三维K-空间Kz轴数据不对称填充技术在3D-TOF脑动脉MRA的应用价值

目的 探讨 3DK 空间Kz轴数据不对称填充方法在 3DTOF脑动脉MRA的应用价值。方法 40例患者行Kz轴K 空间数据不对称填充的 3DTOF脑动脉MRA (TurboMRA)及Kz轴K 空间数据对称填充的 3DTOF脑动脉MRA(常规MRA) ,在 3D源图像和MIP图像上比较二种方法的影像质量、成像时间及显示血管的能力。结果 Kz轴不对称K 空间填充3DTOF脑动脉MRA与Kz轴对称K 空间填充 3DTOF脑动脉MRA相比 ,影像质量指标 (S/N、C/N、Rz)、采集时间TA、血管显示能力等均有显著性差异 (P <0 .0 1)。结论 Kz轴K 空间不对称填充 3DTOF脑动脉MRA与常规 3DTOF脑动脉MRA相比成像质量更佳 ,显示血管更多 ,节约采集时间 44 %。

K - Bounded Sets and A - Spaces

Let E and F be two vector spaces in duality with respect to the bilinear pairing 〈,〉. The weak (Mackey,strong) topology on E will be denoted by σ(E,F) (τ(E,F),β(E,F)). In this paper,we show that AE is σ(E,F) K bounded subset if and only if A is β(E,F) K bounded subset. If τ(E′,E) is a quasi barrelled space,we also give a few characterizations for (E,T) to be A space.

K-very Smooth Banach Spaces

We introduce the notion of K-very smoothness which is a generalization of very smoothness in Banach spaces. A necessary and sufficient condition for a Banach space to be K-very smooth is obtained. We also consider some relations between K-very smoothness and other geometrical notions.

The Existence of Solutions of （k, n - k） Conjugate Boundary Value Problems in Banach Spaces

In this paper, by use of the Schauder fixed-point theorem, the existence of solution of （k, n - k） Conjugate boundary value problems in Banach spaces is investigated.

Mapping Theorems on Quasi-Nagata Spaces

In this paper, we discuss the relationship between k-semi-stratifiable spaces and quais-Nagata spaces and some mapping properties of quasi-Nagata spaces. We get following results: sequence-covering closed mapping preserve quasi-Nagata spaces, and finite-to-one open mappings don't preserve quasi-Nagata spaces.

The Degree Theory of a New Operator

This paper defines a concept of a semi k set contract operator and establishes a degree theory for it.

Asymptotic Excisions of Metric Spaces and Ideals of Asymptotic Coarse Roe Algebras

We introduce in this note the notions of asymptotic excision of proper metric spaces and asymptotic equivalence relation for subspaces of metric spaces, which are relevant in characterizing spatial ideals of the asymptotic coarse Roe algebras. We show that the lattice of the asymptotic equivalence classes of the subspaces of a proper metric space is isomorphic to the lattice of the spatial ideals of the asymptotic Roe algebra. For asymptotic excisions of the metric space, we also establish a MayeroVietoris sequence in K-theory of the asymptotic coarse Roe algebras.

Interpolated Tensor Products of Exponential Type Vectors of Unbounded Operators

In this paper we define the tensor products of spaces of exponential type vectors of closed unbounded operators in Banach spaces. Using the real method of interpolation （K-functional） we prove the interpolation theorems that permit to characterize of tensor products of spaces of exponential type vectors, We show an application of abstract results to the theory of regular elliptic operators on bounded domains. For such operators the exponential type vectors are root vectors. Thus we describe the tensor products of root vectors of regular elliptic operators on bounded domains.

On K-groups of Operator Algebra on the 1-shift Space

In this paper we discuss the K-groups of Wiener algebra ;W. For the 1-shift space XGM2,We obtain a characterization of Fredholm operators on X^nGM2 for all n ∈ N. We also calculate the K-groups of operator algebra on the 1-shift space XGM2.

AVERAGE σ-K WIDTH OF CLASS OF L_p(R^n) IN L_q (R^n)

The average σ-K width of the Sobolev-Wiener class in Lq(Rn) is studied for and the asymptotic behaviour of this quantity is determined. The exact value of average σ-K width of some class of smooth functions in L2(Rn) is obtained.

Positivity of Fock Toeplitz Operators via the Berezin Transform

Abstract This paper deals with the relationship between the positivity of the Fock Toeplitz operators and their Berezin transforms. The author considers the special case of the bounded radial function φ（z）=α ＋ be-α｜z｜2 ＋ ce-β｜z｜2, where a, b, c are real numbers and α,β are positive numbers. For this type of φ, one can choose these parameters such that the Berezin transform of is a nonnegative function on the complex plane, but the corresponding Toeplitz operator Tφ is not positive on the Fock space.

RRS-PBC: a molecular approach for periodic systems

Technically, when dealing with a perfect crystal, methods （PBC） in conjunction with plane-wave basis sets are widely in k-（reciprocal） space that impose periodic boundary conditions used. Chemists, however, tend to think of a solid as a giant mole- cule, which offers a molecular way to describe a solid by using a finite cluster model （FCM）. However, FCM may fail to sim- ulate a perfect crystal due to its inevitable boundary effects. We propose an RRS-PBC method that extracts the k-space infor- mation of a perfect crystalline solid out of a reduced real space （RRS） of an FCM. We show that the inevitable boundary effects in an FCM are eliminated naturally to achieve converged high-quality band structures.