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基于MW-FDTD与树木精细模型的树林电波传播研究 被引量:2
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作者 刘健明 陈鹏 +2 位作者 杨永钦 苏婷 迟阔 《电波科学学报》 北大核心 2025年第3期559-566,共8页
随着城市低空经济的提出和发展,对城市无线通信信道精细化建模仿真提出了更高的要求。特别是在无人机等应用场景中,城市树林环境对电波传播的影响不可忽略。本文首先提出了树木精细建模方法,相较于传统的树木近似建模方法,所提方法能够... 随着城市低空经济的提出和发展,对城市无线通信信道精细化建模仿真提出了更高的要求。特别是在无人机等应用场景中,城市树林环境对电波传播的影响不可忽略。本文首先提出了树木精细建模方法,相较于传统的树木近似建模方法,所提方法能够更精确地描述树木特征;其次,引入向量化滑动窗时域有限差分(moving window finite-difference time-domain,MW-FDTD)方法,提高了树林电波传播问题的计算效率;最后,针对两类典型城市植被环境,进行了树林电波传播测量,并将测量数据与数值仿真结果进行了对比。数据对比结果表明,与传统MW-FDTD相比,向量化MW-FDTD具有更高的计算效率;与树木近似模型相比,树木精细模型的仿真结果与实测数据的均方根误差更小。 展开更多
关键词 传播模型 时域有限差分(Fdtd)法 滑动窗 树木模型 电波传播特性
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Age-Related Differences in Information Gathering among Nursing Students: Implications for Nursing Education
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作者 Yuriko Inoue Mikako Tanaka +6 位作者 Hiromitsu Ezure Junji Ito Akiko Sasaki Takashi Takaki Harumi Hata Masaaki Takayanagi Naruhito Otsuka 《Open Journal of Nursing》 2025年第1期60-66,共7页
Background: For nursing students, gathering social information is essential for understanding healthcare and social issues and developing critical thinking and decision-making skills. However, the choice of informatio... Background: For nursing students, gathering social information is essential for understanding healthcare and social issues and developing critical thinking and decision-making skills. However, the choice of information sources varies by age and individual habits. With the widespread use of the internet, there are notable differences between younger and older generations in their reliance on the internet versus traditional media sources like newspapers and television. Given the wide age range and diverse backgrounds of nursing students, understanding generational differences in information-gathering methods is important for implementing effective education. Purpose: The purpose of this study is to identify how nursing students in different age groups obtain social information and to examine media usage trends by age group. Additionally, we aim to use the findings to provide insights into effective information dissemination methods in nursing education. Results: The results showed that nursing students in their teens to forties, regardless of gender, primarily relied on the internet as their main information source, with television playing a secondary role. In contrast, students in their fifties tended to obtain information more often from newspapers and television than from the internet. This highlights an age-related difference in preferred information sources, with older students showing a greater reliance on traditional media. Conclusions: This study demonstrates that nursing students use different information-gathering methods based on their age, suggesting a need to custo-mize information dissemination strategies in nursing education. Digital media may be more effective for younger students, while traditional media or printed materials might better serve older students. Educational institutions should consider these generational differences in media usage and adopt strategies that meet the diverse needs of their student populations. 展开更多
关键词 Nursing Students Social Information Sources Media Usage Trends Generational differences
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Gender differences in the burden of near vision loss in China:An analysis based on GBD 2021 data
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作者 LIU Yu ZHU Liping +4 位作者 LIN Yanhui WANG Yanbing XIONG Kun LI Xuhong YAN Wenguang 《中南大学学报(医学版)》 北大核心 2025年第6期1030-1041,共12页
Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden ... Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden of NVL in China by sex and age groups from 1990 to 2021 and to project trends over the next 15 years.Methods:Using data from the Global Burden of Disease(GBD)2021 database,we conducted descriptive analyses of NVL prevalence in China,calculated age-standardized prevalence rates(ASPR)and age-standardized disability-adjusted life years rates(ASDR)to compare burden differences between sexes and age groups,and applied an autoregressive integrated moving average(ARIMA)model to predict NVL trends for the next 15 years.The model selection was based on best-fit criteria to ensure reliable projections.Results:From 1990 to 2021,China’s ASPR of NVL