نتایج جستجو برای: conformal

تعداد نتایج: 22314  

Journal: :iranian journal of radiation research 0
s.a. vaezzadeh department of medical physics and biomedical engineering, tehran university of medical sciences, tehran, iran m. allahverdi department of medical physics and biomedical engineering, tehran university of medical sciences, tehran, iran h.a. nedaie department of radiotherapy – oncology, tehran university of medical sciences, tehran, iran m. aghili department of radiotherapy – oncology, tehran university of medical sciences, tehran, iran m. esfehani department of radiotherapy – oncology, tehran university of medical sciences, tehran, iran

background: to evaluate the dosimetric difference between conventional and three-dimensional conformal radiotherapy (3d-crt) using 6 and 18 mv x-ray photons. materials and methods: computed tomography scans of 26 pelvic patients were acquired and transferred to the 3d treatment planning system. for each patient, 8 conventional plans (3, 4, 5 and 6 fields) and one 3d-crt plan were prepared using...

2008
R. Langevin

We give a new proof of the conformal invariance of the writhe of a knot from a conformal geometric vewpoint.

2006
Miao Jin Juhno Kim Feng Luo Seungyong Lee Xianfeng Gu

Surface parameterization is a fundamental problem in graphics. Conformal surface parameterization is equivalent to finding a Riemannian metric on the surface, such that the metric is conformal to the original metric and induces zero Gaussian curvature for all interior points. Ricci flow is a theoretic tool to compute such a conformal flat metric. This paper introduces an efficient and versatile...

1991
N. Read

It is argued that fractional quantum Hall effect wavefunctions can be interpreted as conformal blocks of two-dimensional conformal field theory. Fractional statistics can be extended to nonabelian statistics and examples can be constructed from conformal field theory. The Pfaffian state is related to the 2D Ising model and possesses fractionally charged excitations which are predicted to obey n...

2008
A. Wehner

We consider an involutive automorphism of the conformal algebra and the resulting symmetric space. We display a new action of the conformal group which gives rise to this space. The space has an intrinsic symplectic structure, a group-invariant metric and connection, and serves as the model space for a new conformal gauge theory. ∗Electronic-mail: [email protected]

2008
Christian Lübbe

In this article we describe the formulation of null geodesics as null conformal geodesics and their description in the tractor formalism. A conformal extension theorem through an isotropic singularity is proven by requiring the boundedness of the tractor curvature and its derivatives to sufficient order along a congruence of null conformal geodesic. This article extends earlier work by Tod and ...

1999
Kiyoshi Hayasaka Ryuichi Nakayama

It is shown that the effective theory of D-particles has conformal symmetry with field-dependent parameters. This is a consequence of the supersymmetry. The string coupling constant is not transformed in contrast with the recent proposal of generalized conformal symmtery by Jevicki et al.[5][6] This conformal symmetry can also be generalized to other Dp-brane systems. [email protected]...

2008
Victor Kac Michael Lau

We introduce the formalism of differential conformal superalgebras, which we show leads to the “correct” automorphism group functor and accompanying descent theory in the conformal setting. As an application, we classify forms of N = 2 and N = 4 conformal superalgebras by means of Galois cohomology.

2008
Helmut Friedrich

We discuss properties of conformal geodesics on general, vacuum, and warped product space-times and derive a system of conformal deviation equations. The results are used to show how to construct on the Schwarzschild-Kruskal space-time global conformal Gauss coordinates which extends smoothly and without degeneracy to future and past null infinity.

1995
Shahn Majid

We show that the action of the special conformal transformations of the usual (undeformed) conformal group is the q → 1 scaling limit of the braided adjoint action or R-commutator of q-Minkowski space on itself. We also describe the qdeformed conformal algebra in R-matrix form and its quasi-∗ structure.

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