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On Tensor Spaces for Rook Monoid Algebras
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作者 Zhan Kui XIAO 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2016年第5期607-620,共14页
Let m, n ∈ N, and V be an m-dimensional vector space over a field F of characteristic 0. Let U = F + V and Rn be the rook monoid. In this paper, we construct a certain quasi-idempotent in the annihilator of U^×... Let m, n ∈ N, and V be an m-dimensional vector space over a field F of characteristic 0. Let U = F + V and Rn be the rook monoid. In this paper, we construct a certain quasi-idempotent in the annihilator of U^×n in FRn, which comes from some one-dimensional two-sided ideal of rook monoid algebra. We show that the two-sided ideal generated by this element is indeed the whole annihilator of U^×n in FR^n. 展开更多
关键词 Rook monoid tensor space general linear group symmetric group
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CANONICAL REPRESENTATIONS AND DEGREE OF FREEDOM FORMULAE OF ORTHOGONAL TENSORS IN N-DIMENSIONAL EUCLIDEAN SPACE
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作者 熊祝华 郑泉水 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第1期93-101,共9页
In this paper, with the help of the eigenvalue properties of orthogonal tensors in n-dimensional Euclidean space and the representations of the orthogonal tensors in 2-dimensional space, the canonical representations ... In this paper, with the help of the eigenvalue properties of orthogonal tensors in n-dimensional Euclidean space and the representations of the orthogonal tensors in 2-dimensional space, the canonical representations of orthogonal tensors in n-dimensional Euclidean space are easily gotten. The paper also gives all the constraint relationships among the principal invariants of arbitrarily given orthogonal tensor by use of Cayley-Hamilton theorem; these results make it possible to solve all the eigenvalues of any orthogonal tensor based on a quite reduced equation of m-th order, where m is the integer part ofn \2. Finally, the formulae of the degree of freedom of orthogonal tensors are given. 展开更多
关键词 CANONICAL REPRESENTATIONS AND DEGREE OF FREEDOM FORMULAE OF ORTHOGONAL tensorS IN N-DIMENSIONAL EUCLIDEAN space exp
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Tensor Product of 2-Frames in 2-Hilbert Spaces
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作者 G. Upender Reddy 《Advances in Pure Mathematics》 2016年第8期517-522,共6页
2-frames in 2-Hilbert spaces are studied and some results on it are presented. The tensor product of 2-frames in 2-Hilbert spaces is introduced. It is shown that the tensor product of two 2-frames is a 2-frame for the... 2-frames in 2-Hilbert spaces are studied and some results on it are presented. The tensor product of 2-frames in 2-Hilbert spaces is introduced. It is shown that the tensor product of two 2-frames is a 2-frame for the tensor product of Hilbert spaces. Some results on tensor product of 2-frames are established. 展开更多
关键词 tensor Product 2-Inner Product spaces FRAMES 2-Frames
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Targeting the brain’s glymphatic pathway:A novel therapeutic approach for cerebral small vessel disease
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作者 Yuhui Ma Yan Han 《Neural Regeneration Research》 2026年第2期433-442,共10页
Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological me... Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease. 展开更多
关键词 AQUAPORIN-4 ASTROCYTES cerebral amyloid angiopathy cerebral small vessel disease cerebrospinal fluid diffusion tensor image analysis along the perivascular space glymphatic system interstitial fluid perivascular space therapeutic strategies
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ON THE CENTRAL LIMIT THEOREM IN PRODUCT SPACES
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作者 SU ZHONGGEN 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 1995年第4期367-378,共12页
Suppose that E and F are separable Banach spaces, X and Y are independent symmetric E and F-valued random vectors respectively. This paper is devoted to the study of the central limit theorem for X Y in the injective... Suppose that E and F are separable Banach spaces, X and Y are independent symmetric E and F-valued random vectors respectively. This paper is devoted to the study of the central limit theorem for X Y in the injective and projective tensor product spaces E F and E F. Special attention is paid to l2 l2. In addition, two counter-examples are given. 展开更多
关键词 Central limit theorem injective and projective tensor product spaces Gaussian process.