rose from 10096.24/100000 to 15624.54/100000,and ASDR increased from 101.75/100000 to 158.75/100000.In 2021,ASPR(16551.70/100000)and ASDR(167.69/100000)were higher among females than males(14686.21/100000 and 149.76/100000,respectively).China ranked highest globally in both NVL cases and disability-adjusted life years(DALYs),with female burden significantly exceeding male burden.Projections indicated this trend and sex gap will persist until 2036.Compared with 1990,the prevalence cases and DALYs increased by 239.20%and 238.82%,respectively in 2021,with the highest burden among females and the 55−59 age group.The ARIMA model predicted continued increases in prevalence and DALYs by 2036,with females maintaining a higher burden than males.Conclusion:This study reveals a marked increase in the NVL burden in China and predicts continued growth in the coming years.Public health policies should prioritize NVL prevention and control,with special attention to women and middle-aged populations to mitigate long-term societal and health impacts. 展开更多
关键词 China near vision loss Global Burden of Disease database autoregressive integrated moving average model gender differences
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Sex and age differences in depression and anxiety networks among adolescents with idiopathic scoliosis:A network analysis
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作者 Shu-Wen Dong Lei Yang +8 位作者 Yi-Fan Lin Li-Wen Yang Dan Li Li-Wan Zhu Cai-Yun Zhang Yan-Zhi Li Wan-Xin Wang Ci-Yong Lu Bin Yan 《World Journal of Psychiatry》 2025年第3期261-271,共11页
BACKGROUND Depression and anxiety are prevalent psychological challenges among patients with adolescent idiopathic scoliosis(AIS),affecting individuals across both sex and age groups.AIM To explore the network structu... BACKGROUND Depression and anxiety are prevalent psychological challenges among patients with adolescent idiopathic scoliosis(AIS),affecting individuals across both sex and age groups.AIM To explore the network structure of depression and anxiety symptoms,with a focus on identifying differences at the symptom level between sex and age subgroups.METHODS A total of 1955 participants diagnosed with AIS aged 10-18 years were assessed using the Patient Health Questionnaire Depression Scale(PHO-9)and the Generalized Anxiety Disorder Scale(GAD-7),and 765 patients exhibiting PHQ-9 or GAD-7 scores ≥ 5 were enrolled in our study. Network analysis and network comparison tests were utilized toconstruct and compare the depression-anxiety symptoms networks among sex and age subgroups.RESULTSThe results revealed GAD3 “Excessive worry” and PHQ2 “Sad mood” were the most significant central symptomsin all subgroups, while “Sad mood” had higher strength than “Excessive worry” in the lower age group. In thenetwork comparisons, the female network exhibited tighter connectivity, especially on GAD6 “Irritability” andGAD2 “Uncontrollable worry”, while only PHQ3 “Sleep” and PHQ9 “Suicidal ideation” had differences at thelocal level in the lower age group.CONCLUSIONSeveral interventions targeting excessive worry and sad mood could reduce the risk of depression and anxietysymptoms in the AIS population. Furthermore, specific anxiety symptoms in females, along with sleep disturbancesand suicidal ideation in the lower age group, should be addressed at an early stage to prevent significantdisruptions in mental health trajectories. 展开更多
关键词 Adolescent idiopathic scoliosis Network analysis Depression and anxiety symptoms Age difference Sex difference
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Brief introduction in phenotypic and genetic differences of C57BL/6 and BALB/c mice substrains
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作者 Lan Zhao Jie Wei Bingfei Yue 《Animal Models and Experimental Medicine》 2025年第9期1628-1634,共7页
Experimental mice play a critical role in biomedical research.The phenotype and application of different substrains vary due to genetic differentiation and variation.To ensure validity and reliability of results,it is... Experimental mice play a critical role in biomedical research.The phenotype and application of different substrains vary due to genetic differentiation and variation.To ensure validity and reliability of results,it is imperative to adhere to standardized experiments and controls.This paper objectively reviews the origin,differentiation,and phenotypic and genetic differences between the C57BL/6 and BALB/c mouse substrains.Furthermore,an optimal selection strategy is proposed based on the genetic quality control technology to facilitate the precise application of these two mouse substrains. 展开更多
