 0.64; 95% CI, 0.48 to 0.86), CPS ≥ 1 (HR, 0.66; 95% CI, 0.55 to 0.81), and total (HR, 0.73; 95% CI, 0.61 to 0.88) populations. PFS2 was similar after pembrolizumab and longer after pembrolizumab-chemotherapy on next-line taxanes and shorter after pembrolizumab and similar after pembrolizumab-chemotherapy on next-line nontaxanes.
With a 4-year follow-up, first-line pembrolizumab and pembrolizumab-chemotherapy continued to demonstrate survival benefit versus cetuximab-chemotherapy in recurrent/metastatic head and neck squamous cell carcinoma. Patients responded well to subsequent treatment after pembrolizumab-based therapy.
The estimation of the thermochemical radius is very important because most of the properties of the electrolyte solutions are, to some extent, linked to this property. Also, these thermochemical ...radii can be used to estimate lattice energies, which can be a very important parameter to be evaluated when assessing the possibility of synthesizing new inorganic materials. This study presents a formulation for estimating the thermochemical radii of complex ions. More specifically, these thermochemical radii are estimated using a weighted sum based on the radii of the contributing cations and anions. Also, the influence of the ionic charge on these thermochemical radii is assessed and discussed. Finally, the parameters obtained from the estimation of the thermochemical radii of complex cations are used to estimate cation volumes, and this estimation is then validated through comparison with literature values. As a result, the equations developed for thermochemical radii of complex ions produce predictions that are accurate to within 15% in general, whereas the equation developed to estimate cation volumes produces predictions that are accurate to within 20% considering cation volumes greater than 70 Å3.
•New Aspen Plus/MATLAB kinetic model for the downdraft gasifier.•Realistic representation of the non-condensable gas release.•The model is validated against several woody biomass types.•Prediction of ...the gasifier performance under different power loads.
Biomass gasification technology is evolving and more research through modelling alongside the experimental work needs to be performed. In the past, all the attention has been concentrated on the combustion and reduction stages to be the controlling reactions while the pyrolysis is modelled as an instantaneous process. In this study, a new enhanced model for the gasification process in the downdraft reactor is proposed with a more realistic representation of the pyrolysis stage as a temperature-dependent sequential release of gases. The evolution of the pyrolysis gas, followed by the combustion and reduction reactions, are kinetically controlled in the proposed model which is developed within the Aspen Plus software package. The simulation of the reactor temperature profile and the evolution of the pyrolysis gas is carried out in an integrated MATLAB and Aspen Plus model. The proposed model has been validated against experimental data obtained from the gasification of different woody biomass types and considering a range of scale reactor and power loads. The predicted results are in very good agreement with the experimental data, and therefore the model can be used with confidence to perform a sensitivity analysis to predict the performance of a gasifier at different load levels corresponding to the air flow rate range of 3–10 L/s. As the supplied air flow rate increases, the LHV decreases but the gas yield behaves conversely, and in turn the cold gas efficiency is maintained at a good level of energy conversion at ≥ 70%. Furthermore, the variation in the biomass moisture content, which is commonly in the range of 5–25 % has a significant effect on the gasification efficiency. Such that biomass that has a high moisture content substantially reduces the CO content and consequently the LHV of the produced gas. Hence, it is important to maintain the moisture content at the lowest level.
Purpose
Anterior cruciate ligament (ACL) graft failure is a complication that may require revision ACL reconstruction (ACL-R). Non-anatomic placement of the femoral tunnel is thought to be a frequent ...cause of graft failure; however, there is a lack of evidence to support this belief. The purpose of this study was to determine if non-anatomic femoral tunnel placement is associated with increased risk of revision ACL-R.
Methods
After screening all 315 consecutive patients who underwent primary single-bundle ACL-R by a single senior orthopedic surgeon between January 2012 and January 2017, 58 patients were found to have both strict lateral radiographs and a minimum of 24 months follow-up without revision. From a group of 456 consecutive revision ACL-R, patients were screened for strictly lateral radiographs and 59 patients were included in the revision group. Femoral tunnel placement for each patient was determined using a strict lateral radiograph taken after the primary ACL-R using the quadrant method. The center of the femoral tunnel was measured in both the posterior–anterior (PA) and proximal–distal (PD) dimensions and represented as a percentage of the total distance (normal center of anatomic footprint: PA 25% and PD 29%).
Results
In the PA dimension, the revision group had significantly more anterior femoral tunnel placement compared with the primary group (38% ± 11% vs. 28% ± 6%,
p
< 0.01). Among patients who underwent revision; those with non-traumatic chronic failure had statistically significant more anterior femoral tunnel placement than those who experienced traumatic failure (41% ± 13% vs. 35% ± 8%,
p
< 0.03). In the PD dimension, the revision group had significantly more proximal femoral tunnel placement compared with the primary group (30% ± 9% vs 38% ± 9%,
p
< 0.01).