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Projective Tensor Products of <i>C*</i>-Algebras
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作者 Ajay Kumar Vandana Rajpal 《Advances in Pure Mathematics》 2014年第5期176-188,共13页
For C*-algebras A and B, the constant involved in the canonical embedding of into is shown to be . We also consider the corresponding operator space version of this embedding. Ideal structure of is obtained in case A ... For C*-algebras A and B, the constant involved in the canonical embedding of into is shown to be . We also consider the corresponding operator space version of this embedding. Ideal structure of is obtained in case A or B has only finitely many closed ideals. 展开更多
关键词 Banach space PROJECTIVE tensor NORM Operator space PROJECTIVE tensor NORM
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YANG-BAXTER OPERATORS AND TENSOR TRANSFORMATIONS
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作者 汪振华 《Acta Mathematica Scientia》 SCIE CSCD 2002年第3期427-432,共6页
The author considers relations between Yang-Baxter operators and tensor transformations, and proves that all tensor transform at ions over the category of modules of a Yang-space form a group.
关键词 Yang-Baxter operators Yang-space tensor transformations
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Flat Space-Time and Motion in Gravitational Field
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作者 Zhang Junhao Chen Xiang (Department of Physics, Shantou University Shantou, Guangdong 515063, P. R. China) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1995年第4期273-284,共12页
Two fundamental hypotheses of special relativistic gravitational theory are: (1) the equivalence of gravitational mass and inertial mass, (2) the equation of the gravitational tensor potential in linear approximat... Two fundamental hypotheses of special relativistic gravitational theory are: (1) the equivalence of gravitational mass and inertial mass, (2) the equation of the gravitational tensor potential in linear approximation. Main results: (1) the values of the planetary perihelion shill, and the angle of deflection of light are the same as those of general relativity. The value of the red shill is consistent with the experiment. One cannot use these experimental values to judge whether space-time is curved. (2) In GP-B experiment, the gyroscope will be acted on by the additional gravitational fields due to the Earth's spin (S) and the orbital motion of satellite (L). The average precession rates are , where β and δ are the gyroscope's polar angles, (S) and (G) designate values deduced from special and general relativity, respectively. The GP-B experiment is the first one to judge whether space-time is flat. 展开更多
关键词 GRAVITY Coupling coefficient tensor potential Flat space-time.
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Einstein’s Pseudo-Tensor in <i>n</i>Spatial Dimensions for Static Systems with Spherical Symmetry