关键词 BALB/c mice C57BL/6 mice genetic differences phenotypic differences substrains
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基于FDTD的双导体传输线瞬态响应研究 被引量:1
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作者 史艺迪 田炜 +1 位作者 李军 周小平 《延安大学学报(自然科学版)》 2025年第1期102-109,共8页
为解决传输系统供给微波电子设备信号功率的优化问题,运用时域有限差分(Finite-Difference Time-Domain,FDTD)方法研究了多导体传输线对负载设备的宽带响应特性。运用二阶精度的中心差分方法离散了多导体传输线方程,结合传输线电压与电... 为解决传输系统供给微波电子设备信号功率的优化问题,运用时域有限差分(Finite-Difference Time-Domain,FDTD)方法研究了多导体传输线对负载设备的宽带响应特性。运用二阶精度的中心差分方法离散了多导体传输线方程,结合传输线电压与电流节点的网格划分,给出了传输线瞬态响应的FDTD步进式迭代方程,利用电源和负载端的广义戴维南定理实现了FDTD计算域的截断,通过传输线波动方程分析了FDTD建模的稳定性条件。采用传输线与终端负载阻抗匹配的模式,验证了该传输线FDTD算法的准确性。以调制高斯脉冲源激励为例,数值计算得到了微波传输线之间的电磁干扰结果,讨论了阻抗匹配和失配对干扰冲击幅度的影响,得到了较为完整的传输线对负载的瞬态响应规律。 展开更多
关键词 瞬态电磁响应 多导体传输线 电磁干扰 时域有限差分方法
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Uncovering differences in the spatial structure of intercity interactive networks described by multi-source migration flow:From the multi-hierarchical perspective
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作者 WEI Shimei PAN Jinghu 《Journal of Geographical Sciences》 2025年第5期1049-1079,共31页
Population migration data derived from location-based services has often been used to delineate population flows between cities or construct intercity relationship networks to reveal and explore the complex interactio... Population migration data derived from location-based services has often been used to delineate population flows between cities or construct intercity relationship networks to reveal and explore the complex interaction patterns underlying human activities.Nevertheless,the inherent heterogeneity in multimodal migration big data has been ignored.This study conducts an in-depth comparison and quantitative analysis through a comprehensive lens of spatial association.Initially,the intercity interactive networks in China were constructed,utilizing migration data from Baidu and AutoNavi collected during the same time period.Subsequently,the characteristics and spatial structure similarities of the two types of intercity interactive networks were quantitatively assessed and analyzed from overall(network)and local(node)perspectives.Furthermore,the precision of these networks at the local scale is corroborated by constructing an intercity network from mobile phone(MP)data.Results indicate that the intercity interactive networks in China,as delineated by Baidu and AutoNavi migration flows,exhibit a high degree of structure equivalence.The correlation coefficient between these two networks is 0.874.Both networks exhibit a pronounced spatial polarization trend and hierarchical structure.This is evident in their distinct core and peripheral structures,as well as in the varying importance and influence of different nodes within the networks.Nevertheless,there are notable differences worthy of attention.Baidu intercity interactive network exhibits pronounced cross-regional effects,and its high-level interactions are characterized by a“rich-club”phenomenon.The AutoNavi intercity interactive network presents a more significant distance attenuation effect,and the high-level interactions display a gradient distribution pattern.Notably,there exists a substantial correlation between the AutoNavi and MP networks at the local scale,evidenced by a high correlation coefficient of 0.954.Furthermore,the“spatial dislocations”phenomenon was observed within the spatial structures at different levels,extracted from the Baidu and AutoNavi intercity networks.However,the measured results of network spatial structure similarity from three dimensions,namely,node location,node size,and local structure,indicate a relatively high similarity and consistency between the two networks. 展开更多
关键词 network differences interactive network intercity migration multimodal data China
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Intergenerational differences and influencing factors of farmers' terrace abandonment behavior:Based on a questionnaire survey of 2382 rural households in China
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作者 WEN Jiaming LUO Shilong +1 位作者 XIE Hualin LI Xiubin 《Journal of Geographical Sciences》 2025年第2期315-334,共20页
