球面中具有半平行和二阶平行Moebius第二基本形式的超曲面     

钟定兴 《赣南师范学院学报》2006,27(3):21-25

给出了单位球面上具有半平行和二阶平行Moebius第二基本形式的超曲面的分类,并且证明了如果Moebius第二基本形式是平行的,那么Blaschke张量也是平行的.  相似文献   

Inter-Parietal White Matter Development Predicts Numerical Performance in Young Children     

Cantlon JF  Davis SW  Libertus ME  Kahane J  Brannon EM  Pelphrey KA 《Learning and individual differences》2011,21(6):672-680

In an effort to understand the role of interhemispheric transfer in numerical development, we investigated the relationship between children's developing knowledge of numbers and the integrity of their white matter connections between the cerebral hemispheres (the corpus callosum). We used diffusion tensor imaging (DTI) tractography analyses to test the link between the development of the corpus callosum and performance on symbolic and non-symbolic numerical judgment tasks. We were especially interested in the interhemispheric connections of parietal cortex in 6-year-old children, because regions of parietal cortex have been implicated in the development of numerical skills by several prior studies. Our results revealed significant structural differences between children and adults in the fibers of the corpus callosum connecting the left and right parietal lobes. Importantly, these structural differences were predictive of individual differences among children in performance on numerical judgment tasks: children with poor numerical performance relative to their peers exhibited reduced white matter coherence in the fibers passing through the isthmus of the corpus callosum, which connects the parietal hemispheres.  相似文献   

环面的一些几何性质的研究     

杨晨响  梅雪峰 《浙江教育学院学报》2011,(3):70-78

运用定义及已知公式,讨论了环面的基本形式,通过初等计算,得到了环面的Gauss曲率、测地曲率及R iemann曲率张量.  相似文献   

模的广义局部化及其性质     

苏业芹  王秋丽 《商丘师范学院学报》2013,(9):22-24

在给出交换模的广义局部化定义及部分性质的基础之上，在张量积上研究了相关性质，并证明了张量积关于广义局部化的泛性质。  相似文献   

E-characteristic polynomials of real rectangular tensor     

吴伟  陈肖肖 《天津大学学报(英文版)》2014,20(3):232-235

By the resultant theory, the E-characteristic polynomial of a real rectangular tensor is defined. It is proved that an E-singular value of a real rectangular tensor is always a root of the E-characteristic polynomial. The definition of the regularity of square tensors is generalized to the rectangular tensors, and in the regular case, a root of the E-characteristic polynomial of a special rectangular tensor is an E-singular value of the rectangular tensor. Moreover, the best rank-one approximation of a real partially symmetric rectangular tensor is investigated.  相似文献   

Combining fiber dissection,plastination, and tractography for neuroanatomical education: Revealing the cerebellar nuclei and their white matter connections          下载免费PDF全文

Hisse Arnts  Michiel Kleinnijenhuis  Jan G.M. Kooloos  Annelieke N. Schepens‐Franke  Anne‐Marie van Cappellen van Walsum 《Anatomical sciences education》2014,7(1):47-55

In recent years, there has been a growing interest in white matter anatomy of the human brain. With advances in brain imaging techniques, the significance of white matter integrity for brain function has been demonstrated in various neurological and psychiatric disorders. As the demand for interpretation of clinical and imaging data on white matter increases, the needs for white matter anatomy education are changing. Because cross‐sectional images and formalin‐fixed brain specimens are often insufficient in visualizing the complexity of three‐dimensional (3D) white matter anatomy, obtaining a comprehensible conception of fiber tract morphology can be difficult. Fiber dissection is a technique that allows isolation of whole fiber pathways, revealing 3D structural and functional relationships of white matter in the human brain. In this study, we describe the use of fiber dissection in combination with plastination to obtain durable and easy to use 3D white matter specimens that do not require special care or conditions. The specimens can be used as a tool in teaching white matter anatomy and structural connectivity. We included four human brains and show a series of white matter specimens of both cerebrum and cerebellum focusing on the cerebellar nuclei and associated white matter tracts, as these are especially difficult to visualize in two‐dimensional specimens and demonstrate preservation of detailed human anatomy. Finally, we describe how the integration of white matter specimens with radiological information of new brain imaging techniques such as diffusion tensor imaging tractography can be used in teaching modern neuroanatomy with emphasis on structural connectivity. Anat Sci Educ. 7: 47–55. © 2013 American Association of Anatomists.  相似文献   

Projectively flat exponential Finsler metric     

YU Yao-yong YOU Ying 《浙江大学学报(A卷英文版)》2006,7(6):1068-1076

INTRODUCTION One century ago, Hilbert announced his famous 23 problems. The Hilbert’s Fourth Problem is to characterize the (not-necessarily-reversible) distance functions on an open subset in ún such that straight lines are shortest paths. Distance functions induced by a Finsler metric are regarded as smooth ones. Thus Hilbert’s Fourth Problem in the smooth case is to characterize Finsler metric on an open subset in ún whose geodesics are straight lines. Finsler metric on an ope…  相似文献   

关于电介质的教学     

李江芬 《石家庄学院学报》2004,6(6):1-3

根据物质的电极化特性将电介质分类,澄清了电磁学教学中电介质用语的不规范现象.  相似文献   

Projectively flat Asanov Finsler metric     

HAN Jing-wei YU Yao-yong 《浙江大学学报(A卷英文版)》2007,8(6):963-968

In this work, we study the Asanov Finsler metric F=α(β2/α2 gβ/α 1)1/2exp{(G/2)arctan[β/(hα) G/2]}, where α=(αijyiyj)1/2 is a Riemannian metric and β=biyj is a 1-form, g∈(-2,2), h=(1-g2/4)1/2, G=g/h. We give the necessary and sufficient condition for Asanov metric to be locally projectively flat, i.e., α is projectively flat and β is parallel with respect to α. Moreover, we proved that the Douglas tensor of Asanov Finsler metric vanishes if and only if β is parallel with respect to α.  相似文献   

刚体动能的一种计算方法   总被引：1，自引：0，他引：1  

郭茂政 《商丘师范学院学报》2003,19(5):23-25

根据克尼希定理和刚体转动的有关理论，导出了由关于质心对称的任两对称点的速度来计算刚体动能的一种算式。并用两个算例说明了该式的优越性。  相似文献