目的近年来,基于深度学习的水印方法得到了广泛研究。现有方法通常对特征图的低频和高频部分同等对待,忽视了不同频率成分之间的重要差异,导致模型在处理多样化攻击时缺乏灵活性,难以同时实现水印的高保真性和强鲁棒性。为此,本文提出...目的近年来,基于深度学习的水印方法得到了广泛研究。现有方法通常对特征图的低频和高频部分同等对待,忽视了不同频率成分之间的重要差异,导致模型在处理多样化攻击时缺乏灵活性,难以同时实现水印的高保真性和强鲁棒性。为此,本文提出一种频率感知驱动的深度鲁棒图像水印技术(deep robust image watermarking driven by frequency awareness,RIWFP)。方法通过差异化机制处理低频和高频成分,提升水印性能。具体而言,低频成分通过小波卷积神经网络进行建模,利用宽感受野卷积在粗粒度层面高效学习全局结构和上下文信息;高频成分则采用深度可分离卷积和注意力机制组成的特征蒸馏块进行精炼,强化图像细节,在细粒度层面高效捕捉高频信息。此外,本文使用多频率小波损失函数,引导模型聚焦于不同频带的特征分布,进一步提升生成图像的质量。结果实验结果表明,提出的频率感知驱动的深度鲁棒图像水印技术在多个数据集上均表现出优越性能。在COCO(common objects in context)数据集上,RIWFP在随机丢弃攻击下的准确率达到91.4%;在椒盐噪声和中值滤波攻击下,RIWFP分别以100%和99.5%的准确率达到了最高水平,展现了其对高频信息的高效学习能力。在Ima⁃geNet数据集上,RIWFP在裁剪攻击下的准确率为93.4%;在JPEG压缩攻击下的准确率为99.6%,均显著优于其他对比方法。综合来看,RIWFP在COCO和ImageNet数据集上的平均准确率分别为96.7%和96.9%,均高于其他对比方法。结论本文所提方法通过频率感知的粗到细处理策略,显著增强了水印的不可见性和鲁棒性,在处理多种攻击时表现出优越性能。展开更多
Variations in temperature and precipitation affect local ecosystems. Considerable spatial and temporal heterogeneity exists in arid ecosystems such as desert steppes. In this study, we analyzed the spatiotemporal dy- ...Variations in temperature and precipitation affect local ecosystems. Considerable spatial and temporal heterogeneity exists in arid ecosystems such as desert steppes. In this study, we analyzed the spatiotemporal dy- namics of climate and vegetation phenology in the desert steppe of Inner Mongolia, China using meteorological data （1961-2010） from 11 stations and phenology data （2004-2012） from 6 ecological observation stations. We also estimated the gross primary production for the period of 1982-2009 and found that the annual mean tem- perature increased at a rate of 0.47~C/decade during 1961-2010, with the last 10 years being consistently warmer than the 50 years as an average. The most significant warming occurred in winters. Annual precipitation slightly decreased during the 50-year period, with summer precipitation experiencing the highest drop in the last 10 years, and spring precipitation, a rise. Spatially, annual precipitation increased significantly in the northeastern and eastern central areas next to the typical steppe. From 2004 to 2012, vegetation green-up and senescence date advanced in the study area, shortening the growing season. Consequently, the primary productivity of the desert steppe de- creased along the precipitation gradient from southeast to northwest. Temporally, productivity increased during the period of 1982-1999 and significantly decreased after 2000. Overall, the Last decade witnessed the most dramatic climatic changes that were likely to negatively affect the desert steppe ecosystem. The decreased primary produc- tivity, in particular, decreases ecosystem resilience and impairs the livelihood of local farmers and herdsmen.展开更多
[目的]分析1993—2023年全球水土流失监测技术领域的研究现状、进展及前沿热点的演变趋势,梳理其发展态势,为促进水土流失监测技术的创新与发展提供参考。[方法]选取Web of Science的Core Collection数据库和中国知网(CNKI)数据库中1993...[目的]分析1993—2023年全球水土流失监测技术领域的研究现状、进展及前沿热点的演变趋势,梳理其发展态势,为促进水土流失监测技术的创新与发展提供参考。[方法]选取Web of Science的Core Collection数据库和中国知网(CNKI)数据库中1993—2023年水土流失监测技术领域的943篇文献,利用CiteSpace文献计量软件对文献发表的发文趋势、国别、结构、作者合作网络,关键词聚类、关键词突现进行可视化分析。[结果](1)全球发文量持续增长,2010年后研究步入发展的快车道,中国是全球发文量的质心,中国和美国在世界范围内对水土流失监测技术领域的学术影响力最大。(2)中国科学院、北京师范大学等机构研究范围和合作网络较为广泛;刘宝元、Poesen Jean等是该领域发文量享有较高声誉的学者。(3)两大数据库中的研究热点都聚焦于黄土高原、东北地区两大水土流失严重区域,沟蚀和坡面侵蚀是重点关注的水土流失类型。[结论]水土流失监测技术由传统测量转变为现代测量,多技术融合已成为该领域的发展趋势,并推动水土流失监测成效提升。展开更多
