5,710 research outputs found

    Long time clinical outcomes of limus-eluting stent versus paclitaxel-eluting stent in patients undergoing percutaneous coronary artery intervention: A meta-analysis of randomized controlled clinical trials

    Get PDF
    Background: The meta-analysis was aimed to compare the long time (> 2 year) clinical outcomes of limus-based stents (LBS) and paclitaxel-eluting stents (PES). LBS and PES are two kinds of most common coronary artery stents in clinics.Methods: Electronic data bases of PubMed, Cochrane, and EMBASE were searched. We included randomized controlled clinical trials (RCT) comparing LBS and PES with long time clinical outcomes. Methodological quality of eligible trials was assessed using “risk of bias” tool. The efficacy endpoints included target lesion revascularization (TLR), target vessel revascularization (TVR), and stent thrombosis (ST), and the safety endpoints included all cause death, cardiac death, and myocardial infarction (MI). Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated for each endpoint.Results: A total of 23 RCTs and 19,319 participants were included and analyzed in this meta-analysis. All trials were of an acceptable quality. At 2 years, LBS showed reduced risk of revascularization and ST (TLR: OR = 0.59, 95% CI 0.44–0.78; TVR: OR = 0.63, 95% CI 0.55–0.71; ST: OR = 0.55, 95% CI 0.41–0.73) and a lower rate of MI (OR = 0.67, 95% CI 0.57–0.79). Subgroup analysis showed that both everolimus-eluting stents and sirolimus-eluting stents had better clinical outcomes compared with PES. The comparisons of 3, 4 and 5 year follow-up results revealed that the clinical outcomes of PES were non-inferior to those of LBS but LBS was associated with reduced risk of MI and ST at 3 years.Conclusions: LBS is associated with better clinical outcomes at 2 years. Both LBS and PES showed similar efficacy and safety at long time period.

    Towards a reliable prediction of the infrared spectra of cosmic fullerenes and their derivatives in the JWST era

    Full text link
    Fullerenes, including C60, C70, and C60+, are widespread in space through their characteristic infrared vibrational features (C60+ also reveals its presence in the interstellar medium through its electronic transitions) and offer great insights into the carbon chemistry and stellar evolution. The potential existence of fullerene-related species in space has long been speculated and recently put forward by a set of laboratory experiments of C60+, C60H+, C60O+, C60OH+, C70H+, and [C60-Metal]+ complexes. The advent of the James Webb Space Telescope (JWST) provides a unique opportunity to search for these fullerene-related species in space. To facilitate JWST search, analysis, and interpretation, an accurate knowledge of their vibrational properties is essential. Here, we compile a VibFullerene database and conduct a systematic theoretical study on those species. We derive a set of range-specific scaling factors for vibrational frequencies, to account for the deficiency of density functional theory calculations in predicting the accurate frequencies. Scaling factors with low root-mean-square and median errors for the frequencies are obtained, and their performance is evaluated, from which the best-performing methods are recommended for calculating the infrared spectra of fullerene derivatives which balance the accuracy and computational cost. Finally, the recommended vibrational frequencies and intensities of fullerene derivatives are presented for future JWST detection.Comment: 19 pages, 8 figures, 5 tables. Accepted for publication in MNRA

    Realizing bending waveguides with anisotropic epsilon-near-zero metamaterials

    Full text link
    We study metamaterials with an anisotropic effective permittivity tensor in which one component is near zero. We find that such an anisotropic metamaterial can be used to control wave propagation and construct almost perfect bending waveguides with a high transmission rate (>95%). This interesting effect originates in the power flow redistribution by the surface waves on the input and output interfaces, which smoothly matches with the propagating modes inside the metamaterial waveguide. We also find that waves in such anisotropic epsilon-near-zero materials can be reflected by small-sized perfect magnetic conductor defects. Numerical calculations have been performed to confirm the above effects

    Radial Angular Momentum Transfer and Magnetic Barrier for Short-Type Gamma-Ray Burst Central Engine Activity

