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"Kun Yu"
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Observation of the exceptional-point-enhanced Sagnac effect
Exceptional points (EPs) are special spectral degeneracies of non-Hermitian Hamiltonians that govern the dynamics of open systems. At an EP, two or more eigenvalues, and the corresponding eigenstates, coalesce
1
–
3
. Recently, it was predicted that operation of an optical gyroscope near an EP results in improved response to rotations
4
,
5
. However, the performance of such a system has not been examined experimentally. Here we introduce a precisely controllable physical system for the study of non-Hermitian physics and nonlinear optics in high-quality-factor microresonators. Because this system dissipatively couples counter-propagating lightwaves within the resonator, it also functions as a sensitive gyroscope for the measurement of rotations. We use our system to investigate the predicted EP-enhanced Sagnac effect
4
,
5
and observe a four-fold increase in the Sagnac scale factor by directly measuring rotations applied to the resonator. The level of enhancement can be controlled by adjusting the system bias relative to the EP, and modelling results confirm the observed enhancement. Moreover, we characterize the sensitivity of the gyroscope near the EP. Besides verifying EP physics, this work is important for the understanding of optical gyroscopes.
precisely controllable integrated optical gyroscope based on stimulated Brillouin scattering is used to study non-Hermitian physics, revealing a four-fold enhancement of the Sagnac scale factor near exceptional points.
Journal Article
لقاء في القرية العالمية = An encounter in the global village : قصص مختارة من المؤتمر الدولي الرابع عشر للقصة القصيرة
هذا الكتاب يحتوي على قصص مختارة من المؤتمر الدولي الرابع عشر للقصة القصيرة وهذا اللقاء الذي نظم من قبل جمعية دراسة القصص القصيرة الإنجليزية (أس أس أس أس إي) وهي جمعية عالمية أنشئت في الولايات المتحدة عام 1992 وينعقد كل عامين ويعتبر اللقاء العالمي الوحيد الذي يركز بشكل خاص على دراسات القصة القصيرة أما القصص المشاركة في اللقاء فهي مكتوبة من قبل 29 كاتبا ينتمون إلى عشرة دول هي الصين وتايوان والهند والولايات المتحدة وكندا ونيوزلندا وفرنسا وإيرلندا والنمسا وسنغافورا وجامايكا.
BOOK
Adaptive Bi-Directional LSTM Short-Term Load Forecasting with Improved Attention Mechanisms
Special load customers such as electric vehicles are emerging in modern power systems. They lead to a higher penetration of special load patterns, raising difficulty for short-term load forecasting (STLF). We propose a hierarchical STLF framework to improve load forecasting accuracy. An improved adaptive K-means clustering algorithm is designed for load pattern recognition and avoiding local sub-optimal clustering centroids. We also design bi-directional long-short-term memory neural networks with an attention mechanism to filter important load information and perform load forecasting for each recognized load pattern. The numerical results on the public load dataset show that our proposed method effectively forecasts the residential load with a high accuracy.
Journal Article
Earth rotation measured by a chip-scale ring laser gyroscope
Optical gyroscopes are among the most accurate rotation measuring devices and are widely used for navigation and accurate pointing. Since the advent of photonic integrated components for communications, and with their increasing complexity, there has been interest in the possibility of chip-scale optical gyroscopes1. Besides the potential benefits of integration, such solid-state systems would be robust and resistant to shock. Here, we report a gyroscope using Brillouin ring lasers on a silicon chip. Its stability and sensitivity enable measurement of Earth’s rotation, representing a major milestone for this new class of gyroscope.A Sagnac gyroscope based on Brillouin ring lasers on a silicon chip is presented. The stability and sensitivity of this on-chip planar gyroscope allow measurement of the Earth’s rotation, with an amplitude sensitivity as small as 5 deg h−1 for a sinusoidal rotation, an angle random walk of 0.068 deg h−1/2 and bias instability of 3.6 deg h−1.
