Abstract
Aims
Randomized controlled trials (RCTs) testing bleeding reduction strategies using antiplatelet treatment regimens (BRATs) in acute coronary syndromes (ACS) have shown promising results, ...but the generalizability of these findings may be significantly influenced by the ethnicity of the patients enrolled, given that East Asian (EA) patients show different ischaemic-bleeding risk profile compared to non-EA patients.
Methods and results
RCTs comparing a BRAT vs. standard 12-month dual antiplatelet therapy (DAPT) in patients with ACS undergoing percutaneous coronary intervention (PCI) were selected. The primary efficacy endpoint was major adverse cardiovascular events (MACE) as defined in each trial and the primary safety endpoint was minor or major bleeding. Twenty-six RCTs testing seven different BRATs were included. The only strategy associated with a trade-off in MACE was ‘upfront unguided de-escalation’ in the subgroup of non-EAs (risk ratio 1.16, 95% confidence interval 1.09–1.24). All but aspirin monotherapy-based strategies (i.e. ‘short and very short DAPT followed by aspirin’) were associated with reduced bleeding compared with standard DAPT in both EA and non-EA patients. There were no significant differences between subgroups, but the lack of RCTs in some of the included strategies and the difference in the certainty of evidence between EA and non-EA patients revealed that the evidence in support of different BRATs in ACS undergoing PCI is influenced by ethnicity. Moreover, absolute risk reduction estimation revealed that some BRATs might be more effective than others in reducing bleeding according to ethnicity.
Conclusion
The majority of BRATs are associated with reduced bleeding without any trade-off in hard ischaemic endpoints regardless of ethnicity. However, the supporting evidence and relative safety profiles of different BRATs might be significantly affected by ethnicity, which should be taken into account in clinical practice.
Study registration
This study is registered in PROSPERO (CRD42023416710).
We present a model for the process of the growth of carbon nanotubes (CNTs) obtained by chemical vapour deposition in the presence of transition metal nanoparticles (Me-NPs) which act as a catalyst. ...We have deduced that the growth of a CNT occurs in the presence of two forces: (i) a viscous force, due to the surrounding hot gas, which opposes and slows down the growth of the CNT, and (ii) an extrusive force that causes the growth and that in the steady-state stage of the growth is completely balanced by the viscous force. We believe that it is the great decrease in free energy in the assembling reaction that occurs at the interface of the Me-NP catalyst that causes the extrusive force for the growth of a CNT. Moreover, the process of chemisorption of a C2 fragment, through the interaction of the C2 system with the 3d metal orbitals, has been considered as well as the coordination action of the Fe, Ni and Co metal surfaces. The structural properties of the Fe, Co and Ni surfaces show that the (1, - 1, 0) planes of Fe and the (1, 1, 1) planes of Co and Ni exhibit the symmetry and distances required to overlap with the lattice of a graphene sheet. This gives us information about the coordination mechanism responsible for assembling the CNTs. In fact, we show that it is possible to cleave an Me-NP in such a way as to match the correct symmetry and dimension of the armchair structure of a single-walled nanotube. The mechanism of C2 addition at the edge of the growing CNT has also been considered in relation to the highest occupied molecular orbitallowest unoccupied molecular orbital (HOMOLUMO) symmetry. We demonstrate that the action of d orbitals of the metal atoms forming the Me-NP makes possible the thermally forbidden reaction, which involves the C2 system.
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We investigate the application of multilayer perceptron neural networks on the inversion of waveform governing parameters related to the seismic source and the propagation medium. These parameters ...are given by the size of the source, thicknesses and velocities of the layers, and a parameter κ describing the whole path attenuation of the wave due to absorption. Synthetic SH waves radiated from a circular source model are used for this study. The neural network returns a mapping function which can be used for an entire class of signals, provided that the parameters are within the limits of the model space explored during the training. The application of the mapping function to a set of signals is mathematically simple and fast. This can be a considerable advantage over systematic search techniques, such as simulated annealing or genetic algorithms, since the stability of the results that are found with the neural network can be tested easily with examples not used for the estimation of the mapping function. The use of an appropriate transform of the signal (i.e., spectra or autocorrelation function) gives slightly better results than the crude waveforms. The seismic waveform‐governing parameters can be identified with a reasonable accuracy if an appropriate network topology is chosen and if the number of examples used for the training phase is sufficiently large. Even in the case where 16 parameters of the models are searched and the global error remained somewhat unsatisfying, important parameters, such as the source radius or the velocity of the uppermost layers, are still recognized with a fair accuracy. The error is, at least to some degree, an effect of the nonuniqueness of the inversion problem. Performing a search with simulated annealing 31 times for an example seismogram, we obtain 31 solutions with a scatter for the different parameters which is of the same order as the errors obtained with the network.
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