Osserman manifolds are a generalization of locally two-point homogeneous spaces. We introduce k-root in which the reduced Jacobi operator has exactly k eigenvalues. investigate one-root and two-root as another prove that there is no Riemannian manifold odd dimension. In twice an dimension, we describe all algebraic curvature tensors give additional conditions for manifolds.

BACKGROUND The transposition of the great arteries (TGA) is one of the most severe congenital heart diseases. The arterial switch operation (ASO) is the preferred procedure to treat TGA. Although numerous reports have shown good results after ASOs, some patients suffer from circulatory system problems following the procedure. One reason for problems post-ASO is the local changes in the curvatur...

INTRODUCTION Root canal preparation is an important process in endodontic therapy. Nickel-titanium (NiTi) rotary file system can be used in single length technique (simultaneous technique) without early coronal enlargement, as well as in crown-down method. The purpose of this in vitro study was to compare single length with crown-down methods' shaping ability using Mtwo NiTi files. MATERIALS ...

There are no quantitative data on the mechanical efficacy of irrigation in the removal of bacteria from curved canals. This study quantitatively analyzed the effects of root canal curvature and preparation size on the mechanical efficacy of irrigation using 33 mandibular single-rooted bicuspids allocated to groups according to root canal curvatures, group 1 (straight) 4 to 8 degrees, group 2 (i...

AIMS This study aimed to compare the frequency of ProTaper rotary instrument fracture with rotary (conventional) and hybrid (rotary and hand files) canal preparation techniques. Secondary objectives were to determine whether there was an association of ProTaper file fracture with the canal curvature and to compare the mean time required for canal preparation in the two techniques. METHODS An ...

Root canal shaping is of utmost importance in the success of root canal treatment. Numbers of systems available are effective for shaping; accounting from stainless steel hand files to nickel-titanium rotary files to the new single file system concept. Single file technique is developed for shaping vast majority of canals, regardless of their length, diameter or curvature. Therefore, single use...

Background The arterial Switch operation (ASO) is now performed routinely for the repair of transposition of the great arteries (TGA). Neo-aortic root dilatation and reduced elasticity of the ascending aorta have been shown to impact the long-term outcomes of these patients. The aim of this study was to assess the effect of the ASO with the Lecompte maneuver on the dynamic behavior and dimensio...

OBJECTIVE To evaluate the effect of number of uses, angle and radius of curvature and type of instrument on the fracture of ProTaper rotary instruments when used by undergraduate students. STUDY DESIGN Three hundred and seventy-six molars, with a total of 1114 root canals, extracted were instrumented by undergraduate students using ProTaper instruments according to the manufacturer´s recommen...

Some characteristics of the gravity sensing mechanism in maize root caps were investigated using a bioelectric current as an indicator of gravity sensing. This technique involves the measurement of a change in the current density which arises at the columella region coincidently with the presentation time. Two inhibitors of auxin transport, triiodobenzoic acid and naphthylphthalamic acid, blo...

The purpose of this investigation was to compare centring ratio of ProTaper and Mtwo rotary systems. 60 mandibular molar teeth which had 25, 30 and 35 degree curvature in mesio-buccal root canal were used. Group 1 had 25°, Group 2 had 30°, and Group 3 had 35° curvatures. The roots were sectioned horizontally at 2 mm away from the apex. The apical region was then observed under a stereo-microsco...