Journal Article
Does Recognition versus Disclosure Affect Value Relevance? Evidence from Pension Accounting
This study examines whether institutional ownership and analyst following affect the value relevance of disclosed versus recognized pension liabilities. Using a sample of firms with pension liabilities that were disclosed under SFAS No. 87 and subsequently recognized under SFAS No. 158 from 1999 to 2007, I find that off-balance-sheet pension liabilities are more value relevant for firms with a higher level of institutional ownership or analyst following in the pre-158 period. More importantly, I find that SFAS No. 158 increases the value relevance of previously disclosed off-balance-sheet pension liabilities for firms with a low level of institutional ownership or analyst following, and that the increase in the value relevance becomes less pronounced for firms with a higher level of institutional ownership or analyst following. Overall, the results are consistent with the view that institutional ownership and analyst following affect the value relevance of disclosed information as well as the valuation difference between disclosed and recognized information. This study also highlights the importance of considering institutional ownership and analyst following in the value-relevance research.
Journal Article
Framing the challenges of artificial intelligence in medicine
[...]even in cases of overwhelming public good such as in vaccination programs, lack of full disclosure and inadequate attention to patient education and autonomy can have dramatic negative consequences for the diffusion of helpful technologies.10 The relevance here is that the Frame Problem and related issues will inevitably cause medical errors that will draw the attention of both the public and, at least in the USA, lawsuits against parties using, deploying or developing medical AI applications. [...]optimised machine learning models in healthcare can be confounded by their training data where the reimbursement strategies driving diagnostic coding are implicit and may not reflect a more objective clinical assessment. Ongoing data-driven controversies regarding the causes of poor health outcomes among disadvantaged populations (ie, differential access vs differential biological health risks)13 illustrate just how difficult it is to avoid confounding in the analysis of observational health data. A recent study showed that over-reliance on decision support systems resulted in increased false negative rate in radiology diagnoses, compared with the study scenario where the computer-aided diagnostic system was unavailable to the same group of radiologists.14 Additionally, excessive warning information will result in alert fatigue,15 and inexperienced practitioners may over-react to the warning messages.
Journal Article
Artificial intelligence in healthcare
Artificial intelligence (AI) is gradually changing medical practice. With recent progress in digitized data acquisition, machine learning and computing infrastructure, AI applications are expanding into areas that were previously thought to be only the province of human experts. In this Review Article, we outline recent breakthroughs in AI technologies and their biomedical applications, identify the challenges for further progress in medical AI systems, and summarize the economic, legal and social implications of AI in healthcare.
This Review summarizes the medical applications of artificial intelligence, and its economic, legal and social implications for healthcare.
Journal Article
Medical Artificial Intelligence and Human Values
Key PointsMedical Artificial Intelligence and Human ValuesAs large language models and other artificial intelligence models are used more in medicine, ethical dilemmas can arise depending on how the model was trained. A user must understand how human decisions and values can shape model outputs. Medical decision analysis offers lessons on measuring human values.A large language model will respond differently depending on the exact way a query is worded and how the model was directed by its makers and users. Caution is advised when considering the use of model output in decision making.
Journal Article
The Role of Tidal Mixing in Regulating the Poleward Meridional Heat Transport
Based on an earth‐system climate model, a series of numerical experiments with different scaling factors of tidal mixing parameterization were conducted to study the impact of tidal mixing diffusivity on global meridional heat transport (MHT) in the ocean. Results show that an increase in vertical diffusivity κ associated with tidal mixing can enhance poleward MHT in most of the global ocean by strengthening the overturning circulations in the North Atlantic Ocean, the Indian Ocean, and the Pacific Ocean (located in the Southern Hemisphere), and weakening it in the Southern Ocean. A mathematical fitting reveals that MHT follows a power‐law relationship with κ by a coefficient of about 0.1, that is, MHTpw ∝ κ0.1. This is the first time to quantify the relationship between tidal mixing strength and poleward MHT, shedding light on the influence of tides on global climate change.
Journal Article