This study explores the impact of intergenerational differences on farmers' terrace abandonment in response to increasing intergenerational differentiation among rural households and the practical issue of terrace... This study explores the impact of intergenerational differences on farmers' terrace abandonment in response to increasing intergenerational differentiation among rural households and the practical issue of terrace abandonment. Logit and Tobit models are employed to conduct empirical analysis and it is found that terrace abandonment increases sequentially among the new, middle, and old generations, confirming that intergenerational differences significantly influence whether farmers abandon terraces and the terrace abandonment scale. Village characteristics and government subsidies significantly influence farmers' terrace abandonment. An increase in the number of migrant workers in the village increases terrace abandonment among new and middle generation farmers, whereas an increase in the distance from the village to the county significantly increases terrace abandonment among old generation farmers. An increase in the village's total population significantly reduces terrace abandonment among new generation farmers. An increase in government subsidies significantly reduces terrace abandonment among middle and old generation farmers. The impact of intergenerational differences on terrace abandonment is more pronounced in low-altitude areas. To reduce terrace abandonment, it is necessary to promote terrace transfer, develop characteristic agriculture, improve terrace farming subsidies, and propose targeted strategies for the different generations of farmers. 展开更多
关键词 terrace abandonment intergenerational differences terrace protection terrace use
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Analysis of Cognitive Differences and Influencing Factors of Traditional Chinese Medicine Culture in Rural Areas
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作者 Siyi Deng Huijun Li Xueyao Wu 《Journal of Clinical and Nursing Research》 2025年第6期340-349,共10页
This article compares the cognitive differences and influencing factors of traditional Chinese medicine culture among rural residents in Guigang,Guangxi,and Jinhua,Zhejiang,providing a reference for balanced developme... This article compares the cognitive differences and influencing factors of traditional Chinese medicine culture among rural residents in Guigang,Guangxi,and Jinhua,Zhejiang,providing a reference for balanced development.A stratified sampling method was used to conduct a questionnaire survey in three townships in each region,and data were analyzed using SPSS 25.0 and chi-square test.The survey shows that residents in Guigang rely more on personal experience for their understanding,resulting in fragmented cognition,with their needs concentrated on disease treatment.On the other hand,residents in Jinhua rely on rational trust and digital communication,leading to deeper cognition,and their needs tend to focus on preventive healthcare.Occupational factors significantly affect the cognitive level in Jinhua,while in Guigang,it is closely related to trust and cultural atmosphere.The interaction of regional economy,occupational background,and cultural tradition affects cognitive differences.It is suggested that Guigang should build a community traditional Chinese medicine cultural experience matrix,develop digital content for ethnic medical resources,and strengthen the“experience-identification-dissemination”closed loop.Jinhua should deepen the construction of digital IP and promote the integration of industry and education.The two regions should jointly build a cross-regional cultural corridor,cultivate inheritors,and use new media to expand the coverage of dissemination. 展开更多
关键词 Traditional Chinese medicine culture Influencing factors Cognitive differences
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Negotiable Fate Belief and Suicidal Ideation among Left-Behind Children:The Mediating Role of Coping Self-Efficacy and Gender Differences
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作者 Xiao Hu Biao Li Jun Qin 《International Journal of Mental Health Promotion》 2025年第8期1203-1220,共18页