Early-and late-onset narcolepsy constitutes two distinct diagnostic subgroups.However,it is not clear whether symptomology and genetic risk factors differ between early-and late-onset narcoleptics.This study compared ...Early-and late-onset narcolepsy constitutes two distinct diagnostic subgroups.However,it is not clear whether symptomology and genetic risk factors differ between early-and late-onset narcoleptics.This study compared clinical data and single-nucleotide polymorphisms(SNPs)between early-and late-onset patients in a large cohort of 899 Han Chinese narcolepsy patients.Blood,cerebrospinal fluid,and clinical data were prospectively collected from patients,and patients were genotyped for 40 previously reported narcolepsy risk-conferring SNPs.Genetic risk scores(GRSs),associations of five different sets of SNPs(GRS1–GRS5)with early-and late-onset narcolepsy,were evaluated using logistic regression and receiver operating characteristic curves.Mean sleep latency was significantly shorter in early-onset cases than in late-onset cases.Symptom severity was greater among late-onset patients,with higher rates of sleep paralysis,hypnagogic hallucinations,health-related quality of life impairment,and concurrent presentation with four or more symptoms.Hypocretin levels did not differ significantly between early-and late-onset cases.Only rs3181077(CCR1/CCR3)and rs9274477(HLA-DQB1)were more prevalent among early-onset cases.Only GRS1(26 SNPs;OR=1.513,95%CI:0.893–2.585;P<0.05)and GRS5(6 SNPs;OR=1.893,95%CI:1.204–2.993;P<0.05)were associated with early-onset narcolepsy,with areas under the receiver operating characteristic curves of 0.731 and 0.732,respectively.Neither GRS1 nor GRS5 included SNPs in HLA regions.Our results indicate that symptomology and genetic risk factors differ between early-and late-onset narcolepsy.This protocol was approved by the Institutional Review Board(IRB)Panels on Medical Human Subjects at Peking University People’s Hospital,China(approval No.Yuanlunshenlinyi 86)in October 2011.展开更多
Sodium-glucose cotransporter-2(SGLT2)inhibitors have emerged as a pivotal intervention in diabetes management,offering significant cardiovascular benefits.Empagliflozin,in particular,has demonstrated cardioprotective ...Sodium-glucose cotransporter-2(SGLT2)inhibitors have emerged as a pivotal intervention in diabetes management,offering significant cardiovascular benefits.Empagliflozin,in particular,has demonstrated cardioprotective effects beyond its glucose-lowering action,reducing heart failure hospitalizations and improving cardiac function.Of note,the cardioprotective mechanisms appear to be independent of glucose lowering,possibly mediated through several mechanisms involving shifts in cardiac metabolism and anti-fibrotic,anti-inflammatory,and anti-oxidative pathways.This editorial summarizes the multifaceted cardiovascular advantages of SGLT2 inhibitors,highlighting the need for further research to elucidate their full therapeutic potential in cardiac care.展开更多
Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonst...Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture.<c+a>slip,tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation,whereas the orientation dependence becomes less obvious with further increasing strain.The high work hardening rate at the strain of 2%–5%is accompanied by the significant increase of<c+a>slip and tension twinning activities.The fine microstructure strongly restricts the activation and growth of twinning,resulting in a slow exhaust of tension twinning and thin compression twins.The restriction of twinning and the activation of profuse<c+a>slip near grain/twin boundaries,relaxing the stress concentration,sustain the homogeneous deformation to a high strain.展开更多
A sustainable management of national park requires collaboration between park staff, NGOs, local organizations and stakeholders, and government intervention. This collaboration promotes community-based welfare and ins...A sustainable management of national park requires collaboration between park staff, NGOs, local organizations and stakeholders, and government intervention. This collaboration promotes community-based welfare and inspires a sense of responsibility, thus promoting more benefits than conflicts. A survey administered to residents surrounding Nyungwe National Park was used to evaluate the relationship between Nyungwe National Park management and local communities. The residents acknowledged a positive attitude towards