5632 research outputs found
Sort by
An Investigation of Resonator Guitar Sound
No full textIdentified by the cones that transduce string vibration, resonator guitars have a sound quite distinct from the rest of acoustic guitars. Sound processing by the body is crucial. To illustrate that, a standard single-cone resonator is compared to two design variants, to a banjo, and to a flat-top wood guitar. Similarly played and recorded music is presented for reference. Likely candidates for signatures of the metallic sound are identified in spectrograms and spectra. Almost all of the discussion is descriptive. The only quantitative measurement and calculation relate static physical measurements to the observed main resonance of a cone
Realizing symmetry-protected topological phases in a spin-1/2 chain with next-nearest-neighbor hopping on superconducting qubits
No full textQuantum simulation on near-term quantum hardware is a topic of intense interest. The preparation of novel quantum states of matter provides a quantitative assessment of the capabilities of near-term digital quantum computers to implement circuits with structure of relevance to quantum simulation. Here, we conduct a benchmark study by realizing symmetry-protected topological (SPT) phases of a spin-1/2 Hamiltonian with next-nearest-neighbor hopping on up to 11 qubits on a programmable superconducting quantum processor using adiabatic state preparation. Using recompilation techniques to reduce the gate count to around 50 two-qubit gates, we observe clear signatures of the two distinct SPT phases, such as excitations localized to specific edges and finite string-order parameters. We identify a parasitic phase associated with the two-qubit gate as the dominant imperfection that limits the depth of the circuits, indicating a research topic of interest for future hardware development
Specifications of standards in systems and synthetic biology: status and developments in 2022 and the COMBINE meeting 2022
No full textThis special issue of the Journal of Integrative Bioinformatics contains updated specifications of COMBINE standards in systems and synthetic biology. The 2022 special issue presents three updates to the standards: CellML 2.0.1, SBML Level 3 Package: Spatial Processes, Version 1, Release 1, and Synthetic Biology Open Language (SBOL) Version 3.1.0. This document can also be used to identify the latest specifications for all COMBINE standards. In addition, this editorial provides a brief overview of the COMBINE 2022 meeting in Berlin
SpECTRE Cauchy-characteristic evolution system for rapid, precise waveform extraction
No full textWe give full details regarding the new Cauchy-characteristic evolution (CCE) system in spectre. The implementation is built to provide streamlined flexibility for either extracting waveforms during the process of a spectre binary compact object simulation or as a stand-alone module for extracting waveforms from worldtube data provided by another code base. Using our recently presented improved analytic formulation, the CCE system is free of pure-gauge logarithms that would spoil the spectral convergence of the scheme. It gracefully extracts all five Weyl scalars, in addition to the news and the strain. The spectre CCE system makes significant improvements on previous implementations in modularity, ease of use, and speed of computation
The 2022 Chihshang, Taiwan, Earthquake: Initial GEER Team Observations
No full textWe recently returned from a post-earthquake reconnaissance trip to Taiwan sponsored by the National Science Foundation–funded Geoengineering Extreme Events Reconnaissance (GEER) Association. We studied the effects of the September 18, 2022 MW6.9 Chihshang, Taiwan earthquake. The earthquake occurred on the Central Range strike-slip fault, with the rupture direction extending north from the epicenter. Nearfield seismic stations measured peak ground accelerations (PGAs) exceeding 0.5g along the fault. Peak ground velocities (PGVs) increased in the direction of the rupture with average intensities of 8 cm/s near the epicenter, increasing along the fault to 89 cm/s
at the northern terminus. The ground motion recordings of the east (approximately fault parallel) component indicated strong velocity pulses in the direction of the rupture (Fig. 1)
Durability and long-term behaviour of shape memory polymers and composites for the space industry - A review of current status and future perspectives
No full textRapid developments in thermoset and thermoplastic shape memory polymers (SMPs) during the last two decades have increased their engineering applications significantly. For this reason, many researchers have begun evaluating the durability of SMPs and SMP composites (SMPCs) to ensure the sustainability of the applications. This review has thoroughly investigated available research works conducted on the durability of SMPs and SMPCs during the past two decades. Such a thorough investigation had not been conducted to this point. Important time-dependant characteristics of SMPs such as thermal cycles and creep are discussed in detail. Furthermore, the long-term effects of exposure to high-energy electromagnetic waves such as UV and gamma rays as well as high-energy particle interactions such as that of atomic Oxygen, protons and electrons at higher altitudes are reported comprehensively. The long-term behaviour of thermo-mechanical properties and shape memory effects of each SMP are highlighted appropriately in the relevant sections of the article. The authors also highlight gaps in the current knowledge base and suggest recommendations for developing more durable SMP reinforced composites for future uses. For this work, the authors accessed the major material research databases using a few keywords and selected 460 research papers. Later, the search results were filtered to 168 research papers which are discussed in this review
Precision sirolimus dosing in children: The potential for model-informed dosing and novel drug monitoring