Objectives:Suicidal ideation is a strong predictor of suicide deaths,which refers to the consideration or desire to give up one's own life.Left-behind children in rural China are more vulnerable to psychological p... Objectives:Suicidal ideation is a strong predictor of suicide deaths,which refers to the consideration or desire to give up one's own life.Left-behind children in rural China are more vulnerable to psychological problems and suicidal ideation compared to their non-left-behind peers.The aim of the current study was to examine two potential protective factors,negotiable fate belief and coping self-efficacy,and to test the mediating role of coping self-efficacy in the relationship between negotiable fate belief and suicidal ideation.We also analyzed gender differences in this mediation model.Methods:Across-sectional survey was conducted in rural areas ofChina.A sample of 526 left-behind children(285 males,54.18%;241 females,45.82%;Meanage=13.29 years,SD=0.97 years)was recruited to complete the Negotiable Fate Belief Scale,Coping Self-Efficacy Scale,and the Positive and Negative Suicide Ideation Inventory-Negative Scale.We used structural equation modeling to test the mediation model and multigroup analysis to test the moderation effect of gender.Results:Negotiable fate belief is negatively correlated with suicidal ideation(r=-0.13,p<0.01).Moreover,coping self-efficacy mediates the relationship between negotiable fate belief and suicidal ideation(β=-0.06,95%confidence interval(CI)[-0.12,-0.02]),accounting for 35.29%of the total effect.Finally,the mediating effect of coping self-efficacy was found to be significant only for female left-behind children(male:95%CI[-0.09,0.07];female:95%CI[-0.16,-0.01]).For female left-behind children,the mediating effect was complete,with a coefficient of-0.06,accounting for 85.71%of the total effect.Conclusions:The relationship between negotiable fate belief and suicidal ideation among rural left-behind children is mediated by coping self-efficacy,and this mediation effect was moderated by gender.This study provides a theoretical explanation for how cultivating the belief in negotiable fate and coping self-efficacy is effective for reducing suicidal ideation of rural left-behind children. 展开更多
关键词 Negotiable fate belief coping self-efficacy suicidal ideation left-behind children gender differences
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Causes of Differences in the Tropical Pacific SST Warming Pattern Projected by CMIP6 Models
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作者 Jun YING Matthew COLLINS +4 位作者 Robin CHADWICK Shangfeng CHEN Xiaoming HU Tao LIAN Shangmin LONG 《Advances in Atmospheric Sciences》 2025年第6期1077-1091,共15页
The inter-model difference in the tropical Pacific SST warming pattern is a big stumbling block for reliable projections of global climate change. Here by conducting an inter-model Empirical Orthogonal Function(EOF) a... The inter-model difference in the tropical Pacific SST warming pattern is a big stumbling block for reliable projections of global climate change. Here by conducting an inter-model Empirical Orthogonal Function(EOF) analysis as well as an ocean mixed-layer heat budget, we find that the first two modes of inter-model difference in the SST warming pattern projected by 30 CMIP6 models, explaining more than three-quarters of the total inter-model variance, are both tied to different cloud–radiation feedbacks. The EOF1 mode that captures the different magnitudes of El Ni?o-like warming as well as the largest inter-model variance in the far eastern equatorial Pacific, is likely driven by highly diverse cloud–radiation feedbacks in the east and, to a lesser extent, by differing changes in the oceanic vertical temperature gradient. The EOF2 mode that mainly represents the different magnitudes of SST warming in the western equatorial Pacific, is associated with differing levels of negative cloud–radiation feedback over the central equatorial Pacific through a dynamic air–sea coupled process involving both the Bjerknes feedback and the wind–evaporation–SST feedback.Considering in isolation the robust common model bias of a weak negative cloud–radiation feedback over the central equatorial Pacific, the projected SST warming in the western equatorial Pacific is likely to be smaller than the multi-model ensemble mean, thereby presenting a more weakeened zonal SST gradient than expected, implying the potential for more severe climate extremes under global warming. 展开更多
关键词 SST warming pattern inter-model difference cloud–radiation feedback
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Is metabolically healthy obesity shaped by inflammation,gender differences,and fat distribution?