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作者 Frank R. Tangherlini 《Journal of Modern Physics》 2013年第9期1200-1204,共5页
It was noted earlier that the general relativity field equations for static systems with spherical symmetry can be put into a linear form when the source energy density equals radial stress. These linear equations lea... It was noted earlier that the general relativity field equations for static systems with spherical symmetry can be put into a linear form when the source energy density equals radial stress. These linear equations lead to a delta function energymomentum tensor for a point mass source for the Schwarzschild field that has vanishing self-stress, and whose integral therefore transforms properly under a Lorentz transformation, as though the particle is in the flat space-time of special relativity (SR). These findings were later extended to n spatial dimensions. Consistent with this SR-like result for the source tensor, Nordstrom and independently, Schrodinger, found for three spatial dimensions that the Einstein gravitational energy-momentum pseudo-tensor vanished in proper quasi-rectangular coordinates. The present work shows that this vanishing holds for the pseudo-tensor when extended to n spatial dimensions. Two additional consequences of this work are: 1) the dependency of the Einstein gravitational coupling constant κ on spatial dimensionality employed earlier is further justified;2) the Tolman expression for the mass of a static, isolated system is generalized to take into account the dimensionality of space for n ≥ 3. 展开更多
关键词 Field EQUATIONS Point Particle Dimensionality of space Einstein’s Pseudo-tensor
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Space-Time Curvature Mode Quanta
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作者 Philipp Kornreich 《Journal of Modern Physics》 2020年第12期1977-1992,共16页
Einstein theorized that Gravity is not a force derived from a potential that acts across a distance. It is a distortion of space and time in which we live by masses and energy. Consistent with Einstein’s theory, a mo... Einstein theorized that Gravity is not a force derived from a potential that acts across a distance. It is a distortion of space and time in which we live by masses and energy. Consistent with Einstein’s theory, a model of space-time curvature modes and associated curvature quanta in slightly warped space-time generated by a light Photon is derived. Both a Schr<span style="white-space:nowrap;">?</span>dinger and a Second Quantized representation of the space-time curvature mode quanta are calculated and are fourth rank tensors. The eigenvalues of these equations are radii of curvature, not energy. The Eigenfunctions are linear functions of the components of the tensor that describes the curvature of space-time. 展开更多
关键词 PHOTONS PHONONS GRAVITY General Relativity space-TIME Radius of Curvature tensor
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基于多尺度3D-CNN-CBAM的空气质量指数时空预测
