Search results for "racket"
showing 10 items of 132 documents
Influence of delay between dental bleaching with 35% hydrogen peroxide and orthodontic brackets on the bond strength at the enamel/adhesive interface
2019
Background The aim of this study was to evaluate the influence of waiting time between the bleaching with 35% hydrogen peroxide and orthodontic brackets bonding on shear bond strength (SBS) in enamel. Material and Methods Eighty bovine teeth were randomly divided into four groups (G): G1(negative control) and G2, G3 and G4 (experimental groups). The experimental groups were submitted to bleaching. Prior to orthodontic brackets bonding to enamel the procedure was adopted different waiting times, as follows: G2 (1 day); G3 (7 days) and G4 (14 days). It was performed enamel etching (30s), washing water (30s), application of adhesive system followed by photoactivation (20s). A thin layer of com…
Nambu structures and super-theorem of Amitsur-Levitzki
2004
In this thesis, we establish new polynomial identities in a non commutative combinatorial framework. In the first part, we present new Nambu-Lie structures by classifying all (n-1)-structures in \R^n and we give a method for defining all-order brackets in Lie algebras. We are able to quantify one of our structures, thanks to standard polynomials and even Clifford algebras. In the second part of our work, we generalize the notion of standard polynomials to graded algebras, and we prove an Amitsur-Levitzki type theorem for the Lie superalgebras \osp(1,2n) inspired by Kostant's cohomological interpretation of the classical theorem. We give super versions of properties and results needed in Kos…
The tennis racket effect in a three-dimensional rigid body
2017
We propose a complete theoretical description of the tennis racket effect, which occurs in the free rotation of a three-dimensional rigid body. This effect is characterized by a flip ($\pi$- rotation) of the head of the racket when a full ($2\pi$) rotation around the unstable inertia axis is considered. We describe the asymptotics of the phenomenon and conclude about the robustness of this effect with respect to the values of the moments of inertia and the initial conditions of the dynamics. This shows the generality of this geometric property which can be found in a variety of rigid bodies. A simple analytical formula is derived to estimate the twisting effect in the general case. Differen…
New applications of graded Lie algebras to Lie algebras, generalized Lie algebras and cohomology
2007
We give new applications of graded Lie algebras to: identities of standard polynomials, deformation theory of quadratic Lie algebras, cyclic cohomology of quadratic Lie algebras, $2k$-Lie algebras, generalized Poisson brackets and so on.
Integrable Systems and Factorization Problems
2002
The present lectures were prepared for the Faro International Summer School on Factorization and Integrable Systems in September 2000. They were intended for participants with the background in Analysis and Operator Theory but without special knowledge of Geometry and Lie Groups. In order to make the main ideas reasonably clear, I tried to use only matrix algebras such as $\frak{gl}(n)$ and its natural subalgebras; Lie groups used are either GL(n) and its subgroups, or loop groups consisting of matrix-valued functions on the circle (possibly admitting an extension to parts of the Riemann sphere). I hope this makes the environment sufficiently easy to live in for an analyst. The main goal is…
Minority Integration in a Western City: An Agent-Based Modelling Approach
2019
This chapter describes the design and construction of an agent-based model we refer to as the ‘Simulation of Extended Time Integration’ (SETI) model. This model was designed with the goal of obtaining a better understanding of the conditions and mechanisms leading to the structural, social, and cultural integration of minorities into large Western societies. SETI is a virtual society with structural (employment, income, education) and demographic (marriage, reproduction, life expectancy) variables typical of Westerns countries. Initialization occurs after a hypothesized immigration event in which a single minority population settles into the majority population, bracketing the first decade …
Overview of ghost correction for HDR video stream generation
2015
International audience; Most digital cameras use low dynamic range image sensors, these LDR sensors can capture only a limited luminance dynamic range of the scene[1], to about two orders of magnitude (about 256 to 1024 levels). However, the dynamic range of real-world scenes varies over several orders of magnitude (10.000 levels). To overcome this limitation, several methods exist for creating high dynamic range (HDR) image (expensive method uses dedicated HDR image sensor and low-cost solutions using a conventional LDR image sensor). Large number of low-cost solutions applies a temporal exposure bracketing. The HDR image may be constructed with a HDR standard method (an additional step ca…
Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin
2013
Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental blea - ching under orthodontic bracket. Material and methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths…
Gli obiettivi e i risultati della ricerca
2008
Il testo presenta il programma di ricerca intrapreso dalla Fondazione Rocco Chinnici e coordinato da A. La Spina, il cui primo risultato è il volume I costi dell'illegalità - Mafia ed estorsioni in Sicilia. La cultura dell’illegalità, molto diffusa nel Mezzogiorno, rappresenta uno dei più rilevanti ostacoli allo sviluppo economico e sociale di tale area. La gran parte delle stime quantitative, che pure esistono, lasciano a desiderare quanto a coerenza, controllabilità e attendibilità del percorso seguito per la loro formulazione (come viene illustrato nel testo). È necessario individuare con precisione e con cautele maggiori di quanto non sia stato fatto in passato, e attraverso percorsi me…