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作者 Davide Ramoni Luca Liberale +1 位作者 Federico Carbone Fabrizio Montecucco 《World Journal of Cardiology》 2025年第8期1-8,共8页
The obesity epidemic continues to challenge global cardiovascular(CV)health,but not all obesity is equal.Emerging evidence underscores that distinct obesity phenotypes—particularly metabolically healthy vs unhealthy ... The obesity epidemic continues to challenge global cardiovascular(CV)health,but not all obesity is equal.Emerging evidence underscores that distinct obesity phenotypes—particularly metabolically healthy vs unhealthy profiles—confer differential CV risks.Recent large-scale studies have revealed that even metabol-ically healthy obesity(MHO)is associated with an increased risk of adverse CV events,particularly in the context of socioeconomic disadvantage.Central is the role of chronic low-grade inflammation,termed“metaflammation”,which can persist even in the absence of overt metabolic syndrome and is shaped by both gender and fat distribution.Epicardial and visceral adiposity contribute to this pro-inflammatory state and are strongly associated with conditions such as heart failure and atrial fibrillation.Notably,aging and hormonal changes,particularly in women,may destabilize MHO status,increasing CV vulnerability over time.This overview calls for a paradigm shift in cardiometabolic care,moving beyond anthropometric parameters toward a more refined assessment that incorporate inflammatory biomarkers,fat distribution and sex-specific factors.Recognizing these underlying biological and phenotypic differences enables more accurate CV risk stratification and supports the development of precision-based therapeutic strategies.Ultimately,understanding not just who is at risk,but why,is essential to improving prevention and outcomes across diverse populations facing the bur-den of obesity. 展开更多
关键词 Cardiovascular risk Epicardial adipose tissue INFLAMMATION Metabolically healthy obesity Metaflammation OBESITY Sex differences Visceral fat
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Beyond the optic disc:Investigating gender-based differences in optic neuritis
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作者 Marco Zeppieri Simonetta Gaia Nicolosi +6 位作者 Fabiana D’Esposito Mutali Musa Alessandro Avitabile Caterina Gagliano Marco Battista Piero Barboni Matteo Capobianco 《World Journal of Clinical Cases》 2025年第32期23-36,共14页
Optic neuritis(ON)is a focal inflammatory demyelinating disorder of the optic nerve.Although classically regarded as a sentinel event for multiple sclerosis(MS),ON also occurs in antibody-mediated entities such as aqu... Optic neuritis(ON)is a focal inflammatory demyelinating disorder of the optic nerve.Although classically regarded as a sentinel event for multiple sclerosis(MS),ON also occurs in antibody-mediated entities such as aquaporin-4-IgGpositive neuromyelitis optica spectrum disorder(AQP4-NMOSD)and myelinoligodendrocyte-glycoprotein-antibody disease.In all these settings biological sex is a pivotal determinant of susceptibility,clinical expression,treatment response and long-term outcome.Data synthesized from an extensive literature analysis utilizing PubMed,Scopus,and