participating in conservation organizations where there was involvement, while a negative response revealed weak community mobilization. The community’s opinions about protection and tourism progression noted weak conflict resolution, but a positive attitude towards tourism activities in the area since they believed employment was likely as a result. In addition, the residents asked for support from government investments and stakeholders to develop the local private sector, and asked to be involved during the planning process. Approaches including the design of coordination mechanisms and integrated conservation and developments projects are suggested to promote a management structure leading to community involvement in conservation and tourism activities. This will increase visitor numbers and contribute to economic development not only in the region but also in the whole country. Empirical studies along with the factors shaping tourism and conservation activities should be considered as the basis for sustainable decision and policy making for sustainable management, and will contribute to government, stakeholders and park manager collaborations at Nyungwe national park.展开更多
Jet pumps often suffer from efficiency losses due to the intense mixing of power and suction fluids,which leads to significant kinetic energy dissipation.Enhancing the efficiency of such pumps requires careful optimiz...Jet pumps often suffer from efficiency losses due to the intense mixing of power and suction fluids,which leads to significant kinetic energy dissipation.Enhancing the efficiency of such pumps requires careful optimization of their structural parameters.In this study,a computational fluid dynamics(CFD)model of a hydraulic jet sand-flushing pump is developed to investigate the effects of throat-to-nozzle distance,area ratio,and throat length on the pump’s sand-carrying performance.An orthogonal experimental design is employed to optimize the structural parameters,while the influence of sand characteristics on pumping performance is systematically evaluated.Complementary indoor experiments are used to validate the numerical results,yielding an optimized configuration with a throat-to-nozzle cross-sectional area ratio of 4,a throat length five times the throat diameter,and a throat-to-nozzle distance equal to the nozzle diameter.Under a power fluid flow rate of 1.7 m3/h with this area ratio,the sand-carrying efficiency reaches its peak,achieving a sand transport rate of 290 g/min(6.7 L/h).Comparison of CFD predictions with experimental data across different area ratios demonstrates excellent agreement,with an average relative error of 2.44%and an average absolute error of 3.56%,confirming the reliability of the simulation approach.展开更多
文摘目的近年来,基于深度学习的水印方法得到了广泛研究。现有方法通常对特征图的低频和高频部分同等对待,忽视了不同频率成分之间的重要差异,导致模型在处理多样化攻击时缺乏灵活性,难以同时实现水印的高保真性和强鲁棒性。为此,本文提出一种频率感知驱动的深度鲁棒图像水印技术(deep robust image watermarking driven by frequency awareness,RIWFP)。方法通过差异化机制处理低频和高频成分,提升水印性能。具体而言,低频成分通过小波卷积神经网络进行建模,利用宽感受野卷积在粗粒度层面高效学习全局结构和上下文信息;高频成分则采用深度可分离卷积和注意力机制组成的特征蒸馏块进行精炼,强化图像细节,在细粒度层面高效捕捉高频信息。此外,本文使用多频率小波损失函数,引导模型聚焦于不同频带的特征分布,进一步提升生成图像的质量。结果实验结果表明,提出的频率感知驱动的深度鲁棒图像水印技术在多个数据集上均表现出优越性能。在COCO(common objects in context)数据集上,RIWFP在随机丢弃攻击下的准确率达到91.4%;在椒盐噪声和中值滤波攻击下,RIWFP分别以100%和99.5%的准确率达到了最高水平,展现了其对高频信息的高效学习能力。在Ima⁃geNet数据集上,RIWFP在裁剪攻击下的准确率为93.4%;在JPEG压缩攻击下的准确率为99.6%,均显著优于其他对比方法。综合来看,RIWFP在COCO和ImageNet数据集上的平均准确率分别为96.7%和96.9%,均高于其他对比方法。结论本文所提方法通过频率感知的粗到细处理策略,显著增强了水印的不可见性和鲁棒性,在处理多种攻击时表现出优越性能。
基金supported by the State Key Basic Research Development Program of China (2012CB722201)the National Basic Research Program of China (31200414, 31060320, 30970504)+1 种基金the National Basic Research Program of Inner Mongolia (2009ms0603)the Earmarked Fund for Modern Agro-Industry Technology Research System
