DSRM: Boost Textual Adversarial Training with Distribution Shift Risk Minimization

Adversarial training is one of the best-performing methods in improving the robustness of deep language models. However, robust models come at the cost of high time consumption, as they require multi-step gradient ascents or word substitutions to obtain adversarial samples. In addition, these generated samples are deficient in grammatical quality and semantic consistency, which impairs the effectiveness of adversarial training. To address these problems, we introduce a novel, effective procedure for instead adversarial training with only clean data. Our procedure, distribution shift risk minimization (DSRM), estimates the adversarial loss by perturbing the input data's probability distribution rather than their embeddings. This formulation results in a robust model that minimizes the expected global loss under adversarial attacks. Our approach requires zero adversarial samples for training and reduces time consumption by up to 70\% compared to current best-performing adversarial training methods. Experiments demonstrate that DSRM considerably improves BERT's resistance to textual adversarial attacks and achieves state-of-the-art robust accuracy on various benchmarks.Comment: Accepted by ACL202

Low-loss chip-scale programmable silicon photonic processor

Chip-scale programmable optical signal processors are often used to flexibly manipulate the optical signals for satisfying the demands in various applications, such as lidar, radar, and artificial intelligence. Silicon photonics has unique advantages of ultra-high integration density as well as CMOS compatibility, and thus makes it possible to develop large-scale programmable optical signal processors. The challenge is the high silicon waveguides propagation losses and the high calibration complexity for all tuning elements due to the random phase errors. In this paper, we propose and demonstrate a programmable silicon photonic processor for the first time by introducing low-loss multimode photonic waveguide spirals and low-random-phase-error Mach-Zehnder switches. The present chip-scale programmable silicon photonic processor comprises a 1×4 variable power splitter based on cascaded Mach-Zehnder couplers (MZCs), four Ge/Si photodetectors, four channels of thermally-tunable optical delaylines. Each channel consists of a continuously-tuning phase shifter based on a waveguide spiral with a micro-heater and a digitally-tuning delayline realized with cascaded waveguide-spiral delaylines and MZSs for 5.68 ps time-delay step. Particularly, these waveguide spirals used here are designed to be as wide as 2 µm, enabling an ultralow propagation loss of 0.28 dB/cm. Meanwhile, these MZCs and MZSs are designed with 2-µm-wide arm waveguides, and thus the random phase errors in the MZC/MZS arms are negligible, in which case the calibration for these MZSs/MZCs becomes easy and furthermore the power consumption for compensating the phase errors can be reduced greatly. Finally, this programmable silicon photonic processor is demonstrated successfully to verify a number of distinctively different functionalities, including tunable time-delay, microwave photonic beamforming, arbitrary optical signal filtering, and arbitrary waveform generation

Cobalt-based electrode materials for sodium-ion batteries

The demand for grid-scale energy storage systems has rapidly grown over recent years, to meet the requirements of structural innovation within the energy industry. Due to their inexpensive manufacturing and operating costs, and the similar electrochemical mechanism with the well-established lithium-ion batteries (LIBs), sodium ion batteries (SIBs) have been considered as an attractive candidate for grid-scale energy storage systems. A variety of cobalt-based cathode and anode materials, including cobalt oxides, cobalt chalcogenides and layered sodium cobaltates, have been synthesized and evaluated for sodium storage within the academic literature. In this article, we present a comprehensive review of the recent progress with cobalt-based electrodes (both as an anode and cathode material) used in SIBs. In detail, the electrochemical mechanisms, advantages and disadvantages, the relationship between crystalline structure and electrochemical performance and strategies to enhance the overall electrochemical performance of cobalt-based cathode and anode materials are discussed. Up to now, some cathode materials have already reached a high energy density, which is comparable to commercial LIBs. Furthermore, some cobalt-based materials can maintain a high Coulombic efficiency of over 99% with high reversible capacity during long cycling life. These encouraging results, allow such cobalt-based electrode materials to be a potential solution for grid-scale SIB systems

Secrets of RLHF in Large Language Models Part I: PPO

Large language models (LLMs) have formulated a blueprint for the advancement of artificial general intelligence. Its primary objective is to function as a human-centric (helpful, honest, and harmless) assistant. Alignment with humans assumes paramount significance, and reinforcement learning with human feedback (RLHF) emerges as the pivotal technological paradigm underpinning this pursuit. Current technical routes usually include \textbf{reward models} to measure human preferences, \textbf{Proximal Policy Optimization} (PPO) to optimize policy model outputs, and \textbf{process supervision} to improve step-by-step reasoning capabilities. However, due to the challenges of reward design, environment interaction, and agent training, coupled with huge trial and error cost of large language models, there is a significant barrier for AI researchers to motivate the development of technical alignment and safe landing of LLMs. The stable training of RLHF has still been a puzzle. In the first report, we dissect the framework of RLHF, re-evaluate the inner workings of PPO, and explore how the parts comprising PPO algorithms impact policy agent training. We identify policy constraints being the key factor for the effective implementation of the PPO algorithm. Therefore, we explore the PPO-max, an advanced version of PPO algorithm, to efficiently improve the training stability of the policy model. Based on our main results, we perform a comprehensive analysis of RLHF abilities compared with SFT models and ChatGPT. The absence of open-source implementations has posed significant challenges to the investigation of LLMs alignment. Therefore, we are eager to release technical reports, reward models and PPO code