Web of Science in this review shows that women experience ON far more frequently–with female-to-male ratios ranging from 3:1 in MS to almost 9:1 in AQP4-NMOSD–yet men,when affected,tend to accumulate irreversible neuro-axonal loss more rapidly.Sex-specific patterns arise at every biological stratum:X-linked gene dosage,epigenetic regulation,hormonal cycles from puberty through menopause,metabolic co-modifiers such as obesity and vitamin-D status,and psychosocial forces that influence healthcare utilization.By weaving these elements into an expanded narrative,the present review provides a detailed resource for clinicians and investigators aiming at gender-tailored management of ON. 展开更多
关键词 Optic neuritis Gender differences Neuromyelitis optica spectrum disorder Myelin oligodendrocyte glycoprotein antibody disease Optic nerve
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Mechanical differences of laminations and crack propagation mechanism of continental shale
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作者 Yong-Ting Duan Cheng-Cheng Zhu +3 位作者 Pathegama Gamage Ranjith Bai-Cun Yang Tian-Qiao Mao Yu Li 《Petroleum Science》 2025年第4期1653-1669,共17页
Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of con... Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of continental shale oil reservoir.The Chang 72continental shale was used to investigate the mechanical properties of laminations and the effect of natural structure on the crack propagation of the shale.The XRD and thin section tests show that the laminations contain two types:bright sandy lamination with void structure and dark muddy lamination with layer structure.The real-time CT uniaxial compression tests were conducted to investigate the differences of mechanical properties between the muddy lamination and sandy lamination.It found that the uniaxial compression strength and elastic modulus of the sandy lamination are higher,forming a simple crack with large opening,and the Poisson's ratio of the muddy lamination is large,forming obvious lateral deformation and more secondary cracks.On this basis,the cuboid-shaped continental shale specimens were tested under true triaxial compression conditions to study the effect of laminations and interface cracks on crack propagation combining AE and CT techniques.It found that nascent cracks connected laminations and interface cracks to form fracture network under appropriate loading condition,tensile cracks developed in sandy lamination and shear cracks occurred in muddy lamination because of deformation dissonance and brittleness index differences,and more secondary cracks formed in muddy lamination with smaller fracture toughness.Moreover,the combination relationships between nascent and natural cracks mainly conclude direct penetration and deflection,which is affected by the filling degree and morphology of interface cracks and the relationship of lamination types.These conclusions show that laminar continental shale is conducive to forming complex fracture network,which can provide a theoretical basis for the proposal of indicators and methods for fracability evaluation. 展开更多
关键词 Continental shale oil Mechanical properties of different lamination types True triaxial compression test Structure control mechanism Fracability evaluation