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作者 刘金培 罗瑞 +1 位作者 陈华友 周礼刚 《控制与决策》 北大核心 2025年第2期404-412,共9页
精确地把握空气质量指数(AQI)的实时动态演变规律对大气污染防治和城市公共卫生治理至关重要.因此,通过构建三维空间张量,将AQI特征信息由时间维度扩展至时空维度,并提出一种基于多尺度三维卷积注意力机制的时空预测网络模型,以提高AQI... 精确地把握空气质量指数(AQI)的实时动态演变规律对大气污染防治和城市公共卫生治理至关重要.因此,通过构建三维空间张量,将AQI特征信息由时间维度扩展至时空维度,并提出一种基于多尺度三维卷积注意力机制的时空预测网络模型,以提高AQI预测精度.预测方法首先对相关影响因素数据进行有效筛选.其次,将AQI数据及其影响因素分解为不同模态下的子序列.进而,基于时间、空间地理位置和影响因素3个维度,构建三维空间张量,以反映AQI数据的时空特征演变.然后,设计三维卷积注意力机制网络模型对子序列进行预测,以有效提取AQI与其影响因素之间的关键时空关联性特征.通过学习局部AQI序列特征的重要程度,该模型能够对空间时域信息赋予不同权重,以增强关键信息的影响力.将所提出的方法应用于3大城市群2019年~2024年的日度AQI预测,结果表明,该方法适用于具有时空属性的AQI预测,与现有方法相比具有更高的预测精度和适用性. 展开更多
关键词 时空预测 空气质量指数 卷积神经网络 注意力机制 三维空间张量 多元经验模态分解
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Spin and Quantization of Gravitational Space
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作者 Bin Liang 《Journal of Modern Physics》 2012年第11期1757-1762,共6页
According to the formula of translational motion of vector along an infinitesimal closed curve in gravitational space, this article shows that the space and time both are quantized;the called center singularity of Sch... According to the formula of translational motion of vector along an infinitesimal closed curve in gravitational space, this article shows that the space and time both are quantized;the called center singularity of Schwarzschild metric does not exist physically, and Einstein’s theory of gravity is compatible with the traditional quantum theory in essence;the quantized gravitational space is just the spin network which consists of infinite quantized loops linking and intersecting each other, and that whether the particle is in spin eigenstate depends on the translational track of its spin vector in gravitational space. 展开更多
关键词 QUANTIZATION of GRAVITATIONAL space TRANSLATIONAL Motion of Vector Curvature Area tensor SPIN Network SPIN EIGENSTATE
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General Relativity without Curved Space-Time (&#8370;R)
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作者 Abed El Karim S. Abou Layla 《Journal of High Energy Physics, Gravitation and Cosmology》 2019年第1期156-166,共11页
The theory of general relativity is related to the concept of curvature of space- time induced by the presence of the massive objects. We will see through this paper that the general relativity can be linked with line... The theory of general relativity is related to the concept of curvature of space- time induced by the presence of the massive objects. We will see through this paper that the general relativity can be linked with linear Algebra and Vector Analysis without the need for concept of space-time. This is important for the unification of general relativity with quantum mechanics, gravity with electromagnetic, and a better understanding of the universe, gravity, black holes. The most important is the separation between the space-time and the big bang theory, which prove the existence of space-time before that, which leads to the existence of the creator of the universe. 展开更多