文摘Variations in temperature and precipitation affect local ecosystems. Considerable spatial and temporal heterogeneity exists in arid ecosystems such as desert steppes. In this study, we analyzed the spatiotemporal dy- namics of climate and vegetation phenology in the desert steppe of Inner Mongolia, China using meteorological data （1961-2010） from 11 stations and phenology data （2004-2012） from 6 ecological observation stations. We also estimated the gross primary production for the period of 1982-2009 and found that the annual mean tem- perature increased at a rate of 0.47~C/decade during 1961-2010, with the last 10 years being consistently warmer than the 50 years as an average. The most significant warming occurred in winters. Annual precipitation slightly decreased during the 50-year period, with summer precipitation experiencing the highest drop in the last 10 years, and spring precipitation, a rise. Spatially, annual precipitation increased significantly in the northeastern and eastern central areas next to the typical steppe. From 2004 to 2012, vegetation green-up and senescence date advanced in the study area, shortening the growing season. Consequently, the primary productivity of the desert steppe de- creased along the precipitation gradient from southeast to northwest. Temporally, productivity increased during the period of 1982-1999 and significantly decreased after 2000. Overall, the Last decade witnessed the most dramatic climatic changes that were likely to negatively affect the desert steppe ecosystem. The decreased primary produc- tivity, in particular, decreases ecosystem resilience and impairs the livelihood of local farmers and herdsmen.
文摘[目的]分析1993—2023年全球水土流失监测技术领域的研究现状、进展及前沿热点的演变趋势,梳理其发展态势,为促进水土流失监测技术的创新与发展提供参考。[方法]选取Web of Science的Core Collection数据库和中国知网(CNKI)数据库中1993—2023年水土流失监测技术领域的943篇文献,利用CiteSpace文献计量软件对文献发表的发文趋势、国别、结构、作者合作网络,关键词聚类、关键词突现进行可视化分析。[结果](1)全球发文量持续增长,2010年后研究步入发展的快车道,中国是全球发文量的质心,中国和美国在世界范围内对水土流失监测技术领域的学术影响力最大。(2)中国科学院、北京师范大学等机构研究范围和合作网络较为广泛;刘宝元、Poesen Jean等是该领域发文量享有较高声誉的学者。(3)两大数据库中的研究热点都聚焦于黄土高原、东北地区两大水土流失严重区域,沟蚀和坡面侵蚀是重点关注的水土流失类型。[结论]水土流失监测技术由传统测量转变为现代测量,多技术融合已成为该领域的发展趋势,并推动水土流失监测成效提升。
基金supported by the Research Project of Central Health Care Special Fund,China,No.W2017BJ52(to JZ)
文摘Early-and late-onset narcolepsy constitutes two distinct diagnostic subgroups.However,it is not clear whether symptomology and genetic risk factors differ between early-and late-onset narcoleptics.This study compared clinical data and single-nucleotide polymorphisms(SNPs)between early-and late-onset patients in a large cohort of 899 Han Chinese narcolepsy patients.Blood,cerebrospinal fluid,and clinical data were prospectively collected from patients,and patients were genotyped for 40 previously reported narcolepsy risk-conferring SNPs.Genetic risk scores(GRSs),associations of five different sets of SNPs(GRS1–GRS5)with early-and late-onset narcolepsy,were evaluated using logistic regression and receiver operating characteristic curves.Mean sleep latency was significantly shorter in early-onset cases than in late-onset cases.Symptom severity was greater among late-onset patients,with higher rates of sleep paralysis,hypnagogic hallucinations,health-related quality of life impairment,and concurrent presentation with four or more symptoms.Hypocretin levels did not differ significantly between early-and late-onset cases.Only rs3181077(CCR1/CCR3)and rs9274477(HLA-DQB1)were more prevalent among early-onset cases.Only GRS1(26 SNPs;OR=1.513,95%CI:0.893–2.585;P<0.05)and GRS5(6 SNPs;OR=1.893,95%CI:1.204–2.993;P<0.05)were associated with early-onset narcolepsy,with areas under the receiver operating characteristic curves of 0.731 and 0.732,respectively.Neither GRS1 nor GRS5 included SNPs in HLA regions.Our results indicate that symptomology and genetic risk factors differ between early-and late-onset narcolepsy.This protocol was approved by the Institutional Review Board(IRB)Panels on Medical Human Subjects at Peking University People’s Hospital,China(approval No.Yuanlunshenlinyi 86)in October 2011.
