Motivated by the descent equation in string theory, we give a new interpretation for the action of the symmetry charges on the BRST cohomology in terms of what we call the Gerstenhaber bracket. This bracket is compatible with the graded commutative product in cohomology, and hence gives rise to a new class of examples of what mathematicians call a Gerstenhaber algebra. The latter structure was ...

To solve the trouble of cervical vertebra disease caused by long working hours, this work is aimed at designing an active monitor stand to achieve best dynamic trajectory planning. The operation system consists image input, face positioning, and robotic arm. According user’s inverse kinematics method used calculate steering angle in each direction, height are adjusted make corresponding selecti...

The aim of this study was to compare frictional resistance among conventional, passive and active selfligating brackets using Finite Elements Analysis (FEA). Seventynine (79) slide tests were performed by combining an upper first bicuspid conventional bracket, 0.018" stainless steel wires and 0.010" ligature by means of an INSTRON 3345 load system to obtain average maximum static frictional res...

OBJECTIVE This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. METHODS Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxil...

This paper is a consequence of the close connection between combinatorial group theory and the topology of surfaces. In the eighties Goldman discovered a Lie algebra structure on the vector space generated by the free homotopy classes of oriented curves on an oriented surface. The Lie bracket [a,b] is defined as the sum over the intersection points of a pair of transversal representatives of th...

The purpose of this research was to investigate the torque capacity of active and passive self-ligating brackets compared with metallic, ceramic, and polycarbonate edgewise brackets. Six types of orthodontic brackets were included in the study: the self-ligating Speed and Damon2, the stainless steel (SS), Ultratrimm and Discovery, the ceramic bracket, Fascination 2, and the polycarbonate bracke...

OBJECTIVE To examine the influence of third-order torque on kinetic friction in sliding mechanics involving active and passive self-ligating brackets. MATERIALS AND METHODS Wire-slot frictional forces were quantified and compared across five sets of brackets and tubes within a simulated posterior dental segment with -15 degrees , -10 degrees , -5 degrees , 0 degrees , +5 degrees , +10 degrees...

The aim of this research was to investigate the retention of a bracket equipped with a novel base, the R-system. The design of the bracket base is characterized by concentric grooves. The behaviour of this bracket was compared with a bracket with a conventional mesh base from the same manufacturer. Thirty lower adult bovine incisors were selected and metallic brackets were bonded using the Conc...

introduction: this study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with erbium-doped yttrium aluminum garnet (er:yag) laser or sandblasting. methods: twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. debonded brackets were randomly divided into 2 groups of 14. one group...