关键词 Gravity Electromagnetism BIG Bang space-TIME General RELATIVITY LORENTZ Force Density The Einstein’s tensor
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基于磁共振成像的脑类淋巴功能指标在评估系统性红斑狼疮患者神经功能损害中的应用研究
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作者 崔彩霞 谷磊磊 +2 位作者 李林芳 杨存 高铎 《脑与神经疾病杂志》 2025年第11期661-667,共7页
目的 本研究旨在利用沿血管周围间隙扩散张量成像方法(DTI-ALPS)研究系统性红斑狼疮(SLE)患者的脑类淋巴功能,并探讨DTI-ALPS指数与不同脑区血管周围间隙(PVS)之间的关系。方法 本研究共纳入65例非神经精神性系统性红斑狼疮(non-NPSLE)... 目的 本研究旨在利用沿血管周围间隙扩散张量成像方法(DTI-ALPS)研究系统性红斑狼疮(SLE)患者的脑类淋巴功能,并探讨DTI-ALPS指数与不同脑区血管周围间隙(PVS)之间的关系。方法 本研究共纳入65例非神经精神性系统性红斑狼疮(non-NPSLE)患者、46例神经精神性系统性红斑狼疮(NPSLE)患者和39例健康对照者(HCs组)。所有受试者均行磁共振成像检查,包括T1WI、T2WI、3DT1和DTI。计算每位受试者的DTI-ALPS指数、在T2WI序列上定量测定基底核(BG)、侧脑室(LVB)、半卵圆中心(CSO)的PVS,计算3个区域PVS占总灰质和白质体积的比例,得到BG-PVS%、LVB-PVS%、CSO-PVS%。通过调整协变量,采用偏相关分析评价DTI-ALPS指数与PVS%之间的关系。结果non-NPSLE组和NPSLE组左侧、右侧、平均DTI-ALPS指数均低于HCs组。non-NPSLE组和NPSLE组患者BG-PVS%、LVB-PVS%和CSO-PVS%高于HCs组。non-NPSLE组与NPSLE组DTI-ALPS指数和PVS%差异无统计学意义。偏相关分析显示SLE患者DTI-ALPS与LVB-PVS%呈中度负相关(r=-0.41,P<0.001)。结论 基于磁共振成像的DTI-ALPS指数提示SLE患者脑类淋巴功能受损,这些变化与LVB区PVS增大有关。 展开更多
关键词 沿血管周围间隙弥散张量成像方法 脑类淋巴系统 血管周围间隙 系统性红斑狼疮
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Riemannian Space-Time, de Donder Conditions and Gravitational Field in Flat Space-Time 被引量:1
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作者 Gordon Liu 《International Journal of Astronomy and Astrophysics》 2013年第1期8-19,共12页
Let the coordinate system xi of flat space-time to absorb a second rank tensor field Φij of the flat space-time deforming into a Riemannian space-time, namely, the tensor field Φuv is regarded as a metric tensor wit... Let the coordinate system xi of flat space-time to absorb a second rank tensor field Φij of the flat space-time deforming into a Riemannian space-time, namely, the tensor field Φuv is regarded as a metric tensor with respect to the coordinate system xu. After done this, xu is not the coordinate system of flat space-time anymore, but is the coordinate system of the new Riemannian space-time. The inverse operation also can be done. According to these notions, the concepts of the absorption operation and the desorption operation are proposed. These notions are actually compatible with Einstein’s equivalence principle. By using these concepts, the relationships of the Riemannian space-time, the de Donder conditions and the gravitational field in flat space-time are analyzed and elaborated. The essential significance of the de Donder conditions (the harmonic conditions or gauge) is to desorb the tensor field of gravitation from the Riemannian space-time to the Minkowski space-time with the Cartesian coordinates. Einstein equations with de Donder conditions can be solved in flat space-time. Base on Fock’s works, the equations of gravitational field in flat space-time are obtained, and the tensor expression of the energy-momentum of gravitational field is found. They all satisfy the global Lorentz covariance. 展开更多