    Get PDF
    Soft extended emission (EE) following initial hard spikes up to 100 seconds was observed with {\em Swift}/BAT for about half of short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of the black hole-neutron star merger models, we study the roles of the radial angular momentum transfer in the disk and the magnetic barrier around the black hole for the activity of SGRB central engines. We show that the radial angular momentum transfer may significantly prolong the lifetime of the accretion process and multiple episodes may be switched by the magnetic barrier. Our numerical calculations based on the models of the neutrino-dominated accretion flows suggest that the disk mass is critical for producing the observed EE. In case of the mass being 0.8M\sim 0.8M_{\odot}, our model can reproduce the observed timescale and luminosity of both the main and EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE with about one order of magnitude and the timescale is shorter than 20 seconds if the disk mass being 0.2M\sim 0.2M_{\odot}. {\em Swift}/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component would be a probe for merger process and disk formation for compact star mergers.Comment: 9 pages, 3 figures, accepted for publication in Ap

    Pentagon, Hexagon, or Bridge? Identifying the Location of a Single Vanadium Cation on Buckminsterfullerene Surface

    Full text link
    Buckminsterfullerene C60 has received extensive research interest ever since its discovery. In addition to its interesting intrinsic properties of exceptional stability and electron-accepting ability, the broad chemical tunability by decoration or substitution on the C60-fullerene surface makes it a fascinating molecule. However, to date there is uncertainty about the binding location of such decorations on the C60 surface, even for a single adsorbed metal atom. In this work, we report the gas-phase synthesis of the C60V+ complex and its in-situ characterization by mass spectrometry and in-frared spectroscopy with the help of quantum chemical calculations and molecular dynamics simulations. We identify the most probable binding position of a vanadium cation on C60 above a pentagon center in eta5-fashion, demonstrate a high thermal stability for this complex, and explore the bonding nature between C60 and the vanadium cation, reveal-ing that large orbital and electrostatic interactions lie at the origin of the stability of the eta5-C60V+ complex.Comment: 29 pages (11 pages for main text and 17 pages for the supporting information

    Tunable superluminal propagation at spectral hole-burning regions in magneto-optical atomic medium

    Get PDF
    In the context of spectral hole-burning, normal dispersion with subluminal propagation is usually observed in the spectral hole-burning depth region. However, anomalous dispersion can occur in the continuous absorption peak region, which leads to superluminal light propagation. In this paper, we report an unusual behavior of dispersion at discontinued absorption kink regions. We demonstrate both normal dispersion at the kink absorption region and anomalous dispersion at the spectral hole-burning depth region. The unusual dispersion leads to a positive group index in the absorption kink region and a negative group index in the spectral hole-burning depth region. The spectral hole-burning is due to variation of magnetization rather than the molecular distribution. The outcomes of our work offer promising applications in communication technologies and storage devices

    VITATECS: A Diagnostic Dataset for Temporal Concept Understanding of Video-Language Models

    Full text link
    The ability to perceive how objects change over time is a crucial ingredient in human intelligence. However, current benchmarks cannot faithfully reflect the temporal understanding abilities of video-language models (VidLMs) due to the existence of static visual shortcuts. To remedy this issue, we present VITATECS, a diagnostic VIdeo-Text dAtaset for the evaluation of TEmporal Concept underStanding. Specifically, we first introduce a fine-grained taxonomy of temporal concepts in natural language in order to diagnose the capability of VidLMs to comprehend different temporal aspects. Furthermore, to disentangle the correlation between static and temporal information, we generate counterfactual video descriptions that differ from the original one only in the specified temporal aspect. We employ a semi-automatic data collection framework using large language models and human-in-the-loop annotation to obtain high-quality counterfactual descriptions efficiently. Evaluation of representative video-language understanding models confirms their deficiency in temporal understanding, revealing the need for greater emphasis on the temporal elements in video-language research.Comment: 23 pages, 6 figures, 18 tables, data is available at https://github.com/lscpku/VITATEC
    corecore