we classify the paracontact riemannian manifolds that their rieman-nian curvature satisfies in the certain condition and we show that thisclassification is hold for the special cases semi-symmetric and locally sym-metric spaces. finally we study paracontact riemannian manifolds satis-fying r(x, ξ).s = 0, where s is the ricci tensor.

Let K be a convex body in R, i.e. a compact convex set with a non-empty interior. We say that K is origin-symmetric if K = −K. The presence of origin-symmetry is an essential assumption in various problems. Many results that hold for origin-symmetric convex bodies fail in the absence of the symmetry condition. For example, origin-symmetric convex bodies are uniquely determined by the volumes of...

Let X be a complex manifold, π:E→X locally trivial holomorphic fibration with fiber F, and (g,〈•,•〉) Lie algebra an invariant symmetric form. We associate to this data prefactorization Fg,π on in the formalism of Costello-Gwilliam. When X=C, g is simple, F smooth affine variety, we extract from vertex which vacuum module for universal central extension g⊗H0(F,O)[z,z−1]. As special case, when al...

background: proper placement of central venous catheter (cvc) tip could reduce early and late catheter-related complications.although the live fluoroscopy is standard of care for placement of the catheter, it is not available in many centers. therefore, the present study evaluated the sensitivity and specificity of bedside chest x-ray (cxr) for proper positioning of the catheter tip. materials ...

In this paper, some properties of $alpha$-skew Armendariz and central Armendariz rings have been studied by variety of others. We generalize the notions to central $alpha$-skew Armendariz rings and investigate their properties. Also, we show that if $alpha(e)=e$ for each idempotent $e^{2}=e in R$ and $R$ is $alpha$-skew Armendariz, then $R$ is abelian. Moreover, if $R$ is central $alpha$-skew A...

A quasigroup (Q, ∗) is called totally anti-symmetric if (c ∗ x) ∗ y = (c ∗ y) ∗ x⇒ x = y and x∗y = y∗x⇒ x = y. A totally anti-symmetric quasigroup can be used for the definition of a check digit system. Ecker and Poch [9] conjectured that there are no totally anti-symmetric quasigroups of order 4k + 2. This article will completely disprove their conjecture (except for n = 2, 6) as we will give ...

The use of electrostatic forces to provide actuation is a method of central importance in microelectromechanical system (MEMS) and in nanoelectromechanical systems (NEMS). Here, we study the electrostatic deflection of an annular elastic membrane. We investigate the exact number of positive radial solutions and non-radially symmetric bifurcation for the model −∆u = λ (1− u)2 in Ω, u = 0 on ∂Ω, ...

the non-commuting graph $nabla(g)$ of a non-abelian group $g$ is defined as follows: its vertex set is $g-z(g)$ and two distinct vertices $x$ and $y$ are joined by an edge if and only if the commutator of $x$ and $y$ is not the identity. in this paper we 'll prove that if $g$ is a finite group with $nabla(g)congnabla(bs_{n})$, then $g cong bs_{n}$, where $bs_{n}$ is the symmetric group of degre...

We present CHANDRA observations of the X-ray luminous, distant galaxy cluster RBS797 at z = 0.35. In the central region the X-ray emission shows two pronounced X-ray minima, which are located opposite to each other with respect to the cluster centre. These depressions suggest an interaction between the central radio galaxy and the intra-cluster medium, which would be the first detection in such...

We construct linear operators factorizing the three bases of symmetric polynomials: monomial symmetric functions mλ(x), elementary symmetric polynomials Eλ(x), and Schur functions sλ(x), into products of univariate polynomials.