关键词 General Relativity Gravitation RIEMANNIAN space-TIME FLAT space-TIME Einstein Equations Harmonic CONDITIONS ENERGY-MOMENTUM tensor Significance of the Coordinates Gravitational RED-SHIFT
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基于单张量辐射场的数字服装重照明方法
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作者 陈鑫磊 郑军红 +1 位作者 金耀 何利力 《丝绸》 CAS 北大核心 2025年第1期85-93,共9页
针对现有基于三维表面重建的图像重照明方法存在纹理噪点、重照明质量不足及特征空间利用率低等问题,文章提出一种基于单张量辐射场的数字服装重照明方法。该方法首先利用球面高斯函数和多层感知机,分别模拟环境直射光和服装表面间的间... 针对现有基于三维表面重建的图像重照明方法存在纹理噪点、重照明质量不足及特征空间利用率低等问题,文章提出一种基于单张量辐射场的数字服装重照明方法。该方法首先利用球面高斯函数和多层感知机,分别模拟环境直射光和服装表面间的间接反射光,以构建一个精准的入射光场;接着通过引入梯度引导平滑策略,优化从特征空间中提取双向反射分布函数模型参数的过程。最后,利用简化的反射率方程,结合入射光场、双向反射分布模型及特征空间,成功地渲染出高质量的服装重照明图像。实验结果表明,该方法有效地减少了服装纹理噪点,显著降低了服装重照明的失真现象。相较于先进方法,该方法在生成服装新视角图像方面,各项评估指标的平均提升约9.922%;在服装重照明结果方面,各项评估指标的平均提升约4.549%。 展开更多
关键词 单张量辐射场 特征空间 服装重照明 3D维重建 图像生成 双向反射分布函数
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近期皮质下小梗死患者血管周围间隙扩大与脑类淋巴系统功能及认知功能的相关性研究
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作者 张雪 张敏 恽文伟 《中国脑血管病杂志》 北大核心 2025年第7期453-464,共12页
目的探讨近期皮质下小梗死(RSSI)患者不同区域血管周围间隙扩大(EPVS)与脑类淋巴系统(GS)功能及认知功能的相关性。方法回顾性连续纳入南京医科大学第三附属医院(常州市第二人民医院)神经内科2023年12月至2024年12月住院治疗的RSSI患者... 目的探讨近期皮质下小梗死(RSSI)患者不同区域血管周围间隙扩大(EPVS)与脑类淋巴系统(GS)功能及认知功能的相关性。方法回顾性连续纳入南京医科大学第三附属医院(常州市第二人民医院)神经内科2023年12月至2024年12月住院治疗的RSSI患者。收集患者的基线及临床资料,包括年龄、性别、体质量指数(BMI)、吸烟史、饮酒史、高血压病、糖尿病、心房颤动、冠心病、入院实验室检查指标(包括同型半胱氨酸、总胆固醇、三酰甘油、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇、糖化血红蛋白、尿酸、肌酐等)。发病后7 d内采用简易精神状态检查(MMSE)量表和蒙特利尔认知评估(MoCA)量表(包括视空间与执行功能、命名能力、注意力、语言能力、抽象思维、延迟回忆能力及定向力7个认知域)进行认知功能评估。所有患者入院后3 d内完善头部MRI检查,序列包括弥散张量成像(DTI)等。采用沿血管周围间隙DTI分析(DTI-ALPS)后处理工具计算大脑左、右侧DTI-ALPS指数并取其平均值作为分析指标,以评估RSSI患者整体GS功能。测量基底节(BG)区和半卵圆中心(CSO)区的EPVS体积,根据Potter标准视觉量化评估结果将EPVS程度分为0、1、2、3、4级,0~1级为无-轻度组,2~4级为中重度组,并进一步按区域分为BG-EPVS和CSO-EPVS的无-轻度组与中重度组,比较各组RSSI患者的基线及临床资料、DTI-ALPS指数及认知功能评分。采用方差膨胀因子对基线及临床资料单因素分析中P<0.05的变量进行共线性检验,将其中不存在多重共线性的指标纳入多因素Logistic回归分析,以筛选RSSI患者BG-EPVS严重程度的独立影响因素,为评估DTI-ALPS指数预测BG-EPVS严重程度结果的稳健性,采用离群值诊断与剔除分析方法识别并剔除异常样本,重新构建多因素Logistic回归模型进行分析。采用Spearman相关分析评估BG-EPVS体积与DTI-ALPS指数、MMSE量表评分、MoCA量表及其各项认知域评分的相关性,并通过中介分析检验DTI-ALPS指数在BG-EPVS体积与MoCA量表评分间的中介效应。结果共纳入65例RSSI患者,男34例,女31例,年龄37~78岁,平均(53±15)岁。其中总体EPVS无-轻度组30例,EPVS中重度组35例;BG-EPVS无-轻度组34例,BG-EPVS中重度组31例;CSO-EPVS无-轻度组36例,CSO-EPVS中重度组29例。(1)单因素分析结果显示,在总体EPVS和BG-EPVS患者中,与中重度组比较,无-轻度组年龄、男性患者比例和高血压病患者比例均更低,DTI-ALPS指数、MMSE量表评分和MoCA量表评分均更高(均P<0.05),余基线及临床资料的组间差异均无统计学意义(均P>0.05)。在CSO-EPVS患者中,与中重度组比较,无-轻度组仅年龄更低(P<0.05),余基线及临床资料的组间差异均无统计学意义(均P>0.05)。(2)多重共线性分析结果显示,年龄、性别、高血压病、DTI-ALPS指数不存在多重共线性。多因素Logistic回归分析结果显示,高龄(OR=4.410,95%CI:1.211~16.025,P=0.024)、男性(OR=1.076,95%CI:1.001~1.156,P=0.048)、高血压病(OR=6.287,95%CI:1.635~24.167,P=0.007)为RSSI患者发生中重度BG-EPVS的独立危险因素,高DTI-ALPS指数(OR=0.002,95%CI:0.000~0.904,P=0.046)为RSSI患者发生中重度BG-EPVS的独立保护因素。为进一步评估模型结果的稳健性,识别并剔除6例异常样本后,DTI-ALPS指数与RSSI患者BG-EPVS发生风险的负相关性仍然存在(OR=0.050,95%CI:0.003~0.974,P=0.048)。(3)Spearman相关性分析结果显示,RSSI患者的BG-EPVS体积与DTI-ALPS指数(r_(s)=-0.842,P=0.007)、MMSE量表评分(r_(s)=-0.491,P=0.033)、MoCA量表评分(r_(s)=-0.563,P=0.018)、视空间与执行功能评分(r_(s)=-0.596,P=0.001)均成负相关;BG-EPVS体积与命名能力、注意力、语言能力、抽象思维、延迟回忆能力和定向力评分无相关性(均P>0.05)。(4)中介分析结果显示,BG-EPVS体积对RSSI患者MoCA量表评分的总效应值为-0.673,其中直接效应值为-0.537,占总效应值的79.79%,间接效应值为-0.136,占总效应值的20.21%。结论在RSSI患者中,年龄、性别、高血压病及DTI-ALPS指数是BG-EPVS严重程度的独立影响因素。BG-EPVS体积与RSSI患者DTI-ALPS指数及认知功能评分均成负相关,且DTI-ALPS指数在RSSI患者BG-EPVS体积与认知功能之间发挥中介作用。 展开更多