文摘Sodium-glucose cotransporter-2(SGLT2)inhibitors have emerged as a pivotal intervention in diabetes management,offering significant cardiovascular benefits.Empagliflozin,in particular,has demonstrated cardioprotective effects beyond its glucose-lowering action,reducing heart failure hospitalizations and improving cardiac function.Of note,the cardioprotective mechanisms appear to be independent of glucose lowering,possibly mediated through several mechanisms involving shifts in cardiac metabolism and anti-fibrotic,anti-inflammatory,and anti-oxidative pathways.This editorial summarizes the multifaceted cardiovascular advantages of SGLT2 inhibitors,highlighting the need for further research to elucidate their full therapeutic potential in cardiac care.
基金This project has received funding from the National Key Research and Development Program(2021YFB3702100)TY was supported by a research grant(VIL50197)from VILLUM FONDEN。
文摘Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture.<c+a>slip,tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation,whereas the orientation dependence becomes less obvious with further increasing strain.The high work hardening rate at the strain of 2%–5%is accompanied by the significant increase of<c+a>slip and tension twinning activities.The fine microstructure strongly restricts the activation and growth of twinning,resulting in a slow exhaust of tension twinning and thin compression twins.The restriction of twinning and the activation of profuse<c+a>slip near grain/twin boundaries,relaxing the stress concentration,sustain the homogeneous deformation to a high strain.
文摘A sustainable management of national park requires collaboration between park staff, NGOs, local organizations and stakeholders, and government intervention. This collaboration promotes community-based welfare and inspires a sense of responsibility, thus promoting more benefits than conflicts. A survey administered to residents surrounding Nyungwe National Park was used to evaluate the relationship between Nyungwe National Park management and local communities. The residents acknowledged a positive attitude towards participating in conservation organizations where there was involvement, while a negative response revealed weak community mobilization. The community’s opinions about protection and tourism progression noted weak conflict resolution, but a positive attitude towards tourism activities in the area since they believed employment was likely as a result. In addition, the residents asked for support from government investments and stakeholders to develop the local private sector, and asked to be involved during the planning process. Approaches including the design of coordination mechanisms and integrated conservation and developments projects are suggested to promote a management structure leading to community involvement in conservation and tourism activities. This will increase visitor numbers and contribute to economic development not only in the region but also in the whole country. Empirical studies along with the factors shaping tourism and conservation activities should be considered as the basis for sustainable decision and policy making for sustainable management, and will contribute to government, stakeholders and park manager collaborations at Nyungwe national park.
基金funded by China Oilfield Services Limited,grant number YXB24YF003.
文摘Jet pumps often suffer from efficiency losses due to the intense mixing of power and suction fluids,which leads to significant kinetic energy dissipation.Enhancing the efficiency of such pumps requires careful optimization of their structural parameters.In this study,a computational fluid dynamics(CFD)model of a hydraulic jet sand-flushing pump is developed to investigate the effects of throat-to-nozzle distance,area ratio,and throat length on the pump’s sand-carrying performance.An orthogonal experimental design is employed to optimize the structural parameters,while the influence of sand characteristics on pumping performance is systematically evaluated.Complementary indoor experiments are used to validate the numerical results,yielding an optimized configuration with a throat-to-nozzle cross-sectional area ratio of 4,a throat length five times the throat diameter,and a throat-to-nozzle distance equal to the nozzle diameter.Under a power fluid flow rate of 1.7 m3/h with this area ratio,the sand-carrying efficiency reaches its peak,achieving a sand transport rate of 290 g/min(6.7 L/h).Comparison of CFD predictions with experimental data across different area ratios demonstrates excellent agreement,with an average relative error of 2.44%and an average absolute error of 3.56%,confirming the reliability of the simulation approach.
