233 research outputs found

    A RECENT UPDATE ON HISTOGENESIS OF ADENOMATOID ODONTOGENIC TUMOR: A REVIEW

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    Adenomatoid odontogenic tumor (AOT) is a relatively rare benign, epithelial tumor of odontogenic origin. There is varying class of thoughts contemplating this lesion to be a hamartoma or neoplastic growth of odontogenic epithelium. Controversy regarding the histogenesis of the lesion is plentiful in earlier literature. The recent advent of immunohistochemical and ultrastructural studies has aided in throwing light on the tissue of origin of this tumor. This review aims at understanding the evolving concepts of histogenesis of AOT to better understand the biological behavior of the lesion. The review of AOT was carried out using PubMed and Google Scholar databases and 39 articles from the year 2001 to 2016 which contributed to the histogenesis of AOT were included for review. Since the origin of the cystic lining is similar to a reduced enamel epithelium and not the dental lamina, we propose the former to be the progenitor of AOT. Furthermore, we consider extra-follicular, as well as peripheral AOTs, originate from the remnants of Hertwig’s epithelial root sheath (epithelial rests of Malassez), which complies with the common histology for all these variants

    Solving systems of nonlinear equations by harmony search

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    In this paper, we aim to analyze the performance of some variants of the harmony search (HS) metaheuristic when solving systems of nonlinear equations through the global optimization of an appropriate merit function. The HS metaheuristic draws its inspiration from an artistic process, the improvisation process of musicians seeking a wonderful harmony. A new differential best HS algorithm, based on an improvisation operator that mimics the best harmony and uses a differential variation, is proposed. Computational experiments involving a well-known set of small-dimensional problems are presented.Fundação para a Ciência e a Tecnologia (FCT

    Nonmonotone hybrid tabu search for Inequalities and equalities: an experimental study

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    The main goal of this paper is to analyze the behavior of nonmonotone hybrid tabu search approaches when solving systems of nonlinear inequalities and equalities through the global optimization of an appropriate merit function. The algorithm combines global and local searches and uses a nonmonotone reduction of the merit function to choose the local search. Relaxing the condition aims to call the local search more often and reduces the overall computational effort. Two variants of a perturbed pattern search method are implemented as local search. An experimental study involving a variety of problems available in the literature is presented.Fundação para a Ciência e a Tecnologia (FCT

    Combined mutation differential evolution to solve systems of nonlinear equations

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    This paper presents a differential evolution heuristic to compute a solution of a system of nonlinear equations through the global optimization of an appropriate merit function. Three different mutation strategies are combined to generate mutant points. Preliminary numerical results show the effectiveness of the presented heuristic.Fundação para a Ciência e a Tecnologia (FCT

    Solving nonlinear equations by a tabu search strategy

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    Solving systems of nonlinear equations is a problem of particular importance since they emerge through the mathematical modeling of real problems that arise naturally in many branches of engineering and in the physical sciences. The problem can be naturally reformulated as a global optimization problem. In this paper, we show that a metaheuristic, called Directed Tabu Search (DTS) [16], is able to converge to the solutions of a set of problems for which the fsolve function of MATLAB® failed to converge. We also show the effect of the dimension of the problem in the performance of the DTS.Fundação para a Ciência e a Tecnologia (FCT

    Solving systems of inequalities and equalities by a nonmonotone hybrid tabu search method

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    Series : AIP Conference Proceedings, Vol. 1479This paper presents a derivative-free nonmonotone hybrid tabu search to compute a solution of overdetermined systems of inequalities and equalities through the global optimization of an appropriate merit function. The proposed algorithm combines global and local searches aiming to reduce computational effort. Preliminary numerical results show the effectiveness of the combined heuristic.Fundação para a Ciência e a Tecnologia (FCT

    On metaheuristics for solving the parameter estimation problem in dynamic systems: A comparative study

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    This paper presents an experimental study that aims to compare the practical performance of well-known metaheuristics for solving the parameter estimation problem in a dynamic systems context. The metaheuristics produce good quality approximations to the global solution of a finite small-dimensional nonlinear programming problem that emerges from the application of the sequential numerical direct method to the parameter estimation problem. Using statistical hypotheses testing, significant differences in the performance of the metaheuristics, in terms of the average objective function values and average CPU time, are determined. Furthermore, the best obtained solutions are graphically compared in relative terms by means of the performance profiles. The numerical comparisons with other results in the literature show that the tested metaheuristics are effective in achieving good quality solutions with a reduced computational effort.The authors would like to acknowledge the financial support of CIDEM, R&D Unit, funded by the Portuguese Foundation for the Development of Science and Technology (FCT), Ministry of Science, Technology and Higher Education, under the Project UID/EMS/0615/2016, and of COMPETE: POCI-01-0145-FEDER-007043 and FCT within the Projects UID/CEC/00319/2013 and UID/MAT/00013/2013.info:eu-repo/semantics/publishedVersio

    Combining global tabu search with local search for solving systems of equalities and inequalities

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    This papers aims at providing a combined strategy for solving systems of equalities and inequalities. The combined strategy uses two types of steps: a global search step and a local search step. The global step relies on a tabu search heuristic and the local step uses a deterministic search known as Hooke and Jeeves. The choice of step, at each iteration, is based on the level of reduction of the l2-norm of the error function observed in the equivalent system of equations, compared with the previous iterationFundação para a Ciência e a Tecnologia (FCT

    Importance of Sanskrit language in learning Ayurveda

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    Textual knowledge and practical knowledge is inevitable to learn and practice any scientific subjects. To master the text, one must master the language in which the original text has been written. The science of Ayurveda has written in Sanskrit. Sanskrit is a language which has a scientifically structured grammar. By adding the prefixes and suffixes, it gives varied meaning to a single word. So, one has to learn it perfectly while handling that language. Even the same root can express different meanings as they are listed under different groups which undergo various grammatical processes. The knowledge in the learning tools used is very important in learning the scientific scripts written in Sanskri

    Finding multiple roots of systems of nonlinear equations by a hybrid harmony search-based multistart method

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    A multistart (MS) clustering technique to compute multiple roots of a system of nonlinear equations through the global optimization of an appropriate merit function is presented. The search procedure that is invoked to converge to a root, starting from a randomly generated point inside the search space, is a new variant of the harmony search (HS) metaheuristic. The HS draws its inspiration from an artistic process, the improvisation process of musicians seeking a wonderful harmony. The new hybrid HS algorithm is based on an improvisation operator that mimics the best harmony and uses the idea of a differential variation, borrowed from the differential evolution algorithm. Computational experiments involving a benchmark set of small and large dimensional problems with multiple roots are presented. The results show that the proposed hybrid HS-based MS algorithm is effective in locating multiple roots and competitive when compared with other metaheuristics.FCT - Fuel Cell Technologies Program(UID/EMS/0615/2016). The authors are grateful to the anonymous referees for their helpful suggestions to improve the paper. This research has been supported by CIDEM (Centre for Research & Development in Mechanical Engineering, Portugal), by COMPETE POCI-01-0145-FEDER-007043 and FCT (Foundation for Science and Technology, Portugal) within the projects UID/EMS/0615/2016 and UID/CEC/00319/2013
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