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HEMP与典型建筑物作用的FDTD分析
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作者 冯浩南 何欣波 +1 位作者 陈萌 魏兵 《现代应用物理》 2025年第3期86-92,共7页
针对强脉冲对室内设备的影响,模拟计算了半空间情形下典型建筑在高空核爆电磁脉冲(high-altitude nuclear explosion electromagnetic pulse,HEMP)入射情形下内部的场分布情况。为提高计算效率,采用半解析快速半空间计算方法,通过引入... 针对强脉冲对室内设备的影响,模拟计算了半空间情形下典型建筑在高空核爆电磁脉冲(high-altitude nuclear explosion electromagnetic pulse,HEMP)入射情形下内部的场分布情况。为提高计算效率,采用半解析快速半空间计算方法,通过引入双向入射波从而考虑半空间的影响,并采用基于消息传递接口(message passing interface,MPI)的FDTD并行算法,进一步提高计算效率。计算结果表明,在HEMP入射情形下,建筑物内部电场分布主要受钢筋结构的影响。进一步分析表明,在建筑物中不同空间位置处,钢筋结构对电磁脉冲的屏蔽效果影响较大。本文研究可为典型建筑物的抗核爆辐射加固提供参考。 展开更多
关键词 时域有限差分法 高空核爆电磁脉冲 电磁屏蔽 半空间加源 典型建筑物
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基于LOD-FDTD的探地雷达正演模拟
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作者 王波桦 沈鸿雁 +6 位作者 车晗 刘帅 王驰 张成伟 王昊 封士圣 王康龙 《工程地球物理学报》 2025年第4期632-644,共13页
探地雷达(Ground Penetrating Radar,GPR)正演模拟是解译和反演实测GPR数据的基础。然而,使用传统时域有限差分方法(Finite Difference Time Domain,FDTD)实现GPR正演模拟时,时间步长受到Courant Friedrichs Lewy(CFL)条件严格限制,存... 探地雷达(Ground Penetrating Radar,GPR)正演模拟是解译和反演实测GPR数据的基础。然而,使用传统时域有限差分方法(Finite Difference Time Domain,FDTD)实现GPR正演模拟时,时间步长受到Courant Friedrichs Lewy(CFL)条件严格限制,存在运算耗时较长的问题,为此,提出使用局部一维隐式时域有限差分方法(Locally One Dimension Finite Difference Time Domain,LOD-FDTD)实现二维GPR正演模拟。LOD-FDTD使用Crank-Nicolson方法从FDTD中推导得到,该方法的时间步长不受CFL条件限制,能够使用大时间步快速完成GPR正演模拟。对均质模型以及含多层界面和多个地质体的复杂地质模型进行GPR正演模拟实验,结果表明,在占用内存空间小于120MB的情况下,LOD-FDTD方法能够使用FDTD最大时间步长2倍以上的时间步长,有效地计算雷达波在地下空间的传播过程,并获得不同地质体的GPR响应信号,证明了本文方法具有占用内存适中、运算速度快、求解精度好等优点,较传统FDTD能够快速、高效地实现GPR正演模拟。 展开更多
关键词 探地雷达 正演模拟 时域有限差分 局部一维时域有限差分 卷积完美匹配层
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基于FDTD亚网格的地面LEMP波传播特性分析
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作者 刘育佳 张玉强 《延安大学学报(自然科学版)》 2025年第2期90-97,共8页
地闪回击电磁脉冲(LEMP)具有幅值高、频谱宽和辐射范围广等特点,会与电子电气设备发生电磁耦合,干扰其正常运行甚至造成毁伤,因此,研究LEMP传播特性具有重要意义。然而在进行LEMP特性FDTD分析时,采用均匀网格会使计算区域网格数急剧增加... 地闪回击电磁脉冲(LEMP)具有幅值高、频谱宽和辐射范围广等特点,会与电子电气设备发生电磁耦合,干扰其正常运行甚至造成毁伤,因此,研究LEMP传播特性具有重要意义。然而在进行LEMP特性FDTD分析时,采用均匀网格会使计算区域网格数急剧增加,导致计算出现困难。本文将Huygens亚网格技术引入LEMP传播特性FDTD分析,在靠近回击通道的区域采用细网格,而在远离回击通道的区域采用粗网格,粗细网格间通过Huygens等效面实现电磁耦合,实现了LEMP的广域计算。并将算法用于不同类型、湿度土壤情况下LEMP远距离传播时水平电场Er和垂直电场Ez的影响分析。研究结果可为电磁屏蔽和雷电防护工作提供理论依据。 展开更多
关键词 雷电电磁脉冲 传播特性 亚网格 时域有限差分法(Fdtd)
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基于FDTD的隧道衬砌缺陷雷达检测分辨率研究
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作者 田云程 刘晓甲 《工程地球物理学报》 2025年第5期565-573,共9页
针对探地雷达(Ground Penetrating Radar,GPR)在实际检测中因电磁波衰减、噪声干扰及多路径反射导致分辨率受限的问题,本文基于时域有限差分法(Finite-difference Time-domain,FDTD)构建数值模型,结合GPRmax仿真软件,系统研究了不同频... 针对探地雷达(Ground Penetrating Radar,GPR)在实际检测中因电磁波衰减、噪声干扰及多路径反射导致分辨率受限的问题,本文基于时域有限差分法(Finite-difference Time-domain,FDTD)构建数值模型,结合GPRmax仿真软件,系统研究了不同频率天线(400 MHz/900 MHz)对隧道衬砌脱空、钢筋分布不均等缺陷的垂直与水平分辨率特性及其影响因素。通过精细化建模与物理试验验证,揭示了天线频率、缺陷尺寸及埋深与分辨率之间的内在关联机制。研究通过分层脱空模型和钢筋间距模型开展数值模拟,量化了垂直分辨率与水平分辨率的理论极限。研究表明,高频天线(900 MHz)在浅层可实现λ_(1)/10的垂直分辨率和0.15 m的水平分辨率,而低频天线(400 MHz)虽分辨率下限为λ_(2)/8且水平分辨需0.20 m间距;埋深增加会导致菲涅尔带直径扩展,高频天线(900 MHz)分辨率随深度下降更显著。本文通过FDTD方法实现了隧道衬砌多缺陷模型的电磁场动态响应模拟,揭示了天线频率选择需权衡分辨率与探测深度的矛盾,提出多频数据融合策略以提升复杂工况下的检测精度。 展开更多
关键词 时域有限差分法(Fdtd) 探地雷达 隧道衬砌缺陷 分辨率 数值模拟
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