关键词 近期皮质下小梗死 血管周围间隙扩大 脑类淋巴系统 沿血管周围间隙弥散张量成像分析 认知功能
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脑小血管病患者DTI-ALPS及血管周围间隙改变及其与认知功能的关联性研究 被引量:1
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作者 赵婧含 常佩佩 +5 位作者 杜伟 曹家骏 王嫚 胡帅 宋清伟 苗延巍 《磁共振成像》 北大核心 2025年第3期31-37,共7页
目的采用沿血管周围间隙的扩散张量成像分析(diffusion tensor imaging analysis along the perivascular space,DTI-ALPS)指标及血管周围间隙扩大(enlarged perivascular space,EPVS)状态评价脑小血管疾病(cerebral small vessel disea... 目的采用沿血管周围间隙的扩散张量成像分析(diffusion tensor imaging analysis along the perivascular space,DTI-ALPS)指标及血管周围间隙扩大(enlarged perivascular space,EPVS)状态评价脑小血管疾病(cerebral small vessel disease,CSVD)患者的类淋巴功能,并探究其与认知功能的关系。材料与方法前瞻性纳入CSVD组(81例)和健康对照组(20例)的临床资料,根据神经心理学量表评估结果将CSVD患者分为认知正常组(CSVD-NC组,27例)、轻度认知障碍(mild cognitive impairment,MCI)组(CSVD-MCI组,31例)和血管性痴呆(vascular dementia,VaD)组(CSVD-VaD组,23例)。所有被试行常规MRI序列、扩散张量成像(diffusion tensor imaging,DTI)检查。对所有被试的基底神经节(basal ganglio,BG)以及半卵圆中心(centrum semi-ovale,CSO)的EPVS等级进行量化评分;并测量ALPS指标(ALPS-index)。比较EPVS等级及ALPS指标的组间差异,分析影像指标与认知评分的关系,并进一步进行多元线性回归分析。结果与HC组相比,CSVD-NC组、CSVD-MCI组、CSVD-VaD组的ALPS指标均降低,CSVD-MCI组、CSVD-VaD组的BG-EPVS等级评分及CSO-EPVS等级评分均增高(P<0.05)。相关性分析显示,CSVD患者的BG-EPVS等级与ALPS指标、MoCA评分、MMSE评分均呈负相关(r=-0.291,P=0.008;r=-0.342,P=0.002;r=-0.309,P=0.005);同时,ALPS指标与MoCA评分、MMSE评分呈正相关(r=0.226,P=0.043;r=0.225,P=0.044)。回归分析结果显示,BG-EPVS等级评分是MoCA评分及MMSE评分的独立影响因素(β=-0.294,P=0.009;β=-0.274,P=0.017)。结论CSVD患者的DTI-ALPS指标及EPVS等级评分均发生不同程度改变,提示存在类淋巴系统功能损害,且与认知功能障碍密切相关。 展开更多
关键词 脑小血管疾病 沿血管周围间隙的扩散张量成像分析 磁共振成像 类淋巴系统 认知功能 血管周围间隙
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Gravitational Space-Time Curve Generation via Accelerated Charged Particles
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作者 Edward A. Walker 《Journal of Modern Physics》 2016年第9期863-874,共12页
A force with an acceleration that is equal to multiples greater than the speed of light per unit time is exerted on a cloud of charged particles. The particles are resultantly accelerated to within an infinitesimal fr... A force with an acceleration that is equal to multiples greater than the speed of light per unit time is exerted on a cloud of charged particles. The particles are resultantly accelerated to within an infinitesimal fraction of the speed of light. As the force or acceleration increases, the particles’ velocity asymptotically approaches but never achieves the speed of light obeying relativity. The asymptotic increase in the particles’ velocity toward the speed of light as acceleration increasingly surpasses the speed of light per unit time does not compensate for the momentum value produced on the particles at sub-light