For biointegrated flexible systems that acquire and process electrophysiological signals, amplifying weak biosignals from their original low amplitudes (ranging from microvolt to millivolt) to volt-level is essential for subsequent processing. Achieving this level of amplification requires a high voltage gain (>105 or 100 decibels for microvolt signals). However, realizing such gain in flexible circuits remains highly challenging because of constrained integration scale and limits in feasible circuit topologies. Here, we report flexible amplifiers that achieve ultrahigh gain by leveraging intrinsic gain singularities induced by negative differential resistance (NDR) effect in carbon nanotube–based transistors. The NDR behavior is investigated under various factors, including contacts, gate structures, and channel lengths. Guided by insights into the correlations between NDR characteristics and device-level parameters, a device-circuit codesign approach is implemented to build a flexible amplifier achieving a record-high gain of 104 decibels among all reported flexible amplifiers, with successful demonstration of electroencephalogram signals amplification. A carbon nanotube–based flexible amplifier achieves >100-dB voltage gain, demonstrating EEG signal amplification.
The development of the sixth generation of wireless communications technology requires terminals that can operate at frequencies above 100 GHz. For human-centric applications, these terminals should also be flexible and have low power. However, current flexible radio-frequency transistors typically have lower maximum frequencies, in part due to the poor thermal conductivity of flexible substrates. Here we report radio-frequency transistors that are based on aligned carbon nanotube arrays on flexible substrates, having current-gain cut-off frequencies (fT) and power-gain cut-off frequencies (fmax) above 100 GHz. This is achieved by using electrothermal co-design to improve the heat dissipation and radio-frequency performance of the devices. The transistors exhibit an on-state current of 0.947 mA µm−1, a transconductance of 0.728 mS µm−1, a peak extrinsic fT of 152 GHz, a peak extrinsic fmax of 102 GHz and a power consumption under 200 mW mm−1. We also show that the devices can be used to create flexible radio-frequency amplifiers with an output power of 64 mW mm−1 and an 11-dB power gain in the K band.
Higher-Order Ambisonics (HOA) encoding from sparse, irregular microphone arrays remains a critical challenge for consumer spatial audio capture in immersive communication and XR. We propose Flow-HOA, a generative framework that jointly optimizes a multi-dimensional objective encompassing time-domain, spectral, and spatial fidelity while producing a deployable, time-invariant bank of Finite Impulse Response (FIR) encoding filters. Using conditional flow matching, the model learns to map a simple prior distribution to the target distribution of FIR filtercoefficients. Training is guided by a composite loss that balances time-domain waveform fidelity, multi-resolution spectral consistency, sub-band energy preservation, and spatial directivity constraints. Objective evaluations on synthetically simulated data demonstrate improved performance over strong model-based baselines in both signal fidelity and spatial accuracy metrics. Subjective listening tests on real microphone array recordings further confirmthat Flow-HOA yields higher overall sound quality with reduced artifacts, demonstrating generalization from synthetic training data to real-world capture conditions.
Chinese universities have actively engaged in knowledge production about other countries and played crucial roles in training professionals for the country’s foreign policy community since the founding of the People’s Republic (PRC). For decades, the transformations of the PRC’s international and area studies programs have not only reflected the shifting demands of top decision-makers but also influenced the interactions among scholars, academic institutions, government agencies, business elites, and the general public. This article analyzes the ups and downs of China’s international and area studies programs in the second half of the 20th century and how they were closely intertwined with the country’s shifting priorities in foreign policy, overseas Chinese affairs, and higher education. Primarily focusing on the case of Southeast Asian Studies (SEAS), this paper explores how the PRC’s area studies programs interacted with the country’s foreign policy during the 1955–1965 and post-1978 periods. Despite the changing geopolitical dynamics after 2000, the academic infrastructure and particular institutional culture formed in these two phases remain essential to our understanding of China’s area studies initiatives today.
This paper revisits the commercial peace hypothesis using global event data from 1989 to 2019. We show that greater imports consistently worsen bilateral relations, with the effect strengthening after the 2008 financial crisis. The negative impact is most pronounced in democracies, high-income countries and those with elevated unemployment, where globalisation's distributive conflicts more easily shape foreign policy. Instrumental variable estimates confirm causality, and analyses using militarised interstate disputes reveal that trade-driven tensions extend beyond diplomacy to overt conflict. These findings challenge the optimistic view that economic interdependence fosters peace.
Individualized head-related transfer functions (HRTFs) require accurate pinna geometry, yet commodity multi-view captures leave the ear region self-occluded and weakly textured. We present a practical pipeline that couples ear-centric acquisition with 3D Gaussian splatting (3DGS) and the boundary element method (BEM) for complete HRTF computation. The protocol augments horizontal views with per-ear elevated captures under directional lighting; 3DGS training with depth-distortion regularization yields watertight meshes via truncated signed distance function (TSDF) fusion. Standardized head coordinates and ear-canal annotations interface the mesh with BEM. Experimental evaluations demonstrate that our method achieves lower ear-region geometric error and lowerfull-band spectral distortion compared to existing image-based personalized reconstruction baselines including AudioEar, NeuS, and Metashape MVS.
Gender ideology can affect household energy consumption; however, the existing literature has ignored this aspect. Using data from household surveys, this study employs econometric modeling to examine the impact of gender ideology on household cooking fuel choices and their underlying mechanisms. The results show that an emancipatory gender ideology can substantially promote adoption of clean cooking fuels by households. The results of the mechanistic analysis show that gender ideology encourages the adoption of clean cooking fuels through two pathways: increased internet use and exercise. Furthermore, the impact of gender ideology on households' choice of cooking fuel is moderated by income and the importance of internet, with neighborhood spillover effects and heterogeneity. The HOUSE model, developed by integrating households and neighbors, clarifies the complex relationship between gender ideology and household cooking fuel choice. This study provides meaningful theoretical and practical guidance for encouraging rural households to adopt cleaner cooking fuel.
Hydroxymethyl hydroperoxide (HMHP, HOCH2OOH) is one of the most abundant organic peroxides (POs) in the atmosphere. Owing to its extremely high solubility, HMHP readily partitions into cloudwater and aerosol liquid water, where it hydrolyzes to hydrogen peroxide (H2O2) and formaldehyde (HCHO). However, previous studies were conducted in dilute solutions and did not adequately account for the high-salinity characteristic of deliquesced aerosol particles. Here, we systematically investigate the combined effects of pH (0–6), temperature (277–313 K), ionic strength (0–10 M), and ion identity (NH4+, Na+, SO42–, and Cl–) on the hydrolysis kinetics of HMHP. For the first time, a parametrization formula describing the dependence of the hydrolysis rate constant on ionic strength is established, demonstrating that ionic strength exerts only a limited influence on HMHP hydrolysis. However, it is found that in highly concentrated ammonium salt solutions, HMHP undergoes a previously unrecognized NH3-driven reaction pathway. This new pathway competes with hydrolysis, accelerating the apparent transformation rate of HMHP by more than an order of magnitude while significantly reducing the yield of H2O2 and HCHO. Our findings highlight that future atmospheric chemical models should fully account for the NH3-driven pathway in aqueous-phase reactions of POs, thereby enabling a more accurate assessment of the role of POs in atmospheric oxidant cycling and secondary particulate matter formation.