Plant 45S rDNA Clusters Are Fragile Sites and Their Instability Is Associated with Epigenetic Alterations

Our previous study demonstrated that 45S ribosomal DNA (45S rDNA) clusters were chromosome fragile sites expressed spontaneously in Lolium. In this study, fragile phenotypes of 45S rDNA were observed under aphidicolin (APH) incubation in several plant species. Further actinomycin D (ActD) treatment showed that transcriptional stress might interfere with chromatin packaging, resulting in 45S rDNA fragile expression. These data identified 45S rDNA sites as replication-dependent as well as transcription-dependent fragile sites in plants. In the presence of ActD, a dramatic switch to an open chromatin conformation and accumulated incomplete 5′ end of the external transcribed spacer (5′ETS) transcripts were observed, accompanied by decreased DNA methylation, decreased levels of histone H3, and increased histone acetylation and levels of H3K4me2, suggesting that these epigenetic alterations are associated with failure of 45S rDNA condensation. Furthermore, the finding that γ-H2AX was accumulated at 45S rDNA sites following ActD treatment suggested that the DNA damage signaling pathway was associated with the appearance of 45S rDNA fragile phenotypes. Our data provide a link between 45S rDNA transcription and chromatin-packaging defects and open the door for further identifying the molecular mechanism involved

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens (IOL). The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions

Exploring the potential of terahertz time-domain spectroscopy for label-free identification of animal origin of chondroitin sulfate

This study developed a simple method to distinguish the animal source of chondroitin sulfate (CS) through systematic investigations and comparisons of the terahertz (THz) spectral characteristics of CS with different animal sources. CS from shark had the lowest THz absorption coefficient, followed by that from cattle, with CS from piglet exhibiting the highest values. Meanwhile, in case of continuous and no heating, the changing trends of the THz absorption index value of CS from shark source exhibited significant changes, followed by that from cattle and piglet. Based on the Raman spectrum, infrared spectrum, and thermogravimetric analysis, the molecular composition and structure differences between them were the primary causes of the observed results, being related to the physical index of production by different manufacturers. Thus, the THz spectral characteristics of CS exhibit obvious species differences, which can be used in qualitative animal origin identification

Subjective Exercise Experience and Group Cohesion among Chinese Participating in Square Dance: A Moderated Mediation Model of Years of Participation and Gender

(1) Background: This study aimed to explore the relationship between years of participation, subjective exercise experience, and group cohesion among gender-specific square dance practitioners. (2) Methods: The Subjective Exercise Experience Questionnaire (SEEQ) and Group Environment Questionnaire (GEQ) were used to evaluate Subjective Exercise Experience (SEE) and group cohesion (GC). An analysis was conducted on 130 Chinese (63 males and 67 females) using multiple group analysis within a structural equation model. (3) Results: (a) The positive aspects of Subjective Exercise Experience (SEE) and Positive Well-Being (PWB), had a strongly positive effect on GC in both groups. The negative aspects of SEE, Psychological Fatigue (PF), and Psychological Distress (PD), had negative effects on GC. (b) Only for the male group was there an indirect effect of participation years on the association between SEE and GC in the model (a × b = 0.062, 95% CI [0.001, 0.181]; standard error (SE) = 0.062, p = 0.048). (c) The significant differences between paths coefficients were noticed in the association of years of participation with SEE (t = −2.043) and GC (t = −1.962). (4) Conclusion: Based on these results, gender differences in terms of the partial mediating role of adherence in the relationship of SEE and GC were presented for future research, fitness popularization, and society

The Landscape Pattern Evolution of Typical Open-Pit Coal Mines Based on Land Use in Inner Mongolia of China during 20 Years

As the province most abundant in mineral resources in China, Inner Mongolia has more than 200 open-pit coal mines. The coal mining activities seriously hinder the sustainable use of regional land and the improvement of residents’ wellbeing. Taking 13 typical open-pit coal mines of Inner Mongolia as the study area, combining remote sensing images and the Google Earth Engine (GEE) platform, the trend features of spatial and temporal evolution of land use and landscape patterns from 2001 to 2020 were analyzed by transfer matrix and landscape pattern index methods. According to the mining plan and reclamation measures of the “Land Reclamation Plan”, the impacts of ecological restoration projects on land-use structure and landscape patterns were evaluated. The results showed that the following: (1) The landscape types of typical open-pit coal mining areas were mainly grassland, cropland, and industrial landscapes. The change trend of landscape pattern was obvious over the past 20 years, and the changes in grassland and mining land were relatively large, which decreased by 56.51 km2 and increased by 60.42 km2, respectively. (2) Land reclamation and ecological restoration projects had positive impacts on landscape pattern changes. With the transformation from mining activities to land reclamation activities beginning in 2007, nearly 70% of the study area showed a decreasing trend in landscape fragmentation, indicating a better landscape pattern of mining area. (3) Positive policy orientation of mine ecological restoration promoted more reasonable landscape patterns