Conclusion
In this retrospective study of 58 patients with successful primary ACL-R compared with 59 patients with failed ACL-R, anterior and proximal (high) femoral tunnels for ACL-R were shown to be independent risk factors for ACL revision surgery. As revision ACL-R is associated with patient- and economic burden, particular attention should be given to achieving an individualized, anatomic primary ACL-R. Surgeons may reduce the risk of revision ACL-R by placing the center of the femoral tunnel within the anatomic ACL footprint.
Level of evidence
Level III.
•A hybrid SE and ORC driven μ-CCHP energy model fueled by biomass was developed.•Impact of key parameters and quality of fuel on the μ-CCHP have been investigated.•Hybridisation of SE and ORC ...significantly improved the performance of the system.•Simulated results revealed system’s performance and support its sizing optimisation.•Proposed system offers promising gains over separate production of energy vectors.
Stirling engines (SE) offer good part load performance and high heat sink temperatures which make it a suitable candidate to serve as a prime mover in micro-combined cooling, heating and power (μ-CCHP) applications. In this study, a novel μ-CCHP configuration hybridising a SE prime mover with an ORC to utilise the waste heat from the SE to produce additional power is proposed. Additional waste heat was recovered from the flue gas to dry the biomass feedstock, fire a thermal chiller and produce hot water. Further, a non-ideal thermal model was formulated and implemented in MATLAB to model the SE prime mover while the models of the other subsystems were implemented in Aspen plus®. Also, the control of the subsystems of the μ-CCHP was achieved in MATLAB by establishing a connection between the software and Aspen plus®. A detailed sensitivity analysis was conducted to study the influence of cooling and heating loads, rotational speed of the prime mover and quality of the biomass fuel on the energy utilisation factor, primary energy savings (PES), CO2 emissions reduction (CO2ER) and exergy efficiency of the μ-CCHP system. It was found that hybridising SE and ORC increased the power output and thermal efficiency of the standalone SE by 66% and 63.4%, respectively at its operating speed of 2500 rpm, and also improved the performance at high rotational speeds. Further, the deployment of hybrid prime movers in the design of the μ-CCHP yielded high PES and CO2ER of 55% and 43%, respectively when the system utilised woodchips fuel containing 10% moisture. The proposed energy system performs better than conventional energy systems producing only one energy vector over a wide range of engine frequencies, cooling ratios and woodchips compositions.
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•Techno-economic and life cycle assessment of sustainable aviation fuel within BECCS.•The inclusion of CCS increases the minimum selling price of SAF by 7.9%.•The inclusion of CCS ...achieves negative-emissions.•The costs are sensitive to feedstock price and CAPEX.•The GWP is sensitive to the amount of CO2 separated from the syngas.•The implementation of relevant policies can provide profit generation scenarios.
In this study, the economic and environmental feasibility of a process configuration based on the Bioenergy and Carbon Capture and Storage (BECCS) concept is assessed. The research analyses the production of jet fuel from forestry residues-derived syngas via the Fischer-Tropsch (FT) technology. Further, the CO2 removed in the syngas cleaning section is not released to the environment, instead it is permanently sequestrated. The produced Sustainable Aviation Fuel (SAF) has the potential to achieve negative emissions. The present research is a one-of-a-kind study for the jet fuel production within the BECCS concept. The process has been modelled within the Aspen Plus and Matlab software to obtain detailed and realistic mass and energy balances. Based on these balances, the technical, economic and environmental parameters have been calculated. Based on a plant that treats 20 dry-t/h of forest residues, 1.91 t/h of jet fuel are produced, while 11.26 t/h of CO2 are permanently stored. The inclusion of the CCS chain in the biorefinery increase the minimum jet fuel selling price from 3.03 £/kg to 3.27 £/kg. The LCA results for global warming show a favourable reduction in the BECCS case, in which negative emissions of −121.83 gCO2eq/MJ of jet fuel are achieved, while without CCS case exhibits GHG emissions equal to 15.51 gCO2eq/MJ; in both cases, the multi-functionality is faced with an energy allocation approach. It is, then, evident the significant environmental advantages of the BECCS process configuration. Nevertheless, financial feasibility can only be attained through the implementation of existing policy schemes and the formulation of new strategies that would reward negative emissions. The application of the UK’s policy “Renewable Transport Fuel Obligation” and a hypothetical scheme that rewards negative CO2 emissions, breaks-even the Minimum Jet fuel Selling Price (MJSP) at 1.49 £/kg for a certificate and carbon price of 0.20 £/certificate and 246.64 £/tonne of CO2.
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