No full textThe mTOR inhibitor sirolimus is prescribed to treat children with varying diseases, ranging from vascular anomalies to sporadic lymphangioleiomyomatosis to transplantation (solid organ or hematopoietic cell). Precision dosing of sirolimus using therapeutic drug monitoring (TDM) of sirolimus concentrations in whole blood drawn at the trough (before the next dose) time-point is the current standard of care. For sirolimus, trough concentrations are only modestly correlated with the area under the curve, with R² values ranging from 0.52 to 0.84. Thus, it should not be surprising, even with the use of sirolimus TDM, that patients treated with sirolimus have variable pharmacokinetics, toxicity, and effectiveness. Model-informed precision dosing (MIPD) will be beneficial and should be implemented. The data do not suggest dried blood spots point-of-care sampling of sirolimus concentrations for precision dosing of sirolimus. Future research on precision dosing of sirolimus should focus on pharmacogenomic and pharmacometabolomic tools to predict sirolimus pharmacokinetics and wearables for point-of-care quantitation and MIPD
Quantized topological response in trapped quantum gases
No full textWe study the quantized topological response of trapped one-dimensional quantum gases, which involves applying an optical pulse to a half-infinite region in an asymptotically harmonic trap and measuring the resulting density distribution. We prove that the corresponding linear response is described by a universal quantized formula in the thermodynamic limit, which is invariant under local continuous deformations of the trapping potential V, atom distribution f_Λ, the spatial envelope of the optical pulse Θₚ, and the measurement region Θₘ. Our numerical analysis confirms this prediction with high accuracy, and we show that a short but finite optical pulse duration only causes a violation of quantization near the transition time. Our work presents an exciting avenue for exploring quantized topological phenomena in trapped quantum gases
A multi-institutional study using artificial intelligence to provide reliable and fair feedback to surgeons
No full textBackground. Surgeons who receive reliable feedback on their performance quickly master the skills necessary for surgery. Such performance-based feedback can be provided by a recently-developed artificial intelligence (AI) system that assesses a surgeon’s skills based on a surgical video while simultaneously highlighting aspects of the video most pertinent to the assessment. However, it remains an open question whether these highlights, or explanations, are equally reliable for all surgeons.
Methods. Here, we systematically quantify the reliability of AI-based explanations on surgical videos from three hospitals across two continents by comparing them to explanations generated by humans experts. To improve the reliability of AI-based explanations, we propose the strategy of training with explanations –TWIX –which uses human explanations as supervision to explicitly teach an AI system to highlight important video frames.
Results. We show that while AI-based explanations often align with human explanations, they are not equally reliable for different sub-cohorts of surgeons (e.g., novices vs. experts), a phenomenon we refer to as an explanation bias. We also show that TWIX enhances the reliability of AI-based explanations, mitigates the explanation bias, and improves the performance of AI systems across hospitals. These findings extend to a training environment where medical students can be provided with feedback today.
Conclusions. Our study informs the impending implementation of AI-augmented surgical training and surgeon credentialing programs, and contributes to the safe and fair democratization of surgery
Performance and Next-Generation Development of the Finite-Fault Rupture Detector (FinDer) within the United States West Coast ShakeAlert Warning System
No full textRapid fault rupture information is important to estimate seismic ground motions and damage in large earthquakes, and is, therefore, of great value for earthquake early warning (EEW) and rapid response. The Finite-Fault Rupture Detector (FinDer) algorithm computes earthquake line-source models by comparing spatial distributions of high-frequency seismic amplitudes with precomputed template maps. FinDer is one of two seismic EEW algorithms currently adopted by the United States West Coast ShakeAlert EEW system. Between March 2018 and October 2022, FinDer detected 1048 earthquakes (2.3 ≤ M ≤ 7.1) inside the FinDer-reporting region in California, Oregon, and Washington with a median detection time of 8.5 s (75th and 95th percentile: 11.5 s, 38.9 s) after event origin and median errors (first report) of 6.7 km (75th and 95th percentile: 10.5 km, 25.5 km) in location, −0.45 s (mean ± st. dev.: 0.1 ± 5.9 s) in origin time, and 0.33 units (mean ± st. dev.: 0.33 ± 0.31 m.u.) in magnitude. Ground motions estimated using FinDer source parameters are in excellent agreement with observed peak ground accelerations, and residuals are, on average, 30% smaller than if predicted from catalog source parameters. This suggests that FinDer’s simple source parameter terms are accounting for more complex high-frequency source characteristics. This article summarizes the performance of FinDer in ShakeAlert and describes the recent improvements to the algorithm addressing issues encountered during real-time operation. This includes the handling of latent seismic data, robust event detection in regions with sparse instrumentation, enabling faster magnitude convergence in large earthquakes, use of fault- and scenario-specific earthquakes (e.g., along the Cascadia subduction zone or San Andreas fault), as well as increased robustness of FinDer in complex earthquake sequences. We demonstrate the performance of the new FinDer version 3 algorithm using waveform playbacks of selected events along the U.S. West Coast, Japan, and China, including both historic and synthetic earthquakes