针对现有医学影像合成技术在准确捕捉复杂解剖结构和病理状态方面存在不足,从而生成低质量且与实际情况不符的胸片问题,文中提出了一种创新性的医学潜在扩散模型Chest-Chat。基于先前研究结果改进了所提模型,引入一种多模态文本编码器Me...针对现有医学影像合成技术在准确捕捉复杂解剖结构和病理状态方面存在不足,从而生成低质量且与实际情况不符的胸片问题,文中提出了一种创新性的医学潜在扩散模型Chest-Chat。基于先前研究结果改进了所提模型,引入一种多模态文本编码器MedA-BERT(Medical Attention Strategy Pre-training of Deep Bidirectional Transformers for Language Understanding)。采用跨模态视觉-语言预训练策略构建该编码器并强化胸片影像与对应文本报告间的深刻语义联系,结合双向交叉注意力机制和对比学习显著增强了模型对医学影像报告语义的理解和处理能力。将MedA-BERT与潜在扩散模型的视觉模块相结合,使Chest-Chat能够生成具有详细解剖和病理描述的高质量胸片。在CheXpert和MIMIC-CXR(Chest X-ray)两个公开数据集上进行了广泛评估。实验结果表明,Chest-Chat的FID InceptionV3(Fréchet Inception Distance)、FID XRV和MS-SSIM(Multi-Scale Structural Similarity)分别为58.38、3.69和0.12±0.11,其表现优于现有方法。展开更多
Understanding the hydrochemical dynamics of alpine arid basins is essential for ensuring sustainable water resources on the Tibetan Plateau.The Nianchu River,a typical alpine and arid basin on the Tibetan Plateau,is t...Understanding the hydrochemical dynamics of alpine arid basins is essential for ensuring sustainable water resources on the Tibetan Plateau.The Nianchu River,a typical alpine and arid basin on the Tibetan Plateau,is the focal area of the“One River,Two Tributaries”Comprehensive Development Project in Xizang Autonomous Region of China.However,no systematic studies on hydrochemistry in this basin have been conducted.This study investigated the spatio-temporal variations and controlling mechanisms of water chemistry in the Nianchu River basin with a focus on the understudied influence of widely distributed geothermal springs.During the dry and wet seasons,44 river water and 13 geothermal water samples were collected and analyzed for major ions.Results showed that the river water was weakly alkaline,with total dissolved solids and major ion concentrations(e.g.,Ca^(2+),HCO₃^(-),SO_(4)^(2-))significantly higher in the dry season(mean EC:372μS/cm)than in the wet season(mean EC:236μS/cm),and peaking in the midstream tributary of the Longma River.In contrast,the geothermal springs were moderately acidic and exhibited markedly higher mineralization(mean EC:1,936μS/cm),with Na^(+),K^(+),and Cl^(-)concentrations being 20.8,22.5,and 44.8 times those in river water,respectively.The direct discharge of geothermal water was identified as a key driver that significantly elevated Na^(+),K^(+),and Cl^(-)levels and altered the hydrochemical facies of the river in affected reaches.The main conclusions are that:(1)the hydrochemical evolution of the Nianchu River is predominantly governed by carbonate and silicate weathering,while geothermal water chemistry is controlled by evaporation-crystallization and deep water-rock interactions;and(2)sulfuric acid participates in carbonate weathering alongside carbonic acid,particularly in the mid-lower reaches,enhances the release of Ca^(2+),Mg^(2+),and SO_(4)^(2-).This study provides a holistic understanding of hydrogeochemical controls in a typical alpine basin and underscores the critical role of geothermal fluids,offering a scientific basis for protecting water resources under climate and anthropogenic pressures.展开更多
文摘针对现有医学影像合成技术在准确捕捉复杂解剖结构和病理状态方面存在不足,从而生成低质量且与实际情况不符的胸片问题,文中提出了一种创新性的医学潜在扩散模型Chest-Chat。基于先前研究结果改进了所提模型,引入一种多模态文本编码器MedA-BERT(Medical Attention Strategy Pre-training of Deep Bidirectional Transformers for Language Understanding)。采用跨模态视觉-语言预训练策略构建该编码器并强化胸片影像与对应文本报告间的深刻语义联系,结合双向交叉注意力机制和对比学习显著增强了模型对医学影像报告语义的理解和处理能力。将MedA-BERT与潜在扩散模型的视觉模块相结合,使Chest-Chat能够生成具有详细解剖和病理描述的高质量胸片。在CheXpert和MIMIC-CXR(Chest X-ray)两个公开数据集上进行了广泛评估。实验结果表明,Chest-Chat的FID InceptionV3(Fréchet Inception Distance)、FID XRV和MS-SSIM(Multi-Scale Structural Similarity)分别为58.38、3.69和0.12±0.11,其表现优于现有方法。
基金jointly funded by the School Scientific Research Development Fund project(2022LFR091)。
文摘Understanding the hydrochemical dynamics of alpine arid basins is essential for ensuring sustainable water resources on the Tibetan Plateau.The Nianchu River,a typical alpine and arid basin on the Tibetan Plateau,is the focal area of the“One River,Two Tributaries”Comprehensive Development Project in Xizang Autonomous Region of China.However,no systematic studies on hydrochemistry in this basin have been conducted.This study investigated the spatio-temporal variations and controlling mechanisms of water chemistry in the Nianchu River basin with a focus on the understudied influence of widely distributed geothermal springs.During the dry and wet seasons,44 river water and 13 geothermal water samples were collected and analyzed for major ions.Results showed that the river water was weakly alkaline,with total dissolved solids and major ion concentrations(e.g.,Ca^(2+),HCO₃^(-),SO_(4)^(2-))significantly higher in the dry season(mean EC:372μS/cm)than in the wet season(mean EC:236μS/cm),and peaking in the midstream tributary of the Longma River.In contrast,the geothermal springs were moderately acidic and exhibited markedly higher mineralization(mean EC:1,936μS/cm),with Na^(+),K^(+),and Cl^(-)concentrations being 20.8,22.5,and 44.8 times those in river water,respectively.The direct discharge of geothermal water was identified as a key driver that significantly elevated Na^(+),K^(+),and Cl^(-)levels and altered the hydrochemical facies of the river in affected reaches.The main conclusions are that:(1)the hydrochemical evolution of the Nianchu River is predominantly governed by carbonate and silicate weathering,while geothermal water chemistry is controlled by evaporation-crystallization and deep water-rock interactions;and(2)sulfuric acid participates in carbonate weathering alongside carbonic acid,particularly in the mid-lower reaches,enhances the release of Ca^(2+),Mg^(2+),and SO_(4)^(2-).This study provides a holistic understanding of hydrogeochemical controls in a typical alpine basin and underscores the critical role of geothermal fluids,offering a scientific basis for protecting water resources under climate and anthropogenic pressures.