velocities. Hence, the particles’ inertial mass value must increase as acceleration increases. This increase in the particles’ inertial mass as the particles are accelerated produce a gravitational field which is believed to occur in the oscillation of quarks achieving velocities close to the speed of light. The increased inertial mass of the density of accelerated charged particles becomes the source mass (or Big “M”) in Newton’s equation for gravitational force. This implies that a space-time curve is generated by the accelerated particles. Thus, it is shown that the acceleration number (or multiple of the speed of light greater than 1 per unit of time) and the number of charged particles in the cloud density are surjectively mapped to points on a differential manifold or space-time curved surface. Two aspects of Einstein’s field equations are used to describe the correspondence between the gravitational field produced by the accelerated particles and the resultant space-time curve. The two aspects are the Schwarzchild metric and the stress energy tensor. Lastly, the possibility of producing a sufficient acceleration or electromagnetic force on the charged particles to produce a gravitational field is shown through the Lorentz force equation. Moreover, it is shown that a sufficient voltage can be generated to produce an acceleration/force on the particles that is multiples greater than the speed of light per unit time thereby generating gravity. 展开更多
关键词 Charged Particles Accelerated Particles Inertial Mass Gravitational Force Einstein’s Field Equations space-Time Manifold Schwardchild Metric Stress Energy tensor Surjective Mapping Lorentz Force
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基于DTI-ALPS指数分析不同亚型发作性睡病患者类淋巴系统功能改变
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作者 胡鹏鑫 邹宇 +6 位作者 袁于青 熊瑞芳 李承毅 朱涵婷 周明玉 谢亮 唐小平 《放射学实践》 北大核心 2025年第3期295-301,共7页
目的:基于血管周围间隙扩散张量成像(DTI-ALPS)分析不同亚型发作性睡病(NT)患者的类淋巴系统功能改变及其与临床参数的关系,并进一步探讨类淋巴系统系统功能指标区分不同亚型NT的价值。方法:收集2022年9月-2024年2月在南昌大学第二附属... 目的:基于血管周围间隙扩散张量成像(DTI-ALPS)分析不同亚型发作性睡病(NT)患者的类淋巴系统功能改变及其与临床参数的关系,并进一步探讨类淋巴系统系统功能指标区分不同亚型NT的价值。方法:收集2022年9月-2024年2月在南昌大学第二附属医院确诊的31名1型发作性睡病(NT1)和15名2型发作性睡病(NT2)患者及年龄性别相匹配的30名健康对照者(HC)。受试者进行Epworth嗜睡量表(ESS)、匹兹堡睡眠质量指数量表(PSQI)评分,所有NT患者均进行多导睡眠监测和多次睡眠潜伏期实验,记录平均睡眠潜伏期时间和始发快速眼动期睡眠(SOREMP)次数及N1期、N2期、N3期睡眠占比等相关参数。所有受试者的DTI图像使用DSI-Studio软件处理并计算双侧DTI-ALPS指数。比较不同组间受试者临床资料,采用单因素方差分析不同组间的双侧DTI-ALPS指数的差异,采用受试者操作特征(ROC)曲线评估双侧DTI-ALSP指数区分NT1和NT2患者的诊断价值。为控制年龄和性别的影响,采用偏相关性分析NT患者双侧DTI-ALPS指数与临床参数的相关性。结果:NT1组的ESS评分、PSQI评分显著高于NT2组和HC组(P<0.05),NT1组双侧DTI-ALPS指数(左:1.412±0.137;右:1.398±0.152)显著低于NT2组(左:1.608±0.106;右:1.586±0.067)和HC组(左:1.632±0.159;右:1.660±0.181)(P<0.001)。NT患者DTI-ALPS指数与N2期、N3期占比呈正相关(P<0.05),与ESS评分、N1期占比、SOREMP次数呈负相关(P<0.05)。双侧DTI-ALPS指数对区分NT1和NT2患者具有较好的诊断效能,临界值分别为1.528、1.524,AUC分别为0.899、0.839。结论:NT患者存在类淋巴系统功能障碍,且NT1患者更为严重,NT患者类淋巴系统功能障碍与其睡眠结构紊乱有关。DTI-ALPS指数区分不同亚型NT患者具有较好的诊断效能。 展开更多
关键词 发作性睡病 类淋巴系统 血管周围间隙 磁共振成像 扩散张量成像
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